A modification method for improving the performance of carbon molecular sieve membrane gas separation
By introducing an oxidant into the carbon molecular sieve membrane to adjust the pore size, the problem of insufficient hydrogen separation performance of existing carbon molecular sieve membranes was solved, achieving a high-efficiency gas separation performance improvement and energy consumption reduction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-17
- Publication Date
- 2026-04-10
AI Technical Summary
Existing carbon molecular sieve membranes have insufficient performance in hydrogen separation processes, and existing modification methods are complex to operate and have high energy consumption.
Oxygen-containing functional groups were introduced into the carbon molecular sieve membrane by impregnation, and the membrane was then subjected to simple post-treatment with oxidants such as sodium hypochlorite to adjust the membrane pore size and improve hydrogen sieving performance.
It significantly improves the separation performance of hydrogen/methane, hydrogen/nitrogen, and hydrogen/carbon dioxide by carbon molecular sieve membranes, simplifies the operation process, and reduces energy consumption.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of membrane preparation and application, and discloses a modification method for improving the gas separation performance of carbon molecular sieve membranes. BACKGROUND
[0002] Hydrogen is one of the important components of future energy, and its sources are diverse. The mainstream hydrogen production process is usually accompanied by the generation of various impurities, such as H2O, CO2, CO, N2 and hydrocarbons, which will have a great impact on the subsequent use of hydrogen. Therefore, efficient separation of H2 from other impurity gases is the key to the preparation of high-purity H2.
[0003] Membrane separation technology has a series of advantages such as high energy efficiency, low cost, small space occupation and simple maintenance, and has a high H2 purification potential. Specific temperature programmed pyrolysis of polymer membranes can produce carbon molecular sieve membranes, which have adsorption / diffusion mechanisms and thus exhibit selective separation of specific gas pairs. The adsorption / diffusion performance of carbon molecular sieve membranes depends largely on their surface properties. Steam activation, ammonia activation and fluorine treatment methods have been applied to carbon molecular sieve membranes and have been proven to be able to improve the specific gas separation performance of carbon molecular sieve membranes. For example, the use of fluorine / nitrogen blowing post-surface treatment method for existing carbon molecular sieve membranes can significantly improve their He / H2 separation performance (Qi Wu, Lu Liu, Yang Jiao, Zhenyuan Li, Ju Bai, Prof. Xiaohua Ma, Prof. Shuangjiang Luo, Prof. Suojian Zhang, Precise Helium Sieving from Hydrogen Using Fluorine-Decorated Carbon Hollow Fiber Membranes, Angew. Chem. Int. Ed, 2024, 63(33), e202400688) Steam activation post-treatment can also change the gas permeation performance of carbon molecular sieve membranes (Hui-Chun Lee, Majid Monji Doug Parsley, Muhammad Sahimi, Paul Liu, Fokion Egolfopoulos, Theodore Tsotsis, Use of Steam Activation as a Post-treatment Technique in the Preparation of Carbon Molecular Sieve Membranes, Ind. Eng. Chem. Res., 2013, 52(3), 1122-1132,). But the existing carbon molecular sieve membrane post-processing means all have the characteristics of complex operation, high energy consumption. The present application intends to develop a low energy consumption, simple operation of carbon molecular sieve membrane modification method, for improving its hydrogen / methane, hydrogen / nitrogen and hydrogen / carbon dioxide separation performance. SUMMARY
[0004] In view of the insufficient hydrogen separation performance of the existing carbon molecular sieve membrane, the present application provides a modification method for improving the gas separation performance of the carbon molecular sieve membrane.
[0005] The technical scheme of the present application:
[0006] A modification method for improving the gas separation performance of the carbon molecular sieve membrane, by impregnation method, oxygen-containing functional groups are introduced into the prepared carbon molecular sieve membrane, to obtain a carbon molecular sieve membrane with high hydrogen / methane, hydrogen / nitrogen and hydrogen / carbon dioxide separation performance, so as to further improve the small molecule gas such as hydrogen of the carbon molecular sieve membrane.
