WO2023004020A1 - Processus de fabrication d'une membrane cms à écoulement de surface/ à sélectivité inverse pour la séparation de gaz - Google Patents

Processus de fabrication d'une membrane cms à écoulement de surface/ à sélectivité inverse pour la séparation de gaz Download PDF

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WO2023004020A1
WO2023004020A1 PCT/US2022/037838 US2022037838W WO2023004020A1 WO 2023004020 A1 WO2023004020 A1 WO 2023004020A1 US 2022037838 W US2022037838 W US 2022037838W WO 2023004020 A1 WO2023004020 A1 WO 2023004020A1
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membrane
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PCT/US2022/037838
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Abhishek Roy
Thomas C. FITZGIBBONS
Li Tang
Surendar R. Venna
Derrick W. Flick
Nikki J. MONTANEZ
Hali J. MCCURRY
James B. HEARD
Barry B. Fish
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Dow Global Technologies Llc
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    • 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
    • B01D67/0039—Inorganic membrane manufacture
    • B01D67/0067—Inorganic membrane manufacture by carbonisation or pyrolysis
    • 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
    • B01D71/02—Inorganic material
    • B01D71/021—Carbon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2256/00—Main component in the product gas stream after treatment
    • B01D2256/24—Hydrocarbons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/28—Pore treatments
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/22—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion
    • B01D53/228—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion characterised by specific membranes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/40—Capture or disposal of greenhouse gases of CO2

Definitions

  • Embodiments of the present disclosure generally relate to hollow fiber carbon molecular sieve (CMS) membranes for use in gas separation, and in particular, a method for producing hollow fiber CMS membranes with reverse selectivity.
  • CMS carbon molecular sieve
  • Membranes are widely used for the separation of gases and liquids, including for example, separating acid gases, such as CO2 and H2S from natural gas, and the removal of O2 from air. Gas transport through such membranes is commonly modeled by the sorption-diffusion mechanism.
  • acid gases such as CO2 and H2S from natural gas
  • O2 oxygen species
  • Polymeric membranes are well studied and widely available for gaseous separations due to easy processability and low cost. CMS membranes, however, have been shown to have attractive separation performance properties exceeding that of polymeric membranes.
  • CMS membranes are typically produced through thermal pyrolysis of polymer precursors.
  • defect-free hollow fiber CMS membranes can be produced by pyrolyzing cellulose hollow fibers.
  • many other polymers have been used to produce CMS membranes in fiber and dense film form, among which polyimides have been favored. Polyimides have a high glass transition temperature, are easy to process, and perform better than most other polymeric membranes, even prior to pyrolysis.
  • CMS membrane separation properties are primarily affected by the following factors: (1) pyrolysis precursor, (2) pyrolysis temperature, (3) thermal soak time, and (4) pyrolysis atmosphere. For example, increases in both temperature and thermal soak time have been shown to increase the selectivity but decrease permeance for CO2/CH4 separation.
  • a precursor polymer with a rigid, tightly packed structure tends to lead to a CMS membrane having higher selectivity compared with less rigid precursor polymers.
  • the impact of pyrolysis atmosphere gas has not been studied in great detail, nor have the long term use of the CMS membranes and the stability of the membranes with respect to maintaining the permeance and selectivity for particular gas molecules of interest.
  • CMS membranes may find utility in olefin-paraffin separation.
  • olefin-paraffin separations it is necessary to separate olefins from paraffins and lighter gases, such as Eh, CO2, and CH4.
  • Eh, CO2, and CH4 lighter gases
  • CMS membrane includes heating a polymeric precursor to a pyrolysis temperature that is greater than or equal to 500 °C and less than or equal to 1200 °C; pyrolyzing the polymeric precursor at the pyrolysis temperature, thereby forming a pyrolyzed polymeric membrane; exposing the pyrolyzed polymeric membrane to an atmosphere comprising greater than or equal to 50 ppm oxidant; and cooling the pyrolyzed polymeric membrane to a cooling temperature that is less than or equal to 50 °C. The exposing and the cooling are performed sequentially or simultaneously, thereby forming the hollow fiber CMS membrane.
  • FIGURE (FIG.) 1 provides a schematic of a system for pyrolysis and oxidation of a hollow fiber CMS membrane in accordance with embodiments described herein;
  • FIG. 2 is a chart of temperature on the x-axis and simulated O2 concentration on the y-axis for use with embodiments described herein.
