An in-situ IR study on the adsorption of CO2 and H2O on hydrotalcites. (March 2018)

• Record Type: Journal Article
• Authors: Coenen, Kai; Gallucci, Fausto; Mezari, Brahim; Hensen, Emiel; van Sint Annaland, Martin
• Is Part Of: Journal of CO₂ utilization. Volume 24(2018)
• Page Start: 228
• Page End: 239
• Publication Date: 2018-03
• Subjects: In-situ IR -- Hydrotalcite -- CO2 Capture -- Bidentate carbonate; Carbon dioxide -- Periodicals; Carbon dioxide -- Environmental aspects -- Periodicals; Carbon dioxide mitigation -- Periodicals; Carbon dioxide; Carbon dioxide -- Environmental aspects; Carbon dioxide mitigation; Periodicals; 628.53205
• DOI: 10.1016/j.jcou.2018.01.008
• Languages: English
• ISSNs: 2212-9820

Abstract

Graphical abstract: In-situ IR was used to study the sorption of CO2 and H2 O on a hydrotalcite based adsorbent at elevated temperatures between 300 and 500 °C to indentify different carbonate species involved in the adsorption mechanism. Highlights: In-situ IR revealed bidentate carbonate formed at the sorbent surface during exposure to CO2 . Adsorption sites with basic strength are present on the surface of the sorbent. H2 O leads to the decomposition of stronger bond bidentate carbonate. Abstract: In-situ IR technique was used to study the reversible adsorption of CO2 and H2 O at elevated temperatures on a potassium-promoted hydrotalcite for its use in sorption-enhanced water-gas shift (SEWGS). It was found that mainly bidentate carbonate species are responsible for the reversible (cyclic) adsorption capacity of the sorbent. The presence of H2 O can enhance the decomposition of bidentate carbonates bond to the stronger basic surface-sites. The basic strength of the involved adsorption sites for bidentate formation appears to be highly heterogeneous. At higher operating temperatures, reversible formation of bulk carbonates seem to participate in the reversible adsorption for CO2 . The presence of H2 O on the sorbent can lead to the formation of bi-carbonate, especially at lower operating temperatures of 300 °C. The transient absorbance of the main absorption bands for carbonate species identified during this study can be used in the development of a detailed description of the reversible adsorption/desorption kinetics reported before using thermogravimetric analyses.