Combinatorial Approaches in
Heterogeneous Catalysis
Jochen Lauterbach
University of South Carolina
1
Department of Chemical EngineeringSmartState Center for Strategic Approaches to the
Generation of [email protected]
Day of examples!
• Metallic glasses & machine learning (not
catalysis)
• Flexible fuel reforming catalyst
• NOx SCR catalysts for power plants
• Mixed oxide catalysts for partial oxidation
of ethane
• (NH3 decomposition)
2
Metallic Glass Formation Prediction via
Machine Learning
– Material Selection
– Machine Learning
– High Throughput Synthesis
– Results and Iterative Learning
x
Example 1: Metallic Glasses
Metallic Glasses4
Schroers, J. Phys. Today 2013, February, 32.
Metallic Glasses5
Küchemann, S.; Samwer, K. Acta Mater. 2016, 104, 119. Chen, M. NPG Asia Mater. 2011, 3 (September), 82.
Machine Learning
Theories(Thermodynamic,
Geometric, etc.)
Experimental
Datasets(Prior known material
compositions)
(Landolt–Börnstein)_
Elemental
Properties(atomic size, number,
etc.)
Machine
Learning1Prediction
Training
Data
Features
61) Ward, L., Agrawal, A., Choudhary, A. & Wolverton, C. A general-purpose machine learning framework for predicting properties of inorganic materials. arXiv preprint arXiv:1606.09551 (2016)
Machine Learning Predictions
indicates experimental data
7
Compositional Gradient Film
8
Characterization – XRDLinear Accelerator
9
Metric for Determination of Glass Formation
10
“sharp” diffraction peak is an indication for metallic glass formation
Metric for Determination of Glass Formation
11
Metric for Determination of Glass Formation
12
Metric for Determination of Glass Formation
Full Width at Half Max
13
Machine Learning Predictions
indicates experimental data
14
XRD Results
15
Amorphous Silica as a Threshold for FWHM
Gla
s
s
Cry
sta
l
FWHM FSDP
Silica
(0.57 Q)
16
Results of First Generation Machine Learning
19
Machine Learning Generation 2
20
21
Glass
Cry
sta
l
FWHM FSDP
Silica
(0.57 Q)
Machine Learning Generation 2
221000˚C
Combinatorial Cycle
Rapid Synthesis
Parallel Screening
Data Minimizationand Analysis
Hypothesis Generation
0 10 20 30 40 50 60 70
0
10
20
30
40
50
60
70
Model P
redic
ted N
Ox s
tora
ge
Experimental NOx storage
Design Points
Validation Points
Hattrick-Simpers, J. R., Wen, C., and Lauterbach, J. “The Materials Super Highway: Integrating High-Throughput Experimentation into Mapping the Catalysis Materials Genome” Catalysis Letters145, no. 1 (2014): 290–298.
Factors Influencing Yield of a Catalyst
J. Bisquert, Journal of Physical Chemistry Letters 2 (2011) 270
Portable power applications:
• Unmanned aerial vehicles powered by LPG fuel cells
– Weight and charge advantages over batteries
• Auxiliary power applications
– Increase stationary efficiency
• Trucks during idle time
• RVs, boats
• Emergency responders
Example II: LPG Fuel Cell Technology
24
Why JP-8? Availability
• JP-8 is the single battlefield fuel of NATO
• Widespread existing supply infrastructure
and distribution network
Liquid Fuels as Feedstock
Challenge – Obtain LPG from JP-8 /
Diesel / gasoline
25
Process options:
1. Steam Reforming – cannot add water
2. Partial Oxidation – high temperature load, yields syngas
3. Catalytic Cracking
Challenges:
• Target specific C2-C4 product distribution
• High sulfur content
– JP-8 may contain up to 3,000 ppmw sulfur
• Significant concentration of aromatics
– Typically precursors to carbon coking
Hydrocarbon Type JP-8 (%)
Paraffins 71
Alkylbenzenes 19
Naphthalenes 6.2
Olefins 3.5
Balance 0.3
SS
Benzothiophenes
Dibenzothiophenes
Dodecane C12H26 22.5%
Tetradecane C14H30 16.9%
Decane C10H22 16.1%
Hexadecane C16H34 12.2%
Source: Air Force, 1991.
