Metal sulfate-catalyzed methanolysis of cellulose at high solid loadings: Heterogeneous degradation kinetics and levulinate synthesis

Abstract

Increasing efforts have been devoted to the production of bio-based chemicals from high solid content of renewable biomass to pursue optimal process efficiency and economics. In this study, the preparation of methyl levulinate (ML) by metal sulfate-catalyzed methanolysis from high solid content of cellulose was investigated. When the cellulose loading was 15%, 38.67% of ML yield can be obtained under the optimum reaction conditions. Al2(SO4)3 can be reused more than five times while maintaining high activity in the process. The characterization of cellulose particles confirmed that cellulose particles shrunk over the reaction time. The heterogeneous degradation kinetics of high solid content of cellulose in methanol could be explained by a shrinking core model. High solid loadings led to a decrease of the reaction rate constants of methanolysis. Using cellulose with a small particle size can improve the methanolysis reaction rate. The study also proposed comprehensive reaction pathways for ML production from high solid content of cellulose. To elucidate the methanolysis mechanism, an assessment of density functional theories for the calculation of glucose methanolysis at the molecular level is presented. All these results can inspire the development of ML synthesis technology through methanolysis from renewable biomass with high solid loadings.