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

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Presentation on theme: "Reims -07 Lignin complexity: fundamental and applied issues Göran Gellerstedt."— Presentation transcript:

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

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

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

4 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

5 Reims -07 Monomer yield on thioacidolysis (theoretical: ~4700-5500 mol/g)

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

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

8 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

9 Reims -07 Types of LCC isolated from spruce wood meal

10 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

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

12 Reims -07 S/G ratios in hardwoods

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

14 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

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

16 Reims -07 Lignin in annual plants

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

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

19 Reims -07 Degree of delignification for different wood species

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

21 Reims -07 -O-4 structures in wood and pulp based on thioacidolysis (birch and eucalyptus) Degradation product,  mol/g of lignin Klason lignin, %: 16.6 0.6 18.3 0.9

22 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

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

24 Reims -07 Principles in the steam explosion process (Conditions: ~190-240 o C, 1-5 min)

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

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

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

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

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

30 Reims -07 Steam explosion chemistry

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

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

33 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

34 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

35 Reims -07 Indicative targets for the share of biofuel in the EU 2005: 2% (not achieved) 2010: 5.75% (will probably not be achieved) ------------------- 2007: New energy policy document setting a minimum requirement at 10% by 2020

36 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

37 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,..)

38 Reims -07 Biomass composition

39 Reims -07 The ideal separation of biomass

40 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

41 Reims -07 Elemental analysis

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

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

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

45 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

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

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

48 Reims -07 Thermal analysis of purified kraft lignins

49 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)

50 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

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