Abstract: A two stage pressure swing adsorption process is set forth for producing the less strongly adsorbed component of a feed gas mixture wherein the first stage utilizes a first adsorbent for bulk removal of the more strongly adsorbed component and wherein the second stage utilizes a second adsorbent for trace removal of the more strongly adsorbed component. A further feature of the present invention is that the desorbed gas from the second stage's depressurization step (consisting primarily of the desired less strongly adsorbed component) is recycled to the first stage in order to improve its performance. In a preferred embodiment of the present invention, high purity nitrogen (less than 1000 ppm oxygen, preferably less than 100 ppm oxygen) is produced from an air feed using a kinetically controlled carbon molecular sieve adsorbent in the first stage and an equilibrium controlled metal complex-based adsorbent in the second stage.

Abstract: Valuable process gas is dried to a low water content, for example a dew point of less than -20.degree. F., using membrane separation in which compression of the permeate gases and condensation and separation of liquid water from the permeate stream is combined with a total recycle of uncondensable permeate gases so that no process gas is lost as a result of the drying operation. Feed gas is combined with the recycled gas either prior to compressing, cooling and separating the liquid water from the process gas or subsequent to these steps, depending upon the pressure of the available feed stream to be dried. Membrane separation efficiency is improved by sweeping the downstream surfaces of the membrane with dried product gas. All of the sweep gas is recaptured with the permeate gases and returned to the separation unit, thereby enabling 100%, recovery of the fresh feed gas from the drying operation. Only liquid water and dissolved gases are purged from the system.

Abstract: The present invention is a process for the production and recovery of an O.sub.2 -lean argon stream from a gas mixture containing argon and oxygen. The argon-containing gas mixture is initially treated in a cryogenic separation unit to produce a crude argon stream having an argon concentration between 80-98%. The crude argon stream is passed to a membrane separation unit where it is separated to produce an O.sub.2 -lean argon stream and an O.sub.2 - rich stream. The O.sub.2 -rich stream is recycled tothe cryogenic separation unit and the O.sub.2 -lean argon stream is recovered as product or futher purified.

Abstract: The present invention involves an efficient process for recovering helium from a gas mixture containing helium and at least one other component. Separation is effected by integrating a semi-permeable membrane-based unit with a non-membrane type separation unit.

Abstract: The present invention is a process for separating and recovering a component from a multi-component feed gas mixture. The feed gas mixture is initially separated in a membrane separation unit or units to produce a gas stream concentrated in the desired component. The concentrated gas stream is subsequently further separated in an adsorption unit having an adsorbent which selectively adsorbs non-desired gaseous components thereby producing a purified product stream. The non-desired gaseous components are subsequently desorbed and a purge stream from the adsorption unit containing the desorbed non-desired gaseous components along with a portion of the desired components is recycled to the feed gas mixture.