Non-precious Cu/WO3 catalyst for hydrogenolysis of HMF to 5-MF with ultra-high selectivity in a continuous flow reactor

Abstract

The influence of metal-support interactions on the hydrogenation catalytic performance of 5-hydroxymethylfurfural (HMF) was investigated using Cu as the active metal. Low-cost Cu was selected, and group VIB metal oxides (Cr₂O₃, MoO₃, and WO₃) were employed as supports to explore their impact on metal-support interactions. The results demonstrated the following: (1) Under identical experimental conditions, the catalysts Cu/Cr₂O₃, Cu/MoO₃, and Cu/WO₃ exhibited selectivity differences for the product 5-methylfurfural (5-MF), achieving values of 46.5%, 59.5%, and 72.7%, respectively. (2) X-ray photoelectron spectroscopy (XPS) revealed that the oxidation state stability of Cu varied depending on the support, with Cu exhibiting greater stability in a low oxidation state when WO₃ was used. (3) Density functional theory (DFT) calculations confirmed that the electronic structure of Cu changes with different supports. Specifically, Cu on WO₃ displayed the lowest d-band center position, enhancing H₂ adsorption, while HMF exhibited moderate adsorption energy on WO₃, collectively leading to the highest 5-MF selectivity. (4) The effects of reaction temperature and solvent composition on catalytic performance were also evaluated. Notably, the Cu/WO₃ catalyst achieved a 5-MF yield of 94.3% under reaction conditions of 300 °C and a solvent mixture of 1,4-dioxane and water (4 : 1).