Gas permeation process through crosslinked membrane

Abstract

To provide a process for separating an operative material from a gaseous feed material by a membrane including a polymer phase and a liquid phase.SOLUTION: The process comprises, over a first time interval, separating at least a separation fraction of the operative material in response to permeation of the at least a separation fraction of the operative material through the membrane, where the membrane includes crosslinked polymeric material.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to improving the performance of transmission methods. [Background technology]

[0002] Membrane-based separation has proven to be an effective technology for the separation of gases. Some of the mechanisms for promoting the selective permeation of materials through the membrane relate to the binding of carriers dissolved in a solution disposed within the membrane polymer matrix. The carriers can form a reversible complex with at least one component of a given mixture, thereby enhancing transport across the membrane. During operation, the liquid medium within the membrane polymer matrix is ​​consumed, which affects the performance of the membrane separation. Summary of the Invention

[0003] In one aspect, a method is provided for separating an operative material from a gaseous feed by a membrane comprising a polymer phase and a liquid phase, the method comprising the step of separating at least a separated fraction of the operative material in response to permeation of at least the separated fraction of the operative material through the membrane over a first time interval, the membrane comprising a crosslinked polymeric material.

[0004] In another aspect, a method is provided for separating a compound being processed from a gaseous feed by a membrane comprising a polymer phase and a liquid phase, the method comprising fractionating the gaseous feed based on the relative permeabilities of the compounds through the membrane over a first time interval, the membrane comprising a crosslinked polymeric material.

[0005] Preferred embodiments are described below with the aid of the accompanying drawings. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram of one embodiment of an apparatus for carrying out embodiments of the present method. [Diagram 2] FIG. 2 is an example of an association that occurs upon contact of an olefin (ethylene) with a carrier reagent (silver ion). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Detailed Description Unless otherwise stated, as in the examples, all amounts and numerical values ​​used herein are intended to be interpreted as modified by the term "about." Similarly, all compounds or elements specified herein are intended to be non-limiting and exemplary of other compounds or elements that would be commonly considered by one of ordinary skill in the art to be within the same family of compounds or elements, unless otherwise stated.

[0008] The term "associated" and its grammatical variations include any type of interaction, including polar and non-polar interactions through chemical bonds (e.g., covalent bonds, ionic bonds, and hydrogen bonds) and / or van der Waals forces and / or other physical constraints provided by molecular structure, as well as interactions through physical mixing.

[0009] 1, a membrane 30 is provided for effecting separation of at least a fraction of a material to be processed from a gaseous feed material. The gaseous feed material is fed through the membrane 30 to a feed receiving space 10 disposed in mass transfer communication with a permeate receiving space 20.

[0010] In some embodiments, for example, the operative material comprises at least one operative compound. In some of these embodiments, for example, the operative material-derived material comprises at least one operative material-derived compound. Each one of the at least one operative material-derived compound comprises at least a fraction of one or more of the operative compounds.

[0011] In some embodiments, for example, suitable compounds to be treated are olefins, suitable olefins include ethylene, propylene, 1-butene, and 2-butene.

[0012] In some embodiments, for example, the material to be treated is defined by at least one treated compound, where each of the at least one treated compound is an olefin. In some embodiments, for example, the material to be treated is defined by at least one treated compound, where the at least one treated compound is a single treated compound, where the single treated compound is an olefin.

[0013] In some embodiments, for example, suitable olefins are those containing a total of 2 to 8 carbon atoms.

[0014] In some embodiments, for example, the one or more olefins is an alpha olefin.

[0015] The membrane comprises a polymer phase and a liquid phase.

[0016] The polymer phase comprises a crosslinked polymeric material.

[0017] In some embodiments, for example, the liquid phase is dispersed throughout the crosslinked polymeric material.

[0018] In some embodiments, for example, the polymeric material of the polymer phase comprises at least one polymeric compound. In some embodiments, for example, each of the at least one polymeric compound is hydrophilic. In some embodiments, for example, each of the at least one polymeric compound S has a number average molecular weight of 20,000 to 1,000,000.

[0019] In some embodiments, for example, the liquid phase is aqueous.

[0020] In some embodiments, for example, the liquid phase is associated with the polymeric material of the polymer phase.

[0021] In some embodiments, for example, association is effective to fractionate a liquid mixture passing through the membrane. In some embodiments, for example, fractionation is based on differences in permeability through the membrane, such as between compounds within the liquid mixture. In some embodiments, for example, fractionation of a liquid mixture containing two compounds is characterized by a separation factor of at least 2 relative to the faster permeating compound. In some embodiments, for example, fractionation of a liquid mixture containing an olefin and a paraffin is characterized by a separation factor of at least 2 for separation of the olefin from the paraffin, relative to the olefin.

[0022] In some embodiments, for example, the liquid phase is defined by a continuous liquid phase domain, which is encapsulated within the polymer phase.

[0023] In some embodiments, for example, the association is characterized by defining a gel. In some embodiments, for example, the gel comprises a hydrogel.

[0024] In some embodiments, for example, the associations are characterized by swelling the polymer phase.

[0025] In some embodiments, for example, the association comprises a chemical bond (eg, by covalent, ionic, or hydrogen bonding), van der Waals forces, polar interactions, or non-polar interactions, or any combination thereof.

