Method for producing an easily polymerizable compound

Abstract

This invention provides a method for efficiently obtaining high-quality products. The invention relates to a method for manufacturing a polymerizable compound using a purification apparatus comprising: a crystallization tank and / or a ripening tank, the crystallization tank generating crystals of the polymerizable compound from a mother liquor containing a solution of the polymerizable compound or a slurry containing crystals of the polymerizable compound, the ripening tank causing the crystals of the polymerizable compound to grow; and a washing column. The purification apparatus is characterized by further comprising a pipeline connected to at least one selected from the group consisting of a crystallization tank, a ripening tank, and a washing column, and having a bend where the ratio of the radius of curvature R to the inner diameter D of the pipeline R / D exceeds 4 and is less than 10. The manufacturing method includes a step of feeding a slurry containing crystals of the polymerizable compound using the pipeline.

Description

Technical Field

[0001] This invention relates to a method for manufacturing easily polymerizable compounds. More specifically, it relates to a method for manufacturing easily polymerizable compounds, a method for purifying easily polymerizable compounds, and an apparatus for purifying easily polymerizable compounds. Background Technology

[0002] For example, purification equipment is widely used in industry to purify compounds used as raw materials for resins, etc. In most areas of the chemical industry, there is a pursuit of high-quality compounds with further reduced impurities, leading to various studies on more advanced purification equipment for this purpose.

[0003] In industrial applications, crude compounds are mostly purified through continuous purification processes. In these processes, piping connects devices to form pipelines (hereinafter, "pipeline" refers to connected piping or piping connections) that allow for inter-device transport of the purified liquid. For example, a method for manufacturing acrylic acid, a readily polymerizable compound, discloses the following: a feed gas is subjected to a contact gas-phase oxidation reaction; the collected acrylic acid solution is supplied via a pipeline to a crystallization apparatus for purification; the remaining mother liquor is supplied via a pipeline to a reactive distillation apparatus; and, after the Michael addition product of acrylic acid has been decomposed, the mother liquor is returned via a pipeline to a collection process (see, for example, Patent Document 1).

[0004] Furthermore, regarding the conveying of slurries containing solids, the following is disclosed: when recycling catalysts such as ion exchange resins used in the manufacture of unsaturated carboxylic acid esters, the shape of the piping used for conveying slurries containing resin (catalyst) as solids, the resin concentration of the slurry, and the flow rate are specified, thereby preventing slurry retention in the piping and resin breakage (see, for example, Patent Document 2).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2007-182437

[0008] Patent Document 2: Japanese Patent Application Publication No. 2002-338520 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] As described above, there is a need for a superior method for manufacturing easily polymerizable compounds, and a desire for a method that efficiently yields high-quality products (easily polymerizable compounds). This invention was made in view of the above-mentioned situation, and its object is to provide a method for efficiently obtaining high-quality products.

[0011] Solution for solving the problem

[0012] The inventors have researched methods for efficiently obtaining high-quality products, focusing on continuous purification apparatus capable of efficient purification. Various studies have been conducted on purification apparatuses comprising: a crystallization tank and / or a ripening tank, wherein the crystallization tank generates crystals of the polymerizable compound from a mother liquor containing a solution or a slurry containing crystals of the polymerizable compound, and the ripening tank allows the crystals of the polymerizable compound to grow; and a washing column. Furthermore, a problem was discovered that when producing the polymerizable compound in such a purification apparatus, if the slurry containing crystals is fed through a pipeline, the impurity concentration in the product increases depending on the conditions of that pipeline. Here, the inventors conducted in-depth research and discovered the following, thus achieving the present invention: by providing a method for manufacturing easily polymerizable compounds using the above-described purification apparatus, high-quality products can be obtained, and the blockage of pipelines by crystals can be effectively prevented, thus solving the aforementioned problems. The purification apparatus further includes a pipeline connected to at least one selected from the group consisting of a crystallization tank, a ripening tank, and a cleaning column, and has a bend where the ratio of the radius of curvature R to the inner diameter D of the pipeline, R / D, is greater than 4 and less than 10. The manufacturing method includes a step of feeding a slurry containing crystals of easily polymerizable compounds using the pipeline.

[0013] Furthermore, the higher quality products obtained by the above manufacturing method are believed to be due to the fact that the bends in the pipeline are relatively gentle, which can effectively prevent the growth of misaligned crystals and crystal breakage within the pipeline, thus preventing the expansion of the crystal grain size distribution. This allows for the formation of a crystal bed with a roughly uniform crystal shape in the cleaning column, thereby improving the cleaning performance.

[0014] That is, the present invention is a method for manufacturing a polymerizable compound, which uses a purification apparatus comprising: a crystallization tank and / or a ripening tank, wherein the crystallization tank generates crystals of the polymerizable compound from a mother liquor containing a solution of the polymerizable compound or a slurry containing crystals of the polymerizable compound, and the ripening tank allows the crystals of the polymerizable compound to grow; and a washing column, characterized in that the purification apparatus further comprises a pipeline connected to at least one selected from the group consisting of a crystallization tank, a ripening tank and a washing column, and having a bend in which the ratio of the radius of curvature R to the inner diameter D of the pipeline R / D is greater than 4 and less than 10, the manufacturing method comprising a step of feeding a slurry containing crystals of the polymerizable compound using the pipeline.

[0015] Furthermore, although Patent Document 2 discloses information about slurry transport, it only discloses information about transporting slurries in which the solid component is a resin (catalyst), and does not disclose any information about transporting slurries containing crystals of easily polymerizable compounds, nor does it disclose any information about obtaining a high-quality target product.

[0016] The effects of the invention

[0017] By using the manufacturing method of the present invention, high-quality products can be obtained efficiently. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating an example of a bend in the pipeline used in the manufacturing method of the present invention.

[0019] Figure 2 This is a schematic diagram illustrating an example of a pipeline in the purification apparatus of the present invention that can be applied according to the present invention.

[0020] Figure 3 This is a schematic diagram illustrating another example of a pipeline in the purification apparatus of the present invention that can be applied according to the present invention.

[0021] Figure 4 This is a schematic diagram illustrating another example of a pipeline in the purification apparatus of the present invention that can be applied according to the present invention.

[0022] Figure 5 This is a schematic diagram illustrating another example of a pipeline in the purification apparatus of the present invention that can be applied according to the present invention.

[0023] Figure 6 This is a schematic diagram illustrating another example of a pipeline in the purification apparatus of the present invention that can be applied according to the present invention.

[0024] Figure 7 This is a schematic diagram illustrating another example of a pipeline in the purification apparatus of the present invention that can be applied according to the present invention.

[0025] Figure 8 This is a schematic diagram illustrating another example of a pipeline in the purification apparatus of the present invention that can be applied according to the present invention. Detailed Implementation

[0026] The present invention will now be described in detail.

[0027] Furthermore, a configuration in which two or more of the preferred features of the present invention described below are combined is also a preferred configuration of the present invention.

[0028] Hereinafter, firstly, the method for manufacturing the polymerizable compound of the present invention will be described. Next, the purification method for the polymerizable compound of the present invention and the purification apparatus of the present invention will be described in sequence.

[0029] (Method for manufacturing the polymerizable compound of the present invention)

[0030] The present invention discloses a method for manufacturing a polymerizable compound, which uses a purification apparatus comprising: a crystallization tank and / or a ripening tank, wherein the crystallization tank generates crystals of the polymerizable compound from a mother liquor containing a solution of the polymerizable compound or a slurry containing crystals of the polymerizable compound, and the ripening tank allows the crystals of the polymerizable compound to grow; and a washing column. The purification apparatus is characterized by further comprising a pipeline connected to at least one selected from the group consisting of a crystallization tank, a ripening tank, and a washing column, and having a bend in which the ratio of the radius of curvature R to the inner diameter D of the pipeline R / D exceeds 4 and is less than 10. The manufacturing method includes a step of feeding the slurry containing crystals of the polymerizable compound using the pipeline.

[0031] Below, we will first explain the above-mentioned liquid delivery process, and then explain the other processes in turn. Furthermore, in continuous purification processes, each process typically occurs simultaneously when viewed as a whole as a purification unit.

[0032] In this specification, "easily polymerizable compound" refers to an easily polymerizable compound obtained using the manufacturing method of the present invention, and does not refer to the raw materials, by-products, or solvents used in the manufacturing method of the present invention. "Easily polymerizable compound" can be replaced with "target compound" or "target product." In this specification, "impurity" refers to components other than "easily polymerizable compound," such as raw materials, by-products, and solvents.

[0033] Furthermore, in this specification, the generation of crystals of easily polymerizable compounds from the mother liquor of a slurry containing a solution of easily polymerizable compounds or crystals of easily polymerizable compounds not only refers to the generation of crystals of easily polymerizable compounds from a solution containing easily polymerizable compounds, but also refers to the generation of newly formed crystals of easily polymerizable compounds from the mother liquor of a slurry containing crystals of easily polymerizable compounds, and an increase in the crystal concentration in the slurry after it is taken out of the crystallization tank compared to before it was supplied to the crystallization tank.

[0034] For example, in the method for manufacturing the polymerizable compound of the present invention, the method for purifying the polymerizable compound of the present invention, and the purification apparatus of the present invention, in addition to the case of supplying a solution containing the polymerizable compound to a crystallization tank to obtain a slurry containing crystals of the polymerizable compound, there is also a case of supplying a slurry containing crystals of the polymerizable compound to a crystallization tank to obtain a slurry with a higher crystal concentration. Furthermore, the slurry containing crystals of the polymerizable compound supplied to the crystallization tank usually also contains the polymerizable compound in its mother liquor.

