Biodiesel production with hydroprocessing process from waste cooking palm oil over ni-mo/al2o3 and co-mo/al2o3 carbides catalysts

Abstract

Hydroprocessing of vegetable oil has been known as a process for biodiesel production to replace trans-esterification. In this research, waste cooking palm oil (WCPO) is used as a starting feedstock to reduce a cost of raw-material. Ni- and Co-Mo/Al2O3 prepared by co-impregnation method were pretreated by sulphidation or carburization. The operating temperature of 380C, hydrogen pressure of 50 bar and reaction time of 6 h was found suitable to maximize the diesel range yield. The highest yield of 71.8% can be obtained by Ni-Mo/Al2O3 sulphided catalyst. Sulphided catalyst shows slightly higher diesel yield than that of carbide catalyst; however, the strong beneficial of carbide catalyst over sulphided catalyst are higher reusability. After pretreatment the used carbide catalyst, the catalytic performance becomes comparable to the fresh carbide catalyst while the regenerated sulphided catalysts are still suffered from activity loss. The liquid and gas product distribution shows a conform results which indicated that hydrodecarboxylation and hydrodecarbonylation reaction pathways are dominated over hydrodeoxygenation.