Surface Tuning of La0.5Sr0.5CoO3 Perovskite Catalysts by Acetic Acid for NOx Storage and Reduction

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• 作者：Yue Peng ; Wenzhe Si ; Jinming Luo ; Wenkang Su ; Huazhen Chang ; Junhua Li ; Jiming Hao ; John Crittenden
• 刊名：Environmental Science & Technology
• 出版年：2016
• 出版时间：June 21, 2016
• 年：2016
• 卷：50
• 期：12
• 页码：6442-6448
• 全文大小：588K
• 年卷期：0
• ISSN：1520-5851

文摘

Selective dissolution of perovskite A site (A of ABO₃ structure) was performed on the La_1 – xSr_xCoO₃ catalysts for the NO_x storage and reduction (NSR) reaction. The surface area of the catalysts were enhanced using dilute HNO₃ impregnation to dissolve Sr. Inactive SrCO₃ was removed effectively within 6 h, and the catalyst preserved the perovskite framework after 24 h of treatment. The tuned catalysts exhibited higher NSR performance (both NO_x storage and NO-to-NO₂ oxidation) under lean-burn and fuel-rich cycles at 250 °C. Large amounts of NO_x adsorption were due to the increase of nitrate/nitrite species bonding to the A site and the growth of newly formed monodentate nitrate species. Nitrate species were stored stably on the partial exposed Sr²⁺ cations. These exposed Sr²⁺ cations played an important role on the NO_x reduction by C₃H₆. High NO-to-NO₂ oxidation ability was due to the generation of oxygen defects and Co²⁺–Co³⁺ redox couples, which resulted from B-site exsolution induced by A-site dissolution. Hence, our method is facile to modify the surface structures of perovskite catalysts and provides a new strategy to obtain highly active catalysts for the NSR reaction.