Disclosed is an improved method and system of operating the semi-closed cycle, which both reduces parasitic loads for oxygen generation and for gas clean up, while also reducing, capital cost of the gas clean up plant (reduced drying requirement) and of the oxygen plant (enabling membranes vs. mole sieves). The invention is applicable to piston or turbine engines, and results in a near fully non-emissive power system via the Semi-Closed Cycle (SCC), in a manner which both captures carbon in the form of carbon dioxide, CO2, and in a manner which improves the efficiency and cost effectiveness of prior disclosures. The captured carbon is of a purity and pressure directly suitable for Enhanced Oil Recovery (EOR), sequestration, or industrial use.

Electro oxidation membrane evaporator 1 comprises sweep air handler 60; fluid tank 20 defining a fluid container; fluid contactor/separator 30; oxidation cell 40; and scrubber 80. Electro oxidation membrane evaporator 1 may allow higher percent water recovery from wastewater prior to delivering brine to a brine water recovery system and can allow O.sub.2 from air such as cabin air to continuously diffuse into the wastewater as O.sub.2 is consumed to generate oxidants, helping to eliminate the low oxidant environment at the end of the cycle that causes pH to remain high, and low pH prevents precipitates from forming for longer so more water can be evaporated from the wastewater.

A pressure swing adsorption process (PSA) comprising the following steps: feeding an input gas containing H.sub.2, CO.sub.2 and impurities through a CO.sub.2 adsorbent material in a pressure vessel under a high pressure; withdrawing a first H.sub.2-rich product gas due to adsorption of CO.sub.2 in the adsorbent material; setting the pressure to an intermediate pressure causing the adsorbent material release a second gas stream; passing a CO.sub.2-rich purge stream through the adsorbent material, obtaining a purge gas; setting the pressure to a sub-atmospheric low pressure, so that a CO.sub.2-rich product gas is released under vacuum by the adsorbent material; re-pressurizing the vessel to said high pressure; said steps being performed cyclically in a pressure vessel or in a plurality of parallel pressure vessels of a multiple vessel setup.

Disclosed herein are 2-stage membrane separation methods for capturing CO.sub.2 from a feed gas. The methods can employ two selectively permeable membranes, which may be the same or different. The selectively permeable membrane can have a carbon dioxide permeance of from 500 to 3000 GPU at 57° C. and 1 atm feed pressure and a carbon dioxide:nitrogen selectivity of from 10 to 1000 at 57° C. and 1 atm feed pressure. High pressure ratios across the membranes can be achieved by compressing the feed gas to a high pressure, by using vacuum pumps to create a lowered pressure on the permeate side of the membrane, by using a sweep stream, or a combination thereof. When a sweep stream is used, the sweep stream may include a portion of the retentate gas stream obtained from the retentate side of one or more of the membranes used.

In a method for separating a mixture containing carbon dioxide, the mixture is cooled in a heat exchanger and partially condensed and a first liquid is separated from the mixture in a first system operating at low temperature comprising at least one first phase separator and a gas from the first system is treated in a membrane system to produce a permeate and a non-permeate, the gas from the first system being divided into two portions, a first portion being sent to the membrane system without being heated and a second portion being heated to at least an intermediate temperature of the heat exchanger and then sent to the membrane system without being cooled.

Disclosed herein is a gas separation membrane comprising a furan-based polymer, an apparatus comprising the gas separation membrane, and a process for separating a mixture of gases using said gas separation membrane. The process comprises contacting one side of a gas separation membrane comprising a furan-based polymer with a mixture of gases having different gas permeances, whereby at least one gas from the mixture of gases permeates preferentially across the gas separation membrane, thereby separating the at least one gas from the mixture of gases.

Disclosed is an absorbent containing an amine for absorption of an acid gas in a biogas, and a biogas purification system using the same.

The disclosure relates to a three-stage reciprocating compressor comprising pistons and suction and compression chambers in which a medium is compressed for each separate stage, which stages are connected in series and where a first stage is fluidly connected to an inlet for inlet of uncompressed or pre-compressed gas where the three-stage pistons move synchronously along a common axis in one connected unit such that the first and second stage suction and compression chambers share piston as well as cylinder wall, and having separate cylinder heads, a top headpiece and a bottom headpiece on each side of the piston, the third stage piston extending from a center of the first and second stage common piston and is passed through an opening in the cylinder head of the first stage suction and compression chamber, in extension of which is placed a third stage cylinder tube with a smaller diameter than a diameter of the cylinder for stage one and two, each stage fluidly separated by one or more one way valves, where the second stage suction and compression chamber is formed between the cylinder wall and a piston skirt as well as between an underside of the piston and the headpiece placed in a bottom of the cylinder.

A synthetic fuel production system and related techniques are disclosed. In accordance with some embodiments, the disclosed system may be configured to produce a liquid fuel using carbon dioxide extracted from the air and hydrogen generated from aqueous solutions by electrochemical means (e.g., water electrolysis). In production of the fuel, the disclosed system may be configured, in accordance with some embodiments, to react the carbon dioxide and hydrogen, for example, to form methanol. The disclosed system also may be configured, in accordance with some embodiments, to utilize one or more subsequent reaction steps to produce a given targeted set of hydrocarbons and partially oxidized hydrocarbons. For example, the disclosed system may be used to produce any one (or combination) of: ethanol; dimethyl ether; formic acid; formaldehyde; alkanes of various chain length; olefines; aliphatic and aromatic carbon compounds; and mixtures thereof, such as gasoline fuels, diesel fuels, and jet fuels.

This invention describes a method and apparatus for the capture, storage and release of carbon dioxide for use in the horticulture industry, the method including reduction of a transition metal oxide to form a transition metal and carbon dioxide; carburization or partial carburization of the transition metal to form metal carbide; carbonation of an alkaline metal oxide or alkaline earth metal oxide to form an alkaline metal carbonate or alkaline earth metal carbonate; contacting the metal carbide with air to produce a transition metal oxide and carbon dioxide; and calcining the alkaline metal carbonate or alkaline earth metal carbonate to form carbon dioxide and alkaline metal oxide or alkaline earth metal oxide. Also described is a sorbent material for use in the method and apparatus of the invention.