Device and method for separating and coupling transesterification reaction

Abstract

The invention provides an ester exchange reaction separation coupling device and method, and belongs to the technical field of chemical engineering, the ester exchange reaction separation coupling device comprises a reaction kettle, a circulation pipeline and a catalyst preparation tank; the top of the reaction kettle is provided with a feed port, and the bottom is provided with a discharge port; the circulating pipeline is located on the outer side of the reaction kettle, and the two ends of the circulating pipeline are communicated with the feeding port and the discharging port respectively; the circulating pipeline is sequentially connected with a membrane filtering unit, a micro-interface strengthening mixer and a pre-reactor from the discharging opening to the feeding opening, and the circulating pipeline is further connected with a circulating pump; the catalyst preparation tank is connected to the position, between the membrane filtration unit and the micro-interface strengthening mixer, of the circulation pipeline through a feeding pipe; the circulating pipeline is provided with a waste catalyst discharging pipe at the upstream of the feeding pipe, and when part of the waste catalyst in the circulating pipeline is regularly discharged, a new catalyst is supplemented to the circulating pipeline at the same time; according to the arrangement, after mixed feed liquid is introduced into the reaction kettle, the influence of discharge of a waste catalyst on the transesterification reaction in the reaction kettle can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical engineering, and in particular relates to a transesterification reaction separation coupling device and method. Background Art

[0002] Alkyl oxalate is an important organic chemical raw material and methylation / ethylation reagent, which can undergo various condensation reactions with fatty acid esters, amides or aniline compounds and many heterocyclic compounds; as an asymmetric alkyl oxalate, it can be used as a lithium battery electrolyte solvent.

[0003] In the heterogeneous catalytic synthesis of alkyl oxalate, a solid catalyst is used; the catalyst is introduced into the reactor through a catalyst pipe, and the materials in the reactor react at an accelerated rate under the action of the catalyst; when the catalyst performance decreases or becomes inactivated, the concentrated slurry at the bottom of the reactor is discharged to a waste catalyst separation system; after the discharge is completed, the catalyst is reintroduced into the reactor.

[0004] However, the above process will discharge a large amount of catalyst, and the discharge and addition of the catalyst are carried out in steps, which is likely to affect the transesterification reaction in the reactor. Summary of the Invention

[0005] The embodiment of the present invention provides an ester exchange reaction separation coupling device and method, which aims to solve the problem that a large amount of catalyst is discharged in the heterogeneous catalytic synthesis process of alkyl oxalate in the prior art, and affects the ester exchange reaction in the reactor.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] Provided is a transesterification reaction separation coupling device, comprising:

[0008] The reactor has a feed port at the top and a discharge port at the bottom;

[0009] A circulation pipeline is located outside the reactor, and both ends of the circulation pipeline are connected to the feed port and the discharge port respectively; the circulation pipeline is sequentially connected to a membrane filtration unit, a micro-interface enhanced mixer and a pre-reactor from the discharge port to the feed port, and the circulation pipeline is also connected to a circulation pump;

[0010] The catalyst preparation tank is connected to the circulation pipeline between the membrane filtration unit and the micro-interface enhanced mixer through a feed pipe; the circulation pipeline is provided with a waste catalyst discharge pipe upstream of the feed pipe;

[0011] Wherein, when part of the spent catalyst in the circulation pipeline is discharged regularly, new catalyst is added to the circulation pipeline at the same time.

[0012] In a possible implementation, a feed mixer is further included, wherein the top of the feed mixer has an ester phase raw material inlet and an alcohol phase raw material inlet. After the ester raw material and the alcohol raw material are mixed in proportion in the feed mixer, they are introduced into the micro-interface enhanced mixer.

[0013] In one possible implementation, the circulation pump is arranged at the inlet end of the membrane filtration unit, an opening valve is provided at the outlet end of the membrane filtration unit, the waste catalyst discharge pipe is located at the rear side of the opening valve, and the material in the circulation pipeline first passes through the opening valve and then through the catalyst discharge pipe.

[0014] In a possible implementation, a backwash tank is further included. The backwash tank is connected to the clear liquid side of the membrane filtration unit through a pipeline, and a backwash gas inlet is provided at the top of the backwash tank.

[0015] In a possible implementation, the top of the catalyst preparation tank is provided with a catalyst inlet, and the catalyst preparation tank is connected to the clear liquid side of the membrane filtration unit through a pipeline.

