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    • 专利摘要:
    POLYIMIDE MEMBRANE, AND, SEPARATION PROCESS TO SEPARATE TWO OR MORE SUBSTANCES The present invention describes a new type of polyimide membrane with high pressures and high selectivities for gas separations and in particular for CO2 / CH4 and H2 / CH4 separations. Polyimide membranes have CO2 permeability of 50 Barrers or greater and single gas selectivity for CO2 / CH4 of 15 or greater at 50 ° C and under 791 kPa for CO2 / CH4 separation. Polyimide membranes have UV crosslinkable functional groups and can be used for the preparation of UV crosslinkable polyimide membranes with CO2 permeability of 20 Barrers or above and single gas selectivity for CO 2 / CH4 of 35 or above 50 ° C under 791 kPa for CO2 / CH4 separation.
    公开号:BR112013024956B1
    申请号:R112013024956-0
    申请日:2012-05-31
    公开日:2020-11-17
    发明作者:Chunqing Liu；Travis C. Bowen；Emily G. Harbert；Raisa Minkov；Syed A. Faheem；Zara Osman
    申请人:Uop Llc；
    IPC主号:
    专利说明:

    BACKGROUND OF THE INVENTION
    [001] This invention relates to a new type of polyimide membrane with high permeation and high selectivity for gas separation and, more particularly, for upgrading in natural gas beneficiation and hydrogen purification.
    [002] In the last 30-35 years, the state of the art of polymeric gas separation processes has evolved rapidly. Membrane based technologies are a low capital cost solution and provide high energy efficiency compared to conventional separation methods. Membrane gas separation is of particular interest to oil producers and refineries, chemical companies, and suppliers of industrial gas. Various membrane gas separation applications have achieved commercial success, including the enrichment of N2 from the air, the removal of carbon dioxide from natural gas and improved oil recovery, as well as the removal of hydrogen from nitrogen, methane and argon in ammonia purge gas streams. For example, Separex ™ cellulose acetate spiral wound membrane from UOP is currently the international market leader for the removal of carbon dioxide from natural gas.
    [003] Polymers provide a range of properties, including low cost, permeability, mechanical stability and ease of processing, which are important for gas separation. Glassy polymers (that is, polymers at temperatures below their Tg) have the hardest polymer backbone and therefore allow small molecules such as hydrogen and helium to pass through more quickly, while Larger molecules, such as hydrocarbons, pass through more slowly compared to polymers with less rigid backbones. Vitreous polymeric cellulose acetate (CA) membranes are used extensively in gas separation. Currently, such CA membranes are used for processing natural gas, including the removal of carbon dioxide. Although CA membranes have many advantages, they are limited in a number of properties, including selectivity, permeability, and chemical, thermal, and mechanical stability. High performance polymers such as polyimides (Pis), poly (trimethylsilylpropino) and polythriazole have been developed to improve membrane selectivity, permeability, and thermal stability. These polymeric membrane materials have shown promising intrinsic properties for separating gas pairs such as CO2 / CH4, O2 / N2, H2 / CH4, and propylene / propane (C3H6 / C3H8).
    [004] The membranes most commonly used in commercial liquid and gas separation applications are asymmetric polymeric membranes and have a selective non-porous thin film layer that performs the separation. The separation is based on a diffusion-solution mechanism. This mechanism involves molecular scale interactions of the permeation gases with the membrane polymer. The mechanism assumes that in a membrane with two opposite surfaces, each component is absorbed by the membrane to a surface, transported by a gradient of gas concentration, and desorbed on the opposite surface. According to this solution-diffusion model, the performance of the membrane in the separation of a given gas pair (for example, CO2 / CH4, O2 / N2, H2 / CH4) is determined by two parameters: the permeability coefficient (the abbreviated as permeability or PA) and selectivity (OLA / B). PA is the product of the gas flow and the thickness of the selective film layer of the membrane, divided by the pressure difference across the membrane. The CIA / B is the ratio of the permeability coefficients of two gases ('A / B = PA / PB), where PA represents the permeability of the most permeable gas and PB is the permeability of the least permeable gas. Gases can have high permeability coefficients due to a high solubility coefficient, a high diffusion coefficient, or because both coefficients are high. In general, the diffusion coefficient decreases, while the solubility coefficient increases with the increase in the molecular size of the gas. In high performance polymer membranes, both high permeability and selectivity are desirable, because greater permeability decreases the size of the membrane area required to treat a given volume of gas, thereby decreasing the capital cost of membrane units, and, because greater selectivity results in a higher purity gas product.
    [005] One of the components to be separated by a membrane must have sufficiently high permeation under the preferred conditions or an extraordinarily large membrane surface area is necessary to allow the separation of large amounts of material. Permeation, measured in gas permeation units (GPU, 1 GPU = 10'6 cm3 (STP) / cm2 s (cm Hg)), is the flow normalized by pressure and is equal to the permeability divided by the thickness of the film layer of the membrane. Commercially available polymeric gas separation membranes, such as AC, polyimide, and polysulfone membranes formed by phase inversion and solvent exchange methods have an asymmetric membrane structure entirely without film. Such membranes are characterized by a selectively semipermeable, thin and dense surface “film” and a non-selective support region containing a less dense (or porous) void, with pore dimensions ranging from large in the support region to very small near of the “film”. However, it is very complicated and tedious to make such asymmetric membranes entirely without film with a defect-free film layer. The presence of nanopores or defects in the film layer reduces the selectivity of the membrane. Another type of commercially available polymeric gas separation membrane is the thin-film composite membrane (or TFC), comprising a selective thin film deposited on a porous support. TFC membranes can be formed from CA, polysulfone, polyethersulfone, polyamide, polyimide, polyetherimide, cellulose nitrate, polyurethane, polycarbonate, polystyrene, etc. The manufacture of TFC membranes that are free from defects is also difficult and requires several steps. Yet another approach to reducing or eliminating nanopores or defects in the film layer of asymmetric membranes has been the manufacture of an asymmetric membrane comprising a membrane of “selective” origin containing substantial and relatively porous voids such as polysulfone or cellulose acetate, which would have high selectivity was not porous, in which the original membrane is coated with a material, such as a polysiloxane, a silicone rubber, or a UV-curable epoxy silicon to occlude contact with the original porous membrane, the surface pores of lining filling and other imperfections that comprise voids. The coating of such coated membranes, however, is subject to solvent swelling, poor performance durability, low resistance to hydrocarbon contaminants, and low resistance to plastification by absorbed penetrating molecules, such as CO2 or C3H6.
    [006] Many of the deficiencies of these prior art membranes are improved in the present invention which provides a new type of polyimide membrane with high permeations and high selectivities for gas separations. SUMMARY OF THE INVENTION
    [007] A new type of polyimide membrane with high permeations and high selectivities for gas separations was made.
    [008] The present invention generally relates to gas separation membranes and, more particularly, to high permeability and high selectivity polyimide membranes for gas separations. The polyimide membranes with high permeations and high selectivities described in the present invention have a CO2 permeability of at least 50 Barrer (1 Barrer = 10 10 cm3 (STP) cm / cm2 s (cm Hg)) and CO2 / CH4 selectivity in gas single, at least 15 to 50 ° C under 791 kPa of supply pressure.
