Adsorption equilibrium of carbon dioxide, methane and nitrogen onto mordenite at high pressures

In this work, the adsorption equilibrium isotherms of carbon dioxide, methane and nitrogen on mordenite at three temperatures (279, 293 and 308 K) for pressures up to 2 MPa have been obtained. The experimental isotherms have been fitted with the Toth model. The selectivity order is: carbon dioxide >> methane > nitrogen. The sorbent capacity for methane and nitrogen is recovered with vacuum, making it adequate for a PSA separation, whereas this does not apply to carbon dioxide. The study of the carbon dioxide desorption with the TPD technique shows that it adsorbs onto two different sites, and the low desorption rate for one of them explain the low regeneration. A PSA cycle is proposed to increase the methane content of a methane/nitrogen mixture, using mordenite as the sorbent.