Abstract: The present invention describes an analysis device and a method associated with this device, said device comprising an analysis cell (8) containing an optrode (10), receiving an input laser signal and sending an output signal to the Raman spectrometer, and said method using two analysis routes: an analysis route 1 connected to the internal circulation current passing from adsorber B to adsorber A, and an analysis route 2 connected to the distilled raffinate originating from distillation column C.

Abstract: In order to provide a technique for enriching a combustible gas that allows enrichment of the combustible gas to a higher concentration in an efficient manner with minimization of loss of a source material, there are provided an adsorption tower charged with an adsorbent, a feeding/discharging means for feeding a source gas containing a combustible gas and air, a collecting means for desorbing the combustible gas adsorbed to the adsorbent and collecting the desorbed gas, a controlling means for sequentially effecting a combustible gas adsorption process and a combustible gas desorption process, a detecting means for detecting the concentration of the combustible gas in the source gas, and an operation condition setting section for varying an adsorption completion timing for the controlling means to complete the adsorption process, based on the combustible gas concentration detected by the detecting means.

Abstract: A combustible gas enrichment system includes an adsorption unit charged therein with an adsorbent for selectively adsorbing a combustible gas, a source gas feeding means capable of feeding source gas containing the combustible gas into the adsorption unit from the outside, a suctioning means capable of suctioning the gas from the inside of the adsorption unit and a controlling means for executing an adsorption process for feeding the source gas into the adsorption unit for adsorption of the combustible gas to the adsorbent and a desorption process for desorbing the combustible gas from the adsorbent under the suction force of the suctioning means after the adsorption process and taking the desorbed combustible gas to the outside. The controlling means operates the suctioning means such that the suction force of the suctioning means when no desorption process is effected is smaller than the suction force when the desorption process is effected.

Abstract: A process of producing PX comprising providing a C8+ feedstock, the C8+ feedstock has C8 hydrocarbons and C9+ hydrocarbons, to a crystallization unit under crystallization conditions to produce a PX enriched stream having a PX concentration of at least 99.5 wt % based on the weight of the PX enriched stream, wherein the C8+ feedstock has a PX concentration of at least 70 wt % based on total weight of xylenes in the C8+ feedstock, which the C8+ feedstock having a C9+ hydrocarbons concentration in a range from 1 wppm to 10 wt % based on the total weight of the C8+ feedstock.

Abstract: The invention is directed to a process of contacting at least one zeolite, selected from the MWW family of zeolites, with an aromatic hydrocarbon stream in a system comprising at least one reactor containing the at least one zeolite, wherein the conditions in the reactor are adjusted in response to at least one measurement of the system so as to preferentially increase oxygenate removal or to preferentially increase olefin removal.

Abstract: Embodiments of simulated moving bed systems for separating a preferentially adsorbed component from a feed stream and processes for determining a pump-around profile of the simulated moving bed systems are provided. The process comprises the steps of rotating a rotary valve to a first valve position to direct the feed stream to a first adsorbent sub-bed. An intermediate stream between two adsorbent sub-beds in direct fluid communication with each other is irradiated with laser light that is directed from a probe of a Raman system positioned for inline sampling of the intermediate stream. Scattered light from the irradiated intermediate stream is collected with the probe. A spectrum of the scattered light is generated with the Raman system to determine concentrations of the preferentially adsorbed component and one or more other components in the intermediate stream.

Abstract: The invention relates to a process for the regeneration of a copper-, zinc- and zirconium oxide-comprising adsorption composition after use thereof for the adsorptive removal of carbon monoxide from substance streams comprising carbon monoxide and at least one olefin, in which the adsorption composition is heated to a temperature in the range from 160 to 400° C. and a regeneration gas is passed through the adsorption composition, wherein the regeneration gas comprises 1000 to 3000 ppm of oxygen in an inert carrier gas.

Abstract: A process to reduce flush circulation rates in an adsorption separation system is presented. The flush stream is used to improve the capacity of the simulated moving bed system by flushing the contents of the transfer lines containing raffinate material back into the adsorbent column. The flush stream is a material that is used to flush the head chambers in the column, or from the rotary valve flush dome sealant.

Abstract: There is provided a closed loop purity and recovery control system and process for operating a xylene purification system such as a Parex unit.

