Method for gas-liquid two-phase contact reaction

Abstract

This invention relates to the field of gas-liquid reactions, specifically to a method for gas-liquid two-phase contact reactions. The method is carried out in a shell-and-tube microbubble reactor, which includes a shell and a tube located within and penetrating the shell. The tube wall has holes for the limited passage of gaseous feedstock. The two ends of the tube penetrating the shell are a gaseous feedstock inlet and an unreacted gaseous feedstock outlet, respectively. The shell has a liquid feedstock inlet and a product outlet. The method includes: introducing gaseous feedstock into the tube of the shell-and-tube microbubble reactor, and entering the shell side through the holes in the tube wall to react with the introduced liquid feedstock. This invention, by employing a specially structured shell-and-tube microbubble reactor for gas-liquid two-phase reactions, greatly enhances the gas-liquid reaction process.

Description

Technical Field

[0001] This invention relates to the field of gas-liquid reactions, and more specifically to a method for gas-liquid two-phase contact reactions. Background Technology

[0002] Gas-liquid reactions are a common type of reaction. The process involves gaseous reactants dissolving in a liquid phase, then reacting with catalysts and other reactants in the liquid to produce products. Many reactions utilize gas-liquid reactions, such as hydroformylation, hydrogenation, and oxidation reactions involving oxygen. Reaction kinetics and interface chemistry reveal that gas-liquid reactions essentially occur at the interface between gas and liquid molecules. The diffusion layer is only 3-5 μm; therefore, the better the gas is dispersed in the liquid, the faster the reaction rate. Initially, continuous gas-liquid reactors included continuous batch reactors and tubular reactors. Their reaction processes were often affected by the gas-liquid distribution, resulting in long residence times. Many researchers began to improve the gas-liquid distribution, developing various bubbling reactors. In these reactors, gas is uniformly distributed in the form of small bubbles, continuously passing through the gas-liquid reaction layer, ensuring sufficient gas-liquid contact surface for thorough mixing and a good reaction. However, the effectiveness of contact reactions is still not ideal.

[0003] Homogeneous and heterogeneous catalysts are two common types of catalysts, each with its own advantages and disadvantages. Homogeneous catalysts are in the same phase as the reactants, thus exhibiting higher reaction rates and selectivity, more stable reaction conditions, and more predictable results. Heterogeneous catalysts, due to the mixing of different substances, can provide a larger reaction contact area, thereby increasing reaction rates and yields, but reaction conditions and results may be affected by many factors. However, homogeneous catalysts are dissolved in the reaction system, making complete catalyst recovery and recycling difficult, potentially causing environmental pollution, and requiring large amounts of catalyst addition, resulting in high costs. Heterogeneous catalysts, on the other hand, are in different phases from the reactants and products, making it relatively easy to separate the catalyst from the products after the reaction, reducing catalyst consumption and costs. Therefore, homogeneous catalysts are commonly used in organic synthesis and polymerization reactions due to their high activity and selectivity, while heterogeneous catalysts are widely used in the chemical industry, such as in catalytic reforming, hydrogenation, and oxidation reactions. Their advantages lie in the ease of catalyst separation and recovery, and the ability to process large quantities of materials. Solving the problem of separating homogeneous catalysts and achieving recycling of homogeneous catalysts in continuous reactions would greatly facilitate their industrial application. We proposed using a membrane separation device to achieve the reuse of homogeneous catalysts. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem of insufficient gas-liquid contact in the prior art and to provide a method for gas-liquid two-phase contact reaction, which can greatly enhance the gas-liquid reaction process.

[0005] To achieve the above objectives, the present invention provides a method for gas-liquid two-phase contact reaction, which is carried out in a shell-and-tube microbubble reactor.

[0006] The shell-and-tube microbubble reactor includes:

[0007] The shell, and a tube located inside and penetrating the shell, the tube wall having holes for the passage of a limited gaseous material;

[0008] The tube passes through the shell at both ends, which are the gaseous raw material inlet and the unreacted gaseous raw material outlet, respectively. The shell is provided with a liquid raw material inlet and a product outlet.

