A molten carbonate shell modified perovskite redox catalyst for anaerobic oxidative dehydrogenation of ethane.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 32426468.
- Also identified by DOI 10.1126/sciadv.aaz9339 and PMC identifier 7182410.
- Licence recorded as CC BY-NC.
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Abstract
Acceptor-doped, redox-active perovskite oxides such as La<sub>0.8</sub>Sr<sub>0.2</sub>FeO<sub>3</sub> (LSF) are active for ethane oxidation to CO <i><sub>x</sub></i> but show poor selectivity to ethylene. This article reports molten Li<sub>2</sub>CO<sub>3</sub> 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 Li<sub>2</sub>CO<sub>3</sub> layer covering the solid LSF substrate. The molten layer facilitates the transport of active peroxide (O<sub>2</sub> <sup>2-</sup>) species formed on LSF while blocking the nonselective sites. Spectroscopy measurements and density functional theory calculations indicate that Fe<sup>4+</sup>→Fe<sup>3+</sup> 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.