WO2010110975A2 - Membranes polymères de polybenzoxazole et de polybenzothiazole réticulés à haut rendement - Google Patents

Membranes polymères de polybenzoxazole et de polybenzothiazole réticulés à haut rendement Download PDF

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WO2010110975A2
WO2010110975A2 PCT/US2010/024855 US2010024855W WO2010110975A2 WO 2010110975 A2 WO2010110975 A2 WO 2010110975A2 US 2010024855 W US2010024855 W US 2010024855W WO 2010110975 A2 WO2010110975 A2 WO 2010110975A2
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membranes
cross
polymer
poly
membrane
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PCT/US2010/024855
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WO2010110975A3 (fr
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Chunqing Liu
Man-Wing Tang
Raisa Serbayeva
Lubo Zhou
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Uop Llc
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Priority claimed from US12/412,629 external-priority patent/US8127936B2/en
Priority claimed from US12/412,633 external-priority patent/US8127937B2/en
Application filed by Uop Llc filed Critical Uop Llc
Priority to CA2755923A priority Critical patent/CA2755923A1/fr
Priority to JP2012502061A priority patent/JP5607721B2/ja
Priority to CN2010800229646A priority patent/CN102448593A/zh
Priority to AU2010229241A priority patent/AU2010229241B2/en
Priority to KR1020117024855A priority patent/KR101392124B1/ko
Priority to EP10756536.8A priority patent/EP2411130A4/fr
Priority to BRPI1013695A priority patent/BRPI1013695A2/pt
Publication of WO2010110975A2 publication Critical patent/WO2010110975A2/fr
Publication of WO2010110975A3 publication Critical patent/WO2010110975A3/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/58—Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
    • B01D71/62—Polycondensates having nitrogen-containing heterocyclic rings in the main chain
    • B01D71/64—Polyimides; Polyamide-imides; Polyester-imides; Polyamide acids or similar polyimide precursors
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G75/00—Macromolecular compounds obtained by reactions forming a linkage containing sulfur with or without nitrogen, oxygen, or carbon in the main chain of the macromolecule
    • C08G75/32—Polythiazoles; Polythiadiazoles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/0083—Thermal after-treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/009—After-treatment of organic or inorganic membranes with wave-energy, particle-radiation or plasma
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/66—Polymers having sulfur in the main chain, with or without nitrogen, oxygen or carbon only
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • C08G73/1042—Copolyimides derived from at least two different tetracarboxylic compounds or two different diamino compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/22—Polybenzoxazoles
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/20—Manufacture of shaped structures of ion-exchange resins
    • C08J5/22—Films, membranes or diaphragms
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/08—Heat treatment
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L79/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen or carbon only, not provided for in groups C08L61/00 - C08L77/00
    • C08L79/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/30—Cross-linking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/34—Use of radiation
    • B01D2323/345—UV-treatment
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
    • C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/05—Polymer mixtures characterised by other features containing polymer components which can react with one another

Definitions

  • This invention pertains to high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes and methods for making and using these membranes.
  • Membrane-based technologies have advantages of both low capital cost and high-energy efficiency compared to conventional separation methods.
  • Membrane gas separation is of special interest to petroleum producers and refiners, chemical companies, and industrial gas suppliers.
  • Several applications have achieved commercial success, including carbon dioxide removal from natural gas and from biogas and enhanced oil recovery, and also in hydrogen removal from nitrogen, methane, and argon in ammonia purge gas streams.
  • UOP 's SeparexTM cellulose acetate polymeric membrane is currently an international market leader for carbon dioxide removal from natural gas.
  • the membranes most commonly used in commercial gas separation applications are polymeric and nonporous. Separation is based on a solution-diffusion mechanism. This mechanism involves molecular-scale interactions of the permeating gas with the membrane polymer. The mechanism assumes that in a membrane having two opposing surfaces, each component is sorbed by the membrane at one surface, transported by a gas concentration gradient, and desorbed at the opposing surface.
  • the membrane performance in separating a given pair of gases e.g., CO2/CH4, O2/N2, H2/CH4
  • P ⁇ the permeability coefficient
  • ⁇ / ⁇ selectivity
  • the P ⁇ is the product of the gas flux and the selective skin layer thickness of the membrane, divided by the pressure difference across the membrane.
  • Gases can have high permeability coefficients because of 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 an increase in the molecular size of the gas.
  • both high permeability and high selectivity are desirable because higher permeability decreases the size of the membrane area required to treat a given volume of gas, thereby decreasing capital cost of membrane units, and because higher selectivity results in a higher purity product gas.
  • Polymers provide a range of properties including low cost, good permeability, mechanical stability, and ease of processability that are important for gas separation.
  • a polymer material with a high glass-transition temperature (T 2 ), high melting point, and high crystallinity is preferred.
  • Glassy polymers i.e., polymers at temperatures below their Tg
  • polymers which are more permeable are generally less selective than less permeable polymers.
  • a general trade-off has always existed between permeability and selectivity (the so-called polymer upper bound limit). Over the past 30 years, substantial research effort has been directed to overcoming the limits imposed by this upper bound.
  • Various polymers and techniques have been used, but without much success.
  • traditional polymer membranes also have limitations in terms of thermal stability and contaminant resistance.
  • CA Cellulose acetate glassy polymer membranes are used extensively in gas separation.
  • CA membranes are used commercially for natural gas upgrading, including the removal of carbon dioxide.
  • CA membranes have many advantages, they are limited in a number of properties including selectivity, permeability, and in chemical, thermal, and mechanical stability. It has been found that polymer membrane performance can deteriorate quickly. The primary cause of loss of membrane performance is liquid condensation on the membrane surface. Condensation can be prevented by providing a sufficient dew point margin for operation, based on the calculated dew point of the membrane product gas.
  • UOP 's MemGuardTM system a regenerable adsorbent system that uses molecular sieves, was developed to remove water as well as heavy hydrocarbons from the natural gas stream, hence, to lower the dew point of the stream.
  • the selective removal of heavy hydrocarbons by a pretreatment system can significantly improve the performance of the membranes.
  • these pretreatment systems can effectively perform this function, the cost is quite significant.
