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

摘要

To investigate active-component-distribution and carbonation behaviors, potassium-based sorbents were prepared by impregnation of K2CO3, K2CO3 · 1.5H2O, and KHCO3 on supports such as activated carbon (AC) and Al2O3. The CO2 capture capacity is significantly increased for K2CO3 and K2CO3 dehydrated from K2CO3 · 1.5H2O after they have been loaded on AC and Al2O3. For the sorbents with AC as their support, the active components keep their original phase in the impregnation process. Under an atmosphere of CO2 and H2O, the hydration reaction occurs first, and then KHCO3 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 Al2O3 as their support, all of the active components change into K2CO3 during the impregnation process. Under the same reaction atmosphere, K2CO3· 1.5H2O is not produced. H2O is adsorbed at first, and then CO2 reacts with the adsorbed H2O and K2CO3 to produce KHCO3. 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 Al2O3 in the form of many small aggregates.