METAL-ORGANIC FRAMEWORK MATERIAL SEPARATION MEMBRANE, PREPARATION METHOD THEREFOR, AND USE THEREOF

Abstract

A metal-organic framework material separation membrane and a preparation method for the metal-organic framework material separation membrane are provided. The metal-organic framework material separation membrane has a base membrane and a metal-organic framework material functional layer. The metal-organic framework material functional layer comprises has an inter-embedded polyhedron structure. The preparation metal-organic framework material separation membrane includes the steps of: (1) preparing a solution containing a first organic solvent, an organic ligand, a metal compound, and an auxiliary agent; (2) subjecting a base membrane to a pretreatment, involving introducing, on the surface of the base membrane, metal atoms from the metal compound of step (1); and (3) mixing the pretreated base membrane of step (2) with the solution of step (1) to obtain a first mixture, and then heating the first mixture for reaction, so as to prepare a metal-organic framework material separation membrane.

Claims

1. A metal-organic framework material separation membrane, comprising a base membrane and a metal-organic framework material functional layer which comprises a plurality of inter-embedded polyhedron structures; preferably, the polyhedron is composed of a plurality of crystal lattices, and among the inter-embedded polyhedron structures, two adjacent polyhedrons share crystal lattices and/or a distance between centers of the two adjacent polyhedrons is less than an average value L of lengths of the two adjacent polyhedrons, preferably less than 0.95 L, and more preferably is 0.2-0.9 L; preferably, at least 20% of the polyhedrons in the metal-organic framework material functional layer are inter-embedded, preferably at least 30%, preferably at least 40%, preferably at least 50%, preferably at least 60%, and preferably at least 80% of the polyhedrons are inter-embedded; preferably, the polyhedron includes hexahedron and/or octahedron, and preferably, a length of the polyhedron is 50-2000 nm; and preferably, the crystal lattice is composed of a metal atom and organic ligands; preferably, the metal atom is selected from zirconium atom, niobium atom, molybdenum atom or cobalt atom; and preferably, the organic ligand is selected from terephthalic acid and/or nitroterephthalic acid.

2. The separation membrane according to claim 1, characterized in that, a length of the hexahedron is 50-1000 nm, wherein the hexahedrons with a length of 400-600 nm account for 50-80%.

3. The separation membrane according to claim 1, characterized in that, a length of the octahedron is 200-2000 nm, wherein the octahedrons with a length of 800-1200 nm account for 60-80%.

4. The separation membrane according to claim 1, characterized in that, the metal-organic framework material functional layer has an average pore size of 0.1-2.0 nm, preferably 0.30-0.96 nm; and/or, the metal-organic framework material functional layer has a thickness of 200-5000 nm, preferably 1000-5000 nm.

5. The separation membrane according to claim 1, characterized in that, the base membrane is selected from one or more of polypropylene membrane, polyethylene membrane, polyvinyl chloride membrane or polytetrafluoroethylene membrane; and/or, the base membrane has a pore size of 10-10000 nm, preferably 50-5000 nm, more preferably 200-1000 nm.

6. The separation membrane according to claim 1, characterized in that, the separation membrane further comprises an organosilicon layer on the surface of the metal-organic framework material functional layer.

7. A preparation method for a metal-organic framework material separation membrane, comprising the following steps: (1) preparing a solution containing a first organic solvent, an organic ligand, a first metal compound, and an auxiliary agent selected from water or glacial acetic acid; (2) subjecting a base membrane to a pretreatment, involving introducing, on the surface of the base membrane, metal atoms of the first metal compound in step (1); (3) mixing the pretreated base membrane in step (2) with the solution in step (1) to obtain a first mixture, and heating the first mixture for reaction, so as to obtain the metal-organic framework material separation membrane, and (4) optionally, subjecting the separation membrane to a cleaning treatment.

8. The method according to claim 7, characterized in that, in step (1), a molar ratio of the first organic solvent, the organic ligand and the first metal compound is (10-1000):(1-100):(1-100), preferably (100-1000):(1-10):(1-10), more preferably (100-700):1:1, further preferably (400-600):1:1, and/or a molar ratio of the first organic solvent and the auxiliary agent water is 100:(0.001-0.05), and a molar ratio of the first organic solvent and the auxiliary agent glacial acetic acid is 100:(20-60); preferably, the first organic solvent is selected from one or more of N-methylpyrrolidone, N,N-dimethylformamide and dimethylacetamide, preferably, the organic ligand is selected from terephthalic acid and/or nitroterephthalic acid; and preferably, the first metal compound is selected from one or more of zirconium compound, niobium compound, molybdenum compound and cobalt compound, preferably zirconium tetrachloride.

9. The method according to claim 7, characterized in that, the base membrane is selected from one or more of polypropylene membrane, polyethylene membrane, polyvinyl chloride membrane or polytetrafluoroethylene membrane; and/or, the base membrane has a pore size of 10-10000 nm, preferably 50-5000 nm, more preferably 200-1000 nm.

10. The method according to claim 7, characterized in that, the step (2) comprises the following steps: (2A-1) preparing a solution containing polyacrylic acid, polyvinyl alcohol and a second metal compound, and (2A-2) coating the solution of step (2A-1) onto the base membrane; preferably, the polyacrylic acid includes polyacrylic acid and partially hydrolyzed polyacrylic acid, and/or a mass concentration of the polyacrylic acid and the polyvinyl alcohol in the solution is 500-2000 mg/L, and a molar ratio of a sum of polyacrylic acid and polyvinyl alcohol to the metal compound is 1-3:1; preferably, a metal atom in the second metal compound is the same as a metal atom in the first metal compound in step (1), and preferably, the second metal compound is selected from one or more of zirconium compound, niobium compound, molybdenum compound and cobalt compound, preferably zirconium tetrachloride; and preferably, in step (2A-2), a ratio of a surface area of the base membrane to a volume of the solution obtained in step (2A-1) is 0.1-10 m.sup.2/L, preferably 0.5-5 m.sup.2/L, more preferably 1-2 m.sup.2/L.

11. The method according to claim 7, characterized in that, the step (2) comprises the following steps: (2B-1) preparing a solution containing a metal complex represented by formula I and a second organic solvent, (2B-2) mix the base membrane with the solution of step (2B-1), and (2B-3) cleaning the mixed base membrane in step (2B-2) by using a third solvent; ##STR00011## in formula I, Q is selected from acylamino, carbonyl or C1-C6 alkylene; R.sub.1 is selected from hydrogen, C1-C6 alkyl, C1-C6 alkoxy or halogen; M.sub.1 is the same as a metal atom in the first metal compound in step (1), and preferably, M.sub.1 is selected from zirconium atom, niobium atom, molybdenum atom or cobalt atom; m is 5-20; and n is 1-10; preferably, the second organic solvent is selected from one or more of organic solvents capable of allowing the base membrane to swell, is preferably selected from one or more of C5-C10 aliphatic hydrocarbon, C1-C10 halogenated aliphatic hydrocarbon, C6-C20 aromatic hydrocarbon and C6-C20 halogenated aromatic hydrocarbon, and is more preferably selected from one or more of n-pentane, n-hexane, trichloromethane, carbon tetrachloride, benzene and toluene; and the third solvent is selected from one or more solvents capable of allowing the swollen base membrane to deswell, and is preferably selected from water; preferably, in the solution of step (2B-1), a mass concentration of the metal complex represented by formula I is 500-2000 mg/L; and preferably, in step (2B-2), a ratio of a surface area of the base membrane to a volume of the solution obtained in step (2B-1) is 0.1-10 m.sup.2/L, preferably 0.5-5 m.sup.2/L, more preferably 1-2 m.sup.2/L.

