Study On Ex-situ Presulfidation Of Diesel Hydrotreating Catalyst

The factors that influenced ex-situ presulfidation of the diesel hydrogenation catalyst were studied in this paper, which included impregnation condition and sulfidation condition, and the right sulfurization agent was selected. The sulfided catalysts were characterized by XRF, XRD, in addition , the hydrogenation activity and stability of these sulfided catalysts were studied.It showed that the factors that influenced ex-situ presulfidation included impregnation te- mperature, impregnation time, impregnation pressure, sulfidation time and sulfidation temperature by studing of impregnation and sulfidation conditions. Impregnation temperature was one of the main factors of presulfidation. For different sulfurization agents, the effect of presulfidation was better when the impregnation temperature was slightly lower than the boiling point of the sulfurization agent. The influence of impregnation pressure on the sulfidation was not obvious. The effect of presulfidation was better when impregnation time was 1 hour. The sulfidation temperature had an important influence to the effect of presulfidation, and it was better from 320℃to 350℃. Sulfurization time was appropriate not less than 1 hour.The hydrogenation activity of sulfided catalysts and the effect of sulfidation with different sulfurization agents such as DMDS, sulphur, the composition of sulphur and 1-dodecene, the composition of DMDS and sulphur, the composition of DMDS and ammonium sulfide, and ammonium thiosulfate were studied.It showed that the sulfided catalyst had the highest sulfidation degree, the best crystalline of metal sulfide, the best stability and the best function of HDS and HDN when the composition of DMDS and sulphur acted as sulfurization agent.Compared with the catalysts which impregnation and sulfidation proceed continuously, the sulfidation degree of catalysts decreased to some extent when these catalysts were pre-sulfided days later after being impregnated. It showed that impregnation and sulfidation should be proceed continuously. The ex-situ pre-sulfided catalyst had better hydrogenation activity compared with in-situ pre-sulfided catalyst.