一个新的满足未来排放标准的摩托车尾气净化催化剂

采用共沉淀法制备CeO₂-ZrO₂-La₂O₃-PrO₂-Al₂O₃复合氧化物载体材料，以浸渍法制备了Pd-Rh，Pt-Rh和Pt-Pd-Rh型整体式催化剂. 用N₂吸附-脱附、程序升温还原、储氧量和X射线衍射对其进行了表征，并考察了老化前后催化剂的空燃比特性、空速特性和温度特性. 结果表明，在三种催化剂中，Pt-Pd-Rh型催化剂表现出更优异的性能. 在40000 h^-1空速下，新鲜Pt-Pd-Rh型催化剂对C₃H₈，CO和NO的起燃温度T₅₀分别为239，187和191 ℃，ΔT （T₉₀ - T₅₀）分别为21，3和3 ℃. 老化后，C₃H₈，CO和NO的T₅₀分别为298，203和223 ℃，ΔT分别为22，5和13 ℃，且老化前后空燃比窗口较宽，适合于未来排放标准的摩托车尾气净化.

A new monolithic Pt-Pd-Rh motorcycle exhaust catalyst to meet future emission standards

A new composite oxide material as support, CeO₂-ZrO₂-La₂O₃-PrO₂-Al₂O₃, was synthesized by a co-precipitation method. Pd-Rh, Pt-Rh, and Pt-Pd-Rh supported on monolithic carrier catalysts were obtained by an impregnation route. The textural, structural, and reductive properties of the catalysts were characterized by N₂ adsorption-desorption, temperature-programmed reduction, oxygen storage capacity measurements, and X-ray diffraction. The air-fuel-ratio (A/F), space velocity (SV), and temperature characteristics of the fresh and aged catalysts were investigated on a systematic basis. The results showed that among the three catalysts, Pt-Pd-Rh displayed the best performance. For an SV of 40000 h^-1 in the case of fresh Pt-Pd-Rh, the light-off temperatures (T₅₀) for C₃H₈, CO, and NO were 239, 187, and 191 ℃, respectively, with corresponding ΔT (T₉₀-T₅₀) values of 21, 3, and 3 ℃, respectively. After aging, the T₅₀ for C₃H₈, CO, and NO were 298, 203, and 223 ℃, respectively, and the ΔT values were 22, 5, and 13 ℃, respectively. Moreover, the window widths for the A/F in the case of fresh and aged Pt-Pd-Rh catalysts were wide. Overall, the excellent performance for the Pt-Pd-Rh catalyst makes it suitable as a motorcycle exhaust catalyst, which can meet future emission standards.