Anomalous steady-state and spatio-temporal features of methane oxidation on Pt/Pd/Al sub(2)O sub(3) monolith spanning lean and rich conditions

The steady-state and transient features of methane oxidation on a Pt/Pd/Al sub(2)O sub(3) washcoated monolith are reported for a wide range of temperatures and feed gas compositions. With increasing temperature the multiplicity, in the form of a clockwise hysteresis in the rich regime, expands over...

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Bibliographic Details
Published in:Applied catalysis. B, Environmental Environmental, 2015-04, Vol.165, p.68-78
Main Authors: Bugosh, Gregory S, Easterling, Vencon G, Rusakova, Irene A, Harold, Michael P
Format: Article
Language:English
Subjects:
Aluminum oxide
Catalysis
Conversion
Hysteresis
Mass spectrometry
Methane
Oxidation
Palladium
Platinum
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Summary:The steady-state and transient features of methane oxidation on a Pt/Pd/Al sub(2)O sub(3) washcoated monolith are reported for a wide range of temperatures and feed gas compositions. With increasing temperature the multiplicity, in the form of a clockwise hysteresis in the rich regime, expands over a broader O sub(2) concentration range. Spatially resolved capillary-inlet mass spectrometry (SpaciMS) measurements reveal two primary zones within the monolith. The low conversion branch is attributed to inhibition by O sub(2) adsorption occupying the metallic catalyst sites, although the state is unstable in the lean regime as the more active PdO phase forms. The multiple high conversion state branches in the rich regime and the associated slow transient approach to a single stable high conversion branch are attributed to the supply of oxygen from the underlying bulk of PdO which favors methane partial oxidation.
ISSN:0926-3373
DOI:10.1016/j.apcatb.2014.09.058