A comparative study of carbon gasification with O-2 and CO2 by density functional theory calculations

Zhu, Z. H., Finnerty, J., Lu, G. Q. and Yang, R. T. (2002) A comparative study of carbon gasification with O-2 and CO2 by density functional theory calculations. Energy & Fuels, 16 6: 1359-1368. doi:10.1021/ef0200020


Author Zhu, Z. H.
Finnerty, J.
Lu, G. Q.
Yang, R. T.
Title A comparative study of carbon gasification with O-2 and CO2 by density functional theory calculations
Journal name Energy & Fuels   Check publisher's open access policy
ISSN 0887-0624
Publication date 2002
Sub-type Article (original research)
DOI 10.1021/ef0200020
Volume 16
Issue 6
Start page 1359
End page 1368
Total pages 10
Place of publication Washington
Publisher American Chemical Society
Collection year 2002
Language eng
Subject C1
250103 Colloid and Surface Chemistry
660199 Energy transformation not elsewhere classified
Abstract A comparative study of carbon gasification with O-2 and CO2 was conducted by using density functional theory calculations. It was found that the activation energy and the number of active sites in carbon gasification reactions are significantly affected by both the capacity and manner of gas chemisorption. O-2 has a strong adsorption capacity and the dissociative chemisorption of O-2 is thermodynamically favorable on either bare carbon surface or even isolated edge sites. As a result, a large number of semiquinone and o-quinone oxygen can be formed indicating a significant increase in the number of active sites. Moreover, the weaker o-quinone C-C bonds can also drive the reaction forward at (ca. 30%) lower activation energy. Epoxy oxygen forms under relatively high O-2 pressure, and it can only increase the number of active sites, not further reduce the activation energy. CO2 has a lower adsorption capacity. Dissociative chemisorption of CO2 can only occur on two consecutive edge sites and o-quinone oxygen formed from CO2 chemisorption is negligible, let alone epoxy oxygen. Therefore, CO2-carbon reaction needs (ca 30%) higher activation energy. Furthermore, the effective active sites are also reduced by the manner Of CO2 chemisorption. A combination of the higher activation energy and the fewer active sites leads to the much lower reaction rate Of CO2-carbon.
Keyword Energy & Fuels
Engineering, Chemical
Earth Catalyzed Gasification
Unified Mechanism
Basal-plane
Coal Chars
Oxygen
Graphite
Kinetics
Surface
Alkali
Microscopy
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
Australian Institute for Bioengineering and Nanotechnology Publications
 
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