    [009] The present invention provides a new type of polyimide membranes with high permeation and high selectivity for gas separation. A polyimide membrane described in the present invention is made from poly (3,3 ', 4,4'-diphenylsulfone tetracarboxylic -2,4,6-trimethyl-m-phenylenediamine) polyimide (abbreviated as NPI-1), which is derived from the 3,3 ', 4,4'-diphenylsulfone tetracarboxylic (DSDA) polycondensation reaction with 2,4,6-trimethyl-m-phenylenediamine (TMPDA). Tests have shown that this NPI-1 polyimide DE membrane has an intrinsic CO2 permeability of 73.4 Barrers and single gas selectivity for CO2 / CH4 from 25.3 to 50 ° C under 791 kPa for CO2 / CH4 separation. This membrane also has intrinsic H2 permeability of 136.6 Barrers and single gas selectivity for H2 / CH4 from 47.1 to 50 ° C under 791 kPa for H2 / CH4 separation. This NPI-1 polyimide membrane contains UV crosslinkable sulfonic groups.
    [0010] Another polyimide membrane described in the present invention is manufactured from poly (3,3 ', 4,4'-diphenylsulfone tetracarboxylic -3,3', 4,4'-biphenyl tetracarboxylic dianhydride -2, 4, 6 - trimethyl-m-phenylenediamine -3,3 ', 5,5'-tetramethyl- 4,4'-methylene dianiline) polyimide (abbreviated as NPI-2), which is derived from the DSDA and 3.3 polycondensation reaction ', 4,4' - tetracarboxylic biphenyl dianhydride (BPDA) with 3,3 ', 5,5'-tetramethyl- 4,4'- methylene dianiline (TMMDA) and TMPDA (DSDA: BPDA: TMMDA: TMPDA = 3.06 : 1.02: 2.00: 2.00 (molar ratio)). Pure gas permeation results showed that this NPI-2 membrane has an intrinsic CO2 permeability of 57.5 Barrers and single gas selectivity for CO2 / CH4 from 20.2 to 50 ° C under 791 kPa for CO2 separation / CH4. This membrane also has intrinsic H2 permeability of 109.9 Barrers and single gas selectivity for H2 / CH4 from 38.6 to 50 ° C under 791 kPa for H2 / CH4 separation. This NPI-2 membrane contains UV-crosslinkable sulfonic groups.
    [0011] However, another polyimide membrane that forms part of the present invention is made from poly (3,3 ', 4,4'-tetracarboxylic benzophenone - pyromelitic dianhydride - 2,4,6-trimethyl-m-phenylenediamine ) polyimide (abbreviated as NPI-3), which is derived from the polycondensation reaction of 3,3 ', 4,4'-tetracarboxylic benzophenone dianhydride (BTDA) and pyromelitic dianhydride (PMDA) with TMPDA (BTDA: PMDA: TMPDA = 2.04: 2.04: 4.00 (molar ratio)). The pure gas permeation results showed that this NPI-3 membrane has an intrinsic CO2 permeability of 179 Barrers and a selectivity of single CO2 / CH4 gas of 15.8 at 50 ° C under 791 kPa for CO2 / CH4 separation . This membrane also has the intrinsic H2 permeability of 256.5 Barrers and a single H2 / CH4 gas selectivity of 22.7 at 50 ° C under 791 kPa for H2 / CH4 separation. This NPI-3 membrane contains UV-crosslinkable carbonyl groups.
    [0012] However, another polyimide membrane that forms part of the present invention is manufactured from poly (3,3 ', 4,4'-tetracarboxylic benzophenone - pyromellitic dianhydride -2,4,6-trimethyl-m-phenylenediamine -3,3 ', 5,5'-tetramethyl- 4,4'-methylene dianiline) polyimide (abbreviated as NPI-4), which is derived from the polycondensation reaction of BTDA and PMDA with TMPDA and TMMDA (BTDA: PMDA: TMPDA: TMMDA = 2.04: 2.04: 2.00: 2.00 (molar ratio)). Pure gas permeation results showed that this NPI-4 membrane has an intrinsic CO2 permeability of 97.0 Barrers and a single CO2 / CH4 gas selectivity of 17.1 at 50 ° C under 791 kPa for CO2 separation / CH4. This membrane also has an intrinsic H2 permeability of 159.5 Barrers and a single H2 / CH4 gas selectivity of 28.2 at 50 ° C under 791 kPa for H2 / CH4 separation. This NPI-4 membrane contains UV-crosslinkable carbonyl groups.
    [0013] In another embodiment of the invention, the present invention relates to high performance polyimide membranes, which have been subjected to an additional crosslinking step, by chemical or UV crosslinking or other crosslinking process as known for a person skilled in the art. A cross-linked polyimide membrane can be prepared by UV cross-linking of the polyimide membrane by exposing the membrane to UV radiation. The polyimide polymers used for the preparation of polyimide membranes described in the present invention have UV-crosslinkable sulfonic (-SO2-) or carbonyl (-C (O) -) groups. Cross-linked polyimide membranes comprise segments of the polymer chain where at least part of these segments of the polymer chain are cross-linked to each other through possible direct covalent bonds upon exposure to UV radiation. The cross-linking of polyimide membranes provides the membranes with improved selectivities and decreased permeations compared to the corresponding non-cross-linked polyimide membranes.
    [0014] The formulation of the solution to be spun from the membrane for the preparation of high permeation polyimide membranes for gas separations in the present invention comprises N-methylpyrrolidone (NMP) and 1,3-dixolane which are good solvents for the polymer of polyimide. In some cases, the formulation of the solution to be spun from the membrane for the preparation of polyimide membranes with high permeations and high selectivities for gas separations in the present invention also comprises acetone and isopropanol (or methanol), which are weak solvents for the polymer of polyimide. The new polyimide membrane with high permeations and high selectivities for gas separations described in the present invention has either a flat sheet (spiral wound) or hollow fiber geometry. In some cases, the layer surface of the selective film of the polyimide membranes is coated with a thin layer of material, such as a polysiloxane, a fluoropolymer, a thermally curable silicone rubber, or a UV-cured silicone rubber.
    [0015] The invention provides a process for separating at least one gas from a mixture of gases, using the new polyimide membranes with high permeations and high selectivities described herein, the process comprising: (a) providing a membrane of polyimide with high permeation and high selectivity described in the present invention, which is permeable to said at least one gas; (b) contacting the mixture on one side of the polyimide membrane to cause said at least one gas to permeate the membrane, and (c) removing from the opposite side of the membrane a permeate gas composition comprising a portion of said at least one gas that permeated said membrane.
    [0016] The new polyimide membranes with high permeations and high selectivities are not only suitable for a variety of liquid, gas and vapor separations such as reverse osmosis water desalination, non-aqueous liquid separation such as deep desulfurization of diesel and gasoline fuels, ethanol / water separations, perhydration dewatering of aqueous / organic mixtures, CO2 / CH4, CO2 / N2, H2 / CH4, O2 / N2, H2S / CH4, olefin / paraffin, isoparaffin / paraffin separations normal and other light gas mix separations, but can also be used for other applications such as catalysis and fuel cell applications. DETAILED DESCRIPTION OF THE INVENTION
    [0017] The use of membranes for the separation of both gases and liquids is a growing technological area with a high potential for economic reward due to low energy requirements and the potential for the expansion of modular membrane projects. Advances in membrane technology, with the continued development of new membrane materials and new methods for the production of high-performance membranes will make this technology even more competitive with traditional, expensive, high-energy processes such as distillation . Among the applications of large-scale gas separation membrane systems are nitrogen enrichment, oxygen enrichment, hydrogen recovery, removal of hydrogen sulfide and carbon dioxide from natural gas and air dehydration and natural gas. Various hydrocarbon separations are potential applications for the appropriate membrane system. The membranes that are used in these applications should have a high selectivity, durability and productivity when processing large volumes of gas or liquid, in order to be an economic success. Gas separation membranes have evolved rapidly over the past 25 years due to their easy processing for low energy and scaling needs. More than 90% of membrane gas separation applications involve the separation of non-condensable gases, such as carbon dioxide from methane, nitrogen from air, and hydrogen from nitrogen, argon or methane. Membrane gas separation is of particular interest to oil producers and refineries, chemical companies, and suppliers of industrial gas. Various membrane gas separation applications have achieved commercial success, including nitrogen enrichment from air, the removal of carbon dioxide from natural gas and biogas and improved oil recovery.
