The Critical Role of Hydroxyls on Anatase TiO 2 in the Ring Opening of 2,5-Dimethylfuran to 2,5-Hexanedione

Abstract

The selective ring-opening of biomass-derived furanic molecules offers an attractive route for the synthesis of industrially relevant linear ketones. Herein, the ring-opening reaction of 2,5-dimethylfuran (2,5-DMF) was systematically investigated over a series of oxide catalysts. Anatase TiO2 (TiO2-A) exhibits superior catalytic performance for the conversion of 2,5-DMF to 2,5-hexanedione (2,5-HD), delivering high selectivity under mild reaction conditions. Structure-activity correlation studies reveal that surface hydroxyl groups on TiO2-A play a decisive role in promoting the ring-opening reaction through strong interfacial interactions with the furan ring. Spectroscopic analyses indicate that these hydroxyls serve as the primary surface sites involved in the activation and subsequent cleavage of the furan C-O bond. Nevertheless, catalyst deactivation occurs during prolonged operation, which is mainly attributed to the strong and irreversible adsorption of 2,5-HD on surface hydroxyl groups, leading to progressive site blockage and loss of activity.