Study On The Preparation Of Perovskite-type Nsr Catalysts Bafe_1-xti_xo₃ And Their No_x Storage And Sulfur Resistance Behaviors

In this paper, the sol-gel and impregnation methods were employed to prepare the BaFe_1-xTi_xO₃ (x=0.1, 0.2, 0.3) perovskite-type NSR catalysts. The BET, XRD, FT-IR, DRIFTS, H2-TPR, and XPS were employed to characterize the structure and adsorption/desorption properties of the catalyst. The NOx storage capacity (NSC) and sulfur resistance were also investigated and discussed with the results of the characterizations.The catalytic activity test showed that the sulfur resistance of BaFe_1-xTi_xO₃ catalysts was greatly improved by doping Ti in the BaFeO3 catalyst. When the proportion of the doped titanium reached 20 % by the impregnation method, the Imp-Ti0.2 sample exhibited the good NOx storage capacity as well as the high sulfur resistance, i.e. NSC = 1000μmol/g and the NSC only decreasing about 5.1 % comparing with the fresh catalyst. Nevertheless, after sulfation, the NSC of the BaFeO3 sample reduce 21.2 %,and the reduced ratio of the conversion of NO just was 31.3 %. The addition of titanium increased the surface area of the catalyst, leading to the excellent dispersion of the active sites on the catalyst, and also, the amount of BaCO3 formed during preparation also suppressed significantly. After sulfation, there were not only BaSO4 but also Fe2(SO4)3 formed on the surface of catalysts causing a slight decrease of the NSC. Calcinating the catalysts at higher temperature could reduce the quantity of BaCO3 in the perovskite-type catalyst, but the catalytic activity also decreased simultaneously. In conclusion, the Imp-Ti0.2-750 sample exhibited the best NOx storage capacity and sulfur resistence property.