Abstract: A method for increasing product recovery or reducing the size of steam methane reformer and pressure swing adsorption systems utilized for hydrogen production. A significant portion of the hydrogen in the PSA depressurization and purge effluent gas, which is otherwise burned as fuel in the reformer, is recovered and recycled to the PSA system to provide additional high purity hydrogen product. This is accomplished by processing selected portions of the depressurization and purge effluent gas in adsorbent membrane separators to increase hydrogen content for recycle to the PSA system. Remaining portions of the depressurization and purge effluent gas which contain lower concentrations of hydrogen are utilized for fuel value in the reformer.

Abstract: A process for pressure swing adsorption of oxygen from a gas mixture containing at least oxygen and nitrogen to recover an unadsorbed nitrogen enriched product from a plurality of parallel piped adsorbent beds undergoing adsorption, depressurization and repressurization wherein the improvement is conducting a pressure transfer from one bed to another from an intermediate point of the bed finishing adsorption to a point closer to the feed end of a bed that is repressurizing to improve productivity and recovery of nitrogen enriched gas in the process.

Abstract: A PSA method incorporating the invention is applicable to the separation of a preferred gas from a mixture of the preferred gas and a less preferred gas. The PSA method uses an adsorbent bed including one or more layers of O.sub.2 equilibrium selective adsorbents, and comprises the steps of: pressurizing the adsorbent bed to a high pressure with a feed of air to enable the adsorbent bed to adsorb O.sub.2 ; extracting from the bed at bed pressure, a flow of N.sub.2 and storing at least some of the flow in a product tank; desorbing O.sub.2 from the adsorbent bed by feeding void gas in the bed enclosure to a storage tank and venting the adsorbent bed to a low pressure region; purging the adsorbent bed by feeding thereto the void gas from the storage tank; and repressurizing the adsorbent bed to an intermediate pressure with a flow of void gas from the storage tank.

Abstract: The flow rate of a nonadsorbed product gas stream from a multiple unit PSA plant can be reduced in response to a reduced product demand by isolating all units in the plant and inserting an idle step into the adsorption cycle immediately following bed equalization steps of the cycle. In a preferred embodiment, the duration of the idle step is inversely proportional to the percentage reduction in the product demand. To maintain the product gas purity at the desired level, minor adjustments of the idle step duration can be made following adjustment to the idle step in response to a change in product demand.

Abstract: The process comprises a regeneration phase including a co-current depressurization step, in order to participate in the repressurization of another adsorber, a countercurrent depressurization down to the low pressure of the cycle without gas intake, and then a countercurrent elution step at the low pressure of the cycle with oxygen taken off from production. The cycle time does not exceed 20 seconds. The process is particularly application to the production of oxygen having a purity greater than 90% with flow rates of 2 to 6 liters/minute for oxygenotherapy.

Abstract: The present process is directed to the efficient recovery of helium gas from gas streams which contain about 25 percent by volume or more helium. The process comprises two stages of pressure swing adsorption, each stage being comprised of a plurality of interconnected adsorbent beds. In the first stage of pressure swing adsorption which is comprised of about five phases, the helium content of the gas stream is increased to 95 percent by volume or more. A secondary product gas stream from the first stage of pressure swing adsorption is fed to the second stage of pressure swing adsorption. The second stage of pressure swing adsorption increases the helium content of this primarily non-helium product gas to more than about 50 percent by volume. This gas now with a helium content of more than about 50 percent by volume is fed along with the gas stream as the input gas to the first stage of pressure swing adsorption.

Abstract: A pressure swing adsorption process which includes switching a plurality of adsorption columns packed with an adsorbent successively to an adsorption step, a pressure equalization step, an evacuation step, a vacuum purge step, a pressure equalization step and a repressurization step to allow a more strongly adsorbable component gas contained in a gaseous mixture to be adsorbed on the adsorbent and to separate a less strongly adsorbable component gas. The process further includes compressing the thus separated less strongly adsorbable component gas by a product gas compressor to supply it as a product gas.

Abstract: Vacuum pressure swing adsorption (VPSA) processing is carried out employing a processing sequence of ten steps that serves to enhance the productive capacity thereof for air separation and other desirable applications.

Abstract: A regenerative desiccant air dryer system. Dry air is alternately drawn from approximately the center of two desiccant housings which are open at the top and bottom. A reclamation assembly directs dry air into the housing being purged to assist in the purging of moisture from the desiccant, and subsequently cooling the desiccant. The system is portable and operated by a programmable controller.