[0009] The method includes:

[0010] The gaseous feedstock is introduced into the tube of the shell-and-tube microbubble reactor and enters the shell side through the holes in the tube wall to react with the introduced liquid feedstock.

[0011] Through the above technical solution, the present invention has the following advantages:

[0012] This invention utilizes a specially structured shell-and-tube microbubble reactor for gas-liquid two-phase reactions, which greatly enhances the gas-liquid reaction process.

[0013] In a preferred embodiment of the present invention, membrane separation is used to separate and reuse the catalyst for homogeneous reactions, enabling the reaction to proceed continuously, greatly improving economic efficiency, and facilitating the use of homogeneous catalysts in the industrial field. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of a shell-and-tube microbubble reactor according to a preferred embodiment of the present invention.

[0015] Figure 2 This is a cross-sectional view of a shell-and-tube microbubble gas-liquid reactor according to a preferred embodiment of the present invention.

[0016] Figure 3 This is a schematic diagram of a system and process for a gas-liquid two-phase contact reaction according to a preferred embodiment of the present invention.

[0017] Figure 4 This is a schematic diagram of a membrane separator according to a preferred embodiment of the present invention.

[0018] Figure 4 In the middle section, 1 is the liquid inlet; 2 is the liquid outlet; 3 is the gas inlet; 4 is the gas and product outlet; 5 is the membrane tube body; and 6 is the membrane separator shell. Detailed Implementation

[0019] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0020] In this invention, along the direction of liquid flow, unless otherwise stated, directional terms are used such as upper part, which refers to the position of the reactor shell from top to bottom 0-30%; lower part, which refers to the position of the reactor shell from top to bottom 70-100%; top, which refers to the position of the shell from top to bottom 0-10%; and bottom, which refers to the position of the reactor shell from top to bottom 90-100%.

[0021] This invention provides a method for gas-liquid two-phase contact reaction, which is carried out in a shell-and-tube microbubble reactor, such as... Figure 1 As shown, the shell-and-tube microbubble reactor includes: a shell, and a tube located inside the shell and penetrating the shell, the tube wall having holes for the passage of limited gaseous raw materials; the two ends of the tube penetrating the shell are respectively a gaseous raw material inlet and an unreacted gaseous raw material outlet, and the shell has a liquid raw material inlet and a product outlet;

[0022] The method includes: introducing gaseous raw materials into the tube of a shell-and-tube microbubble reactor, and allowing them to enter the shell side through holes in the tube wall to react with the introduced liquid raw materials.

[0023] This invention utilizes a specially structured shell-and-tube microbubble reactor for gas-liquid two-phase reactions, which greatly enhances the gas-liquid reaction process.

[0024] In this invention, no special requirements are made for the type of gas-liquid reaction. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the type of gas-liquid two-phase contact reaction is a gas-liquid two-phase reaction involving at least one gaseous raw material selected from hydrogen, oxygen, and carbon monoxide.

[0025] According to a preferred embodiment of the present invention, the gas-liquid two-phase contact reaction is a homogeneous catalytic reaction, preferably a hydrogen esterification reaction of α-olefins and / or cycloolefins, wherein the hydrogen esterification reaction of α-olefins and / or cycloolefins is carried out in the presence of a homogeneous catalyst.

[0026] According to a preferred embodiment of the present invention, the homogeneous catalyst is a palladium-phosphine-acid catalyst, preferably the molar ratio of acid, phosphine and palladium in the homogeneous catalyst is 1-9∶9-1∶1, and more preferably 4-6∶6-4∶1.

[0027] According to a preferred embodiment of the present invention, the acid is at least one selected from methylbenzenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, sulfuric acid, trifluoroacetic acid, sodium phosphate, and hydrochloric acid.

[0028] According to a preferred embodiment of the present invention, the phosphine is at least one selected from triphenylphosphine, tri-n-butylphosphine, tricyclohexylphosphine, 1,2-bis(diphenylphosphine)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphine)butane, bis(diphenylphosphine)ferrocene, 1,3-bis(di-tert-butylphosphine)propane, and 1,2-bis(di-tert-butylphosphine)ethane.

