A Study On Hybrid Membranes Of Adsorption Desulfurization For Fluid Catalytic Cracking (FCC) Gasoline

With the environmental regulations increasingly stringent all over the world,the standard for the sulfur content in gasoline are getting more and more strict.74%of gasoline product in china and furthermore 85-95%of sulfur of gasoline product come from the catalytically cracked gasoline.Therefore reduce the content of sulfur in FCC gasoline was the key for improving the quality of gasoline.Adsorption desulfurization has the advantages of selectivity,low investment,mild condition,low operation cost and holding the octane number,the fixed or fluid bed were applied in the most adsorption desulfurization techniques.Adsorption desulfurization has some defects,such as the smaller specific surface area and the smaller adsorption capacity of the adsorber,but Gasoline desulfurization by membrane process is a newly technology.The process offers a number of potential advantages compared to conventional desulfurization process.In this dissertation,Intergrative system adsorption desulfurization with membrane technology will be used to desulfurize for the catalytically cracked gasoline.Ce(Ⅳ)-loaded Y-zeolites(CeY)were prepared for selective removal of the sulfur compounds from gasoline model.The CeY samples can be prepared from Na-Y-zeolite using liquid-phase ion-exchange methods.The properties such as structures,specific surface area and static adsorptions of sulfur compounds of the CeY samples were investigated using XRD,IR,SEM and other analyzer.The CeY-zeolite with one time ion-exchange and one time calcine has much adsorption capacity than Na-Y-zeolite.CeY/PES hybrid membranes were prepared by a phase separation method,using PES as membrane matrix material,CeY as functional group,NMP as solvent, PEG-400 and PVP as additives.Several factors affecting formation and characteristics of the hybrid membrane(concentration of polymer and additives,temperature and constitution of coagulation bath,et al)were studied.The membranes morphology change sponginess from asymmetry.The membranes had high pure water flux and showed high BSA rejection.CeY/PES hollow fiber hybrid membranes were prepared by the dry-wet spinning process.The effects of species of additives,temperature of casting solution and concentration of interior liquid on the morphology of membrane were studied.The membranes have spongy morphology.This structure make adsorber particles disperse in the membrane evenly.Accordingly,the sulfur mixture could have more chances to touch the adsorber and the mechanical strength of the membrane was well.The adsorption and desorption performance of the membrane adsorber were investigated.The adsorption with high velocity could reach saturation within four hours.The adsorption velocity is decreased but the adsorption capacity is increased with low temperature.The adsorption capacities was 21.5mgS/g membranes at 5℃. The desorption ratio of sulfur could reach 65.7%when the ethanol was used as diluter.