Research Of Diesel Deep Hydrodesulfurization

Diesel,as a major oil products,has an important position in the national economy.How ever,the sulfide in it has a lot of harm.The SOx produced in combustion is one of the main pollutants in atmosphere,and the SOx produced in industry process will corrode mechanical equipment,cause equipment life down,also may cause a security risk.Therefore,to reduce the content of sulfide in diesel is a very important work.However,the dibenzothiophene class sulfides is very stable,which is difficult to be totally removed in the current level of industrial technology.Our country was originally scheduled for July 1,2011 implementation of car fuel diesel new national standards(requiring sulfur content less than 50 ppm),also delayed because the current production of diesel fuel is difficult to meet the standards.Therefore,to reduce the sulfide content in the diesel is a very important job.Based on the above status and the diesel's characteristics,this paper try to use completely liquid technic invented by our group for preparation of diesel ultra-deep desulfurization slurry catalyst,intends to explore new ways of ultra-deep desulfurization of a diesel.This paper mainly studies on preparation,characterization,and evaluation of the Ni-Mo diesel hydrodesulfurization catalyst supported by carriers of mixed Ti,A1 components and single Al components.The catalyst was prepared by the completely liquid phase method,evaluated on the intermittent slarry bed reactor with material of diesel joined two dibenzonethiophene to modulate the content of sulfur.The charac-terization of the catalyst include XRD,NH3-TPD,XPS and FT-IR,means to study influence of the content of components Ti and different sequence of adding raw materials on catalytic activity,the degree of difficulty of sulfide and the existing forms of the various components,dispersion degree and surface acidity.The main contents are as follows:Prepared the Ni-Mo catalyst supported by carriers of different Ti/Al by the completely liquid phase method,verify the feasibility of the completely liquid phase as a method of diesel hydrodesulfurization catalyst preparation.The catalyst has high activity while low Ti/Al or no Ti components adding.The sulfur content of finished diesel fuel with paraffin diluted is from 500 ppm before treatment to less than 30 ppm after treatment while the Ti/Al is 0.25.The catalyst characterization results shows that the Al composition exist as the form of AlO(OH),the Ti components exist in the form of amorphous Ti02 and anatase.The catalyst activity decreased with increasing amount of Ti components,This is due to a large number of TiO2 is generayed when adding excessive Ti components,the Ti02 attached to the catalyst surface and have adverse effects to the surface and spatial structure of the catalyst.Prepared the Ni-Mo catalyst with the use of different sequence of adding raw materials at Ti/Al is 0.25.The results showed that the catalyst has the best activity with the sequence of nickel nitrate,ammonium nitrate,the to add precursor,and it could reduce sulfur content of diesel to 11.67 ppm after treatment,with the desulfurization rate is 97.67%.The catalyst characterization results shows that the hydrodesulfurization reaction of dibenzothiophene class is structure-sensitive,and because of that the surface structure and the crystal of the active component of the catalyst have a significant impact in activity.The elemental Ni may be beneficial for the hydrodesulfurization of dibenzo-thiophene class.Adding Ti components helps to improve the quantity of acid strength and the number of acid centers on the catalyst surface.And there is a relatively good correlation between the number of weak acid centers and the catalyst activity.Liquid paraffin of the heat treatment process will not have a great impact on the contact of the catalyst powder with the reactants,and could ensure full contact of the catalyst and diesel components.Prepared the catalyst supported by carrier of single A1 component with the use of different sequence of adding raw materials.The study found that AlO(OH)is stable in the reaction process,and catalyst has good activity while sequence of adding Precursor is nitrate,nickel nitrate,ammonium molybdate.