A reaction separation bifunctional catalytic membrane reaction device for synthesizing imine by catalytic dehydration condensation of alcohol amine and a method thereof

Abstract

The application discloses a reaction-separation bifunctional catalytic membrane reaction device for synthesizing imines through catalytic dehydration condensation of alcohol amines and a method thereof. The device comprises an inner cavity and an outer cavity. The inner cavity is prepared according to the following steps: S1, providing a porous matrix, a first modification solution, an LTA molecular sieve membrane synthesis solution and an active metal layer synthesis solution; S2, modifying the porous matrix in the first modification solution to obtain a modified porous matrix; S3, placing the modified porous matrix in the LTA molecular sieve membrane synthesis solution, and placing them together in a hydrothermal kettle to perform a hydrothermal synthesis reaction, so that a porous matrix coated with an LTA molecular sieve membrane is obtained; and S4, placing the porous matrix coated with the LTA molecular sieve membrane in the active metal layer synthesis solution to perform surface impregnation, so that a porous matrix coated with an LTA molecular sieve membrane loaded with an active metal is obtained, namely the inner cavity. The application solves the problem of low conversion rate in the reaction process, moves the overall balance of the reaction to the positive direction, and significantly improves the yield of imines.

Description

Technical Field

[0001] This invention belongs to the field of imine preparation technology, specifically relating to a bifunctional catalytic membrane reaction device and method for catalytic dehydration condensation of alcoholamines to prepare imines. Background Technology

[0002] The synthesis of imines solves the problem of directly activating unstable intermediates from inert starting materials, demonstrating broad value in the pharmaceutical, materials, and green chemical industries. Traditionally, these compounds are produced through acid-catalyzed condensation of aldehydes or ketones, but this method has limitations in handling acidic wastes, and the suitable substrate range for aldehydes or ketones is narrow. In recent years, various alternative strategies have been developed for imine synthesis. The direct coupling of alcohols and amines to form imines has become a particularly attractive and efficient route. Direct coupling of alcohols and amines to form imines eliminates the need for the traditional two-step synthesis method—that is, alcohol dehydrogenation to aldehydes or ketones, followed by dehydration condensation with amines to synthesize imines. Simplifying the two-step process into a one-pot method is a major advantage of direct coupling of alcohols and amines to form imines. Furthermore, the direct coupling of alcohols and amines to form imines produces only water and hydrogen as byproducts, adhering to the principles of green chemistry. Therefore, the direct coupling of alcohols and amines to form imines has a very broad market application prospect in the chemical industry.

[0003] Currently, the main technologies for producing imines include two processes: traditional aldehyde-amine condensation and direct coupling of alcohols and amines. The traditional aldehyde-amine condensation method involves the dehydration condensation of an aldehyde or ketone with a primary amine under the action of a catalyst to generate an imine. The direct coupling of alcohols and amines uses widely available and stable alcohols as raw materials, directly reacting them with amines through dehydrogenation or transfer hydrogenation under the action of a metal catalyst to obtain imines. This process uses water as the only byproduct, exhibiting high atom economy and environmental friendliness.

[0004] The direct coupling of alcohols and amines to form imines is currently the greenest and most widely used technique for synthesizing imines. The main catalysts used in this method include Cu / SiO2, Ni / SiO2, and CuMn / SiO2. Copper-based catalysts exhibit high selectivity for imines. However, because SiO2 acts as a neutral support, its surface lacks sufficient acidic sites for the dehydration process. Furthermore, Cu itself, while a relatively weak but stable metal, has low activity for alcohol dehydrogenation. Therefore, the conversion rate of the direct coupling of alcohols and amines to imines is relatively low. The reaction intermediates, aldehydes or ketones, also require acidic sites for activation, increasing the polarization of the C=O bond and enhancing the positive charge of C, allowing the nitrogen in the amine compound with a lone pair of electrons to undergo a nucleophilic reaction. These factors contribute to the low conversion rate of this reaction.

[0005] The direct coupling of alcoholic amines to form imines is itself a reversible reaction, as shown in the following equation:

[0006] In traditional fixed-bed reactors, as the reaction proceeds, the water produced during the N-alkylation of alkanolamines cannot be removed in time, making it difficult for the reaction to continue in the forward direction, resulting in a low conversion rate. Increasing the temperature to promote N-alkylation disrupts the thermodynamic equilibrium and easily allows the imine to contact with metal hydrides, generating unwanted secondary amines and reducing the selectivity of the imine. Therefore, timely removal of the water produced during the reaction is crucial for improving the conversion rate of this reaction.

[0007] Membrane reactors can fundamentally solve thermodynamic equilibrium problems, achieving breakthroughs in multiple aspects such as significantly increased yield, simplified processes, effective reduction in energy consumption, and outstanding environmental benefits. For the pursuit of green, efficient, and economical imine synthesis processes, membrane reactors provide a practical and ideal pathway. The membrane reactor directly removes water generated during the reaction, allowing the entire reaction to proceed in the forward direction and significantly improving the conversion rate. Because the membrane reactor is designed to directly load metal active sites onto LTA molecules that can selectively filter water, when the N-alkylation process occurs at the active sites on the LTA membrane, the LTA membrane can directly remove the generated water in situ, allowing the reaction to proceed in the forward direction.

[0008] Ammonia water is used to complex copper nitrate as the active metal solution. The active metal solution is a copper-ammonia complex solution. The copper-ammonia complex solution combines with the silanol groups on the surface of the LTA membrane to form layered silicates. The layered silicates are reduced by hydrogen to form monovalent copper. The synergistic effect of monovalent copper and zero-valent copper helps the catalytic reaction. Monovalent copper, as a Lewis acid site, can activate ketones and polarize C=O, making it easier for N with lone pair electrons to attack C, and facilitating N alkylation. CN106000269A discloses a reaction separation bifunctional catalytic membrane reactor and its application for catalytic dehydration of methanol to prepare dimethyl ether. The reactor has an inner cavity and an outer cavity structure. The inner cavity consists of a porous matrix, an LTA molecular sieve membrane, and a FAU molecular sieve membrane from the inside to the outside. Methanol is filled between the inner and outer cavities for catalytic reaction. At the same time, the water vapor generated by the reaction is separated in situ by the LTA molecular sieve membrane, thereby breaking the reaction equilibrium limitation and improving the methanol conversion rate and dimethyl ether selectivity. Compared with the traditional fixed-bed reactor, the dimethyl ether yield is significantly improved.

