Preparation of Hydrocracking Catalysts Promoted by Organometallics ( Co, Ni, Mo )

点击翻译按钮获取中文摘要

Organometallic complexes of Ni, Co and Fe were doped on a MoO_3/Al_2O_3 catalyst in order to enhance hydrogenation (HY) activity of Molybdenum sulfide catalysts. After presulfiding newly prepared catalysts, model test reactions were carried out to clarify catalytic functions of the catalysts such as HY or hydrocracking (HC) activity. Higher HY activities were obtained over the newly prepared catalysts as compared to Ni-Mo or Co-Mo catalysts prepared using Ni or Co nitrate.Metal phthalocyanines (Me(pc)) were found to be better promoters than other organometallics. The HY activities of the catalysts (Me(Pc)-MoS_2/Al_2O_3) decreased with the increase in calcination temperature. XRD and FT-IR measurements revealed that Me(Pc) structure on the catalysts was damaged after high temperature calcination in air indicating that Me(Pc) structure is effective for the formation of HY active sites. When the catalysts were calcined in N_2 atmosphere, the Me(Pc) structure was less damaged. Nickel phthalocyanine gave the highest HY activity among various Me(Pc)'s. Much lower HY activity was observed over Me(Pc)/Al_2O_3 catalysts as compared to Me(Pc)-MoS_2/Al_2O_3 catalysts, indicating that the synergy between Mo atom in MoS_2 and Ni or Co atom in Me(Pc)'s is essential for the formation of HY active sites of the molybdenum sulfide catalysts. On the other hand, HC activities of the Me(Pc)-MoS_2/Al_2O_3 catalysts were much less than those of Ni-Mo and Co-Mo catalysts showing that this newly prepared catalysts have superior catalytic selectivity for HY reaction.A formation of aluminate or oxide was not observed after calcination of Me(Pc)/Al_2O_3 Me(Pc)'s supported on MoO_3/Al_2O_3 were stable during calcination in N_2 and presulfurization in 5vol% H_2S/H_2 at 400ﾟC. These new findings mentioned above seem to show that highly dispersed state of Ni or Co as well as metallic state are suitable for promoting HY activity of the molybdenum sulfide catalysts.