A method and device for improving MAQ yield

Abstract

The application discloses a method and device for improving MAQ yield, and the method comprises the following steps: taking HPPA, sulfuric acid and methanol as raw materials, and sequentially performing the steps of dosing, esterification, cleaning, crystallization and drying to obtain the MAQ, wherein the weight ratio of HPPA to methanol is 0.8-1.2:0.8-1.2. Through the method, the direct reaction can reach a conversion rate of more than 99%, the water washing is omitted, and the condensation reflux during the reaction is omitted, so that the cost is greatly saved.

Description

TECHNICAL FIELD

[0001] The present application relates to the chemical technology field, in particular to a method and device for improving the yield of MAQ. BACKGROUND

[0002] MAQ is a chemical substance, specifically R-(+)-2-(4-hydroxyphenoxy) propionic acid methyl ester, with a molecular formula of C 10 H 12 O4, which appears as white powder, and its applications include but are not limited to an important intermediate for the synthesis of phenoxy propionic acid herbicides.

[0003] The existing technology MAQ production process is to use HPPA (R-(+)-2-(4-hydroxyphenoxy) propionic acid), methanol, sulfuric acid, and toluene as raw materials, to carry out esterification reaction under normal pressure conditions, over the boiling point of methanol (80℃), after reaction, to remove water, methanol, and toluene in the system under negative pressure, and to achieve a material conversion rate of about 98% through three repeated processes. The specific method is that HPPA: methanol = 3:2 (weight ratio), sulfuric acid ratio 1%, toluene is added in three times, the reaction is carried out under normal pressure and 80℃, after the reaction, 1:2 toluene is added for alkali washing and water washing, after detection, the qualified product is removed, and then the temperature is lowered, crystallization, centrifugation (the centrifugal mother liquor needs to be cleaned), and drying.

[0004] The above-mentioned conversion rate is low, and the content of the qualified product needs to be ≥99%, and the HPPA that has not completed esterification needs to be added with a solvent for dissolution, cleaned to remove impurities, and then the solvent is removed, and the process is more complex. Therefore, there is an urgent need for a MAQ production process with high conversion rate and relatively simplified process. SUMMARY

[0005] The present application aims to provide a method and device for improving the yield of MAQ to improve the conversion rate.

[0006] In order to achieve the above-mentioned purpose, the present application provides a method and device for improving the yield of MAQ, which adopts the technical scheme as follows:

[0007] According to the first technical scheme of the present application, a method for improving the yield of MAQ is provided, which comprises:

[0008] HPPA, sulfuric acid, and methanol are used as raw materials, and the MAQ is prepared through the processes of batching, esterification, cleaning, crystallization, and drying in sequence, wherein the weight ratio of HPPA to methanol is 0.8-1.2:0.8-1.2.

[0009] Further, the batching process comprises:

[0010] HPPA and sulfuric acid are mixed and dissolved to obtain the batching under normal pressure conditions.

[0011] Further, the esterification process comprises:

[0012] Sulfuric acid is added to the ingredients to perform the esterification reaction, which comprises: after nitrogen blowing, the temperature is raised to 100±5℃, after the reaction is completed, the temperature is lowered to 40±5℃, the pressure is adjusted to normal pressure, and the temperature is raised to 70±5℃, the pressure is adjusted to-0.08mpa, and the unreacted methanol is removed and rectified;

[0013] Methanol and sulfuric acid are added again, and the esterification reaction is repeated twice, wherein the added methanol includes the methanol obtained by removing and rectifying the unreacted methanol, after removing the methanol, the temperature is lowered to 40±5℃, and an appropriate amount of toluene is added to obtain the first material.

[0014] Further, the cleaning process comprises:

[0015] Toluene is added to the first material, and after the temperature is lowered to 40℃ or below, the pH is adjusted, stirred, and separated into the lower aqueous solution;

[0016] Washing with water, removing toluene by heating, the highest temperature is not more than 95℃, and the pressure is set to-0.08mpa,

[0017] After removing a certain amount of toluene, the temperature is lowered to 40±5℃ to obtain the second material.

[0018] Further, the crystallization process comprises:

[0019] The temperature of the second material is lowered to below 5℃, and solid-liquid separation is performed by centrifugation, the solid material enters the drying process, and the liquid material is a toluene solution, which is filtered and used as the feed of the esterification process and the cleaning process.