  • the cost of the pretreatment system was as high as 10 to 40% of the total cost (pretreatment system and membrane system) depending on the feed composition. Reduction of the pretreatment system cost or total elimination of the pretreatment system would significantly reduce the membrane system cost for natural gas upgrading.
  • more and more membrane systems have been applied to large offshore natural gas upgrading projects.
  • the footprint of the pretreatment system is also very high at more than 10 to 50% of the footprint of the whole membrane system. Removal of the pretreatment system from the membrane system has great economic impact, especially to offshore projects.
  • High-performance polymers such as polyimides (PIs), poly(trimethylsilylpropyne) (PTMSP), and polytriazole have been developed to improve membrane selectivity, permeability, and thermal stability.
  • PIs polyimides
  • PTMSP poly(trimethylsilylpropyne)
  • polytriazole have been developed to improve membrane selectivity, permeability, and thermal stability.
  • These polymeric membrane materials have shown promising properties for separation of gas pairs such as CO2/CH4, O2/N2, H2/CH4, and propylene/propane (C ⁇ Hg/C ⁇ Hg).
  • CO2/CH4, O2/N2, H2/CH4 propylene/propane
  • current polymeric membrane materials have reached a limit in their productivity-selectivity trade-off relationship.
  • gas separation processes based on the use of glassy solution-diffusion membranes frequently suffer from plasticization of the stiff polymer matrix by the sorbed penetrant molecules such as CO2 or C3H5.
  • Aromatic polybenzoxazoles PBOs
  • polybenzothiazoles PBTs
  • polybenzimidazoles PBIs
  • PBOs Aromatic polybenzoxazoles
  • PBTs polybenzothiazoles
  • PBIs polybenzimidazoles
  • the membrane films exhibited 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 produced a minor increase in selectivity compared to the present invention which used different starting materials as well as a significantly higher membrane treating temperature.
  • a recent publication in the journal SCIENCE reported a new type of high permeability polybenzoxazole polymer membranes for gas separations (Ho Bum Park et al, SCIENCE 318, 254 (2007)). These polybenzoxazole membranes are prepared from high temperature thermal rearrangement of hydroxy-containing polyimide polymer membranes containing pendent hydroxyl groups ortho to the heterocyclic imide nitrogen.
  • polybenzoxazole polymer membranes exhibited extremely high CO2 permeability (>1000 Barrer) which is 100 times better than conventional polymer membranes and similar to that of some inorganic molecular sieve membranes but the CO2/CH4 selectivity was similar to commercial cellulose acetate membranes. Improved selectivity is needed for these membranes to be of commercial use.
  • the authors tried to increase the selectivity of these polybenzoxazole polymer membranes by adding small acidic dopants (e.g., HCl and H3PO4).
  • small acidic dopants e.g., HCl and H3PO4
  • the present invention overcomes the problems of both the prior art polymer membranes and inorganic molecular sieve membranes by providing a new type of high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes and a route to make said membranes that have the following properties/advantages: ease of processability, both high selectivity and high permeation rate or flux, high thermal stability, and stable flux and sustained selectivity over time by resistance to solvent swelling, plasticization and hydrocarbon contaminants. These membranes provide much better permeability when compared to crosslinked polyimide membranes and much better selectivity when compared to uncrosslinked polybenzoxazole membranes.
  • This invention pertains to high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes and methods for making and using these membranes.
  • the high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes are prepared from cross-linkable polyimide polymers comprising both UV cross-linkable functional groups in the polymer backbone and pendent functional groups (e.g., -OH or -SH groups) ortho to the heterocyclic imide nitrogen by thermal conversion followed by UV radiation.
  • the high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes described in the current invention comprise polybenzoxazole or polybenzothiazole polymer chain segments wherein at least a part of these polymer chain segments are cross-linked to each other through possible direct covalent bonds by exposure to UV radiation.
  • the cross-linking of the polybenzoxazole and polybenzothiazole polymer membranes offers the membranes significantly improved membrane selectivity and chemical and thermal stability.
  • cross-linked polybenzoxazole and polybenzothiazole polymer membranes overcome the problems of both the prior art polymer membranes and inorganic molecular sieve membranes with advantages of ease of processability, high selectivity, high permeation rate or flux, high thermal stability, and stable flux and sustained selectivity over time by resistance to solvent swelling, plasticization and hydrocarbon contaminants.
  • a method for the production of the high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes comprises: 1) first synthesizing aromatic polyimide polymers comprising pendent functional groups (e.g., -OH or -SH) ortho to the heterocyclic imide nitrogen and UV cross-linkable functional groups (e.g., carbonyl group) in the polymer backbone; 2) fabricating polyimide membranes from the aromatic polyimide polymers synthesized in step 1); 3) converting the polyimide membranes to polybenzoxazole or polybenzothiazole membranes by heating between 300° and 600 0 C under inert atmosphere, such as argon, nitrogen, or vacuum; and 4) finally converting the polybenzoxazole or polybenzothiazole membranes to cross-linked polybenzoxazole or polybenzothiazole polymer membranes by exposure to UV radiation.
  • pendent functional groups e.g., -OH or -SH
  • UV cross-linkable functional groups
  • a membrane post-treatment step can be added after the exposure to UV radiation in which the selective layer surface of the cross-linked polybenzoxazole or polybenzothiazole polymer membranes is coated with a thin layer of high permeability material such as a polysiloxane, a fluoro-polymer, a thermally curable silicone rubber, or a UV radiation curable epoxy silicone.
  • a polysiloxane such as a polysiloxane, a fluoro-polymer, a thermally curable silicone rubber, or a UV radiation curable epoxy silicone.
  • the cross-linked polybenzoxazole and polybenzothiazole polymer membranes can have either a nonporous symmetric structure or an asymmetric structure with a thin nonporous dense selective layer supported on top of a porous support layer. These membranes can be fabricated into any convenient geometry such as flat sheet (or spiral wound), disk, tube, hollow fiber, or thin film composite.
  • the invention provides a process for separating at least one gas or liquid from a mixture of gases or liquids using either the cross-linked polybenzoxazole polymer membrane or the cross-linked polybenzothiazole polymer membrane.