  • a method of making a hollow fiber CMS membrane includes first heating a polymeric precursor to a pyrolysis temperature.
  • the polymeric precursor may be any useful polymer for making hollow fiber CMS membranes, such as polyimides for example.
  • the polyimide may be a conventional or fluorinated polyimide.
  • the polymeric precursor may comprise a polymer comprising monomers Ac, By, and Cz, where X, Y, and Z are the mole fraction of each of A, B, and C, respectively, present in the polymer.
  • X + Y + Z l.
  • X + Y + Z ⁇ 1 , and other monomers are present in the polymer.
  • Each of A, B, and C is a monomer selected from the group consisting of 2, 4,6- trimethyl- 1,3 -phenylene diamine (DAM); oxydianaline (ODA); dimethyl-3, 7-diaminodiphenyl- thiophene-5,5'-dioxide (DDBT); 3,5-diaminobenzoic acid (DABA); 2.3,5,6-tetramethyl-l,4- phenylene diamine (durene); meta-phenylenediamine (m-PDA); 2,4-diaminotolune (2,4-DAT); tetramethylmethylenedianaline (TMMDA); 4,4'-diamino-2,2'-biphenyl disulfonic acid (BDSA); 5,5'-[2,2,2-trifluoro-l-(trifluoromethyl)ethylidene]-l,3-isobenzofurandion (6FDA); 3,3 ',4,4
  • polyimides may contain at least two different moieties selected from DAM; ODA; DDBT; DAB A; durene; m-PDA; 2,4-DAT; TMMDA; BDSA; 6FDA; BPDA; PMDA; NTDA; and BTDA.
  • A is a monomer selected from the group consisting of 6FDA,
  • the polyimide may be MATRIMIDTM 5218 (Huntsman Advanced Materials), a commercially available polyimide in which A is BTDA; B is DAPI; and Z is 0.
  • the polyimide may comprise, consist essentially of, or consist of
  • 6FDA/BPDA-DAM as shown in formula (1), which may be synthesized via thermal or chemical processes from a combination of three commercially available monomers: DAM; 6FDA, and BPDA.
  • X + Y may be from 0.1 to 0.9, and Z may be from 0.1 to 0.9.
  • X + Y may be from 0.1 to 1, and Z may be from 0 to 0.9.
  • X may be 0 and Y + Z may be 1.
  • X and Z may be from 0.25, 0.3, or 0.4 to 0.9, 0.8, or 0.75.
  • X + Y is 0.5 and Z is 0.5.
  • Formula (2) below shows a representative structure for 6FDA/BPDA-DAM, with a potential for adjusting the ratio between X and Z to tune polymer properties.
  • a 1 : 1 ratio of X to Z may also abbreviated as 6FDA/BPDA(1:1)-DAM.
  • the polyimide may be formed by the reaction of a diamine with a dianhydride.
  • at least one of A, B, and C is a diamine, and at least one other of A, B, and C, is a dianhydride.
  • the total diamine and the total dianhydride may be in a molar ratio of diamine to dianhydride of greater than or equal to 49:51 to 51:49. In embodiments, the diamine and dianhydride may be in a molar ratio of diamine to dianhydride of about 50:50.
  • more than one dianhydride may be used with one diamine.
  • the molar ratio of dianhydride 1 to dianhydride 2 may be greater than or equal to 20:80 and less than or equal to 80:20.
  • this molar ratio may be greater than or equal to 25:75 and less than or equal to 75:25, greater than or equal to 30:70 and less than or equal to 70:30, greater than or equal to 35:65 and less than or equal to 65:35, greater than or equal to 40:60 and less than or equal to 60:40, or even greater than or equal to 45:55 and less than or equal to 55:45.
  • the molar ratio of dianhydride 1 to dianhydride 2 may be about 50:50. In embodiments, one dianhydride may be used with more than one diamines. In such embodiments using two diamines, diamine 1 and diamine 2, the molar ratio of diamine 1 to diamine 2 may be greater than or equal to 20:80 and less than or equal to 80:20.
  • this molar ratio may be greater than or equal to 25:75 and less than or equal to 75:25, greater than or equal to 30:70 and less than or equal to 70:30, greater than or equal to 35:65 and less than or equal to 65:35, greater than or equal to 40:60 and less than or equal to 60:40, or even greater than or equal to 45:55 and less than or equal to 55:45.
