CN113842665A - Leaching tower, system and method for purifying ester compounds - Google Patents
Leaching tower, system and method for purifying ester compounds Download PDFInfo
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Abstract
The invention discloses a leaching tower, wherein at least one group of flow guide members are arranged in the leaching tower and are fixed on a central shaft at the axis of the leaching tower; each group of flow guide members comprises at least two flow guide rings, each flow guide ring is a hollow circular table, and the bottom surface of each circular table is parallel to the central axis; the adjacent guide rings are communicated and fixed through at least one pipeline. The invention also discloses a purification system, comprising: a pretreatment unit, optionally an impurity removal unit, a crystallization unit, a leaching unit, optionally a post-treatment unit. The invention also discloses a method for purifying the ester compound by adopting the system. The invention has the advantages of high recovery rate, simple and continuous process, low energy consumption and the like, and particularly, the whole process does not need a rectification unit by adopting the purification process.
Description
Technical Field
The invention relates to a leaching tower, a system for purifying ester compounds and a method for purifying the ester compounds by adopting the system.
Background
Dimethyl 2, 6-naphthalene dicarboxylate (2,6-NDC) is an important intermediate for preparing various polyesters, polyurethanes, polyamides and liquid crystal resins, and particularly, 2,6-NDC can be used for producing novel polyester polyethylene naphthalate (PEN), so that the research and development of 2,6-NDC have been widely focused by various large-scale enterprises abroad since the 90 s of the 20 th century.
The PEN has the structural formula shown above, compared with the traditional polyester PET, a benzene ring in the system is substituted by a naphthalene ring with better rigidity, so that the PEN has more excellent performance compared with the PET, and the potential application of the PEN covers all fields in which the PET can be applied and can provide better performance. First PEN for CO2And O2The permeability of the PEN film is only about 30 percent of that of the traditional PET, and the PEN has better air tightness, so that the PEN film can better store food. Meanwhile, PEN has high modulus, high strength, tensile resistance and creep resistance, so that PEN can be used for manufacturing tires, conveyor belts, high-pressure conveying pipes and the like; finally, PEN has excellent chemical resistance and ultraviolet resistance, and is an excellent material for manufacturing various cables. In addition, PEN has a reduced crystallization rate compared to PET, and transparent blow molded articles can be obtained.
The key to the production of PEN is to obtain polymeric grade monomers. PEN production can take two routes, one is the direct polymerization of 2, 6-naphthalene dicarboxylic acid (2,6-NDA) with ethylene glycol; the other is the ester exchange polymerization of 2,6-NDC and ethylene glycol. Although the process of the first route is simple, the melting point of the monomer 2,6-NDA is as high as 310 ℃, the vapor pressure is low, and the solubility in various organic solutions is poor, so that the 2,6-NDA is difficult to purify by adopting an efficient separation method; the second route entails first esterifying the 2,6-NDA with methanol and then purifying the esterification product and polymerizing it with ethylene glycol. Compared with the first route, the method is relatively complex and methanol is generated as a byproduct in the polymerization process, however, the melting point of the 2,6-NDC is far lower than that of the 2,6-NDA and is about 190 ℃, and meanwhile, the solubility of the 2,6-NDC in an organic solvent is far higher than that of the 2,6-NDA, so that the 2,6-NDC can be purified in the forms of crystallization, rectification and the like. As the purification of 2,6-NDC is relatively easy, the industrialization of PEN production is realized by the Bp-Amoco company by adopting the process route for the first time.
The crude ester product obtained after the esterification reaction contains a large amount of 2,6-NDC, and also contains incompletely reacted monomethyl 2, 6-naphthalenedicarboxylate (MM-2,6-NDC), unreacted 2,6-NDA, trimellitate, methyl 2-naphthoate, methyl 2-formyl-6-naphthoate (2,6-FNC), methyl 2-acetyl-6-naphthoate (2,6-ANC), and impurities such as a catalyst introduced in the earlier process. U.S. Pat. No. 5,5262560 reports in detail a process for the separation and purification of 2,6-NDC by the combined use of crystallization and rectification. Firstly, carrying out hot filtration on an esterified product obtained by the reaction after the esterification reaction so as to remove impurities insoluble in a system; then dissolving the obtained esterification product in methanol at 150 ℃, wherein the mass ratio of the methanol to the crude ester is about 5:1, and when the crude ester is completely dissolved, carrying out primary crystallization on the system, wherein the final cooling temperature of the crystallization is about 20 ℃; dissolving the product obtained by the primary crystallization in methanol at 150 ℃ for secondary crystallization, controlling the final temperature of cooling the secondary crystallization to be about 60 ℃, and obtaining a mixed product of 2,6-NDC and MM-2,6-NDC with higher purity after the secondary crystallization, wherein the yield is 75-90%; and finally, rectifying and purifying the secondary crystallization product to obtain the polymerization-grade 2,6-NDC, and feeding the MM-2,6-NDC and the unreacted 2,6-NDA which are positioned in the tower kettle in the rectifying process into the esterification reactor again for esterification.
In the crystallization process, methanol can be selected as a solvent, and o-xylene can also be used as a solvent, however, when o-xylene is used as a solvent, the o-xylene is required to be recovered, so that the process flow becomes complicated; and the methanol is used as a solvent, and can directly enter the esterification unit for esterification without solvent recovery. US patent US6013831 teaches that recovery and reuse of the metal catalyst separated from the crystallization unit in the previous oxidation unit can improve the grain distribution of the crystallization unit. In the rectification process, the temperature of the tower kettle is controlled to be 210-290 ℃, and vacuum rectification is adopted at the same time, wherein the pressure is 7.9-13 kPa. In order to prevent the degradation of the 2,6-NDC in the rectification process, a stabilizer can be added during the rectification, and the commonly used stabilizer is organic phosphate or low molecular weight monohydric alcohol and the like. When the rectifying tower adopts a packed tower, in order to prevent heavy components from blocking the packing in the rectifying process, the feeding point of the feeding can be positioned below the packing.
