The preferential adsorption sites of H2O on adsorption sites of CO2 at low temperature onto NaX and BaX zeolites

Study of preferential adsorption sites of H2O on NaX and BaX zeolites was carried out after adsorption/desorption of carbon dioxide (CO2). The profiles of CO2 desorption revealed two distinct zones. The first one, at low temperature (T < 533 K), corresponding to physisorbed CO2 where BaX zeolite has an energy of adsorption higher than that of NaX as well as strong interactions of adsorbent/adsorbate. The second one (533-623 K) corresponds to the chem-isorbed CO2. The presence of water influences CO2 adsorption. The effect is more important for NaX than for BaX. For NaX, water occupies the adsorption sites of CO2 between 373 and 483 K. In contrast, BaX preserves a majority of adsorption sites of physisorbed CO2 in the presence of water, in particular the adsorption sites located in the interval of temperature 423-533 K.