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 CO2 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 CO2, N2, or H2 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 CO2 was observed with all three sorbents. The adsorption capacity of CO2 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 CO2 of activated carbon was lower than that of molecular sieve 13X, but at higher pressures (>25 psi) activated carbon exhibited significantly higher CO2 capacities than were found for molecular sieves. Competitive adsorption of CO2 from gas mixtures also indicated that both molecular sieve 13X and activated carbon can be utilized for separation of CO2 from gas mixtures.