CN217661612U - Recrystallization system for purifying dimethyl 2, 6-naphthalene dicarboxylate - Google Patents

Abstract

The utility model provides a recrystallization system for purifying 2, 6-naphthalene dicarboxylic acid dimethyl ester, include: reation kettle and double-deck suction filter device, reation kettle include the cauldron body, agitating unit and adsorption filtration device, and adsorption filtration device demountable installation is in the internal position that is close to the discharge gate of cauldron. The double-layer suction filtration device comprises a cooling liquid storage tank and a collecting bottle which are communicated with each other, the cooling liquid storage tank is positioned above the collecting bottle, a first filter plate is detachably connected to the position, close to the lower part, of the cooling liquid storage tank, and heat tracing heat preservation devices are arranged on the inner walls of the kettle body and the cooling liquid storage tank. The utility model discloses a set up the heat tracing heat preservation device in reation kettle, guarantee that 2,6-NDC can be stable and smooth and easy ejection of compact, avoid condensing and block up the filter plate, operating efficiency improves, and the energy consumption is low, makes the yield and the purity of the 2,6-NDC of winning all improve to some extent. The double-layer suction filtration device is provided with the heat tracing and heat insulating device, so that the liquid storage tank can be cooled rapidly, and the crystallization speed is accelerated.

Description

Recrystallization system for purifying dimethyl 2, 6-naphthalenedicarboxylate

Technical Field

The utility model relates to the field of new materials in the coal chemical industry, in particular to a recrystallization system for purifying dimethyl 2, 6-naphthalene dicarboxylate.

Background

The coal reserves in China are abundant, and at present, the method has important significance for developing a high added value route of naphthalene as a measure for increasing the comprehensive utilization of heavy components in energy such as coal, petroleum and the like under the condition of increasingly tense energy. Dimethyl-2, 6-Naphthalate (NDC) is a key intermediate for some high-end specialty polyesters, and the main use is in the synthesis of polyethylene-2, 6-naphthalate (PEN). PEN material is a new functional polymer resin material with excellent performance, mainly prepared by esterifying or ester-exchanging and polycondensing 2, 6-naphthalene dicarboxylic acid (2, 6-NDA) or 2,6-NDC with ethylene glycol, and compared with widely used polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), the PEN material has better air tightness, mechanical property, heat resistance, dyeing property, resilience, anti-fouling property and chemical stability. Therefore, PEN polyester materials are widely used in the fields of fiber textile materials, film materials, packaging materials, engineering plastics and the like.

Dimethyl-2, 6-Naphthalene Dicarboxylate (NDC) is obtained mainly by catalytic esterification of 2, 6-naphthalene dicarboxylic acid with methanol. After the methyl esterification reaction, a crude product NDC is precipitated, which also contains by-products such as 2, 6-naphthalenedicarboxylic acid monoester, trimethyl trimellitate, 6-methyl-2-naphthoic acid monoester, trimethyl trimellitate, and methyl 2-methyl-6-naphthoate. The crude ester obtained by this reaction has such parameters as purity, chromaticity, acid value and the like that cannot satisfy the requirements for synthesis of a satisfactory polymeric PEN material, and it is necessary to further refine and purify the crude ester to obtain 2,6-NDC with high accuracy.

The prior art has the following defects:

1. at present, the traditional recrystallization mode adopted for purifying the 2,6-NDC is operated in an intermittent mode, the adopted recrystallization system is simpler and more complicated to operate, the heating and the suction filtration of the 2,6-NDC are separately carried out, the materials need to be quickly transferred, and the smooth discharging can be carried out at least when the heat tracing temperature is higher than 190 ℃ because the melting point (187-193 ℃) and the boiling point (345-350 ℃) of the 2,6-NDC are very high. After the materials are transferred to the suction filtration device, the materials are partially condensed when meeting a filter plate at normal temperature, so that the filter plate is blocked, stable and smooth discharging cannot be further caused, the operation efficiency is low, and the yield of the obtained 2,6-NDC is low.

2. At present, when materials are transferred by adopting a recrystallization system, a solvent is easy to volatilize into the air, and the used solvent is a dimethylbenzene solvent with certain toxicity, so that air pollution can be caused, and the traditional recrystallization system does not meet the requirements of green experiments.

