Study On Alkylation Transfer Of Thiophenic Sulphur In FCC Gasoline Catalyzed By Y

Due to the increasingly stringent environmental regulations, Ultra-low sulfur or “zero”gasoline will be extremely urgently produced for refineries. At present, hydrodesulfurizationis the most important and popular technologies for removing sulfur in gasoline, and itsdesulfurization effect is not ideal because a mass of thiophene sulfide with stable structureexists in FCC gasoline. Hence, non-hydrodesulfurization emerges as the times require andmakes up for the shortage of hydrodesulfurization. Olefinic alkylation of thiophenic sulfur（OATS），One of the non-hydrodesulfurization approaches, utilizes an acidic catalytic processto alkylate thiophenic sulfides with olefins in FCC gasoline, bringing about the increase inthe molecular weight of thiophenic compounds, and the heavier sulfides with higher boilingpoints can be removed from gasoline by distillation. Therefore, we can obtain light clean fuel.In this paper, HY zeolites made from ion-exchange were used as alkylation catalyst, thecatalytic effects of HY zeolites concerning two kinds of Si/Al （HY-1: the ratio Si to Al is4.8;HY-2: the ratio Si to Al is5.3）, including the reaction temperature, reaction time, the ratio ofcatalyst to oil and rotate speed on FCC gasoline desulfurization were investigated to seek outthe optimal reaction conditions；and the catalysts modified before were characterized by XRD,NH3-TPD, TG and BET, which were the same as the the catalysts modified after and the HYzeolites alkylation before and after. Then the oil of the alkylation before and after wasanalysed by GC-SCD and GC-FID.Meanwhile, on the basis of above experiment, the stability of the HY-2zeolites catalystand the influence factors were also discussed．Finally, the overall kinetics of alkylation by HY-2was researched and the kineticsequation was established．The results showed that the modified HY zeolites were provided with favourablealkylation performance, the appropriate reaction temperature of HY-1and HY-2wasrespectively130℃and160℃, while HY-1catalysed the thiophene sulfur in the FCC gasoline and the reaction conditions were at130℃,1h, Mcatalyst: M_gasoline=1:10and420r/h, the sulfurconcentration in light distillates declined to10.70mg/L and the rate of sulphur conversion was91.01%, which distilled point was at120℃, however, while utilizing the HY-2zeolitecatalyzing the alkylation and the reaction conditions were at160℃,1h, Mcatalyst: M_gasoline=1:10and420r/h, the sulfur concentration in light distillates droped to9.33mg/L and theconversion rate of sulphur was92.16%, whose distilled point was at120℃. GC-SCD analysisindicated that the large portions of the sulfur compounds were transfer to heavy fraction fromlight fraction by alkylation. The hydrocarbon composition analysed that the major olefinsparticipating in alkylation were isomericolefines, such as C5and C6, and its octane numberonly dropped about0.2units compared with the feedstock.The stability experiment proved that the stability of catalyst was reduced after severalreaction times. The main cause was not the collapse of crystal structure，or the loss of surfaceacid amount．This could be attributed to the organic macromolecular packaging the surface ofthe catalyst rather than the acid amounts were lost in the alkylation process, then the stabilityof the catalyst was decreased．By means of kinetics study on HY-2catalysing the alkylation in FCC gasoline, owing tothe constant concentration of olefins, the kinetics equation of thiophnic sulfur compoundswas fit to r=kC．...