  • the process comprises providing a cross-linked polybenzoxazole or polybenzothiazole polymer membrane which is permeable to at least one gas or liquid; contacting the mixture of gases or liquids on one side of the cross-linked polybenzoxazole or polybenzothiazole polymer membrane to cause at least one gas or liquid to permeate the cross-linked polybenzoxazole or polybenzothiazole polymer membrane; and removing from the opposite side of the membrane a permeate gas or liquid composition that is a portion of at least one gas or liquid which permeated the membrane.
  • the high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes are not only suitable for a variety of liquid, gas, and vapor separations such as desalination of water by reverse osmosis, non-aqueous liquid separation such as deep desulfurization of gasoline and diesel fuels, ethanol/water separations, pervaporation dehydration of aqueous/organic mixtures, CO2/CH4, CO2/N2, H2/CH4, O2/N2, H2S/CH4, olefin/paraffin, iso/normal paraffins separations, and other light gas mixture separations, but also can be used for other applications such as for catalysis and fuel cell applications.
  • liquid, gas, and vapor separations such as desalination of water by reverse osmosis, non-aqueous liquid separation such as deep desulfurization of gasoline and diesel fuels, ethanol/water separations, pervaporation dehydration of aqueous/organic mixtures, CO2/CH4, CO2/N2, H2/CH4,
  • Tullos et al. reported the synthesis of a series of hydroxy-containing polyimide polymers containing pendent hydroxyl groups ortho to the heterocyclic imide nitrogen. These polyimides were found to undergo thermal conversion to polybenzoxazoles upon heating between 350° and 500 0 C under nitrogen or vacuum. (Tullos et al, MACROMOLECULES, 32, 3598 (1999))
  • a recent publication in SCIENCE reported a further study that the polybenzoxazole polymer materials reported by Tullos et al. possessed tailored free volume elements with well-connected morphology.
  • the unusual microstructure in these polybenzoxazole polymer materials can be systematically tailored using thermally-driven segment rearrangement, providing a route for preparing polybenzoxazole polymer membranes for gas separations. See Ho Bum Park et al, SCIENCE, 318, 254 (2007). These polybenzoxazole polymer membranes exhibited extremely high CO2 permeability (>1000 Barrer) which is 100 times better than conventional polymer membranes and similar to that of some inorganic molecular sieve membranes but lower CO2/CH4 selectivity than that of some small pore inorganic molecular sieve membranes for CO2/CH4 separation. [0021]
  • the present invention involves novel high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes and methods for making and using these membranes.
  • the present invention overcomes the problems of both the prior art polymer membranes and inorganic molecular sieve membranes by providing a new type of high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes and a route to make these membranes that have the properties/advantages of ease of processability, both high selectivity and high permeation rate or flux, high thermal stability, and stable flux and sustained selectivity over time by resistance to solvent swelling, plasticization and deterioration by exposure to hydrocarbon contaminants.
  • the high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes described in the current invention are prepared from cross-linkable polyimide polymers comprising both UV cross-linkable functional groups (e.g., carbonyl group) in the polymer backbone and pendent functional groups (e.g., -OH or -SH) ortho to the heterocyclic imide nitrogen via thermal conversion followed by UV radiation.
  • the membranes comprise polybenzoxazole or polybenzothiazole polymer chain segments wherein at least a portion of these polymer chain segments are cross-linked to each other through direct covalent bonds by exposure to UV radiation.
  • the cross-linking of the polybenzoxazole and polybenzothiazole polymer membranes offers the membranes significantly improved membrane selectivity and chemical and thermal stabilities.
  • the present invention provides a method for the production of these high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes by: 1) first synthesizing aromatic polyimide polymers comprising pendent functional groups (e.g., - OH or -SH) ortho to the heterocyclic imide nitrogen and UV cross-linkable functional groups (e.g., carbonyl group) in the polymer backbone; 2) fabricating polyimide membranes from the aromatic polyimide polymers synthesized in step 1); 3) converting the polyimide membranes to polybenzoxazole or polybenzothiazole membranes by heating between 300° and 600 0 C under inert atmosphere, such as argon, nitrogen, or vacuum; and 4) finally converting the polybenzoxazole or polybenzothiazole membranes to cross-linked polybenzox
  • a membrane post-treatment step can be added after the UV radiation in which the selective layer surface of the cross-linked polybenzoxazole or polybenzothiazole polymer membranes are coated with a thin layer of high permeability material such as a polysiloxane, a fluoro-polymer, a thermally curable silicone rubber, or a UV radiation curable epoxy silicone.
  • the polybenzoxazole-type and polybenzothiazole-type of polymer membranes used in the present invention for the preparation of cross-linked polybenzoxazole and polybenzothiazole polymer membranes are prepared from thermal conversion of polyimide membranes upon heating between 300° and 600 0 C under inert atmosphere, such as argon, nitrogen, or vacuum.
  • the polyimide membranes are fabricated from soluble polyimides with UV cross-linkable functional groups in the polymer backbone (e.g., carbonyl group) and pendent functional groups (e.g., -OH or -SH) ortho to the heterocyclic imide nitrogen by a solution casting or solution spinning method.
  • the thermal conversion of the polyimide with pendent functional groups (e.g., -OH or -SH) ortho to the heterocyclic imide nitrogen results in the formation of polybenzoxazole (if the pendent functional groups are -OH groups) or polybenzothiazole (if the pendent functional groups are -SH groups) by irreversible molecular rearrangement, and is accompanied by loss of carbon dioxide with no other volatile byproducts being generated.
  • the polybenzoxazole and polybenzothiazole polymers comprise the repeating units of a formula (I), wherein said formula (I) is:
  • the UV cross-linkable polyimide polymers containing pendent functional groups ortho to the heterocyclic imide nitrogen, that are used for the preparation of high performance cross-linked polybenzoxazole -type and polybenzothiazole-type of membranes in the present invention comprise a plurality of first repeating units of a formula (II), wherein formula (II) is:
  • X2 of formula (II) is either the same as Xl or is selected from
  • -Z-, -Z'-, and -Z"- are independently -O- or -S-, -R- is
  • Y of formula (II) is selected from the group of:
  • Xl of formula (II) is selected from the group of:
  • X2 of said formula (II) is selected from the group of:
  • Y of formula (II) is selected from the group of:
  • poly(BTDA-APAF) poly[3,3',4,4'-benzophenonetetracarboxylic dianhydride-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'-diamino-biphenyl)
  • poly(BTDA-HAB) poly[3,3',4,4'- diphenylsulfone te
  • the polyimides comprising UV cross-linkable functional groups and pendent functional groups (e.g., -OH or -SH) ortho to the heterocyclic imide nitrogen in the polymer backbone that are used for the preparation of the cross-linked polybenzoxazole and polybenzithiazole polymer membranes in the present invention are synthesized from diamines and dianhydrides in polar solvents such as l-methyl-2-pyrrolidione (NMP) or N ,N- dimethylacetamide (DMAc) by a two-step process involving the formation of the poly(amic acid)s followed by a solution imidization or a thermal imidization.
