Synergistic effect of surface Cu0 and Cu+ species over hydrotalcite-derived CuxCo3-xAlOy mixed-metal oxides toward efficient hydrogenation of furfural to furfuryl alcohol

A series of CuCoAl catalysts derived from layered double hydroxides (LDHs) with adjustable Cu/Co ratios were prepared via a facile in situ structure topotactic transformation strategy. The comprehensive characterization results revealed that the introduction of Co element and the confined effect of LDHs jointly promoted the dispersion and stability of Cu species, as well as significantly increased the active specific surface area. Interestingly, Cu 1.5 Co 1.5 Al sample showed the superior performance for furfural (FF) hydrogenation to furfuryl alcohol (FA) under the synergistic effect of Cu 0 and Cu + species, as well as the interaction between Cu species and the support. It allowed for FF conversion of 97.5% and FA selectivity of 99.7% (150 °C, 3 h, 2 MPa initial H 2 pressure, isopropanol as solvent, m(FF):m(catalyst) = 60:1). Moreover, Cu 1.5 Co 1.5 Al displayed the satisfactory reusability, where the activity and selectivity kept stable after six successive recycling runs. Specially, it displayed the promising potential for the scale-up production. Furthermore, the mechanism study based on in situ Fourier transform infrared spectra indicated that the surface exposed Cu 0 species could promote the H 2 adsorption and then rapidly dissociated H 2 into the activated H atoms, whilst Cu + species were the active sites for FF selective hydrogenation in a η 1 (O)-aldehyde adsorption configuration.