Abstract: A process for separating a mixture of gases by selective adsorption, in which pressure swing is used to induce both desorption and the flow of gas through at least one simulated moving chromatographic column.

Abstract: A pressure swing adsorption process for the recovery of oxygen from air improves upon a prior art process by depressurizing the adsorbent bed within an adsorbent vessel to an intermediate pressure by releasing void space gas from the product end of the vessel to a low purity oxygen tank while concurrently evacuating the adsorbent vessel from the feed end. This action enables an increased speed of depressurization and a reduction of the cycle time. Further, the adsorbent bed is repressurized to an intermediate pressure from the product outlet end with gas from the low purity oxygen tank, while concurrently pressurizing the adsorbent vessel from the input feed end. This action increases the load time fraction for a feed/vacuum blower. Further, oxygen is introduced to the product end of the adsorbent bed vessel from a high purity oxygen tank (which provides product to downstream applications) while concurrently, air is introduced to the feed end of the adsorbent bed within the vessel.

Abstract: A vacuum swing adsorption process for separating a feed gas mixture into a more strongly adsorbable component and a less strongly adsorbable component in a process employing two vacuum pumps and three adsorbent beds containing an adsorbent selective for the more strongly adsorbable component using countercurrent depressurization and cocurrent ambient feed repressurization simultaneous with product end to product end pressure equalization and a common-shaft machinery arrangement which allows the expansion energy contained in the countercurrent depressurization and cocurrent ambient feed repressurization streams to be recovered and utilized to reduce overall process power consumption. Addition of three valves and an expander element will also allow expansion energy in the product purge and pressure equalization streams to be recovered. Oxygen product can be recovered from air at low cost using the process.

Abstract: Large vacuum pressure swing adsorption-oxygen plants are employed with four adsorption vessels, two air compressors, two vacuum pumps and an oxygen surge tank, operated on a (two) two-bed processing system basis. One two-bed system is offset from the other by one half of one half processing cycle. Reduced power and capital cost savings are achieved.

Abstract: Pressure swing apparatus comprises at least three parallel beds of adsorbent operated on cycles of being on-line to adsorb contaminant from a feed gas stream under pressure, being depressurized, being regenerated by a purge gas, and being repressurised. Feed gas is transferred from a depres-surising bed to a repressurizing bed to reduce switch loss and repressurization is extended to occupy at least 50% of the cycle to smooth the feed gas output.

Abstract: Method and apparatus for separating gases, especially for removing water or from a gas such as air. This invention uses a short-cycle process which produces reduction in dewpoint (for dehydrating gas separation processes) or change in gas concentration (for non-dehydrating gas separation processes) at high pressure, and which includes adding a short burst of heat during the beginning of the reactivation cycle to boost desorption and complete it typically in about thirty minutes or less time. An easily desorbed desiccant (or other adsorbent material for non-dehydrating applications) and the short low-temperature burst of heat serve to reactivate a significant portion of the desiccant bed (or adsorbent bed), and the cooler purge fluid that follows cools that portion of the bed in preparation for the next drying (or adsorbing) cycle.

Abstract: The disclosed hybrid membrane and pressure swing adsorption process can recover helium from source streams of about 0.5 to 5 percent by volume helium and concentrate the helium to a concentration of greater than about 98 percent by volume. The process comprises a membrane separation followed by two stages of pressure swing adsorption which are used in series. The source gas will primarily contain hydrocarbons but will contain some nitrogen. The membrane unit will contain a semipermeable membrane which is permeably selective for helium and will to the extent feasible reject hydrocarbons. The permeate gas will be increased in helium content by 2 to 10 times. Part of the residue gas is used in the regeneration of the adsorbent beds in the first stage of pressure swing adsorption. Each stage of pressure swing adsorption will contain a plurality of adsorbent beds, and will be cycled through multiple phases.

