Membrane reaction-separation integrated system and method for phenol production process

Abstract

The invention discloses a membrane reaction-separation integrated system and method for phenol production, and belongs to the technical field of chemical process and equipment. Aiming at the problems of low mass transfer efficiency, complex separation process, huge equipment and the like in the traditional cumene oxidation method, the system adopts hollow fiber membrane contactors which are connected in series; the integrated operation of oxidation, decomposition and extraction is realized through three stages: in the first stage, cumene and oxygen are in countercurrent contact in a hydrophobic porous hollow fiber membrane reactor and are efficiently oxidized to generate cumene hydroperoxide; in the second stage, cumyl hydroperoxide and sulfuric acid are decomposed into phenol and acetone through a membrane reactor; in the third stage, directional enrichment of phenol from a sulfuric acid phase to an organic extraction agent is realized by utilizing a membrane extractor, and meanwhile, sulfuric acid is recovered. By strengthening gas-liquid / liquid-liquid interface mass transfer, the reaction rate and selectivity are improved, by-products and phase separation energy consumption are reduced, equipment is compact, production is easy to amplify, and the method has the advantages of flow simplification, cost reduction, environmental friendliness and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of phenol production, and particularly relates to a membrane reaction-separation integrated system and method for the phenol production process. Background Art

[0002] Phenol, as an important basic organic chemical raw material, is widely used in multiple industrial fields such as plastics, synthetic fibers, pharmaceuticals, and dyes. Currently, the cumene hydroperoxide method is one of the main methods for producing phenol. This process mainly includes three steps: the oxidation of cumene to form cumene hydroperoxide, the acid-catalyzed decomposition of cumene hydroperoxide to form phenol and acetone, and the refining process of the final product. However, the traditional production process has problems such as insufficient mixing of oxygen and cumene and low mass transfer efficiency in the oxidation stage, resulting in limited reaction rate and increased by-products; in the separation stage, it faces complex separation processes and high energy consumption.

[0003] The existing oxidation of cumene is carried out in a large oxidation tower, which not only increases the size and complexity of the equipment but also may lead to a significant increase in energy consumption. In addition, due to the low contact efficiency between oxygen and liquid-phase cumene, it is easy to cause uneven distribution of the catalyst, thus affecting the selectivity and yield of the reaction. Similarly, in the decomposition process of cumene hydroperoxide, acidic catalysts such as sulfuric acid are usually used and carried out in a traditional reactor, also facing problems such as low reaction efficiency, many by-products, and complex operations. In the extraction and refining process of phenol, traditional multi-stage extraction and distillation operations often require a large amount of solvents and energy, and may cause environmental problems such as wastewater. Patent CN 117181151 A uses enhanced unit technology to improve the efficiency of the cumene oxidation process. This technology is an improved version of the existing oxidation tower, but in essence, the enhanced mass transfer by bubble breaking cannot solve the shortcoming of the low internal phase contact area in the liquid phase main body. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the present invention aims to provide a membrane reaction-separation integrated system and method for the phenol production process to solve the problems existing in the traditional process, such as low oxidation efficiency, complex separation, large equipment volume, and high safety risks.

[0005] The first aspect of the present invention provides a membrane reaction-separation integrated system for the phenol production process, including a three-stage hollow fiber membrane contactor connected in series. The three-stage hollow fiber membrane contactors are respectively:

[0006] The first-stage hollow fiber membrane reactor, which is used for the oxidation reaction of cumene and oxygen to form cumene hydroperoxide. Among them, cumene and oxygen are respectively introduced into the tube side and shell side of the first-stage hollow fiber membrane reactor, and the two phases are in countercurrent contact;

[0007] The second-stage hollow fiber membrane reactor is used for the decomposition reaction of cumene hydroperoxide and sulfuric acid aqueous solution to produce phenol and acetone. Cumene hydroperoxide and sulfuric acid aqueous solution are respectively introduced into the tube side and shell side of the second-stage hollow fiber membrane reactor, and the two phases are in countercurrent contact.

