Adsorption equilibrium for sulfur dioxide, nitric oxide, carbon dioxide, nitrogen on 13X and 5A zeolites

For developing a single adsorption system to remove SO2, NO, and CO2 in flue gas simultaneously, the equilibrium adsorption behavior for main pollutants on candidate adsorbents were investigated and compared. The adsorption equilibrium isotherms for SO2, NO, CO2 and N-2 on 13X and 5A zeolites were obtained at varied temperatures by a static volume instrument respectively. Henry's law constant and selectivity were investigated to understand adsorbent and adsorbate affinity. In order to compare the shape differences among the isotherms, a new isotherm shape parameter was constructed and morphogenesis for isotherms was also discussed. Finally, thermodynamic functions integral Gibbs' free energy, enthalpy and entropy were calculated to characterize adsorption behavior. It was found that adsorption affinity follow the order SO2 > CO2 > NO > N-2 on both zeolites, Henry's law constant values of SO2, NO, CO2 are at least 118, 4, 11 times higher than that of N-2, respectively. The affinity effect likely attributes to the sum of adsorbate molecular multipole moments and polarizability. Isotherms of SO2 and NO exhibit higher degree of curvature and morphogenesis of their isotherms are probably decided by adsorbate-adsorbent interaction transition. Molecule CO2 exhibits the most efficient molecule packing on both zeolites, while SO2 takes the highest freedom in cavities. Better performance is found on 5A than 13X zeolite at adsorbing SO2, NO and CO2 through multi-component adsorption equilibrium simulation. Crown Copyright (c) 2012 Published by Elsevier B.V. All rights reserved.