3. When the existing recrystallization system is used for purifying 2,6-NDC, the amount of a recrystallization solvent consumed is large, and an adsorbent is usually directly added into the solvent, so that the consumed adsorbent is large, the adsorbent cannot be recycled, and the adsorbent is wasted.

Disclosure of Invention

An object of the utility model is to provide a recrystallization system for purifying 2, 6-naphthalene dicarboxylic acid dimethyl ester, have high efficiency, easy operation, the energy consumption is low, the characteristics of environmental friendly, when using this system to 2, 6-naphthalene dicarboxylic acid dimethyl ester recrystallization, can high-efficient stable 2, 6-naphthalene dicarboxylic acid dimethyl ester who obtains high purity and color and luster good, can improve the yield.

The embodiment of the application provides a recrystallization system for purifying dimethyl 2, 6-naphthalene dicarboxylate, which comprises: reation kettle and double-deck suction filtration device, reation kettle includes the cauldron body, agitating unit and adsorbs filter equipment, adsorbs filter equipment demountable installation in the internal position that is close to the discharge gate of cauldron, and it is internal that agitating unit locates the cauldron, is equipped with first charge door and second charge door on the cauldron body.

The double-layer suction filtration device comprises a cooling liquid storage tank and a collection bottle which are communicated with each other, the cooling liquid storage tank is positioned above the collection bottle, a first filter plate is detachably connected to the position below the cooling liquid storage tank, vacuumizing ports are formed in the cooling liquid storage tank and the collection bottle, and a discharge port at the bottom end of the reaction kettle is connected with a material transferring port of the cooling liquid storage tank through a pipeline; the inner walls of the kettle body and the cooling liquid storage tank are both provided with heat tracing heat preservation devices.

The utility model discloses a set up the heat tracing heat preservation device in reation kettle, guarantee that 2,6-NDC can be stable and smooth and easy ejection of compact, avoid condensing and block up the filter plate, operating efficiency improves, and the energy consumption is low, makes the yield and the purity of the 2,6-NDC of adopting all improve to some extent. The double-layer suction filtration device is provided with the heat tracing and heat insulating device, so that the liquid storage tank can be cooled rapidly, and the crystallization speed is accelerated.

The utility model discloses a set up adsorption and filtration device, adsorb at the in-process of suction filtration, the adsorbent does not directly add to the solvent of boiling, can reduce the consumption of adsorbent, makes the recoverable recycling of adsorbent, can guarantee 2, 6-NDC's good color and luster simultaneously.

In some embodiments, the heat tracing and heat preserving device is a double-layer jacket, and the double-layer jacket is connected with an external refrigeration and heating circulating device.

In some embodiments, the adsorption filtration device comprises a second filter plate and an adsorption mechanism, wherein the adsorption mechanism is detachably connected to the lower end of the second filter plate, and adsorbent is loaded in the adsorption mechanism.

In some embodiments, the adsorption mechanism includes an adsorbent housing and a lower filter plate, the lower filter plate is disposed at a lower end of an interior of the adsorbent housing, the adsorbent housing is detachably connected to a lower end of the second filter plate, the adsorbent housing is loaded with adsorbent, and the adsorbent is located above the lower filter plate.

In some embodiments, the device further comprises a rotary evaporator, and the discharge port of the collecting bottle is connected with the feed port of the rotary evaporator through a pipeline.

In some embodiments, a first discharge valve is arranged at the discharge port of the kettle body, a second discharge valve is arranged between the cooling liquid storage tank and the collecting bottle, a third discharge valve is arranged at the discharge port of the collecting bottle, and the first discharge valve, the second discharge valve and the third discharge valve are all made of high borosilicate glass.

In some embodiments, a condensation return pipe is communicated with the kettle body.

In some embodiments, the double-layer jacket is glass.

In some embodiments, a temperature sensor and a pressure sensor are arranged in the kettle body.

In some embodiments, the first filter plate and the second filter plate are both sand core filter plates, and the filter pore size is 20-25 μm.

The beneficial effects of the utility model are that:

1. the utility model ensures the stable and smooth discharging of the 2,6-NDC by arranging the heat tracing and heat insulating device in the reaction kettle, avoids the blockage of the filter plate due to condensation, improves the operation efficiency, has low energy consumption and improves the yield and the purity of the extracted 2, 6-NDC; the double-layer suction filtration device is provided with the heat tracing and heat insulating device, so that the liquid storage tank can be cooled rapidly, and the crystallization speed is accelerated.

