Control of the mechanism of chemical-looping of ethanol in non-stoichiometric ferrites by Cu-Mn substitution

• Published in: Catalysis today 2023-06, Vol.418, p.114105, Article 114105
• Main Authors: Vozniuk, Olena, Cacciaguerra, Thomas, Tanchoux, Nathalie, Albonetti, Stefania, Stievano, Lorenzo, Millet, Jean-Marc M., Bion, Nicolas, Di Renzo, Francesco, Cavani, Fabrizio
• Format: Article
• Language: English
• Subjects: Catalysis; Chemical Sciences; Environment and Society; Environmental Sciences; Hydrogen; Mössbauer; Redox; Renewable; Spinel
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2023.114105

Copper-manganese spinel ferrites have been evaluated as solid oxygen carriers for the production of hydrogen from water by ethanol-steam redox cycles. The materials were characterized by X-ray diffraction, Mössbauer spectroscopy, temperature-programmed reduction, oxygen isotope exchange and textural analysis. Surface reactions were followed by DRIFT spectroscopy. The amount and purity of hydrogen, produced in redox cycles at constant temperature of 450 °C, were highly affected by the nature of the oxygen carrier phases in the reduction step of the cycle. Cu-rich ferrites were reduced by ethanol to metallic copper and iron carbides, whereas Mn-rich ferrites were less deeply reduced to manganowustite. Ethanol was mainly oxidized by Cu-ferrites to CO and CO2, while mainly oxydehydrogenation products were formed on Mn-ferrites. In the reoxidation of the oxygen carrier by steam, the production of CO and CO2 by oxidation of carbides negatively affected the purity of the hydrogen formed. [Display omitted] •Transition-metal ferrites as oxygen carriers for hydrogen production from oxygenates.•The mechanism of reduction of ferrites is controlled by divalent components.•The production of low-carbon ethanol depends on the pathway of ethanol reforming.