Adsorption Kinetic Behaviour of Pure CO2, N2 and CH4 in Natural Clinoptilolite at Different Temperatures

Abstract

The adsorption kinetics of pure CO2, N2 and CH4 on a natural clinoptilolite (ZSL) sample from Villa de Reyes (San Luis Potosí, México) were measured at different temperatures using a glass, high-vacuum volumetric system. The ability of the natural zeolite to adsorb these gases depended on the gas–adsorbent contact time, t. For short values of t, the gas adsorption uptakes decreased in the order CO2 >> N2 > CH4. However, for long t values, the adsorption uptakes decreased in the sequence CO2 > CH4 > N2. It was established that the activation energies (kJ/mol) for the adsorption process increased in the following order CO2 (15) < N2 (18) < CH4 (40), correlating fairly well with the increasing order of kinetic diameter (Å) of the molecules: CO2 (3.3) < N2 (3.64) < CH4 (3.8). In comparison to the ZSL sample, the rate of adsorption of N2 and CH4 on H-ZSL increased and the total adsorption capacity decreased. The ZSL sample may be recommended as an effective adsorbent for the separation of CO2/CH4 and N2/CH4 mixtures.