The NO selective reduction on the La1-xSrxMnO3 catalysts

La1-xSrxMnO3 (x = 0, 0.1, 0.3, 0.5, 0.7) perovskite-type oxides (PTOs) were prepared by coprecipitation under various calcination temperature, and their performances for the NO reduction were evaluated under a simulated exhaust gas mixture. The X-ray diffraction (XRD) and thermogravimetric analysis were carried out to find the formation process of the perovskite. The NO reduction rate under different reaction temperature, the concentration of oxygen and the presence of hydrocarbon were observed by the input/output analysis. In the presence of 10% excess oxygen, the catalyst La0.7Sr0.3MnO3 calcined at 900degreesC showed a NO reduction rate of 61% at 380degreesC. The study of the reaction curves showed that C3H8 could act as the reducer for the NO reduction below 400degreesC. The NO reduction is highly affected by increasing the O-2 concentration from 0.5 to 10%, especially at high temperatures when oxygen becomes more competitive than NO on the oxidation of C3H8, leading to a decrease of the NO reduction from 100% to zero at 560degreesC. (C) 2004 Elsevier B.V. All rights reserved.