Carbon dioxide–nitrogen separation through pressure swing adsorption

The reduction of carbon dioxide emissions from flue gases can be achieved using post-combustion capture technologies such as adsorption. In this paper, we report the continuous separation of a 15% mol/mol carbon dioxide–nitrogen mixture through the pressure swing adsorption (PSA) process. To this aim, zeolite 13X was used as the adsorbent in a fixed-bed column at different temperatures. The adsorption equilibrium of CO2 was described according to the Toth isotherm, while the N2 adsorption did not affect the CO2 adsorption. The overall performance of the process was assessed through the CO2 and N2 purity and also the recovery of carbon dioxide. A model based on the LDF approximation for the mass balance, including energy balance and momentum, was proposed, which is able to satisfactorily reproduce all of the experimental data.

• The active sites for N2 and CO2 adsorption are independent and consequently the presence of nitrogen in the mixture does not affect the CO2 adsorption.
• The separation N2/CO2 is controlled by the equilibrium.
• At low temperature, a superior CO2 purity is obtained due to the high CO2 adsorption capacity of zeolite 13X.
• The cooling of the exhaustion gas before CO2 separation is not necessary.