[0016] In a possible implementation, a feed distributor is provided at the top of the reactor, and the feed distributor is connected to a feed port through a pipeline.

[0017] In a possible implementation, the spent catalyst discharge pipe is located between the outlet of the membrane filtration unit and the feed pipe.

[0018] In a possible implementation, the top of the reactor is connected to a distillation tower via a pipeline, and the top of the distillation tower is provided with a by-product outlet.

[0019] Working process: After mixing, the ester raw materials and the alcohol raw materials are introduced into the micro-interface enhanced mixer. The catalyst in the catalyst preparation tank is also introduced into the micro-interface enhanced mixer through the feed pipe. The ester raw materials and the alcohol raw materials are fully mixed with the catalyst in the micro-interface enhanced mixer and introduced into the pre-reactor together; the mixture discharged from the pre-reactor flows along the circulation pipeline and finally enters the reactor from the feed port.

[0020] The ester raw materials and the alcohol raw materials undergo an ester exchange reaction under the action of the catalyst. The reaction liquid and the catalyst are discharged from the discharge port of the reactor. The circulating pump provides power to enable the reaction liquid and the catalyst to move from the discharge port of the reactor along the circulation pipeline to the feed port, so that the reaction liquid and the catalyst circulate between the reactor and the circulation pipeline.

[0021] By setting a membrane filtration unit on the circulation pipeline, the reaction liquid and catalyst can be filtered, and the filtered clear liquid can be discharged from the membrane filtration unit, and the filtered concentrated slurry continues to participate in the circulation; when the activity of the catalyst decreases, part of the concentrated slurry filtered by the membrane filtration unit is regularly discharged. The concentrated slurry contains catalyst, so part of the waste catalyst can be regularly discharged; in the process of discharging the waste catalyst, new catalyst is simultaneously added to the circulation pipeline.

[0022] Compared with the prior art, the ester exchange reaction separation coupling device provided by the present invention can achieve online solid-liquid separation of reaction products through the above-mentioned process of the present application, and the discharge of waste catalyst and the addition of new catalyst can be carried out simultaneously; the newly added catalyst and the old catalyst that has not been discharged enter the micro-interface enhanced mixer together and are fully mixed with the ester raw materials and alcohol raw materials. Therefore, after the mixed liquid is passed into the reactor, the impact of the discharge of waste catalyst on the ester exchange reaction in the reactor can be reduced.

[0023] To achieve the above object, another technical solution adopted by the present invention is:

[0024] Provided is a transesterification reaction separation coupling method, comprising the following steps:

[0025] The ester raw materials and the alcohol raw materials undergo an ester exchange reaction in the reactor under the action of the catalyst, and the materials in the reactor circulate in the circulation pipeline from the discharge port to the feed port;

[0026] As the material flows through the circulation pipeline, it is filtered by the membrane filtration unit and the filtered clear liquid is discharged. The filtered concentrated slurry continues to flow to the reactor.

[0027] A mixture of ester raw materials and alcohol raw materials is introduced into the circulation pipeline, and the amount of the added mixture is kept in balance with the amount of clear liquid discharged;

[0028] Part of the filtered concentrated slurry containing spent catalyst is discharged regularly; at the same time, new catalyst is introduced into the circulation pipeline.

[0029] In a possible implementation, when the transmembrane pressure difference of the membrane filtration unit exceeds a preset value, the membrane filtration unit is backflushed to remove the filter cake layer on the surface of the membrane filtration unit.

[0030] The beneficial effects of the transesterification reaction separation coupling method provided in the present application are the same as those of the transesterification reaction separation coupling device, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the transesterification reaction separation coupling device provided in an embodiment of the present invention.