Abstract: A process for separating components of a gas by adsorption in an enclosure (1) divided into equal tight separated compartments (27) each provided with an adsorbent material (7, 8) chosen in function of the gas to be treated and each provided for temporarily allowing the gas to be treated to be introduced and at least one chosen component of the components of this gas to be evacuated whilst the other component or components of this gas are adsorbed by the material (7, 8), which process consists in introducing the gas to be treated into one of the compartments (27) until a predetermined pressure is reached while in the next compartments (27), gas to be treated is introduced in at least one compartment (27) and the chosen component is allowed to escape, the pressure in the next compartment (27) is allowed to drop so as to obtain a partial desorption of the non chosen component or components of the gas, a purging fluid is injected in the last compartment to achieve the final desorption, and device for carrying ou

Abstract: An adsorption process in which high and low pressure feed streams are introduced into a plurality of beds to produce product streams by adsorbing one or more preferentially adsorbed components within the beds. Each bed is subjected to a low pressure feed stage to produce a low pressure product stream followed by a high or higher pressure feeding stages to produce one or more high pressure product streams. Thereafter the beds are regenerated through depressurization and purge stages. The cycle is conducted out of phase so that one of the beds is producing the high pressure product stream while another bed is producing a low pressure product stream.

Abstract: Segregated external gas storage tanks are used to store gases of varying purity for use in the purge and pressure equalization and product repressurization steps of pressure swing adsorption operations, thereby enabling the bed size factor and the power requirements of pressure swing adsorption-gas separation operations to be significantly reduced.

Abstract: An air separation method in which a pre-purification unit is provided with three or more beds which are subjected to a pressure swing adsorption process. Each of the beds is subjected to feed, pressurization, purge and repressurization stages. The purge stages are conducted with a waste stream from the air separation unit and the duration of the purge stage is equal to the total time of the cycle divided by the number of beds.

Abstract: In a "vacuum" type cycle, the depressurization of a first adsorber at the high pressure of the cycle is effected by placing it in communication with the outlet of a second adsorber at the low pressure of the cycle. This communication takes place simultaneously with countercurrent pumping in a first stage for the second adsorber and in a second stage for the first adsorber, the recompression to the high pressure of the cycle being effected by production gas. Used for the production of oxygen from air.

Abstract: A method for recovering argon and hydrogen simultaneously from a feed mixture comprising argon, hydrogen, methane, nitrogen, ammonia, and moisture by passing a two stage adsorption separation (PSA). The feed gas including 4-6% hydrogen is sent to the first stage PSA to obtain a product hydrogen during the first period of adsorption step, and to obtain an intermediate product of argon and hydrogen mixture during the next period of adsorption step. The adsorbed gases are evacuated and sent to fuel gas. The intermediate product argon and hydrogen mixture is sent to the second stage adsorption bed. The effluent of adsorption step is recovered as another product hydrogen. After the adsorption step, the second stage adsorber is undergone concurrent blowdown, pressure equalization, argon recovery, argon purge, desorption production of argon, pressure equalization, pressurization with product hydrogen. Through such cyclic operation of two-stage PSA, high purity argon and hydrogen are recovered simultaneously.

Abstract: The disclosed pressure swing adsorption processes can recover helium from source streams of less than about 10 percent by volume helium and concentrate the helium to a concentration of greater than about 98 percent by volume. Two stages of pressure swing adsorption are used in series. The source of the helium gas will be natural gas wells. The source gas will contain hydrocarbons but in most instances the primary gas other than helium will be nitrogen. Each stage of pressure swing adsorption will contain a plurality of adsorbent beds, and preferably about four. In each stage the adsorbent beds will be cycled through multiple phases. In the first stage the adsorbent beds will sequentially undergo the phases of adsorption, recycle, depressurization, evacuation, helium pressurization and recycle feed pressurization.

Abstract: A process for separating a feed gas mixture into a more strongly adsorbable component and a less strongly adsorbable component in a plurality of adsorbent beds containing an adsorbent selective for the more strongly adsorbable component using cocurrent depressurization to provide purge gas and pressurization by product end to product end pressure equalization between beds simultaneous with cocurrent ambient and elevated pressure feed pressurization, and countercurrent evacuation. Oxygen product can be recovered from air at high recovery and adsorbent productivity levels using the process.