[0008] The third-stage hollow fiber membrane extractor is used for the extraction and separation of sulfuric acid aqueous solution containing phenol and the extractant. Sulfuric acid aqueous solution and the extractant are respectively introduced into the tube side and shell side of the third-stage hollow fiber membrane extractor, and the two phases are in countercurrent contact.

[0009] Preferably, the hollow fiber membrane materials of the first-stage hollow fiber membrane reactor, the second-stage hollow fiber membrane reactor and the third-stage hollow fiber membrane extractor are all hydrophobic porous structures, with an average pore diameter of 0.1 - 1.0 μm, a porosity of 30% - 60%, the inner diameter of a single hollow fiber membrane is 0.3 - 3.0 mm, the membrane spacing is 0.5 - 3.0 mm, and the membrane material is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyethersulfone or polypropylene.

[0010] Preferably, the shells of the first-stage hollow fiber membrane reactor, the second-stage hollow fiber membrane reactor and the third-stage hollow fiber membrane extractor are all cylindrical structures, the membrane fibers are distributed axially, and both ends are sealed with glue and cut to form independent tube side and shell side channels.

[0011] Preferably, in the first-stage hollow fiber membrane reactor, the volume flow ratio of cumene to oxygen is 1:5 - 20; in the second-stage hollow fiber membrane reactor, the volume flow ratio of cumene hydroperoxide to sulfuric acid solution is 1:5 - 20; in the third-stage hollow fiber membrane extractor, the volume flow ratio of sulfuric acid aqueous solution containing phenol to the extractant is 2:10 - 1.

[0012] Preferably, the extractant is selected from at least one of ethyl acetate, propyl acetate, butyl acetate, methyl isobutyl ketone, n-hexane, dichloromethane or toluene.

[0013] The second aspect of the present invention provides a membrane reaction-separation integration method for the phenol production process, including the following steps:

[0014] (a) In the first-stage hollow fiber membrane reactor, control the gas phase pressure slightly higher than the liquid phase pressure to make cumene and oxygen form a stable gas-liquid contact at the membrane interface to generate cumene hydroperoxide;

[0015] (b) Introduce the product of step (a) into the second-stage hollow fiber membrane reactor to make cumene hydroperoxide and sulfuric acid undergo a decomposition reaction at the membrane interface to generate sulfuric acid aqueous solution containing phenol and an organic phase;

[0016] (c) Feed the sulfuric acid aqueous solution containing phenol obtained in step (b) into the third-stage hollow fiber membrane extractor, and contact it countercurrently with the extractant. Enrich phenol to the organic phase through the radial concentration gradient to realize the recycling of sulfuric acid.

[0017] Preferably, in step (a), oxygen is fed into the shell side in the form of pure oxygen or oxygen-enriched air, the reaction temperature is controlled at 80-120 °C, and the pressure is 0.1-1.0 MPa.

[0018] Preferably, in step (b), the concentration of the sulfuric acid solution is 5-30 wt%, the reaction temperature is controlled at 40-80 °C, and the pressure is 0.05-0.2 MPa.

[0019] Preferably, in step (c), the extraction temperature is 25-60 °C, and the pressure difference between the tube side and the shell side is 0.05-0.2 MPa.

[0020] In the first-stage hollow fiber membrane reactor, the second-stage hollow fiber membrane reactor, and the third-stage hollow fiber membrane extractor, the fluids in their respective tube sides and shell sides can exchange positions to form a stable phase interface and ensure high-efficiency production; the first-stage hollow fiber membrane reactor, the second-stage hollow fiber membrane reactor, and the third-stage hollow fiber membrane extractor adopt a modular combination method of series or parallel connection, and the processing scale is adjusted by increasing or decreasing the number of membrane contactors.