12. The method according to claim 7, characterized in that, the step (2) comprises the following steps: (2C-1) preparing a solution containing a metal complex represented by formula II, and (2C-2) mixing the base membrane with the solution of step (2C-1) to obtain a mixture, and subjecting the mixture to polymerization reaction under microwave radiation conditions; ##STR00012## in formula II, X is selected from acylamino, carbonyl or C1-C6 alkylene; R.sub.2, R.sub.3 and R.sub.4 are the same or different, each independently selected from hydrogen, C1-C6 alkyl, C1-C6 alkoxy or halogen; and M.sub.2 is the same as a metal atom in the first metal compound in step (1), and preferably, M.sub.2 is selected from zirconium atom, niobium atom, molybdenum atom or cobalt atom; preferably, the solution of the metal complex in step (2C-1) is an aqueous solution of the metal complex, and/or a mass concentration of the metal complex represented by formula II is 500-20000 mg/L; preferably, in step (2C-2), a ratio of a surface area of the base membrane to a volume of the solution obtained in step (2C-1) is 0.1-10 m.sup.2/L, preferably 0.5-5 m.sup.2/L, more preferably 1-2 m.sup.2/L; and preferably, in step (2C-2), the microwave radiation has a microwave intensity of 500-2000 W/cm.sup.2, and a frequency of 1000-200000 Hz.

13. The method according to claim 7, characterized in that, in step (3), a ratio of a surface area of the pretreated base membrane in step (2) to a volume of the solution obtained in step (1) is (0.01-100) m.sup.2/L.

14. The method according to claim 7, characterized in that, in the step (3), a reaction temperature is 50-300 C., a reaction pressure is MPa, and a reaction time is 1-100 h, preferably 10-72 h, more preferably 15-30 h.

15. The method according to claim 7, characterized in that, the method further comprises the following step: (5) subjecting the metal-organic frame material separation membrane obtained in step (3) or (4) to a repairing treatment for one or more time(s).

16. The method according to claim 7, characterized in that, the repairing treatment comprises the following steps: (A) mixing the metal-organic framework material separation membrane with a solution containing a first organic solvent, an organic ligand, a first metal compound and an auxiliary agent to obtain a second mixture, wherein the auxiliary agent is selected from water or glacial acetic acid; (B) heating the second mixture for reaction to obtain the metal-organic framework material separation membrane; and (C) optionally, subjecting the separation membrane to a cleaning treatment; preferably, in step (B), a reaction temperature is 50-300 C., a reaction pressure is 0.01-0.5 MPa, and a reaction time is 1-100 h, preferably 5-50 h, more preferably 10-20 h.

17. (canceled)

18. The method according to claim 16, characterized in that, the method further comprises the following steps: coating a silane coating liquid onto a surface of the metal-organic framework material separation membrane prepared in step (3) or (4) or (B) or (C), heating the metal-organic framework material separation membrane coated with the silane coating liquid to subject the silane coating liquid to crosslinking reaction, so as to obtain a metal-organic frame material separation membrane including an organosilicon layer; and preferably, a temperature of the crosslinking reaction is 50-300 C., and a time therefor is 0.1-20 h.

19. A metal-organic framework material separation membrane prepared by the method according to claim 7.

20. Use of the metal-organic framework material separation membrane according to claim 19 in organic separations.

21. Use of the metal-organic framework material separation membrane according to claim 1 in organic separations.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0158] FIG. 1 shows an electron micrograph of a surface of the MOFs organic gas separation membrane prepared in Example 1;

[0159] FIG. 2 shows an electron micrograph of a surface of the MOFs organic gas separation membrane prepared in Example 5;

[0160] FIG. 3 shows an electron micrograph of a surface of the MOFs organic gas separation membrane prepared in Example 9;

[0161] FIG. 4 shows an electron micrograph of a surface of the MOFs organic gas separation membrane prepared in Example 13;

[0162] FIG. 5 shows an electron micrograph of a surface of the MOFs organic gas separation membrane prepared in Example 21;

[0163] FIG. 6 is a photograph of a polyvinylidene fluoride (PVDF) substrate after being soaked in a precursor solution in comparative example 1;

[0164] FIG. 7 is a photograph of a polyvinylidene fluoride (PVDF) substrate after being soaked in the precursor solution in comparative example 2;

[0165] FIG. 8 shows an electron micrograph of a surface of the MOFs organic gas separation membrane prepared in comparative example 3;

[0166] FIG. 9 shows an electron micrograph of a surface of the MOFs organic gas separation membrane prepared in comparative example 4;

[0167] FIG. 10 shows a schematic view of a test device for membrane performance.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0168] The present invention will be further described by means of examples, but is not limited to these examples.

[0169] Unless otherwise specified, the raw materials used in the examples are commercially available, and the chemicals mentioned are public chemicals in the prior art.

[0170] (1) A structural formula of acrylic acid-N-tert-butyl acrylamide/zirconium complex in the examples is represented as follows:

##STR00009##

wherein, m=12, n=1;

[0171] Preparation method: 47 g of acrylic acid was taken and dissolved in 250 g of deionized water, and pH value was adjust to 7-9 with NaOH solution; and 50 g of deionized water was taken, to which 12 g of sodium dodecyl sulfate (SDS) and 8.9 g of nonylphenol polyoxyethylene ether (NP) were added, and 3 g of tert-butyl acrylamide monomer was added under continuous and uniform stirring to form a uniform and stable clear solution. After the obtained two kinds of solution were mixed, then were put into an adiabatic polymerization kettle; after nitrogen gas was filled for about 10 minutes to remove oxygen gas, a redox initiator (ammonium persulfate-sodium bisulfate (each is added as 1% aqueous solution obtained by dissolving 0.05 g of a solid pure product in deionized water)) was added; and after the resultant solution become thick, the gas filling was stopped to allow the reaction to proceed under spontaneous temperature rise. After 6-8 hours, the reaction was completed to obtain a hydrogel product, which was then cut into pieces, baked to dryness at 50 C., and powdered to obtain an acrylic acid-tert butyl acrylamide copolymer. The copolymer was dissolved in water at a certain concentration, and a zirconium acetate salt was added to obtain the above poly acrylic acid-tert butyl acrylamide-zirconium coordination copolymer.

[0172] (2) A structural formula of the acrylic acid-N-dipropylene enamine/zirconium complex in the examples is represented as follows:

##STR00010##

[0173] Preparation method: 120 g of acrylic acid was taken and dissolved in 80 g of deionized water, and pH value was adjust to 7-9 with NaOH solution; and 20 g of deionized water was taken, to which 6 g of methylene bisacrylamide was added to form a uniform and stable clear solution. 95 g of industrial 5 #white oil was taken, to which an appropriate amount of 7.65 g of Span80 and 10 g of Tween80 were added, and the resultant was stirred to form a stable and uniform solution. A first part of the obtained aqueous phase was mixed with the obtained oil phase, and emulsified with an emulsifying machine to form a stable reversed-phase emulsion, which was then put in a polymerization kettle and cooled. An ammonium persulfate initiator solution (0.05 g of ammonium persulfate was dissolved in deionized water, to obtain 1% aqueous solution) was firstly added. A sodium bisulfite solution (0.05 g pure solid was dissolved in deionized water to obtain 1% aqueous solution) and a second part of the methylene bisacrylamide solution was slowly added dropwise under uniform stirring and under the nitrogen gas filling for protection. The reaction was slightly exothermic. The stirring was continued for 2 hours after the dropwise addition was completed. Thereafter, an emulsion was taken out, into which isopropanol/acetone was poured to produce a white precipitate. After the precipitate was obtained by centrifugation, it was washed with ethanol, to obtain a copolymer of acrylic acid and methylene bisacrylamide. The copolymer was dissolved in water, to which zirconium acetate was added to form the above copolymer.

