Post on 29-Jun-2020
transcript
Mechanocatalytic Depolymerization
of Lignin
Carsten Sievers
March 7, 2017
Atlanta, GA
Sievers Research Group
Email: carsten.sievers@chbe.gatech.edu
Phone: 404-385-7685, Fax: 404-894-2866
Catalytic Routes for Sustainable
Production of Fuels and Chemicals
SynthesisProcess
Development
Surface
Reactions
Characteri-
zation
Tailored active sites
Water-
tolerant solid acid
Multi-functional catalysts
Acidity / Basicity
Metal
particles
Porosity
Crystallinity
In-situ spectroscopy
Inter-
mediates
Reaction
pathways
Catalytic reactions
Reactor
design
Deactivation
R.M. Ravenelle et al., J. Phys. Chem. C 114 (2010) 19582.
R.M. Ravenelle et al., ACS Catal. 1 (2011) 552.R.M. Ravenelle et al., Top. Catal. 55 (2012) 162.
R.M. Ravenelle et al., ChemCatChem 4 (2012) 492.
Stability of Solid Catalysts in Hot Water
Objectives:
Understanding the pathways of catalyst deactivation in
hot liquid water
Elucidating the influence of biomass-derived
feedstocks on the stability of solid catalysts
Improving the hydrothermal stability of solid catalysts
using protective coatings and additives
Approaches:
Kinetic studies on transformations of solid catalysts in
hot water and solutions of oxygenates
Physicochemical characterization (N2 physisorption,
XRD, TEM, SEM, IR, NMR, XPS, titration)
Development of synthesis techniques for improving
hydrothermal stability
Performance studies with stabilized catalysts
2θ / °
ppm
ppm
t / h
t / h
PtAl3+ + H2O ↔ H+
O
H+ +H2
Cl
H
OH
Al
A.L. Jongerius et al., ACS Catalysis 3 (2013) 464.
M.W. Hahn et al., ChemSusChem 6 (2013) 2304.A.H. Van Pelt et al., Carbon 77 (2014) 143.
C. Sievers et al., ACS Catalysis 6 (2016) 8286.
J.R. Copeland et al., Langmuir 29 (2013) 581.
J.R. Copeland et al., Catal. Today 205 (2013) 49.J.R. Copeland et al., J. Phys. Chem. C 117 (2013) 21413.
Surface Chemistry of Oxygenates
Objectives:
Understanding surface interactions of biomass-
derived oxygenates in aqueous media
Identification of intermediates and reaction pathways
for reactions such as aqueous phase reforming and
hydrodeoxygenation (HDO)
Quantification of rates of individual reaction steps
Identification of active sites for specific reaction paths
Characterization of solvent effects
Understanding surface interactions in composite
materials
Approaches:
IR spectroscopy (in vacuum, vapor phase (≈1 atm),
and liquid phase)
NMR spectroscopy
Liquid phase adsorption isotherms
Raman spectroscopy
DFT calculations (in collaboration with David Sholl)
ATR IR setup for in-situ studies in liquid phase
under flow conditions Feed
InletEffluent
N2 Inlet
IR InletIR Outlet
TC
Heating
Element
Gasket
Window
IRE
Foo et al., ACS Catalysis 4 (2014) 3180.
C. Sievers et al., ACS Catalysis 6 (2016) 8286.
Glycerol on g-Al2O3
H1
C1
O3
H2
H3H4
H5
H6
H7
H8
C2C3
O1
O2
O4
Al1Al2
O4 O3
O2C1
C2
C3
Al1 Al2
H2
H5
H4
H7
H3
H8
H1 H6
a
b
Lactic Acid Production from Glucose
Objectives:
Understanding of interactions between catalysts
and reactants, intermediates, and products
Identification of structure-property relationships
Design of solid catalysts with high activity,
selectivity, and longevity
Development of a continuous lab-scale process
for lactic acid production
Understanding and mitigating the role of
impurities in feed solutions
Approaches:
Spectroscopic and modeling studies on surface
interactions of reactants and intermediates (in
collaboration with David Sholl)
Reactivity studies with well-defined
homogeneous catalysts (in collaboration with
Charles Liotta)
Synthesis and detailed characterization of solid
catalysts
Reactivity studies in a continuously operated
fixed bed reactor setup
Pressure Gauge
PID Controller
Fixed Bed Reactor
Quaternary HPLC Pump
Backpressure Regulator
16-Way Selector Valve
Albuquerque et al., ChemCatChem 9 (2017).