[0032] Explanation of the accompanying symbols: 1. Reactor; 11. Feed distributor; 12. Stirring blade; 2. Circulation pump; 3. Membrane filtration unit; 4. Opening valve; 5. Micro-interface enhanced mixer; 51. Filter membrane tube; 6. Pre-reactor; 61. Spiral tube; 7. Backwash tank; 8. Catalyst preparation tank; 9. Feed mixer; 10. Distillation tower; A. Ester phase raw material inlet; B. Alcohol phase raw material inlet; C. Catalyst inlet; D. Nitrogen inlet; E. Product outlet; F. Spent catalyst outlet; G. By-product outlet. DETAILED DESCRIPTION

[0033] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] Please also refer to Figure 1 , the ester exchange reaction separation coupling device provided by the present invention is now described. The ester exchange reaction separation coupling device includes a reactor 1, a circulation pipeline and a catalyst preparation tank 8; the reactor 1 has a feed port on the top and a discharge port on the bottom; the circulation pipeline is located on the outside of the reactor 1, and the two ends of the circulation pipeline are connected to the feed port and the discharge port respectively; the circulation pipeline is sequentially connected with a membrane filtration unit 3, a micro-interface enhanced mixer 5 and a pre-reactor 6 from the discharge port to the feed port, and a circulation pump 2 is also connected to the circulation pipeline; the catalyst preparation tank 8 is connected to the circulation pipeline between the membrane filtration unit 3 and the micro-interface enhanced mixer 5 through a feed pipe; the circulation pipeline is provided with a waste catalyst discharge pipe upstream of the feed pipe, and the upstream here means that the feed pipe and the waste catalyst discharge pipe are staggered. That is, the feed liquid in the circulation pipeline first passes through the waste catalyst discharge pipe and then passes through the feed pipe; therefore, when new catalyst is introduced into the circulation pipeline through the feed pipe, the new catalyst is driven by the feed liquid to move into the micro-interface enhanced mixer 5 and will not be discharged from the waste catalyst discharge pipe; wherein, when part of the waste catalyst in the circulation pipeline is regularly discharged, new catalyst is simultaneously replenished into the circulation pipeline; a valve is provided on the waste catalyst discharge pipe, and when the waste catalyst does not need to be discharged, the valve on the waste catalyst discharge pipe is in a closed state; a valve is also provided on the feed pipe, and when new catalyst does not need to be introduced into the circulation pipeline, the valve on the feed pipe is in a closed state; the other end of the waste catalyst discharge pipe is a waste catalyst outlet F.

[0035] Compared with the prior art, the ester exchange reaction separation coupling device provided by the present invention can achieve online solid-liquid separation of the reaction products through the above-mentioned process of the present application, and the discharge of the waste catalyst and the addition of the new catalyst can be carried out simultaneously; the newly added catalyst and the old catalyst that has not been discharged enter the micro-interface enhanced mixer 5 together and are fully mixed with the ester raw materials and the alcohol raw materials. Therefore, after the mixed liquid is passed into the reactor 1, the influence of the discharge of the waste catalyst on the ester exchange reaction in the reactor 1 can be reduced.

[0036] Specific description of the micro-interface enhanced mixer 5: The micro-interface enhanced mixer 5 has a plurality of filter membrane tubes 51 inside, and the axial direction of the filter membrane tubes 51 is perpendicular to the flow direction of the catalyst; the ester raw material and the alcohol raw material are introduced into the filter membrane tubes 51 after mixing, and the ester raw material and the alcohol raw material can be evenly dispersed after passing through the filter membrane tubes 51, thereby enabling the ester raw material and the alcohol raw material to be fully mixed with the catalyst.

[0037] The material of the filter membrane tube 51 is one or more of metal powder sintered filter material, metal wire mesh filter material, powder mesh composite filter material, ceramic filter material, and organic porous filter material.

[0038] Specific description of the pre-reactor 6: The pre-reactor 6 can heat the mixed liquid by heat exchange; a number of spiral tubes 61 are provided in the pre-reactor 6, and the mixed liquid discharged from the micro-interface enhanced mixer 5 enters the pre-reactor 6, enters from one end of the spiral tube 61, and is discharged from the other end of the spiral tube 61; the purpose of arranging the spiral tube 61 in the pre-reactor 6 is to further fully mix the liquid and the catalyst, and to increase the heat exchange area, enhance the heat exchange effect, and make the mixed liquid reach the reaction temperature.

[0039] Specific description of the membrane filtration unit 3: The membrane filtration unit 3 uses cross-flow filtration to separate the reaction liquid and the catalyst; the membrane element in the membrane filtration unit 3 is one or more of metal powder sintered filter material, metal wire mesh filter material, powder mesh composite filter material, ceramic filter material, and organic porous filter material; the shape of the membrane element can be a plate structure or a tubular structure.

[0040] Exemplarily, the circulation pump 2 is provided on the circulation pipeline between the membrane filtration unit 3 and the discharge port of the reactor 1 .

