A composite carbon molecular sieve and preparation method thereof

Abstract

The present invention discloses a composite carbon molecular sieve and a preparation method thereof, and relates to the field of membrane separation technology. The present invention discloses a preparation method of a composite carbon molecular sieve, comprising the following steps: a porous support is immersed in a coating liquid, then taken out and dried to obtain a pre-treated molecular sieve; in an inert gas atmosphere, the pre-treated molecular sieve is carbonized to obtain a composite carbon molecular sieve; the present application first prepares a porous support as a base membrane of the composite carbon molecular sieve, effectively improving the mechanical strength of the molecular sieve, and using modified polyamic acid as a coating organic matter, and attaching the modified polyamic acid to the surface of the porous support by an impregnation method, so that the molecular sieve structure formed after the material is pyrolyzed and carbonized is loose, and the pore size of the molecular sieve is adjusted, which is conducive to the penetration and diffusion of the gas.

Description

Technical Field

[0001] The invention relates to the technical field of membrane separation, and in particular to a composite carbon molecular sieve and a preparation method thereof. Background Art

[0002] Carbon molecular sieve is a new type of carbon-based membrane material prepared by high-temperature pyrolysis of polymers. It is mainly composed of slit-shaped micropores below 1nm and a small number of macropores, with a narrow pore size distribution, generally 0.3-1.0nm. Carbon molecular sieve has excellent gas separation performance and good thermal and chemical stability. It has broad application prospects in the field of gas separation, especially in the field of small molecule gas separation, such as the enrichment and separation of oxygen and nitrogen in the air, the separation and recovery of carbon dioxide, the recovery of hydrogen, the separation and utilization of low-carbon hydrocarbons, etc. It can also be used in many aspects such as membrane reactors. There are two main gas separation mechanisms of carbon molecular sieves: adsorption equilibrium and kinetic separation. Based on kinetic separation, it is generally believed in theory that when the pore size distribution of carbon molecular sieve is uniform, between the diameters of two gases and close to the gas molecule diameter of the component to be separated, the diffusion rate or adsorption rate of the mixed gas in its pores is different, thereby achieving gas separation.

[0003] In the prior art, polyamic acid is used as a precursor, and pyrolysis and carbonization are carried out. The chemical structure undergoes low-temperature pyrolysis and high-temperature carbonization during the pyrolysis process. Low-temperature pyrolysis undergoes imidization and structural reformation to form a cross-linked network structure, forming carbon microcrystals. The disordered accumulation of carbon microcrystals constitutes the disordered pore structure of the composite carbon molecular sieve. The pores are tortuous and the paths are long. The gas permeation and diffusion time in the pores is long, the resistance is large, and the gas permeation flux is low. Polyimide carbon molecular sieves have not yet been able to achieve large-scale industrial applications. The main reason is that the existing carbon molecular sieves not only have low strength, but also poor gas permeability. In contrast, the use of supported carbon membranes with high mechanical strength for performance optimization has become an important way to achieve industrial applications of carbon membranes. Supported carbon membranes are composite carbon membranes prepared by pyrolysis by coating carbon membrane precursors on a support by different methods. The impregnation method is a simple and widely used preparation method. Its principle is to immerse the support into the precursor, let it stand for a period of time, allow the precursor to penetrate into the surface pores of the support, and then go through heat treatment such as drying and carbonization. However, the thickness of the carbon film prepared by the impregnation method in the prior art is uneven, and even cracks occur. Summary of the invention

[0004] The purpose of the present invention is to provide a composite carbon molecular sieve and a preparation method thereof to solve the following technical problems:

[0005] The existing polyimide carbon molecular sieves not only have low strength but also poor gas permeability and have not yet been able to achieve large-scale industrial application.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing a composite carbon molecular sieve comprises the following steps: immersing a thiol-modified porous support in a coating solution, taking it out, and drying it to obtain a pre-treated molecular sieve; carbonizing the pre-treated molecular sieve to obtain a composite carbon molecular sieve;