[0021] The beneficial effects of the present invention include:

[0022] 1. Through the first-stage hollow fiber membrane reactor, the second-stage hollow fiber membrane reactor, and the third-stage hollow fiber membrane extractor, the three steps of the oxidation of cumene, the decomposition of cumene hydroperoxide, and the extraction of products are completed in the same type of series-connected equipment, simplifying the process flow and reducing the floor area of the equipment;

[0023] 2. Using the first-stage hollow fiber membrane reactor increases the contact area between cumene and oxygen, enhances the oxidation reaction rate, and effectively inhibits the generation of by-products;

[0024] 3. In the second-stage hollow fiber membrane reactor, the phenol generated during the oxidation process is extracted in real time using an acidic aqueous solution, promoting the forward reaction and improving the overall production efficiency;

[0025] 4. In the third-stage hollow fiber membrane extractor, non-dispersed phase solvent extraction is realized, avoiding the emulsification phenomenon that may occur in the traditional extraction process and improving the purity of the product. These improvements not only optimize the efficiency and quality of phenol production, but also reduce production costs and environmental impacts. Description of the Drawings

[0026] Figure 1It is a schematic diagram of the three-stage membrane contactor (including membrane reactor and membrane extractor) of the present invention.

[0027] Figure 2 It is a schematic process flow diagram of the membrane reaction-separation integrated system of the present invention. Detailed implementation manners

[0028] The first-stage hollow fiber membrane reactor, the second-stage hollow fiber membrane reactor, and the third-stage hollow fiber membrane extractor are all realized by using a hollow fiber membrane contactor. The hollow fiber membrane contactor uses a hydrophobic porous hollow fiber membrane as the medium for two-phase contact. Tens of thousands of membrane fibers can be filled in a single membrane contactor. The tube-side channel inside the membrane fiber and the shell-side channel outside are respectively fed with two-phase fluids. By adjusting the pressure difference between the two phases, a stable phase contact surface can be formed, and the two phases are in continuous phase contact, which not only increases the contact area but also avoids the cost of subsequent phase separation.

[0029] Example 1

[0030] A membrane reaction-separation integrated system and method for phenol production, comprising the following steps:

[0031] a. Oxidation process, fabricate the first-stage hollow fiber membrane reactor as shown in Figure 1 . The outer diameter of the shell is 400 mm, and a polytetrafluoroethylene porous hollow fiber is used. The outer diameter of the membrane fiber is 1.0 mm, the inner diameter is 0.6 mm, the effective length is 1.2 m, and the porosity is 50%. There are 80,000 membrane fibers in the membrane reactor, and five-stage membrane reactors are connected in series for production. The production process is as follows: The flow rate of cumene is 2.2 L / min, the temperature is 80 °C, and the pressure is 0.10 MPa; the flow rate of oxygen is 10 L / min, the pressure is 0.15 MPa, and the temperature is 80 °C. The concentration of cumene hydroperoxide in the oxidation reaction product is 35 wt%. The total volume of the membrane reactor device in this stage is about 0.75 m 3 .

[0032] b. Decomposition process, the parameters of the second-stage hollow fiber membrane reactor are the same as those of the first stage. Three-stage membrane reactors are connected in series and used for the acid-catalyzed decomposition of cumene hydroperoxide to produce an organic phase of phenol and acetone. The production process is as follows: The flow rate of cumene hydroperoxide is 2.2 L / min, the temperature is 80 °C, and the pressure is 0.10 MPa; the flow rate of the sulfuric acid solution is 20 L / min, the sulfuric acid content is 20 wt%, and the temperature is 80 °C. The phenol content in the product sulfuric acid aqueous solution of the decomposition reaction is 21 wt%. The total volume of the membrane reactor device in this stage is about 0.45 m 3 .

