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Appl. Sci. 2015, 5(3), 174-186; doi:10.3390/app5030174

In operando Detection of Three-Way Catalyst Aging by a Microwave-Based Method: Initial Studies

1
Bayreuth Engine Research Center (BERC), Zentrum für Energietechnik (ZET), Department of Functional Materials, University of Bayreuth, 95445 Bayreuth, Germany
2
Umicore AG & Co. KG, 63403 Hanau-Wolfgang, Germany
*
Authors to whom correspondence should be addressed.
Academic Editor: Takayoshi Kobayashi
Received: 4 June 2015 / Revised: 17 July 2015 / Accepted: 20 July 2015 / Published: 29 July 2015
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Abstract

Initial studies on aging detection of three way catalysts with a microwave cavity perturbation method were conducted. Two physico-chemical effects correlate with the aging state. At high temperatures, the resonance frequencies for oxidized catalysts (λ = 1.02) are not influenced by aging, but are significantly affected by aging in the reduced case (λ = 0.98). The catalyst aging state can therefore potentially be inferred from the resonance frequency differences between reduced and oxidized states or from the resonance frequency amplitudes during lambda oscillations. Secondly, adsorbed water at low temperatures strongly affects the resonance frequencies. Light-off experiment studies showed that the resonance frequency depends on the aging state at temperatures below the oxygen storage light-off. These differences were attributed to different water sorption capabilities of differently aged samples due to a surface area decrease with proceeding aging. In addition to the aging state, the water content in the feed gas and the temperature affect the amount of adsorbed water, leading to different integral electrical material properties of the catalyst and changing the resonance properties of the catalyst-filled canning. The classical aging-related properties of the catalyst (oxygen storage capacity, oxygen storage light-off, surface area), agreed very well with data obtained by the microwave-based method. View Full-Text
Keywords: three-way catalyst (TWC); on-board diagnosis (OBD); oxygen storage capacity (OSC); microwave cavity perturbation; lambda-probe three-way catalyst (TWC); on-board diagnosis (OBD); oxygen storage capacity (OSC); microwave cavity perturbation; lambda-probe
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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MDPI and ACS Style

Beulertz, G.; Votsmeier, M.; Moos, R. In operando Detection of Three-Way Catalyst Aging by a Microwave-Based Method: Initial Studies. Appl. Sci. 2015, 5, 174-186.

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