[0008] The coating liquid is a solution containing 1-10wt% of modified polyamic acid;

[0009] The preparation method of modified polyamic acid comprises the following steps:

[0010] S1: In a nitrogen atmosphere, benzoguanamine and N,N-dimethylformamide are added into a reaction kettle, and 1,2,4,5-pyromellitic dianhydride is added, the temperature is controlled at 60-70°C, the reaction is kept warm for 1-2 hours, water is added to precipitate, filtered, washed, and dried to obtain polyamic acid;

[0011] S2: In a nitrogen atmosphere, polyamic acid and N-methyl-2-pyrrolidone are added to a reaction kettle and dispersed evenly, 3-isocyanate propyl triethoxysilane is added, the temperature is controlled at 55-65°C, the reaction is kept warm for 3-6 hours, water is added to stop the reaction, methanol is washed, and the reaction is dried to obtain organosilicon-modified polyamic acid;

[0012] S3: adding organosilicon-modified polyamic acid, 5-hydroxy-2-pentene and deionized water into a reaction kettle, uniformly dispersing by ultrasonication, stirring and reacting for 9-12 hours at room temperature, filtering and drying to obtain modified polyamic acid.

[0013] As a further solution of the present invention: the coating liquid is composed of modified polyamic acid and a solvent; the solvent is any one of anhydrous ethanol, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and tetrahydrofuran.

[0014] As a further embodiment of the present invention, the addition ratio of benzoguanamine, N,N-dimethylformamide and 1,2,4,5-pyromellitic dianhydride in S1 is 10 g: 100-200 mL: 10-13 g.

[0015] As a further solution of the present invention: the addition ratio of polyamic acid, N-methyl-2-pyrrolidone and 3-isocyanatepropyltriethoxysilane in S2 is 10 g: 100-200 mL: 4-6 g.

[0016] As a further solution of the present invention: the addition ratio of the organosilicon-modified polyamic acid, 5-hydroxy-2-pentene and deionized water in S3 is 10 g: 0.5-1.5 g: 100-200 mL.

[0017] As a further embodiment of the present invention: the preparation method of the thiol-modified porous support comprises the following steps:

[0018] A1: Add imidazole-2-carboxaldehyde and deionized water 1 into a reaction kettle and disperse them evenly, mix zinc nitrate hexahydrate and deionized water 2 and add them into the reaction kettle, stir evenly, centrifuge and wash to obtain component 1;

[0019] A2: Add component 1 and methanol into a reaction kettle and disperse them evenly, add 5-amino-1-mercaptopentane, heat and reflux for 1-2 hours, wash with methanol, and dry to obtain a thiolated porous support.

[0020] As a further embodiment of the present invention, the addition ratio of imidazole-2-carboxaldehyde, deionized water 1, zinc nitrate hexahydrate, and deionized water 2 in A1 is 10 g: 15-30 mL: 8-10 g: 15-30 mL.

[0021] As a further embodiment of the present invention: the addition ratio of component 1, methanol and 5-amino-1-mercaptopentane in A2 is 10 g: 100-200 mL: 2-6 g.

[0022] As a further solution of the present invention: the specific procedure of carbonization treatment is:

[0023] Stage 1 heating: heating rate 15-25℃ / min, heating to T1=300-350℃ under normal temperature;

[0024] Second stage heating: heating rate 5-10℃ / min, heating to T2=800-850℃ under T1 condition;

[0025] Three-stage heating: heating rate 1-5℃ / min, heating to 850-900℃ under T2 condition temperature, and keeping warm for 2-5h.

[0026] As a further solution of the present invention: the carbonization treatment is carried out in an inert gas atmosphere; the inert gas is any one of nitrogen, helium or argon; the inert gas flow rate is 500-1500 mL / min.

