Carbonation and Active-Component-Distribution Behaviors of Several Potassium-Based Sorbents

To investigate active-component-distribution and carbonation behaviors, potassium-based sorbents were prepared by impregnation of K 2 CO 3, K 2 CO 3 ·1.5H 2 O, and KHCO 3 on supports such as activated carbon (AC) and Al 2 O 3 . The CO 2 capture capacity is significantly increased for K 2 CO 3 and K 2 CO 3 dehydrated from K 2 CO 3 ·1.5H 2 O after they have been loaded on AC and Al 2 O 3 . For the sorbents with AC as their support, the active components keep their original phase in the impregnation process. Under an atmosphere of CO 2 and H 2 O, the hydration reaction occurs first, and then KHCO 3 is produced rapidly. The active components are held in macropore spaces without blocking micropores, and the rest is nonuniformly distributed on the surface of AC in the form of large aggregates. For the sorbents with Al 2 O 3 as their support, all of the active components change into K 2 CO 3 during the impregnation process. Under the same reaction atmosphere, K 2 CO 3 ·1.5H 2 O is not produced. H 2 O is adsorbed at first, and then CO 2 reacts with the adsorbed H 2 O and K 2 CO 3 to produce KHCO 3 . Most of the active components are distributed in the mesopores and macropores of the support, and the rest is uniformly distributed on the surface of Al 2 O 3 in the form of many small aggregates.