Nanocasted Synthesis of Mesoporous LaCoO3 Perovskite with Extremely High Surface Area and Excellent Activity in Methane Combustion

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• 作者：Yangang Wang ; Jiawen Ren ; Yanqin Wang ; Fengyuan Zhang ; Xiaohui Liu ; Yun Guo ; Guanzhong Lu
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：October 2, 2008
• 年：2008
• 卷：112
• 期：39
• 页码：15293-15298
• 全文大小：234K
• 年卷期：v.112,no.39(October 2, 2008)
• ISSN：1932-7455

文摘

Ordered mesoporous LaCoO₃ perovskite with high surface area was synthesized via nanocasting strategy by using ordered mesoporous cubic (Ia3d) vinyl silica as the template. The sample, prepared by filling mesopores in silica template with a La−Co citrate complex precursor followed by calcination and silica removal, was characterized by XRD, TEM, and nitrogen sorption techniques, and its catalytic activity was tested for complete methane oxidation. The wide-angle XRD pattern showed LaCoO₃ perovskite was formed and no La-oxide/Co-oxide phases were detected in the obtained material. This LaCoO₃ perovskite displayed a high BET surface area of 96.7 m² g⁻¹ from nitrogen sorption analysis and a three-dimensional ordered mesostructure from TEM images, as well as a small-angle XRD pattern. Moreover, this material showed much higher activity in the complete methane oxidation than the conventional bulk LaCoO₃ perovskite. The light-off temperature (T₁₀) and the half-conversion temperature (T₅₀) were at 335 and 470 °C, respectively. Further analysis by means of H₂-TPR and XPS techniques showed that the existence of high valent cobalt ions and high content of O₂²⁻/O⁻ species contributed to the high activity.