Lignin depolymerization

Figure 4. Effect of solvent on conversion and ether solubles of glycol lignin depolymerized in 3% NaOH.

Figure 8. Effect of treatment severity on glycol lignin depolymerization in 2% NaOH. C/0 = carbon/oxygen ratio in residual lignins.

If, as a criterion of value to the study of lignin depolymerization by alkaline hydrolysis, the maximum yield of oxygen-bearing, phenylpropanoid derivatives is chosen, then the conditions of such a study have been optimized here at a treatment severity corresponding to a reaction temperature of 300°C for 1 hour. Under these conditions, 20% of the lignin is recovered as ether-solubles of which 55% is identifiable as monomeric derivatives. The rest of this material probably consists of dimeric-type compounds not identified by capillary gas chromatography. 

Figure 6. Simulated pyrolysis of polyVGE at 380°C. Reprinted with permission from Chem. Eng. Sci., vol. 41, p. 1053, J. B. McDermott and M. T. Klein, Chemical and Probabilistic Modelling of Complex Reactions A Lignin Depolymerization Example, copyright 1986 [25], Pergamon Press PLC.

Chlorination is carried out at low eonsisteney of about 3% (because of the low solubility of chlorine in water). Chlorine (C) reacts almost instantly with all lignin groups, primarily by substitution and oxidation, with some addition of chlorine to double bonds also occurring (Sjdstrom, 1981). Chlorination reactions affect some lignin depolymerization to low moleeular weight chlorinated products, but high... 

R Bourboimais, MG Paice, ID Reid, P Lanthier, M Yaguchi. Lignin oxidation by laccase isozymes from Trametes versicolor and role of the mediator 2,2 -azinobis-(3-ethylbenzthiazoline-6-sulphonate) in kraft lignin depolymerization. Appl Environ Microbiol 61 (5) 1876-1880, 1995. 

McDermott, J.B. Chemical and Stochastic Modelling of Complex Reactions A Lignin Depolymerization Example, Ph.D. Thesis. University of Delaware. 1986... 

Pandey MP, Kim CS (2011) Lignin depolymerization and conversion a review of thermochemical methods. Chem Eng Technol 34 29... 

Morohoshi N, Glasser W G 1979 The structure of lignins in pulps. Part 4 Comparative evaluation of five lignin depolymerization techniques. Wood Sci Technol 13 165-178... 

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