Xiong Chao, Xue Can, Yu Xingrui, He Yaorong, Liang Yichao, Zhou Xiantai, Ji Hongbing
Fine Chemical Industry Research Institute, School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, PR China.
School of Chemical Engineering and Technology, Sun Yat-Sen University, Zhuhai 519082, PR China; Guangdong Provincial Key Laboratory of Optical Chemicals, XinHuaYue Group, Maoming 525000, PR China.
J Hazard Mater. 2023 Jan 5;441:129888. doi: 10.1016/j.jhazmat.2022.129888. Epub 2022 Sep 3.
Under the background of carbon dioxide emission reduction, how to realize the treatment and the high value-added conversion of typical olefin volatile organic compounds (olefin-VOCs), such as styrene, is a big challenge. In this contribution, the ceria-supported coinage metal catalysts (M/CeO, M = Au, Ag, and Cu) are successfully synthesized by a dry mechanochemical method, and their catalytic performance for styrene-VOC epoxidation with tert-butyl hydrogen peroxide (TBHP) as an oxidant to prepare high-value styrene oxide (SO) is investigated. The oxygen vacancies of ceria play a key role in the anchoring of metal nanoparticles. After ball milling, Au(III) is partially reduced and coexists on ceria in two valence states (Au and Au), and the reactive oxygen species of the as-prepared catalyst are enhanced. The catalytic behaviors, including solvents effect, substrate concentration, oxidant ratio, catalyst dosage, reaction time, and temperature, are systematically investigated. Au/CeO exhibits good styrene epoxidation performance with a total styrene conversion of 94% and a SO yield of 63%, along with good reusability and substrate scalability. Thermodynamics and kinetics show that Au/CeO was more favorable for styrene epoxidation and this reaction is dominated by the rate of intrinsic chemical reactions on the surface of the catalyst. Based on experimental discussions and a set of characterizations (XPS, XRD, in-situ FT-IR, ESR, ESI-HSMS, etc.), the mechanism is revealed as the synergistic catalysis between the reactive oxygen species of Au/CeO and the peroxide radicals generated by the homolysis of TBHP.
在二氧化碳减排的背景下，如何实现典型烯烃挥发性有机化合物（烯烃 - VOCs）如苯乙烯的处理及高附加值转化是一项巨大挑战。在本研究中，通过干式机械化学法成功合成了二氧化铈负载的贵金属催化剂（M/CeO，M = Au、Ag和Cu），并研究了它们以叔丁基过氧化氢（TBHP）为氧化剂催化苯乙烯 - VOC环氧化制备高附加值环氧苯乙烷（SO）的性能。二氧化铈的氧空位在金属纳米颗粒的锚定中起关键作用。球磨后，Au(III)部分被还原并以两种价态（Au⁰和Au³⁺）共存于二氧化铈上，所制备催化剂的活性氧物种得到增强。系统研究了包括溶剂效应、底物浓度、氧化剂比例、催化剂用量、反应时间和温度等催化行为。Au/CeO表现出良好的苯乙烯环氧化性能，苯乙烯总转化率为94%，SO产率为63%，同时具有良好的可重复使用性和底物扩展性。热力学和动力学表明，Au/CeO更有利于苯乙烯环氧化，且该反应受催化剂表面本征化学反应速率主导。基于实验讨论和一系列表征（XPS、XRD、原位FT - IR、ESR、ESI - HM S等），揭示了其机理为Au/CeO的活性氧物种与TBHP均裂产生的过氧自由基之间的协同催化作用。