  • polar solvents such as l-methyl-2-pyrrolidione (NMP) or N ,N- dimethylacetamide (DMAc)
  • 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 regarding the preparation of these polymers can be found in Tullos et al, MACROMOLECULES, 32, 3598 (1999).
  • the polyimide membrane that is used for the preparation of high performance cross-linked polybenzoxazole-type or polybenzothiazole-type of membrane in the present invention can be fabricated into a membrane with nonporous symmetric thin film geometry from the polyimide polymer comprising UV cross-linkable functional groups and pendent functional groups (e.g., -OH or -SH) ortho to the heterocyclic imide nitrogen in the polymer backbone by casting a homogeneous polyimide solution on top of a clean glass plate and allowing the solvent to evaporate slowly inside a plastic cover for at least 12 hours at room temperature. The membrane is then detached from the glass plate and dried at room temperature for 24 hours and then at 200 0 C for at least 48 hours under vacuum.
  • UV cross-linkable functional groups and pendent functional groups e.g., -OH or -SH
  • the solvents used for dissolving the polyimide polymer are chosen primarily for their ability to completely dissolve the polymers and for ease of solvent removal in the membrane formation steps. Other considerations in the selection of solvents include low toxicity, low corrosive activity, low environmental hazard potential, availability and cost.
  • Representative solvents for use in this invention include most amide solvents that are typically used for the formation of polymeric membranes, such as N-methylpyrrolidone
  • NMP N,N-dimethyl acetamide
  • DMAC N,N-dimethyl acetamide
  • methylene chloride tetrahydrofuran
  • THF tetrahydrofuran
  • acetone acetone
  • DMF dimethyl sulfoxide
  • toluene dioxanes, 1,3-dioxolane, mixtures thereof, others known to those skilled in the art and mixtures thereof.
  • the polyimide membrane that is used for the preparation of high performance cross-linked polybenzoxazole-type or polybenzothiazole-type of membrane in the present invention can also be fabricated by a method comprising the steps of: dissolving the polyimide polymer in a solvent to form a solution of the polyimide material; contacting a porous membrane support (e.g., a support made from inorganic ceramic material) with this solution; and then evaporating the solvent to provide a thin selective layer comprising the polyimide polymer material on the supporting layer.
  • a porous membrane support e.g., a support made from inorganic ceramic material
  • the polyimide membrane can also be fabricated as an asymmetric membrane with a flat sheet or hollow fiber geometry by phase inversion followed by direct air drying through the use of at least one drying agent which is a hydrophobic organic compound such as a hydrocarbon or an ether (see US 4,855,048).
  • the polyimide membrane can also be fabricated as an asymmetric membrane with flat sheet or hollow fiber geometry by phase inversion followed by solvent exchange (see US 3,133,132).
  • the polyimide membrane is then converted to a polybenzoxazole or polybenzothiazole polymer membrane by heating between 300 0 C and 600 0 C, preferably from 400 0 C to 500 0 C and most preferably from 400 0 C to 45O 0 C under inert atmosphere, such as argon, nitrogen, or vacuum.
  • the heating time for this heating step is in a range of 30 seconds to 2 hours. A more preferred heating time is from 30 seconds to 1 hour.
  • the cross-linked polybenzoxazole or polybenzothiazole polymer membrane is then formed by UV-cross- linking the polybenzoxazole or polybenzothiazole polymer membrane using a UV lamp from a predetermined distance and for a period of time selected based upon the separation properties sought.
  • a cross-linked polybenzoxazole or polybenzothiazole polymer membrane can be prepared from a polybenzoxazole or polybenzothiazole polymer membrane by exposure to UV radiation using 254 nm wavelength UV light generated from a UV lamp with 1.9 cm (0.75 inch) distance from the membrane surface to the UV lamp and a radiation time of 30 minutes at less than 5O 0 C.
  • the UV lamp described here is a low pressure, mercury arc immersion UV quartz 12 watt lamp with 12 watt power supply from Ace Glass Incorporated. Optimization of the cross-linking degree in the cross-linked polybenzoxazole and polybenzothiazole polymer membranes should promote the tailoring of the membranes for a wide range of gas and liquid separations with improved permeation properties and environmental stability.
  • the cross-linking degree of the cross-linked polybenzoxazole and polybenzothiazole polymer membranes can be controlled by adjusting the distance between the UV lamp and the membrane surface, UV radiation time, wavelength and strength of UV light, etc.
  • the distance from the UV lamp to the membrane surface is in the range of 0.8 to 25.4 cm (0.3 to 10 inches) with a UV light provided from 12 watt to 450 watt low pressure or medium pressure mercury arc lamp, and the UV radiation time is in the range of 0.5 minute to 1 hour. More preferably, the distance from the UV lamp to the membrane surface is in the range of 1.3 to 5.1 cm (0.5 to 2 inches) with a UV light provided from 12 watt to 450 watt low pressure or medium pressure mercury arc lamp, and the UV radiation time is in the range of 0.5 to 40 minutes.
  • a membrane post-treatment step can be added after the formation of the cross-linked polybenzoxazole or polybenzothiazole polymer membrane with the application of a thin layer of a high permeability material such as a polysiloxane, a fluoro- polymer, a thermally curable silicone rubber, or a UV radiation curable epoxy silicone.
  • a high permeability material such as a polysiloxane, a fluoro- polymer, a thermally curable silicone rubber, or a UV radiation curable epoxy silicone.
  • the high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes of the present invention can have either a nonporous symmetric structure or an asymmetric structure with a thin nonporous dense selective layer supported on top of a porous support layer.
