Co doping induces Co_xP-Ni₂P bimetallic site and acid synergistic effect to achieve efficient hydrodeoxidation

The development of highly efficient hydrodeoxidation (HDO) catalyst is the key to upgrad the quality of bio-oil. Co_xP-Ni₂P/SiO₂-y catalysts (y is the initial P/(Ni+Co) molar ratio) comprised of Co_xP-Ni₂P bimetallic sites and acidic site were prepared by doping Co into Ni₂P active phase using mesoporous SiO₂ as the support. The structure and chemical properties of the catalyst were characterized by XRD, BET, XPS, H₂-TPR, NH₃-TPD, Py-FTIR and TEM methods. The effects of Co doping and P/M molar ratio on the hydrodeoxidation performance of Ni₂P/SiO₂ catalyst were investigated taking m-cresol as the model compound. The results show that Co doping not only creates new Co_xP active sites, but also optimizes the electronic structure of Ni₂P, thus improving the HDO activity of the catalyst. Among the Co_xP-Ni₂P/SiO₂-y catalysts, Co_xP-Ni₂P/SiO₂-0.5 with P/M molar ratio of 0.5 exhibits the best catalytic performance, with the m-cresol conversion of 98.7% and selectivity to the deoxidized product methylcyclohexane (MCH) of 95.6% at 275 ℃ , 2 MPa and 1 h. The HDO of m-cresol over the Co_xP-Ni₂P/SiO₂-y catalyst mainly proceeded through HYD pathway.