[0007] Specifically includes the following steps:
[0008] (1) Preparation of polymer precursor film: dissolve polymer A in solvent B to form casting solution, after sufficient stirring, pour it into a watch glass, after complete evaporation of the solvent at a certain temperature, put it into vacuum condition to further dry the solvent to obtain polymer precursor film;
[0009] (2) Preparation of carbon molecular sieve membrane: heat the polymer precursor film to 550℃ in a tube furnace under inert gas N2 atmosphere and keep for 2h, after natural cooling to room temperature, obtain carbon molecular sieve membrane;
[0010] (3) Carbon molecular sieve membrane post-processing: put the carbon molecular sieve membrane into solution D, constant stirring, soak for a certain time, take out the carbon molecular sieve membrane and put it into vacuum condition for drying.
[0011] Further, polymer A is a trog base polymer Base), 6FDA-DAM polymer, 6FDA-DAM-DABA, Matrimid, P84 polymer; solvent B is one of chloroform, N-methyl pyrrolidone, N, N-dimethylformamide; solution D is one or more than two kinds of mixture of sodium hypochlorite, potassium persulfate, sodium persulfate, hydrogen peroxide, potassium permanganate.
[0012] Further, in step (1), the mass fraction of the casting solution is 2%-20%; the time of sufficient stirring is 12-24h; the solvent evaporation temperature is 25-80℃.
[0013] Further, in step (3), the concentration of solution D is 50-800ppm; the stirring rate is 100-1000r / min; the soaking time is 12-48h.
[0014] Compared with the prior art, the present application has the advantages that: through a simple post-processing solution immersion step, oxidation functional groups are introduced into the carbon molecular sieve membrane to adjust the membrane pore size, and the hydrogen screening performance of the carbon molecular sieve membrane is greatly improved. BRIEF DESCRIPTION OF DRAWINGS
[0015] Figure 1 is the XRD spectrum of Comparative Example 1 and Example 1.
[0016] Figure 2 is the infrared spectrum of Comparative Example 1 and Example 1. DETAILED DESCRIPTION
[0017] The specific embodiments of the present application are further described below in combination with the drawings and technical solutions.
[0018] The preparation method of the carbon molecular sieve membrane used in the present application is: dissolving the polymer into a chloroform solution to form a casting solution with a mass fraction of 2%, and further drying after forming a polymer membrane by sufficient natural evaporation; then, cutting a 2*2cm 2 The polymer membrane is heated to 550℃ in a tube furnace under an inert gas N2 atmosphere and kept for 2h, and the final carbon molecular sieve membrane is obtained after natural cooling to room temperature.
[0019] Gas permeability test: the permeability test of the carbon molecular sieve gas separation membrane in the present application adopts the constant volume pressure swing method, and the test temperature is 35℃.
[0020] Comparative Example 1
[0021] 0.2g of Trogamine-based polymer is dissolved in 9.8g of chloroform solvent, and after the solvent is sufficiently and naturally volatilized, the formed polymer membrane is further dried; then, a 2*2cm 2The Troger base polymer membrane was heated to 550°C in a tube furnace under inert gas N2 atmosphere for 2 h, and the 6FDA-DAM-DABA carbon molecular sieve membrane was obtained after natural cooling to room temperature.
[0022] Comparative Example 2
[0023] 0.2 g of 6FDA-DAM-DABA polymer was dissolved in 9.8 g of chloroform solvent, and after the solvent was sufficiently naturally volatilized, the formed polymer membrane was further dried; then, the cut 2x2 cm 2 The Troger base polymer membrane was heated to 550°C in a tube furnace under inert gas N2 atmosphere for 2 h, and the 6FDA-DAM-DABA carbon molecular sieve membrane was obtained after natural cooling to room temperature.
[0024] Comparative Example 3
[0025] 0.2 g of 6FDA-DAM polymer was dissolved in 9.8 g of chloroform solvent, and after the solvent was sufficiently naturally volatilized, the formed polymer membrane was further dried; then, the cut 2x2 cm 2 The Troger base polymer membrane was heated to 550°C in a tube furnace under inert gas N2 atmosphere for 2 h, and the 6FDA-DAM-DABA carbon molecular sieve membrane was obtained after natural cooling to room temperature.