During the rectification process, the tower kettle is prevented from being silted up due to overhigh viscosity of the materials at the tower kettle. Japanese patent JP1989249746 teaches that the addition of a high boiling point solvent (such as dibutyl phthalate, trioctyl phosphate, etc.) during rectification is effective in improving the fluidity of the column bottom material, thereby preventing the column bottom from clogging during the rectification. Concentrated sulfuric acid is used as a catalyst in the esterification reaction, and the fluidity of the tower bottom of the rectification unit can be improved, because the concentrated sulfuric acid can react with a metal catalyst to generate soluble salt substances, the metal catalyst is removed in a recrystallization unit, and materials entering the rectification unit contain no or only trace metal compounds.
Eastman chemical reports a process for separating and purifying 2,6-NDC by flash distillation and rectification. The reaction mixture is first esterified in an esterification reactor. The gaseous product in the upper part of the reactor and the liquid product in the lower part of the reactor are fed into the first flash tank through a pressure reducing valve, and the operation pressure can be normal pressure or small negative pressure. Most of the 2,6-NDC in the esterification reaction enters the gas phase through flash evaporation, and due to the entrainment effect, a part of MM-2,6-NDC which is not completely reacted and unreacted 2,6-NDA in the gas phase need to be further rectified and separated.
As can be seen from the existing process for separating and purifying 2,6-NDC, the following defects exist: the processes need to adopt a rectification link to obtain a final product, and the energy consumption is high.
Disclosure of Invention
The invention aims to provide a leaching tower, a system for purifying ester compounds and a method for purifying the ester compounds by adopting the system, aiming at the defects in the existing esterification process. The invention has the advantages of high recovery rate, simple and continuous process, low energy consumption and the like, and particularly, the whole process does not need a rectification unit by adopting the purification process.
In order to realize the aim of the invention, the invention provides a leaching tower, wherein at least one group of flow guide components are arranged in the leaching tower and are fixed on a central shaft at the axis of the leaching tower; each group of flow guide members comprises at least two flow guide rings, each flow guide ring is a hollow circular table, and the bottom surface of each circular table is parallel to the central axis; the adjacent guide rings are communicated and fixed through at least one pipeline.
According to a preferred embodiment of the invention, the central axis is located at the axis of the leaching tower, and at least one end of the central axis is fixedly connected with the top surface or the bottom surface of the impregnation tower.
According to a preferred embodiment of the invention, 2-6 sets of flow guiding elements are arranged inside the leaching tower.
According to a preferred embodiment of the invention the distance between two adjacent sets of flow guiding members is between 1/20 and 1/2 tower heights, preferably between 1/10 and 1/3 tower heights, more preferably 1/6 tower heights.
According to a preferred embodiment of the invention each set of flow guiding members comprises 2-6 flow guiding rings, preferably symmetrically arranged along the central axis.
According to a preferred embodiment of the present invention, two bottom surfaces of the deflector ring are provided with holes, and the hole opening ratio is 1-30%.
According to a preferred embodiment of the invention, the included angle between the side surface and the bottom surface of the circular truncated cone is 10-80 ℃, preferably 20-60 ℃, and more preferably 30-50 ℃.
According to the preferred embodiment of the present invention, the guide ring closest to the central axis is provided with a circulating liquid inlet. If two guide rings are arranged at equal distance from the central axis, one guide ring is selected to be provided with a circulating liquid inlet. The position of the circulating liquid inlet can be positioned at any position on the guide ring, preferably on the bottom surface of the guide ring, and is used for introducing the circulating leaching agent.
According to a preferred embodiment of the present invention, adjacent deflector rings are connected and fixed by at least one, preferably two, conduits.
According to the preferred embodiment of the invention, the guide rings of the same group of guide members are connected and fixed through pipelines, and the pipelines can communicate the adjacent guide rings. The guide ring closest to the central shaft is provided with a circulating liquid inlet, and liquid entering the guide ring flows to the connected guide ring through a pipeline and further flows to other guide rings.
According to some embodiments of the invention, the leach tower further comprises at least one set of circulation members, the circulation members comprising a booster pump, a feed circulation line, and a discharge circulation line.
According to a preferred embodiment of the invention, the booster pump is arranged outside the column.
According to the preferred embodiment of the invention, one end of the tower inlet circulating pipeline is connected with an outlet of a booster pump, and the other end of the tower inlet circulating pipeline is connected with a circulating liquid inlet on the guide ring; one end of the tower outlet circulation pipeline is connected with an inlet of the booster pump, and a port at the other end is arranged at the center of the flow guide component.
According to a preferred embodiment of the invention, the extraction of lixiviant by the circulation means is at least 1/10 of the whole column lixiviant feed flow rate.
When the liquid circulation device works, a part of liquid is led out from the center of the flow guide member through the circulation member, and circulates back to the flow guide rings of the flow guide member after passing through the booster pump, the liquid is discharged from the bottom surfaces of the flow guide rings, and the flow speed of the liquid circulating back to the flow guide rings is increased due to the boosting effect.
According to some embodiments of the invention, the leaching tower is provided with a feed inlet, a discharge outlet and a leaching agent inlet.
According to a preferred embodiment of the invention, the feed inlet may be located at the top or bottom of the leaching tower, preferably at the top of the leaching tower, for introducing the material to be leached.
The material to be leached is introduced from the feed inlet at the top, falls onto the side surface of the guide ring in the falling process, and the side surface is inclined, so that the falling of the material is accelerated.
According to a preferred embodiment of the invention, the discharge port is located at the bottom of the leaching tower for discharging leached material.
According to a preferred embodiment of the invention, the lixiviant inlet may be located at the top or bottom of the leaching tower, preferably at the bottom of the leaching tower, for the introduction of the lixiviant.
According to a preferred embodiment of the invention, the material to be leached and the leaching agent can be flowed cocurrently, cocurrently or crosscurrently.
In another aspect of the invention, there is provided a purification system comprising a leaching tower according to one aspect of the invention.
According to a preferred embodiment of the present invention, the purification system comprises:
the pretreatment device is used for pretreating the crude product to be purified and removing insoluble substances in the crude product;
optionally, an impurity removal device for receiving the product from the pretreatment device and removing impurities from the product;
the crystallization device is used for receiving the product from the pretreatment device and/or the product from the impurity removal device and carrying out crystallization treatment on the product to obtain a crystal I;
the leaching device is used for receiving the crystal I from the crystallization device and leaching the crystal I to obtain a crystal II;
optionally a post-treatment unit for receiving and post-treating the crystals II from the leaching unit.