  • the porous support can be made from the same cross-linked polybenzoxazole or polybenzothiazole polymer material or a different type of organic or inorganic material with high thermal stability.
  • the high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes of the present invention can be fabricated into any convenient geometry such as flat sheet (or spiral wound), disk, tube, hollow fiber, or thin film composite.
  • the invention provides a process for separating at least one gas or liquid from a mixture of gases or liquids using the cross-linked polybenzoxazole and polybenzothiazole polymer membranes, the process comprising: (a) providing a cross-linked polybenzoxazole or polybenzothiazole polymer membrane which is permeable to at least one gas or liquid; (b) contacting the mixture to one side of the cross-linked polybenzoxazole or polybenzothiazole polymer membrane to cause at least one gas or liquid to permeate the cross-linked polybenzoxazole or polybenzothiazole polymer membrane; and (c) then removing from the opposite side of the membrane a permeate gas or liquid composition comprising a portion of at least one gas or liquid which permeated the membrane.
  • These high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes are especially useful in the purification, separation or adsorption of a particular species in the liquid or gas phase.
  • these high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes may, for example, be used for the desalination of water by reverse osmosis or for the separation of proteins or other thermally unstable compounds, e.g. in the pharmaceutical and biotechnology industries.
  • the high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes may also be used in fermenters and bioreactors to transport gases into the reaction vessel and transfer cell culture medium out of the vessel.
  • the high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes may be used for the removal of microorganisms from air or water streams, water purification, ethanol production in a continuous fermentation/membrane pervaporation system, and in detection or removal of trace compounds or metal salts in air or water streams.
  • the cross-linked polybenzoxazole and polybenzothiazole polymer membranes of the present invention are especially useful in gas separation processes in air purification, petrochemical, refinery, and natural gas industries.
  • separations include separation of volatile organic compounds (such as toluene, xylene, and acetone) from an atmospheric gas, such as nitrogen or oxygen and nitrogen recovery from air.
  • Further examples of such separations are for the separation of CO2 or H2S from natural gas, H2 from N2, CH4, and Ar in ammonia purge gas streams, H2 recovery in refineries, olefin/paraffin separations such as propylene/propane separation, and iso/normal 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 using the cross-linked polybenzoxazole or polybenzothiazole polymer membranes described herein. More than two gases can be removed from a third gas.
  • some of the gas components which can be selectively removed from a raw natural gas using the membrane described herein include carbon dioxide, oxygen, nitrogen, water vapor, hydrogen sulfide, helium, and other trace gases.
  • Some of the gas components that can be selectively retained include hydrocarbon gases.
  • permeable components are acid components selected from the group consisting of carbon dioxide, hydrogen sulfide, and mixtures thereof and are removed from a hydrocarbon mixture such as natural gas
  • one module, or at least two in parallel service, or a series of modules may be utilized to remove the acid components.
  • the pressure of the feed gas may vary from 275 kPa to 2.6 MPa (25 to 4000 psi).
  • the differential pressure across the membrane can be as low as 0.7 bar or as high as 145 bar (10 psi or as high as 2100 psi) depending on many factors such as the particular membrane used, the flow rate of the inlet stream and the availability of a compressor to compress the permeate stream if such compression is desired.
  • Differential pressure greater than 145 bar (2100 psi) may rupture the membrane.
  • a differential pressure of at least 7 bar (100 psi) is preferred since lower differential pressures may require more modules, more time and compression of intermediate product streams.
  • the operating temperature of the process may vary depending upon the temperature of the feed stream and upon ambient temperature conditions.
  • the effective operating temperature of the membranes of the present invention will range from - 50° to 15O 0 C. More preferably, the effective operating temperature of the membranes of the present invention will range from -20° to 100 0 C, and most preferably, the effective operating temperature of the membranes of the present invention will range from 25° to 100 0 C.
  • the cross-linked polybenzoxazole and polybenzothiazole polymer membranes are especially useful in gas/vapor separation processes in chemical, petrochemical, pharmaceutical and allied industries for removing organic vapors from gas streams, e.g. in off-gas treatment for recovery of volatile organic compounds to meet clean air regulations, or within process streams in production plants so that valuable compounds (e.g., vinylchloride monomer, propylene) may be recovered.
  • gas/vapor separation processes in which these cross-linked polybenzoxazole and polybenzothiazole polymer membranes may be used are hydrocarbon vapor separation from hydrogen in oil and gas refineries, for hydrocarbon dew pointing of natural gas (i.e.
  • the cross-linked polybenzoxazole and polybenzothiazole polymer membranes may incorporate a species that adsorbs strongly to certain gases (e.g. cobalt porphyrins or phthalocyanines for O2 or silver(I) for ethane) to facilitate their transport across the membrane.
  • gases e.g. cobalt porphyrins or phthalocyanines for O2 or silver(I) for ethane
  • the cross-linked polybenzoxazole and polybenzothiazole polymer membranes can be operated at high temperature to provide the sufficient dew point margin for natural gas upgrading (e.g, CO2 removal from natural gas).
  • the cross-linked polybenzoxazole and polybenzothiazole polymer membranes can be used in either a single stage membrane or as the first and/or second stage membrane in a two stage membrane system for natural gas upgrading.
  • the high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes with high selectivity, high permeance, and high thermal and chemical stabilities of the present invention allow the membranes to be operated without a costly pretreatment system.
  • a costly membrane pretreatment system such as an adsorbent MemGuardTM system would not be required in the new process containing the cross-linked polybenzoxazole or polybenzothiazole polymer membrane system.
  • cross-linked polybenzoxazole and polybenzothiazole polymer membranes may also be used in the separation of liquid mixtures by pervaporation, such as in the removal of organic compounds (e. g., alcohols, phenols, chlorinated hydrocarbons, pyridines, ketones) from water such as aqueous effluents or process fluids.
  • organic compounds e. g., alcohols, phenols, chlorinated hydrocarbons, pyridines, ketones
  • the cross-linked polybenzoxazole or polybenzothiazole polymer membrane which is ethanol-selective would be used to increase the ethanol concentration in relatively dilute ethanol solutions (5-10% ethanol) obtained by fermentation processes.
