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).

A hydrocarbon is reacted with water in the presence of a catalyst to form hydrogen, carbon monoxide, and carbon dioxide. Hydrogen is selectively allowed to pass through a hydrogen separation membrane to a permeate side of a reactor, while water and carbon-containing compounds remain in a retentate side of the reactor. An outlet stream is flowed from the retentate side to a heat exchanger. The outlet stream is cooled to form a cooled stream. The cooled stream is separated into a liquid phase and a vapor phase. The liquid phase is flowed to the heat exchanger and heated to form steam. The vapor phase is cooled to form condensed water and a first offgas stream. The first offgas stream is cooled to form condensed carbon dioxide and a second offgas stream. The steam and the second offgas stream are recycled to the reactor.

Methods and systems for producing carbon-negative hydrogen and renewable natural gas from biomass are included herein. In an embodiment, the method may include gasifying biomass in a gasification unit to form a first stream comprising syngas. The syngas may include methane, hydrogen, carbon dioxide, carbon monoxide, ethylene, and water. The method may also include reacting the carbon monoxide with water in the presence of a catalyst to form a second stream. The second stream may include a greater hydrogen concentration than the first stream. The method may further include separating at least a portion of the second stream to form a hydrogen stream and a natural gas stream. The hydrogen stream may have a greater concentration of hydrogen than the second stream. The natural gas stream may have a greater concentration of methane than the second stream.

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 power-to-X system for the utilization of off-gases, includes an electrolyzer for generating hydrogen H2 and oxygen O2, a unit, connected to the electrolyzer, for processing the hydrogen H2, for removing any remaining water H2O and oxygen O2 from the generated stream of hydrogen H2, a compressor, connected to the unit for processing the hydrogen H2, for compressing the hydrogen H2, and a chemical reactor, connected to the compressor, for producing a synthesis gas consisting of hydrogen H2 and carbon dioxide CO2 that can be added. An oxy-fuel combustion system to which non-condensable off-gases from the chemical reactor and oxygen O2 from the electrolyzer can be supplied, and carbon dioxide CO2 generated during the combustion of the off-gases in the oxy-fuel combustion system can be returned to the stream of hydrogen H2 downstream of the electrolyzer via a return line.

A method and system for producing liquid air wherein liquid refrigerant is cycled between two core tanks maintained at a temperature sufficient to liquify compressed air passed through condensing tubing in the interior of the core tanks. Liquid refrigerant is cycled by alternating high pressure gas from a high pressure tank to one of the core tanks, which forces liquid refrigerant from this tank through an expansion device to expand a portion of the liquid refrigerant to absorb heat in the other core tank, the resulting refrigerant gas being driven into a low pressure tank. A compression device transfers the refrigerant gas from the low pressure tank to the high pressure tank and maintains the pressure in the high pressure tank. Connections between the low and high pressure tanks and the core tanks are reversed with each cycle.

A hydrogen plant for producing hydrogen, including: a reforming reactor system including a first catalyst bed including an electrically conductive material and a catalytically active material, a heat insulation layer between the first catalyst bed and the pressure shell, and at least two conductors electrically connected to the electrically conductive material and to an electrical power supply placed outside the pressure shell, wherein the electrical power supply is dimensioned to heat at least part of the first catalyst bed to a temperature of at least 500° C. by passing an electrical current through the electrically conductive material, where the pressure shell has a design pressure of between 5 and 200 bar; a water gas shift unit downstream the reforming reactor system; and a gas separation unit downstream the water gas shift unit. A process for producing hydrogen from a feed gas including hydrocarbons.

In a process for the separation of a mixture containing hydrogen and carbon monoxide to produce gaseous hydrogen, the mixture is cooled down to a temperature below −180° C. and then separated at a temperature below −100° C. to produce a gas enriched in hydrogen and a fluid enriched in carbon monoxide, at least a part of the gas enriched in hydrogen is sent to a pressure swing adsorption separation apparatus operating at a temperature above 0° C. to produce a gas rich in hydrogen at a pressure of at least 20 bars, and at least a part of the gas rich in hydrogen is cooled in the heat exchanger down to a temperature below −100° C., reduced in pressure in a turbine down to a pressure of at least 8 bars and reheated in the heat exchanger to constitute a product rich in hydrogen at a pressure of at least 8 bars.

A method to recover olefins and C.sub.2.sup.+ fractions from refineries gas streams. The traditional recovery methods employed at refineries are absorption with solvents and cryogenic technology using compression and expansion aided by external refrigeration systems. In contrast to known methods, there is provided first a pre-cooling heat exchanger on a feed line feeding the gas stream to a in-line mixer, secondly by injecting and mixing a stream of LNG to condense the C.sub.2.sup.+ fractions upstream of the fractionator. The temperature of the gas stream entering the fractionator is monitored downstream of the in-line mixer. A LNG stream is temperature controlled to flow through the injection inlet and mix with the feed gas at a temperature which results in the condensation of the C.sub.2.sup.+ fractions before entering the fractionator. A LNG reflux stream is temperature controlled to maintain fractionator overhead temperature. The fractionator bottoms temperature is controlled by a circulating reboiler stream.

A hydrocarbon is reacted with water in the presence of a catalyst to form hydrogen, carbon monoxide, and carbon dioxide. Hydrogen is selectively allowed to pass through a hydrogen separation membrane to a permeate side of a reactor, while water and carbon-containing compounds remain in a retentate side of the reactor. An outlet stream is flowed from the retentate side to a heat exchanger. The outlet stream is cooled to form a cooled stream. The cooled stream is separated into a liquid phase and a vapor phase. The liquid phase is flowed to the heat exchanger and heated to form steam. The vapor phase is cooled to form condensed water and a first offgas stream. The first offgas stream is cooled to form condensed carbon dioxide and a second offgas stream. The steam and the second offgas stream are recycled to the reactor.