Cu/SO2-4/La2O3-ZrO2-Al2O3 catalyst:: Preparation and catalytic performance on the selective reduction of NO with propylene

Cu/SO42-/LaO3-ZrO2-Al2O3 catalyst was prepared by La2O3-ZrO2-Al2O3 composite support modified with SO42- followed by loading with Cu2+. The composite support was made of Al2O3 matrix added with ZrO2 and La2O3. The catalytic effects on the selective reduction of NO by propylene in excess oxygen were investigated. The relationship of structure and property of Cu/SO42-/La2O3-ZrO2-Al2O3 catalyst was also explored by means of XRD, SEM, TG, Py-IR, NH3-TPD, FTIR and TPR. The results indicate that the addition of ZrO2 contributes mainly to the increase of the catalytic activity in low temperature of the title catalyst; whilst the addition of La2O3. contributes mainly to the enhancement of the thermal stability and reducibility of the catalyst; the SO42- is able to combine with Zr to form a chelate bidentate state favorable for an increase of the acid quantity on the surface of the catalyst and the acidity. Consequently, the catalytic activity and hydrothermal stability of the catalyst to the selective reduction of NO with propylene in excess oxygen have been improved effectively. Under the condition free from water vapor, Cu/SO42-/La2O3-ZrO2-Al2O3 catalyst could make the conversion rate of NO up to a degree of 84.3%,even at temperature of 275 degrees C with the present of 10% water vapor, the conversion rate of NO could also reach to 81.2%.