The invention provides a process for producing a fermentable gas stream from a gas source that contains one or more constituent which may be harmful to the fermentation process. To produce the fermentable gas stream, the gas stream is passed through a specifically ordered series of removal modules. The removal modules remove and/or convert various constituents found in the gas stream which may have harmful effects on downstream removal modules and/or inhibitory effects on downstream gas fermenting microorganisms. At least a portion of the fermentable gas stream is preferably capable of being passed to a bioreactor, which contains gas fermenting microorganisms, without inhibiting the fermentation process.

The invention relates to a process for the recovery and recycling of the iodine from aqueous solutions comprising iodine-comprising aromatic compounds in which the iodine contained in said aromatic compounds is directly converted into molecular iodine at a pH lower than 1, in the absence of a catalyst.

A combined plant for cryogenic separation and liquefaction of methane and carbon dioxide in a biogas stream, including a mixing means, a compressor, a first exchanger, a distillation column, a second exchanger, a separating means, an expanding means, and a separator vessel. Wherein the mixing means is configured such that the recycle gas is the overhead vapour stream, and the first exchanger and the expanding means are combined.

A combined plant for cryogenic separation and liquefaction of methane and carbon dioxide in a biogas stream, including a mixing means, a compressor, a first exchanger, a distillation column, a second exchanger, a separating means, an expanding means, and a separator vessel. Wherein, the mixing means is configured such that the recycle gas is the overhead vapour stream, and the first exchanger and the expanding means are combined.

A method for recovering helium from a feed gas mixture comprising helium, carbon dioxide and at least one of methane and nitrogen, and wherein at least a part of the feed gas mixture is subjected to a separation sequence including a membrane-based separation and an adsorption-based separation forming a helium product, wherein the the membrane based separation is performed using a first membrane separation step and a second membrane separation step, the membrane based separation and the separation sequence includes no further membrane separation steps, the adsorption based separation is performed using a pressure swing adsorption step, at least a part of the feed gas mixture is subjected to the first membrane separation step forming a first retentate and a first permeate. A corresponding arrangement is also provided.

The present invention relates to an adsorption process for xenon recovery from a cryogenic liquid or gas stream wherein a bed of adsorbent is contacted with a xenon-containing liquid or gas stream selectively adsorbing the xenon from said stream. The adsorption bed is operated to at least near full breakthrough with xenon to enable a deep rejection of other stream components, prior to regeneration using the temperature swing method. After the stripping step, the xenon adsorbent bed is drained to clear out the liquid residue left in the nonselective void space and the xenon molecules in those void spaces is recycled upstream to the ASU distillation column for increasing xenon recovery. The xenon adsorbent bed is optionally purged with oxygen, followed by purging with gaseous argon at cryogenic temperature (≤160 K) to displace the oxygen co-adsorbed on the AgX adsorbent due to higher selectivity of argon over oxygen on the AgX adsorbent. By the end of this step, the xenon adsorbent bed is filled with argon and xenon. Then the entire adsorbent bed is heated indirectly without utilizing any of the purge gas for direct heating. Operating the adsorption bed to near full breakthrough with xenon and displacing the adsorbed oxygen and other residues with argon, prior to regeneration, along with indirect heating of the bed, enables production of a high purity product ≥40 vol % xenon from the adsorption bed and further enables safely heating without any purge gas and ease for downstream product collection, even in cases where hydrocarbons are co-present in the feed stream.

The invention provides a process for producing a fermentable gas stream from a gas source that contains one or more constituent which may be harmful to the fermentation process. To produce the fermentable gas stream, the gas stream is passed through a specifically ordered series of removal modules. The removal modules remove and/or convert various constituents found in the gas stream which may have harmful effects on downstream removal modules and/or inhibitory effects on downstream gas fermenting microorganisms. At least a portion of the fermentable gas stream is preferably capable of being passed to a bioreactor, which contains gas fermenting microorganisms, without inhibiting the fermentation process.

A method of obtaining helium from a helium-containing feed gas. Helium-containing feed gas is fed to a prepurifying unit that uses a pressure swing adsorption process to remove undesirable components from the helium-containing feed gas and obtain a prepurified feed gas. The prepurified feed gas is fed to a membrane unit connected downstream of the prepurifying unit and that has at least one membrane more readily permeable to helium than to at least one further component present in the prepurified feed gas. A pressurized low-helium retentate stream that has not passed through the membrane is fed to the prepurifying unit. The pressurized low-helium retentate is used to displace helium-rich gas from an adsorber that is to be regenerated into an already regenerated adsorber.

A separation membrane structure comprises a porous suppor, and a separation membrane formed on the porous support. The separation membrane has an average pore diameter of greater than or equal to 0.32 nm and less than or equal to 0.44 nm. The separation membrane includes addition of at least one of a metal cation or a metal complex that tends to adsorb nitrogen in comparison to methane.

The present invention relates to a process for purification of a carbon dioxide feedstock, for example from a production well, which comprises carbon dioxide and gaseous and liquid C.sub.1+ hydrocarbons. Specifically, a carbon dioxide feedstream is passed through one or more separation unit wherein each separation unit removes one or more C.sub.1+ hydrocarbon from the carbon dioxide feedstream to provide a richer carbon dioxide gas stream. The process comprises one or more separation unit which employs an adsorption media and has an adsorption step and a media regeneration step wherein the regeneration step may be operated as a batch process, a semi-continuous process, or a continuous process. One embodiment of this method provides for the use of a different regenerable adsorbent media in two or more separation units.