biomass characterization and organosolv pretreatment of acs conference march 20… · • high gas...

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Biomass Characterization and Organosolv Pretreatment of

Buddleja davidii

Bassem Hallac, Poulomi Sannigrahi, Yunqiao Pu, and Arthur Ragauskas

School of Chemistry and Biochemistry, Institute of Paper Science and Technology, Georgia Institute of Technology, Atlanta, GA

Michael Ray and Richard Murphy

Division of Biology, Imperial College London, UK

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Global Energy Challenge

•• Finite amount of fossil fuelFinite amount of fossil fuel•• IncreaseIncrease in the demand for energythe demand for energy

•• Doubling of energy use by 2050Doubling of energy use by 2050•• High gas pricesHigh gas prices

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Energy Alternatives?

•• NuclearNuclear•• ElectricElectric•• WindWind•• Solar Solar

•• GeothermalGeothermal

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Ragauskas et al. Science 311 (2006) 484-489

•• Renewable and Renewable and sustainable sustainable

energyenergy

•• Integrated BiorefineryIntegrated Biorefinery•• fuelsfuels•• powerpower•• materialsmaterials

Biofuels

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1st vs. 2nd Generation Bioethanol• First Generation:

– Corn or sugar cane• Has food-value• Requires agricultural land

• Second Generation:– Lignocellulosic biomass

• Has no food-value • Can grow on non-agricultural land

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Biomass• Lignocellulosic materials,

such as wood, used to produce bioethanol.

• The cell wall consist of three biopolymers:

• Cellulose• Hemicellulose• Lignin

www.genomics.energy.gov

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U.S. Biomass Distribution

http://genomics.energy.gov

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Buddleja davidii• Buddleja davidii is a shrub that originated in

China, but has been naturalized in different parts of the world, including the U.S.

• It has several attractive agro-energy features– a potential bioresource for biofuels

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Characteristics of B. davidii• This plant:

– Exhibits a very wide range of growth habitat – Has no food-value– Is perennial – Has moderate growth dimensions (1.8-3.7 m

tall and 1.2-4.6 m spread)

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Vigorous growth in open and poor soil

Growth in very poor sites

Growth in no soil at all

Growth Habitat

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384219Betula papyrifera (Birch)

274821Populus tremuloides (Aspen)

Hardwoods

274129Pinus strobus (Pine)

314127Picea glauca (Spruce)

Softwoods

343530Buddleja davidii

Hemicellulose (%)Cellulose (%)Lignin (%)Wood Species

Wood Macromolecules

Chemical Features of Buddleja davidii

Hallac et al. J. Agric. Food Chem. 57 (2009) 1275-128133000.45Spruce

25000.47Aspen

10000.55Buddleja davidii

DP of CelluloseCrystallinity Index of Cellulose

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Quantitative 13C NMR of Lignin

COOH

Substituted AromaticUnsubstituted

Aromatic

Aryl group

Cα Cβ Cγ

Methoxyl

1.17/aryl group

h:g:s = 0:81:19

p-hydroxyphenyl (h)guaiacyl (g), syringyl (s)

Hallac et al. J. Agric. Food Chem. 57 (2009) 1275-1281

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Aliphatic OH

Cyclohexanol

Condensed phenolic OH Noncondensed phenolic OH

4.51 mmol/g lignin

Quantitative 31P NMR of Lignin

COOH

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The Process of Bioethanol Production from Biomass


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Ethanol Organosolv Pretreatment

Pan et al. Biotechnology and Bioengineering 94 (2006) 851 - 861


Cooking

Ground wood• ethanol• water• H2SO4

Unwashed pulp

Filtration

Sampling liquor for furfural and HMF analysis

Spent liquor Dilution with water

Precipitation

Filtration

Precipitate Filtrate

Pulp

Warm aqueous ethanol washing

Ethanol washes

Washed pulp

Water-soluble fractionsugars

(monomers & oligomers)depolymerized ligninfurfural and HMFSolid fraction

celluloseresidual ligninresidual hemicellulose

Ethanol organosolv lignin fraction

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Pretreatment Results

651.50601953

501.75401802

501.25601801

Ethanol Concentration (%, v/v)

