Zeolite membrane for efficient separation of co2 and preparation method and application thereof

Abstract

The application discloses a zeolite membrane for efficient separation of CO2 and a preparation method and application thereof. The zeolite membrane is prepared by encapsulating organic guest molecules (or ions) in the channels of the zeolite membrane, and then further regulating the structure and content of the organic guest molecules to obtain the zeolite membrane. Since the residual organic guest molecules have strong interaction with CO2, the diffusion rate of CO2 in the zeolite membrane is greatly reduced, and finally the efficient separation between CO2 and other gas mixtures can be realized. Compared with the conventional zeolite membrane, the zeolite membrane can be used for the separation of CO2 in various different mixture systems, and the application field is very wide, and the adaptability is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of membrane separation technology, specifically relating to a zeolite membrane for efficient CO2 separation, its preparation method, and its application. Background Technology

[0002] Zeolite molecular sieves, with their uniform molecular-level pores and excellent chemical and thermal stability, are considered ideal membrane separation materials and are currently widely used for the efficient separation of various mixture systems. Among them, small-pore zeolite molecular sieve membranes (such as SAPO-34, SSZ-13, and DDR) have been extensively studied for CO2 separation, particularly exhibiting excellent separation performance in CO2 / CH4 mixtures, with CO2 permeability reaching 10⁻⁶. -7 -10 -6 mol Pa -1 m -2 s -1 The separation selectivity of CO2 / CH4 can reach over 100. This is mainly due to two factors: firstly, CH4 molecules are significantly larger than CO2 molecules, resulting in a significantly slower diffusion rate within the membrane; secondly, the preferential adsorption of CO2 by the zeolite membrane plays a crucial role in its excellent separation performance. The aforementioned small-pore zeolite molecular sieve membranes show promising application prospects in the natural gas industry.

[0003] For CO2 / CH4 mixtures with high CO2 concentrations, such as landfill gases where CO2 concentrations can exceed 60%, the large throughput required for CO2 separation necessitates a large membrane area for traditional CO2-preferential zeolite molecular sieve membranes, leading to high production costs. Furthermore, for small molecule mixtures like H2 / CO2, such as the separation of H2 from methane steam reforming hydrogen production products, the selectivity of zeolite molecular sieve membranes for H2 / CO2 separation is typically low due to the significantly smaller molecular sizes of both H2 and CO2 compared to the pore size of the membrane, making them unsuitable for this system. Therefore, developing novel zeolite molecular sieve CO2 separation membranes is of great significance in further improving the applicability of zeolite molecular sieve membranes for separating CO2-containing gas mixtures.

[0004] Altering the interaction between the membrane material and CO2 can significantly affect the CO2 permeation characteristics. Boffa et al. (ChemSusChem, 2008, 1, 437-443) prepared Nb-doped silica membranes. Although the molecular size of CO2 is relatively small compared to molecules such as N2, its permeability is still much lower than that of N2 molecules. This is mainly due to the strong interaction between the membrane and CO2 molecules, resulting in an extremely low CO2 diffusion rate. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the purpose of this invention is to introduce specific guest molecules (or ions) into the pores of zeolite molecular sieves, thereby enhancing the interaction between the membrane and CO2 molecules, and thus selectively and significantly reducing the diffusion rate of CO2 in the membrane, ultimately obtaining a novel zeolite molecular sieve membrane for efficient CO2 separation.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows.

[0007] A method for preparing a zeolite membrane for efficient CO2 separation includes the following steps:

[0008] (1) Introducing organic guest molecules or ions into the pores of a zeolite molecular sieve membrane; wherein the organic guest molecules or ions are substances that have strong interactions with CO2 molecules.

[0009] (2) The structure and content of organic guest molecules or ions in the pores of zeolite molecular sieve membrane are subjected to secondary regulation; the secondary regulation method is slow decomposition by low temperature heating or decomposition by ultraviolet radiation.

[0010] Preferably, in step (1), the zeolite molecular sieve membrane is one or more of the following types: MFI, CHA, LTA, DDR, FAU, MOR, and BEA.

[0011] Preferably, the substance that has a strong interaction with CO2 molecules is one or more of organic amines and quaternary ammonium bases.

[0012] Preferably, the organic amine is one or more combinations of monomethylamine, dimethylamine, trimethylamine, monoethylamine, monopropylamine, dipropylamine, tripropylamine, diethylamine, triethylamine, isopropylamine, diisopropylamine, cyclopropylamine, n-butylamine, di-n-butylamine, isobutylamine, sec-butylamine, ethylenediamine, 1,2-propanediamine, and 1,4-butanediamine.