[0009] CN220919219U discloses an apparatus for preparing ethyl methyl carbonate using a membrane reactor. The apparatus uses dimethyl carbonate and anhydrous ethanol as raw materials, which are preheated, vaporized, and superheated before entering the membrane reactor. A transesterification reaction is carried out under the catalysis of NaY molecular sieves. Simultaneously, a hydrophilic LTA molecular sieve membrane is used to selectively separate the byproduct methanol, achieving integrated reaction and separation. Compared to traditional distillation processes, this method simplifies the process, reduces energy consumption and equipment investment, and improves the conversion rate of ethyl methyl carbonate.

[0010] CN112371114A discloses a method for the oxidative coupling synthesis of imines from alcohols using manganese oxide catalysts. The method employs manganese oxides such as MnO2, Mn2O3, Mn3O4, or MnO as catalysts, with air or oxygen as the oxygen source, and carries out the oxidative coupling reaction of alcohols and amines in organic solvents such as toluene at 30–120°C to synthesize imine compounds in one step. Compared to precious metal catalysts, this manganese oxide catalyst has inexpensive and readily available raw materials, a simple preparation process, and high imine selectivity and yield. However, the reaction is carried out in batch reaction flasks and reflux condensers, resulting in a discontinuous process and difficulty in scale-up. Furthermore, the reaction is conducted in organic solvents such as toluene, ethylbenzene, xylene, and ethyl acetate, increasing solvent recovery and environmental burden.

[0011] Currently, the direct synthesis of imines via coupling of alcoholamines still suffers from drawbacks such as low conversion rate and low yield. There is an urgent need to develop a reaction apparatus and method that can improve the conversion rate and product yield, improve the working environment, save production costs, and achieve high-efficiency synthesis of imines. Summary of the Invention

[0012] To address the aforementioned technical problems in the existing technology, the present invention aims to provide a reaction separation bifunctional molecular sieve membrane catalytic reaction device and method suitable for the direct synthesis of imine from the dehydration condensation of alcoholamines. By applying the membrane reactor to imine synthesis, the problem of low conversion rate during the reaction process is effectively solved, the overall equilibrium of the reaction is shifted to the positive direction, and the yield of imine is significantly improved. Moreover, the membrane reactor involved is similar to a fixed-bed reactor, which can realize continuous production of imine and has great potential for industrial scale-up.

[0013] The technical solution adopted in this invention is: The first aspect of the present invention relates to a bifunctional catalytic membrane reaction apparatus for catalyzing the dehydration condensation of alcoholamines to synthesize imines. The reaction apparatus includes an inner cavity and an outer cavity, the gap between the inner and outer cavities being used to fill a mixed solution of an amine and an alcohol. The inner cavity, from the inside out, comprises: a porous substrate, an LTA molecular sieve membrane bonded to the surface of the porous substrate, and an active metal layer bonded to the surface of the LTA molecular sieve membrane. The inner cavity is characterized by being prepared according to the following steps: S1. Provides a porous matrix, a first modification solution, an LTA molecular sieve membrane synthesis solution, and an active metal layer synthesis solution; S2. The porous matrix is ​​placed in the first modification solution for modification to obtain a modified porous matrix; S3. The modified porous matrix is ​​placed in the LTA molecular sieve membrane synthesis solution and then placed together in a hydrothermal reactor to carry out a hydrothermal synthesis reaction, and the reaction yields a porous matrix coated with the LTA molecular sieve membrane. S4. The porous substrate coated with the LTA molecular sieve membrane is placed in the active metal layer synthesis solution for surface impregnation to obtain the porous substrate coated with the active metal-loaded LTA molecular sieve membrane, i.e., the inner cavity.

[0014] Furthermore, the porous matrix is ​​a hollow tubular α-Al₂O₃; the LTA molecular sieve membrane is a hydrophilic LTA molecular sieve membrane, used for the selective separation of water vapor formed during the reaction process. The hydrophilicity of the LTA molecular sieve membrane and the Na₂O₃ on its surface... + The sites can selectively and rapidly adsorb and permeate water molecules while blocking the entry of alcohols and amines; the active metal layer is a copper-based metal layer used to catalyze the reaction of amines and alcohols to form imines. It is formed by immersing the substrate covered with the LTA membrane in a metal precursor solution. The active metal of the active metal layer is covalently bonded to the LTA molecular sieve membrane.

[0015] Furthermore, the hollow tubular α-Al2O3 has an outer diameter of 10~12 mm, an inner diameter of 6~9 mm, a length of 10~12 cm, and a pore size of 1.0~15 µm.

[0016] Furthermore, in step S1, the first modified solution is a mixed solution of APTES and toluene.

[0017] The LTA molecular sieve membrane is bridged with a porous matrix using a mixed solution of APTES and toluene. The molecular structure of APTES is NH2-(CH2)3-Si(OC2H5)3. Under heating conditions, its ethoxy group (-OC2H5) hydrolyzes and condenses with the hydroxyl group (-OH) on the α-Al2O3 surface, forming stable Si-O-Al covalent bonds, thus chemically anchoring the APTES molecules to the support surface. The LTA molecular sieve membrane is bonded to the APTES-modified α-Al2O3 matrix through hydrogen bonds and electrostatic interactions, while the zeolite network of the LTA molecular sieve membrane is formed through covalent bonds. Specifically, the silicate and aluminate groups in the synthesis solution interact electrostatically or with the amino groups (-NH2) of APTES, guiding the preferential growth of zeolite crystals on the modified surface. Through hydrothermal synthesis, zeolite crystals grow and intertwine directly on the support surface, forming a continuous membrane layer. The newly formed zeolite crystals are connected by covalent bonds (Si-O-Si, Al-O-Si).

[0018] Furthermore, the thickness of LTA molecular sieve membranes using APTES as a covalent linker is 1~3.5μm; the thickness of LTA molecular sieve membranes using PEI as a substrate modifier is 3.5~6μm.

