Characterization and reactivity of Ce-promoted PtBa lean NO_x trap catalysts

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• 作者：A. Infantes-Molina^b ; L. Righini^a ; L. Castoldi^a ; C.V. Loricera^b ; J.L.G. Fierro^b ; A. Sin^c ; L. Lietti^a ; ^{luca.lietti@polimi.it}
• 关键词：Pt-Ba/Al2O3 catalyst ; Ceria ; NOx storage ; NOx reduction mechanism ; LNT systems ; Temperature programmed surface reaction
• 刊名：Catalysis Today
• 出版年：2012
• 出版时间：15 December, 2012
• 年：2012
• 卷：197
• 期：1
• 页码：178-189
• 全文大小：2181 K

文摘

The effect of cerium addition to a model Pt-Ba/Al₂O₃ lean NO_x trap catalyst (LNT) is investigated in this paper by a combination of characterization techniques and reactivity experiments. It is found that the presence of Ce does not alter the morphological and structural characteristics of the catalyst, although slight changes in the Ba-carbonate phase are apparent. On the other hand, the presence of Ce does not seem to affect significantly the characteristics of Pt, in particular its redox state. CO adsorption experiments pointed out the presence of Pt¡ã particles presenting different coordination degree, whose characteristics are however not significantly affected by the presence of Ce.

The storage capacity of the PtBa/Al sample is hardly affected by the presence of Ce; however Ce favours the thermal decomposition of the stored NO_x species. The Ce-doped sample also shows a slightly higher reactivity in the reduction of the stored NO_x by H₂: in fact the reaction is monitored at lower temperatures. A slightly higher selectivity towards the formation of N₂ is also observed.