[0026] In some embodiments, for example, the polymeric material comprises a polysaccharide material. In this regard, in some embodiments, for example, the polysaccharide material comprises one or more polysaccharides. Suitable polysaccharides include natural polysaccharides, such as alginic acid, pectinic acid, chondroitin, hyaluronic acid, and xanthan gum; derivatives of natural polysaccharides, such as cellulose, chitin, pullulan, C1-6 esters, their esters, ethers, and alkylcarboxy derivatives, and phosphates of these natural polysaccharides, such as partially methyl esterified alginic acid, carboxymethoxylated alginic acid, phosphorylated alginic acid, and aminated alginic acid, carboxymethylcellulose, cellulose sulfate, cellulose phosphate, salts of anionic cellulose derivatives, such as sulfoethylcellulose, and phosphonoethylcellulose, and semi-synthetic polysaccharides, such as guar gum phosphate and chitin phosphate. Specific examples of polysaccharide membranes include those composed of chitosan and salts of its derivatives, including salts of chitosan, such as N-acetylated chitosan, chitosan phosphate, and carbomethoxylated chitosan. Among these, membranes composed of alginic acid and its salts and derivatives, chitosan and its salts and derivatives, and cellulose and its derivatives are preferred from the viewpoints of their membrane-forming properties, mechanical strength and membrane function, as well as gel formation and swelling properties (tendency to swell when exposed to water).

[0027] In those embodiments in which the membrane comprises a hydrogel, in some of these embodiments, for example, the hydrogel comprises one or more polysaccharides and also comprises one or more other polymeric compounds. In this respect, in some embodiments, for example, the membrane is composed of a major amount (e.g., at least 60% by weight based on the total weight of the membrane) of one or more polysaccharides and a minor amount (e.g., up to 40% by weight based on the total weight of the membrane) of one or more other compatible polymeric compounds, such as polyvinyl alcohol (PVA), or a blend of natural polysaccharides, such as starch and pullulan. In some embodiments, for example, the membrane is composed of grafted ionic polysaccharides obtained by grafting hydrophilic vinyl monomers, such as acrylic acid.

[0028] In some embodiments, for example, the membrane is a facilitated transport membrane. In this regard, in some embodiments, for example, the membrane includes a carrier reagent to facilitate transport of the material through the membrane.

[0029] In those embodiments in which the membrane is an enhanced transfer membrane, in some of these embodiments, for example, the membrane comprises a gel.

[0030] In those embodiments where the membrane is a facilitated transfer membrane, in some embodiments, for example, the carrier reagent is dissolved in the liquid material of the liquid phase. In some embodiments, for example, the carrier reagent comprises at least one metal cation. In some embodiments, for example, the carrier reagent comprises silver ions. In some embodiments, for example, the carrier reagent comprises copper(I) ions. In some embodiments, for example, the carrier reagent comprises silver ions, in which respect the liquid material comprises dissolved silver nitrate and the carrier reagent comprises the silver ions of silver nitrate. In some embodiments, for example, the silver nitrate is dissolved in the liquid material to provide an aqueous solution, which liquid material is part of the liquid phase of the membrane 30 and the aqueous solution comprises dissolved silver nitrate. In some embodiments, for example, the carrier reagent forms a complex or chelate with the polymeric material of the polymeric phase.

[0031] An exemplary polymer phase is crosslinked chitosan, which can be crosslinked in aqueous and non-aqueous phases with a variety of crosslinking agents, such as sulfuric acid, glutaraldehyde, 1,6-hexamethylene diisocyanate, sulfosuccinic acid, epichlorohydrin, 2,4-toluylene diisocyanate, and trimesoyl chloride.

[0032] An exemplary method for cross-linking chitosan is cross-linking with sulfuric acid. In this regard, cross-linking of chitosan is carried out by submerging the membrane in a cross-linking solution containing 0.005 M sulfuric acid in 50% v / v aqueous acetone for 5 minutes. The cross-linked chitosan membrane is then washed with deionized water to remove excess sulfuric acid. Various degrees of cross-linking can be achieved by exposing the chitosan to the cross-linking reaction for periods of time ranging from, for example, 1 to 80 minutes.

[0033] In some embodiments, for example, membrane 30 is supported on a substrate to result in a composite membrane.

[0034] Suitable substrates include films, nonwoven substrates, flat sheets, in plate and frame constructions, in spiral wound constructions, and tubular or hollow fiber substrates.

[0035] Suitable supports also include ultrafiltration and nanofiltration membranes, for example those having a pore size of from 1 to 500 nanometers, such as from 5 to 300 nanometers.

[0036] Suitable substrate materials include polyesters, polysulfones, polyethersulfones, polyimides, polyamides, polycarbonates, polyacrylonitrile, cellulose acetate, and combinations thereof. The support material can also be a microporous ceramic, glass, and / or metal.

[0037] With respect to composite membranes, in some embodiments, for example, the membrane has a thickness of 0.01 to 20 microns, such as 0.5 to 10 microns, or such as 1 to 5 microns, and the substrate material has a thickness of 30 to 200 microns, such as 50 to 150 microns, or such as 80 to 110 microns.

[0038] With respect to composite membranes, in some embodiments, for example, the membrane is applied to a substrate. In some of these embodiments, for example, application is by coating, casting, or lamination.

[0039] With respect to composite membranes, in some embodiments, for example, the layers of the membrane are continuous. In some embodiments, for example, the membrane is discontinuous.

[0040] With respect to composite membranes, in some embodiments, for example, a layer of the membrane extends into the pores of the substrate.

