An energy efficient process for NGL recovery and production of compressed natural gas (CNG) in which natural gas is fed to a first gas separation membrane-based separation stage where it is separated into a permeate and a retentate. The high C.sub.3+ concentration first stage permeate is chilled and separated to provide liquid phase NGL and a gaseous phase. The first stage retentate is separated at a second gas membrane-based separation stage to produce a retentate meeting pipeline specifications for CNG (including hydrocarbon dewpoint) and a permeate that is recycled to the first stage. The gaseous phase, constituting a low BTU fuel, may be used in on-site power generation equipment and/or in internal combustion engines. The second stage permeate (and optionally the third stage retentate) is (are) recycled back to the first stage to enhance the production of NGL and CNG. The gaseous phase may instead be fed to a third stage to produce a third permeate and a third residue, in which case the third permeate is recycled to the first stage and the third retentate is a low BTU fuel which may be used in on-site power generation equipment and/or in internal combustion engines.

Methods and systems for the separation of hydrogen isotopes from one another are described. Methods include utilization of a hydrogen isotope selective separation membrane that includes a hydrogen isotope selective layer (e.g., graphene) and a hydrogen ion conductive supporting layer. An electronic driving force encourages passage of isotopes selectively across the membrane at an elevated separation temperature to enrich the product in a selected hydrogen isotope.

An article having a nanoporous membrane and a nanoporous graphene sheet layered on the nanoporous membrane. A method of: depositing a layer of a diblock copolymer onto a graphene sheet, and etching a minor phase of the diblock copolymer and a portion of the graphene in contact with the minor phase to form a nanoporous article having a nanoporous graphene sheet and a nanoporous layer of a polymer. A method of: depositing a hexaiodo-substituted macrocycle onto a substrate having a Ag(111) surface; coupling the macrocycle to form a nanoporous graphene sheet; layering the graphene sheet and substrate onto a nanoporous membrane with the graphene sheet in contact with the nanoporous membrane; and etching away the substrate.

Carbon dioxide gas in a high-pressure gas to be treated is stably separated using a separation membrane. Upon separating carbon dioxide gas in a high-pressure gas to be treated using a separation membrane module including a separation membrane, a preliminary boosted gas is supplied to the separation membrane module before the supply of natural gas is started to boost a pressure on a primary side of the separation membrane to a preliminary pressure between a stand-by pressure and an operating pressure. Thus, when the supply of a high-pressure gas to be treated is started to increase the pressure of the separation membrane module to an operating pressure, an abrupt decrease in temperature of the gas to be treated can be suppressed.

The present disclosure pertains to methods and systems for separating olefins from a mixture that includes olefins and non-olefins. The methods include associating the mixture with a support that is embedded with an ionic liquid and a metal ion. The ionic liquid prevents the substantial reduction of the metal ion by reducing agents while the metal ion mediates the transport of the olefin through the support by selectively and reversibly coupling with the olefin. In some embodiments, the support may be in the form of supported ionic liquid porous membranes, and the ionic liquid may be held within the pores of the support by capillary forces. In some embodiments, the support may be in the form of a composite, and the ionic liquid may be dispersed throughout the composite. In some embodiments, the metal ion may be dissolved in the ionic liquid and dispersed throughout the support.

Methods and systems for the separation of hydrogen isotopes from one another are described. Methods include utilization of a hydrogen isotope selective separation membrane that includes a hydrogen isotope selective layer (e.g., graphene) and a hydrogen ion conductive supporting layer. An electronic driving force encourages passage of isotopes selectively across the membrane at an elevated separation temperature to enrich the product in a selected hydrogen isotope.

An air purifying system is a system for purifying air in a room, and the air purifying system includes: a carbon dioxide removing device including a first space and a second space that are divided from each other by a separation membrane that selectively allows carbon dioxide to permeate therethrough; a feed passage that leads the air in the room to the first space; a return passage that leads purified air from which carbon dioxide has been removed from the first space to the room; a supply passage that supplies sweep gas to the second space, the sweep gas having a carbon dioxide partial pressure that is lower than a carbon dioxide partial pressure in the air in the room; and a discharge passage that discharges the sweep gas from the second space after the sweep gas is mixed with the carbon dioxide that has permeated through the separation membrane.

A facility and method for membrane permeation treatment of a feed gas flow containing at least methane and carbon dioxide that includes a compressor, a pressure measurement device, at least one valve, and first, second, third, and fourth membrane separation units for separation of CO.sub.2 from CH.sub.4 to permeates enriched in CO.sub.2 and retentates enriched in CH.sub.4, respectively. The at least one valve adjusts the number of membranes combined and connected to the flow of gas entering into at least one of the membrane separation units as a function of the pressure recorded by the pressure measurement device.

Methods and systems are provided for treating the tail gas stream of a sulfur recovery plant. The methods including generating a tail gas stream from a sulfur recovery plant, treating the tail gas stream with a hydrogen sulfide removal unit and a hydrogen selective membrane unit, generating a stream low in hydrogen sulfide and a stream rich in hydrogen. The hydrogen sulfide rich stream is recycled to the sulfur recovery unit. The hydrogen selective membrane unit includes a glassy polymer membrane selective for hydrogen over hydrogen sulfide and carbon dioxide.

The present invention discloses an integrated new technique and apparatus for recycling volatile organic compounds of coating printing. The new technique collects a mixed gas of volatile organic compounds produced in the process of coating and drying of a coating machine with a volatiles collecting hood of coating machine, compresses and lead the mixed gas of volatile organic compounds into a condensation system for condensation; the obtained condensate enters a gas-liquid separator to obtain a coating solvent with high concentration; non-condensable lean gas enters a membrane separation and enrichment system to obtain a mixed gas of high concentration organic compounds after membrane separation and enrichment with a complete set of membrane assembly, and then returns to front of the condensation system to repeat the integrated technique. The separation membrane as claimed in the present invention has an extremely high permselectivity for volatile organic compounds of coating printing and can quickly enrich the volatile organic compounds. Recycling rate of volatile organic compounds of the apparatus may reach 90%, and the content of organic compounds in the tail gas emission after treatment is no more than 1 g/m.sup.3. This integrated new technique largely reduces the production cost of coating printing industry and at the same time protects the atmospheric environment.