Most prevalent constituents:
JP-8 Composition
26
27
Discovery Approach
Theory inputPrimary
screen thin film libraries
Screening of “real”
catalysts
Process optimization & scale-up
Catalyst Parameter Space
Preparation:
Synthesis
Weight loading
Calcination
Materials:
Active metal
Precursor
Support
Testing:
Temperature
Concentration
Time on Stream
Primary Optical Screen
Expose to JP-8
Darkening Carbon coating
Activity
Optical measurements
Al2O3 SiO2
Substrate
Sample Synthesis
J. Hattrick-Simpers, K. Yang, J. Bedenbaugh, M. Peralta, K.Bunn, J.Lauterbach, ACS Combinatorial Science, 2013
Al2O3-SiO2 Thin Film at 450oC
Raw Image
1 hr Video (accelerated)
Ni
referenceSubstrate
heater
SiO2 Al2O3
29
5% Rh/Al2O3 T = 650oC
CH4
Hydrocarbons
GC-MS Analysis
31
Compound Formula Ret. time
(min)
BP
(oC)
Gas density (20oC, 1
atm)
Methane CH4 8.7 -164 0.67 kg/m3
Ethylene C2H4 12.3 -104 1.17 kg/m3
Ethane C2H6 13.6 -89 1.26 kg/m3
Propylene C3H6 19.0 -47 1.78 kg/m3
Propane C3H8 19.5 -42 1.87 kg/m3
1-Butene C4H8 23.4 -6.3 2.40 kg/m3
Butane C4H10 23.8 -0.5 2.50 kg/m3
JP-8 Conversion to LPG (mass basis)
= kg C2-C4 out / kg JP-8 in (%)
Reaction Conditions:
• 5% JP-8
• Balance He
• 100 sccm total flow
per reactor channel
• Catalyst pretreatment
for ~3 hours at 450oC
32
Metals Supported on γ-Al2O3
Activity Screen
550 600 6500
2
4
6
8
10
kg C
2-C
4 o
ut / kg J
P-8
in (
%)
Temperature (oC)
La-doped Al2O
3
1% Pt / Al2O
3
-Al2O
3
1% Ir / Al2O
3
1% Pd / Al2O
3
1% Ru / Al2O
3
1% Rh / Al2O
3
Methane Ethylene Ethane Propylene Propane 1-Butene Butane0.0
0.5
1.0
1.5
2.0
2.5
kg o
ut
/ kg J
P-8
in (
%)
-Al2O
3
1% Pt/Al2O
3
La-Al2O
3
-Al2O
3
Product Distribution – Al2O3
Sample Conv.
γ-Al2O3 7.3%
1% Pt / Al2O3 7.7%
La-Al2O3 9.7%
α-Al2O3 4.2%
33
T = 650oC
Temp. Conv.
MFI 8.7%
γ-Al2O3 7.3%
MFI at 350oC
γ-Al2O3 at 650oC
34
MFI Zeolites
Product Comparison – γ-Al2O3 vs. MFI
C1 C2 C3 C40.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
kg o
ut
/ kg J
P-8
in (
%)
MFI
-Al2O
3
JP-8 Cracking on ZSM-5
35
350400
450500
550
0
5
10
15
20
25
20
30
40
50607080
LP
G Y
ield
(M
ass%
)
SiO
2:A
l 2O
3 R
atio
Temperature ( oC)
5 10 15 200
2
4
6
8
10
12
14
16
18
20
22
kg
C2-C
4 o
ut
/ kg
JP
-8 in
(%
)
Time on Stream (hr)
ZSM-5, 30:1
ZSM-5, 50:1
36
Catalyst Deactivation
Fresh
sample
Spent
sample
T= 550oC Reaction Conditions:• 5% JP-8
• Balance He
• 100 sccm total flow
per reactor channel
• Catalyst pretreatment
for ~3 hours at 450oC
1 2 3 4 5 6 7 8 9 10 11 12 13 140
5
10
15
20
25
kg C
2-C
4 o
ut / kg J
P-8
in (
%)
Reaction Cycle
Pt-Gd-ZSM-5, 50:1
ZSM-5, 50:1
37
Cyclic Regeneration
T = 450oC
Reaction Conditions:
• ~5% JP-8
• Balance He
• 100 sccm total flow
per reactor channel
• Catalyst pretreatment
for ~3 hours at 450oC
• Regeneration with
air for 1 hour at
450oC between each
successive 5 hour
reaction cycle
TPO • 10 sccm total flow
• 10% O2 Balanced with He
• Ramp rate: 20oC/min
• Oxidation Temperature:
25oC~800oC
400 500 600 700 800 900 1000 1100
Temperature (K)
ZSM-5
Gd/ZSM-5
Pt/ZSM-5
Pt-Gd/ZSM-5
39
Summary JP-8 Cracking
0
5
10
15
20
25 Zeolites
Ion-exchaged zeolites
Impregnated zeolites
Impregnated oxides
Oxides
kg
C2-C
4 o
ut
/ kg
JP
-8 in
(%
)
Sample - Worst to Best
68.3%
64.4%
62.8%
52.6%
39.8%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
450 400 450 500 550
Temperature (°C)
Product distribution
Butane
1-butene
Propane
Propylene
Ethane
Ethylene
Diesel Cracking
JP-8
• Reaction T: 400oC~550C
• Catalyst: HZSM-5 3g
• No Carrier gas, No recycling
• WHSV=10h-1,
Diesel
30.8%
15.7%
21.6%
24.1%26.1%
10%
15%
20%
25%
30%
35%
40%
350 400 450 500 550
kg
C2
-C4 o
ut
/ kg
JP
-8 i
n (
%)
Temperature (°C)
Diesel cracking
JP-8
Diesel
• HT helped to systematically study complex a