2. The utility model discloses a set up adsorption and filtration device, adsorb at the in-process of suction filtration, the adsorbent does not directly add to the solvent of boiling, can reduce the consumption of adsorbent, makes the recoverable recycling of adsorbent, can guarantee 2, 6-NDC's good color and luster simultaneously.

3. The utility model discloses a connect rotatory evaporimeter, can retrieve the solvent after the recrystallization, recycle avoids the solvent to volatilize and causes the pollution to the environment.

4. The utility model discloses a recrystallization system has high efficiency, easy operation, the yield is high, the energy consumption is low, environment friendly's characteristics.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments taken in conjunction with the accompanying drawings,

wherein:

FIG. 1 is a schematic diagram of a recrystallization system for purifying dimethyl-2, 6-naphthalenedicarboxylate according to the present invention;

FIG. 2 is a schematic view of the adsorption filtration device of FIG. 1;

reference numerals:

1-a refrigeration heating cycle device;

2-a reaction kettle; 21-a first feed inlet; 22-a second feed inlet; 23-a stirring device; 24-a reflux condenser line; 25-pressure gauge; 26-double-layer jacket; 27-an adsorption filtration device; 271-a second filter plate; 272-a sorbent containment case; 273-lower filter plate; 28-a first discharge valve;

3-double-layer suction filtration device; 31-an exhaust port; 32-transferring port; 33-a first vacuum port; 34-feeding the tank body; 35-a first filter plate; 36-lower tank body; 37-a second vacuum port; 38-collection bottle; 39-third discharge valve; 40-a second discharge valve;

4-rotary evaporator.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present invention, and should not be construed as limiting the present invention.

A recrystallization system for purifying dimethyl 2, 6-naphthalenedicarboxylate according to an embodiment of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, the present example proposes a recrystallization system for purifying dimethyl 2, 6-naphthalenedicarboxylate, comprising: a reaction kettle 2, a double-layer suction filtration device 3 and a rotary evaporator 4 which are connected in sequence.

The reaction kettle 2 comprises a kettle body, a stirring device 23 and an adsorption filtering device 27, wherein the adsorption filtering device 27 is detachably mounted at a position close to a discharge port in the kettle body, the stirring device 23 is arranged in the kettle body, a first feed inlet 21 and a second feed inlet 22 are arranged on the kettle body, the first feed inlet 21 is used for adding a solvent, and the second feed inlet 22 is used for adding molten dimethyl 2, 6-naphthalene dicarboxylate.

Further, drive arrangement is connected to agitating unit 23 upper end, and drive arrangement installs in the cauldron body upper end outside, and drive arrangement specifically is motor and speed reducer for drive agitating unit 23 rotatory stirring. The stirring device 23 comprises a stirring rod and a stirring blade fixedly connected to the stirring rod, which is known in the art and is not shown in the figures. The driving device controls the opening and closing rotating speed of the driving device through the controller, and the rotating speed range is 0-500 r/min. The stirring rod and the stirring blade are both made of stainless steel and wrapped by polytetrafluoroethylene.

Further, the internal temperature sensor and pressure sensor that set up of cauldron for the internal temperature of control cauldron and pressure, it is corresponding, be provided with the thermometer of connecting temperature sensor outside the cauldron body to and connect pressure sensor's manometer 25.

Further, as shown in fig. 2, the adsorption filter device 27 includes a second filter plate 271 and an adsorption mechanism, the adsorption mechanism is detachably connected to a lower end of the second filter plate 271, and an adsorbent is loaded in the adsorption mechanism.

In some specific embodiments, the adsorption mechanism includes an adsorbent receiving case 272 and a lower filter plate 273, the lower filter plate 273 is detachably mounted on the lower end of the inside of the adsorbent receiving case 272, the adsorbent receiving case 272 is detachably connected to the lower end of the second filter plate 271, the adsorbent receiving case 272 is loaded with adsorbent, and the adsorbent is located above the lower filter plate 273. The micropores of the lower filter plate 273 prevent the adsorbent from leaking out, and allow the lower filter plate 273 to pass only liquid but not solid.

