A mechanistic DFT study of low temperature SCR of NO with NH3 on MnCe1-xO2(111)
A mechanistic DFT study of low temperature SCR of NO with NH3 on MnCe1-xO2(111)
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MnCe1-xO2(111) 上 NH3 低温 SCR 机理 DFT 研究
DOI：
10.1039/c5cy01597a
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发表时间：
2016
影响因子：
5
通讯作者：
Hensen Emiel J. M.
中科院分区：
文献类型：
--
作者：
Song Weiyu;Liu Jian;Zheng Huiling;Ma Sicong;Wei Yuechang;Duan Aijun;Jiang Guiyuan;Zhao Zhen;Hensen Emiel J. M.
锰促进CeO2是一种很有前途的氨氮低温选择性催化还原NO的催化剂。我们通过量子化学DFT+U计算研究了将Mn阳离子掺杂到CeO2（111）表面的模型的反应机理。NH3优先吸附在Lewis酸Mn位点上。其中一个N-H键的解离产生了实验观察到的关键NH2中间体。NO吸附在NH2中间体上产生亚硝胺（NH2NO），然后亚硝胺可以进行进一步的N-H裂解反应形成OH基团。产生的N2O产物被解吸到气相中，并且可以通过其O原子在氧化铈表面的氧空位上重新吸附，这是由水解吸引起的。解吸水是最困难的初等反应步骤。这种氧化还原机制涉及掺杂Mn作为氨吸附的路易斯酸位点和氧化铈表面的O空位，将N2O分解成所需的N2产物。
Mn-promoted CeO2 is a promising catalyst for the low temperature selective catalytic reduction of NO by NH3. We investigated the mechanism of this reaction for a model in which Mn cations are doped into the CeO2(111) surface by quantum-chemical DFT+U calculations. NH3 is preferentially adsorbed on the Lewis acid Mn sites. Dissociation of one of its N–H bonds results in the key NH2 intermediate that has been experimentally observed. NO adsorption on this NH2 intermediate results in nitrosamine (NH2NO) that can then undergo further N–H cleavage reactions to form OH groups. The resulting N2O product is desorbed into the gas phase and can be re-adsorbed through its O atom on an oxygen vacancy in the ceria surface, resulting from water desorption. Water desorption is the most difficult elementary reaction step. This redox mechanism involves doped Mn as Lewis acid sites for ammonia adsorption and O vacancies in the ceria surface to decompose N2O into the desired N2 product.