parameter space in a reasonable time
• Synthesized and screened ~ 800 catalysts at a
variety of conditions in less than 10 months
• Keep an open mind and don’t always trust prior
“knowledge”
• Computation did not generate any useful leads
41
Conclusions
Example II: NOx SCR
42
4NH3 + 4NO + O2 ----> 4N2 + 6H2O
4NH3 + 2NO2 + O2 ----> 3N2 + 6H2O
http://upload.wikimedia.org/wikipedia/en/5/5c/SCR2.GIF
Typical SCR Unit for Coal Fired Power Plant
43http://ect.jmcatalysts.com/diesel-emission-control-coal-power-plants
http://www.alliantenergy.com/AboutAlliantEnergy/EnvironmentalCommi
tment/PerformanceAndCompliance/030357
Current Commercial SCR Catalysts
1. Selectivity
SO2 Oxidation:
2SO2 + O2 ----> 2SO3
Ammonium Sulfates (T 4N2O + 6H2O
T > 400 ˚C
2. Ammonia Slip
3. Operating Temperature Window
4. Fly-ash plugging20 µm
EDAX
44
Carbon, Silica (20-60 wt%)
CaO(5-30 wt%)
Fe2O3 (10-40 wt%)
Alumina (5-35 wt%)
5. Low mechanical endurance
6. Chemical catalyst deactivation
2 µm
Substrate: Cordierite (2MgO•2Al2O3•5SiO2)
Fresh V2O5+WO3/TiO2 Catalyst
CaSO4 can formed from the reaction
between SO3 and CaO on the catalyst
Decrease in Bronsted acidity
Multi-pollutant SCR Catalysts
▪ NOx reduction >90%
▪ < 5ppm NH3 slip
▪ Wide operating temperature
▪ Long-term stability
▪ Lower SO2 conversion
▪ Hg˚ oxidation
45
Small-pore3-4 Å
SSZ-13, SAPO-34
Large-pore7.4-15 Å
Zeolite Y, Beta
Meso-pore5.5-7 Å
ZSM-5, MOR
Primary Screen in HT Reactor
46
Reactan
t
Reaction Conditions•Atmospheric pressure•150oC to 500oC, 50oC increments•500ppm NO, 500ppm NH3, 10% O2, and
balance N2•GHSV = 42,500 mL/(hr*gcat) 16-way Flow split
Effluen
t
Individual temperature monitoring
16 stainless steel reactor tubes
Capillaries
Carrier gas
Heated mixer with high internal
surface area
H2O Dosing Cell
• 500 ppm NO, 500 ppm NH3, 10% O2 and bal N2
D.W. Fickel et al./Applied Catalysis B: Environmental 102 (2011) 441-448
47
Primary Screen – Representative Results
Acid forms of zeolites vs. Cu exchanged zeolites
• Hydrothermal aging - de-alumination occurs above 700˚C:
– Loss of Al(OH)3 = loss of Bronsted acid sites = loss in activity
– Copper migration and formation of clusters
D.W. Fickel et al./Applied Catalysis B: Environmental 102 (2011) 441-448
48
Hydrothermal Stability
Cu-ZSM-5 / Cu-SSZ-13 SCR Deactivation
49
Cu-ZSM-5 before (a) and after (b) hydrothermal treatment,
Cu-SSZ-13 before (c) and after (d) hydrothermal treatment
D.W. Fickel et al. Applied Catalysis B: Environmental 102 (2011) 441.
(a) (b)
(c) (d)
Secondary Screen - 8 Sample HT Reactor
50
NH3/N2
NO/N2
NO2/N2
O2/N2
CO2/N2
SO2/N2
Argon
HCl/N2
H2O
Stream
Selector
Capillary
Furnace
Mass
Spec
Heater / Mixer
Reactors
Sample
Exhaust
Peristalti
c
Pump
T >150˚C
N2
T>120˚C
Component NO NH3 O2 CO2 H2O SO2
Concentration
500
ppmv
500
ppmv
5
vol%
5
vol%
8
vol%
500
ppmv
Detection limit: < 25 ppm of NO
Both powder and
honeycomb
monolith samples
can be tested
GHSV: 40,000 hr-1
8-Channel High-throughput Reactor
Switching
Valve
Capillary
Furnace
Mixer
Peristaltic Pump
Mass Spec
Reactors
MFCs
51
52
Effective Metals for SCR
J. Am. Chem. Soc. 1999, 121, 5595-5596
• 1000 ppm NO, and NH3, 2%
O2 and balance He
• GHSV=4.6E5 1/h
• * detonates addition of 500
ppm SO2
Test Conditions
Activity
• Both Fe and Ce showed high
NO conversion at
temperatures above 400 ᵒC
• Ce-Fe-ZSM-5 did not get
poisoned by SO2 and
showed a lower activity for
SO2 oxidation to SO3
53
Morphology - SSZ-13
Si/Al = 7
Ion-exchanged SSZ-13
10 20 30 40
H-SSZ-13
Fe-SSZ-13
Ce-SSZ-13
Fe-Ce-SSZ-13
(401)
(220)
(104)
(211)
(003)
(021)(110)
Inte
nsi
ty (
a. u
.)
2
(101)
8.5 9.0 9.5 10.0 10.5
(10
1)
H-SSZ-13
Fe-SSZ-13
Ce-SSZ-13
Fe-Ce-SSZ-13
Inte
nsity a
.u.
