Bimetallic NiCu Alloy Catalysts for Hydrogenation of Levulinic Acid
Hong Xu, Di Hu, Man Zhang, Yuchen Wang, Zhiyue Zhao, Zhiwei Jiang, Hector F. Garcés, Kai Yan
Abstract
Upgrading of the biomass-derived levulinic acid (LA) with the activation of carbonyl functional groups is a pivotal reaction in converting biomass into high-value-added products. Herein, we reported a modified strategy to synthesize highly dispersed noble-metal-free bimetallic NiCu alloy nanoparticles (NPs) from metal–organic frameworks for the selective hydrogenation of LA, in which the ligand effect between Ni and Cu plays a crucial role under relatively mild conditions. Among the tested catalysts, the catalyst with a Ni/Cu ratio of 1:2 presented the best catalytic performance in comparison with the homometallic Ni/Cu and bimetallic catalysts with different ratios; an outstanding yield of 93.9% was obtained for γ-valerolactone (GVL). Both experimental studies and characterization analyses verified that the ligand effect is responsible for the excellent catalytic performance. A possible reaction pathway for the samples in the LA hydrogenation process is proposed; after dissociation of adsorbed H2 on the NiCu alloy surface, reactant LA is adsorbed and activated by NPs with the formation of intermediate, and through a self-condensation reaction to form products. The straightforward synthesis, superior performance, and high stability make these noble-metal-free bimetallic NiCu nanoparticles very attractive for the transformation of various biomass-derived sources into valuable products.