Transformation of carbohydrates to 5-hydroxymethylfurfural with high efficiency by tandem catalysis

Production of 5-hydroxymethylfurfural (HMF) is a pivotal step in biorefinery. However, the intrinsic HMF production efficiency in traditional catalytic systems are low owing to the side-reactions. Here we report the highly efficient transformation of carbohydrates to HMF via tandem catalysis in heterogeneous catalytic system. The combination of Al and Sn co-modified hydroxyapatite catalyst (Al/Sn-HAP) with ionic liquid exhibit a low activation energy of 68.4 kJ mol(-1), affording HMF yields of 70.5 and 46.6% at glucose loading of 10 and 40 wt%, respectively. Compared with other catalysts, Al/Sn-HAP exhibits remarkably higher Lewis acid concentration, specific surface area and pore dimeter with slight BrOnsted acid, as are beneficial for glucose isomerization. The efficient conversion of maltose, cellobiose and starch to HMF are achieved via the triple tandem pathway consisted of hydrolysis, isomerization and dehy-dration with inhibited side-reaction. Besides, the Al/Sn-HAP catalyst after regeneration can be reused without decrease of catalytic performance. (C) 2020 Elsevier Ltd. All rights reserved.