[0020] Further, the drying process comprises:

[0021] In a vacuum environment, the temperature of the solid material is raised to 50~705℃ to obtain the MAQ product.

[0022] Further, the removal and rectification of the unreacted methanol specifically comprises:

[0023] After the unreacted methanol is removed and preheated, it is rectified, and methanol is recovered by condensation, wherein the preheating pressure is normal pressure, and the temperature is 65~70℃.

[0024] According to the second technical solution of the present application, a device for improving the yield of MAQ is provided, which is used to realize the method as described above, and the device comprises a high-concentration alcohol tank, the high-concentration alcohol tank is connected to a batching kettle through a pipeline, and is used to pour methanol into the batching kettle, the batching kettle stirs the poured methanol, and HPPA is added through a traveling crane during the stirring process, the batching kettle is connected to an esterification kettle through a pipeline to transfer the obtained ingredients into the esterification kettle.

[0025] The sulfuric acid metering tank is connected to the esterification kettle by a pipeline to add sulfuric acid into the esterification kettle, the esterification kettle is connected to a low-concentration alcohol tank and a methyl ester desolventizing kettle by a pipeline to remove unreacted methanol to the low-concentration alcohol tank and transfer the first material after the esterification reaction to the methyl ester desolventizing kettle, and the esterification kettle is connected to a toluene low tank by a pipeline to add toluene through the toluene low tank;

[0026] The methyl ester desolventizing kettle is connected to a toluene transfer tank by a pipeline to add a toluene solution from the toluene transfer tank for solution, the methyl ester desolventizing kettle is connected to a sodium bicarbonate dissolving kettle by a pipeline to add sodium bicarbonate from the sodium bicarbonate dissolving kettle for pH adjustment, and the methyl ester desolventizing kettle is connected to a crystallization kettle by a pipeline to transfer the second material to the crystallization kettle.

[0027] The crystallization kettle is connected to a centrifuge by a pipeline to send the material after crystallization to the centrifuge for solid-liquid separation, two ports of the centrifuge are respectively connected to a vacuum dryer and a centrifugal mother liquor tank by a pipeline to send the solid material to a drying process and receive toluene solution through the centrifugal mother liquor tank, and the centrifugal mother liquor tank is connected to the esterification kettle and the methyl ester desolventizing kettle by a pipeline.

[0028] Further, the centrifugal mother liquor tank is connected to a filter and the crystallization kettle by a pipeline in sequence.

[0029] Further, the low-concentration alcohol tank is connected to a preheater and a rectifying column by a pipeline in sequence, and the rectifying column is connected to a methanol receiving tank by a pipeline to receive the rectified methanol for standby.

[0030] The method and device for improving the yield of MAQ according to the present application have the following beneficial effects: HPPA: methanol = 1:1 (weight ratio), the proportion of sulfuric acid is 1%, toluene is added in three times, the reaction is carried out under the conditions of 0.6 mpa and 120 DEG C, 1:0.8 toluene is added after the reaction, cooling, crystallization, centrifugation (the centrifugal mother liquor needs to be cleaned), and drying, through the improvement of the reaction mode, the conversion rate of more than 99% is directly achieved, the water washing is saved, the condensation reflux during the reaction is saved, and the cost is greatly saved. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the present application, the drawings needed to be used in the specific embodiments or prior art description will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual proportion.

[0032] Figure 1 A flow chart of a method for improving the yield of MAQ according to an embodiment of the present application is shown.

[0033] Figure 2 A structure diagram of a device for improving MAQ yield according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0034] The present application is described in greater detail by the following specific examples, and other advantages and effects of the present application can be easily understood by those skilled in the art from this disclosure. The present application can also be implemented or applied by other different specific embodiments, and various modifications or changes can be made to the details of the present application based on different views and applications without departing from the spirit of the present application. It should be noted that the following examples and features in the examples can be combined with each other without conflict.

[0035] In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more; the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0036] In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0037] The specific embodiments of the present application are further described in detail below in conjunction with the drawings and examples.

[0038] The present application provides a method for improving MAQ yield, as shown in the method comprises: taking HPPA, sulfuric acid and methanol as raw materials, and sequentially going through the processes of batching, esterification, cleaning, crystallization and drying to obtain the MAQ, wherein the weight ratio of HPPA to methanol is 1:1. Figure 1 The main chemical reaction equation is:

[0039]

[0040]

[0041] ​The working principle of the method is that under acidic conditions, the esterification reaction is reversible, accompanied by hydrolysis reaction, increasing the reaction pressure and temperature, so that the reaction proceeds in the positive direction.