[0027] As a further scheme of the present invention: the specific steps of drying in the preparation method of the composite carbon molecular sieve are: drying at 80-100°C in an inert gas atmosphere for 3-6 hours; then drying at 130-160°C for 3-6 hours, and naturally cooling to room temperature; the inert gas is any one of nitrogen, helium or argon, and the inert gas flow rate is 100-500mL / min.

[0028] A composite carbon molecular sieve is prepared by any one of the above preparation methods.

[0029] Beneficial effects of the present invention:

[0030] (1) This application uses imidazole-2-carboxaldehyde and zinc nitrate hexahydrate to react to prepare a zeolite imidazole ester framework material, namely component one; and uses the aldehyde group on component one to react with the amino group of 5-amino-1-mercaptopentane to obtain a thiolated porous support. This application uses benzoguanamine and 1,2,4,5-pyromellitic dianhydride as raw materials to polymerize polyamic acid; and uses the carboxyl group of polyamic acid to react with the isocyanate group of 3-isocyanate propyltriethoxysilane to obtain organosilicon-modified polyamic acid; finally, uses the organosilicon-modified polyamic acid grafted with siloxane groups to undergo dehydration condensation with 5-hydroxy-2-pentene to obtain modified polyamic acid. The present application utilizes modified polyamic acid to prepare a coating liquid, and the thiol-modified porous support prepared in the present application is immersed in the coating liquid. The thiol groups on the surface of the thiol-modified porous support undergo a click reaction with the modified polyamic acid, and the modified polyamic acid and the thiol-modified porous support are connected by chemical bonds, thereby effectively improving the uniformity of the dispersion of the polyamic acid on the surface of the thiol-modified porous support.

[0031] (2) The modified polyamic acid prepared in the present application is used as a precursor for pyrolysis and carbonization. The chemical structure undergoes low-temperature pyrolysis and high-temperature carbonization during the pyrolysis process. Low-temperature pyrolysis causes imidization and structural reorganization to form a cross-linked network structure, which constitutes the prototype of the carbon structure; high-temperature carbonization causes violent thermal decomposition and thermal polycondensation reactions, and during the high-temperature carbonization process, the organic silicon molecular chains evenly connected on the polyamic acid molecular chains are inorganicized to form silicon dioxide, which effectively regulates the pore structure of the composite carbon molecular sieve. The molecular sieve formed after pyrolysis and carbonization has a loose structure, which is conducive to gas permeation and diffusion.

[0032] The thiol-modified porous support prepared in the present application has the characteristics of developed, uniform pore structure and high mechanical strength, which effectively improves the mechanical strength of the molecular sieve material; the present application uses modified polyamic acid as the membrane-making liquid to modify the surface of the support, thereby realizing the preparation of molecular sieves with high permeability and high separation selectivity on a support with a larger pore structure; the thiol-modified porous support prepared in the present application and the modified polyamic acid act synergistically, and the film-forming effect is good. DETAILED DESCRIPTION

[0033] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1 The preparation method of the thiol-modified porous support comprises the following steps:

[0035] A1: 10 g imidazole-2-carboxaldehyde and 15 mL deionized water 1 were added to a reaction kettle and dispersed evenly. 8 g zinc nitrate hexahydrate and 15 mL deionized water 2 were mixed and added to the reaction kettle. The mixture was stirred evenly, centrifuged and washed to obtain component 1.

[0036] A2: 10 g of component 1 and 100 mL of methanol were added into a reaction kettle and dispersed evenly. 2 g of 5-amino-1-mercaptopentane was added and the temperature was raised to reflux for reaction for 1 h. The mixture was washed with methanol and dried to obtain a thiolated porous support.

