Mechanistic Insight into Catalytic Combustion of Ethyl Acetate on Modified CeO 2 Nanobelts: Hydrolysis-Oxidation Process and Shielding Effect of Acetates/Alcoholates

• Published in: Environmental science & technology 2023-03, Vol.57 (9), p.3864-3874
• Main Authors: Shen, Zude, Gao, Erhao, Meng, Xinyu, Xu, Jiacheng, Sun, Yan, Zhu, Jiali, Li, Jing, Wu, Zuliang, Wang, Wei, Yao, Shuiliang, Dai, Qiguang
• Format: Article
• Language: English
• Subjects: Acetates - chemistry; Hydrolysis; Oxidation-Reduction; Oxygen
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.2c07991

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.