Carbonation Behavior of K2CO3 with Different Microstructure Used as an Active Component of Dry Sorbents for CO2 Capture

To choose the proper active component for potassium-based sorbents to capture CO 2, the carbonation behavior of some potassium carbonate from different sources was investigated with thermogravimetric analysis (TGA) and a fixed-bed reactor. The results show that the carbonation reaction process and the reaction rate of the samples are different, although their crystal structures and elemental compositions are the same. K 2 CO 3 calcined from KHCO 3 shows excellent carbonation capacity through producing the active species of K 4 H 2 (CO 3 ) 3 ·1.5H 2 O. The dimensionless weight increased to 1.36 in 27.7 min in TGA, corresponding to 80.2% conversion of the K 2 CO 3 to KHCO 3 . The amount of CO 2 capture reached 6.74 mol/(kg sorbent) within 23.3 min, corresponding to 93.0% conversion of the K 2 CO 3 to KHCO 3 . The reason is that the particle morphologies of those sorbents are different: the surface area and pore volume of K 2 CO 3 calcined from KHCO 3 are the highest, and the pore distribution range is wider than that of other samples. Therefore, it is better to load potassium carbonate onto a support with a large surface area and pore volume, to improve the CO 2 capture capacity.