[0174] Test Method

[0175] The separation performance of the membrane was tested for a mixed gas of nitrogen gas/organic vapor by using an analytical method described in the literature (Study on separation of organic vapor/nitrogen system through composite hollow fiber membrane, He Chunhong, Tianjin University, 2005). A test device was shown in FIG. 10.

[0176] A typical structure of a gas separation membrane is formed by covering a very thin dense layer on a porous support. It is difficult to accurately measure a true thickness of the dense layer. Therefore, a permeability coefficient and an effective thickness of the membrane are usually used in combination. A ratio of the permeability coefficient and the effective thickness of the membrane is referred as a permeation rate, which is calculated by the following equation:

J.sub.i=(P/I).sub.i=Q.sub.i/(p.Math.A)(1-1)

[0177] In the above equation, J.sub.i is a permeation rate of gas component i, in mol/(m.sup.2.Math.s.Math.Pa); P is a permeability coefficient of gas component i, in mol.Math.m/(m.sup.2.Math.s.Math.Pa); 1 is an effective thickness of the membrane, in m; Q.sub.i is a molar flow of component i in permeation gas under standard conditions, in mol/s; P is an osmotic pressure difference, in Pa; and A is an area of the membrane, in m.sup.2.

[0178] A separation coefficient is calculated by the following equation:

.sub.N2 organic gas=J.sub.N2/J.sub.organic gas(1-2)

Example 1

[0179] (1) A solution required for the preparation of a MOFs membrane

[0180] N-methylpyrrolidone, terephthalic acid, zirconium tetrachloride and pure water were mixed in a molar ratio of 400:1:1:0.01 and fully stirred to obtain the solution required for the preparation of the MOFs membrane.

[0181] (2) Base membrane pretreatment

[0182] (a) Polyacrylic acid, partially hydrolyzed polyacrylic acid and polyvinyl alcohol with a mass concentration of 1000 mg/L and zirconium tetrachloride were mixed in a molar ratio of 2:1, and stirred for 1 h to obtain a solution after reaction;

[0183] (b) After a polypropylene hollow fiber base membrane with a pore size of 500 nm was washed with water and ethanol and dried, the solution prepared in step (a) was coated on a dried surface of the base membrane in a ratio of a surface area of the base membrane to the solution described in step (a) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was coated with 1 L of the prepared solution described in step (a)), and then dried to allow a certain amount of zirconium atoms to attach to the surface of the base membrane, so as to obtain a pretreated base membrane.

[0184] (3) The pretreated base membrane was immersed into the solution for the preparation of the MOFs in a ratio of a surface area of the pretreated base membrane to the solution described in step (1) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was put in 1 L of the solution for the preparation of the MOFs described in step (1)), to obtain a first mixture, which was then subjected to reaction for in-situ growth at 120 C. for 24 h under filling of nitrogen gas for protection, to obtain a separation membrane.

[0185] (4) The separation membrane prepared in step (3) was take out, and the unreacted monomers and the solvent on the membrane surface were cleaned away to obtain a MOFs organic gas separation membrane.

[0186] (5) The separation membrane in step (4) was cleaned to obtain a MOFs organic gas separation membrane.

[0187] An electron micrograph of the surface of the prepared membrane was shown in FIG. 1. It can be seen from FIG. 1 that a MOFs functional layer of the prepared membrane was composed of inter-embedded octahedron crystals, was spread on the surface of the base membrane, was dense and continuous, and had a high surface roughness; the base membrane was completely covered; and the functional layer had few defects.

[0188] The test data for the performance of the membrane were shown in Table 1, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 4.82810.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.30110.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 16.03.

Example 2

[0189] Example 2 only differs from Example 1 in that, in the base membrane pretreatment of step (2), the solution prepared in step (a) was coated on a dried surface of the base membrane in a ratio of a surface area of the base membrane to the solution described in step (a) being 0.1 m.sup.2/L (that is, the membrane with a surface area of 0.1 square meter was coated with 1 L of the prepared solution described in step (a)).

[0190] The test data for the performance of the membrane were shown in Table 1, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 2.0110.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.1810.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 11.17.

Example 3

[0191] Example 3 only differs from Example 1 in that, in the base membrane pretreatment of step (2), the solution prepared in step (a) was coated on a dried surface of the base membrane in a ratio of a surface area of the base membrane to the solution described in step (a) being 5 m.sup.2/L (that is, the membrane with a surface area of 5 square meter was coated with 1 L of the prepared solution described in step (a)).

[0192] The test data for the performance of the membrane were shown in Table 1, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 10.4110.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 1.20610.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 8.63.

Example 4

[0193] Example 4 only differs from Example 1 in that, in the base membrane pretreatment of step (2), the solution prepared in step (a) was coated on a dried surface of the base membrane in a ratio of a surface area of the base membrane to the solution described in step (a) being 10 m.sup.2/L (that is, the membrane with a surface area of 10 square meter was coated with 1 L of the prepared solution described in step (a)).

[0194] The test data for the performance of the membrane were shown in Table 1, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 17.73310.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 1.90910.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 9.29.

TABLE-US-00001 TABLE 1 The ratio of the surface area of the base membrane The flux of The flux of The separation to the solution nitrogen gas propylene coefficient described in step (a) 10.sup.6 mol/ 10.sup.6 mol/ for nitrogen m.sup.2/L (m.sup.2 .Math. s .Math. Pa) (m.sup.2 .Math. s .Math. Pa) gas/propylene Example 1 1 4.828 0.301 16.04 Example 2 0.1 2.01 0.18 11.17 Example 3 5 10.41 1.206 8.63 Example 4 10 17.733 1.909 9.29

Example 5

[0195] (1) A solution required for the preparation of a MOFs membrane

[0196] N-methylpyrrolidone, terephthalic acid, zirconium tetrachloride and pure water were mixed in a molar ratio of 400:1:1:0.01 and fully stirred to obtain the solution required for the preparation of the MOFs membrane.

[0197] (2) Base membrane pretreatment

[0198] (a) acrylic acid-N-tert-butyl acrylamide/zirconium complex was dissolved in n-hexane with a mass concentration of 1000 mg/L to obtain a uniform solution;

[0199] (b) After a polypropylene hollow fiber base membrane with a pore size of 500 nm was washed with water and ethanol and dried, the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was put in 1 L of the prepared solution described in step (a)) for 2 h, taken out and quickly transferred into deionized water for cleaning, and then taken out and dried to obtain a modified base membrane, in which partial acrylic acid-N-tert-butyl acrylamide/zirconium complex was inserted into a surface layer of the embedded base membrane structure, so as to introduce a certain amount of stable zirconium atoms into the base membrane.

[0200] (3) The pretreated base membrane was immersed into the solution for the preparation of the MOFs in a ratio of a surface area of the pretreated base membrane to the solution described in step (1) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was put in 1 L of the solution for the preparation of the MOFs described in step (1)), to obtain a first mixture, which was then subjected to reaction for in-situ growth at 200 C. for 24 h under filling of nitrogen gas for protection, to obtain a separation membrane.

