Alkali-metal enhanced LaMnO3 perovskite oxides for chemical looping oxidative dehydrogenation of ethane

NaW-modified LaMnO3 redox catalyst utilizing the lattice oxygen species to convert ethane into ethylene, exhibited a stable reactivity and better ethylene selectivity in chemical looping oxidative dehydrogenation of ethane. [Display omitted] •The CL-ODH utilize the lattice oxygen species to convert...

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Bibliographic Details
Published in:Applied catalysis. A, General General, 2021-01, Vol.609, p.117910, Article 117910
Main Authors: Ding, Weixiao, Zhao, Kun, Jiang, Shican, Zhao, Zengli, Cao, Yan, He, Fang
Format: Article
Language:English
Subjects:
Alkali promoter
Catalysts
Chemical looping
Dehydrogenation
Ethane
Ethylene
Intermediate oxygen
Lanthanum compounds
Manganese
ODH
Oxidation
Perovskites
Selectivity
Sodium phosphate
Valence
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Summary:NaW-modified LaMnO3 redox catalyst utilizing the lattice oxygen species to convert ethane into ethylene, exhibited a stable reactivity and better ethylene selectivity in chemical looping oxidative dehydrogenation of ethane. [Display omitted] •The CL-ODH utilize the lattice oxygen species to convert ethane into ethylene.•Alkali promoters suppress Mn4+ and induces electron-rich intermediate oxygen species.•Formation of Mn3+ is beneficial for the selective oxidation of ethane into ethylene.•Strong alkalinity aroused by alkalis metals contribute to higher ethylene selectivity. Chemical looping oxidative dehydrogenation (CL-ODH) of ethane provides a potential method to convert ethane into ethylene by using a circulative redox catalyst (also called oxygen carrier). In this work, perovskites type oxide LaMnO3 and three kinds of alkali-metal (Na, Na3PO4 and Na2WO4) promoted LaMnO3 redox catalysts were prepared and tested for CL-ODH of ethane. Results showed that the alkali promoters not only reduce the Mn oxidation state, but also decrease the surface manganese sites. The alkali-doping induces the formation of electron-rich intermediate oxygen species, which contributes to the higher ethylene selectivity of the alkali-modified LaMnO3. As the best candidate for CL-ODH of ethane among the four catalysts, NaW-LaMnO3 exhibited a stable activity during 25 redox cycles. 85 % of ethylene selectivity and 60 % of ethylene yield was obtained, which is significantly improved in comparison to 41.16 % ethylene yield of unpromoted LaMnO3, simultaneously exhibiting less than 1 % of coke formation.
ISSN:0926-860X
1873-3875
DOI:10.1016/j.apcata.2020.117910