  • the molar ratio of diamine 1 to diamine 2 may be about 50:50.
  • the polymeric precursor membranes as produced, but not pyrolyzed are substantially defect-free.
  • “Defect-free” means that selectivity of a gas pair through a hollow fiber membrane is at least 90 percent of the selectivity for the same gas pair through a dense film prepared from the same composition as that used to make the polymeric precur membrane.
  • a 6FDA/BPDA(1:1)-DAM polymer has an O2/N2 selectivity (also known as “dense film selectivity”) of 4.1.
  • the precursor polymers may be formed into hollow fibers or films.
  • coextrusion procedures including a dry -jet wet spinning process (in which an air gap exists between the tip of the spinneret and the coagulation or quench bath) or a wet spinning process (with zero air-gap distance) may be used to make hollow fibers.
  • the hollow fiber CMS membrane may be asymmetric.
  • the term “asymmetric” referes to a property of the hollow fiber CMS membrane in which the hollow fiber CMS membrane has at least one relatively more dense layer and at least one relatively less dense layer.
  • one layer of the hollow fiber CMS membrane may be greater than or equal to 1 pm and less than or equal to 10 pm and be more dense than a second layer.
  • the second layer may be thicker than the first layer, such as greater than or equal to 20 pm and less than or equal to 200 pm.
  • the asymmetric membrane may be an entity composed of an extremely thin, dense skin over a thick porous substructure, which may be of the same or different material as that of the dense skin layer.
  • the asymmetric membrane may be fabricated in a single step by phase inversion, or the thin layer may be coated on the pre-prepared porous support using a dip coating method. These layers in the asymmetric membranes may be created physically by coating or created by chemical modification.
  • the asymmetric membrane may be in the form of a hollow fiber configuration or a film configuration.
  • the asymmetric membrane may contain a third layer of the same or different material as needed to enhance the membrane performance.
  • any suitable supporting means for holding the hollow fiber CMS membranes may be used during the pyrolysis including sandwiching between two metallic wire meshes or using a stainless steel mesh plate in combination with stainless steel wires and as described by US Pat. No. 8,709,133 at col. 6, line 58 to col. 7, line 4, which is incorporated by reference.
  • Precursor polymers may be pyrolyzed to form the hollow fiber CMS membranes
  • the pyrolysis temperature may be greater than or equal to 500 °C and less than or equal to 1200 °C.
  • the pyrolysis temperature may be adjusted in combination with the pyrolysis atmosphere to tune the performance properties of the resulting hollow fiber CMS membrane.
  • the pyrolysis temperature may be 1000 °C or more.
  • the pyrolysis temperature may be greater than or equal to 900 °C and less than or equal to 1000 °C.
  • the pyrolysis temperature may be greater than or equal to 550 °C and less than or equal to 1200 °C, greater than or equal to 600 °C and less than or equal to 1200 °C, greater than or equal to 650 °C and less than or equal to 1200 °C, greater than or equal to 700 °C and less than or equal to 1200 °C, greater than or equal to 750 °C and less than or equal to 1200 °C, greater than or equal to 800 °C and less than or equal to 1200 °C, greater than or equal to 850 °C and less than or equal to 1200 °C, greater than or equal to 900 °C and less than or equal to 1200 °C, greater than or equal to 950 °C and less than or equal to 1200 °C, greater than or equal to 1000 °C and less than or equal to 1
  • the pyrolysis soak time (i.e., the duration of time at the pyrolysis temperature) may vary (and may include no soak time) but may be, for example, greater than or equal to 1 hour and less than or equal to 10 hours, greater than or equal to 2 hours and less than or equal to 8 hours, greater than or equal to 4 hours and less than or equal to 6 hours.
  • An exemplary heating protocol may include: (1) starting at a first set point of about 50 °C; (2) heating to a second set point of about 250 °C at a rate of about 13.3 °C per minute; (3) heating to a third set point of about 535 °C at a rate of about 3.85 °C per minute; (4) heating to a fourth set point of about 550 °C to 700 °C at a rate of about 0.25 °C per minute. The fourth set point may then be maintained for the determined soak time.
  • the precursor polymers may be pyrolyzed under various inert gas purge or vacuum conditions.
  • the precursor polymers may be pyrolyzed under vacuum at low pressures (e.g. less than or equal to 0.1 millibar).