[0037] The preparation method of modified polyamic acid comprises the following steps:

[0038] S1: In a nitrogen atmosphere, 10 g of benzoguanamine and 100 mL of N,N-dimethylformamide were added to a reaction kettle, and 10 g of 1,2,4,5-pyromellitic dianhydride was added. The temperature was controlled at 60°C, and the reaction was kept warm for 1 hour. Water was added to precipitate, filtered, washed, and dried to obtain polyamic acid;

[0039] S2: In a nitrogen atmosphere, 10 g of polyamic acid and 100 mL of N-methyl-2-pyrrolidone were added to a reaction kettle and dispersed evenly, 4 g of 3-isocyanate propyltriethoxysilane was added, the temperature was controlled at 55°C, the reaction was kept warm for 3 h, water was added to stop the reaction, methanol was washed, and dried to obtain organosilicon-modified polyamic acid;

[0040] S3: 10 g of organosilicon-modified polyamic acid, 0.5 g of 5-hydroxy-2-pentene, and 100 mL of deionized water were added into a reaction kettle and dispersed evenly by ultrasonication. The mixture was stirred and reacted for 9 h at room temperature, filtered, and dried to obtain modified polyamic acid.

[0041] Example 2 The preparation method of the thiol-modified porous support comprises the following steps:

[0042] A1: 10 g imidazole-2-carboxaldehyde and 20 mL deionized water 1 were added to a reaction kettle and dispersed evenly. 9 g zinc nitrate hexahydrate and 20 mL deionized water 2 were mixed and added to the reaction kettle. The mixture was stirred evenly, centrifuged and washed to obtain component 1.

[0043] A2: 10 g of component 1 and 150 mL of methanol were added into a reaction kettle and dispersed evenly. 4 g of 5-amino-1-mercaptopentane was added and the temperature was raised to reflux for reaction for 1.5 h. The mixture was washed with methanol and dried to obtain a thiolated porous support.

[0044] The preparation method of modified polyamic acid comprises the following steps:

[0045] S1: In a nitrogen atmosphere, 10 g of benzoguanamine and 150 mL of N,N-dimethylformamide were added to a reaction kettle, and 11.5 g of 1,2,4,5-pyromellitic dianhydride was added. The temperature was controlled at 65°C, and the reaction was kept warm for 1.5 hours. Water was added to precipitate, filtered, washed, and dried to obtain polyamic acid;

[0046] S2: In a nitrogen atmosphere, 10 g of polyamic acid and 150 mL of N-methyl-2-pyrrolidone were added to a reaction kettle and dispersed evenly, 5 g of 3-isocyanatepropyltriethoxysilane was added, the temperature was controlled at 60°C, the reaction was kept warm for 4.5 hours, water was added to stop the reaction, methanol was washed, and dried to obtain organosilicon-modified polyamic acid;

[0047] S3: 10 g of organosilicon-modified polyamic acid, 1 g of 5-hydroxy-2-pentene, and 150 mL of deionized water were added into a reaction kettle and ultrasonically dispersed uniformly. The mixture was stirred for reaction at room temperature for 10 h, filtered, and dried to obtain modified polyamic acid.

[0048] Example 3 The preparation method of the thiol-modified porous support comprises the following steps:

[0049] A1: 10 g of imidazole-2-carboxaldehyde and 30 mL of deionized water 1 were added to a reaction kettle and dispersed evenly. 10 g of zinc nitrate hexahydrate and 30 mL of deionized water 2 were mixed and added to the reaction kettle. The mixture was stirred evenly, centrifuged and washed to obtain component 1.

[0050] A2: 10 g of component 1 and 200 mL of methanol were added into a reaction kettle and dispersed evenly. 6 g of 5-amino-1-mercaptopentane was added and the temperature was raised to reflux for reaction for 2 h. The mixture was washed with methanol and dried to obtain a thiolated porous support.