According to a preferred embodiment of the invention, the leaching apparatus is a leaching tower according to the previous aspect of the invention.
According to a preferred embodiment of the present invention, the pretreatment device comprises:
the dissolving device is used for dissolving the crude product to be purified to obtain mixed liquor;
and the separation device is used for receiving the mixed liquid from the dissolving device, separating the mixed liquid and removing insoluble substances in the mixed liquid to obtain a solution.
According to a preferred embodiment of the invention, the dissolving device is provided with a mixed liquor outlet.
According to a preferred embodiment of the invention, the separation device is provided with a mixed liquor inlet, a solution outlet and a discharge opening.
According to a preferred embodiment of the present invention, the mixed liquid inlet of the separation device is connected to the mixed liquid outlet of the dissolution device, and the solution outlet of the separation device is connected to the crystallization device.
According to a preferred embodiment of the invention, the separation device is a centrifuge.
According to a preferred embodiment of the invention, the impurity removing device comprises an inlet and an outlet, the inlet of the impurity removing device is connected with the solution outlet of the separating device, and the outlet of the impurity removing device is connected with the crystallizing device.
According to a preferred embodiment of the present invention, the impurity removing device is an activated carbon adsorption tower, and the solution from the separation device is subjected to adsorption treatment to remove colored impurities.
According to a preferred embodiment of the invention, the crystallization device comprises an inlet and an outlet, the inlet of the crystallization device is connected with the solution outlet of the separation device or the outlet of the impurity removal device, and the outlet of the crystallization device is connected with the feed inlet of the leaching device.
According to a preferred embodiment of the invention, the post-treatment device comprises an inlet and an outlet, the inlet of the post-treatment device being connected to the outlet of the leaching tower.
According to a preferred embodiment of the invention, the post-treatment device is a drying device, for example an oven.
According to a further aspect of the invention there is provided the use of a leach tower according to the first aspect or a system according to the second aspect for the purification of esters, particularly for the continuous purification of esters.
According to a preferred embodiment of the present invention, the ester compound has the general formula: a- (R1-COO-R2)2，
Wherein A is C6-C20 aryl, preferably C6-C12 aryl, and more preferably benzene ring or naphthalene ring; r1 is a bond or alkylene of C1-C6, preferably a bond, methylene, ethylene, propylene or butylene; r2 is C1-C6 alkyl, preferably methyl, ethyl, propyl or butyl.
According to a preferred embodiment of the present invention, the ester compound is dimethyl naphthalate, preferably dimethyl 2, 6-naphthalate.
In another aspect, the present invention provides a method for purifying an ester compound, comprising the steps of:
(1) pretreating a crude product containing the ester compound to remove insoluble substances in the crude product;
(2) optionally, removing impurities from the pretreated product;
(3) crystallizing the pretreated product and/or the impurity-removed product to obtain a crystal I;
(4) leaching the crystal I to obtain a crystal II;
(5) optionally, the crystals II are worked up.
According to a preferred embodiment of the present invention, the ester compound has the general formula: a- (R1-COO-R2)2，
Wherein A is C6-C20 aryl, preferably C6-C12 aryl, and more preferably benzene ring or naphthalene ring; r1 is a bond or alkylene of C1-C6, preferably a bond, methylene, ethylene, propylene or butylene; r2 is C1-C6 alkyl, preferably methyl, ethyl, propyl or butyl.
According to a preferred embodiment of the present invention, the ester compound is dimethyl naphthalate, preferably dimethyl 2, 6-naphthalate.
According to some embodiments of the invention, the pre-processing comprises:
(1A) dissolving ester compounds to obtain a mixed solution;
(1B) and (4) separating the mixed solution to remove insoluble substances to obtain a solution.
According to a preferred embodiment of the present invention, the ester-containing compound is dissolved with a solvent in step (1A). The solvent is a good solvent for any ester compound, including but not limited to alkylbenzene, lower aliphatic alcohol, lower aliphatic acid, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, etc., wherein the preferred organic solvent is xylene, methanol, acetic acid, etc.
According to a preferred embodiment of the present invention, the dissolution temperature in step (1A) is not lower than 80 ℃, preferably not lower than 100 ℃.
According to a preferred embodiment of the present invention, the separation treatment in step (1B) may be performed by various methods known to those skilled in the art, such as centrifugation of the mixed solution to remove insoluble materials therein to obtain a solution.
According to the preferred embodiment of the invention, in the step (2), the pretreated product is subjected to impurity removal treatment by activated carbon adsorption to remove colored impurities.
According to a preferred embodiment of the invention, the retention time of the adsorption is not less than 0.1h, preferably 0.5-3 h, and the adsorption temperature is not less than the dissolution temperature in step (1).
According to a preferred embodiment of the present invention, the crystallization treatment in step (3) adopts temperature reduction crystallization, and the temperature reduction rate should not be greater than 10 ℃/min, and preferably the temperature reduction rate is less than or equal to 1 ℃/min.
According to a preferred embodiment of the invention, the resulting crystal I particle size of the crystallization unit is greater than 100um, preferably greater than 1000 um.
According to a preferred embodiment of the invention, the leaching agent used in the leaching process comprises one or more of an alcohol and an acid compound, preferably comprises one or more of a fatty alcohol, a cycloaliphatic alcohol and a fatty acid, more preferably a fatty alcohol from C1 to C6.
According to a preferred embodiment of the invention, the temperature of the leaching treatment is between 0 and 100 ℃, preferably between 20 and 80 ℃.
According to a preferred embodiment of the invention, the leaching treatment time is not less than 0.5h, preferably 0.5-5 h.
According to a preferred embodiment of the invention, the leaching treatment is carried out using a leaching tower according to the first aspect of the invention.