[0201] (4) The separation membrane prepared in step (3) was take out, and the unreacted monomers and the solvent on the membrane surface were cleaned away to obtain a MOFs organic gas separation membrane.

[0202] (5) The separation membrane in step (4) was cleaned to obtain a MOFs organic gas separation membrane.

[0203] An electron micrograph of the surface of the prepared membrane was shown in FIG. 2.

[0204] The test data for the performance of the membrane were shown in Table 2, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 1.52110.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.08810.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 17.28.

Example 6

[0205] Example 6 only differs from Example 5 in that, in the base membrane pretreatment of step (2), the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 0.1 m.sup.2/L (that is, the membrane with a surface area of 0.1 square meter was put in 1 L of the prepared solution described in step (a)).

[0206] The test data for the performance of the membrane were shown in Table 2, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 1.0110.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.1210.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 8.42.

Example 7

[0207] Example 7 only differs from Example 5 in that, in the base membrane pretreatment of step (2), the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 5 m.sup.2/L (that is, the membrane with a surface area of 5 square meter was put in 1 L of the prepared solution described in step (a)).

[0208] The test data for the performance of the membrane were shown in Table 2, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 2.8910.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.18810.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 15.37.

Example 8

[0209] Example 8 only differs from Example 5 in that, in the base membrane pretreatment of step (2), the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 10 m.sup.2/L (that is, the membrane with a surface area of 10 square meter was put in 1 L of the prepared solution described in step (a)).

[0210] The test data for the performance of the membrane were shown in Table 2, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa may reach 3.5010.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.21510.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 16.28.

TABLE-US-00002 TABLE 2 The ratio of the surface area of the base membrane The flux of The flux of The separation to the solution nitrogen gas propylene coefficient described in step (a) 10.sup.6 mol/ 10.sup.6 mol/ for nitrogen m.sup.2/L (m.sup.2 .Math. s .Math. Pa) (m.sup.2 .Math. s .Math. Pa) gas/propylene Example 5 1 1.521 0.088 17.28 Example 6 0.1 1.01 0.12 8.42 Example 7 5 2.89 0.188 15.37 Example 8 10 3.50 0.215 16.28

Example 9

[0211] (1) A solution required for the preparation of a MOFs membrane

[0212] N-methylpyrrolidone, terephthalic acid, zirconium tetrachloride and pure water were mixed in a molar ratio of 100:1:1:0.001 and fully stirred to obtain the solution required for the preparation of the MOFs membrane.

[0213] (2) Base membrane pretreatment

[0214] (a) acrylic acid-N-tert-butyl acrylamide/zirconium complex was dissolved in a solution, and then dissolved in water with a mass concentration of 1000 mg/L to obtain a grafting polymerization solution;

[0215] (b) After a polypropylene hollow fiber base membrane with a pore size of 500 nm was washed with water and ethanol and dried, the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was put in 1 L of the prepared solution described in step (a)), and a radiation grafting polymerization was allowed to proceed under microwave radiation with an intensity of 1000 w/cm.sup.2 and a frequency of 1000-200000 Hz for 2 h, to initiate methyl groups on the base membrane to generate radicals, such that a grafting polymerization reaction occurs between the radicals and double bonds in the acrylic acid-N-dipropylene enamine/zirconium complex in the grafting polymerization solution, so as to obtain a modified base membrane and introduce zirconium atoms on the surface thereof.

[0216] (3) The pretreated base membrane was immersed into the solution for the preparation of the MOFs in a ratio of a surface area of the pretreated base membrane to the solution described in step (1) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was put in 1 L of the solution for the preparation of the MOFs described in step (1)), to obtain a first mixture, which was then subjected to reaction for in-situ growth at 200 C. for 24 h under filling of nitrogen gas for protection, to obtain a separation membrane.

[0217] (4) The separation membrane prepared in step (3) was take out, and the unreacted monomers and the solvent on the membrane surface were cleaned away to obtain a MOFs organic gas separation membrane.

[0218] (5) The separation membrane in step (4) was cleaned to obtain a MOFs organic gas separation membrane.

[0219] An electron micrograph of the surface of the prepared membrane was shown in FIG. 3.

[0220] The test data for the performance of the membrane were shown in Table 3, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 1.4110.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.04710.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 30.00.

Example 10

[0221] Example 10 only differs from Example 9 in that, in the base membrane pretreatment of step (2), the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 0.1 m.sup.2/L (that is, the membrane with a surface area of 0.1 square meter was put in 1 L of the prepared solution described in step (a)) for grafting polymerization under radiation.

[0222] The test data for the performance of the membrane were shown in Table 3, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 0.34110.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.011410.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 29.91.

Example 11

[0223] Example 11 only differs from Example 9 in that, in the base membrane pretreatment of step (2), the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 5 m.sup.2/L (that is, the membrane with a surface area of 5 square meter was put in 1 L of the prepared solution described in step (a)) for grafting polymerization under radiation.

[0224] The test data for the performance of the membrane were shown in Table 3, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 1.88410.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.07410.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 25.46.

Example 12

[0225] Example 12 only differs from Example 9 in that, in the base membrane pretreatment of step (2), the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 10 m.sup.2/L (that is, the membrane with a surface area of 10 square meter was put in 1 L of the prepared solution described in step (a)) for grafting polymerization under radiation.

[0226] The test data for the performance of the membrane were shown in Table 3, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 2.98410.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.12110.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 24.66.

TABLE-US-00003 TABLE 3 The ratio of the surface area of the base membrane The flux of The flux of The separation to the solution nitrogen gas propylene coefficient described in step (a) 10.sup.6 mol/ 10.sup.6 mol/ for nitrogen m.sup.2/L (m.sup.2 .Math. s .Math. Pa) (m.sup.2 .Math. s .Math. Pa) gas/propylene Example 9 1 1.41 0.047 30.00 Example 10 0.1 0.341 0.0114 29.91 Example 11 5 1.884 0.074 25.46 Example 12 10 2.984 0.121 24.66

Example 13

[0227] (1) A solution required for the preparation of a MOFs membrane

[0228] N-methylpyrrolidone, terephthalic acid, zirconium tetrachloride and pure water were mixed in a molar ratio of 400:1:1:150 and fully stirred to obtain the solution required for the preparation of the MOFs membrane.

[0229] (2) Base membrane pretreatment

[0230] (a) Polyacrylic acid, partially hydrolyzed polyacrylic acid and polyvinyl alcohol with a mass concentration of 1000 mg/L and zirconium tetrachloride were mixed in a molar ratio of 2:1, and stirred for 1 h to obtain a solution after reaction;

[0231] (b) After a polyethylene hollow fiber base membrane with a pore size of 500 nm was washed with water and ethanol and dried, the solution prepared in step (a) was coated on a dried surface of the base membrane in a ratio of a surface area of the base membrane to the solution described in step (a) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was coated with 1 L of the prepared solution described in step (a)), and then dried to allow a certain amount of zirconium atoms to attach to the surface of the base membrane.

[0232] (3) The pretreated base membrane was immersed into the solution for the preparation of the MOFs in a ratio of a surface area of the pretreated base membrane to the solution described in step (1) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was put in 1 L of the solution for the preparation of the MOFs described in step (1)), to obtain a first mixture, which was then subjected to reaction for in-situ growth at 200 C. for 24 h under filling of nitrogen gas for protection, to obtain a separation membrane.

