Pt-based Diesel Oxidation Catalysts: Oxidation state of Platinum and the origin of CO

oscillations in real Pt/Al2O3 catalysts

Andreas Gänzler1, Alexey Boubnov

1, Maria Casapu

1, Henning Lichtenberg

1, Jan-Dierk

Grunwaldt1*

1Institute for Chemical Technology and Polymer Chemistry (ITCP) and Institute of Catalysis Research and

Technology (IKFT), KIT, Kaiserstr. 12, 76131 Karlsruhe, Germany, grunwaldt@kit.edu

Diesel engines are more efficient than conventional gasoline engines, however, diesel exhaust

gas aftertreatment represents a significantly more challenging task: The abatement system

needs to oxidize CO and unburned hydrocarbons, but also to reduce NOx in a net oxidizing

atmosphere. Therefore multi-component systems are used with Pt or Pd based diesel oxida-

tion catalysts (DOC) as first stage with CO oxidation as major task. However, even though

studied for decades, the noble metal catalyzed reaction is not yet fully understood, especially

with respect to more applied conditions. In this regard, the occurrence of CO conversion os-

cillations in such catalysts is controversially debated (cf. [1-3] and refs. therein). Here, we

demonstrate for the first time how a combination of spatially resolved catalytic reactivity

studies and structural analysis can provide new insight into Pt-based DOC catalysts during

CO-oxidation and its oscillating conditions by extending our previous studies [3].

Our approach is based on a combination of spatially resolved X-ray absorption spectroscopy

at the Pt L3-edge with IR-thermography and net catalytic performance measurements at the

end of the catalyst bed. Results obtained from IR-thermography at one specific temperature

are shown in Figure 1. Along with oscillations in temperature (1.5-2 K) also changes in the

oxidation state of Pt were observed at the same location in the catalyst bed.

Fig. 1: Thermography images during oscillatory CO oxidation: (a) temperature hot-spots visualized by difference imaging, (b) temperature in the middle of the catalyst bed.

By this novel approach - correlating processes on a macroscopic level (temperature, catalytic

performance) with structural information on the microscopic level (oxidation state, atomic

structure) obtained from spatially resolved measurements - we can unambiguously conclude

that on Pt-based catalysts the reduced surface is more active compared to oxidized platinum,

which is in contrast to some recent studies on Pt clusters on model oxide surfaces. During a

short period of high catalytic activity the Pt particles obviously deactivate, which can be di-

rectly correlated to a transition from reduced to oxidized Pt. Subsequently the catalyst slowly

regenerates (slow increase in catalytic activity), which can be linked to the regeneration of

reduced Pt sites. The observed oscillatory behavior originates from a strong tendency of small

particles to oxidize, whereas larger platinum particles tend to remain reduced and therefore

do not show any or much less pronounced oscillatory behavior. These large particles also ex-

hibit higher turnover frequencies for CO conversion, in agreement with earlier studies [4].

[1] R. Imbihl and G. Ertl, Chem. Rev. 95, 697 (1995). [2] R. Jensen, T. Andersen, A. Nierhoff, T. Pedersen, O. Hansen, S. Dahl, I. Chorkendorff, Phys. Chem. Chem. Phys. 15, 2698 (2013).

[3] A. Boubnov, A. Gänzler, S. Conrad, M. Casapu, and J.-D. Grunwaldt, Top. Catal. 56, 333 (2013).

[4] A. Boubnov, S. Dahl, E. Johnson, A.P. Molina, S.B. Simonsen, F.M. Cano, S. Helveg, L.J. Lemus-Yegres, and J.-D. Grunwaldt, Appl. Catal. B, 126 315 (2012).

Oral 1

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conversion

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16th

Nordic Symposium on Catalysis

Ammonium formate decomposition over Au/TiO2: A highly stable catalyst with unique

selectivity against NH3 oxidation

Manasa Sridhar1, Jeroen Anton van Bokhoven

1,2, Oliver Kröcher

1,3*

1 – Paul Scherrer Institut, 5232 Villigen, Switzerland

2 – ETH Zurich, Institute for Chemical and Bioengineering, 8093 Zurich, Switzerland

3 – École Polytechnique Fédérale de Lausanne (EPFL), Institute of Chemical Sciences and Engineering, 1015

Lausanne, Switzerland

* Corresponding author’s email: oliver.kroecher@psi.ch

In the last decade, urea-SCR technology has been developed as an efficient and safe method for NOx abatement

in mobile applications [1]. However, there remains immense interest in replacing urea with alternative NH3

precursors, such as concentrated guanidinium formate, ammonium formate (AmFo) and methanamide solutions,

that are more thermally stable, freeze at lower temperatures, have higher NH3 storage capacities, and decompose

more selectively. One challenge is to identify highly active and robust dedicated hydrolysis catalysts that

selectively hydrolyze the precursors and release NH3, thus without its oxidation. Of the aforementioned

precursors, AmFo is experimentally the simplest choice to study the activity and behaviour of the hydrolysis

catalysts under actual conditions [2].

Here in, we report the unique selectivity of Au/TiO2 for converting AmFo to CO2 in the presence of excess O2

and H2O without oxidizing NH3 up to 300 ºC. Such a discriminative selectivity against NH3 oxidation is

analogous to the extraordinary selectivity of finely dispersed Au for preferential CO oxidation (PROX) in H2-

rich stream [3]. AmFo decomposition was carried out at different temperatures in the range 190 ºC- 300 ºC in a

dedicated setup [4], over 0.5 wt% Au/TiO2 anatase catalysts washcoated onto 400 cpsi cordierite monoliths. The

catalysts synthesized by a facile modified wetness impregnation method exhibited excellent activity at a

washcoat loading of only 0.5 g.L-1

amounting to weight-based pseudo-first-order rate constants greater than 12

L.g-1

.s-1

at 300 ºC. The NH3 yield remained undiminished at ~100%, while the selectivity for CO2 formation

increased from ~78% at 300 ºC to a maximum of 93% at 190 ºC.

Additionally, the fresh catalysts were subjected to two incremental hydrothermal aging steps each lasting for 5 h

at 800 °C in air containing 10% H2O, and the activity tests were repeated. Though the catalysts suffered a

reduction in the rate constants by a factor of ~3, they exhibited time on stream stabilities of greater than 48 h

showing signs of neither deactivation nor ammonia oxidation (Fig. 1).

The observations evidenced in this work, reflecting the exceptional stability and selectivity to NH3 could entail

new applications of monometallic gold in exhaust gas catalysts.

Figure 1. Time on stream plot portraying long term stability of fresh (blue) and 10 h hydrothermally aged (red)

catalysts at 190 ºC (0.5 g∙L-1

washcoat loading on the monolith, GHSV = 19,490 h-1

; feed gas: 5% H2O, 10% O2,

85% N2 and 0.05 mL∙min-1

liquid spray of 40 wt% AmFo).

References

[1] T. V Johnson, Int. J. Engine Res., 2009, 10, 275–285.

[2] O. Kröcher, M. Elsener, and E. Jacob, App. Catal. B, 2009, 88, 66–82.

[3] A. Luengnaruemitchai, S. Osuwan, and E. Gulari, Int. J. Hydrogen Energy, 2004, 29, 429–435.

[4] D. Peitz, A. M. Bernhard, M. Elsener, and O. Kröcher, Rev. Sci. Inst., 2011, 82, 084101.

0 10 20 30 40 50 60 70 80

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Oral 2

Methanol as reducing agent for lean NOx reduction over Ag-Al2O3

- influence of hydrogen and silver loading

Marika Männikkö*, Magnus Skoglundh and Hanna Härelind Competence Centre for Catalysis, Chalmers University of Technology, 412 96 Göteborg, Sweden

* marika.mannikko@chalmers.se

Lean NOx reduction over Ag/Al2O3 has been widely studied for several types of reducing agents [1]. However,

there are only a limited number of detailed reports on methanol as reductant for NOx [2]. Methanol is today one

of the most promising renewable fuels for transports both on land and at the sea. In addition, methanol is a small

molecule and thus methanol-SCR provides a model system for investigations of HC-SCR reactions in general.

The objective of the present study is to investigate the influence of hydrogen and silver loading on the activity

and selectivity for lean NOx reduction with methanol over Ag-Al2O3 catalysts. The aim is to contribute to a

fundamental understanding of methanol-SCR reactions over Ag-Al2O3.

Ag-Al2O3 samples (1-4 wt% Ag) were prepared according to a previously described sol-gel method including

freeze-drying [3]. The catalytic performance of coated monolith samples was studied in a continuous flow

reactor where the outlet gas composition was analyzed by gas-phase FTIR spectroscopy [4]. The silver species

were characterized by temperature programmed reduction with hydrogen (H2-TPR) and UV-Vis spectroscopy.

Figure 1a shows a step-response experiment where H2 is introduced and removed from the feed gas

composition. The results show that H2 is formed during methanol-SCR conditions. In accordance with Johnson

et al. [5], this availability of H2 is suggested to contribute to the high low-temperature activity often observed when using alcohols as reducing agents. Always when H2 is added to the feed in Figure 1a, more oxidized

reaction products are formed. Interestingly, only diminutive amounts of HCHO and CO are observed during

methanol oxidation, compared to during SCR conditions. Consequently their formation must be highly

influenced by the presence of NO, and maybe part of the NOx reduction reactions. Moreover, the addition of H2

results in a temperature increase in the catalyst, likely to a large extent owing to oxidation of H2 to H2O.

However, it is concluded from the methanol-SCR experiments in Figure 1b that the temperature increase alone

cannot cause the higher NOx reduction observed in the presence of H2. Comparison of the H2 consumption

during H2-TPR with the N2 formation during the experiments in Figure 1b, shows that the silver species reduced

by H2 cannot be directly associated with the N2 formation. Furthermore, the UV-Vis analysis indicates a higher

proportion of large metallic particles in the high-loaded samples, which can explain the lower N2 formation at

high temperatures, owing to a more extensive combustion of the reducing agent. In the present study we show

that H2 actually is formed during methanol-SCR conditions. This availability of hydrogen is suggested to result in a similar effect as H2 addition to HC-SCR, when not using an oxygenated reducing agent.

Figure 1. a) Step-response experiment with (3 wt% Ag) Ag-Al2O3 at 260 °C. b) Methanol-SCR during cooling

ramp, with and without H2, over Ag-Al2O3 (1-4% Ag). Inlet gas concentration (when used): 10 % O2, 1,700 ppm

methanol, 500 ppm NO, 1000 ppm H2, Ar bal.

[1] R. Burch, Catal. Rev.-Sci. Eng. 46 (2004) 271.

[2] M. Männikkö, M. Skoglundh, H. Härelind, Top. Catal. 56 (2013) 145.

[3] H. Kannisto, H.H. Ingelsten, M. Skoglundh, J. Mol. Catal. A: Chem. 302 (2009) 86.

[4] M. Männikkö, M. Skoglundh, H.H. Ingelsten, Appl. Catal. B 119-120 (2012) 256.

Oral 3

Combining HC-SCR over Ag/Al2O3 and hydrogen generation over Rh/CeO2-ZrO2 using

bio-fuels: an integrated system approach for real applications

Fredrik Gunnarsson1*, Moa Z. Granlund

2*, Mattias Englund

1, Jazaer Dawody

3, Lars J.

Pettersson2, Hanna Härelind1

1 Competence Centre for Catalysis, Dept. of Chemical and Biological Engineering, Chalmers University of

Technology, SE-412 96 Göteborg, Sweden 2

Chemical Engineering and Technology, Chemical Technology, KTH Royal Institute of Technology, SE-100 44,

Stockholm, Sweden 3

Volvo Group Trucks Technology, Advanced Technology and Research, SE-412 96 Göteborg, Sweden

* corresponding: fredrik.gunnarsson@chalmers.se, moazg@kth.se

We report on a high NOx reduction activity over Ag/Al2O3 catalysts, using hydrogen from a reformer with a

Rh/CeO2-ZrO2 catalyst. The focus of the study is to evaluate the performance of hydrocarbon selective catalytic

reduction (HC-SCR) catalyst in real conditions. Initially, the catalytic materials for fuel reformer (Rh/CeO2-ZrO2 [1])

and the HC-SCR (Ag/Al2O3 [2]) were evaluated in separate bench scale reactor setups. The two bench scale reactor

setups were subsequently combined into one reactor setup with the aim to evaluate the reformate’s influence on the

HC-SCR process in a controlled environment. The reducing agent and reforming fuel used in the combined bench

scale reactor setup was commercial biodiesel (NexBTL). The final phase of the study was to evaluate the

performance of the HC-SCR catalyst in real exhaust conditions. A pilot-scale version of the 4 wt. % Ag/Al2O3

catalyst doped with 100 ppm Pt was used together with a single cylinder genset engine (Yanmar, L100). The system

can evaluate the performance in real exhausts together with real reformate from the separate fuel reformer.

The results from the combined bench-scale reactor setup show that a significant improvement in the NOx reduction

can be achieved when using reformate hydrogen (Figure 1). The improvement is highest at low temperatures and

increase with increasing hydrogen addition. The effect decreases as the temperature is increased, with negligible

effect above 350 °C. The largest improvement is seen over the 4 wt. % Ag/Al2O3 catalyst doped with 100 ppm Pt.

The trends from the pilot-scale reactor can be seen to mimic those from the bench-scale reactor. The NOx reduction

data from the real exhaust experiments using reformate hydrogen mimic those when using bottled hydrogen. The

study gives an excellent link between evaluation of the catalytic materials, controlled bench-scale experiments and

applied engine experiments, proving a viable concept for onboard hydrogen production.

[1] M.Z. Granlund, K. Jansson, M. Nilsson, J. Dawody, L.J. Pettersson, Appl. Catal. B, Environ. (2014),

http://dx.doi.org/10.1016/j.apcatb.2014.02.043

[2] F Gunnarsson, H Kannisto, M Skoglundh, H Härelind, Appl. Catal. B: Environ. 152–153 (2014) 218–225

Figure 1. NOx reduction results from bench

scale reactor experiments 4 wt. % with 100

ppm Pt Ag/Al2O3 samples. Hydrogen

concentrations are denoted as 0 ppm (■),

1000 ppm (●), 1500 ppm (▲) and 3250 ppm

(▼). Inlet gas composition: 200 ppm NO, 10

% O2, 5 % H2O, N2,bal and NExBTL as

reducing agent with a C/N molar ratio of 6

and GHSV = 33,200 h-1.

Oral 4

EPR of Cu-CHA: Identification and quantification of copper species present after dehydration

Susanne Mossin1*, Anita Godiksen1, Frederick N. Stappen1,Søren Birk Rasmussen2 1 – Centre of Catalysis and Sustainable Chemistry, Department of Chemistry, Technical University of Denmark, Kemitorvet 207, 2800 Lyngby, Denmark 2 – Haldor Topsøe A/S, Nymøllevej 55, 2800 Lyngby, Denmark * slmo@kemi.dtu.dk Abatement of harmful emissions from incineration processes is especially important in highly populated areas. This results in tight legislation on the emission of NOx from both mobile and stationary sources. Copper substituted zeolites are active catalysts in the NH3-SCR reaction with high selectivity towards N2. Among them especially the small-pore zeolite chabazite is under investigation due to the high hydrothermal stability. In a fresh catalyst in equilibrium with the atmosphere the copper centers are fully oxidized and fully hydrated copper(II) ions with a high degree of freedom in the zeolite structure. During heating to the operation temperature above 350 degres the zeolite materials go through dehydration and the nature of the copper sites change gradually. The catalytically active sites are generated in-situ based upon the internal structure of the zeolite material and the dehydration conditions. Electron Paramagnetic Resonance (EPR) spectroscopy is sensitive to the dynamics, the geometry and the coordination number of the paramagnetic copper(II) sites and can be applied both ex- and in-situ. In this work we will present the results of an EPR spectroscopic investigation of the copper sites in a specific zeolite with the chabazite structure. The material has high Si/Al ratio of 13 and a Cu/Al ratio of 0.44. The EPR active sites after dehydration in an oxygen containing atmosphere are correlated with the 6 membered ring (6mr) sites in the structure determined by X-ray methods and UV-vis1,2,3 Using the double integral of the EPR spectrum the amount of copper in these sites and a small amount of isotropic Cu2+ can be quantified to be 21% and 7 %, respectively. The remaining copper amounts to 71% and the majority of it is expected to be Cu2+ in 8mr sites. The low symmetry and a dynamic Jahn-Teller distortion result in the copper becoming EPR silent. This interpretation is in accordance with the observation that after exposure to deoxygenated water 80 % of the copper is EPR active. After extended exposure to both water and oxygen the EPR signal of the fresh catalyst is regained 100 %. Figure 1. EPRspectrum of Cu-CHA before and after Figure 2. Two 6mr sites are resolved by EPR dehydration at RT and at 400°. Simulated EPR spectrum is shown in red. [1] Dustin W. Fickel, Raul F. Lobo, J. Phys Chem. C, 2010, 1633-1640. [2] Upakul Deka, Amèlie Juhin, Einar A. Eilertsen, Hermann Emerich, Mark A. Green, Satu T. Korhonen, Bert M. Wekhuysen, Andrew M. Beale, J. Phys Chem. C, 2012, 4809-4818. [3] Filippo Giordanino, Peter N. R. Vennestrøm, Lars F. Lundegaard, Frederick N. Stappen, Susanne Mossin, Pablo Beato, Silvia Bordiga, Carlo Lamberti, Dalton Trans., 2013, 12741-12761.

