JP5607721B2 - High performance crosslinked polybenzoxazole and polybenzothiazole polymer films - Google Patents

Description

  [0001] The present invention relates to high performance cross-linked polybenzoxazole and polybenzothiazole polymer films and methods of making and using these films.

  [0002] During the last 30-35 years, the state of the art of polymer membrane-based gas separation processes has advanced rapidly. Membrane-based technology has both the advantages of low equipment costs and high energy efficiency compared to conventional separation methods. Membrane gas separation is of particular interest to oil producers and refiners, chemical companies, and industrial gas suppliers. Applications in several areas such as carbon dioxide removal from natural gas and biogas and enhanced recovery of crude oil and hydrogen removal from nitrogen, methane, and argon in ammonia purge gas streams have been commercially successful. For example, UOP's Separex cellulose acetate polymer membrane is currently an international market leader for carbon dioxide removal from natural gas.

[0003] The most commonly used membranes in commercial gas separation applications are polymeric and non-porous. Separation is based on a solution diffusion mechanism. This mechanism involves a molecular scale interaction between the permeate gas and the membrane polymer. This mechanism is thought to be that in a membrane having two opposing surfaces, each component is adsorbed to the membrane on one surface, moved by a gas concentration gradient, and desorbed on the opposite surface. According to the solution-diffusion model, membrane performance in the separation of a given pair of gases (e.g., _{CO 2 / CH 4, O 2} / N 2, H 2 / CH 4) is the transmission coefficient (hereinafter, abbreviated as _{P A)} And the selectivity (α _{A / B} ). P _A is multiplied by the thickness of the selected skin layers of the flux and the membrane of the gas is obtained by dividing the pressure difference across the membrane. alpha _{A / B} is the ratio of the two transmission coefficient of the gas _{(α A / B = P A} / P B), where _{P A} is the transmittance of the transmission of higher gas, _{P B} is It is the permeability of gas with lower permeability. A gas may have a high permeability coefficient because of its high solubility coefficient, high diffusion coefficient, or because both coefficients are high. In general, as the gas molecular size increases, the diffusion coefficient decreases while the solubility coefficient increases. Higher permeabilities reduce the size of the membrane area required to process a given volume of gas, thereby reducing the equipment cost of the membrane unit, and higher selectivity also results in higher purity product gas Therefore, high permeability and high selectivity are desirable in high performance polymer membranes.

[0004] Polymers provide various ranges of properties important for gas separation such as low cost, good permeability, mechanical stability, and ease of processing. Polymer materials having a high glass transition temperature (T _g ), a high melting point, and a high crystallinity are preferred. Polymers of glassy (i.e. the polymer at lower temperatures than their T _g) has a more rigid polymer backbone, thus it is more quickly pass through the smaller molecules such as hydrogen and helium, on the other hand, carbonized Larger molecules such as hydrogen pass through glassy polymers more slowly compared to polymers with less rigid backbones. However, more permeable polymers generally have lower selectivity than less permeable polymers. There is always a general trade-off (so-called polymer upper limit) between transmittance and selectivity. Over the past 30 years, great research efforts have been directed at overcoming the limitations imposed by this upper limit. Various polymers and methods have been used, but have not been very successful. In addition, traditional polymer membranes also have constraints on thermal stability and contamination resistance.

  [0005] Cellulose acetate (CA) glassy polymer membranes are widely used in gas separation. Currently, such CA membranes are commercially used for natural gas reforming such as carbon dioxide removal. While CA membranes have many advantages, they are limited in many properties such as selectivity, permeability, and chemical, thermal, and mechanical stability. It has been found that the performance of polymer membranes can degrade quickly. The main cause of the loss of membrane performance is liquid condensation on the membrane surface. Condensation can be inhibited by providing a sufficient dew point margin for operation based on the calculated dew point of the film product gas. In order to remove water and heavy hydrocarbons from natural gas streams, thereby reducing the dew point of the stream, UOP's MemGuard system, a renewable adsorption system using molecular sieves, was developed. The selective removal of heavy hydrocarbons by the pretreatment system can significantly improve membrane performance. These pretreatment systems can perform such functions effectively, but are very expensive. In some projects, the cost of the pretreatment system was as high as 10-40% of the total cost (pretreatment system and membrane system) depending on the feed stream composition. Reducing the cost of the pretreatment system or completely eliminating the pretreatment system itself will greatly reduce the cost of the membrane system for natural gas reforming. On the other hand, in recent years, more and more membrane systems have been applied to large offshore natural gas reforming projects. For offshore projects, the footprint is a major constraint. Therefore, it is very important to reduce the installation area for offshore projects. The pretreatment system footprint is also very high, over 10-50% of the total membrane system footprint. Removing the pretreatment system from the membrane system has a significant economic impact, especially for offshore projects.

[0006] High performance polymers such as polyimide (PI), poly (trimethylsilylpropyne) (PTMSP), and polytriazole have been developed to improve membrane selectivity, permeability, and thermal stability. . These polymeric membrane _{materials, CO 2 / CH 4, O} 2 / N 2, H 2 / CH 4, and propylene / propane _{(C 3 H 6 / C 3} H 8) for separating the pair of gases, such as Shows promising properties. However, current polymer membrane materials have reached their limits in terms of their trade-off of productivity-selectivity. Furthermore, gas separation processes based on the use of glassy solution diffusion membranes often undergo plasticization of rigid polymer matrices with adsorbed osmotic molecules such as CO ₂ or C ₃ H ₆ . If the feed gas mixture contains a condensable gas, the plasticization of the polymer as indicated by the swelling of the membrane structure, and a large increase in the permeability of all components in the feed stream occurs at pressures higher than the plasticization pressure. .

  [0007] Aromatic polybenzoxazole (PBO), polybenzothiazole (PBT), and polybenzimidazole (PBI) are highly heat-stable ladders with flat rigid rod-like phenylene-heterocyclic ring units Glassy polymer. Rigid rigid ring units in such polymers are efficiently packed, leaving a free volume element accessible to very small penetrants, which is desirable for polymer membranes having both high permeability and high selectivity. However, these aromatic PBO, PBT, and PBI polymers with high thermal stability and chemical stability are poorly soluble in ordinary organic solvents, which makes polymer membranes produced by the most practical solvent casting method It cannot be used as a general polymer material. Thermally converting soluble aromatic polyimides containing pendant functional groups ortho to the heterocyclic imide nitrogen in the polymer backbone to aromatic polybenzoxazole (PBO) or polybenzothiazole (PBT) Can provide an alternative method for producing PBO or PBT polymer films that are difficult or impossible to obtain directly from PBO or PBT polymers by solvent casting (Tullos et al., MACROMOLECULES, 32, 3598 (1999). )).

  [0008] On the other hand, some inorganic molecular sieve membranes, such as SAPO-34 and carbon molecular sieve membranes, provide much higher permeability and selectivity than polymer membranes for gas separation, but are costly Mechanical stability is inferior and large-scale manufacturing is difficult. Accordingly, it is still highly desirable to provide a cost effective alternative membrane with improved separation characteristics.

  [0009] In US Pat. No. 5,409,524, a number of different polymer films are treated by heating the film to mitigate excess free volume in the polymer. This has a tendency to reduce the permeability of the polymer. The heating of the film was in the temperature range of 60-300 ° C. The film is then irradiated with UV radiation in the presence of oxygen to at least partially oxidize the surface. One of the films reported to be processed was a polybenzoxazole film. The polybenzoxazole polymer is produced by a one-step polycondensation synthesis procedure, and the film produced from this polybenzoxazole polymer is heat treated at 180 ° C. The membrane film showed a 25% decrease in permeability from 12.25 Barrer to 9.11 Barrer and a 15% increase in oxygen / nitrogen selectivity from 5.34 to 6.21. These conditions provide only a slight increase in selectivity compared to the present invention using different starting materials as well as much higher membrane processing temperatures.