[0029] In this invention, no special requirements are placed on the conditions for the contact reaction; the specific conditions are determined based on the specific reaction.

[0030] According to a preferred embodiment of the present invention, the conditions for the contact reaction include a gas pressure of 1.0-10.0 MPa.

[0031] According to a preferred embodiment of the present invention, the conditions for the contact reaction include a reaction temperature of 50-160°C.

[0032] According to a preferred embodiment of the present invention, the conditions for the contact reaction include a liquid flow rate of 50-500 ml / h.

[0033] like Figure 1 As shown, in this invention, the gas raw material inlets of all the tubes can be combined into one gas raw material inlet, located at one end of the reactor shell; the unreacted gas raw material outlets of all the tubes can be combined into one unreacted gas raw material outlet, located at the other end of the reactor shell.

[0034] In this invention, in order to further enhance the degree of gas-liquid reaction, according to a preferred embodiment of the invention, the pore size distribution range of the holes on the tube wall is 2-10 μm, preferably 3-5 μm.

[0035] According to a preferred embodiment of the present invention, the spacing between the holes in the tube wall is 5-30 μm, preferably 10-20 μm. By adopting the aforementioned preferred embodiment, the gas-liquid contact effect can be further improved, and the degree of gas-liquid reaction can be enhanced.

[0036] In this invention, there is no particular limitation on the thickness of the pipe wall. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the wall thickness of the pipe is 20-200 μm, preferably 50-100 μm.

[0037] According to a preferred embodiment of the present invention, the porosity of the tube wall is 20-50%, preferably 30-40%. By adopting the aforementioned preferred embodiment, the gas-liquid contact effect can be further improved, and the degree of gas-liquid reaction can be enhanced.

[0038] According to a preferred embodiment of the present invention, the equivalent diameter of the tube is 1-8 mm, preferably 2-4 mm. By adopting the aforementioned preferred embodiment, the gas-liquid contact effect can be further improved, and the degree of gas-liquid reaction can be enhanced.

[0039] According to a preferred embodiment of the present invention, when the number of tubes is greater than one, the tube spacing is 5-10 mm, preferably 6-8 mm. By adopting the aforementioned preferred solution, the gas-liquid contact effect can be further improved, and the degree of gas-liquid reaction can be enhanced.

[0040] According to a preferred embodiment of the present invention, the ratio of the total cross-sectional area of ​​the tube to the cross-sectional area of ​​the shell is 0.01-0.3, preferably 0.05-0.2. By adopting the aforementioned preferred embodiment, the gas-liquid contact effect can be further improved, and the degree of gas-liquid reaction can be enhanced.

[0041] In this invention, there are no special requirements for the shape of the reactor shell, as long as the solution of this invention can be implemented. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the shell is cylindrical with a length-to-diameter ratio of 2-10, preferably 3-5.

[0042] According to a preferred embodiment of the present invention, the equivalent diameter of the shell is 30-120 mm, preferably 50-80 mm.

[0043] According to a preferred embodiment of the present invention, the length of the housing is 60-500mm, preferably 200-300mm.

[0044] According to a preferred embodiment of the present invention, the shortest distance between the tube and the shell is 3-20 mm, preferably 5-10 mm.

[0045] According to a preferred embodiment of the present invention, a baffle is disposed within the space formed by the shell and the pipe wall, preferably with a distance of 10-50 mm between adjacent baffles, more preferably 20-40 mm. By adopting the aforementioned preferred embodiment, the gas-liquid contact effect can be further improved, and the degree of gas-liquid reaction can be enhanced.

[0046] According to a preferred embodiment of the present invention, the lower part of the shell is provided with a liquid raw material inlet, and the upper part of the shell is provided with a product outlet.

[0047] In this invention, the size of the liquid raw material inlet and the product outlet is not particularly limited and can be adjusted according to the specific situation. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the equivalent diameter of the liquid raw material inlet and the product outlet is 2-10 mm.