AlO

Si

OAl

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OSi

O

SiO Cu

AlO

Si

OSi

OAl

OSi

O

SiO Cu

2+ 2+

250 300 350 400

b) Cu-SSZ-13 dehydrated at RT

a) Hydrated Cu-SSZ-13

c) Cu-SSZ-13 dehydrated at 400°

Magnetic field / mT

3 2.8 2.6 2.4 2.2 2 1.8

Simulated spectrum

g-values

Oral 5

16th Nordic Symposium on Catalysis Effective Mn/TiO2 catalyst synthesized by deposition-precipitation method for low-temperature selective catalytic reduction of NO with NH3

Rasmus Fehrmann1

*, Siva Sankar Reddy Putluru 1, Leonhard Schill1, Anker Degn Jensen2,

1 – DTU Department of Chemistry, Kemitorvet, Building 207, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark 2 – Combustion and Harmful Emission Control Research Centre, Department of Chemical and Biochemical Engineering, Building 229, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark Waste incineration is a proven technology to reduce net greenhouse gas emissions because it avoids methane emissions from landfills. The incineration of waste releases CO2, however, the generated heat can be used to make electricity and for district heating, thus replacing coal or gas. One challenge of waste incineration is the flue gas containing high levels of Hg, Zn, dust etc. due to which the SCR unit is preferably placed at the tail-end position which requires costly reheating of the flue gas. Over the last decade there was a great interest in development of low-temperature SCR catalysts containing transition metal oxide catalysts like V2O5/TiO2, Fe/TiO2, Cu/TiO2, and Mn/TiO2. Among them Mn supported on titania and promoted with Fe is a promising, non-toxic candidate [1]. The most commonly used method of preparation is impregnation. However, high loadings of metals can cause them to be present in crystalline phase which causes unselective oxidation of NH3 instead of reduction of NO. We have developed a deposition-precipitation (DP) based method of preparation for MnFe/TiO2 yielding activities significantly higher than when using the traditional impregnation (IMP) method, see figure 1. The catalysts were thoroughly characterized using NH3-TPD, H2-TPR, XRD, N2-physisorption, XPS and TGA, see table 1. Compared to the IMP method the DP method leads to more surface acid sites, improved redox properties, no crystalline MnOx, higher surface area and more surface adsorbed oxygen. The higher content of surface adsorbed oxygen as evidenced by XPS is increasing the rate of NO to NO2 oxidation and might make the material also interesting for VOC removal.

150 200 250 300

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References [1]: Fu, M.; Li, C.; Lu, P.; Qu, L.; Zhang, M.; Zhou, Y.,; Yua, M.; Fange, Y., Catal. Sci. Technol. (2014), 4, 14-25

Table 1. Summary of important characteristics of IMP- and DP-prepared catalysts.

Figure 1. NO conversion over MnFe/Ti prepared by impregnation (IMP) and deposition-precipitation (DP).

Oral 6

16th

Nordic Symposium on Catalysis

Fundamental deactivation and regeneration mechanisms of Fe-BEA as NH3-SCR

catalyst for NOX reduction

Soran Shwan1*, Jonas Jansson

2, Louise Olsson

1 and Magnus Skoglundh

1

1 – Competence Centre for Catalysis, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.

2 – Volvo Group Trucks Technology, SE-40508 Gothenburg, Sweden.

* corresponding author: soran@chalmers.se

Introduction

Selective catalytic reduction with ammonia (NH3-SCR) is a well-established and effective method to

eliminate nitrogen oxides (NOx) in oxygen excess for stationary and, more recently, also for mobile applications

[1]. For the latter case, metal exchanged zeolites are attractive alternatives to vanadia-based SCR catalysts.

However, several challenges arise when using these materials in exhaust gas aftertreatment systems for diesel

and lean-burn vehicles. Two of the more important issues are the hydrothermal stability and the tolerance

against chemical poisoning of the metal exchanged zeolites [1].

This presentation will focus on iron-exchanged zeolite beta, Fe-BEA, as NH3-SCR catalyst. The

deactivation of Fe-BEA after hydrothermal treatment and phosphorous exposure has been studied

experimentally and by kinetic modeling as well as regeneration of the catalyst using hydrogen treatment. The

fundamental mechanisms for thermal and chemical degradation of Fe-BEA will be presented and discussed

together with regeneration of the catalyst by hydrogen exposure [2-4].

Results and conclusion

The mechanisms for thermal deactivation, chemical deactivation due to phosphorous exposure and

regeneration after high-temperature hydrogen treatment of Fe-BEA are schematically summarized in the Figure.

The hydrothermal treatment of Fe-BEA results in continuous migration of smaller iron species and formation of

larger iron oxide particles located on the external surface of the zeolite with resulting decreased NH3-SCR

activity. The hydrothermally treated Fe-BEA catalyst can partially be regenerated by high-temperature exposure

to hydrogen, re-dispersing larger iron species to active monomeric and dimeric iron species. Exposure of Fe-

BEA to a relatively low amount of phosphorous results in formation of metaphosphates blocking active iron

species and hence chemical deactivation of the SCR catalyst. The developed kinetic deactivation model

describes the experiments well for both thermally and chemically deactivated samples. To simulate the

deactivation process the number of active sites is decreased in the model to predict the effect of hydrothermal

and chemical deactivation due to loss of active iron sites.

Significance

Understanding catalyst deactivation mechanisms is very important for the choice of operation

conditions for catalytic processes and for the design of new catalyst formulations. For mobile applications,

catalyst deactivation is a practical concern in terms of sizing the catalyst for the lifetime of the vehicle and in

accounting for performance loss over time for the catalyst. Our studies contribute to the understanding of the

fundamental deactivation mechanisms of Fe-BEA as NH3-SCR catalyst with focus on the active iron sites. The

results show how the dynamics of the different active sites together with activity studies may be used to create

kinetic deactivation models.

Figure The different mechanisms discussed in

the presentation; thermal and chemical

deactivation as well as hydrogen regeneration

of Fe-BEA.

References

[1]S.Brandenberger, et al.,Catal.Rev.-Sci.

Eng.50 (2008) 492-531.

[2]S.Shwan, et al.,Catal.Today 197

(2012) 24-37.

[3]S.Swan, et al.,Appl.Catal.B 147

(2014) 111-123.

[4]R.Nedyalkova, et al.,Appl.Catal.B 138–139

(2013) 373-380.

Oral 7

16th Nordic Symposium on Catalysis/Abstract template Title: CO and CO2 Hydrogenation to Methanol

Felix Studt1* 1 – SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, CA * studt@slac.stanford.edu Methanol is among the top ten petrochemicals produced in the world and has been discussed as a transportation fuel in a methanol-based economy [1]. Industrially, methanol is produced from synthesis gas, a mixture of CO, CO2 and H2, at 230-280 °C and 50-120 bar employing a Cu/ZnO/Al2O3 catalyst [2]. Despite several decades of research, the active site of the industrially employed Cu/ZnO/Al2O3 catalyst was only identified recently [3]. It was found that defects and step sites are responsible for both CO and CO2 hydrogenation due to the increase of binding of reaction intermediates and their hydrogenation barriers when compared to terraces. This work also elucidated the reaction mechanism of the conversion of a mixture of CO2, CO and H2 to form methanol. Combined theoretical and experimental work found that the industrial catalyst comprised of Cu and ZnO allows for the fast conversion of CO2 to methanol while bare copper is superior at hydrogenating CO [4]. Performance catalysts will therefore expose a distribution of different sites that maximize the total conversion based on the feed composition (CO2 relative to CO) and reaction conditions. This analysis of Cu/ZnO/Al2O3 catalysts was extended towards other alloy compositions, theoretically investigating their ability to hydrogenate CO2 at low pressures. NiGa alloys were predicted by theory to exhibit catalytic properties close to or superior of those found for Cu/ZnO/Al2O3 (see Figure 1), a finding that was confirmed experimentally [5]. .

Figure 1. Theoretical activity volcano for CO2 hydrogenation to methanol.[5] The turnover frequency (TOF) is plotted as a function of the oxygen binding energy (∆EO) on stepped (211) surfaces. ∆EO for Ni-Ga intermetallic compounds are depicted in red. References [1] G. A. Olah, Angew. Chem. Int. Ed. 52 (2013) 104. [2] J. B. Hansen, P. E. H. Nielsen, in: Handbook of Heterogeneous Catalysis, eds. G. Ertl, H. Közinger, F. Schüth (Wiley VCH, Weinheim, 2008). [3] M. Behrens, F. Studt, I. Kasatkin, S. Kühl, M. Hävecker, F. Abild-Pedersen, S. Zander, F. Girgsdies, P. Kurr, B. L. Kniep, M. Tovar, R. W. Fischer, J. K. Nørskov, R. Schlögl, Science 336 (2012) 893. [4] F. Studt, M. Behrens, E. L. Kunkes, N. Thomas, S. Zander, A. Tarasov, J. Schumann, J. B. Varley, F. Abild-Pedersen, J. K. Nørskov, R. Schlögl, manucscript in preparation. [5] F. Studt, I. Sharafutdinov, F. Abild-Pedersen, C. F. Elkjær, J. S. Hummelshøj, S. Dahl, I. Chorkendorff, J. K. Nørskov, Nature Chem. in press. DOI: 10.1038/NCHEM.1873

-2 -1 0 1 2-1

0

1

2

∆EO-∆EO (eV)

Pd

Cu

Ni

Cu+ZnNi3Ga

NiGa

Cu

-2 -1 0 1 2

-1

0

1

-2

log

(TO

F/TO

FCu ) Ni5Ga3

Ni3Ga

Ni5Ga3

NiGa

Oral 8

Mixed alcohols synthesis over K-Ni-MoS2 catalysts prepared by conventional co-

precipitation and by microemulsion. Effect of alcohols co-feeding.

Rodrigo Suárez París1*, Magali Boutonnet1, Sven Järås1 1 Department of Chemical Engineering and Technology, KTH - Royal Institute of Technology, Stockholm, 10044,

Sweden.

* rosp@kth.se

Syngas can be catalytically converted to mixed alcohols, which are a promising alternative to conventional fuels.

Sulfided molybdenum-based catalysts promoted with alkali and transition metals are one of the most interesting

catalysts since they are sulfur resistant and deactivate slowly by coke deposition [1]. The microemulsion technique

appears to be a suitable method to manufacture the catalyst considering it has shown enhanced properties in many

applications [2]. Moreover, it has been reported that higher alcohols yield can be enhanced by co-feeding

methanol and ethanol with the syngas [3]. However, to the authors' knowledge, little is known regarding this effect

over K-Ni-MoS2 catalysts. The aim of this work is to develop and study the performance of a novel Ni-modified

K-doped molybdenum sulfide catalyst prepared by using the microemulsion technique and compare it with

conventional catalysts. The effect of alcohols co-feeding will also be studied.

Three different conventional catalysts were prepared (containing one or both promoters). Nickel promotion was

done by co-precipitation of Ni(CH3COO)2•4H20 and (NH4)2MoS4 solutions. Potassium doping was achieved by

a mechanical mixing. The final catalysts were obtained after thermal decomposition at 450°C under H2

atmosphere. In order to synthetize the microemulsion (ME) catalyst, two analogous water-in-oil systems were

mixed, containing the nickel and molybdenum salts. The rest of the preparation procedure is analogous to that

used for the conventional catalysts.

Catalysts were characterized by means of ICP, XPS, nitrogen adsorption measurements and XRD. The ME

catalyst shows a greater enrichment of the promoters, especially potassium, on the surface.

Activity and selectivity tests were performed in a setup described in detail elsewhere [4], with a premixed syngas

(H2/CO ratio=1/1 and 4% N2 as internal standard), at P=91 bar, T=340/370°C, GHSV=2000-14000 mL/ h•gcat.

Product analysis was carried out with an on-line GC, equipped with a TCD and two FID detectors. The

combination of both promoters is essential to achieve high selectivities to ethanol and higher alcohols. In addition,

the activity of the novel ME catalyst is higher at the different space velocities and reaction temperatures studied

within this work. Space-time yield of alcohols and, specifically, of ethanol is also enhanced with the new

preparation method, as can be seen in Figure 1. The stability of the ME catalyst has also been examined and no

significant deactivation was observed after about 200 h on stream (Figure 2). Work is on-going regarding the

effect of alcohols co-feeding in the system.

Figure 1 [left]. Space-time yield of ethanol for the different catalysts, at T=340°C.

Figure 2 [right]. CO conversion (■) and selectivity (☓) to ethanol and higher alcohols vs ToS for the ME catalyst,

at the following conditions: T(°C)=340 (1-5,11) / 370 (6-10); GHSV(mL/h•gcat)=2000 (2,7) / 6000 (1,5,6,10,11)

/ 10000 (3,8) / 14000 (4,9).

[1] Subramani, V. and S.K. Gangwal, Energy & Fuels 22 (2008): p. 814-839.

[2] Boutonnet, M., S. Lögdberg, and E. Elm Svensson, Current Opinion in Colloid & Interface Science 13

(2008): p. 270-286.

[3] Lachowska, M. and J. Skrzypek in: Studies in Surface Science and Catalysis, eds. A. Parmaliana, et al.

(Elsevier, 1998): p. 473-478.

[4] Andersson, R., M. Boutonnet, and S. Järås, Applied Catalysis A: General 417–418 (2012): p. 119-128.

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ME K-Ni-MoS2

Oral 9

Water and CO on monoclinic zirconia: Experimental and computational insights

Sonja Kouva1*, Karoliina Honkala2, Juha Lehtonen1, Jaana Kanervo1 1 – Dept. of Biotechnology and Chemical Technology, Aalto University, P.O. Box 16100, FI-00076 Aalto 2 – Dept. of Chemistry, Nanoscience Center, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä * sonja.kouva@aalto.fi Zirconium oxide (zirconia, ZrO2) is an interesting catalyst material for processing of bio-based chemicals and fuels. In this work we have studied the surface of monoclinic zirconia first calcined at 600 °C and then treated with H2 reduction and/or water vapor. CO was introduced to the sample at 100 °C and then the sample was heated in CO up to 550 °C. We have combined in situ DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) and temperature-programmed surface reaction (TPSR) to connect identities and stabilities of surface species to a dynamic, quantitated reactor response. Density functional theory (DFT) calculations complement the experimental data in terms of surface species configurations and their energetics.

Our results indicate that especially the low-temperature interaction between CO and monoclinic zirconia is affected by the pretreatment selection. On reduced zirconia, adsorbed linear CO (ca. 2190 cm-1) is observed on the surface during initial CO adsorption at 100 °C (shown on the left in Fig. 1) with decreasing intensity over time, the same decrease is observed in terminal OH intensity. Simultaneously, formate intensity (on the right, 1569 cm-1) slowly increases. Based on these observations, it seems that at low temperatures where linear CO is formed on the surface, formate formation can take place via terminal surface OH group and adsorbed linear CO, as previously suggested by Bianchi et al. [1]. Water vapor pretreatment blocks linear CO formation, as expected [2], and the onset of formate formation is delayed until 175-200 °C. This is in agreement with computational results showing that formate formation from gas-phase CO is highly activated, Eact is ca. 150 kJ/mol.

The gas-phase response for reduced ZrO2 during heating in CO is shown in Fig. 2., level below zero equals to uptake on the sample and level above zeros equals to release from the sample. Before heating the sample was stabilized in CO flow for 2 hours.

CO uptake takes place up to 330 °C, in accordance with the DRIFTS experiments showing formates at their highest intensity at 325 °C. Water release above 300 °C is due to dehydration of the sample, a blank run in helium shows a similar water release. Formate decomposition is observed after 330 °C: Formate species decompose reversibly to CO and irreversibly to CO2 and H2 with the contribution of the surface hydroxyl groups. The calculated reaction energies for irreversible formate decomposition are ca. 180-360 kJ/mol and in addition to that the calculations show that the process is activated. Based on the observed high reaction temperatures this seems reasonable. All three methods, DRIFTS, TPSR and DFT, give concurring results on formate formation and decomposition. References [1] D. Bianchi, T. Chafik, M. Khalfallah and S. J. Teichner, Appl. Catal., A 105 (1993) 223. [2] C. Morterra, L. Orio and C. Emanuel, J. Chem. Soc., Faraday Trans. 86 (1990) 3003.

Figure 1. 2300-2000 cm-1 and 1650-1450 cm-1 regions duringCO adsorption at 100 °C on reduced ZrO2. The inset showsthe linear CO (2192 cm-1) intensity during CO adsorption.

Figure 2. CO-TPSR for reduced ZrO2.Level 0 is the feed level, 3·10-7 mol/(g s)for 2% CO and none for the othercomponents.

Oral 10

16th Nordic Symposium on Catalysis In situ monitoring of cobalt supported catalysts for Fischer-Tropsch synthesis under realistic activation, reaction and regeneration conditions

Nikolaos E. Tsakoumis1*, Magnus Rønning1, Erling Rytter1, Anders Holmen1 1 –Department of Chemical Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway. * Corresponding: tsakoumi@chemeng.ntnu.no Fischer–Tropsch synthesis (FTS) is a tool for the utilization of synthesis gas derived from different feedstocks, i.e. natural gas, coal, and biomass [1]. In FTS on cobalt supported catalysts, carbon monoxide and hydrogen are converted into linear paraffinic hydrocarbons and water. Although the process counts many decades of existence and different commercial applications, still a lack of understanding exists regarding reaction, deactivation and regeneration mechanisms [2,3]. In order to address these questions a capillary based set-up that can accommodate X-ray based techniques [4,5] and Raman spectroscopy [6] was modified in order to withstand realistic conditions of activation, reaction and regeneration. Several different Co based catalysts were evaluated. Carbon based supports were used in addition to more industrially relevant Al2O3.

Figure 1. Flow diagram of the in situ set-up, 3D representation of Raman spectra, X-ray powder

diffractogramms and normalized X-ray absorption spectra obtained during catalyst activation together with signal from the MS showing H2O production and quantitative determination of the involved phases.

