Separation membrane based on ZSM-12 molecular sieve, preparation method, application and reaction separation device using separation membrane

Abstract

The invention belongs to the technical field of gas membrane separation technologies and catalytic materials, and particularly relates to a ZSM-12 molecular sieve-based separation membrane, a preparation method and application thereof, and a reaction separation device using the separation membrane. The preparation method comprises the following steps: mixing and stirring a PEI polymer solution and a ZSM-12 molecular sieve to obtain a ZSM-12PEI membrane casting solution, scraping the ZSM-12PEI membrane casting solution on a glass plate pasted with a base membrane at a constant speed by using a 200 [mu] m scraper, and then drying in a constant-temperature and constant-humidity chamber at the temperature of 30 DEG C and the humidity of 40RH for 24 hours. The reaction separation device disclosed by the invention is designed in a manner that four stages of chambers are connected in series, so that the CO purity can be purified to 99% through step-by-step enrichment. CO is timely separated to avoid secondary oxidation, and the utilization rate of the catalyst is greatly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of gas membrane separation and catalytic materials, and particularly relates to a separation membrane based on ZSM-12 molecular sieve, a preparation method, application and a reaction separation device using the separation membrane. BACKGROUND

[0002] Photocatalysis refers to a process of using light energy to excite semiconductor materials to generate electron-hole pairs to drive redox reactions. This technology is widely used in environmental governance (such as pollutant degradation), energy conversion (such as CO2 reduction, water splitting to produce hydrogen) and organic synthesis, and has the characteristics of high efficiency, safety and environmental protection. Photocatalytic reduction of carbon dioxide refers to a process of converting carbon dioxide into carbon-based fuels (such as CO, CH4, CH3OH, etc.) and oxygen (O2) using semiconductor materials under light conditions.

[0003] The core challenge of current photocatalytic CO2 reduction technology is the difficulty of separating the mixed gas of CO and O2 generated by photocatalytic reaction. Traditional low-temperature distillation, adsorption method and other separation processes have high energy consumption (more than 30% of the total energy consumption of the system), and are prone to cause secondary oxidation of CO, reducing the yield of products. The selectivity of existing polymer membranes (such as polyimide) to CO / O2 is generally low, which cannot meet the purification demand of high-purity CO. In addition, the existing carbon dioxide photocatalytic reaction device mostly adopts a series mode of "reactor + independent separation unit", which leads to a complex system and energy consumption stacking. It is urgent to develop an integrated device that can simultaneously realize reaction-separation-purification integration to break through the bottleneck of technical economy.

[0004] Gas membrane separation technology is a technology that uses the permeation performance and selective separation performance of membrane materials to different gas molecules under the driving of pressure difference, so that different gases are enriched on both sides of the membrane to realize separation. Although zeolite molecular sieve membrane has a regular pore structure, its rigid skeleton is easy to form grain boundary defects, resulting in a decrease in gas selectivity. ZSM-12 molecular sieve has MTW topology, but pure molecular sieve membrane is brittle and difficult to be prepared on a large scale. SUMMARY

[0005] In view of the problems in the prior art, the application provides a separation membrane based on ZSM-12 molecular sieve, a preparation method, application and a reaction separation device using the separation membrane.

[0006] The application is realized by the following technical solutions: A preparation method of a separation membrane based on ZSM-12 molecular sieve, comprising the following steps: The PEI polymer solution and ZSM-12 molecular sieve are mixed and stirred to obtain a ZSM-12\PEI casting solution, the ZSM-12\PEI casting solution is uniformly scraped on a glass plate with a well-fixed base film using a 200 μm doctor blade, and then dried in a constant temperature and humidity box at a temperature of 30 ℃ and a humidity of 40 RH for 24 hours.

[0007] Further, the mass ratio of the ZSM-12 molecular sieve to the PEI polymer is 2:5.

[0008] Further, the PEI polymer solution is prepared by mixing and stirring 1 g of PEI powder and 19 g of H2O.

[0009] Further, the preparation method of the ZSM-12 molecular sieve comprises the following steps: sodium aluminate (54% Al2O3: 41% Na2O: 5% H2O) and 40% wt of tetraethylammonium hydroxide (TEAOH) are uniformly stirred in distilled water, then colloidal silicon dioxide (Ludox® HS-30, 30% wt) is added, the mixture is continuously stirred for 15 minutes, then transferred to an autoclave, kept in a preheated oven at 160 ℃ for 6 days, the obtained solid is separated by filtration, washed with distilled water until the pH value is 7, and dried at 80 °C for 12 hours.