[0033] c. Extraction process. The parameters of the hollow fiber membrane extractor in the third stage are the same as those in the first stage. A four-stage membrane extractor is used in series for the extraction of phenol. The production process is as follows: The flow rate of the sulfuric acid aqueous solution containing phenol is 40 L / min, and the temperature is 50 °C; the flow rate of methyl isobutyl ketone is 10 mL / min, and the temperature is 50 °C. The phenol content in the extractant after membrane extraction is 42 wt%. Subsequently, the solvent is recovered by distillation to obtain a phenol product with a purity of 99.0 wt%. The total volume of the membrane extractor and the distillation device in this stage is approximately 2.6 m 3 。

[0034] Example 2

[0035] A membrane reaction-separation integrated system and method for phenol production, including the following steps:

[0036] a. Oxidation process. Fabricate the first-stage hollow fiber membrane reactor as shown in Figure 1 . The outer diameter of the shell is 600 mm. Polyvinylidene fluoride porous hollow fibers are used. The outer diameter of the membrane fiber is 1.0 mm, the inner diameter is 0.6 mm, the effective length is 1.1 m, and the porosity is 45%. The membrane reactor contains 180,000 membrane fibers and is produced in series with a five-stage membrane reactor. The production process is as follows: The feed flow rate of cumene is 5.0 L / min, the temperature is 80 °C, and the pressure is 0.10 MPa; the oxygen flow rate is 22 L / min, the pressure is 0.15 MPa, and the temperature is 80 °C. The concentration of cumene hydroperoxide in the oxidation reaction product is 37 wt%. The total volume of the membrane reactor device in this stage is approximately 1.69 m 3 。

[0037] b. Decomposition process. The parameters of the hollow fiber membrane reactor in the second stage are the same as those in the first stage. A three-stage membrane reactor is used in series for the acid-catalyzed decomposition of cumene hydroperoxide to produce an organic phase of phenol and acetone. The production process is as follows: The feed flow rate of cumene hydroperoxide is 5.0 L / min, the temperature is 80 °C, and the pressure is 0.10 MPa; the flow rate of the sulfuric acid solution is 40 L / min, the sulfuric acid content is 22 wt%, and the temperature is 80 °C. The phenol content in the sulfuric acid aqueous solution, which is the product of the decomposition reaction, is 23 wt%. The total volume of the membrane reactor device in this stage is approximately 1.01 m 3 。

[0038] c. Extraction process. The parameters of the hollow fiber membrane extractor in the third stage are the same as those in the first stage. A four-stage membrane extractor is used in series for the extraction of phenol. The production process is as follows: The flow rate of the sulfuric acid aqueous solution containing phenol is 40 L / min, and the temperature is 50 °C; the flow rate of toluene is 22 mL / min, and the temperature is 50 °C. The phenol content in the extractant after membrane extraction is 40 wt%. Subsequently, the solvent is recovered by distillation to obtain a phenol product with a purity of 99.0 wt%. The total volume of the membrane extractor and the distillation device in this stage is approximately 5.3 m 3 。

[0039] Comparative Example 1

[0040] A traditional process device and method for phenol production, comprising the following steps:

[0041] a. Cumene oxidation process, using a bubble column reactor with a total volume of 50 m 3 (diameter 3.2 m, height 16 m, without a gas distributor), introducing cumene and air (volume ratio 1:0.3) through a bottom single-tube bubbler at a flow rate of 1.8 m 3 / h. The liquid-phase material is heated to 110 - 120 °C by jacket steam and maintained under a slightly pressurized condition of 0.3 MPa. During the reaction, unreacted cumene is refluxed through the top condenser. After 10 - 12 h, the reaction is terminated. The concentration of cumene hydroperoxide in the product is 15.2 wt%. After the reaction liquid is stratified, it enters the intermediate storage tank.

[0042] b. Acid-catalyzed decomposition process, pumping the oxidation product into an enamel reactor with a total volume of 12 m 3 at a flow rate of 6 m 3 / h (equipped with a frame stirrer, rotation speed 45 rpm), mixing it with a 1.5 wt% sulfuric acid solution preheated to 50 °C at a mass ratio of 1:0.5, heating it to 75 °C at a rate of 1 °C / min through coil steam heating, maintaining a constant temperature reaction for 90 min, and then adjusting the pH to neutral. The liquid-phase product is centrifuged to obtain phenol containing 22 wt%.

