Study On Synthesis And Modification Of Environmental Catalyst For Removing Trace Olefins From Aromatics

As the increasing demand of environment protection,removal of trace olefins from aromatics has become a hot spot.Clays modified by environmental methanesulfonate with kneading method was synthesized and tested for removal of olefins from aromatics in this paper.Laboratory experiments indicated that clays modified with copper methanesulfonate improved the conversion of olefins and prolonged the lifetime,and the optimal temperature of the reaction is 175 ?.A series of synthesized catalyst samples were characterized by XRD,TG-DSC,N2 adsorption analysis and FTIR pyridine adsorption?py-FTIR?to study the relation of its performance and structure.The characterization results showed that the increase of its acidity after modification is the fundamental reason for the increase of catalyst activity.Besides,the novel and promising solid superacid catalyst S₂O₈^2-/ZrO₂?S₂Z?,by incorporation of persulfate in zirconia,was successfully synthesized by a co-precipitation method and was first utilized for removal of olefins from aromatics.A series of synthesized catalyst samples were characterized by XRD,SEM,TG-DSC,FTIR,N₂ adsorption analysis and FTIR pyridine adsorption?py-IR?.S₂O₈^2-/ZrO₂ catalyst was found to be superiorly active and efficiently reusable,giving available reactivity even after a long time use,which exhibited promising application prospects in industry.The optimum precursor for synthesizing S₂O₈^2-/ZrO₂ was precipitated by ammonium hydroxide with a terminal pH value over 9.28.The final catalyst impregnated with 1.5 mol/L solution and calcined at 650 ?,performed optimally for the purification of aromatics.The addition of S₂O₈^2-increased the dispersion of catalytically active t-ZrO2 and stabilized the structure of smaller crystallite t-ZrO₂,which was favorable to increasing the abundance of acid sites,improving surface properties as well as enhancing the activity.Meanwhile,Al₂O₃ was used as modifier to reduce the complexity of the preparation process,and finally the composite can greatly reduce costs of the production and make S₂O₈^2-/ZrO₂ very promising in industry.