  • Another liquid phase separation example using these cross-linked polybenzoxazole and polybenzothiazole polymer membranes is the deep desulfurization of gasoline and diesel fuels by a pervaporation membrane process similar to the process described in US 7,048,846, incorporated by reference herein in its entirety.
  • the cross-linked polybenzoxazole and polybenzothiazole polymer membranes that are selective to sulfur-containing molecules would be used to selectively remove sulfur-containing molecules from fluid catalytic cracking (FCC) and other naphtha hydrocarbon streams.
  • Further liquid phase examples include the separation of one organic component from another organic component, e. g. to separate isomers of organic compounds.
  • Mixtures of organic compounds which may be separated using the cross-linked polybenzoxazole or polybenzothiazole polymer membrane include: ethylacetate-ethanol, diethylether-ethanol, acetic acid-ethanol, benzene-ethanol, chloroform-ethanol, chloroform-methanol, acetone- isopropylether, allylalcohol-allylether, allylalcohol-cyclohexane, butanol-butylacetate, butanol-1-butylether, ethanol-ethylbutylether, propylacetate-propanol, isopropylether- isopropanol, methanol-ethanol-isopropanol, and ethylacetate-ethanol-acetic acid.
  • the cross-linked polybenzoxazole and polybenzothiazole polymer membranes may be used for separation of organic molecules from water (e.g. ethanol and/or phenol from water by pervaporation) and removal of metal and other organic compounds from water.
  • the cross-linked polybenzoxazole and polybenzothiazole polymer membranes have immediate application for the separation of gas mixtures including carbon dioxide removal from natural gas.
  • the membrane permits carbon dioxide to diffuse through at a faster rate than the methane in the natural gas.
  • Carbon dioxide has a higher permeation rate than methane because of higher solubility, higher diffusivity, or both.
  • carbon dioxide enriches on the permeate side of the membrane, and methane enriches on the feed (or reject) side of the membrane.
  • the cross-linked polybenzoxazole and polybenzothiazole polymer membranes also have immediate application to concentrate olefin in a paraffin/olefin stream for olefin cracking application.
  • the cross-linked polybenzoxazole and polybenzothiazole polymer membranes can be used for propylene/propane separation 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 stages of propylene/propane splitter that is required to get polymer grade propylene can be reduced.
  • cross-linked polybenzoxazole and polybenzothiazole polymer membranes Another application for the cross-linked polybenzoxazole and polybenzothiazole polymer membranes is for separating isoparaff ⁇ n and normal paraffin in light paraffin isomerization and MaxEneTM, a process for enhancing the concentration of normal paraffin (n-paraffm) in the naphtha cracker feedstock, which can be then converted to ethylene.
  • An additional application of the cross-linked polybenzoxazole and polybenzothiazole polymer membranes is as the separator in chemical reactors to enhance the yield of equilibrium-limited reactions by selective removal of a specific substance.
  • the high performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes of the present invention are suitable for a variety of liquid, gas, and vapor separations such as desalination of water by reverse osmosis, non- aqueous liquid separation such as deep desulfurization of gasoline and diesel fuels, ethanol/water separations, 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 , olefin/paraffm, iso/normal paraffins separations, and other light gas mixture separations.
  • liquid, gas, and vapor separations such as desalination of water by reverse osmosis, non- aqueous liquid separation such as deep desulfurization of gasoline and diesel fuels, ethanol/water separations, pervaporation dehydration of aqueous/organic mixtures, CO 2 /CH 4 ,
  • An aromatic poly[3,3',4,4'-benzophenonetetracarboxylic dianhydride-2,2-bis(3- amino-4-hydroxyphenyl)-hexafluoropropane] (poly(BTDA-APAF)) polyimide containing UV cross-linkable carbonyl groups and pendent -OH functional groups ortho to the heterocyclic imide nitrogen in the polymer backbone was synthesized from 2,2-bis(3-amino- 4-hydroxyphenyl)-hexafluoropropane diamine (BTDA) and 3,3',4,4'- benzophenonetetracarboxylic dianhydride (APAF) in NMP polar solvent by a two-step process involving the formation of the poly(amic acid) followed by a solution imidization process.
  • BTDA-APAF 2,2-bis(3-amino- 4-hydroxyphenyl)-hexafluoropropane diamine
  • APAF 3,3',4,4'- benzophen
  • Acetic anhydride was used as the dehydrating agent and pyridine was used as the imidization catalyst for the solution imidization reaction.
  • a 250 mL three-neck round-bottom flask equipped with a nitrogen inlet and a mechanical stirrer was charged with 10.0 g (27.3 mmol) of APAF and 40 mL of NMP.
  • a solution of BTDA (8.8 g, 27.3 mmol) in 40 mL of NMP was added to the APAF solution in the flask.
  • the reaction mixture was mechanically stirred for 24 hours at ambient temperature to give a viscous poly(amic acid) solution.
  • the aromatic poly[4,4'-oxydiphthalic anhydride-2,2-bis(3-amino-4- hydroxyphenyl)-hexafluoropropane] (poly(ODP A-AP AF)) polyimide containing pendent - OH functional groups ortho to the heterocyclic imide nitrogen in the polymer backbone was synthesized from 4,4'-oxydiphthalic anhydride (ODPA) and 2,2-bis(3-amino-4- hydroxyphenyl)-hexafluoropropane (APAF) in NMP polar solvent by a two-step process involving the formation of the poly(amic acid) followed by a solution imidization process.
  • ODPA 4,4'-oxydiphthalic anhydride
  • APAF 2,2-bis(3-amino-4- hydroxyphenyl)-hexafluoropropane
  • Acetic anhydride was used as the dehydrating agent and pyridine was used as the imidization catalyst for the solution imidization reaction.
  • a 250 mL three-neck round- bottom flask equipped with a nitrogen inlet and a mechanical stirrer was charged with 10.0 g (27.3 mmol) of APAF and 20 mL of NMP.
  • 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 for 24 hours at ambient temperature to give a viscous poly(amic acid) solution.
  • the poly(BTDA-APAF) polymer membrane was prepared as follows: 4.0 g of poly(BTD A-AP AF) polyimide synthesized in Example 1 was dissolved in a solvent mixture of 12.0 g of NMP and 12.0 g of 1,3-dioxolane. The mixture was mechanically stirred for 2 h to form a homogeneous casting dope. The resulting homogeneous casting dope was allowed to degas overnight.