[0035] In addition, when crystals are removed from the crystallization tank of the present invention, they are usually removed as a slurry containing crystals of easily polymerizable compounds.

[0036] <Process of feeding slurry containing crystals of easily polymerizable compounds>

[0037] In the above-described liquid delivery step of the manufacturing method of the present invention, a slurry containing crystals of easily polymerizable compounds is delivered using the pipeline of the purification apparatus. The pipeline is connected to at least one selected from the group consisting of a crystallization tank, a ripening tank, and a cleaning column, and has a bend in which the ratio of the radius of curvature R to the inner diameter D of the pipeline R / D exceeds 4 and is less than 10.

[0038] The aforementioned radius of curvature R is the reciprocal of the curvature at the bend in the pipeline, such as... Figure 1 As shown, this is equivalent to the radius of the circle corresponding to the arc when the centerline of the bend in the pipeline is set as an arc. The larger the radius of curvature R, the gentler the bend.

[0039] By setting the ratio of the radius of curvature R to the inner diameter D of the pipeline, R / D, to a value exceeding 4, high-quality polymerizable compounds can be obtained. This is believed to be because the gentler curvature of the bend effectively prevents crystal growth deviation and crystal breakage within the pipeline, thus preventing an expansion of the crystal grain size distribution and enabling the formation of a crystal bed with a generally uniform crystal shape in the cleaning column. Furthermore, it effectively prevents the pipeline from becoming clogged by crystals.

[0040] The ratio of the radius of curvature R to the inner diameter D of the pipeline, R / D, is preferably 4.5 or more, and more preferably 5 or more.

[0041] Furthermore, in the manufacturing method of the present invention, the ratio of the radius of curvature R to the inner diameter D of the pipeline, R / D, is 10 or less. Therefore, the size of the purification apparatus is not excessive, and the pipeline can be appropriately arranged. From the viewpoint of the size of the purification apparatus, the ratio of the radius of curvature R to the inner diameter D of the pipeline, R / D, is preferably 9 or less, and more preferably 8 or less.

[0042] Furthermore, the radius of curvature R is not particularly limited, but in industrial-scale purification devices, it is preferably 50 mm to 5000 mm, and more preferably 100 mm to 2500 mm.

[0043] In industrial-scale purification devices, the inner diameter D of the aforementioned pipeline is preferably 10 mm to 500 mm, and more preferably 20 mm to 250 mm.

[0044] The aforementioned bend is not particularly limited, but the angle formed by the bend (the angle formed by the pipes extending before and after the bend) is preferably 75° to 165°, more preferably 90° to 150°.

[0045] The aforementioned pipeline is connected to at least one selected from the group consisting of a crystallization tank, a ripening tank, and a cleaning column.

[0046] Examples of such pipelines include pipelines connecting crystallization tanks, pipelines connecting crystallization tanks and ripening tanks, pipelines connecting crystallization tanks and cleaning columns or ripening tanks and cleaning columns, and pipelines connecting cleaning columns and melting equipment in the melting loop described later. One or more of these pipelines may be used. The pipeline connecting crystallization tanks may connect the slurry extraction port and the slurry supply port in a particular crystallization tank, or, in the case of multiple tanks (crystallization tanks) connected in series, the pipeline connecting a downstream tank and an upstream tank. Furthermore, other devices may be installed along these pipelines; for example, an external cooling mechanism or a solid-liquid separation device for crystallization may be installed along the pipeline connecting the slurry extraction port and the slurry supply port.

[0047] The aforementioned pipelines are preferably pipelines connecting crystallization tanks, pipelines connecting crystallization tanks and ripening tanks, and pipelines connecting crystallization tanks and cleaning columns or connecting ripening tanks and cleaning columns.

[0048] In particular, in the manufacturing method of the present invention, it is more preferable that the above-mentioned pipeline is a pipeline connecting the crystallization tank and the cleaning column or connecting the ripening tank and the cleaning column, and the above-mentioned liquid delivery process is to use the pipeline to deliver the slurry containing crystals of easily polymerizable compounds from the crystallization tank or the ripening tank to the cleaning column.

[0049] By making the R / D ratio at the bend of the above-mentioned pipeline within the range of the R / D of the present invention, a crystal bed with a more uniform crystal shape can be formed in the cleaning column, and a higher quality product can be obtained.

[0050] As a crystallization tank or ripening tank connected to a pipeline, for example, in the case where the purification apparatus of the present invention comprises multiple tanks connected in series, the last of these tanks (crystallization tank or ripening tank) can be used.

[0051] The pipelines mentioned above are not particularly limited in terms of their material, but are preferably made of metals or alloys such as stainless steel.

[0052] In the manufacturing method of the present invention, it is preferable that, in the above-mentioned liquid delivery process, the linear velocity of the slurry is 1.5 m / s or more and 4.0 m / s or less.

[0053] By setting the linear velocity of the slurry to 1.5 m / s or higher, when the slurry is delivered using the pipeline with the bend of the present invention, it is possible to further prevent the growth of misaligned crystals. Furthermore, it is possible to further prevent pipeline blockage caused by crystals.

[0054] The linear velocity of the slurry is more preferably 1.8 m / s or more, and even more preferably 2.0 m / s or more.

[0055] By setting the linear velocity of the slurry to 4.0 m / s or less, the breakage of crystals contained in the slurry can be further prevented when the slurry is fed using the pipeline with the bend of the present invention. The linear velocity of the slurry is more preferably 3.5 m / s or less, and even more preferably 3.0 m / s or less.

[0056] That is, by making the linear velocity of the slurry above 1.5 m / s and below 4.0 m / s, it is possible to further prevent the growth of misaligned crystals in the pipeline, as well as the blockage and crystal breakage in the pipeline, and to obtain these significant effects at the same time.

[0057] The linear velocity of the slurry can be calculated as follows: by directly measuring the volumetric flow rate at the straight section using a flow meter, or by measuring the mass flow rate at the straight section using a flow meter and dividing the measured value by the slurry density to calculate the volumetric flow rate, and then dividing the volumetric flow rate by the cross-sectional area of ​​the curved section where the slurry flows.

[0058] In the manufacturing method of the present invention, it is preferable that, in the above-mentioned liquid delivery process, the crystal concentration of the slurry is 1% by mass or more and 40% by mass or less.

[0059] By ensuring the crystal concentration of the slurry is 1% by mass or more, the slurry flow rate is appropriate, avoiding the need for large-scale equipment such as pumps, and enabling efficient product production. More preferably, the crystal concentration of the slurry is 5% by mass or more, and even more preferably 10% by mass or more.

[0060] By setting the crystal concentration of the slurry to 40% by mass or less, the slurry can be made sufficiently fluid when it is delivered using the pipeline with the bend of the present invention, and pipeline blockage can be effectively prevented. The crystal concentration of the slurry is more preferably 38% by mass or less, and even more preferably 35% by mass or less.

[0061] In the manufacturing method of the present invention, it is preferable that the pipeline includes a heating mechanism.

[0062] The heating mechanism mentioned above includes a heat preservation mechanism, which may include jackets, steam tracing pipes, electric heaters, etc. that use heat media such as warm water, cooling water (CW), and brine, and may use one or more of them.

[0063] The heating temperature of the heating mechanism can be appropriately set considering the melting point of the polymerizable compound. For example, in the manufacturing method of the present invention, it is preferable that the pipeline is equipped with a heating mechanism, and the temperature of the slurry is 1°C or higher and 50°C or lower in the liquid delivery process.

[0064] In addition, preferably, the temperature difference between the heating temperature of the heating mechanism and the slurry temperature is 1°C to 40°C.

[0065] By maintaining a temperature difference of 1°C or more, when the slurry is delivered using the pipeline with the bend of the present invention, it is possible to further prevent the growth of misaligned crystals within the pipeline and the blockage of the pipeline due to freezing. More preferably, this temperature difference is 2°C or more, and even more preferably 3°C or more.

[0066] By keeping the temperature difference below 40°C, when the slurry is fed using the pipeline with the bend of the present invention, it is possible to further prevent the partial melting of the crystals in the slurry, which would otherwise lead to an expansion of the particle size distribution. More preferably, this temperature difference is below 30°C, even more preferably below 20°C, and particularly preferably below 10°C.

[0067] The pressure conditions in the pipeline during the above-mentioned liquid delivery process can be under pressurized conditions, atmospheric pressure, or depressurized conditions.

[0068] The above-mentioned liquid delivery process can also be intermittent, but in the manufacturing method of the present invention, it is preferred to be carried out substantially continuously.

[0069] The purification apparatus of the present invention includes a cleaning column that is capable of cleaning crystals, and there are no particular limitations, but a cleaning column that forcibly transports the crystal bed is preferred. Specifically, examples of cleaning columns that forcibly transport the crystal bed include mechanical cleaning columns that use a piston to compact the crystals to form / transport the crystal bed, and hydraulic cleaning columns (water pressure cleaning columns) that use a pump to feed slurry into the column and extract the mother liquor from a filter placed inside the column to form / transport the crystal bed.

[0070] From the perspective of higher production capacity and fewer drive units in the cleaning column, resulting in fewer malfunctions caused by the device, the aforementioned cleaning column is more preferably a hydraulic cleaning column.

