Reaction separation and waste catalyst exit system and process for preparing benzenediol through phenol hydroxylation
Through the micro-interface generator, cyclic heat exchange coupling device and backflushing device, the problems of numerous equipment and catalyst wear in the prior art are solved, efficient separation of phenol hydroxylation reaction and harmless treatment of catalysts are achieved, and reaction efficiency and equipment utilization are improved.
Patent Information
- Application Number
- CN202410085928.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-22
- Publication Date
- 2025-07-22
Smart Images
Figure FT_1
Abstract
Description
Technical Field
[0001] The present invention relates to a process for producing benzenediol by hydroxylation of phenol, and particularly to a separation device and process for the hydroxylation reaction of phenol. Background Art
[0002] Benzenediol is an important chemical organic raw material and intermediate. The production methods of benzenediol include aniline oxidation-reduction method, phenol oxidation-reduction two-step method, o-chlorophenol hydrolysis method, etc. Due to the long process flow, serious equipment corrosion, high cost, etc. of these methods, they have been gradually phased out at home and abroad.
[0003] The phenol hydroxylation method uses phenol and hydrogen peroxide as raw materials, and under the action of a titanium silicalite molecular sieve catalyst, benzenediol is formed in one step. The phenol hydroxylation method has a simple process, easy operation, and few by-products, and is increasingly used in industrial applications. After the reaction of the phenol hydroxylation method reaches the requirements, solid-liquid separation of the reaction materials and the solid catalyst is required. The clear liquid of the reaction product benzenediol enters the subsequent process, and the intercepted catalyst returns to the reaction system to continue the reaction. There are mainly two existing reaction separation processes for phenol hydroxylation catalysts: one is to introduce the mixture of the reaction product and the catalyst to an external filter for dead-end filtration separation of solid and liquid. The reaction liquid enters the subsequent process, and the catalyst is re-introduced into the reaction system after enrichment; the disadvantage of this method is that both the reaction and the separation are carried out intermittently. There are many reaction kettles but the individual volume of the reaction kettles is small, the equipment is numerous, and the operation is complex; the other is to lead out the mixed liquid of the reaction product and the catalyst to an external device filter for cross-flow separation. The filtered liquid enters the subsequent process, and the intercepted concentrated catalyst liquid is returned to the reaction kettle to continue to participate in the catalyst reaction. The disadvantage of this method is that the reaction feed liquid needs to be transported outside the reaction kettle, the energy consumption increases, and during the transportation process, the catalyst will be worn due to the shear of the pump, resulting in a decrease in the catalyst performance and catalyst loss.
[0004] The traditional raw material feeding method is direct feeding through a pipeline. In the reaction, it is necessary to ensure an excess of phenol to avoid side reactions. The current feeding method cannot avoid the occurrence of this situation.
[0005] The present invention has reset the filtration system, solved the filtration problem of a large number of equipment and cumbersome operation, and at the same time, through the feeding of the first liquid distributor and the second micro-interface generator, the hydrogen peroxide is more evenly dispersed, the reaction efficiency is improved, and the occurrence of side reactions is reduced. Summary of the Invention
[0006] Aiming at the deficiencies of the existing process, the present invention provides a reaction separation and waste catalyst withdrawal system and process for the hydroxylation of phenol to produce benzenediol, so as to improve the reaction efficiency, reduce the occurrence of side reactions, improve the filtration efficiency, and reduce the equipment investment.
[0007] The present invention provides a reaction separation and spent catalyst withdrawal device for the hydroxylation of phenol to dihydroxybenzene, comprising: a reaction separation device, a microinterface generator and a circulation heat exchange coupling device, a backwashing device, and a spent catalyst withdrawal device.
[0008] The reaction separation device includes a reaction kettle, a liquid distributor, a stirrer, and a membrane filter. The circulating reaction liquid is redistributed through the liquid distributor and, under the action of stirring, is fully mixed with the liquid in the reaction kettle to carry out the hydroxylation reaction. A membrane filter is provided at the lower part of the reaction kettle. The membrane filter filters out the clear liquid of dihydroxybenzene and enters the subsequent process, while the catalyst is intercepted by the membrane filter and remains in the reaction kettle.