[0041] In some embodiments, as Figure 1 As shown, it also includes a feed mixer 9, and the top of the feed mixer 9 has an ester phase raw material inlet A and an alcohol phase raw material inlet B. After the ester raw material and the alcohol raw material are mixed in proportion in the feed mixer 9, they are introduced into the micro-interface enhanced mixer 5.

[0042] It should be noted that the same feed end of several filter membrane tubes 51 is connected to the feed main pipe, the discharge pipe of the feed mixer 9 is connected to the feed main pipe, and the discharge pipe of the feed mixer 9 is provided with a valve; the ester phase raw material inlet A and the alcohol phase raw material inlet B at the top of the feed mixer 9 are also provided with valves. By opening the valves at the ester phase raw material inlet A and the alcohol phase raw material inlet B, the ester raw material and the alcohol raw material enter the feed mixer 9 in a certain proportion. After the ester raw material and the alcohol raw material are mixed in the feed mixer 9, the valve on the discharge pipe is opened, and the mixture in the feed mixer 9 can enter the filter membrane tube 51 through the feed main pipe. The filter membrane tube 51 can evenly disperse the mixture, so as to facilitate sufficient mixing between the mixture and the catalyst.

[0043] In some embodiments, as Figure 1 As shown, the circulation pump 2 is arranged at the inlet end of the membrane filtration unit 3, and the outlet end of the membrane filtration unit 3 is provided with an opening valve 4. The waste catalyst discharge pipe is located on the rear side of the opening valve 4. The material in the circulation pipeline first passes through the opening valve 4 and then through the catalyst discharge pipe; the waste catalyst discharge pipe is located between the outlet of the membrane filtration unit 3 and the feed pipe.

[0044] It should be noted that, under the action of the circulation pump 2, the mixed liquid discharged from the reactor 1 enters the membrane filtration unit 3 through the circulation pipeline, the membrane filtration unit 3 filters the mixed liquid, and discharges the filtered clear liquid from the membrane filtration unit 3. The filtered concentrated slurry contains the catalyst, so the filtered concentrated slurry continues to circulate in the circulation pipeline; by arranging an opening valve 4 at the outlet end of the membrane filtration unit 3, the opening range of the opening valve 4 is 0-100; by controlling the opening of the opening valve 4, the filtration pressure difference of the membrane filtration unit 3 can be controlled; by adjusting the opening of the opening valve 4, the amount of raw material feed and the amount of filtered clear liquid discharged can be kept in relative balance.

[0045] Since the waste catalyst discharge pipe is located at the rear side of the opening valve 4, and the waste catalyst discharge pipe is located at the front side of the feed pipe of the catalyst preparation tank 8, the front side and the rear side here are based on the movement direction of the material in the circulation pipeline, that is, in the process of the material flowing in the circulation pipeline, the material first passes through the opening valve 4, and then passes through the position of the waste catalyst discharge pipe, and finally passes through the position of the feed pipe; through the above arrangement, when the waste catalyst needs to be discharged, since the filtered slurry first passes through the waste catalyst discharge pipe and then passes through the feed pipe, therefore in the process of discharging part of the waste catalyst, new catalyst is added to the circulation pipeline simultaneously, and the new catalyst will not flow to the waste catalyst discharge pipe, thereby avoiding the situation where new catalyst is discharged from the waste catalyst discharge pipe.

[0046] In some embodiments, as Figure 1As shown, it also includes a backwash tank 7, which is connected to the clear liquid side of the membrane filtration unit 3 through a pipeline. The top of the backwash tank 7 is provided with a backwash gas inlet, and the backwash gas inlet at the top of the backwash tank 7 is provided with a valve. The backwash gas inlet is illustrated by taking the nitrogen inlet D as an example; the backwash gas introduced into the backwash tank 7 cannot react with the liquid in the backwash tank 7. A single backwash operation does not require all the liquid in the backwash tank 7 to be introduced into the membrane filtration unit 3. Therefore, the backwash gas does not enter the circulation pipeline.

[0047] It should be noted that the backwash tank 7 has a backwash inlet pipe and a backwash outlet pipe, and both the backwash inlet pipe and the backwash outlet pipe are provided with valves; during the normal filtration process, the valve of the backwash outlet pipe is closed, and the valve of the backwash inlet pipe is opened first, and the filtered clear liquid can enter the backwash tank 7. When the filtered clear liquid in the backwash tank 7 reaches the preset position, the valve of the backwash inlet pipe is closed, and the filtered clear liquid is discharged into the subsequent processing equipment.