[0071] The cleaning column described above may also have a mechanical mechanism for cutting the crystal bed.

[0072] In the manufacturing method of the present invention, it is preferred that the above-mentioned polymerizable compound is a polymerizable compound having reactive double bonds.

[0073] In particular, in the manufacturing method of the present invention, the aforementioned polymerizable compound is more preferably an unsaturated carboxylic acid, further preferably (meth)acrylic acid, and especially preferably acrylic acid. In this specification, (meth)acrylic acid is acrylic acid and / or methacrylic acid.

[0074] Furthermore, the solutions containing readily polymerizable compounds mentioned above are not limited to solutions synthesized in-house, but can also be solutions purchased from elsewhere.

[0075] <Crystallization process>

[0076] The manufacturing method of the present invention may also include a step of crystallizing a solution containing a polymerizable compound or a slurry containing crystals of a polymerizable compound. Using this crystallization step, crystals of the polymerizable compound can be generated from the mother liquor of a solution containing a polymerizable compound or a slurry containing crystals of a polymerizable compound.

[0077] The temperature in the crystallization process described above can be adjusted appropriately according to the type of polymerizable compound being purified, and is generally in the range of -2°C to -15°C relative to the melting point of the pure substance. Furthermore, when the polymerizable compound being purified is (meth)acrylic acid, 0°C to 12°C is preferred. More preferably, 1°C to 11°C, and even more preferably, 2°C to 10°C.

[0078] The temperature in the crystallization process described above refers to the temperature of the mother liquor in the solution containing a polymerizable compound or the slurry containing crystals of a polymerizable compound supplied to the crystallization process.

[0079] The pressure conditions in the above crystallization process can be under pressure, under normal pressure, or under reduced pressure.

[0080] The crystallization process described above is only required to generate crystals of easily polymerizable compounds and is not particularly limited. It can be continuous crystallization or batch crystallization, but continuous crystallization is preferred.

[0081] The crystallization process described above can be performed using the crystallization tank and / or ripening tank described later.

[0082] Furthermore, when extracting slurries containing crystals of easily polymerizable compounds, it is preferable to extract from near the bottom of the tank.

[0083] In the manufacturing method of the present invention, it is preferred that the solution containing the polymerizable compound is an aqueous solution of crude (meth)acrylic acid or a crude (meth)acrylic acid solution.

[0084] Crude (meth)acrylic acid aqueous solution refers to a solution formed by dissolving (meth)acrylic acid in water, and contains impurities such as byproducts from the production of (meth)acrylic acid. Crude (meth)acrylic acid solution refers to a solution composed entirely of (meth)acrylic acid, and contains impurities such as byproducts from the manufacturing of (meth)acrylic acid.

[0085] In addition, examples of the aforementioned impurities include, for instance, acids such as propionic acid, acetic acid, maleic acid, benzoic acid, and acrylic acid dimer; aldehydes such as acrolein, furfural, formaldehyde, and glyoxal; acetone; methyl isobutyl ketone; toluene; and protoanemonin.

[0086] Using the manufacturing method of the present invention, impurities (especially furfural, etc.) contained in solutions or slurries containing easily polymerizable compounds can be sufficiently removed, resulting in high-quality products. Furthermore, in this specification, a high-quality product is defined as one that sufficiently reduces at least one of the aforementioned impurities (e.g., furfural).

[0087] For example, the amount of furfural contained in the product of the easily polymerizable compound obtained by this manufacturing method is preferably 10 ppm or less, more preferably 5 ppm or less, and particularly preferably 0.2 ppm or less.

[0088] <The process of supplying a solution containing a polymerizable compound or a slurry containing crystals of a polymerizable compound to a crystallization tank or maturation tank>

[0089] The manufacturing method of the present invention may also include a step of supplying a solution containing a polymerizable compound or a slurry containing crystals of a polymerizable compound to a crystallization tank or a curing tank.

[0090] Examples of solutions containing polymerizable compounds or slurries containing crystals of polymerizable compounds supplied to the aforementioned tank include liquids composed of polymerizable compounds, aqueous solutions of polymerizable compounds, and aqueous slurries containing crystals of polymerizable compounds. Furthermore, the mother liquor of the aforementioned solutions containing polymerizable compounds or slurries containing crystals of polymerizable compounds typically contains impurities other than the aforementioned polymerizable compounds and water.

[0091] In the manufacturing method of the present invention, it is preferable that the purity (mass ratio) of the polymerizable compound in the mother liquor of the solution containing the polymerizable compound or the slurry containing the crystals of the polymerizable compound is 99% by mass or less.

[0092] Preferably, the mass percentage of the polymerizable compound in the mother liquor of the solution containing the polymerizable compound or the slurry containing the crystals of the polymerizable compound is 60% by mass or more.

[0093] When supplying the above-mentioned solution containing easily polymerizable compounds or slurry containing easily polymerizable compounds to a crystallization tank or maturation tank, the supply rate is not particularly limited, but in industrial-scale crystallization tanks or maturation tanks, it is, for example, 0.2 × 10⁻⁶. 3 kg / h~4.0×10 5 kg / h.

[0094]

[0095] The manufacturing method of the present invention may also include a step of recovering polymerizable compounds from the mother liquor separated by the above-described crystallization process.

[0096] The mother liquor used in the above-mentioned recovery process can be obtained, for example, by extracting and separating it from the crystals from the supernatant of a slurry containing crystals of readily polymerizable compounds in a self-crystallization tank or aging tank. The mother liquor is typically a solution containing readily polymerizable compounds.

[0097] The extracted mother liquor can be recovered and reused in the recycling process. By supplying and reusing the recovered polymerizable compounds to, for example, a downstream (front-end) tank or device, the amount of polymerizable compounds in the mother liquor separated by the crystallization process described above can be reduced.

[0098] There are no particular limitations on the recovery process described above; for example, distillation can be included. The extraction of the mother liquor can also be carried out using a pump or similar device.

[0099] <Stirring process in the curing tank>

[0100] The manufacturing method of the present invention may also include a step of stirring a slurry containing crystals of easily polymerizable compounds in a curing tank.

[0101] In the above-mentioned mixing process, the slurry containing crystals is usually mixed using the mixer provided in the maturation tank.

[0102] <Process of supplying to the cleaning column>

[0103] The manufacturing method of the present invention may also include the step of extracting a slurry containing crystals of easily polymerizable compounds from a self-crystallization tank or a ripening tank and supplying it to a cleaning column.

[0104] Furthermore, the above-mentioned process of supplying the cleaning column is equivalent to the following situation: in the above-mentioned process of feeding the slurry containing crystals of easily polymerizable compounds, the pipeline used to feed the slurry is a pipeline connecting the crystallization tank and the cleaning column or connecting the ripening tank and the cleaning column.

[0105] In the process of supplying the above-mentioned cleaning column, the feeding temperature of the slurry containing crystals can be appropriately set according to the melting point of the above-mentioned easily polymerizable compound, for example, it can be appropriately adjusted within the range of 1°C to 50°C.

[0106] For example, when the polymerizable compound is (meth)acrylic acid, the preferred liquid feeding temperature for the slurry containing crystals is 5°C to 13°C, more preferably 7°C to 11.5°C.

[0107] The feeding temperature of the crystal-containing slurry is the temperature of the mother liquor in the crystal-containing slurry (e.g., the crystal-containing slurry in the pipe or nozzle for feeding the crystal-containing slurry into the cleaning column) before it is fed into the cleaning column.

[0108] <Process for obtaining a solution containing a polymerizable compound from raw materials>

[0109] In the manufacturing method of the present invention, it is preferred that the manufacturing method includes a step of obtaining a solution containing a polymerizable compound from raw materials.

[0110] Preferably, the process of obtaining a solution containing a polymerizable compound from raw materials includes a process of obtaining a gas containing a polymerizable compound from raw materials and a process of obtaining a solution containing a polymerizable compound from a gas containing a polymerizable compound.

[0111] Regarding the above-mentioned process of obtaining a gas containing a polymerizable compound from raw materials, there are no particular limitations as long as a gas containing a polymerizable compound can be obtained. In the case that the polymerizable compound is (meth)acrylic acid, for example, the acrylic acid synthesis process (contact gas-phase oxidation reaction) described in Japanese Patent Application Publication No. 2007-182437 (Patent Document 1) can be appropriately carried out.

[0112] Regarding the above-mentioned process of obtaining a solution containing a polymerizable compound from a gas containing a polymerizable compound, there is no particular limitation as long as a solution containing a polymerizable compound is obtained. In the case that the polymerizable compound is (meth)acrylic acid, for example, the acrylic acid collection process described in Patent Document 1 can be used appropriately.

[0113] In the manufacturing method of the present invention, it is preferred that the above-mentioned (meth)acrylic acid is made from at least one selected from the group consisting of propane, propylene, acrolein, isobutylene, methacrolein, acetic acid, lactic acid, isopropanol, 1,3-propanediol, glycerol, and 3-hydroxypropionic acid. Alternatively, the above-mentioned (meth)acrylic acid and / or raw materials may also be derived from renewable raw materials to produce bio-based (meth)acrylic acid.

[0114] Furthermore, in the aforementioned process of obtaining a gas containing a readily polymerizable compound, impurities such as byproducts are generally generated. For example, when the readily polymerizable compound is (meth)acrylic acid, impurities such as water, propionic acid, acetic acid, maleic acid, benzoic acid, acrylic acid dimer, acrolein, furfural, formaldehyde, glyoxal, acetone, methyl isobutyl ketone, toluene, and protoanemonin are generated. However, using the manufacturing method of the present invention, the separation efficiency of impurities (especially furfural, etc.) is excellent, and the product is obtained efficiently.

