Catalytic conversion of methyl oleate to hydrocarbons: impact of cobalt oxide species integration in SiO2–Al2O3

Abstract

We report the effect of Co incorporation into a SiO₂–Al₂O₃ supported catalytic system on the conversion, selectivity, and stability for the catalytic conversion of methyl oleate into diesel grade hydrocarbons with systematic changes in reaction parameters including temperature, time and hydrogen pressure. A series of cobalt loaded (4–12 wt%) SiO₂–Al₂O₃ catalysts were prepared by a simple wet impregnation method. The formation of a Co₃O₄ active catalyst phase and its homogenous dispersion on the SiO₂–Al₂O₃ surface is revealed successively by XRD and TEM. The results showed that the formation of a Co₃O₄ phase over CoO/Co, the amount of Co loading, reaction time, temperature and H₂ pressure greatly determine the conversion and selectivity. Total ester conversions with more than 50% selectivity towards n-heptadecane/n-octadecene were achieved at a temperature as low as 280 °C and 15 bar H₂ pressure within 10 h using a 6% cobalt loaded catalyst. Significant hydrocracking was observed at higher metal loading under similar reaction conditions.