[0041] With respect to composite membranes, the composite membrane can be embedded in any one of several structures, including a flat sheet, a plate and frame, a spiral wound structure, a tubular structure, or a hollow fiber.

[0042] An exemplary method of producing a membrane includes casting a solution of a polymeric material (such as one or more polysaccharides) as a film. In some embodiments, for example, the solution includes less than 5% by weight of the polymeric material based on the total weight of the solution. In some embodiments, for example, the solution includes less than 2% by weight of the polymeric material based on the total weight of the solution. In some embodiments, for example, the solution is an acidic aqueous solution. In some embodiments, the acid is an organic acid, such as an organic acid having a total carbon number of 1-4. In some embodiments, for example, the acid includes acetic acid. In some embodiments, for example, the resulting solution can be cast as a film onto a flat plate to produce a membrane intermediate. Suitable casting surfaces include glass or Teflon™, etc. (e.g., a smooth substrate to which the polymeric film has low adhesion). The solution is then dried to form a film. In other embodiments, for example, the resulting solution can be cast as a film onto a substrate material to produce a membrane intermediate supported on the substrate material.

[0043] In those embodiments in which the polymeric material comprises a polysaccharide material, for example, the polymeric material comprises chitosan.Below is described an exemplary method of making a membrane in which the polymeric material of the polymer phase is chitosan.

[0044] Chitosan is a generic term for the deacetylated products of chitin obtained by treatment with concentrated alkali. Chitin is the main component of the shells of crustaceans such as lobsters and crabs. In some embodiments, for example, chitosan is obtained by heating chitin to a temperature of at least 60° C. in the presence of an alkaline solution (such as an aqueous solution of sodium hydroxide) having an alkali concentration of 30-50% by weight, which has the effect that the chiton is deacetylated. Chemically, chitosan is a linear polysaccharide composed of randomly distributed β-(1-4) linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). Chitosan dissolves readily in the form of a salt in dilute aqueous solutions of acids such as acetic acid and hydrochloric acid, but when contacted again with aqueous alkali, it coagulates and precipitates again. In some embodiments, for example, chitosan has a degree of deacetylation of at least 50%, and in some of these embodiments, for example, chitosan has a degree of deacetylation of at least 75%.

[0045] The intermediate chitosan membrane can be obtained by dissolving chitosan in a dilute aqueous acid solution and casting this solution as a film onto a flat plate to form a uniform chitosan fraction, or onto a substrate material to form a composite membrane. The cast film can then be contacted with an aqueous alkaline solution to neutralize the acidity and render it sparingly soluble or substantially insoluble in water, or it can be air-dried and then contacted with an aqueous alkaline solution.

[0046] To prepare chitosan-type polysaccharide membranes, the amino groups of the intermediate composite membrane are at least partially neutralized with one or more acids to form ammonium salts. Examples of suitable acids that can be used for neutralization include inorganic acids such as hydrochloric acid, bromic acid, sulfuric acid, and phosphoric acid; and organic acids such as acetic acid, methanesulfonic acid, formic acid, propionic acid, oxalic acid, malonic acid, succinic acid, fumaric acid, maleic acid, glutaric acid, phthalic acid, isophthalic acid, terephthalic acid, trimesic acid, trimellitic acid, citric acid, aconitic acid, sulfobenzoic acid, pyromellitic acid, and ethylenediaminetetraacetic acid.

[0047] The preparation of intermediate chitosan-type polysaccharide membranes using these acids can be carried out, for example, by a method comprising immersing the intermediate chitosan-type polysaccharide membrane in a solution containing an acid to ionize the amino groups of the membrane, or by a method comprising subjecting the chitosan-type polysaccharide membrane to pervaporation with a mixture containing an acid to subsequently convert the amino groups of the chitosan-type polysaccharide membrane to ammonium ions.

[0048] In some embodiments, for example, the membrane intermediate has a dry thickness of from 10 nanometers (0.01 microns) to 20 microns, such as from 0.5 to 10 microns, or such as from 1 to 5 microns. In some embodiments, for example, the substrate material has a thickness of from 30 to 200 microns, such as from 50 to 150 microns, or such as from 80 to 110 microns.

[0049] The membrane intermediate is then contacted with a salt of a metal cation (such as silver ions or copper(I) ions). In some embodiments, for example, the contacting comprises immersing the membrane intermediate in an aqueous solution containing a salt of the metal cation (e.g., a 1-8 M aqueous solution of silver nitrate). The contacting results in the placement of the metal cations in and throughout the polymer matrix of the membrane and within its pores (e.g., by chelation and / or complexation), and results in the formation of a liquid phase.

[0050] The method includes supplying a gaseous feed material to the feed material receiving space 10 .

[0051] In some embodiments, for example, the gaseous feed material has a relative humidity of 0-100%. In some embodiments, for example, the gaseous feed material has a relative humidity of 70-99%. In some embodiments, for example, the gaseous feed material has a relative humidity of 95-99%.