[0010] Further, the molar ratio of sodium aluminate, TEAOH, silicon dioxide and distilled water is 3.2:80:12.7:1040.

[0011] The second object of the present application is to provide a separation membrane based on the ZSM-12 molecular sieve prepared by the above preparation method.

[0012] The third object of the present application is to provide the application of the separation membrane of the ZSM-12 molecular sieve in CO\O2 separation.

[0013] The fourth object of the present application is to provide a gas-solid-liquid membrane separation device using the separation membrane based on the ZSM-12 molecular sieve, comprising a first shell, a second shell, a third shell and a fourth shell, the second shell is located below the first shell, the third shell is located below the second shell, the fourth shell is located below the third shell, and the separation membrane based on the ZSM-12 molecular sieve is placed between adjacent shells; the first shell, the second shell, the third shell and the fourth shell are all hollow chambers, the hollow chambers are communicated and have the same diameter; one side of the first shell is provided with a gas outlet, and one side of the fourth shell is provided with a gas inlet.

[0014] Further, the top of the first shell is a closed structure, and the inside is a hollow chamber, the bottom of the first shell is provided with a circular groove, and a rubber sealing ring is placed in the circular groove. The second shell is open at both ends, and the inside is a hollow chamber; the bottom of the second shell is provided with a circular groove, and a rubber sealing ring is placed in the circular groove; The third shell is located below the second shell, and is open at both ends, and the inside is a hollow chamber; the bottom of the third shell is provided with a circular groove, and a rubber sealing ring is placed in the circular groove; The fourth shell is located below the third shell, and the bottom of the fourth shell is a closed structure, and the inside is a hollow chamber; one side of the fourth shell is provided with an air inlet; the hollow chamber of the fourth shell is filled with water accounting for 1 / 2 to 2 / 3 of the total volume; one side of the fourth shell is provided with an opening, and the opening is bonded with quartz glass by using epoxy resin.

[0015] Further, a cooler is further included, the inside of the cooler is hollow, one side of the cooler is provided with a water inlet, and the other side is provided with a water outlet, the water inlet and the water outlet have a height difference, the outer wall of the water inlet and the water outlet is designed with threads, and the fourth shell is placed in the hollow chamber of the cooler; the diameter of the vacuum chamber of the cooler is greater than the diameter of the outer wall of the fourth shell, so that there is a gap between the inner wall of the cooler and the outer wall of the fourth shell for placing condensed water.

[0016] The application also provides application of the gas-solid-liquid membrane separation device in a CO2 photocatalytic reaction.

[0017] The beneficial technical effects of the application are as follows: (1) The ZSM-12 / PEI mixed matrix membrane of the application combines the sieving effect of the molecular sieve and the compactness of PEI, so that the separation selectivity of CO / O2 is greatly improved compared with pure PEI membrane.

[0018] (2) The PEI polymer coated molecular sieve particles can effectively fill the grain boundary defects and strengthen the mechanical strength, so that a better membrane flux is maintained.

[0019] (3) The reaction separation device of the application is designed in a four-stage chamber series connection mode, so that the CO purity can be purified to 99% through step-by-step enrichment. The CO is separated in time to avoid secondary oxidation, and the utilization rate of the catalyst is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is an FT-IR graph of ZSM-12; Figure 2 It is an FT-IR graph of PEI\ZSM-12 mixed matrix membrane; Figure 3 It is an XRD graph of ZSM-12; Figure 4 It is an XRD graph of PEI\ZSM-12 mixed matrix membrane; Figure 5SEM image of ZSM-12; Figure 6 SEM image of ZSM-12; Figure 7 SEM image of PEI\ZSM-12 mixed matrix membrane; Figure 8 SEM image of PEI\ZSM-12 mixed matrix membrane; Figure 9 Structure diagram of gas-solid-liquid membrane separation device; Figure 10 Structure diagram of gas-solid-liquid membrane separation device; Figure 11 Structure diagram of first shell; Figure 12 Structure diagram of first shell; Figure 13 Structure diagram of second shell; Figure 14 Structure diagram of second shell; Figure 15 Structure diagram of fourth shell; Figure 16 Structure diagram of fourth shell; Figure 17 Illustration of selectivity of mixed matrix membrane to carbon monoxide and oxygen.

