Highly efficient syntheses of 2,5-bis(hydroxymethyl)furan and 2,5-dimethylfuran via the hydrogenation of biomass-derived 5-hydroxymethylfurfural over a nickel–cobalt bimetallic catalyst

The hydrogenation of furan derivatives is of great scientific and strategic significance because the molecular diversity of the hydrogenation products ensures the efficient utilization of biomass resources. In this study, an inexpensive and magnetically separable bimetallic catalyst (NixCoy) was synthesised via solid-phase grinding. The catalyst exhibited efficient catalytic activity towards the hydrogenation of 5-hydroxymethylfurfural (HMF) into 2,5-bis(hydroxymethyl)furan (BHMF) and 2,5-dimethylfuran (DMF) at a low reaction temperature and H2 pressure. Further, the 93.1% and 80.1% selectivities of BHMF and DMF with a full conversion of HMF were obtained under the optimal conditions by controlling the temperature, respectively. Furthermore, the as-prepared catalysts were characterized via the thermogravimetry–derivative thermogravimetry (TG-DTG), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), and N2 adsorption–desorption isotherm techniques. Additionally, the synergistic catalytic effect of the hydrogenation sites in the Ni and Co metals, as well as the Lewis acid sites in NiO and CoO promoted the conversion of HMF into BHMF and DMF. Thereafter, the possible synergistic catalytic mechanism was proposed based on the characterization of the catalyst and the experimental results.