[0043] c. Refining and separation process, using a three-column distillation system with a total volume of 80 m 3 (phenol column diameter 1.8 m / tray number 32, acetone column diameter 1.2 m / tray number 24, residue column diameter 0.9 m). The crude product is first separated in the phenol column at a vacuum of 0.09 MPa to obtain the light components at the top at 85 °C and the phenol fraction at the bottom at 190 °C. Subsequently, acetone at the top at 56 °C is collected in the acetone column under atmospheric pressure, and the residue column recovers the residual cumene at 150 °C. Finally, the phenol purity is 95.2 wt%.

[0044] Comparative Example 2

[0045] A traditional process device and method for phenol production, comprising the following steps:

[0046] a. Cumene oxidation process, in a packed tower reactor with a total volume of 65 m 3 (diameter 4 m, packing layer height 12 m, filled with 25 mm ceramic Raschig rings), cumene is fed from the top at a rate of 2.4 m 3 / h, and oxygen is injected in multiple side lines to achieve a molar ratio of 1:0.15. The reaction temperature is controlled at 105 °C through an external circulation heat exchanger (the actual axial temperature difference reaches 15 °C). After operating at a pressure of 0.5 MPa for 14 - 16 h, the concentration of cumene hydroperoxide in the liquid-phase product is 13.8 wt%.

[0047] b. Acid-catalyzed decomposition process. A continuous tubular reactor with a total volume of 8 m 3 (inner diameter 0.5 m, length 20 m, serpentine coil structure) is used. After the oxidation product is premixed with a mixture of 0.8 wt% hydrochloric acid + 0.2% phosphoric acid in a mass ratio of 1:0.8 through a static mixer, it enters the reactor at a flow rate of 3 m 3 / h. The outer jacket is circulated with hot water to maintain 65 °C (actual temperature fluctuation ±8 °C). After a residence time of 40 min, the product is separated by two-stage sedimentation. The phenol content in the product is 22 wt%.

[0048] c. Refining and separation process. Through an azeotropic distillation - crystallization system with a total volume of 110 m 3 (azeotropic distillation column diameter 2.4 m / tray number 40, crystallizer volume 15 m 3 ), the crude product first enters the azeotropic distillation column to form an azeotrope with circulating water (top temperature 92 °C). After phenol is enriched at the bottom of the column, it enters the crystallizer and crystallizes in -5 °C ethylene glycol coolant for 12 h. 93.8 wt% phenol is obtained after centrifugal separation.

[0049] The "phenol yield per unit device volume" of each example and comparative example was compared, and the results are shown in Table 1. Compared with the traditional production process, the utilization efficiency of the membrane reaction - separation integrated system was significantly improved.

[0050] Table 1. Comparison table of important parameters in examples and comparative examples

[0051]

Claims

1. A membrane reaction-separation integrated system for phenol production process, characterized in that: The invention comprises three-stage hollow fiber membrane contactors connected in series, wherein the three-stage hollow fiber membrane contactors are: The first stage hollow fiber membrane reactor is used for the oxidation reaction of cumene and oxygen to generate cumene hydroperoxide, wherein cumene and oxygen are respectively introduced into the tube side and shell side of the first stage hollow fiber membrane reactor, and the two phases are in countercurrent contact; The second stage hollow fiber membrane reactor is used for the decomposition reaction of cumene hydroperoxide and aqueous sulfuric acid solution to generate phenol and acetone, wherein cumene hydroperoxide and aqueous sulfuric acid solution are respectively introduced into the tube side and shell side of the second stage hollow fiber membrane reactor, and the two phases are in countercurrent contact; The third stage hollow fiber membrane extractor is used for extracting and separating the aqueous sulfuric acid solution containing phenol from the extractant, wherein the aqueous sulfuric acid solution and the extractant are respectively introduced into the tube side and the shell side of the third stage hollow fiber membrane extractor, and the two phases are in countercurrent contact; The hollow fiber membrane materials of the first-stage hollow fiber membrane reactor, the second-stage hollow fiber membrane reactor and the third-stage hollow fiber membrane extractor are all hydrophobic porous structures with an average pore size of 0.1-1.0 μm, a porosity of 30%-60%, an inner diameter of a single hollow fiber membrane of 0.3-3.0 mm, and a membrane spacing of 0.5-3.0 mm. The hollow fiber membrane material is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyether sulfone or polypropylene.