2
54
Si/Al = 7
SCR of NOx - without H2O and SO2
150 200 250 300 350 400 450
0
20
40
60
80
100
Temperature (oC)
NO
Conver
sion (
%)
Cu-SSZ-13
Fe-SSZ-13
Ce-SSZ-13
Fe-Ce-SSZ-13
H-SSZ-13
• Cu-SSZ-13 shows the
best SCR activity over a
wide temperature window
• Fe-Ce-SSZ-13 has good
catalytic activity at high
temperature
55
NO NH3 O2 CO2
500
ppmv
500
ppmv
5
vol%
5
vol%
150 200 250 300 350 400 450
0
20
40
60
80
100
NO
Co
nv
ersi
on
(%
)
Temperature (oC)
Cu-SSZ-13
Fe-SSZ-13
Ce-SSZ-13
Fe-Ce-SSZ-13
Effect of H2O
• Cu-SSZ-13 still shows
the best SCR activity in a
wide temperature window
• Catalytic activity of
Fe/Ce-SSZ-13
decreased with water
addition
NO NH3 O2 CO2 H2O
500
ppmv
500
ppmv
5
vol%
5
vol%
8
vol%
Effect of H2O and SO2
150 200 250 300 350 400 450
0
20
40
60
80
100
NO
Co
nv
ersi
on
(%
)
Temperature (oC)
Cu-SSZ-13
Fe-SSZ-13
Ce-SSZ-13
Fe-Ce-SSZ-13
Commercial
• Catalysts are deactivated
possibly due to ammonium
sulfate under 250oC ζ
• Cu-SSZ-13 shows the best
sulfur resistance at 250oC
57ζEnviron. Sci. Technol., 47, 5294–5301(2013), J. Catal. 186, 254–268 (1999), J. Catal. 188, 332 (1999)
NO NH3 O2 CO2 H2O SO2
500
ppmv
500
ppmv
5
vol%
5
vol%
8
vol%
500
ppmv
Conversion Comparison
250 C Just CO2 + H2O + H2O and SO2
Cu 100 100 71
Fe 82 78 30
Ce 20 11 0
Fe/Ce 97 48 22
58
450 C Just CO2 + H2O + H2O and SO2
Cu 100 100 100
Fe 94 98 100
Ce 100 62 9
Fe/Ce 100 80 88
XPS of S 2p
173 172 171 170 169 168 1670
60
120
180
Counts
(a.
u.)
Binding Energy (eV)406 405 404 403 402 401 400 399 3980
90
180
270
360
Counts
(a.
u.)
Binding Energy (eV)
XPS of N 1s
62%38%
• 0.39% S and 1.38% N (atomic conc. %) are detected
• SO42- (shifted above 168 eV)
• NH4+ form on the surface of the catalyst, possible compounds:
• (NH4)2SO4 at around 400.5 eV
• NH3 absorbed on the Bronsted acid site at around 402.7 eV
XPS Analysis of S Deactivated Catalysts
59
NIST X-ray Photoelectron
Spectroscopy Database, NIST
Standard Reference Database
20, Version 4.1
Conclusions
• HTE has led to the discovery & optimization of
new stable SCR catalysts not based on Ti, Va,
and W
• Both Cu and Fe-SSZ-13 have excellent
resistance to H2O + SO2 above ~350oC
• Cu-SSZ-13 shows similar SCR activity in
comparison to the current commercial catalyst
• All catalysts are deactivated by SO2 at 250oC
and below
• NH4+ and SO4
2- form on the Cu-SSZ-13;
evidence for (NH4)2SO4 formation60
Example III: Catalyst performance via high-throughput /
statistical design methods:
▪ Tailoring of reactivity requires detailed understanding of the
interplay between synthesis parameters
▪ Employing high-throughput experimentation with data mining
tools permits mapping of the synthesis space onto
hydrogenation performance
Catalyst
performance
Activity
Selectivity
Stability
Catalyst
structureCatalyst
preparation
Method
Heating regimen
Pre-treatment
Reagents
Explore synthesis strategies for on-demand mixed-oxide catalyst reactivity for ethane to acidic acid and/or ethylene
Technical Information: prescriptive synthesis relationships for desired partial oxidation properties
Controlled nanomaterial synthesis improves catalyst performance
Requires detailed understanding of the synthesis parameter space
Background
Acid/base and redox properties:
• Acid/base sites for the
activation of ethane;
• Redox sites for the oxidation to
acetic acid;
Ruth, K., et al. (1998). Journal of Catalysis
175(1): 16-26.
Research Methods / Techniques
Data Mining AlgorithmsIn-situ FTIR, EXAFS, XRD,…
30 40 50 60 70 80
Theta(deg)
0
500
1000
1500
2000
2500
3000
Inte
nsity(C
ou
nts
)
71-1178> CoO - Cobalt Oxide(Major)
89-2803> CoO - Cobalt Oxide(Major)
(1
00
)
(0
0
2)
(2
0
0)
(2
2
0)
(1
0
1)
(1
02
)
(1
03
)
(1
10
)
71-1178 CoO hcp
89-2803 CoO cubic
TEMHT synthesis and screening
Cs2SO4-or- K2SO4
-or- Te(OH)6
(NH4)2PdCl4-or- Ti2(SO4)3
-or- NiSO4
(NH4)6Mo7O24C4H4NNbO9
VOSO4
Base Catalyst Composition
Synthesis Gel Composition
[Mo8V2Nb1]x[RrAa]z
Redox-Acid/Base Dopants
Hydrothermal Synthesis
5 Autoclaves
simultaneously
Hydrothermal Synthesis
175oC for 48hr
Dry-120oC
2hr
Calcine-
400oC 4hr
Dry/Calcine
Wash
H2O
Anderson-type heteropoly
molybdate1
• (NH4)3NbMo6H6O24 reacts with VOSO4forming Mo-V-Nb-O
• Dopants incorporate
into Mo-V-Nb-O
framework
1. Chen, N. F.; Oshihara, K.; Ueda, W.
Catalysis today 2001, 64 (1), 121-128
Base catalyst composition:
Mo8-V2-Nb1
Mo8-V2-Nb1 From Ruth
Mo8-V2-Nb0.75Te1.4 From Bergh
Mo8-V2-Nb0.96Pd0.004 From Linke
Mo8-V3.18-Nb1 From Roussel
• Ruth, K., et al. (1998). Journal of Catalysis 175(1): 16-26.