[0233] (4) The separation membrane prepared in step (3) was take out, and the unreacted monomers and the solvent on the membrane surface were cleaned away to obtain a MOFs organic gas separation membrane.

[0234] (5) The separation membrane in step (4) was cleaned to obtain a MOFs organic gas separation membrane.

[0235] An electron micrograph of the surface of the prepared membrane was shown in FIG. 4.

[0236] The test data for the performance of the membrane were shown in Table 4, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 0.89610.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.04710.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 19.06.

Example 14

[0237] Example 14 only differs from Example 13 in that, in the base membrane pretreatment of step (2), the solution prepared in step (a) was coated on a dried surface of the base membrane in a ratio of a surface area of the base membrane to the solution described in step (a) being 0.1 m.sup.2/L (that is, the membrane with a surface area of 0.1 square meter was coated with 1 L of the prepared solution described in step (a)).

[0238] The test data for the performance of the membrane were shown in Table 4, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 0.28810.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.009510.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 30.32.

Example 15

[0239] Example 15 only differs from Example 13 in that, in the base membrane pretreatment of step (2), the solution prepared in step (a) was coated on a dried surface of the base membrane in a ratio of a surface area of the base membrane to the solution described in step (a) being 5 m.sup.2/L (that is, the membrane with a surface area of 5 square meter was coated with 1 L of the prepared solution described in step (a)).

[0240] The test data for the performance of the membrane were shown in Table 4, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 1.20810.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.165910.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 7.28.

Example 16

[0241] Example 16 only differs from Example 13 in that, in the base membrane pretreatment of step (2), the solution prepared in step (a) was coated on a dried surface of the base membrane in a ratio of a surface area of the base membrane to the solution described in step (a) being 10 m.sup.2/L (that is, the membrane with a surface area of 10 square meter was coated with 1 L of the prepared solution described in step (a)).

[0242] The test data for the performance of the membrane were shown in Table 4, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa may reach 1.4810.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.265910.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 5.57.

TABLE-US-00004 TABLE 4 The ratio of the surface area of the base membrane The flux of The flux of The separation to the solution nitrogen gas propylene coefficient described in step (a) 10.sup.6 mol/ 10.sup.6 mol/ for nitrogen m.sup.2/L (m.sup.2 .Math. s .Math. Pa) (m.sup.2 .Math. s .Math. Pa) gas/propylene Example 13 1 0.896 0.047 19.06 Example 14 0.1 0.288 0.0095 30.32 Example 15 5 1.208 0.1659 7.28 Example 16 10 1.48 0.2659 5.57

Example 17

[0243] (1) A solution required for the preparation of a MOFs membrane

[0244] N-methylpyrrolidone, terephthalic acid, zirconium tetrachloride and glacial acetic acid were mixed in a molar ratio of 200:1:1:100 and fully stirred to obtain the solution required for the preparation of the MOFs membrane.

[0245] (2) Base membrane pretreatment

[0246] (a) acrylic acid-N-tert-butyl acrylamide/zirconium complex was dissolved in n-hexane with a mass concentration of 1000 mg/L to obtain a uniform solution;

[0247] (b) After a polyethylene hollow fiber base membrane with a pore size of 500 nm was washed with water and ethanol and dried, the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 10 m.sup.2/L (that is, the membrane with a surface area of 10 square meter was put in 1 L of the prepared solution described in step (a)) for 10 h, taken out and quickly transferred into deionized water for cleaning, and then taken out and dried to obtain a modified base membrane, in which partial acrylic acid-N-tert-butyl acrylamide/zirconium complex was inserted into a surface layer of the embedded base membrane structure, so as to introduce a certain amount of stable zirconium atoms into the base membrane.

[0248] (3) The pretreated base membrane was immersed into the solution for the preparation of the MOFs in a ratio of a surface area of the pretreated base membrane to the solution described in step (1) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was put in 1 L of the solution for the preparation of the MOFs described in step (1)), to obtain a first mixture, which was then subjected to reaction for in-situ growth at 200 C. for 24 h under filling of nitrogen gas for protection, to obtain a separation membrane.

[0249] (4) The separation membrane prepared in step (3) was take out, and the unreacted monomers and the solvent on the membrane surface were cleaned away to obtain a MOFs organic gas separation membrane.

[0250] (5) The separation membrane in step (4) was cleaned to obtain a MOFs organic gas separation membrane.

[0251] The test data for the performance of the membrane were shown in Table 5, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 2.46810.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.11510.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 21.46.

Example 18

[0252] Example 18 only differs from Example 17 in that, in the base membrane pretreatment of step (2), the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 0.1 m.sup.2/L (that is, the membrane with a surface area of 0.1 square meter was put in 1 L of the prepared solution described in step (a)).

[0253] The test data for the performance of the membrane were shown in Table 5, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 0.300810.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.018410.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 16.35.

Example 19

[0254] Example 19 only differs from Example 17 in that, in the base membrane pretreatment of step (2), the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was put in 1 L of the prepared solution described in step (a)).

[0255] The test data for the performance of the membrane were shown in Table 5, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 1.24110.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.03810.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 32.66.

Example 20

[0256] Example 20 only differs from Example 17 in that, in the base membrane pretreatment of step (2), the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 5 m.sup.2/L (that is, the membrane with a surface area of 5 square meter was put in 1 L of the prepared solution described in step (a)).

[0257] The test data for the performance of the membrane were shown in Table 5, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 2.19810.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.08710.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 25.26.

TABLE-US-00005 TABLE 5 The ratio of the surface area of the base membrane The flux of The flux of The separation to the solution nitrogen gas propylene coefficient described in step (a) 10.sup.6 mol/ 10.sup.6 mol/ for nitrogen m.sup.2/L (m.sup.2 .Math. s .Math. Pa) (m.sup.2 .Math. s .Math. Pa) gas/propylene Example 17 10 2.468 0.115 21.46 Example 18 0.1 0.3008 0.0184 16.35 Example 19 1 1.241 0.038 32.66 Example 20 5 2.198 0.087 25.26

Example 21

[0258] (1) A solution required for the preparation of a MOFs membrane

[0259] N-methylpyrrolidone, terephthalic acid, zirconium tetrachloride and glacial acetic acid were mixed in a molar ratio of 1000:1:1:500 and fully stirred to obtain the solution required for the preparation of the MOFs membrane.

[0260] (2) Base membrane pretreatment

[0261] (a) acrylic acid-N-tert-butyl acrylamide/zirconium complex was dissolved in a solution, and then dissolved in water with a mass concentration of 1000 mg/L to obtain a grafting polymerization solution;

[0262] (b) After a polyethylene hollow fiber base membrane with a pore size of 500 nm was washed with water and ethanol and dried, the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was put in 1 L of the prepared solution described in step (a)), and a radiation grafting polymerization was allowed to proceed under microwave radiation with an intensity of 1000 w/cm.sup.2 and a frequency of 1000-200000 Hz for 2 h, to trigger methyl groups on the base membrane to generate radicals, such that a grafting polymerization reaction occurs between the radicals and double bonds in the acrylic acid-N-dipropylene enamine/zirconium complex in the grafting polymerization solution, so as to obtain a modified base membrane and introduce zirconium atoms on the surface thereof.

[0263] (3) The pretreated base membrane was immersed into the solution for the preparation of the MOFs in a ratio of a surface area of the pretreated base membrane to the solution described in step (1) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was put in 1 L of the solution for the preparation of the MOFs described in step (1)), to obtain a first mixture, which was then subjected to reaction for in-situ growth at 200 C. for 24 h under filling of nitrogen gas for protection, to obtain a separation membrane.

