Membrane permeation-pressurized rectification coupling process of diisopropylamine-isopropanol ternary water-containing system

Abstract

The invention discloses a membrane permeation-pressurized rectification coupling process of a diisopropylamine-isopropanol ternary water-containing system, which comprises the following steps: primarily separating by an azeotropic rectification tower to obtain a diisopropylamine-isopropanol-water homogeneous ternary mixture at the tower top, and cooling by a cooler to obtain a ternary mixture; conveying to a membrane dehydration assembly to selectively remove moisture; and the dehydrated diisopropylamine-isopropanol mixture enters a pressurized rectifying tower, so that high-purity recovery of diisopropylamine and isopropanol is realized. The process does not need to introduce a third component, equipment is simple, the recovery purity is high, meanwhile, chemical pollution is avoided, and the environmental protection requirement is met.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical production, and in particular relates to a membrane permeation-pressure distillation coupling process for a diisopropylamine-isopropyl alcohol ternary aqueous system. Background Art

[0002] Global energy demand is positively correlated with economic development. However, a single energy supply structure poses a severe challenge to sustainable social development. Furthermore, the lag in existing environmental protection technologies has led to enormous resource waste and environmental pollution. For developing countries, how to effectively control environmental pollution while achieving rapid economic growth remains an unresolved challenge. These energy and environmental issues are closely related to separation and purification processes. Therefore, developing environmentally friendly and efficient separation and purification technologies to replace outdated processes is crucial for building sustainable economic, social, and environmental systems.

[0003] Organic amines are a class of organic compounds containing amino groups, which can achieve functional diversity through adjustments in carbon chain length and substituent types. These unique physical and chemical properties make organic amines indispensable synthetic raw materials and functional additives in a wide range of fields, with widespread application in the chemical, pharmaceutical, agricultural, and environmental protection sectors. However, this has also led to a surge in production. Currently, the industrial production of organic amines inevitably produces a ternary mixture of diisopropylamine, isopropyl alcohol, and water due to the presence of lower alcohols and water in the raw materials, the formation of reaction byproducts, and the limitations of separation technologies.

[0004] However, due to the azeotropic nature of the diisopropylamine-isopropyl alcohol-water ternary mixture, simple distillation cannot break through thermodynamic equilibrium limitations, and even multi-stage distillation is difficult to completely purify. Furthermore, the similar polarity of diisopropylamine and isopropyl alcohol results in extremely low selectivity for traditional extractants, while the complete miscibility of the mixture makes liquid-liquid demixing difficult, further limiting the efficiency of separation methods such as extraction or adsorption. Therefore, efficient separation and resource recovery of diisopropylamine and isopropyl alcohol must be achieved through the coupling of multiple processes or novel separation materials.

[0005] Several methods for treating the diisopropylamine-isopropanol-water ternary mixture have been developed, such as pressure swing distillation, azeotropic distillation, and extractive distillation. Pressure swing distillation adjusts the relative volatility of the components by changing the system pressure, breaking the azeotropic point limit, but requires two or more towers to be stacked to maintain different pressures and temperatures, and the process is complicated. Azeotropic distillation introduces an azeotrope to form a new azeotrope, but the matching of the azeotrope is difficult, the recovery process is complicated, and there is a risk of secondary contamination. Extractive distillation selectively enhances the volatility difference between components by adding a high-boiling point solvent, but an additional solvent recovery tower is required, resulting in increased equipment, and the introduction of a third component may contaminate the product.

[0006] Therefore, there is an urgent need to develop a process that is efficient, simple in equipment and meets environmental requirements to better separate the diisopropylamine-isopropyl alcohol ternary aqueous system. Summary of the Invention

[0007] In order to solve the above technical problems, a diisopropylamine-isopropyl alcohol ternary aqueous system separation process with high efficiency, simple equipment and environmental protection requirements is developed. The present application provides a membrane osmosis-pressure distillation coupling process for the diisopropylamine-isopropyl alcohol ternary aqueous system.