• Bergh, S., et al. (2003). Applied Catalysis A: General 254(1): 67-76.
• Linke, D., et al. (2002). Journal of Catalysis 205(1): 32-43.
• Roussel, M., et al. (2005). Catalysis Today 99(1–2): 77-87.
Design of Experiments - OutlineResearch hypotheses:
• Identify correlations between the elemental loadings of redox and
acid elements on a base Mo8-V2-Nb1 catalyst on product
distribution in ethane PO through the development of response
surface
• Elucidate multifactor correlations between catalyst composition,
structural parameters, and ethane PO by completing DOE/ANOVA
over multiple responses
Parameter space for 3 level – 4 factor full factorial design (34)
Factor Variable Type Low Center Point High
A: Redox element (R) Categorical Pd Ni Ti
B: Acid/base element (A) Categorical K Cs Te
C: Dopant to host ratio (y/x) Numerical 0.005 0.5 1
D: Redox to acid ratio (r/a) Numerical 0.005 0.5 1
Catalyst composition: [Mo8V2Nb1]x[RrAa]y
PdK PdCs PdTe NiK NiCs NiTe TiK TiCs TiK
R/A=0.005
D/H=0.0051 10 19 28 37 46 55 64 73
R/A=0.005
D/H=0.52 11 20 29 38 47 56 65 74
R/A=0.005
D/H=13 12 21 30 39 48 57 66 75
R/A=0.5
D/H=0.0054 13 22 31 40 49 58 67 76
R/A=0.5
D/H=0.55 14 23 32 41 50 59 68 77
R/A=0.5
D/H=16 15 24 33 42 51 60 69 78
R/A=1
D/H=0.0057 16 25 34 43 52 61 70 79
R/A=1
D/H=0.58 17 26 35 44 53 62 71 80
R/A=1
D/H=19 18 27 36 45 54 63 72 81
Design of Experiments Standard Orders: [Mo8V2Nb1]H[RRAA]D
EDS – Catalyst Composition • 81 samples x 3 scans each• Scaled to Mo and error analyzed
EDS composition of Mo8V2Nb1R0.25A0.25samples
Target loading
XRD
• Responses analyzed (based on 22° peak):
• Crystallite size
• D-spacing, indicative of MoVNb lattice doping
• Abundance of secondary phases
XRD of Mo8V2Nb1R0.25A0.25 samples
XRD Grain Size DOE Analysis
Summary
Model p-value 0.000
R-squared 91.73%
A: Redox element
B: Acid/base
element
C: Dopant to host
ratio
D: Redox to acid
ratio
Redox Element NiAcid/Base Element K
Hold Values
Redox/Acid ratio
Do
pan
t/H
ost
rati
o
1.00.90.80.70.60.50.40.30.20.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
> – – – < 280
280 290290 300300 310
310
XS22deg
Contour Plot of XS22deg vs Dopant/Host ratio, Redox/Acid ratioGrain Size - MoVNbNiK
Redox Element NiAcid/Base Element K
Hold Values
Redox/Acid ratio
Do
pan
t/H
ost
rati
o
1.00.90.80.70.60.50.40.30.20.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
> – – – < 280
280 290290 300300 310
310
XS22deg
Contour Plot of XS22deg vs Dopant/Host ratio, Redox/Acid ratio
Redox Element PdAcid/Base Element K
Hold Values
Redox/Acid ratio
Do
pan
t/H
ost
rati
o
1.00.90.80.70.60.50.40.30.20.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
> – – – < 240
240 250250 260260 270
270
XS22deg
Contour Plot of XS22deg vs Dopant/Host ratio, Redox/Acid ratio
Redox Element PdAcid/Base Element K
Hold Values
Redox/Acid ratio
Do
pan
t/H
ost
rati
o
1.00.90.80.70.60.50.40.30.20.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
> – – – < 240
240 250250 260260 270
270
XS22deg
Contour Plot of XS22deg vs Dopant/Host ratio, Redox/Acid ratioGrain Size - MoVNbPdK
Redox Element TiAcid/Base Element K
Hold Values
Redox/Acid ratio
Do
pan
t/H
ost
rati
o
1.00.90.80.70.60.50.40.30.20.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
> – – – – < 180
180 210210 240240 270270 300
300
XS22deg
Contour Plot of XS22deg vs Dopant/Host ratio, Redox/Acid ratio
Redox Element TiAcid/Base Element K
Hold Values
Redox/Acid ratio
Do
pan
t/H
ost
rati
o
1.00.90.80.70.60.50.40.30.20.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
> – – – – < 180
