Sulfonic acid-functionalized hierarchical SAPO-34 for fructose dehydration to 5-hydroxymethylfurfural

Sulfonic acid-functionalized hierarchical SAPO-34 (S1-SAPO-34-SO3H) was prepared by post-grafting 3-mercaptopropyltriethoxysilane, and the sulfonic acid group was then oxidized by H2O2. The obtained catalysts were characterized by XRD, SEM, FTIR, TG, nitrogen adsorption, XRF, and acid–base titration. The acidity of the modified SAPO-34 increased, which confirmed the success of grafting. The catalytic properties during the dehydration of fructose to 5-hydroxymethylfurfural (5-HMF) were investigated. The yield of 5-HMF was up to 72%, and a 34% increase was found compared with the case of SAPO-34. The findings were discussed and attributed to the synergistic effects caused by both the acid groups and the mesopores. More basic investigations with regard to the conditions, including the reaction time, temperature, solvent, load and regeneration, are needed.