[0048] According to a preferred embodiment of the present invention, the gas source and / or gaseous raw material inlet and the unreacted gaseous raw material outlet are connected by a pipeline to ensure the recycling of gaseous raw materials and to maintain pressure.

[0049] In this invention, valve switches, heating devices, and driving devices are installed on any pipeline.

[0050] According to a preferred embodiment of the present invention, the method further includes: passing the product stream containing a homogeneous catalyst after the contact reaction into a membrane separator for membrane separation to obtain a permeate product and a non-permeate recirculating stream, and recycling the recirculating stream back into the liquid phase feedstock. By using membrane separation to separate the reaction products of the reaction unit of the present invention, the catalyst can be reused online, solving the problem of the ineffective recovery and utilization of catalysts.

[0051] like Figure 3 As shown, according to a preferred embodiment of the present invention, the apparatus used in the method further includes: a product collection unit, such as a product collection tank, and a waste gas recovery unit, such as a waste gas treatment tank, which are sequentially connected to the product outlet of the membrane separation unit; and storage tanks for various raw materials, wherein the storage tank for gaseous raw materials is used to output gaseous raw materials to the reactor and collect unreacted gaseous raw materials, and is optionally connected to the separation unit to provide carrier gas for stripping the separation unit; and liquid raw material tanks, solvent tanks, and catalyst tanks provide materials to the mixer unit for mixing to obtain liquid raw materials.

[0052] According to a preferred embodiment of the present invention, the membrane used in the membrane separation unit is selected from at least one of carbon nanotubes, silica membranes, NaA zeolite membranes, and ZSM-5 zeolite membranes, preferably silica membranes. By adopting the aforementioned preferred embodiment, the separation effect between the product and the catalyst can be further improved.

[0053] According to a preferred embodiment of the present invention, the membrane used in the membrane separation unit has a pore size distribution range of 0.5-2 nm, preferably 0.8-1 nm. By adopting the aforementioned preferred embodiment, the separation effect between the product and the catalyst can be further improved.

[0054] In this invention, no special requirements are made for the thickness of the separation membrane. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the membrane thickness of the membrane used in the membrane separation unit is 2-20 μm, preferably 5-10 μm.

[0055] According to a preferred embodiment of the present invention, the membrane used in the membrane separation unit has a porosity of 10-40%, preferably 15-25%. By adopting the aforementioned preferred embodiment, the separation effect between the product and the catalyst can be further improved.

[0056] In the present invention as Figure 3 The system shown and Figure 4 In the membrane separator, the gas-liquid reaction process includes:

[0057] The catalyst, liquid reactants, and solvent are fed into a mixer for mixing. The mixed liquid feedstock is then fed into a shell-and-tube microbubble gas-liquid mixer in the microbubble reaction unit for reaction. After the reaction is complete, the reaction products are separated by membrane separation. A gaseous feedstock is injected to provide a carrier gas for blowing out the precipitated products on the permeate side of the membrane separator. The catalyst-free permeate is sent to a product collection tank, and the gas removed from it is sent to a waste gas treatment tank. The non-permeate containing the catalyst is recycled back to the reactor. The unreacted gaseous feedstock is recycled back to the gas source and / or the reactor for pressure maintenance. In this process, the membrane used in the separation unit of this invention cannot directly permeate all the solvent and product. The liquid permeates through the pressure difference across the membrane, and the liquid rejection rate is typically 20-70%, with better performance at 30-50%.

[0058] The present invention will be described in detail below through embodiments.

[0059] Example 1

[0060] In such Figure 3 The system shown is used in the experiment, and the structure and parameters of the reactor in the system are as follows: Figure 1-2 As shown, the membrane separator structure is as follows: Figure 4 As shown, specifically, the pore size distribution on the tube wall is 3-5 μm; the spacing between the pores on the tube wall is 10 μm; the tube wall thickness is 100 μm; the porosity of the tube wall is 40%; the tube is a circular tube with a diameter of 3 mm; the number of tubes is 37 or 61, this embodiment uses 37 tubes with a tube spacing of 7.5 mm; the ratio of the total cross-sectional area of ​​the tubes to the cross-sectional area of ​​the shell is 0.093; the shell is cylindrical, with a length of 270 mm and a diameter of 60 mm; the shortest distance between the tubes and the shell is 6 mm; baffles are arranged in the space formed by the shell and the tube wall, with a distance of 30 mm between adjacent baffles; the membrane separation uses a silicon oxide membrane with a pore size distribution range of 0.8-1 nm; the membrane thickness is 10 μm; and the porosity is 20%.

