In situ aqueous phase hydrodeoxygenation of methyl palmitate to hydrocarbons on Ni catalyst derived from the reduction of LaNiO₃ perovskite

Abstract

A series of Ni–La–O-T catalysts (T-calcination temperature) were prepared via the sol–gel process followed by the calcination. They were tested for in situ aqueous phase hydrodeoxygenation (HDO) of methyl palmitate using methanol as hydrogen donor. In the calcined samples, NiO and La₂O₂(CO₃) formed in Ni–La–O-550 and Ni–La–O-650. Apart from NiO and La₂O₂(CO₃), there was LaNiO₃ perovskite in Ni–La–O-750. Only LaNiO₃ perovskite existed in Ni–La–O-800. After the reduction at 650 °C, metallic Ni and La₂O₃ appeared in all the catalysts. During in situ HDO, decarbonylation/decarboxylation was dominating, accompanying with the C–C bond hydrogenolysis and aqueous phase reforming of alkanes. H₂ was generated from not only the aqueous phase reforming of methanol but also that of alkanes. Liquid C₆–C₁₆ alkanes were produced and C₁₅ alkane was main product. Among the catalysts, Ni–La–O-750 afforded the highest activity for deoxygenation, C–C bond hydrogenolysis and aqueous phase reforming. The reaction temperature, reaction time, water and methanol loadings remarkably affected the products distribution. At a suitable condition, the yield of C₆–C₁₆ alkanes reached 71.1% on Ni–La–O-750. Additionally, Ni–La–O-750 was also very active for in situ HDO of methyl palmitate without methanol, however, the C–C bond hydrogenolysis was more serious.