[0009] The microinterface generator and circulation heat exchange coupling device include a first liquid distributor, a first heat exchanger, a second microinterface liquid distributor, a second heat exchanger, and a high-efficiency mixer. The reaction raw materials, phenol and solvent methanol solution, are fed through the first liquid distributor provided in the outer circulation pipeline and are heat-exchanged for the first time through the first heat exchanger. The reaction raw material hydrogen peroxide is fed through the second microinterface liquid distributor to uniformly disperse the hydrogen peroxide in the reaction liquid, and is heat-exchanged and mixed for the first time through the second heat exchanger. After the mixed liquid is mixed through the high-efficiency mixer, it returns to the reaction separation device.
[0010] The backwashing device includes a backwashing tank and a backwashing pipeline. The backwashing liquid uses the filtrate after the membrane filter. The membrane filter is periodically pulsed backwashed through the backwashing device to remove the filter cake on the surface of the membrane filter, making the filtration separation process efficient and stable.
[0011] The spent catalyst treatment device includes a spent catalyst transfer tank, a membrane filter, and a water washing device. When the activity of the catalyst does not meet the requirements, the mixed liquid is discharged into the catalyst transfer tank through the valve at the bottom of the reaction kettle, and solid-liquid separation is carried out in the membrane filter. The filtrate is mixed with the filtrate after the membrane filter and enters the next process. The spent catalyst is retained on the membrane surface, and the catalyst is washed with purified water to completely enter the subsequent process, and the catalyst purified water slurry is discharged to collect the spent catalyst.
[0012] The volume ratio of the reaction liquid to the membrane filtration extraction volume in the reaction separation device is 2.5 - 10:1, ensuring that the content of the dihydroxybenzene product is in the optimal state; Preferably, the extraction volume ratio of the reaction kettle to the membrane filter is 5 - 10:1; The separation membrane of the membrane filter can be one or several or a combination of sintered metal filter elements, ceramic filter elements, and organic membranes; Preferably, a sintered metal membrane filter element is used for filtration, which is hollow rod-shaped, with an inner diameter of 10 - 100 mm and a length of 300 - 2500 mm; The material of the separation membrane can be 304, 304L, 316, 316L, Ti, Ni200, 904L, Hastelloy, etc.; Preferably, 316L and / or Hastelloy are used; The separation membrane has a precision of 0.01 - 10 μm; Preferably, a filtration precision of 0.1 - 5.0 μm is adopted; A reaction separation and waste catalyst withdrawal system for the hydroxylation of phenol to hydroquinone according to claim 1, characterized in that the heat exchange of the hydroxylation of phenol to hydroquinone reaction is carried out in the first and second heat exchangers of the microinterface generator and the circulating heat exchange coupling device. At the same time, the first and second heat exchangers also serve the purpose of mixing the reaction liquid and the catalyst; the first liquid distributor is the liquid distributor for raw material phenol and solvent methanol, and the liquid is distributed by small holes in the back-to-flow direction, and the aperture of the small holes is 0.5 - 10 μm; the hydrogen peroxide microinterface distributor is the liquid distribution carrier for raw material hydrogen peroxide, and the hydrogen peroxide is dispersed into fine micron-sized droplets and carried away by the reaction liquid. The reaction raw materials are evenly distributed, and a metal membrane is used for microinterface distribution with a precision of 0.1 - 100 μm; the high-efficiency mixer efficiently mixes the mixed reaction liquid and then enters the reaction kettle.
[0013] The first liquid distributor is composed of a porous tube in the direction opposite to the liquid flow direction, and the aperture is 0.5 - 10 μm; Preferably, the aperture is 0.5 - 3 μm; The second microinterface liquid distributor adopts a membrane distribution form, and the separation membrane can be one or several or a combination of sintered metal filter elements, ceramic filter elements, and organic membranes; Preferably, a sintered metal membrane filter element is used for filtration, which is hollow rod-shaped, with an inner diameter of 10 - 100 mm and a length of 300 - 2500 mm; The material of the separation membrane can be 304, 304L, 316, 316L, Ti, Ni200, 904L, Hastelloy, etc.; Preferably, 316L and / or Hastelloy are used; The separation membrane has a precision of 0.01 - 10 μm; Preferably, a filtration precision of 0.1 - 5.0 μm is adopted; The first and second heat exchangers play the roles of heat exchange and forced mixing, and the form of the heat exchanger can be a shell-and-tube heat exchanger, a plate heat exchanger, a spiral plate heat exchanger, etc.
