Abstract: The first commercial application of FHUDS-3 hydrofining catalyst newly developed by Fushun Research Institute of Petroleum and Petrochemicals was carried out at the 3.0 Mt/a diesel hydrofining unit of SINOPEC Shanghai Gaoqiao Petrochemical Corporation. The operations of nearly three years showed that FHUDS-3 catalyst possessed high activity, good selectivity and adaptability to various feedstocks, thus, it processed various mixed diesel feedstocks to produce low-sulfur clean diesel meeting the requirements of National Exhaust Emission Standard III and Shanghai Exhaust Emission Standard IV. Nevertheless, after running 26 months, the catalyst activity showed a significant decline trend. By analyzing the spent catalyst, it was found that the serious deactivation of catalyst was caused by the deposition of silicon on the catalyst surface, which reduced the pore volume and specific surface area of the catalyst, covered some active sites and led to catalyst deactivation finally. However, the silicon deposits came from coker distillate in the mixed feedstock due to the use of defoaming agent containing organic silicon at the upstream delayed coking unit.

Key words: catalyst , diesel fuel, hydrofining, silicon, deactivation