According to a preferred embodiment of the invention, the mass ratio of the liquid-solid two-phase feed in the leaching column is (1-10): 1, preferably (3-7): 1.
in another aspect of the present invention, there is provided a method for purifying an ester compound using the system of the second aspect of the present invention, comprising the steps of:
(a) pretreating the crude product containing the ester compound in a pretreatment device to remove insoluble substances in the crude product;
(b) optionally, the product from the pretreatment device enters an impurity removal device and is subjected to impurity removal treatment in the impurity removal device;
(c) enabling the product from the pretreatment device and/or the product from the impurity removal device to enter a crystallization device and carrying out crystallization treatment in the crystallization device to obtain a crystal I;
(d) the crystal I enters a leaching device and is leached in the leaching device to obtain a crystal II;
(e) optionally, the crystals II are passed to a post-treatment apparatus and post-treated therein.
According to a preferred embodiment of the present invention, the ester compound has the general formula: a- (R1-COO-R2)2，
Wherein A is C6-C20 aryl, preferably C6-C12 aryl, and more preferably benzene ring or naphthalene ring; r1 is a bond or alkylene of C1-C6, preferably a bond, methylene, ethylene, propylene or butylene; r2 is C1-C6 alkyl, preferably methyl, ethyl, propyl or butyl.
According to a preferred embodiment of the present invention, the ester compound is dimethyl naphthalate, preferably dimethyl 2, 6-naphthalate.
According to a preferred embodiment of the present invention, the step (a) comprises:
(a1) dissolving a crude product containing ester compounds in a dissolving device to obtain a mixed solution;
(a2) and (3) enabling the mixed solution to enter a separation device, separating the mixed solution in the separation device, and removing insoluble substances in the mixed solution to obtain a solution.
According to a preferred embodiment of the present invention, the crude product containing the ester compound is dissolved in step (a1) with a solvent. The solvent is a good solvent for any ester compound, including but not limited to alkylbenzene, lower aliphatic alcohol, lower aliphatic acid, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, etc., wherein the preferred organic solvent is xylene, methanol, acetic acid, etc.
According to a preferred embodiment of the present invention, the dissolution temperature in step (a1) is not lower than 80 ℃, preferably not lower than 100 ℃.
According to a preferred embodiment of the present invention, the separation process in step (a2) can be performed by various separation devices known to those skilled in the art, such as a centrifuge, to remove insoluble materials from the mixture and obtain a solution.
According to a preferred embodiment of the present invention, the residence time in step (b) is not less than 0.1h, preferably 0.5 to 3h, and the adsorption temperature is not less than the dissolution temperature in step (1).
According to a preferred embodiment of the present invention, the crystallization treatment in step (c) is temperature reduction crystallization, wherein the temperature reduction rate should not be greater than 10 ℃/min, and preferably the temperature reduction rate is less than or equal to 1 ℃/min.
According to a preferred embodiment of the invention, the resulting crystal I particle size of the crystallization unit is greater than 100um, preferably greater than 1000 um.
According to a preferred embodiment of the invention, the leaching agent used in the leaching process comprises one or more of an alcohol and an acid compound, preferably comprises one or more of a fatty alcohol, a cycloaliphatic alcohol and a fatty acid, more preferably a fatty alcohol from C1 to C6.
According to a preferred embodiment of the invention, the temperature of the leaching treatment is between 0 and 100 ℃, preferably between 20 and 80 ℃.
According to a preferred embodiment of the invention, the leaching treatment time is not less than 0.5h, preferably 0.5-5 h.
According to a preferred embodiment of the invention, the liquid phase coming out of the leaching tower is directly sent to the esterification unit, and the solid phase crystal II coming out is sent to a drying device for drying, and the drying can adopt any form, such as drum drying, drying tower drying and the like.
By adopting the technical scheme of the invention, the following beneficial effects can be obtained:
the process of the invention adopts a leaching link to remove the monoester which is difficult to remove in the crystallization process, thereby saving the rectification link and greatly reducing the energy consumption and the operation difficulty; the whole process is efficient, continuous production is easy to realize, and the method is suitable for industrial application.
Drawings
FIG. 1 is a schematic diagram of a leaching tower according to one embodiment of the invention;
FIG. 2 is a schematic view of a flow directing member according to one embodiment of the present invention;
FIG. 3 is a schematic diagram of a purification system according to one embodiment of the present invention;
description of reference numerals: 1 is a leaching tower; 2 is a flow guide component; a booster pump is arranged at the position 3; 4 is a tower inlet circulating pipeline; 5 is a tower outlet circulation pipeline; 6 is a middle shaft; 7 is a flow guide ring; 8 is a pipeline; 9 is a bottom surface; 10 is a dissolving tank; 11 is a centrifuge; 12 is an active carbon adsorption tower; 13 is a crystallizing tank; 14 is a drying device; 15 is a crystal; and 16 is an extracting agent.
Detailed Description
The invention is further illustrated by the following figures and examples, but is not limited to these examples.
As shown in figure 1, one embodiment of the invention provides a leaching tower 1, 5 groups of flow guide components are arranged in the leaching tower 1, and the flow guide components are fixed on a central shaft 6 at the axial center of the leaching tower; the distance between two adjacent sets of flow guide members is about 1/6 tower heights; each group of flow guide parts comprises 8 flow guide rings 7 (shown in fig. 2), each flow guide ring 7 is a hollow circular table, and the bottom surface of each circular table is parallel to the middle shaft; the adjacent guide rings are communicated and fixed through 2 pipelines 8; the guide ring closest to the central shaft is provided with a circulating liquid inlet, two bottom surfaces of the guide ring are provided with holes, and the hole opening rate is 1-30%. Comprises 5 groups of circulating components, wherein the circulating components comprise a booster pump 3, a tower inlet circulating pipeline 4 and a tower outlet circulating pipeline 5.
As shown in fig. 3, one embodiment of the present invention provides a purification system including a pretreatment apparatus including a dissolution tank 10 and a centrifuge 11, an impurity removal apparatus being an activated carbon adsorption tower 12, a crystallization apparatus being a crystallization tank 13, a leaching apparatus being a leaching tower 1, a crystallization apparatus, a leaching apparatus, and a drying apparatus 14.