[0013] Preferably, the quaternary ammonium base has the general structural formula 3RN. + OH - , where R is an alkyl group.

[0014] Preferably, R is methyl, ethyl, propyl or butyl; the selected quaternary ammonium base is one or more of these.

[0015] Preferably, the organic guest molecule or ion is a template agent for the zeolite molecular sieve membrane described in step (1), or a combination of a template agent and other organic amines and quaternary ammonium bases.

[0016] Preferably, in step (1), the organic guest molecules or ions are introduced into the pores of the zeolite molecular sieve membrane by adding organic guest molecules or ions to the zeolite molecular sieve membrane synthesis solution and then performing hydrothermal crystallization to directly encapsulate them into the zeolite molecular sieve membrane.

[0017] Preferably, the temperature for slow decomposition by low-temperature heating is 200-350℃, and the decomposition time is 20-200h.

[0018] Further preferred low-temperature heating and slow decomposition temperature is 300-350℃, and decomposition time is 12-36h.

[0019] Preferably, the atmosphere used for the slow decomposition by low-temperature heating is one of air, oxygen, hydrogen, or ozone.

[0020] Preferably, the ultraviolet radiation decomposition time is 20-500 hours, and the decomposition temperature is less than 100°C.

[0021] The preferred radiation intensity is 3768-5623 μW cm⁻¹. -2 The radiation duration is 70-133 hours.

[0022] Zeolite membranes prepared by any of the above preparation methods.

[0023] The zeolite membrane described above is used for the separation of CO2 in a gas mixture. The CO2 gas separation test temperature is not higher than 350℃.

[0024] Preferably, the CO2 gas separation test temperature is not higher than 200℃.

[0025] This invention introduces molecules that strongly interact with CO2 into the pores of a boiling molecular sieve membrane, thereby controlling the permeation characteristics of CO2 in the membrane and achieving efficient separation of CO2 in different specific mixture systems.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] This invention provides a novel zeolite molecular sieve membrane for highly efficient CO2 separation. By introducing specific organic guest molecules into the pores, the interaction between these molecules and CO2 molecules significantly reduces the diffusion rate of CO2 within the membrane, thereby ultimately achieving efficient separation of other gas components from CO2. Compared to traditional zeolite molecular sieve CO2 separation membranes, the novel zeolite molecular sieve CO2 separation membrane provided by this invention exhibits high selectivity and strong adaptability to mixtures of different types of gases and CO2, greatly expanding the application range of the membrane. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the invention is not limited thereto. For process parameters not specifically noted, conventional techniques can be referred to.

[0029] Example 1

[0030] Prepare a 0.1 wt% SSZ-13 seed solution and sonicate for 1 hour to ensure uniform seed dispersion. Take 1 ml of the above seed solution and deposit the seed crystals onto an α-Al₂O₃ sheet support using vacuum filtration. After drying, calcine at 550℃ for 6 hours to obtain an SSZ-13 seed layer on the α-Al₂O₃ sheet support. Add 0.2062 g NaOH and 0.0975 g Al(OH)₃ sequentially to 11.2243 g deionized water and stir evenly at room temperature. Then, slowly add 8.4537 g TMAdaOH (N,N,N-trimethyl-1-adamantyl ammonium hydroxide) solution and continue stirring at room temperature for 1 hour. Then, add 3.755 g silica sol and stir and age at room temperature for 12 hours to obtain a membrane synthesis solution with a ratio of 1 SiO₂:0.1 Na₂O:0.025 Al₂O₃:0.4 TMAdaOH:44 H₂O. An α-Al₂O₃ sheet-like support pre-coated with an SSZ-13 seed layer was vertically placed into a stainless steel reactor lined with Teflon. The membrane synthesis solution was poured in, and the reactor was sealed. After crystallization at 160℃ for 96 hours, the α-Al₂O₃ ceramic sheet was removed, washed with deionized water until neutral, and dried at 115℃ for 12 hours to obtain the SSZ-13 zeolite membrane. The prepared SSZ-13 zeolite molecular sieve membrane was placed in a tube furnace and heated from room temperature to 350℃ at a heating rate of 1℃ / min under a nitrogen atmosphere. Hydrogen gas was then introduced at a flow rate of 20 ml / min and maintained for 20 hours. The temperature was then reduced to room temperature at a cooling rate of 1℃ / min. The SSZ-13 zeolite molecular sieve membrane was used for H₂ and CO₂ permeation tests. The feed-side and permeation-side pressures were 0.2 MPa and 0.1 MPa, respectively. The H₂ permeability measured at room temperature was 2.8 × 10⁻⁶. -8 mol·m -2 ·s -1 ·Pa -1 The CO2 permeability is 7.9 × 10⁻⁶. -10 mol·m -2 ·s -1 ·Pa -1 The ideal separation selectivity for H2 / CO2 is 35.5.

