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首页> 外文期刊>Materials Chemistry and Physics >Catalytic properties of stoichiometric and non-stoichiometric LaFeO_3 perovskite for total oxidation of methane
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Catalytic properties of stoichiometric and non-stoichiometric LaFeO_3 perovskite for total oxidation of methane

机译：化学计量和非化学计量的LaFeO_3钙钛矿对甲烷完全氧化的催化性能

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摘要

Perovskite LaFeO_3 and derived materials La_(1-ε)FeO_(3-1.5_ε) with ε = 0.1, 0.2, 0.3 have been prepared as polycrystalline powders by thermal low-temperature decomposition of'La and Fe nitrates, a method which ensures a high surface area. They have been used in catalytic methane combustion in the range 300-450℃, showing a 100% selectivity to carbon dioxide. The reaction is indeed characterised by two ranges with different dependence of the reaction rate on temperature, as shown by the Arrhenius plot, whose slope decreases markedly above about 375℃. Temperature programmed desorption experiments of oxygen allowed us to ascertain the presence of two surface oxygen species, whose desorption occurs, respectively before and after the above indicated temperature on this basis, we propose here an hypothesis on the way of working of the catalysts. The characterisation of the catalysts has been then completed by means of temperature programmed reduction, whose results contribute to strengthen the hypothesis that the catalyst reduction operated by methane involves a smaller number of lattice planes than reduction of hydrogen.
机译：钙钛矿型LaFeO_3及其衍生材料La_（1-ε）FeO_（3-1.5_ε）的ε= 0.1、0.2、0.3是通过硝酸镧和硝酸铁的热低温分解制备的多晶粉末，该方法可确保高表面积。它们已用于300-450℃的催化甲烷燃烧，显示出对二氧化碳的100％选择性。实际上，反应的特征是反应速率对温度的依赖性不同的两个范围，如阿伦尼乌斯图所示，其斜率在约375℃以上明显降低。氧气的程序升温脱附实验使我们能够确定两种表面氧的存在，在此基础上分别在上述温度之前和之后发生脱附，我们在此提出关于催化剂工作方式的假设。催化剂的表征随后已通过程序升温还原得以完成，其结果有助于加强这样的假设：甲烷进行的催化剂还原所涉及的晶格面数量少于氢的还原。

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