[0026] Example 1
[0027] The Troger base carbon molecular sieve membrane was prepared according to the same preparation route. The prepared Troger base carbon molecular sieve membrane was placed in an 800 ppm sodium hypochlorite solution and soaked at a stirring rate of 800 r / min for 12 h, and after the carbon molecular sieve membrane was taken out, it was placed in a vacuum drying oven at 80°C for drying for 24 h.
[0028] Example 2
[0029] The 6FDA-DAM-DABA carbon molecular sieve membrane was prepared according to the same preparation route. The prepared 6FDA-DAM-DABA carbon molecular sieve membrane was placed in an 800 ppm sodium hypochlorite solution and soaked at a stirring rate of 800 r / min for 12 h, and after the carbon molecular sieve membrane was taken out, it was placed in a vacuum drying oven at 80°C for drying for 24 h.
[0030] Example 3
[0031] The 6FDA-DAM carbon molecular sieve membrane was prepared according to the same preparation route. The prepared 6FDA-DAM carbon molecular sieve membrane was placed in an 800 ppm sodium hypochlorite solution and soaked at a stirring rate of 800 r / min for 12 h, and after the carbon molecular sieve membrane was taken out, it was placed in a vacuum drying oven at 80°C for drying for 24 h.
[0032] The gas separation performance of Comparative Examples 1, 2, 3 and Examples 1, 2 / 3 at 35°C, 2 Bar is shown in the following table, wherein by comparing Comparative Example 1 and Example 1, Comparative Example 2 and Example 2, Comparative Example 3 and Example 3, we can find that the hydrogen / methane and hydrogen / nitrogen selectivity of the modified Troger's base-based carbon molecular sieve is increased by 119.5% and 29.6%, respectively; the hydrogen / methane and hydrogen / nitrogen selectivity of the modified 6FDA-DAM-DABA carbon molecular sieve is increased by 1167.6% and 458.5%, respectively; the hydrogen / methane and hydrogen / nitrogen selectivity of the modified 6FDA-DAM carbon molecular sieve is increased by 470.2% and 106.2%, respectively. At the same time, the originally low hydrogen / carbon dioxide separation capacity is also significantly improved.
[0033] Table 1 is the gas permeability and selectivity of the gas separation membrane prepared by Comparative Example 1, Comparative Example 2, Comparative Example 3, Example 1, Example 2 and Example 3
[0034]
[0035]
Claims
1. A modification method for improving the performance of a carbon molecular sieve membrane gas separation, characterized by, The method comprises the following steps: (1) Preparation of polymer precursor film: dissolve polymer A in solvent B to form a casting solution, pour the casting solution into a petri dish after sufficient stirring, and then completely volatilize the solvent at a certain temperature, and then further dry the solvent under vacuum to obtain a polymer precursor film; (2) Preparation of carbon molecular sieve membrane: heat the polymer precursor film to 550 DEG C in a tube furnace under an inert gas N2 atmosphere for 2 h, and then naturally cool to room temperature to obtain a carbon molecular sieve membrane; (3) Post-processing of carbon molecular sieve membrane: place the carbon molecular sieve membrane in solution D, constant stirring, soak for a certain time, take out the carbon molecular sieve membrane and then dry it under vacuum; Solution D is one or more than two kinds of sodium hypochlorite, potassium persulfate, sodium persulfate and potassium permanganate.
2. The modification method according to claim 1, characterized in that, The polymer A is one of Troger base-based polymer, 6FDA-DAM, 6FDA-DAM-DABA, Matrimid and P84 polymer.
3. The modification method of claim 1, wherein, The solvent B is one of chloroform, N-methyl pyrrolidone and N,N-dimethylformamide.
4. The modification method of claim 1, wherein, In step (1), the mass fraction of the casting solution is 2%-20%.
5. The modification method of claim 1, wherein, In step (1), the time for sufficient stirring is 12-24 h.
6. The modification method of claim 1, wherein, In step (1), the solvent volatilization temperature is 25-80 DEG C.
7. The modification method of claim 1, wherein In step (3), the concentration of solution D is 50-800 ppm.
8. The modification method of claim 1, wherein, In step (3), the stirring rate is 100-1000 r / min.
9. The modification method of claim 1, wherein, In step (3), the soaking time is 12-48 h.
Citation Information
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