First principles study on the adsorption of CO2 and H 2O on the K2CO3 (001) surface

Hongwei Gao, Stephen Pishney, Michael J. Janik

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Potassium carbonate (K2CO3) is of interest as a CO2 absorbent. The molecular structure and properties of co-adsorption of CO2 and H2O on the K2CO 3 (001) surface were investigated by density functional theory (DFT) methods. The DFT surface energies of K2CO3 low index planes were determined, and the (001) surface has the lowest surface energy. The calculated adsorption energies and Gibb's free energies indicate that H 2O adsorbs much stronger than CO2, and their co-adsorption is repulsive on the K2CO3 (001) surface. The ab initio thermodynamics calculated coverage of CO2 under pre-combustion conditions is vanishingly small such that the net rate of bicarbonate formation is insignificant. This suggests that promoting bicarbonate formation requires a surface with stronger adsorption of CO2. This provides an indication that CO2 adsorption on the surface will be difficult in a wet stream, limiting the rate of conversion to the bicarbonate due to a low CO2 coverage. This is also in agreement with experimental results in the literature indicating that dry K2CO3 uptakes CO2 slowly, and that conversion to the bicarbonate proceeds initially through a hydrated structure.

Original languageEnglish (US)
Pages (from-to)140-146
Number of pages7
JournalSurface Science
Volume609
DOIs
StatePublished - Mar 1 2013

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carbonates
Bicarbonates
Adsorption
adsorption
Interfacial energy
surface energy
Density functional theory
density functional theory
Potash
molecular properties
absorbents
Molecular structure
Free energy
potassium
indication
molecular structure
free energy
potassium carbonate
Thermodynamics
thermodynamics

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

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abstract = "Potassium carbonate (K2CO3) is of interest as a CO2 absorbent. The molecular structure and properties of co-adsorption of CO2 and H2O on the K2CO 3 (001) surface were investigated by density functional theory (DFT) methods. The DFT surface energies of K2CO3 low index planes were determined, and the (001) surface has the lowest surface energy. The calculated adsorption energies and Gibb's free energies indicate that H 2O adsorbs much stronger than CO2, and their co-adsorption is repulsive on the K2CO3 (001) surface. The ab initio thermodynamics calculated coverage of CO2 under pre-combustion conditions is vanishingly small such that the net rate of bicarbonate formation is insignificant. This suggests that promoting bicarbonate formation requires a surface with stronger adsorption of CO2. This provides an indication that CO2 adsorption on the surface will be difficult in a wet stream, limiting the rate of conversion to the bicarbonate due to a low CO2 coverage. This is also in agreement with experimental results in the literature indicating that dry K2CO3 uptakes CO2 slowly, and that conversion to the bicarbonate proceeds initially through a hydrated structure.",
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First principles study on the adsorption of CO2 and H 2O on the K2CO3 (001) surface. / Gao, Hongwei; Pishney, Stephen; Janik, Michael J.

In: Surface Science, Vol. 609, 01.03.2013, p. 140-146.

Research output: Contribution to journalArticle

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AB - Potassium carbonate (K2CO3) is of interest as a CO2 absorbent. The molecular structure and properties of co-adsorption of CO2 and H2O on the K2CO 3 (001) surface were investigated by density functional theory (DFT) methods. The DFT surface energies of K2CO3 low index planes were determined, and the (001) surface has the lowest surface energy. The calculated adsorption energies and Gibb's free energies indicate that H 2O adsorbs much stronger than CO2, and their co-adsorption is repulsive on the K2CO3 (001) surface. The ab initio thermodynamics calculated coverage of CO2 under pre-combustion conditions is vanishingly small such that the net rate of bicarbonate formation is insignificant. This suggests that promoting bicarbonate formation requires a surface with stronger adsorption of CO2. This provides an indication that CO2 adsorption on the surface will be difficult in a wet stream, limiting the rate of conversion to the bicarbonate due to a low CO2 coverage. This is also in agreement with experimental results in the literature indicating that dry K2CO3 uptakes CO2 slowly, and that conversion to the bicarbonate proceeds initially through a hydrated structure.

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