[0010] In a recent issue of SCIENCE, a new type of highly permeable polybenzoxazole polymer membrane for gas separation was reported (Ho Bum Park et al., SCIENCE 318, 254 (2007)). These polybenzoxazole films are obtained by high temperature thermal rearrangement of hydroxy containing polyimide polymer films containing pendant hydroxyl groups ortho to the heterocyclic imide nitrogen. These polybenzoxazole polymer membranes were 100 times better than normal polymer membranes and showed very high CO ₂ permeability (> 1000 Barrer) comparable to that of some inorganic molecular sieve membranes, but CO ₂ / CH ₄ selectivity was comparable to commercial cellulose acetate membranes. In order to use these membranes commercially, improved selectivity is required. The inventors have attempted to increase the selectivity of these polybenzoxazole polymer membranes by adding trace acid dopants (eg, HCl and H ₃ PO ₄ ). However, the stability of trace acid dopants in these polybenzoxazole polymer films is an important issue for commercial use.

  [0011] In US Patent Application Publication No. 2008/0300336 (A1), the characteristics of certain mixed matrix membranes including molecular sieves that function to improve membrane permeability and selectivity by using UV crosslinking are described. It was reported that it was successfully improved. However, to obtain the improved level of properties reported here, it was necessary to both cross-link the polymer and add molecular sieves. To provide an improved polymer film that does not contain molecular sieves, both to avoid the need to disperse molecular sieves and to eliminate problems caused by lack of adhesion between the polymer and molecular sieves Is highly desirable.

US Pat. No. 5,409,524 US Patent Application Publication No. 2008/0300336

Tullos et al., MACROMOLECULES, 32, 3598 (1999) Ho Bum Park et al., SCIENCE 318, 254 (2007)

  [0012] The present invention has the following characteristics / advantages (ie, both processability, high selectivity and high permeation rate or flux, high thermal stability, and solvent swelling, plasticization, and hydrocarbon contamination) By providing a new type of high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes with long-term stable flux and retained selectivity due to resistance to materials, and means for making such membranes, It solves the problems of both technical polymer membranes and inorganic molecular sieve membranes. These membranes give very good permeability compared to crosslinked polyimide membranes and very good selectivity compared to uncrosslinked polybenzoxazole membranes.

[0013] The present invention relates to high performance crosslinked polybenzoxazole and polybenzothiazole polymer films, and methods of making and using these films.
[0014] High performance cross-linked polybenzoxazole and polybenzothiazole polymer films are UV-crosslinkable functional groups in the polymer backbone and pendant functional groups ortho to the heterocyclic imide nitrogen (e.g., -OH or -SH groups). ) From both cross-linkable polyimide polymers by thermal conversion followed by UV irradiation. The high performance cross-linked polybenzoxazole and polybenzothiazole polymer films described in the present invention comprise polybenzoxazole or polybenzothiazole polymer chain segments, and at least some of these polymer chain segments are exposed to UV radiation. In some cases, they are crosslinked to each other via direct covalent bonds. The cross-linking of polybenzoxazole and polybenzothiazole polymer membranes imparts greatly improved membrane selectivity, chemical stability and thermal stability to the membrane.

  [0015] Crosslinked polybenzoxazole and polybenzothiazole polymer membranes are easy to process, high selectivity, high permeation rate or flux, high thermal stability, and resistance to solvent swelling, plasticization, and hydrocarbon contaminants Solves the problems of both prior art polymer membranes and inorganic molecular sieve membranes with the advantages of stable flux over time and retained selectivity.

  [0016] A method for producing high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes is as follows: (1) First, a pendant functional group ortho-positioned to a heterocyclic imide nitrogen (eg, —OH or -SH) and an aromatic polyimide polymer containing a UV-crosslinkable functional group (for example, a carbonyl group); (2) producing a polyimide film from the aromatic polyimide polymer synthesized in step (1); (3) argon, Convert the polyimide film to a polybenzoxazole or polybenzothiazole film by heating between 300 ° C. and 600 ° C. under an inert atmosphere such as nitrogen or under vacuum; and (4) Finally, to UV radiation By exposing the polybenzoxazole or polybenzothiazole film to cross-linked polybenzoxazo It is converted to le or polybenzothiazole polymer film; comprising. In some cases, after exposure to UV radiation, a film post-treatment step is added to make the selective layer surface of the crosslinked polybenzoxazole or polybenzothiazole polymer film a polysiloxane, fluoropolymer, thermosetting silicone rubber, Or it can be coated with a thin layer of highly permeable material such as UV radiation curable epoxy silicone.

  [0017] Crosslinked polybenzoxazole and polybenzothiazole polymer membranes are non-porous symmetric or asymmetric structures having a thin non-porous dense selective layer supported on top of a porous support layer. Can have either. These membranes can be formed in any convenient form such as flat sheets (or spirals), discs, tubes, hollow fibers, or thin film composites.

  [0018] The present invention provides a method of separating at least one gas or liquid from a plurality of gases or liquid mixtures using either a crosslinked polybenzoxazole polymer film or a crosslinked polybenzothiazole polymer film. The method includes providing a crosslinked polybenzoxazole or polybenzothiazole polymer membrane that is permeable to at least one gas or liquid; a plurality of gases or one or more gases on one side of the crosslinked polybenzoxazole or polybenzothiazole polymer membrane. Contacting the liquid mixture to allow at least one gas or liquid to permeate the cross-linked polybenzoxazole or polybenzothiazole polymer membrane; and at least one gas or liquid that has permeated the membrane from the opposite side of the membrane Removing the permeate gas or liquid composition that is part of

[0019] High performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes are used to separate various liquids, gases, and vapors (such as desalting water by reverse osmosis), non-aqueous liquid separations (gasoline and diesel fuel depths). Desulfurization etc.), ethanol / water separation, pervaporation dehydration of aqueous / organic mixtures, CO ₂ / CH ₄ , CO ₂ / N ₂ , H ₂ / CH ₄ , O ₂ / N ₂ , H ₂ S / CH ₄ Not only suitable for the separation of olefins / paraffins, iso / n-paraffins, and other light gas mixtures, but can also be used for other applications such as catalysis and fuel cell applications .

[0020] In 1999, Tullos et al. Reported the synthesis of a series of hydroxy-containing polyimide polymers containing pendant hydroxyl groups ortho to the heterocyclic imide nitrogen. These polyimides were found to undergo thermal conversion to polybenzoxazole when heated between 350 ° C. and 500 ° C. under nitrogen or vacuum (Tullos et al., MACROMOLECULES, 32, 3598 (1999) ). In a recent issue of SCIENCE, a further study was reported that the polybenzoxazole polymer material reported by Tullos et al. Had a free volume element that was tuned with a well-configured morphology. . Thermally driven segmental dislocations can be used to regularly tailor the unique microstructure in these polybenzoxazole polymer materials to provide a route for producing polybenzoxazole polymer membranes for gas separation. See Ho Bum Park et al., SCIENCE, 318, 254 (2007). These polybenzoxazole polymer membranes were 100 times better than normal polymer membranes and showed very high CO ₂ permeability (> 1000 Barrer) comparable to that of some inorganic molecular sieve membranes, but CO ₂ The CO ₂ / CH ₄ selectivity was lower than that of some small pore inorganic molecular sieve membranes for / CH ₄ separation.

