Hydrodeoxygenation of oleic acid over NiMo bimetallic catalysts supported on niobium phosphate

Abstract

The properties of the support have profound effects on the catalytic performance of the supported catalyst. A series of NiMo bimetallic catalysts supported on niobium phosphate supports with different structures via the impregnation method was prepared. The effect of the acidity and porosity of the support on the dispersity and valence state of metal components and the synergistic interaction between Ni and Mo were investigated using XRD, N₂-physisorption, NH₃-TPD, XPS, H₂-TPR, and TEM. The catalytic performance of the catalysts was evaluated in the hydrodeoxygenation of oleic acid (OA). The results demonstrate that the stronger acidity of the support leads to better dispersion of the metal Ni and it is more difficult to reduce the metal Ni. It was shown that the synergistic interaction between Ni and Mo, which could increase the concentration of oxygen vacancies (Ov) in the catalyst and the charge density on the surface of Ni atoms, is the main reason for the catalyst showing high selectivity to n-octadecane (C₁₈). The reaction results showed that the highest selectivity to C₁₈ (91.3%) could be achieved with 98.4% conversion of oleic acid over the Ni2Mo/NbP-3 catalyst under the condition of reaction temperature of 260 °C, 3 MPa initial H₂ pressure, and reaction time of 7 h.