Separation of CO2and CH4by Pressure Swing Adsorption Using a Molecular Trapdoor Chabazite Adsorbent for Natural Gas Purification

Abstract

Adsorption materials play a key role in determining the efficiency of the pressure swing adsorption process. The selectivity of CO2 over CH4 on most zeolite adsorbents drops dramatically with increasing pressure, and few adsorbents work for CO2/CH4 separation at high pressures. Here, we show that the high selectivity (81) can be retained with our "molecular trapdoor"adsorbent- A potassium exchanged chabazite with an Si/Al ratio of 1, which can selectively admit gas molecules by regulating its cation-kept eight-membered ring (8MR) doorways. Analysis of equilibrium adsorption of CO2 and CH4 showed an exceptionally high selectivity (81) of CO2 over CH4; when the temperature is lower than a thre..