Effect of preparation method of NiMo/γ-Al2O3 on the FAME hydrotreatment to produce C15–C18 alkanes

Abstract

The second-generation biodiesel is a clean, green and renewable energy. Herein, NiMo/γ-Al2O3 catalysts were prepared by different methods and used for hydrodeoxygenation of fatty acid methyl ester (FAME) to produce C15–C18 alkanes. The Al–Ni spinel (NiAl2O4) and NiMoO4 species can be formed during the impregnation method, while NiAl2O4 and NiMoO4 can be inhibited by co-precipitation method. The Ni3+ species on the catalyst surface from impregnation and co-precipitation method was assigned to NiMoO4. Ni15Mo5/γ-Al2O3-CP (co-precipitation method) with smaller particle size of active metal oxides, large pore size, and more contents of low chemical valence states from active metal species (Ni2+ and Mo4+) shows a higher hydrodeoxygenation performance than Ni15Mo5/γ-Al2O3-IM (impregnation method). The liquid yield, conversion, oxygen removal efficiency, and selectivity of C15-18 alkanes over Ni5Mo5/γ-Al2O3-CP are 76%, 100%, 99.05%, and 92.45%, respectively. It also shows a stable catalytic performance during 200 h test.