[0115] Figure 1 This is a schematic diagram illustrating an example of a bend in the pipeline used in the manufacturing method of the present invention.

[0116] like Figure 1 As shown, the aforementioned radius of curvature R is equivalent to the radius of the circle corresponding to the arc when the center line (the line passing through the center of the inner diameter D of the pipeline) at the bend of the pipeline is set as an arc.

[0117] The inner diameter D of the pipeline mentioned above is the inner diameter at the bend of the pipeline.

[0118] In the manufacturing method of the present invention, by setting the ratio R / D of the curvature radius R to the inner diameter D of the pipeline to more than 4, the curvature of the bend is relatively gentle, thereby achieving the effect of the present invention in efficiently manufacturing high-quality products. Furthermore, by setting this ratio R / D to 10 or less, the size of the purification apparatus is not excessive, and the pipeline can be appropriately arranged.

[0119] Figures 2-8 This is a schematic diagram illustrating an example of a pipeline in the purification apparatus of the present invention that can be applied to the present invention.

[0120] exist Figures 2-8 In this invention, a pipeline capable of being used is one that delivers a slurry containing crystals of readily polymerizable compounds and is connected to at least one selected from the group consisting of a crystallization tank, a ripening tank, and a cleaning column. Furthermore, in... Figures 2-8 In the attached diagram, the pipeline marked with an underline is the pipeline.

[0121] In this invention, any of the bends in the pipeline that delivers the slurry containing crystals of easily polymerizable compounds and is connected to at least one of the selected components, including a crystallization tank, a ripening tank, and a cleaning column, shall satisfy the aforementioned ratio R / D of radius of curvature R to pipeline inner diameter D. However, it is more preferable that all the bends in the pipeline satisfy this ratio R / D.

[0122] The following is a detailed explanation. Figures 2-8 The purification apparatus of the present invention is shown in its usage configuration.

[0123] Figure 2 It is a device having a crystallization tank and a maturation tank as a crystallization apparatus, and is provided with a pipeline for directly conveying mother liquor from the maturation tank as an upstream tank to the crystallization tank, and a pipeline for directly discharging residue (mother liquor) from the crystallization tank as the downstream tank.

[0124] Solution 1 of the compound supplied to the purification unit is introduced into maturation tank 21. Cooled in crystallization tank 11 equipped with a cooling mechanism, the slurry containing precipitated crystals is conveyed to solid-liquid separation unit 31 via pipeline 51. In solid-liquid separation unit 31, the slurry is separated into mother liquor and concentrated crystal slurry. The concentrated crystal slurry is conveyed to the adjacent maturation tank 21 via pipeline 52, while the mother liquor is returned to crystallization tank 11 via pipeline 61. Additionally, residue 2 is discharged from crystallization tank 11 to the outside of the purification unit via pipeline 71, adjusting the liquid level in crystallization tank 11. After crystal growth in maturation tank 21, the crystal slurry is sent to mechanical cleaning column 41 via pipeline 53. Furthermore, mother liquor is directly conveyed from maturation tank 21 to crystallization tank 11 via pipeline 72 to adjust the liquid level in maturation tank 21.

[0125] Within the mechanical cleaning column 41, a piston compacts the crystals to form a crystal bed. Then, the crystal bed is shaving off at the bottom of the column, suspended in a circulating liquid, and heated to melt. A portion of the resulting circulating liquid containing the melt is discharged as high-purity compound 3. The remaining portion of the circulating liquid (cleaning liquid) is returned to the mechanical cleaning column 41, where it convects with the crystal bed to clean the crystals. Additionally, the mother liquor within the cleaning column is returned to the ripening tank 21 via a line 75 for returning the mother liquor to the crystallization apparatus. This process of compound purification yields a high-purity compound.

[0126] Figure 3 This is a crystallization apparatus comprising a crystallization tank and a maturation tank. It is equipped with a pipeline for directly supplying mother liquor from the maturation tank (an upstream tank) to the crystallization tank, and a pipeline for directly discharging residue (mother liquor) from the crystallization tank (the downstream tank). Furthermore, the crystallization tank is designed to cool the contents of an external cooling tank. The following discussion focuses only on... Figure 2 The different parts of the purification device will be explained.

[0127] The crystallization tank 11 consists of a tank 11A and an external cooling mechanism 11B, connected by pipelines 111 and 121. A solution of the compound (or a slurry containing crystals of the compound) is transported from tank 11A to cooling mechanism 11B via pipeline 111, where it is cooled. The slurry containing precipitated crystals is transported back to tank 11A via pipeline 121. A portion of the slurry containing crystals of the compound is transported from tank 11A to cooling mechanism 11B via pipeline 111, and the remainder is transported to solid-liquid separation device 31 via pipeline 51.

[0128] Figure 4This is a crystallization apparatus with two crystallization tanks. It is equipped with a pipeline for directly supplying mother liquor from crystallization tank 12 (the upstream tank) to crystallization tank 11, and a pipeline for directly discharging residue (mother liquor) from crystallization tank 11 (the downstream tank). Furthermore, the cleaning column is hydraulic and has a mechanical mechanism for shaping the crystal bed. The following description only pertains to... Figure 2 The different parts of the purification device will be explained.

[0129] The compound solution 1 supplied to the purification device is introduced into the crystallization tank 12. The crystallization tank 12 consists of a tank 11A and an external cooling mechanism 11B, which are connected by pipelines 111 and 121. The compound solution (or slurry containing compound crystals) transported from the tank 11A to the cooling mechanism 11B via pipeline 111 is cooled in the cooling mechanism 11B, and the slurry containing precipitated crystals is transported back to the tank 11A via pipeline 121. A portion of the slurry containing compound crystals is transported from the tank 11A to the cooling mechanism 11B via pipeline 111, and the remainder is transported to the solid-liquid separation device 31 via pipeline 51.

[0130] The crystallization tank 12 is also composed of a tank 12A and an external cooling mechanism 12B, which are connected by pipelines 112 and 122. A portion of the slurry containing the crystals of the compound is transported from the tank 12A to the cooling mechanism 12B through pipeline 112, and then returned to the tank 12A through pipeline 122.

[0131] Crystal slurry is fed from the crystallization tank 12 through pipeline 53 to the hydraulic cleaning column 42. At the bottom of the hydraulic cleaning column 42, a mechanical mechanism (scraper) abrades the crystal bed, suspending it in the circulating liquid. The crystal bed is then extracted and heated to melt it. A portion of the resulting circulating liquid containing the melt is sent out as high-purity compound 3. The remaining portion of the circulating liquid (cleaning liquid) is returned to the hydraulic cleaning column 42, where it convects with the crystal bed to clean the crystals.

[0132] Figure 5 This is a crystallization apparatus comprising two crystallization tanks and one ripening tank. A pipeline is installed between the three tanks to directly supply mother liquor from an upstream tank, and a pipeline is installed to directly discharge residue (mother liquor) from the downstream tank. The following discussion focuses only on... Figure 2 The different parts of the purification device will be explained.

[0133] The slurry containing precipitated crystals, cooled in the crystallization tank 11 equipped with a cooling mechanism, is transported to the solid-liquid separation unit 31 via pipeline 51. In the solid-liquid separation unit 31, the slurry is separated into mother liquor and concentrated crystal slurry. The concentrated crystal slurry is transported to the adjacent crystallization tank 12 via pipeline 52, while the mother liquor is returned to the crystallization tank 11 via pipeline 61. Additionally, residue 2 is discharged from the crystallization tank 11 to the outside of the purification unit via pipeline 71, and the liquid level in the crystallization tank 11 is adjusted. The same operation is performed in the crystallization tank 12, where the slurry containing crystals is transported from the crystallization tank 12 to the solid-liquid separation unit 32 via pipeline 53. In the solid-liquid separation unit 32, the slurry is separated into mother liquor and concentrated crystal slurry. The concentrated crystal slurry is transported to the adjacent ripening tank 21 via pipeline 54, while the mother liquor is returned to the crystallization tank 12 via pipeline 62. Additionally, mother liquor is directly supplied from crystallization tank 12 to crystallization tank 11 via pipeline 72 to adjust the liquid level in crystallization tank 12. After crystal growth in maturation tank 21, the crystal slurry is sent to mechanical cleaning column 41 via pipeline 55. Furthermore, mother liquor is directly supplied from maturation tank 21 to crystallization tank 12 via pipeline 73 connecting maturation tank 21 and crystallization tank 12 to adjust the liquid level in maturation tank 21.

[0134] Figure 6 This apparatus, used as a crystallization device, has three crystallization tanks and one ripening tank. Pipelines are installed between the four tanks to directly supply mother liquor from an upstream tank, and to directly discharge residue (mother liquor) from the downstream tank. Furthermore, the cleaning column is hydraulic and has a mechanical mechanism for shaping the crystal bed. The following discussion focuses only on... Figure 5 The different parts of the purification device will be explained.

