Pyrolysis of purified kraft lignin in the presence of AlCl3 and ZnCl2

Worldwide huge amount of lignin is produced by paper and pulp industries and cumulative deposition of lignin in large quantities is environmental concern. Burning is common practice. To find out suitable improved ways to utilize recurringly produced industrial waste kraft lignin, purified industrial waste kraft lignin was subjected to pyrolysis with and without catalysts in modified furnace, under inert atmosphere of nitrogen to obtain low molecular weight compounds. Anhydrous AlCl3 and ZnCl2 were used as catalysts during thermal degradation and the liquid products obtained were qualitatively analyzed on gas chromatography–mass spectroscopy. More conversion of solid lignin into liquid plus gaseous products was obtained in the presence of anhydrous AlCl3 than in the presence of ZnCl2 and that of without catalyst. Lignin shows wide spectrum of liquid degradation products and range of their molecular weights are wide enough. Main liquid products obtained under these conditions were substituted phenols, cyclic esters, mono and dicarboxylic acids. Use of catalysts was observed to be beneficial for more conversion of solid lignin into pyrolysis products but the use of catalyst may be purpose specific.