La-Hexaaluminate Catalyst Preparation and Its Performance for Methane Catalytic Combustion

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• 作者：Cui Meisheng ; Wang Liangshi ; Zhao Na ; Long Zhiqi ; Li Dianqing ; Chen Aifan
• 关键词：La-hexaaluminate ; methane combustion ; cerium oxides ; rare earths
• 刊名：Journal of Rare Earths
• 出版年：2006
• 出版时间：December 2006
• 年：2006
• 卷：24
• 期：6
• 页码：690-694
• 全文大小：420 K

文摘

The La-hexaaluminate catalysts with high performance were synthesized by the modified controllable co-precipitation method with the buffer solution of NH₄HCO₃ and NH₄OH mixture as the precipitation agent. The physicochemical properties of catalysts were characterized by the means of BET, XRD, and TPR techniques. With methane catalytic combustion as the probe reaction, the catalytic performances were also tested on a fixed bed, continual flow system. The results show that it is a good method to obtain chemical homogeneous hexaaluminate materials by the buffer solution as the precipitation agent. The La-hexaaluminate can be formed at low temperatures ranging from 1050 to 1200 °C. The cerium introduction plays a great role in the methane catalytic combustion on La-Mn hexaaluminate because of its high oxygen storage capacity property and the well synergic effect between Ce and Mn. However, the CeO₂ appears in hexaaluminate through the XRD pattern, which reveals that Ce can not enter the crystal lattice position. Mn introduction improves the methane catalytic activity to a large extent due to its high redox property. When Mn atomic substitution amount for Al is 2, the hexaaluminate shows the highest activity, and the catalyst possesses good H₂ consumption and redox performance. Mn can easily occupy the hexaaluminate crystal position, which reveals that the Mn substitute La-hexaaluminate is a promising high temperature methane combustion catalyst with high activity and good stability.