Hydrodeoxygenation of oleic acid over NiCu bimetallic catalysts supported on Mo-modified niobium phosphate

Abstract

The properties of supports have significant effects on the catalytic performance of supported catalysts. The present study involves the synthesis of a series of Mo-modified NbOPO₄ supports, which were subsequently utilized for the preparation of supported NiCu bimetallic catalysts via a hydrothermal method. The effects of acidity and porosity on the dispersity and valence states of the metal components were systematically investigated via BET, XRD, SEM, XPS, NH₃-TPD, and H₂-TPR. The results indicate that the introduction of Mo into the NbOPO₄ support enhances the weak acid sites while reducing strong acid sites, thereby preventing excessive acidity from further cracking of long-chain alkanes and reducing carbon deposition on the catalyst surface. Moreover, the synergistic interaction between Ni and Mo leads to the formation of oxygen vacancies and Mo⁵⁺ sites, as well as alterations in the charge density on the surface of Ni atoms. These factors collectively contribute to the high selectivity of the catalyst toward C18. Catalytic performance of the materials for HDO of oleic acid was assessed and it revealed that NiCu supported on Mo-modified NbOPO₄ exhibited significantly enhanced selectivity for C18 compared to those supported on NbOPO₄ (53.10% vs. 84.16%) under the mild reaction conditions of 250 °C reaction temperature, 3 MPa initial H₂ pressure and 7 h reaction time.