[0008] On the one hand, the present application provides a membrane permeation-pressure distillation coupling process for a diisopropylamine-isopropyl alcohol ternary aqueous system, comprising the following steps: S1, sending the mixture containing diisopropylamine-isopropyl alcohol-water into an azeotropic distillation tower for azeotropic distillation, obtaining a homogeneous ternary mixture of diisopropylamine-isopropyl alcohol-water at the top of the tower, and sending it into a cooler for cooling to obtain a ternary mixture; S2. removing water by a membrane dehydration assembly, wherein the membrane used in the membrane dehydration assembly is at least one of a polyimide membrane and a NaA molecular sieve membrane, to obtain a diisopropylamine-isopropyl alcohol mixture; S3, sending the diisopropylamine-isopropyl alcohol mixture obtained in S2 into a pressure distillation tower, and after pressure distillation, obtaining the isopropyl alcohol product at the top of the pressure distillation tower, and obtaining the diisopropylamine product in the bottom of the pressure distillation tower.

[0009] Through the above technical solution, the present application adopts the combined use of an azeotropic distillation tower, a membrane dehydration component and a pressurized distillation tower to improve the separation efficiency while simplifying the equipment.

[0010] Through the above technical solution, the present application purifies the diisopropylamine-isopropyl alcohol ternary aqueous system, and can simultaneously purify diisopropylamine and isopropyl alcohol products without adding a third component, which is an environmentally friendly separation technology.

[0011] Preferably, in S2, the membrane used in the membrane dehydration component is a double-layer membrane.

[0012] Preferably, in S2, the polyimide film is an organic silicone-modified polyimide film.

[0013] Preferably, in S2, the membrane used in the membrane dehydration assembly is a membrane in which an organic silicone-modified polyimide membrane and a molecular sieve membrane are used in series.

[0014] Through the above technical solution, the present application adopts a NaA molecular sieve membrane and an organic silicone modified polyimide membrane in series treatment, which can improve the selectivity for water molecules, inhibit the osmotic loss of isopropyl alcohol, and improve the retention rate of isopropyl alcohol while improving the dehydration efficiency.

[0015] Preferably, in said S1, the obtained ternary mixture is sent to an evaporator for evaporation to obtain a gaseous ternary mixture, and then the gaseous ternary mixture is sent to a superheater for heating.

[0016] Preferably, in S1, the operating temperature of the evaporator is 110-115°C, and the operating temperature of the superheater is 115-120°C.

[0017] Through the above technical solution, the present application adopts the method of evaporation first and then superheating to ensure that the ternary mixture is in the form of gaseous membrane components, avoiding liquid water or organic matter clogging the membrane pores or reducing the mass transfer efficiency, thereby improving the dehydration efficiency.

[0018] Preferably, in S1, the operating pressure of the azeotropic distillation tower is 0.3-0.5 MPa, the tower top temperature is 110-120°C, the number of plates is 15-20, the reflux ratio is 1-2, and the operating temperature of the cooler is 70-110°C.

[0019] Through the above-mentioned technical solution, this application adopts a specific pressure and temperature for azeotropic distillation, breaking the limitations of the ternary azeotropic system, concentrating the organic phase and reducing the water content (diisopropylamine and isopropyl alcohol, due to their high volatility, rise to the top of the tower with the steam), so that the overhead distillate forms a homogeneous ternary mixture, creating suitable conditions for subsequent membrane dehydration (reducing membrane fouling and pore blockage, avoiding membrane material swelling and structural deformation caused by high water content environment and insufficient transmembrane pressure difference, thereby improving dehydration efficiency), thereby solving the problems of high water content and azeotropic interference, and eliminating the need for multi-tower operation and designing pressure changes based on the composition of the ternary mixture, thereby simplifying the process flow. The homogeneous ternary mixture condensed at the top of the tower is partially refluxed to maintain the gas-liquid equilibrium and thermodynamic equilibrium in the tower, improving separation accuracy.

[0020] Preferably, in S2, the operating pressure of the membrane dehydration component is 0.3-0.5 MPa, and the feed temperature is 110-115°C.

[0021] Through the above technical solution, this application adopts pressure-temperature coordinated optimization, which can accelerate the diffusion rate of water molecules while ensuring sufficient transmembrane pressure difference, reduce the vacuum requirement on the permeate side of the membrane component, and thus reduce the subsequent distillation load.

[0022] Preferably, in S3, the operating pressure of the pressurized distillation tower is 0.5-1.5 MPa, the top temperature is 150-160° C., the bottom temperature is 180-190° C., the number of plates is 20-25, and the reflux ratio is 1.2-1.5.

