Adsorption dynamics of air on zeolite 13X and CMS beds for separation and purification

The adsorption dynamics of N-2, O-2, and Ar in kinetic separation bed with CMS and equilibrium separation bed with zeolite 13X were investigated by using dried air as a feed. In the CMS bed initially saturated with He, Ar was the first breakthrough component showing a small roll-up and N-2 followed at a very close interval. Then, the breakthrough Of O-2 occurred with a broad roll-up due to its fast diffusion rate and the relatively slow diffusion rate of N-2. In the zeolite 13X bed initially saturated with O-2, the breakthrough of Ar first koccurred with roll-up owing to the strong adsorption of N-2, then the breakthrough of N-2 followed after a very short interval. Based upon these results, the cyclic adsorption dynamics of the zeolite 13X VSA for air bulk separation and CMS PSA for oxygen purification were studied. The five-step two-bed O-2 VSA with zeolite 13X produced O-2 of over 90% purity with high recovery. The MTZ variation of N-2 during the adsorption and vacuum steps was described in detail. In the case of the six-step two-bed PSA process for 0,) purification, 0,) of 99.8+% purity could be produced from the binary mixture (O-2/Ar-95:5 vol.%). The dynamic adsorption behaviors were investigated by using a concentration-dependent rate model incorporated with mass, energy, and momentum balances. The model reasonably predicted the adsorption dynamics at the equilibrium and kinetic separation beds.