[0052] The supply of gaseous feed material to the feed receiving space 10 is characterized by the placement of the feed material against the membrane, resulting in the transfer of at least a fraction of the gaseous feed material-disposed material from the feed receiving space 10 through the membrane 30 to the permeate receiving space 20, such fraction being referred to as the "separation fraction". Transfer of at least the separation fraction of the gaseous feed material-disposed material to the permeate receiving space results in the production of a gaseous permeate-disposed material in the permeate receiving space 20. The transfer (e.g., permeation) occurs as a function of the difference in chemical potential of the material to be treated, such as between the feed receiving space and the permeate receiving space. In this regard, during the transfer (e.g., permeation), the chemical potential of the material to be processed disposed in the feed receiving space 10 (i.e., the material to be processed disposed on the side of the feed material receiving space) is greater than the chemical potential of the material to be processed disposed in the permeate receiving space 20 (i.e., the material to be processed disposed on the side of the permeate receiving space). In some embodiments, for example, the chemical potential is defined by partial pressures, such that the transfer (e.g., permeation) occurs in response to a difference in partial pressures of the materials to be processed, such as between the feed receiving space 10 and the permeate receiving space 20. In this regard, during the transfer (e.g., permeation), the partial pressure of the material to be processed disposed in the feed receiving space 19 (i.e., the material to be processed disposed on the side of the feed material receiving space) is greater than the partial pressure of the material to be processed disposed in the permeate receiving space 20 (i.e., the material to be processed disposed on the side of the permeate receiving space).

[0053] The movement (e.g., permeation) of at least a separated fraction of the material to be treated, in which the gaseous feed is disposed in the permeate receiving space 20, includes the movement of at least the separated fraction through the membrane 30. During the movement, and if the liquid phase of the membrane includes a carrier reagent, at least the separated fraction is temporarily associated with the carrier reagent. In some embodiments, for example, in response to contact or interaction between at least the separated fraction and the carrier reagent, a reversible chemical reaction is believed to occur between at least the separated fraction and the carrier reagent. In those embodiments in which the material to be treated includes an olefin and the carrier reagent includes silver ions dissolved in an aqueous solution in the liquid phase of the membrane, a reactive process is carried out such that the olefin is chemically modified by combining with the carrier reagent (e.g., silver ions) through π-complexation. In this regard, in some embodiments, for example, the association is one of chemical bonding through π-complexation. FIG. 2 is an example of an association resulting in response to contact of an olefin (ethylene) with a carrier reagent (silver ions). In some of these embodiments, for example, the carrier reagent is chelated to or complexed with the polymeric material of the polymer phase.

[0054] In some embodiments, the movement of at least the separated fraction across the membrane 30 towards the permeate receiving space 20 includes that caused by the movement of material from the processed material across the membrane 30 towards the permeate receiving space 20. The material from the processed material is generated by contact of at least the separated fraction with the carrier. In this regard, in some embodiments, the movement of the material from the processed material across the membrane 30 towards the permeate receiving space 20 is facilitated by the mobility of the material from the processed material within the membrane 30. In some of these embodiments, for example, the movement of the material from the processed material across the membrane 30 towards the permeate receiving space 20 is facilitated by the mobility of the material from the processed material within the liquid material of the liquid phase of the membrane.

[0055] In some embodiments, movement of at least the separated fraction across membrane 30 and towards permeate receiving space 20 is believed to include that which is caused by "hopping" of the separated fraction from one association with carrier reagent to the next until it reaches permeate receiving space 20.

[0056] In some embodiments, it is believed that movement of at least the separated fraction across membrane 30 and towards permeate receiving space 20 includes movement caused by a combination of both of the above movement mechanisms.

[0057] Due to differences in chemical potential of the materials being processed, such as between the feed receiving space and the permeate receiving space, the concentration of at least the separated fraction in the portion of the membrane adjacent the feed receiving space 10 is higher than the concentration of at least the separated fraction in the portion of the membrane adjacent the permeate receiving space 20, thereby creating a driving force for migration.

[0058] In some embodiments, for example, during transfer (e.g., permeation) of at least the separated fraction to the permeate receiving space 20, a gaseous treated material-depleted residue is discharged from the feed receiving space 20. The molar concentration of the treated material in the gaseous feed being supplied is greater than the molar concentration of the treated material in the gaseous treated material-depleted residue being discharged.

[0059] In some embodiments, for example, during the transfer (e.g., permeation) of at least the separated fraction to the permeate receiving space 20, a residue depleted of the gaseous treated material is discharged from the feed receiving space, and a gaseous permeate product comprising the treated material in which the gaseous permeate is disposed is discharged from the permeate receiving space. The molar concentration of the treated material in the supplied gaseous feed is greater than the molar concentration of the treated material in the discharged gaseous treated material depleted residue, and the molar concentration of the treated material in the discharged gaseous permeate product is greater than the molar concentration of the treated material in the supplied gaseous feed.

[0060] In some embodiments, for example, the movement of at least the separated fraction occurs while the temperature of each of the gaseous feed receiving space and the permeate receiving space is between 5° C. and 80° C. In some embodiments, for example, the movement of the separated fraction occurs while the temperature of each of the gaseous feed receiving space and the permeate receiving space is between 10° C. and 75° C. In some embodiments, for example, the movement of the separated fraction occurs while the temperature of each of the gaseous feed receiving space and the permeate receiving space is between 15° C. and 70° C.

[0061] In some embodiments, for example, the gaseous feed further comprises a less permeable material. The less permeable material comprises at least one less permeable compound. A less permeable compound is a compound that is characterized by a lower permeability through the membrane 30 than the permeability of each of the at least one compound being treated. Such a lower permeability may derive from its relatively low diffusivity in the membrane, its relatively low solubility in the membrane, or both.

[0062] In some embodiments, for example, the less permeable compound has substantially no permeability through membrane 30 .

