Synergetic effect of Cu0 −Cu+ derived from layered double hydroxides toward catalytic transfer hydrogenation reaction

Abstract

As a safe and environmentally friendly selective hydrogenation method, catalytic transfer hydrogenation (CTH) has aroused great interest in preparation of high-value-added products from biomass derived resources. Herein, a Cu-based catalyst (Cu/CuAl-MMO-400) was prepared by structural topological transformation of layered double hydroxides (LDHs) precursor, which displayed promising catalytic behavior toward CTH reaction of furfural (FAL) with 2-propanol (2-POL) as the hydrogen donor. Notably, the reaction rate is as high as 0.125 mol g−1 h−1, which is superior to previously reported non-noble metal catalysts. A combination investigation based on XPS, XANES and Bader charge confirms the co-existence of Cu0 and Cu+ sites on the surface of Cu nanoparticles. Both experimental studies (in situ DRIFTS and isotope labelling MS) and DFT calculations reveal that the Cu0−Cu+ synergistic effect plays a vital role in determining catalytic behavior: the Cu+ species acts as both dehydrogenation and hydrogenation active site; while the Cu0 site promotes the transfer of H atoms between adsorbed substrates. This work substantiates a Cu0 −Cu+ synergetic catalysis by establishing structure-property correlation and revealing reaction pathway, which could be extended to other CTH reactions in the upgrading processes of biomass.