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