ZnO添加量对Pd/Zr0.5Al0.5O1.75催化剂净化稀燃天然气汽车尾气性能的影响

以掺杂不同含量ZnO的Zr_0.5Al_0.5O_1.75为载体，制备了系列1.5%Pd催化剂.在模拟稀燃天然气汽车尾气条件下，测试了催化剂的活性和抗水性，并用N₂吸附-脱附、X射线衍射、H₂程序升温还原和X射线光电子能谱等手段对催化剂进行了系统表征.研究结果表明，ZnO的添加及添加量对催化剂的活性和抗H₂O性有明显影响，其中以ZnO添加量为15%时制备的复合氧化物为载体的催化剂活性最佳.当模拟尾气中不含H₂O时，该催化剂对甲烷的起燃温度（T₅₀）和完全转化温度（T₉₀）分别为278和314℃；在含H₂O时，该催化剂的T₅₀和T₉₀分别为342和371℃.

Effects of ZnO content on the performance of Pd/Zr0.5Al0.5O1.75 catalysts used in lean-burn natural gas vehicles

Mixed oxides obtained by adding varying amounts of ZnO into Zr_0.5Al_0.5O_1.75 were used as supports to prepare 1.5% Pd catalysts. The catalyst activity and H₂O tolerances of the catalysts were evaluated in a gas mixture simulating the exhaust of lean-burn natural gas-fueled vehicles. The catalysts were further characterized by N₂ adsorption-desorption, X-ray diffraction, H₂ temperature programmed reduction and X-ray photoelectron spectroscopy. The catalytic activity was greatly influenced by ZnO contents in Zr_0.5Al_0.5O_1.75 support. The catalyst containing 15% ZnO exhibited a light-off temperature and complete conversion temperature for CH₄ in the absence of H₂O of 278 and 314℃, respectively; while these same values in the presence of H₂O were 342 and 371℃, respectively. These results indicate that this combination of materials offers excellent catalytic activity at low temperature and also exhibits significant H₂O tolerance.