Effect of Zn/Al ratio of Ni/ZnO-Al2O3 catalysts on the catalytic deoxygenation of oleic acid into alkane

Ni-based catalysts supported on Zn-Al composite oxides have been prepared for the catalytic deoxygenation of oleic acid into diesel-ranged alkanes, and the effects of the Zn/Al ratio on the physico-chemical properties of the supports and the deoxygenation activity of the final catalyst were investigated in detail. The results showed that higher Zn/Al ratios led to lower specific surface area of the supports and weakening of the interaction between Ni species and supports thereby improving the reducibility of Ni species. However, higher Zn/Al ratios may limit the dispersion of Ni species, leading to a decrease in the exposure of metallic Ni. Because the conversion and deoxygenation of the reactants mainly depended on the hydrogenation capability of the catalysts which was controlled by the amount of exposed metallic Ni, the catalyst with a Zn/Al ratio of 2/1 showed the highest hydrogenation rate and alkane yield. Further decreasing the Zn/Al ratio led to strong metal-support interaction, making the Ni species difficult to reduce, which may also inhibit the formation of alkane products. In addition, the change in Zn/Al ratio affected intermediate type, which could affect the yield of alkane products. (C) 2016 Elsevier B.V. All rights reserved.