[0135] The compound solution 1 supplied to the purification unit is introduced into the crystallization tank 13. The slurry containing crystals is fed from the second downstream crystallization tank 12 to the solid-liquid separation unit 32 via pipeline 53. In the solid-liquid separation unit 32, the slurry is separated into mother liquor and concentrated crystal slurry. The concentrated crystal slurry is transported to the adjacent crystallization tank 13 via pipeline 54, while the mother liquor is returned to the crystallization tank 12 via pipeline 62. Additionally, mother liquor is directly fed from the crystallization tank 12 to the crystallization tank 11 via pipeline 72 to adjust the liquid level in the crystallization tank 12. The same operation as in the crystallization tank 12 is performed in the crystallization tank 13, where the slurry containing crystals is fed from the crystallization tank 13 to the solid-liquid separation unit 33 via pipeline 55. In the solid-liquid separation device 33, the slurry is separated into mother liquor and concentrated crystal slurry. The concentrated crystal slurry is transported to the adjacent maturation tank 21 via pipeline 56, while the mother liquor is returned to the crystallization tank 13 via pipeline 63. Additionally, mother liquor is directly supplied from the crystallization tank 13 to the crystallization tank 12 via pipeline 73 to adjust the liquid level in the crystallization tank 13. After crystal growth in the maturation tank 21, the crystal slurry is sent to the hydraulic cleaning column 42 via pipeline 57. Furthermore, mother liquor is directly supplied from the maturation tank 21 to the crystallization tank 13 via pipeline 74 connecting the maturation tank 21 and the crystallization tank 13 to adjust the liquid level in the maturation tank 21.

[0136] At the lower part of the hydraulic cleaning column 42, a mechanical mechanism (scraper) is used to scrape the crystal bed, suspending it in the circulating liquid, and then extracting and heating it to melt it. A portion of the resulting circulating liquid containing the melt is sent out as high-purity compound 3. The remaining portion of the circulating liquid (cleaning liquid) is returned to the hydraulic cleaning column 42, where it comes into convective contact with the crystal bed to clean the crystals.

[0137] Figure 7 This is a device comprising two crystallization tanks and one ripening tank, used as a crystallization apparatus. A pipeline is installed between the three tanks to transport mother liquor from an upstream tank via a solid-liquid separation device, and a pipeline is installed to discharge residue from the downstream tank via the solid-liquid separation device. The following only applies to... Figure 5 The different parts of the purification device will be explained.

[0138] exist Figure 7 In the crystallization tank 11, instead of a pipeline for directly discharging residue, a solid-liquid separation device 33 for separating residue from the slurry in the crystallization tank and a pipeline for discharging residue via the solid-liquid separation device 33 are provided. The slurry taken from the crystallization tank 11 is transported to the solid-liquid separation device 33 through pipeline 81. The residue 2 separated by the solid-liquid separation device 33 is discharged outside the purification device through pipeline 91. The remaining concentrated crystal slurry is returned to the crystallization tank 11 through pipeline 82, and the liquid level in the crystallization tank 11 is adjusted.

[0139] In the crystallization tank 12, instead of the pipeline that directly supplies the mother liquor to the crystallization tank 11, a solid-liquid separation device 34 and a pipeline for supplying the mother liquor to the crystallization tank 11 via the solid-liquid separation device 34 are provided. The slurry taken out from the crystallization tank 12 is transported to the solid-liquid separation device 34 through the pipeline 83. The mother liquor separated by the solid-liquid separation device 34 is transported to the crystallization tank 11 through the pipeline 92 for liquid level adjustment. The remaining concentrated crystal slurry is returned to the crystallization tank 12 through the pipeline 84.

[0140] In the maturation tank 21, instead of the pipeline that directly supplies the mother liquor to the crystallization tank 12, a solid-liquid separation device 35 and a pipeline for supplying the mother liquor to the crystallization tank 12 via the solid-liquid separation device 35 are provided. The slurry taken out from the maturation tank 21 is transported to the solid-liquid separation device 35 through the pipeline 85. The mother liquor separated by the solid-liquid separation device 35 is transported to the crystallization tank 12 through the pipeline 93 for liquid level adjustment. The remaining concentrated crystal slurry is returned to the maturation tank 21 through the pipeline 86.

[0141] The cleaning column 43 is hydraulic and does not have a mechanical mechanism for cutting the crystal bed.

[0142] Figure 8 This is a crystallization apparatus comprising two crystallization tanks and one maturation tank. The apparatus includes pipelines for conveying mother liquor from the second crystallization tank to the downstream (first) crystallization tank via a solid-liquid separation device, and pipelines for discharging residue from the downstream tank via the solid-liquid separation device. It also includes a pipeline for directly conveying mother liquor from the maturation tank to the second crystallization tank. The solid-liquid separation device for separating mother liquor from the slurry taken from the second crystallization tank and conveying it to the downstream crystallization tank, and the solid-liquid separation device for separating residue discharged from the downstream crystallization tank to the purification apparatus, are both shared (or combined) by a pipeline for conveying slurry to one upstream tank. Furthermore, the crystallization tanks are designed to cool the contents of the tank outside the main tank. The following discussion focuses only on... Figure 7 The different parts of the purification device will be explained.

[0143] exist Figure 8In the apparatus, the crystallization tank 11 consists of a tank 11A and an external cooling mechanism 11B, connected by pipelines 111 and 121. A solution of the compound (or a slurry containing crystals of the compound) is transported from tank 11A to the cooling mechanism 11B via pipeline 111 and cooled by the cooling mechanism 11B. The slurry containing precipitated crystals is transported back to tank 11A via pipeline 121. A portion of the slurry containing crystals of the compound is transported from tank 11A to the cooling mechanism 11B via pipeline 111, and the remainder is transported to the solid-liquid separation device 31 via pipeline 51. Similarly, the crystallization tank 12 consists of a tank 12A and an external cooling mechanism 12B, connected by pipelines 112 and 122. A portion of the slurry containing crystals of the compound is transported from tank 12A to the cooling mechanism 12B via pipeline 112, and the remainder is transported to the solid-liquid separation device 32 via pipeline 53.

[0144] In addition, Figure 8 In the apparatus, a portion of the slurry containing the crystals of the compound is transported from tank 11A to solid-liquid separation unit 31 via pipeline 51. In solid-liquid separation unit 31, the slurry is separated into mother liquor and concentrated crystal slurry. The concentrated crystal slurry is transported to the adjacent tank 12A via pipeline 52. A portion of the mother liquor separated by solid-liquid separation unit 31 is returned to tank 11A via pipeline 61, and the remainder is discharged outside the purification unit via an additional pipeline 101 connected to pipeline 61. Similarly, in tank 12A, a portion of the slurry containing the crystals of the compound is transported to solid-liquid separation unit 32 via pipeline 53. In solid-liquid separation unit 32, the slurry is separated into mother liquor and concentrated crystal slurry. The concentrated crystal slurry is transported to the adjacent ripening tank 21 via pipeline 54. A portion of the mother liquor separated by the solid-liquid separation device 32 is returned to the crystallization tank 12 via pipeline 62, while the remaining portion is transported to tank 11A via an additional pipeline 102 connected to pipeline 62.

[0145] exist Figure 8 In the purification device, pipeline 51 → solid-liquid separation device 31 → pipelines 61, 101 and Figure 7 In the device, pipelines 81 → solid-liquid separation device 33 → pipelines 82 and 91 correspond to each other. The solid-liquid separation device 31 installed on the pipeline transporting slurry to the upstream tank is shared (or used interchangeably) as the solid-liquid separation device 33, replacing the need for a separate solid-liquid separation device 33. Similarly, pipelines 53 → solid-liquid separation device 32 → pipelines 62 and 102 are... Figure 7 In the device, the pipeline 83 → solid-liquid separation device 34 → pipeline 84, 92 correspond to the solid-liquid separation device 32 installed on the pipeline that transports slurry to the upstream tank. The solid-liquid separation device 34 is used instead of the solid-liquid separation device 34.

[0146] exist Figure 8In the device, replacing Figure 7 The apparatus has a self-curing tank 21 that supplies mother liquor to the crystallization tank 12 via a solid-liquid separation device 35, and a pipeline 73 that directly supplies mother liquor from the self-curing tank 21 to the tank 12A.

[0147] (Purification methods for easily polymerizable compounds)

[0148] In addition, the present invention is also a method for purifying a polymerizable compound using a purification apparatus comprising: a crystallization tank and / or a ripening tank, wherein the crystallization tank generates crystals of the polymerizable compound from a mother liquor containing a solution of the polymerizable compound or a slurry containing crystals of the polymerizable compound, and the ripening tank allows the crystals of the polymerizable compound to grow; and a washing column, characterized in that the purification apparatus further comprises a pipeline connected to at least one selected from the group consisting of a crystallization tank, a ripening tank, and a washing column, and having a bend in which the ratio of the radius of curvature R to the inner diameter D of the pipeline R / D exceeds 4 and is less than 10, the purification method comprising a step of feeding a slurry containing crystals of the polymerizable compound using the pipeline.

[0149] The purification method of the present invention can efficiently and effectively purify polymerizable compounds.

[0150] The preferred form of the purification method of the present invention is the same as the preferred form of the manufacturing method of the present invention described above.

[0151] (The purification apparatus of the present invention)

[0152] The present invention is also a purification apparatus for a polymerizable compound, comprising: a crystallization tank and / or a ripening tank, wherein the crystallization tank generates crystals of the polymerizable compound from a mother liquor containing a solution of the polymerizable compound or a slurry containing crystals of the polymerizable compound, and the ripening tank allows the crystals of the polymerizable compound to grow; and a washing column, wherein the purification apparatus further comprises a pipeline connected to at least one selected from the group consisting of a crystallization tank, a ripening tank, and a washing column, and having a bend in which the ratio of the radius of curvature R to the inner diameter D of the pipeline is greater than 4 and less than 10, the pipeline being used to deliver the slurry containing crystals of the polymerizable compound.