[0019] Furthermore, in step S3, the reaction temperature in the hydrothermal reactor is 40~100℃, the hydrothermal synthesis time is 10~24 hours, and the porous matrix coated with the LTA molecular sieve membrane obtained after the hydrothermal synthesis reaction is dried at 90~120℃.

[0020] Furthermore, in step S3, the reaction temperature in the hydrothermal reactor is 50℃~80℃, the hydrothermal synthesis time is 20~24 hours, and the porous matrix coated with the LTA molecular sieve membrane obtained after the hydrothermal synthesis reaction is dried at 100~110℃.

[0021] Furthermore, in step S4, the active metal layer solution refers to the precursor solution of the active metal layer, which is a mixed solution of copper nitrate trihydrate and one of ammonia, ethylenediamine, ethanolamine, and mannitol, or a mixed solution of nickel nitrate hexahydrate and ammonia.

[0022] Furthermore, in step S4, the surface impregnation involves vertically inserting the porous substrate coated with the LTA molecular sieve membrane into a glass bottle containing the active metal layer synthesis solution, maintaining the impregnation state for 30-60 seconds, vertically pulling it out after impregnation, and repeating the impregnation process 10-20 times.

[0023] Furthermore, in step S4, the immersion state is maintained for 30 to 40 seconds.

[0024] Furthermore, in step S4, after drying is completed, the product is placed in a muffle furnace for roasting at a temperature of 300°C to 500°C.

[0025] Furthermore, in step S1, the Na, Al, and Si sources used in the LTA molecular sieve membrane synthesis solution are NaOH, NaAlO2, and Na2SiO2. 3； The molar ratio of Na2O, Al2O3, SiO2, and H2O is 50~60:1~2:5~10:700~1000.

[0026] Furthermore, in step S1, the Na, Al, and Si sources used in the LTA molecular sieve membrane synthesis solution are NaOH, NaAlO2, and tetraethyl orthosilicate (TEOS). The molar ratio of NaOH, NaAlO2, tetraethyl orthosilicate, and H2O is 20~100:0.5~5:5~10:500~1000.

[0027] Furthermore, in step S1, the Na, Al, and Si sources used in the LTA molecular sieve membrane synthesis solution are NaOH, NaAlO2, and Ludox silica sol. The molar ratio of NaOH, NaAlO2, silica sol, and H2O is 20~100:0.5~5:5~10:500~1000.

[0028] A second aspect of the present invention relates to a method for preparing imines using the reaction apparatus described above, characterized in that the method comprises the following steps: i) Fill the gap between the inner and outer cavities of the reaction apparatus with a mixed solution of alcohol and amine. The mixed solution of alcohol and amine is injected into the gap between the inner and outer cavities by an injection pump. Inside the inner cavity, N2 is turned on to purge or a vacuum pump is turned on to create negative pressure for purging, blowing away the water vapor generated in the reaction. ii) Heat the reaction apparatus to 150°C-250°C to obtain an imine.

[0029] Furthermore, the flow rate of the syringe pump described in step i) is controlled at 0.01 ml / min to 2 ml / min.

[0030] Furthermore, in step i), the molar ratio of alcohol to amine in the mixed solution of alcohol and amine is 1:1 to 1:10.

[0031] Compared with the prior art, the beneficial effects of the present invention are reflected in: 1. The reaction apparatus of this invention is active against various amines and alcohols. Using aniline as the amine reactant, it can react with various fatty alcohols and aromatic alcohols. Using benzyl alcohol as the alcohol reactant, it can react with various aromatic amines. Fatty alcohols include one of propylene glycol methyl ether, isopropanol, cyclohexanol, pentanol, hexanol, and octanol; aromatic alcohols include one of benzyl alcohol, o-nitrobenzyl alcohol, p-methylbenzyl alcohol, p-nitrobenzyl alcohol, p-chlorobenzyl alcohol, and phenethyl alcohol. Various aromatic amines include one of aniline, 2-methyl-6-ethylaniline, p-methylaniline, p-methoxyaniline, p-chloroaniline, and p-nitroaniline.

[0032] 2. This invention applies a membrane reactor to imine synthesis, which effectively solves the problem of low conversion rate during the reaction process, shifts the overall equilibrium of the reaction to the positive side, and significantly improves the yield of imine. Moreover, the membrane reactor involved is similar to a fixed-bed reactor, which can realize continuous production of imine and has great potential for industrial scale-up.

[0033] 3. In this invention, the imine and water generated in the reaction are formed on the surface of the active metal layer. The gaseous alcohol and liquid amine are pre-mixed and enter the channel, flowing axially along the outer wall of the membrane tube. The alcohol and amine come into full contact with the active metal layer, resulting in a complete reaction. Because the gas phase flows closely against the inner wall of the LTA molecular sieve membrane, the water generated by N-alkylation immediately vaporizes into water vapor at the reaction temperature. Once the water vapor passes through the membrane pores, it is rapidly carried away, forming an integrated "generation-permeation-removal" rapid dehydration channel. This avoids secondary adsorption or accumulation of water on the membrane surface, significantly improving membrane separation efficiency.

[0034] 4. When the present invention uses a vacuum pump instead of N2 purging, a negative pressure is formed inside α-Al2O3. At this time, the liquid amine between the inner and outer cavities is "drawn" to the membrane surface due to the pressure difference, forming a thinner liquid film, which is conducive to the dissolution of gaseous alcohol; the negative pressure will cause the trace amount of gas dissolved in the amine (including alcohol and water vapor generated by the reaction) to produce a "micro-boiling" effect, forming local microbubbles, which further enhances mixing. Attached Figure Description

[0035] Figure 1 This is an overall schematic diagram of the reaction separation bifunctional catalytic membrane reactor described in this invention. Figure 1 .

[0036] Figure 2 This is a schematic diagram of the reaction tube of the bifunctional catalytic membrane reactor for reaction separation described in this invention. Figure 2 .

[0037] Figure 3 This is a schematic diagram of the internal structure of the reaction separation bifunctional catalytic membrane reaction device described in this invention. Figure 3 .