  • the pyrolysis utilizes a controlled inert purge gas atmosphere.
  • an inert gas such as argon is used as the purge gas atmosphere.
  • suitable inert gases include, but are not limited to, nitrogen, helium, or any combination thereof.
  • the inert gas containing a specific concentration of oxidant may be introduced into the pyrolysis chamber.
  • the oxidant may be introduced in the presence or absence of the inert gas.
  • the amount of oxidant in the purge atmosphere may be greater than 0 ppm and less than or equal to 250 ppm.
  • the amount of oxidant may be greater than 0 ppm and less than or equal to 240 ppm, greater than 0 ppm and less than or equal to 230 ppm, greater than 0 ppm and less than or equal to 220 ppm, greater than 0 ppm and less than or equal to 210 ppm, greater than 0 ppm and less than or equal to 200 ppm, greater than 0 ppm and less than or equal to 190 ppm, greater than 0 ppm and less than or equal to 180 ppm, greater than 0 ppm and less than or equal to 170 ppm, greater than 0 ppm and less than or equal to 160 ppm, greater than 0 ppm and less than or equal to 150 ppm, greater than 0 ppm and less than or equal to 140 ppm, greater than 0 ppm and less than or equal to 130 ppm, greater than 0 ppm and less than or equal to 120 ppm, greater than 0 pp
  • the oxidant added to the purge gas atmosphere used in the pyrolysis may be selected from the group consisting of gaseous oxygen, CO2, CO, nitrogen oxide, ozone, hydrogen peroxide, steam, and air.
  • the hollow fiber CMS membrane may be oxidized by exposing it to an atmosphere containing greater than or equal to 50 ppm and less than or equal to 40,000 ppm oxidant in the purge gas or another carrier gas.
  • the concentration of oxidant in the purge gas or another carrier gas is greater than or equal to 1000 ppm and less than or equal to 40,000 ppm, greater than or equal to 2000 ppm and less than or equal to 40,000 ppm, greater than or equal to 3000 ppm and less than or equal to 40,000 ppm, greater than or equal to 4000 ppm and less than or equal to 40,000 ppm, greater than or equal to 5000 ppm and less than or equal to 40,000 ppm, greater than or equal to 6000 ppm and less than or equal to 40,000 ppm, greater than or equal to 7000 ppm and less than or equal to 40,000 ppm, greater than or equal to 8000 ppm and less than or equal to 40,000 ppm, greater than or equal to 9000 ppm and less than or equal to 40,000 ppm, greater than or equal to 10,000 ppm and less than or equal to 40,000 ppm, greater than or equal to 11,000 ppm and less than or equal to 40,000 ppm
  • the hollow fiber CMS membrane may be exposed to an atmosphere containing greater than or equal to 500 ppm oxidant in the carrier gas.
  • the carrier gas is the same as the purge gas of the pyrolysis. In other embodiments, the carrier gas is not the same as the purge gas but may also be selected from inert gases such as argon, nitrogen, helium, or any combination thereof.
  • the flow of purge gas over the hollow fiber CMS membrane may be decreased while the flow of the mixture of oxidant and carrier gas is increased.
  • the temperature at which the flow of the purge gas stops completely and the flow of the mixture of oxidant and carrier gas is at its maximum is referred to throughout as the “oxidant exposure temperature” or the “air exposure temperature” when the oxidant is air.
  • the oxidant exposure temperature may be greater than or equal to 300 °C and less than or equal to 700 °C.
  • the oxidant exposure temperature may be greater than or equal to 300 °C and less than or equal to 650°C, greater than or equal to 300 °C and less than or equal to 600 °C, greater than or equal to 300 °C and less than or equal to 550 °C, greater than or equal to 300 °C and less than or equal to 500 °C, greater than or equal to 300 °C and less than or equal to 450 °C, greater than or equal to 300 °C and less than or equal to 400 °C, greater than or equal to 350 °C and less than or equal to 700 °C, greater than or equal to 400 °C and less than or equal to 700 °C, greater than or equal to 450 °C and less than or equal to 700 °C, greater than or equal to 500 °C and less than or equal to 700 °C, greater than or equal to 550 °C and less than or equal to 700 °C, or even greater than or equal to 600 °C and less than or equal to 700 °C,
  • the hollow fiber CMS membrane may undergo oxidation for greater than or equal to 0.5 hours and less than or equal to 24 hours, greater than or equal to 1 hours and less than or equal to 24 hours, greater than or equal to 1.5 hours and less than or equal to 24 hours, greater than or equal to 2.5 hours and less than or equal to 24 hours, greater than or equal to 3.5 hours and less than or equal to 24 hours, greater than or equal to 4.5 hours and less than or equal to 24 hours, greater than or equal to 5.5 hours and less than or equal to 24 hours, greater than or equal to
  • oxidation of the hollow fiber CMS membrane enhances its ability to separate components of a mixture stream. This may be because the oxidation helps to create a porous suface and increases polarity of that surface. As a result, transport of larger gas molecules may be enhanced due to increased solubility and a pore blocking transport mechanism.