180 210210 240240 270270 300
300
XS22deg
Contour Plot of XS22deg vs Dopant/Host ratio, Redox/Acid ratioGrain Size - MoVNbTiK
Redox Element PdAcid/Base Element Te
Hold Values
Redox/Acid ratio
Do
pan
t/H
ost
rati
o
1.00.90.80.70.60.50.40.30.20.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
> – – – – – – < 220
220 230230 240240 250250 260260 270270 280
280
XS22deg
Contour Plot of XS22deg vs Dopant/Host ratio, Redox/Acid ratio
Redox Element PdAcid/Base Element Te
Hold Values
Redox/Acid ratio
Do
pan
t/H
ost
rati
o
1.00.90.80.70.60.50.40.30.20.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
> – – – – – – < 220
220 230230 240240 250250 260260 270270 280
280
XS22deg
Contour Plot of XS22deg vs Dopant/Host ratio, Redox/Acid ratioGrain Size - MoVNbPdTe
Ethane Partial Oxidation T=450oC
78
2023
26
36
118
11
20
2935
38
8
30 2923
26
3632
2722
28
39 38
1821
2935
20 19 18 18
2522 20
23
8
10
1
14
11
3212
1
1
9
31
11 14 26 21
8
924
16
16
1111
2312
13
13
27
15 16 15
1923 27 19
36
3
15
3 26
23
16
23
2
2
314
169
18
8
2 10
12
21
16
11
7 23
26 6
4
18
25 2321
2318
20
19
26
1
2
4
3
2
3
1
2
2
2
2
5
2
2
2
4
1
2
7 6
5
26
11
2
1 2
2
6
2
2
1
1
Base5 10 17 31 34 35 45 13 14 6 19 21 26 27 24 9 22 20 46 73 4 1 41 42 2 23 29 28 37 38 36 33 30 32
0
10
20
30
40
50
60
70
80
90
100
Yie
ld (
%)
Sample
CH4 Yield
AA Yield
CO Yield
Ethylene Yield
CO2 Yield
GHSV: 1200 h-1
Pressure: 1 bar
Temperature 450 ±10oC
Catalyst: 2.0 g
Flow rate: 40 ml min-1
Ethane to O2 ratio: 4:5
EPO Temperature Optimization
79
0
31
212525
3432
21
51
12
39
1 001 20 10
17
11
17
2024 6924
21
13
15
11
52
915
17
4710
0
10 15
2011
2
10
20
9
2
9
11
11
1
2
4
0
11
4 2
2
2
2
4
4
2
2
2
5
5
3
2
2
2
7
72
1 19 20 21 22 24 26 27 28 29 30 33 36 37 4 41 42 46 73 9
0
10
20
30
40
50
60
70
80
90
100
Yie
ld (
%)
Sample
AA Yield
CH4 Yield
CO Yield
Ethylene Yield
CO2 Yield
GHSV: 1200 h-1
Pressure: 1 bar
Catalyst: 2.0 g
Flow rate: 40 ml min-1
Ethane to O2 ratio: 4:5
EPO Temperature Optimization
80
1
54
38 3740
78
58
31
15
6
33
59
23 3 2 47 5 6
97
20
31 30
39
14
17
35
58 73
39
17
7277 76
33
45
71
4436
2
18 28 30
18
5
1729
24 1024 16
8
98
4
7
16
10
11
83 33 4
864
125
8
1911 13
61
44
6
4147
1 19 20 21 22 24 26 27 28 29 30 33 36 37 4 41 42 46 73 9
0
10
20
30
40
50
60
70
80
90
100S
ele
ctivity (
%)
Sample
AA
CH4
CO
C2H
4
CO2
81
Example - NH3 Decomposition
82
250 300 350 400 450 500 550 600
40
60
80
100
% N
H3 C
on
vers
ion
T[oC]
Equilibrium, P=1atm
Current catalyst1
1. S. Yin, et al. App. Catal. A: General, 2006
NH3 (g) 1/2 N2 (g) + 3/2 H2 (g)
∆Hrxn = 46 kJ/mol
83
Effect of Metal
100 200 300 400 500 600
0
20
40
60
80
100%
NH
3 C
on
ve
rsio
n
Temperature [oC]
Ru
Ir
Rh
Pd
Pt
84
Promotional Effect of Alkaline Metals
200 250 300 350 400 450 500
0
10
20
30
40
50
60
70
80
90
100
Catalysts Prepared using H2O
Inlet Feed: 100 sccm of 10% NH3 in He
% N
H3 C
on
vers
ion
T[C]
4 wt Ru/12 wt% K
4 wt% Ru/12 wt% Rb
4 wt% Ru/12 wt% Na
4 wt% Ru/12 wt% Cs
4 wt% Ru
200 250 300 350 400 450 500
0
20
40
60
80
100
NH
3 C
on
vers
ion
T[oC]
0%
6%
12%
18%
24%
30%
Optimizing K-Promotion
• SVNH3=4000
mL/(gcat*hr)
• 12% is optimal
K loading for
4wt% Ru.
85
K-Promotion: Effect on Morphology
0
20
40
60
80
% N
H3 C
on
vers
ion
4Ru
4Ru/12K
4Ru / γ-Al2O3
W. Pyrz, R. Vijay, J. Binz, J. Lauterbach, and D. Buttrey, Topics in Catalysis (2008)
T = 350oC
1 μm
4Ru-12K / γ-Al2O3
86
Structural Analysis of Nanowhiskers
87
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
0
100
200
300
400
500
600
O
C
AlCu
K
Ru
RuCo
un
ts
Energy (keV)
Ru
Alkali Ru Hollandite
• Electron diffraction
shows that whiskers
are KRu4O8.
