Study On Deep Desulfurization Process Of Catalytic Cracking Gas

With the increasing of the domestic crude oil,the sulfur content in FCC liquefied petroleum gas?LPG?is also getting higher and higher.FCC liquefied gas sulfur compounds are mainly hydrogen sulfide,sulfur,carbonyl sulfide and two sulfide,etc,after the process of hydrogen sulfide gas,liquefied gas still contains dozens of ?g/g sulfide,can not meet the production requirements.In this paper,the residual hydrogen sulfide and carbonyl sulfide are removed by the process of carbonyl sulfide hydrolysis,the process of oxidation of thiol converts small molecules mercaptans are converted into large molecular disulfide,at this time,the main sulfide of the liquefied petroleum gas is the high boiling point sulfide and the two sulfide.Finally,after the rectification cutting method,the top of the tower contains less sulfur content of light components C3 and light C4,tower bottom to get heavy C4,C5 and sulfide,so as to achieve the effect of the depth of the desulfurization of liquefied gas.This paper is investigating the oxidation of the thiol activator,carbonyl sulfide hydrolysis catalyst,thiol oxidation by Aspen simulation software,after COS hydrolysis LPG distillation process,investigating the overhead product sulfur content.The conversion process of mercaptan oxidation,sulfonated cobalt phthalocyanine as catalyst for oxidation of thiol,added activating agent in the reaction process: one or two kinds of A or B or C or D or F,studied on the effect of oxidation reaction.The experimental results indicated that: activation agent used D and C mixture,the ratio was 7:3,the temperature was30?,empty oil volume ratio of 300,space velocity 4 h-1,activation agent concentration was10%,the adding amount of 20 ?g/g,the desulfurization rate could be improved from 52.6% to99.16%.In this paper,the effects of COS hydrolysis catalyst carrier,active components and their additives on the activity of hydrolysis were investigated.The experimental results showed that the calcination temperature had a certain effect on the ?-Al₂O₃ catalyst,and the catalyst with high calcination temperature 750? was better.With the increase of TiO₂ content,the hydrolysis activity of TiO₂/?-Al₂O₃ catalyst was also increased.When the amount of TiO₂ was14wt%,the activity tended to be stable.TiO₂/?-Al₂O₃ catalyst supported on the P as active component,the catalyst of the alkaline enhanced,COS hydrolysis activity was significantlyimproved,when the amount of P was more than 10wt%,the catalytic activity is basically unchanged.Modificated P/TiO₂·?-Al₂O₃ by using the additive of double metal oxides?X and Y?,the experimental results showed that the first group was divided into Fe2O3,the second groups were divided into Y,and the X loading was 5% and the X:Y mass ratio was 5:1,the activity of the catalyst was the best.The optimized catalyst Y-X-P/TiO₂·?-Al₂O₃,in the optimal process conditions: the temperature was 30?,the amine flow was 3 ml/h,the carbonyl sulfur concentration in the raw material was 1000 mg·m-3,the desulfurization rate was 98.5%.Used Aspen Plus simulation software to simulate the distillation process optimization,Used Aspen Plus simulation software simulation and optimization of distillation column,the results showed the number of theoretical plates N was 37,the actual reflux ratio R was 1.3?molar ratio?,the optimum position of the feed NFwas 20.Obtained by simulation fractionator feed the material properties of the components,calculated the recoveries of components in the bottom and overhead of the tower,the product sulfur content in the overhead was 3.50?g/g.