Efficient transfer hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) over Ni/NiO–MC (MC = mesoporous carbon)

Abstract

Ni/NiO–MC (MC = mesoporous carbon), with Ni and NiO nanoparticles well distributed on MC, has been successfully synthesized by pyrolysis of a Ni/mesostructured polymer framework precursor prepared via an ion-exchange process between Ni²⁺ in [Ni(NH₃)₆]²⁺ and H⁺ in the polymeric gel. Due to the synergistic effect played by Ni, NiO and MC, the as-synthesized Ni/NiO–MC showed superior performance for the transfer hydrogenation of levulinic acid (LA) to produce γ-valerolactone (GVL), with 99.9% of LA converted and a yield of 99.5% to GVL at 200 °C over Ni/NiO–MC with a Ni : LA molar ratio of 1 : 50. Even with only a small loading amount of Ni (1.12 wt%) in Ni/NiO–MC, the as-obtained Ni/NiO–MC still show a high turnover frequency (TOF) of 10.80 h⁻¹ for the formation of GVL, comparable to those previously reported over Ni-based catalysts (with a Ni amount ranging from 15 to 65 wt%) for transfer hydrogenation of LA to produce GVL. This study not only provides an efficient and economical Ni-based catalytic system for the hydrogenation of LA to produce GVL, but also highlights the great potential of using MC as an ideal support in fabricating highly efficient catalytic systems.