Oxygen selectivity of calcined Na-A type zeolite

Na-A type zeolite (Na-A) pellet showed a greater oxygen selectivity than Na-A powder (Izumi, J. and M. Suzuki, Adsorption, submitted; Izumi, J. et al., Japan Patent Toku-Kou-Shou 62-026808 (1987)). It was considered that a water adsorption at calcination stage influenced a window diameter shrinkage to increase the oxygen selectivity. For the confirmation of an optimum preparation condition for the oxygen selectivity enhancement of Na-A pellet, an experiment of oxygen and nitrogen adsorption on calcined Na-A was undertaken with a small adsorbent column under a pressure swing adsorption (PSA) condition at a temperature from 298 K to 213 K. It was found that the secondary calcination (953-1033 K) after the water vapor adsorption provided a remarkable increase of the oxygen selectivity. At the optimum condition for calcined Na-A, the oxygen separation factor is greater than 6. Calcined Na-A has a potential to separate oxygen and nitrogen from air by PSA effectively.