Adsorption of CO2, N2, and O2 on natural zeolites

Pressure swing adsorption (PSA) and temperature swing adsorption are potential techniques for removing CO(2) from high-pressure fuel gas streams. Natural zeolites are suitable candidate sorbents for use in the PSA process. Studies of volumetric gas adsorption Of CO(2), N(2), and O(2) on three natural zeolites, with different major cations, were conducted at 25 degreesC up to a pressure of 300 psi (2 x 10(6) Pa). Preferential adsorption Of CO(2) was observed with all three zeolites. The natural zeolite with the highest sodium content and highest surface area showed the highest CO(2) adsorption capacity. Competitive gas adsorption studies also showed that the zeolite with the highest sodium content gave the best separation Of CO(2) from the gas mixtures. Contact time did not affect the extent of adsorption of the zeolites. Temperature-programmed desorption studies indicated that the majority of the physically adsorbed CO(2) was desorbed at room temperature, while some strongly bound CO(2) was desorbed at 115 degreesC.