Preparation of a novel solid acid bearing sulfur-containing active groups and evaluation of its activity for cellulose hydrolysis

Abstract

A novel metal-free solid acid was prepared by co‑carbonation followed sulfonation, using cellulose and sodium thiosulfate as raw materials. The effects of sulfur-doping on the structure and catalytic activity of the solid acid were discussed. The results reveal that S content of the solid acid was up to 23.53 wt%, in which S was present in the form of sulfoxide, sulfone, thiophene and disulfide groups in addition to sulfonic acid group. The solid acid exhibited high adsorption capacity and catalytic activity in cellulose hydrolysis compared with carbon-based solid acid, which is initially attributed to the appearance of sulfoxide and thiophene. Sulfoxide and thiophene can enhance the adsorption capacity of the solid acid through hydrogen bonding and CH-π interaction respectively, leading to improvement in hydrolytic activity of the solid acid.