Support effect on the NO_x storage and sulfur-resisting performance of the NO_x trap catalysts Pt/Li/TiO₂¨CMO_x (M = Al, Zr, Si, Sn)

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• 作者：Ming  ; Meng  ; ;   ; ^{mengm@tju.edu.cn} ; Lihong  ; Guo ; Junjun  ; He ; Youlei  ; Lai ; Zhaoqiang  ; Li ; Xingang  ; Li
• 关键词：Lithium ; TiO₂&ndash ; MO_x(M = Al ; Zr ; Si ; Sn) oxides ; NO_x storage ; Sulfur-resistance ; Pt dispersion
• 刊名：Catalysis Today
• 出版年：2011
• 出版时间：25 October 2011
• 年：2011
• 卷：175
• 期：1
• 页码：72-77
• 全文大小：622 K

文摘

A series of Li-based lean-burn NO_x trap (LNT) catalysts Pt/Li/TiO₂¨CMO_x (M = Al, Zr, Si, Sn) were prepared by sequential impregnation with the supports TiO₂¨CMO_x synthesized by co-precipitation. The support effect on the NO_x storage and sulfur-resisting performance of Pt/Li/TiO₂¨CMO_x catalysts was investigated carefully. The NO_x storage capacity of fresh Pt/Li/TiO₂ is greatly improved by doping with Al₂O₃ or ZrO₂ due to the remarkably increased specific surface area and the oxidation ability of the catalysts. HR-TEM and H₂-chemisorption results reveal that the oxidation ability of Pt/Li/TiO₂¨CMO_x is mainly determined by Pt crystallite size. Larger Pt crystallites correspond to stronger oxidation ability. The regeneration of sulfated Pt/Li/TiO₂¨CMO_x strongly depends on the total acidity of the supports, including Br?nsted and Lewis acid; the supports with larger acidity possess higher ability of sulfur-resistance and regeneration. The results of in situ DRIFTS show that over Pt/Li/TiO₂¨CMO_x (M = Al, Zr, Si, Sn) NO_x is mainly stored as ionic nitrate species at 350 ¡ãC. Taking the NSC and regeneration ability into account, the catalyst Pt/Li/TiO₂¨CAl₂O₃ is the most promising one for practical application.