镧、铈比对Pd-TWC性能的协同效应

The Synergestic Effect of Lanthanium-Cerium Ratio on Catalytic Properties of Pd-TWC

摘要: 研究了以宜兴堇青石蜂窝体为载体,γ-Al₂O₃为洗涂层的La和Ce的催化活性与La、Ce物质量的比例关系;探讨了 La、Ce配比对 Pd-TWC性能的影响.结果表明, Pd-TWC对汽车尾气中 CO、HC、NO的催化活性随 La、Ce比的不同而变化,当 n(La):n(Ce)=1:4时,催化活性最好,此时,其表面过剩氧量最多; XPS分析表明 Ce以十 3、+ 4价共存,且Ce⁴⁺所占比例在所有样品中最大,为60%. La、Ce虽为性质相近的稀土元素。

Abstract: The relationship between the activity of La-Ce Catalysts and molar ratio of La-Ce was studied in the paper. These catalysts were prepared by impregnation method using cordierite holeycomb monoliths obtained from Yixing coated by γ-Al₂O₃ as carrier. The effect of the molar ratio of La-Ce on the property of Pd-TWC was also studied. consults showed that the catalytic astivity of Pd-TWC in Purifying CO, HC and NO varied with the ratio of La-Ce. The best catalytic activity was obtained when the ratio was l:4. Under this circumstances, the amount of resodual oxygen on its surface was largest. XPS results showed that Ce⁴⁺ coexited with Ce³⁺ and the relative amount of Ce⁴⁺ is the biggest in all the samples and equaled 60%. La and Ce had a synergestic action on improving catalytic astivity of Pd-TWC.