The adsorbent housing case 272 is a cartridge, and the filtration region of the second filter sheet 271 completely covers the adsorbent housing case 272, so that the liquid falling from the second filter sheet 271 can completely enter the adsorbent housing case 272. The second filter plate 271 is a teflon sand core filter plate having a filter pore size of about 20 to 25 μm and is used for filtering the insoluble matter in hot xylene.

The last equipartition of adsorbent storage shell 272 has a plurality of through-hole for will pass through absorption and filterable solution, thereby the circulation is to in the double-deck suction filtration device 3.

Optionally, the adsorbent is activated carbon or activated clay. Among them, activated carbon is generally porous amorphous carbon having a strong adsorption ability in a powdery or granular form. The granular activated carbon can be cylindrical, spherical, hollow cylindrical, hollow spherical and irregular-shaped broken carbon, and the like. The activated carbon has good decolorizing effect and can effectively remove the chromaticity in the solution.

Activated clay, also known as bleaching earth, is a fine-grained, naturally occurring, high-adsorption-rate earthy substance having the ability to adsorb impurities or colored substances from fats, oils or oils. The bleaching clay has wide decolorizing performance, great decolorizing power, strong adsorbability and purification capacity, and strong adsorbability to pigments and impurities. Can be recycled and does not pollute the environment.

In some specific embodiments, the removable connection relationship between the adsorbent receiving case 272 and the second filter plate 271 may be various. In one embodiment, one side of the upper end of the adsorbent receiving case 272 is hinged to the lower end of the second filter plate 271 through a hinge, and the other side of the upper end of the adsorbent receiving case may be provided with a snap fit to engage with a snap groove at the lower end of the second filter plate 271. As another example, both opposite sides of the upper end of the adsorbent receiving case 272 are connected to the second filter sheet 271 by a snap. As another embodiment, the lower end of the second filter plate 271 and the adsorbent receiving case 272 may be connected by a fastener, and further, the edge of the upper end of the adsorbent receiving case 272 extends outward to form a rim, and the rim is connected to the second filter plate 271 by a bolt.

The utility model discloses a set up adsorption and filtration device 27, adsorb at the in-process of suction filtration, the adsorbent does not directly add to the solvent of boiling, can reduce the consumption of adsorbent, makes the recoverable recycling of adsorbent, can guarantee 2, 6-NDC's good color and luster simultaneously.

In some specific embodiments, the upper end of the kettle body is communicated with a condensate return pipe 24, and circulating condensate water or other cooling media are introduced into the condensate return pipe 24. When the 2,6-NDC in the kettle body is dissolved with the solvent, the solvent can volatilize when meeting high temperature, the volatilized solvent enters the condensing reflux pipe 24, and the solvent is condensed into liquid after precooling and falls into the kettle body again.

In some specific embodiments, the inner wall of the kettle body is provided with a heat tracing and heat insulating device, the heat tracing range is-30-200 ℃, the stable and smooth discharging of the 2,6-NDC can be ensured, the filter plate is prevented from being blocked by condensation, the operation efficiency is improved, the energy consumption is low, and the yield and the purity of the extracted 2,6-NDC are improved.

In some specific embodiments, the heat tracing thermal insulation device is specifically a double-layer jacket 26, and the double-layer jacket 26 is connected with the external refrigeration and heating cycle device 1.

In some specific embodiments, the autoclave body is a borosilicate glass autoclave body, the volume of the autoclave body is 20L, the use temperature is-80 to 200 ℃, the double-layer jacket 26 is made of glass, and heat-conducting media such as heat-conducting oil or water are introduced into the double-layer jacket 26 and used for heat tracing of the autoclave body.

In some specific embodiments, reaction kettle 2 is split type, including the kettle cover, go up the cauldron body and the cauldron body down that top-down can dismantle the connection in proper order, goes up the contact surface between the cauldron body and the cauldron body down and is equipped with the sealing washer, goes up cauldron body lower extreme and outwards extends and has the border, and cauldron body upper end outwards extends and has the border down, and the border of going up the cauldron body and the cauldron body down passes through bolted connection back, and the sealing washer can play sealed effect. The connection relationship between the kettle cover and the upper kettle body is the same as the connection mode of the upper kettle body and the lower kettle body.

The first feed inlet 21, the second feed inlet 22, the condensation reflux pipe 24, the driving device, the thermometer and the pressure gauge 25 are all arranged on the kettle cover.

