Performance comparison among three types of adsorbents in CO2 adsorption and recovery from wet flue gas

Abstract

Properties of adsorbent considerably influence their performance in CO2 adsorption and recovery from flue gas during vacuum swing adsorption (VSA). Hydrophilic adsorbents have a strong capability to separate CO2 from N2 in dry conditions, and hydrophobic adsorbents perform well in CO2 adsorption and recovery from wet flue gas. Water vapor in real flue gas streams significantly affects CO2 adsorption and recovery from wet flue gas. Hydrophilic adsorbents can be used for CO2 adsorption and recovery from wet flue gas after modification. The results of VSA with activated carbon bed and K2CO3/Al2O3 bed have been described in detail in previous research. This paper proposes a set of new adsorption equilibrium expressions (Sips–Gaussian model) of H2O/CO2/N2 on 13X and Al2O3 on the basis of a traditional adsorption isotherm model and previous research. Then, a series of calculations of VSA with double-layered Al2O3 + 13X bed is completed. The adsorption and desorption characteristics and performance of double-layered Al2O3 + 13X bed, activated carbon bed, K2CO3/Al2O3 bed in CO2 adsorption and recovery from wet flue gas are compared. Suggestions about the use of adsorbents in VSA for CO2 adsorption and recovery from wet flue gas are proposed.