The effect of difference in chemical composition between cellulose and lignin on carbon based solid acids applied for cellulose hydrolysis

Carbon based solid acids (CSAs) were prepared from cellulose and lignin at different carbonization temperatures and applied to hydrolysis of cellulose, which is of great significance for the multiple utilization of biomass. The structure and performance of cellulose based solid acids (CCSAs) and lignin based solid acids (LCSAs) were investigated by TG-DTG, XRD, FT-IR, XPS, elemental analysis, titration methods, etc. And immersion enthalpy was introduced into estimating the hydrophilicity of CSAs. The results show that the optimum carbonization temperature varies for raw material, and the optimum carbonization temperatures of cellulose and lignin are 683 and 653 K respectively. The adsorption capacities of CCSAs and LCSAs may not only be related to phenolic OH density, but may also relate to alkyl side chains and aromatic frameworks. Compared with LCSAs, the CCSAs possess higher immersion enthalpy, indicating that the CCSAs are more easily accessible to substrate, which contributes to hydrolysis. The hydrolysis activities of CCSAs are always higher than those of LCSAs, which may be due to a higher -SO3H groups densities and better accessibility between substrate and acid sites for CCSAs. These are determined by a big difference in the chemical composition between cellulose and lignin.