[0023] Through the above technical solution, this application adopts a pressurized distillation process. By controlling the pressure and the top and bottom temperatures of the tower, the relative volatility of diisopropylamine and isopropyl alcohol is increased, the distillation time is shortened, and the reflux ratio is reduced, thereby reducing energy consumption. The isopropyl alcohol condensed at the top of the tower is partially refluxed to maintain the balance of components within the tower, enhance gas-liquid mass transfer, reduce the entrainment of high-boiling point components, and ensure the high-purity recovery of isopropyl alcohol.

[0024] Preferably, the diisopropylamine recovered by this method has a purity of 98 wt % or more, and the isopropyl alcohol recovered has a purity of 96 wt % or more.

[0025] Through the above technical solution, the present application achieves high-purity recovery of diisopropylamine-isopropyl alcohol, avoids the discharge of industrial waste liquid into the environment, reduces pollution, and realizes the reuse of resources.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. This application uses a combination of an azeotropic distillation tower, a membrane dehydration component, and a pressurized distillation tower to improve separation efficiency while simplifying the equipment; 2. This application uses specific pressure and temperature for azeotropic distillation, breaking the limitations of the ternary azeotropic system, concentrating the organic phase and reducing the water content, so that the overhead distillate forms a homogeneous ternary mixture, creating suitable conditions for subsequent membrane dehydration, thereby solving the problems of high water content and azeotropic interference and simplifying the process flow; 3. The use of a molecular sieve membrane and an organosilicone-modified polyimide membrane in series can improve the selectivity for water molecules, inhibit the permeation loss of isopropyl alcohol, and improve the retention rate of isopropyl alcohol while increasing the dehydration efficiency; 4. This application adopts the method of evaporation first and then superheating to ensure that the ternary mixture enters the membrane module in gaseous form, avoiding liquid water or organic matter from clogging the membrane pores or reducing mass transfer efficiency, thereby improving dehydration efficiency; 5. This application achieves high-purity recovery of diisopropylamine-isopropyl alcohol, avoids the discharge of industrial waste liquid into the environment, reduces pollution, and realizes resource reuse. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the membrane permeation-pressure distillation coupling process flow of the diisopropylamine-isopropyl alcohol ternary aqueous system of the present application.

[0028] In the figure, T-1, azeotropic distillation tower; E-1, azeotropic tower top condenser; E-2, azeotropic tower kettle reboiler; E-3, azeotropic tower top cooler; E-4, evaporator; E-5, superheater; M-1, membrane dehydration component; E-6, permeate condenser; T-2, pressurized distillation tower; E-7, pressurized distillation tower top condenser; E-8, pressurized tower kettle reboiler. DETAILED DESCRIPTION

[0029] The applicant states that while the above-described embodiments illustrate the present process, the present invention is not limited to the above-described steps, nor does it imply that the present invention must rely on the above-described steps for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for the raw materials used, additions of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

[0030] The present application provides a membrane permeation-pressure distillation coupled process for a diisopropylamine-isopropyl alcohol ternary aqueous system, comprising the following steps: S1. Sending a mixture containing diisopropylamine-isopropyl alcohol-water into an azeotropic distillation tower for azeotropic distillation, the azeotropic distillation tower has an operating pressure of 0.3-0.5 MPa, a tower top temperature of 110-120° C., 15-20 plates, and a reflux ratio of 1-2; obtaining a homogeneous ternary mixture of diisopropylamine-isopropyl alcohol-water at the tower top, and sending the mixture into a cooler for cooling to obtain a ternary mixture; S2. Dehydration is performed by a membrane dehydration assembly, wherein the membrane used in the membrane dehydration assembly is a double-layer polyimide membrane, to obtain a diisopropylamine-isopropyl alcohol mixture. The operating pressure of the membrane dehydration assembly is 0.3-0.5 MPa, and the feed temperature is 110-115° C. S3. The diisopropylamine-isopropyl alcohol mixture obtained in S2 is fed into a pressure distillation tower, wherein the operating pressure of the pressure distillation tower is 0.5-1.5 MPa, the tower top temperature is 150-160° C., the tower bottom temperature is 180-190° C., the number of tower plates is 20-25, and the reflux ratio is 1.2-1.5; after pressure distillation, the isopropyl alcohol product is obtained at the top of the pressure distillation tower, and the diisopropylamine product is obtained in the bottom of the pressure distillation tower.