[0153] The above-mentioned pipeline can be any bend with a radius of curvature R to pipeline inner diameter D that is greater than 4 and less than 10. There are no particular limitations, but it is preferred to be a pipeline that connects the crystallization tank and the cleaning column or connects the ripening tank and the cleaning column.

[0154] That is, in the purification apparatus of the present invention, preferably, the above-mentioned pipeline is a pipeline connecting the crystallization tank and the cleaning column or connecting the ripening tank and the cleaning column, for feeding the slurry containing crystals of easily polymerizable compounds from the crystallization tank or the ripening tank to the cleaning column.

[0155] As other devices included in the purification apparatus of the present invention, the above-described devices can be used appropriately.

[0156] The aforementioned crystallization tank can be equipped with a cooling mechanism, as long as it can cool the solution containing easily polymerizable compounds or the slurry containing easily polymerizable crystals to cause crystal precipitation, thereby generating crystals; there are no particular limitations. Furthermore, it can be broadly categorized into the following methods: the tank itself has a cooling jacket for direct cooling of the tank to generate crystals (see [reference]). Figure 2 , Figure 5 , Figure 6 , Figure 7 The cooling mechanism is separate from the tank, and is connected by piping to circulate and cool simultaneously, thereby generating crystals (see reference). Figure 3 , Figure 4 , Figure 8 ).

[0157] Cooling mechanisms that are separate from the tank are not particularly limited as long as they can cool solutions containing easily polymerizable compounds or slurries containing easily polymerizable compounds to induce crystal precipitation. However, it is preferable to use cooling disc crystallizers, scraped surface heat exchangers, or votator-type heat exchangers that can ensure a large heat transfer area.

[0158] The crystallization temperature in the crystallization tank can be set to the temperature in the crystallization process described above.

[0159] The purification apparatus of the present invention has the aforementioned crystallization tank and / or ripening tank, and can have one or more tanks. When the purification apparatus of the present invention has multiple tanks (tanks 1 to N, with the first tank downstream and the Nth tank upstream), these multiple tanks are preferably connected in series. In this case, the purification apparatus of the present invention typically has a pipeline for conveying a slurry containing crystals of a polymerizable compound from tank to tank, with or without a solid-liquid separation device, as desired. Additionally, in this case, the purification apparatus of the present invention has a pipeline for supplying a solution containing a polymerizable compound or a slurry containing crystals of a polymerizable compound to at least one tank.

[0160] Furthermore, as described above, the purification apparatus of the present invention only needs to have a crystallization tank and / or a ripening tank; it may or may not have a ripening tank, but it is preferred to have one. In the present invention, the ripening tank is a tank for growing crystals of the compound. By feeding liquid into the washing column after crystal growth to form crystals with approximately uniform crystal shape, impurities can be efficiently removed using the washing column, and compounds with higher purity can be obtained in higher yields. Therefore, it is preferable that the tank for feeding liquid into the washing column, i.e., the Nth tank, is a ripening tank.

[0161] The purification apparatus of the present invention preferably has a pipeline for feeding a slurry containing crystals of the compound from a curing tank to a washing column.

[0162] The aforementioned ripening tank is only required to maintain the crystals of easily polymerizable compounds in a suspended state within the tank; there are no particular limitations. By holding the crystals for a certain period of time, Ostwald ripening is utilized to melt finer crystals and further grow larger crystals, thus narrowing the crystal diameter distribution. This yields high-quality crystals, which can be supplied to purification processes such as hydraulic cleaning columns as the next step, thereby further improving the purification efficiency of the hydraulic cleaning column.

[0163] The temperature in the ripening tank can be set to the temperature in the crystallization process described above.

[0164] The aforementioned curing tank typically has an extraction port near its bottom for extracting slurry containing easily polymerizable compounds from the curing tank.

[0165] The size of the crystallization tank or ripening tank is not particularly limited, but its inner diameter is preferably 100 mm to 50,000 mm. Furthermore, its height is preferably 1,000 mm to 100,000 mm.

[0166] The purification apparatus of the present invention may further include: an absorption tower for collecting gas containing a polymerizable compound to obtain a solution containing the polymerizable compound; and a pipeline for conveying the solution containing the polymerizable compound from the absorption tower to the crystallization tank or the aging tank.

[0167] The aforementioned absorption tower absorbs the reaction product obtained from the reactor, i.e., the gas containing easily polymerizable compounds, into water containing dissolved anti-polymerization agents, thereby obtaining a solution containing easily polymerizable compounds.

[0168] The pipeline used to transport the solution containing the polymerizable compound from the absorption tower to the crystallization tank or ripening tank may also include an intermediate tank, a resin tank filled with ion exchange resin, and a distillation apparatus for low-boiling distillation. Furthermore, as mentioned above, in the case where the polymerizable compound is (meth)acrylic acid, low-boiling components that can be removed by low-boiling distillation include, for example, acrolein, acetic acid, and water.

[0169] The purification apparatus of the present invention is preferably capable of performing a continuous purification process, and for example, it further includes a cleaning column (preferably a cleaning column that forcibly delivers crystals) as the downstream section of the tank of the present invention.

[0170] In addition, the purification apparatus of the present invention may also include a pipeline for extracting a circulating slurry containing crystals from a self-cleaning column and a device for dissolving the crystals contained in the extracted circulating slurry.

[0171] The crystals originate from a crystal bed formed at the bottom of the cleaning column. Crystal extraction can be performed, for example, using a mechanism that extracts crystals from a crystal bed within a self-cleaning column.

[0172] In addition, during crystal extraction, the circulating liquid is usually extracted as well, and is extracted as a circulating slurry containing crystals and supplied to the melting process.

[0173] The purification apparatus of the present invention may also include a pipeline (extraction pipeline) connecting the crystal extraction port of the washing column and the melting device, and a return pipeline connecting the melting device and the return port of the circulating liquid containing the extracted crystals located in the washing column. These pipelines and the portion within the washing column connecting the return port and the crystal extraction port are used for circulating the liquid. This circulation path is also referred to as the melting loop.

[0174] A heater can be used as the melting device described above. Examples of heaters include those capable of efficiently transferring heat to the slurry containing crystals, such as vertical multi-tube heat exchangers, horizontal multi-tube heat exchangers, shell-and-tube heat exchangers, spiral heat exchangers, plate heat exchangers, and electric heaters. This heater is installed in the melting loop, preferably in a forced circulation type where the circulating slurry (which becomes a circulating liquid after melting) is circulated using a pump installed in the melting loop.

[0175] The purification apparatus of the present invention may also include a pipeline connected to the above-described return pipeline for discharging the product from the above-described cleaning column.

[0176] As described above, the purification apparatus of the present invention may also include pipelines for returning the mother liquor from the upstream (rear) side tank or device to the downstream (front) side tank or device.

[0177] Furthermore, the purification apparatus of the present invention may also include a mechanism for controlling the feed rate of the slurry and the return rate of the mother liquor. Examples of such a control mechanism include valves installed in various pipelines.

[0178] The purification apparatus of the present invention may also appropriately include other apparatus commonly used in purification apparatuses.

[0179] Example

[0180] The present invention will be described in more detail below with examples, but the present invention is of course not limited to the following examples, and can be implemented by appropriate modifications within the scope of the spirit of the context, all of which are included within the technical scope of the present invention.

[0181] In addition, unless otherwise specified, "%" means "percentage of mass" and "parts" means "parts of mass".

[0182] (Measuring instruments for gas chromatography and liquid chromatography)

[0183] Gas chromatography: GC-2014 manufactured by Shimadzu Corporation

[0184] High Performance Liquid Chromatography: Shimadzu LC-20AD HPLC Unit

[0185] Use the above instruments to measure furfural.

[0186] (Method for obtaining acrylic acid aqueous solution)

[0187] According to the method described in International Publication No. 2010 / 032665, propylene is subjected to contact gas-phase oxidation to obtain a gas containing acrylic acid, and the obtained gas containing acrylic acid is treated in an absorption tower to obtain an aqueous solution of acrylic acid.

[0188] (Methods for obtaining the slurry)

[0189] An aqueous solution of acrylic acid is supplied to a crystallization tank with an inner diameter of 650 mm. Refrigerant is supplied to a jacket disposed on the peripheral wall of the crystallization tank for indirect cooling, thereby scraping off the crystals adhering to the inner surface of the crystallization tank by a scraper disposed inside the crystallization tank to prepare a slurry containing crystals (slurry supply).

[0190] (Purification methods for slurry)

[0191] A hydraulic cleaning column was used as the cleaning column for purifying the above-mentioned slurry. The slurry was supplied to the cleaning column via the following supply line. While the mother liquor of the slurry was extracted from the filter installed in the cleaning column, the crystal bed formed in the column was moved downwards by hydraulic pressure. The crystals were melted in the melting loop to obtain the product.

[0192] <Purification Apparatus - Implementation Conditions>

[0193] The prepared crystallization tank and the cleaning column are connected by a supply line with an inner diameter of 25 mm. This supply line has three bends, each at a 90° angle. The slurry prepared in the crystallization tank, with a crystal concentration of 11.0% by mass and a delivery temperature of 10.5°C, is supplied to the cleaning column via this supply line, yielding the product. Furthermore, the supply line is equipped with a jacket as a heating mechanism, into which a heat medium set to 15°C is introduced.

