Method for separating gaseous carbon dioxide from air, in particular from ambient atmospheric air (1), by cyclic adsorption/desorption using a sorbent material (3), wherein said sorbent material (3) is a solid inorganic or organic, non-polymeric or polymeric support material functionalized on the surface with amino functionalities capable of reversibly binding carbon dioxide, with a specific BET surface area, preferably measured by nitrogen adsorption, in the range of 1-20 m2/g.

A process for separating carbon dioxide from a feed gas comprising carbon dioxide may comprise compressing the feed gas in a feed gas compressor to produce a compressed feed gas. The process may also comprise separating the compressed feed gas by an adsorption process comprising: using a plurality of adsorbent beds to produce a carbon dioxide-enriched product stream and a carbon dioxide-depleted stream, and a blowdown step. A blowdown gas may be removed from the adsorbent bed. The process may also comprise compressing the blowdown gas in the feed gas compressor and combining the blowdown gas with the compressed feed gas.

A process for separating carbon dioxide from a feed gas comprising carbon dioxide may comprise compressing the feed gas in a feed gas compressor to produce a compressed feed gas. The process may also comprise separating the compressed feed gas by an adsorption process comprising: using a plurality of adsorbent beds to produce a carbon dioxide-enriched product stream and a carbon dioxide-depleted stream, and a blowdown step. A blowdown gas may be removed from the adsorbent bed. The process may also comprise compressing the blowdown gas in the feed gas compressor and combining the blowdown gas with the compressed feed gas.

An apparatus that includes (A) an atmospheric water extraction unit; and (B) a direct air capture unit positioned downstream of and in communication with the atmospheric water extraction unit, wherein the apparatus is capable of reversibly operating in (i) adsorption mode to adsorb water and CO.sub.2 from an incoming air stream and (ii) regeneration mode to release adsorbed water and CO.sub.2, wherein the atmospheric water extraction unit comprises a first desiccant bed comprising a sorbent that adsorbs water from an incoming air stream during adsorption mode and releases water during regeneration mode, and wherein the direct air capture unit comprises a first moisture-responsive CO.sub.2 sorbent bed comprising a sorbent that adsorbs CO.sub.2 from an air stream during adsorption mode and releases CO.sub.2 upon contact with water vapor during regeneration mode.

An apparatus that includes (A) an atmospheric water extraction unit; and (B) a direct air capture unit positioned downstream of and in communication with the atmospheric water extraction unit, wherein the apparatus is capable of reversibly operating in (i) adsorption mode to adsorb water and CO.sub.2 from an incoming air stream and (ii) regeneration mode to release adsorbed water and CO.sub.2, wherein the atmospheric water extraction unit comprises a first desiccant bed comprising a sorbent that adsorbs water from an incoming air stream during adsorption mode and releases water during regeneration mode, and wherein the direct air capture unit comprises a first moisture-responsive CO.sub.2 sorbent bed comprising a sorbent that adsorbs CO.sub.2 from an air stream during adsorption mode and releases CO.sub.2 upon contact with water vapor during regeneration mode.

One variation of a method for carbon sequestration includes: mixing ambient air including carbon dioxide and secondary gases with a working fluid to generate a first mixture; conveying the first mixture through a compressor to pressurize the first mixture from a first pressure to a second pressure greater than the first pressure to promote absorption of carbon dioxide into the working fluid; depositing the first mixture in a high-pressure vessel to generate an exhaust stream of secondary gases and a second mixture including carbon dioxide dissolved in the working fluid; conveying the second mixture through a turbine configured to extract energy and reduce pressure of the second mixture, from the second pressure to the first pressure, to promote desorption of carbon dioxide from the working fluid; transferring the second mixture into the low-pressure vessel; and releasing carbon dioxide, desorbed from the working fluid, from the low-pressure vessel for collection.

A process for separating carbon dioxide from a waste gas of a fluid catalytic cracking installation including converting at least a portion of the carbon monoxide of the waste gas into carbon dioxide to form a flow enriched in carbon dioxide, separating at least a portion of the flow enriched in carbon dioxide to form a gas enriched in carbon dioxide and depleted in nitrogen and a gas rich in nitrogen and depleted in carbon dioxide, and at least a portion of the gas enriched in carbon dioxide and depleted in nitrogen is separated by way of separation at a temperature of less than 0° C. to form a fluid rich in carbon dioxide and a fluid depleted in carbon dioxide and sending a gas containing at least 90% oxygen to combustion.

A process for membrane separation of a mixture containing as main, or even major, components hydrogen and carbon dioxide and also at least one other component, for example chosen from the following group: carbon monoxide, methane and nitrogen, including: heating of the mixture in the heat exchanger, permeation of the reheated mixture in a first membrane separation unit making it possible to obtain a first permeate which is a hydrogen and carbon dioxide enriched relative to the mixture, and a first residue which is hydrogen and carbon dioxide lean, permeation of the first residue in a second membrane separation unit making it possible to obtain a second residue, at least one portion of the first permeate is compressed in a booster compressor and the second residue is expanded in a turbine, the booster compressor being driven by the turbine.

A process for membrane separation of a mixture containing as main, or even major, components hydrogen and carbon dioxide and also at least one other component, for example chosen from the following group: carbon monoxide, methane and nitrogen, including: heating of the mixture in the heat exchanger, permeation of the reheated mixture in a first membrane separation unit making it possible to obtain a first permeate which is a hydrogen and carbon dioxide enriched relative to the mixture, and a first residue which is hydrogen and carbon dioxide lean, permeation of the first residue in a second membrane separation unit making it possible to obtain a second residue, at least one portion of the first permeate is compressed in a booster compressor and the second residue is expanded in a turbine, the booster compressor being driven by the turbine.

A multi-stage process to remove contaminant gases from raw methane streams is provided. The present technology is an innovative solution to recover and purify biogas by use of a process having at least two pressure swing adsorption stages. Taking advantage of the presence of carbon dioxide in the raw biogas streams, nitrogen and oxygen are bulky removed in the first stage, using selective adsorbents, and a nitrogen and oxygen-depleted intermediate stream is yielded to the second stage. The second stage employs an adsorbent or adsorbents to selectively remove carbon dioxide and trace amounts of remaining nitrogen and oxygen, thus producing a purer methane stream that meets pipeline and natural gas specifications.