[0021] The present invention includes novel high performance cross-linked polybenzoxazole and polybenzothiazole polymer films, and methods of making and using these films.
[0022] The present invention addresses both processability, high selectivity and high permeation rate or flux, high thermal stability, and solvent swelling, plasticization, and degradation from exposure to hydrocarbon contaminants. Provided are new types of high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes having these characteristics / advantages of stable flux and retained selectivity over time due to resistance, and these membranes This solves the problems of both prior art polymer membranes and inorganic molecular sieve membranes.

  [0023] The high performance cross-linked polybenzoxazole and polybenzothiazole polymer films described in this invention can be obtained by thermal conversion followed by UV irradiation to form UV crosslinkable functional groups (eg carbonyl groups) and heterocyclic imides in the polymer backbone. Made from a crosslinkable polyimide polymer containing both pendent functional groups ortho to the nitrogen (eg, —OH or —SH). The film comprises polybenzoxazole or polybenzothiazole polymer chain segments, at least some of these polymer chain segments being crosslinked to one another by direct covalent bonding by exposure to UV radiation. The cross-linking of polybenzoxazole and polybenzothiazole polymer membranes imparts greatly improved membrane selectivity, chemical stability and thermal stability to the membrane.

  [0024] The present invention provides: (1) First, in the polymer backbone, a pendant functional group ortho-positioned with respect to the heterocyclic imide nitrogen (eg -OH or -SH) and a UV-crosslinkable functional group (eg carbonyl group) (2) A polyimide film is produced from the aromatic polyimide polymer synthesized in step (1); (3) 300 ° C. under an inert atmosphere such as argon or nitrogen or under vacuum. Heating between ˜600 ° C. converts the polyimide film to a polybenzoxazole or polybenzothiazole film; and (4) finally, exposing the polybenzoxazole or polybenzothiazole film to exposure to UV radiation Converted to a crosslinked polybenzoxazole or polybenzothiazole polymer film; To provide a method for producing a performance crosslinked polybenzoxazole and polybenzothiazole polymer film. In some cases, a film post-treatment step is added after UV irradiation to make the selective layer surface of the crosslinked polybenzoxazole or polybenzothiazole polymer film a polysiloxane, fluoropolymer, thermosetting silicone rubber, or UV radiation. It can be coated with a thin layer of a highly permeable material such as a curable epoxy silicone.

  [0025] The polybenzoxazole-type and polybenzothiazole-type polymer films used in the present invention to produce cross-linked polybenzoxazole and polybenzothiazole polymer films can be obtained under an inert atmosphere such as argon, nitrogen or under vacuum. Manufactured by thermal conversion of polyimide film by heating between 300 ° C and 600 ° C. The polyimide film is formed by a solution-casting or solution-spinning method in which a UV-crosslinkable functional group (for example, a carbonyl group) in the polymer skeleton and a pendant functional group (for example, —OH or —SH) in the ortho position with respect to the heterocyclic imide nitrogen are used. Manufactured from soluble polyimide. When a polyimide having a pendant functional group ortho-positioned to the heterocyclic imide nitrogen (for example, —OH or —SH) is thermally converted, polybenzoxazole (when the pendant functional group is an —OH group) by irreversible molecular rearrangement ) Or polybenzothiazole (if the pendant functional group is a -SH group) and the thermal conversion is accompanied by the disappearance of carbon dioxide, but no other volatile by-products are generated. Polybenzoxazole and polybenzothiazole polymers have the formula (I):

(Where X in formula (I) is O for polybenzoxazole and S for polybenzothiazole.)
Of repeating units.

  [0026] A UV crosslinkable polyimide polymer comprising pendent functional groups ortho to the heterocyclic imide nitrogen used to produce high performance crosslinked polybenzoxazole type and polybenzothiazole type films in the present invention comprises: Formula (II):

(Where X1 in formula (II) is

Or a mixture thereof; X2 in formula (II) is the same as X1, or

Or a mixture thereof; -Y- in formula (II) is

Or a mixture thereof; -Z-, -Z'-, and -Z "-are independently -O- or -S-; -R- is

Or a mixture thereof. )
A plurality of first repeating units.
[0027] In one embodiment of the invention, when preferred X1 and X2 of formula (II) are the same,

Or selected from the group of mixtures thereof; Y in formula (II) is

Or selected from the group of these mixtures.
[0028] In another embodiment of the present invention, X1 of formula (II) is

Or selected from the group of mixtures thereof; X2 in formula (II) is

Or selected from the group of mixtures thereof; Y in formula (II) is

Or selected from the group of these mixtures.
[0029] Some of the preferred polyimide polymers used to make high performance crosslinked polybenzoxazole and polybenzothiazole films in the present invention include poly [3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride. Product-2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane] (poly (BTDA-APAF)), poly [4,4′-oxydiphthalic anhydride-2,2-bis (3- Amino-4-hydroxyphenyl) hexafluoropropane] (poly (ODPA-APAF)), poly (3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride-3,3′-dihydroxy-4,4 '-Diaminobiphenyl) (poly (BTDA-HAB)), poly [3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane] (poly (DSDA-APAF)), poly (3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride-2 , 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane-3,3′-dihydroxy-4,4′-diaminobiphenyl (poly (DSDA-APAF-HAB)), poly [2,2′- Bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride-3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride-2,2-bis (3-amino-4-hydroxyphenyl) Hexafluoropropane] (poly (6FDA-BTDA-APAF)), poly [4,4′-oxydiphthalic anhydride-2,2-bis (3-amino-4-hydride) Roxyphenyl) hexafluoropropane-3,3′-dihydroxy-4,4′-diaminobiphenyl] (poly (ODPA-APAF-HAB)), poly [3,3 ′, 4,4′-benzophenone tetracarboxylic acid Anhydride-2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane-3,3′-dihydroxy-4,4′-diaminobiphenyl] (poly (BTDA-APAF-HAB)), and poly (4,4′-bisphenol A dianhydride-3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride-2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane] ( Poly (BPADA-BTDA-APAF)), but is not limited thereto.

  [0030] Suspended functional groups ortho-positioned to UV-crosslinkable functional groups and heterocyclic imide nitrogens in the polymer backbone (such as-) used in the present invention to produce crosslinked polybenzoxazole and polybenzothiazole polymer films OH or —SH) containing polyimides form 1-methyl-2-pyrrolidone (NMP) or N 2 by a two-step process that includes forming poly (amidic acid) followed by solution imidization or thermal imidization. , N-dimethylacetamide (DMAc) is synthesized from diamine and dianhydride in a polar solvent. Acetic anhydride is used as the dehydrating agent, and pyridine (or triethylamine) is used as the imidization catalyst for the solution imidization reaction. More information on the production of these polymers is available in Tullos et al., MACROMOLECULES, 32, 3598 (1999).

  [0031] In the present invention, a polyimide film used for producing a high-performance crosslinked polybenzoxazole type or polybenzothiazole type film is obtained by casting a uniform polyimide solution on the top surface of a clean glass plate and using a plastic as a solvent. By slowly evaporating at room temperature for at least 12 hours inside the cover, pendant functional groups ortho-positioned to the UV crosslinkable functional groups and the heterocyclic imide nitrogen (eg —OH or —SH) in the polymer backbone. The polyimide polymer containing can be molded into a film having a non-porous symmetric thin film form. The membrane is then removed from the glass plate and dried at room temperature for 24 hours and then under vacuum at 200 ° C. for at least 48 hours.