    [0018] The present invention provides a new type of polyimide membranes with high permeations and high selectivities for gas separations. This invention also relates to the application of such polyimide membranes with high permeations and high selectivities for a variety of gas separations, such as CO2 / CH4, H2S / CH4, CO2 / N2 separations, olefin / paraffin separations (for example, propylene / propane separation), H2 / CH4, O2 / N2, isoparaffin / normal paraffin, polar molecules such as H2O, H2S, and NHβ / mixtures with CH4, N2, H2 and other light gas separations, as well as for the separation liquids, such as desalination and pervaporation.
    [0019] The formulation of the solution to be spun from the membrane for the preparation of polyimide membranes with high permeations and high selectivities for gas separations in the present invention comprises good solvents for the polyimide polymer which can completely dissolve the polymer. Good representative solvents for use in the present invention include N-methylpyrrolidone (NMP), N, N-dimethyl acetamide (DMAc), methylene chloride, N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dioxanes, 1, 3-dioxolane, mixtures thereof, others known to those skilled in the art and mixtures thereof. In some cases, the formulation of the solution to be spun from the membrane for the preparation of polyimide membranes with high permeations and high selectivities for gas separations in the present invention also comprises the solvents poor for the polyimide polymer which cannot dissolve the polymer , such as acetone, methanol, ethanol, tetrahydrofuran (THF), toluene, n-octane, n-decane, lactic acid, citric acid, isopropanol and mixtures thereof. It is believed that the appropriate weight ratio of the solvents used in the present invention provides asymmetric polyimide membranes with a selective non-porous superfine film layer <100 nm, resulting in high permeations. The polyimide membranes with high permeations and high selectivities described in the present invention have CO2 permeability of at least 50 Barrers and single gas selectivity for CO2 / CH4 of at least 15 to 50 ° C under 791 kPa of feed pressure.
    [0020] The present invention provides a new type of polyimide membranes with high permeations and high selectivities for gas separations. A polyimide membrane described in the present invention is manufactured from poly (3,3 ', 4,4'-diphenylsulfone tetracarboxylic -2,4,6-trimethyl-m-phenylenediamine), polyimide (abbreviated as NPI-1) , which is derived from the 3,3 ', 4,4'-diphenylsulfone tetracarboxylic (DSDA) polycondensation reaction with 2,4,6-trimethyl-m-phenylenediamine (TMPDA). Tests have shown that this NPI-1 polyimide membrane has an intrinsic CO2 permeability of 73.4 Barrers and single gas selectivity for CO2 / CH4 from 25.3 to 50 ° C under 791 kPa for CO2 / CH4 separation. This membrane also has intrinsic H2 permeability of 136.6 Barrers and single gas selectivity for H2 / CH4 from 47.1 to 50 ° C under 791 kPa for H2 / CH4 separation. This NPI-1 polyimide membrane contains UV crosslinkable sulfonic groups.
    [0021] Another polyimide membrane described in the present invention is made from -3.3 ', 4,4'-tetracarboxylic diphenylsulfone poly (3,3', 2,4'-biphenyl tetracarboxylic dianhydride , 6 - trimethyl-m-phenylenediamine -3,3 ', 5,5'-tetramethyl-4,4'-methylene dianiline) polyimide (abbreviated as NPI-2), which is derived from the DSDA polycondensation reaction and 3, 3 ', 4.4' - tetracarboxylic biphenyl dianhydride (BPDA) with 3.3 ', 5.5'-tetramethyl- 4.4' - methylene dianiline (TMMDA) and TMPDA (DSDA: BPDA: TMMDA: TMPDA = 3, 06: 1.02: 2.00: 2.00 (molar ratio)). Pure gas permeation results showed that this NPI-2 membrane has an intrinsic CO2 permeability of 57.5 Barrers and single gas selectivity for CO2 / CH4 from 20.2 to 50 ° C under 791 kPa for CO2 separation / CH4. This membrane also has intrinsic H2 permeability of 109.9 Barrers and single gas selectivity for H2 / CH4 from 38.6 to 50 ° C under 791 kPa for H2 / CH4 separation. This NPI-2 membrane contains UV-crosslinkable sulfonic groups.
    [0022] However, another polyimide membrane, which forms part of the present invention, is manufactured from poly (3,3 ', 4,4'-tetracarboxylic benzophenone - pyromelitic dianhydride - 2,4,6-trimethyl-m-phenylenediamine ) polyimide (abbreviated as NPI-3), which is derived from the polycondensation reaction of 3,3 ', 4,4'-tetracarboxylic benzophenone dianhydride (BTDA) and pyromelitic dianhydride (PMDA) with TMPDA (BTDA: PMDA: TMPDA = 2.04: 2.04: 4.00 (molar ratio)). Pure gas permeation results showed that this NPI-3 membrane has an intrinsic CO2 permeability of 179 Barrers and single gas selectivity for CO2 / CH4 from 15.8 to 50 ° C under 791 kPa for CO2 / CH4 separation. This membrane also has intrinsic H2 permeability of 256.5 Barrers and single gas selectivity for H2 / CH4 from 22.7 to 50 ° C under 791 kPa for H2 / CH4 separation. This NPI-3 membrane contains UV-crosslinkable carbonyl groups.
    [0023] However, another polyimide membrane, which is part of the present invention, is manufactured from poly (3,3 ', 4,4'-tetracarboxylic benzophenone - pyromelitic dianhydride -2,4,6-trimethyl-m-phenylenediamine -3,3 ', 5,5'-tetramethyl-4,4'-methylene dianiline) polyimide (abbreviated as NPI-4), which is derived from the polycondensation reaction of BTDA and PMDA with TMPDA and TMMDA (BTDA: DMPA: TMPDA: TMMDA = 2.04: 2.04: 2.00: 2.00 (molar ratio)). Pure gas permeation results showed that this NPI-4 membrane has an intrinsic CO2 permeability and 97.0 Barrers single gas selectivity for CO2 / CH4 from 17.1 to 50 ° C under 791 kPa for CO2 / CH4 separation . This membrane also has intrinsic H2 permeability of 159.5 Barrers and single gas selectivity for H2 / CH4 from 28.2 to 50 ° C under 791 kPa for H2 / CH4 separation. This NPI-4 membrane contains UV crosslinkable carbonyl groups.
