Effect of crystal structure on CO2 capture characteristics of dry potassium-based sorbents

SEM and N2 adsorption tests show that the surface area is 3.0 m2 g−1 for K2CO3 with structure of monoclinic crystal (PC#1) while that of K2CO3 with structure of hexagonal crystal (PC#2) is 0.95 m2 g−1, and the pore volume of PC#1 and PC#2 are 8.0 × 10−3 and 2.8 × 10−3 cm3 g−1, respectively. Their pore size distribution curves show almost the same trends. Compared with PC#2, the particle morphology of PC#1 is better for the carbonation reaction. However, the carbonation reaction activity of PC#2 is better than that of PC#1. In order to find out the reason, the crystal structure characteristics of these sorbents are investigated with XRD and Inorganic Crystal Structure Database searching. It is shown that the difference in crystal structure causes the difference of carbonation reactivity between PC#1 and PC#2. The present work provides basic data for the technology of CO2 capture from flue gas using dry potassium-based sorbents.