Abstract: Embodiments of simulated moving bed systems for separating a preferentially adsorbed component from a feed stream and processes for determining a pump-around profile of the simulated moving bed systems are provided. The process comprises the steps of rotating a rotary valve to a first valve position to direct the feed stream to a first adsorbent sub-bed. An intermediate stream between two adsorbent sub-beds in direct fluid communication with each other is irradiated with laser light that is directed from a probe of a Raman system positioned for inline sampling of the intermediate stream. Scattered light from the irradiated intermediate stream is collected with the probe. A spectrum of the scattered light is generated with the Raman system to determine concentrations of the preferentially adsorbed component and one or more other components in the intermediate stream.

Abstract: Disclosed is a method for separating aromatic compounds using a simulated moving bed adsorptive chromatography, comprising a sulfolan process that is a non-aromatic compound removing process, a benzene/toluene fractionation process, an aromatic compound fractionation process, a selective toluene disproportionation process, a transalkylation process, a simulated moving bed para-xylene separation process and a xylene isomerization process, wherein the method is characterized by further comprising a simulated moving bed xylene mixture pre-treatment process and an additional xylene isomerization process. The separation method of aromatic compounds according to the present invention can make significant improvement in para-xylene and benzene production in the overall process, as compared to the conventional aromatic compound separation process.

Abstract: The present invention describes a novel configuration for simulated moving bed separation processes characterized by using two adsorbers each containing 12 beds, these two adsorbers functioning in parallel. This novel configuration can be used to optimize para-xylene production.

Abstract: Processes and apparatuses are provided for producing a normal paraffin product or a substantially linear paraffin product from a feed including normal hydrocarbons, non-normal hydrocarbons, and contaminants. The contaminants are extracted from the feed through contact with an ionic liquid stream to form a clean stream of hydrocarbons. The desired hydrocarbons are selectively adsorbed from the clean stream of hydrocarbons with a molecular sieve to remove the desired hydrocarbons from the non-desired hydrocarbons. A desorbent recovers the desired hydrocarbons from the molecular sieve. Then the desired hydrocarbons are separated from the desorbent to yield the normal paraffin product.

Abstract: Purge fluid from a vessel head in an adsorption process is distributed to recovery processes according to the purity of product contained in the fluid. Extract-rich fluid thus is routed directly to recovery of the extract product. Distribution preferably is determined by internal positioning of feed, desorbent and product streams in the adsorption vessel.

Abstract: There is provided a closed loop purity and recovery control system and process for operating a xylene purification system such as a Parex unit.

Abstract: The invention relates to a process for the regeneration of a copper-, zinc- and zirconium oxide-comprising adsorption composition after use thereof for the adsorptive removal of carbon monoxide from substance streams comprising carbon monoxide and at least one olefin, in which the adsorption composition is heated to a temperature in the range from 160 to 400° C. and a regeneration gas is passed through the adsorption composition, wherein the regeneration gas comprises 1000 to 3000 ppm of oxygen in an inert carrier gas.

Abstract: A method for treating a hydrocarbon solvent, the method comprising continuously introducing a hydrocarbon solvent to a liquid medium containing hydrogen ions; allowing the hydrocarbon solvent to be in contact with the liquid medium for at least 1 minute; continuously removing hydrocarbon solvent from the liquid medium to provide a treated hydrocarbon solvent stream.

Abstract: The invention provides a process of polymerizing ethylene and at least one ?-olefin, said process comprises polymerizing the ethylene and the at least one ?-olefin in the presence of 5-ethylidene-2-norbornene, which comprises low levels of impurities, as determined by the absorbances at the following wavelengths: 320 nm and 343 nm. The invention also provides a method of increasing the catalysts efficiency, and a method of determining the expected catalyst efficiency, each in a polymerization of ethylene and at least one ?-olefin in the presence of the 5-ethylidene-2-norbornene, which comprises low levels of impurities, as determined by the absorbances at the above wavelengths. The invention further provides a method of purifying 5-ethylidene-2-norbornene to form a purified 5-ethylidene-2-norbornene, which comprises low levels of impurities, as determined by the absorbances of the above wavelengths.