• K large tunnel ions.
• Ru cations located in
oxygen-octahedron.
K O Ru
9.880 A
88
4Ru/12K, after 1 hour reaction
1 μm
Active Catalyst in the SEM
Post-Reaction Analysis
9030 40 50 60
Inte
nsi
ty (
a.u
.)
2
-Al2O3
KRu4O8 (040)
KCl, associated with the promoter
Ruo (101)
4Ru/12K, after reaction
4Ru/12K, after 1 hour
H2 treatment, 450oC
4Ru/12K, after 3 hour
Calcination, 550oC
TEM Analysis
(a) Catalyst after 15 min in H2,
(b) interplanar spacing corresponding to Ru(100)
(c) Ru particle residing on Ru nanowire
(d) polycrystalline Ru nanoparticles on catalyst after 45 min
(e) crystalline Ru nanowire on catalyst after 60 min in H2(f) FFT of (e) showing crystallinity
Structure Sensitivity of NH3 Decomposition
92
nanoparticle catalysts (1-10 nm)1 < Ru crystallites (~20 nm)
nanowiresliterature
1Yin, et al., J. Catal., 2004
Li, et al., Carbon, 2007
Karim, et al., JACS, 2009
Simulated Ru particle2
Reaction type Catalyst design goal
Structure Insensitive Maximize surface atoms
Structure Sensitive Maximize active sites
up to 1x109 times
faster reaction rate
on steps3
Step atoms
High Resolution TEM investigation of nanowire structure
2Honkala, et al., Science, 2005
Step edges giving rise
to B5-sites in red
3Dahl, et al., Phys. Rev. Lett., 1999
Grain boundary
between crystallites
2Honkala, et al., Science, 2005
20 nm
9393
0 1 2 3 4 5
260
280
300
320
340
360
380
400
420
440
% Co Loading
T [C
] 0
5.000
10.00
15.00
20.00
25.00
30.00
35.00
Dependence on Co and T
Model Predictions - Long Cycle NOx Storage
NOx storage = f(Pt,Ba,Co,Rh,T)
Rxn. conditions
NO = 0.15%
O2 = 6% or 0%
CO = 0.9 %
C2H4=0.15%
0% Pt,15% Ba and 0% Rh
NOx Storage
9494
Term Coefficient
Constant 44.68
Pt 3.72
Rh 2.97
Ba 30.6
Co -1.05
T -2.69
Pt*Pt -12.63
Rh*Rh -7.93
Ba*Ba 9.34
Co*Co -14.38
T*T -24.06
Pt*Ba 13.19
Pt*T -7.12
Rh*Ba 9.54
0 20 40 60 80 100
0
10
20
30
40
50
60
70
80
90
100
Model P
redic
ted N
Ox s
tora
ge [10
-6 m
ole
s N
Ox]
Experimental NOx Storage [10
-6 moles NO
x]
Model development points
Validation points
Model Prediction vs. Experimental Values
Optimum Catalyst Composition 1.4Pt/0.9Rh/4Co/23Ba
All catalyst loadings are actual loadings
9595
Traditional Materials - Pt/Ba
0 2 4 6 8 10 12 14
0.0
0.2
0.4
0.6
0.8
1.0
Ba [% w/w]
Pt [%
w/w
]
0
5
10
15
20
25
30
35
40
[* 1
0-6 m
ole
s N
Ox]
Reaction
Conditions:
0.14% - NO
6.0 % - O2
0.9 % - CO
0.15% - C2H4
648 K
Fe = 2.5 % w/w
Optimize
loadings
L. Castoldi, I. Nova, L. Lietti, P. Forzatti, Catal. Today 96 (2004) 43
* * **
9696
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
300
320
340
360
380
40015%Ba, 0% Co and Rh
Pt Loading
Tem
pe
ratu
re [oC
]
10.0015.0020.0025.0030.0035.0040.0045.0050.0055.0060.0065.0070.0075.00
NOx storage
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
300
320
340
360
380
400
Pt Loading
Te
mp
era
ture
[oC
]
10.0015.0020.0025.0030.0035.0040.0045.0050.0055.0060.0065.0070.0075.00
1%Co, 15%Ba and 0%Rh
NOx storage
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
300
320
340
360
380
400
Pt Loading
Te
mp
era
ture
[oC
]
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
50.00
55.00
60.00
65.00
70.00
75.00
NOx storage
2.5%Co, 15%Ba and 0%Rh
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
300
320
340
360
380
400
Pt Loading
Te
mp
era
ture
[oC
]
10.0015.0020.0025.0030.0035.0040.0045.0050.0055.0060.0065.0070.0075.00
5%Co, 15%Ba and 0%Rh
NOx Storage: effect of Co loading
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
300
320
340
360
380
400
Pt Loading
Te
mp
era
ture
[oC
]
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
50.00
55.00
60.00
65.00
70.00
75.00
NOx storage
4%Co, 15%Ba and 0%Rh
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