[0264] (4) The separation membrane prepared in step (3) was take out, and the unreacted monomers and the solvent on the membrane surface were cleaned away to obtain a MOFs organic gas separation membrane.

[0265] (5) The separation membrane in step (4) was cleaned to obtain a MOFs organic gas separation membrane.

[0266] An electron micrograph of the surface of the prepared membrane was shown in FIG. 5.

[0267] The test data for the performance of the membrane were shown in Table 6, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 0.88910.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.04210.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 21.17.

Example 22

[0268] Example 22 only differs from Example 21 in that, in the base membrane pretreatment of step (2), the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 0.1 m.sup.2/L (that is, the membrane with a surface area of 0.1 square meter was put in 1 L of the prepared solution described in step (a)) for grafting polymerization under radiation.

[0269] The test data for the performance of the membrane were shown in Table 6, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 0.15210.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.011210.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 13.57.

Example 23

[0270] Example 23 only differs from Example 21 in that, in the base membrane pretreatment of step (2), the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 5 m.sup.2/L (that is, the membrane with a surface area of 5 square meter was put in 5 L of the prepared solution described in step (a)) for grafting polymerization under radiation.

[0271] The test data for the performance of the membrane were shown in Table 6, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 1.05510.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.08710.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 12.13.

Example 24

[0272] Example 24 only differs from Example 21 in that, in the base membrane pretreatment of step (2), the dried base membrane was immersed in the solution prepared in step (a) in a ratio of a surface area of the base membrane to the solution described in step (a) being 10 m.sup.2/L (that is, the membrane with a surface area of 10 square meter was put in 1 L of the prepared solution described in step (a)) for grafting polymerization under radiation.

[0273] The test data for the performance of the membrane were shown in Table 6, which showed that, for a mixed gas of propylene and nitrogen gas, the flux of the nitrogen gas at 0.1 Mpa can reach 1.38610.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.11410.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 12.16.

TABLE-US-00006 TABLE 6 The ratio of the surface area of the base membrane The flux of The flux of The separation to the solution nitrogen gas propylene coefficient described in step (a) 10.sup.6 mol/ 10.sup.6 mol/ for nitrogen m.sup.2/L (m.sup.2 .Math. s .Math. Pa) (m.sup.2 .Math. s .Math. Pa) gas/propylene Example 21 1 0.889 0.042 21.17 Example 22 0.1 0.152 0.0112 13.57 Example 23 5 1.055 0.087 12.13 Example 24 10 1.386 0.114 12.16

Examples 25-29

[0274] (1) A solution required for the preparation of a MOFs membrane

[0275] N-methylpyrrolidone, terephthalic acid, zirconium tetrachloride and pure water were mixed in molar ratios of 50:1:1:0.0005, 100:1:1:0.001, 200:1:1:0.002, 500:1:1:0.005, 1000:1:1:0.001 respectively and fully stirred to obtain the solution required for the preparation of the MOFs membrane.

[0276] (2) Base membrane pretreatment

[0277] (a) Polyacrylic acid, partially hydrolyzed polyacrylic acid and polyvinyl alcohol with a mass concentration of 1000 mg/L and zirconium tetrachloride were mixed in a molar ratio of 2:1, and stirred for 1 h to obtain a solution after reaction;

[0278] (b) After a polypropylene hollow fiber base membrane with a pore size of 500 nm was washed with water and ethanol and dried, the solution prepared in step (a) was coated on a dried surface of the base membrane in a ratio of a surface area of the base membrane to the solution described in step (a) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was coated with 1 L of the prepared solution described in step (a)), and then dried to allow a certain amount of zirconium atoms to attach to the surface of the base membrane.

[0279] (3) The pretreated base membrane was immersed into the solution for the preparation of the MOFs in a ratio of a surface area of the pretreated base membrane to the solution described in step (1) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was put in 1 L of the solution for the preparation of the MOFs described in step (1)), to obtain a first mixture, which was then subjected to reaction for in-situ growth at 120 C. for 24 h under filling of nitrogen gas for protection, to obtain a separation membrane.

[0280] (4) The separation membrane prepared in step (3) was take out, and the unreacted monomers and the solvent on the membrane surface were cleaned away to obtain a MOFs organic gas separation membrane.

[0281] (5) The separation membrane in step (4) was cleaned to obtain a MOFs organic gas separation membrane.

[0282] The separation membranes prepared in Example 25-29 were tested for separation coefficient for n-hexane gas and nitrogen gas and membrane fluxes thereof. The test data for the performance of the membrane were shown in Table 7.

TABLE-US-00007 TABLE 7 The molar ratio of N-methylpyrrolidone, The flux of The flux of Separation terephthalic acid, nitrogen gas n-hexane gas coefficient zirconium tetrachloride 10.sup.6 mol/ 10.sup.6 mol/ for nitrogen and pure water (m.sup.2 .Math. s .Math. Pa) (m.sup.2 .Math. s .Math. Pa) gas/n-hexane Example 25 50:1:1:0.0005 1.608 0.0473 34 Example 26 100:1:1:0.001 2.239 0.0533 42 Example 27 200:1:1:0.002 2.759 0.05871 47 Example 28 500:1:1:0.005 3.253 0.06378 51 Example 29 1000:1:1:0.01 10.079 1.120 9

[0283] It can be seen from the data in Table 7 that, as a content of the monomer in the formulation was decreased (a concentration thereof was decreased), the separation coefficient for nitrogen gas/n-hexane of the prepared separation membrane showed an increasing trend, rising from 34 to 51; and the flux were also slightly increased, rising from 1.510.sup.6 mol/(m.sup.2.Math.s.Math.Pa) to nearly 351 mol/(m.sup.2.Math.s.Math.Pa). This was mainly because that, as the concentration of the monomer was decreased, an in-situ polymerization reaction become more orderly, such that the formed functional layer had a more compact structure, decreased defects and a higher crystallinity, which was beneficial to the improvement of the separation coefficient. When the concentration of the monomer was relatively high, it was readily to form oligomers accompanied by occurrence of agglomeration phenomenon due to the high reaction speed and high ligand concentration, such that the structure of crystals was loose, whereas the oligomers blocked the channels, resulting in the reduction of the separation coefficient and the fluxes. As to the formulation in example 29, when the ratio was 1000:1:1:0.01, the separation coefficient was decreased to less than 10, but the flux exceeds 1010.sup.6 mol/(m.sup.2.Math.s.Math.Pa), indicating that when the concentration of the monomer was too low, there will be more defects in the MOFs functional layer, and the flux will be greatly increased, such that the separation performance of the membrane cannot be maintained for a long time.

Examples 30-37

[0284] (1) A solution required for the preparation of a MOFs membrane

[0285] N-methylpyrrolidone, terephthalic acid, zirconium tetrachloride and pure water were mixed in a molar ratio of 500:1:1:0.005 and fully stirred to obtain the solution required for the preparation of the MOFs membrane.

[0286] (2) Base membrane pretreatment

[0287] (a) Polyacrylic acid, partially hydrolyzed polyacrylic acid and polyvinyl alcohol with a mass concentration of 1000 mg/L and zirconium tetrachloride were mixed in a molar ratio of 2:1, and stirred for 1 h to obtain a solution after reaction;

[0288] (b) After a polypropylene hollow fiber base membrane with a pore size of 500 nm was washed with water and ethanol and dried, the solution prepared in step (a) was coated on a dried surface of the base membrane in a ratio of a surface area of the base membrane to the solution described in step (a) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was coated with 1 L of the prepared solution described in step (a)), and then dried to allow a certain amount of zirconium atoms to attach to the surface of the base membrane.