[0063] In some embodiments, for example, the movement (e.g., permeation) of at least the separated fraction of the treated material disposed on the gaseous feed side occurs while at least one less permeable compound moves from the feed receiving space 10 through the membrane 30 to the permeate receiving space 20. For each of the at least one treated compound of the at least separated fraction of the treated material disposed on the gaseous feed side, a operative ratio associated with the treated compound is provided, which ratio is defined by the ratio of the molar rate of permeation of the treated compound to the molar fraction of the treated compound in the feed receiving space, thereby defining operative ratios associated with a plurality of treated compounds, and at least one of the operative ratios associated with the plurality of treated compounds is the operative ratio associated with the smallest treated compound. For each of the at least one transfer (or permeation) of the less permeable compound, the ratio of the molar rate of permeation of the compound to be treated to the molar fraction of the less permeable compound in the feed receiving space is less than the treatment ratio associated with the smallest compound to be treated, such that for each of the at least one compound to be treated, the molar concentration of the compound to be treated in the gaseous permeate transferred (or permeated) from the gaseous feed receiving space through the membrane to the permeate receiving space is greater than the molar concentration of the compound to be treated in the gaseous feed. In some embodiments, for example, during the transfer, the gaseous permeate is released from the permeate receiving space as a gaseous permeation product. At this point, the gaseous feed is fractionated based on the relative permeabilities of its compounds.

[0064] In some embodiments, for example, each of the at least one treated compound is an olefin and each of the at least one less permeable compound is a paraffin.

[0065] In some embodiments, for example, the at least one treated compound is a single treated compound, where the single treated compound is an olefin, and the at least one less permeable compound is a single less permeable compound, where the single less permeable compound is a paraffin.

[0066] In some embodiments, for example, suitable paraffins are those having 1-10 total carbon atoms.

[0067] In some embodiments, for example, a flow of the gaseous feed, characterized in that the gaseous feed is disposed relative to the membrane such that at least a fraction of the material to be treated (hereinafter such fraction is referred to as the "separated fraction") in which the gaseous feed is disposed is transferred from the feed receiving space 10 through the membrane 30 to the permeate receiving space 20, such that a flow of the gaseous feed is established across the membrane 30, the established flow spanning a traversed distance of the membrane 30 as measured in the direction of the established flow, which is at least 10 cm, such as at least 20 cm, for example at least 30 cm.

[0068] In some embodiments, for example, the method is carried out in an apparatus 40 , with the feed receiving space 10 and the permeate receiving space 20 defined by respective compartments 12 , 22 within the apparatus 40 .

[0069] The compartment 12 defining the feed receiving space includes a receiving communicator 14 and a discharge communicator 16. The receiving communicator 14 is arranged to receive a gaseous feed, which is intended to feed the feed receiving space 10, which is intended to place the gaseous feed in mass transfer communication with the membrane 30, and the receiving communicator 14 is arranged in some embodiments to receive a replenishment material, which is intended to feed the feed receiving space 10, which is intended to place the replenishment material in mass transfer communication with the membrane 30, which is intended to replenish the liquid material consumed during the process (liquid phase of the membrane 30). The discharge communicator 16 is arranged to discharge a residue material comprising the residue of the gaseous material to be treated consumed. The compartment 22 defining the permeate receiving space includes a discharge communicator 26. Discharge communication 26 is arranged to discharge gaseous permeation products.

[0070] The method includes contacting the membrane 30 with a replenishment material.

[0071] At least a portion of the liquid material in the liquid phase of the membrane 30 is consumed during contact of the gaseous feed with the membrane (e.g., while the gaseous feed is being fed into the feed receiving space 10), which contact is characterized by the transfer (permeation) of at least a separated fraction. Contact of the membrane with the replenishment material results in the replenishment of at least a portion of the liquid material in the liquid phase of the membrane 30.

[0072] Replenishment is desirable as liquid material is consumed from the liquid phase by mass transfer from the membrane 30, e.g., mass transfer to both the feed receiving space 10 and the permeate receiving space 20. Liquid material may evaporate and move into the feed receiving space 10 in response to a concentration gradient. Liquid material may also evaporate and be disposed of in at least the separated fraction that is permeating through the membrane 30. At least the separated fraction spreads through the membrane as it is being moved from the feed receiving space 10 to the permeate receiving space 20. As at least the separated fraction spreads, liquid from the liquid phase evaporates and is swept away by the permeation of at least the separated fraction.

[0073] In some embodiments, for example, the liquid material of the replenishment material is water. In some embodiments, for example, the liquid material includes water.

[0074] In some embodiments, for example, the replenishment material comprises 10-90% water by weight based on the total weight of the replenishment material. In some embodiments, for example, the replenishment material comprises 25-75% water by weight based on the total weight of the replenishment material. In some embodiments, for example, the replenishment material comprises 30-50% water by weight based on the total weight of the replenishment material.

[0075] In some embodiments, for example, the liquid material of the replenishment material may also include other additives, such as co-solvents and hygroscopic materials.

[0076] In some embodiments, for example, the replenishment material includes a carrier reagent disposed in the replenishment material dissolved in the liquid material in which the replenishment material is disposed. The liquid material of the replenishment material in which the replenishment material is disposed defines the liquid material of the replenishment material. The carrier reagent disposed in the replenishment material dissolved in the liquid material in which the replenishment material is disposed defines the dissolved carrier reagent of the replenishment material. In those embodiments in which the liquid material is water, in some of these embodiments, for example, the carrier reagent is dissolved in water to provide an aqueous solution including the dissolved carrier reagent.