    [0024] In some cases, the high performance polyimide membranes described in the present invention have been subjected to an additional crosslinking step, by chemical or UV crosslinking or other crosslinking process as known to a person skilled in the art. A cross-linked polyimide membrane can be prepared by UV cross-linking of the polyimide membrane by exposing the membrane to UV radiation. The polyimide polymers used for the preparation of polyimide membranes described in the present invention have UV-crosslinkable sulfonic (-SO2 -) or carbonyl (-C (O) -) groups. Cross-linked polyimide membranes comprise segments of the polymer chain where at least part of the segments of the polymer chain are cross-linked to each other through possible direct covalent bonds upon exposure to UV radiation. The cross-linking of polyimide membranes provides the membranes with better selectivities and decreased permeations compared to the corresponding non-cross-linked polyimide membranes. The UV-crosslinked polyimide membranes described in the present invention have the CO2 permeability of 20 Barrers or greater and single gas selectivity for CO2 / CH4 of 35 or greater at 50 ° C under 791 kPa for CO2 / CH4 separation.
    [0025] The optimization of the degree of crosslinking in the UV crosslinked polyimide membrane described in the present invention, should promote the making of membranes for a wide range of gas and liquid separations with improved permeation properties and environmental stability. The degree of crosslinking of the UV crosslinked polyimide membrane of the present invention can be controlled by adjusting the distance between the UV lamp and the membrane surface, the UV radiation time, wavelength and the intensity of the UV light, etc. Preferably, the distance between the UV lamp and the membrane surface is in the range of 0.8 to 25.4 centimeters (0.3 to 10 inches), with a UV light provided from the low-mercury arc lamp. pressure or average pressure from 12 watt to 450 watt, and the UV radiation time is in the range of 0.5 minutes to 1 hour. Most preferably, the distance between the UV lamp and the membrane surface is in the range of 1.3 to 5.1 cm (0.5 to 2 inches) with a UV light supplied from the low-mercury arc lamp pressure or average pressure from 12 watts to 450 watts, and the UV radiation time is in the range of 1 to 40 minutes.
    [0026] As an example, UV crosslinked NPI-4 membrane is prepared by additional UV crosslinking of the UV crosslinked NPI-4 membrane, using a UV lamp from a certain distance, and for a selected period of time with based on the separation properties seen. For example, the UV-crosslinked NPI-4 membrane can be prepared from the NPI-4 membrane by exposure to UV radiation using 254 nm wavelength ultraviolet light generated by a 1.9 cm UV lamp ( 0.75 inches) away from the membrane surface to the UV lamp and an irradiation time of 10 minutes at 50 ° C. The UV lamp described here is a 12 watt low pressure mercury arc UV quartz lamp with a 12 watt power supply from Ace Glass Incorporated. Pure gas permeation results showed that the UV-crosslinked NPI-4 membrane has an intrinsic CO2 permeability of 39.3 Barrers and single gas selectivity for CO2 / CH4 from 41.2 to 50 ° C under 791 kPa for separation CO2 / CH4. This UV crosslinked NPI-4 membrane also has intrinsic H2 permeability of 149.8 Barrers and single gas selectivity for H2 / CH4 of 156.8 at 50 ° C under 791 kPa for H2 / CH4 separation. These results indicate that the UV-crosslinked NPI-4 membrane significantly increased the selectivity of single gas for CO2 / CH4 and the selectivity of single gas for H2 / CH4 over the non-cross-linked NPI-4 membrane.
    [0027] The polyimide polymers used to make the polyimide membrane with high permeations and high selectivities described in the present invention can comprise a plurality of first repeating units of general formula (I):
    where XI is selected from the group consisting of
    and mixtures thereof; X2 is selected from the group consisting of
    and mixtures thereof. Y is selected from the group consisting of
    and mixtures of the same enemies are independent integers from 2 to 500.
    [0028] The polyimide polymers used to make the polyimide membrane with high permeations and high selectivities described in the present invention have a weight average molecular weight in the range of 50,000 to 1,000,000 Daltons, preferably between 70,000 and 500,000 Daltons.
    [0029] Some examples of polyimide polymers used to make the polyimide membrane with high permeations and high selectivities described in the present invention may include, but are not limited to, tetracarboxylic poly (3,3 ', 4,4'-dianhydride diphenylsulfone - 2,4,6-trimethyl-m-phenylenediamine) polyimide (abbreviated as NPI-1) derived from the 3,3 ', 4,4'-diphenylsulfone tetracarboxylic (DSDA) polycondensation reaction with 2,4,6-trimethyl -m-phenylenediamine (TMPDA), poly (3,3 ', 4,4'-diphenylsulfone tetracarboxylic -3,3', 4,4'-biphenyl tetracarboxylic - 2,4,6-trimethyl-m-phenylenediamine - 3,3 ', 5,5'-methylene 4,4'-dianiline) polyimides derived from the DSDA polycondensation reaction and 3,3', 4,4'-tetracarboxylic biphenyl dianhydride (BPDA) with 3.3 ', 5,5'-tetramethyl- 4,4'-methylene dianiline (TMMDA) and TMPDA (abbreviated as NPI-2 when DSDA: BPDA: TMMDA: TMPDA = 3.06: 1.02: 2.00: 2, 00 (molar ratio) and abbreviated as NPI -5 when o DSDA: BPDA: TMMDA: TMPDA = 2.04: 2.04: 1.00: 3.00 (molar ratio)), poly (3.3 ', 4,4'-tetracarboxylic benzophenone dianhydride - pyromelitic dianhydride -2 , 4,6-trimethyl-m-phenylenediamine) polyimides derived from the 3,3 'polycondensation reaction, 4,4'-tetracarboxylic benzophenone (BTDA) and pyromelitic dianhydride (PMDA) with TMPDA (abbreviated as NPI-3 when BTDA: PMDA: TMPDA = 2.04: 2.04: 4.00 (molar ratio) and abbreviated as NPI -6 when BTDA: PMDA: TMPDA = 2.45: 1.63: 4.00 (molar ratio)) , poly (3,3 ', 4,4'-tetracarboxylic benzophenone dianhydride - pyromelitic dianhydride -2,4,6-trimethyl-m-phenylenediamine -3,3', 5,5'-tetramethyl- 4,4'-methylene dianiline) polyimide (abbreviated as NPI -4) derived from the polycondensation reaction of BTDA PMDA with TMPDA and TMMDA (BTDA: PMDA: TMPDA: TMMDA = 2.04: 2.04: 2.00: 2.00 (molar ratio) ).
    [0030] The polyimide membranes described in the present invention can be manufactured in any convenient geometry, such as flat sheet (or spiral wound), tube, or hollow fiber.
    [0031] The present invention also involves the combined polymer membranes comprising the polyimide polymers used to make the polyimide membrane with high permeations and high selectivities described in the present invention. In some embodiments of the invention, the combined polymer membranes comprising the polyimide polymers used to make the polyimide membrane with high permeations and high selectivities described in the present invention can be subjected to an additional cross-linking step to increase the selectivity of the membrane.
    [0032] The term "combined polymer membranes" in the present invention refers to a membrane prepared from a combination of two or more polymers. The combined polymer membrane comprising the polyimide polymers used to make the high permeation and high selectivity polyimide membrane described in the present invention contains a combination of two or more polymers, wherein at least one polymer is a polyimide polymer described in present invention.
    [0033] In some cases, it is desirable to crosslink the combined polymer membrane to improve the selectivity of the membrane. The crosslinked combined polymer membrane described in the present invention is prepared by UV crosslinking of the combined polymer membrane comprising at least one polyimide polymer used to make the high permeation and high selectivity polyimide membranes described in the present invention. After UV crosslinking, the crosslinked combined polymer membrane comprises the segments of the polymer chain, in which at least a part of these segments of the polymer chain are cross-linked to each other through possible direct covalent bonds upon exposure to UV radiation. The crosslinking of the mixing polymer membranes offers the membranes superior selectivity and improved thermal and chemical stability than the corresponding unbound combined polymer membranes comprising at least one polyimide polymer used to make the polyimide membranes with high permeations and high selectivities described in the current invention.
