Hydrogen-mediated acid-base transformation of Ni supported Mo5N6 for hydrogenative rearrangement of furfural derivatives

Abstract

The hydrogenative rearrangement of bioderived furfural derivatives to various cyclopentanone derivatives is vital for synthesizing fine chemicals but challenging owing to the complex cascade reaction network. Herein, a noble metal-free Ni-supported molybdenum nitride (Ni/Mo₅N₆) catalyst was prepared with an efficient catalytic performance for the synthesis of 3-methyl cyclopentanone with a yield of 90.3% from 5-methyl furfural at a mild reaction temperature of 130 °C. Furthermore, it showed excellent catalytic performance for the synthesis of cyclopentanones with >80% yield from other furfurals. It catalyzed a direct one-pot synthesis of 3-methyl cyclopentanone from 5-hydroxymethyl furfural with a yield of 70.1% for the first time via a tandem hydrogenation–hydrogenation-rearrangement route. The catalytic mechanism indicated that hydrogen was activated on Ni nanoparticles, spilled on the Mo₅N₆ support, and formed H⁻–Mo–N–H⁺ pairs, which played multiple roles: a novel hydrogenation site for the CO hydrogenation of furfurals, acid sites for the ring opening of furfuryl alcohols, and base sites for intramolecular aldol condensation of linear diketones. This study presents an interesting method for multifunctional metal–acid/base catalysis by forming transient H⁺–H⁻ pairs over metal nitrides.