Abstract: A natural gas feed stream containing significant quantities of nitrogen can be increased to a content of greater than 95 percent by volume of natural gas, and preferably greater than about 98 percent, by passing the natural gas feed stream sequentially through at least four adsorbent beds which are cycled through six phases comprising an adsorption phase to adsorb natural gas, a recycle phase to remove feed gas from the voids in the adsorbent bed and nitrogen from the adsorbent by the passage of a depressurization gas therethrough to produce a recycle gas, a depressurization phase to reduce the adsorbent bed pressure to about ambient and to produce the depressurization gas, an evacuation phase where the pressure in the adsorbent is further reduced and an enriched natural gas product stream recovered, a pressurization phase where the pressure in the adsorbent bed is increased using nitrogen gas from a bed in an adsorption phase, and further pressurizing the adsorbent bed in a recycle feed pressurization phase

Abstract: Process swing adsorption processes for gas separation are carried out using overlapping pressure swing adsorption, feed gas repressurization and desorption steps. The adsorptive capacity of the system employed is increased, unit power consumption is decreased, and the overall efficiency of the operation is enhanced.

Abstract: The present invention is an apparatus and method for preferentially adsorbing carbon monoxide from a gas stream containing carbon monoxide in the presence of water and potentially ammonia while not adsorbing methane, hydrogen or carbon dioxide which may be present in the gas stream using an adsorbent of a supported cuprous compound situated downstream serially from a pretreatment adsorbent of 3A zeolite which protects the cuprous compound from water. An additional pretreatment layer of a basic metal compound to protect the acid-unstable 3A zeolite layer is also contemplated.

Abstract: The present invention is an apparatus and process for separating oxygen from air by adsorption of at least nitrogen on multiple layers of air separation adsorbent in an adsorption bed wherein the multiple layers are Na X-zeolite followed by at least another layer of adsorbent selected from the group consisting of Ca X-zeolite, Li X-zeolite, Ca A-zeolite followed by Ca X-zeolite, Ca A-zeolite followed by Li X-zeolite, Ca X-zeolite followed by Li X-zeolite, Li X-zeolite followed by Ca X-zeolite and Mg A-zeolite followed by Ca X-zeolite.

Abstract: Oxygen of uniform purity is produced in a two-bed air-fed oxygen pressure swing adsorption process in which the beds are operated out of phase. The steps of the adsorption cycle include a pressurization/production step and a bed regeneration step, with the bed undergoing regeneration being purged with a low pressure stream of the oxygen-enriched gas produced as the nonadsorbed product of the process. The oxygen concentration in the purged gas effluent is continuously periodically monitored, and the maximum oxygen concentration in the effluent during selected purge steps is compared with the maximum oxygen concentration in the effluent during a previous purge step, and the difference is used to adjust the timing and duration of a purge step following the selected purge step in a manner that reduces the difference between the oxygen concentration in the sequential purge steps.

Abstract: The components of a gas mixture are separated by pressure swing adsorption in a plurality of adsorption vessels. In the first step of the half-cycle adsorption takes place in a first bed while the second bed undergoes countercurrent desorption. At the end of the first step the first bed is vented countercurrently and the first and second beds undergo, as a first bed equalization step, outlet-to-outlet equalization or outlet to both inlet and outlet equalization. The vent step may precede or be concurrent with the first bed equalization step. In a second equalization step the beds simultaneously undergo inlet-to-inlet and outlet-to-outlet equalization. The second bed is then further pressurized with nonadsorbed product gas. The half cycle is then repeated but with the first bed being substituted for the second bed and vice versa.

Abstract: A process claimed for the removal of VOCs from fluid streams. The process comprises a vacuum swing adsorption zone containing at least 2 adsorption beds wherein the adsorbent beds are cocurrently purged with a diluent stream comprising an inert gas prior to a countercurrent evacuation step. In addition, the adsorbent beds may contain a first adsorption layer comprising an adsorbent selective for the adsorption of the inert gas, whereby the inert gas is retained within the VSA system to prevent the creation of an explosive mixture upon the condensation of the desorbed VOCs.

Abstract: A method of separating nitrogen-enriched gas is performed by PSA with the use of an apparatus which comprises a plurality of adsorbers (1, 2), a balance tank (3), and a product receiver (4). The method is characterized by comprising the steps of (a) passing, at a predetermined flow rate, high-purity nitrogen gas from the balance tank (3) to an outlet of an adsorber (2) undergoing regeneration; (b) establishing communication between the outlets of both adsorbers (1, 2) through a pressure equalization line while opening the inlets of both adsorbers to atmospheric pressure; (c) after the above step (b), causing a predetermined amount of high-purity nitrogen gas in the balance tank (3) to reversely pass via the outlet of the adsorber (2) which is to be switched from regeneration to adsorption while also supplying the crude gas through its inlet.