With the proposed experimental configuration the catalyst activation could be followed in detail and all the intermediate phases could be identified for several Co supported catalysts. The reaction was also performed at realistic conditions of high pressure (10-18 bar) and FTS relevant temperatures (210-220oC). Results highlight the importance of the induction period in FTS in which phase transformations were detected coinciding with changes in the reactor environment on the way to the pseudo-steady state. During the first days of reaction the signal from X-ray based bulk techniques and Raman spectroscopy was rather stable and only simulation of temperature runaways up to 400oC showed significant sintering and crystalline carbon formation. Phase gradients along the reactors length at different stages of the experiment were also detected. For the evaluation of the long term exposure of the catalytic material into FTS environment, catalysts were withdrawn from fixed-bed and slurry reactors and characterized in a pseudo-in situ manner. Results showed that one of the main deactivation mechanisms is sintering of Co nanoparticles although other deactivation mechanisms co-exist. Ex situ characterization techniques were applied to support the findings. Regeneration attempts of the deactivated catalyst through reducing and oxidative-reducing environments have been performed. The activity and selectivity of the catalyst was regained after specific treatments. However the structure activity/selectivity relations are still to be explained. [1] M.E. Dry, Catal. Today 71 (2002) 227–241. [2] N.E. Tsakoumis, M. Rønning, Ø. Borg, E. Rytter, A. Holmen, Catal. Today 154 (2010) 162–182. [3] N.E. Tsakoumis, A. Voronov, M. Rønning, W. van Beek, Ø. Borg, E. Rytter, A. Holmen, J. Catal. 291 (2012) 138–148. [4] J.W. Couves, J.M. Thomas, D. Waller, R.H. Jones, A.J. Dent, G.E. Derbyshire, G.N. Greaves, Nature 354 (1991) 465–468. [5] B.S. Clausen, H. Topsøe, Catal. Today 9 (1991) 189. [6] N.E. Tsakoumis, R. Dehghan, R.E. Johnsen, A. Voronov, W. van Beek, J.C. Walmsley, Ø. Borg, E. Rytter, D. Chen, M. Rønning, A.

Holmen, Catal. Today 205 (2013) 86–93.

Oral 11

16th

Nordic Symposium on Catalysis

Changes in the heat of adsorption during DME synthesis due to coking

Stefanie Tamm1,2

*, Louise Olsson1,2

1 – Competence Centre for Catalysis, Chalmers University of Technology, 412 96 Göteborg, Sweden

2 – Chemical Engineering, Chalmers University of Technology, 412 96 Göteborg, Sweden

* corresponding author: stamm@chalmers.se

During the last years, researchers have clarified the risks for serious climate changes caused by increasing

amounts of CO2 in the atmosphere. To minimize the effects of global warming, a substantial reduction of the

CO2 emissions from fossil resources is needed. One effective way to reduce CO2 emissions is the use of

alternative fuels produced from renewable resources like biomass and waste. Dimethyl ether (DME) is one of

the most energy effective and less CO2 emitting alternative transportation fuels which meets these criteria. In

addition, DME is non-toxic, non-cancerogenic and environmental benign, which is a further advantage

compared to conventional fuels [1].

In the synthesis of DME three reactions are involved: (1) methanol is formed form synthesis gas, (2) this

methanol is dehydrated to DME and (3) water reacts with CO to CO2 and H2. For each reaction a different

catalyst with different properties is needed. In the present study, we focus on the last step, the dehydration of

methanol to DME and compare an H-ZSM-5 and γ-alumina catalyst, the most widely studied materials for

methanol dehydration. The difference between these catalysts is the number and strength of acid sites. It is

known, that a large number of strong acid sites effectively catalyzes the dehydration reaction [2]. At the same

time, deactivation of the catalyst occurs due to formation of coke on acid sites explaining why ZSM-5 is more

prone to coking than alumina. This will influence how the gases can adsorb on the catalyst. Therefore, we

follow in the present study the changes in the heat of adsorption ΔH during formation of coke in a calorimeter.

The heat of adsorption ΔH is measured at three different temperatures over the fresh sample and after 4 h

coking. An example is shown in fig. 1. We find that ΔH decreases with temperature from 160 kJ/mol at 200 °C

to 140 kJ/mol at 100 °C and from 150 to 100 kJ/mol at the same temperatures over the fresh H-ZSM-5 and γ-

alumina, respectively. This indicates that ΔH is a function of the coverage over both catalysts. This is in line

with the adsorption of methoxy groups on different acid sites as observed in a DRIFT study.

Formation of coke additionally decreases the heats of adsorption at each temperature over the ZSM-5 sample.

The amount of formed coke was enough to be observed by a grey color of the sample at the end of the

experiment. In contrast, no clear formation of coke was observed over the Al2O3 sample, confirming that Al2O3

is the better catalyst for methanol dehydration to DME.

Figure 1. Thermogram and DME concentration for DME adsorption at different temperatures over the fresh

alumina catalyst.

References

[1] T.A. Semelsberger, R.L. Borup and H.L. Greene, J. Power Sources 156 (2006) 497-511.

[2] D.M. Sung, Y.H. Kim, E.D. Park and J.E. Yie, Res. Chem. Intermed. 36 (2010) 653-660.

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Co

olin

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olin

g

Oral 12

CO2 uptake in supported ionic liquid phase materials

Helene Kolding1, Anders Riisager1, Rasmus Fehrmann1* 1 – Centre for Catalysis and Sustainable Chemistry, Department of Chemistry, Technical University of Denmark, 2800 Kongens Lyngby, Denmark * rf@kemi.dtu.dk Carbon dioxide (CO2) has been named a culprit in the struggle against man-made climate change [1]. Abatement and conversion of CO2 is most easily accomplished where the highest concentrations are found: Power plant flue gases. However, flue gas contains many compounds incompatible with most catalyst systems: corrosive and reactive species such as SO2, NOx as well as a lot of water. In order to rule out the sensitivity of most catalysts to the impurities found in flue gases, separation and concentration of CO2 may well be a necessity for a catalyst to work properly. Transformation of CO2 therefore demands a pure source of CO2. One way to accomplish this could be to use an end-tail system with reversible ab- and desorption, where desorption is carried out separately to obtain a pure stream. A number of amino acid-based ionic liquids and their supported ionic liquid phase (SILP) analogs have been tested for reversible CO2 uptake, including tetrahexylammonium prolinate, [N6666][Pro].[2] Most materials showed a stoichiometric uptake of CO2 at ambient temperature and pressure. Reversible absorption/desorption and rapid sorption dynamics were shown to occur for the SILP materials without degradation with desorption at 80°C under a flow of Ar. Even after several cycles, the SILP materials retain >90% of their absorption stoichiometry. A flow study showed a significant silent time when a fixed-bed of [N6666][Pro] SILP was inserted into a dry gas stream containing 9 % CO2.[2] This system is envisioned to be used for CO2 uptake in an end-tail coal-fired power plant [1] S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K. B. Averyt, M. Tignor, and H. L. Miller, Climate Change 2007, Cambridge University Press, 2007. [2] H. Kolding, A. Riisager, and R. Fehrmann, Science China Chemistry 55 (2012) 1648

Oral 13

16th Nordic Symposium on Catalysis/Abstract template High throughput catalyst discovery for the direct synthesis of propylene carbonates from propylene glycol and CO2

Richard H. Heyn1* 1 – SINTEF Materials and Chemistry, P. O. Box 124 Blindern, 0314 Oslo * rhh@sintef.no Utilization of CO2 is of current interest from several perspectives. For large scale applications, the reduction of CO2 to fuels is under consideration as a recyclable energy storage vector and, depending on the overall CO2 balance of the reduction technology, a means of mitigating atmospheric CO2 emissions. Small scale applications focus on the use of CO2 in the synthesis of value-added chemicals and polymers. The effect on atmospheric CO2 emissions in these applications is significantly smaller, due to the overall volumes of these chemicals and polymers. The driving force here is sustainability, as CO2 is a renewable, essentially non-toxic, and inherently cheap C1 feedstock for the chemical industry. New reaction pathways involving CO2 rather than other C1 feedstocks can in principle be cleaner, with fewer byproducts and a smaller environmental footprint. Regardless of the application, radical improvements in both catalysis and process design are required to improve implementation of CO2 utilization technologies. CO2 is a very stable molecule kinetically and thermodynamically, so these improvements are necessary to drag CO2 out of these wells and into the light of chemical productivity. The EU project CyclicCO2 [1] is addressing these issues by a combination of catalyst and process design research for the production of cyclic carbonates from the renewables glycerol and CO2. Cyclic carbonates are envisioned for a number of applications, such as solvents, battery electrolytes, and additives to personal care products and detergents. Our activities and this presentation will discuss the discovery via high throughput technologies and understanding of improved catalysts for reaction 1. We have used this reaction as a surrogate for the carboxylation of glycerol due to experimental and analytical challenges with the use of glycerol. The catalyst screening is performed in the presence of MeCN, which acts as a chemical water trap (producing acetamide and eventually acetoxypropanols), in order to push the equilibrium further toward products. A total of 125 different catalyst combinations have been screened (Figure 1). Selected hits have been studied in a bench scale Parr reactor. Selected combinations show improved catalytic activities as compared to the standard catalyst Zn(OAc)2 + p-chlorobenzenesulfonic acid (Figure 2).

Figure 1. Normalized yields of propylene carbonate from Figure 2. Time vs. yield plot for the synthesis of high throughput experiments. propylene carbonate with Zn(OAc)2 + acid. Details of these experiments and the modelling of catalytic intermediates for this reaction will be presented. Reference [1] This research project has received funding from the European Union Seventh Framework Programme (FP7/2007 – 2013) under grant agreement n° 309497

C OO +

HO OH

O O

O

+ H2O (1)

Oral 14

Selective adsorption in Zirconium based metal-organic frameworks

Sigurd Øien1*, Knut Hylland1, Unni Olsbye1, Richard Blom2, Mats Tilset1, Karl Petter Lillerud1 1 – Department of Chenistry, University of Oslo, P.O. box 1033 Blindern, 0315 OSLO, Norway 2 – SINTEF Materialer og kjemi, P.O.Box 124 Blindern, NO-0314 Oslo, Norway * corresponding sigurdoi@kjemi.uio.no Zr-based metal-organic frameworks (MOFs) are crystalline, porous materials that recently have gained a lot of attention for their properties as catalysts. The catalytic property comes from the possibility to incorporate active seats as part of the framework itself, and has been demonstrated for many reactions1. Furthermore, this can be used to tune the adsorption properties of the material by designing sterical and chemical composition of the pores with functional groups.

Figure 1: The structure of UiO-67-Me.

Depending on the functional groups on the organic constituent, the BET surface area of Zr biphenyl framework UiO-67 (see figure 1) ranges from 2000 – 3000 m2/g, making it a promising adsorbent. We have shown in initial experiments that by functionalizing UiO-67 with methyl groups, the BET surface area decreases slightly, and the adsorption properties of methane, CO2 and water is altered (see figures 2 and 3).

Figure 2. High pressure adsorption curve of CO2. Figure 3. High pressure adsorption curves of methane. Our initial data suggests that UiO-67-Me has a higher enthalpy of adsorption and a higher storage capacity for methane, than regular UiO-67. For CO2, we observe the opposite. This selectivity is an exciting result, but is also likely improvable by utilizing other functional groups. References [1] M. Kim, S. M. Cohen, CrystEngComm, 2012,14, 4096-4104.

Oral 15

The reactivity of radicals and coke molecules trapped within the HZSM-5 cavities in the Methanol and Ethanol-to-Hydrocarbons reaction. S. Hamieh1, L. Pinard1, K. Ben Tayeb2*, H. Vezin2 1 – IC2MP UMR CNRS 7285, University of Poitiers, 86000 Poitiers, France. 2 – LASIR UMR CNRS 8516, University of Lille 1, 59650 Villeneuve d’Ascq, France. * karima.ben-tayeb-meziane@univ-lille1.fr

Ethanol and methanol are converted using HZSM-5 (Si/Al=40) zeolite into identical hydrocarbons and surprisingly with same selectivity. This is only possible owing to the fact that the two reactants have a common reaction intermediate (CRI). The objective of the study is to identify the CRI which will allow to propose a mechanism of the initial C-C bond formation from C1 unit that is an open question addressed many times and since long times.

The HZSM-5 zeolite converts, at 623K and under 3.0 MPa, methanol and ethanol into aromatics, olefins and paraffins molecules during a long time in spite of a high coke content [1, 2]. The mechanism of transformation of alcohols into hydrocarbons is radical and occurs through a common intermediate species; the carbene. :CH2 oligomerizes into olefins following a rake mechanism in which the growth probability factor α, determined by the Flory’s equation, is 0.53. Then olefins are either transformed into aromatics or are isomerized through benzyl carbocations blocked inside pores zeolite (Coke).

The role of coke is paradoxical, it can be a poison of zeolite acid sites or an active site of the isomerization reaction. Finally, the mechanism proposed in Fig. 1 is an alternative to the hydrocarbon pool mechanism, it combines two types of active sites: radicals and coke. It represents a combination of three mechanisms: I- “rake” type mechanism involving carbene species, II- olefins isomerization by active coke and III- transformation of olefins into aromatics.

Figure 1: Mechanism of methanol and ethanol conversion into hydrocarbons on HZSM-5 zeolite (olig. =

oligomerization, cyl. = cyclization and HT = hydrogen transfer, A = aromatics)

References [1] L. Pinard, S. Hamieh, C. Canaff, F. Ferreira Madeira, I. Batonneau-Gener, S. Maury, O. Delpoux, K. Ben Tayeb, Y. Pouilloux, H. Vezin, Journal of Catalysis. 299 (2013) 284-297. [2] L. Pinard, K. Ben Tayeb, S. Hamieh, H. Vezin, C. Canaff, S. Maury, O. Delpoux, Y. Pouilloux, Catalysis Today 218-219 (2013) 57-64.

C2

C=2

C3•• C4

•• C7+••:CH2

CH3OH (C2H5OH)

:CH2:CH2

α=0.53 αα α

Gas phase

ββ

:CH2 :CH2

C3= n-C4

=

C5•• C6

••

β β

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=

Adsorbed phase

Adsorbed phase

HC+

CH3

CH3

CH2+

C+

CH3

CH3

i-C4+ A

olig.

cyl.

HT

olig.

cyl.

HT

A

Gas phase

β=0.53

I

III

II

A(CH3)… A(CH3)2

A(CH3)A(CH3)2

Oral 16

A Reactivity Descriptor in Solid Acid Catalysis: Predicting Turnover Frequencies of Alkene Methylation in Zeotype Materials

Chuan-Ming Wang1,2, Rasmus Y. Brogaard2,3, Bert M. Weckhuysen4, Jens K. Nørskov2,3, Felix Studt2,* 1 – Shanghai Research Institute of Petrochemical Technology SINOPEC, Shanghai 201208, China 2 – SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA 3 – Department of Chemical Engineering, Stanford University, CA 94305, USA 4 – Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Faculty of Science, Utrecht University, 3584 CG Utrecht, The Netherlands * studt@slac.stanford.edu Recent work has reported discovery of metal surface catalysts by employing a descriptor-based approach, establishing a correlation between few well-defined properties of a material and its catalytic activity [1]. This theoretical work aims for a similar approach in solid acid catalysis, focusing on the reaction between alkenes and methanol catalyzed by Brønsted acidic zeotype catalysts. We modify the acidity by isomorphic substitution of metal ions in the zeolite and zeotype frameworks. Experimentally, the ammonia heat of adsorption is often used as a measure of the strength of acid sites [2]. Using periodic DFT calculations, we show that this measure can be used to establish linear scaling relations for the energy of intermediates and transition states of different chemical composition. Importantly, the scaling relations are independent of the chemical composition of the framework, lining up both zeolite and aluminophosphate materials of the same framework topology. These results show that the heat of ammonia adsorption can quantify the reactivity of the Brønsted acid sites. Interestingly, the scaling lines exhibit the same slope for transition states involving alkenes of different size and substitution in the same framework topology. This illustrates that the alkenes are equally sensitive to acid site reactivity, despite an inherent difference in the absolute rates of their methylation in a given material. The scaling lines allow us to use micro-kinetic modeling to predict a quantitative relation between ammonia heat of adsorption and the rate of alkene methylation from first principles [3]. We propose this as a step towards descriptor-based design of solid acid catalysts.

References [1] F. Studt, F. Abild-Pedersen, T. Bligaard, R. Z. Sørensen, C. H. Christensen, J. K. Nørskov, Science 320 (2008) 1320. [2] E. Derouane, J, Vedrine, R. R. Pinto, P. Borges, L. Costa, M. Lemos, F. Lemos, F. R. Ribeiro, Catal. Rev. - Sci. Eng. 55 (2013) 454. [3] C.-M. Wang, R. Y. Brogaard, B. M. Weckhuysen, J. K. Nørskov, F. Studt (2014), submitted.

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225 concerted

stepwise))step)1

0

25

75

stepwise))step)2

y=1.09x+97.9

y=0.80x+117.9

y=0.84x+147.1R2=0.98

R2=0.95

R2=0.98

AlPO234

CHA

250

Figure 2. Predicted rate of propene methylation as a function of calculated heat of ammonia adsorption in zeotype materials of the CHA framework.

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-175 -150 -50

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Si-AlPO-34Al-MFI

Al-CHANi-AlPO-34

Mg-AlPO-34

Figure 1. Scaling relations of transition states involved in the stepwise and concerted mechanisms of propene methylation in zeotype materials of the CHA framework topology.

Oral 17

Observation of Coke formation during the Methanol-to-Olefin Process using in situ

UV/Vis and Confocal Fluorescence Microspectroscopy

Emily C. Corker,1 Elena Borodina,

2 Javier Ruiz-Martínez,

2,* Rasmus Fehrmann

1 and Bert M.

