Combined experimental and theoretical study of o-xylene elimination on Fe-Mn oxides catalysts
Combined experimental and theoretical study of o-xylene elimination on Fe-Mn oxides catalysts
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Fe-Mn氧化物催化剂脱除邻二甲苯的实验与理论联合研究
DOI：
10.1016/j.chemosphere.2021.133442
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发表时间：
2021
期刊：
影响因子：
8.8
通讯作者：
Jianrong Chen
中科院分区：
文献类型：
--
作者：
Ji Mei;Yao Shen;Yuanming Li;Shihan Zhang;Yi Shen;Wei Li;Zhuowei Cheng;Jingkai Zhao;Jianrong Chen
开发低成本、易获取的催化剂以实现挥发性有机化合物催化燃烧的实际应用仍然是一个挑战。本文采用易氧化还原-沉淀法制备了一系列Fe-Mn氧化物催化剂，用于去除邻二甲苯。在所合成的催化剂中，Fe3Mn1-RP的t50和t90分别为223°C和236°C（邻二甲苯浓度为500 ppm， WHSV = 36000 mL g−1h−1），表现出优异的邻二甲苯去除活性。表征结果表明，大的比表面积、良好的还原性和高的Mn4+比例可以获得优异的催化活性。此外，高铁含量证明有利于产生额外的氧空位，从而提高催化剂的性能。通过密度泛函理论（DFT）计算，确定了催化剂的稳定晶体结构和表面电子密度分布，以及邻二甲苯在催化剂表面的吸附位置，为邻二甲苯氧化的发生提供了深入的机制。此外，氧化过程的能垒分析证明，活化能低至2.46 eV的Fe3Mn1-RP表面的开环反应更可能通过氧空位发生。
The development of low-cost and easily accessible catalysts to realize the practical applications of catalytic combustion of volatile organic compounds remains a challenge. In this work, a series of Fe–Mn oxides catalysts were prepared via a facile redox-precipitation route for the elimination of o-xylene. Among the synthesized catalysts, Fe3Mn1-RP exhibited excellent activity for o-xylene elimination with a T50and T90of 223 °C and 236 °C, respectively (o-xylene concentration = 500 ppm, WHSV = 36,000 mL g−1h−1). Characterization results demonstrated that superior catalytic activity could be achieved from large specific surface area, good reducibility and high proportion of Mn4+. Besides, high Fe contents proved beneficial in generating additional oxygen vacancies, thereby improving the performance of the catalyst. The stable crystal structures and surface electron density distributions of the catalysts, and adsorption sites of o-xylene on the catalyst surface, were also determined through density functional theory (DFT) calculations to provide an in-depth mechanism on how the o-xylene oxidation occurred. Moreover, analysis of the energy barrier during the oxidation process proved that the ring-opening reaction on the surface of Fe3Mn1-RP with an activation energy as low as 2.46 eV would more likely occur via oxygen vacancies.