A process and plant for producing a high purity CO.sub.2 product, comprising: providing a CO.sub.2-rich stream containing hydrocarbons, hydrogen and/or CO, combining it with a stream rich in methane (CH.sub.4), and mixing it with oxygen, thereby forming a CO.sub.2/O.sub.2- mixture; subjecting the CO.sub.2/O.sub.2- mixture to a catalytic oxidation step, thereby producing a purified stream having a higher CO.sub.2 and/or H.sub.2O concentration; removing H.sub.2O from said purified stream, for producing said high purity CO.sub.2 product stream. The CO.sub.2-rich stream is for instance derived from the CO.sub.2-removal section of a plant for producing hydrogen.

A membrane including a polymer substrate having pore channels and a metal-organic framework disposed on the polymer substrate. Methods of producing the membrane are described. Methods of separating gases using the membrane are also provided.

Disclosed is an adsorbent containing a metal oxide for adsorption of hydrogen sulfide in biogas, and a biogas purification system using the same.

A method for separating gaseous carbon dioxide from a gas mixture, preferably from at least one of ambient atmospheric air (1), flue gas and biogas, by cyclic adsorption/desorption using a sorbent material (3), wherein the method comprises at least the following sequential and in this sequence repeating steps (a)-(e): (a) contacting said gas mixture (1) with the sorbent material (3) to allow gaseous carbon dioxide to adsorb; (b) isolating said sorbent material (3) from said flow-through; (c) inducing an increase of the temperature of the sorbent material (3); (d) extracting at least the desorbed gaseous carbon dioxide from the unit (8) and separating gaseous carbon dioxide from steam in or downstream of the unit (8); (e) bringing the sorbent material (3) to ambient atmospheric conditions;
wherein said sorbent material (3) comprises primary and/or secondary amine moieties immobilized on a solid support, wherein the amine moieties, in the α-carbon position, are substituted by one hydrogen and one non-hydrogen substituent (R).

A gas separation membrane for selective separation of hydrogen and helium from gas mixtures containing carbon dioxide includes a porous support layer, an aromatic polyamide layer on the porous support layer, and a coating including a glassy polymer formed on the aromatic polyamide layer. A glass transition temperature of the glassy polymer is greater than 50° C. The gas separation membrane may be formed by contacting a solution including the glassy polymer with an aromatic polyamide layer of a composite membrane and drying the solution to form a coating of the glassy polymer on the aromatic polyamide layer. Separating hydrogen or helium from a gas stream including carbon dioxide includes contacting a gas feed stream including carbon dioxide with the gas separation membrane to yield a permeate stream having a concentration of helium or hydrogen that exceeds the concentration of helium or hydrogen, respectively, in the gas feed stream.

A methane destruction apparatus for capturing and converting fugitive methane gas emissions into carbon dioxide and water comprises a methane-capturing module for capturing the fugitive methane gas emissions and a methane conversion module for receiving captured methane from the methane-capturing module. The methane-capturing module includes a fugitive methane gas emission intake connected to an emissions line having a backpressure equal to 1 to 3 inches of water (249 to 746 Pa), a natural gas feed for feeding natural gas into the methane-capturing module, may include a relief vent for preventing overpressure within the methane-capturing module and a drain for draining liquids that have condensed within the methane-capturing module. The methane conversion module includes a conversion pad for catalytically converting the captured methane into carbon dioxide and water, a water vapour opening for outputting the water and a carbon dioxide opening for outputting the carbon dioxide.

Embodiments of the present disclosure describe polyimide blend compositions, methods of making polyimide blend compositions, methods of using polyimides, membranes including polyimide blends, methods of making membranes including polyimide blends, methods of separating mixtures using the membranes including polyimide blends, and the like.

Various illustrative embodiments of a system and process for recovering high-quality biomethane and carbon dioxide product streams from biogas sources and utilizing or sequestering the product streams are provided. The system and process synergistically yield a biomethane product which meets gas pipeline quality specifications and a carbon dioxide product of a quality and form that allows for its transport and sequestration or utilization and reduction in greenhouse gas emissions. The system and process result in improved access to gas pipelines for products, an improvement in the carbon intensity rating of the methane fuel, and improvements in generation of credits related to reductions in emissions of greenhouse gases.

System (2) for CO.sub.2 capture from a combustion engine (1) comprising an exhaust gas flow circuit (6) having an inlet end fluidly connected to an exhaust of the combustion engine, a heat exchanger circuit (12), a primary exhaust gas heat exchanger (H1) for transferring heat from exhaust gas to fluid in the heat exchanger circuit, at least one compressor (10) for compressing fluid in a section of the heat exchanger circuit, the compressor driven by thermal expansion of heat exchanger circuit fluid from the primary exhaust gas heat exchanger (H1), and a CO.sub.2 temperature swing adsorption (TSA) reactor (4) fluidly connected to an outlet end of the exhaust gas flow circuit. The TSA reactor includes at least an adsorption reactor unit (D4) and a desorption reactor unit (D2), the heat exchanger circuit comprising a heating section (12b) for heating the desorption unit (D2) and a cooling section (12a) for cooling the adsorption unit (D4).

The invention provides a system for removing target moieties from gas streams, the system comprising a supersonic expander coaxially positioned within an array of oblique shock inducers. Also provided is a method for removing target moieties from gas streams, the method comprising simultaneously subjecting the streams to supersonic expansion and oblique shock compression.