Heterogeneous hydrolysis of cellulose into glucose over phenolic residue-derived solid acid

Carbon-based solid acid (CSA) was successfully prepared using phenolic residue as starting material. The characterization results indicate that such solid acid catalyst mainly consists of four building blocks: the condensed aromatic carbon sheets, the active groups (including SO3H, COOH and phenolic OH), the side chains (including CH3 and OCH3) and the bridge linkages (including O, CH2, CH2CH2, and OCH2) acting as the intermediates between aromatic clusters. Most of these building blocks, except for the SO3H, could be derived from the corresponding part of the phenolic residue. Aliphatic side chains have been demonstrated to greatly improve the sulfonation activity of carbon precursor and promote the catalytic performance in cellulose hydrolysis, and the carbon-based catalyst sulfonated for just 1 h could exhibit almost similar catalytic activity compared with the catalyst sulfonated for a longer time. However, their hydrophobicity and steric hindrance reduced the utilization efficiency of the sulfonic acid groups to a certain extent.