Weckhuysen2,*

1 – Centre for Catalysis and Sustainable Chemistry, Department of Chemistry, Technical University of

Denmark, DK-2800, Kgs. Lyngby, Denmark

2 – Group of Inorganic Chemistry and Catalysis, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht,

The Netherlands

* corresponding authors: J.RuizMartinez@uu.nl; b.m.weckhuysen@uu.nl

The methanol-to-olefins (MTO) process over large H-ZSM-5 crystals was studied at two temperatures

(350 and 500 °C). The development of external and internal coke species could be detected using in situ UV/Vis

spectroscopy and confocal fluorescence microspectroscopy (Fig.1, 2,3), and has been correlated with catalytic

results. The large zeolites optical images, given in Figure 1, reveal the development of coke species during

MTO reaction. Deconvolution of the UV/Vis results, summarised in Figure 2, show an increase in the external

coking during the reaction and at higher reaction temperatures. This observation is in agreement with previous

literature findings regarding increased coke formation over H-ZSM-5 at higher temperatures.1,2

Confocal

fluorescence microscopy results (Figure 3) suggest the formation of larger aromatic molecules from smaller

ones, supporting the coke formation pathway as suggested by Mores et al..1,2

By comparing in situ

characterisation results to catalytic tests combined with operando UV/Vis measurements, we can conclude that

internal coke does not affect the stability of the catalyst and external coking caused by large aromatic species

contributes to the deactivation of H-ZSM-5 catalysts during MTO conversions.

Figure 1. Optical microphotographs of H-ZSM-5

crystals taken during the MTO conversion at 350

°C. The corresponding time is indicated in minutes.

Figure 2. Time development of deconvoluted

UV/Vis absorption peaks measured during MTO

conversion at 350 °C

.

Figure 3. Distribution of the fluorescence intensity from

H-ZSM-5 crystals irradiated with laser light sources at

488 nm and emissions were detected within the ranges

510-550 nm, in the middle crystal planes at varying

reaction times during MTO at 350 °C. The

corresponding time is indicated in minutes.

References

(1) Mores, D.; Stavitski, E.; Kox, M. H. F.;

Kornatowski, J.; Olsbye, U.; Weckhuysen, B. M.

Chem.-Eur. J. 2008, 14, 11320.

(2) Mores, D.; Kornatowski, J.; Olsbye, U.;

Weckhuysen, B. M. Chem.-Eur. J. 2011, 17, 2874.

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Oral 18

The influence of catalyst acid strength on reactions relevant for Methanol To

Hydrocarbons (MTH) catalysis

Marius Westgård Erichsen1, Kristof De Wispelaere

2, Jeroen Van der Mynsbrugge

2, Samuel

Moors2, Thomas Deconinck

2, Stian Svelle

1, Karen Hemelsoet

2, Veronique Van Speybroeck

2,

Unni Olsbye1*

1inGAP Centre of Research Based Innovation, Department of Chemistry, University of Oslo, N-0315 Oslo,

Norway 2 Center for Molecular Modeling, Ghent University, Technologiepark 903, B-9052 Zwijnaarde, Belgium

* corresponding author: unni.olsbye@kjemi.uio.no

Acid catalysis is important in many chemical reactions, not least in the petrochemical industry where acidic

zeolite catalysts are used in major processes such as catalytic cracking. Fundamental understanding of the effect

of Brønsted acid strength on key reactions is therefore a topic of major interest. Yet, few examples of such

studies exist. In one of the few available studies of acid strength Macht et al. [1] recently suggested that

reactions involving transitions states with localized charges are less sensitive to changes in acid strength than

those with diffuse charges.

This contribution compares two isostructural catalysts with different acid strength, H-SSZ-24 and H-SAPO-5

(AFI), for methanol to hydrocarbons (MTH) catalysis and key reaction steps relevant to this process. The MTH

reaction is a flexible reaction route to produce light alkenes or gasoline from alternative hydrocarbon feed-

stocks such as natural gas, biomass or coal [2]. Under steady-state MTH conditions, direct reactions between

methanol molecules are insignificant. Instead, product formation proceeds via continuous methylation of an

adsorbed hydrocarbon pool, which subsequently eliminates alkenes. The complexity of the reaction means that

key reaction steps might exhibit different sensitivities to a change in acid strength, and that overall selectivity

may be tailored by changing the acid strength.

When the product selectivity in the MTH reaction was compared in the two materials employed here, it was

found that the strongly acidic H-SSZ-24 is more selective towards aromatic products and light alkenes (C2-C3)

than the moderately acidic H-SAPO-5 [3]. Furthermore, isotopic labelling studies implied that while aromatic

hydrocarbon pool species appear to play an important role in H-SSZ-24, these are of less importance in the

weaker acid H-SAPO-5 [3]. To elucidate the reasons for this change in the major reaction intermediates, an

understanding of the key reaction steps involved in the MTH reaction and their individual sensitivity to changes

in acid strength is necessary.

The current study focuses on methylation reactions in the two catalysts. Co-reactions and kinetic investigations

strongly suggest that the methylation of alkenes is strongly favoured relative to methylation of aromatics in H-

SAPO-5, while methylation of aromatics is facile over H-SSZ-24. Concurrently with the reactor studies,

periodic DFT based simulations are used to investigate adsorption in the two catalysts. The key methylation

reactions are also studied by means of a molecular dynamics approach, which provides insight in the reactivity

of the different adsorption complexes and allows investigation of temperature effects [4].

Figure 1. While the strongly acidic H-SSZ-24 prefers aromatic intermediates, methylation of alkenes is strongly

preferred in the moderately acidic H-SAPO-5

References

[1] J. Macht et al., J. Am. Chem. Soc., 131 (2009) 6554.

[2] U. Olsbye et al., Angew. Chem., Int. Ed., 51 (2012) 5810.

[3] M. Westgård Erichsen et al., Catal. Today, 215 (2013) 216

[4] S.L.C. Moors et al., ACS Catal., 3 (2013) 2556

Oral 19

Dynamics of catalytic Pd nano-particles studied by time resolved high energy XRD

Davide Ferri1*, Mark A. Newton2, Marco di Michiel2, Oliver Kröcher1 1 – Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland 2 – ESRF, F-38043 Grenoble, France *Corresponding: davide.ferri@psi.ch Automotive catalysts work typically under severe conditions with respect to temperature and reaction environment. Moreover, due to the dynamics of engine operation the atmosphere to which the catalysts are exposed also changes periodically. Obtaining information about relevant structural changes occurring under such operation conditions at lab scale is challenging in terms of time and spectral resolution of the selected spectroscopic method. When time resolution is met, identification of relevant dynamic spectral features may be hindered by their typically weaker response compared to static signals not relevant to the process under study. In this contribution, we use the concentration modulation excitation approach (ME) [1] to extract structural information of small Pd nano-particles under fast transients from synchrotron X-ray diffraction (XRD). ME consists in the alternate and repeated switch between reaction conditions followed by phase sensitive analysis enabling separation of signals of possibly relevant components from those of the bulk response [2]. The advantage of using the ME approach is emphasized in the case of 2 wt% Pd/CeZrO2 (Pd/CZ) that is typically silent in the XRD with respect to the Pd-PdO phase. The time-resolved high energy XRD data collected during CO-O2 experiments designed to simulate oxygen storage capacity (OSC) experiments for three-way catalysis applications exhibit the reflections of cubic CZ but hardly display any tangible change. Also, given the fine dispersion of PdO induced by CZ, no information is available about the state of Pd. The phase-resolved XRD data exhibit only the very subtle changes associated with the signals responding to the modulation experiment. All signals of the CZ support shift repeatedly to lower and back to higher Q values in response to the CO and the O2 pulses, respectively. This behaviour qualitatively describes the reduction and the re-oxidation of CZ associated with its OSC. Importantly, the data also exhibit additional broad features (e.g. at ca 2.8 Å-1) that correspond to reflections of Pd nano-particles of 2 nm. The sole intensity change is associated with the relative increase of long range order attributed to PdO reduction. Therefore, the modulation data can capture the dynamic reduction and re-oxidation of PdO and CZ. Reduction of both PdO and CZ occurs much slower than re-oxidation. Comparison with the same experiment on 2 wt% Pd/Al2O3 confirms that this is the effect of the OSC of CZ. Hence, it is demonstrated that subtle structural changes of the XRD patterns can be captured and their temporal response precisely assessed. This provides access to the detailed structural-dynamic behaviour of the system.

Figure 1. (a) Colour map representation and (b) time-resolved hard-XRD patterns of 2 wt% Pd/CZ during a full CO/O2 modulation experiment at 573 K (T= 50 s). (c) Corresponding phase-resolved data. (d-f) High energy-XRD data for an identical experiment performed on 2 wt% Pd/Al2O3. (○) Pd and (�) PdO. [1] D. Baurecht, U.P. Fringeli, Rev. Sci. Instrum. 72 (2001) 3782. [2] D. Ferri, S.K. Matam, R. Wirz, A. Eyssler, O. Korsak, P. Hug, A. Weidenkaff, M.A. Newton, PCCP 12 (2010) 5634; D. Ferri, M.A. Newton, M. Di Michiel, S. Yoon, G.L. Chiarello, V. Marchionni, S.K. Matam, M. Aguirre, A. Weidenkaff, F. Wen, J. Gieshoff, PCCP 115 (2013) 1231; D. Ferri, M.A. Newton, M. Nachtegaal, Top. Catal. 54 (2011) 1070.

Oral 20

16th Nordic Symposium on Catalysis Catalytic application of metal nanoparticles confined in porous materials

Jacob Abildstrøm1, Agata Gallas-Hulin1, Jerrik Mielby1, Søren Kegnæs1* 1 – Department of Chemistry, Technical University of Denmark, Kemitorvet 207, Kgs. Lyngby 2800 * Corresponding authors skk@kemi.dtu.dk, In spite of the great technological, environmental and economic interests, general methods for the stabilization of metal nanoparticles against sintering are missing. Although for some specific systems it has been achieved by optimizing the interaction of nanoparticles with a support material or by encapsulation of the metal particles [1-3]. However, these known catalytic systems are in general rather expensive and difficult to synthesize and they cannot be produced in industrial scale. Therefore, the development of novel sintering stable heterogeneous nanoparticle catalysts, which find use in the chemical industry, is of great importance. Recently, we have developed several different catalytic systems where metal nanoparticles are confined in different porous materials. As an example, in figure 1, is shown gold nanoparticles trapped inside a silicalite-1 zeolite. The aim with encapsulation metal nanoparticles in a porous matrix, like a zeolite, is first of all to prevent the metal nanoparticle from sintering during a high temperature catalytic reaction. Furthermore, the porous matrix can also contribute active to the catalytic reaction. We have for instance shown that the encapsulated metal nanoparticles only are accessible through the pores which give highly size-selective reactions. Here, we present the progress, which we have made, on the synthesis of metal nanoparticles confined in different porous materials like zeolites, metal oxides and polymers. We have tested the materials as catalysts in different selective reactions. Furthermore, we have characterized the materials with various techniques including SEM, in situ TEM, STEM, TEM tomography, XPS, XRF, and XRD among others

Figure 1. STEM image of gold nanoparticles encapsulated in silicalite-1.

References [1] P. M. Arnal, M. Comotti, F. Schüth, Angew. Chem., 118 (2006), 8404. [2] Y. Dai, B. Lim, Y. Yang, C. M. Cobley, W. Li, E. C. Cho, B. Grayson, P. T. Fanson, C. T. Campbell, Y. Sun, and Y. Xia, Angew. Chem. Int. Ed. 49 (2010) 1. [3] A. B. Laursen, K. T. Højholt, L. F. Lundegaard, S. B. Simonsen, S. Helveg, F. Schüth, M. Paul, J.-D. Grunwaldt, S. Kegnæs, C. H. Christensen, K. Egeblad, Angew. Chem. Int. Ed. 49 (2010) 3504.

Oral 21

Investigation of Active Sites for the Oxygen Reduction Reaction on Nitrogen-doped

Carbon Nanomaterials

Marthe E. M. Buan1*, Navaneethan Muthuswamy

1, Ida Hjorth

1, De Chen

1 and Magnus

Rønning1

1 – Department of Chemical Engineering, Norwegian University of Science and Technology (NTNU),

Trondheim, Norway

*marthe.e.m.buan@ntnu.no

N-doped carbon nanomaterials exhibit activity towards the oxygen reduction reaction (ORR), the cathode

reaction in fuel cells [1-3]. These materials could thus be a cheap alternative to replace the high cost noble

metals currently used. However, the ORR-activities reported so far have not been as high as for Pt. In addition,

the nature of the active sites and the role of the transition metal used as carbon growth catalyst still remain

unclear. Efforts should therefore be made to understand the active site structure in N-doped carbon

nanomaterials so that the ORR-activity can be further improved. In the present work, a systematic evaluation of

the ORR on N-doped carbon nanofibers (N-CNFs) is performed, and the possible active sites are explored by

correlating the catalyst performance with results from XPS, S(T)EM and HRTEM.

Nitrogen-doped CNFs were grown over Fe supported on expandable graphite (Fe/EG) using a chemical vapor

deposition method. The N-CNFs were treated with nitric acid (NCNF_HNO3) and annealed at 900⁰C

(NCNF_900) in order to remove Fe and alter the O-functional groups on the surface. The ORR-activity was

examined by linear sweep voltammetry in an acidic electrolyte. A rotating ring disk electrode was used as

working electrode to enable the detection of H2O2 formation during the ORR. Elemental distribution on a single

N-CNF was performed by EDX-analysis in S(T)EM.

Both pristine N-CNFs and post-treated N-CNFs showed oxygen reduction potentials around 0.9V which is close

to the ORR potential of commercial Pt catalysts, see Table 1. However, the H2O2 production was lower for the

acid treated N-CNFs. This could be attributed to the presence of O-functional groups on the surface favoring the

4-electron pathway for the ORR. Furthermore, EDX-analysis showed high concentrations of oxygen and iron at

the tip of the N-CNFs, see Figure 1. This suggests that iron oxide is present in the N-CNFs and might be part of

the active site for the ORR. To study more closely the effect of nitrogen and iron on the ORR-activity, pure

CNFs (CNF) and NH3-treated Fe on EG (Fe/EG_NH3) were tested for the ORR. Interestingly, both samples

showed ORR onset potentials around 0.8V. It therefore seems that both Fe and N are contributing to the ORR-

activity of N-CNFs. Further investigations using highly sensitive characterization techniques such as HRTEM

will be performed in order to fully understand the nature of the active sites for the ORR.

[1] Matter, P. H., Zhang, L. & Ozkan, U. M., Journal of Catalysis 239 (2006) 83–96.

[2] Gong, K., Du, F., Xia, Z., Durstock, M. & Dai, L., Science 323 (2009) 760.

[3] Chen, Z., Higgins, D., Yu, A., Zhang, L. & Zhang, J., Energy and Environmental Science 4 (2011) 3167.

Figure 1: EDX-analysis on N-CNF in STEM.

Table 1: Comparison of the ORR onset

potential and the H2O2 formation at 0.5V

for the electrocatalysts.

Catalyst EORR (V) H2O2 (%)

Fe/EG 0.40 -

Fe/EG_NH3 0.80 46.9

CNF 0.83 6.9

NCNF 0.92 7.8

NCNF_HNO3 0.89 5.1

NCNF_900 0.92 10.1

Pt/C (E-TEK) 1.05 -

Oral 22

Adsorption Energy of Propylene Oxide Enantiomers on Chirally Modified Platinum

Measured with Single-Crystal Adsorption Calorimetry

Petr Dementyev*, Swetlana Schauermann, Hans-Joachim Freund Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany

* dementyev@fhi-berlin.mpg.de

Current demands of pharmaceutical and agrochemical industries in chirally pure chemicals are covered by

natural chiral precursors, enzyme and homogeneous enantioselective catalysis. Implementation of

heterogeneous catalysts into the enantioselective synthesis would have many advantages. The main wide-

recognized strategy for preferential production of one enantiomer over the other is a modification of usual metal

catalysts by adsorption of chiral organic molecules - chiral modifiers [1]. There are two proposed mechanisms

of the stabilizing interaction between a modifier and a reactant which are responsible for chirality induction. The

first one is the docking interaction that is formation of one-to-one complexes between modifier and reactant

molecules. The second mechanism is the formation of two-dimensional assemblies of modifier molecules which

provide specific adsorption sites for reagent molecules. This is so called chiral templating.

In this study we employ a surface science approach to elucidate the above mechanisms and to investigate two

model chiral modifiers. These are 1-(1-naphthyl)ethylamine (NEA) and 2-methylbutanoic acid (MBA) which

were studied before by temperature-programmed desorption and infrared spectroscopy [2, 3]. In both cases

chirally modified Pt(111) surface shows pronounced enantioselectivity revealed by adsorption and subsequent

desorption of chiral probe molecules of propylene oxide (PO). Herein a novel single-crystal adsorption

calorimeter (SCAC) is applied to test the same systems [4]. The technique allows us to directly measure the

interaction energetics between gaseous chiral molecules and chirally modified metal surface and to precisely

determine the absolute surface uptakes of the probe molecules. Detailed coverage dependences of adsorption

energy for both R- and S-enantiomers of PO were obtained as a function of the modifiers amount under clean

UHV conditions.

Low-temperature SCAC measurements illustrate that adsorption energy of PO on NEA-modified Pt(111) differs

from that on the pristine surface. For various modifier amounts it decays monotonically with PO uptake and

saturation of the monolayer takes place at the same level of approximately 5*1014

molecules/cm2. Initial

adsorption energy decreases by about 10 kJ/mol when going from bare Pt to the surface fully covered with

NEA. And adsorption energy on the modified surface is still higher than on PO multilayer. Thus PO adsorbs on

top of NEA molecules and interacts with NEA more strongly than with itself which is consistent with the one-

to-one model. On the contrary, adsorption energy of PO on MBA-modified Pt(111) follows the coverage

dependence of bare Pt, particularly PO molecules first occupy free metal sites and then form multilayer. Initial

adsorption energies on samples with four different MBA amounts are almost identical and equal to that on

pristine Pt being around 55 kJ/mol. PO uptake decreases gradually with increasing of MBA quantity. When the

modifier amount is close to a monolayer, PO uptake is still almost a half of that on the bare metal surface. It

indicates that MBA molecules form supramolecular structures having a lot of free surface pockets which agrees

with the templating mechanism. Within the SCAC experimental error neither energetic difference nor inequality

in surface uptake were detected between R- and S- PO enantiomers adsorbing on Pt surface decorated with NEA

as well as with MBA.

