Non-noble Ni@NbOx Catalyst for Selective Hydrodehydroxylation of 5-Hydroxymethylfurfural to 5-Methylfurfural

Abstract

Selective hydrogenation of substrates containing multiple unsaturated bonds (C═C and C═O) is a crucial catalytic process in the production of high-value chemicals. The development of nonprecious metal catalytic systems is of importance for hydrogenation processes due to the high cost and scarcity of noble metals. In this study, we have developed a straightforward and versatile encapsulation technique for the synthesis of Ni@NbO_x catalysts, which enables highly selective hydrodehydroxylation of 5-hydroxymethylfurfural (HMF) to 5-methylfurfural (MF) under H₂. Mechanistic studies revealed that metallic Ni⁰ encapsulated within NbO_x facilitates hydrogen dissociation through an energy quasi-barrierless process (<0.1 eV), while simultaneously avoiding the adsorption of furan or C═O groups over Ni nanoparticles, therefore enhancing the selective hydrodehydroxylation of HMF to MF. Furthermore, the Ni@NbO_x catalyst was tolerant to different conditions for selective hydrogenation, such as crude H₂ containing CO, substrates contaminated with various metal salts, etc.