Vapor-phase hydrogenation of levulinic acid to γ-valerolactone over Cu-Ni alloy catalysts

Abstract Vapor-phase hydrogenation of levulinic acid (LA) to ɤ-valerolactone (GVL) was investigated over supported-type Cu-Ni/Al2O3 catalysts in H2 flow at 250 °C. Ni-rich Cu-Ni/Al2O3 catalysts, typically 6 wt.% Cu and 14 wt.% Ni, achieved high LA conversion with high stability and high GVL selectivity. XRD analyses of the catalysts clarified that Cu-Ni alloy nanoparticles were produced on the alumina support by forming a solid solution of CuO-NiO. The Cu-Ni/Al2O3 catalyst showed the highest GVL productivity of 11.0 kg kgcat-1 h-1 with a selectivity of 98.6%, although the catalyst was gradually deactivated with time on stream under high SV conditions. In the characterization of the used catalysts, the catalyst deactivation would be caused by the sintering of active Cu-Ni alloy nanoparticles, which could be induced by the cycle of the oxidation with H2O and the reduction with H2.