[0031] The raw materials used in the examples of this application can be obtained from commercial sources, including: Polyimide film, thickness 10 μm, Forsman Technology (Beijing) Co., Ltd. NaA molecular sieve membrane, thickness 10 μm, Jiangsu Jiutian High-Tech Co., Ltd.; Bis-dimethylsiloxane, Jiangxi Hongshi New Materials Co., Ltd.; N-Methylpyrrolidone, Shanghai Jizhi Biochemical Technology Co., Ltd. Specific embodiments

[0032] Example 1 S1. A mixture consisting of 12.49 wt % diisopropylamine, 31.14 wt % isopropyl alcohol, and 56.35 wt % water, with the remainder being impurities, is fed into an azeotropic distillation column for azeotropic distillation. The feed rate of the diisopropylamine-isopropyl alcohol-water mixture is 1500 kg / h. The azeotropic distillation column operates at a pressure of 0.4 MPa, 20 plates, a top temperature of 110° C., and a reflux ratio of 1. A mixed vapor of diisopropylamine-isopropyl alcohol-water is obtained at the top of the column and is cooled in a cooler at 90° C. to obtain a ternary mixture consisting of 26.37 wt % diisopropylamine, 61.16 wt % isopropyl alcohol, and 12.45 wt % water. S2. The cooled ternary mixture is introduced into a membrane dehydration assembly to remove moisture. The membrane dehydration assembly operates at a pressure of 0.3 MPa, uses a double-layer polyimide membrane, and has a feed temperature of 110°C. The organic component after dehydration is composed of 31.84 wt% diisopropylamine, 63.04 wt% isopropyl alcohol, and 5.12 wt% water. S3. After membrane dehydration, the product enters a pressurized distillation tower with an operating pressure of 1 MPa, 20 plates, a top temperature of 156°C, a bottom temperature of 186°C, and a reflux ratio of 1.5. Diisopropylamine with a purity of 98.83 wt% was obtained in the bottom of the tower, with a yield of 91.94%. Isopropyl alcohol with a purity of 96.36 wt% was obtained at the top of the tower, with a yield of 76.52%.

[0033] Example 2 S1. A mixture consisting of 40.05 wt% diisopropylamine, 12.32 wt% isopropyl alcohol, 47.62 wt% water, and the remainder being impurities is fed into an azeotropic distillation column for azeotropic distillation. The feed rate of the diisopropylamine-isopropyl alcohol-water mixture is 1500 kg / h, the operating pressure of the azeotropic distillation column is 0.5 MPa, the number of plates is 15, the top temperature is 120°C, and the reflux ratio is 1.5. A mixed vapor of diisopropylamine-isopropyl alcohol-water is obtained at the top of the column and fed into a cooler for cooling. The cooler is operated at 70°C to obtain a ternary mixture. The mass composition of the ternary mixture is 64.75 wt% diisopropylamine, 19.86 wt% isopropyl alcohol, and 15.39 wt% water. S2. The cooled ternary mixture is introduced into a membrane dehydration assembly to remove moisture. The membrane dehydration assembly operates at a pressure of 0.4 MPa, uses a double-layer polyimide membrane, and has a feed temperature of 115°C. The organic component after dehydration is composed of 74.36 wt% diisopropylamine, 20.56 wt% isopropyl alcohol, and 5.08 wt% water. S3. After membrane dehydration, the product enters a pressurized distillation tower with an operating pressure of 0.5 MPa, 25 plates, a top temperature of 150°C, a bottom temperature of 180°C, and a reflux ratio of 1.2. Diisopropylamine with a purity of 98.90 wt% was obtained in the bottom of the tower, with a yield of 92.44%. Isopropyl alcohol with a purity of 96.00 wt% was obtained at the top of the tower, with a yield of 83.10%.

