A molten carbonate shell modified perovskite redox catalyst for anaerobic oxidative dehydrogenation of ethane
A molten carbonate shell modified perovskite redox catalyst for anaerobic oxidative dehydrogenation of ethane
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DOI：
10.1126/sciadv.aaz9339
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发表时间：
2020-04-01
期刊：
影响因子：
13.6
通讯作者：
Li, Fanxing
中科院分区：
文献类型：
--
作者：
Gao, Yunfei;Wang, Xijun;Li, Fanxing
受体掺杂的氧化还原活性钙钛矿氧化物如La0.8Sr0.2FeO3 （LSF）对乙烷氧化成CO X具有活性，但对乙烯的选择性较差。本文报道了熔融Li2CO3作为一种有效的“促进剂”来修饰乙烷化学环氧化脱氢（CL-ODH）的LSF。在工作状态下，氧化还原催化剂由覆盖在固体LSF衬底上的熔融Li2CO3层组成。熔融层促进了LSF上形成的活性过氧化物（O-2(2-)）的运输，同时阻断了非选择性位点。光谱测量和密度泛函理论计算表明，Fe4+ -> Fe3+跃迁是过氧化物形成的原因，导致了放热ODH和空气再氧化步骤。该催化剂具有90%的乙烯选择性，高达59%的乙烯收率和良好的反应热，具有很好的乙烷强化转化潜力。机理研究结果也为设计CL-ODH氧化还原催化剂提供了一种通用的方法。
Acceptor-doped, redox-active perovskite oxides such as La0.8Sr0.2FeO3 (LSF) are active for ethane oxidation to CO X but show poor selectivity to ethylene. This article reports molten Li2CO3 as an effective "promoter" to modify LSF for chemical looping-oxidative dehydrogenation (CL-ODH) of ethane. Under the working state, the redox catalyst is composed of a molten Li2CO3 layer covering the solid LSF substrate. The molten layer facilitates the transport of active peroxide (O-2(2-)) species formed on LSF while blocking the nonselective sites. Spectroscopy measurements and density functional theory calculations indicate that Fe4+ -> Fe3+ transition is responsible for the peroxide formation, which results in both exothermic ODH and air reoxidation steps. With >90% ethylene selectivity, up to 59% ethylene yield, and favorable heat of reactions, the core-shell redox catalyst has an excellent potential to be effective for intensified ethane conversion. The mechanistic findings also provide a generalized approach for designing CL-ODH redox catalysts.