Pilot Scale-up Study On Reactivation Of Spent S-Zorb Adsorbents For Gasoline Desulfurization

The S-Zorb process is a technology for reactive adsorption desulfurization of Fluid Catalytic Cracking gasoline.This process achieves deep desulfurization of gasoline and produces a large amount of spent adsorbents.These spent adsorbents are classified as hazardous wastes because they contain metal species such as Ni.However,no resource utilization has been made for this type of hazardous waste up to now.Using chemical methods to reactivate the spent adsorbent to rebuild the structure and restore the desulfurization activity will fundamentally solve the problem of S-Zorb spent adsorbent treatment.This can effectively avoid environmental pollution caused by spent adsorbents,reduce the input amount of fresh adsorbents in the production process,and generate greater social and economic benefits.In this paper,based on reactivating S-Zorb spent adsorbent with inorganic acid-base coupling,the reactivation conditions are further optimized,and 0.5 L,1 L and 10 L stepwise scale-up experiments were performed.The fluid mechanics simulation method is used to explore the influence of the structural changes of the reactor on the structure composition and desulfurization activity of the reactivated adsorbent and the scale-up effect in the reactivation process is explained.In addition,the reactivation pilot process is constructed,the 3000 L scale industrial pilot test was completed,and the pilot test path for the reactivation of the spent adsorbent is clarified.By screening different reactivation conditions,the reactivation treatment temperature and the amount of precipitant are reduced.The reactivated adsorbent with homogeneous dispersion of surface-active metals is prepared by the dispersion co-precipitation method and the impregnation method.The quantity ratio of Ni O and Zn O on the surface of the adsorbent is further optimized,so that the different active phases of the reactivated adsorbent has a synergistic effect.The desulfurization performance is improved,and the induction period of the adsorbent desulfurization reaction is shortened.The dispersion co-precipitation method is more effective than the impregnation method to adjust the metal composition of the adsorbent surface.Through the scale up test,combined with fluid mechanics software simulation,the reactivation scale-up effect is clarified,and the process route for the reactivation of the spent adsorbent is proposed.The adsorbents reactivated at different scales all show excellent desulfurization activity,and as the scale increases,the crystal size of the active phase in the adsorbent decreases significantly,and the desulfurization activity steadily increases.The adsorbent reactivated at the 3000 L scale can reduce the sulfur content in gasoline to 1.19 ppm,and the desulfurization activity is greatly improved.The fluid dynamics simulation results show that the solid-liquid mixing system has obvious sidewall effects.With the increase of the processing scale,the concentration distribution of the spent adsorbent particles becomes uniform,and their contact with the reactivation reagent becomes sufficient,which completely changes the phase structure composition of the waste adsorbent,thereby greatly improving the desulfurization performance.