Depolymerization of cellulose into high-value chemicals by using synergy of zinc chloride hydrate and sulfate ion promoted titania catalyst.

Experiments for cellulose depolymerization by synergy of zinc chloride hydrate (ZnCl2·RH2O) and sulfated titania catalyst (SO42-/TiO2) were investigated in this study. The results showed the introduction of sulfate into the TiO2 significantly enhanced the catalyst acid amount, especially for Brønsted acid site, which is beneficial for subsequent cellulose depolymerization. ZnCl2·RH2O hydrate, only a narrow composition range of water, specifically 3.0≤R≤4.0, can dissolve cellulose, which finally resulted the cellulose with low crystallinity and weak intrachain and interchain hydrogen bond network. Coupling of ZnCl2·RH2O hydrate and SO42-/TiO2 catalyst as a mixed reaction system promoted cellulose depolymerization, and the products can be adjusted by the control of reaction conditions, the low temperature (80-100°C) seemed beneficial for glucose formation (maximal yield 50.5%), and the high temperature (120-140°C) favored to produce levulinic acid (maximal yield 43.1%). Besides, the addition of organic co-solvent making HMF as the main product (maximal yield 38.3%).