[0021] Reference signs: 1 - first shell, 2 - second shell, 3 - third shell, 4 - fourth shell, 5 - gas inlet, 6 - gas outlet, 7 - cooler, 8 - water inlet, 9 - water outlet, 10 - round groove, 11 - separation membrane, 12 - rubber sealing ring, 13 - quartz glass. DETAILED DESCRIPTION

[0022] The application will be further described below with reference to the accompanying drawings.

[0023] Example 1 Synthesis of ZSM-12 molecular sieve Synthesis of ZSM-12 molecular sieve by one-step method, using tetraethylammonium hydroxide (TEAOH, 40%wt) as structure template, mixing colloidal silica (Ludox® HS-30, 30%wt), sodium aluminate (54% Al2O3: 41% Na2O: 5% H2O) and distilled water in the following molar ratio: xAl2O3: 80 SiO2: 12.7 TEAOH: 1040 H2O, where x is 3.2 respectively. After the sodium aluminate and TEAOH were dissolved in distilled water and stirred uniformly, colloidal silica was added. The mixture was continuously stirred for 15 minutes and then transferred to an autoclave, which was kept in an oven preheated to 160°C for 6 days. The obtained solid was separated by filtration, washed with distilled water (to pH 7) and dried at 80°C for 12 hours.

[0024] The ZSM-12 molecular sieve prepared in Example 1 was characterized by scanning electron microscopy, and the results are shown in Figure 5 and Figure 6 , indicating that the molecular sieve specifically presents a rod shape.

[0025] The ZSM-12 molecular sieve prepared in Example 1 was characterized by infrared spectroscopy, and the results are shown in Figure 1 , indicating that the strong absorption peak in the low wave number region (1200-500 cm⁻¹) confirms the integrity of the ZSM-12 aluminosilicate framework, and no structural collapse occurs. No C-H peak (~2900 cm⁻¹) indicates that the organic template has been completely removed, which meets the standard of high-purity zeolite.

[0026] The ZSM-12 molecular sieve prepared in Example 1 was characterized by XRD, and the results are shown in Figure 3 , indicating that ZSM-12 is a zeolite with MTW topology, and there is a strong peak near 20.7°. The ZSM-12 shown in the XRD pattern meets the characteristics.

[0027] Example 2 Synthesis of mixed matrix membrane A PEI polymer solution was prepared by mixing and stirring 1 g of PEI powder and 19 g of H2O, and a ZSM-12\PEI casting solution was prepared by mixing and stirring 120 mg of ZSM-12 molecular sieve and 6 g of PEI polymer solution. The mass ratio of ZSM-12 molecular sieve to PEI polymer was 2:5, and a casting solution with a ZSM-12 molecular sieve content of 40% PEI polymer was prepared.

[0028] The ZSM-12\PEI casting solution was uniformly scraped on the glass plate with the base film using a 200-micron scraper, and the obtained sample was dried in a constant temperature and humidity box at a temperature of 30°C and a humidity of 40 RH for one day.

[0029] The obtained mixed matrix membrane was characterized by scanning electron microscopy, and the results are shown in Figure 7 andFigure 8 The combination state of polymer and molecular sieve is clearly shown in the image, indicating that the polymer and molecular sieve are successfully loaded on the surface of the base film.

[0030] The obtained mixed matrix membrane was characterized by FT-IR, and the results are shown in Figure 2 , indicating that the strong peak near 1720 - 1780 cm⁻¹ is the key characteristic peak of PEI. Polyetherimide contains imide rings, and the carbonyl group (C=O) produces a strong absorption peak in this region.

[0031] The obtained mixed matrix membrane was characterized by XRD, and the results are shown in Figure 4 , indicating that there is a broad peak between 15° - 20°, which is a typical characteristic of amorphous polyetherimide (PEI), confirming the presence of the polymer matrix. On the background of the amorphous broad peak, a series of sharp, narrow diffraction peaks can be observed, corresponding to the XRD pattern of ZSM-12, confirming that the ZSM-5 zeolite particles are successfully incorporated into the PEI membrane.

