Thermodynamic Properties of CO{sub 2} Capture Reaction by Solid Sorbents [electronic resource] : Theoretical Predictions and Experimental Validations

Published: Washington, D.C. : United States. Dept. of Energy, 2012.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Additional Creators: National Energy Technology Laboratory (U.S.), United States. Department of Energy, and United States. Department of Energy. Office of Scientific and Technical Information

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Summary

It is generally accepted that current technologies for capturing CO₂ are still too energy intensive. Hence, there is a critical need for development of new materials that can capture CO₂ reversibly with acceptable energy costs. Accordingly, solid sorbents have been proposed to be used for CO₂ capture applications through a reversible chemical transformation. By combining thermodynamic database mining with first principles density functional theory and phonon lattice dynamics calculations, a theoretical screening methodology to identify the most promising CO₂ sorbent candidates from the vast array of possible solid materials has been proposed and validated. The calculated thermodynamic properties of different classes of solid materials versus temperature and pressure changes were further used to evaluate the equilibrium properties for the CO₂ adsorption/desorption cycles. According to the requirements imposed by the pre- and post- combustion technologies and based on our calculated thermodynamic properties for the CO₂ capture reactions by the solids of interest, we were able to screen only those solid materials for which lower capture energy costs are expected at the desired pressure and temperature conditions. These CO₂ sorbent candidates were further considered for experimental validations. In this presentation, we first introduce our screening methodology with validating by solid dataset of alkali and alkaline metal oxides, hydroxides and bicarbonates which thermodynamic properties are available. Then, by studying a series of lithium silicates, we found that by increasing the Li₂O/SiO₂ ratio in the lithium silicates their corresponding turnover temperatures for CO₂ capture reactions can be increased. Compared to anhydrous K₂CO₃, the dehydrated K₂CO₃·1.5H₂O can only be applied for post-combustion CO₂ capture technology at temperatures lower than its phase transition (to anhydrous phase) temperature, which depends on the CO₂ pressure and the steam pressure with the best range being PH₂O≤1.0 bar. Above the phase-transition temperature, the sorbent will be regenerated into anhydrous K₂CO₃. Our theoretical investigations on Na-promoted MgO sorbents revealed that the sorption process takes place through formation of the Na₂Mg(CO₃)₂ double carbonate with better reaction kinetics over porous MgO, that of pure MgO sorbent. The experimental sorption tests also indicated that the Na-promoted MgO sorbent has high reactivity and capacity towards CO₂ sorption and can be easily regenerated either through pressure or temperature swing processes.

Report Numbers

E 1.99:netl-355
netl-355

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Published through SciTech Connect.
01/01/2012.
"netl-355"
2012 International Pittsburgh Coal Conference.
Li, Liyu; King, David; Duan, Yuhua; Luebke, David; Pennline, Henry; Xiao, Yunhan; Zhang; Keling; Zhao; Lifeng.

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