[0034] Example 3 S1. A mixture consisting of 55.19wt% diisopropylamine, 15.95wt% isopropyl alcohol, 28.84wt% water, and the remainder being impurities is fed into an azeotropic distillation column for azeotropic distillation. The feed rate of the diisopropylamine-isopropyl alcohol-water mixture is 1500kg / h, the operating pressure of the azeotropic distillation column is 0.3MPa, the number of plates is 20, the top temperature is 110°C, and the reflux ratio is 2. A mixed vapor of diisopropylamine-isopropyl alcohol-water is obtained at the top of the column and fed into a cooler for cooling. The cooler is operated at a temperature of 110°C to obtain a ternary mixture. The mass composition of the ternary mixture is 65.74wt% diisopropylamine, 18.79wt% isopropyl alcohol, and 15.47wt% water. S2. The cooled ternary mixture is introduced into a membrane dehydration assembly to remove moisture. The membrane dehydration assembly operates at a pressure of 0.5 MPa, uses a double-layer polyimide membrane, and has a feed temperature of 115°C. The organic component after dehydration is composed of 75.77 wt% diisopropylamine, 19.32 wt% isopropyl alcohol, and 4.91 wt% water. S3. After membrane dehydration, the product enters a pressurized distillation tower with an operating pressure of 1.5 MPa, 20 trays, a top temperature of 160°C, a bottom temperature of 190°C, and a reflux ratio of 1.5. Diisopropylamine with a purity of 98.90 wt% was obtained in the bottom of the tower, with a yield of 91.76%. Isopropyl alcohol with a purity of 96.00 wt% was obtained at the top of the tower, with a yield of 80.98%.

[0035] As can be seen from Examples 1-3, the present application adopts a three-stage synergistic mechanism of thermodynamic regulation (azeotropic distillation), mass transfer enhancement (membrane permeation), and kinetic optimization (pressurized distillation), which breaks through the separation bottleneck of the diisopropylamine-isopropyl alcohol-water ternary system, improves the separation efficiency, simplifies the equipment, and is conducive to the separation of different mixture components containing diisopropylamine-isopropyl alcohol-water. The bottom of the azeotropic distillation tower makes the recovery rate of diisopropylamine and isopropyl alcohol more than 99%.

[0036] Example 4 The difference between this embodiment and embodiment 1 is that in this embodiment, the double-layer polyimide membrane is replaced by a double-layer NaA molecular sieve membrane; After dehydration, the organic mass composition was 32.13 wt% diisopropylamine, 64.84 wt% isopropyl alcohol, and 3.03 wt% water. Diisopropylamine with a purity of 99.36 wt% was obtained in the bottom of the column, with a yield of 96.54%. Isopropyl alcohol with a purity of 98.74 wt% was obtained at the top of the column, with a yield of 78.14%.

[0037] It can be seen from Examples 1 and 4 that the NaA molecular sieve membrane can improve the water removal effect of the membrane dehydration component, thereby improving the recovery purity of diisopropylamine and isopropyl alcohol.

[0038] Example 5 The difference between this embodiment and embodiment 1 is that in this embodiment, the double-layer polyimide film is replaced by a double-layer organosilicon-modified polyimide film; The organosilicone-modified polyimide film is prepared by the following preparation method: The polyimide film is dried in an oven at 60°C for 2 hours, and then dimethicone and N-methylpyrrolidone are added and soaked for 30-60 minutes. The film is then heated in a stepwise manner to 250-300°C and heated for 2-3 hours. The film is then cooled to room temperature and dried to obtain an organosilicone-modified polyimide film. After dehydration, the organic mass composition was 28.73 wt% diisopropylamine, 66.39 wt% isopropyl alcohol, and 4.88 wt% water. Diisopropylamine with a purity of 99.07 wt% was obtained in the bottom of the column, with a yield of 96.44%. Isopropyl alcohol with a purity of 96.85 wt% was obtained at the top of the column, with a yield of 89.39%.

[0039] It can be seen from Examples 1 and 5 that the organosilicone-modified polyimide membrane can improve the interception effect of the membrane dehydration component on isopropyl alcohol, thereby improving the recovery rate of isopropyl alcohol.

