The effect of Lewis acidity of tin loading siliceous MCM-41 on glucose conversion into 5-hydroxymethylfurfural

5-hydroxymethylfurfural (HMF) is a carbon-neutral feedstock to produce liquid fuels and fine chemicals. HMF can be produced from glucose using solid-acid catalysts via a tandem reaction mechanism involving glucose isomerization to fructose on Lewis acid sites (LAS) and subsequent dehydration to HMF on Brønsted acid sites (BAS). However, few studies have reported HMF production from glucose over LAS. To address this research gap, we designed a series of LAS-dominant tin (Sn) loading mesoporous siliceous MCM-41 molecular sieve (xSn/MCM) for efficient glucose conversion. The study found that the density of LAS plays a crucial role in glucose conversion, and the highest HMF selectivity was achieved using the catalyst with the highest LAS density (2.2Sn/MCM). The produced HMF can be further dehydrated into levulinic acid (LA) on LAS or converted into a series of HMF derivatives due to the redox performance of SnO2 formed on catalysts. The highest HMF yield was achieved through an equilibrium of HMF formation and conversion, with approximately 70% selectivity of HMF and HMF-derivatives achieved with near 100% glucose conversion over 2.2Sn/MCM at 150 °C for 3 h. Furthermore, the possible reaction pathway of glucose conversion on the xSn/MCM catalyst was elucidated.