Preparation of 5-hydroxymethylfurfural from cellulose catalyzed by chemical bond anchoring catalyst Hf x Zr 1−x P/SiO 2

A series of HfxZr1−xP/SiO2 catalysts were prepared for the catalytic conversion of cellulose to HMF in a two-phase solution system. Metal phosphate supported on mesoporous SiO2 microspheres had improved stability owing to the metal phosphate-O–Si chemical bonds, and used less active metals than conventional catalysts. The effect of the reaction conditions on the preparation of HMF was studied. Hf0.7Zr0.3P/SiO2 reacted at 463 K for 4 h, the cellulose conversion rate reached 86.2%, and the HMF yield was 62.03%. The structures and physicochemical properties of the catalysts were characterized using various techniques. The catalysts haves both Lewis acid and Bronsted acid active sites, which can facilitate the hydrolysis of cellulose, the isomerization of glucose and the dehydration of fructose to obtain HMF. A suitable Bronsted acid to Lewis acid ratio was obtained by adjusting the Hf/Zr/Si content ratio to produce Hf0.7Zr0.3P/SiO2. This helped improve the HMF yield. The catalyst retained more than 90% of its performance after five test cycles. A ratio of hafnium phosphate and zirconium phosphate is loaded onto the surface of the SiO2 microspheres. Due to the appropriate ratio of Bronsted acid to Lewis acid, and the anchoring of the metal phosphate to the carrier by chemical bonding. These catalysts are highly efficient and stable in catalyzing the conversion of cellulose to 5-(hydroxymethyl)furfural in a NaCl-H2O/tetrahydrofuran biphasic system.