Catalytic combustion is an efficient and economical technique to deal with the air pollution of diluted volatile organic compounds (VOCs). In this work, oxygen-rich CeO₂-Nb₂O₅ mixed oxides (Ce_xNb_1-xO_4+δ) with varied Ce/Nb molar ratios in the bulk synthesized by modified sol–gel method were investigated for complete catalytic combustion of VOCs as exemplified by monochlorobenzene and toluene. To reveal the structure–function relationship of these materials, comprehensive catalytic performance evaluation and characterizations were performed, which showed that the 4Ce1Nb catalyst (CeO₂-Nb₂O₅ with Ce/Nb molar ratio of 4:1) displayed superb apparent catalytic activity. Complete oxidation could be accomplished below 300 °C, which was significantly lower than that of single-component CeO₂ or Nb₂O₅, as well as some other types of V and Cr based mixed oxide catalysts. Moreover, the apparent catalytic activity of 4Ce1Nb could be maintained for at least 100 h at 280 °C with high selectivity to the formation of HCl and CO₂. The improved catalytic performance of 4Ce1Nb could be ascribed to the formation of oxygen-rich Ce_xNb_1-xO_4+δ mixed oxides with high dispersion of Ce and Nb species into each other, the strong interaction of Ce–O-Nb, an abundance of active oxygen species, high specific surface area and mesoporous structure.

Graphic Abstract

中文翻译：

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Ce / Nb摩尔比对富氧Ce x Nb 1-x O 4 +δ材料在聚醚多元醇合成过程中催化燃烧VOC的影响

催化燃烧是一种有效且经济的技术，可应对稀释的挥发性有机化合物（VOC）的空气污染。在这项工作中，研究了通过改进的溶胶-凝胶法合成的本体中具有不同Ce / Nb摩尔比的富氧CeO ₂ -Nb ₂ O ₅混合氧化物（Ce _x Nb _1-x O _{4 +δ}） VOC的燃烧，例如一氯苯和甲苯。为了揭示这些材料的结构-功能关系，进行了全面的催化性能评估和表征，结果表明4Ce1Nb催化剂（CeO ₂ -Nb ₂ O ₅Ce / Nb摩尔比为4：1）表现出极好的表观催化活性。在300°C以下可以完成完全氧化，这明显低于单组分CeO ₂或Nb ₂ O ₅以及一些其他类型的V和Cr基混合氧化物催化剂。此外，4Ce1Nb的表观催化活性可以在280°C下保持至少100 h，并且对HCl和CO ₂的形成具有很高的选择性。4Ce1Nb催化性能的提高归因于富氧Ce _x Nb _1-x O _{4 +δ的形成} Ce和Nb物种之间具有高分散性的混合氧化物，Ce-O-Nb的强相互作用，大量活性氧，高比表面积和介孔结构。

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