  [0032] Solvents used to dissolve the polyimide polymer are selected primarily for their ability to completely dissolve the polymer and the ease of removal of the solvent in the film forming process. Other considerations in selecting a solvent include low toxicity, low corrosive activity, low environmental hazard potential, availability, and cost. Typical solvents for use in the present invention include most amide solvents commonly used to form polymer films, such as N-methylpyrrolidone (NMP) and N, N-dimethylacetamide (DMAC), chloride Methylene, tetrahydrofuran (THF), acetone, N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), toluene, dioxane, 1,3-dioxolane, mixtures thereof, others known to those skilled in the art, and these Of the mixture.

  [0033] The polyimide film used in the present invention to produce a high performance crosslinked polybenzoxazole type or polybenzothiazole type film also dissolves the polyimide polymer in a solvent to form a solution of the polyimide material; Contacting a membrane support (eg, a support made from an inorganic ceramic material) with this solution; then evaporating the solvent to provide a thin selective layer comprising a polyimide polymer material on the support layer; Can also be manufactured.

  [0034] The polyimide membrane can also be planarized by performing phase inversion and then directly air drying using at least one desiccant that is a hydrophobic organic compound such as a hydrocarbon or ether. It can also be produced as an asymmetric membrane having the form of a simple sheet or hollow fiber (see US Pat. No. 4,855,048). Polyimide membranes can also be produced as asymmetric membranes in the form of flat sheets or hollow fibers by phase inversion followed by solvent exchange.

  [0035] The polyimide film is then heated between 300 ° C. and 600 ° C., preferably between 400 ° C. and 500 ° C., most preferably between 400 ° C. and 450 ° C., under an inert atmosphere such as argon, nitrogen or under vacuum. By doing so, it is converted into a polybenzoxazole or polybenzothiazole polymer film. The heating time for this heating step is in the range of 30 seconds to 2 hours. A more preferable heating time is 30 seconds to 1 hour. Next, the polybenzoxazole or polybenzothiazole polymer film is UV-crosslinked by using a UV lamp from a predetermined distance and UV-crosslinking the polybenzoxazole or polybenzothiazole polymer film for a predetermined time selected based on the required separation characteristics. Form. For example, a crosslinked polybenzoxazole or polybenzothiazole polymer film is generated from a UV lamp at less than 50 ° C. using a 1.9 cm (0.75 inch) film surface to UV lamp distance and a 30 minute irradiation time. It can be produced from polybenzoxazole or polybenzothiazole polymer films by exposure to UV radiation using UV light of a wavelength of 254 nm. The UV lamp described here is a low pressure mercury arc immersion UV quartz 12W lamp with a 12W power supply available from Ace Glass Incorporated. Optimizing the degree of crosslinking in crosslinked polybenzoxazole and polybenzothiazole polymer membranes facilitates tailoring the membrane to suit a wide range of gas and liquid separations with improved permeation properties and environmental stability. The degree of crosslinking of the crosslinked polybenzoxazole and polybenzothiazole polymer films can be controlled by adjusting the distance between the UV lamp and the film surface, the UV irradiation time, the wavelength and intensity of the UV light, and the like. Preferably, the distance from the UV lamp to the film surface is 0.8 to 25.4 cm (0.3 to 10 inches) when using UV light provided from a low or medium pressure mercury arc lamp of 12 W to 450 W. The UV irradiation time is in the range of 0.5 minutes to 1 hour. More preferably, the distance from the UV lamp to the membrane surface is between 1.3 and 5.1 cm (0.5 to 2 inches) when using UV light provided from a 12 W to 450 W low or medium pressure mercury arc lamp. The UV irradiation time is in the range of 0.5 to 40 minutes.

  [0036] In some cases, after the formation of a crosslinked polybenzoxazole or polybenzothiazole polymer film, a post-treatment step of the film is added to form a polysiloxane, fluoropolymer, thermosetting silicone rubber, or UV radiation curable A thin layer of highly permeable material such as epoxy silicone can be applied. The coating fills other defects including surface pores and vacancies (US Pat. Nos. 4,230,463; 4,877,528; 6,368,382). See the specification).

  [0037] The high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes of the present invention have a non-porous symmetrical structure with a thin non-porous and dense selection layer supported on top of the porous support layer Or can have either an asymmetric structure. The porous support can be composed of the same crosslinked polybenzoxazole or polybenzothiazole polymer material, or different types of organic or inorganic materials with high thermal stability. The high performance crosslinked polybenzoxazole and polybenzothiazole polymer membranes of the present invention can be formed into any convenient form such as flat sheets (or spirals), disks, tubes, hollow fibers, or thin film composites. .

  [0038] The present invention is a method of separating at least one gas or liquid from a mixture of a plurality of gases or liquids using a crosslinked polybenzoxazole and polybenzothiazole polymer membrane comprising (a) at least one type Providing a cross-linked polybenzoxazole or polybenzothiazole polymer membrane that is permeable to gas or liquid; (b) contacting the mixture on one side of the cross-linked polybenzoxazole or polybenzothiazole polymer membrane to form at least one gas or Allowing the liquid to permeate the cross-linked polybenzoxazole or polybenzothiazole polymer membrane; and (c) removing from the opposite side of the membrane a permeate gas or liquid composition comprising at least one gas or liquid portion that has permeated the membrane A method as described above is provided.

  [0039] These high performance crosslinked polybenzoxazole and polybenzothiazole polymer membranes are particularly useful in the purification, separation, or adsorption of certain species in the liquid or gas phase. In addition to the separation of multiple gas pairs, these high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes are suitable for desalting water, for example by reverse osmosis in the pharmaceutical and biotechnology industries or for proteins or other Can be used to separate thermally unstable compounds. High performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes can also be used in fermenters and bioreactors to transfer gases into reaction vessels and to remove cell culture media from the vessels. In addition, high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes can be used to remove microorganisms from air or water streams, for water purification, for ethanol production in continuous fermentation / membrane pervaporation systems, and for air streams or It can be used to detect or remove trace amounts of compounds or metal salts in the water stream.

[0040] The crosslinked polybenzoxazole and polybenzothiazole polymer membranes of the present invention are particularly useful in gas separation processes in the air purification, petrochemical, refinery, and natural gas industries. Examples of such separations include separation of volatile organic compounds (eg, toluene, xylene, and acetone) from atmospheric gases such as nitrogen or oxygen, and recovery of nitrogen from the air. Further examples of such separations include separation of CO ₂ or H ₂ S from natural gas, separation of H ₂ from N ₂ , CH ₄ , and Ar in an ammonia purge gas stream, recovery of H ₂ in refineries, olefins For separation of paraffin / paraffin, for example of propylene / propane, and iso / n-paraffin. Using the cross-linked polybenzoxazole or polybenzothiazole polymer membrane described herein, any given pair or group of gases having different molecular sizes, such as nitrogen and oxygen, carbon dioxide and methane, hydrogen and methane, or one Carbon oxide, helium, and methane can be separated. More than two gases can be extracted from the third gas. For example, some of the gaseous components that can be selectively extracted from raw natural gas using the membranes described herein include carbon dioxide, oxygen, nitrogen, water vapor, hydrogen sulfide, helium, and other trace gases. Is mentioned. Examples of the gas component that can be selectively left include hydrocarbon gas. When the permeable component is an acid component selected from the group consisting of carbon dioxide, hydrogen sulfide, and mixtures thereof, when taken from a hydrocarbon mixture such as natural gas, one module, or at least in parallel The acid component can be removed using at least two modules operating in series or in series. For example, when one module is used, the pressure of the supply gas can be in the range of 275 kPa to 2.6 MPa (25 to 4000 psi). The differential pressure across the membrane can be as low as 0.7 bar depending on many factors such as the particular membrane used, the flow rate of the inlet stream, and the effectiveness of the compressor to compress the permeate stream if compression is desired. Or a range of heights such as 145 bar (heights such as 10 psi or 2100 psi). Differential pressures higher than 145 bar (2100 psi) can damage the membrane. A lower differential pressure may require more modules, more time, and compression of the intermediate product stream, so a differential pressure of at least 7 bar (100 psi) is preferred. The operating temperature of the process can be varied depending on the feed stream temperature and ambient temperature conditions. Preferably, the effective operating temperature of the membrane of the present invention is in the range of -50 ° C to 150 ° C. More preferably, the effective operating temperature of the membrane of the present invention is in the range of −20 ° C. to 100 ° C., and most preferably the effective operating temperature of the membrane of the present invention is in the range of 25 ° C. to 100 ° C.