Thereby we for the first time directly measured the energetics for adsorption of chiral molecules onto chirally

modified metal surfaces exhibiting both templating and one-to-one characters. And the energetic

enantiospecificity seems to be very subtle. Some kinetic effects should be responsible for the overall

enantioselectivity observed in the desorption experiments [2, 3].

References

[1] C. J. Baddeley et al., Top. Catal. 54 (2011) 1348.

[2] I. Lee and F. Zaera, J. Am. Chem. Soc. 130 (2008) 14697.

[3] I. Lee et al., J. Am. Chem. Soc. 128 (2006) 8890.

[4] J.-H. Fischer-Wolfarth et al., Rev. Sci. Instrum. 82 (2011) 024102.

Oral 23

Near-Ambient Pressure XPS study of CO and H2 Oxidation over Pd model surfaces

Anne Borg1*, Vasco R. Fernandes1, Mari. H. Farstad1, Jan Knudsen2, Johan Gustafson2, Edvin Lundgren2, Hilde J. Venvik3 1 – Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, NORWAY 2 – Division of Synchrotron Radiation Research, Lund University, Box 117, SE-221 00 Lund, SWEDEN 3 – Department of Chemical Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, NORWAY * corresponding author: anne.borg@ntnu.no Palladium is a versatile oxidation catalyst, among others finding applications in CO removal from car exhaust [1] and total oxidation of hydrocarbons [2]. Furthermore, Pd and its alloys have high solubility, permeability and selectivity for hydrogen, making them suitable as hydrogen separation membrane materials [3]. Pd/Ag is a commonly selected alloy [4]. In the present work, we have investigated single crystal surfaces of Pd(100) and Pd75Ag25(100) as model systems for addressing oxide formation during CO and H2 oxidation reactions at Pd surfaces as well as the influence of Ag as alloying element on these reactions under near ambient, oxygen rich conditions. The experimental tools applied have been near ambient X-ray photoelectron spectroscopy (NAPXPS) in combination with quadropole mass spectrometry (QMS). The experiments were performed at beamline I511-1 of the MAX IV Laboratory [5]. An example of recorded data during CO oxidation over Pd(100) is presented in Fig. 1. The activation energy for CO oxidation over this surface was determined to be 1.0 eV, while a value of 1.1 eV was obtained for Pd75Ag25(100). CO inhibition of the reaction is observed at low temperatures for both surfaces upon CO oxidation only as well as in the case of simultaneous oxidation of CO and H2. In the latter case, the CO oxidation reaction is determining the overall reaction behaviour. While high activity for H2 oxidation over Pd(100) is demonstrated already at room temperature, low activity for this reaction is observed below a critical temperature over Pd75Ag25(100). Ag as alloying element thus significantly affects the oxidation reactions. While the characteristic surface oxide [6] is the highly active surface in the reactions for Pd(100), chemisorbed oxygen plays this role for Pd75Ag25(100). In summary, the presence of silver in the outermost surface layer significantly affects the surface chemistry and thereby the reaction mechanism.

Figure 1. CO oxidation over the Pd(100) surface at 0.7 mbar total pressure and O2:CO ratio 10:1. Left: The O 1s core level region recorded as a function of sample temperature along with the corresponding QMS data for O2, CO and CO2. Right: Decomposition of the O 1s core level spectra at two different stages (marked with dashed lines in the left part) during the CO oxidation experiment, low activity (lower panel) and high activity (upper panel) towards CO2 production. References [1] R. Heck et al., Catalytic Air Pollution Control: Commercial Technology, 3.ed, Van Nostand Reinhold, 2009. [2] P. Henry, Palladium Catalyzed Oxidation of Hydrocarbons, Springer 1980. [3] See eg. N. Itoh andR. Govind, Ind. Eng. Chem. Res. 28 (1989) 1554. [4] A. K. M. Fazle Kibria et al., Int. J. Hydrogen Energy 25 (2000) 853. [5] J. Schnadt et al., J. Synchrotron Rad. 19 (2012) 701. [6] M. Todorova et al., Surf. Sci. 541 (2003) 101.

Gas phase O2

Pd 3p

Surface oxide

CO

Gas phase CO2

Oral 24

16th

Nordic Symposium on Catalysis/Abstract template

Inhibition and Deactivation of Ni-MoS2 for Hydrodeoxygenation by Bio-oil Impurities

Peter M. Mortensen1, Diego Gardini

2, Hudson W. P. de Carvalho

3 Christian D. Damsgaard

2,

Jan-Dierk Grunwaldt3, Peter A. Jensen

1, Jakob B. Wagner

2, Anker D. Jensen

1*

1 – Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads

229, DK-2800, Denmark

2 – Center for Electron Nanoscopy, Technical University of Denmark, Fysikvej 307, DK-2800, Denmark

3 – Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT),

Engesserstrasse 20, D-79131, Germany

* corresponding aj@kt.dtu.dk

A prospective route to biofuels usable in the current infrastructure is the combination of flash pyrolysis and hydrodeoxygenation (HDO). However, little work has been devoted to evaluating long term stability or

resistance of catalysts toward feed impurities during HDO [1]. Traditional hydrotreating catalysts, as Co-MoS2

and Ni-MoS2, have been among the most tested catalysts [1]. This group of catalysts is already industrially

established catalysts in hydrodesulfurization (HDS) [1]. In the current study the stability of Ni-MoS2/ZrO2 has

been evaluated in a simulated bio-oil system.

The long term stability of the Ni-MoS2/ZrO2 catalyst is highly dependent on the presence of sulfur as evidenced

by two experiments in which sulfur was added from different sources and different concentrations. Figure 1

shows that 0.3 vol% 1-octanethiol in the feed was found insufficient to maintain stability of the catalyst, as the

degree of deoxygenation (DOD) decreased from 74% to 44% over 109 h of operation. Much better stability was

obtained when adding 2 vol% DMDS to the feed, here the DOD only dropped from 90% to 82% over 96 h of

operation.

Figure 1: Stability of Ni-MoS2/ZrO2 during HDO of

phenol and 1-octanol in two cases with different types

and concentrations of feed sulfur. T = 280 °C, P = 100

bar, WHSV = 4.0 h-1.

Figure 2: DOD over a Ni-MoS2/ZrO2 catalyst during

HDO of phenol in 1-octanol exposed to chlorine or

potassium. 1-chlorooctane was added to the feed in a

concentration of 0.05 wt% Cl. KNO3 was

impregnated on fresh catalyst in stoichiometric

amounts. T = 280 °C, P = 100 bar, WHSV = 4.0 h-1.

Analysis of the spent catalyst samples by XRD, TEM, and elemental analysis revealed that the catalyst co-fed

with 0.3 vol% 1-octanethiol was partly oxidized to MoO3.

Adding chlorine or alkali metal to the catalyst was found to cause a decrease in the DOD, as shown in Figure 2. Potassium caused a severe persistent deactivation, decreasing the DOD to ca. 5%. DFT calculations by

Andersen et al. [2] showed that potassium saturates the vacancy sites along the edges of the MoS2 slabs, which

probably explains the severe deactivation. Thus, both Ni and MoS2 based catalysts are severely deactivated by

potassium, indicating that this should be removed from the bio-oil before long term operation can be achieved.

Addition of chlorine to the feed was found to inhibit the reaction, and only decreased the DOD from 91% in the

un-poisoned case to 74% in the chlorine poisoned case. Removing the chlorine from the feed increased the

activity toward the level of the un-poisoned case again, showing a non-persistent nature of the chlorine

deactivation mechanism.

This work highlights the potential deactivation mechanisms relevant during hydrodeoxygenation of bio-oil.

[1] P.M. Mortensen, J.-D. Grunwaldt, P.A. Jensen, K.G. Knudsen, A.D. Jensen, Appl. Catal. A, 407 (1-2) (2011) 1

[2] A. Andersen et al., J. Phys. Chem. C, 115 (2011) 9025

Oral 25

Thermochemical conversion of biomass to fuels and chemicals

Juha Linnekoski*, Pekka Simell, Yrjö Solantausta, Matti Reinikainen, Ville Paasikallio,

Martta Asikainen, VTT-Technical Research Center of Finland, Solutions for Natural Resources and

Environment, Espoo, P.O.Box 1000, FI- 02044 VTT, Finland, * corresponding Juha.Linnekoski@vtt.fi

This presentation summarizes the long R&D work done at VTT for the production of fuels and chemicals

through gasification and pyrolysis routes. The work includes tests from laboratory and bench scale to process

demonstration units as well as techno-economic process evaluations and simulations.

In gasification the development has been focused on gas filtration and catalytic gas reforming, which can be

considered as the most challenging process steps and are still the focus of intense R&D. The aim of the work has

been on the improvement of the overall process economics of individual process steps, in tandem with detailed

modelling and techno-economic evaluation. Working solution for gas reforming has been a staged catalytic

reformer based on zirconia, precious metal and nickel catalysts operating at 700 – 1000 °C. It has been

successfully demonstrated that the concept works technically. Thousands of operating hours with gas reformer

has been achieved, but the challenges lies in the economics. The main results from this work will be sown

together with figures from economic evaluation based on Aspen Plus simulation models.

In pyrolysis, the first goal has been the production of heating oil, and today the first industrial scale

demonstration plants are starting in Finland: Fortum corporation is just commissioning a 50 000 t/a capacity

integrated pyrolysis oil plant in the town Joensuu [1]. Consequently, the focus of the present R&D work in this

field is shifting more towards catalytic upgrading of pyrolysis oil via e.g. catalytic pyrolysis and

hydrodeoxygenation. The aim of both technologies is to reduce the oxygen content of pyrolysis oil, thus making

it more suitable for further upgrading operations, or for more advanced end-use applications.

It is also important to note that the production of many essential chemicals is highly dependent on fossil raw

material and for instance the utilization of shale gas doesn’t provide any solution to this. As an example there is

an established market for BTX, naphthalene and some other alkylated benzene derivatives and the worldwide

demand for benzene derivatives is growing faster than 6% each year. About 85-90 % of aromatics are currently

produced from petroleum and practically all aromatics are based on fossil raw materials. The demand for

aromatics from renewable sources has increased rapidly and there is an urgent need for alternative, preferably

“green” production routes. VTT is working actively in this field. It is possible to produce aromatics both via

syngas route and via the pyrolysis oil route. So far technical feasibility studies have been made and several

interesting options for BTX production have been found.

In addition to the gasification and syngas route VTT has also developed other routes to manufacture bio-

aromatics. Interesting option for simultaneous bio-aromatics and bi-olefins (ethylene and propylene) production

is the hydrodeoxygenation (HDO) of wood pulping waste streams such as crude tall oil (CTO) followed by

steam cracking of the obtained bio-naphtha to light alkenes and aromatics [2-4]. Equal aromatic (BTX) and light

olefin composition can be achieved with CTO as currently with petroleum naphtha either by using pure CTO or

by co-cracking with petroleum naphtha.

In addition to the bio-olefins and bio-aromatics production VTT has also developed technology to transform

sugars to terephthalic acid (TPA), a precursor for polyethylene terephthalate (PET). PET is used in fibers and in

bottles and films. Future growth of bio-based PET is predicted to be high since the global beverage

manufacturers have announced that they will move to bio-based bottles. Currently TPA is oxidized from

petroleum based p-xylene. In VTT patented process p-xylene is fully or partly replaced by drop-in chemical p-

cymene. p-Cymene can be produced from biotechnically produced monoterpenes such as y-terpinene [5,6].

Cymenes can also be produced from terpene mixtures such as crude sulfur turpentine (CST) [7].

References:

1. http://www.fortum.com/en/energy-production/fuels/bio-oil/pages/default.aspx

2. Pyl, S.P. et al., Bioresource Technology 126 (2012) 48-56

3. Anthonykutty, J.M. et al., Ind. Eng. Chem. Res. 52 (2013) 10114-10125.

4. Harlin, A. et al., US20120053379-A1

5. Bromann, K. et al. WO13167812A1

6. Asikainen, M., et al, Green Chem. 2013, 15(11), 3230-3235.

7. Linnekoski, J., et al, submitted for publication in, Organic. Process. Res&Dev., 2014.

Oral 26

Catalytic Effects of Site Confinement on the Shuffling of Hydrogen Atoms during Alkanal

Deoxygenation on Solid Brønsted Acid Catalysts

Fan Lin, Ya-Huei (Cathy) Chin* Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Canada

* cathy.chin@utoronto.ca

Brønsted acid sites immobilized on solid matrixes with nano-meter sized pores and cages catalyze the

deoxygenation of light alkanals (RCH2CHO, R=CH3, C2H5, C3H7) from the effluent of biomass pyrolysis stream

at moderate temperatures (473-673 K) and ambient pressures without external hydrogen sources [1]. The

deoxygenation occurs via competitive or sequential catalytic events of inter-molecular or intra-molecular C=C

bond formation, ring closure, dehydration, alkylation, and H transfer steps to evolve larger alkenals, C6-C15

aromatics, C2-C9 olefins, and a small amount of dienes [2]. These pathways are either uni-molecular or bi-

molecular in nature and may require inter-molecular H transfer steps. We report mechanistic details for

deoxygenation on Brønsted acid sites grafted onto solid matrixes of (i) medium pore H-MFI, (ii) large pore H-Y,

and (iii) polyoxometalate clusters (H4SiW12O40) dispersed on mesoporous SiO2, based on rate measurements, acid

site titrations, and temperature programmed techniques. Specifically, we address the catalytic consequences of

local acid site environments, within which the acid sites were protected and contained to different extents. We

describe the site confinement effects on the shuffling of H atoms during deoxygenation catalysis, which in turn

determines the relative rates for the various reaction pathways and selectivities towards olefins, aromatics,

unsaturated oxygenates, and dienes, as well as the overall catalyst stabilities against coking.

Inter-molecular C=C bond formation of alkanals occurs via aldol type condensation reaction and forms

larger, unsaturated alkenals. This step is bi-molecular in nature and requires the formation of larger transition

state, therefore it occurs more rapidly on unconfined acid sites found on polyoxometalate clusters (H4SiW12O40)

than on sites confined within microporous crystalline structures (H-MFI, H-Y). The sequential ring closure and

dehydrogenation steps, however, require confined environments and these steps occur much faster on acid sites

contained within H-MFI and H-Y than on polyoxometalate clusters. The dehydrogenation step that forms the

aromatics provides the H atoms for a separate, competitive pathway of direct, uni-molecular deoxygenation

reaction, which involves the removal of O heteroatom to create the intra-molecular C=C bond and form the olefins.

In addition to these pathways, a parallel isomerization-dehydration reaction of the alkanals forms the diene. The

inter-molecular shuffling of H atoms, which are produced from the secondary dehydrogenation steps, and their

transfer onto alkanal isomers leads to the direct deoxygenation. The extent of H transfer determines the relative

amount of larger oxygenates and olefins in the product, whereas the formation of dienes from the isomerization-

dehydration step leads to catalyst deactivation.

In summary, we report the catalytic pathways and mechanistic details of H transfer and then discuss the

catalytic effects of site confinement. These effects govern the relative rates and thus selectivities towards the

formation of larger oxygenates, alkenes, dienes, and aromatics.

Acknowledgements

We acknowledge Natural Sciences and Engineering Research Council of Canada (NSERC) and Canadian

Foundation for Innovation (CFI) for their financial supports. Fan Lin acknowledges Hatch for Hatch Graduate

Scholarship for Sustainable Energy Research.

References

[1] T. Q. Hoang, X. Zhu, T. Sooknoi, D.E. Resasco, R. G. Mallinson, J. Catal. 271 (2010) 201-208.

[2] F. Lin and Y-H. Chin J. Catal. 311 (2014) 244-256.

Oral 27

16th Nordic Symposium on Catalysis/Abstract

Activity enhancement of CeZr oxide catalysts by SO2 treatment in NH3-SCR

Ari Väliheikki1*, Tanja Kolli1, Mika Huuhtanen1, Teuvo Maunula2, Riitta L. Keiski1

1 – Mass and Heat Transfer Process Engineering, Faculty of Technology, P,O,Box 4300, FI-90014 University

of Oulu, Oulu, Finland

2 – Dinex Ecocat Oy, Typpitie 1, FI-90620 Oulu, Finland

* corresponding ari.valiheikki@oulu.fi

Sulphur dioxide (SO2) is a poisoning component in exhaust gas (originated e.g. from ships) for deNOx catalysts.

SO2 declines the activity of iron [1] and copper based catalysts [2] in selective catalytic reduction of NOx by

NH3 (NH3-SCR). Vanadium(V)-SCR catalysts have other disadvantages e.g. low thermal durability and the

toxicity of vanadium compounds [3,4]. Thus, novel catalysts are screened to replace existing catalysts and to

fulfill the existing emission standards [5]. Cerium–zirconium (CeZr) oxide-containing catalysts have shown

high activity in several applications such as SCR, three-way catalysis (TWCs), and diesel oxidation catalysis

(DOC). Sulphur added on CeZr oxide in aqueous phase has been found to increase the NO conversion from 50%

to 80% in NH3-SCR [6]. The goal of this study is to find out the effect of sulphur on CeZr mixed oxides.

1g of CeZr oxide powder (provided by Dinex Ecocat) was placed in a quartz tube reactor. The sample was

exposed to 100 ppm of gaseous SO2 in the absence or presence of 10 vol-% of water (marked as S and SW,

respectively) with 10 vol-% of air and N2 balance for 5h at 400°C. The amount of sulphur on S and SW treated

CeZr oxides was 1.4 and 1.8 wt-%, respectively, according to XRF. S and SW treatments over the CeZr oxide

decreased the BET surface area by 26-30% and BJH pore volume by 24-26%. The NH3-SCR activity of the

studied samples was tested at 150-600°C and the catalyst mass and gas flow rate were kept constant (250 mg,

1 L/min). The reaction gas mixture consisted of 900 ppm NO, 100 ppm NO2 1000 ppm NH3, 10% O2, 10% H2O

balanced with N2. The NOx and NH3 conversions of fresh, S, and SW treated CeZr oxides are shown in Figure 1.