[0031] Example 2

[0032] Prepare a 0.1 wt% SSZ-13 seed solution and sonicate for 1 hour to ensure uniform seed dispersion. Take 1 ml of the above seed solution and deposit the seed crystals onto an α-Al₂O₃ sheet support using vacuum filtration. After drying, calcine at 650℃ for 6 hours to obtain an SSZ-13 seed layer on the α-Al₂O₃ sheet support. Add 0.5668 g TEAOH (tetraethylammonium hydroxide), 2.3128 g TMAdaOH, 0.1401 g NaOH, and 0.0294 g Al(OH)₃ sequentially to 23.6026 g of deionized water and stir at room temperature for 1 hour. Then add 2.1028 g of silica sol dropwise and stir and age at 50℃ for 24 hours to obtain a membrane synthesis solution with the following ratio: 1.45 TMAdaOH: 0.51 TEAOH: 7.42 SiO₂: 1.8 NaOH: 0.2 Al(OH)₃: 795 H₂O. An α-Al₂O₃ sheet-like support pre-coated with an SSZ-13 seed layer was vertically placed into a stainless steel reactor lined with Teflon. The membrane synthesis solution was poured in, and the reactor was sealed. After crystallization at 160℃ for 48 hours, the α-Al₂O₃ ceramic sheet was removed, washed with deionized water until neutral, and dried at 115℃ for 12 hours to obtain the SSZ-13 zeolite membrane. The prepared SSZ-13 zeolite molecular sieve membrane was placed in a tube furnace and heated from room temperature to 350℃ at a heating rate of 1℃ / min under an argon atmosphere. Hydrogen gas was then introduced at a flow rate of 40 ml / min and maintained for 36 hours. The temperature was then reduced to room temperature at a cooling rate of 1℃ / min. The SSZ-13 zeolite molecular sieve membrane was used for H₂ and CO₂ permeation tests. The feed-side and permeation-side pressures were 0.2 MPa and 0.1 MPa, respectively. The H₂ permeability measured at room temperature was 8.3 × 10⁻⁶. -9 mol·m -2 ·s -1 ·Pa -1 The CO2 permeability is 5.0 × 10⁻⁶. - 10 mol·m -2 ·s -1 ·Pa -1 The ideal separation selectivity for H2 / CO2 is 16.5.

[0033] Example 3

[0034] Prepare a 0.3 wt% pure silicon CHA seed solution and sonicate for 1 hour to disperse the seeds evenly. Take 1 ml of the above seed solution and deposit the seeds onto an α-Al₂O₃ sheet support using vacuum filtration. After drying, calcine at 650℃ for 6 hours to obtain a pure silicon CHA seed layer on the α-Al₂O₃ sheet support. Add 82.8467 g TMAdaOH and 14.8805 g TEOS (tetraethyl orthosilicate) sequentially to a polytetrafluoroethylene beaker. Stir at room temperature for 24 hours. After mixing evenly, dry at 60℃ to obtain a white solid, which is then crushed into powder. Add a small amount of deionized water and 4.9 g HF and stir evenly. Continue stirring at 60℃ for 6 hours to obtain a membrane synthesis solution with a ratio of 1.0 SiO₂:1.4 TMAdaOH:1.4 HF:9.4 H₂O. An α-Al₂O₃ sheet-like support pre-coated with a pure silicon CHA seed layer was vertically placed into a stainless steel reactor lined with Teflon. The membrane synthesis solution was poured in, and the reactor was sealed. After crystallization at 160℃ for 18 hours, the α-Al₂O₃ ceramic sheet was removed, washed with deionized water until neutral, and dried at 115℃ for 12 hours to obtain a pure silicon CHA zeolite membrane. The prepared pure silicon CHA zeolite molecular sieve membrane was placed in a tube furnace and heated from room temperature to 350℃ at a heating rate of 1℃ / min under an argon atmosphere. Hydrogen gas was then introduced at a flow rate of 30 ml / min and maintained for 24 hours. The temperature was then reduced to room temperature at a cooling rate of 1℃ / min. The pure silicon CHA zeolite molecular sieve membrane was used for H₂ and CO₂ permeation tests, with feed-side and permeation-side pressures of 0.2 MPa and 0.1 MPa, respectively. The H₂ permeability at room temperature was 1.5 × 10⁻⁶. -8 mol·m -2 ·s -1 ·Pa -1 The CO2 permeability is 6.6 × 10⁻⁶. -10 mol·m -2 ·s -1 ·Pa -1 The ideal separation selectivity for H2 / CO2 is 22.6.

