Adsorption kinetics of CO₂, CO, N₂ and CH₄ on zeolite LiX pellet and activated carbon granule

The adsorption uptake curves of CO₂, CO, N₂ and CH₄ on zeolite LiX and activated carbon were measured using a volumetric method at 293, 308 and 323 K and pressure up to 100 kPa. The experimental uptake curves were correlated with a non-isothermal kinetic model because the adsorption kinetics was controlled by heat generation and transfer, and an isothermal model showed large deviation from experimental uptake. The adsorption rates of the gases on zeolite LiX and activated carbon were affected by the isosteric heat of adsorption, heat transfer rate and adsorption affinity. At the same pressure and temperature, the sequence of effective diffusion time constants was CO₂ ≪ CO < N₂ < CH₄ for zeolite LiX and CO₂ ≪ CH₄ ≤ N₂ < CO for activated carbon. The adsorption rate of CO showed the largest difference between the two adsorbents. Effective diffusion time constants (D/R²) for all cases were provided, which depended on pressure and temperature.