| The prominent characteristics of FCC diesel is high sulfur content,nitride content and aromatic content,which has low cetane value,high density and low stability,so how to effectively improve the quality of FCC diesel is the key of diesel hydro-upgrading.Hydro-upgrading technology of inferior diesel can effectively reduce the content of aromatics,especially the polycyclic aromatic hydrocarbon in the FCC diesel and greatly improve the cetane value,at the same time,this technology can further reduce the sulfur,nitrogen content,and diesel density,which is one of the most effective methods to improve the quality of diesel oil.hydro-upgrading catalyst is a kind of dual functional catalyst,the hydrogenation function is provided by metals,the acidity function is provided by zeolites.This paper which is based on the understanding of hydro-upgrading reaction mechanism,focuses on the secondary structure design of acid components for the hydro-upgrading catalysts.This paper firstly research on the modification of NaY zeolites.Characterization and performance evaluation of USY zeolites were conducted.The results revealed that during the hydrothermal treatment,the intermediate calcination process had great influence on the content of Na in NaY zeolite,the Na content in NaY zeolite calcined by routine calcination scheme could not meet the experiment requirement.In this paper when adopting high temperature in short time as the calcination process,the Na content in NaY zeolite is lower than 1%;the USY zeolite modified at 600°C has rich mesoporous.Besides,after hydro-treating,the acid strength of Bronsted acid decreased with the increase of silicon aluminum ratio in USY zeolite,and the acid strength of Lewis acid remained constant or increased slightly,which is mainly caused by the non framework aluminum in the mesoporous of USY zeolite.Secondly,this paper prepares the supported Ni-Mo-P catalysts with modified USY zeolites as acidic component by the incipient wetness impregnation method.The results revealed that the temperature can affect the reaction route of ring opening reaction of tetralin,in a certain temperature range,increasing temperature is beneficial to improve the unimolecular reaction rate,such as hydrogenation reaction,isomerization reaction and the ?-scission reaction.The most suitable temperature for selective ring opening of tetralin is 320°C.The strength and content of B acid can affect the rate of ring opening of tetralin.The results revealed that,when the acid center match with the metal center,the selective ring opening of tetralin can achieve good result.In addition,the rich mesoporous in modified USY zeolite is conducive to the spread of products,avoiding secondly cracking.The result for selective ring opening of tetralin show that,when the framework silicon aluminum ratio is 17.9 in USY zeolite,the performance is the best.Finally,the NMY hydro-upgrading catalysts are used for Qingdao refining FCC diesel oil.The results show that,the hydro-dearomatization of Qingdao refining FCC diesel oil is remarkable,polycyclic aromatic hydrocarbon removal rate was above 90%;in particular,polycyclic aromatic hydrocarbons leaves within 2%.The excessive strong acid is bad for improving the yield of diesel.Considering Cetane value,the yield of diesel,sulfur and nitrogen content,the NMY3 hydro-upgrading catalyst has the best performance in the series of NMY hydro-upgrading catalysts. |
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