[0061] Add 0.1 mmol Pd(OAc)₂, 0.5 mmol PPh₃, 0.5 mmol trifluoroacetic acid, and 100 mL anhydrous methanol to the catalyst tank and mix thoroughly with a stirrer. Add 500 mL dodecene to the α-olefin tank and 1 L methanol to the methanol tank. Purify the reaction apparatus three times with carbon monoxide. Pump the catalyst, dodecene, and methanol into the mixer at flow rates of 5 mL / h, 100 mL / h, and 200 mL / h, respectively. After thorough mixing, introduce the mixture into the reactor. Then, introduce carbon monoxide into the tube bundle of the reactor and gradually increase the pressure to 5.0 MPa. The temperature was slowly raised to 120℃, and the reaction product was fed into a membrane separation unit for separation. Simultaneously, carbon monoxide was introduced as a carrier gas to blow out the precipitated product from the permeate side of the membrane separator. The membrane rejection rate was 40%. The catalyst-free permeate was sent to a product collection tank, while the gas removed was sent to a waste gas treatment tank. The catalyst-containing non-permeate was recycled back to the reactor. Unreacted gaseous feedstock was recycled back to the gas source, i.e., the gas phase storage tank, for pressurization. Samples were taken from the product collection tank and quantitatively analyzed using gas chromatography. The product contained no catalyst, with a dodecene conversion rate of 99% and a selectivity of 98% for methyl tridecaate.

[0062] Example 2

[0063] Same as Example 1, except that cyclopentadiene is used instead of dodecene.

[0064] Reaction results: The conversion rate of cyclopentadiene was 99%, and the selectivity of the product dimethyl cyclopentanoate was 98%.

[0065] Example 3

[0066] Same as Example 1, except that oxygen is used as the gaseous raw material and cumene is used as the liquid raw material for the reaction, and the reaction conditions are 110°C and gas pressure is 1 MPa.

[0067] Reaction results: The conversion rate of cumene was 20-25% (excessive product concentration can lead to local overheating and explosion); the selectivity of cumene hydroperoxide was 96%.

[0068] Example 4

[0069] Similar to Example 1, except that the pore size distribution of the tube wall is 5-10 μm, the porosity remains unchanged, and the spacing and number of pores are adjusted accordingly.

[0070] Reaction results: Dodecene conversion rate was 90%, and the selectivity of the product methyl tridecanoate was 90%.

[0071] Example 5

[0072] Same as Example 1, except that the pipe diameter is 5mm, the number of pipes remains the same, and the pipe spacing is adjusted accordingly.

[0073] Reaction results: Dodecene conversion rate was 92%, and the selectivity of the product methyl tridecanoate was 91%.

[0074] Example 6

[0075] Same as Example 1, except that the reactor length is 120 mm.

[0076] Reaction results: Dodecene conversion rate was 89%, and the selectivity of the product methyl tridecanoate was 93%.

[0077] Example 7

[0078] Same as Example 1, except that the same NaA zeolite membrane is used.

[0079] Reaction results: Dodecene conversion rate was 96%, and the selectivity of the product methyl tridecanoate was 95%.

[0080] Comparative Example 1

[0081] Similar to Example 1, except that an AC250 automatic reactor is used for gas-liquid contact reaction.

[0082] Reaction results: Dodecene conversion rate was 83%, and the selectivity of the product methyl tridecanoate was 88%.