[0289] (3) The pretreated base membrane was immersed into the solution for the preparation of the MOFs in a ratio of a surface area of the pretreated base membrane to the solution described in step (1) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was put in 1 L of the solution for the preparation of the MOFs described in step (1)), to obtain a first mixture, which was then subjected to reaction for in-situ growth at 120 C. for 6 h, 12 h, 18 h, 24 h, 30 h, 36 h, 42 h and 48 h respectively under filling of nitrogen gas for protection, to obtain a separation membrane.

[0290] (4) The separation membrane prepared in step (3) was take out, and the unreacted monomers and the solvent on the membrane surface were cleaned away to obtain a MOFs organic gas separation membrane.

[0291] (5) The separation membrane in step (4) was cleaned to obtain a MOFs organic gas separation membrane.

[0292] The separation membranes prepared in Example 30-37 were tested for separation coefficient for n-hexane gas and nitrogen gas and membrane fluxes thereof. The test data for the performance of the membrane were shown in Table 8.

TABLE-US-00008 TABLE 8 The flux of The flux of Separation In situ nitrogen gas n-hexane gas coefficient growth time 10.sup.6 mol/ 10.sup.6 mol/ for nitrogen h (m.sup.2 .Math. s .Math. Pa) (m.sup.2 .Math. s .Math. Pa) gas/n-hexane Example 30 6 4.441 0.3965 11.2 Example 31 12 4.276 0.1332 32.1 Example 32 18 3.509 0.08237 42.6 Example 33 24 3.253 0.06353 51.2 Example 34 30 2.047 0.03914 52.3 Example 35 36 1.462 0.02912 50.2 Example 6 42 1.371 0.02703 50.7 Example 37 48 1.371 0.0273 50.2

[0293] It can be seen from the data in Table 8 that, when the reaction time was increased from 12 h to 24 h, the separation coefficient of the MOFs separation membrane was increased rapidly from 30 to 50. Thus it can be seen that the formation of the MOFs functional layer endowed the membrane with a separation effect for nitrogen gas/n-hexane. At the same time, the flux for gas permeation was still be maintained at a high level of above 3.010.sup.6 mol/(m.sup.2.Math.s.Math.Pa). Since the functional layer was composed of U10-66 with a uniform pore size distribution and a great porosity, which had a crystal lattice pore size of 0.6 nm that was slightly smaller than the size of a n-hexane molecule, the functional layer blocked the passage of n-hexane molecules, whereas a nitrogen gas molecule had a diameter of 3.4-3.6 nm, may pass through the MOFs membrane, thereby achieving a high flux.

[0294] As the reaction time was further increased, the separation coefficient remained stable at 52, while the flux was gradually decreased. The flux was decreased to less than 1.510.sup.6 mol/(m.sup.2.Math.s.Math.Pa) when the reaction time was 48 h. This indicated that a continuous and dense separation layer had been formed when the reaction time was 24 h. Further increase of the reaction time would only increase the thickness of the functional layer, and even would result in that a part of oligomers, monomers and solvents was wrapped in the functional layer to block the membrane pores of the membrane, causing a decrease in permeation flux. Therefore, the best reaction time was 18-24 h. When the separation coefficient reached 50, the permeation flux of the nitrogen gas exceeded 3.110.sup.6 mol/(m.sup.2.Math.s.Math.Pa), which was 10-15 times the flux of a current silicone rubber-based organic gas separation membrane, and more than 30 times the flux of an imported polyimide hydrogen gas separation membrane.

Example 38

[0295] (1) A solution required for the preparation of a MOFs membrane

[0296] N-methylpyrrolidone, terephthalic acid, zirconium tetrachloride and pure water were mixed in a molar ratio of 400:1:1:0.01 and fully stirred to obtain the solution required for the preparation of the MOFs membrane.

[0297] (2) Base membrane pretreatment

[0298] (a) Polyacrylic acid, partially hydrolyzed polyacrylic acid and polyvinyl alcohol with a mass concentration of 1000 mg/L and zirconium tetrachloride were mixed in a molar ratio of 2:1, and stirred for 1 h to obtain a solution after reaction;

[0299] (b) After a polypropylene hollow fiber base membrane with a pore size of 500 nm was washed with water and ethanol and dried, the solution prepared in step (a) was coated on a dried surface of the base membrane in a ratio of a surface area of the base membrane to the solution described in step (a) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was coated with 1 L of the prepared solution described in step (a)), and then dried to allow a certain amount of zirconium atoms to attach to the surface of the base membrane.

[0300] (3) The pretreated base membrane was immersed into the solution for the preparation of the MOFs in a ratio of a surface area of the pretreated base membrane to the solution described in step (1) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was put in 1 L of the solution for the preparation of the MOFs described in step (1)), to obtain a first mixture, which was then subjected to reaction for in-situ growth at 120 C. for 24 h under filling of nitrogen gas for protection, to obtain a separation membrane.

[0301] (4) The separation membrane prepared in step (3) was take out, and the unreacted monomers and the solvent on the membrane surface were cleaned away to obtain a MOFs organic gas separation membrane.

[0302] (5) The MOFs organic gas separation membrane prepared in step (4) was mixed with a solution containing N-methylpyrrolidone, terephthalic acid, zirconium tetrachloride and pure water to obtain a second mixture, wherein a molar ratio of the N-methylpyrrolidone, the terephthalic acid, the zirconium tetrachloride and the pure water was 400:1:1:0.01, and a ratio of a surface area of the membrane to the solution containing the N-methylpyrrolidone, the terephthalic acid, the zirconium tetrachloride and the pure water was 0.5 m.sup.2/L.

[0303] (6) the second mixture obtained in step (5) was heated at 120 C. for reaction for 12 h to obtain a separation membrane.

[0304] (7) The separation membrane in step (4) was cleaned to obtain a MOFs organic gas separation membrane.

[0305] The test data for the performance of the membrane showed that, the flux of the nitrogen gas at 0.1 Mpa can reach 3.12010.sup.6 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.08910.sup.6 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 35.05.

Example 39

[0306] (1) A solution required for the preparation of a MOFs membrane

[0307] N-methylpyrrolidone, terephthalic acid, zirconium tetrachloride and pure water were mixed in a molar ratio of 400:1:1:0.01 and fully stirred to obtain the solution required for the preparation of the MOFs membrane.

[0308] (2) Base membrane pretreatment

[0309] (a) Polyacrylic acid, partially hydrolyzed polyacrylic acid and polyvinyl alcohol with a mass concentration of 1000 mg/L and zirconium tetrachloride were mixed in a molar ratio of 2:1, and stirred for 1 h to obtain a solution after reaction;

[0310] (b) After a polypropylene hollow fiber base membrane with a pore size of 500 nm was washed with water and ethanol and dried, the solution prepared in step (a) was coated on a dried surface of the base membrane in a ratio of a surface area of the base membrane to the solution described in step (a) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was coated with 1 L of the prepared solution described in step (a)), and then dried to allow a certain amount of zirconium atoms to attach to the surface of the base membrane.