[0035] Example 4

[0036] Prepare a 0.05 wt% SAPO-34 seed solution and sonicate for 3 hours to ensure uniform seed dispersion. Take 1 ml of the above seed solution and deposit the seed crystals onto an α-Al₂O₃ sheet support using vacuum filtration. After drying, calcine at 550℃ for 6 hours to obtain a SAPO-34 seed layer on the α-Al₂O₃ sheet support. Add 2.2 g of phosphoric acid and 4.5617 g of aluminum isopropoxide sequentially to 24.5694 g of deionized water and stir at room temperature for 3 hours. Then, add 0.4957 g of silica sol and 6.4794 g of TEAOH solution dropwise and stir for 1 hour. Finally, add 1.8173 g of DPA (di-n-propylammonium) and stir for 3 hours to obtain a membrane synthesis solution with a ratio of 1.0 Al₂O₃:1.0 P₂O₅:0.3 SiO₂:1.0 TEAOH:1.6 DPA:150 H₂O. An α-Al₂O₃ sheet-like support pre-coated with a SAPO-34 seed layer was vertically placed into a stainless steel reactor lined with Teflon. The membrane synthesis solution was poured in, and the reactor was sealed. After crystallization at 200℃ for 24 hours, the α-Al₂O₃ ceramic sheet was removed, washed with deionized water until neutral, and dried at 115℃ for 12 hours to obtain a SAPO-34 zeolite membrane. The prepared SAPO-34 zeolite molecular sieve membrane was placed in a tube furnace and heated from room temperature to 300℃ at a heating rate of 1℃ / min under a nitrogen atmosphere. Hydrogen gas was then introduced at a flow rate of 20 ml / min and maintained for 24 hours. The temperature was then reduced to room temperature at a cooling rate of 1℃ / min. The SAPO-34 zeolite molecular sieve membrane was used for H₂ and CO₂ permeation tests. The feed-side and permeation-side pressures were 0.2 MPa and 0.1 MPa, respectively. The H₂ permeability was measured to be 2.5 × 10⁻⁶ at room temperature. -8 mol·m -2 ·s -1 ·Pa -1 The CO2 permeability is 1.0 × 10⁻⁶. - 9 mol·m -2 ·s -1 ·Pa -1 The ideal separation selectivity for H2 / CO2 is 24.4.

[0037] Example 5

[0038] The steps for preparing the SAPO-34 zeolite membrane were the same as in Example 4. At room temperature, the prepared SAPO-34 zeolite molecular sieve membrane was irradiated under a UV lamp, with the zeolite membrane surface 5 cm from the UV lamp surface, and the radiation intensity was 5623 μW / cm². -2 The irradiation time was 70 hours. The SAPO-34 zeolite molecular sieve membrane was used for CO2 and CH4 permeation tests, with feed-side and permeation-side pressures of 0.2 MPa and 0.1 MPa, respectively. The CO2 permeability measured at room temperature was 2.9 × 10⁻⁶. -9 mol·m-2 ·s -1 ·Pa -1 The permeability of CH4 is 5.7 × 10⁻⁶. -8 mol·m -2 ·s -1 ·Pa -1 The ideal separation selectivity for CH4 / CO2 is 19.6.

[0039] Example 6

[0040] The steps for preparing the SAPO-34 zeolite membrane were the same as in Example 4. The prepared SAPO-34 zeolite molecular sieve membrane was placed under a UV lamp for irradiation, with the zeolite membrane surface 2.5 cm from the UV lamp surface, and the radiation intensity was 3768 μW / cm². -2 The irradiation time was 133 h. The SAPO-34 zeolite molecular sieve membrane was used for H2 and CO2 permeation tests, with feed-side and permeation-side pressures of 0.2 MPa and 0.1 MPa, respectively. The H2 permeability measured at room temperature was 8.4 × 10⁻⁶. -8 mol·m -2 ·s -1 ·Pa -1 The CO2 permeability is 1.6 × 10⁻⁶. -9 mol·m -2 ·s -1 ·Pa -1 The ideal separation selectivity for H2 / CO2 is 51.8.

