摘要
本文基于密度泛函理论(DFT)与微观动力学模型,系统性研究了石墨烯量子点负载单原子Ni催化剂(Ni/G)上CO还原NO反应中的微观反应机理。结果表明Ni/G催化剂上CO还原NO反应的主要路径为:两个NO分子通过Langmuir-Hinshelwood机理吸附在Ni活性位后分解生成气态N_(2)O和表面吸附氧(O^(*)),随后气体N_(2)O吸附在Ni活性位并还原为N_(2)及O^(*),最终CO还原O^(*)生成CO_(2)并释放Ni活性位。能垒分析结果发现,NO分解生成N_(2)O及O^(*)具有较高的反应能垒,控制了NO还原的反应速率。微观动力学分析结果表明,升高反应温度可显著提升O^(*)的还原速率,但N_(2)O还原生成N_(2)的反应速率始终高于CO还原O^(*)的反应速率,导致Ni原子表面被O^(*)占据;残留的O^(*)抑制了NO的吸附与还原,引起Ni/G催化剂失活。
The microscopic reaction mechanism of NO reduction by CO on the graphene-supported single-atom Ni catalyst(Ni/G)was investigated by using density functional theory(DFT)and microkinetic modeling.The results indicate that as the most probably pathway for the NO reduction by CO over the Ni/G catalyst,two NO molecules adsorb onto the Ni atoms via the Langmuir-Hinshelwood mechanism and then transform to N_(2)O and active oxygen(O^(*)).Subsequently,N_(2)O is adsorbed on the Ni surface and reduced to N_(2) and O^(*).Finally,CO reduces O^(*)to form CO_(2),releasing the active Ni sites.From the energy barrier perspective,the transformation of NO to N_(2)O and O^(*)has a higher energy barrier,which controls the NO reduction reaction rate.From the microkinetic perspective,the reaction temperature has a significant effect on the rate of O^(*)reduction with CO,which is lower than that of N_(2)O reduction.As a result,the Ni atoms are gradually occupied by O^(*),which may inhibit the adsorption and reduction of NO,leading to the deactivation of the Ni/G catalyst.
作者
赵妍
李响
王焕然
朱亚明
李先春
ZHAO Yan;LI Xiang;WANG Huanran;ZHU Yaming;LI Xianchun(Liaoning School of Civil Engineering,University of Science and Technology,Anshan 114051,China;Liaoning School of Chemical Engineering,University of Science and Technology,Anshan 114051,China)
出处
《燃料化学学报(中英文)》
北大核心
2025年第7期1061-1071,共11页
Journal of Fuel Chemistry and Technology
基金
国家重点研发计划(2022YFE0208100)
辽宁科技大学研究生科技创新项目(LKDYC202424)资助。
