Lignin Structure and Applications

Göran Gellerstedt

Wageningen 2011 H CO H3CO 3 OH HO O OH Lignin structure O HO HO OH H3CO CH OH H CO CH OH CH2OH 2 3 O2H OH O O H CO O 3 OH HO OCH 3 HO OH H3CO OH Lignin OH O O OCHOH H3CO OCH3 O 3 OCH H3CO O 3 OH H CO OH OH 3 O O H3CO 1OCH 2 3 3 H3CO OH CH2OH HO OH O Lignin PlantO Type p-Coumaryl alcohol Coniferyl alcohol Sinapyl alcohol HO HO OH O H3CO O OCH3 HO HO O HO H3CO H3CO HO Per cent OCH3 HO HO O OH O OH OH H3CO Coniferous; Softwoods <5 O>95 0 HO OH O OH O H3CO Eudocotyledonous; HardwoodsO O 0-8 25-50 45-75 HO H3CO OH O OCH H3CO Monocotyledonous; Grasses H CO 5-35 3 35-80 20-55 CHO H3CO 3 HO Lignin OH

Wageningen 2011 Lignin content in plants

Plant Lignin Content Scientific/Common Name Gymnosperms Picea abies, Norway spruce 28 " (compression wood) 39 Pinus sylvestris, Scots pine 28 Angiosperms - Eudicotyledons Betula verrucosa, Siver birch 20 Eucalyptus globulus, Blue gum eucalyptus 22 Populus tremula, European aspen 19 Angiosperms - Monocotyledons Saccharum species, Bagasse 14

Wageningen 2011 From biomass to liquid fuels in 2020 (5.38  43 Mtoe within EU)

Biodiesel Pulp

4 (+9) Mtoe

11 Mtoe Lignin 13 (+1) Mtoe DME, FT-diesel

Ethanol 5 Mtoe Hemicell.

Wageningen 2011 Current Biorefinery Activities (EU)

EuroBioRef 37.4 M€

suprabio Biomass – Processing – Lignin – Processing – surfactants 19.0 M€ emulsifiers antioxidants

Biocore CIMV-process – Lignin – resins, adhesives, … 20.3 M€

Wageningen 2011 Suggested uses for lignin

Phenols Fragmentation Vanillin Org. S-comp.

Macromolecule in Dispersants solution systems Emulsion stab.

Lignin Resins Macromolecule in Polyblends material systems Antioxidant Rubber reinf.

Energy

Wageningen 2011 Technical lignins

Commercial

• Lignosulfonates (softwood, hardwood) • Kraft lignins (softwood, hardwood) • Soda lignins (annual plants)

Pilot plant scale

• Organosolv lignins (hardwood, softwood) • Steam explosion lignins (annual plants) • Acid hydrolysis lignins (softwood)

Wageningen 2011 Compounds in spent sulfite liquor (kg/ton of pulp)

Component Spruce Birch Lignosulfonate, tot. 4801) 3701)

Mw > 5,000 245 55 Carbohydrates 280 375 - Arabinose 10 10 - Xylose 60 340 - Mannose 120 10 - Galactose 50 10 Ethanol - Glucose 40 5 Aldonic acids 50 95 Acetic acid 40 100 Extractives 40 40 Misc. compounds 40 60 1) calculated as lignin

Wageningen 2011 Lignosulfonate as dispersing agent (Borregaard – Lignotech)

Aq. lignosulfonate

Wageningen 2011 Compounds in kraft black liquor (kg/ton of pulp)

Component Pine Birch Lignin 490 330 Carbohydrate derived - Hydroxy acids 320 230 - Acetic acid 50 120 - Formic acid 80 50 Turpentine 10 - Resin and/or fatty acids 50 40 Misc. products 60 80

Wageningen 2011 Modern kraft pulping – A lignin out- take can be accepted

Pulpwood Fibre processing Pulp & paper

Black Recovery boiler liquor The LignoBoost process

Lignin Conversion Chemicals

Conversion Biofuels

Wageningen 2011 Precipitated kraft lignin

Carbon: 61-65% Hydrogen: 5-7% Oxygen: 28-30% Sulfur: 1-3% Ash: 0.2-0.4% Carbohydrates: 1-2%

Wageningen 2011 Bonding energies, kcal/mol

H 88 100 O 62 82

72 85

CH3 CH O 59 O H 99

Wageningen 2011 van Krevelen diagram showing different biomass and fossil materials