[0311] (3) The pretreated base membrane was immersed into the solution for the preparation of the MOFs in a ratio of a surface area of the pretreated base membrane to the solution described in step (1) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was put in 1 L of the solution for the preparation of the MOFs described in step (1)), to obtain a first mixture, which was then subjected to reaction for in-situ growth at 120 C. for 24 h under filling of nitrogen gas for protection, to obtain a separation membrane.

[0312] (4) The separation membrane prepared in step (3) was take out, and the unreacted monomers and the solvent on the membrane surface were cleaned away to obtain a MOFs organic gas separation membrane.

[0313] (5) The MOFs organic gas separation membrane prepared in step (4) was mixed with a solution containing N-methylpyrrolidone, terephthalic acid, zirconium tetrachloride and pure water to obtain a second mixture, wherein a molar ratio of the N-methylpyrrolidone, the terephthalic acid, the zirconium tetrachloride and the pure water was 400:1:1:0.01, and a ratio of a surface area of the membrane to the solution containing the N-methylpyrrolidone, the terephthalic acid, the zirconium tetrachloride and the pure water was 0.5 m.sup.2/L.

[0314] (6) the second mixture obtained in step (5) was heated at 120 C. for reaction for 12 h to obtain a separation membrane.

[0315] (7) Siloxane coating:

[0316] Hydroxysilane, ethyl orthosilicate and n-hexane in a ratio of 1:0.2:8.8 were mixed at room temperature, and stirred at a high speed for 24 h for dissolution, to which 0.01% dibutyltin dilaurate was added to allow pre-crosslinking for 5 h to obtain a silane coating liquid with a viscosity of 100 mPa.Math.s. Thereafter, the MOFs organic gas separation membrane prepared in step (6) was soaked into the silane coating liquid, and taken out after standing for 100 s, wherein the thickness of the coating liquid was 5-10 microns.

[0317] (8) Thermal crosslinking: the coated organic gas separation membrane was subjected to thermal crosslinking at 80 C. for 1 h to finally obtain an organic gas separation membrane with a three-layer structure.

[0318] The test data for the performance of the membrane showed that, the flux of the nitrogen gas at 0.1 Mpa can reach 1.08610.sup.7 mol/(m.sup.2.Math.s.Math.Pa), while the flux of the propylene gas was only 0.0329810.sup.7 mol/(m.sup.2.Math.s.Math.Pa); and a separation coefficient for nitrogen gas/propylene was 32.92.

Comparative Example 1

[0319] (1) Preparation of a Precursor Solution

[0320] 0.42 g of zirconium chloride and 0.30 g of terephthalic acid were dissolved in 67.5 mL of N,N-dimethylformamide (DMF), to which 32 L of deionized water was added, and the resultant was stirred under a ultrasound condition to allow the reagents to be fully dissolved, and the obtained clear precursor solution was transferred to a hydrothermal kettle;

[0321] (2) Heat Treatment

[0322] A polyvinylidene fluoride (PVDF) hollow fiber membrane was vertically soaked in the prepared precursor solution with a fixed support, and then subjected to a heat treatment at 120 C. under a constant temperature condition for 72 h. During the heat treatment, the hollow fiber membrane was still dissolved in the precursor solution, and the preparation of a separation membrane cannot be further completed.

[0323] The characterizations of the base membrane and the solution after reaction were shown in FIG. 6.

Comparative Example 2

[0324] (1) A precursor solution required for the preparation of the MOFs membrane

[0325] The precursor solution required for the preparation of the MOFs membrane is the same as that of Example 1.

[0326] (2) Base membrane pretreatment

[0327] (a) This step is same as that of Example 1;

[0328] (b) Polyvinylidene fluoride (PVDF) membrane with a pore size of 500 nm was used, and the rest was the same as that of Example 1. The resultant was subjected to a heat treatment at 120 C. under a constant temperature condition for 72 h. During the heat treatment, the hollow fiber membrane was still dissolved in the precursor solution, and the preparation of a separation membrane cannot be further completed.

[0329] The characterizations of the base membrane and the solution after reaction were shown in FIG. 7.

Comparative Example 3

[0330] (1) Preparation of a Precursor Solution

[0331] 0.42 g of zirconium chloride and 0.30 g of terephthalic acid were dissolved in 67.5 mL of N,N-dimethylformamide (DMF), to which 32 L of deionized water was added, and the resultant was stirred under a ultrasound condition to allow the reagents to be fully dissolved, and the obtained clear precursor solution was transferred to a hydrothermal kettle;

[0332] (2) Heat Treatment

[0333] A polypropylene hollow fiber membrane was vertically soaked in the prepared precursor solution with a fixed support, and subjected to a heat treatment at 120 C. under a constant temperature condition for 72 h, and then naturally cooled after heat treatment;

[0334] (3) Ultrasonic Treatment

[0335] The obtained membrane was taken out and subjected to an ultrasonic treatment for 5 s to remove the particles with poor adhesion, so as to obtain a substrate with crystal seeds;

[0336] (4) Formation of a Continuous Membrane

[0337] The substrate on which the crystal seeds was deposited was subjected to a heat treatment twice in the same method as step (2) to obtain a continuous membrane; and the continuous membrane was cleaned first with DMF and then with methanol, and dried at room temperature.

[0338] An electron micrograph of the surface of the prepared membrane was shown in FIG. 8. It can be seen from FIG. 8 that the individually octahedron structures in the MOFs functional layer of the prepared membrane was present independently of each other and an inter-embedded structure was not formed.

Comparative Example 4

[0339] (1) A solution required for the preparation of a MOFs membrane

[0340] N-methylpyrrolidone, terephthalic acid, zirconium tetrachloride and pure water were mixed in a molar ratio of 400:1:1:0.01 and fully stirred to obtain the solution required for the preparation of the MOFs membrane.

[0341] (2) After a polypropylene hollow fiber base membrane with a pore size of 500 nm was washed with water and ethanol and dried, the dried base membrane was immersed into the solution for the preparation of the MOFs membrane in a ratio of a surface area of the pretreated base membrane to the solution described in step (1) being 1 m.sup.2/L (that is, the membrane with a surface area of 1 square meter was put in 1 L of the solution for the preparation of the MOFs described in step (1)) to obtain a first mixture, which was then subjected to reaction for in-situ growth at 120 C. for 24 h under filling of nitrogen gas for protection, to obtain a separation membrane.

[0342] (3) The separation membrane prepared in step (2) was take out, and the unreacted monomers and the solvent on the membrane surface were cleaned away to obtain a MOFs organic gas separation membrane.

[0343] (4) The separation membrane in step (3) was cleaned to obtain a MOFs organic gas separation membrane.

[0344] An electron micrograph of the surface of the prepared membrane was shown in FIG. 9. It can be seen from FIG. 9 that when the base membrane was not pretreated, some discontinuous crystals were attached to the base membrane, and the crystals were composed of a plurality of octahedrons agglomerated together, and a continuous structure was not formed.

[0345] The present invention is not subject to any limitation of the embodiments. The present invention has been described with reference to typical examples, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as required within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials and examples, it does not mean that the present invention is limited to the specific examples disclosed herein. Instead, the present invention may be extended to all of other methods and applications with the same function.

DESCRIPTION OF REFERENCE NUMERALS

[0346] 1. Purging gas [0347] 2. Feed gas [0348] 3. Temperature sensor [0349] 4. Humidity sensor [0350] 5. Membrane assembly [0351] 6. Pressure gauge [0352] 7. Gas chromatograph [0353] 8. Soap-membrane flowmeter.