Assessment of limestone treatment with organic acids for CO sub(2) capture in Ca-looping cycles

• Published in: Fuel processing technology 2013-12, Vol.116, p.284-291
• Main Authors: Ridha, F N, Manovic, V, Macchi, A, Anthony, MA, Anthony, E J
• Format: Article
• Language: English
• ISSN: 0378-3820

The main challenge for CO sub(2) capture in calcium looping cycles is the decay of CO sub(2) carrying capacity of the CaO-based sorbents with increasing number of cycles. In this work, limestone was treated with organic acids and tested for CO sub(2) capture in calcium looping cycles to understand how practical and reliable the treatment is for CO sub(2) looping capture. The results showed that after 20 cycles the carbonation conversions of limestone treated with acetic acid, vinegar, formic acid, and oxalic acid were 33.1%, 21.1%, 31%, and 35.2%, respectively, compared to 18.9% for untreated limestone. The treatment with organic acids clearly improves the sintering-resistance properties of the modified sorbent. However, the activity of these sorbents was found to decline in similar fashion to that of untreated limestone. It was concluded that although limestone treatment with organic acids enhances CO sub(2) capture capacity, the enhancement is marginal in most cases while the treatment increases the cost of CO sub(2) capture significantly. Accordingly, the treatment may not be an adequate approach if the goal is to maintain low-cost capture of CO sub(2): moreover, treated sorbents which perform well for CO sub(2) capture do also perform well for SO sub(2) capture, causing their capacity to decline at least as rapidly as a natural untreated sorbent and often more so.