NOx storage and soot combustion over well-dispersed mesoporous mixed oxides via hydrotalcite-like precursors

• Main Authors: Wang, Zhongpeng, Lu, Peng, Zhang, Xiaomin, Wang, Liguo, Li, Qian, Zhang, Zhaoliang
• Format: Article
• Language: English
• ISSN: 2046-2069
• DOI: 10.1039/c5ra07414b

A series of mixed oxides with highly dispersed redox components were prepared via hydrotalcite-like precursors in which Mg was partly substituted with copper and cobalt, which were employed for NO x storage and soot combustion. The physico-chemical properties of the catalysts were characterized by XRD, TGA, IR, N 2 adsorption, H 2 -TPR and in situ FTIR techniques. The results show the transition metal cations have isomorphously replaced Mg 2+ in the layered structures forming a single hydrotalcite type phase. After calcination, the transition metal oxides exist in a highly dispersed form in the Mg(Al)O matrix and there is a cooperative effect between the copper and cobalt on the redox properties of the catalyst. The as-prepared oxide catalysts exhibit large surface areas, basic characters and improved redox properties, resulting in high performances in NO x storage and soot combustion. Both the NO x storage and desorption are catalytically accelerated due to the highly dispersed transition metal oxides. The presence of NO x positively affects the activity of all the oxides catalysts for soot combustion, which may be related to the production of NO 2 during NO oxidation. NO 2 -assisted mechanism and active oxygen mechanism may occur simultaneously in soot/NO/O 2 reaction. Partial substitution of Mg in hydrotalcite layers with transition metal ions leads to well-dispersed mesoporous mixed oxides exhibiting high performances on NO x storage and soot combustion.