300
320
340
360
380
400
Pt Loading
Tem
pe
ratu
re [oC
]
10.0015.0020.0025.0030.0035.0040.0045.0050.0055.0060.0065.0070.0075.00
5%Co, 15%Ba and 0%Rh
TST
DFT
BOC
Elementary Reaction Mechanism
Reactor Model
Quantitative, Parallel HTE
Design of Experiments Model Optimization
Model Validation
HTE – Kinetic Modeling
97
Ammonia Decomposition
• Synthesis Model1
– Developed for Ammonia Synthesis
• No Interaction Model2
– Developed for Ammonia Decomposition
– Utilizes Bond Order Conservation (BOC) to calculate activation energies
• Interaction Model2
– Incorporates N* - N* interactions
– Incorporates coverage depended activation energies
1Hinrichsen, O. Catalysis Today 53 (1999) 1772Mhadeshwar, et al., D.G. Catalysis Letters 96 (2004) 13
**
2
*
3 * HNHNH
***
2 * HNHNH
*** * HNNH
*2)(2 2* gHH
*2)(2 2* gNN
*
33 *)( NHgNH
98
0 20 40 60 80 100
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0Co
vera
ge F
ract
ion
Predicted Ammonia Conversion
Synthesis H*
Synthesis N*
Interaction H*
Interaction N*
No N-N Interaction H*
No N-N Interaction N*
Predicted Surface Coverages
Kinetic parameters from
literature and DFT
• Two models predict low H* and very high N* coverages– H2 adsorption blocked
• Interaction model– Repulsive N*-N* interactions decrease N* coverage
– Increased H* coverage – favors NH*+H* -> NH2– Hydrogen inhibition effect 99
Catalyst Preparation & Characterization
• Synthesized via incipient wetness– RuCl3 xH20 (Strem Chemical)
– γ-Al2O3 (Catalox Sba-200, 200 m2/g)
• Calcination at 823 K in dry air
• Oxidized and reduced in situ prior to reaction
• Dispersion and surface area measured with CO pulse chemisorption
• Reactor model parameters experimentally measured
Nominal (w/w) Dispersion Surface Area
1% Ru/Al2O3 6.59% 0.37 m2/g
2% Ru/Al2O3 9.08% 1.08 ± 0.45 m2/g
3% Ru/Al2O3 7.55% 1.34 ± 0.19 m2/g
4% Ru/Al2O3 5.89% 1.40 ± 0.35 m2/g
6% Ru/Al2O3 4.42% 1.57 ± 0.57 m2/g 100
Experiments – Hydrogen Addition
3%(w/w) Ru / γ-Al2O3
10/90 NH3/He
10/20/70 NH3/H2/He
P = 1.05 bar
SA/g = 1.34 m2/g
GHSV = 30,000 mL/h/gcat
620 640 660 680 700 720 740 760 780 8000
10
20
30
40
50
60
70
80
90
100
Convers
ion (
%)
Temperature (K)
101
Synthesis Model – Hydrogen Addition
3%(w/w) Ru / γ-Al2O3
10/90 NH3/He
10/20/70 NH3/H2/He
P = 1.05 bar
SA/g = 1.34 m2/g
GHSV = 30,000 mL/h/gcat
620 640 660 680 700 720 740 760 780 8000
10
20
30
40
50
60
70
80
90
100
Convers
ion (
%)
Temperature (K)
102
No Interaction Model – Hydrogen Addition
3%(w/w) Ru / γ-Al2O3
10/90 NH3/He
10/20/70 NH3/H2/He
P = 1.05 bar
SA/g = 1.34 m2/g
GHSV = 30,000 mL/h/gcat
620 640 660 680 700 720 740 760 780 8000
10
20
30
40
50
60
70
80
90
100
Convers
ion (
%)
Temperature (K)
103
Interaction Model – Hydrogen Addition
3%(w/w) Ru / γ-Al2O3
10/90 NH3/He
10/20/70 NH3/H2/He
P = 1.05 bar
SA/g = 1.34 m2/g
GHSV = 30,000 mL/h/gcat
620 640 660 680 700 720 740 760 780 8000
10
20
30
40
50
60
70
80
90
100
Convers
ion (
%)
Temperature (K)
104
Weight Loading
620 640 660 680 700 720 740 760 780
0
10
20
30
40
50
60
70
80
90
100
Am
mo
nia
Co
nver
sio
n (
%)
Temperature (K)
620 640 660 680 700 720 740 760 780
0
10
20
30
40
50
60
70
80
90
100
Am
mo
nia
Co
nver
sio
n (
%)
Temperature (K)
620 640 660 680 700 720 740 760 780
0
10
20
30
40
50
60
70
80
90
100
Am
mon
ia C
on
ve
rsio
n (
%)
Temperature (K)
6% Ru4% Ru
2% Ru 1% Ru
10 v/v%
NH3/He620 640 660 680 700 720 740 760 780
0
10
20
30
40
50
60
70
80
90
100
Am
monia
Convers
ion (
%)
Temperature (K)
105
0 20 40 60 80 100
0
20
40
60
80
100P
redic
ted A
mm
on
ia C
on
ve
rsio
n
Experimental Ammonia Conversion
6% Ru/-Al2O
3
4% Ru/-Al2O
3
3% Ru/-Al2O
3
2% Ru/-Al2O
3
1% Ru/-Al2O
3
Putting all Data Together
Data used for model development
106
