耐高温高比表面Ce_xZr_(1-x)-Al复合氧化物的制备及其单Pd型三效催化性能的研究

Preparation of Ce_xZr_(1-x)-Al mixed oxides and investigation of the palladium-only three-way catalytic performance

利用溶胶-凝胶法和超临界干燥法相结合的技术制备了系列CexZr1-xAl复合氧化物，采用BET、XRD等技术进行了表征，并研究了其负载Pd催化剂的三效性能．BET和xRD结果表明，CexZr1-x-Al复合氧化物具有良好的热稳定性，经1100℃焙烧4h后仍具有较大比表面积（〉95m^2·g^-1），无α—Al2O3产生．TEM和催化剂活性评价表明，含有铈锆固溶体的负载Pd催化剂具有良好的催化活性和耐热稳定性，其中Pd／Ce0.75 Zr0.25-Al的催化性能最好，CO、C3H6、NO和NO2的起燃温度（T20％）分别为140、268、340、175℃，经1100℃焙烧4h后对各气体组分的完全转化温度仅提高10～20℃．

The CexZr1-x-Al mixed oxides were prepared by the sol-gel method and the super-critical dryness method. The samples were characterized by means of XRD and BET techniques, and the three-way catalytic performance of their supported-Pd catalysts was also investigated. It was found that the samples calcined at 1 100 ℃ for 4 h still had large specific surface area（〉95 m^2 · g^-1） and no α-Al2O3 was formed. Based on the TEM and the investigation of catalytic performance, the catalysts containing cerium zirconium solid solution had good catalytic activity and thermal stability, and the three-way catalytic performance of Pd/Ce0.75 Zr0.25-Al was best. The catalyst Pd/Ce0. 75 Zr0.25-Al had low light-up temperatures （T20%） of 140 ℃, 268 ℃, 340℃ and 175 ℃ for CO, C3H6, NO and NO2, respectively, and the temperatures at which the reactants were converted fully were only raised by 10-20 ℃ after thermal aging.