Shen Zude, Gao Erhao, Meng Xinyu, Xu Jiacheng, Sun Yan, Zhu Jiali, Li Jing, Wu Zuliang, Wang Wei, Yao Shuiliang, Dai Qiguang
School of Environmental Science and Engineering, Changzhou University, Changzhou 213164, Jiangsu, P. R. China.
Key Laboratory for Advanced Materials, Research Institute of Industrial Catalysis, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China.
Environ Sci Technol. 2023 Mar 7;57(9):3864-3874. doi: 10.1021/acs.est.2c07991. Epub 2023 Feb 22.
In this study, based on the comparison of two counterparts [Mn- and Cr-modified CeO nanobelts (NBs)] with the opposite effects, some novel mechanistic insights into the ethyl acetate (EA) catalytic combustion over CeO-based catalysts were proposed. The results demonstrated that EA catalytic combustion consisted of three primary processes: EA hydrolysis (C-O bond breakage), the oxidation of intermediate products, and the removal of surface acetates/alcoholates. Rapid EA hydrolysis typically occurs on surface acid/base sites or hydroxyl groups, and the removal of surface acetates/alcoholates resulting from EA hydrolysis is considered the rate-determining step. The deposited acetates/alcoholates like a shield covered the active sites (such as surface oxygen vacancies), and the enhanced mobility of the surface lattice oxygen as an oxidizing agent played a vital role in breaking through the shield and promoting the further hydrolysis-oxidation process. The Cr modification impeded the release of surface-activated lattice oxygen from the CeO NBs and induced the accumulation of acetates/alcoholates at a higher temperature due to the increased surface acidity/basicity. Conversely, the Mn-substituted CeO NBs with the higher lattice oxygen mobility effectively accelerated the in situ decomposition of acetates/alcoholates and facilitated the re-exposure of surface active sites. This study may contribute to a further mechanistic understanding into the catalytic oxidation of esters or other oxygenated volatile organic compounds over CeO-based catalysts.
在本研究中，基于对具有相反效应的两种对应物[Mn和Cr改性的CeO纳米带（NBs）]的比较，提出了一些关于乙酸乙酯（EA）在CeO基催化剂上催化燃烧的新颖机理见解。结果表明，EA催化燃烧包括三个主要过程：EA水解（C-O键断裂）、中间产物的氧化以及表面乙酸盐/醇盐的去除。快速的EA水解通常发生在表面酸/碱位点或羟基上，并且由EA水解导致的表面乙酸盐/醇盐的去除被认为是速率决定步骤。沉积的乙酸盐/醇盐就像一个盾牌覆盖了活性位点（如表面氧空位），而作为氧化剂的表面晶格氧的增强迁移率在突破盾牌并促进进一步的水解-氧化过程中起着至关重要的作用。Cr改性阻碍了CeO纳米带表面活性晶格氧的释放，并由于表面酸度/碱度的增加导致乙酸盐/醇盐在较高温度下积累。相反，具有较高晶格氧迁移率的Mn取代的CeO纳米带有效地加速了乙酸盐/醇盐的原位分解，并促进了表面活性位点的重新暴露。本研究可能有助于进一步从机理上理解CeO基催化剂上酯或其他含氧挥发性有机化合物的催化氧化。