[0051] The preparation method of modified polyamic acid comprises the following steps:

[0052] S1: In a nitrogen atmosphere, 10 g of benzoguanamine and 200 mL of N,N-dimethylformamide were added to a reaction kettle, and 13 g of 1,2,4,5-pyromellitic dianhydride was added. The temperature was controlled at 70°C, and the reaction was kept warm for 2 h. Water was added to precipitate, filtered, washed, and dried to obtain polyamic acid;

[0053] S2: In a nitrogen atmosphere, 10 g of polyamic acid and 200 mL of N-methyl-2-pyrrolidone were added to a reaction kettle and dispersed evenly, 6 g of 3-isocyanatepropyltriethoxysilane was added, the temperature was controlled at 65°C, the reaction was kept warm for 6 hours, water was added to stop the reaction, methanol was washed, and dried to obtain organosilicon-modified polyamic acid;

[0054] S3: 10 g of organosilicon-modified polyamic acid, 1.5 g of 5-hydroxy-2-pentene, and 200 mL of deionized water were added into a reaction kettle and dispersed evenly by ultrasonication. The mixture was stirred and reacted for 12 h at room temperature, filtered, and dried to obtain modified polyamic acid.

[0055] Example 4 A method for preparing a composite carbon molecular sieve comprises the following steps:

[0056] B1: The modified polyamic acid prepared in Example 1 is blended with N,N-dimethylformamide to obtain a 10 wt % modified polyamic acid solution as a coating solution;

[0057] B2: The thiolated porous support prepared in Example 1 was immersed in the coating solution prepared in step B1 for 24 hours, taken out, placed in a nitrogen atmosphere with a nitrogen flow rate of 100 mL / min, dried at 80°C for 6 hours, then placed in a nitrogen atmosphere for 3 hours, and naturally cooled to room temperature to obtain a pretreated molecular sieve;

[0058] B3: Place the pretreated molecular sieve prepared in step B2 in a muffle furnace, flush with argon gas at a flow rate of 500 mL / min, so that the muffle furnace is in an argon gas atmosphere, and heat up to T1 = 300 °C at room temperature at a heating rate of 15 °C / min; heat up to T2 = 800 °C at T1 at a heating rate of 10 °C / min; heat up to 850 °C at T2 at a heating rate of 5 °C / min, and keep warm for 2 hours to obtain a composite carbon molecular sieve.

[0059] Example 5 Compared with Example 4, Example 5 only replaces the modified polyamic acid prepared in Example 1 used in Example 4 with an equal amount of modified polyamic acid prepared in Example 2; and replaces the thiol-containing porous support prepared in Example 1 used in Example 4 with the thiol-containing porous support prepared in Example 2; the remaining components and preparation method of Example 5 are exactly the same as those of Example 4.

[0060] Example 6 Compared with Example 4, Example 6 only replaces the modified polyamic acid prepared in Example 1 used in Example 4 with an equal amount of modified polyamic acid prepared in Example 3; and replaces the thiol-containing porous support prepared in Example 1 used in Example 4 with the thiol-containing porous support prepared in Example 3; the remaining components and preparation method of Example 5 are exactly the same as those of Example 4.

[0061] Comparative Example 1 The preparation method of the porous support comprises the following steps:

[0062] 10 g of imidazole-2-carboxaldehyde and 20 mL of deionized water were added into the reaction kettle and dispersed evenly. 9 g of zinc nitrate hexahydrate and 20 mL of deionized water were mixed and added into the reaction kettle. The mixture was stirred evenly, centrifuged and washed to obtain a porous support.

[0063] The preparation method of the modified polyamic acid is exactly the same as that of Example 2.

[0064] Comparative Example 2 The preparation method of the thiol-modified porous support is completely consistent with that of Example 2.

[0065] The preparation method of modified polyamic acid comprises the following steps:

[0066] S1: In a nitrogen atmosphere, 10 g of benzoguanamine and 150 mL of N,N-dimethylformamide were added to a reaction kettle, and 11.5 g of 1,2,4,5-pyromellitic dianhydride was added. The temperature was controlled at 65°C, and the reaction was kept warm for 1.5 hours. Water was added to precipitate, filtered, washed, and dried to obtain polyamic acid;

[0067] S2: In a nitrogen atmosphere, 10 g of polyamic acid and 150 mL of N-methyl-2-pyrrolidone were added to a reaction kettle and dispersed evenly, 5 g of 3-isocyanatepropyltriethoxysilane was added, the temperature was controlled at 60°C, the reaction was kept warm for 4.5 hours, water was added to stop the reaction, methanol was washed and dried to obtain modified polyamic acid.

