Multicyclic Study on the Simultaneous Carbonation and Sulfation of High-Reactivity CaO

Micron-sized CaO, obtained by calcination of mesoporous CaCO 3, attained 36 wt % CO 2 sorption capacity after 100 cycles of carbonation and calcination reactions at 700 °C. The extent of simultaneous carbonation ( X CO 2 ) and sulfation ( X SO 2 ) of CaO at 700 °C was obtained under simulated flue gas conditions (10% CO 2, 3000 ppm of SO 2, 4% O 2 in N 2 ). CaO reacts with SO 2 to form thermally stable CaSO 4, which leads to a reduction in the CO 2 capture capacity of CaO. Whereas X SO 2 increases monotonically with the residence time, X CO 2 goes through a maximum and eventually drops as a result of direct sulfation of CaCO 3 . The maximum value attained by X CO 2 was 50% in 10 min in the first cycle. The highest X CO 2 / X SO 2 ratio of 5 is attained at a residence time of 5 min. X SO 2 is higher under simultaneous carbonation and sulfation conditions compared to sulfation of CaO or direct sulfation of CaCO 3 .