揭示成对氧化还原-酸性位点对用于通过NH-SCR高效脱除NO的金属氧化物催化剂的影响。
Revealing the effect of paired redox-acid sites on metal oxide catalysts for efficient NO removal by NH-SCR.
作者信息
Tan Wei, Wang Chunying, Yu Shuohan, Li Yaobin, Xie Shaohua, Gao Fei, Dong Lin, Liu Fudong
机构信息
Department of Civil, Environmental, and Construction Engineering, Catalysis Cluster for Renewable Energy and Chemical Transformations (REACT), NanoScience Technology Center (NSTC), University of Central Florida, Orlando, FL 32816, United States; Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Jiangsu Key Laboratory of Vehicle Emissions Control, School of Environment, Center of Modern Analysis, Nanjing 210093, China.
Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
出版信息
J Hazard Mater. 2021 Aug 15;416:125826. doi: 10.1016/j.jhazmat.2021.125826. Epub 2021 Apr 24.
Understanding the nature of active sites on metal oxide catalysts in the selective catalytic reduction (SCR) of NO by NH (NH-SCR) is a crucial prerequisite for the development of novel efficient NH-SCR catalysts. In this work, two CeO-based SCR catalyst systems with diverse acidic metal oxides-CeO interfaces, i.e., NbO-CeO (NbO/CeO and CeO/NbO) and WO-CeO (WO/CeO and CeO/WO), were prepared and used to reveal the relationship between NH-SCR activity and surface acidity/redox properties. In combination with the results of the NH-SCR activity test and various characterizations, it was found that the NH-SCR performance of NbO-CeO and WO-CeO catalysts was highly dependent on the strong interactions between the redox component (CeO) and acidic component (NbO or WO), as well as the amount of paired redox-acid sites. From a quantitative perspective, an activity-surface acidity/redox property relationship was proposed. For both NbO-CeO and WO-CeO catalysts systems operated at the more concerned low-temperature range (200 °C), the NH-SCR activity in low NO conversion region (< 40%) was mainly dominated by the surface acidity of catalysts, while the NH-SCR activity in high NO conversion region (> 40%) was more determined by redox properties.
了解金属氧化物催化剂上的活性位点在氨选择性催化还原（NH-SCR）一氧化氮反应中的本质，是开发新型高效NH-SCR催化剂的关键前提。在本工作中，制备了两种具有不同酸性金属氧化物 - CeO界面的CeO基SCR催化剂体系，即NbO-CeO（NbO/CeO和CeO/NbO）和WO-CeO（WO/CeO和CeO/WO），并用于揭示NH-SCR活性与表面酸性/氧化还原性质之间的关系。结合NH-SCR活性测试结果和各种表征发现，NbO-CeO和WO-CeO催化剂的NH-SCR性能高度依赖于氧化还原组分（CeO）与酸性组分（NbO或WO）之间的强相互作用，以及成对的氧化还原 - 酸性位点的数量。从定量角度提出了活性 - 表面酸性/氧化还原性质关系。对于在更受关注的低温范围（200°C）下运行的NbO-CeO和WO-CeO催化剂体系，低NO转化率区域（<40%）的NH-SCR活性主要由催化剂的表面酸性主导，而高NO转化率区域（>40%）的NH-SCR活性则更多地由氧化还原性质决定。
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