Influences of Calcination Temperature on Pt-SO42-/ZrO2-Al2O3 Catalysts and Their Catalytic Performance for Isobutane Isomerization
A series of solid superacid catalysts of Pt-SO42-/ZrO2-Al2O3 calcined at different temperatures were prepared.The physicochemical properties of Pt-SO42-/ZrO2-Al2O3 catalysts were characterized by N2 adsorption-desorption,XRD and XPS.Moreover,isobutane isomerization was defined as the model reaction to investigate the effect of calcination temperature on catalyst performance.The results show that when the calcination temperatures increase gradually from 680 ℃ to 780 ℃,the specific surface areas of the catalysts decrease,the pore sizes increase,and the sulfur contents decrease.Zirconia is still dominated by tetragonal phase,and there is no obvious crystal transformation.Pt-SO42-/ZrO2-Al2O3 catalyst calcined at 720 ℃(PSZA720)has the highest S and Zr electron binding energy and S distribution density,the highest acid strength and the highest isobutane isomerization activity.At the hydrogen/hydrocarbon molar ratio of 0.1,reaction temperature of 200 ℃,reaction pressure of 1.8 MPa and mass space velocity of 2 h 1 for isobutane,the isobutane conversion and n-butane selectivity on PSZA720 catalyst can reach 43.9％and 71.7％,respectively.
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