[0014] A reaction separation and waste catalyst withdrawal system for the hydroxylation of phenol to hydroquinone according to claim 1, characterized in that the backwashing device backwashes with membrane filtration clear liquid, and the membrane filter is backwashed by a pulse method, and the backwashing frequency is 60 - 1800 s.
[0015] Preferably, the backwash interval of the backwash system is 300 - 1200 s / time, and the single backwash time is 0 - 6 s / time; A reaction separation and waste catalyst withdrawal system for the hydroxylation of phenol to dihydroxybenzene according to claim 1, characterized in that the waste catalyst treatment device performs harmless treatment on the withdrawn waste catalyst, conducts thorough solid-liquid separation, and at the same time uses a water washing device for thorough water washing to discharge the catalyst purified water slurry.
[0016] The separation membrane of the membrane filter can be one or several or a combination of sintered metal filter elements, ceramic filter elements, and organic membranes; Preferably, a sintered metal membrane filter element is used for filtration, which is hollow rod-shaped, with an inner diameter of 10 - 100 mm and a length of 300 - 2500 mm; The material of the separation membrane can be 304, 304L, 316, 316L, Ti, Ni200, 904L, Hastelloy, etc.; Preferably, 316L and / or Hastelloy is used; The precision of the separation membrane is 0.01 - 10 μm; Preferably, a filtration precision of 0.1 - 5.0 μm is used; A reaction separation and waste catalyst withdrawal process for the hydroxylation of phenol to dihydroxybenzene includes the following steps: Step 1: Add raw material phenol, solvent methanol, and titanium silicalite catalyst into the reaction kettle. The temperature in the reaction kettle is 75 - 100 °C, and the pressure is 0.8 - 1.2 MPa to establish a circulation; Step 2: Continuously add phenol and methanol through the first liquid distributor; Step 3: Continuously add hydrogen peroxide through the second microinterface generator; Step 4: Control the temperature of the reaction system to be stable through the first and second heat exchangers; Step 5: The reaction continues. When the dihydroxybenzene concentration in the reaction liquid reaches the extraction requirement, extraction starts. The volume ratio of the reaction liquid to the material liquid is 2.5 - 10:1; Step 6: The membrane filter at the lower part of the reaction kettle uses a metal membrane for separation. The backwashing interval is 60 - 1800 s, and the clear dihydroxybenzene liquid continuously filters through and enters the subsequent process. The phenol hydroxylation catalytic reaction and separation are carried out continuously; Step 7: When the reaction efficiency decreases, the catalyst withdrawal operation is carried out. The catalyst slurry enters the waste catalyst transfer tank, and solid-liquid separation is carried out through a membrane separator. The catalyst is washed with purified water, and after the catalyst is made harmless, the catalyst and purified water thick slurry are discharged.
[0017] 1. The reaction separation and waste catalyst withdrawal system for the hydroxylation of phenol to dihydroxybenzene provided by the present invention uses microinterface distributed liquid feeding, which improves the dispersion effect, improves the reaction selectivity, and reduces the occurrence of side reactions; 2. The reaction separation and spent catalyst withdrawal system for preparing dihydroxybenzene by hydroxylation of phenol provided by the present invention uses a membrane separation method to treat the spent catalyst, completely separating the catalyst from the reaction solution, reducing the difficulty of catalyst treatment and alleviating the environmental protection burden. 3. The reaction separation and spent catalyst withdrawal system for preparing dihydroxybenzene by hydroxylation of phenol provided by the present invention adopts an in-kettle reaction separation method, reducing the number of equipment units and ensuring stable operation of the production. Description of the Drawings Figure 1 It is a schematic diagram of the reaction separation and spent catalyst withdrawal system, process structure and process flow for preparing dihydroxybenzene by hydroxylation of phenol according to the present invention. 1. Reaction kettle; 2. Backwashing tank; 3. Spent catalyst transfer tank; 4. Water washing tank; 5. Membrane filter; 6. Catalyst storage tank; 7. Spent catalyst thick slurry tank; 8. First liquid distributor; 9. First heat exchanger; 10. Microinterface liquid distributor; 11. Second heat exchanger; 12. High-efficiency mixer; 13. Liquid distributor; 14. Membrane filter; 15. Stirring; 16. Feed pump; 17. Spent catalyst pump; 18. Reactor external circulation pipeline; 19. Clear liquid main pipe; 20. Spent catalyst pipeline; Detailed Embodiments
[0019] The following further elaborates on the present invention with reference to embodiments, enabling those skilled in the art to implement it according to the description in the specification. These embodiments are only illustrative and not limited to the application scope of the present invention.