The crude product containing the ester compound enters a dissolving tank 10, a solvent is added into the dissolving tank to be dissolved to form a mixed solution, then the mixed solution enters a centrifuge 11, a solution obtained after insoluble substances are removed through centrifugal separation in the centrifuge 11 enters a crystallization tank 13, the temperature is reduced and crystallization is carried out to obtain crystals I, the crystals I enter a leaching tower 1 from the top of the leaching tower, a leaching agent enters the leaching tower 1 from the bottom, crystals II obtained after leaching enter a drying unit 14, and the refined ester compound is obtained through drying.
The following examples were conducted using the same crude 2,6-NDC starting material, and the crude 2,6-NDC starting material was quantitatively analyzed by liquid chromatography to obtain the starting material composition shown in Table 1. The dimensions of the main devices of the invention are as follows: a dissolving tank: 5L; an activated carbon adsorption tower: the diameter is 0.1m, the height is 1m, and granular activated carbon is filled inside; cooling the crystallizing tank: 5L; leaching tower: diameter 0.1m, height 1 m. The diversion component of the leaching tower has three structures: the tower comprises a flow guide member 1(4 flow guide rings, the opening rate of the bottom surface is 10%, the height of each flow guide ring is 1/5 of the tower diameter, the included angle alpha between the bottom surface and the side surface of each flow guide ring is 30 degrees), a flow guide member 2(4 flow guide rings, the opening rate of the bottom surface is 30%, the height of each flow guide ring is 1/5 of the tower diameter, the included angle alpha between the bottom surface and the side surface of each flow guide ring is 60 degrees), a flow guide member 3(2 flow guide rings, the opening rate of the bottom surface is 5%, the height of each flow guide ring is 1/3 of the tower diameter, the included angle alpha between the bottom surface and the side surface of each flow guide ring is 70 degrees), a flow guide member 4(4 flow guide rings, the opening rate of the bottom surface is 10%, the height of each flow guide ring is 1/5 of the tower diameter, the included angle alpha between the bottom surface and the side surface of each flow guide ring is 45 degrees, a flow guide member 5(2 flow guide rings, the opening rate of the bottom surface is 10%, the height of each flow guide ring is 1/5 of the tower diameter, and the included angle alpha between the bottom surface and the side surface of each flow guide ring is 30 degrees.
TABLE 1 crude 2,6-NDA feed composition
Example 1
Continuously adding the crude 2,6-NDC and m-xylene into a dissolving tank, wherein the temperature of the dissolving tank is 130 ℃, the retention time of the dissolving tank is 0.5h to ensure that the 2,6-NDC is fully dissolved, so as to obtain a mixed solution with the mass fraction of 30 wt%, the mixed solution discharged from the dissolving tank enters a centrifuge for centrifugal separation, solid insoluble substances are removed, the obtained liquid phase solution enters an activated carbon adsorption tower, the retention time of the adsorption tower is 1.5h, and the operating temperature of the adsorption tower is 135 ℃. The solution obtained by the adsorption tower enters a crystallizing tank, the temperature is reduced to 20 ℃ of the end point temperature at the cooling rate of 10 ℃/min, solid-liquid separation is carried out, and the solid as a crystal I enters a leaching tower. The leaching solvent in the leaching tower is methanol, liquid-solid two phases are fed from the top of the tower in the flowing mode in the tower, a flow guide component in the leaching tower is a flow guide component 1, 1/10 methanol with the feeding flow is led out from the flow guide component, the flow guide components are arranged at intervals of 1/6 tower heights in the whole leaching tower, the mass ratio of liquid-solid feeding in the leaching tower is 2:1, the temperature in the leaching tower is 20 ℃, the residence time in the whole leaching tower is 5 hours, crystals II discharged from the bottom of the tower are dried and then analyzed, and the obtained product results are shown in table 2.
TABLE 2 product quality index
Example 2
Continuously adding the crude 2,6-NDC and m-xylene into a dissolving tank, wherein the temperature of the dissolving tank is 130 ℃, the retention time of the dissolving tank is 0.5h to ensure that the 2,6-NDC is fully dissolved, so as to obtain a mixed solution with the mass fraction of 30 wt%, the mixed solution discharged from the dissolving tank enters a centrifuge for centrifugal separation, solid insoluble substances are removed, the obtained liquid phase solution enters an activated carbon adsorption tower, the retention time of the adsorption tower is 0.5h, and the operating temperature of the adsorption tower is 135 ℃. The solution obtained by the adsorption tower enters a crystallization tank, the temperature is reduced to 80 ℃ of the end point temperature at the cooling rate of 1 ℃/min, solid-liquid separation is carried out, and the solid serving as a crystal I enters a leaching single tower. The leaching solvent in the leaching tower is methanol, the flow mode in the tower is liquid-solid two-phase countercurrent contact (namely the feed inlet of the leaching tower is positioned at the bottom), wherein the solid is fed into the tower top, the flow guide component in the leaching tower is flow guide component 2, the methanol with the feed flow of 1/5 is led out from the flow guide component, the flow guide components are arranged at the position of every 1/6 tower heights in the whole leaching tower, the liquid-solid feed ratio of the leaching tower is 5:1, the temperature in the leaching tower is 60 ℃, the residence time of the whole leaching tower is 3 hours, the solid discharged from the tower bottom is dried and then analyzed, and the obtained product results are shown in table 3.
TABLE 3 product quality index
Example 3
Continuously adding the crude 2,6-NDC and formic acid into a dissolving tank, wherein the temperature of the dissolving tank is 130 ℃, the residence time of the dissolving tank is 1h to ensure the 2,6-NDC is fully dissolved, so as to obtain a mixed solution with the mass fraction of 30 wt%, the mixed solution discharged from the dissolving tank enters a centrifugal machine for centrifugal separation, solid insoluble substances are removed, the obtained liquid phase solution enters an activated carbon adsorption tower, the residence time of the adsorption tower is 3h, and the operating temperature of the adsorption tower is 130 ℃. The solution obtained by the adsorption tower enters a crystallizing tank, the temperature is reduced to the end point temperature of 60 ℃ at the cooling rate of 0.1 ℃/min, solid-liquid separation is carried out, and the solid serving as a crystal I enters a leaching tower. The extraction solvent in the extraction tower is ethanol, the flow mode in the tower is liquid-solid two-phase countercurrent contact, wherein the top of the tower is filled with solid, the diversion component in the extraction tower is a diversion component 3, the position of the diversion component is led out to 1/5 feed flow rate of ethanol, the diversion component is arranged at the position of every 1/6 tower heights in the whole extraction tower, the liquid-solid feed ratio of the extraction tower is 3:1, the temperature in the extraction tower is 80 ℃, the residence time of the whole extraction tower is 0.5h, the solid discharged from the bottom of the tower is dried and then analyzed, and the obtained product results are shown in table 4.
