| A three-way catalyst comprised novel oxygen storage materials for emission control in natural gas powered engines was prepared. The three-way catalysts were prepared by impregnation and their three-way catalytic activities were evaluated. Moreover, TPD and TPR were used to characterize the catalysts.The two key materials (alumina and oxygen storage material) for three-way catalysts were prepared and studied. It was proved that the alumina has good performance of high-temperature-resistant, and the novel oxygen storage material has large surface area and high oxygen storage capacity. The addition of novel oxygen storage components to the Pd/γ-Al2O3 catalysts resulted in improved fresh and aged activities by lowering the light-off temperature for methane. When 5 wt% of MnOx was added, the catalyst exhibited the lowest light-off temperature for methane ( 280oC), and the NOx and CO were removed perfectly.The space velocity performance and the A/F window were mainly considered in the evaluation of catalysts. The space velocity influenced light-off performance greatly, so it is very important to improve the preparation technology for Pd-only three-way catalysts.It was found that the additives La2O3,SrO, especially ZrO2, could improve the activities and thermal stability of Pd-only three-way catalysts greatly; ZrO2 could promote the three-way catalytic performance remarkably. The effects of Pd weight loading were examined as well. The catalytic activity of catalysts increased as the amount of Pd increased to 1.5g/l, and little change in performance was observed at higher loadings. Hydrothermal ageing was performed at 1000oC for 5 h, in the presence of 5 vol% H2, 10 vol% H2O and 85 vol% N2. The aged catalysts exhibit higher activity and better thermal stability than traditional three-way catalysts. |
