Catalytic hydrolytic cleavage and oxy-cleavage of lignin linkages

Abstract

In this work, new strategies involving organic bases were evaluated to depolymerize lignin to reduced molecular fragments in aqueous medium. NaOH as an inorganic base was also investigated as a reference. Full nature lignin samples were used for the study. As research tools to unravel the complexity of the macro lignin structure and bulky molecular size under this study, size exclusion chromatography and high resolution mass spectrometric analysis, typically used for protein characterizations, were used to follow the progress of lignin depolymerisation by measuring the molecular weight distribution of the products and determining the key molecular mass fingerprints, respectively. The results show that sodium phenoxide and guanidine carbonate are effective catalysts for lignin depolymerization. It is observed that the organic bases enhance the oxy-cleavage effect of H2O2, which is strongest with guanidine carbonate.