Preparation and Catalytic Properties Study of Solid Superacid Catalyst S_2O_8~(2-)/ZrO_2-Al_2O_3 Modified by Lanthanum

Solid superacid catalyst with the composition of S2O82-/ZrO2-Al2O3loaded with lanthanum was prepared by precipitation and impregnation method.The catalytic performance for the synthesis of tri-n-butyl citrate was investigated.The influences of introduction of La on the catalytic properties were fully characterized by means of FTIR,XRD and NH3-TPD analysis methods.The results showed that,catalyst prepared under the conditions of impregnation 0.5mol/L(NH4)2S2O8,with n(ZrO2)∶n(Al2O3)=1∶1and calcination at 600℃for 4h,the mass fraction of La(NO3)3used in solid superacid was 1wt.%exhibited good catalytic activity.The conversion of citric acid reached93.69%.La can increase the combining ability between S and O and inhibit decomposition of active components,improve the acid strength and the acidity of catalysts.