TABLE 4 product quality index
Example 4
Continuously adding the crude 2,6-NDC and m-xylene into a dissolving tank, wherein the temperature of the dissolving tank is 130 ℃, the retention time of the dissolving tank is 0.5h to ensure that the 2,6-NDC is fully dissolved, so as to obtain a mixed solution with the mass fraction of 30 wt%, the mixed solution discharged from the dissolving tank enters a centrifuge for centrifugal separation, solid insoluble substances are removed, the obtained liquid phase solution enters an activated carbon adsorption tower, the retention time of the adsorption tower is 1.5h, and the operating temperature of the adsorption tower is 135 ℃. The solution obtained by the adsorption tower enters a crystallizing tank, the temperature is reduced to 20 ℃ of the end point temperature at the cooling rate of 10 ℃/min, solid-liquid separation is carried out, and the solid as a crystal I enters a leaching tower. The leaching solvent in the leaching tower is methanol, the flow mode in the tower is liquid-solid two-phase countercurrent contact, wherein solid enters the tower top, a flow guide component in the leaching tower is a flow guide component 1, methanol with 1/10 feeding flow is led out from the flow guide component, the flow guide component is arranged at the position of every 1/3 tower heights in the whole leaching tower, the mass ratio of liquid to solid feeding in the leaching tower is 2:1, the temperature in the leaching tower is 20 ℃, the residence time in the whole leaching tower is 5 hours, crystals II discharged from the tower bottom are dried and then analyzed, and the obtained product results are shown in table 5.
TABLE 5 product quality index
Example 5
Continuously adding the crude 2,6-NDC and m-xylene into a dissolving tank, wherein the temperature of the dissolving tank is 130 ℃, the retention time of the dissolving tank is 0.5h to ensure that the 2,6-NDC is fully dissolved, so as to obtain a mixed solution with the mass fraction of 30 wt%, the mixed solution discharged from the dissolving tank enters a centrifuge for centrifugal separation, solid insoluble substances are removed, the obtained liquid phase solution enters an activated carbon adsorption tower, the retention time of the adsorption tower is 1.5h, and the operating temperature of the adsorption tower is 135 ℃. The solution obtained by the adsorption tower enters a crystallizing tank, the temperature is reduced to 20 ℃ of the end point temperature at the cooling rate of 10 ℃/min, solid-liquid separation is carried out, and the solid as a crystal I enters a leaching tower. The leaching solvent in the leaching tower is methanol, the flow mode in the tower is liquid-solid two-phase countercurrent contact, wherein solid enters the tower top, the flow guide component in the leaching tower is a flow guide component 4, 1/10 methanol with the feeding flow is led out from the flow guide component, the flow guide components are arranged at the position of every 1/6 tower heights in the whole leaching tower, the mass ratio of liquid to solid feeding in the leaching tower is 2:1, the temperature in the leaching tower is 20 ℃, the residence time in the whole leaching tower is 5 hours, crystals II discharged from the tower bottom are dried and then analyzed, and the obtained product results are shown in table 6.
TABLE 6 product quality index
Example 6
Continuously adding the crude 2,6-NDC and m-xylene into a dissolving tank, wherein the temperature of the dissolving tank is 130 ℃, the retention time of the dissolving tank is 0.5h to ensure that the 2,6-NDC is fully dissolved, so as to obtain a mixed solution with the mass fraction of 30 wt%, the mixed solution discharged from the dissolving tank enters a centrifuge for centrifugal separation, solid insoluble substances are removed, the obtained liquid phase solution enters an activated carbon adsorption tower, the retention time of the adsorption tower is 1.5h, and the operating temperature of the adsorption tower is 135 ℃. The solution obtained by the adsorption tower enters a crystallizing tank, the temperature is reduced to 20 ℃ of the end point temperature at the cooling rate of 10 ℃/min, solid-liquid separation is carried out, and the solid as a crystal I enters a leaching tower. The leaching solvent in the leaching tower is methanol, the flow mode in the tower is liquid-solid two-phase countercurrent contact, wherein solid enters the tower top, a flow guide component in the leaching tower is a flow guide component 5, 1/10 methanol with the feeding flow is led out from the flow guide component, the flow guide component is arranged at the position of every 1/6 tower heights in the whole leaching tower, the mass ratio of liquid to solid feeding in the leaching tower is 2:1, the temperature in the leaching tower is 20 ℃, the residence time in the whole leaching tower is 5 hours, crystals II discharged from the tower bottom are dried and then analyzed, and the obtained product results are shown in table 7.
TABLE 7 product quality index
Example 7
Continuously adding the crude 2,6-NDC and methanol into a dissolving tank, wherein the temperature of the dissolving tank is 130 ℃, the retention time of the dissolving tank is 0.5h to ensure the 2,6-NDC to be fully dissolved, so as to obtain a mixed solution with the mass fraction of 30 wt%, the mixed solution discharged from the dissolving tank enters a centrifuge for centrifugal separation, solid insoluble substances are removed, the obtained liquid phase solution enters an activated carbon adsorption tower, the retention time of the adsorption tower is 1.5h, and the operating temperature of the adsorption tower is 135 ℃. The solution obtained by the adsorption tower enters a crystallizing tank, the temperature is reduced to 20 ℃ of the end point temperature at the cooling rate of 10 ℃/min, solid-liquid separation is carried out, and the solid as a crystal I enters a leaching tower. The leaching solvent in the leaching tower is methanol, the flow mode in the tower is liquid-solid two-phase countercurrent contact, wherein solid enters the tower top, a flow guide component in the leaching tower is a flow guide component 5, 1/10 methanol with the feeding flow is led out from the flow guide component, the flow guide component is arranged at the position of every 1/6 tower heights in the whole leaching tower, the mass ratio of liquid to solid feeding in the leaching tower is 2:1, the temperature in the leaching tower is 20 ℃, the residence time in the whole leaching tower is 5 hours, crystals II discharged from the tower bottom are dried and then analyzed, and the obtained product results are shown in table 8.
