Selective aqueous-phase hydrogenation of furfural to cyclopentanol over Ni-based catalysts prepared from Ni-MOF composite

Metal-organic frameworks (MOFs) as an emerging class of porous materials exhibit some unique advantages, including controllable composition, a large surface area, high porosity, and so on. In this work, the spherical NiMo bimetal catalysts supported on porous carbon matrix were prepared using a simple wet impregnation method and studied for selective hydrogenation of furfural (FFA). Three different catalysts were investigated including Ni/C-Mo-BTC, Ni/C-Mo-DHTA and Ni/C-Mo-PTA. Of the catalysts studied the Ni/C-Mo-BTC catalyst could achieve the highest selectivity of CPL (up to 90%) under moderate reaction conditions (140 degrees C, 2 MPa, 2 h) in aqueous medium. In addition, other Ni-based catalysts (Ni/C-Fe, Ni/C-Zn, Ni/C-Cu, Ni/C-Ce) were also investigated to achieve yields of 20-70% under the same reaction conditions. The influence of temperature, H2 pressure, time and solvent were investigated for the best performing catalyst. Based on the optimal reaction condition, various of furfural derivatives could also be effectively transferred to produce corresponding products. The detailed physicochemical characterization was carried out by means of XRD, SEM, TEM, XPS, NH3-TPD and Raman analysis. In the end, the optimal Ni/C-Mo0.4 catalyst could be recycled magnetically and efficiently applied in the next run for five consecutive recycling tests in the FFA hydrogenation to CPL. The results suggested Ni/C-Mo0.4 catalyst occurred to increasingly favor the formation of Ni-Mo alloys and suggested a metallic active site in FFA hydrogenation with the addition of element Mo. Mechanism study indicated that water was a key factor contributing to the formation of different desired products, which was responsible for the arrangement of furan compound.