200 300 400 500 600

0

20

40

60

80

100

NO

x C

on

vers

ion

(%

)

Temperature (oC)

Fresh

S

SW

a)

200 300 400 500 600

0

20

40

60

80

100b)

NH

3 C

on

ve

rsio

n (

%)

Temperature (oC)

Fresh

S

SW

Figure 1. NOx (a) and NH3 (b) conversions of fresh, S and SW treated CeZr oxides as a function of temperature.

It was found that S and SW treatments increased the NH3-SCR activity of CeZr oxides. The NOx and NH3

conversions over S and SW treated CeZr oxides followed the similar trends. Based on these results, SO2 present

in exhaust gas has a significant positive effect on the NH3-SCR activity of CeZr oxides at 150-570°C. The effect

of SO2 on CeZr oxides will be examined further to interpret the observation. The new knowledge can be utilized

in designing future sulfur-tolerant SCR catalyst systems.

References

[1] G. Qi, Y. Wang and R.T. Yang, Catal Lett 121 (2008) 111.

[2] M.L.M de Oliveira, C.M. Silva, R. Moreno-Tost, T.L. Farias, A. Jimenez-Lopez and E. Rodriguez-Castellon

Appl Catal B 88 (2009) 420.

[3] L. Jiang, Y. Ge, A. Naeem Shah, C. He and Z. Liu, J Env Sci 22 (2010) 575.

[4] J.L. Domingo, Reprod Toxicol 10 (1996) 175.

[5] Directive 715/2007/EC of the European Parliament and Council.

[6] Z. Si, D. Weng, X. Wu, J. Yang and B. Wang, Catal Commun 11 (2010) 1045.

Oral 28

16th

Nordic Symposium on Catalysis

Investigation of NOx storage and release on different perovskite type catalysts

Norman Wilken1*, Mike Andersson², Magnus Skoglundh

1

1- Competence Centre for Catalysis, Chalmers University of Technology, Göteborg, Sweden.

2 - Dept. of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden

* corresponding wilken@chalmers.se

NO and NO2 are poisonous gases emitted by today’s diesel and gasoline engines. Especially for lean burn

engines operating with excess oxygen in order to achieve a more complete combustion of the fuel, NOx is a

concern. A traditional 3-way catalyst cannot remove NOx efficiently from the exhaust gas stream in the strongly

oxidizing environment resulting from the lean combustion. The interaction of NOx with different materials can

be used for a wide variety of applications including NOx storage and reduction catalysts or NOx sensors.

perovskites are an interesting group of materials because of their thermal stability at high temperatures (900C)

and their chemical resistivity in the hostile environment of exhaust gas streams. Furthermore their chemical

properties can be tailored specifically according to the application demands by choosing a combination of

elements in the perovskite framework.

In this work the adsorption and desorption properties of MgTiO3, CaTiO3, SrTiO3 and BaTiO3 have been

studied. The perovskite samples have been prepared in house using a wet chemical method. Different metal

salts were dissolved in water, the resulting solutions were combined to achieve the mixture of the desired metals

on an atomic level. The resulting precipitate was then filtered and freeze dried. In the final step the precursor

was heated in an oven to 1000°C to form a perovskite framework.

A series of experiments was performed using calorimetry in combination with mass spectrometry. Figure 1

shows a set of temperature programmed desorption experiments using SrTiO3. During the experiment the

perovskite samples were exposed to 2000ppm NO in 8%O2 at temperatures from 200°C to 500°C. After NO

was adsorbed on the surface the sample was heated in Ar with 40°C/min so that the stored NO could desorb

again. The experiment showed that more NO could be stored on low temperatures and also that the NO stored at

low temperatures was more strongly bound to the surface. At 500°C no NO storage is nearly completely

disabled.

Similar experiments were conducted with MgTiO3, CaTiO3, BaTiO3 in order to compare NOx storage and

release between the different materials. The Authors acknowledge the Swedish Energy Agency for funding.

Figure 1.Results from a series of NO-Temperature-Programmed-Desorption experiment on SrTiO3 between

200 and 500°C adsorption temperature.

0

50

100

150

200

250

300

350

400

0 2 4 6 8 10 12 14 16

pp

m P

d in

so

luti

on

Time (h)

65 C 22 C

Oral 29

Catalyst performance in high temperature catalytic combustion

Ingrid Linnas1, Bård Lindström

1, Henrik M.J. Kušar

2*

1 – ReformTech Sweden AB and ReformTech Heating Technologies AB, SE-164 40 Stockholm, Sweden

2 – KTH Royal Institute of Technology, Department of Chemical Engineering and Technology, SE-10044

Stockholm, Sweden

* corresponding hkusar@kth.se

The development of electric vehicles and environmentally friendly cars has increased significantly in the last 10

years and car manufacturers have shown increasing interest towards cleaner products. Most of the cars, busses

and trucks used today have some version of internal heating system. Today the market for vehicle heating

systems is dominated by few main manufacturers whose conventional heaters burn diesel at very low air-to-fuel

ratios resulting in high flame temperature that produces significant emissions, especially in NOX content. The

demand for cleaner heaters is growing continuously, due to the up-coming Euro 6 emission standard legislation

and at the moment there are very few cleaner products available on the market. ReformTech Heating

Technologies Sweden AB is developing a catalytic heater for the vehicle industry, compared to the conventional

heaters the system is burning diesel on a catalyst surface at high air-to-fuel ratios what results in very low

exhaust emissions. The catalytic combustors are easier to operate than flame combustors, and they can be

operated in a wide range of temperatures from ignition temperature to adiabatic flame temperature. Most of the

gaseous and liquid fuels can be used over a wide range of air to fuel ratios. Control of emissions gives an

important environmental aspect compared to the conventional heating systems. Furthermore, the catalytic

combustors are less noisy than flame combustors which make them suitable for heating applications

The purpose of this study was to evaluate catalyst performance in a catalytic heater. Different catalysts were

tested for the combustion of diesel at 5 KW adiabatic power. The catalysts were evaluated based on the

temperature profiles, emission results and mechanical durability. As shown in Figure 1 the experimental system

consists of two tubes that are on top of each other. The lower tube is for preheating purposes and the upper tube

for main operation, where the catalyst is placed in the end of the tube.

Figure 1 Catalytic reactor design.

The system is ignited with a spark plug in the preheating tube at low air to fuel ratios to ensure fast ignition. The

system is run on preheating mode until the temperature before the catalyst in the upper tube reaches 600°C.

After the preheating, the fuel is cut from the lower tube and introduced to the upper tube. In the upper chamber

the fuel spray and air is mixed before the catalyst. The combustion reactions occur on the surface of the catalyst.

The temperature of the catalyst is kept under 1200°C to reduce the risk of catalyst damage. During the tests the

temperatures before, after and inside the catalyst were monitored. Emissions were measured with Fourier

Transform Infrared Spectroscopy (FTIR).

The temperatures inside the catalysts were kept between 1000 and 1200°C. In order to sustain these

temperatures the air flow for the ceramic catalyst was significantly higher than for the metallic catalysts where

the air-to-fuel ratios were λ= 3,1 and λ= 2,6/2,7 respectively. For the ceramic supported catalyst there was a

peak in temperatures in the beginning of the operation which was not evident in the metallic catalysts

performance. In most of the experiments there was a slight decrease in the working temperatures of the catalysts

during the first hour of performance (50 to 100°C) what can be caused by the thermal stabilization of the

system. The catalyst with ceramic support showed the most promising results for this application with the

highest mechanical durability and exhaust emissions below 0,5 ppm for diesel and CO, NOX content in the

exhaust gas was negligible.

Oral 30

Study on the catalytic oxidation of DMDS over (Al2O3, Al-Si20 and SiO2) supported

catalysts

Bouchra Darif 1,2

*, Satu Ojala2, Laurence Pirault-Roy

3, Mohammed Bensitel

1, Rachid

Brahmi1 and Riitta L. Keiski

2

1-Laboratory of Catalysis and Corrosion of Materials (LCCM), Department of Chemistry, Faculty of Sciences

of El Jadida, University of Chouaib Doukkali, BP.20, 24000 El Jadida, Morocco.

2-Mass and Heat Transfer Process Engineering (MHTPE), Faculty of Technology, University of Oulu, P.O.

Box 4300, FI-90014 University of Oulu, Finland.

3- Institute of Chemistry of Poitiers: Materials and natural resources, CNRS-UMR 7285, University of Poitiers

B27, Rue Michel Brunet, 86073 POITIERS CEDEX 9 France. * Corresponding darif.bouchra@gmail.com

The objective of this work is to meet the challenges of the environmental regulations in the reduction of harmful

sulfur containing compounds such as dimethyldisulfide DMDS by preparing effective catalysts to perform

catalytic oxidation. In this work the approach is in varying the support material, as it is known as an important

factor influencing the nature and the dispersion of the catalytically active sites. Through this study, we report

improved catalytic activity and selectivity at relatively low temperatures for complete catalytic oxidation of

DMDS over 0.3wt%Pt-10wt%Cu based catalysts supported on -Al2O3 denoted Al, (Al2O3)0.8 (SiO2).0.2 denoted

AlSi20 and SiO2 denoted Si. We also report the effects of various catalyst properties determined by Brunauer-

Emmett-Teller (BET) surface area measurement, X-ray diffraction (XRD), Temperature Programmed Reduction

(TPR), Transmission Electron Microscopy (TEM) and in-situ FTIR measurement, on the activity and selectivity

of the catalysts in complete oxidation of DMDS.

CH3-S-S-CH3 +

O2 2 SO2 + 2 CO2 +3 H2O (1)

Table 1. Comparison of the catalytic reaction products

flow at the outlet stream for 0.3Pt10Cu/Al,

0.3Pt10Cu/AlSi20 and 0.3Pt10Cu/Si catalysts

Figure 1. DMDS content in the outlet stream vs. temperature for 0.3Pt/Al, 0.3Pt10Cu/Al, 0.3Pt10Cu/AlSi20

and 0.3Pt10Cu/Si (DMDS 550 ppm, m =100 mg, RT-550°C, 5°C /min).

From the results shown in Figure 1 it is concluded that DMDS is completely oxidised over 0.3Pt10Cu/Al at

relatively lower temperature compared to the 0.3Pt10Cu/AlSi20 catalyst. Catalyst characterizations by TEM-

EDX analyses suggested that this result is due to the formation of “Pt-Cu alloy” particles of 5 nm on the 0.3Pt-

10Cu/Al catalyst. However it has been found that the copper particles of 2 nm were dispersed separately from Pt

on the 0.3Pt10Cu/Al-Si20 catalyst, and crystal agglomerates of (50-100 nm) in the case of 0.3Pt10Cu/Si. Pt

particle size is 2 nm for Pt/Al. According to the reaction equation (Eq. 1), the catalytic oxidation of DMDS

should lead to the formation of CO2, SO2 and H2O. In Table 1 representing the formed reaction by-products in

molL-1

, it can be seen that the by-products content at the end of the catalytic reaction over 0.3Pt10Cu/AlSi20

matched with the theoretical values (Eq. 1) and only traces of CO are formed. However, in the case of

0.3Pt10Cu/Al and 0.3Pt10Cu/Si, we observed about 0.9 and 0.8 molL-1

of CO, respectively. Our results

evidenced that 0.3Pt10Cu/AlSi20 is as active as 0.3Pt10Cu/Al for DMDS oxidation and is the most selective

towards the formation of targeted products, CO2 and SO2. Concerning stability, an improvement is expected by

using the Al2O3-SiO2 support since it has been found that the amorphous Al2O3-SiO2 phase increases the

resistance of a supported catalyst against sulfur poisoning [1].

References

[1] W.R.A.M. Robinson, J.A.R. van Veen, V.H.J. de Beer, R.A. van Santen, Fuel Process. Technol. 61 (1999)

61.

Reaction products (mol.L-1

) 10-5

/

catalysts

CO

CO2

SO2

0.3Pt10Cu/Al 0.9 2.8 2.2

0.3Pt10Cu/AlSi20

0.2 2.4 2.0

0.3Pt10Cu/Si

0.8 1.6 2.6

Oral 31

Comparative study of Pt and Ni-Mn supported catalysts in dry reforming of methane Tatyana Kuznetsova*, Tamara. Kriger, Evgenii Paukshtis, Vladimir Rogov, Dmitrii Arendarskii, Arcadii Ishchenko, Vladislav Sadykov Boreskov Institute of Catalysis, Pr. Lavrentieva, 5, 630090, Novosibirsk, Russia * corresponding tgkuzn@catalysis.ru For Pt supported on γ-Al2O3 or Ce-Zr-(La)-O and NiyMnMezOx (20%)/γ-Al2O3 composites (Ni/Mn ratio =0.2÷1.0, Me=Cu, Mg, Mo, La, Zr or Ce, z=0.2), catalytic properties in dry reforming of CH4 (DR) in concentrated feeds were studied. NiMnOx-based composites are characterized by XRD and HRTEM. The specific features of reaction mechanism for different types of catalysts are elucidated by pulse microcalorimetry and kinetic transients and discussed with a due regard for their real structure and surface properties. Steady-state catalytic activity strongly depends upon composition of active components and supports (Fig. 1). For supported Pt catalysts (loading 1.4 wt.%), the highest activity is observed for CeZrLax (x=0.2-0.3) fluorite–like supports. At pulsing more diluted reaction mixture (7% CH4 + 7% CO2), the difference in activity of oxygen -pretreated Pt catalysts is not so dramatic. For both catalysts, conversions of CH4 and especially CO2 in pulses of one reagent (CH4 or CO2) are significantly lower than those observed in mixed pulses. This indicates the important role of conjugated activation of both reagents for the oxidative transformation of CH4 into CO and H2. Up to 1-3 oxygen monolayers (mobile oxygen of doped ceria-zirconia with the heat of O2 adsorption < 620-640 kJ/mol) are removed from oxidized Pt/CeZrLa catalyst until reaching the quasi steady-state, thus creating sites for efficient CO2 activation on reduced surface. Co-adsorption and activation of CH4 (on Ptδ+ centers) and CO2 (on anion vacancies sites) along with O transfer from activated CO2 to CHx fragments effectively proceed at Pt/CeZrLaxO interface without participation of strongly bound surface/bulk oxygen. The most optimal structure of such interface is realized for Pt/CeZrLax (x=0.2-0.3) catalyst due to partial incorporation of Pt into surface positions in vicinity of domain boundaries of fluorite (forming complex cluster defects) which helps to stabilize cationic Pt species. A weak interaction of Pt with alumina provides only a low concentration of active Ptδ+ sites at Pt/support interface and, hence, a low activity. Oxidized NiMnOx/alumina composites are slowly (~ 1h) activated in the reaction mixture at 900oC due to segregation of Ni nanoparticles from the mixed oxide precursor. Composite with Ni/Mn ratio =0.2 (Fig. 1) is less active as compared to Pt/CeZrLa catalyst. It confirms well-known data on a higher activity of Pt species in comparison with Ni in the activation of C-H bonds in CH4. Substitution of Mn by different cations decreases activity. In spent catalysts, Ni0, NiO, MnOx and NiMnOx clusters stabilized on the surface of Al-Mn and Al-Ni spinels are observed. Surface species Ni/NiO+MnOx could be considered as active centers for DR. The total scheme of DR mechanism on composites is close to that for Pt catalysts. CH4 activation proceeds on Ni0/Niδ+ clusters stabilized on NiMnOx surface domains which provide anion vacancies for CO2 activation and O transfer. Thus, for various catalysts, DR efficiently proceeds at metal/reducible support interface with a similar mechanism of conjugated activation of both reagents. NiMnO-based composites supported on alumina can be suggested as active and inexpensive catalysts for DR. A somewhat lower efficiency of Ni centers as compared to Pt in activation of C-H bonds in CH4 would be compensated by a higher Ni loading.

Figure 1. CH4 conversion for Pt and NiMnOx supported catalysts in DR at 700 and 800oC. 31.5% CH4 + 46.0% CO2 + 22.5% He, 2.3 l/h.

Figure 2. Possible models of active clusters for Pt/CeZrLaO (1), Pt/Al2O3 (2) and NiMnOx/Al2O3 (3) catalysts in DR.

Support by FP7 OCMOL and BIOGO Projects is gratefully acknowledged.

Oral 32

Supported nickel based catalysts, Ni/Mg(Al)O, for natural gas conversion, prepared via

delamination and restacking of MgAl- and NiAl- nanosheets

J. Karthikeyan, H. Song, U. Olsbye, H. Fjellvåg, A. Olafsen Sjåstad*

Department of Chemistry and Centre for Materials Science and Nanotechnology, University of Oslo, P. O. Box

1033, Blindern, N-0315, Oslo, Norway.*a.o.sjastad@kjemi.uio.no

Due to cost and availability of nickel metal relative to noble metals such as rhodium, nickel based catalysts are normally preferred for converting light alkanes to synthesis gas (H2 + CO). Råberg et al. [1] and Olafsen et al.

[2] have in the past shown that nanometer sized nickel particles supported on an Mg(Al)O mixed oxide give

very active and stable reforming catalysts. The superior performance of this type of catalysts is believed to be

linked to an optimal combination of support basisity and Ni particle size, e.g. [1,2]. Layered double hydroxides

or hydrotalcite like materials are used as precursors when synthesizing the Ni/Mg(Al)O catalysts; Figure 1.

Various LDH synthesis approaches have been explored for optimizing the nickel dispersion on the Ni/Mg(Al)O

catalysts; e.g. incorporation of nickel in the brucite-like layers as a solid solution [1,2] as well as incorporating

anionic nickel complexes to the LDH interlayer gallery [3,4] followed by calcination- and reduction steps.

