Study On Supported Skeletai Nickel Catalyst In Hydrogenation Of Coking C₉ And Its Regeneration Performance

Coking C₉ is one of the fractions of coking crude benzene,which contains a large amount of highly unsaturated hydrocarbons compounds（such as indene,alkenyl aromatics）and a variety of heterocyclic compounds.These substances were easily oxidated by air or self-aggregating into gum,affecting the comprehensive utilization value of coking C₉.The gum content could be reduced and oxidation stability could be improved by hydrorefining of coking C₉,so the resources of coking C₉ could be rationally used.This paper studied the supported skeleton Ni catalyst for its easily obtained raw material,simple preparation method and good hydrogenation activity.The effects of different impurities on the hydrogenation of coking C₉ were investigated and the reasons of inactivation of supported skeleton Ni catalyst were analyzed to seek the suitable supported skeleton Ni catalyst regeneration method,which is of great significance for the development of such catalysts.The supported skeleton Ni catalyst was prepared by the gelation,kneading,crushing,calcination and alkali activation of the mixture of pseudo-boehmite and Ni-Al alloy powder,which was used in coking C₉ hydrogenation reaction.The effects of impurities were investigated on hydrogenation of coking C₉ by using indene hydrogenation as probe.The results showed that the reaction temperature has a great significance effect on the indene conversion of coking C₉ hydrogenation,and the appropriate temperature of C₉ hydrogenation was 210℃.The heterocyclic compounds containing oxygen,nitrogen and sulfur（such as coumarone,pyridine,o-cresol and thiophene）had a strong inhibitory effect on hydrogenation.The reasons of catalyst activity decrease of supported skeleton Ni catalyst were analyzed after coking C₉ hydrogenation reacting 1500 h.The conversion of indene maintained above 95% within 1000 h,which indicated that the supported skeleton Ni catalyst had a good activity stability.The catalysts were characterized by XRD,BET,H2-TPR,SEM,XPS and TG-DTA.There was obvious carbon deposition on the surface of the catalyst.The skeleton Ni decreased and the Ni grains were agglomerated and grew up of catalyst with increasing reaction time.Therefore,the reasons for the deactivation of supported skeleton Ni catalyst for coking C₉ hydrogenation are in many forms,including: surface carbon,aggregation of Ni grains et al.The catalyst was regenerated in the 5%O2（O2:N2=5:95）atmosphere and air atmosphere after partial deactivation,and the hydrogenation activities were studied.The results showed that with the increase of regeneration temperature（400℃⁶00℃）,the content of NiO oxidized from Ni was increased,the specific surface area of the regenerated catalyst and the hydrogenation activity of the catalyst was reduced.The catalyst regenerated at 400 ℃ had high activity and stability.The optimum regeneration time of the catalyst was 9h in the 5%O2（O2:N2 =5:95）atmosphere of 400℃.Under the air atmosphere,the effects of regeneration temperature and regeneration time on indene hydrogenation were investigated.Within the scope of investigation,the suitable regeneration temperature and regeneration time were 400 ℃,6h,respectively,the conversion of indene was 98.7%.