[0038] The accompanying diagrams are labeled as follows: 1-Liquid piping system; 2-Gas piping system; 3-Membrane reactor; 4-Cooling and product collection system; 5-Purge gas outlet; 11-Raw material tank; 12-Feed pump; 21-Gas cylinder; 22-Mass flow meter; 31-Cavity; 32-Inner cavity; 33-Outer cavity. Detailed Implementation

[0039] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0041] The present invention will now be described in detail with reference to the accompanying drawings and exemplary embodiments.

[0042] Example 1

[0043] refer to Figures 1 to 3 The present invention provides a bifunctional molecular sieve membrane catalytic reaction device suitable for the direct synthesis of imines from the dehydration condensation of alcoholamines, comprising a liquid pipeline system 1, a gas pipeline system 2, a membrane reactor 3, and a cooling and product collection system 4; as shown in the figure. Figure 1 The top of the membrane reactor 3 shown is connected to the liquid pipeline system 1 and the gas pipeline system 2, respectively. The bottom of the membrane reactor 3 is connected to the cooling and product collection system 4; wherein: the membrane reactor includes a cavity 31, the cavity 31 includes an inner cavity 32 and an outer cavity 33, the inner cavity 32 ( Figure 3 The membrane reactor 3 comprises a porous α-Al₂O₃ matrix, an LTA molecular sieve membrane on the surface of the porous matrix, and an active metal layer on the surface of the LTA molecular sieve. A mixed solution of amines and alcohols is filled between the inner and outer cavities. The liquid piping system 1 includes a raw material tank 11 and a feed pump 12, which are connected via liquid piping. The feed pump 12 is also connected to the side of the membrane reactor 3 via liquid piping. The gas piping system 2 includes a gas cylinder 21 and a mass flow meter 22, which are connected via gas piping. The mass flow meter is also connected to the top of the membrane reactor 3 via gas piping. The inner cavity is prepared according to the following steps: S1. Provides a porous matrix, a first modification solution, an LTA molecular sieve membrane synthesis solution, and an active metal layer synthesis solution; S2. The porous matrix is ​​placed in the first modification solution for modification to obtain a modified porous matrix; S3. The modified porous matrix is ​​placed in the LTA molecular sieve membrane synthesis solution and then placed together in a hydrothermal reactor to carry out a hydrothermal synthesis reaction, and the reaction yields a porous matrix coated with the LTA molecular sieve membrane. S4. The porous substrate coated with the LTA molecular sieve membrane is placed in the active metal layer synthesis solution for surface impregnation to obtain the porous substrate coated with the active metal-loaded LTA molecular sieve membrane, i.e., the inner cavity.

[0044] In this embodiment, the porous substrate is a hollow tubular α-Al₂O₃; the LTA molecular sieve membrane is a hydrophilic LTA molecular sieve membrane, used for the selective separation of water vapor formed during the reaction process. The hydrophilicity of the LTA molecular sieve membrane and the Na₂O₃ on its surface... + The sites can selectively and rapidly adsorb and permeate water molecules while blocking the entry of alcohols and amines; the active metal layer is a copper-based metal layer used to catalyze the reaction of amines and alcohols to form imines. It is formed by immersing the substrate covered with the LTA membrane in a metal precursor solution. The active metal of the active metal layer is covalently bonded to the LTA molecular sieve membrane.

[0045] In this embodiment, the hollow tubular α-Al2O3 has an outer diameter of 10~12 mm, an inner diameter of 6~9 mm, a length of 10~12 cm, and a pore size of 1.0~15 µm.

[0046] In this embodiment, in step S1, the first modification solution is a mixed solution of APTES and toluene.

[0047] The LTA molecular sieve membrane is bridged with a porous matrix using a mixed solution of APTES and toluene. The molecular structure of APTES is NH2-(CH2)3-Si(OC2H5)3. Under heating conditions, its ethoxy group (-OC2H5) hydrolyzes and condenses with the hydroxyl group (-OH) on the α-Al2O3 surface, forming stable Si-O-Al covalent bonds, thus chemically anchoring the APTES molecules to the support surface. The LTA molecular sieve membrane is bonded to the APTES-modified α-Al2O3 matrix through hydrogen bonds and electrostatic interactions, while the zeolite network of the LTA molecular sieve membrane is formed through covalent bonds. Specifically, the silicate and aluminate groups in the synthesis solution interact electrostatically or with the amino groups (-NH2) of APTES, guiding the preferential growth of zeolite crystals on the modified surface. Through hydrothermal synthesis, zeolite crystals grow and intertwine directly on the support surface, forming a continuous membrane layer. The newly formed zeolite crystals are connected by covalent bonds (Si-O-Si, Al-O-Si).

[0048] In this embodiment, the thickness of the LTA molecular sieve membrane using APTES as a covalent linker is 1~3.5μm; the thickness of the LTA molecular sieve membrane using PEI as a substrate modifier is 3.5~6μm.

[0049] In this embodiment, in step S3, the reaction temperature in the hydrothermal reactor is 40~100℃, the hydrothermal synthesis time is 10~24 hours, and the porous matrix coated with the LTA molecular sieve membrane obtained after the hydrothermal synthesis reaction is dried at 90~120℃.

[0050] In this embodiment, in step S3, the reaction temperature in the hydrothermal reactor is 50℃~80℃, the hydrothermal synthesis time is 20~24 hours, and the porous matrix coated with the LTA molecular sieve membrane obtained after the hydrothermal synthesis reaction is dried at 100~110℃.

[0051] In this embodiment, in step S4, the active metal layer solution refers to the precursor solution of the active metal layer. The precursor solution is a mixed solution of copper nitrate trihydrate and ammonia, ethylenediamine, ethanolamine, and mannitol, or a mixed solution of nickel nitrate hexahydrate and ammonia.

[0052] Specifically, the precursor solution is prepared from Cu(NO3)2·3H2O and ammonia water with a concentration of 25-28%. 2+ :NH 4+ =1:2~1:4; or the precursor solution is a mixed solution of Cu(NO3)2·3H2O and ethylenediamine.

[0053] In this embodiment, in step S4, the surface impregnation involves vertically inserting a porous substrate coated with an LTA molecular sieve membrane into a glass bottle containing the active metal layer synthesis solution, maintaining the impregnation state for 30-60 seconds, and then vertically pulling it out after impregnation. This impregnation is repeated 10-20 times.

