Abstract The effect of oxygen vacancies on ceria catalyst for selective catalytic reduction with NH3 (NH3-SCR) of NO was investigated. The characterizations indicated that CeO2-Ar catalyst calcined in Ar atmosphere possessed more oxygen vacancies than CeO2 catalyst calcined in ambient air. XPS results showed that the surface oxygen contents of CeO2 and CeO2-Ar catalysts were 70.2 and 67.9% respectively, indicative of the loss of surface oxygen and existence of oxygen vacancies on CeO2-Ar catalyst. The H2-TPR and O2-TPO experiments suggested that the presence of abundant oxygen vacancies improved the redox behavior, providing CeO2-Ar catalyst a superior ability to oxygen uptake and release. Furthermore, the adsorption capacity for NH3 and NO of CeO2-Ar catalyst was enhanced by oxygen vacancies. As a result, CeO2-Ar catalyst showed a quite higher NO conversion (>90% above 260 °C) than CeO2 catalyst at 120 – 400 °C. The proposed mechanism suggested that the oxygen vacancies accelerated the acidity cycle and redox cycle during NH3-SCR reaction. Under the action of surface adsorbed oxygen on oxygen vacancies, the adsorption and activation of NH3 and NO were promoted and the restore of Ce4+ from Ce3+ was facilitated, which were responsible for the enhancement of catalytic performance of CeO2-Ar catalyst.

中文翻译：

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氧空位对二氧化铈催化剂NH3选择性催化还原NO的影响

摘要 研究了氧空位对二氧化铈催化剂NH3选择性催化还原NO(NH3-SCR)的影响。表征表明，在Ar气氛中煅烧的CeO2-Ar催化剂比在环境空气中煅烧的CeO2催化剂具有更多的氧空位。XPS 结果表明，CeO2 和 CeO2-Ar 催化剂的表面氧含量分别为 70.2% 和 67.9%，表明 CeO2-Ar 催化剂上存在表面氧损失和氧空位。H2-TPR 和 O2-TPO 实验表明，大量氧空位的存在改善了氧化还原行为，为 CeO2-Ar 催化剂提供了优越的氧吸收和释放能力。此外，氧空位增强了 CeO2-Ar 催化剂对 NH3 和 NO 的吸附能力。因此，CeO2-Ar 催化剂在 120 – 400 °C 时表现出比 CeO2 催化剂更高的 NO 转化率（260 °C 以上>90%）。所提出的机制表明氧空位加速了NH3-SCR反应过程中的酸度循环和氧化还原循环。在表面吸附氧对氧空位的作用下，促进了NH3和NO的吸附活化，促进了Ce3+还原Ce4+，提高了CeO2-Ar催化剂的催化性能。