Adsorption of CO₂ on Molecular Sieves and Activated Carbon

Abstract

Pressure swing adsorption (PSA) and temperature swing adsorption (TSA) are some of the potential techniques that could be applicable for removal of CO 2 from high-pressure fuel gas streams. Molecular sieves and activated carbons are some of the sorbents that could be utilized in the PSA process. Volumetric adsorption studies of CO 2, N 2, or H 2 on molecular sieve 13X, molecular sieve 4A, and activated carbon were conducted at 25 °C up to a pressure of 300 psi (∼2× 106 Pa). Preferential adsorption of CO 2 was observed with all three sorbents. The adsorption capacity of CO 2 for molecular sieve 13X was higher than that for molecular sieve 4A at all pressures up to 300 psi. At low pressures (<25 psi) the adsorption capacity for CO 2 of activated carbon was lower than that of molecular sieve 13X, but at higher pressures (>25 psi) activated carbon exhibited significantly higher CO 2 capacities than were found for molecular sieves. Competitive adsorption of CO 2 from gas mixtures also indicated that both molecular sieve 13X and activated carbon can be utilized for separation of CO 2 from gas mixtures.