Novel methods for pretreating a rare-gas-containing stream exiting an etch chamber followed by recovering the rare gas from the pre-treated, rare-gas containing stream are disclosed. More particularly, the invention relates to the pretreatment and recovery of a rare gas, such as xenon or krypton, from a nitrogen-based exhaust stream with specific gaseous impurities generated during an etch process that is performed as part of a semiconductor fabrication process.

Cavitand compositions that comprise void spaces are disclosed. The void spaces may be empty, which means that voids are free of guest molecules or atoms, or the void spaces may comprise guest molecules or atoms that are normally in their gas phase at standard temperature and pressure. These cavitands may be useful for industrial applications, such as the separation or storage of gasses. Novel cavitand compounds are also disclosed.

The invention relates to a method (200-400) for extracting pure helium using a first membrane separation stage (1), a second membrane separation stage (2), and a third membrane separation stage (3), in which a first helium-containing feed mixture is supplied to the first membrane separation stage (1), a second helium-containing feed mixture is supplied to the second membrane separation stage (2), and a third helium-containing feed mixture is supplied to the third membrane separation stage (3), and in which a first permeate and a first retentate are formed in the first membrane separation stage (1), a second permeate and a second retentate are formed in the second membrane separation stage (2), and a third permeate and a third retentate are formed in the third membrane separation stage (3). According to the invention, the first feed mixture is formed using at least one portion of a helium-containing starting mixture, the second feed mixture is formed using at least one portion of the first permeate, the third feed mixture is formed using at least one portion of the second retentate, the second permeate is at least partially processed by pressure-swing adsorption in order to obtain the pure helium and a remaining mixture, and at least one portion of the third permeate and/or at least one portion of the third retentate is guided back into the method (200). The invention also relates to a corresponding system.

The present invention provides a composite body having, on a porous substrate and in the interstices of the substrate that includes fibers, preferably of an electrically nonconductive material, a porous layer (1) composed of oxide particles bonded to one another and partly to the substrate that include at least one oxide selected from oxides of the elements Al, Zr, Ti and Si, preferably selected from Al.sub.2O.sub.3, ZrO.sub.2, TiO.sub.2 and SiO.sub.2, and having, at least on one side, a further porous layer (2) including oxide particles bonded to one another and partly to layer (1) that include at least one oxide selected from oxides of the elements Al, Zr, Ti and Si, preferably selected from Al.sub.2O.sub.3, ZrO.sub.2, TiO.sub.2 and SiO.sub.2, where the oxide particles present in layer (1) have a greater median particle size than the oxide particles present in layer (2), which is characterized in that the median particle size (d.sub.50) of the oxide particles in layer (1) is from 0.5 to 4 μm and the median particle size (d.sub.50) of the oxide particles in layer (2) is from 0.015 to 0.15 μm, preferably 0.04 to 0.06 μm, a process for producing corresponding composite bodies and for the use thereof, especially in gas separation.

Novel methods for pretreating a rare-gas-containing stream exiting an etch chamber followed by recovering the rare gas from the pre-treated, rare-gas containing stream are disclosed. More particularly, the invention relates to the pretreatment and recovery of a rare gas, such as xenon or krypton, from a nitrogen-based exhaust stream with specific gaseous impurities generated during an etch process that is performed as part of a semiconductor fabrication process.

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.

Novel methods for pretreating a rare-gas-containing stream exiting an etch chamber followed by recovering the rare gas from the pre-treated, rare-gas containing stream are disclosed. More particularly, the invention relates to the pretreatment and recovery of a rare gas, such as xenon or krypton, from a nitrogen-based exhaust stream with specific gaseous impurities generated during an etch process that is performed as part of a semiconductor fabrication process.

A system and method for flexible production of argon from a cryogenic air separation unit is provided. The cryogenic air separation unit is capable of operating in a ‘no-argon’ or ‘low-argon’ mode when argon demand is low or non-existent and then switching to operating in a ‘high-argon’ mode when argon is needed. The recovery of the argon products from the air separation unit is adjusted by varying the percentages of dirty shelf nitrogen and clean shelf nitrogen in the reflux stream directed to the lower pressure column. The cryogenic air separation unit and associated method also provides an efficient argon production/rejection process that minimizes the power consumption when the cryogenic air separation unit is operating in a ‘no-argon’ or ‘low-argon’ mode yet maintains the capability to produce higher volumes of argon products at full design capacity to meet argon product demands.

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.