Hydrotreatment of jatropha oil over CoMoS/γ-Al₂O₃ catalyst

CoMoS/γ-Al₂O₃ catalysts were prepared by ex-situ presulfiding method using ammonium thiosulfate as a sulfiding agent and characterized by XRD, N₂ physisorption, NH₃-TPD and XRF techniques. The catalytic performances were tested by hydrotreatment of jatropha oil in a fixed-bed reactor. The effects of sulfidity, reaction temperature, hydrogen pressure and reaction time on catalyst activity and catalytic product distributions were investigated. Reaction pathways for the hydrotreatment of jatropha oil were also discussed. The results showed that the CoMoS₁/γ-Al₂O₃ catalyst with a sulfidity of 1 had the best hydrotreatment activity, showing 96.3% conversion of jatropha oil and 75.6% yield to the main components of C_15~18 n-alkanes at temperature 360℃ and hydrogen pressure 3 MPa. Its conversion was 36.9% higher than that of the non-sulfided CoMo/γ-Al₂O₃ catalyst at the same reaction conditions. It is worth noticing that both of the conversion of jatropha oil and the total oxygen-free compound of products could achieve 100% over CoMoS₁/γ-Al₂O₃ at 420℃, 3 MPa. With the increase of sulfidity and reaction temperature or the decrease of hydrogen pressure, the hydrodecarboxylation and hydrodecarbonylation were enhanced.