    [0034] The second polymer in the combined polymer membrane comprising the polyimide polymers described in the present invention can be selected from, but is not limited to, polysulfones; sulfonated polysulfones; polyethersulfones; sulfonated polyethersulfones, and polyvinylpyrrolidones. The invention provides a process for separating at least one gas from a mixture of gases, using the new high permeation and high selectivity polyimide membranes described in the present invention, the process comprising: (a) providing a polyimide membrane with high permeability and high selectivity described in the present invention, which is permeable to at least one gas; (b) contacting the mixture on one side of the asymmetric polyimide membrane with high permeability described in the present invention to cause at least one gas to permeate the membrane; and (c) removing from the opposite side of the membrane a composition of the permeate gas comprising a portion of at least one gas which permeated the asymmetric polyimide membrane.
    [0035] The polyimide membranes with high permeations and high selectivities described in the present invention are especially useful in the purification, separation or adsorption of a particular species in the liquid or gaseous phase. In addition to the separation of the gas pairs, these high permeation and high selectivity polyimide membranes described in the present invention can, for example, be used for the desalination of water by reverse osmosis, or for the separation of proteins or other thermally unstable compounds , for example, in the pharmaceutical and biotechnology industries. The polyimide membranes with high permeations and high selectivities described in the present invention can also be used in fermenters and bioreactors to transport gases into the reaction vessel and transfer the cell culture medium out of the vessel. In addition, these polyimide membranes with high permeations and high selectivities described in the present invention can be used for the removal of microorganisms from drafts or water, in the purification of water, and in the production of ethanol in a membrane pervaporation system / continuous fermentation, and in the detection or removal of trace compounds or metal salts in air or water currents.
    [0036] Polyimide membranes with high permeations and high selectivities described in the present invention are especially useful in gas separation processes in air purification, petrochemical, refinery, and in the natural gas industries. Examples of such separations include the separation of volatile organic compounds (such as toluene, xylene, and acetone) from an atmospheric gas, such as nitrogen or oxygen and recovery of nitrogen from the air. Other examples of such separations are for the separation of CO2 or H2S from natural gas, Fka from N2, CH4, and Ar, in ammonia purge gas streams, the recovery of H2 in refineries, olefin / paraffin separations such as propylene / propane separation and normal isoparaffin / paraffin separations. Any given pair or group of gases that differ in molecular size, for example, nitrogen and oxygen, carbon dioxide and methane, hydrogen and methane or carbon monoxide, helium and methane, can be separated through high permeation polyimide membranes described in the present invention. More than two gases can be removed from a third gas. For example, some of the gas components that can be selectively removed from a raw natural gas using the membrane described here include carbon dioxide, oxygen, nitrogen, water vapor, hydrogen sulfide, helium and other waste gases. Some of the gas components that can be selectively retained include hydrocarbon gases. When permeable components are acidic components selected from the group consisting of carbon dioxide, hydrogen sulfide and mixtures thereof and are removed from a mixture of hydrocarbons, such as natural gas, one module or at least two in service in parallel, or a series of modules can be used to remove acidic components. For example, when a module is used, the supply gas pressure can vary between 275 kPa to 7.5 MPa (25 to 4000 psig). The differential pressure across the membrane can be as low as 70 kPa or as high as 14.5 MPa (or as high as 2100 psi), depending on many factors, such as the particular membrane used, the flow of the incoming current and the availability of a compressor to compress the permeate current, if such compression is desired. A differential pressure greater than 14.5 MPa (2100 psi) can break the membrane. A differential pressure of at least 0.7 MPa (100 psi) is preferred since lower differential pressures may require more modules, more time and compression of the intermediate product streams. The operating temperature of the process may vary depending on the temperature of the supply chain and the ambient temperature conditions. Preferably, the effective operating temperature of the membranes of the present invention will vary between -50 ° to 150 ° C. More preferably, the effective operating temperature of the high permeation polyimide membranes of the present invention will vary from -20 ° C to 100 ° C, and more preferably, the effective operating temperature of the membranes of the present invention will vary from 25 ° at 100 ° C.
    [0037] The polyimide membranes with high permeations and high selectivities described in the present invention are also especially useful in gas / vapor separation processes in the chemical, petrochemical, pharmaceutical and allied industries for the removal of organic vapors from streams. gas, for example, in the treatment of gaseous effluents for the recovery of volatile organic compounds to comply with clean air regulations, or within process streams in production facilities so that high value compounds (for example, vinyl chloride, propylene) can be recovered. Other examples of gas / vapor separation processes, in which the polyimide membranes with high permeations and high selectivities and described in the present invention can be used are separation of hydrocarbon vapor from hydrogen in oil and gas refineries, to natural gas hydrocarbon dew (ie, to lower the hydrocarbon dew point below the lowest possible temperature of the export pipeline so that liquid hydrocarbons do not separate in the pipeline), to control the number of methane in fuel gas for gas engines and gas turbines, and gasoline recovery. The polyimide membranes with high permeations and high selectivities described in the present invention can incorporate a species that strongly absorbs certain gases (for example, porphyrins, phthalocyanines or O2 or silver (I) for ethane) to facilitate their transport across the membrane.
    [0038] The polyimide membranes with high permeations and high selectivities described in the present invention also have immediate application to the concentration of olefins in a paraffin / olefin stream for an olefin cracking application. For example, the polyimide membranes with high permeations and high selectivities described in the present invention can be used for the separation of propylene / propane to increase the concentration of the effluent, in a catalytic dehydrogenation reaction for the production of propylene from propane and isobutylene from isobutane. Therefore, the number of phases of the propylene / propane divider that is required to obtain polymer-grade propylene can be reduced. Another application for the polyimide membranes with high permeations and high selectivities described in the present invention, is for the separation of normal paraffin and isoparaffin in the isomerization of light paraffin and MaxEne ™, a process to increase the concentration of normal paraffins (n-paraffin) in the feed charge of the naphtha cracker, which can then be converted into ethylene.
    [0039] The polyimide membranes with high permeations and high selectivities described in the present invention can also be operated at an elevated temperature to provide sufficient dew point margin for the processing of natural gas (for example, the removal of CO2 from natural gas). The polyimide membranes with high permeations and high selectivities described in the present invention can be used either in a single-phase membrane or as the first and / or second phase membrane in a two-phase membrane system for the processing of natural gas. The polyimide membranes with high permeations and high selectivities described in the present invention have a high selectivity, high permeation, high mechanical stability and high thermal and chemical stability that allow the membranes to be operated without an expensive pre-treatment system. Due to the elimination of the pretreatment system and the significant reduction of the membrane area, the new process can achieve significant capital cost savings and reduce the existing membrane area.
