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Kang, Running, Ma, Pandong, He, Junyao, Li, Huixin, Bin, Feng, Wei, Xiaolin, Dou, Baojuan, Hui, Kwun Nam and Hui, Kwan San 
ORCID: https://orcid.org/0000-0001-7089-7587
(2021)
Transient behavior and reaction mechanism of CO catalytic ignition over a CuO–CeO2 mixed oxide.
Proceedings of the Combustion Institute, 38 (4).
pp. 6493-6501.
ISSN 1540-7489
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Abstract
As a key heterogeneous process, the catalytic oxidation of CO is essential not only for practical applications such as automotive exhaust purification and fuel cells but also as a model reaction to study the reaction mechanism and structure-reactivity correlation of catalysts. In this study, the variation in activity-controlling factors during CO catalytic ignition over a CuO-CeO 2 catalyst was investigated. The activity for CO combustion follows the decreasing order of CuO-CeO 2 > CuO > CeO 2. Except for inactive CeO 2, increasing temperature induces CO ignition to achieve self-sustained combustion over CuO and CuO-CeO 2. However, CuO provides enough copper sites to adsorb CO, and abundant active lattice oxygen, thus obtaining a higher hot zone temperature (208.3 °C) than that of CuO-CeO 2 (197.3 °C). Catalytic ignition triggers a kinetic transition from the low-rate steady-state regime to a high-rate steady-state regime. During the induction process, Raman, X-ray photoelectron spectroscopy, CO temperature-programmed desorption and IR spectroscopy results indicated that CO is preferentially adsorbed on oxygen vacancies (Cu +-[Ov]-Ce 3+) to yield Cu +-[C≡O]-Ce 3+ complexes. Because of the self-poisoning of CO, the adsorbed CO and traces of adsorbed oxygen react at a relative rate, which is entirely governed by the kinetics on the CO-covered surface and the heat transport until the pre-ignition regime. The Cu +-[C≡O]-Ce 3+ complex is a major contributor to CO ignition. The step-response runs and kinetic models showed that after ignition, a kinetic phase transition occurs from a CO-covered surface to an active lattice oxygen-covered surface. During CO self-sustained combustion, the rapid gas diffusivity and mass transfer is beneficial for handling the low coverage of CO. The active lattice oxygen of CuO takes part in CO oxidation.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | carbon monoxide,catalytic ignition,copper-cerium oxide,reaction mechanism,transient behavior,chemical engineering(all),mechanical engineering,physical and theoretical chemistry ,/dk/atira/pure/subjectarea/asjc/1500 |
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| Depositing User: | LivePure Connector |
| Date Deposited: | 15 Sep 2020 23:55 |
| Last Modified: | 22 Oct 2022 07:02 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/76883 |
| DOI: | 10.1016/j.proci.2020.06.186 |
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