[0054] In this embodiment, in step S4, the immersion state is maintained for 30 to 40 seconds.

[0055] In this embodiment, in step S4, after drying is completed, the product is placed in a muffle furnace for roasting at a temperature of 300℃~500℃.

[0056] In this embodiment, in step S1, the Na, Al, and Si sources used in the LTA molecular sieve membrane synthesis solution are NaOH, NaAlO2, and Na2SiO2. 3； The molar ratio of Na2O, Al2O3, SiO2, and H2O is 50~60:1~2:5~10:700~1000.

[0057] In this embodiment, in step S1, the Na, Al, and Si sources used in the LTA molecular sieve membrane synthesis solution are NaOH, NaAlO2, and tetraethyl orthosilicate (TEOS). The molar ratio of NaOH, NaAlO2, tetraethyl orthosilicate, and H2O is 20~100:0.5~5:5~10:500~1000.

[0058] In this embodiment, in step S1, the Na, Al, and Si sources used in the LTA molecular sieve membrane synthesis solution are NaOH, NaAlO2, and Ludox silica sol. The molar ratio of NaOH, NaAlO2, silica sol, and H2O is 20~100:0.5~5:5~10:500~1000.

[0059] Example 2

[0060] A method for preparing imines using the reaction apparatus provided in Example 1 according to the present invention, the method comprising the following steps: i) The gap between the inner and outer cavities of the reaction apparatus is filled with a mixed solution of alcohol and amine. The mixed solution of alcohol and amine is injected into the gap between the inner and outer cavities by an injection pump. N2 is turned on inside the inner cavity to blow away the water vapor generated in the reaction. ii) Heat the reaction apparatus to 150°C-250°C to obtain an imine.

[0061] 9. The method as described in claim 8, wherein the flow rate of the syringe pump in step i) is controlled at 0.01 ml / min to 2 ml / min.

[0062] 10. The method according to claim 8, wherein the molar ratio of alcohol to amine in the mixed solution of alcohol and amine in step i) is 1:1 to 1:10.

[0063] Before the reaction, the membrane reactor must be activated with H2 at a temperature between 250 and 300°C. The H2 flow rate is between 30 ml / min and 50 ml / min.

[0064] Example 3

[0065] In step S3, the reaction temperature in the hydrothermal reactor is 60°C, the hydrothermal synthesis time is 24 hours, and the porous matrix coated with the LTA molecular sieve membrane obtained after the hydrothermal synthesis reaction is dried at 90~120°C.

[0066] The Na, Al, and Si sources used in the LTA molecular sieve membrane synthesis solution are NaOH, NaAlO2, and Na2SiO3, respectively. The molar ratio of Na2O, Al2O3, SiO2, and H2O is 50:2:5:1000. The active metal solution refers to the metal precursor solution, which is prepared from Cu(NO3)2·3H2O and ammonia water with a concentration of 25-28%. 2+ :NH 4+ =1:2.

[0067] The membrane reactor prepared under the above conditions was used with aniline and benzyl alcohol as the substrate. A 500 mL mixture of aniline and benzyl alcohol in a 2:1 molar ratio (326 g aniline, 189 g benzyl alcohol) was prepared as the reactants. The reaction temperature was set at 200℃, and the flow rate of the reaction solution was set at 0.1 mL / min. After 8 hours, the reaction solution was collected in a collection tank and analyzed by gas chromatography (GC). The GC model was SP-3000. The capillary tube model was HP-5. The chromatographic column was a capillary column (30 m × 0.32 mm × 0.50 μm). The carrier gas was high-purity N2. The split ratio was 60:1. The carrier gas flow rate was 40 mL / min. The vaporization chamber temperature was 250℃. The detector was FID, with hydrogen at 50 mL / min and air at 60 mL / min. Temperature rise program settings: Initial temperature set to 80 ℃, hold for 2 min, rise to 250 ℃ at 15 ℃ / min, hold for 1 min.

[0068] The remaining implementation methods are the same as those in Examples 1 and 2.

[0069] Example 4

[0070] In step S3, the reaction temperature in the hydrothermal reactor is 60°C, the hydrothermal synthesis time is 24 hours, and the porous matrix coated with the LTA molecular sieve membrane obtained after the hydrothermal synthesis reaction is dried at 90~120°C.

[0071] The Na, Al, and Si sources used in the LTA molecular sieve membrane synthesis solution are NaOH, NaAlO2, and Na2SiO3, respectively. The molar ratio of Na2O, Al2O3, SiO2, and H2O is 50:2:5:1000. The active metal solution refers to the metal precursor solution, which is prepared from Cu(NO3)2·3H2O and ammonia water with a concentration of 25-28%. 2+ :NH 4+ =1:2.

[0072] The membrane reactor prepared under the above conditions was used as a substrate for the reaction with propylene glycol methyl ether and aniline. A 500 ml mixture of aniline and propylene glycol methyl ether in a molar ratio of 2:1 was prepared as the reaction raw material, with 333 g of aniline and 161 g of propylene glycol methyl ether. After 8 h, the reaction solution was collected in a collection tank and analyzed by gas chromatography.

[0073] The remaining implementation methods are the same as those in Examples 1 and 2.

[0074] Example 5

[0075] In step S3, the reaction temperature in the hydrothermal reactor is 60°C, the hydrothermal synthesis time is 24 hours, and the porous matrix coated with the LTA molecular sieve membrane obtained after the hydrothermal synthesis reaction is dried at 90~120°C.

[0076] The Na, Al, and Si sources used in the LTA molecular sieve membrane synthesis solution are NaOH, NaAlO2, and Na2SiO3, respectively. The molar ratio of Na2O, Al2O3, SiO2, and H2O is 50:2:5:1000. The active metal solution refers to the metal precursor solution, which is prepared from Cu(NO3)2·3H2O and ammonia water with a concentration of 25-28%. 2+ :NH 4+ =1:2.

[0077] The membrane reactor prepared under the above conditions was used as a substrate reaction with isopropanol and aniline. A 500 ml mixture of aniline and isopropanol with a molar ratio of 2:1 was prepared as the reaction raw material, with 360 g of aniline and 116 g of isopropanol. After 8 h, the reaction solution was collected in a collection tank and analyzed by gas chromatography.