It is well know that nitrate based LDHs can be delaminated in formamide into positively charged brucite-like

sheets with a thickness of less than one nanometer, without disturbing the atomic arrangement and the chemical

composition of the brucite-like layers [5]. The obtained stable suspension from the delamination process can in a

next step be utilized by stacking chemically distinct layers (e.g. layers of MgAl and NiAl stabilized in different suspensions) in an ordered or disordered manner, to form a nanocompositite [6]; see Figure 2.

In this work we have explored the potential of controlling nickel particle size and particle size distribution of

Ni/Mg(Al)O catalysts through a novel delamination – reconstruction – calcination/activation route. Good metal

dispersion is achieved through restacking of MgAl and NiAl nanosheets in a way that the NiAl layers are highly

separated in the reconstructed nanocomposite (Figure 2). We present procedures for preparation of the catalytic

materials, detailed materials characterization as well as catalytic testing results for a reference Ni/Mg(Al)O

catalyst and the new Ni/(Mg(Al)O catalyst produced from delaminated LDHs. Test reaction used is dry

reforming of propane.

Figure 1 a) Schematic drawing of the structural

arrangement of LDHs. b) TEM images showing

morphology of as-syn 3MgAl-NO3 and 3NiAl-

NO3.

Figure 2 Schematics showing principle for

delamination of two different LDHs and

subsequent restacking into a nanocomposite.

References

[1] L. Råberg, M. Jensen, U. Olsbye, C. Daniel, S. Haag, C. Mirodatos, A.O. Sjåstad, J. Catal. 249 (2007) 250.

[2] A. Olafsen, Å. Slagtern, I.M. Dahl, U. Olsbye, Y. Schuurman, C. Mirodatos, J. Catal. 229 (2005) 163.

[3] C. Gerardin, D. Kostadinova, N. Sanson, B. Coq, D. Tichit, Chem. Mater. 17 (2005) 6473.

[4] C. Gerardin, D. Kostadinova, N. Sanson, B. Coq, D. Tichit, Chem. Mater. 20 (2008) 2086.

[5] Q. Wu, A. Olafsen, Ø.B. Vistad, J. Roots, P. Norby, J. Mater. Chem. 15 (2005) 4695. [6] R.E. Johnsen, Q. Wu, A.O. Sjåstad, Ø.B. Vistad, F. Krumeich, P. Norby, J. Phys. Chem. C 112 (2008)

16733.

Oral 33

16th Nordic Symposium on Catalysis Studies on perovskite-type oxide LaCoO3±δ as methanol steam reforming catalyst: Effect of Pd and Zn substitution on the CO2 selectivity

J. Kuc1, M. Neumann2, M. Armbrüster2, S. Yoon1, A. Weidenkaff1,3, Santhosh K. Matam1* 1 – Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland 2 – Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, DE-01187 Dresden, Germany 3 – Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, DE-70569 Stuttgart, Germany * corresponding: santhosh.matam@empa.ch Steam reforming of methanol (SRM) got a significant attention as a promising process for on-board H2 generation for fuel cell (FC) applications [1]. Methanol is easier and safer to handle than the compressed H2 gas cylinder. The main drawback of SRM is the formation of CO as a by-product, which can poison Pt electrodes of a FC. Thus, extensive studies are dedicated to develop materials (ranging from classical metal oxides to intermetallic compounds) that can selectively perform SMR reaction as shown in eq. 1 [2]. CH3OH + H2O → 3H2 + CO2 ∆H° = 49 kJmol-1 (1) The present study investigates the novel multifunctional perovskite-type oxides as potential SRM catalysts to produce selectively H2 and CO2. To this end, a series of LaCo1-xBxB’yO3-1/2x (B = Pd2+ and B’ = Zn2+; x = y = 0.025, 0.075 and 0.0127: denoted as LCPZO-1, -2 and -3, respectively), together with the reference materials (LCO, LaCoO3-δ; LCPO, LaCo0.873Pd0.127O3-δ; LCZO, LaCo0.89Zn0.11O3-δ), were prepared by the amorphous citrate sol-gel method and characterized by various physico-chemical techniques. SRM activity of the catalysts was determined in a plug flow reactor equipped with mass spectrometer (MS) and gas chromatograph (GC). Prior to the experiments, catalysts were reductively pretreated at 590°C for 2 h. XRD results reveal that un-substituted LCO contains a single phase rhombohedral perovskite crystal structure with the 𝑅3�𝑐 space group. The structure is retained after partial substitution of Co by Pd and/or Zn ions. In situ XRD and TG-DTA during the reduction and H2-TPR data indicate that the onset reduction temperature of Co ions decreases significantly with Pd substitution, which is attributed to the hydrogen spillover effect [3].

Figure 1. Temperature dependent CH3OH conversion (left) and CO2 selectivity (right) of LCO ( ), LCPO ( ), LCZO ( ), LCPZO-0 ( ), LCPZO-1 ( ), LCPZO-2 ( ) and LCPZO-3 ( ). To evaluate the CO2 selectivity of the catalysts and to eliminate the effect of reverse water gas shift reaction (RWGS) on the selectivity, comparable CH3OH conversion at a given temperature over the catalysts is obtained by changing the catalyst mass. As evident from Figure 1, catalysts LCPZO-1, LCPZO-2 and LCPZO-3 with Pd/Zn show better CO2 selectivity (in the whole temperature range) than the reference materials LCO, LCPO and LCZO. At comparable CH3OH conversion of around 8% at 325°C over the catalysts (except LCPO that shows higher conversion due to Pd), the CO2 selectivity increases from 12 to 80% for reference and Pd/Zn substituted catalysts, respectively. The CO2 selectivity patterns in the high temperature range resemble the CO2 equilibrium curve. The improved selectivity of the catalysts can be attributed to ZnPd-like species [2]. References [1] J. Agrell, M. Boutonnet, and J.L.G. Fierro, Applied Catalysis A: General 253 (2003) 213. [2] M. Armbrüster, M. Behrens, K. Föttinger, S.K. Matam, et al., Catal. Rev. Sci. Eng. 55 (2013) 289. [3] Y.J. Huang, J. Xue, and J.A. Schwarz, Journal of Catalysis 111(1988) 59.

Oral 34

SUPPORTED IONIC LIQUID PHASE (SILP) CATALYZED GAS PHASE ETHYLENE

METHOXY CARBONYLATION

Santosh G. Khokarale*, Eduardo J. Garcia-Suarez, Anders Riisager, Rasmus Fehrmann

Centre for Catalysis and Sustainable Chemistry, Department of Chemistry,

Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark

*E-Mail:ksgo@kemi.dtu.dk

Supported ionic liquid phase (SILP) is an attractive way to heterogenized homogeneous catalyst. The SILP

technology consists basically in an ionic liquid (IL) film immobilize on a porous solid material (e.g. silica) and a

homogeneous catalyst dissolved in a supported IL layer (Figure 1). In practice, SILP is the perfect combination

of the benefits of both homogeneous catalysts allowing high activity and selectivity and heterogeneous catalysts

due to the large interfacial reaction areas and good product separation. Indeed, SILP catalysis has potential for

efficient catalyst recycling and it makes possible the application of homogeneous catalysis in fixed-bed reactor

technology. Furthermore, the resulting ionic liquid catalyst film is only a few nanometers thick allowing the

complete utilization of both ionic liquid and catalyst since the mass transport resistance from the gas into the

liquid phase is minimized compared with the biphasic systems where ILs are employed as reaction media [1]. In

addition, the very low vapor pressure of ionic liquids makes these catalytic systems optimum to be used in

continuous gas-phase processes minimizing the catalyst deactivation [2]. Therefore, SILP catalysis has attracted

much attention in the last years to the scientific community due to their attractive and successful performance in

many gas-phase catalytic processes with high industrial relevance such as, carbonylation, hydroformylation,

hydroamination, hydrogenation, Suzuki coupling etc., with excellent results in terms of catalytic activity and

catalyst stability [3-6].

Figure.1 SILP catalysis technology

In this work, we reported for the first time the application of the SILP catalysis technology to the continuous

gas-phase methoxycarbonylation of ethylene for methylpropanoate (MP) production (scheme 1) where MP is an

essential monomer in the industrial production of the highly world demanded methylmethacrylate (MMA).

Preliminary screening of the influence of different reactions parameters such as, ionic liquid loading, nature of

the support, metal loading, temperature and GHSV (h-1

), in both catalyst activity and selectivity is performed in

this study.

Scheme 1. Ethylene methoxycarbonylation

[1] A. Riisager, B. Jørgensen, P. Wasserscheid and R. Fehrmann, Chem. Commun. (2006)994.

[2] A. Riisager, R. Fehrmann, M. Haumann, and P.Wasserscheid, Angew. Chem. Int. Ed. 44(2005)815.

[3] R. Fehrmann, A. Riisager and M. Haumann (Eds.), Supported Ionic Liquids: Fundamentals and

Applications, Wiley-VHC, Weinheim, 2014

[4] M. Haumann and A. Riisager, Chem. Rev. 108(2008)1474.

[5] S. Breitenlechner, M. Gleck, T.E. Muller and A. Suppan, J. Mol.Catal. A: Chem. 214(2004)175.

[6] H. Hagiwara, Y. Sugawara, K. Isobe, T.Suzuki, Org. Lett. 6(2004)2325.

Reactant

SILP

Particle

Porous support

Product Metal complex

Ionic Liquid Film

Oral 35

Sonogashira coupling reaction over supported gold nanoparticles

Sheetal Sisodiya1, Joachim Schnadt2, Ola F. Wendt1* 1 - Centre for Analysis and Synthesis, Department of Chemistry, Lund University Box 124, SE-221 00, Lund, Sweden. 2 - Division of Synchrotron Radiation Research, Department of Physics, Lund University Box 118, SE-221 00 Lund, Sweden. * ola.wendt@chem.lu.se The Sonogashira coupling reaction, comprising the carbon-carbon (C-C) bond formation between a terminal alkyne and an aryl or vinyl halide (Scheme 1), represents one of the most important classes of reaction for synthetic organic chemistry and pharmaceuticals. Supported Pd, Ru and/or Pt-based nanoparticles have been extensively studied as catalysts [1,2]. However, their performance is challenged by practical issues, such as, metal leaching, formation of undesired byproducts, and use of cocatalysts. Lately, gold nanoparticles supported on metal oxides have been demonstrated as very selective and efficient catalysts for the title reaction [3]. Still, important aspects, namely: (i) support effect on the dispersion and nature of gold species, (ii) method of deposition of gold, (iii) optimization of reaction conditions, and (iv) reaction mechanism have not yet been addressed in full details. Our work on the Sonogashira coupling of phenylacetylene (PA) with iodobenzene (IB) (Scheme 1) aims to shed light on these crucial points.

Scheme 1. Sonogashira coupling of phenylacetylene (PA) and iodobenzene (IB) to diphenylacetylene (DPA).

Table 1. Characterization of supported Au catalysts.

Catalyst Aua (Wt.%) SBET (m2 g-1) Au/WO3 2.8 4 (5)b Au/TiO2 2.9 50 (55) Au/CeO2 2.7 53 (57) Au/V2O5 3.2 5 (4)

a Au content by XRF for impregnated samples. b Surface area (SBET) of the carriers in parenthesis.

Different metal oxide (WO3, TiO2, CeO2, V2O5, and Al2O3) supported gold nanoparticles were synthesized by dry impregnation and deposition-precipitation methods. The catalysts were characterized by various techniques, including powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron microscopy, X-ray fluorescence (XRF), and N2 sorption. The synthesized catalysts were tested in Sonogashira coupling of PA and IB using a liquid-phase glass batch reactor set-up, equipped with heater with temperature controller and magnetic stirrer. The reactions were carried out at different reaction temperatures (120-200°C), catalyst amounts, solvents, Au loading, and reaction time. The gold content in the as-prepared catalysts by dry impregnation is slightly less than the nominal value of 4 wt.% (Table 1). The samples prepared by deposition-precipitation (DP) revealed lower gold content (~1-2 wt.%) than those of impregnated, even though the nominal loading was same. The latter could be related to the loss of some gold ions during the washing step in the DP method. XRD patterns (not shown for brevity) of the impregnated samples showed sharper reflections of gold compared to those in the DP samples, likely indicating smaller and better dispersed Au nanoparticles for the latter method. The SBET of the carriers remained similar after deposition of Au, which suggests that the gold is deposited on the surface without altering the pore-structure of the carriers. XPS (not shown) spectra of the fresh Au/WO3 unraveled the formation of Au0. Furthermore, electron microscopy analysis is undertaken. The reaction data demonstrated the superiority of DP method over impregnation for Au/TiO2, Au/CeO2, and Au/V2O5 in term of conversion of IB and selectivity to DPA. However, Au/WO3 prepared by dry impregnation and DP exhibited similar conversion (XIB = 78%) and selectivity (SDPA = 62%). Au/WO3 prepared by dry impregnation was further tested to optimize the reaction conditions. The recyclability tests over Au/WO3 showed a little drop of IB conversion (by ~2%) and DPA selectivity (by ~6%) for the 4th cycle, which suggests the robustness of this catalyst. Also, mechanistic insights gained by XPS studies will be presented. References [1] G.W. Kabalka, L. Wang, and R.M. Pagni, Tetrahedron 57 (2001) 8017. [2] S. Gao, N. Zhao, M. Shu, S. Che, Appl. Catal. A: General 388 (2010) 196. [3] A. Corma, H. Garcia, Chem. Soc. Rev. 37 (2008) 2096.

Oral 36

16th

Nordic Symposium on Catalysis/Abstract

Effects of carbon supports in platinum catalysts for propane dehydrogenation

Andrey S. Volynkin1*, Prof. Edd A. Blekkan1, Prof. Magnus Rønning1

* corresponding andrey.s.volynkin@ntnu.no

1 – Department of Chemical Engineering, NTNU, 7491 Trondheim

Carbon can play different roles in the catalytic dehydrogenation of light hydrocarbons. While coke deposition

deactivates dehydrogenation catalysts, carbon can also be used as support for the active phase. In this work

graphite, multiwall carbon-nanotubes, fishbone carbon-nanofibers, platelet carbon-nanofibers and carbon black

(vulcan-72R) were used as support for platinum and investigated in two model reactions, propane

dehydrogenation and ethylene hydrogenation to investigate how different carbon supports influence the catalyst

behavior and properties.

All catalyst samples in this work were prepared by the polyol method [1], by first preparing platinum nano-

particles in basic ethylene glycol solution and then depositing them on carbon supports. Samples where

characterized by a range of techniques, including N2 physisorption (including BET), thermogravimetric analysis

(TGA), cyclic voltammetry with CO stripping, Raman and infrared spectroscopy, and electron microscopy

(SEM and TEM). Catalytic propane dehydrogenation was done at 500 °C with and without H2 in the feed.

Ethylene hydrogenation over the same catalysts at 100 °C was also studied.

In spite of the same origin of the Pt nano-particles, the catalysts show different catalytic behavior, showing a

dependence on the catalyst support. Carbon black supported samples demonstrated very different behavior from

catalysts with nanostructured carbon or graphite is used as support. A key difference is a higher catalytic

activity for propane dehydrogenation without hydrogen present in the feed (as seen in Figure 1a), while all other

samples showed negligible activity at those conditions. With some hydrogen present in the feed the long-term

activity for propane dehydrogenation is higher (Fig. 1b), but there are still differences between the supports and

carbon black gives the highest activity. These results are in contradiction with CO adsorption experiments

(measured by CV- stripping as described by Schmidt et al. [2]) and ethylene hydrogenation, which both indicate

lower available Pt surface area for the carbon black supported material.

Thus, the results indicate that the Pt/carbon black catalyst is less susceptible to coking compared to the other

catalysts tested for propane dehydrogenation.

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Figure 1. Catalytic dehydrogenation of propane at 500 °C over 0.102 g catalyst. a) With C3H8 and N2 (27.9:77.6

ratio) in the feed and 105 ml/min flow rate. b) With H2, C3H8 and N2 in the feed (4.4:27.6:69.8 ratio) and 102

ml/min flow rate.

References

1. I. Kvande, S. T. Briskeby, M. Tsypkin, M. Ronning, S. Sunde, R. Tunold and C. De, Top. Catal., 2007, 45,

81-85.

2. T.J. Schmidt, H. A. Gasteiger, G. D. Stab, P.M. Urban, D.M. Kolb and R. J. Behm, J. Electrochem. Soc.,

1998, 145, 2354-2358.

Oral 37

Mild and selective Hydrogenation of aromatic and aliphatic (di)nitriles with a well-

defined Iron Pincer complex

Christoph Bornschein,1 Svenja Werkmeister,1 Bianca Wendt,1 Haijun Jiao,1 Elisabetta

Alberico,1,2 Wolfgang Baumann,1 Henrik Junge,1 Kathrin Junge,1 and Matthias Beller1*

1) Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein Straße 29a,

Rostock, 18059, Germany

2) Istituto di Chimica Biomolecolare, CNR, tr. La Crucca 3, 07100 Sassari, Italy

*Matthias.Beller@catalysis.de

Nowadays, the hydrogenation of carboxylic acid derivatives constitutes a major task in organic

chemistry. Notably, for the pharmaceutical industry the hydrogenation of such derivatives represents a key

technology for crucial transformations. Therefore, carboxylic acid esters, amides and nitriles are regarded as

highly interesting substrate classes leading to extremely important products. Particularly, nitriles are attractive

starting materials for the synthesis of amines due to the fact that they can be easily obtained by a variety of

chemical transformations.[1] Furthermore, nitriles are readily available in nature: cyanogenic glycosides, cyan

lipids, and cyanohydrins which are found in bacteria, algae, sponges and fungi as well as in higher organism.[2]

Homogeneous catalysts for the hydrogenation of nitriles are almost limited to the presence of precious metals[3].

