Preparation of Cu/La2O3-ZrO2-Al2O3 catalyst and its catalytic properties for selective reduction of NO

The La2O3-ZrO2-Al2O3 composite support was prepared by coprecipitation method with the mixed aqueous solution of La(NO3)3, Al(NO3)3, and ZrOCl2 dropping into the precipitant of (NH4)2CO3 aqueous solution. The Cu/La2O3-ZrO2-Al2O3 catalyst was prepared by the impregnation of La2O3-ZrO2-Al2O3 with active component Cu2+ aqueous solution. The effects of the catalyst on the selective catalytic reduction of NO with propylene in excess oxygen were investigated. The relationships among the preparation method, structure, and properties of the Cu/La2O3-ZrO2-Al2O3 catalyst were also explored by means of Scanning electron microscope(SEM), X-ray diffraction（XRD）, Surface area measurements (BET), Pyridine absorption infrared spectrum (Py-IR), Thermalgravimetry(TG), and Temperatureprogrammed reduction (TPR). The results indicate that the support γ-Al2O3 prepared by Al(NO3)3 dropping into (NH4)2CO3 can remarkably enlarge the surface area; the addition of La2O3 contributes mainly to the enhancement of the thermal stability; the introduction of ZrO2 can increase the amount of Lewis and Brφnsterd acid. Consequently, the catalyst Cu/La2O3-ZrO2-Al2O3 has excellent activity for the selective reduction of NO with propylene in excess oxygen. The NO conversion is up to 88.9% at 300℃ and 81.9% even at the presence of 10% volume fraction of water vapor.