Abstract
In-situ IR technique was used to study the reversible adsorption of CO2 and H2O 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 H2O 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 H2O 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.
Highlights
Hydrotalcites and hydrotalcite-based materials are widely used in several base-catalyzed reactions such as self-condensation and the cross-adol condensation of aldehydes and ketones owing to their basic properties [1]
In-situ IR technique was used to study the reversible adsorption of CO2 and H2O at elevated temperatures on a potassium-promoted hydrotalcite for its use in sorption-enhanced water-gas shift (SEWGS)
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
Summary
Hydrotalcites and hydrotalcite-based materials are widely used in several base-catalyzed reactions such as self-condensation and the cross-adol condensation of aldehydes and ketones owing to their basic properties [1]. Hydrotalcite-based materials can adsorb large quantities of CO2 in a wide range of temperatures and pressures [2]. Potassium promoted hydrotalcite has been investigated as a potential catalytic adsorbent in the sorption-enhanced water-gas shift (SEWGS) reaction. In SEWGS, CO2 adsorption to a solid material shifts the equilibrium of the water-gas shift (WGS) reaction, so that a high concentration of hydrogen can be obtained. Mechanical stability issues have been reported for Mg-rich potassium-promoted hydrotalcites due to the formation of MgCO3 at high partial pressures of CO2 and H2O [7,8,9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