[0083] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for gas-liquid two-phase contact reaction, characterized in that, This method is carried out in a shell-and-tube microbubble reactor. The shell-and-tube microbubble reactor includes: The shell, and a tube located inside and penetrating the shell, the tube wall having holes for the passage of a limited gaseous material; The tube passes through the shell at both ends, which are the gaseous raw material inlet and the unreacted gaseous raw material outlet, respectively. The shell is provided with a liquid raw material inlet and a product outlet. The method includes: The gaseous feedstock is introduced into the tube of the shell-and-tube microbubble reactor and enters the shell side through the holes in the tube wall to react with the introduced liquid feedstock.

2. The method according to claim 1, wherein, The gas-liquid two-phase contact reaction is a gas-liquid two-phase reaction involving at least one gaseous raw material selected from hydrogen, oxygen, and carbon monoxide.

3. The method according to claim 1 or 2, wherein, The gas-liquid two-phase contact reaction is a homogeneous catalytic reaction, preferably a hydrogen esterification reaction of α-olefins and / or cycloolefins, wherein the hydrogen esterification reaction of α-olefins and / or cycloolefins is carried out in the presence of a homogeneous catalyst; more preferably... The homogeneous catalyst is a palladium-phosphonic acid catalyst, and preferably the molar ratio of acid, phosphine and palladium in the homogeneous catalyst is 1-9∶9-1∶1, more preferably 4-6∶6-4∶1; More preferably, The acid is at least one selected from the following: toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, sulfuric acid, trifluoroacetic acid, sodium phosphate, and hydrochloric acid; and / or The phosphine is at least one selected from triphenylphosphine, tri-n-butylphosphine, tricyclohexylphosphine, 1,2-bis(diphenylphosphine)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphine)butane, bis(diphenylphosphine)ferrocene, 1,3-bis(di-tert-butylphosphine)propane, and 1,2-bis(di-tert-butylphosphine)ethane.

4. The method according to any one of claims 1-3, wherein, The conditions for the contact reaction include: a gas pressure of 1.0-10.0 MPa and / or a reaction temperature of 50-160°C.

5. The method according to any one of claims 1-4, wherein, The pore size distribution range of the holes on the pipe wall is 2-10 μm, preferably 3-5 μm; and / or The hole spacing on the tube wall is 5-30 μm, preferably 10-20 μm; and / or The wall thickness of the tube is 20-200 μm, preferably 50-100 μm; and / or The porosity of the tube wall is 20-50%, preferably 30-40%.

6. The method according to any one of claims 1-5, wherein, The equivalent diameter of the tube is 1-8 mm, preferably 2-4 mm; and / or When the number of tubes is greater than one, the tube spacing is 5-10 mm, preferably 6-8 mm; and / or The ratio of the total cross-sectional area of ​​the tube to the cross-sectional area of ​​the shell is 0.01-0.3, preferably 0.05-0.

2.

7. The method according to any one of claims 1-6, wherein, The shell is cylindrical with a length-to-diameter ratio of 2-10, preferably 3-5; preferably... The equivalent diameter of the shell is 30-120 mm, preferably 50-80 mm; and / or The length of the shell is 60-500mm, preferably 200-300mm.

8. The method according to any one of claims 1-7, wherein, The shortest distance between the tube and the shell is 3-20 mm, preferably 5-10 mm; and / or A flow-bending component is disposed within the space formed by the shell and the pipe wall, preferably with a distance of 10-50 mm between adjacent flow-bending components, more preferably 20-40 mm; and / or The lower part of the shell is provided with a liquid raw material inlet, and the upper part of the shell is provided with a product outlet.

9. The method according to any one of claims 1-8, wherein, The method further includes: passing the product stream containing the homogeneous catalyst after the contact reaction into a membrane separator for membrane separation to obtain the permeate product and the non-permeate circulating stream, and recycling the circulating stream back into the liquid phase feed.

10. The method according to claim 9, wherein, The membrane used in the membrane separation unit is selected from at least one of carbon nanotubes, silica membranes, NaA zeolite membranes, and ZSM-5 zeolite membranes, preferably silica membranes; and / or The membrane used in the membrane separation unit has a pore size distribution range of 0.5-2 nm, preferably 0.8-1 nm, and / or a membrane thickness of 2-20 μm, preferably 5-10 μm, and / or a porosity of 10-40%, preferably 15-25%.

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