The invention relates to a process and to a plant for producing methanol from a synthesis gas having a hydrogen deficit. A fresh gas stream from a reformer unit which includes hydrogen and carbon oxides is combined with a hydrogen-containing stream from a hydrogen recovery stage. This affords a synthesis gas stream having a stoichiometry number SN, defined as SN=[n(H.sub.2)?n(CO.sub.2)]/[n(CO)+n(CO.sub.2)], of less than 2.0. The synthesis gas stream is combined with a residual gas stream and the synthesis gas stream and the residual gas stream are passed through a bed of a methanol synthesis catalyst at elevated pressure and elevated temperature to obtain a product stream having methanol and the residual gas stream, and the product stream is cooled to separate methanol from the residual gas stream.

A method for producing a hydrogen-enriched gas, the method including: (A) generating a mixed gas containing hydrogen and oxygen in a reactor that decomposes water into hydrogen and oxygen using sunlight in the presence of a photocatalyst; (B) collecting the mixed gas in a storage tank; (C) supplying the mixed gas in the storage tank to a gas separation device that includes a membrane having an ability to separate hydrogen and oxygen; and (D) separating a hydrogen-enriched gas from the mixed gas in the gas separation device.

A method of purifying a gas composed of a product gas and one or more impurity gases including combining a feed stream with a second stream thereby forming a combined feed stream, introducing the combined feed stream into a pressure swing adsorption device, thereby producing a high purity product gas stream and an off-gas stream, and introducing the off-gas stream into a membrane separation device, thereby producing a gas stream lean in product gas and a permeate stream.

A method of obtaining helium from a process gas. The process gas is at a pressure less than 15 bar to a first membrane separation stage having a first membrane more readily permeable for helium than for at least one other component in the process gas. A first retentate stream is fed to a second membrane separation stage having a second membrane more readily permeable for helium than for at least one other component in the process gas. Helium is separated from a first helium-containing permeate stream using a pressure swing adsorption to obtain a helium-containing product stream. A second helium-containing permeate stream is recycled to the first membrane separation stage. A purge gas from the pressure swing adsorption is also recycled to the first membrane separation stage.

A low carbon-emission hydrogen production process may be achieved by first separating carbon dioxide from a reformer syngas stream, followed by separating the carbon dioxide-depleted syngas stream using a semi-permeable membrane to produce a hydrogen-enriched permeate and a hydrogen-depleted retentate. The hydrogen-enriched permeate is purified to produce a hydrogen product and a hydrogen-depleted tail gas stream. The hydrogen-depleted retentate stream may be recycled to the feed and the hydrogen-depleted tail gas stream may be used as fuel in the reformer burners.

Converting carbon sources that would otherwise be vented to the atmosphere or discarded as waste to one or more products. Carbon sources may be dilute carbon containing streams that are purified to from about 90 vol.-% to about 95 vol.-% carbon compound. In certain aspects, also disclosed are the processes for producing desirable products, such as ethylene, from industrial waste streams.

An input stream of gaseous nitrogen and carbon dioxide is introduced into a first interior volume of a separation vessel that is divided into first and second interior volumes by a separation membrane that includes a metal layer. The metal layer selectively permits movement of nitrogen through the metal layer. An output stream of gaseous nitrogen and carbon dioxide is conveyed out of the first interior volume and into a reaction vessel. The volume fraction of carbon dioxide is greater in the output stream than in the input stream; the volume fraction of nitrogen is reduced in the output stream relative to the input stream. Nitrogen is removed from the second interior volume to maintain a gradient of nitrogen partial pressure across the separation membrane that causes net transport of nitrogen from the first interior volume through the separation membrane into the second interior volume.

The present provides a helium gas separation and recovery process involving cryogenic fractionation process, which comprises cooling a dehydrated high-pressure gas stream while maintain velocity and pressure of the stream; reducing pressure of the dehydrated high-pressure gas stream via a Joule-Thompson's process to obtain a partially liquefied gas stream; and iii) subjecting the partially liquefied gas stream to at least one gas-liquid separation process to obtain at least one liquid stream and a gaseous stream comprising helium, and a residual amount of the gaseous components; recycling the liquid stream obtained in step iii) for use as cooling refrigerant to cool the dehydrated high-pressure gas stream; and purifying the unrefined helium gas stream using pressure swing adsorption (PSA) and/or membrane separation process to obtain a helium product stream having a purity of 98.0 mole % or more.

An input stream of gaseous nitrogen and carbon dioxide is introduced into a first interior volume of a separation vessel that is divided into first and second interior volumes by a separation membrane that includes a metal layer. The metal layer selectively permits movement of nitrogen through the metal layer. An output stream of gaseous nitrogen and carbon dioxide is conveyed out of the first interior volume and into a reaction vessel. The volume fraction of carbon dioxide is greater in the output stream than in the input stream; the volume fraction of nitrogen is reduced in the output stream relative to the input stream. Nitrogen is removed from the second interior volume to maintain a gradient of nitrogen partial pressure across the separation membrane that causes net transport of nitrogen from the first interior volume through the separation membrane into the second interior volume.

The present disclosure provides systems and methods for hydrogen production as well as apparatuses useful in such systems and methods. Hydrogen is produced by steam reforming of a hydrocarbon in a gas heated reformer that is heated using one or more streams comprising combustion products of a fuel in an oxidant, preferably in the presence of a carbon dioxide circulating stream.