  • the poly(BTDA-APAF) polymer membrane was prepared from the bubble free casting dope on a clean glass plate using a doctor knife with a 20-mil gap. The membrane together with the glass plate was then put into 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 0 C under vacuum for at least 48 hours to completely remove the residual solvents to form poly(BTDA-APAF) polymer membrane.
  • the polybenzoxazole polymer membrane PBO(BTD A- AP AF-45 OC) was prepared by thermally heating the poly(BTD A-AP AF) polymer membrane prepared in Example 3 from 5O 0 C to 450 C at a heating rate of 5°C/min under N 2 flow. The membrane was hold for 1 hour at 45O 0 C and then cooled down to 5O 0 C at a heating rate of 5°C/min under N 2 flow.
  • cross-linked PBO(BTD A- AP AF -45 OC) polybenzoxazole polymer membrane (abbreviated as cross-linked PBO(BTD A- AP AF-45 OC))
  • Cross-linked PBO(BTD A- AP AF-45 OC) polymer membrane was prepared by UV cross-linking the PBO(BTD A- AP AF -45 OC) polymer membrane prepared in Example 4 by exposure to UV radiation using 254 nm wavelength UV light generated from a UV lamp with 1.9 cm (0.75 inch) distance from the membrane surface to the UV lamp and a radiation time of 20 minutes at 5O 0 C.
  • the UV lamp that was used was a low pressure, mercury arc immersion UV quartz 12 watt lamp with 12 watt power supply from Ace Glass Incorporated.
  • poly(ODPA-APAF) polymer membrane was prepared using similar procedures as described in Example 3, but poly(BTDA-APAF) polyimide synthesized in Example 2 was used in this example.
  • the polybenzoxazole polymer membrane PBO(ODP A- AP AF-45 OC) was prepared by thermally heating the poly(ODPA-APAF) polymer membrane prepared in Example 6 using similar procedures as described in Example 4.
  • the polybenzoxazole polymer membrane PBO(ODP A- AP AF-400C) was prepared by thermally heating the poly(ODPA-APAF) polymer membrane prepared in Example 6 from 5O 0 C to 400 0 C at a heating rate of 5°C/min under N 2 flow. The membrane was hold for 1 hour at 400 0 C and then cooled down to 50 0 C at a heating rate of 5°C/min under N2 flow.
  • Cross-linked PBO(ODP A- AP AF-45 OC) polymer membrane was prepared by UV cross-linking the PBO(ODP A- AP AF -45 OC) polymer membrane prepared in Example 7 by exposure to UV radiation using 254 nm wavelength UV light generated from a UV lamp with 1.9 cm (0.75 inch) distance from the membrane surface to the UV lamp and a radiation time of 20 minutes at 5O 0 C.
  • the UV lamp that was used was a low pressure, mercury arc immersion UV quartz 12 watt lamp with 12 watt power supply from Ace Glass Incorporated.
  • Cross-linked PBO(ODP A- AP AF-400C) polymer membrane was prepared by UV cross-linking the PBO(ODP A- AP AF -400C) polymer membrane prepared in Example 8 by exposure to UV radiation using 254 nm wavelength UV light generated from a UV lamp with 1.9 cm (0.75 inch) distance from the membrane surface to the UV lamp and a radiation time of 20 minutes at 5O 0 C.
  • the UV lamp that was used was a low pressure, mercury arc immersion UV quartz 12 watt lamp with 12 watt power supply from Ace Glass Incorporated.
  • the cross-linked PBO(BTD A-AP AF-450C) polymer membrane showed significantly increased CO2/CH4 selectivity (48.4 at 50 0 C testing temperature) compared to the PBO(BTDA-APAF- 450C) membrane at both 50 0 C and 100 0 C testing temperature, respectively.
  • a Pco2 and P CH 4 were tested at 5O 0 C and 690 kPa (100 psig); b Pco2 and P CH 4 were tested at 100 0 C and 690 kPa (100 psig);
  • the CO2 permeability (PcO2) of the cross-linked PBO(ODP A- AP AF-45 OC) polymer membrane is still more than 15 times higher than that of the conventional cellulose acetate polymer membrane.
  • the CO2 permeability (PcO2) of me cross-linked PBO(ODP A- AP AF-400C) polymer membrane is still 8 times higher than that of the conventional cellulose acetate polymer membrane.
  • Comparable Example 1 was a single stage system using the currently commercially available membranes.
  • Comparable Examples 2 and 3 were single stage systems using the high gas permeability cross-linked PBO(BTD A- AP AF -45 OC) membrane listed in Table 1.
  • Comparable Example 1 and Example 2 were operated at feed temperature of 50 0 C.
  • MemGuardTM that uses molecular sieves developed by UOP LLC, was applied in these two examples.
  • Comparable Example 3 was operated at high feed temperature of 100 0 C due to the high thermal and mechanical stability of the cross-linked polybenzoxazole polymer membranes. Since sufficient dew point margin was provided by operating the membrane system at the high temperature, no pretreatment system was required in Comparable Example 3.
  • MemGuardTM would be required for Comparable Example 4.
  • high gas permeability cross-linked PBO(BTD A-AP AF -450C) membrane was used for both first- and second-stage membranes.
  • Comparable Example 5 operated the first stage at an elevated temeprature to provide a sufficient dew point margin for the product gas.
  • No pretreatment system was required for Comparable Example 5.
  • the second stage of Comparable Example 5 was operated at 50 0 C feed temperature to increase the membrane selectivity, hence, reduce the hydrocarbon loss. Since heavy hydrocarbons are hard to reach a second stage feed, the pretreatment unit such as MemGuardTM was not required.
  • Comparable Examples 1, 2, and 3 assumed a natural gas feed with 8% CO2, and the product spec for CO2 is at 2%.
  • Comparable Example 1 the commercially available membrane was assumed to be a membrane with typical performance in the current natural gas upgrading market.
  • Comparable Examples 2 and 3 the cross-linked PBO(BTDA-APAF- 450C) (shown in Table 1) material was used to make the membrane with a thickness of 200 nm.