In-situ IR Studies of Deoxygenation Reactions
Objectives:
Identification of surface species and reaction
pathways in deoxygenation reactions with and
without hydrogen
Understanding pathways for coke formation and
deactivation
Elucidation of the role of specific active sites in
different reactions
Design of highly efficient deoxygenation catalysts
Approaches:
In-situ IR studies on time-resolved evolution of
surface species under reaction conditions
Complementary analysis of reaction products by
online mass spectrometry and offline GC-MS
Detailed physicochemical characterization of
catalysts
IR beam
Reactants
Products
1800 1700 1600 1500 1400 1300
1627
15951529
1491
1440
1380
Time
Ab
sorb
ance
/ a
.uWavenumber / cm-1
G.S. Foo, et al., ACS Catalysis 6 (2016) 1292.
Mechanocatalytic Depolymerization
of Lignin
Mechanocatalytic Reactions
Reactants, catalysts, and milling balls
are combined in a milling vessel.
No solvents are used during the
milling.
Separation of
products can
become more
efficient.
Q. Zhang, and F. Jerome, ChemSusChem 6 (2013) 2042.
milling balls
lignincatalyst
Catalytic Sites in Ball Milling
The rate of CO oxidation over a
Cr2O3 catalysts increased
dramatically when the shaker mill is
running.
The effect is completely reversibly and repeatable.
Milling creates short lived but highly
active catalytic sites.
S. Immohr, M. Felderhoff, C. Weidenthaler, F. Schüth, Angew. Chem. Int. Ed. 52
(2013) 12688.
CO + 1/2O2 CO2 over Cr2O3
Shaker Mill
Plug Flow Reactor
Shaker Mill
Hydrolysis of Carbohydrates
OH
OH
H
H
OHH
H
OH
O
O
OH
H
H
OH
OHHH
OH
O
HO
H
OH
H
H
OH
OHHH
OH
H2O
[H+]
OH
H
O
HO
H
OH
H
H
OH
OHHH
OH
Carbohydrates can be depolymerized by addition of water to the glycosidic bond.
Hydrolysis of carbohydrates is catalyzed by acids or enzymes.
Solid acid can be used to depolymerize cellulose in a ball mill.
Grinding provides intimate contact between reactant and catalytically active sites.
Water-soluble compounds are obtained as main products.
Dealuminated kaolinite is an efficient catalyst.
S.M. Hick, C. Griebel, D.T. Restrepo, J.H. Truitt, E.J. Buker, C. Bylda, R.G. Blair,
Green Chem. 12 (2010) 468.Blair, R. G.; Hick, S. M.; Truitt, J. H., US patent 8,062,428 (2011).
Mechanocatalytic Conversion of Cellulose
Lignin Structure
J. Zakzeski, P.C.A. Bruijnincx, A.L. Jongerius, B.M. Weckhuysen, Chem. Rev. 110
(2010) 3552.
Possible Products from Lignin
Benzene, toluene, xylene (BTX) are used in many
processes in the chemical industry.
For example terephthalic acid is produced from
p-xylene.
Phenol is used for the production of resins and adipic
acid (Nylon precursor).
Conversion of Lignin
J. Zakzeski, P.C.A. Bruijnincx, A.L. Jongerius, B.M. Weckhuysen, Chem. Rev. 110
(2010) 3552.
Lignin can be cracked over solid acid catalysts at
350 to 400 °C.
Initial conversion of non-volatiles to volatiles.
Volatiles can be further converted to light gases
and chars.
Moderate yields of valuable aromatics.
Strong bases catalyze hydrolysis of ether linkages.
Significant amounts of basic liquid waste are
formed.
Traditionally, few processes for the conversion of
lignin have been economically viable.