[0194] <Example 1>

[0195] The ratio of the radius of curvature R of all bends in the supply pipeline to the inner diameter D of the pipeline, R / D, was set to 5, and the linear velocity of the slurry supply was set to 1.5 m / s to obtain acrylic acid as the product. The concentration of furfural in the product, the furfural ratio, and the blockage status of the piping are shown in Table 1.

[0196] <Examples 2 and 3>

[0197] Except for changing the linear velocity of the slurry supply as described in Table 1, acrylic acid was obtained as the product in the same manner as in Example 1. The furfural concentration, furfural ratio, and pipe blockage status in the product are shown in Table 1.

[0198] <Example 4>

[0199] Except for changing the ratio of the radius of curvature R of all bends in the supply pipeline to the pipeline inner diameter D (R / D) to 10, and changing the linear velocity of the slurry supply to 1.8 m / s, acrylic acid was obtained as the product in the same manner as in Example 1. The furfural concentration, furfural ratio, and pipe blockage status in the product are shown in Table 1.

[0200] <Example 5>

[0201] Except for changing the linear velocity of the slurry supply as described in Table 1, acrylic acid was obtained as the product in the same manner as in Example 1. The furfural concentration, furfural ratio, and pipe blockage status in the product are shown in Table 1.

[0202] <Example 6>

[0203] Except for changing the crystal concentration of the supplied slurry as described in Table 1, acrylic acid was obtained as the product in the same manner as in Example 1. The pipe blockage status is shown in Table 1.

[0204] <Comparative Example 1>

[0205] Except for changing the ratio of the radius of curvature R of all bends in the supply pipeline to the pipeline inner diameter D (R / D) to 3, and changing the linear velocity of the slurry supply to 1.8 m / s, acrylic acid was obtained as the product in the same manner as in Example 1. The furfural concentration, furfural ratio, and pipe blockage status in the product are shown in Table 1.

[0206] <Example 7>

[0207] Except for changing the linear velocity of the slurry supply as described in Table 1, acrylic acid was obtained as the product in the same manner as in Example 1. The furfural concentration, furfural ratio, and pipe blockage status in the product are shown in Table 1.

[0208] [Table 1]

[0209]

[0210] *The furfural ratio is a ratio based on the furfural concentration in the product of Example 3.

[0211] As shown in Table 1 (Examples 2, 4, and Comparative Example 1), when the R / D ratio is small (4 or less), the furfural concentration in the product increases, and the product purity decreases. Furthermore, it is known that even when the R / D ratio is set relatively large, if it is 5 or more, the furfural concentration in the product remains approximately constant. Therefore, as described above, the ratio of the radius of curvature R to the inner diameter of the pipeline, R / D, is preferably 10 or less. It is known that even when the R / D ratio is set to 10 or more, the size of the purification apparatus increases, and on the other hand, it is not possible to expect the production of higher quality acrylic acid.

[0212] Furthermore, according to the results in Table 1 (Examples 1, 3, 5, 7), it can be seen that when the linear velocity of the slurry is at least within the specified range (above 1.5 m / s and below 4.0 m / s), high-quality products with low furfural concentration can be obtained efficiently.

[0213] Furthermore, according to the results in Table 1 (Examples 1 and 6), it is evident that when the crystal concentration of the supplied slurry is within the specified range (1% by mass or more and 40% by mass or less), clogging at the bends in the piping of the purification apparatus can be sufficiently prevented. Moreover, it is known that clogging is generally less likely when the crystal concentration of the slurry is low; therefore, in the case where the crystal concentration of the supplied slurry is 11.0% by mass or less as shown in Example 1, there are no problems related to piping clogging.

[0214] Based on the above results, it is evident that if the manufacturing method for easily polymerizable compounds includes the following steps, high-quality products can be obtained, and the blockage of pipelines by crystals can be effectively prevented, resulting in highly efficient and high-quality products: A purification apparatus equipped with a crystallization tank and a cleaning column is used to feed a slurry containing crystals of easily polymerizable compounds through a pipeline connected to the tank and / or cleaning column, having a bend in the pipeline with a radius of curvature R to the pipeline inner diameter D ratio R / D exceeding 4 and less than 10. Furthermore, the higher quality products obtained using the above manufacturing method are considered to be due to the ability to effectively prevent crystal growth and breakage within the pipeline, thus preventing an expansion of the crystal particle size distribution. A crystal bed with a substantially uniform crystal shape can be formed in the cleaning column, improving the cleaning performance.

[0215] Explanation of reference numerals in the attached figures

[0216] 1. Solution containing easily polymerizable compounds; 2. Residue; 3. High-purity easily polymerizable compounds; 11, 12. Crystallization tanks with cooling mechanisms; 11A. Tank (forming the downstream crystallization tank [the first crystallization tank]); 11B, 12B. Cooling mechanisms (outside the tank); 12A. Tank (forming the second crystallization tank); 21. Curing tank; 31-35. Solid-liquid separation device; 41. Mechanical cleaning column; 42. Hydraulic cleaning column (with features for removing...) 43. Mechanical mechanism of crystal bed; 51-57. Hydraulic cleaning column (without mechanical mechanism for cutting crystal bed); 61-63. Pipeline for conveying slurry from downstream tank to upstream tank or cleaning column; 71-74. Pipeline for returning mother liquor separated from slurry by solid-liquid separation device to the original tank; 71. Pipeline for discharging residue (mother liquor) directly from the downstream tank to the outside of purification device; 72-74. Pipeline for directly conveying mother liquor from upstream tank to a downstream tank; 7 5. A pipeline that returns the mother liquor to the maturation tank via a self-cleaning column; 81-86. A pipeline that separates the slurry taken from the tank by a solid-liquid separation device into a concentrated slurry containing crystals and returns it to the original tank; 91. A pipeline that discharges the residue (mother liquor) separated from the slurry taken from the tank by the solid-liquid separation device to the outside of the purification device; 92, 93. A pipeline that transports the mother liquor separated from the slurry taken from the tank by the solid-liquid separation device to a downstream tank; 101. For An additional pipeline for discharging a portion of the mother liquor separated from the slurry taken from the downstream tank by the solid-liquid separation device to the outside of the purification device; 102, an additional pipeline for conveying a portion of the mother liquor separated from the slurry taken from the second tank by the solid-liquid separation device to the downstream tank; 111, 112, 121, 122, pipelines connecting the tank and the cooling mechanism in the form of a crystallization tank in which the contents of the tank are cooled outside the tank; D, inner diameter of the pipeline; R, radius of curvature.

Claims

1. A method for manufacturing a polymerizable compound, comprising a purification apparatus having a crystallization tank and / or a ripening tank and a washing column, wherein, when the purification apparatus has the crystallization tank, the crystallization tank generates crystals of the polymerizable compound from a mother liquor containing a solution of the polymerizable compound or a slurry containing crystals of the polymerizable compound; and, when the purification apparatus has the ripening tank, the ripening tank allows the crystals of the polymerizable compound to grow, characterized in that... The purification apparatus also includes a pipeline connected to at least one selected from the group consisting of a crystallization tank, a ripening tank, and a washing column, and has a bend with a radius of curvature R to pipeline inner diameter D ratio R / D greater than 4 and less than 10. The manufacturing method includes a step of feeding a slurry containing crystals of easily polymerizable compounds into the pipeline. In the liquid delivery process, the linear velocity of the slurry is above 1.5 m / s and below 4.0 m / s.

2. The method for manufacturing the easily polymerizable compound according to claim 1, characterized in that, The pipeline is a pipeline connecting the crystallization tank and the cleaning column or connecting the ripening tank and the cleaning column. In the liquid delivery process, the pipeline is used to deliver a slurry containing crystals of easily polymerizable compounds from the crystallization tank or the ripening tank to the cleaning column.

3. The method for manufacturing the polymerizable compound according to claim 1 or 2, characterized in that, In the liquid delivery process, the crystal concentration of the slurry is 1% by mass or more and 40% by mass or less.

4. The method for manufacturing the polymerizable compound according to claim 1 or 2, characterized in that, The cleaning column is a hydraulic cleaning column.

5. The method for manufacturing the polymerizable compound according to claim 1 or 2, characterized in that, The pipeline is equipped with a heating mechanism. In the liquid delivery process, the temperature of the slurry is above 1°C and below 50°C.

6. The method for manufacturing the polymerizable compound according to claim 1 or 2, characterized in that, The manufacturing method includes the following steps: A gas containing easily polymerizable compounds is obtained from the raw materials; and A solution containing a polymerizable compound is obtained from a gas containing a polymerizable compound.

7. The method for manufacturing the polymerizable compound according to claim 1 or 2, characterized in that, The polymerizable compound is (meth)acrylic acid.

8. The method for manufacturing the polymerizable compound according to claim 7, characterized in that, The (meth)acrylic acid is made from at least one selected from the group consisting of propane, propylene, acrolein, isobutylene, methacrolein, acetic acid, lactic acid, isopropanol, 1,3-propanediol, glycerol, and 3-hydroxypropionic acid.

