Methods of sequestering CO.sub.2 from a gaseous source of CO.sub.2 are provided. Aspects of the methods include employing an alkali enrichment protocol, such as a membrane mediated alkali enrichment protocol, in a CO.sub.2 sequestration protocol. Also provided are systems for practicing the methods.

The invention relates to a process for the combined production of hydrogen and carbon dioxide from a hydrocarbon mixture, in which the residual gas of a PSA H.sub.2 (12) is separated by permeation in order to reduce the hydrocarbon content thereof and the hydrocarbon-purified gas is separated at a low temperature to produce a carbon dioxide-rich liquid (22).

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.

Disclosed are embodiments of a cabin filter system including a sorbent material for removing gas and/or water from a cabin. The filter system also includes at least one heater configured to transmit thermal energy (e.g., microwave energy) to the sorbent material. Also disclosed are methods of using such filter systems.

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 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 carbon dioxide (CO.sub.2) capture and utilization system captures CO.sub.2 from flue gas and utilizes the same to enhance algae or cyanobacteria growth. The system generally comprises a CO.sub.2 capture unit and a utilization unit that is in fluid communication with the CO.sub.2 capture unit. The CO.sub.2 capture unit includes a membrane CO.sub.2 absorber that captures CO.sub.2 from incoming flue gas to produce a CO.sub.2-rich solvent. The utilization unit processes the CO.sub.2-rich solvent to produce a product stream that includes CO.sub.2 and NH.sub.3 in a predetermined CO.sub.2:NH.sub.3 ratio. The product stream is delivered to a cultivation subsystem of the utilization of the unit including one or more species of algae or cyanobacteria. A method for capturing and utilizing CO.sub.2 is also provided herein.

Described herein are systems and methods for the depolymerization of polyethylene-based plastics. In one embodiment, a method is disclosed that comprises combining a polyethylene-based plastic with a solvent in a reactor to generate a plastic solvent mixture, heating the plastic solvent mixture in the reactor, and fractionating the plastic solvent mixture into a gas phase product, a solid phase product, and a liquid phase product. In another embodiment, a system is disclosed that comprises a solvent, and a reactor configured to receive the polyethylene-based plastic and the solvent and convert the polyethylene-based plastic into a gas phase product, a solid phase product, and a liquid phase product, the reactor being configured to operate at a temperature greater than 275° C. and at a pressure greater than 2 megapascals.

The invention relates to a process and a plant for producing pure hydrogen from an input gas containing hydrogen and hydrocarbons, in particular from a hydrogen-containing refinery off-gas, by steam reforming in a steam reforming stage and multi-stage hydrogen enrichment. According to the invention the input gas containing hydrogen and hydrocarbons is separated in a first hydrogen enrichment stage into a hydrogen-enriched substream and a hydrogen-depleted substream, wherein at least a portion of the hydrogen-enriched substream is supplied to a second hydrogen enrichment stage or introduced into the pure hydrogen product stream and at least a portion of the hydrogen-depleted substream is supplied to the steam reforming stage as a reforming feed stream or as part thereof and/or to the burners as a fuel gas stream.

Provided is a method for upgrading a bio-based material, the method including the steps of pre-treating bio-renewable oil(s) and/or fat(s) to provide a bio-based fresh feed material, hydrotreating the bio-based fresh feed material, followed by separation, to provide a bio-propane composition.