[0077] By including the carrier reagent within the liquid material in which the replenishment material is disposed, stripping of the carrier reagent from the membrane is mitigated during contact of the membrane with the replenishment material. In this regard, for example, in some embodiments in which the replenishment material does not contain a carrier reagent, a concentration gradient may cause carrier reagent associated within membrane 30 to migrate from membrane 30 to the replenishment material in contact with membrane 30.

[0078] In some embodiments, for example, the carrier reagent is silver ions and the replenishment material comprises an aqueous solution containing silver ions at a molar concentration of at least 1.0. In some embodiments, for example, the replenishment material comprises an aqueous solution containing silver ions at a molar concentration of 2.0 to 10.0. In some embodiments, for example, the replenishment material comprises an aqueous solution containing silver ions at a molar concentration of 5.0 to 8.0. In these embodiments, for example, the membrane comprises chitosan.

[0079] The rate and extent of consumption of the liquid material depends on the operating conditions, such as the operating temperature and pressure, the rate of material flow through the feed receiving space, and the rate of release of the permeate product from the permeate receiving space, and also on the water content in each of the feed receiving space and the permeate receiving space. Maintaining a minimum concentration of the liquid material in the membrane aids in carrying out continuous separation and permeation, since it promotes the desired mobility of the material from the material being treated, while maintaining the desired structural integrity of the membrane. Complete consumption of the liquid material leads to uneven tensions, cracks, or pinholes that impair performance. By including a carrier reagent in the liquid material in which the replenishment material is disposed, stripping of the carrier reagent from the membrane during contacting the membrane with the replenishment material is mitigated. In this regard, in some embodiments in which the replenishment material does not contain a carrier reagent, for example, a concentration gradient may cause the carrier reagent associated with the membrane 30 to migrate from the membrane 30 to the replenishment material in contact with the membrane 30.

[0080] In response to contact of the replenishment material with the membrane, at least a fraction of the liquid material in which the replenishment material is disposed is disposed within the liquid phase of membrane 30 .

[0081] In some embodiments, for example, the membrane 30 is contacted with the replenishment material after at least a portion of the liquid material of the liquid phase of the membrane 30 has been consumed during the supply of the gaseous feed material to the feed material receiving space 10, the supply being such that at least the migration (permeation) of the separated fraction is effected. In this respect, in some embodiments, for example, the contact with the replenishment material is effected after the supply of the gaseous feed material to the feed material receiving space 10 has been effected.

[0082] In some embodiments, for example, contacting membrane 30 with replenishment material occurs in response to sensing that at least a fraction of the liquid material disposed within the liquid phase of the membrane has been consumed.

[0083] In some embodiments, for example, contact between the membrane 30 and the replenishment material occurs in the feed receiving space 10. In some embodiments, for example, contact between the membrane and the replenishment material occurs in the permeate receiving space 20. In some embodiments, for example, contact between the membrane and the replenishment material occurs in both the feed receiving space 10 and the permeate receiving space 20. In some embodiments, for example, contact occurs with a stationary or stagnant permeate of the replenishment material.

[0084] In some embodiments, for example, contacting of the membrane with the make-up material occurs while the gaseous feed material is being fed to the feed receiving space 10. In this regard, in some embodiments, for example, make-up occurs while a separation process is being performed. In some embodiments, for example, make-up material is fed to the permeate receiving space 20 while a separation process is being performed by feeding a gaseous feed material to the feed receiving space 10. In some embodiments, for example, make-up material is fed to the feed receiving space 10 such that a combined mixture of the gaseous feed material and the make-up material is fed to the feed receiving space 10, and in some embodiments, (i) contacting of the membrane with the make-up material occurs and (ii) a separation process is performed while a combined mixture of the gaseous feed material and the make-up material is fed to the feed receiving space 10. In some embodiments, for example, make-up material is fed to both the feed receiving space 10 and the permeate receiving space 20 while a separation process is being performed by feeding a gaseous feed material to the feed receiving space 10.

[0085] In those embodiments in which contact between the membrane and the make-up material is performed while the gaseous feed material is being fed to the feed receiving space 10, in some embodiments, for example, the performance of contact between the membrane and the make-up material is periodic. In this regard, in some embodiments, for example, the method includes feeding the gaseous feed material to the feed receiving space 10 for a first time interval, which is characterized by permeation of at least a separation fraction from the feed receiving space through the membrane 30 to the permeate receiving space 20. After the first time interval, contact between the membrane 30 and the make-up material is performed while continuing to feed the gaseous feed material to the feed receiving space 10 during a second time interval, which is characterized by permeation from the feed receiving space through the membrane 30 to the permeate receiving space 20. After the second time interval, during a third time interval, the gaseous feed material continues to be fed to the feed receiving space 10, but at the end of the second time interval, contact between the membrane and the make-up material is suspended so that the membrane 30 does not come into contact with the make-up material. After the third time interval, during a fourth time interval, the supply of replenishment material (to bring the replenishment material into contact with the membrane 30) resumes while continuing to supply gaseous feed material to the feed material receiving space 10.

