Cascade conversion of glucose to 5-hydroxymethylfurfural over Brönsted-Lewis bi-acidic SnAl-beta zeolites

The control of acidic properties in a catalyst is one of the key features of technology utilizing biomass for chemical production. In this study, the Brönsted and Lewis bi-acidic SnAl-beta zeolites with controllable acidity were successfully prepared by acid dealumination and isomorphic substitution of Al by Sn, and applied for the cascade conversion of glucose to 5-hydroxymethylfurfural (5-HMF). The Lewis acidity of the catalysts was increased as the higher concentration of nitric acid used for the dealumination process. The optimum portion of Lewis/(Brönsted+Lewis) ratio was investigated to maximize the yield of 5-HMF, which is converted from the glucose via fructose by the cascade reaction. The conversion of glucose was increased until the L/(B+L) ratio reached 0.89 and the selectivity to 5-HMF reached its maximum at the Lewis acid portion of 0.76 among the total acid sites.