Ce/Zr比对PdO/Ce_xZr_(1-x)O_2催化剂三效催化性能的影响

Effect of Ce/Zr Atomic Ratio on the TWC Properties of PdO/Ce_xZr_(1-x)O_2(x=0-1.0) Catalysts

采用溶胶-凝胶法制备一系列CexZr1-xO2(x=0～1)复合氧化物,并以该复合氧化物为载体制备负载贵金属的PdO/CexZr1-xO2(x=0～1)催化剂,选择NO-CO反应和CO以及CH4氧化反应为模型反应对催化剂的三效催化性能进行评价,并通过XRD、H2-TPR等手段对载体和催化剂进行初步表征。结果表明:Ce/Zr比对CexZr1-xO2载体及负载PdO催化剂三效催化性能均存在重要影响,不同Ce/Zr比的CexZr1-xO2复合氧化物载体具有不同的晶相结构及还原性能,由其负载的PdO催化剂的三效催化性能也各不相同。同时,催化剂的NO还原活性与CO氧化活性与α还原峰存在一定的对应关系。

The CexZr1-xO2 (x=0-1) composite oxides were prepared by sol-gel method, and then they were used as supportpr tp prepare PdO/CexZr1-xO2 catalysts. The effect of Ce/Zr atomic ratio on the structure of crystalline phase, redox property and TWC catalytic activity of CexZr1-xO2 composite oxides and PdO/CexZr1-xO2 catalysts were studied. The results show that phase structure of CexZr1-xO2 composite oxide depends on the CeO2 content. The different Ce/Zr atomic ratio affects the catalytic activity of PdO/CexZr1-xO2 catalysts much. In the reaction of NO-CO and CO-O2, the catalytic activity of PdO/Ce0.8Zr0.2O2 catalyst is the highest. However, the catalytic activity of PdO/Ce0.5Zr0.5O2 catalyst is the highest in the reaction of CH4-O2. The α: H2-TPR peak is related probably to the NO-CO and CO-O2 catalytic activity of PdO/Ce0.8Zr0.2O2 catalysts.