Recent progress is mainly achieved using ruthenium systems based on P or PN-ligands requiring the addition of

base to prevent side reactions. Until now, one non-precious metal catalyst has been reported for the reduction of

nitriles giving the desired amine only as a side product.[4] Hence, the synthesis of primary amines remains

challenging, particularly due to the higher reactivity compared with its secondary and tertiary derivatives.[5]

Especially, the use of an environmentally benign, easy available and therefore cheap catalysts is desirable to

satisfy ecological needs.[6]

Herein we present the first iron-catalyzed reduction of nitriles. Under mild conditions the catalytic

utility allows for the general hydrogenation of various aryl, alkyl, heterocyclic nitriles and dinitriles. By using

the molecular-defined iron PNP pincer complex 1 an exceptional functional group tolerance for ester-, ether-,

halogen-, acetamido-, amino and ,-unsaturated double bonds is achieved. An additional highlight of this work

is the hydrogenation of industrially important adiponitrile to 1,6-hexamethylenediamine in a multi-gram scale.

Furthermore, we performed B3PW91 density functional theory computation suggesting the preference of an

outer-sphere over an inner-sphere mechanism for this hydrogenation. In order to support these mechanistic

findings NMR-analysis of each crucial complex intermediate were conducted yielding in a proposed catalytic

cycle for the reduction of nitriles. In conclusion, we established the first mild and broad applicable

hydrogenation of functionalized aromatic and especially aliphatic nitriles and dinitriles.

Oral 38

Application of Proton Coupled Electron Transfer in Synthesis: Developing an Catalytic

and Highly Enantioselective Aza-Pinacol Reaction

Lydia J. Rono, Hatice G. Yayla, David Y. Wang, Michael F. Armstrong, and Robert R.

Knowles* Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States

* Corresponding author rknowles@princeton.edu

Concerted proton-coupled electron transfer (PCET) plays a critical role for substrate activation in biological

redox catalysis. However, the application of PCET mechanisms to organic synthesis remains largely

unexplored. [1][2] Herein, the first highly enantioselective catalytic protocol for the reductive coupling of

ketones and hydrazones is reported. These reactions proceed through neutral ketyl radical intermediates

generated via a concerted PCET event. Ketyl-formation is mediated by a chiral phosphoric acid and the

photoredox catalyst Ir(ppy)2(dtbbpy)PF6. Interestingly, these neutral ketyl radicals appear to remain H-bonded to

the chiral conjugate base of the Brønsted acid during the course of a subsequent C−C bond-forming step,

furnishing syn 1,2-amino alcohol derivatives with excellent levels of diastereo- and enantioselectivity. This

work illustrates the feasibility and advantages of concerted PCET activation in asymmetric radical chemistry.

References

[1] Tarantino, K. T.; Liu, P.; Knowles, R. R. J. Am. Chem. Soc. 2013, 135, 10022-10025

[2] Rono, L. J.; Yayla, H. G.; Wang, D. Y.; Armstrong, M. F.; Knowles, R. R. J. Am. Chem. Soc. 2013, 135,

17735-17738

Oral 39

16th Nordic Symposium on Catalysis Theory-Assisted Development of Z-Selective Olefin Metathesis Catalysts

Giovanni Occhipinti, Vitali Koudriavtsev, Karl W. Törnroos and Vidar R. Jensen* Department of Chemistry, University of Bergen, Allégaten 4, N-5007 Bergen, Norway * Vidar.Jensen@kj.uib.no Catalysis represents an important application area for molecular-level computational studies. The most important role of these studies has traditionally been to provide valuable insight into the mechanisms with which existing, successful catalysts mediate chemical processes. However, little by little, theory is taking on a more active and leading role in the development of new and better catalysts, exemplified by the advent of fully automated in silico drug-design-style methods for catalyst development [1]. Here, we present hands-on examples of interplay between theory and experiment in development of highly Z-selective catalysts for olefin metathesis. Achieving such catalysts has been a major goal in olefin metathesis for years [2], with reasonably selective catalysts being obtained only in recent years [3,4]. We have developed and used a comprehensive computational approach to develop Z-selective olefin metathesis catalysts. In addition to being based on detailed insight into the mechanism of metathesis as mediated by the ruthenium-based catalysts, the approach also takes into account catalytic activity and catalyst stability. Predictions using this strategy are consistent with experimental observations and have led to the realization of new catalysts with up to 96% Z-selectivity [3,5,6]. Equally important is the fact that the computational focus on catalyst stability has paid off: The most recent of the new catalysts, depicted in Figure 1, can be used in air, with unpurified and non-degassed substrates and solvents, and in the presence of acids [5]. These are traits that are unprecedented among previously reported Z-selective olefin metathesis catalysts. They are also very promising with respect to practical applications of Z-selective olefin metathesis.

Figure 1. New, highly Z-selective and robust olefin metathesis catalyst developed with help from theory References

[1] Y. Chu, W. Heyndrickx, G. Occhipinti, V. R. Jensen, B. K. Alsberg J. Am. Chem. Soc. 2012, 134, 8885–8895. M. Foscato, G. Occhipinti, V. Venkatraman, B. K. Alsberg, V. R. Jensen J. Chem. Inf. Model. 2014, in press. [2] A. Fürstner Science 2013, 341, 1357-1364. [3] G. Occhipinti, F. R. Hansen, K. W. Törnroos, V. R. Jensen J. Am. Chem. Soc. 2013, 135, 3331. [4] B. K. Keitz, K. Endo, M. B. Herbert, R. H. Grubbs J. Am. Chem. Soc. 2011, 133, 9686. M. M Flook, A. J. Jiang, R. R. Schrock, P. Müller, A. H. Hoveyda J. Am. Chem. Soc. 2009, 131, 7962. [5] G. Occhipinti, V. Koudriavtsev, K. W. Törnroos and V. R. Jensen Dalton Trans. 2014, in press. [6] V. R. Jensen, G. Occhipinti, F. Hansen, Novel Olefin Metathesis Catalysts. Int. Patent Appl. WO 2012032131, 2012

Oral 40

16th

Nordic Symposium on Catalysis

Reactivity of Cyclometalated Gold(III) Complexes Toward Alkenes

Eirin Langseth1*

, Eline Aa. Tråseth1, Ainara Nova

2, Richard H. Heyn

3 and Mats Tilset

2

1 – Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, 0315 Oslo, Norway

2 – Centre for Theoretical and Computational Chemistry (CTCC)

3 – SINTEF Materials and Chemistry, P.O. Box 124, Blindern, 0314 Oslo, Norway

* corresponding eirin.langseth@kjemi.uio.no

The interest in organo-gold compounds continues to grow. Gold(III) complexes are being investigated as

catalysts for organic transformations including the coupling of alkenes and alkynes to other organic

fragments.[1,2]

A key step in the catalytic reactions involving gold(III) is assumed to be the coordination of a C-C

multiple bond to the gold center. Various catalytic cycles involving a gold(III) -complex have been proposed.[2]

However, gold(III) alkene, alkyne, allene, or arene complexes have until recently not been conclusively detected

and characterized.[3,4]

We have observed that one of our cyclometalated gold(III) complexes[5]

reacts with ethylene in trifluoroacetic

acid (TFA) or trifluoroethanol (TFE) as depicted in the Scheme 1. This can be envisioned as way of

functionalizing ethylene. Reactivity of some gold(III) complexes with alkenes will be discussed as well as the

proposed mechanism for the reaction shown in Scheme 1.

Scheme 1. Reaction of Au(OCOCF3)2(tpy) with ethylene

[1] A. S. K. Hashmi, Chem. Rev. 107 (2007) 3180.

[2] H.Schmidbaur, A. Schier, Arab. J. Sci. Eng. 37 (2012), 1187.

[3] E. Langseth, M. L. Scheuermann, D. Balcells, W. Kaminsky, K. I. Goldberg, O. Eisenstein, R. H. Heyn, M.

Tilset, Angew. Chem, Int. Ed. 52 (2013) 1660.

[4] N. Savjani, D.-A. Rosça, M. Schormann, M.; Bochmann, Angew. Chem., Int. Ed. 52 (2013) 874.

[5] E. Langseth, C. H. Gørbitz, R. H. Heyn, M. Tilset, Organometallics 32 (2012) 6567.

Oral 41

16th

Nordic Symposium on Catalysis

Direct Catalytic Hydrogenation of Amides to Amines Under Mild Conditions

Jennifer Houghton1*, Rosa Ladero Gallardo

2, Stuart Bartlett

2, Martin Schneider

2, Jacorien

Coetzee2, Anders Riisager

1, David Cole-Hamilton

2 and Rasmus Fehrmann

1

1 – DTU Department of Chemistry, Kemitorvet, Building 207, Technical University of Denmark, DK-2800

Kgs. Lyngby, Denmark

2 – School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, Scotland, UK

* corresponding jenho@kemi.dtu.dk

Amines are an important class of compounds with a diverse range of applications including use in dyes,

detergents, solvents and as key intermediates and target molecules in the pharmaceutical industry. A convenient

route to the synthesis of amines, carried out widely in industry, is via the reduction of the corresponding amide.

Conventionally, stoichiometric hydride reagents are used to carry out such transformations, however these

reagents bring numerous drawbacks such as the requirement for lengthy and hazardous work-up procedures and

the generation of large quantities of waste.

As part of the EU SYNFLOW project, we have developed catalytic methods for the direct hydrogenation of

amides to the corresponding amines under mild conditions, using both homogeneous and heterogeneous

catalytic systems. The heterogeneous catalysts, the focus of the presented work, consist of supported bimetallic

nanoparticles of formula MRe/TiO2 (where M= Pd or Pt). Operation of the best of these catalysts has been

demonstrated in batch and continuous flow modes on an industrially relevant substrate. These provide atom

efficient alternatives to the use of bulk hydrides, and offer a significantly reduced environmental impact.

References

[1] J. Coetzee, H. G. Manyar, C. Hardacre, D. J. Cole-Hamilton, ChemCatChem, 2013, 5, 2843-2847

Figure 2. TEM image of amide hydrogenation

catalysts:a) 4%Pt4%Re/TiO2 ánd b)

8%Re2%PdTiO2

Figure 1. Hydrogenation of N-Methylpyrrolidone using

4%Pt4%Re/TiO2 in batch mode (including 2 recycles) (Conditions: 0.444 g catalyst, 5.88 mmol NMP in 1,2-dimethoxyethane,

20 bar H2, 160°C, 18h reaction time)

Oral 42

Catalysts based in cerium oxides for wet air oxidation of bisphenol A

Anne Heponiemi1*, Said Azalim

1, Tao Hu

1, Ulla Lassi

1,2

1 – University of Oulu, Department of Chemistry, P.O. Box 3000, FIN-90014 University of Oulu, Finland

2 – Kokkola University Consortium Chydenius, P.O. Box 567, 67701 Kokkola, Finland

* corresponding author anne.heponiemi@oulu.fi

Catalytic wet air oxidation (CWAO) of aqueous solution of bisphenol A (BPA) was investigated in the batch

reactor at temperature of 160 °C, air partial pressure of 20 bar and with the catalyst concentration of 4 g/l.

Several solids (CeO2, Ce0.85Zr0.15O2, Ce0.2Zr0.8O2, Ag/CeO2, Ag/Ce0.85Zr0.15O2 and Ag/Ce0.2Zr0.8O2) were

prepared and used as catalysts in the reaction. CeO2 was supplied by Sigma-Aldrich and Ce-Zr mixed oxides

were prepared by sol-gel method. Silver (2.5 wt-%) was loaded on different oxides by both wet impregnation

and complexation. Abbreviations of the catalysts are reported in Table 1.

Table 1. Nomenclature of the catalytic materials.

Oxides Abbreviations for oxides Abbreviations for 2.5 wt-% Ag catalysts,

Ag loaded with wet impregnation (i) or complexation (c)

CeO2 C A/Ci -

Ce0.85Zr0.15O2 Ce A/Cei A/Cec

Ce0.2Zr0.8O2 Zr A/Zri A/Zrc

Both fresh and used catalysts were characterized by BET method (specific surface area), XRD (diffractograms

and crystallite sizes) and ICP-OES (metal content). The residual BPA concentration was followed by taking

samples during oxidation reaction. BPA concentration was determined by UV-Vis spectrometry and the overall

amount of organic compounds by measuring the total organic carbon (TOC). The possible leaching of the

catalyst metals were determined by ICP-OES and forming intermediates were analyzed by UPLC.

According to the results, all studied catalysts were active in the removal of BPA (Fig. 1). High BPA reductions

were obtained with pure oxides (70-76 %) and the maximum removal attained already after one hour experiment

with Ce-Zr mixed oxides.

Figure 1. BPA removal as a function of oxidation time for a) oxide catalysts and b) for silver loaded catalysts.

Operating conditions: p (air): 20 bar, T: 160 °C, catalyst load: 4 g/l, c (BPA): 60 mg/l.

The adding of silver to the oxide supports did not affect significantly BPA removal efficiency. As a matter of

fact, the BPA removal even dropped from 70 % (pure oxide) to 52 % after silver loading in the case of CeO2.

According to our studies, the adding of silver to the CeO2 and Ce-Zr mixed oxides has no improvement in the

abatement of bisphenol A from aqueous solutions. The highest BPA removal (76 %) was achieved with

Ce0.85Zr0.15O2 catalyst.

Acknowledgements

Authors acknowledge the Academy of Finland for research funding (AOPI, project 263397) within the research

programme for Sustainable Governance of Aquatic Resources (AKVA).

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Oral 43

Toluene oxidation mechanism over ZrO2-based gasification gas clean-up catalysts

Tiia Viinikainen*, Sonja Kouva, Juha Lehtonen, Jaana Kanervo Aalto University, School of Chemical Technology, P.O. Box 16100, 00076 Aalto, Finland * tiia.viinikainen@aalto.fi Biomass gasification is an environmentally attractive way to produce energy and synthesis gas that can be converted into liquid biofuels and chemicals [1]. Before utilizing the product it has to be cleaned from impurities, namely from tar and ammonia [2]. Catalytic hot gas cleaning is a preferable option. Lately ZrO2-based catalysts have shown to preferentially oxidize tar molecules within the gas mixture [3-4]. To enable process design ensuring high-quality gas, detailed knowledge of tar decomposition mechanism needs to be established. Therefore, temperature-programmed oxidation of toluene (a tar model compound) was carried out and the reaction mechanism was postulated. Extensive kinetic data was measured for pure ZrO2, Y2O3-ZrO2 and SiO2-ZrO2 by applying three oxygen/toluene feed ratios of 9.2, 16.7 and 28.6 (≈ 1, 2 and 3.5 x theoretical total oxidation ratio, respectively) and three heating rates (6.7, 10 and 15 °C/min) in the temperature range of 200-600 °C. The temperature-programmed reactor was modelled as a dynamic pseudohomogeneous plug flow reactor and the kinetic parameters were estimated by non-linear regression between the measured and simulated molar flows of the reaction components. Four products were detected in all toluene oxidation experiments over ZrO2-based catalysts: CO2, H2O, CO and H2 (typical gas flow out of the reactor shown for ZrO2 in Fig. 1). The effect of oxygen to toluene feed ratio to CO2/CO formation ratio is shown in Fig. 2. It can be seen that with higher O2/TOL ratio, the CO2/CO ratio increases rapidly at higher temperatures implying potential loss of valuable gasification gas components. The data analysis showed that toluene starts to convert at lower temperatures than oxygen, indicating that surface species are involved. Therefore, the formation of benzyl species [C7H7] from toluene (reaction 1) is suggested to be the first step in toluene oxidation, in accordance with our previous spectroscopic findings [5]. Furthermore, the product formation curves over all three catalysts showed two shapes; CO2 and H2O curves are similar, as are those for CO and H2, suggesting that products are formed in pairs. Including the measured product ratios, a preliminary reaction mechanism is proposed. In this mechanism, benzyl species are first decomposed into 5 CH-units, 1 CH2-unit and 1 C-unit on the surface (reaction 2), products are formed in pairs (reactions 3 and 4) and reactions 5-8 will be used to obtain the measured product ratios. Further data analysis for reaction mechanism hypotheses and the obtained modelling results will be shown in the presentation. C7H8 (g) → [C7H7] + [H] (1) [C7H7] → 5 [CH] + [CH2] + [C] (2) [CH] + 1.25 O2 (g) → CO2 (g) + 0.5 H2O (g) (3) [CH2] + 0.5 O2 (g) → CO (g) + H2 (g) (4)

[C] + 0.5 O2 (g) → CO (g) (5) [C] + O2 (g) → CO2 (g) (6) [H] → 0.5 H2 (g) (7) [H] + 0.25 O2 (g) → 0.5 H2O (g) (8)

Figure 1. Typical gas flow out from the reactor Figure 2. The effect of feed ratio to CO2/CO ratio over ZrO2 (O2/TOL: 9.2, heating rate: 10 °C/min). over ZrO2 (heating rate: 10 °C/min). [1] P. Gallezot, A. Kiennemann, in: Ertl, G., Knözinger, H., Schüth, F. and Weitkamp, J. (Eds.), Handbook of Heterogeneous Catalysis, 2nd ed., Wiley-VCH, Weinheim, 2008. [2] D. Sutton, B. Kelleher, J.R.H. Ross, Fuel Process. Technol. 3 (2001) 155. [3] S.J. Juutilainen, P.A. Simell, A.O.I. Krause, Appl. Catal. B 62 (2006) 86. [4] T. Viinikainen, H. Rönkkönen, H. Bradshaw, H. Stephenson, S. Airaksinen, M. Reinikainen, P. Simell, O. Krause, Appl. Catal. A. 362 (2009) 169. [5] T. Viinikainen, E.I. Kauppi, S.T. Korhonen, L. Lefferts, J.M. Kanervo, J. Lehtonen, Appl. Catal. B 142-143 (2013) 769.

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2 x theoretical O2/TOL ratio

3.5 x theoretical O2/TOL ratio

Oral 44