Performance and Carbonation Kinetics of Modified CaO-Based Sorbents Derived from Different Precursors in Multiple CO 2 Capture Cycles

Calcium-based sorbent is a suitable sorbent for the solid looping CO 2 capture. The loss-in-capacity due to sintering, however, poses a big problem to the direct utilization of natural/pure CaO in the looping process. The issue of attrition, meanwhile, adds a further obstacle to the long-term cyclic utilization of the sorbent. Additionally, the performance of CaO-based sorbent in the long term solid looping CO 2 capture depends to a great degree on the type of precursor used to derive the sorbent. This study aims to systematically study the influence of the various calcium precursors on the sorbent performance in the long term carbonation-calcination cycles. Results of this study indicate that the absorption capacity of CaO sorbents was influenced significantly by the type of CaO precursor. It was found that CaO sorbent derived from calcium acetate gave the best absorption capacity of 0.61 mol-CO 2 /mol-sorbent after 48 carbonation/calcination cycles. The addition of inert supporting matrix of Al 2 O 3 has enhanced sintering resistance of the sorbents. The X-ray diffraction (XRD) results, supported with scanning electron microscopy (SEM) observations and N 2 adsorption/desorption analysis, suggest that the formation of mayenite (Ca 12 Al 14 O 33 ) helped to strengthen the framework of the sorbents, consequently improved sintering resistance and long-term cyclic stability of the modified sorbents. The incorporation of calcium aluminate cement decreased the attrition of sorbents, over the 48 cycles of carbonation and calcination, from 24.6% to 7.4%. Finally, in this study, carbonation kinetics of the sorbent was studied using a new, more precise three-stage carbonation kinetic model. The calculated results fitted to the experimental results very well.