Bimetallic effects in the catalytic hydrogenolysis of lignin and its model compounds on Nickel-Ruthenium catalysts

摘要

The synergistic catalysis in the catalytic hydrogenolysis (CH) of lignin and its model compounds over a Ni-Ru/AC bimetallic surface was well established. The Ni-Ru/AC exhibits excellent activity and stability for catalytic hydrogenolysis of lignin and its model compound. The additions of Ru into supported Ni/AC can not only improve the overall reactants conversion, but also modify the product distribution. The apparent activation energy (E-a) of BPE hydrogenolysis over Ni-Ru/AC is measured approximately to be 18.3 kJ/mol. This value is considerably lower than the values measured for monometallic Ni/AC (42.4 kJ/mol). Additionally, the turnover frequency (TOF) of Ni-Ru/AC (62.7 h(-1)) was much higher than that of Ni/AC (5.1 h(-1)). In case of CH of lignin, Ni-Ru/AC gave better total liquid yield and higher relative content of main aromatic monomers. The enhancement in the overall hydrogenolysis activity of reactants over bimetallic Ni-Ru/AC is related to the synergistic effect of Ni and Ru. Various characterization methods (XRD, XPS, TEM-EDS, SEM-EDX and BET) are performed to elucidate the formation of synergistic effect. This synergistic effect could originate from the generation of additional surface active sites, small size of metal particles and high dispersion of metal particles.