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안광진

An, Kwangjin
Advanced Nanocatalysis Lab.
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Evidence of Highly Active Cobalt Oxide Catalyst for the Fischer−Tropsch Synthesis and CO2 Hydrogenation

Author(s)
Melaet, GeromeRalston, Walter T.Li, Cheng-ShiuanAlayoglu, SelimAn, KwangjinMusselwhite, NathanKalkan, BoraSomorjai, Gabor A.
Issued Date
2014-02
DOI
10.1021/ja412447q
URI
https://scholarworks.unist.ac.kr/handle/201301/12792
Fulltext
http://pubs.acs.org.library.unist.ac.kr:8010/doi/abs/10.1021/ja412447q
Citation
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, v.136, no.6, pp.2260 - 2263
Abstract
Hydrogenations of CO or CO2 are important catalytic reactions as they are interesting alternatives to produce fine chemical feedstock hence avoiding the use of fossil sources. Using monodisperse nanoparticle (NP) catalysts, we have studied the CO/H2 (i.e., Fischer-Tropsch synthesis) and CO2/H2 reactions. Exploiting synchrotron based in situ characterization techniques such as XANES and XPS, we were able to demonstrate that 10 nm Co NPs cannot be reduced at 250 C while supported on TiO2 or SiO2 and that the complete reduction of cobalt can only be achieved at 450 C. Interestingly, cobalt oxide performs better than fully reduced cobalt when supported on TiO2. In fact, the catalytic results indicate an enhancement of 10-fold for the CO2/H2 reaction rate and 2-fold for the CO/H2 reaction rate for the Co/TiO2 treated at 250 C in H2 versus Co/TiO2 treated at 450 C. Inversely, the activity of cobalt supported on SiO2 has a higher turnover frequency when cobalt is metallic. The product distributions could be tuned depending on the support and the oxidation state of cobalt. For oxidized cobalt on TiO2, we observed an increase of methane production for the CO2/H2 reaction whereas it is more selective to unsaturated products for the CO/H2 reaction. In situ investigation of the catalysts indicated wetting of the TiO2 support by CoOx and partial encapsulation of metallic Co by TiO 2-x. © 2014 American Chemical Society.
Publisher
AMER CHEMICAL SOC
ISSN
0002-7863

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