Highly Active HDS Catalyst for Producing Ultra-low Sulfur Diesel Fuels

Cosmo Oil Co., Ltd. developed a highly active CoMo HDS catalyst, C-606A, for the production of ultra-low sulfur diesel fuels. This patented preparation method involves impregnation of the support with a solution containing CoCO₃, MoO₃, citric acid, and phosphoric acid, and air-drying without calcination, to provide the high activity HDS catalyst. XPS studies suggested that the addition of citric acid to the impregnation solution during catalyst preparation prevents the sulfidation of Co at low temperature and the uncalcining procedure during catalyst preparation promotes the sulfidation of Mo at low temperature, thereby increasing the formation of the Co–Mo–S structure. The results of the catalytic characterization and the reactivities of the sulfur species and nitrogen species in diesel fuel during the hydrotreating process on C-606A clearly indicate that significant improvements of catalytic activity of the developed catalyst can be achieved by improving the intrinsic activity of the active sites, as well as by increasing the number of Co–Mo–S structure. The commercial operation directly demonstrates the excellent activity and stability of C-606A under industrial operating conditions.