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.

Pressure swing adsorption (PSA) and temperature swing adsorption (TSA) are potential techniques for removing carbon dioxide (CO 2 ) from high-pressure fuel gas streams. Zeolites are suitable candidate sorbents for use in these processes; however, the systems would be even more energy efficient if the sorbents were operational at moderate or high temperatures, especially for the removal of CO 2 from high-pressure gas streams, such as those from integrated gasification combined-cycle (IGCC) systems. Competitive gas adsorption tests with gas mixtures representing both coal combustion and coal gasification gas streams were conducted in an atmospheric flow reactor with five zeolites at 120 °C. Promising results of preferential adsorption of CO 2 were observed with two of these zeolites. However, the CO 2 adsorption capacity was significantly lower at 120 °C than at ambient temperature. Volumetric gas adsorption tests of CO 2 and nitrogen (N 2 ) on these two zeolites were conducted at 120 °C, up to a pressure of 300 psi (2 × 10 6 Pa). Both showed high CO 2 adsorption capacity at high pressure. High-pressure flow reactor studies also indicated the preferential adsorption of CO 2 from gas mixtures at 120 °C. CO 2 adsorption rates were measured utilizing thermogravimetric analysis, and the rates were similar for the two 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 °C up to a pressure of 300 psi (2 × 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 °C.

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