Sulfuric Acid (%, w/w oven-dried wood)

Time (min)Temperature (°C)Condition

From Condition 1 Condition 3

More delignification and carbohydrate hydrolysis/degradation

05

1015202530354045

KL Glu Xyl

Con

tent

(%)

UntreatedCondition1

Condition 2Condition 3

Solid Fraction

O

H

HO

H

HO

H

OHOHH

H

OH

• Increase in EOL Fraction• Increase in % Lignin in Water-Soluble Fraction• Increase in Furfural and HMF in WS Fraction

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Enzymatic Hydrolysis


Cellobiohydrolases:• act on the reducing ends of cellulose• contain catalytic domains and

carbohydrate-binding molecules

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Enzymatic HydrolysisCellulase = 20 FPU/g celluloseCellobiase = 40 IU/g cellulose

Why did condition 2 and 3 produce readily digestible substrates?

0

20

40

60

80

100

0 12 24 36 48 60 72Hydrolysis time, h

Cel

lulo

se-to

-glu

cose

con

vers

ion

yiel

d% Untreated

Condition 1

Condition 2

Condition 3

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Main Factors that Affect Enzymatic Hydrolysis

1. Lignin content

2. Hemicellulose content

3. DP of cellulose 4. Crystallinity of cellulose

0

20

40

60

80

100

0 12 24 36 48 60 72Hydrolysis time, h

Cel

lulo

se-to

-glu

cose

con

vers

ion

yiel

d% Untreated

Condition 1

Condition 2

Condition 3

05

1015202530354045

KL Glu XylC

onte

nt (%

)

UntreatedCondition1

Condition 2Condition 3

0.490.530.530.55Crystallinity index

4205309701000DP

Cellulose 3Cellulose 2Cellulose 1Untreated

Fraction of reducing ends Accessibility

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Solid-State CP/MAS 13C NMR Spectrum of B. davidii Cellulose

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To further understand the effect of cellulose

structure/characteristics on enzymatic hydrolysis


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Spectral Fitting for the C-4 Region of CP/MAS 13C NMR Spectrum of Cellulose


Iβ – monoclinic two-chain unit cell

Iα – one chain triclinic unit cell


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Ultrastructure of Cellulose• Upon extensive depolymerization

of cellulose (decrease in DP)

651.50601953

501.75401802

501.25601801

Ethanol Concentration

(%, v/v)

Sulfuric Acid

(%, w/woven-dried

wood)

Time (min)

Temperature (°C)

Condition

•decrystallization

•conversion from crystalline to para-crystalline cellulose

Cellulo

se I α+

βpa

ra-Crys

tallin

e

Cellulo

se

Amorpho

us

Cellulo

se

Rel

ativ

e In

tens

ity (%

)

0

10

20

30

40

50

60UntreatedCellulose 1Cellulose 2Cellulose 3

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Conclusions• Buddleja davidii has several unique features ranging from its distribution

and growth habitat to aspects of its composition.

• The presence of high lignin (30%) and hemicellulose (34%) content did not prevent the formation of readily hydrolysable substrates.

• The low DP of cellulose (1000) did not provide enough accessibility to cellulases, while the crystallinity index of 0.55 did not seem to have any influence on the enzymatic hydrolysis.

• Ethanol organosolv pretreatment was capable of producing digestible substrates by:1) Removing most of the hemicelluloses2) Mild delignification of the wood3) Reducing the DP of cellulose4) Converting the stable cellulose dimorphs (Iα/Iβ) to the easily degradable para-

crystalline and amorphous celluloses

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Acknowledgments • Institute of Paper Science and Technology

• The AtlanTICC Alliance program and the UK Office of Science and Innovation

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BiofuelsBiofuelsBiofuelsThe Fuel of the FutureThe Fuel of the FutureThe Fuel of the Future

biomass characterization and organosolv pretreatment of acs conference march 20… · • high gas...

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