[0068] Comparative Example 3 The preparation method of the thiol-modified porous support is completely consistent with that of Example 2.

[0069] The preparation method of modified polyamic acid comprises the following steps:

[0070] S1: In a nitrogen atmosphere, 10 g of benzoguanamine and 150 mL of N,N-dimethylformamide were added to a reaction kettle, and 11.5 g of 1,2,4,5-pyromellitic dianhydride was added. The temperature was controlled at 65 ° C. The reaction was kept warm for 1.5 h, water was added to precipitate, filtered, washed, and dried to obtain polyamic acid;

[0071] S2: 10 g of polyamic acid, 1 g of 5-hydroxy-2-pentene and 150 mL of deionized water were added into a reaction kettle for uniform ultrasonic dispersion. The mixture was stirred for reaction at room temperature for 10 h, filtered and dried to obtain modified polyamic acid.

[0072] Comparative Example 4 Compared with Example 4, Comparative Example 4 only replaces the modified polyamic acid prepared in Example 1 used in Example 4 with an equal amount of the modified polyamic acid prepared in Comparative Example 1; the thiol-containing porous support prepared in Example 1 used in Example 4 is replaced with the porous support prepared in Comparative Example 1; the remaining components and preparation method of Comparative Example 4 are exactly the same as those of Example 4.

[0073] Comparative Example 5 Compared with Example 4, Comparative Example 5 only replaces the modified polyamic acid prepared in Example 1 used in Example 4 with an equal amount of modified polyamic acid prepared in Comparative Example 2; the thiol-containing porous support prepared in Example 1 used in Example 4 is replaced with the thiol-containing porous support prepared in Comparative Example 2; the remaining components and preparation method of Comparative Example 5 are exactly the same as those of Example 4.

[0074] Comparative Example 6 Compared with Example 4, Comparative Example 6 only replaces the modified polyamic acid prepared in Example 1 used in Example 4 with an equal amount of modified polyamic acid prepared in Comparative Example 3; and replaces the thiol-containing porous support prepared in Example 1 used in Example 4 with the thiol-containing porous support prepared in Comparative Example 3; the remaining components and preparation method of Comparative Example 6 are exactly the same as those of Example 4.

[0075] Performance Testing

[0076] (1) Pure component gas permeability test: The composite carbon molecular sieves prepared in Examples 4-6 and Comparative Examples 4-6 were tested for their permeability to 5N high-purity gas (hydrogen, nitrogen, carbon dioxide, oxygen) using a constant pressure-variable volume method; the gas permeability was tested at a temperature of 30°C and a transmembrane pressure of 0.15 MPa; the test results are shown in Table 1;

[0077] Table 1: Statistical table of permeability test data of Examples 4-6 and Comparative Examples 4-6

[0078]

[0079] (2) Mixed gas selectivity test: Using a GC-9790 gas chromatograph, at a permeation temperature of 30°C and a permeation pressure of 0.15 MPa, the molecular sieve was tested for separation of O2 / N2 in compressed air. The test results are shown in Table 2.

[0080] Table 2: Statistical table of selective detection data of Examples 4-6 and Comparative Examples 4-6

[0081]

[0082] As can be seen from Table 1-2, the composite carbon molecular sieve prepared in the present application modifies and optimizes the pore structure of the molecular sieve, while ensuring the high selectivity of the molecular sieve and expanding the permeability of the molecular sieve, so that the prepared composite carbon molecular sieve has the advantages of high selectivity and high permeability.

