Influence of the concentration of CO 2 and SO 2 on the absorption of CO 2 by a lithium orthosilicate-based absorbent

R. Pacciani, J. Torres, P. Solsona, C. Coe, R. Quinn, J. Hufton, T. Golden, L. F. Vega

Research output: Contribution to journalArticlepeer-review

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Abstract

A novel, high temperature solid absorbent based on lithium orthosilicate (Li 4SiO 4) has shown promise for postcombustion CO 2 capture. Previous studies utilizing a clean, synthetic flue gas have shown that the absorbent has a high CO 2 capacity, >25 wt %, along with high absorption rates, lower heat of absorption and lower regeneration temperature than other solids such as calcium oxide. The current effort was aimed at evaluating the Li 4SiO 4 based absorbent in the presence of contaminants found in typical flue gas, specifically SO 2, by cyclic exposure to gas mixtures containing CO 2, H 2O (up to 25 vol. %), and SO 2 (up to 0.95 vol. %). In the absence of SO 2, a stable CO 2 capacity of ∼25 wt % over 25 cycles at 550 °C was achieved. The presence of SO 2, even at concentrations as low as 0.002 vol. %, resulted in an irreversible reaction with the absorbent and a decrease in CO 2 capacity. Analysis of SO 2-exposed samples revealed that the absorbent reacted chemically and irreversibly with SO 2 at 550 °C forming Li 2SO 4. Thus, industrial application would require desulfurization of flue gas prior to contacting the absorbent. Reactivity with SO 2 is not unique to the lithium orthosilicate material, so similar steps would be required for other absorbents that chemically react with SO 2.

Original languageBritish English
Pages (from-to)7083-7088
Number of pages6
JournalEnvironmental Science and Technology
Volume45
Issue number16
DOIs
StatePublished - 15 Aug 2011

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