Abstract: Mixing small amounts of an inorganic halide, such as NaCl, to basic copper carbonate followed by calcination at a temperature sufficient to decompose the carbonate results in a significant improvement in resistance to reduction of the resulting copper oxide. The introduction of the halide can be also achieved during the precipitation of the carbonate precursor. These reduction resistant copper oxides can be in the form of composites with alumina and are especially useful for purification of gas or liquid streams containing hydrogen or other reducing agents. These reduction resistant copper oxides can function at near ambient temperatures.

Abstract: High-purity 2,6-dimethylnaphthalene is prepared by (1) subjecting a dimethylnaphthalene isomer mixture rich in 1,5-dimethylnaphthalene, high boiling point materials, unreacted 1,5-dimethyltetralin, and low boiling point materials, which are produced from a dehydrogenation reaction of 1,5-dimethyltetralin, to separation, using a distillation column; subjecting the dimethylnaphthalene mixture separated by the distillation column to liquid state isomerization in the presence of an isomerization catalyst; (3) a first crystallization (melt crystallization process) by cooling the product of liquid state isomerization with a refrigerant without a solvent to form crystals; and (4) a second crystallization (solution crystallization process) of mixing the crystals of the first crystallization step with a solvent to form crystals.

Abstract: The invention concerns a process for separating meta-xylene from a hydrocarbon feed comprising isomers containing 8 carbon atoms, comprising: a step for bringing said feed into contact with a faujasite type zeolite adsorbant, the percentage of water in the adsorbant being in the range 0 to 8% by weight and the adsorption temperature being from 25° C. to 250° C.; a desorption step employing a solvent selected from tetraline and its alkylated derivatives; a step for separating meta-xylene from the desorbant.

Abstract: The present invention relates to a process for the removal of sulfur contaminants from a hydrocarbon stream comprising: (a) providing a gaseous hydrocarbon stream having sulfur contaminants, but having less than 10 ppmw of said sulfur contaminants as thiophenes, to a bed of adsorbent material, said material having at least one Group VIII metal compound with at least one Group VI, IA, IIA, IB metal compound on an inorganic metal oxide support material, without substantial added hydrogen, to absorb said contaminants; (b) periodically stopping said providing of said gaseous hydrocarbon feed stream of (a); (c) then, regenerating said adsorbent bed by introducing at least one regenerant, in any order, in the place of said stream; and, (d) continuing to alternate (a) and (b) plus (c) as needed.

Abstract: Methods and apparatus for the purification and distribution of acetylene. Acetylene is removed from an acetylene storage device, and provided to a purifier where solvent is removed. The purified acetylene is then provided to a semiconductor processing tool.

Abstract: The present invention provides processes for removing CO2 from an effluent stream derived from an oxygenate to olefins reaction system. In one embodiment, the invention comprises contacting the effluent stream with a first CO2 removal medium in a first CO2 removal zone under conditions effective to remove a first portion of the CO2 from the effluent stream and form a first CO2 depleted stream. The first CO2 depleted stream is contacted with a second CO2 removal medium in a second CO2 removal zone under conditions effective to remove a second portion of the CO2 from the first CO2 depleted stream and form a second CO2 depleted stream comprising less than about 0.5 vppm CO2.

Abstract: This invention is drawn to a process for recovering detergent-range olefins from a feed stream by adsorption. The adsorbent and desorbent are selected to enable olefins with a range of carbon numbers to be recovered simultaneously in light of differing adsorbent retention characteristics.

Abstract: The present invention is related to a method for kinetically separating a light hydrocarbon mixture comprising at least two components by preferentially adsorbing a first component on a zeolite adsorbent comprising 8-member rings of tetrahedra as the pore opening controlling hydrocarbon diffusion and alkali metal cations balancing a framework charge, wherein a second component is not preferentially adsorbed. The novel process comprises contacting the light hydrocarbon mixture with a zeolite adsorbent having a SiO2/Al2O3 ratio greater than about 50 and less than 200 and further having a diffusion rate at least 50 times greater for the first component as compared to the second component, and then recovering at least one of the first component or the second component.

Abstract: Method of optimizing the operation of a unit intended for separation of the components of a feed (xylenes) by simulated countercurrent in hybrid operating mode. The method allows to minimize the solvent ratio and to maximize the capacity of the separation unit while keeping product specifications such as purity and yield constant. It has been verified that these two objectives cannot be reached simultaneously and it is recommended to operate with a minimum solvent ratio while guaranteeing a high capacity compatible with stable operation of the separation unit. These optimization objectives are reached while keeping good stability around the optimum point thus defined, by using a known operation control process such as the one described in patent EP-875,268 for example.