[0041] Crosslinked polybenzoxazole and polybenzothiazole polymer membranes meet, for example, clean air regulations in gas / vapor separation processes for removing organic vapors from gas streams in the chemical, petrochemical, pharmaceutical, and related industries Or in off-gas treatment to recover volatile organic compounds in the process stream at the manufacturing plant so that valuable compounds (eg, vinyl chloride monomer, propylene) can be recovered. Further examples of gas / vapor separation processes that can use these crosslinked polybenzoxazole and polybenzothiazole polymer membranes include separation of hydrocarbon vapors from hydrogen in oil and gas refineries, hydrocarbon dew point control of natural gas (Ie, reducing the hydrocarbon dew point below the lowest possible exhaust pipeline temperature so that liquid hydrocarbons do not separate in the pipeline) This is for controlling the methane number in the tank and for recovering gasoline. Crosslinked polybenzoxazole and polybenzothiazole polymer films are species that strongly adsorb to specific gases and promote their migration across the film (eg, cobalt porphyrin or phthalocyanine for O ₂ or silver (I) for ethane) May be contained.

[0042] Crosslinked polybenzoxazole and polybenzothiazole polymer membranes can be operated at elevated temperatures to provide sufficient dew point margin for natural gas reforming (eg, removal of CO ₂ from natural gas). . Crosslinked polybenzoxazole and polybenzothiazole polymer membranes can be used either as single stage membranes for natural gas modification or as first and / or second stage membranes in a two stage membrane system. High performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes with high selectivity, high permeability, and high thermal and chemical stability of the present invention operate the membranes without using high cost pretreatment systems be able to. Thus, in new processes involving cross-linked polybenzoxazole or polybenzothiazole polymer membrane systems, an expensive membrane pretreatment system such as an adsorbent MemGuard system may not be necessary. Because the pretreatment system is eliminated and the membrane area is greatly reduced, this new process can achieve significant equipment cost savings and reduce the existing membrane footprint.

  [0043] These cross-linked polybenzoxazole and polybenzothiazole polymer membranes are also used in the separation of liquid mixtures by pervaporation, for example organic compounds (eg alcohols, phenols) from water such as aqueous effluents or process fluids. , Chlorinated hydrocarbons, pyridines, ketones). Using a cross-linked polybenzoxazole or polybenzothiazole polymer membrane that is ethanol selective will increase the ethanol concentration in a relatively dilute ethanol solution (5-10% ethanol) obtained by the fermentation process. Other liquid phase separation examples using these crosslinked polybenzoxazole and polybenzothiazole polymer membranes are described in US Pat. No. 7,048,846, which is incorporated herein by reference in its entirety. Deep desulfurization of gasoline and diesel fuel by a pervaporation membrane process similar to the process being described. Crosslinked polybenzoxazole and polybenzothiazole polymer membranes that are selective for sulfur-containing molecules will selectively remove sulfur-containing molecules from fluid catalytic cracking (FCC) and other naphtha hydrocarbon streams. Let's go. Examples of further liquid phases include the separation of one organic component from another organic component, for example to separate isomers of organic compounds. As a mixture of a plurality of organic compounds that can be separated using a crosslinked polybenzoxazole or polybenzothiazole polymer membrane, 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-butyl acetate, butanol-1-butyl ether, ethanol-ethyl butyl ether, propyl acetate-propanol, isopropyl ether-isopropanol, methanol-ethanol-isopropanol And ethyl acetate-ethanol-acetic acid.

  [0044] Crosslinked polybenzoxazole and polybenzothiazole polymer membranes separate organic molecules from water (eg, ethanol and / or phenol from water by pervaporation) and remove metals and other organic compounds from water Can be used for.

  [0045] Crosslinked polybenzoxazole and polybenzothiazole polymer membranes have direct applications for separation of gas mixtures such as removal of carbon dioxide from natural gas. The membrane can diffuse carbon dioxide through at a faster rate than methane in natural gas. Carbon dioxide has a higher permeation rate than methane due to higher solubility, higher diffusivity, or both. Thus, carbon dioxide is enriched on the permeate side of the membrane and methane is enriched on the supply (or waste) side of the membrane.

  [0046] Crosslinked polybenzoxazole and polybenzothiazole polymer membranes also have direct applications for concentrating olefins in paraffin / olefin streams for olefin cracking applications. For example, cross-linked polybenzoxazole and polybenzothiazole polymer membranes can be used to separate propylene / propane to increase the concentration of the effluent in a catalytic dehydrogenation reaction to produce propylene from propane and isobutylene from isobutane. Can do. Thus, the number of propylene / propane separator stages required to obtain polymer grade propylene can be reduced. Other uses for cross-linked polybenzoxazole and polybenzothiazole polymer membranes are to increase the concentration of light paraffin isomerization and n-paraffins in the naphtha cracker feed, which can then be converted to ethylene. This is because isoparaffin and n-paraffin are separated in the process MaxEne.

  [0047] A further application of cross-linked polybenzoxazole and polybenzothiazole polymer membranes is separators in chemical reactors to increase the yield of equilibrium limiting reactions by selective removal of certain materials.

[0048] In summary, the high performance crosslinked polybenzoxazole and polybenzothiazole polymer membranes of the present invention are capable of separating various liquids, gases, and vapors such as water desalting by reverse osmosis, gasoline and diesel fuel depths. Separation of non-aqueous liquids such as desulfurization, separation of ethanol / water, pervaporation dehydration of aqueous / organic mixtures, CO ₂ / CH ₄ , CO ₂ / N ₂ , H ₂ / CH ₄ , O ₂ / N ₂ , H ₂ S / CH _4, is suitable for the separation of olefins / paraffins, separation of the iso / n-paraffins, and other light gas mixture.

  [0049] The following examples are given to illustrate one or more preferred embodiments of the present invention, but are not limited thereto. Numerous changes can be made to the following examples, which are within the scope of the invention.