[0041] Example 7

[0042] Prepare a 0.1 wt% pure silicon MFI seed solution and sonicate for 1 hour to ensure uniform seed dispersion. Take 1 ml of the above seed solution and deposit the seeds onto an α-Al₂O₃ sheet support using vacuum filtration. After drying, calcine at 550℃ for 6 hours to obtain a pure silicon MFI seed layer on the α-Al₂O₃ sheet support. Mix 1.0209 g TPAOH (tetrapropylammonium hydroxide) with 24.4567 g deionized water, then slowly add 2.9761 g TEOS and stir overnight at room temperature to obtain a membrane synthesis solution with a ratio of 0.2 TPAOH:1.0 TEOS:100 H₂O. An α-Al₂O₃ sheet-like support pre-coated with a pure silicon MFI seed layer was vertically placed into a stainless steel reactor lined with Teflon. The membrane synthesis solution was poured in, and the reactor was sealed. After crystallization at 150℃ for 24 hours, the α-Al₂O₃ ceramic sheet was removed, washed with deionized water until neutral, and dried at 115℃ for 12 hours to obtain a pure silicon MFI zeolite membrane. The prepared pure silicon MFI zeolite molecular sieve membrane was placed in a tube furnace and heated from room temperature to 310℃ at a heating rate of 1℃ / min under an argon atmosphere. Hydrogen gas was then introduced at a flow rate of 30 ml / min and maintained for 12 hours. The temperature was then reduced to room temperature at a cooling rate of 1℃ / min. The pure silicon MFI zeolite molecular sieve membrane was used for H₂ and CO₂ permeation tests, with feed-side and permeation-side pressures of 0.2 MPa and 0.1 MPa, respectively. The H₂ permeability measured at room temperature was 9.2 × 10⁻⁶. -9 mol·m -2 ·s -1 ·Pa -1 The CO2 permeability is 4.3 × 10⁻⁶. -10 mol·m -2 ·s -1 ·Pa -1 The ideal separation selectivity for H2 / CO2 is 21.4.

[0043] Example 8

[0044] The preparation steps for the SSZ-13 zeolite membrane were the same as in Example 1. The SSZ-13 zeolite molecular sieve membrane was used for H2 and CO2 permeation tests, with feed-side and permeation-side pressures of 0.2 MPa and 0.1 MPa, respectively. The H2 permeability was measured to be 8.2 × 10⁻⁶ at 250 °C. -8 mol·m -2 ·s -1 ·Pa -1 The CO2 permeability is 1.1 × 10⁻⁶. -9 mol·m -2 ·s -1 ·Pa -1 The ideal separation selectivity for H2 / CO2 is 74.5.

Claims

1. A method for preparing a zeolite membrane for efficient CO2 separation, characterized in that, Includes the following steps: (1) Introducing organic guest molecules or ions into the pores of a zeolite molecular sieve membrane; wherein the organic guest molecules or ions are substances that have strong interactions with CO2 molecules; (2) The structure and content of organic guest molecules or ions in the pores of zeolite molecular sieve membrane are subjected to secondary regulation; the secondary regulation method is slow decomposition by low temperature heating or decomposition by ultraviolet radiation.

2. The preparation method according to claim 1, characterized in that, In step (1), the zeolite molecular sieve membrane is one or more of the following types: MFI, CHA, LTA, DDR, FAU, MOR, and BEA; the substance that has a strong interaction with CO2 molecules is one or more of the following types: organic amines and quaternary ammonium bases.

3. The preparation method according to claim 1, characterized in that, In step (1), the organic guest molecules or ions are introduced into the pores of the zeolite molecular sieve membrane by adding organic guest molecules or ions to the zeolite molecular sieve membrane synthesis solution and then directly encapsulating them into the zeolite molecular sieve membrane through hydrothermal crystallization.

4. The preparation method according to claim 1, characterized in that, The low-temperature heating slow decomposition temperature is 200-350℃, and the decomposition time is 20-200h; the atmosphere used for the low-temperature heating slow decomposition is one of air, oxygen, hydrogen, and ozone; the ultraviolet radiation decomposition time is 20-500h, and the decomposition temperature is less than 100℃.

5. A zeolite membrane prepared by any one of claims 1-4.

6. The zeolite membrane of claim 5 is used for the separation of CO2 in a gas mixture, characterized in that, The CO2 gas separation test temperature should not exceed 350℃.

7. The zeolite membrane according to claim 6 for the separation of CO2 in a gas mixture, characterized in that, The CO2 gas separation test temperature shall not exceed 200℃.