Integrated Study On Solid Superacid Catalyst That Prepared By Microemulsion Method For Normal Paraffin Isomerization

Recently S_aO_b^2-/M_xO_y solid superacid catalysts,have attracted much attention of the researchers,due to their strong acidity,improved selectivity,easy to preparation,no pollution and high reusability.In this paper,the Pt-S₂O₈^2-/ZrO2-AlO3?Pt-SZA-M?solid superacid catalyst was prepared by microemulsion method for the first time.The catalysts were characterized by FT-IR?XPS?TG-DTA?XRD?TPR?SEM?BET and TEM.The isomerization performance of catalysts prepared with different microemulsion method,calcination temperature,Pt content and Al2O3 were inspected by using the reaction of n-pentane isomerization.The results show that the tetragonal phase of ZrO2 in Pt-SZA-M catalyst formed gradually with the increase of calcination temperature,at the same time the diameter of particles increase,the surface area and S content decrease,when the calcination temperature reaches 650 ?,the quantity of tetragonal phase,surface area and S content reaches a perfect balance,though gets the best activity;The addition of Pt can coordinate the Pt and S=O,then improves the ability of adsorption of 02,enhance the acid strength and thermal stability of Pt-SZA-M catalyst,the appropriate quantity of Pt is 0.1%,the acid strength and thermal stability of Pt-SZA-M will decrease when the Pt content is more or less than 0.1%.When the A1 was added with the formation of aluminium nitrate or Al2O3,it can improve the formation of tetragonal phase of ZrO2 and the surface superacid,enhance the surface area and oxidative activity of catalyst.Comparatively the pseudoboehmite and ?-Al2O3 are more stable,they have low ability to improve the tetragonal phase of ZrO2,surface acid and oxidative activity of catalyst.the Pt particles on Pt-SZA-M were smaller?4.5nm?and more uniform size;the specific surface area of Pt-SZA-M was 109.6 m2·g-1,which was 15.4%higher than that of Pt-SZA?95.0 m2·g-1?.The initial reduction temperature of Pt-SZA-M was decreased by 10-20? compared with the Pt-SZA,which indicated that loading Pt by microemulsion method could improve the oxidative activity of catalyst and enhance the dissociation adsorption ability of H2 on the surface of catalyst.The activity test of isomerization performance indicated that compared to the Pt-SZA,the activity of isomerization of the Pt-SZA-M under low temperature was significant improved,under the condition of reaction temperature is 230 ?,pressure is 2.0 MPa,the hydrogen/hydrocarbon molar ratio is 4:1 and the hourly mass space velocity?MHSV?is 1.0 h-1,the isopentane yield is 60.8%.