[0042] The various steps involved in the method will be described in detail below in conjunction with a specific device for improving the yield of MAQ, the structure of which is shown in Figure 2 .

[0043] (1) batching

[0044] Methanol is pumped from the high-concentration alcohol tank 100 into the batching kettle 200, and stirring is started. HPPA is added to the kettle using a row of hangers, and the jacket is circulated with water. The dissolution is an endothermic reaction, and after the dissolution is complete under normal pressure conditions, the material is transferred to the esterification kettle 300.

[0045] (2) esterification

[0046] The material is transferred to the esterification kettle 300, sulfuric acid is added from the sulfuric acid metering tank 400, nitrogen is purged for half an hour, then all valves are closed, the temperature is raised to 100±5°C, and the reaction is carried out for 2 hours. The jacket is circulated with water to reduce the temperature to 40°C, the pressure is adjusted to normal pressure, then the distillation system is started, the jacket is circulated with steam, the temperature is raised to 70°C, the pressure is -0.08mpa, and the unreacted methanol is removed and enters the low-concentration alcohol tank 600 after passing through the receiving tank 500, thereby transferring to the methanol rectification system.

[0047] Methanol and sulfuric acid are added again to the kettle, and the esterification process is repeated. After about 2 esterifications, the material is reacted to pass the test, the methanol is removed, the jacket is circulated with water to reduce the temperature to 40°C, and a small amount of toluene is added from the toluene low tank to prevent the material from crystallizing. The material is transferred to the methyl ester desolventizing kettle 700 using a transfer pump.

[0048] (3) washing

[0049] The methyl ester desolventizing kettle 700 is first dissolved in toluene (solution) from the toluene transfer tank 800, the jacket is circulated with low-temperature water to reduce the temperature to below 40°C, a small amount of baking soda solution is added from the baking soda dissolution kettle 900 to make the pH in the reaction kettle 7, and the mixture is stirred and separated. The lower aqueous solution is separated into the water separation storage tank 1000. According to the situation, the kettle is washed once with a small amount of water, the water is separated into the water separation storage tank 1000, then the jacket is changed to circulation with steam to raise the temperature to remove toluene, the maximum temperature is not more than 95°C, and the pressure is -0.08mpa. After a small amount of toluene is removed, low-temperature water is used to reduce the temperature to about 40°C, and the material is transferred to the crystallization kettle 1100.

[0050] (4) crystallization

[0051] The crystallization kettle 1100 is circulated with refrigerated water to reduce the material to below 5°C, then the material is transferred to the centrifuge (M6801) for solid-liquid separation by the automatic centrifuge, the solid is transferred to the drying room for drying, and the liquid is transferred to the centrifugal mother liquor tank.

[0052] (5) Drying

[0053] The material is transferred into the drying machine by vacuum, the jacket is heated by hot water, the temperature is 50~70℃, -0.09mpa, and the drying is finished after about 4~6 hours, then the material is weighed, packed and stored.

[0054] (6) Filtration

[0055] The toluene solution in the centrifugal mother liquor tank is transferred into the esterification filter kettle after several times of recycling, the jacket is heated by steam, the temperature is raised to 60℃, and the solution is filtered into the crystallization kettle under the nitrogen pressure of 0.06mpa.

[0056] (7) Methanol rectification

[0057] The methanol in the low-concentration alcohol tank is preheated by the preheater and then enters the rectification tower for rectification, the preheater jacket is heated by steam, the material temperature is controlled to 65℃, normal pressure, the top temperature is controlled to 70℃, the heavy liquid enters the rectification kettle, and then is transferred into the sewage treatment, and the light phase is recovered by condensation and then enters the methanol receiving tank.

[0058] Through the above steps, the content of the obtained MAQ product reaches more than 99% through actual measurement, the reaction method is improved, the conversion rate reaches more than 99% directly, the water washing is saved, the condensation reflux during the reaction is saved, and the cost is greatly saved.

[0059] The above implementation manners are only used for describing the present application, and are not used for limiting the present application, ordinary technicians in the related technical field can also make various changes and modifications without departing from the spirit and scope of the present application, therefore, all equivalent technical solutions also belong to the scope of the present application, and the patent protection scope of the present application should be limited by the claims.