  • the permeance of the new high gas permeability cross-linked PBO(BTDA-AP AF-450C) polymer membrane was assumed at 0.030 m 3 (STP)/m 2 .h.kPa at 5O 0 C and 0.044 m3(STP)/m2.h.kPa at 100 0 C based on the permeability measured for the dense membrane, and the selectivities were assumed at 44 at 5O 0 C and 15 at 100 0 C, which are lower than the selectivities shown in Table 1.
  • a process simulation based on the above performance was performed for Comparable Examples 1, 2 and 3. The results are shown in Table 6.
  • Comparable Example 2 showed significant cost saving (59.8% less membrane area required) and higher hydrocarbon recovery (7.4% more) compared to Comparable Example 1.
  • Comparable Example 3 not only can save the membrane area (82.6%), but also can eliminate the costly MemGuardTM pretreatment system at slightly lower hydrocarbon recovery. It is anticipated that the new high gas permeability and high selectivity cross-linked polybenzoxazole polymer membrane system will significantly reduce the membrane system cost and footprint which is extremely important for large offshore gas processing projects.
  • the hydrocarbon recovery can be increased by running a two stage membrane system as shown in Comparable Examples 4 and 5.
  • both stages applied the commercially available membranes with the performance data the same as those in Comparable Example 1.
  • the cross-linked PBO(BTDA-APAF- 450C) polymer membrane was used for both first stage and second stage. The first stage was operated at elevated temperature to eliminate the MemGuardTM system. The second stage was operated at lower temperature to increase the selectivity.
  • the natural gas feed in Comparable Examples 3 and 4 had been changed to 45% CO2 (more meaningful for a two-stage system), and the product specification for CO2 in these two examples were assumed at 8%.
  • Table 7 shows the results of the simulation for Comparable Examples 4 and 5.
  • Comparable Example 4 and Comparable Example 5 have very similar hydrocarbon recovery. Due to the high temperature operation for the first stage membrane, Comparable Example 5 does not require a pretreatment such as a MemGuardTM system, which is 10 to 40% of the total cost of Comparable Example 4. At the same time, the first stage membrane area is reduced by 79.5% and the second stage membrane area is reduced by 59.2% from Comparable Example 4 to Comparable Example 5. It can be expected that the Comparable Example 5 will have a big capital (>50%) and footprint (>50%) saving compared to Comparable Example 4. The only drawback is that the compressor will be slightly bigger. Table 7 shows a 7.5% horse power increase from Comparable Example 4 to Comparable Example 5.

Abstract

La présente invention concerne des membranes polymères de polybenzoxazole et de polybenzothiazole réticulés à haut rendement, et des méthodes de production et d'utilisation de ces membranes. Les membranes polymères de polybenzoxazole et de polybenzothiazole réticulés sont préparées: 1) d'abord par synthèse de polymères polyimide comprenant des groupes fonctionnels pendants (p. ex. -OH ou SH) ortho à l'azote d'imide hétérocyclique et des groupes fonctionnels réticulables présents dans le squelette polymère; 2) par fabrication de membranes polyimide à partir de ces polymères; 3) par conversion des membranes polyimide en membranes de polybenzoxazole ou de polybenzothiazole par chauffage dans une atmosphère inerte, telle que l'azote ou sous vide; et 4) enfin par conversion des membranes en membranes de polybenzoxazole ou de polybenzothiazole réticulés à haut rendement par un traitement de réticulation, de préférence aux rayons ultraviolets. Les membranes peuvent être fabriquées en une quelconque géométrie pratique. Les membranes polymères de polybenzoxazole et de polybenzothiazole réticulés à haut rendement de l'invention sont appropriées pour diverses séparations en phase liquide, gazeuse ou vapeur.
PCT/US2010/024855 2009-03-27 2010-02-22 Membranes polymères de polybenzoxazole et de polybenzothiazole réticulés à haut rendement WO2010110975A2 (fr)

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JP2012502061A JP5607721B2 (ja) 2009-03-27 2010-02-22 高性能架橋ポリベンゾオキサゾール及びポリベンゾチアゾールポリマー膜
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AU2010229241A AU2010229241B2 (en) 2009-03-27 2010-02-22 High performance cross-linked polybenzoxazole and polybenzothiazole polymer membranes
KR1020117024855A KR101392124B1 (ko) 2009-03-27 2010-02-22 고성능의 가교된 폴리벤족사졸 또는 폴리벤조티아졸 고분자 막
EP10756536.8A EP2411130A4 (fr) 2009-03-27 2010-02-22 Membranes polymères de polybenzoxazole et de polybenzothiazole réticulés à haut rendement
BRPI1013695A BRPI1013695A2 (pt) 2009-03-27 2010-02-22 método para preparar membranas poliméricas de polibenzoxazol e de polibenzotiazol reticuladas, e, processo para separar pelo menos um gás ou líquido de uma mistura de gases ou líquidos

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CN102560894A (zh) * 2011-11-17 2012-07-11 江西先材纳米纤维科技有限公司 聚苯并二噁唑纳米纤维非织造布的制备方法及其应用
CN102728237A (zh) * 2012-06-20 2012-10-17 中国科学技术大学 均相阴离子交换膜及其制备方法
JP2013053216A (ja) * 2011-09-02 2013-03-21 Daicel Corp 相分離構造体及び有機半導体
WO2012173776A3 (fr) * 2011-06-17 2013-05-23 Uop Llc Membrane de polyimide pour la séparation de gaz
WO2013111732A1 (fr) * 2012-01-24 2013-08-01 公益財団法人名古屋産業科学研究所 Membrane de séparation de gaz
WO2015047711A1 (fr) * 2013-09-27 2015-04-02 Uop Llc Membranes polybenzoxazole à partir de membranes polyimide aromatiques autoréticulables
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US9440197B2 (en) 2013-07-01 2016-09-13 ICUF-HYU (Industry-University Cooperation Foundation Hanyang University) Crosslinked thermally rearranged poly(benzoxazole-co-imide), gas separation membranes comprising the same and preparation method thereof
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BRPI1013695A2 (pt) 2016-04-26
KR20110130503A (ko) 2011-12-05
AU2010229241A1 (en) 2011-10-06
EP2411130A2 (fr) 2012-02-01
CN102448593A (zh) 2012-05-09
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