[0048] When the membrane filter unit 3 needs to be backwashed, the backwash inlet pipe is in a closed state, the backwash outlet pipe is in an open state, the backwash gas inlet valve is in an open state, and the backwash gas enters the backwash tank 7, presses the liquid in the backwash tank 7 into the filtered clear liquid side of the membrane filter unit 3, and passes through the filter membrane of the membrane filter unit 3, thereby washing away the filter cake on the filter membrane; after the backwash is completed, the valve of the backwash outlet pipe is closed, the backwash gas is stopped from being introduced into the backwash tank 7, and the backwash gas is discharged from the backwash tank 7, and the backwash inlet pipe is opened, so that the filtered clear liquid of the membrane filter unit 3 can enter the backwash tank 7. When the filtered clear liquid in the backwash tank 7 reaches a preset position, the valve of the backwash inlet is closed; the backwash frequency is 4-48 times / day, and the single backwash time is 0.5-10S; through the above settings, the continuous operation of the membrane separator (3) can be achieved.

[0049] In some embodiments, as Figure 1 As shown, the top of the catalyst preparation tank 8 is provided with a catalyst inlet, and the catalyst preparation tank 8 is connected to the clear liquid side of the membrane filtration unit 3 through a pipeline; the feed pipe of the catalyst preparation tank 8 is provided with a valve.

[0050] It should be noted that a valve is provided at the catalyst inlet position, and a valve is provided at the pipeline connecting the catalyst preparation tank 8 and the clear liquid side of the membrane filtration unit 3; when new catalyst needs to be added to the circulation pipeline, the valve of the feed pipe is opened to allow the catalyst in the catalyst preparation tank 8 to enter the circulation pipeline, thereby realizing the process of adding new catalyst.

[0051] After the new catalyst is added, the valve of the feed pipe is closed. At this time, the valve connecting the catalyst preparation tank 8 and the clear liquid side of the membrane filtration unit 3 is opened, and the filtered clear liquid can enter the catalyst preparation tank 8 to replenish the catalyst preparation tank 8; new catalyst can also be added to the catalyst preparation tank 8 through the catalyst inlet.

[0052] In some embodiments, as Figure 1 As shown, a feed distributor 11 is provided at the top of the reactor 1 , and the feed distributor 11 is connected to the feed port through a pipeline.

[0053] It should be noted that the feed distributor 11 includes several discharge ports, each of which is facing the bottom of the reactor 1; after the mixed liquid enters the feed distributor 11, the mixed liquid flows out from the several discharge ports, so that the mixed liquid is evenly distributed in the reactor 1.

[0054] A stirring shaft is provided in the reactor 1, the top of which passes through the top of the reactor 1. A drive motor is connected to the top of the reactor 1, and the output shaft of the drive motor is connected to the stirring shaft to drive the stirring shaft to rotate; a stirring blade 12 is connected to the stirring shaft. During the rotation of the stirring shaft, the stirring blade 12 can stir the mixed liquid. The stirring speed is 30-60rmp, which is a low-speed stirring, mainly to prevent the catalyst from precipitating; the stirring method of the stirring blade 12 is mechanical stirring, and the reactor 1 is provided with a feed distributor 11 to carry out the aging process of the esterification reaction under the action of mechanical stirring.

[0055] In some embodiments, as Figure 1 As shown, the top of the reactor 1 is connected to a distillation tower 10 through a pipeline. The top of the distillation tower 10 is provided with a by-product outlet G, and the by-product outlet G has a valve.

[0056] The above-mentioned setting of the present application realizes the coupling of reaction and separation, realizes the continuous advance and retreat of the catalyst, realizes micro-interface enhanced feeding through the micro-interface enhanced mixer 5, and the materials are evenly dispersed. The concentrate, the configured catalyst and the reaction raw materials are forcibly mixed in the micro-interface enhanced mixer 5, which enhances the mass transfer. The mixing heat exchanger further enhances the liquid-solid mixing while enhancing the pre-reaction. It is the main place for the reaction. The reactor 1 is provided with a feed distributor 11, which carries out the maturation process of the esterification reaction under the action of mechanical stirring. A distillation tower 10 is provided on the top of the reactor 1, and the by-products of the reaction are extracted to facilitate the forward progress of the esterification reaction.