Abstract: A process claimed for the removal of VOCs from fluid streams. The process comprises a vacuum swing adsorption zone containing at least 2 adsorption beds wherein the adsorbent beds are cocurrently purged with a diluent stream comprising an inert gas prior to a countercurrent evacuation step. In addition, the adsorbent beds may contain a first adsorption layer comprising an adsorbent selective for the adsorption of the inert gas, whereby the inert gas is retained within the VSA system to prevent the creation of an explosive mixture upon the recovery of the desorbed VOCs.

Abstract: During a purge step of a PSA plant the waste gas being vented is analyzed to identify when a preselected volume of the waste gas contains purge gas after which the purge step is stopped.

Abstract: A process is set forth for purifying and liquefying a feed gas mixture with respect to its less strongly adsorbed component of lower volatility which integrates temperature swing adsorption (TSA), pressure swing adsorption (PSA) and cryogenic distillation to optimize overall performance. The TSA portion of the process is used to remove the strongly adsorbed component from the feed; the PSA portion of the process is used to remove the moderately strongly adsorbed component from the feed; and the cryogenic distillation portion of the process is used to remove the less strongly adsorbed component of higher volatility from the feed while also providing for the liquefaction of the product. A key to the present invention is the use of the PSA and distillation waste streams in the regeneration of the TSA and PSA adsorbents. An important application of the present invention is the purification and liquefaction of a natural gas feed stream with respect to its methane/C.sub.2 hydrocarbon component.

Abstract: A process for removing argon from a feed gas stream comprising oxygen and argon to yield a high purity oxygen stream and the system for carrying out the process. The process includes the steps of: (a) providing a feed gas of oxygen and argon at a temperature between -30.degree. C. and 100.degree. C. and a pressure between 5 psia and 160 psia; and (b) passing the feed gas over an adsorbent bed comprising a Ag ion exchanged type X zeolite wherein at least 80% of the available ion sites are occupied by Ag such that at least a portion of the argon in the feed gas is adsorbed by the adsorbent bed thereby leaving an oxygen-enriched gas stream.

Abstract: Type X zeolites whose charge-compensating cations are composed of 95 to 50% lithium ions, 4 to 50% of one or more of aluminum, cerium, lanthanum and mixed lanthanides and 0 to 15% of other ions. The zeolites preferentially adsorb nitrogen from gas mixtures.

Abstract: The present invention provides a process for the recovery of methyl chloride from a mixture thereof with isobutane. The process employs pressure swing adsorption with a size selective adsorbent having a pore opening of between about 3.7.times.3.7 Angstroms and about 4.9.times.5.7 Angstroms, such as zeolite A, clinoptilolite and mixtures thereof to selectively adsorb methyl chloride from vent streams comprising methyl chloride and isobutane and recovering a tail gas stream enriched in methyl chloride. The process may be used in applications such as treating the vent gas streams from the direct synthesis of methyl chlorosilanes. The process provides an economical route to recovering a valuable raw material in the process of making silicones and reduces the volume and methyl chloride content of the vent stream which is typically incinerated to avoid the release of halogenated hydrocarbons to the atmosphere.

Abstract: A system for controlling the atmosphere of a container for use in the storage and/or transportation of perishable goods which includes adsorption apparatus for the selective adsorption in whole or in part and in a predeterminded order of any water vapor, carbon dioxide, oxygen or ethylene contained within the atmosphere, a blower for urging the atmosphere to the adsorption apparatus, and a conduiting for returning the controlled atmosphere to the container.

Abstract: The disclosure describes a sorbing apparatus for removing one or more undesirable components from an influent gas. The sorbing apparatus comprises at least one chamber having first and second ports and defining a gas flow path between the first and second ports. A sorbent bed having a sorbing region and a guard region is disposed in the sorbing chamber in the gas flow path. The sorbing region includes a first sorbent material and the guard region includes a second sorbent material. A gas control arrangement is coupled to the sorbing chamber to cyclically (1) direct the influent gas through the first port, through the sorbing region and the guard region of the sorbent bed and out the second port wherein the undesirable components are sorbed from the influent gas and (2) direct a purge gas through the second port, through the guard region and the sorbing region of the sorbent bed and out the first port wherein the sorbing region is regenerated.