Example 1:
Synthesis of poly (BTDA-APAF) polyimide:
[0050] Suspension ortho to the UV-crosslinkable carbonyl group and the heterocyclic imide nitrogen in the polymer backbone by a two-step process comprising forming a poly (amic acid) and then performing a solution imidization process Aromatic poly [3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride-2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane] (poly (BTDA) containing OH functional group -APAF)) polyimide in NMP polar solvent with 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (APAF) and 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride (BTDA). Acetic anhydride was used as a dehydrating agent, and pyridine was used as an imidization catalyst for solution imidization reaction. For example, a 250 mL three-necked round bottom flask equipped with a nitrogen inlet and a mechanical stirrer was charged with 10.0 g (27.3 mmol) APAF and 40 mL NMP. When APAF was completely dissolved, a solution of BTDA (8.8 g, 27.3 mmol) in 40 mL NMP was added to the APAF solution in the flask. The reaction mixture was mechanically stirred at ambient temperature for 24 hours to give a viscous poly (amic acid) solution. Next, 11.1 g of acetic anhydride in 10 mL of NMP was slowly added to the reaction mixture with stirring, and then 8.6 g of pyridine in 10 mL of NMP was added to the reaction mixture. The reaction mixture was mechanically stirred at 80 ° C. for an additional hour to obtain poly (BDTA-APAF) polyimide. The poly (BTDA-APAF) polyimide product in fine fiber form was recovered by slowly precipitating the reaction mixture into a large volume of methanol. Next, the obtained poly (BTDA-APAF) polyimide fiber was thoroughly rinsed with methanol and dried in a vacuum oven at 150 ° C. for 24 hours.

Example 2:
Synthesis of poly (ODPA-APAF) polyimide:
[0051] Including a pendant-OH functional group ortho to the heterocyclic imide nitrogen in the polymer backbone by a two-step process involving forming a poly (amidic acid) and then performing a solution imidization process Aromatic poly [4,4′-oxydiphthalic anhydride-2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane] (poly (ODPA-APAF)) polyimide is prepared in 4 in NMP polar solvent. , 4′-oxydiphthalic anhydride (ODPA) and 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (APAF). Acetic anhydride was used as a dehydrating agent, and pyridine was used as an imidization catalyst for solution imidization reaction. For example, a 250 mL three-necked round bottom flask equipped with a nitrogen inlet and a mechanical stirrer was charged with 10.0 g (27.3 mmol) APAF and 20 mL NMP. When APAF was completely dissolved, a solution of ODPA (8.88 g, 27.3 mmol) in 35 mL of NMP was added to the APAF solution in the flask. The reaction mixture was mechanically stirred at ambient temperature for 24 hours to give a viscous poly (amic acid) solution. Next, 11.1 g of acetic anhydride in 10 mL of NMP was slowly added to the reaction mixture with stirring, and then 8.6 g of pyridine in 10 mL of NMP was added to the reaction mixture. The reaction mixture was mechanically stirred at 80 ° C. for an additional hour to obtain poly (ODPA-APAF) polyimide. The poly (ODPA-APAF) polyimide product in fine fiber form was recovered by slowly precipitating the reaction mixture in a large volume of methanol. Next, the obtained poly (ODPA-APAF) polyimide fiber was thoroughly rinsed with methanol and dried in a vacuum oven at 150 ° C. for 24 hours.

Example 3:
Production of poly (BTDA-APAF) polymer membrane:
[0052] A poly (BTDA-APAF) polymer membrane was prepared as follows. 4.0 g of poly (BTDA-APAF) polyimide synthesized in Example 1 was dissolved in a solvent mixture of 12.0 g NMP and 12.0 g 1,3-dioxolane. The mixture was mechanically stirred for 2 hours to form a uniform casting dope. The resulting uniform casting dope was degassed overnight. A poly (BTDA-APAF) polymer film was prepared from a bubble-free casting dope on a clean glass plate with a doctor knife using a 20 mil gap. The membrane was then placed in a vacuum oven with a glass plate. The solvent was removed by slowly increasing the vacuum oven vacuum and temperature. Finally, the membrane was dried under vacuum at 200 ° C. for at least 48 hours to completely remove residual solvent to form a poly (BTDA-APAF) polymer membrane.

Example 4:
Production of polybenzoxazole polymer film PBO (BTDA-APAF-450C) (abbreviated as PBO (BTDA-APAF)):
[0053] The poly (BTDA-APAF) polymer membrane produced in Example 3 was heated from 50 ° C. to 450 ° C. at a heating rate of 5 ° C./min under N ₂ flow to produce a polybenzoxazole polymer membrane PBO (BTDA -APAF-450C) was produced. The membrane was held at 450 ° C. for 1 hour and then cooled to 50 ° C. at a cooling rate of 5 ° C./min under N ₂ flow.

Example 5:
Production of crosslinked PBO (BTDA-APAF-450C) polybenzoxazole polymer film (abbreviated as crosslinked PBO (BTDA-APAF-450C)):
[0054] The PBO (BTDA-APAF-450C) polymer film produced in Example 4 was UV irradiated from a 1.9 cm (0.75 inch) film surface using UV light with a wavelength of 254 nm generated from a UV lamp. A cross-linked PBO (BTDA-APAF-450C) polymer film was prepared by UV cross-linking by exposure to UV radiation at 50 ° C. with a distance to the lamp and an irradiation time of 20 minutes. The UV lamp used was a low pressure mercury arc immersion UV quartz 12W lamp with a 12W power supply from Ace Glass Incorporated.

Example 6:
Production of poly (ODPA-APAF) polymer film:
[0055] A procedure similar to that described in Example 3 was used, but in this example a poly (ODPA-APAF) polymer membrane was prepared using the poly (OTDA-APAF) polyimide synthesized in Example 2. did.

Example 7:
Production of polybenzoxazole polymer film PBO (ODPA-APAF-450C) (abbreviated as PBO (ODPA-APAF-450C)):
[0056] Using a procedure similar to that described in Example 4, the poly (ODPA-APAF) polymer film produced in Example 6 was heated to produce a polybenzoxazole polymer film PBO (ODPA-APAF-450C). ) Was manufactured.

Example 8:
Production of polybenzoxazole polymer film PBO (ODPA-APAF-400C) (abbreviated as PBO (ODPA-APAF-400C)):
[0057] The poly (ODPA-APAF) polymer membrane produced in Example 6 was heated from 50 ° C. to 400 ° C. at a heating rate of 5 ° C./min under N ₂ flow to thereby obtain a polybenzoxazole polymer membrane PBO (ODPA -APAF-400C) was produced. The membrane was held at 400 ° C. for 1 hour and then cooled to 50 ° C. at a heating rate of 5 ° C./min under N ₂ flow.

Example 9:
Production of crosslinked PBO (ODPA-APAF-450C) polybenzoxazole polymer film (abbreviated as crosslinked PBO (ODPA-APAF-450C)):
[0058] The PBO (ODPA-APAF-450C) polymer film produced in Example 7 was UV irradiated from a 1.9 cm (0.75 inch) film surface using UV light at a wavelength of 254 nm generated from a UV lamp. A cross-linked PBO (ODPA-APAF-450C) polymer film was prepared by UV cross-linking by exposure to UV radiation at 50 ° C. with a distance to the lamp and an irradiation time of 20 minutes. The UV lamp used was a low pressure mercury arc immersion UV quartz 12W lamp with a 12W power supply from Ace Glass Incorporated.

Example 10:
Production of crosslinked PBO (ODPA-APAF-400C) polybenzoxazole polymer film (abbreviated as crosslinked PBO (ODPA-APAF-400C)):
[0059] The PBO (ODPA-APAF-400C) polymer film produced in Example 8 was UV irradiated from a 1.9 cm (0.75 inch) film surface using UV light with a wavelength of 254 nm generated from a UV lamp. A cross-linked PBO (ODPA-APAF-400C) polymer film was prepared by UV cross-linking by exposure to UV radiation at 50 ° C. with a distance to the lamp and an irradiation time of 20 minutes. The UV lamp used was a low pressure mercury arc immersion UV quartz 12W lamp with a 12W power supply from Ace Glass Incorporated.