Claims

1. A method for improving MAQ yield, characterized in that: The method comprises: The MAQ is prepared using HPPA, sulfuric acid and methanol as raw materials through the steps of batching, esterification, washing, crystallization and drying, wherein the weight ratio of HPPA to methanol is 0.8-1.2:0.8-1.2; The esterification process comprises: Sulfuric acid is added to the ingredients to carry out an esterification reaction, wherein the esterification reaction comprises: heating to 100±5°C after nitrogen purging, cooling to 40±5°C after the reaction is complete, adjusting the pressure to normal pressure, and heating to 70±5°C, adjusting the pressure to -0.08 MPa, removing unreacted methanol and performing rectification; Methanol and sulfuric acid are added again, and the esterification reaction is repeated twice, wherein the added methanol includes methanol obtained by removing unreacted methanol and performing distillation, and after removing the methanol, the temperature is lowered to 40±5° C., and an appropriate amount of toluene is added to obtain a first material; The cleaning process comprises: Add toluene to the first material, cool it to below 40°C, adjust the pH, stir and separate the layers, and separate the lower aqueous solution; Add water to rinse, increase the temperature to remove toluene, the maximum temperature does not exceed 95℃, and the pressure is set to -0.08mpa. After removing a certain amount of toluene, the temperature was lowered to 40±5° C. to obtain the second material.

2. The method for improving MAQ yield according to claim 1, wherein The batching process includes: Under normal pressure, HPPA and sulfuric acid are mixed and dissolved to obtain ingredients.

3. The method for improving MAQ yield according to claim 2, wherein: The crystallization process includes: The temperature of the second material is cooled to below 5°C, and the solid-liquid separation is carried out by centrifugation. The solid material enters the drying process, and the liquid material is a toluene solution, which is filtered and used as the feed for the esterification process and the cleaning process.

4. The method for improving MAQ yield according to claim 3, wherein: The drying process includes: Under vacuum environment, the temperature of the solid material is raised to 50~705℃ to obtain MAQ product.

5. The method for improving MAQ yield according to claim 4, wherein: The step of removing the unreacted methanol and performing distillation specifically comprises: The unreacted methanol is removed, preheated, and then distilled, and condensed to recover methanol, wherein the preheating pressure is normal pressure and the temperature is 65~70℃.

6. A device for improving MAQ yield, for implementing the method according to claim 5, characterized in that: The device includes a high-concentration alcohol tank, the high-concentration alcohol tank is connected to a batching kettle via a pipeline, and is used to add methanol into the batching kettle. The batching kettle stirs the added methanol, and HPPA is added via a crane during the stirring process. The batching kettle is connected to an esterification kettle via a pipeline to transfer the obtained ingredients into the esterification kettle. The sulfuric acid metering tank pipeline is connected to the esterification kettle to add sulfuric acid into the esterification kettle, the esterification kettle pipeline is connected to the low-concentration alcohol tank and the methyl ester desolvation kettle to remove unreacted methanol to the low-concentration alcohol tank and transfer the first material after the esterification reaction to the methyl ester desolvation kettle, and the esterification kettle pipeline is connected to the toluene low-level tank to add toluene through the toluene low-level tank; The methyl ester desolventizing kettle pipeline is connected to a toluene transfer tank to add a toluene solution from the toluene transfer tank for dissolution, the methyl ester desolventizing kettle pipeline is connected to a baking soda dissolution kettle to add baking soda from the baking soda dissolution kettle to adjust the pH value, and the methyl ester desolventizing kettle pipeline is connected to a crystallization kettle to transfer the second material to the crystallization kettle; The crystallization kettle pipeline is connected to the centrifuge to send the crystallized material into the centrifuge for solid-liquid separation. The two ports of the centrifuge are respectively connected to the vacuum dryer and the centrifugal mother liquor tank through pipelines, for sending the solid material to the drying process and receiving the toluene solution through the centrifugal mother liquor tank; the centrifugal mother liquor tank is respectively connected to the esterification kettle and the methyl ester desolventizing kettle through pipelines.

7. The device for improving MAQ yield according to claim 6, characterized in that: The centrifugal mother liquor tank is sequentially connected to the filter and the crystallization kettle through pipelines.

8. The device for improving MAQ yield according to claim 6, characterized in that: The low-concentration alcohol tank is connected to the preheater and the distillation tower in sequence through pipelines, and the distillation tower pipeline is connected to the methanol receiving tank to receive the distilled methanol for standby use.

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