0100200300400500600700800900
0 100 200 300 400 500
Mn
(g/
mo
l)
Milling Time (min)
Methanol as Scavenger
pure lignin
with NaOH
with NaOH + CH3OH
Shaker mill
Steel balls
25 ml vessel
Room temperature
Frequency: 800 RPM
In the presence of NaOH the average molar mass
decreases rapidly in the first 15 minutes.
Methanol acts as a scavenger for reactive intermediates.
Without a scavenger, intermediates repolymerize.
lignin + NaOH lignin + NaOH + MeOH
pure lignin Analysis of lignin
linkage patterns was
performed via HSQC
2-D NMR
Spectroscopy.
By milling with NaOH
for two hours, 15% of
β-O-4 bonds were
cleaved.
Milling with NaOH
and MeOH resulted
in a 65% decrease of
β-O-4 bonds.
Methanol as Scavenger
Retention Time / min
Inte
nsity /
Mco
unts
1
2
3
4
5.0 7.5 10.0 12.5 15.0
GC-MS Analysis of Products
Organosolv lignin
Catalyst: NaOH
Shaker mill
Room temperature
Frequency: 800 RPM
Lignin to Adipic Acid
Project 1 advisors
Project 2 advisors
Project 3 advisors
Ceria-zirconia has oxygen vacancies that can bind oxygen
atoms from organic molecules.
This interaction enables hydrodeoxygenation reactions.
Catalyst: 0.5 g of Ce82
Temperature: 400 °C
Pressure: 1 bar
Hydrogen flow: 40 mL/min
Liquid flow: 0.001 to 0.08 mL/min
0.001 mL/min repeated
Total run time: ~ 72 hours
Ceria-Based HDO Catalysts
S.M. Schimming, O. LaMont, M. König, A.K. Rogers, A. D'Amico, M.M. Yung, C. Sievers,
ChemSusChem 8 (2015) 2073.
CexZryOz
HH
CexZryOz
CexZryOz
H H
H
+
+ H2
- CH3OH
-
Suggested HDO Reaction Paths
The fasted reaction is demethoxylation of guaiacol to phenol.
Ceria-zirconia has limited activity for converting phenol to benzene.
Cresol is formed by a transalkylation involving phenol.
S.M. Schimming, O. LaMont, M. König, A.K. Rogers, A. D'Amico, M.M. Yung, C. Sievers,
ChemSusChem 8 (2015) 2073.
OCH3
OH
OH
OH
OH
OH
CH3
Guaiacol Catechol
Benzene
Cresol
Phenol
OCH3
Anisole
Mechanocatalytic Hydrotreating
Metal sites can
dissociate molecular
hydrogen to atomic
hydrogen.
Atomic hydrogen
can spillover to
other sites.
W.C. Conner, J.L. Falconer, Chem. Rev. 95 (1995) 759.
Continuous Removal of Products
Small and deoxygenated lignin fragments are
volatile and can be removed as vapors.
Hydrogen can be separated from the products
using a condenser or membrane.
Ball mill
Condenser
Liquid
products
H2 recycle
H2 feed
Lignin feed
The addition of an inlet and
outlet to the milling vessel
allows for reactions under
gases other than air.
Mechanical energy input
could potentially drive
traditionally thermochemical
reactions, such as
hydrodeoxygenation (HDO).
Flow Reactor Design
Flow Reactor Design
50 mL milling vessel
Six milling balls (Ø = 25 mm)
Milling speed: 800 rpm
5.75 g Diphenyl Ether
0.25 g 5 wt% Pt/Al2O3
50.0 SCCM H2
Total molar yield
Dicyclohexylether Cyclo-
hexanol
Cyclo-
hexanone
Diphenylether
Acknowledgements
Alex Brittain
Andrew Tricker
Natasha Chrisandina
Rachel Cooper
Lucas Ferreira
Brandan Brown
Rohan Kadambi
Kara Yogan
Mariefel Olarte
John Cort
Matthew Realff
Valeria Thomas
Renewable Bioproducts Institute
Imerys
International Paper
NewPage
Acknowledgements