    [0040] These polyimide membranes with high permeations and high selectivities described in the present invention can also be used in the separation of liquid mixtures by pervaporation, as well as in the removal of organic compounds (for example, alcohols, ethers, chlorinated hydrocarbons, pyridines, ketones) from water, such as aqueous effluents or process fluids. A membrane that is selective for ethanol would be used to increase the concentration of ethanol in relatively diluted ethanol solutions (5 - 10% ethanol), obtained by fermentation processes. Another example of liquid phase separation using these high permeation and high selectivity polyimide membranes described in the present invention is the deep desulfurization of diesel fuel and gasoline using a pervaporation membrane process similar to the process described in US 7,048,846, incorporated herein by reference in its entirety. The polyimide membranes with high permeations and high selectivities described in the present invention, which are selective for sulfur-containing molecules would be used to selectively remove sulfur-containing molecules from fluid catalytic cracking (FCC) and other naphtha hydrocarbon streams. Other examples of liquid phases include the separation of an organic component from another organic component, for example, to separate the isomers from organic compounds. Mixtures of organic compounds that can be separated using the high permeation polyimide membranes described in the present invention include: ethyl acetate - ethanol, diethyl ether - ethanol, acetic acid - ethanol, benzene - ethanol, chloroform - ethanol, chloroform-methanol , acetone-isopropyl ether, allyl alcohol - allyl ether, allyl alcohol - cyclohexane, butanol - buryl acetate, butanol - 1-butyl ether, ethanol - ethyl butyl ether, propyl acetate - propanol, isopropyl ether - isopropanol, methanol - ethanol - isopropanol and ethyl acetate - ethanol - acetic acid. EXAMPLES
    [0041] The following examples are presented to illustrate one or more preferred embodiments of the invention, but are not limited to embodiments thereof. Numerous variations can be made for the following examples that are within the scope of the invention. EXAMPLE 1 Preparation of dense polyimide film membrane using poly (3,3 ', 4,4'-diphenylsulfone tetracarboxylic -2,4,6-trimethyl-m-phenylenediamine) polyimide (NPI-1)
    [0042] An aromatic poly (3,3 ', 4,4'-diphenylsulfone tetracarboxylic -2,4,6-trimethyl-m-phenylenediamine) polyimide (abbreviated as NPI-1), containing UV crosslinkable sulfonic groups has been synthesized from 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride (DSDA) and 2,4,6-trimethyl-m-phenylenediamine (TMPDA) in polar solvent DMAc by a two-step process involving the formation of poly ( ammic acid) followed by a solution imidization process. Acetic anhydride was used as the dehydrating agent and pyridine was used as an imidization catalyst for the solution imidization reaction. For example, in a 250 ml three-neck round-bottom flask equipped with a nitrogen inlet and a mechanical stirrer, it was loaded with 10.5 g of TMPDA and 42 g of DMAc. Once TMPDA was completely dissolved, 25.8 g of solid DSDA powder was added to the TMPDA solution gradually with agitation in the flask. 50 g of dimethylacetamide (DMAc) was added to the solution, after the TMPDA powder was added. The reaction mixture was mechanically stirred for 24 hours at room temperature, to provide a viscous solution of poly (amic acid). Then, 14.7 g of acetic anhydride were added slowly to the reaction mixture under stirring, followed by the addition of 22.8 g of pyridine, to the reaction mixture. The reaction mixture was mechanically stirred for an additional 2.0 hours at 90 ° C to obtain a polyimide designated as NPI-1, for the purpose of the present application. The NPI-1 product in a fine fiber form was recovered by slowly precipitating the reaction mixture in a large amount of methanol and acetone mixture with a 1: 1 volume ratio. The resulting NPI-1 polyimide fibers were then carefully washed with methanol and dried in a vacuum oven at 100 ° C for 24 hours.
    [0043] The NPI -1 polymer dense film membrane was prepared as follows: 12.0 g of NPI-1 polyimide was dissolved in a solvent mixture of 19.5 g of NMP and 13.7 g of 1 , 3-dixolane. The mixture was mechanically stirred for 2 hours to form a homogeneous solution to be spun for molding. The resulting homogeneous solution for molding was filtered and allowed to degas overnight. The NPI -1 polymer dense film membrane was prepared from the solution to be spun for bubble-free molding on a clean glass plate with a scraper knife with a 20 mil (508 pm) slit. The membrane together with the glass plate was then placed in a vacuum oven. The solvents were removed by slowly increasing the vacuum and the temperature of the vacuum oven. Finally, the membrane was dried at 200 ° C under vacuum for at least 48 hours to completely remove residual solvents to form a dense film polymer membrane. EXAMPLE 2 Evaluation of the separation performance of CO2 / CH4 and H2 / CH4 of the NPI-1 membrane prepared in Example 1
    [0044] The NPI-1 membrane in the form of dense film was tested for separations of CO2 / CH4 and H2 / CH4 at 50 ° C under 791 kPa (100 psig) of pure gas supply pressure. The results show that the new NPI-1 membrane has an intrinsic CO2 permeability of 73.4 Barrers (Barrer 1 = 10 10 cm3 (STP) cm / cm2 s (cm Hg)) and single gas selectivity for CO2 / CH4 of 25 , 3 to 50 ° C under 791 kPa for CO2 / CH4 separation. This membrane also has intrinsic H2 permeability of 136.6 Barrers and single gas selectivity for H2 / CH4 from 47.1 to 50 ° C under 791 kPa for H2 / CH4 separation. EXAMPLE 3 Preparation of the NPI-1 polyimide hollow fiber membrane using NPI-1 polyimide prepared in Example 1
    [0045] A solution to be spun for hollow fiber spinning, containing 29.7 g of NPI-1 polyimide from Example 1, 62.86 g of NMP, 8.48 g of 1.3 - dioxolane, 2.51 g of isopropanol, and 2.51 g of acetone was prepared, solution to be spun for spinning was extruded at a flow rate of 2.6 mL / min through a spinneret at 50 ° C spinning temperature. An orifice fluid containing 10% by weight of water in NMP was injected into the orifice of the fiber at a flow rate of 0.8 mL / min, simultaneously with the extrusion of the solution to be spun for spinning. The nascent fiber moved through an air gap length of 5 cm at room temperature with a humidity of 25%, and then was immersed in a water coagulant bath at 21 ° C and wound at a rate of 8.0 m / min. The fiber wetted in water was annealed in a hot water bath at 85 ° C for 30 minutes. The fiber moistened in annealed water was then replaced sequentially with methanol and hexane, three times and for 30 minutes each time, followed by drying at 100 ° C in an oven for 1 hour to form the hollow NPI-1 fiber membrane. . EXAMPLE 4
    [0046] Synthesis of poly (3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride - 3,3', 4,4'-biphenyl tetracarboxylic dianhydride - 2,4,6-trimethyl-m-phenylenediamine -3,3 ', 5,5'-tetramethyl-4,4' - methylene dianiline) (referred to as NPI-2)
