In-situ Studies of CO Oxidation on Pt(111): Evidence of a Self-Limiting Reaction at 140 K

Published

April 29, 2004

Author(s)

D J. Burnett, A M. Gabelnick, A T. Capitano, Daniel A. Fischer, J L. Gland

Abstract

In-situ oxidation experiments in oxygen pressures up to 1.3 Pa indicate that the 140 K carbon monoxide oxidation process is self-limiting. This experimental data suggests that adsorbed atomic oxygen may be responsible for limiting the extent of reaction between molecular oxygen and CO. Temperature Programmed Fluorescence Yield Near Edge Spectroscopy (TP-FYNES) and Temperature Programmed Reaction Spectroscopy (TPRS) were used to characterize this reaction over a wide range of reaction conditions. Previously published TPRS experiments with preadsorbed molecular oxygen and post exposures of carbon monoxide indicate that CO and O2 react at 140 K to form CO2. On the other hand, if the order of adsorption is reversed and CO is preadsorbed followed by post-exposures of O2, no 140 K CO2 is formed under TPRS conditions. We find that for oxygen pressures above 0.666 Pa the 140 K oxidation channel can be directly accessed even for this preadsorbed CO case. For both configurations, results indicate that only a small fraction of the CO reacts with molecular oxygen, suggesting that molecular oxygen needs to be adsorbed in close proximity to CO in order to react at 140 K. Unreacted atomic oxygen formed at this temperature appears to limit the extent of oxidation at 140 K even when the reaction progresses in flowing oxygen pressures up to 1.3 Pa.

Citation

Journal of Physical Chemistry

Volume

564

Pub Type

Journals

Keywords

carbon dioxide, intermediates, oxidation, plantinum, soft x-ray, surface science

Citation

Burnett, D. , Gabelnick, A. , Capitano, A. , Fischer, D. and Gland, J. (2004), In-situ Studies of CO Oxidation on Pt(111): Evidence of a Self-Limiting Reaction at 140 K, Journal of Physical Chemistry (Accessed April 23, 2024)