Preparation of a novel carbon-based solid acid from cocarbonized starch and polyvinyl chloride for cellulose hydrolysis

•CCSA was prepared from cocarbonized starch and PVC followed by sulfonation.•The ether (C–O–C) and aliphatic (–CH2–) bridges make carbon sheets fully stretch.•Covalent chlorine tends to form hydrogen bonds with cellulose hydroxyl groups.•Based on the above two points, reducing sugar yield improves by approximately 57%.•The good stability may be attributed to resonance effect among Cl and aromatic rings. A novel carbon-based solid acid was successfully prepared by sulfonation of cocarbonized starch and polyvinyl chloride (PVC). The characterization results show that this catalyst possesses all characteristics of traditional carbon-based solid acids (CSAs). The differences are that chlorine from PVC is covalently bonded to edges of aromatic carbon sheets as new active groups, and ether (C–O–C) and aliphatic (–CH2–) bridges are formed during the cocarbonization process which are derived from oxygen in starch and alkyl in PVC, respectively. Chlorine groups can adsorb cellulose hydroxyl groups strongly and bridge bonds make the carbon framework fully stretch, which reduces hindrance between SO3H groups and glycosidic bonds to promote the catalytic performance in cellulose hydrolysis experiments. Furthermore, the durability results indicate that this catalyst has good stability.