Abstract: Small particle size SAPO-34 is obtained by using a tetraalkyl orthosilicate as the silicon source.

Abstract: A process for treating nitrogen-containing, substantially paraffinic product derived from a Fischer-Tropsch process. The substantially paraffinic product is purified in a purification process to lower the concentration of oxygen, nitrogen, and other impurities. The nitrogen content of the purified product is monitored, and the conditions of the purification step are adjusted to increase nitrogen removal if the nitrogen content of the purified product exceeds a preselected value.

Abstract: The present invention provides means which can be used for maintaining the freshness of or controlling maturation of plants or perishables such as fruits, vegetables, and flowers and which is safe to the human body. According to the present invention, a method for maintaining the freshness of or conversely controlling the maturation of plants or perishables by controlling the concentration of ethylene gas by use of an ethylene gas adsorbent containing an alcohol extract solution of raw bamboo and a filter having held thereon the alcohol extract solution of raw bamboo. Also, according to the present invention, there is provided an ethylene gas sensor including a quartz crystal microbalance having coated thereon the alcohol extract solution of raw bamboo.

Abstract: Small particle size SAPO-34 is obtained by using a tetraalkyl orthosilicate as the silicon source.

Abstract: A process for treating nitrogen-containing, substantially paraffinic product derived from a Fischer-Tropsch process. The substantially paraffinic product is purified in a purification process to lower the concentration of oxygen, nitrogen, and other impurities. The nitrogen content of the purified product is monitored, and the conditions of the purification step are adjusted to increase nitrogen removal if the nitrogen content of the purified product exceeds a preselected value.

Abstract: An improved process for recovering hydrocarbons from an inlet inert gas-hydrocarbon vapor mixture is provided. The inlet mixture is caused to flow through a first bed of solid adsorbent whereby hydrocarbon vapors are adsorbed on the bed and a residue gas stream comprised of substantially hydrocarbon-free inert gas is produced. The hydrocarbon-free inert gas is vented and a second bed of solid adsorbent having hydrocarbon vapors adsorbed thereon is evacuated with an ejector operated by a motive liquid. A major portion of the hydrocarbon vapors is desorbed from the bed and an inert gas and hydrocarbon-rich vapor mixture commingled with the motive liquid is produced. The inert gas and hydrocarbon-rich vapor mixture is separated from the motive liquid and conducted to a point of additional processing or disposal.

Abstract: In a method for separating at least one alkylnaphthalene from a stock mixture containing at least two alkylnaphthalenes selected from the group consisting of monoalkylnaphthalenes and dialkylnaphthalenes, a column packed with an optically active chromatographic packing is used for separation. The method can effectively separate a variety of alkylnaphthalenes from a mixture thereof.

Abstract: The capacity of a simulated moving bed adsorptive separation process is increased by flushing the contents of the transfer line just previously used to remove the raffinate stream from the adsorbent chamber back into the adsorbent chamber. This step is performed immediately upstream of the point of raffinate withdrawal. Preferably the feed stream to the process is used as the flushing liquid. This flush step eliminates the passage of a quantity of the raffinate material into the adsorbent chamber when the process conduit is subsequently used to charge the feed stream to the adsorbent chamber.

Abstract: Method for controlling with precision a permanent in-line process for separating constituents of a mixture in a simulated moving bed separation system from concentration and flow rate measurements.The system comprises a set of columns forming a closed loop comprising several zones between fluid injection and draw-off points. Control of the process (linear or nonlinear) is performed from a knowledge model and from a certain number of operating variables at a plurality of measuring points along the loop (concentrations and flow rates for example) and characteristic measurements of the fluids injected and drawn off. Ratios respectively indicative of the ratio, in each of the different zones, between the fluid flow rates and the simulated adsorbent material flow rates, are determined from actual values of controlled variables depending on the measured operating variables (purity of the constituents, system yield, etc.).

Abstract: A process for separating a product from a multicomponent feedstream to an adsorption apparatus or system. The apparatus or system may comprise a moving-bed or a simulated moving-bed adsorption means. The product comprises at least one organic compound, such as an aryl compound with alkyl substitutes. The conduits used to supply the feedstream to the apparatus or system are flushed with media of multiple grades. Amounts of the media are sufficient to fill the conduits. The process achieves improvements in the efficiency of adsorption separation, the capacity of adsorption apparatus and systems, and the purity of product attainable by adsorption process.