[0083] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing a composite carbon molecular sieve, characterized in that: The method comprises the following steps: immersing the thiol-modified porous support in a coating liquid, taking it out, and drying it to obtain a pre-treated molecular sieve; carbonizing the pre-treated molecular sieve to obtain a composite carbon molecular sieve; The coating solution is a solution containing 1-10wt% of modified polyamic acid; The preparation method of modified polyamic acid comprises the following steps: S1: In a nitrogen atmosphere, benzoguanamine and N,N-dimethylformamide are added into a reaction kettle, and 1,2,4,5-pyromellitic dianhydride is added, the temperature is controlled at 60-70°C, the reaction is kept warm for 1-2 hours, water is added to precipitate, filtered, washed, and dried to obtain polyamic acid; S2: In a nitrogen atmosphere, polyamic acid and N-methyl-2-pyrrolidone are added to a reaction kettle and dispersed evenly, 3-isocyanate propyl triethoxysilane is added, the temperature is controlled at 55-65°C, the reaction is kept warm for 3-6 hours, water is added to stop the reaction, methanol is washed, and the reaction is dried to obtain organosilicon-modified polyamic acid; S3: adding organosilicon-modified polyamic acid, 5-hydroxy-2-pentene and deionized water into a reaction kettle, uniformly dispersing by ultrasonication, stirring and reacting for 9-12 hours at room temperature, filtering and drying to obtain modified polyamic acid.

2. The method for preparing a composite carbon molecular sieve according to claim 1, characterized in that: The addition ratio of benzoguanamine, N,N-dimethylformamide and 1,2,4,5-pyromellitic dianhydride in S1 is 10g:100-200mL:10-13g.

3. The method for preparing a composite carbon molecular sieve according to claim 1, characterized in that: The addition ratio of polyamic acid, N-methyl-2-pyrrolidone, and 3-isocyanatepropyltriethoxysilane in S2 is 10 g: 100-200 mL: 4-6 g.

4. The method for preparing a composite carbon molecular sieve according to claim 1, characterized in that: The addition ratio of the organosilicon-modified polyamic acid, 5-hydroxy-2-pentene, and deionized water in S3 is 10 g: 0.5-1.5 g: 100-200 mL.

5. The method for preparing a composite carbon molecular sieve according to claim 1, characterized in that: The preparation method of the thiol porous support comprises the following steps A1: Add imidazole-2-carboxaldehyde and deionized water 1 into a reaction kettle and disperse them evenly, mix zinc nitrate hexahydrate and deionized water 2 and add them into the reaction kettle, stir evenly, centrifuge and wash to obtain component 1; A2: Add component 1 and methanol into a reaction kettle and disperse them evenly, add 5-amino-1-mercaptopentane, heat and reflux for 1-2 hours, wash with methanol, and dry to obtain a thiolated porous support.

6. The method for preparing a composite carbon molecular sieve according to claim 5, characterized in that: The addition ratio of imidazole-2-carboxaldehyde, deionized water 1, zinc nitrate hexahydrate, and deionized water 2 in A1 is 10 g: 15-30 mL: 8-10 g: 15-30 mL.

7. The method for preparing a composite carbon molecular sieve according to claim 5, characterized in that: The addition ratio of component 1, methanol, and 5-amino-1-mercaptopentane in A2 is 10 g: 100-200 mL: 2-6 g.

8. The method for preparing a composite carbon molecular sieve according to claim 1, characterized in that: The specific procedures of carbonization treatment are: Stage 1 heating: heating rate 15-25℃ / min, heating to T1=300-350℃ under normal temperature; Second stage heating: heating rate 5-10℃ / min, heating to T2=800-850℃ under T1 condition; Three-stage heating: heating rate 1-5℃ / min, heating to 850-900℃ under T2 condition temperature, and keeping warm for 2-5h.

9. The method for preparing a composite carbon molecular sieve according to claim 8, characterized in that: The carbonization treatment is carried out in an inert gas atmosphere; the inert gas is any one of nitrogen, helium or argon; the inert gas flow rate is 500-1500 mL / min.

10. A composite carbon molecular sieve, characterized in that: Prepared by the preparation method described in any one of claims 1 to 9.

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