Highly Selective Hydrodecarbonylation of Oleic Acid into n‐Heptadecane over a Supported Nickel/Zinc Oxide–Alumina Catalyst

Abstract

AbstractThe production of second‐generation biodiesel with triglycerides or their derivatives through hydroprocessing is considered as a promising approach to make transportation fuels. In this study, a series of Ni‐based catalysts supported on basic composite oxides (MO‐Al2O3, M=Mg, Ca, Ni, Cu, Zn) were prepared for the catalytic deoxygenation of oleic acid in the presence of H2. Ni/ZnO‐Al2O3 exhibited the highest deoxygenation activity and alkane selectivity, which depended on its moderate basicity. Investigations of the reaction conditions, which include reaction time, reaction temperature, H2 pressure, and Ni loading, suggested that n‐heptadecane was the predominant product and its content increased with reaction temperature. The reaction temperature was more important than H2 pressure in the catalytic deoxygenation of oleic acid. Additionally, the overall reaction pathways for the conversion of oleic acid were proposed based on the product distribution for different durations and reaction rates of stearic acid, 1‐octadecanol, and stearyl stearate, in which the oxygen atoms in the oleic acid were mainly removed in the form of CO through a hydrogenation–dehydrogenation–decarbonylation reaction route. If glycerol trioleate was used instead of oleic acid, Ni/ZnO‐Al2O3 exhibited a high hydrodecarbonylation activity and selectivity to n‐heptadecane.