[0086] In those embodiments in which contact of the membrane 30 with the replenishment material is periodic, in some of these embodiments, for example, the minimum concentration of the carrier reagent dissolved in the replenishment material provided during at least one period (e.g., one of the second and fourth time intervals, referring again to the example provided above) is greater than the maximum concentration of the carrier reagent dissolved in the replenishment material provided during at least another one of the time intervals (e.g., another one of the second and fourth time intervals, referring again to the example provided above). In some embodiments, for example, the minimum concentration of the carrier reagent dissolved in the replenishment material provided during at least one of the time intervals is 1.05 to 2.0 times greater than the maximum concentration of the carrier reagent dissolved in the replenishment material provided during at least another one of the time intervals. In some embodiments, replenishment material that further dilutes the dissolved carrier reagent is provided during at least one of the time intervals to facilitate dissolution of any carrier reagent that may be precipitated on the membrane during the method.

[0087] In some embodiments, for example, contacting the membrane 30 with the make-up material is performed after the supply of the gaseous feed material to the feed receiving space 10 has been suspended. In this respect, the method further includes suspending the supply of the feed material to the feed receiving space 10 after the suspension, such that contacting the membrane with the make-up material is performed without or substantially without the supply of the gaseous feed material. After sufficient replenishment, the method further includes suspending the performance of contacting the membrane with the make-up material so that the first liquid replenishment period is completed. After the suspension of the performance of contacting the membrane with the make-up material, the supply of the gaseous feed material to the feed receiving space 10 is resumed, whereby permeation of at least the separated fraction from the feed receiving space through the membrane 30 to the permeate receiving space 20 is performed during the resumption of the supply of the gaseous feed material to the feed receiving space 10. Subsequently, the resumption of the supply of the gaseous feed material to the feed receiving space is suspended. After the resumption of the supply of gaseous feed material to the feed receiving space is paused, the contacting of the membrane 30 with the replenishment material is resumed, whereby contacting of the membrane 30 with the replenishment material occurs during a second liquid replenishment period, whereby contacting of the membrane with the replenishment material occurs without or substantially without supplying gaseous feed material to the feed receiving space. In some of these embodiments, for example, the minimum concentration of the carrier reagent dissolved in the replenishment material provided during one of the first and second liquid replenishment time intervals is greater than the maximum concentration of the carrier reagent dissolved in the replenishment material provided during the other one of the first and second liquid replenishment time intervals. In some embodiments, for example, the minimum concentration of the carrier reagent dissolved in the replenishment material provided during at least one of the first or second liquid replenishment intervals is 1.05 to 2.0 times greater than the maximum concentration of the carrier reagent dissolved in the replenishment material provided during the other one of the first or second liquid replenishment intervals. In some embodiments, it may be desirable to provide a more dilute replenishment material of dissolved carrier reagent during one of the liquid replenishment intervals to facilitate dissolution of any carrier reagent that may be precipitated on the membrane during the method. In some of these embodiments, for example, contacting the membrane with the replenishment material is performed for a predetermined time interval that is determined by several factors.These factors include gas deposition across the membrane, operating temperature, pressure differential, membrane thickness, molarity of the hydration solution, substrate properties, etc. (Some of these are, of course, interdependent.) Experiments show the onset of changes in membrane permeability, membrane selectivity, or both, and changes in membrane composition due to membrane dehydration, for a given set of operating conditions. The liquid material is replenished at appropriate intervals to maintain uniform performance and / or protect the integrity of the membrane.

[0088] In some embodiments, for example, the supply of replenishment material (to one or both of the gaseous feed receiving compartment 12 and the permeate receiving compartment 22) is performed by flowing the replenishment material upwards, which improves contact between the supplied replenishment material and the membrane 30.

[0089] In some embodiments, for example, a make-up material is fed to one of the feed receiving space 10 and the permeate receiving space 20, whereby a transfer is effected through the membrane 30 from one of the feed receiving space 10 and the permeate receiving space 20 to the other of the feed receiving space 10 and the permeate receiving space 20, where the pressure in the feed receiving space and in the other of the permeate receiving spaces is less than atmospheric pressure. By effecting a transfer through the membrane to a space located at less than atmospheric pressure, concentration of the liquid material is reduced. Such concentration creates a back pressure on the membrane and prevents the transfer (permeation) of a separated fraction of the material to be treated, in which the gaseous feed is located, from the feed receiving space to the permeate receiving space.

[0090] By providing a crosslinked polymeric material as the polymeric phase of membrane 30, the resistance to movement of the replenishment material through the membrane is increased and the permeation rate of the replenishment material is decreased, thereby reducing the amount of inventory of replenishment material required on hand to effect replenishment.

[0091] As discussed above, in some embodiments, a make-up material is contacted with the membrane, for example, to replenish the liquid material in the membrane 30 with the gaseous feed material. In some embodiments, for example, the contact is made by supplying the make-up material to the feed receiving space 10. In this respect, a method is provided that includes supplying a gaseous feed material to the feed receiving space 10 for a first time interval, which is characterized by permeation of at least a separated fraction from the feed receiving space through the membrane 30 to the permeate receiving space 20. After the first time interval, while continuing to supply the gaseous feed material to the feed receiving space 10 during a second time interval (which has the effect of causing permeation of at least a separated fraction from the feed receiving space through the membrane 30 to the permeate receiving space 20), contact is made with the make-up material to the membrane 30 (which has the effect of placing at least a fraction of the liquid material in which the make-up material is placed in the liquid phase of the membrane 30).

[0092] In this regard, during the second time interval, a replenishment phase mixture is disposed within the feed material receiving space 10, the replenishment phase mixture including the gaseous feed material and the replenishment material. In some of these embodiments, for example, the replenishment phase mixture is a mixture obtained by mixing at least the gaseous feed material and the replenishment material, and the method includes mixing at least the gaseous feed material and the replenishment material to obtain the feed phase mixture.

