A comparative study of CO2 diffusion from adsorption kinetic measurements on microporous materials at low pressures and temperatures

GARCÉS-POLO, S.I.; VILLARROEL-ROCHA, J.; SAPAG, K.; KORILI, S.A.; GIL, A.

CHEMICAL ENGINEERING JOURNAL

ELSEVIER SCIENCE SA

Año: 2016 vol. 302 p. 278 - 286

1385-8947

The equilibrium adsorption and kinetics of CO2 on several microporous materials has been studied at 273, 283 and 293 K and gas pressures of up to 100 kPa. The porous materials used in this work were two zeolites (5A and 13X), two metal-organic frameworks (Basolite A100 and Basolite Z1200), an activated carbon and two pillared clays (Al-PILC and Zr-PILC). The isothermal and non-isothermal diffusion models were applied to calculate the diffusion time constants (D0/rc 2) from the uptake curves. The non-isothermal model was found to fit the experimental data well over the whole range of adsorption rates. The values found for the zeolites, which ranged from 0.020 to 0.043 s-1, were lower than those for the metal-organic frameworks and pillared clays, which ranged from 0.036 to 0.081 s-1, in the same interval of temperatures. Furthermore, the values of the diffusion time constants were found to depend on gas pressure. The pressure-dependence of the diffusion time constants was studied using the Darken equation. Finally, activation energy values were estimated from the temperature-dependence for all materials and it was found to increase in the order: Z1200 < Al-PILC < 13X < AC < Zr-PILC < 5A; A100.