[0078] The remaining implementation methods are the same as those in Examples 1 and 2.

[0079] Example 6

[0080] In step S3, the reaction temperature in the hydrothermal reactor is 60°C, the hydrothermal synthesis time is 24 hours, and the porous matrix coated with the LTA molecular sieve membrane obtained after the hydrothermal synthesis reaction is dried at 90~120°C.

[0081] The Na, Al, and Si sources used in the LTA molecular sieve membrane synthesis solution are NaOH, NaAlO2, and Na2SiO3, respectively. The molar ratio of Na2O, Al2O3, SiO2, and H2O is 50:2:5:1000. The active metal solution refers to the metal precursor solution, which is prepared from Cu(NO3)2·3H2O and ammonia water with a concentration of 25-28%. 2+ :NH 4+ =1:2.

[0082] The membrane reactor prepared under the above conditions was used as a substrate reaction with cyclohexanol and aniline. A 500 ml mixture of aniline and cyclohexanol with a molar ratio of 2:1 was prepared as the reaction raw material, with 325 g of aniline and 175 g of cyclohexanol. After 8 h, the reaction solution was collected in a collection tank and analyzed by gas chromatography.

[0083] The remaining implementation methods are the same as those in Examples 1 and 2.

[0084] Example 7

[0085] In step S3, the reaction temperature in the hydrothermal reactor is 60°C, the hydrothermal synthesis time is 24 hours, and the porous matrix coated with the LTA molecular sieve membrane obtained after the hydrothermal synthesis reaction is dried at 90~120°C.

[0086] The Na, Al, and Si sources used in the LTA molecular sieve membrane synthesis solution are NaOH, NaAlO2, and Na2SiO3, respectively. The molar ratio of Na2O, Al2O3, SiO2, and H2O is 50:2:5:1000. The active metal solution refers to the metal precursor solution, which is prepared from Cu(NO3)2·3H2O and ammonia water with a concentration of 25-28%. 2+ :NH 4+ =1:2.

[0087] The membrane reactor prepared under the above conditions was used as a substrate with o-nitrobenzyl alcohol and aniline. A 500 ml mixture of aniline and o-nitrobenzyl alcohol with a molar ratio of 2:1 was prepared as the reaction raw material, with 313 g of aniline and 258 g of o-nitrobenzyl alcohol. After 8 h, the reaction solution was collected in a collection tank and analyzed by gas chromatography.

[0088] The remaining implementation methods are the same as those in Examples 1 and 2.

[0089] Example 8

[0090] In step S3, the reaction temperature in the hydrothermal reactor is 60°C, the hydrothermal synthesis time is 24 hours, and the porous matrix coated with the LTA molecular sieve membrane obtained after the hydrothermal synthesis reaction is dried at 90~120°C.

[0091] The Na, Al, and Si sources used in the LTA molecular sieve membrane synthesis solution are NaOH, NaAlO2, and Na2SiO3, respectively. The molar ratio of Na2O, Al2O3, SiO2, and H2O is 50:2:5:1000. The active metal solution refers to the metal precursor solution, which is prepared from Cu(NO3)2·3H2O and ammonia water with a concentration of 25-28%. 2+ :NH 4+ =1:2.

[0092] The membrane reactor prepared under the above conditions was used as a substrate reaction with p-methylbenzyl alcohol and aniline. A 500 ml mixed solution of aniline and p-methylbenzyl alcohol with a molar ratio of 2:1 was prepared as the reaction raw material, with 303 g of aniline and 199 g of p-methylbenzyl alcohol. After 8 h, the reaction solution was collected in a collection tank and analyzed by gas chromatography.

[0093] The remaining implementation methods are the same as those in Examples 1 and 2.

[0094] Example 9

[0095] The precursor solution is a mixed solution of copper nitrate trihydrate and ethylenediamine; The membrane reactor used aniline and benzyl alcohol as the base reaction. A 500 ml mixed solution of aniline and benzyl alcohol with a molar ratio of 2:1 was prepared as the reaction raw material, with 326 g of aniline and 189 g of benzyl alcohol. The reaction temperature was set to 200℃ and the flow rate of the reaction solution was set to 0.1 ml / min. After 8 h, the reaction solution was collected in a collection tank and analyzed by gas chromatography.

[0096] The remaining implementation methods are the same as those in Examples 1 and 2.

[0097] Example 10

[0098] The precursor solution is a mixed solution of nickel nitrate hexahydrate and ammonia. The membrane reactor used aniline and benzyl alcohol as the base reaction. A 500 ml mixed solution of aniline and benzyl alcohol with a molar ratio of 2:1 was prepared as the reaction raw material, with 326 g of aniline and 189 g of benzyl alcohol. The reaction temperature was set to 200℃ and the flow rate of the reaction solution was set to 0.1 ml / min. After 8 h, the reaction solution was collected in a collection tank and analyzed by gas chromatography.

[0099] The remaining implementation methods are the same as those in Examples 1 and 2.

[0100] Examples 3 to 10 illustrate the N-alkylation reactions of various alcohols with aniline, demonstrating the reactor's activity with a wide range of alcohols. For example, the conversion rates of aliphatic alcohols described in Examples 4, 5, and 6 reach 60%–70%, indicating that the reactor effectively promotes the activation of secondary aliphatic alcohols. For aromatic alcohols, such as those shown in Example 3 (using aniline and benzyl alcohol as examples), the conversion rate of benzyl alcohol can reach over 70%. In Example 7, o-nitrobenzyl alcohol, where the nitro group is an electron-withdrawing group, achieves a conversion rate of 66.46% even with the electron-withdrawing group substituted on the benzyl alcohol. In Example 8, p-methylbenzyl alcohol, where the methyl group on the benzene ring acts as an electron-donating group, achieves a conversion rate of 70.66%. In Example 9, replacing the ammonia complex with ethylenediamine also demonstrates its activity with the substrate. In Example 10, replacing copper nitrate with nickel nitrate also demonstrates its activity with the substrate.

