Catalytic oxidation of diesel soot particulates over Ag/LaCoO₃ perovskite oxides in air and NO_x

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• 作者：Qi Fan ; Shuai Zhang ; Liying Sun ; Xue Dong ; Lancui Zhang ; Wenjuan Shan ; ^{wjshan@dicp.ac.cn" class="auth_mail" title="E-mail the corresponding author} ; Zaiming Zhu ; ^{zhuzaiming@lnnu.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Soot combustion ; NOx ; Silver ; Perovskite ; Thermal stability
• 刊名：Chinese Journal of Catalysis
• 出版年：2016
• 出版时间：March 2016
• 年：2016
• 卷：37
• 期：3
• 页码：428-435
• 全文大小：1591 K

文摘

Ag/LaCoO₃ perovskite catalysts for soot combustion were prepared by the impregnation method. The structure and physicochemical properties of the catalysts were characterized using X-ray diffraction, N₂ adsorption-desorption, H₂ temperature-programmed reduction, soot temperature- programmed reduction, and X-ray photoelectron spectroscopy. The catalytic activity of the catalysts for soot oxidation was tested by temperature-programmed oxidation in air and in a NO_x atmosphere. Metallic Ag particles were the main Ag species. Part of the Ag migrated from the surface to the lattice of the LaCoO₃ perovskite, to form La_1-xAg_xCoO₃. This increased the amount of oxygen vacancies in the perovskite structure during thermal treatment. Compared with unmodified LaCoO₃, the maximum soot oxidation rate temperature (T_p) decreased by 50–70 °C in air when LaCoO₃ was partially modified by Ag, depending on the thermal treatment temperature. The T_p of the Ag/LaCoO₃ catalyst calcined at 400 °C in a NO_x atmosphere decreased to about 140 °C, compared with that of LaCoO₃. Ag particles and oxygen vacancies in the catalysts contributed to their high catalytic activity for soot oxidation. The stable catalytic activity of the Ag/LaCoO₃ catalyst calcined at 700 °C in a NO_x atmosphere was related to its stable structure.