Article pubs.acs.org/cm
Reversible CO2 Absorption by the 6H Perovskite Ba4Sb2O9 Matthew T. Dunstan,† Wen Liu,‡ Adriano F. Pavan,§ Justin A. Kimpton,∥ Chris D. Ling,§ Stuart A. Scott,⊥ John S. Dennis,‡ and Clare P. Grey*,† †
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, United Kingdom § School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia ∥ Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia ⊥ Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, United Kingdom ‡
S Supporting Information *
ABSTRACT: A novel compound for carbon capture and storage (CCS) applications, the 6H perovskite Ba4Sb2O9, was found to be able to absorb CO2 through a chemical reaction at 873 K to form barium carbonate and BaSb2O6. This absorption was shown to be reversible through the regeneration of the original Ba4Sb2O9 material upon heating above 1223 K accompanied by the release of CO2. A combined synchrotron X-ray diffraction, thermogravimetric, and microscopy study was carried out to characterize first the physical absorption properties and then to analyze the structural evolution and formation of phases in situ. Importantly, through subsequent carbonation and regeneration of the material over 100 times, it was shown that the combined absorption and regeneration reactions proceed without any significant reduction in the CO2 absorption capacity of the material. After 100 cycles the capacity of Ba4Sb2O9 was ∼0.1 g (CO2)/g (sorbent), representing 73% of the total molar capacity. This is the first report of a perovskite-type material showing such good properties, opening the way for studies of new classes of inorganic oxide materials with stable and flexible chemical compositions and structures for applications in carbon capture. KEYWORDS: carbon capture and storage, CO2 absorption, X-ray diffraction, thermogravimetric analysis, perovskite
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INTRODUCTION The combustion of fossil fuels, such as coal, to generate electricity contributes substantially to the total anthropogenic emission of carbon dioxide. To meet the projected demand for electricity, it is unlikely that this use of fossil fuels can be totally replaced by renewable sources of energy, such as wind, solar, or biomass, over the next two decades. Accordingly, because of the link between the concentration of CO2 in the atmosphere and climate change, means are needed to be able to continue using fossil fuels while capturing CO2 from the resulting flue gases and sequestering it in suitable geological structures. Such disposal is feasible only if the CO2 is almost pure and largely free of nitrogen and other gases. Among the various schemes to capture carbon from stationary sources of emission, postcombustion capture offers the greatest process flexibility, as a postcombustion capture unit can be retrofitted to existing facilities. The most mature technology for postcombustion capture, i.e., amine scrubbing, uses a liquid sorbent. This process occurs at relatively low temperatures (
