A three-product PSA system which produces three product streams from a feed gas mixture comprising a light key component, at least one heavy key component, and at least one intermediate key component is described. The three-product PSA system produces a high pressure product stream enriched in the light key component, a low pressure tail gas stream enriched in the at least one heavy key component, and an intermediate pressure vent gas stream enriched in the at least one intermediate key component.

An oxygen separator for generating an oxygen-enriched gas from an oxygen comprising gas, said oxygen separator comprising: a) an oxygen separator device comprising i) a sorbent material for sorbing at least one component of the oxygen comprising gas; and ii) at least two controllable interfaces, comprising a first controllable interface and a second controllable interface, for controlling the communication of gas between the inside and the outside of the oxygen separator device, b) a processor for controlling the oxygen separator such that a plurality of phases are sequentially carried, amongst them a purging phase; wherein the processor is configured to control the at least two controllable interfaces such that a flow of gas is generated between the first controllable interface and the second controllable interface during at least the purging phase, wherein the second controllable interface is located and/or controlled such that it controls the fluidic coupling between the inside of the oxygen separator device and a volume of non-oxygen-enriched gas during the purging phase.

A system for producing ammonia comprises a reactor configured for receiving nitrogen feed gas and hydrogen feed gas, the reactor comprising a catalyst configured to convert at least a portion of the nitrogen gas and at least a portion of the hydrogen feed gas to ammonia to form a reactant mixture comprising the ammonia and unreacted nitrogen feed gas and unreacted hydrogen feed gas, an adsorbent configured to selective adsorb at least a portion of the ammonia from the reactant mixture, and a recycle line to recycle the unreacted nitrogen feed gas, the unreacted hydrogen feed gas, and unabsorbed ammonia to the reactor.

An ammonia-producing system comprises a reactor that catalytically converts nitrogen and hydrogen feed gases to ammonia to form a reaction mixture of the ammonia, unreacted nitrogen gas, and unreacted hydrogen gas. A feed system feeds the nitrogen and hydrogen gases to the reactor at a reaction pressure of from about 9 to about 100 atmospheres. A reactor control system controls the temperature during conversion of the nitrogen and hydrogen to ammonia by maintaining a reaction temperature of from about 330 C. to about 550 C. An absorbent selectively absorbs at least a portion of the ammonia from the reaction mixture, and an absorbent control system controls one or both of a temperature and pressure at the absorbent during selective absorption of the ammonia from the reaction mixture. A recycle line downstream of the absorbent recycles the unreacted nitrogen and unreacted hydrogen to the reactor.

A method for upgrading biogas comprising methane and nitrogen, where the biogas is provided in at least one pressurized vessel at a pressure of at least 65 atm (6586 kPa). The method includes a pressure swing adsorption (PSA) cycle having a feed phase, where biogas is fed into a first adsorbent bed when the inlet end is open and the outlet end is closed, followed by a first depressurization phase, where a gas enriched in methane is withdrawn through the outlet end with the inlet end being closed. This gas enriched in methane can be pipeline quality and at pipeline pressures. A methane recovery phase is provided, which can improve methane recovery, wherein gas is withdrawn and the pressure drops to one or more lower values, and where this gas can be recycled for use in the feed phase, used in a regeneration phase, and/or fed to a second bed.

A method for upgrading biogas comprising methane and nitrogen, where the biogas is provided in at least one pressurized vessel at a pressure of at least 65 atm (6586 kPa). The method includes a pressure swing adsorption (PSA) cycle having a feed phase, where biogas is fed into a first adsorbent bed when the inlet end is open and the outlet end is closed, followed by a first depressurization phase, where a gas enriched in methane is withdrawn through the outlet end with the inlet end being closed. This gas enriched in methane can be pipeline quality and at pipeline pressures. A methane recovery phase is provided, which can improve methane recovery, wherein gas is withdrawn and the pressure drops to one or more lower values, and where this gas can be recycled for use in the feed phase, used in a regeneration phase, and/or fed to a second bed.