Abstract: A process of continuously controlling at least one characteristic of a simulated moving bed para-xylene separation process has been developed. The characteristics controlled may be the purity or the recovery of the para-xylene. The process involves measuring the concentrations of the para-xylene, meta-xylene, ortho-xylene, and ethylbenzene in the pumparound or pusharound stream, calculating the value of the characteristic, and making required adjustments to operating variables according to an algorithm which relates changes in the value of the characteristic to the changes in the concentrations of the components resulting from changes in the operating variables. The process is unique in that the necessary quantity of data to control the separation is rapidly generated, thereby providing increased efficiency, precision, and accuracy.

Abstract: A process of continuously controlling at least one characteristic of a simulated moving adsorbent bed separation process has been developed. The characteristics controlled may be the purity or the recovery of the component of interest. The process involves measuring the concentration of the components in the pumparound or pusharound stream, calculating the value of the characteristic, and making required adjustments to operating variables according to an algorithm which relates changes in the value of the characteristic to the changes in the concentrations of the components resulting from changes in the operating variables. The process is unique in that the necessary quantity of data to control the separation is rapidly generated, thereby providing increased efficiency, precision and accuracy.

Abstract: Disclosed is a process for the production of an alkylene oxide in which an alkene, and an oxygen containing gas are reacted in the presence of a flame suppressor under conditions of low alkene conversion and high alkylene oxide selectivity in which unreacted alkene is recycled to the reactor and there is efficient removal of nitrogen and carbon dioxide.

Abstract: A process for purifying linear paraffins in which a hydrocarbon feedstream containing linear paraffins contaminated with aromatics, sulfur-, nitrogen-, and oxygen-containing compounds, and color bodies, and also containing up to about 5 wt % desorbent from effluent recycle, is contacted with a solid adsorbent such as a NaX zeolite or zeolite MgY; after adsorption the adsorbent is desorbed with an alkyl-substituted aromatic desorbent, such as toluene. As the adsorent bed is being desorbed, the initial effluent from the adsorption cycle will contain levels of desorbent and may be recycled to the hydrocarbon feedstream. Previous to the removal of impurities from the adsorbent by desorption, the desorbent displaces interstitial linear paraffins which are also recycled to the hydrocarbon feedstream.

Abstract: A process for purifying linear paraffins in which a hydrocarbon stream containing linear paraffins contaminated with aromatics, sulfur-, nitrogen-, and oxygen-containing compounds, and color bodies, but essentially free of olefins, is contacted with a solid absorbent such as a NaX zeolite or zeolite MgY. After adsorption the adsorbent is desorbed with an alkyl- substituted aromatic desorbent, such as tuluene. The initial effluent from the adsorb cycle, which will contain a high concentration of residual desorbent, is recycled to a desorbent recovery system. The level of desorbent in the adsorber effluent is monitored on a real time basis until the desorbent level of the adsorber effluent declines from a plateau level, i.e., a 100% plateau level, that correlates with the level of impurities, particularly the aromatic impurities in the feed, which is an indication of aromatics breakthrough, thereby signaling the need to switch the adsorbent beds.

Abstract: Processes are disclosed for separating by adsorption lower octane normal and mono-methyl paraffins from hydrocarbon feeds containing normal, mono-methyl and more highly branched paraffin fractions in the pentane and hexane carbon range. Adsorbents capable of adsorbing mono-methyl paraffins are used in combination with adsorbents capable of adsorbing normal paraffins but not mono-methyl paraffins. Isopentane, although adsorbed along with the mono-methyl hexane paraffins, is preferentially desorbed and eluted from the adsorber bed and recovered as an adsorption effluent along with di-methyl branched hexane paraffins. Isomerization processes are disclosed for isomerizing the normal and mono-methyl paraffins to produce higher octane isopentane and more highly branched paraffins.

