Zr基载体负载Pd催化剂用于贫燃天然气汽车尾气净化

Pd Catalysts Supported on Zr-Based Materials Used in Lean-Burn Natural Gas Exhaust Combustion

采用共沉淀法制备了ZrO2,Y0.1Zr0.9Ox,Ce0.1Zr0.9Ox和Al0.1Zr0.9Ox系列Zr基载体,并用N2吸附-脱附和X射线衍射对其进行了表征.再以此为载体,采用浸渍法制备了整体式负载Pd催化剂,催化剂涂层的涂覆量为180g/L左右,Pd含量为1.25%.测定了催化剂上Pd的分散度.在模拟的贫燃天然气汽车尾气中考察了催化剂的活性,并在尾气中有或无SO2存在的条件下比较了催化剂活性的差异.结果表明,Y3+,Ce4+或Al3+改性载体负载的Pd催化剂的耐硫性能明显改善;无论尾气中是否存在SO2,以Y3+或Al3+改性载体负载的Pd催化剂的活性均明显高于ZrO2负载体的Pd催化剂.

A series of Zr-based supports such as ZrO2, Y0.1Zr0.9Ox, Ce0.1Zr0.9Ox, and Al0.1Zr0.9Ox were prepared by a co-precipitation method. The physicochemical properties of the supports were characterized by N2 adsorption-desorption （the Brunauer-Emmet-Teller method） and X-ray powder diffraction. The Pd-based catalysts were prepared with Pd supported on these supports by the impregnation method. The Pd dispersion on the catalyst surface was characterized by CO chemisorption. The activity of the Pd-based catalysts in a simulated mixture gas from lean-burn natural gas vehicles with and without SO2 was tested. The results indicated that ZrO2 modified by Y^3＋, Ce^4＋, or Al^3＋ improved the resistance of the catalysts to sulphur poisoning. The modification of Pd/ZrO2 with Y^3＋ or Al^3＋ led to more active than the Pd/ZrO2 catalyst no matter with or without SO2 in the simulated gas.