  • the hollow fiber CMS membrane that has formed is cooled to temperature near room temperature, such as less than or equal to 50 °C.
  • the cooling may be at any useful rate, such as passively cooling (e.g., turning off the power to the furnace and allowing to cool naturally).
  • passively cooling e.g., turning off the power to the furnace and allowing to cool naturally.
  • it may be desirable to more rapidly cool such as by using known techniques to realize faster cooling.
  • Known techniques include, but are not limited to, cooling fans or employment of water cooled jackets, purging with a gas having a lower temperature than the hollow fiber CMS membrane, or opening the furnace to the surrounding environment.
  • FIG. 1 Flow control device 10 is first set to an “on” configuration, meaning that fluid is permitted to flow through conduit 12 from purge gas reservoir 14 to furnace 16, which contains the hollow fiber CMS membrane (not shown). During the pyrolysis step, most or even all of the fluid entering furnace 16 originates from purge gas reservoir 14.
  • flow control device 10 When the temperature within furnace 16 decreases to the desired oxidation initiation temperature, such as greater than or equal to 100 °C to less than or equal to 600 °C, flow control device 10 reduces flow of the fluid from the purge gas reservoir 14 and flow control device 18 increases flow of the fluid from the oxidant reservoir 20 into furnace 16 via conduit 22.
  • conduit 12 and conduit 22 both feed into inlet 24.
  • the oxidant reservoir 20 may contain a premixed volume of oxidant and carrier gas, such as air (oxygen gas as oxidant and nitrogen gas as carrier) or a mixture of oxygen gas (oxidant) and argon (carrier).
  • gases from the furnace 16 may pass through outlet 26 and eventually be vented via conduit 28. Conveniently, these gases may be analyzed using oxygen sensor 30 to allow proper control of the process, including gas composition during the pyrolysis.
  • conduit includes, but is not limited to, casings, liners, pipes, tubes, coiled tubing, and mechanical structures with interior voids.
  • reservoir includes any container of any size capable of containing a fluid, whether in liquid or gaseous form.
  • exemplary reservoirs include, but are not limited to, gas cylinders, holding tanks, bladders, inflatable membranes (such as a balloon), drums, and bottles.
  • flow control device includes, but is not limited to, a ball valve, a butterfly valve, a choke valve, a diaphragm valve, a gate valve, a globe valve, a knife valve, a needle valve, a pinch valve, a piston valve, a plug valve, a solenoid valve, and a spool valve.
  • a method of making a hollow fiber carbon molecular sieve (CMS) membrane includes heating a polymeric precursor to a pyrolysis temperature that is greater than or equal to 500 °C and less than or equal to 1200 °C; pyrolyzing the polymeric precursor at the pyrolysis temperature, thereby forming a pyrolyzed polymeric membrane; exposing the pyrolyzed polymeric membrane to an atmosphere comprising greater than or equal to 50 ppm oxidant; and cooling the pyrolyzed polymeric membrane to a cooling temperature that is less than or equal to 50 °C. The exposing and the cooling are performed sequentially or simultaneously, thereby forming the hollow fiber CMS membrane.
  • the hollow fiber CMS membrane is asymmetric.
  • the pyrolyzing is conducted for greater than or equal to 1 hour and less than or equal to 24 hours.
  • the cooling temperature is greater than or equal to 20 °C and less than or equal to 30 °C.
  • the exposure temperature is greater than or equal to 500 °C.
  • the atmosphere comprises greater than or equal to 500 ppm oxidant.
  • the pyrolysis temperature is greater than or equal to 900 °C and less than or equal to 1200 °C.
