阅读说明：本技术 纯化甲硫氨酸的制造方法及甲硫氨酸的固结防止方法 (Method for producing purified methionine and method for preventing solidification of methionine ) 是由 古泉善行 山城直也 守本玲 于 2018-07-19 设计创作，主要内容包括：本发明的课题在于提供能够防止甲硫氨酸的固结的纯化甲硫氨酸的制造方法。本发明涉及纯化甲硫氨酸的制造方法,其为由粗制甲硫氨酸制造纯化甲硫氨酸的方法,该方法包括下述工序：(1)得到经水洗的粗制甲硫氨酸的湿滤饼的工序、(2)对前述湿滤饼的pH进行调节的工序、和(3)将pH调节后的前述湿滤饼干燥的工序,其中,pH调节后的前述湿滤饼的pH为5.2以上且6.1以下。(The present invention addresses the problem of providing a method for producing purified methionine, whereby solidification of methionine can be prevented. The present invention relates to a method for producing purified methionine from crude methionine, comprising the steps of: (1) a step of obtaining a wet cake of crude methionine washed with water, (2) a step of adjusting the pH of the wet cake, and (3) a step of drying the wet cake after pH adjustment, wherein the pH of the wet cake after pH adjustment is 5.2 or more and 6.1 or less.)

1. A method for producing purified methionine from crude methionine, said method comprising the steps of:

a step for obtaining a wet cake of water-washed crude methionine;

adjusting the pH of the wet cake; and

a step of drying the wet cake after the pH adjustment,

wherein the pH of the wet cake after the pH adjustment is 5.2 or more and 6.1 or less.

2. The method of claim 1, wherein the pH of the wet cake after pH adjustment is 5.7 or greater.

3. A method of preventing or eliminating the consolidation of methionine, said method comprising the steps of:

a step for obtaining a wet cake of methionine;

adjusting the pH of the wet cake; and

a step of drying the wet cake after the pH adjustment,

wherein the pH of the wet cake after the pH adjustment is 5.2 or more and 6.1 or less.

4. The method of claim 3, wherein the pH of the wet cake after pH adjustment is 5.7 or greater.

Technical Field

This patent application claims priority on paris convention based on japanese patent application No. 2017-140093 (application date: 2017, 7 and 19), which is hereby incorporated by reference in its entirety into this specification.

The present invention relates to a method for producing purified methionine and a method for preventing the solidification of methionine.

Background

Methionine can be obtained by hydrolysis reaction of 5- (2- (methylthio) ethyl) imidazolidine-2, 4-dione as shown in the following reaction formula (1), for example.

[ chemical formula 1]

Methionine is useful as a feed supplement for animals. Various studies have been made on a method for producing methionine from the viewpoints of improvement in quality, reduction in production cost, and the like (for example, patent documents 1 and 2).

Disclosure of Invention

Problems to be solved by the invention

Methionine as a product was in powder form. However, in the preservation process, methionine may be consolidated, and when consolidation is promoted, a lump of methionine may be formed. If the powdery methionine contains methionine lumps, the handling properties of the product methionine may be impaired. Therefore, in order to prevent the formation of methionine cake, it is required to establish a technique capable of preventing the consolidation of methionine.

In the above-mentioned patent document 1, a technique of drying a wet cake (wet cake) of methionine under mechanical agitation has been studied to solve the problem of providing a method for producing methionine having a high bulk density which is easy to handle. However, patent document 1 does not disclose any technique for preventing the consolidation of methionine.

In the above-mentioned patent document 2, a technique for producing methionine which is advantageous in terms of cost and also advantageous in terms of wastewater treatment has been studied. However, this patent document 2 also does not disclose any technique for preventing the consolidation of methionine.

This presents the following situation: although methionine has been produced for a long time, prevention of solidification of methionine has not been sufficiently studied.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for producing purified methionine and a method for preventing the solidification of methionine, which can prevent the solidification of methionine.

Means for solving the problems

The present inventors have conducted intensive studies on a technique capable of preventing the consolidation of methionine, and have found that methionine to be subjected to drying treatment, i.e., the pH of a wet cake of methionine, is related to the consolidation of methionine, and have completed the present invention. That is, the method for producing purified methionine according to the present invention is a method for producing purified methionine from crude methionine, comprising the steps of:

(1) a step for obtaining a wet cake of water-washed crude methionine;

(2) adjusting the pH of the wet cake; and

(3) a step of drying the wet cake after the pH adjustment,

here, the pH of the wet cake after pH adjustment is 5.2 or more and 6.1 or less.