[0032] Example 3 Separation test of carbon monoxide (CO) and oxygen (O2) for mixed matrix membrane The mixed matrix membrane prepared in Example 2 was used for the separation of carbon monoxide (CO) and oxygen (O2), and the results are shown in Figure 17 , the selectivity of the mixed matrix membrane for carbon monoxide and oxygen is about 2.5, while the pure PEI polymer under the same conditions has no separation performance for carbon monoxide and oxygen.

[0033] Example 4 Referring to Figures 9-10 A gas-solid-liquid membrane catalytic reaction device for separating reactants and products and purification, comprising a first shell, a second shell, a third shell, and a fourth shell, the top of the first shell is a closed structure, and the inside is a hollow chamber; one side of the first shell is provided with an air outlet; the bottom of the first shell is provided with a circular groove; a rubber sealing ring is placed in the circular groove; the second shell is located below the first shell, and the inside is a hollow chamber; the third shell is located below the second shell; the structure of the third shell is consistent with that of the second shell; the fourth shell is located below the third shell; the bottom of the fourth shell is a closed structure, and the inside is a hollow chamber; one side of the fourth shell is provided with an air inlet; the hollow chamber of the fourth shell is filled with water accounting for 1 / 2 to 2 / 3 of the total volume.

[0034] The first shell and the second shell, the second shell and the third shell, and the third shell and the fourth shell are placed with a matrix membrane and sealed by a rubber sealing ring. Multiple membranes can be effectively used for the separation and purification of generated gas.

[0035] Referring to Figures 11-16The hollow chambers of the first shell, the second shell, the third shell and the fourth shell are communicated and have the same diameter. The first shell comprises a cylinder and a lower base, the cylinder and the lower base are integrally formed, the circular groove is arranged on the lower surface of the lower base, and the air outlet is arranged on one side of the cylinder. The second shell comprises a cylinder, an upper base and a lower base, the cylinder, the upper base and the lower base are integrally formed, the circular groove is arranged on the lower surface of the lower base, and the third shell has the same structure as the second shell. The fourth shell comprises a cylinder and an upper base, the cylinder and the upper base are integrally formed, and the air inlet is arranged on one side of the cylinder. The other side of the fourth shell is provided with an opening, and the opening is bonded with quartz glass by using epoxy resin.

[0036] The lower base of the first shell, the upper base of the second shell, the lower base of the second shell and the upper base of the third shell, the lower base of the third shell and the upper base of the fourth shell are clamped and fixed by a clamp.

[0037] The gas-solid-liquid membrane catalytic reaction device for separating reactants and products and purification further comprises a cooler, the inside of the cooler is hollow, one side of the cooler is provided with a water inlet, the other side is provided with a water outlet, the water inlet and the water outlet have a height difference, the outer walls of the water inlet and the water outlet are designed with threads, and the fourth shell is placed in the hollow chamber of the cooler; the diameter of the vacuum chamber of the cooler is greater than the diameter of the outer wall of the fourth shell, so that there is a gap between the inner wall of the cooler and the outer wall of the fourth shell for placing condensed water.

[0038] Example 5: Carbon dioxide photocatalytic reaction using the device Before the reaction starts, 1 / 2 to 2 / 3 of the total volume of water is filled into the hollow chamber of the fourth shell, and the shells are sequentially installed, connected and sealed; the vacuum pump is connected with the gas outlet of the first shell through the three-way valve; when the reaction starts, carbon dioxide reaction gas is introduced through the gas inlet on the fourth shell connected with the reaction gas bottle, the other side is subjected to light irradiation treatment using epoxy resin adhesive quartz glass, the whole device is placed on a magnetic stirrer, a magnetic sub is placed in the fourth shell, the magnetic stirrer is started, and the water and carbon dioxide in the chamber are subjected to photocatalytic reaction to obtain the required product; the vacuum pump is started to generate a pressure difference between the shells in the reactor and use it as a driving force; the mixed matrix membrane can separate the product gas carbon monoxide and oxygen generated by photocatalysis, and the pressure difference and concentration difference can make the product gas carbon monoxide pass through the multiple membranes to achieve the purpose of separation and purification. The purified pure carbon monoxide gas enters the connected product gas collection box through the gas outlet of the first shell, and the collected gas is detected by a gas chromatograph. In this embodiment, by selecting a multi-layer composite membrane and optimizing the operation parameters, high selectivity and high flux CO / O2 separation are realized. The output ratio of carbon monoxide to oxygen is about 2:1.

