Hierarchical porous carbon-based solid acid as a high-performance catalyst for conversion of fructose to 5-hydroxymethylfurfural

Fructose dehydration produces 5-hydroxymethylfurfural (HMF), which is a versatile precursor for clean fuels, advanced biofuels and fuel additives. Hierarchical porous carbon-based solid acid (HPCSA) was applied to catalyze fructose dehydration to produce HMF in dimethyl sulfoxide (DMSO). The active sulfonic acid groups were grafted onto the hierarchical porous carbon prepared from waste alkali lignin in paper industry using SiO2 and CaCl2 dual templates. The interconnected macropores and large specific areas benefit to loading S content and improve accessibility of active acid sites to fructose molecules. The results show that HPCSA achieves the HMF yield of 90 % at 110 °C for 90 min with 1 wt% catalyst loading. Under same numbers of acids, the yield of HMF with HPCSA as catalyst is 6.7 and 1.4 times higher than that of sulfonated activated carbon and sulfonated nonporous carbon, respectively. Macropores promote accessibility of fructose to active sites and avoid the local concentration of HMF in catalyst, and high acid loading are also the key factors to improve the catalytic activity of HPCSA. The activity of reused HPCSA can be easily recovered via sulfonation.