Selective conversion of cotton cellulose to glucose and 5-hydroxymethyl furfural with SO42−/MxOy solid superacid catalyst

This paper presented a mild hydrothermal process for degradation of cotton cellulose with solid superacid catalyst and selective conversion of cotton cellulose to glucose and 5-hydroxymethyl furfural (HMF). Five kinds of solid superacid catalyst such as SO42−/SnO2, SO42−/TiO2, SO42−/ZrO2, SO42−/Fe2O3 and SO42−/Al2O3 were prepared by impregnation method. The BET surface area of catalyst SO42−/SnO2 was up to 118.8 m2 g−1 when impregnation was performed with 1 mol L−1 H2SO4 of impregnating solution at 550 °C calcination temperature for 3 h. It made the hydrothermal temperature of cellulose degradation decrease to 190 °C successfully and suppressed the side reaction. The NH3-TPD profile of SO42−/SnO2 indicated there was a wide region of stronger acid sites on the catalyst surface. The depolymerization of cotton cellulose obtained 11.0% yield and 22.0% selectivity of HMF and 26.8% yield and 53.4% selectivity of glucose, respectively. The regeneration and reuse of solid superacid catalyst were also discussed in this paper.