[0020] Embodiment 1: Methanol and phenol are added to the reaction kettle at a mass ratio of 4:1, and the temperature is raised. When the operating temperature reaches 50°C, the catalyst is slowly added, and circulation is established. The temperature is raised to 90°C. In the first liquid distributor, methanol and phenol are introduced into the reaction system at a mass ratio of 4:1. At the same time, hydrogen peroxide is introduced into the second microinterface generator at a ratio of phenol:hydrogen peroxide = 15:1, and the continuous reaction lasts for 4 hours. The phenol conversion rate is measured to reach 30%, and the in-kettle membrane filter of the reaction kettle is opened to keep the feed rate and the withdrawal rate balanced.
[0021] Example 2: Methanol and phenol were added to the reaction kettle at a mass ratio of 5:1. The liquid level in the reaction kettle was 40%. The temperature was raised. When the temperature in the reaction kettle reached 60°C, the catalyst was slowly added, and the mass ratio of the catalyst was 10%. A circulation was established. In the first liquid distributor, methanol and phenol were introduced into the reaction system at a mass ratio of 5:1. At the same time, hydrogen peroxide was introduced into the second microinterface generator at a ratio of phenol:hydrogen peroxide = 12:1. The reaction continued for 4 hours. As the reaction proceeded, the temperature rose. When it rose to 85°C, the first and second heat exchangers were enabled to maintain the temperature in the reaction kettle at 85°C. The phenol conversion rate was measured to be 45%. The in-reactor membrane filter was opened to keep the feed rate and the withdrawal rate in balance.
[0022] Example 3: When the phenol conversion rate began to decline, the operation of withdrawing the spent catalyst was carried out. The liquid material was sent from the bottom of the reaction kettle to the spent catalyst transfer tank and filtered using a membrane filter for thorough solid-liquid separation. The filtrate was combined with the filtrate of the membrane filter and sent to the subsequent process. The catalyst was intercepted on the membrane surface. The catalyst was washed with purified water. The filtrate showed no change in the phenol color reaction, and the catalyst purified water thick slurry was discharged.
[0023] The above examples are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the various embodiments of the present invention.
Claims
1. A reaction separation and waste catalyst withdrawal device for the hydroxylation of phenol to dihydroxybenzene, characterized in that, Including: A reaction separation device, a microinterface generator and a circulation heat exchange coupling device, a backwashing device, and a spent catalyst withdrawal device.
2. The reaction separation device includes a reaction kettle, a liquid distributor, a stirrer, and a membrane filter. The circulating reaction liquid is redistributed through the liquid distributor and fully mixed with the liquid in the reaction kettle under the action of stirring to carry out a hydroxylation reaction. A membrane filter is provided at the lower part of the reaction kettle. The membrane filter filters out the hydroquinone clear liquid and enters the subsequent process, and the catalyst is intercepted by the membrane filter and remains in the reaction kettle.
3. The microinterface generator and the circulation heat exchange coupling device include a first liquid distributor, a first heat exchanger, a second microinterface liquid distributor, a second heat exchanger, and a high-efficiency mixer. The reaction raw materials, phenol and solvent methanol solution, are fed through the first liquid distributor provided in the outer circulation pipeline and subjected to the first heat exchange through the first heat exchanger. The reaction raw material, hydrogen peroxide, is fed through the second microinterface liquid distributor to uniformly disperse the hydrogen peroxide in the reaction liquid, and heat exchange and the first mixing are carried out through the second heat exchanger. After the mixed liquid is mixed through the high-efficiency mixer, it returns to the reaction separation device.
4. The backwashing device includes a backwashing tank and a backwashing pipeline. The backwashing liquid uses the filtered liquid after the membrane filter. The membrane filter is periodically pulsed backwashed through the backwashing device to remove the filter cake on the surface of the membrane filter, making the filtration separation process efficient and stable.