TABLE 8 product quality index
Example 8
Continuously adding the crude 2,6-NDC and m-xylene into a dissolving tank, wherein the temperature of the dissolving tank is 130 ℃, the retention time of the dissolving tank is 0.5h to ensure that the 2,6-NDC is fully dissolved, so as to obtain a mixed solution with the mass fraction of 30 wt%, the mixed solution discharged from the dissolving tank enters a centrifuge for centrifugal separation, solid insoluble substances are removed, the obtained liquid phase solution enters an activated carbon adsorption tower, the retention time of the adsorption tower is 1.5h, and the operating temperature of the adsorption tower is 135 ℃. The solution obtained by the adsorption tower enters a crystallizing tank, the temperature is reduced to 50 ℃ of the end point temperature at the cooling rate of 1 ℃/min, solid-liquid separation is carried out, and the solid serving as crystal I enters a leaching tower. The leaching solvent in the leaching tower is methanol, the flow mode in the tower is liquid-solid two-phase countercurrent contact, wherein solid enters the tower top, a flow guide component in the leaching tower is a flow guide component 5, 1/10 methanol with the feeding flow is led out from the flow guide component, the flow guide component is arranged at the position of every 1/6 tower heights in the whole leaching tower, the mass ratio of liquid to solid feeding in the leaching tower is 2:1, the temperature in the leaching tower is 20 ℃, the residence time in the whole leaching tower is 5 hours, crystals II discharged from the tower bottom are dried and then analyzed, and the obtained product results are shown in table 9.
TABLE 9 product quality index
Example 9
Continuously adding the crude 2,6-NDC and m-xylene into a dissolving tank, wherein the temperature of the dissolving tank is 130 ℃, the retention time of the dissolving tank is 0.5h to ensure that the 2,6-NDC is fully dissolved, so as to obtain a mixed solution with the mass fraction of 30 wt%, the mixed solution discharged from the dissolving tank enters a centrifuge for centrifugal separation, solid insoluble substances are removed, the obtained liquid phase solution enters an activated carbon adsorption tower, the retention time of the adsorption tower is 1.5h, and the operating temperature of the adsorption tower is 135 ℃. The solution obtained by the adsorption tower enters a crystallizing tank, the temperature is reduced to 20 ℃ of the end point temperature at the cooling rate of 10 ℃/min, solid-liquid separation is carried out, and the solid as a crystal I enters a leaching tower. The extraction solvent in the extraction tower is ethanol, the flow mode in the tower is liquid-solid two-phase countercurrent contact, wherein solid enters the tower top, the diversion component in the extraction tower is diversion component 5, 1/10 methanol with feed flow is led out from the diversion component, the diversion component is arranged at the position of every 1/6 tower heights in the whole extraction tower, the mass ratio of liquid to solid feeding in the extraction tower is 2:1, the temperature in the extraction tower is 20 ℃, the residence time in the whole extraction tower is 5h, crystals II discharged from the tower bottom are dried and then analyzed, and the obtained product results are shown in table 10.
TABLE 10 product quality index
Example 10
Continuously adding the crude 2,6-NDC and m-xylene into a dissolving tank, wherein the temperature of the dissolving tank is 130 ℃, the retention time of the dissolving tank is 0.5h to ensure that the 2,6-NDC is fully dissolved, so as to obtain a mixed solution with the mass fraction of 30 wt%, the mixed solution discharged from the dissolving tank enters a centrifuge for centrifugal separation, solid insoluble substances are removed, the obtained liquid phase solution enters an activated carbon adsorption tower, the retention time of the adsorption tower is 1.5h, and the operating temperature of the adsorption tower is 135 ℃. The solution obtained by the adsorption tower enters a crystallizing tank, the temperature is reduced to 20 ℃ of the end point temperature at the cooling rate of 10 ℃/min, solid-liquid separation is carried out, and the solid as a crystal I enters a leaching tower. The leaching solvent in the leaching tower is methanol, the flow mode in the tower is that liquid-solid two phases are fed from the top of the tower (namely the feed inlet of the leaching tower is positioned at the top), the flow guide component in the leaching tower is flow guide component 5, 1/10 methanol with the feed flow is led out from the flow guide component, the flow guide component is arranged at the position of every 1/6 tower heights in the whole leaching tower, the mass ratio of the liquid to the solid in the leaching tower is 2:1, the temperature in the leaching tower is 20 ℃, the residence time in the whole leaching tower is 5 hours, crystals II discharged from the bottom of the tower are dried and then analyzed, and the obtained product results are shown in Table 11.
TABLE 11 product quality index
Example 11
Continuously adding the crude 2,6-NDC and m-xylene into a dissolving tank, wherein the temperature of the dissolving tank is 130 ℃, the retention time of the dissolving tank is 0.5h to ensure that the 2,6-NDC is fully dissolved, so as to obtain a mixed solution with the mass fraction of 30 wt%, the mixed solution discharged from the dissolving tank enters a centrifuge for centrifugal separation, solid insoluble substances are removed, the obtained liquid phase solution enters an activated carbon adsorption tower, the retention time of the adsorption tower is 1.5h, and the operating temperature of the adsorption tower is 135 ℃. The solution obtained by the adsorption tower enters a crystallizing tank, the temperature is reduced to 20 ℃ of the end point temperature at the cooling rate of 10 ℃/min, solid-liquid separation is carried out, and the solid as a crystal I enters a leaching tower. The leaching solvent in the leaching tower is methanol, the flow mode in the tower is liquid-solid two-phase countercurrent contact, wherein solid enters the tower top, a flow guide component in the leaching tower is a flow guide component 5, 1/10 methanol with the feeding flow is led out from the flow guide component, the flow guide component is arranged at the position of every 1/6 tower heights in the whole leaching tower, the mass ratio of liquid to solid feeding in the leaching tower is 5:1, the temperature in the leaching tower is 20 ℃, the residence time in the whole leaching tower is 5h, crystals II discharged from the tower bottom are dried and then analyzed, and the obtained product results are shown in table 12.
