CO2 sorption on MgO and CaO surfaces: a comparative quantum chemical cluster study
Morten B Jensen1, Lars G M Pettersson, Ole Swang
1Center for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo, Norway.
The Journal of Physical Chemistry. B
|July 21, 2006
Summary
Carbon dioxide (CO2) adsorption on MgO and CaO surfaces was studied. Findings reveal CO2 binds differently on MgO and CaO, challenging previous assumptions and reinterpreting experimental data for CaO adsorption.
Area of Science:
- Surface science
- Computational chemistry
- Materials science
Background:
- Understanding CO2 adsorption on metal oxides is crucial for catalysis and carbon capture.
- Previous studies often assumed bidentate adsorption of CO2 on MgO.
- Experimental data for CO2 adsorption on CaO requires re-evaluation.
Purpose of the Study:
- To perform a comparative quantum chemical study of CO2 adsorption on MgO and CaO.
- To theoretically calculate infrared (IR) frequencies for adsorbed CO2.
- To compare theoretical results with existing experimental IR spectra.
Main Methods:
- Comparative quantum chemical calculations.
- Theoretical infrared (IR) frequency calculations.
- Comparison with literature IR experimental data.
Main Results:
- On MgO, CO2 adsorbs as monodentate on edge sites and bidentate on corner sites.
- On CaO, CO2 adsorbs as monodentate on both edge and corner sites, revising prior interpretations.
- Calculated frequencies for terrace (100) sites did not match experimental spectra.
Conclusions:
- The study challenges the common assumption of bidentate CO2 adsorption on MgO.
- Reinterprets CO2 adsorption on CaO as primarily monodentate.
- Suggests alternative assignments for experimental IR bands on terrace sites, possibly involving surface carbonate ions.
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