    [0047] An aromatic polyimide, poly (3,3 ', 4,4'-diphenylsulfone tetracarboxylic -3,3', 4,4'-biphenyl tetracarboxylic -2,4,6-trimethyl-m-phenylenediamine -3 , 3 ', 5,5'-tetramethyl- 4,4'-methylene dianiline) (referred to as NPI-2) containing UV-crosslinkable sulfonic groups, was synthesized by DSDA and 3.3' polycondensation reaction, 4.4 '-biphenyl tetracarboxylic dianhydride (BPDA) with 3,3', 5,5'-tetramethyl -4,4 '-methylene dianiline (TMMDA) and TMPDA (DSDA: BPDA: TMMDA: TMPDA = 3.06: 1.02: 2.00: 2.00 (molar ratio)) in a polar DMAc solvent. A 500 ml three-neck round-bottom flask equipped with a nitrogen inlet and a mechanical stirrer was loaded with 17.8 g of TMMDA, 10.5 g of TMPDA, and 60 g of DMAc. Once TMMDA and TMPDA were fully dissolved, 38.3 g of DSDA and 10.5 g of solid BPDA powder were added to the TMMDA and TMPDA solution gradually, with agitation in the flask. 40 g of DMAc was added to the solution, then DSDA and BPDA powder was added. Another 30 g of DMAc was added after 10 minutes. The reaction mixture was then heated to 70 ° C to completely dissolve the powder. Another 130 g of DMAc was added to the reaction mixture after being heated to 70 ° C for 0.5 hours. The reaction mixture was then cooled to room temperature and was mechanically stirred for 24 hours at room temperature, to provide a viscous solution of poly (amic acid). Then, 31.4 g of acetic anhydride were added slowly to the reaction mixture with stirring, followed by the addition of 48.7 g of pyridine, to the reaction mixture. The reaction mixture was mechanically stirred for an additional 2 hours at 90 ° C to produce NPI-2. The polyimide product NPI-2 in the form of fine fiber was recovered by slow precipitation of the reaction mixture in a large amount of methanol. The resulting NPI-2 polyimide fibers were then carefully washed with methanol and dried in a vacuum oven at 100 ° C for 24 hours. EXAMPLE 5 Preparation of 2- NPI dense film membrane
    [0048] The NPI-2 dense film membrane was prepared as follows: 7.0 g of NPI-2 polyimide was dissolved in a solvent mixture of 15.5 g of NMP and 12.5 g of 1.3 -dioxolane. The mixture was mechanically stirred for 2 hours to form a homogeneous solution to be spun for molding. The resulting homogeneous solution for molding was filtered and allowed to degas overnight. The NPI-2 dense film membrane was prepared from the solution to be spun for bubble-free molding on a clean glass plate with a scraper knife with a difference of 20 mil (508 p, m). The dense film, together with the glass plate, was then placed in a vacuum oven. The solvents were removed by slowly increasing the vacuum and the temperature of the vacuum oven. Finally, the dense film was dried at 200 ° C under vacuum for at least 48 hours to completely remove residual solvents to form the NPI-2 dense film membrane. EXAMPLE 6 Preparation of UV crosslinked NPI-2 dense film membrane
    [0049] The NPI-2 dense film membrane prepared in Example 5 was further crosslinked by UV by exposure to UV radiation using UV light of 254 nm wavelength, generated by a 1.9 cm (0 cm) UV lamp. , 75 inches) away from the surface of the NPI-3 dense film membrane to the UV lamp and a radiation time of 10 minutes at 50 ° C. The UV lamp described here is a 12 watt low pressure mercury arc UV quartz lamp with a 12 watt power supply from Ace Glass Incorporated. EXAMPLE 7 Synthesis of poly (3,3 ', 4,4'-tetracarboxylic benzophenone dianhydride - pyromellitic dianhydride -2,4,6-trimethyl-m-phenylenediamine) (referred to as NPI-3)
    [0050] An aromatic polyimide, poly (3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride - pyromelitic -2,4,6-trimethyl-m-phenylenediamine dianhydride) (referred to as NPI-3) containing carbonyl groups cross-linked by UV was synthesized by polycondensation reaction of 3,3 ', 4,4'-tetracarboxylic benzophenone dianhydride (BTDA) and pyromelitic dianhydride (PMDA) with TMPDA (BTDA: PMDA: TMPDA = 2.04: 2.04: 4.00 (molar ratio)) in polar NMP solvent. The synthesis procedure for NPI-3 was the same as that described in Example 4 for NPI-2, except that different monomers and solvent were used for the synthesis of NPI-3. EXAMPLE 8 Preparation of NPI-3 dense film membrane
    [0051] The NPI-3 dense film membrane was prepared using a procedure similar to that described in Example 5, except that the polymer used to make the dense film membrane is NPI-3. EXAMPLE 9 Preparation of UV-crosslinked NPI-3 dense film membrane
    [0052] The NPI-3 dense film membrane prepared in Example 8 was further crosslinked by UV using 254 nm wavelength UV light, generated by a 1.9 cm (0.75 inch) distance UV lamp from the dense NPI-3 film surface to the UV lamp and a radiation time of 10 minutes at 50 ° C. The UV lamp described here is a 12 watt low pressure mercury arc immersion quartz UV lamp with a 12 watt power supply from Ace Glass Incorporated. EXAMPLE 10 CO2 / CH4 H2 / CH4 separation properties of dense film membranes
    [0053] The permeability of CO2, H2 and CH4 (Pco2, PH2, and Pcm) and selectivity of CO2 / CH4 (αco2 / CH4) and H2 / CH (αm / cm) of the dense film membranes prepared in Examples 5, 6 , 8 and 9, respectively, were measured by means of pure gas measurements, at 50 ° C under 790 kPa (100 psig) of pressure. The results are shown in Table 1. TABLE 1
    [0054] Results of pure gas permeation tests of dense film membranes for CO2 / CH4 and H2 / CH4 separations
    “Tested at 50 ° C under 790 kPa (100 psig (689.5 kPa)) of pure gas pressure; Barrer 1 = 10 10 (cm3 (STP) cm) / (cm2.s.cmHg) EXAMPLE 11 Preparation of NPI-2 hollow fiber membranes
    [0055] A polymer spun solution consisting of 52.1 g of N-methylpyrrolidinone (NMP), 7.0 g of 1,3-dioxolane, 2.1 g of 2-propanol, 2.1 g of acetone and 23.4 g of NPI-2 polyimide synthesized in Example 4 was mixed until uniform. The viscosity of this solution to be spun was 280,000 cP at 30 ° C. This solution to be spun was extruded from the circular crown of a hollow fiber die, with a flow rate in the range of 0.7 and 3.0 ml / min. At the same time, an orifice solution of 10% by weight of H2O / 90% by weight of NMP flowed from the inner passage of the die at 0.4 to 0.8 ml / min to prevent the nascent fiber from collapsing into yourself. During extrusion, the solution to be spun and the spinneret were controlled at 50 ° C. The nascent fiber passed through a 3 to 10 cm air gap and then inserted in a water coagulation bath at 4 ° C to allow the liquid-liquid to be mixed and the asymmetric porous portion of the fiber membrane to form the CA. Finally, the solidified hollow fiber membrane was wound in a pickup drum partially submerged in water at room temperature at 8 to 37 m / min. The resulting NPI-2 hollow fiber membranes had a selective dense layer on the outer surface of the fibers.
    [0056] The newly formed hollow fibers were treated in water at 85 ° C for 30 minutes, then, soaked in a water bath at room temperature overnight. Then, the fibers were submerged in three successive volumes of methanol, for 30 minutes each, followed by submersion in three successive volumes of hexane, for 30 minutes each. These steps were carried out to remove residual solvents from the fibers. Then, the fibers were dried for 1 hour at 100 ° C, and then bundles of fibers were sealed in modules for gas permeation tests. Details of the specific conditions used for each NPI-2 hollow fiber membrane are shown in Table 2. EXAMPLE 12 Preparation of NPI-3 hollow fiber membranes
    [0057] A spun polymer solution consisting of 62.6 g of NMP, 8.5 g of 1,3-dioxolane, 2.5 g of 2-propanol, 2.5 g of acetone and 24.0 g of NPI-3 polyimide synthesized in Example 7 was mixed until uniform. The viscosity of this solution to be spun was 300,000 cP at 30 ° C. This solution to be spun was extruded from the ring of a hollow fiber membrane die, with a flow rate in the range of 0.7 and 3.0 ml / min. At the same time, an orifice solution of 10% by weight of H2O / 90% by weight of NMP flowed from the inner passage of the die at 0.4 to 0.8 ml / min to prevent the nascent fiber from collapsing into yourself. During extrusion, the solution to be spun and the spinneret were controlled at 50 ° C. The nascent fiber is passed through a 3 to 10 cm air gap and then inserted into a water coagulation bath at 3 ° C. Finally, the solidified hollow fiber membrane was wound in a pickup drum partially submerged in water at room temperature at 8 to 30 m / min. The resulting membranes had a selective dense layer on the outer surface of the fibers. Details of the specific conditions used for each of the NPI-3 hollow fiber membranes are shown in Table 3.