[0057] In addition, this scheme is a heterogeneous transesterification process, and the transesterification catalyst uses a solid base catalyst. During operation, the transesterification catalyst is present in the reaction raw materials and reacts with impurities, causing the catalyst to become inactivated. In order to ensure the reaction rate and the activity of the catalyst, part of the catalyst needs to be discharged regularly and fresh catalyst needs to be added. Generally, 1 / 10 of the concentrated reaction liquid (catalyst content is about 5-15%) of the total volume of the reactor is discharged regularly every day, and fresh catalyst is added at the same time. The added amount is 0.3-1% of the catalyst calculated based on the normal liquid level of the reactor.

[0058] It should be noted that the conventional cross-flow filtration circulation volume is 20-30 times the clear liquid output, and the circulation volume is 8-15 times the normal reactor volume. The circulation is completed by a pump. Circulation pump 2 is generally a centrifugal pump, and the impeller shear is very severe. In this application, the circulation volume of circulation pump 2 is 1.5-8 times the clear liquid output. Reducing the circulation volume will greatly reduce the damage to the catalyst caused by the pump impeller shear, thereby reducing the breakage of the solid catalyst.

[0059] Based on the same inventive concept, the present application also provides a transesterification reaction separation coupling method, comprising the following steps:

[0060] The ester raw materials and the alcohol raw materials undergo an ester exchange reaction in the reactor 1 under the action of the catalyst, and the materials in the reactor 1 circulate in the circulation pipeline from the discharge port to the feed port.

[0061] During the flow of the material in the circulation pipeline, the material is filtered by the membrane filtration unit 3 and the filtered clear liquid is discharged. The filtered concentrated slurry continues to flow to the reactor 1.

[0062] A mixture of ester raw materials and alcohol raw materials is introduced into the circulation pipeline, and the amount of the added mixture is kept in balance with the amount of clear liquid discharged.

[0063] Part of the filtered concentrated slurry containing spent catalyst is discharged regularly; at the same time, new catalyst is introduced into the circulation pipeline.

[0064] In some embodiments, as Figure 1 As shown, when the transmembrane pressure difference of the membrane filtration unit 3 exceeds a preset value, the membrane filtration unit 3 is backflushed to remove the filter cake layer on the surface of the membrane filtration unit 3 .

[0065] Example 1: Preparation of ethyl methyl oxalate by transesterification

[0066] The steps of performing ester exchange using the device of the present invention are: closing the opening valve 4, closing the inlet valve of the micro-interface enhanced mixer 5, opening the inlet of dimethyl oxalate raw material, opening the inlet of ethanol raw material, configuring the ester and alcohol raw materials according to a certain proportion, opening the catalyst inlet C, and adding a sufficient amount of catalyst to the catalyst preparation tank 8 at one time; opening the valve on the discharge pipe of the feed mixer 9, the valve on the feed pipe on the catalyst preparation tank 8 and the inlet valve of the micro-interface enhanced mixer 5, and allowing the reaction raw materials and the catalyst to enter the micro-interface enhanced mixer 5 so that the ester and alcohol raw materials and the catalyst are fully mixed in the micro-interface enhanced mixer 5; the fully mixed reaction raw materials and catalyst are heated in the pre-reactor 6 and pre-reacted; the reaction raw materials and catalyst enter the reactor 1, and the stirring blades 12 in the reactor 1 stir the reaction raw materials and the catalyst.

[0067] When the liquid level in the reactor 1 reaches the specified requirement, open the by-product outlet G valve of the distillation tower 10, open the opening valve 4, and start the circulation pump 2 to allow the reaction liquid and catalyst to circulate between the circulation pipeline and the reactor 1; open the clear liquid side valve of the membrane filtration unit 3, and adjust the opening valve 4 so that the feed from the feed mixer 9 to the micro-interface enhanced mixer 5 and the discharge volume of the clear liquid side of the membrane filtration unit 3 are in a balanced state; by opening the valve of the backwash inlet pipe, the clear liquid discharged from the clear liquid side can enter the backwash tank 7, the backwash tank 7 is replenished; by opening the valves on the catalyst preparation tank 8 and the clear liquid side of the membrane filtration unit 3, the clear liquid can enter the catalyst preparation tank 8 and replenish the catalyst preparation tank 8; by opening the valve at the catalyst inlet position, new catalyst can be added to the catalyst preparation tank 8; after the replenishment is completed, the valves on the catalyst preparation tank 8 and the backwash tank 7 connected to the clear liquid side are closed. At this time, the clear liquid discharged from the clear liquid side enters the subsequent process from the product outlet E, and finally obtains ethyl methyl oxalate.

