Reims -07 Lignin complexity: fundamental and applied issues Göran Gellerstedt

Reims -07 Content The lignin structure in wood Lignin chemistry in pulping Technical lignins

Reims -07 Content The lignin structure in wood Lignin chemistry in pulping Technical lignins

Reims -07 Spruce: C 9 H 8.62 O 2.48 (OCH 3 ) 0.94 Phenolic OH: 20-30% Birch: C 9 H 8.59 O 2.86 (OCH 3 ) 1.52 Phenolic OH: Milled Wood Lignin Ref., Adler, 1977

Reims -07 Monomer yield on thioacidolysis (theoretical: ~ mol/g)

Reims -07 Mechano-chemical cleavage of -O-4 structures in milling

Reims -07 SEC of thioacidolysis products from spruce, eucalyptus and birch wood

Reims -07 Endoglucanase (Novozyme 476) Action of urea - Breaks down the crystallinity of the cellulose by forming hydrogen bonds between the microfibrils - Dissolves any material containing > ~50% lignin - Removes enzyme contamination from the fibres Action of alkaline borate solution - Dissolves all remaining components Dissolution of wood/pulp fibres by the use of enzyme

Reims -07 Types of LCC isolated from spruce wood meal

Reims -07 DimerMonomer SEC of acetylated thioacidolysis products from spruce LCCs Xylan-rich LCC (40% lignin on wood) Glucomannan-rich LCC (48% lignin on wood) Wood Response

Reims -07 Suggested lignin structures in spruce wood Linear xylan-lignin Branched glucomannan-lignin

Reims -07 S/G ratios in hardwoods

Reims -07 G-units/S-units in white birch wood Ref. Saka and Goring, 1988

Reims -07 The lignin structure in hardwoods … contains a high proportion of S-units which results in a high percentage of linear lignin – unevenly distributed

Reims -07 MS-identification of lignin fragment from E. globulus lignin Evtuguin et al, 2003

Reims -07 Lignin in annual plants

Reims -07 Content The lignin structure in wood Lignin chemistry in pulping Technical lignins

Reims -07 Dissolution of lignin and carbohydrates in kraft pulping Residual lignin; removed by bleaching

Reims -07 Degree of delignification for different wood species

Reims -07 Kraft pulping of birch and E. globulus respectively to similar kappa numbers E. globulus Birch

Reims -07 -O-4 structures in wood and pulp based on thioacidolysis (birch and eucalyptus) Degradation product,  mol/g of lignin Klason lignin, %:

Reims -07 Size exclusion chromatography (SEC) of lignin degradation products (no ”residual lignin” present in wood) Methodology Thioacidolysis of wood/pulp Acetylation SEC in tetrahydrofuran

Reims -07 Suggested mode of formation of radical coupling products in kraft pulping

Reims -07 Principles in the steam explosion process (Conditions: ~ o C, 1-5 min)

Reims -07 Chemical composition before and after steam explosion Substantial removal of hemicelluloses and extractives: SO2SE > TwoSE > OneSE Spruce samples Birch samples

Reims -07 Lignin isolation yield (hardwoods) SO2SE > OneSE (missing lignin from aspen  highly soluble lignin) Birch samples Aspen samples

Reims -07 SEC of acetylated lignin from steam exploded aspen wood

Reims -07 Degradability by thioacidolysis/SEC analysis Condensation  less degradability Spruce

Reims -07 Degradability by thioacidolysis/SEC analysis, SE aspen SE SO2SE monomers

Reims -07 Steam explosion chemistry

Reims -07 Content The lignin structure in wood Lignin chemistry in pulping Technical lignins

Reims -07 Biomass tree showing the main chemical outlets Ref. Rintekno oy, 1984

Reims -07 Highest-value lignin uses to show greatest future rise (W. Glasser) As structure of lignin yields to advances in analytical techniques, new markets are projected in adhesives, foams, films, coatings and plastics Ref: C&EN 1984

Reims -07 The Biorefinery Concept Production of large volumes of ethanol will be necessary in a short term New separation process(es) for lignocellulosics required New chemistry based on carbohydrates will be developed Lignin for fuel – and for chemicals On a longer term, gasification of biomass to syngas (biodiesel) will be developed

Reims -07 Indicative targets for the share of biofuel in the EU 2005: 2% (not achieved) 2010: 5.75% (will probably not be achieved) : New energy policy document setting a minimum requirement at 10% by 2020

Reims -07 From biomass to liquid fuels Biodiesel from oils and fat; rapeseed etc – esterification with methanol Biochemical pathways to ethanol; 1) Sugar beet etc – sugar-fermentation 2) Starch crops – hydrolysis-sugar-fermentation 3) Lignocellulosics – separation-hydrolysis-sugar- fermentation; lignin as byproduct Thermochemical pathways to biofuels; 1) lignocellulosics – pyrolysis-bio oil-biofuels 2) lignocellulosics – gasification-methanol/FT-fuels

Reims -07 Feedstock sources Forestry waste (forest residue, bark, wood chips, thinnings) Agricultural residues (straw, stover, bagasse) Energy crops (poplar, willow, switch grass) Municipal waste (paper, packaging,..)

Reims -07 Biomass composition

Reims -07 The ideal separation of biomass

Reims -07 … and the reality Kraft and soda pulping Sulfite pulping Acid hydrolysis Steam explosion Organosolv pulping At present, none of these processes results in an efficient and cheap separation

Reims -07 Elemental analysis

Reims -07 Substance Groups in Kraft Black Liquors (kg/ton of pulp) Ref: Sjöström 1993

Reims -07 Principle for manufacturing of lignin from kraft black liquor

Reims -07 Solvent fractionation of softwood kraft lignin Ref: Kringstad et al

Reims -07 Lignin fractionation Material: Industrial black liquor of softwood (pine/spruce), birch and eucalypt respectively Fractionation: Ultra-filtration, 5 kD and 15 kD to remove high molecular particles / carbohydrates Lignin isolation: Precipitation with CO 2 (pH 9), Acid washing with H 2 SO 4 (pH 2.3), Drying Purification: Cation-exchange to remove traces of Me + Permeate Retentate

Reims -07 SEC of kraft lignins before/after fractionation softwood eucalypt

Reims -07 SEC-data from fractionated (5 kDa) kraft lignins

Reims -07 Thermal analysis of purified kraft lignins

Reims -07 Even a small lignin withdrawal can be interesting … 650,000 tonnes of pulp Lignin withdrawal of 10% yields 33,000 tonnes … converted to 16,000 tonnes of CF …to support 160,000 cars with CF-composite (~40% replacement)

Reims -07 Conclusions All native lignins are heterogeneous biopolymers linked to polysaccharides Alkaline or acidic processes result in both lignin degradation and re-polymerisation The up-grading of technical lignins require purification steps Several options exist for an increased lignin use