[0093] In some embodiments, the supply of replenishment material is carried out having the feature that, for example, a liquid material of the replenishment material is positioned relative to the membrane 30 such that it is disposed within the liquid phase of the membrane 30, whereby a flow of the replenishment material is established across the membrane 30, the established flow spanning a transverse distance of the membrane 30, which transverse distance being at least 10 cm, such as at least 20 cm, for example at least 30 cm, when measured in the direction of the established flow.

[0094] In the preceding description for purposes of illustration, numerous details have been set forth to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that these specific details are not required for the practice of the present disclosure. Although specific dimensions and materials have been described to implement the disclosed exemplary embodiments, other suitable dimensions and / or materials may be used within the scope of this disclosure. Such modifications and variations, including all current and future suitable changes in technology, are considered to be within the scope and scope of the present disclosure. All references cited are incorporated herein by reference in their entirety.

Claims

1. 1. A method for separating a material to be processed from a gaseous feed by a membrane comprising a polymer phase and a liquid phase, comprising: separating at least a separated fraction of the material to be processed in response to permeation of at least the separated fraction of the material to be processed through the membrane over a first time interval; placing a replenishment material comprising a liquid material against the membrane after the first time interval to place the liquid material of the replenishment material in a liquid phase of the membrane such that replenishment of the membrane occurs; Including, The permeation involves the movement of at least a separated fraction of the material being processed through the membrane, during which at least a separated fraction of the material being processed is temporarily associated with a carrier reagent dissolved within a liquid material in the liquid phase of the membrane. the supplemental material comprises a carrier reagent; the membrane comprises crosslinked chitosan; method.

2. the separating step occurs in response to contact of the membrane with a gaseous feed; The refilling of the membrane occurs while the gaseous feed is contacting the membrane. The method of claim 1.

3. the support material comprises silver ions; the replenishment material comprises an aqueous solution containing silver ions at a molar concentration of at least 1.0; The method of claim 2.

4. 4. The method of claim 2 or 3, wherein during the first time interval a fraction of the liquid material of the liquid phase of the membrane is consumed.

5. The method according to any one of claims 2 to 4, wherein the liquid material comprises water.

6. 6. The method according to claim 1, wherein the permeation of at least the separated fraction is carried out while at least one less permeable compound of the gaseous feed is permeating through the membrane.

7. 7. The method according to claim 1, wherein said permeation of at least said separated fraction is carried out during which at least one less permeable compound of the gaseous feed material permeates through the membrane, thereby fractionating the gaseous feed material.

8. said at least separated fraction comprises at least one compound to be treated; For each of the at least one treated compound of the at least separated fraction, an operative ratio is provided that is defined by the ratio of the molar rate of permeability of the treated compound to the molar fraction of the treated compound in the feed receiving space, thereby defining a plurality of treated compound operative ratios, at least one of the plurality of treated compound operative ratios being a minimum treated compound operative ratio; 8. The method of claim 6 or 7, wherein, for each of the at least one less permeable permeable compounds, the ratio of the molar rate of permeation of the less permeable compound to the molar fraction of the less permeable compound in the feed receiving space is less than the treat ratio associated with the smallest treated compound, whereby, for each of the at least one treated compound, the molar concentration of the treated compound in the gaseous permeate permeated through the membrane from the gaseous feed receiving space to the permeate receiving space is greater than the molar concentration of the treated compound in the gaseous feed.

9. each of said at least one treated compound is independently an olefin; each of the at least one less permeable compound is independently a paraffin; The method according to claim 8.

10. the separation occurs in response to an established flow of the gaseous feed material across the membrane; the established flow is across a transverse distance of the membrane; 10. The method of any one of claims 1 to 9, wherein the traversed distance, measured in the direction of the established flow, is at least 10 cm.

11. 1. A method for separating a material to be processed from a gaseous feed by a membrane comprising a polymer phase and a liquid phase, comprising: fractionating the gaseous feed based on the relative permeability of its compounds through a membrane over a first time interval; placing a replenishment material comprising a liquid material against the membrane after the first time interval to place the liquid material of the replenishment material in a liquid phase of the membrane such that replenishment of the membrane occurs; Including, the membrane includes a carrier reagent dissolved within a liquid material of the liquid phase of the membrane, the carrier reagent being associated with a permeated fraction of the gaseous feed material and facilitating its permeation through the membrane; the supplement comprises the carrier reagent; the membrane comprises crosslinked chitosan; method.

12. the fractionating step occurs in response to contact of the membrane with the gaseous feed; said refilling of said membrane occurs while said gaseous feed is contacting said membrane; The method of claim 11.

13. the carrier material comprises silver ions; the replenishment material comprises an aqueous solution containing silver ions at a molar concentration of at least 1.0; 13. The method according to claim 11 or 12.

14. The method according to any one of claims 11 to 13, wherein during said first time interval a fraction of liquid material of the liquid phase of the membrane is consumed.

15. The method according to any one of claims 11 to 14, wherein the liquid material comprises water.

16. the gaseous feed comprises an olefinic material defined by at least one olefin and a paraffinic material defined by at least one paraffin; the fractionation in the first device is characterized in that the retentate is enriched in paraffinic material relative to the gaseous feed material; The fractionation in the second device is characterized in that a second retentate and a second permeate are obtained, the second retentate being enriched in paraffinic material with respect to the retentate received by the first device. The method according to any one of claims 11 to 15.

Images