Template-free synthesis of silicon‑aluminum intergrowth molecular sieves using industrial residues without pretreatments for producing 5-hydroxymethylfurfural (5-HMF)

As a silicon‑aluminum solid waste in the preparation of fluid catalytic cracking (FCC) catalysts, residues (named as FCCR) are directly employed as synthesis raw materials without any pretreatments. An eco-friendly and template-free route is proposed to prepare ZSM-5/mordenite intergrowth molecular sieves using FCCR via a microwave assisted hydrothermal method. ZSM-5/mordenite intergrowth molecular sieves with controllable porosity and acidity are obtained. The proportion of ZSM-5 or mordenite molecular sieves is regulated by optimizing synthesis conditions (e.g., amount of seed, heating temperature/ duration, alkalinity, and SiO2/Al2O3). ZSM-5/mordenite intergrowth molecular sieves exhibit catalytic performance in the dehydration reaction of glucose to prepare 5-hydroxymethylfurfural (5-HMF). The in-situ FTIR approach proves a dehydration route “glucose→fructose→5-HMF” under the synergistic effect of BrØnsted and Lewis acid sites. These results are important for the disposal of FCCR and eco-friendly synthesis of molecular sieves.