Claims

1. A method for the preparation of a separation membrane based on ZSM-12 molecular sieve, characterized by: The method comprises the following steps: The PEI polymer solution and ZSM-12 molecular sieve are mixed to obtain a ZSM-12\PEI casting solution, the ZSM-12\PEI casting solution is uniformly scraped on a glass plate with a 200 μm doctor blade, and then dried in a constant temperature and humidity box at a temperature of 30 °C and a humidity of 40 RH for 24 hours, wherein the mass ratio of ZSM-12 molecular sieve to PEI is 2:

5.

2. The method for producing a separation membrane based on a ZSM-12 molecular sieve according to claim 1, characterized by: The PEI polymer solution is prepared by mixing and stirring 1 g of PEI powder and 19 g of H2O.

3. The method of claim 1 for making a separation membrane based on a ZSM-12 molecular sieve, wherein: The preparation method of the ZSM-12 molecular sieve comprises the following steps: sodium aluminate (54% Al2O3: 41% Na2O: 5% H2O) and 40% wt of tetraethylammonium hydroxide (TEAOH) are uniformly stirred in distilled water, then colloidal silicon dioxide (Ludox® HS-30, 30% wt) is added, the mixture is continuously stirred for 15 minutes, then transferred to an autoclave, and kept in a preheated oven at 160 °C for 6 days, and the obtained solid is separated by filtration, washed with distilled water to pH 7, and dried at 80 °C for 12 hours.

4. The method of claim 3 for making a separation membrane based on a ZSM-12 molecular sieve, characterized by: The molar ratio of sodium aluminate, TEAOH, silicon dioxide and distilled water is 3.2:80:12.7:1040.

5. A ZSM-12 molecular sieve-based separation membrane prepared by the preparation method according to any one of claims 1-4.

6. The use of the ZSM-12 molecular sieve-based separation membrane according to claim 5 in CO\O2 separation.

7. A gas-solid-liquid membrane separation apparatus using a separation membrane based on a ZSM-12 molecular sieve, characterized by: The device comprises a first shell, a second shell, a third shell and a fourth shell, the second shell is below the first shell, the third shell is below the second shell, and the fourth shell is below the third shell, and a ZSM-12 molecular sieve-based separation membrane is arranged between adjacent shells; the first shell, the second shell, the third shell and the fourth shell are all hollow chambers, the hollow chambers are communicated and have the same diameter; one side of the first shell is provided with an air outlet, and one side of the fourth shell is provided with an air inlet.

8. The gas-solid-liquid membrane separation apparatus using a separation membrane based on a ZSM-12 molecular sieve according to claim 7, characterized by: The top of the first shell is a closed structure, and the inside is a hollow chamber; the bottom of the first shell is provided with a circular groove, and a rubber sealing ring is arranged in the circular groove; The second shell is an open structure at both ends, and the inside is a hollow chamber; the bottom of the second shell is provided with a circular groove, and a rubber sealing ring is arranged in the circular groove; The third shell is below the second shell, and is an open structure at both ends, and the inside is a hollow chamber; the bottom of the third shell is provided with a circular groove, and a rubber sealing ring is arranged in the circular groove; The fourth shell is below the third shell, and the bottom of the fourth shell is a closed structure, and the inside is a hollow chamber; one side of the fourth shell is provided with an air inlet; the hollow chamber of the fourth shell is filled with water accounting for 1 / 2 to 2 / 3 of the total volume; one side of the fourth shell is provided with an opening, and the opening is bonded with quartz glass by using epoxy resin.

9. The gas-solid-liquid membrane separation apparatus using a separation membrane based on ZSM-12 molecular sieves according to claim 7, characterized by: Also included is a cooler made of quartz material, the inside of which is hollow, one side of which is provided with a water inlet, and the other side is provided with a water outlet, the water inlet and the water outlet have a height difference, the outer wall of the water inlet and the water outlet is designed with threads, the fourth shell is placed in the hollow chamber of the cooler; the diameter of the vacuum chamber of the cooler is larger than the diameter of the outer wall of the fourth shell, so that there is a gap between the inner wall of the cooler and the outer wall of the fourth shell for placing condensed water.

10. Use of a gas-solid-liquid membrane separation device according to any one of claims 7-9 in a photocatalytic reaction of CO2.

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