Abstract: Processes are disclosed for separating by adsorption lower octane normal and mono-methyl paraffins from hydrocarbon feeds containing normal, mono-methyl and more highly branched paraffin fractions in the pentane and hexane carbon range. Adsorbents capable of adsorbing mono-methyl paraffins but not di-methyl branched paraffins are employed to adsorb normal and mono-methyl branched parafins. Isopentane, although adsorbed along with the mono-methyl hexane paraffins, is preferentially adsorbed and eluted from the adsorber bed and recovered as an adsorption effluent along with di-methyl branched hexane paraffin. In one aspect of the invention adsorbents capable of adsorbing normal paraffins but not mono-methyl paraffins are additionally employed to pretreat the feeds to adsorb normal paraffins. Isomerization processes are disclosed for isomerizing the normal and mono-methyl paraffins to produce higher-octane isopentane and more highly branched paraffins.

Abstract: A combination isomerization and liquid phase adsorptive separation process is given increased efficiency and cost effectiveness while also improving the product quality by eliminating the columns for the separation of desorbent material from extract and raffinate streams. In this arrangement a C.sub.5 + naphtha stream is split into a heavy hydrocarbon stream comprising normal hexane and higher boiling hydrocarbons and an isomerization zone feedstream comprising isohexane and lower boiling hydrocarbons. The heavy hydrocarbon stream goes directly to a deisohexanizer column. The isomerization zone feedstream is combined with an excess desorbent stream and the extract stream from an adsorptive separation section to form a combined feed. Hydrocarbons in the combined feed are isomerized and after stabilization pass directly into the adsorption section.

Abstract: The present invention is a concentration swing adsorption process for separating a liquid phase feedstock comprising a more adsorbable component (A) and a less adsorbable component (B) with respect to an adsorbent. The process is operated in a system comprising a single or a plurality of adsorption columns containing the adsorbent which are operated in cycle in a predetermined sequence. The following operational steps are performed in the order recited in each of the adsorption columns in its turn. Feedstock is passed through the adsorbent and the more adsorbable component (A) is selectively adsorbed while a stream enriched in component (B) is discharged from the adsorption column. The adsorbent is rinsed in a direction co-current to the feedstock with the more adsorbable component (A) whereby the less adsorbable component (B) is displaced from the adsorbent and a stream comprising a mixture of the more adsorbable component (A) and the less adsorbable component (B) is withdrawn from the adsorption column.

Abstract: This invention relates to processes for separating by adsorption lower octane normal and mono-methyl paraffins from hydrocarbon feeds containing normal, mono-methyl and more highly branched paraffin fractions and isomerizing the normal and mono-methyl paraffins to produce higher octane isopentane and more highly branched paraffins. Adsorbents capable of adsorbing both normal and mono-methyl paraffins are used either alone or in combination with adsorbents capable of adsorbing normal paraffins but not mono-methyl paraffins. Isopentane, although adsorbed along with the mono-methyl paraffins, is preferentially eluted from the adsorber and recovered as an adsorption effluent.

Abstract: This invention relates to a process for increasing the octane of a refinery gasoline pool by segregating components which are increased in value by isomerization from those which are diminished in octane value by isomerization. The preferred feed stream of this process comprises di-branched paraffins, mono-methyl-branched paraffins and normal paraffins from which mono-methyl-branched and normal paraffins are selectively captured by a shape-selective molecular sieve. The preferred separatory shape-selective molecular sieve has a pore size of 5.5.times.5.5 to 4.5.times.4.5A but excluding 4.5.times.4.5A. Mono-methyl-branched paraffins and normal paraffins are removed from the shape-selective molecular sieve and isomerized in an isomerization zone to form di-methyl branched paraffins. An isomerization zone effluent stream is produced comprising unisomerized normal paraffins, mono-methyl-branched paraffins and di-branched paraffins.

Abstract: In a process for the direct oxidation of ethylene to ethylene oxide, ethylene is recovered from normally vented gas by contacting first with an activated carbon adsorbent then by pressure swing adsorption with a zeolitic molecular sieve adsorbent.

Abstract: A method and apparatus for the semi-continuous batch separation of a feed mixture of gaseous products into individual substantially pure products utilizes preferential adsorption in which all the components of a gaseous feed mixture are adsorbed by one or more adsorbers through which the feed mixture of gaseous products are sequentially cycled through the steps of (1) progressive adsorption of adsorbates from the mixture of gaseous products; (2) rectification of the adsorbates and (3) desorption of adsorbates contained in the adsorber with the adsorber being readied for further adsorption. Substantially pure gases are collected at appropriate intervals throughout the sequential cycling.