[0040] Example 6 The difference between this embodiment and embodiment 1 is that in this embodiment, the double-layer polyimide membrane is replaced by a polyimide membrane and a NaA molecular sieve membrane used in series; After dehydration, the organic mass composition was 32.65 wt% diisopropylamine, 65.19 wt% isopropyl alcohol, and 2.16 wt% water. Diisopropylamine with a purity of 99.45 wt% was obtained in the bottom of the column, with a yield of 96.58%. Isopropyl alcohol with a purity of 99.06 wt% was obtained at the top of the column, with a yield of 77.33%.

[0041] Example 7 The difference between this embodiment and embodiment 4 is that in this embodiment, the double-layer NaA molecular sieve membrane is replaced by a membrane in which a NaA molecular sieve membrane and an organosilicone-modified polyimide membrane are used in series; After dehydration, the organic mass composition was 28.51 wt% diisopropylamine, 69.46 wt% isopropyl alcohol, and 2.03 wt% water. Diisopropylamine with a purity of 99.56 wt% was obtained in the bottom of the column, with a yield of 96.85%. Isopropyl alcohol with a purity of 99.19 wt% was obtained at the top of the column, with a yield of 94.62%.

[0042] It can be seen from Examples 1 and 6-7 that selective dehydration by a NaA molecular sieve membrane followed by interception of isopropyl alcohol by an organosilicone-modified polyimide membrane can improve the selectivity for water molecules, inhibit the osmotic loss of isopropyl alcohol, and improve the retention rate of isopropyl alcohol while improving the dehydration efficiency.

[0043] Example 8 S1. A mixture consisting of 12.49 wt% diisopropylamine, 31.14 wt% isopropyl alcohol, and 56.35 wt% water, with the remainder being impurities, is fed into an azeotropic distillation column for azeotropic distillation. The feed rate of the diisopropylamine-isopropyl alcohol-water mixture is 1500 kg / h. The azeotropic distillation column operates at a pressure of 0.4 MPa, 20 stages, a top temperature of 110°C, and a reflux ratio of 1. A diisopropylamine-isopropyl alcohol-water vapor mixture is obtained at the top of the column and is cooled in a cooler operating at 90°C to obtain a ternary mixture consisting of 26.37 wt% diisopropylamine, 61.16 wt% isopropyl alcohol, and 12.45 wt% water. The ternary mixture is then evaporated in an evaporator operating at 110°C to obtain a vapor-phase ternary mixture. The vapor-phase ternary mixture is then heated in a superheater operating at 120°C. S2. The cooled ternary mixture is introduced into a membrane dehydration assembly to remove moisture. The membrane dehydration assembly operates at a pressure of 0.3 MPa. The membrane used in the membrane dehydration assembly is a NaA molecular sieve membrane and an organosilicone-modified polyimide membrane connected in series. The feed temperature is 110°C. After dehydration, the organic component mass composition is 27.60 wt% diisopropylamine, 70.57 wt% isopropyl alcohol, and 1.83 wt% water. S3. After membrane dehydration, the product enters a pressurized distillation tower with an operating pressure of 1 MPa, 20 trays, a top temperature of 156°C, a bottom temperature of 186°C, and a reflux ratio of 1.5. Diisopropylamine with a purity of 99.79 wt% was obtained in the bottom of the tower, with a yield of 97.23%. Isopropyl alcohol with a purity of 99.71 wt% was obtained at the top of the tower, with a yield of 99.69%.

[0044] Example 9 The difference between this embodiment and embodiment 9 is that the operating temperature of the evaporator in this embodiment is 115°C; After dehydration, the organic mass composition was 27.64 wt% diisopropylamine, 70.55 wt% isopropyl alcohol, and 1.81 wt% water. Diisopropylamine with a purity of 99.84 wt% was obtained in the bottom of the column, with a yield of 97.60%. Isopropyl alcohol with a purity of 99.75 wt% was obtained at the top of the column, with a yield of 99.90%.

[0045] Example 10 The difference between this embodiment and embodiment 10 is that the operating temperature of the superheater in this embodiment is 115°C; After dehydration, the organic mass composition was 27.65 wt% diisopropylamine, 70.56 wt% isopropyl alcohol, and 1.79 wt% water. Diisopropylamine with a purity of 99.9 wt% was obtained in the bottom of the column, with a yield of 97.66%. Isopropyl alcohol with a purity of 99.8 wt% was obtained at the top of the column, with a yield of 99.94%.