[0068] As the reaction separation proceeds, the transmembrane pressure difference of the membrane filtration unit 3 gradually increases. When the transmembrane pressure difference reaches a preset value, or the reaction separation time reaches a preset time, the valve on the clear liquid side of the membrane filtration unit 3 is closed, the valve of the backwash outlet pipe on the backwash tank 7 is opened, and the backwash gas inlet valve is opened. The clear liquid in the backwash tank 7 is pressed into the membrane filtration unit 3 by the gas pressure to backwash the membrane filtration unit 3, so that the flux of the membrane filtration unit 3 is restored.

[0069] As the reaction proceeds, the activity of the catalyst gradually decreases. By opening the valve of the waste catalyst discharge pipe and the valve of the feed pipe on the catalyst preparation tank 8, part of the waste catalyst can be discharged and new catalyst can be introduced. The above-mentioned process of discharging the waste catalyst and the process of introducing the new catalyst are carried out simultaneously. While ensuring the activity of the catalyst, the effect of the increase or decrease of the catalyst on the reaction of the reactants in the reactor 1 can be reduced.

[0070] Example 2: Preparation of Ethyl Methyl Carbonate by Transesterification

[0071] The steps of performing ester exchange using the device of the present invention are: closing the opening valve 4, closing the inlet valve of the micro-interface enhanced mixer 5, opening the inlet of the dimethyl carbonate raw material, opening the inlet of the ethanol raw material, configuring the ester and alcohol raw materials according to a certain proportion, opening the catalyst inlet C, and adding a sufficient amount of catalyst to the catalyst preparation tank 8 at one time; opening the valve on the discharge pipe of the feed mixer 9, the valve on the feed pipe on the catalyst preparation tank 8 and the inlet valve of the micro-interface enhanced mixer 5, and allowing the reaction raw materials and the catalyst to enter the micro-interface enhanced mixer 5 so that the ester and alcohol raw materials and the catalyst are fully mixed in the micro-interface enhanced mixer 5; the fully mixed reaction raw materials and catalyst are heated in the pre-reactor 6 and pre-reacted; the reaction raw materials and catalyst enter the reactor 1, and the stirring blades 12 in the reactor 1 stir the reaction raw materials and catalyst to prevent the catalyst from precipitating.

[0072] When the liquid level in the reactor 1 reaches the specified requirement, open the by-product outlet G valve of the distillation tower 10, open the opening valve 4, and start the circulation pump 2 to allow the reaction liquid and catalyst to circulate between the circulation pipeline and the reactor 1; open the clear liquid side valve of the membrane filtration unit 3, and adjust the opening valve 4 so that the feed from the feed mixer 9 to the micro-interface enhanced mixer 5 and the discharge volume of the clear liquid side of the membrane filtration unit 3 are in a balanced state; by opening the valve of the backwash inlet pipe, the clear liquid discharged from the clear liquid side can enter the backwash tank 7, the backwash tank 7 is replenished; by opening the valves on the catalyst preparation tank 8 and the clear liquid side of the membrane filtration unit 3, the clear liquid can enter the catalyst preparation tank 8, and the catalyst preparation tank 8 is replenished; by opening the valve at the catalyst inlet position, new catalyst can be added to the catalyst preparation tank 8; after the replenishment is completed, the valves on the catalyst preparation tank 8 and the backwash tank 7 connected to the clear liquid side are closed. At this time, the clear liquid discharged from the clear liquid side enters the subsequent process from the product outlet E, and finally obtains ethyl methyl carbonate.

[0073] As the reaction separation proceeds, the transmembrane pressure difference of the membrane filtration unit 3 gradually increases. When the transmembrane pressure difference reaches a preset value, or the reaction separation time reaches a preset time, the valve on the clear liquid side of the membrane filtration unit 3 is closed, the valve of the backwash outlet pipe on the backwash tank 7 is opened, and the backwash gas inlet valve is opened. The clear liquid in the backwash tank 7 is pressed into the membrane filtration unit 3 by the gas pressure to backwash the membrane filtration unit 3, so that the flux of the membrane filtration unit 3 is restored.