  • the heating is conducted in an atmosphere comprising greater than 0 ppm and less than or equal to 150 ppm oxidant.
  • the polymeric precursor comprises a polyimide.
  • the polymeric precursor comprises a polymer comprising one or more monomers selected from the group consisting of 2, 4, 6-trimethyl- 1, 3 -phenylene diamine (DAM); oxydianaline (ODA); dimethyl-3, 7-diaminodiphenyl-thiophene-5,5'-dioxide (DDBT); 3,5-diaminobenzoic acid (DABA); 2.3,5,6-tetramethyl-l,4-phenylene diamine (durene); meta-phenylenediamine (m- PDA); 2,4-diaminotolune (2,4-DAT); tetramethylmethylenedianaline (TMMDA); 4,4'-diamino- 2,2'-biphenyl disulfonic acid (BDSA); 5,5'-[2,2,2-trifluoro-l-(trifluoromethyl)ethylidene]-l,3-
  • DAM 2, 4, 6-trimethyl- 1, 3 -phenylene diamine
  • the polymeric precursor comprises a polymer comprising monomers Ac, Bg, and Cz, where X, Y, and Z are a mole fraction of each of A, B, and C, respectively, present in the polymer.
  • the sum of X, Y, and Z is less than or equal to 1.
  • Each of A, B, and C is a monomer selected from the group consisting of 2, 4, 6-trimethyl- 1,3 -phenylene diamine (DAM); oxydianaline (ODA); dimethyl-3, 7-diaminodiphenyl-thiophene-5,5'-dioxide (DDBT); 3,5-diaminobenzoic acid (DABA); 2.3,5,6-tetramethyl-l,4-phenylene diamine (durene); meta-phenylenediamine (m- PDA); 2,4-diaminotolune (2,4-DAT); tetramethylmethylenedianaline (TMMDA); 4,4'-dNamino- 2,2'-biphenyl disulfonic acid (BDSA); S ⁇ -P ⁇ -trifluoro-l ⁇ trifluoromethy ⁇ ethyl-ideneJ-l ⁇ - isobenzofurandion (6FDA); 3,3',4,4'-biphenyl
  • A is a monomer selected from the group consisting of 6FDA, ODPA, and BTDA; B is DAM; and C is a monomer selected from the group consisting of BPDA and PMDA.
  • A is 6FDA; B is DAM; and B is DAM; and
  • the oxidant is selected from the group consisting of gaseous oxygen, CO2, CO, nitrogen oxide, ozone, hydrogen peroxide, steam, and air.
  • FIG. 2 provides a chart of temperature on the x-axis and simulated O2 concentration on the y-axis. As is evident from the chart, the concentration of O2 increases linearly as the temperature decreases. Further, this relationship may be used to determine an expected concentration of O2 when performing a pyrolysis and oxidation.
  • CMS membranes were prepared using 6FDA:BPDA-DAM polymer acquired from
  • the homogeneous dope was loaded into a 500 milliliter (mL) syringe pump and allowed to degas overnight by heating the pump to a set point temperature from 50 °C to 60 °C using a heating tape.
  • Bore fluid (85 wt% NMP and 15 wt% water, based on total bore fluid weight) was loaded into a separate 100 mL syringe pump and then the dope and bore fluid were co-extruded through a spinneret operating at a flow rate of 180 milliliters per hour (mL/hr) for the dope and 60 mh/hr bore fluid, filtering both the bore fluid and the dope in line between delivery pumps and the spinneret using 40 pm and 2 pm metal filters.
  • the temperature was controlled using thermocouples and heating tape placed on the spinneret, dope filters, and dope pump at a set point temperature of 70 °C.
  • the nascent fibers that were formed by the spinneret were quenched in a water bath (50 °C), and the fibers were allowed to phase separate.
  • the fibers were collected using a 0.32 meter (m) diameter polyethylene drum passing over TEFLON guides and operating at a take-up rate of 30 meters per minute (m/min).
  • the fibers were cut from the drum and rinsed at least four times in separate water baths over a span of 48 hours.
  • the rinsed fibers underwent solvent exchange three times with methanol for 20 minutes and then hexane for 20 minutes before recovering the fibers and drying them under vacuum at a set point temperature of 110 °C for one hour or drying under vacuum at 75 °C for 3 hours.