Example 11:
CO ₂ / CH ₄ separation performance of PBO (BTDA-APAF-450C) and crosslinked PBO (BTDA-APAF-450C) polymer membranes:
[0060] The PBO (BTDA-APAF-450C) polymer membrane produced in Example 4 and the crosslinked PBO (BTDA-APAF-450C) polymer membrane produced in Example 5 were subjected to test temperatures of 50 ° C. and 100 ° C., respectively. Were tested for CO ₂ / CH ₄ separation (Table 1). From Table 1, the PBO (BTDA-APAF-450C) polymer membrane has high CO ₂ permeability (P _CO2 = 535.9 Barrer at 50 ° C. test temperature) and moderate CO ₂ / CH ₄ selectivity (50 ° C. It can be seen that the test temperature showed 26.0). After cross-linking, the cross-linked PBO (BTDA-APAF-450C) polymer membrane has a CO ₂ / CH ₄ selectivity (compared to PBO (BTDA-APAF-450C) membrane, respectively, at both 50 ° C. and 100 ° C. test temperatures. There was a significant increase of 48.4) at a test temperature of 50 ° C.

Example 12:
H ₂ / CH ₄ separation performance of PBO (BTDA-APAF-450C) and crosslinked PBO (BTDA-APAF-450C) polymer membranes:
[0061] The PBO (BTDA-APAF-450C) polymer membrane produced in Example 4 and the crosslinked PBO (BTDA-APAF-450C) polymer membrane produced in Example 5 were subjected to H ₂ / It was tested for CH ₄ separation (Table 2). From Table 2, the crosslinked PBO (BTDA-APAF-450C) polymer membrane shows a high H ₂ / CH ₄ selectivity of 133, which is more than 3 times higher than that of the PBO (BTDA-APAF-450C) polymer membrane. It turns out that it was. These results suggest that cross-linking PBO (BTDA-APAF-450C) polymer film is a good candidate materials for the _H 2 / CH ₄ separation.

Example 13:
Propylene / propane separation performance of PBO (BTDA-APAF-450C) and crosslinked PBO (BTDA-APAF-450C) polymer membranes:
[0062] The PBO (BTDA-APAF-450C) polymer membrane produced in Example 4 and the crosslinked PBO (BTDA-APAF-450C) polymer membrane produced in Example 5 were propylene / propane at a test temperature of 50 ° C. Tested for separation (Table 3). From Table 3, it can be seen that the propylene / propane selectivity of PBO (BTDA-APAF-450C) polymer membrane increased from 12.6 to 19.1 after the membrane was crosslinked by UV radiation. These results suggest that cross-linked PBO (BTDA-APAF-450C) polymer membranes are also good candidate materials for propylene / propane separation.

Example 14:
CO ₂ / CH ₄ separation performance of PBO (ODPA-APAF-450C) and crosslinked PBO (ODPA-APAF-450C) polymer membranes:
[0063] The PBO (ODPA-APAF-450C) and cross-linked PBO (ODPA-APAF-450C) polymer membranes prepared in Example 7 and Example 9, respectively, at 50 ° C. under a pure gas pressure of 690 kPa CO ₂ / Tested for CH ₄ separation (Table 4). From Table 4, PBO (ODPA-APAF-450C) polymer membranes made from poly (ODPA-APAF) polyimide membranes by heat treatment at 450 ° C. are 50 times more than normal cellulose acetate polymer membranes under the same test conditions. It can be seen that a high 545 Barrer CO ₂ permeability (P _CO2 ) was shown. However, the PBO (ODPA-APAF-450C) CO 2 / CH 4 selectivity of a polymer membrane (α _{CO2 /} CH4 = 22) is equivalent to the ordinary cellulose acetate polymer membrane. After crosslinking, the crosslinked PBO (ODPA-APAF-450C) polymer membrane has twice the CO ₂ / CH ₄ selectivity (α _{CO2 / CH4} = 45 compared to the uncrosslinked PBO (ODPA-APAF-450C) membrane. )showed that. The CO ₂ permeability (P _CO2 ) of the crosslinked PBO (ODPA-APAF-450C) polymer membrane is still more than 15 times higher than that of a normal cellulose acetate polymer membrane.

Example 15:
CO ₂ / CH ₄ separation performance of PBO (ODPA-APAF-400C) and crosslinked PBO (ODPA-APAF-400C) polymer membranes:
[0064] The PBO (ODPA-APAF-400C) and cross-linked PBO (ODPA-APAF-400C) polymer membranes prepared in Example 8 and Example 10, respectively, at 50 ° C. under a pure gas pressure of 690 kPa CO ₂ / Tested for CH ₄ separation (Table 5). From Table 5, PBO (ODPA-APAF-400C) polymer film made from poly (ODPA-APAF) polyimide film by heat treatment at 400 ° C. is 13 times more than normal cellulose acetate polymer film under the same test conditions. It can be seen that the high 143 Barrer CO ₂ permeability (P _CO2 ) was shown. The PBO (ODPA-APAF-400C) CO 2 / CH 4 selectivity of a polymer membrane (α _{CO2 /} CH4 = 32) is 45% higher than that of ordinary cellulose acetate polymer membrane. After crosslinking, the crosslinking PBO (ODPA-APAF-400C) polymer membranes, the uncrosslinked PBO (ODPA-APAF-400C) further increased _CO 2 / CH ₄ selectivity as compared to the film (α _{CO2 /} CH4 = 45 )showed that. The CO ₂ permeability (P _CO2 ) of the crosslinked PBO (ODPA-APAF-400C) polymer membrane is still 8 times higher than that of a normal cellulose acetate polymer membrane.

Comparative example:
[0065] Five process simulation examples were studied and high cross-linked cross-linked polybenzoxazole polymer membranes were compared to commercially available membranes. Comparative Example 1 was a single stage system using a currently commercially available membrane. Comparative Examples 2 and 3 were single stage systems using the highly gas permeable crosslinked PBO (BTDA-APAF-450C) membrane shown in Table 1. Comparative Examples 1 and 2 were operated at a feed stream temperature of 50 ° C. In these two examples, a pre-treatment called MemGuard using a molecular sieve developed by UOP LLC in order to obtain sufficient dew point margin to prevent condensation on the membrane surface during operation. A renewable adsorbent system was applied. Comparative Example 3 was operated at a high feed stream temperature of 100 ° C. due to the high thermal and mechanical stability of the crosslinked polybenzoxazole polymer membrane. Since a sufficient dew point margin was provided by operating the membrane system at high temperatures, a pretreatment system was not required in Comparative Example 3.

  [0066] In order to improve the recovery of hydrocarbons from natural gas streams, a two-stage membrane system was investigated. In Comparative Example 4, a commercially available membrane was used for both the first and second stages. For Comparative Example 4, a pretreatment system such as MemGuard would be necessary. In Comparative Example 5, a high gas permeable crosslinked PBO (BTDA-APAF-450C) membrane was used for both the first and second stage membranes. In Comparative Example 5, the first stage was operated at the elevated temperature to provide a sufficient dew point margin for the product gas. For Comparative Example 5, no pretreatment system was required. The second stage of Comparative Example 5 was operated at a feed stream temperature of 50 ° C. to increase membrane selectivity and reduce hydrocarbon loss. Since heavy hydrocarbons are difficult to reach the second stage feed stream, a pretreatment unit such as MemGuard was not necessary.

