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 sorbentswere 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/A1₂O₃ showed excellent carbonation capacity, the conversion rates of those sorbentswere 92.5%, 85.1%, and 88.2%, respectively. The regenerationrates 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 andK₂CO₃/SG showed poor carbonation capacity, the conversion conversionswere 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, 0.33 cm³/g, respectively. The carbonation capacity is affectedby 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.