Influence of the pressure and temperature on CO2 adsorption using zeolite

https://doi.org/10.1088/1468-6996/9/1/013007

“Several investigations carried out with diverse zeolites (LaM-10, H-ZSM-5, M-ZSM-5 (M = Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺), NaX or 13X, 5A, 4A, NaLSX, MCM-48, erionite, mordenite, clinoptilolite) have shown the effect of pressure and temperature on CO₂ adsorption [10–12, 14, 16, 18, 19, 37, 52, 63–67]. In general, the capacity of CO₂ adsorption on the zeolites enhances when the partial CO₂ pressure increases and decreases with a rise of temperature (table 3). The results obtained by Yucel and Ruthven [68] and Gardner et al [69] have also shown that the diffusion of CO₂ in the zeolite 4A and H-ZSM-5 enhances with the increase of the partial pressure. Moreover, the data obtained by Akten et al [52] have indicated that the Na-4A selectivity for the CO₂ in the presence of N₂ and H₂ decreases slightly when the pressure in the gas phase enhances. This decrease of selectivity is more marked when the molecules of other gas smaller than CO₂ are presents in the gas phase. The effect of the pressure on the CO₂ adsorption might be attributed to fact that the amounts of CO₂ adsorbed are directly proportional to the cationic density in the zeolites pores at low pressures, whereas the volume of pores plays an important role at high pressures [9, 44]. Katoh et al [19] have also attributed this effect of the pressure in the case of the zeolite Li-ZSM-5, to the existence of two types of cations sites species and to the possibility that a rise of the partial pressure might induce a penetration of CO₂ deep into the small channels of zeolite, this allowed to interact more strongly with the Li⁺ cations. In parallel, the decrease of the CO₂ adsorption with the increase of the temperature has been associated with a decrease of adsorbent-adsorbate interactions (site–adsorbate) induced by an increase of the mobility of adsorbed molecules into the zeolites cavities that might be caused by a rise of thermal agitation [34].”