Construction of HfO2 nanoparticles with rich hydroxyl group for the efficient catalytic transfer hydrogenation of furfural

Abstract

Although metal oxide has unique advantages in catalytic transfer hydrogenation (CTH) of furfural (FAL) into furfuryl alcohol (FOL), the excessive stability of the metal site and oxygen coordination leads to the inert Lewis acid site in the oxide, which affects the catalytic activity and limits its broader application. It is known that the hydroxyl group on the oxide surface can promote the adsorption of isopropanol in an alkoxide species by assisting its deprotonation, thereby activating the metal site and enhance the overall reaction activity. However, constructing metal oxide with rich hydroxyl groups is always challenging. This contribution prepared a series of HfO2 nanoparticles (NPs) with rich hydroxyl groups through hydrothermal methods. Systematic characterizations proved the presence of hydroxyl groups on the surface of HfO2 NPs, which promoted its adsorption capacity for isopropanol (hydrogen donor and reaction solvent) and substrate (FAL), thus accelerating the subsequent reaction for CTH of FAL into FOL. As a result, a 100% of FAL conversion with 95.2% of FOL yield was obtained at 160 °C in 4 h, which has significant advantages over commercial and other literature reported oxides. This finding provides a new idea for designing of efficient metal oxides for the CTH reaction by enhancing the hydroxyl group.