Guo Jundong, Gan Fengli, Zhao Yifan, He Jinglin, Wang Bangda, Gao Tao, Jiang Xia, Ma Shenggui
College of Architecture and Environment, Sichuan University Chengdu 610065 China
College of Carbon Neutrality Future Technology, Sichuan University Chengdu 610065 China.
RSC Adv. 2023 Jan 27;13(6):4032-4039. doi: 10.1039/d2ra06744g. eCollection 2023 Jan 24.
The detailed atomic-level mechanism of the effect induced by engineering the crystal facet of α-MnO catalysts on NO formation during ammonia-selective catalytic reduction (NH-SCR) was ascertained by combining density functional theory (DFT) calculations and thermodynamics/kinetic analysis. The surface energies of α-MnO with specific (100), (110), and (310) exposed planes were calculated, and the adsorptions of NH, NO, and O on three surfaces were analyzed. The adsorption energies showed that NH and NO molecules could be strongly adsorbed on the surface of the α-MnO catalyst, while the adsorption of O was weak. Moreover, the key steps in the oxidative dehydrogenation of NH and the formation of NHNO as well as dissociation of NH were studied to evaluate the catalytic ability of NH-SCR reaction and N selectivity. The results revealed that the α-MnO catalyst exposed with the (310) plane exhibited the best NH-SCR catalytic performance and highest N selectivity, mainly due to its low energy barriers in NH dehydrogenation and NHNO generation, and difficulty in NH dissociation. This study deepens the comprehension of the facet-engineering of α-MnO on inhibiting NO formation during the NH-SCR, and points out a strategy to improve their catalytic ability and N selectivity for the low-temperature NH-SCR process.
通过结合密度泛函理论（DFT）计算以及热力学/动力学分析，确定了在氨选择性催化还原（NH-SCR）过程中，α-MnO催化剂晶面工程对NO生成影响的详细原子水平机制。计算了具有特定（100）、（110）和（310）暴露面的α-MnO的表面能，并分析了NH、NO和O在这三个表面上的吸附情况。吸附能表明，NH和NO分子可强烈吸附在α-MnO催化剂表面，而O的吸附较弱。此外，研究了NH氧化脱氢、NHNO形成以及NH解离的关键步骤，以评估NH-SCR反应的催化能力和N选择性。结果表明，暴露（310）面的α-MnO催化剂表现出最佳的NH-SCR催化性能和最高的N选择性，这主要归因于其在NH脱氢和NHNO生成过程中的低能垒以及NH解离的困难。本研究加深了对α-MnO晶面工程在NH-SCR过程中抑制NO生成的理解，并指出了一种提高其在低温NH-SCR过程中催化能力和N选择性的策略。