5. The spent catalyst treatment device includes a spent catalyst transfer tank, a membrane filter, and a water washing device. When the activity of the catalyst does not meet the requirements, the mixed liquid is discharged into the catalyst transfer tank through the valve at the bottom of the reaction kettle, and solid-liquid separation is carried out in the membrane filter. The filtered liquid is mixed with the filtered liquid after the membrane filter and enters the next process. The spent catalyst is intercepted on the membrane surface, and the catalyst is washed with purified water to make the reaction liquid completely enter the subsequent process, and the catalyst purified water slurry is discharged to collect the spent catalyst.
6. According to a reaction separation and spent catalyst withdrawal system for the hydroxylation of phenol to hydroquinone as described in claim 1, the special feature is that the volume ratio of the reaction liquid in the reaction separation device to the volume of the membrane filtration output is 2.5 - 10:1, ensuring that the hydroquinone product content is in the optimal state; the separation accuracy of the membrane filter is 0.1 - 100 μm; the membrane filter is distributed inside the reaction kettle, and the filtered liquid enters the post-treatment process.
7. According to a reaction separation and spent catalyst withdrawal system for the hydroxylation of phenol to hydroquinone as described in claim 1, the special feature is that the heat exchange of the hydroxylation reaction of phenol to hydroquinone is carried out in the first and second heat exchangers of the microinterface generator and the circulation heat exchange coupling device. At the same time, the first and second heat exchangers also serve the purpose of mixing the reaction liquid and the catalyst; the first liquid distributor is a liquid distributor for raw material phenol and solvent methanol, and the liquid is distributed by small holes with a countercurrent flow. The aperture of the small holes is 0.5 - 10 μm; the hydrogen peroxide microinterface distributor is a liquid distribution carrier for raw material hydrogen peroxide. The hydrogen peroxide is dispersed into fine micron-sized droplets and carried away by the reaction liquid. The reaction raw materials are evenly distributed. A metal membrane is used for microinterface distribution with an accuracy of 0.1 - 100 μm; the high-efficiency mixer efficiently mixes the mixed reaction liquid and then enters the reaction kettle.
8. A reaction separation and spent catalyst withdrawal system for the hydroxylation of phenol to dihydroxybenzene according to claim 1, characterized in that, The backwashing device backwashes with the membrane filtration clear liquid, and backwashes the membrane filter in a pulsed manner. The backwashing frequency is 60 - 1800 s.
9. A reaction separation and spent catalyst withdrawal system for the hydroxylation of phenol to dihydroxybenzene according to claim 1, characterized in that, The spent catalyst treatment device harmlessly treats the withdrawn spent catalyst, conducts thorough solid-liquid separation, and at the same time uses a water washing device for thorough water washing to discharge the catalyst purified water slurry.
10. A process for the reaction separation of phenol hydroxylation to dihydroxybenzene and the withdrawal of spent catalyst, comprising the following steps: Step 1: Add raw material phenol, solvent methanol, and titanium silicate molecular sieve catalyst into the reaction kettle. The temperature in the reaction kettle is 75 - 100 °C, and the pressure is 0.8 - 1.2 MPa to establish a cycle; Step 2: Continuously add phenol and methanol through the first liquid distributor; Step 3: Continuously add hydrogen peroxide through the second microinterface generator; Step 4: Control the temperature of the reaction system to be stable through the first and second heat exchangers; Step 5: The reaction continues. When the dihydroxybenzene concentration in the reaction liquid reaches the requirement for extraction, start the extraction. The volume ratio of the reaction liquid to the material liquid is 2.5 - 10:1; Step 6: The membrane filter at the lower part of the reaction kettle uses a metal membrane for separation. The backwashing interval is 60 - 1800 s. The clear liquid of dihydroxybenzene continuously filters through and enters the subsequent process, and the phenol hydroxylation catalytic reaction and separation are carried out continuously; Step 7: When the reaction efficiency decreases, carry out the operation of withdrawing the catalyst. The catalyst slurry enters the spent catalyst transfer tank, and solid-liquid separation is carried out through a membrane separator. The catalyst is washed with purified water, and after harmless treatment of the catalyst, the catalyst and purified water thick slurry are discharged.