[0101] Table 1 Summary of Example Data

[0102] Example 11

[0103] In step S3, the reaction temperature in the hydrothermal reactor is 60°C, the hydrothermal synthesis time is 24 hours, and the porous matrix coated with the LTA molecular sieve membrane obtained after the hydrothermal synthesis reaction is dried at 90~120°C.

[0104] The Na, Al, and Si sources used in the LTA molecular sieve membrane synthesis solution are NaOH, NaAlO2, and Na2SiO3, respectively. The molar ratio of Na2O, Al2O3, SiO2, and H2O is 50:2:5:1000. The active metal solution refers to the metal precursor solution, which is prepared from Cu(NO3)2·3H2O and ammonia water with a concentration of 25-28%. 2+ :NH 4+ =1:2.

[0105] The membrane reactor prepared under the above conditions was used as a substrate with benzyl alcohol and 2-methyl-6-ethylaniline. A 500 ml mixed solution of 2-methyl-6-ethylaniline and benzyl alcohol with a molar ratio of 2:1 was prepared as the reaction raw material. 261 g of 2-methyl-6-ethylaniline and 155 g of benzyl alcohol were used. After 8 h, the reaction solution was collected in a collection tank and analyzed by gas chromatography.

[0106] The remaining implementation methods are the same as those in Examples 1 and 2.

[0107] Example 12

[0108] In step S3, the reaction temperature in the hydrothermal reactor is 60°C, the hydrothermal synthesis time is 24 hours, and the porous matrix coated with the LTA molecular sieve membrane obtained after the hydrothermal synthesis reaction is dried at 90~120°C.

[0109] The Na, Al, and Si sources used in the LTA molecular sieve membrane synthesis solution are NaOH, NaAlO2, and Na2SiO3, respectively. The molar ratio of Na2O, Al2O3, SiO2, and H2O is 50:2:5:1000. The active metal solution refers to the metal precursor solution, which is prepared from Cu(NO3)2·3H2O and ammonia water with a concentration of 25-28%. 2+ :NH 4+ =1:2.

[0110] The membrane reactor prepared under the above conditions was used as a substrate reaction with benzyl alcohol and p-methylaniline. A 500 ml mixed solution of p-methylaniline and benzyl alcohol with a molar ratio of 2:1 was prepared as the reaction raw material. 281 g of p-methylaniline and 143 g of benzyl alcohol were used. After 8 h, the reaction solution was collected in a collection tank and analyzed by gas chromatography.

[0111]

[0112] Table 2 Summary of Example Data

[0113] Using benzyl alcohol as a substrate, Examples 11 and 12 both contain aniline with an electron-donating group on the benzene ring. The electron-donating aniline has good reactivity with benzyl alcohol, and the conversion rate of benzyl alcohol is above 60%.

[0114] Example 13

[0115] Referring to Example 3, the only difference is that the temperature in step S3 is adjusted to 100°C, while all other conditions remain the same. The target product is N-phenylbenzylimine. Analysis and calculations show that the conversion rate of the target product is 47.74%, and the selectivity is 88.19%.

[0116] Example 14

[0117] Referring to Example 3, the only difference is that the temperature in step S3 is adjusted to 70°C; all other conditions are the same. The target product is N-phenylbenzylimine. Analysis and calculations show that the conversion rate of the target product is 52.67%, and the selectivity is 91.40%.

[0118] Example 15

[0119] Referring to Example 3, the only difference is that the temperature in step S3 is adjusted to 80°C; all other conditions are the same. The target product is N-phenylbenzylimine. Analysis and calculations show that the conversion rate of the target product is 47.29%, and the selectivity is 85.23%.

[0120] In the comparative examples, we used a fixed-bed device to catalyze the reaction of aniline and benzyl alcohol. The catalysts used were conventionally supported Cu / SiO2, CuMn / SiO2, CuFe / SiO2, CuNi / SiO2, CuZn / SiO2, and Cu / SiO2-AE, as shown in Table 3.

[0121] Table 3 Summary of the compared catalyst systems obtained

[0122] In the comparative examples below, a fixed-bed reactor was used to complete the reaction. All catalysts used were supported catalysts, with spherical SiO2 as the support. The main metal was Cu, and the auxiliary metal was one of Mn, Fe, Ni, or Zn. The precursors for both the main and auxiliary metals were corresponding nitrate solutions. The preparation method involved mixing the nitrate solutions of the main and auxiliary metals and adding them to sieved 20-40 mesh spherical SiO2. The mixture was ultrasonicated for 11 hours, impregnated for 12 hours, dried at 110℃, calcined at 500℃, and reduced in situ with H2 at 250℃. In another comparative example, the catalyst Cu / SiO2-AE was prepared by ammonia stripping. The precursor solution was prepared from Cu(NO3)2·3H2O and ammonia solution with a concentration of 25-28%. 2+ :NH 4+=1:2. The prepared precursor solution was added to sieved 20-40 mesh spherical SiO2 and impregnated for 5 hours. The impregnated catalyst was then evaporated to dryness at 50°C in a rotary evaporator and placed in an oven at 190°C overnight. Calcination was performed at 500°C, followed by in-situ reduction with H2 at 250°C.

[0123] Comparative Example 1

[0124] N-Phenylacetin was synthesized by the catalytic reaction of aniline and benzyl alcohol in a fixed-bed reactor. A 2:1 molar ratio (326 g aniline and 189 g benzyl alcohol) mixed solution was prepared as the reactants in 500 ml of the reactor. 6 g of 20-40 mesh Cu / SiO2 (CAT-1) catalyst was charged into the fixed-window reactor. The reaction temperature was set at 200℃, and the reactant flow rate was set at 0.1 ml / min. After 8 hours, the reaction solution was collected and analyzed by gas chromatography. The conversion rate of the target product was calculated to be 8.66%, and the selectivity was 91.68%.

[0125] Comparative Example 2

[0126] Referring to Comparative Example 1, the only difference was that the catalyst was changed to Cu / SiO2-AE (CAT-2), while all other conditions remained the same. The target product was N-phenylbenzylimine. Analysis and calculations showed that the conversion rate of the target product was 35.53%, and the selectivity was 94.7%.