9. A purification apparatus for a polymerizable compound, comprising a crystallization tank and / or a ripening tank and a washing column, wherein, when the purification apparatus has the crystallization tank, the crystallization tank generates crystals of the polymerizable compound from a mother liquor containing a solution containing the polymerizable compound or a slurry containing crystals of the polymerizable compound; wherein, when the purification apparatus has the ripening tank, the ripening tank allows the crystals of the polymerizable compound to grow, characterized in that, The purification apparatus also includes a pipeline connected to at least one selected from the group consisting of a crystallization tank, a ripening tank, and a washing column, and has a bend with a radius of curvature R to pipeline inner diameter D ratio R / D greater than 4 and less than 10. This pipeline is used to deliver liquid to slurries containing crystals of easily polymerizable compounds.

10. The purification apparatus for easily polymerizable compounds according to claim 9, characterized in that, The pipeline is a pipeline connecting the crystallization tank and the cleaning column or connecting the ripening tank and the cleaning column. This pipeline is used to feed a slurry containing crystals of easily polymerizable compounds from the crystallization tank or ripening tank to the cleaning column.

11. The method for manufacturing the polymerizable compound according to claim 1 or 2, characterized in that, The ratio of the radius of curvature R to the inner diameter D of the pipeline, R / D, is 4.5 or higher.

12. The method for manufacturing the polymerizable compound according to claim 11, characterized in that, The ratio of the radius of curvature R to the inner diameter D of the pipeline, R / D, is 5 or higher.

13. The method for manufacturing the polymerizable compound according to claim 1 or 2, characterized in that, The ratio of the radius of curvature R to the inner diameter D of the pipeline, R / D, is less than 9.

14. The method for manufacturing the polymerizable compound according to claim 13, characterized in that, The ratio of the radius of curvature R to the inner diameter D of the pipeline, R / D, is less than 8.

15. The method for manufacturing the polymerizable compound according to claim 1 or 2, characterized in that, The angle formed by the bending portion is 75° to 165°.

16. The method for manufacturing the polymerizable compound according to claim 15, characterized in that, The angle formed by the bending portion is 90° to 150°.

17. The method for manufacturing the polymerizable compound according to claim 1, characterized in that, The pipeline is selected from at least one of the group consisting of pipelines connecting crystallization tanks and crystallization tanks, pipelines connecting crystallization tanks and ripening tanks, pipelines connecting crystallization tanks and cleaning columns or connecting ripening tanks and cleaning columns, and pipelines of a melting apparatus connecting cleaning columns and melting loops.

18. The method for manufacturing the polymerizable compound according to claim 17, characterized in that, The pipeline is selected from at least one of the group consisting of a pipeline connecting a crystallization tank and a crystallization tank, a pipeline connecting a crystallization tank and a ripening tank, and a pipeline connecting a crystallization tank and a cleaning column or connecting a ripening tank and a cleaning column.

19. The method for manufacturing the polymerizable compound according to claim 1, characterized in that, In the liquid delivery process, the linear velocity of the slurry is 1.8 m / s or higher.

20. The method for manufacturing the polymerizable compound according to claim 19, characterized in that, In the liquid delivery process, the linear velocity of the slurry is 2.0 m / s or higher.

21. The method for manufacturing the polymerizable compound according to claim 1, characterized in that, In the liquid delivery process, the linear velocity of the slurry is less than 3.5 m / s.

22. The method for manufacturing the polymerizable compound according to claim 21, characterized in that, In the liquid delivery process, the linear velocity of the slurry is less than 3.0 m / s.

23. The method for manufacturing the polymerizable compound according to claim 3, characterized in that, In the liquid delivery process, the crystal concentration of the slurry is 5% by mass or more.

24. The method for manufacturing the polymerizable compound according to claim 23, characterized in that, In the liquid delivery process, the crystal concentration of the slurry is 10% by mass or more.

25. The method for manufacturing the polymerizable compound according to claim 3, characterized in that, In the liquid delivery process, the crystal concentration of the slurry is 38% by mass or less.

26. The method for manufacturing the polymerizable compound according to claim 25, characterized in that, In the liquid delivery process, the crystal concentration of the slurry is 35% by mass or less.

27. The method for manufacturing the polymerizable compound according to claim 5, characterized in that, In the liquid delivery process, the temperature difference between the heating temperature of the heating mechanism and the temperature of the slurry is 1℃ to 40℃.

28. The method for manufacturing the polymerizable compound according to claim 27, characterized in that, In the liquid delivery process, the temperature difference between the heating temperature of the heating mechanism and the temperature of the slurry is greater than 2°C.

29. The method for manufacturing the polymerizable compound according to claim 28, characterized in that, In the liquid delivery process, the temperature difference between the heating temperature of the heating mechanism and the temperature of the slurry is more than 3°C.

30. The method for manufacturing the polymerizable compound according to claim 27, characterized in that, In the liquid delivery process, the temperature difference between the heating temperature of the heating mechanism and the temperature of the slurry is less than 30°C.

31. The method for manufacturing the polymerizable compound according to claim 30, characterized in that, In the liquid delivery process, the temperature difference between the heating temperature of the heating mechanism and the temperature of the slurry is less than 20°C.

32. The method for manufacturing the polymerizable compound according to claim 31, characterized in that, In the liquid delivery process, the temperature difference between the heating temperature of the heating mechanism and the temperature of the slurry is less than 10°C.

33. The method for manufacturing the polymerizable compound according to claim 1 or 2, characterized in that, The polymerizable compound is a polymerizable compound with reactive double bonds.

34. The method for manufacturing the polymerizable compound according to claim 1 or 2, characterized in that, The polymerizable compound is an unsaturated carboxylic acid.

35. The method for manufacturing the polymerizable compound according to claim 7, characterized in that, The polymerizable compound is acrylic acid.

36. The method for manufacturing the polymerizable compound according to claim 1 or 2, characterized in that, The method for manufacturing the polymerizable compound includes a step of crystallizing a solution containing the polymerizable compound or a slurry containing crystals of the polymerizable compound.

37. The method for manufacturing the polymerizable compound according to claim 36, characterized in that, The temperature during the crystallization process is in the range of -2°C to -15°C relative to the melting point of the purified polymerizable compound.

38. The method for manufacturing the polymerizable compound according to claim 7, characterized in that, The temperature in the crystallization process is in the range of 0℃ to 12℃.

39. The method for manufacturing the polymerizable compound according to claim 38, characterized in that, The temperature in the crystallization process is in the range of 1℃ to 11℃.

40. The method for manufacturing the polymerizable compound according to claim 39, characterized in that, The temperature in the crystallization process is in the range of 2℃ to 10℃.

41. The method for manufacturing the polymerizable compound according to claim 1 or 2, characterized in that, The solution containing the polymerizable compound is an aqueous solution of crude (meth)acrylic acid or a crude (meth)acrylic acid solution.

42. The method for manufacturing the polymerizable compound according to claim 1 or 2, characterized in that, The method for manufacturing the polymerizable compound includes a step of obtaining a solution containing the polymerizable compound from raw materials.

43. The purification apparatus for easily polymerizable compounds according to claim 9 or 10, characterized in that, The ratio of the radius of curvature R to the inner diameter D of the pipeline, R / D, is 4.5 or higher.

44. The purification apparatus for polymerizable compounds according to claim 43, characterized in that, The ratio of the radius of curvature R to the inner diameter D of the pipeline, R / D, is 5 or higher.

45. The purification apparatus for easily polymerizable compounds according to claim 9 or 10, characterized in that, The ratio of the radius of curvature R to the inner diameter D of the pipeline, R / D, is less than 9.

46. ​​The purification apparatus for easily polymerizable compounds according to claim 45, characterized in that, The ratio of the radius of curvature R to the inner diameter D of the pipeline, R / D, is less than 8.

47. The purification apparatus for easily polymerizable compounds according to claim 9 or 10, characterized in that, The angle formed by the bending portion is 75° to 165°.

48. The purification apparatus for easily polymerizable compounds according to claim 47, characterized in that, The angle formed by the bending portion is 90° to 150°.

49. The purification apparatus for easily polymerizable compounds according to claim 9, characterized in that, The pipeline is selected from at least one of the group consisting of pipelines connecting crystallization tanks and crystallization tanks, pipelines connecting crystallization tanks and ripening tanks, pipelines connecting crystallization tanks and cleaning columns or connecting ripening tanks and cleaning columns, and pipelines of a melting apparatus connecting cleaning columns and melting loops.

50. The purification apparatus for easily polymerizable compounds according to claim 49, characterized in that, The pipeline is selected from at least one of the group consisting of a pipeline connecting a crystallization tank and a crystallization tank, a pipeline connecting a crystallization tank and a ripening tank, and a pipeline connecting a crystallization tank and a cleaning column or connecting a ripening tank and a cleaning column.

51. The purification apparatus for easily polymerizable compounds according to claim 9 or 10, characterized in that, The crystallization tank is equipped with a cooling mechanism.

52. The purification apparatus for easily polymerizable compounds according to claim 9 or 10, characterized in that, The purification apparatus for the polymerizable compound has multiple tanks that serve as crystallization tanks and / or aging tanks, which are connected in series.

53. The purification apparatus for easily polymerizable compounds according to claim 9 or 10, characterized in that, The curing tank is able to maintain the crystals of easily polymerizable compounds in a suspended state within the tank.

54. The purification apparatus for easily polymerizable compounds according to claim 9 or 10, characterized in that, The purification apparatus for the polymerizable compound further comprises: an absorption tower for collecting gas containing the polymerizable compound to obtain a solution containing the polymerizable compound; and a pipeline for conveying the solution containing the polymerizable compound from the absorption tower to the crystallization tank or the aging tank.

Images