Hydrogenative rearrangement of bioderived furfurals to cyclopentanones over Ni/Nb2O5 catalysts: Promotion effect of reducible NbOx and water.

[Display omitted] • Ni/Nb 2 O 5 catalysts with reducible NbO x species were synthesized. • An exceedingly high cyclopentanone yield was achieved by using Ni/Nb 2 O 5 in H 2 O. • Superior performance resulted from close cooperation between Ni-NbO x sites and H 2 O. • NbO x sites facilitated furfural adsorption via flat configuration. • H 2 O mediated furfural activation and transferred active hydrogen. Selective aqueous hydrogenation of furfurals to valuable cyclopentanones is attractive for biomass utilization. Herein, Ni/Nb 2 O 5 catalysts with different calcination temperatures were synthesized and employed to study the effect of reducible NbO x species and water solvent on the aqueous hydrogenation-rearrangement of furfural. A significantly higher cyclopentanone (CPO) yield (>92 %) was achieved in water on Ni/Nb 2 O 5 -500, while no CPO was detected in heptane. Catalysts characterization indicated that the calcination temperature of Nb 2 O 5 determined the crystallinity and modulated reducible NbO x. Kinetic and isotopic experiments elucidated that the excellent catalytic performance of Ni/Nb 2 O 5 remarkably correlated with surface reducible NbO x species and H 2 O-mediated effect. NbO x species closely interacted with Ni sites, in which Ni was in charge of H 2 activation and NbO x facilitated furfural adsorption via flat configuration. Water helped furfural activation and active hydrogen transfer between Ni sites and adsorbed furfural on NbO x sites, thus significantly boosted aqueous hydrogenation of furfural to CPO. [ABSTRACT FROM AUTHOR]