2. A membrane reaction-separation integrated system for phenol production process according to claim 1, characterized in that: The shells of the first-stage hollow fiber membrane reactor, the second-stage hollow fiber membrane reactor and the third-stage hollow fiber membrane extractor are all cylindrical structures, the membrane fibers are distributed along the axial direction, and the two ends are sealed with glue and cut to form independent tube-side and shell-side channels.

3. The membrane reaction-separation integrated system for phenol production process according to claim 1, characterized in that: In the first-stage hollow fiber membrane reactor, the volume flow ratio of isopropylbenzene to oxygen is 1:5-20; in the second-stage hollow fiber membrane reactor, the volume flow ratio of isopropylbenzene hydroperoxide to sulfuric acid solution is 1:5-20; in the third-stage hollow fiber membrane extractor, the volume flow ratio of phenol-containing sulfuric acid aqueous solution to the extractant is 2:10-1.

4. A membrane reaction-separation integrated system for phenol production process according to claim 1, characterized in that: The extractant is selected from at least one of ethyl acetate, propyl acetate, butyl acetate, methyl isobutyl ketone, n-hexane, dichloromethane or toluene.

5. A membrane reaction-separation integrated method for phenol production process, applicable to a membrane reaction-separation integrated system for phenol production process as described in any one of claims 1 to 5, characterized in that The following steps are involved: (a): In the first stage hollow fiber membrane reactor, the gas phase pressure is controlled to be higher than the liquid phase pressure, so that cumene and oxygen form a stable gas-liquid contact at the membrane interface to generate cumene hydroperoxide; (b): passing the product of step (a) into the second-stage hollow fiber membrane reactor to cause a decomposition reaction between cumene hydroperoxide and sulfuric acid at the membrane interface to generate a sulfuric acid aqueous solution containing phenol and an organic phase; (c): The phenol-containing aqueous sulfuric acid solution obtained in step (b) is passed into the third-stage hollow fiber membrane extractor, where it is countercurrently contacted with the extractant, and the phenol is enriched in the organic phase through a radial concentration gradient, thereby realizing the recovery and reuse of sulfuric acid.

6. A membrane reaction-separation integrated method for phenol production process according to claim 5, characterized in that: In step (a), oxygen is introduced into the shell side in the form of pure oxygen or oxygen-enriched air, and the reaction temperature is controlled at 80-120° C. and the pressure is 0.1-1.0 MPa.

7. A membrane reaction-separation integrated method for phenol production according to claim 6, characterized in that: In step (b), the concentration of the sulfuric acid solution is 5-30wt%, the reaction temperature is controlled at 40-80°C, and the pressure is 0.05-0.2MPa.

8. A membrane reaction-separation integrated method for phenol production according to claim 7, characterized in that: In step (c), the extraction temperature is 25-60° C., and the pressure difference between the tube side and the shell side is 0.05-0.2 MPa.

9. A membrane reaction-separation integrated method for phenol production according to any one of claims 6 to 8, characterized in that: In the first-stage hollow fiber membrane reactor, the second-stage hollow fiber membrane reactor and the third-stage hollow fiber membrane extractor, the respective tube-side and shell-side fluids can exchange positions to form a stable phase interface and ensure high-efficiency production; the first-stage hollow fiber membrane reactor, the second-stage hollow fiber membrane reactor and the third-stage hollow fiber membrane extractor adopt a modular combination of series or parallel connection, and the processing scale is adjusted by increasing or decreasing the number of membrane contactors.

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