[0046] As can be seen from Examples 1 and 8-10, evaporating and superheating the cooled gas-liquid mixed phase can ensure that the ternary mixture is in a gaseous form and passes through the membrane assembly, thereby preventing liquid water or organic matter from clogging the membrane pores or reducing the mass transfer efficiency, improving the dehydration efficiency, and thereby improving the recovery purity and yield of isopropyl alcohol and diisopropylamine.

[0047] The preferred embodiments of the present invention are described in detail above. However, the present invention includes but is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0048] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0049] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A membrane permeation-pressure distillation coupling process for a diisopropylamine-isopropyl alcohol ternary aqueous system, characterized in that: The following steps are involved: S1, sending the mixture containing diisopropylamine-isopropyl alcohol-water into an azeotropic distillation tower for azeotropic distillation, obtaining a homogeneous ternary mixture of diisopropylamine-isopropyl alcohol-water at the top of the tower, and sending it into a cooler for cooling to obtain a ternary mixture; S2. removing water by a membrane dehydration assembly, wherein the membrane used in the membrane dehydration assembly is at least one of a polyimide membrane and a NaA molecular sieve membrane, to obtain a diisopropylamine-isopropyl alcohol mixture; S3, sending the diisopropylamine-isopropyl alcohol mixture obtained in S2 into a pressure distillation tower, and after pressure distillation, obtaining the isopropyl alcohol product at the top of the pressure distillation tower, and obtaining the diisopropylamine product in the bottom of the pressure distillation tower.

2. The membrane permeation-pressure distillation coupled process for a diisopropylamine-isopropyl alcohol ternary aqueous system according to claim 1, characterized in that: In S2, the membrane used in the membrane dehydration component is a double-layer membrane.

3. The membrane permeation-pressure distillation coupled process for a diisopropylamine-isopropyl alcohol ternary aqueous system according to claim 1, characterized in that: In the above-mentioned S2, the polyimide film is an organic silicone-modified polyimide film.

4. The membrane permeation-pressure distillation coupled process for a diisopropylamine-isopropyl alcohol ternary aqueous system according to claim 1, characterized in that: In the above S2, the membrane used in the membrane dehydration assembly is a membrane composed of an organic silicone-modified polyimide membrane and a NaA molecular sieve membrane connected in series.

5. The membrane permeation-pressure distillation coupled process for a diisopropylamine-isopropyl alcohol ternary aqueous system according to claim 1, characterized in that: In S1, the obtained ternary mixture is sent to an evaporator for evaporation to obtain a gaseous ternary mixture, and then the gaseous ternary mixture is sent to a superheater for heating.

6. The membrane permeation-pressure distillation coupled process for a diisopropylamine-isopropyl alcohol ternary aqueous system according to claim 5, characterized in that: In S1, the operating temperature of the evaporator is 110-115°C, and the operating temperature of the superheater is 115-120°C.

7. The membrane permeation-pressure distillation coupled process for a diisopropylamine-isopropyl alcohol ternary aqueous system according to claim 1, characterized in that: In S1, the operating pressure of the azeotropic distillation tower is 0.3-0.5 MPa, the tower top temperature is 110-120° C., the number of tower plates is 15-20, the reflux ratio is 1-2, and the operating temperature of the cooler is 70-110° C.

8. The membrane permeation-pressure distillation coupled process for a diisopropylamine-isopropyl alcohol ternary aqueous system according to claim 1, characterized in that: In S2, the operating pressure of the membrane dehydration component is 0.3-0.5 MPa, and the feed temperature is 110-115°C.

9. The membrane permeation-pressure distillation coupled process for a diisopropylamine-isopropyl alcohol ternary aqueous system according to claim 1, characterized in that: In S3, the operating pressure of the pressurized distillation tower is 0.5-1.5 MPa, the tower top temperature is 150-160° C., the tower bottom temperature is 180-190° C., the number of tower plates is 20-25, and the reflux ratio is 1.2-1.

5.

10. The membrane permeation-pressure distillation coupled process for a diisopropylamine-isopropyl alcohol ternary aqueous system according to claim 1, characterized in that: In S3, the recovered diisopropylamine separated by this method has a purity of more than 98 wt %, and the recovered isopropyl alcohol has a purity of more than 96 wt %.

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