Abstract: The present invention is a nitrogen pressure swing adsorption process for separating gas mixtures containing nitrogen and oxygen, such as air, using a unique gas transfer process step, continuous feed gas introduction and an appropriate isolation step with continued product purge/repressurization to achieve high purity nitrogen product of 99.9% or greater by volume nitrogen, preferably 99.99% or greater by volume of nitrogen.

Abstract: A gas drying device (30) in which wet gas (31) is introduced into a chamber (36) containing desiccant (38) in which the desiccant (38) adsorbs moisture from the wet gas (31) to dry the wet gas (31) and in which energy is utilized to energize and to remove the moisture from the desiccant (38) to dry and to regenerate the desiccant (38) for reuse to dry wet gas (31) includes a microwave generator (52) and an antenna member (48) in communication with microwaves (50) generated by the microwave generator (52) in which at least a portion of the antenna (48) is disposed within the chamber (46).

Abstract: A process for separating a feed gas mixture into a more strongly adsorbable component and a less strongly adsorbable component in a plurality of adsorbent beds containing an adsorbent selective for the more strongly adsorbable component using pressurization by product end to product end pressure equalization between beds simultaneous with cocurrent ambient and elevated pressure feed pressurization, coproduction of product and purge gas, and cocurrent depressurization for pressure equalization gas simultaneous with countercurrent evacuation. Oxygen product can be recovered from air at high recovery using the process.

Abstract: A device (10) for removing contaminants from truck air systems or the like includes an assembly including a desiccant canister (100), a carrier (46), and a bottom closure (28) vertically removable in a passage (14) of a collar (12) mounted to the truck. The carrier (46) includes a horizontal plate (48) which divides the passage (14) into a coalescing chamber having a horizontally orientated, tubular coalescing filter (98) extending vertically above and diametrically over the sump including an electrically actuated purge valve (42) of the bottom closure (28). Air is directed vertically downward from the filter (98) by vertical legs (62) extending down from the horizontal plate (48) and on opposite sides of the filter (98). A follower plate (118) is biased in the canister (100) against the desiccant beads (116) by a wave spring (140) sandwiched thereagainst by a slideable retainer (142) fixed in the side wall (104) of the canister (100).

Abstract: A process claimed for the removal of VOCs from fluid streams. The process comprises a vacuum swing adsorption zone containing at least 2 adsorption beds wherein the adsorbent beds are cocurrently purged with at diluent stream comprising an inert gas prior to a countercurrent evacuation step. In addition, the adsorbent beds may contain a first adsorption layer comprising an adsorbent selective for the adsorption of the inert gas, whereby the inert gas is retained within the VSA system to prevent the creation of an explosive mixture upon the condensation of the desorbed VOCs.

Abstract: A process for separating a feed gas mixture into a more strongly adsorbable component and a less strongly adsorbable component in a plurality of adsorbent beds containing an adsorbent selective for the more strongly adsorbable component with two cocurrent depressurizations, first to provide product and then to provide a purge gas, and using a combination of less strongly adsorbable component and feed gas mixture to repressurize the adsorbent bed. Oxygen product can be recovered from air at high recovery using the process.

Abstract: Vacuum and other pressure swing adsorption vessels are monitored, and corrective adjustments are made in the pressure equalization and/or repressurization steps in response to imbalances in the temperature profiles of the vessels in order to tune the system. The PSA process is also desirably purge tuned to avoid over purging or under purging of each vessel.

Abstract: The process is conducted in a circuit having first and second adsorbers and a product reservoir vessel, connected serially. The feedstock is a gas mixture containing contaminant and product components (for example, air containing N.sub.2 and O.sub.2). The process steps involved are: (1) feeding a charge of feed gas into the first adsorber, temporarily retaining it therein, and pressurizing it, so that the adsorbent adsorbs most of the contaminant component and purified product gas is produced; (2) co-currently depressurizing the first adsorber by discharging purified product gas through the second adsorber and reservoir vessel; (3) counter-currently venting both adsorbers; (4) partly re-pressurizing both the adsorbers with purified gas from the reservoir vessel; and then repeating steps (1)-(4) inclusive.

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: The present invention is directed to a process for separating nitrogen from gas mixtures containing nitrogen and less strongly adsorbed components such as oxygen, hydrogen, argon or helium at ambient temperatures or above by use of a magnesium exchanged, sodium A-zeolite in a preferred level of magnesium exchange and an appropriate pressure range for adsorption and desorption of bulk gases which provides improved recovery and reduced bed size factor.