Hierarchical Flower-like Bimetallic NiCu catalysts for Catalytic Transfer Hydrogenation of Ethyl Levulinate into γ-Valerolactone

Due to fast exploitation and consumption of fossil resources, efficient transformation of renewable biomass would be of vital significance for the production of biofuels and value-added chemicals. Here, we developed new alumina microsphere (AMS) supported bimetallic NiCu catalysts with a hierarchical flower-like architecture for highly efficient catalytic transfer hydrogenation of biomass-derived ethyl levulinate (EL) to gamma-valerolactone (GVL), which were derived from flower-like core shell structured AMS@Ni-Cu-Al layered double hydroxide precursors (ANIS@NiCuAl-LDH). Various characterizations demonstrated that the reduction of NiCuAl-LDH precursors in situ grown on the AMS could generate bimetallic NiCu alloy nanoparticles embedded into surface standing and intercrossed LDH-derived alumina nanoplatelets (ANPs), thereby forming a novel hierarchical multilevel AMS@NiCu@ANPs superstructure. As-fabricated bimetallic NiCu catalyst with 0.5 Cu/Ni molar ratio exhibited enhanced activity for catalytic transfer hydrogenation, in comparison with monometallic and other bimetallic ones, owing to the synergy between Ni-Cu species in highly dispersed bimetallic NiCu nanoparticles, i.e., the electronic effect, favorable surface acid-base property, and highly porous architecture. Moreover, the catalyst possessed good stability and recyclability, due to strong interactions between ANPs and AMS support, as well as between NiCu NPs and ANPs matrix.