The second filter plate 271 is detachably connected in the lower kettle body in various manners, such as in the form of bolts or buckles. When the solid filtered by the second filter plate 271 needs to be taken out, the lower kettle body can be detached from the upper kettle body. When the adsorption device needs to be replaced, the adsorption device is detached from the second filter plate 271 in the detached lower kettle body. When the adsorbent needs to be replaced, the adsorbent storage case 272 may be opened in the detached adsorption device. The lower end of the lower kettle body is provided with a discharge hole and a first discharge valve 28.

In some specific embodiments, the kettle is externally supported by a support with a lifting function, and the kettle cover, the upper kettle body and the lower kettle body can be respectively lifted by arranging a lifting rocker, so that the kettle body can be detached, cleaned and overhauled, and the filter plate can be cleaned.

The discharge port at the bottom end of the reaction kettle 2 is connected with a material transferring port 32 of the cooling liquid storage tank through a pipeline.

Double-deck suction filter device 3 is including the cooling liquid storage pot and the receiving flask 38 of intercommunication each other, and the cooling liquid storage pot is located receiving flask 38 top, and the upper end of cooling liquid storage pot is equipped with first evacuation mouth 33, gas vent 31 and commentaries on classics material mouth 32, and first evacuation mouth 33 is used for connecting the vacuum pump, carries out 2 suction filters of reation kettle, and suction filter first time promptly, and the solution after with the suction filter passes through the pipeline and enters into the cooling liquid storage pot via commentaries on classics material mouth 32.

The position of the cooling liquid storage tank close to the lower part is detachably connected with a first filter plate 35, the first filter plate 35 adopts a tetrafluoro sand core filter plate, and the filter aperture is 20-25 mu m.

The volume of the cooling liquid storage tank is 20L, and the use temperature is-80-200 ℃.

In some embodiments, the first filter plate 35 is covered with a filter cloth, which may be made of polypropylene, and the filter pore size is 20 μm.

In some specific embodiments, the inner wall of the cooling liquid storage tank is provided with a heat tracing and heat insulating device, the heat tracing range is-30-200 ℃, the cooling liquid storage tank can be cooled, the temperature is reduced to be below 10 ℃, and in order to recrystallize 2,6-NDC.

In some specific embodiments, the heat tracing thermal insulation device is specifically a double-layer jacket 26, a heat conducting medium such as heat conducting oil or water is used in the double-layer jacket 26, and the double-layer jacket 26 is connected to the external refrigeration heating cycle device 1. The liquid storage tank can be cooled rapidly, and the crystallization speed is accelerated.

In some embodiments, the cooling reservoir is a split type, and includes an upper tank 34 and a lower tank 36 detachably connected to each other in the same manner as the reaction vessel 2, and the first filter plate 35 is detachably disposed in the lower tank 36. The connection mode between the first filter plate 35 and the lower tank 36 is the same as the connection mode between the second filter plate 271 and the tank, and is not described herein.

A second emptying valve 40 is arranged between the cooling liquid storage tank and the collecting bottle 38, emptying is controlled through a knob switch, the switch is in a closed state during the first suction filtration, and the switch is opened during the second suction filtration.

And a second vacuum-pumping port 37 and an exhaust port 31 are arranged on the collecting bottle 38, the second vacuum-pumping port 37 is used for connecting a vacuum pump to carry out suction filtration for the second time, and the solution after suction filtration enters the collecting bottle 38. A second suction filtration was used for recrystallization of the 2,6-NDC, the crystals were left on the upper end of the first filter plate 35, and the solvent was suction filtered into the collection bottle 38. A third discharge valve 39 is arranged at the discharge port of the collecting bottle 38, and discharge is controlled by a knob switch and is used for transferring the solvent xylene into the rotary evaporator 4.

In some embodiments, the first discharge valve 28, the second discharge valve 40, and the third discharge valve 39 are all made of borosilicate glass.

In some specific embodiments, the rotary evaporator 4 is further included, and the discharge port of the collecting bottle 38 is connected with the feed port of the rotary evaporator 4 through a pipeline. The xylene is conveyed to a collecting bottle 38 of the rotary evaporator 4 by connecting a diaphragm vacuum pump on the pipeline, so that the continuous distillation process can be realized.