TABLE 12 product quality index
Any numerical value mentioned in this specification, if there is only a two unit interval between any lowest value and any highest value, includes all values from the lowest value to the highest value incremented by one unit at a time. For example, if it is stated that the amount of a component, or a value of a process variable such as temperature, pressure, time, etc., is 50 to 90, it is meant in this specification that values of 51 to 89, 52 to 88 … …, and 69 to 71, and 70 to 71, etc., are specifically enumerated. For non-integer values, units of 0.1, 0.01, 0.001, or 0.0001 may be considered as appropriate. These are only some specifically named examples. In a similar manner, all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be disclosed in this application.
It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.
Claims (10)
1. The leaching tower is internally provided with at least one group of flow guide members which are fixed on a central shaft at the axis of the leaching tower; each group of flow guide members comprises at least two flow guide rings, each flow guide ring is a hollow circular table, and the bottom surface of each circular table is parallel to the central axis; the adjacent guide rings are communicated and fixed through at least one pipeline.
2. The leaching tower according to claim 1, wherein the distance between two adjacent sets of flow guiding elements is between 1/20 and 1/2 tower height; and/or two bottom surfaces of the flow guide ring are provided with holes, and the hole opening rate is 1-30%; and/or a circulating liquid inlet is arranged on the guide ring closest to the central shaft.
3. The leaching column according to claim 1 or 2, further comprising at least one set of circulation members, said circulation members comprising a booster pump, a feed circulation line and a discharge circulation line; preferably, the booster pump is arranged outside the tower; preferably, one end of the tower inlet circulating pipeline is connected with an outlet of the booster pump, and the other end of the tower inlet circulating pipeline is connected with a circulating liquid inlet on the guide ring; one end of the tower outlet circulation pipeline is connected with an inlet of the booster pump, and a port at the other end is arranged at the center of the flow guide component.
4. The leaching tower according to any one of claims 1 to 3, wherein the leaching tower is provided with a feed inlet, a discharge outlet and a leaching agent inlet; preferably the feed inlet is located at the top of the leach tower; preferably the discharge port is located at the bottom of the leaching tower; preferably the lixiviant inlet is located at the bottom of the leaching tower.
5. A purification system comprising the leaching column of any one of claims 1-4.
6. The purification system of claim 5, comprising:
the pretreatment device is used for pretreating the crude product to be purified and removing insoluble substances in the crude product;
optionally, an impurity removing device for receiving the product from the pretreatment device and removing impurities from the product to remove colored impurities in the product;
the crystallization device is used for receiving the product from the pretreatment device and/or the product from the impurity removal device and carrying out crystallization treatment on the product to obtain a crystal I;
the leaching device is used for receiving the crystal I from the crystallization device and leaching the crystal I to obtain a crystal II; preferably the leaching unit is a leaching tower according to any one of claims 1 to 4;
optionally a post-treatment unit for receiving and post-treating the crystals II from the leaching unit.
7. Use of the leaching column according to any one of claims 1 to 4 or the system according to claim 5 or 6 for purifying ester compounds;
preferably, the ester compound has the general formula: a- (R1-COO-R2)2，
Wherein A is C6-C20 aryl, preferably C6-C12 aryl, and more preferably benzene ring or naphthalene ring; r1 is a bond or alkylene of C1-C6, preferably a bond, methylene, ethylene, propylene or butylene; r2 is C1-C6 alkyl, preferably methyl, ethyl, propyl or butyl.
8. A method for purifying an ester compound, comprising the steps of:
(1) pretreating a crude product containing the ester compound to remove insoluble substances in the crude product;
(2) optionally, removing impurities from the pretreated product;
(3) crystallizing the pretreated product and/or the impurity-removed product to obtain a crystal I;
(4) leaching the crystal I to obtain a crystal II;
(5) optionally, post-treating the crystals II;
preferably, the ester compound has the general formula: a- (R1-COO-R2)2，
Wherein A is C6-C20 aryl, preferably C6-C12 aryl, and more preferably benzene ring or naphthalene ring; r1 is a bond or alkylene of C1-C6, preferably a bond, methylene, ethylene, propylene or butylene; r2 is C1-C6 alkyl, preferably methyl, ethyl, propyl or butyl.
9. The method according to claim 8, wherein the leaching agent used in the leaching process comprises one or more of an alcohol and an acid compound, preferably comprises one or more of a fatty alcohol, a cycloaliphatic alcohol and a fatty acid, more preferably a fatty alcohol of C1-C6; and/or the temperature of the leaching treatment is 0-100 ℃, preferably 20-80 ℃; and/or the leaching treatment time is not less than 0.5h, preferably 0.5-5 h; and/or, the leaching treatment is carried out using a leaching tower according to any one of claims 1 to 4.
10. A method for purifying ester compounds using the system of claim 5 or 6, comprising the steps of:
(a) pretreating the crude product containing the ester compound in a pretreatment device to remove insoluble substances in the crude product;
(b) optionally, the product from the pretreatment device enters an impurity removal device and is subjected to impurity removal treatment in the impurity removal device;
(c) enabling the product from the pretreatment device and/or the product from the impurity removal device to enter a crystallization device and carrying out crystallization treatment in the crystallization device to obtain a crystal I;
(d) the crystal I enters a leaching device and is leached in the leaching device to obtain a crystal II;
(e) optionally, passing the crystals II to a post-treatment apparatus and post-treating therein;
preferably, the ester compound has the general formula: a- (R1-COO-R2)2，
Wherein A is C6-C20 aryl, preferably C6-C12 aryl, and more preferably benzene ring or naphthalene ring; r1 is a bond or alkylene of C1-C6, preferably a bond, methylene, ethylene, propylene or butylene; r2 is C1-C6 alkyl, preferably methyl, ethyl, propyl or butyl.
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