  • the precursor fibers were pyrolized in a pyrolysis chamber having an oxygen content at room temperature less than 10 ppm. Argon was used as the inert purge gas. After the pyrolysis, the pyrolysis chamber was allowed to cool, and the gas line to suppy purging argon gas was discontinued at various temperatures (i.e., 375 °C, 485 °C, and 575 °C) to enable the air flow into the furnace from the exhaust line at the outlet of the furnace. After the membranes were pyrolyzed and cooled, a single fiber module was fabricated and tested for CO2/N2 and C2H4/C2H6 gas pair permeance. [0066] Example 3 - Gas Separation
  • a Maxum II process GC (Siemens, Munich, Germany) is used to measure the composition of the permeate & sweep mixture, and a Mesalabs Bios Drycal flowmeter (Mesa Labs, Inc., Butler, NJ) is used for the permeate flow rate measurement.
  • the volumetric flow rate from the Bios DryCal flowmeter and the composition from the GC were used to analyze the permeance and selectivity of the fibers in the test gas system.
  • the gas permeation properties of a hollow fiber CMS membrane are determined by gas permeation experiments. Two intrinsic properties have utility in evaluating separation performance of a membrane material: its “permeability,” a measure of the hollow fiber CMS membrane’s intrinsic productivity; and its “selectivity,” a measure of the hollow fiber CMS membrane’s separation efficiency.
  • One typically determines “permeability” in Barrer (1 Barrer 10 10 [cm 3 (STP) cm]/[cm 2 s cmHg], calculated as the flux (nQ divided by the partial pressure difference between the hollow fiber CMS membrane upstream and downstream (Dr, ). and multiplied by the thickness of the hollow fiber CMS membrane (Z).
  • GPU Gas Permeation Units
  • “selectivity” is defined herein as the ability of one gas’s permeability through the hollow fiber CMS membrane or permeance relative to the same property of another gas. It is measured as a unitless ratio.
  • Table 1 provides gas separation properties of control and air exposed oxidized samples made in accordance with the subject matter described herein. Samples 1 and 7 were not oxidized and are thus comparative examples. Samples 2-6 were exposed to air at the initial air exposure temperature provided.
  • Samples 5 and 6 highlight the impact of pyrolysis temperature. Permeability of

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

L'invention concerne un procédé de fabrication d'un tamis moléculaire en carbone à fibres creuses (CMS) membrane consiste à chauffer un précurseur polymère à une température de pyrolyse qui est supérieure ou égale à 500 °C et inférieure ou égale à 1200 °C ; à pyrolyser le précurseur polymère à la température de pyrolyse, ce qui permet de former une membrane polymère pyrolysée ; à exposer la membrane polymère pyrolysée à une atmosphère comprenant un oxydant supérieur ou égal à 50 ppm ; et à refroidir la membrane polymère pyrolysée jusqu'à une température de refroidissement qui est inférieure ou égale à 50 °C. L'exposition et le refroidissement sont réalisés de manière séquentielle ou simultanée, formant ainsi la membrane CMS à fibres creuses.
PCT/US2022/037838 2021-07-21 2022-07-21 Processus de fabrication d'une membrane cms à écoulement de surface/ à sélectivité inverse pour la séparation de gaz WO2023004020A1 (fr)

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WO2024091872A1 (fr) * 2022-10-24 2024-05-02 Dow Global Technologies Llc Fibres de carbone creuses asymétriques comprenant des couches de surface oxydées
WO2024155660A1 (fr) * 2023-01-20 2024-07-25 Dow Global Technologies Llc Membranes à base de carbone sélectives inverses et leurs procédés de fabrication
WO2024173056A1 (fr) * 2023-02-16 2024-08-22 Dow Global Technologies Llc Membranes de tamis moléculaire carboné autosupportées et leurs procédés d'utilisation

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024091872A1 (fr) * 2022-10-24 2024-05-02 Dow Global Technologies Llc Fibres de carbone creuses asymétriques comprenant des couches de surface oxydées
WO2024155660A1 (fr) * 2023-01-20 2024-07-25 Dow Global Technologies Llc Membranes à base de carbone sélectives inverses et leurs procédés de fabrication
WO2024173056A1 (fr) * 2023-02-16 2024-08-22 Dow Global Technologies Llc Membranes de tamis moléculaire carboné autosupportées et leurs procédés d'utilisation

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