    [0058] A second solution to be spun of polymer consisting of 70.5 g of NMP, 3.5 g of 2-propanol, 1.2 g of lactic acid, and 22.5 g of NPI-3 synthesized in Example 7 was mixed until uniform. The viscosity of this solution to be spun was 210,000 cP at 30 ° C. This solution to be spun was extruded from the ring of a hollow fiber membrane die, with a flow rate between 0.7 and 3.0 ml / min. At the same time, an orifice solution of 10% by weight of H2O / 90% by weight of NMP flowed from the inner passage of the die at 0.4 to 0.8 ml / min to prevent the nascent fiber from collapsing into yourself. During extrusion, the solution to be spun and the spinneret were controlled at 50 ° C. The nascent fiber is passed through a 3 to 10 cm air gap and then inserted in a 5 ° C water coagulation bath. Finally, the solidified hollow fiber membrane was wound in a pickup drum partially submerged in water at room temperature at 8 to 37 m / min. The resulting NPI-3 hollow fiber membranes had a selective dense layer on the outer surface of the fibers. Details of the specific conditions used for each of the hollow fiber membranes are shown in Table 4.
    [0059] The newly formed hollow fibers from each set of membranes were treated in water at 85 ° C for 30 minutes, then, soaked in a water bath at room temperature overnight. Then, the fibers were submerged in three successive volumes of methanol, for 30 minutes each, followed by submersion in three successive volumes of hexane, for 30 minutes each. Then, the fibers were dried for 1 hour at 100 ° C, and then bundles of fibers were sealed in modules for gas permeation tests. EXAMPLE 13 CO2 / CH4 separation properties of NPI-2 polyimide hollow fiber membranes
    [0060] Polyimide hollow fiber membranes prepared from INP -2 polyimide in Example 11 were tested for single gas permeation of CO2 and CH4, at 50 ° C, with feed at 790 kPa (100 psig) and the permeate at 101 kPa (0 psig). Performance of these membranes is shown in Table 2, along with the unique manufacturing conditions for each membrane. Other manufacturing conditions for these membranes were described in Example 11. All of the hollow NPI-2 polyimide fiber membranes shown in Table 2 were practically free of defects and had CO2 / CH4 selectivities close to or greater than the intrinsic selectivity of the film membrane dense NPI-2. TABLE 2 Performance of single gas permeation for CO2 / CH4 of NPI-2 hollow fiber membranes.
    (1 AU = 1 ft3 (STP) / h • ft2 • 100 psi) EXAMPLE 14 CO2 / CH4 separation properties of NPI-3 hollow fiber membranes
    [0061] Polyimide hollow fiber membranes prepared from INP - 3 of Example 12 were tested for permeation of single gas of CO2 and CH4, at 50 ° C, with feed at 790 kPa (100 psig) and the permeate at 101 kPa (0 psig). Two different sets of NPI-3 hollow fiber membranes were prepared using different formulations of the solution to be spun, as described in Example 12. The performance of these membranes is shown in Tables 3 and 4, together with the unique manufacturing conditions for each membrane. Other manufacturing conditions for these membranes were described in Example 12. All of the hollow NPI-3 polyimide fiber membranes shown in Tables 3 and 4 were almost free from defects and had higher CO2 / CH4 selectivities than the intrinsic selectivity of fiber membranes hollow NPI-2. TABLE 3 Single gas permeation performance for CO2 / CH4 of NPI-3 hollow fiber membranes prepared using a spun solution of 62.6 g of NMP, 8.5 g of 1.3-dixolane, 2.5 g of 2-propanol, 2.5 g of acetone and 24.0 g of NPI-3 polyimide.
    (1 AU = 1 ft3 (STP) / h • ft2. 100psi) TABLE 4 Single gas permeation performance for CO2 / CH4 of NPI-3 hollow fiber membranes prepared using a 70.5 g solution to be spun. NMP, 3.5 g of 2-propanol, 1.2 g of lactic acid and 22.5 g of NPI-3.
    (1 AU = 1 ft3 (STP) / h • ft2 • 100 psi) EXAMPLE 15 Preparation of the NPI-2 / PES combination dense film membrane
    [0062] A dense film membrane of combined polymers of NPI-2 polyimide and polyethersulfone (PES) was prepared as follows: 3.5 g of NPI-2 polyimide and 3.5 g of PES were dissolved in a mixture of solvent of 15.5 g of NMP and 12.5 g of 1,3-dioxolane. The mixture was mechanically stirred for 2 hours to form a homogeneous solution to be spun for molding. The resulting homogeneous solution for molding was filtered and allowed to degas overnight. The NPI-2 / PES combination dense film membrane was prepared from the solution to be spun for bubble-free molding on a clean glass plate with a scraper knife with a 20 mil (508 µm) slit. The dense film, together with the glass plate, was then placed in a vacuum oven. The solvents were removed, slowly increasing the vacuum and the temperature of the vacuum oven. Finally, the dense film was dried at 200 ° C under vacuum for at least 48 hours to completely remove residual solvents to form the NPI-2 / PES combination dense film membrane.
    权利要求:
    Claims (9)
    [0001]
    1. Polyimide membrane, characterized by the fact that it comprises an aromatic polyimide polymer comprising a plurality of first repeating units of formula (I)
    [0002]
    2. Polyimide membrane according to claim 1, characterized by the fact that it additionally comprises polyethersulfone.
    [0003]
    3. Separation process for separating two or more substances, characterized by the fact that it uses the polyimide membrane as defined in either of claims 1 or 2.
    [0004]
    Process according to claim 3, characterized in that the separation process separates one or more organic compounds from water.
    [0005]
    5. Process according to claim 4, characterized by the fact that the separation process is a pervaporation process to remove sulfur from diesel fuel or gasoline.
    [0006]
    Process according to claim 3, characterized in that the separation process separates at least one first organic compound from a second organic compound.
    [0007]
    7. Process according to claim 3, characterized by the fact that the separation process is a desalination of water by reverse osmosis.
    [0008]
    Process according to claim 3, characterized in that the two or more substances comprise a mixture of gases.
    [0009]
    Process according to claim 8, characterized in that the gas mixture includes at least one gas selected from carbon dioxide and hydrogen sulfide, which is mixed with methane.
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    RU2556666C2|2015-07-10|
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    法律状态:
    2018-04-03| B06F| Objections, documents and/or translations needed after an examination request according art. 34 industrial property law|
    2019-07-23| B06U| Preliminary requirement: requests with searches performed by other patent offices: suspension of the patent application procedure|
    2020-06-02| B09A| Decision: intention to grant|
    2020-11-17| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 31/05/2012, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    US201161498107P| true| 2011-06-17|2011-06-17|
    US61/498,107|2011-06-17|
    PCT/US2012/040057|WO2012173776A2|2011-06-17|2012-05-31|Polyimide gas separation membranes|
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