(216h) Depolymerization of Lignin to Mono-Aromatic Compounds over Solid Acid Catalysts with Hydrogen

Depolymerization of lignin to high yield aromatic compounds for production of fuels and chemicals is vital for an economically competitive biorefinery. In this study, we report a catalytic process involving acidic zeolite with hydrogen under mild conditions in water for cleaving C-O-C linkages to hydrolyze the dilute alkali extracted corn stover lignin to aromatic monomeric compounds with high yield (> 82.4% wt/wt). Results showed that the depolymerization of alkali lignin to mono-aromatic compounds was promoted by the amount of acid sites present on the zeolite and, therefore, lower silica-alumina ratio zeolites were preferred. For both alkali lignin and the β-O-4 model compound, series of reactions, including hydrolysis, dehydraration, and decarbonylation, were proposed and confirmed by computational simulation. In addition, C-C bond coupling reaction was also observed in the β-O-4 model compound under the same conditions.