The specific operation mode is as follows:

adding the 2,6-NDC to be purified into the kettle body of the reaction kettle 2 through a second feed opening 22, adding a solvent xylene into the kettle body of the reaction kettle 2 through a first feed opening 21, wherein the dosage of the xylene solvent is 4-8 times of the mass of the 2,6-NDC, adjusting a temperature controller of the refrigeration and heating circulating device 1, heating the kettle body, and heating and boiling the solution for 30 minutes. The vacuum pump of the first vacuum port 33 and the first discharge valve 28 are opened, and the hot filtrate passes through the adsorption and filtration device 27, wherein the dosage of the adsorbent in the adsorption and filtration device 27 is 3-10% of the mass of the 2,6-NDC to be purified. And (3) feeding the solution after suction filtration into a cooling liquid storage tank, adjusting a temperature controller of the refrigeration heating circulating device 1, cooling for 30 minutes below 10 ℃, opening a vacuum pump of a second vacuum pumping port 37 and a second discharge valve 40, carrying out second suction filtration, carrying out solid-liquid separation on the cooled and precipitated 2,6-NDC, and cooling the solid obtained in the liquid storage tank to obtain the white needle-shaped crystal 2,6-NDC. The purity was >99.95% and the yield of 2,6-NDC was 96%. The filtrate enters the collection bottle 38. The filtrate in the collection flask 38 is then pumped into the rotary evaporator 4 and the solvent is rapidly recovered by distillation under reduced pressure.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like, indicate the orientation or positional relationship indicated based on the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; may be mechanically coupled, may be electrically coupled or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.

In the present application, unless expressly stated or limited otherwise, the first feature may be directly on or directly under the second feature or indirectly via intermediate members. Also, a first feature "on," "above," and "over" a second feature may be directly on or obliquely above the second feature, or simply mean that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the present disclosure, the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art without departing from the scope of the present invention.

Claims (10)

1. A recrystallization system for purifying dimethyl 2, 6-naphthalenedicarboxylate comprising:

the reaction kettle comprises a kettle body, a stirring device and an adsorption and filtration device, wherein the adsorption and filtration device is detachably arranged in the kettle body at a position close to the discharge port;

the double-layer suction filtration device comprises a cooling liquid storage tank and a collecting bottle which are communicated with each other, the cooling liquid storage tank is positioned above the collecting bottle, a first filter plate is detachably connected to the position, close to the lower part, of the cooling liquid storage tank, vacuumizing ports are formed in the cooling liquid storage tank and the collecting bottle, and a discharge port at the bottom end of the reaction kettle is connected with a material transferring port of the cooling liquid storage tank through a pipeline; the inner walls of the kettle body and the cooling liquid storage tank are both provided with heat tracing heat preservation devices.

2. The recrystallization system according to claim 1, wherein the heat tracing and heat preserving device is a double-layer jacket, and the double-layer jacket is connected with an external refrigerating and heating circulating device.

3. The recrystallization system according to claim 1, wherein the adsorption filtration device comprises a second filter plate and an adsorption mechanism, the adsorption mechanism is detachably connected to a lower end of the second filter plate, and the adsorption mechanism is loaded with an adsorbent.

4. The recrystallization system according to claim 3, wherein the adsorption mechanism comprises an adsorbent receiving case and a lower filter plate, the lower filter plate is disposed at a lower end of an interior of the adsorbent receiving case, the adsorbent receiving case is detachably attached to a lower end of the second filter plate, the adsorbent receiving case is loaded with the adsorbent, and the adsorbent is located above the lower filter plate.

5. The recrystallization system according to claim 1, further comprising a rotary evaporator, wherein the discharge port of the collecting bottle is connected with the feed port of the rotary evaporator through a pipeline.

6. The recrystallization system according to claim 1, wherein a first emptying valve is arranged at a discharge port of the kettle body, a second emptying valve is arranged between the cooling liquid storage tank and the collecting bottle, a third emptying valve is arranged at a discharge port of the collecting bottle, and the first emptying valve, the second emptying valve and the third emptying valve are all made of borosilicate glass.

7. The recrystallization system according to any one of claims 1 to 6, wherein a condensing return pipe is communicated with the kettle body.

8. The recrystallization system according to claim 2, wherein the double-walled jacket is a glass material.

9. The recrystallization system according to claim 2, wherein a temperature sensor and a pressure sensor are provided in the tank body.

10. The recrystallization system according to claim 3, wherein the first filter plate and the second filter plate are sand core filter plates, and the filter pore size is 20 to 25 μm.

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