[0067] In Comparative Examples 1, 2, and 3, a natural gas feed stream having 8% CO ₂ was assumed. The product specification for CO ₂ is 2%. In Comparative Example 1, a commercially available membrane was considered to be a membrane with typical performance in the current natural gas reforming market. In Comparative Examples 2 and 3, a film having a thickness of 200 mm was produced using a crosslinked PBO (BTDA-APAF-450C) (shown in Table 1) film. The permeability of the novel high gas permeable crosslinked PBO (BTDA-APAF-450C) polymer membrane is 0.030 m ³ (STP) / m ² · h · at 50 ° C. based on the permeability measured for the dense membrane. Assuming that kPa is 0.044 m ³ (STP) / m ² · h · kPa at 100 ° C., the selectivity is 44 at 50 ° C. and 15 at 100 ° C. (this is shown in Table 1) Assumed to be lower than the selectivity). For Comparative Examples 1, 2, and 3, a process simulation based on the above performance was performed. The results are shown in Table 6.

  [0068] By comparing the above examples, Comparative Example 2 has significant cost savings (requires only 59.8% less membrane area) and higher hydrocarbon recovery (7.4%) than Comparative Example 1. It can be seen that it was high). Comparative Example 3 not only saves membrane area (82.6%), but also eliminates the high cost MemGuard pretreatment system with slightly lower hydrocarbon recovery. The new high gas permeable and highly selective cross-linked polybenzoxazole polymer membrane system is expected to greatly reduce the cost of the membrane system and the critical footprint for large offshore gas treatment projects. The

[0069] As shown in Comparative Examples 4 and 5, the hydrocarbon recovery can be increased by operating a two-stage membrane system. In Comparative Example 4, a commercially available membrane having performance data equivalent to that in Comparative Example 1 was applied at both stages. In Comparative Example 4, a crosslinked PBO (BTDA-APAF-450C) polymer film was used for both the first stage and the second stage. The first stage was operated at elevated temperature to eliminate the MemGuard system. The second stage was operated at a lower temperature to increase the selectivity. The natural gas feed stream in Comparative Examples 3 and 4 changed to 45% CO ₂ (more important for a two-stage system), and the product specification for CO ₂ in these two examples was considered 8%. Table 7 shows the results of the simulation for Comparative Examples 4 and 5.

  [0070] From Table 7, it can be seen that Comparative Example 4 and Comparative Example 5 have very similar hydrocarbon recovery rates. Due to the high temperature operation on the first stage membrane, Comparative Example 5 does not require pretreatment like the MemGuard system (which is 10-40% of the total cost of Comparative Example 4). At the same time, from Comparative Example 4 to Comparative Example 5, the area of the first stage film is reduced by 79.5% and the area of the second stage film is reduced by 59.2%. Comparative Example 5 can be expected to provide significant equipment cost savings (> 50%) and installation area savings (> 50%) compared to Comparative Example 4. The only drawback is that the compressor is slightly larger. Table 7 shows that the horsepower increases from Comparative Example 4 to Comparative Example 5 by 7.5%.

Claims (7)

A method of separating at least one gas or liquid from a mixture of gases or liquids using a crosslinked polybenzoxazole or polybenzothiazole polymer membrane,
(A) Providing a crosslinked polybenzoxazole or polybenzothiazole polymer film made from a crosslinkable polyimide polymer, wherein the crosslinkable polyimide polymer is a crosslinkable functional group found in the backbone of the crosslinkable polyimide polymer. And a pendant —OH or —SH group ortho to the heterocyclic imide nitrogen, and the crosslinkable polyimide polymer is first converted to a polybenzoxazole or polybenzothiazole polymer by thermal conversion, then The polybenzoxazole or polybenzothiazole polymer is subjected to a crosslinking treatment by UV radiation, and the crosslinked polybenzoxazole or polybenzothiazole polymer membrane is permeable to at least one gas or liquid ;
(B) contacting said cross-linked polybenzoxazole or a mixture of a plurality of gas or liquid on a surface of polybenzothiazole polymer film, at least one of gas or liquid the crosslinked polybenzoxazole or polybenzothiazole polymer film it transmits; and (c) from the opposite side of the film, to take out the permeate or a liquid composition is at least one gas or part of the liquid that has passed through the membrane;
Only containing the crosslinkable polyimide polymer is represented by the formula (II):

(Where X1 in formula (II) is

Or selected from the group consisting of these, wherein X2 in formula (II) is the same as X1, or

Or selected from the group consisting of these, -Y- in formula (II) is

Or selected from the group consisting of these, -Z-, -Z'-, and -Z "-are independently -O- or -S-, -R- is

Or selected from the group consisting of mixtures thereof. )
A method comprising a plurality of repeating units. The method according to claim 1, wherein a plurality of _{gas, CO 2 / CH 4, CO} 2 / N 2, H 2 / CH 4, O 2 / N 2, H 2 S / CH 4, olefin / A process which is a mixture selected from the group consisting of paraffin and isoparaffin / n-paraffin. The method according to claim 1, at least one said plurality of gas or liquid, methane, and carbon dioxide, oxygen, nitrogen, water vapor, is selected from the group consisting of hydrogen sulfide, helium, and other trace gases A method involving natural gas containing various gaseous components. The method according to claim 1, comprising the surface of the selective layer of the crosslinked polybenzoxazole and polybenzothiazole polymers membranes, polysiloxane, fluoropolymers, thermosetting silicone rubbers, and UV radiation curable epoxy silicone The method further comprising coating with a thin layer of a highly permeable material selected from the group. The method of claim 1, wherein X1 and X2 in formula (II) are the same,

And a group of these mixtures; Y in formula (II) is

And a method selected from the group of these mixtures. The method of claim 1, wherein X1 in formula (II) is

Or selected from the group of mixtures thereof; X2 in formula (II) is

Or selected from the group of these mixtures; Y in formula (II) is

Or a method selected from the group of these mixtures. The method of claim 1, wherein the polyimide polymer is poly [3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride-2,2-bis (3-amino-4-hydroxyphenyl). ) Hexafluoropropane] (poly (BTDA-APAF)), poly (3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride-3,3′-dihydroxy-4,4′-diamino-biphenyl) (Poly (BTDA-HAB)), poly [3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride-2,2-bis (3-amino-4-hydroxyphenyl) -hexafluoropropane] (Poly (DSDA-APAF)), poly (3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride-2,2-bis (3-amino-4-hydroxyphenyl) hexene Safluoropropane-3,3′-dihydroxy-4,4′-diaminobiphenyl (poly (DSDA-APAF-HAB)), poly [2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane Anhydride-3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride-2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane] (poly (6FDA-BTDA-APAF)) , Poly [4,4′-oxydiphthalic anhydride-2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane] (poly (ODPA-APAF)), poly [4,4′-oxydiphthalic acid Anhydride-2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane-3,3′-dihydroxy-4,4′-diaminobifu Nyl] (poly (ODPA-APAF-HAB)), poly [3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride-2,2-bis (3-amino-4-hydroxyphenyl) hexafluoro Propane-3,3′-dihydroxy-4,4′-diaminobiphenyl] (poly (BTDA-APAF-HAB)), and poly (4,4′-bisphenol A dianhydride-3,3 ′, 4,4 A process selected from the group consisting of '-benzophenonetetracarboxylic dianhydride-2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane] (poly (BPADA-BTDA-APAF)).