CO2 capture using dry potassium-based sorbents in a bubbling fluidized-bed reactor

Abstract

A bubbling fluidized-bed reactor was used to study the CO2 capture characteristics of dry potassium-based sorbents. Potassium-based sorbents were prepared by impregnation with potassium carbonate on supports such as cocoanut activated charcoal (AC#1), coal active carbon (AC#2), activated alumina (Al2O3), silica gel (SG) and diatomite. Sorbents such as K2CO3/AC#1, K2CO3/AC#2, and K2CO3/Al2O3 showed excellent carbonation capacity, the conversion rates of those sorbents were 92.5%, 85.1%, and 88.2%, respectively. The regeneration rates of those sorbents were 87.1%, 83.9% and 86.7%, respectively. SEM and N2 adsorption tests showed that the surface area and pore volume of those sorbents were 669 m2 g-1, 390 m2 g-1, 139 m2/g, and 0.08 cm3/g, 0.17 cm3/g, 0.34 cm3/g, respectively. The particle morphologies of those sorbents are propitious to the carbonation reaction. However, K2CO3/diatomite and K 2CO3/SG showed poor carbonation capacity, the conversion conversions were only 2.0% and 1.9%, respectively. The surface area and pore volume of two sorbents were 1.1 m2/g, 39 m2/g and 0.004 cm3/g, 0.33 cm3/g, respectively. The carbonation capacity is affected by the particle morphology of those sorbents. The present work has provided data base for designing and operating a large scale CO2 capture process with two fluidized-bed reactors.