School of Energy and Environment, Anhui University of Technology, Ma Anshan 243002, PR China.
School of Energy and Environment, Anhui University of Technology, Ma Anshan 243002, PR China.
J Hazard Mater. 2021 Jun 15;412:125258. doi: 10.1016/j.jhazmat.2021.125258. Epub 2021 Jan 29.
Phosphomolybdic acid catalyst (PMoA/TiO) is a promising catalyst for selective catalytic reduction of NO with NH (NH-SCR) due to its strong acidity and excellent redox property. This work presents the NH-SCR reaction mechanism by In-situ diffuse reflectance Infrared Fourier Transform Spectroscopy (In-situ DRIFTs) and density functional theory (DFT). In-situ DRIFTs results indicated that the NH-SCR performance over PMoA/TiO followed both Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms. The reaction pathway, intermediate, transition state and energy barrier over PMoA to complete NH-SCR reaction were calculated by DFT. The results showed that the catalytic cycle includes foundational reaction (NH + NO reaction) and regenerative reaction (NH + NO reaction). NH, NHNO, HNNOH and HONNH species were the key intermediates. In the foundational reactions, NO played an important role in the removal of remaining H atoms. The NH dissociation on Lewis acid site, the internal hydrogen transfer on Brønsted acid site and the formation of HONNH species were the rate-controlling steps. The catalytic cycle of NH-SCR over PMoA consists of standard SCR and fast SCR.
磷钼酸催化剂（PMoA/TiO）由于其强酸性和优异的氧化还原性能，是一种很有前途的用于选择性催化还原 NO 的 NH（NH-SCR）的催化剂。本工作通过原位漫反射红外变换光谱（In-situ DRIFTs）和密度泛函理论（DFT）研究了 NH-SCR 反应机理。原位 DRIFTs 结果表明，PMoA/TiO 上的 NH-SCR 性能遵循 Eley-Rideal（E-R）和 Langmuir-Hinshelwood（L-H）两种机制。通过 DFT 计算了 PMoA 上完成 NH-SCR 反应的反应途径、中间体、过渡态和能垒。结果表明，催化循环包括基础反应（NH + NO 反应）和再生反应（NH + NO 反应）。NH、NHNO、HNNOH 和 HONNH 物种是关键中间体。在基础反应中，NO 在去除剩余的 H 原子中起重要作用。NH 在路易斯酸位上的离解、Brønsted 酸位上的内部氢转移和 HONNH 物种的形成是速率控制步骤。PMoA 上 NH-SCR 的催化循环包括标准 SCR 和快速 SCR。