[0074] As the reaction proceeds, the activity of the catalyst gradually decreases. By opening the valve of the waste catalyst discharge pipe and the valve of the feed pipe on the catalyst preparation tank 8, part of the waste catalyst can be discharged and new catalyst can be introduced. The above-mentioned process of discharging the waste catalyst and the process of introducing the new catalyst are carried out simultaneously. While ensuring the activity of the catalyst, the effect of the increase or decrease of the catalyst on the reaction of the reactants in the reactor 1 can be reduced.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Transesterification reaction separation coupling device, characterized in that: include: The reactor has a feed port at the top and a discharge port at the bottom; A circulation pipeline is located outside the reactor, and both ends of the circulation pipeline are connected to the feed port and the discharge port respectively; the circulation pipeline is sequentially connected to a membrane filtration unit, a micro-interface enhanced mixer and a pre-reactor from the discharge port to the feed port, and the circulation pipeline is also connected to a circulation pump; The catalyst preparation tank is connected to the circulation pipeline between the membrane filtration unit and the micro-interface enhanced mixer through a feed pipe; the circulation pipeline is provided with a waste catalyst discharge pipe upstream of the feed pipe; Wherein, when part of the spent catalyst in the circulation pipeline is discharged regularly, new catalyst is added to the circulation pipeline at the same time.

2. The transesterification reaction separation coupling device according to claim 1, characterized in that: It also includes a feed mixer, the top of which is provided with an ester phase raw material inlet and an alcohol phase raw material inlet. After the ester raw material and the alcohol raw material are mixed in proportion in the feed mixer, they are introduced into the micro interface enhanced mixer.

3. The transesterification reaction separation coupling device according to claim 1, characterized in that: The circulation pump is arranged at the inlet end of the membrane filtration unit, and an opening valve is provided at the outlet end of the membrane filtration unit. The waste catalyst discharge pipe is located at the rear side of the opening valve. The material in the circulation pipeline first passes through the opening valve and then passes through the catalyst discharge pipe.

4. The transesterification reaction separation coupling device according to claim 1, characterized in that: The system also includes a backwash tank, which is connected to the clear liquid side of the membrane filtration unit through a pipeline, and a backwash gas inlet is provided at the top of the backwash tank.

5. The transesterification reaction separation coupling device according to claim 1, characterized in that: The top of the catalyst preparation tank is provided with a catalyst inlet, and the catalyst preparation tank is communicated with the clear liquid side of the membrane filtration unit through a pipeline.

6. The transesterification reaction separation coupling device according to claim 1, characterized in that: A feed distributor is provided at the top of the reactor, and the feed distributor is communicated with a feed port through a pipeline.

7. The transesterification reaction separation coupling device according to claim 1, characterized in that: The waste catalyst discharge pipe is located between the outlet of the membrane filtration unit and the feed pipe.

8. The transesterification reaction separation coupling device according to claim 1, characterized in that: The top of the reactor is connected to a distillation tower via a pipeline, and the top of the distillation tower is provided with a by-product outlet.

9. A transesterification reaction separation coupling method using the transesterification reaction separation coupling device according to any one of claims 1 to 8, characterized in that: The following steps are involved: The ester raw materials and the alcohol raw materials undergo an ester exchange reaction in the reactor under the action of the catalyst, and the materials in the reactor circulate in the circulation pipeline from the discharge port to the feed port; As the material flows through the circulation pipeline, it is filtered by the membrane filtration unit and the filtered clear liquid is discharged. The filtered concentrated slurry continues to flow to the reactor. A mixture of ester raw materials and alcohol raw materials is introduced into the circulation pipeline, and the amount of the added mixture is kept in balance with the amount of clear liquid discharged; Part of the filtered concentrated slurry containing spent catalyst is discharged regularly; at the same time, new catalyst is introduced into the circulation pipeline.

10. The transesterification reaction separation coupling device according to claim 1, characterized in that: When the transmembrane pressure difference of the membrane filtration unit exceeds a preset value, the membrane filtration unit is backflushed to remove the filter cake layer on the surface of the membrane filtration unit.

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