Adsorption separation of CO2 from N2 and CH4 has attracted an increasing interest recently. It is believed that the properties of adsorbents play the pivotal roles in determining the adsorption separation effectiveness. In our experiments, employing the molecular sieving mechanism, we have tailored the chabazite adsorbents to achieve a record-high selectivity of CO2 from N2 and CH4. For example, the CO2:CH4 and CO2:N2 selectivities on potassium chabazite are over 80 and 90, respectively, at 273 K and 1 atm. Our NMR and positron experiments and ab initio density functional theory (DFT) calculations reveal that the molecular sieving is activated by an adsorptive-induced cation-migration-concomitant mechanism, in which interaction of the gas molecules and cations plays a key role. This new understanding enables us to develop novel adsorbent materials and processes to separate gas molecules, which is a challenge by using other mechanism, e.g., molecule sieving based on molecular size.

Probing the controllable molecular sieving mechanism on chabazite for CO2/N2/CH4 separation

243rd National Meeting (2012)

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