[0127] Comparative Example 3

[0128] Referring to Comparative Example 1, the only difference was that the catalyst was changed to CuFe / SiO2 (CAT-3), while all other conditions remained the same. The target product was N-phenylbenzylimine. Analysis and calculations showed that the conversion rate of the target product was 29.94%, and the selectivity was 88.32%.

[0129] Comparative Example 4

[0130] Referring to Comparative Example 1, the only difference was that the catalyst was changed to CuMg / SiO2 (CAT-4), while all other conditions remained the same. The target product was N-phenylbenzylimine. Analysis and calculations showed that the conversion rate of the target product was 5.21%, and the selectivity was 10.92%.

[0131] Comparative Example 5

[0132] Referring to Comparative Example 1, the only difference was that the catalyst was changed to CuZn / SiO2 (CAT-5), while all other conditions remained the same. The target product was N-phenylbenzylimine. Analysis and calculations showed that the conversion rate of the target product was 17.48%, and the selectivity was 83.4%.

[0133] Comparative Example 6

[0134] Referring to Comparative Example 1, the only difference was that the catalyst was changed to CuMn / SiO2 (CAT-6), while all other conditions remained the same. The target product was N-phenylbenzylimine. Analysis and calculations showed that the conversion rate of the target product was 27.95%, and the selectivity was 93.32%.

[0135] Compared to the conventional fixed-bed reaction, the conversion rates of alcohols were significantly improved in the designed membrane reactor examples, promoting the forward reaction and conversion to imines. This improvement was also reflected in the selectivity of imines, with an increasingly higher proportion of imines among the byproducts, leading to increased imine selectivity. The increased conversion rate indicates a forward shift in the reaction, attributed to the in-situ removal of water within the membrane reactor. This demonstrates the effectiveness of the membrane reactor in disrupting the thermodynamic equilibrium of this reaction.

[0136] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0137] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0138] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0139] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0140] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0141] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A bifunctional catalytic membrane reaction apparatus for catalyzing the dehydration condensation of alcoholamines to synthesize imines, the reaction apparatus comprising an inner cavity and an outer cavity, the gap between the inner cavity and the outer cavity being used to fill a mixed solution of amine and alcohol; The inner cavity comprises, from the inside out: a porous substrate, an LTA molecular sieve membrane bonded to the surface of the porous substrate, and an active metal layer bonded to the surface of the LTA molecular sieve membrane, characterized in that the inner cavity is prepared according to the following steps: S1. Provides a porous matrix, a first modification solution, an LTA molecular sieve membrane synthesis solution, and an active metal layer synthesis solution; S2. The porous matrix is ​​placed in the first modification solution for modification to obtain a modified porous matrix; S3. The modified porous matrix is ​​placed in the LTA molecular sieve membrane synthesis solution and then placed together in a hydrothermal reactor to carry out a hydrothermal synthesis reaction, and the reaction yields a porous matrix coated with the LTA molecular sieve membrane. S4. The porous substrate coated with the LTA molecular sieve membrane is placed in the active metal layer synthesis solution for surface impregnation to obtain the porous substrate coated with the active metal-loaded LTA molecular sieve membrane, i.e., the inner cavity.

2. The bifunctional catalytic membrane reaction apparatus for catalyzing the dehydration condensation of alcoholamines to synthesize imines according to claim 1, characterized in that, The porous matrix is ​​a hollow tubular α-Al2O3; the LTA molecular sieve membrane is a hydrophilic LTA molecular sieve membrane used to selectively separate water vapor formed during the reaction; the active metal layer is a copper-based metal layer used to catalyze the reaction of amines and alcohols to form imines.

3. The bifunctional catalytic membrane reaction apparatus for catalyzing the dehydration condensation of alcoholamines to synthesize imines according to claim 2, characterized in that, The hollow tubular α-Al2O3 has an outer diameter of 10~12 mm, an inner diameter of 6~9 mm, a length of 10~12 cm, and a pore size of 1.0~15 µm.

4. The bifunctional catalytic membrane reaction apparatus for catalyzing the dehydration condensation of alcoholamines to synthesize imines according to claim 1, characterized in that, In step S1, the first modified solution is a mixture of APTES and toluene.

5. The bifunctional catalytic membrane reaction apparatus for catalyzing the dehydration condensation of alcoholamines to synthesize imines according to claim 1, characterized in that, In step S3, the reaction temperature in the hydrothermal reactor is 60~100℃, the hydrothermal synthesis time is 10~24 hours, and the porous matrix coated with the LTA molecular sieve membrane obtained after the hydrothermal synthesis reaction is dried at 90~120℃.

6. The bifunctional catalytic membrane reaction apparatus for catalyzing the dehydration condensation of alcoholamines to synthesize imines according to claim 1, characterized in that, In step S4, the active metal layer solution refers to the precursor solution of the active metal layer, which is a mixed solution of copper nitrate trihydrate and one of ammonia, ethylenediamine, ethanolamine, and mannitol, or a mixed solution of nickel nitrate hexahydrate and ammonia.

7. The bifunctional catalytic membrane reaction apparatus for catalyzing the dehydration condensation of alcoholamines to synthesize imines according to claim 1, characterized in that, In step S4, the surface impregnation involves vertically inserting a porous substrate coated with an LTA molecular sieve membrane into a glass bottle containing the active metal layer synthesis solution, maintaining the impregnation state for 30-60 seconds, and then vertically pulling it out after impregnation. This impregnation process is repeated 10-20 times.

8. A method for preparing imine using the reaction apparatus of claim 1, characterized in that, The method includes the following steps: i) The gap between the inner and outer cavities of the reaction apparatus is filled with a mixed solution of alcohol and amine. The mixed solution of alcohol and amine is injected into the gap between the inner and outer cavities by an injection pump. N2 is turned on inside the inner cavity to blow away the water vapor generated in the reaction. ii) Heat the reaction apparatus to 150°C-250°C to obtain an imine.

9. The method as described in claim 8, characterized in that, The flow rate of the syringe pump described in step i) is controlled between 0.01 ml / min and 2 ml / min.

10. The method as described in claim 8, characterized in that, In step i), the molar ratio of alcohol to amine in the mixed solution of alcohol and amine is 1:1 to 1:10.

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