D, [H]

Wageningen 2011 Phenol from kraft lignin at 340-450 oC Theoretical: cat: Fe-oxide; Co-oxide; …

C8.35 H7.27 O1.89 S0.08 (OCH3)0.89 + 12.73H  C6H6O + 3.24(CH4) + 1.78(H2O) + 0.08(H2S) 560 kg/ton lignin

Product Volatiles  Water Neutrals Mono- High Mw Hydrogen o o C5H12 <240 C phenols >240 C

% by weight 25.2 17.9 14.0 37.5 11.1 5.7

CH3

CH3 CH3 CH3 CH3

CH3 CH3 OH OH OH OH OH OH OH OH H3C

Yield, %: 6 4 22 33 8 20 7

Ref: Huibers and Parkhurst Jr, 1983

Wageningen 2011 Kraft lignins; Analytical data

Functionality Spruce Birch E. globulus Aromatic OH, mmol/g 4.1 4.3 3.3 Aliphatic OH (total), mmol/g 3.1 1.7 1.5 Carboxyl groups, mmol/g 0.5 0.5 0.2

Molecular mass, Mw 4500 1600 2300

Polydispersity, Mw/Mn 4.5 3.6 4.3

o Glass transition temp. Tg, C 148 119 133 Free aromatic C5, mmol/g 3.1 1.2 n.a.

Wageningen 2011 Some lignin reactions

1) Lignosulfonates upgrading

Lignin sulfite dispersing agents 2) reactive aldehyde amine chelating agents Reactive OCH3 phenol adhesives position OH (Softwood) kraft lignin

3) Kraft lignin (low Mw-fraction) + polyol + isocyanate polyurethane

Wageningen 2011 Sulfomethylation of lignin

Lignin Lignin ~140 oC

+ NaHSO3 + CH2O NaO3S OCH3 NaOH C OCH3 H OH H OH

A maximum of ~2 mmol sulfonate groups/g of lignin can be obtained  ~33% reactive positions

Wageningen 2011 13C-NMR of tannin and lignin

B A Spruce tannin 160 150 140 130 120 110 ppm A B A OH RO OH B D OH

catechol OR resorcinol

160 150 140 130 120 110 ppm D RO OH Spruce lignin phloroglucinol C OCH3 C

O 160 150 140 130 120 110 ppm guaiacol Wageningen 2011 Reactivity towards formaldehyde

• Phloroglucinol: highly reactive • Resorcinol: intermediate • Catechol/phenol: low

Tannins are presently used as wood adhesives, lignins are not In the future, formaldehyde-free adhesives based on lignin might be developed

Wageningen 2011 Lignin  uniform reactivity

Wageningen 2011 Polyurethane from oxypropylated kraft lignin

O HO HO

O KOH OCN R NCO OCH3 O OCH3 OCH3 OH O O CH2O CH OH NH 2 R O HN O n

Wageningen 2011 Manufacturing process for CF

Starting material:

. Polyacrylonitrile (PAN; ~90% of CF) . Petroleum/coal pitch . Regenerated cellulose (rayon)

Wageningen 2011 Carbon fiber use ….towards the automotive industry

Driving force: lower price of CF

Advantage: lower weight of vehicle, less gas consumption

Wageningen 2011 Even a small lignin withdrawal can be interesting …

650,000 tonnes Lignin withdrawal of 10% … converted to of pulp yields 33,000 tonnes 16,000 tonnes of CF

…to support 160,000 cars with CF-composite (~40% replacement) Wageningen 2011 SEC of kraft lignins before/after fractionation

softwood E. globulus

SWL EL

SP5 EP5

SR5 ER5

dw/d log M dw/d log M log dw/d

0 1 2 3 4 5 6 0 1 2 3 4 5 6 log M (relative polystyrene) log M (relative polystyrene)

Wageningen 2011 Carbon fibre characteristics

Wageningen 2011 Conclusions

• Large quantities of lignins will be formed in future biorefineries • Most of the lignin will be used as internal process fuel or subjected to

gasification (CO + H2) • A partial out-take of (purified) lignin is technically feasible in different types of processes • Carbon fibre would be an interesting option but will require new knowledge about the structure-property relationship • Other uses: biofuels, adhesives and other polymers (esters, ethers, urethanes), BTX chemicals, activated carbon • There is still a long way to go …

Wageningen 2011