Anodic Modification of Lignins during Electrolysis in the Organocell Process

Abstract

Pulping liquor from the 5 t/day demonstration plant of Organocell GmbH, Munich, was electrolyzed with different current densities. The analysis of the isolated lignins revealed considerable changes of lignin structure during electrolysis. These changes included polymerization reactions involving the formation of C-and O-condensed interunit linkages and reactions of the side-chain such äs decomposition of enol ethers and increase of COOH, CO and OH a |j. groups. The extent of the observed reactions was found to be highly dependent on the current density. With the exception of OH a ü. groups and residual sugars, the degree of structural modification was inversely proportional to current density.

Studies on electrooxidation of lignin and lignin model compounds. Part 1: Direct electrooxidation of non-phenolic lignin model compounds

“…But even in this case, the cleavage of non-phenolic b-O-4 substructure is a key reaction. There are a few reports concerning electrooxidation of lignin in alkali medium (Limosin et al 1986;Löbbecke et al 1990) for non-energetic lignin utilization, but they did not discuss C a -carbonylation. Many fundamental studies on electrochemical oxidation were performed with lignin model compounds Britton and Steelink 1974;Chabaud and Sundholm 1978;Sundholm 1982;Limosin and Canquis 1985;Pardini et al 1991Pardini et al , 1992.…”