High Yield Production of 5-Hydroxymethylfurfural from Carbohydrates Over Phosphated TiO2-SiO2 Heterogeneous Catalyst

An efficient and selective process for the conversion of carbohydrates to 5-hydroxymethylfurfural (HMF) was applied over a novel phosphated TiO2-SiO2 (P-TiO2-SiO2) catalyst. The catalyst, synthesized by a facile sol-gel technique, was characterized by X-ray diffraction (XRD), N2 sorption, NH3 temperature-programmed-desorption, and Fourier transform infrared spectroscopy (FT-IR) study of the pyridine adsorbed. The highest HMF yield of 63.0 mol% was achieved at 170 °C for 90 min over P-TiO2-SiO2 catalyst in a tetrahydrofuran (THF)/H2O-NaCl system. The P-TiO2-SiO2 catalyst showed a predominant catalytic performance in the synthesis of HMF, a result of its moderate acid density and suitable Bronsted/Lewis (B/L) acid ratio. Additionally, the catalyst was shown to be efficient in the conversion of more complex cellulose with the high HMF yield of 56.0 mol%. More importantly, this mesoporous catalyst exhibited high stability and recyclability, making it a promising choice for the future production of HMF.