SO{sub 2} Retention by CaO-Based Sorbent Spent in CO{sub 2} Looping Cycles

• Published in: Industrial & engineering chemistry research 2009-07, Vol.48 (14)
• Main Authors: Manovic, V., Anthony, E.J., Loncarevic, D.
• Format: Article
• Language: English
• Subjects: 01 COAL, LIGNITE, AND PEAT; ADSORBENTS; CALCIUM OXIDES; CAPTURE; CARBON DIOXIDE; COMPARATIVE EVALUATIONS; DESULFURIZATION; LIMESTONE; PORE STRUCTURE; RETENTION; SULFATION; SULFUR DIOXIDE; WASTE PRODUCT UTILIZATION
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie9002365

CaO-based looping cycles are promising processes for CO{sub 2} Capture from both syngas and flue gas. The technology is based on cyclical carbonation of CaO and regeneration of CaCO{sub 3} in a dual fluidized-bed reactor to produce a pure CO{sub 2} stream suitable for sequestration. Use of spent sorbent from CO{sub 2} looping cycles for SO{sub 2} capture is investigated. Three limestones were investigated: Kelly Rock (Canada), La Blanca (Spain), and Katowice (Poland, Upper Silesia). Carbonation/calcination cycles were performed in a tube furnace with both the original limestones and samples thermally pretreated for different times (i.e., sintered). The spent sorbent samples were sulfated in a thermogravimetric analyzer (TGA). The changes in the resulting sorbent pore structure were then investigated using mercury porosimetry. It has been shown that the sulfation rates of both thermally pretreated and spent sorbent samples are lower in comparison with those of the original samples. However, final conversions of both spent and pretreated sorbents after longer sulfation time were comparable or higher than those observed for the original sorbents under comparable conditions. Maximum sulfation levels strongly depend on sorbent porosity and pore surface area. The results showed that spent sorbent samples from CO{sub 2} looping cycles can be used as sorbents for SO{sub 2} retention in cases where significant porosity loss does not occur during CO{sub 2} reaction cycles. In the case of spent Kelly Rock and Katowice samples, sorbent particles are practically uniformly sulfated, achieving final conversions that are determined by the total pore volume available for the bulky CaSO{sub 4} product.