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Title: Carbon Monoxide Adsorption on Manganese Oxide/Cobalt: an Ambient Pressure X-ray Photoelectron Spectroscopy Study

Journal Article · · Journal of Physical Chemistry. C

MnOx enhances the catalytic activity of Co during Fischer–Tropsch synthesis, increases selectivity toward C5+ products, and decreases methane formation. These desired traits are thought to result from a higher CO adsorption energy and, thus, potentially higher CO coverage. To investigate this, ambient pressure X-ray photoelectron spectroscopy (APXPS) was used to probe the CO coverage of Co foil with increasing MnOx amounts at room temperature. The technique permits the quantification of chemical species on a surface from ultrahigh vacuum to the mbar pressure regime. CO was found to adsorb at both Co and MnOx sites. The electronic effect which results in the promotion of CO adsorption also promotes the adsorption of OH groups from background water vapor pressures. This process competes with CO adsorption, despite the water pressure being ~8 orders of magnitude lower than the CO pressure at 1 mbar. Because water is a product of Fischer–Tropsch synthesis, this result has relevance to the understanding of MnOx as a promoter. This finding highlights the importance of considering unexpected contributions of background impurities in APXPS and other ambient pressure surface science techniques.

Research Organization:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Grant/Contract Number:
SC0012704
OSTI ID:
1595692
Report Number(s):
BNL--213578-2020-JAAM
Journal Information:
Journal of Physical Chemistry. C, Journal Name: Journal of Physical Chemistry. C Journal Issue: 6 Vol. 124; ISSN 1932-7447
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English

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