Abstract MnCeOx/TiO2 has been widely used in selective catalytic reduction (SCR) of NOx at low temperature. However, it is often poisoned in the presence of water vapor and sulfur dioxide. In this work, the promotion mechanism of Ba modification is investigated. Results show that the doped BaO reacts with CeO2 and forms the BaCeO3. This unique perovskite structure of BaCeO3 significantly enhances NO oxidation and NH3 activation of MnCeOx/TiO2 catalyst so that the NO conversion and the resistances to SO2 improve. It is found that Ba species obviously promote the NO adsorption ability and improve the redox properties of MnCeOx/TiO2 catalyst. While the acid properties of the catalyst are inhibited by Ba modification and among which Lewis acid sites are dominant for both MnCeOx/TiO2 and MnCe(Ba)Ox/TiO2 catalysts. Furthermore, in situ DRIFT experiments reveals that the NO reduction upon MnCeOx/TiO2 and MnCe(Ba)Ox/TiO2 catalysts follows both E-R and L-H mechanism, in which L-H is preferred. Ba species enhanced the formation of active nitrate species, which accelerates the NO reduction through L-H mechanism. It is interesting that although Ba species weakens the NH3 adsorption, it induces the ammonia conversion to coordination ammonia, which in turn accelerates the catalytic reaction.

中文翻译：

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MnCe(Ba)O/TiO2复合氧化物催化剂的新见解：钡添加剂加速氨转化

摘要 MnCeOx/TiO2 已广泛应用于NOx 的低温选择性催化还原(SCR)。然而，在水蒸气和二氧化硫存在的情况下，它往往会中毒。在这项工作中，研究了 Ba 修饰的促进机制。结果表明掺杂的 BaO 与 CeO2 反应并形成 BaCeO3。BaCeO3 这种独特的钙钛矿结构显着增强了 MnCeOx/TiO2 催化剂的 NO 氧化和 NH3 活化，从而提高了 NO 转化率和对 SO2 的抵抗力。发现Ba物种明显促进了NO吸附能力并改善了MnCeOx/TiO2催化剂的氧化还原性能。而催化剂的酸性性质受到 Ba 改性的抑制，其中路易斯酸位对于 MnCeOx/TiO2 和 MnCe(Ba)Ox/TiO2 催化剂来说都是主要的。此外，原位漂移实验表明，MnCeOx/TiO2 和 MnCe(Ba)Ox/TiO2 催化剂对 NO 的还原遵循 ER 和 LH 机制，其中 LH 是首选。Ba 物种增强了活性硝酸盐物种的形成，从而通过 LH 机制加速了 NO 还原。有趣的是，虽然 Ba 物种削弱了 NH3 的吸附，但它会诱导氨转化为配位氨，进而加速催化反应。