Improvement of CO2 capture performance of calcium-based absorbent modified with palygorskite

Limestone can be used for CO2 capture and sequestration (CCS) in flue gas effectively. However, its CCS capability will dramatically decline after several cycles due to the surface “sintering”. In this work, the limestone was modified with palygorskite to reduce sintering phenomenon between the absorbent particles during the CCS process and the carbonation rate of the limestone can be enhanced effectively. Palygorskite is a natural mineral with nano-fibrous structure which can reduce the mutual contact of limestone particles during the CCS process. The results were detected by TGA, SEM, MIP, FTIR and particle size analyzer respectively. The best CO2 capture performance of modified absorbent was 13.11% improvement with only 5 wt% palygorskite added during the CCS process after 15 cycles compared with natural absorbent. It was found that excellent microscopic structures of absorbent modified with palygorskite was created, and the surface sintering was postponed leading to CO2 capture performance enhanced under the same conditions.