In this method for producing purified methionine, the wet cake adjusted to a specific pH is subjected to a drying treatment based on the above-mentioned findings concerning prevention of solidification of methionine. In the purified methionine obtained by the production method, solidification can be effectively prevented. This can suppress the formation of lump methionine, and therefore the purified methionine has extremely good handling properties.

In this method for producing purified methionine, the pH of the wet cake after pH adjustment is preferably 5.7 or more, and according to the above constitution, consolidation of purified methionine can be effectively prevented at step .

Further, a method for preventing the consolidation of methionine according to the present invention is a method for preventing the consolidation of methionine, comprising the steps of:

(1) a step for obtaining a wet cake of methionine;

(2) adjusting the pH of the wet cake; and

(3) a step of drying the wet cake after the pH adjustment,

here, the pH of the wet cake after pH adjustment is 5.2 or more and 6.1 or less.

In the method for preventing the consolidation of methionine, the wet cake adjusted to a specific pH is also subjected to a drying treatment. Therefore, in methionine to which the method for preventing consolidation is applied, consolidation can be effectively prevented. This can suppress the formation of lump methionine, and therefore the methionine has extremely good handling properties.

In this method for preventing the consolidation of methionine, the pH of the wet cake after pH adjustment is preferably 5.7 or more, and according to the above configuration, the consolidation of methionine can be effectively prevented at step .

ADVANTAGEOUS EFFECTS OF INVENTION

In the production method of the present invention, purified methionine can be obtained with solidification prevented. In addition, the consolidation of methionine can be prevented by applying the consolidation prevention method of the present invention. That is, the present invention can provide a method for producing purified methionine and a method for preventing the solidification of methionine, which can effectively prevent the solidification of methionine.

Drawings

FIG. 1 is a process diagram showing the flow of steps involved in the process for producing purified methionine according to embodiment of the present invention.

Fig. 2 is a schematic view showing a state where a slurry is charged into an apparatus for performing solid-liquid separation.

Fig. 3 is a schematic diagram showing a process for forming a wet cake in an embodiment of the invention.

Fig. 4 is a schematic view showing a process of adjusting the pH of the wet cake in example 1.

Detailed Description

Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the accompanying drawings as appropriate.

[ Process for producing purified methionine ]

FIG. 1 shows a flow of steps included in a method for producing purified methionine according to embodiment of the present invention, which includes a reaction step 2, a crystallization step 4, a separation step 6, a water washing step 8, an adjustment step 10, and a drying step 12.

In the embodiment of the present invention, a wet cake of water-washed crude methionine described later can be obtained by series of steps from the reaction step 2 to the water washing step 8, and the steps of the reaction step 2, the crystallization step 4, the separation step 6, and the water washing step 8 are not particularly limited, but in this production method, the steps of the reaction step 2, the crystallization step 4, the separation step 6, and the water washing step 8 can be configured to have the same contents as those of the steps in a conventionally known production method.

(reaction step 2)

In the reaction step 2, 5- [2- (methylthio) ethyl ] imidazolidine-2, 4-dione is used as a raw material, and this is hydrolyzed in the presence of a basic compound such as potassium hydroxide, sodium hydroxide, potassium carbonate or potassium hydrogencarbonate. Thus, a reaction solution containing methionine in the form of an alkaline salt was obtained.

In the reaction step 2, the basic compound is used in an amount of usually 2 to 10 moles, preferably 3 to 6 moles, in terms of potassium or sodium, based on 1 mole of 5- [2- (methylthio) ethyl ] imidazolidine-2, 4-dione. The amount of water used is usually set to 2 to 20 times the mass of 5- [2- (methylthio) ethyl ] imidazolidine-2, 4-dione. Usually, the hydrolysis is carried out in a reaction tank (not shown) having a gauge pressure of 0.5 to 1MPa and a temperature of 150 to 200 ℃. The reaction time is usually set in the range of 10 minutes to 24 hours.

(crystallization step 4)

In the crystallization step 4, carbon dioxide is introduced into the reaction solution obtained in the reaction step 2. By the introduction of carbon dioxide, methionine is released from the basic salt of methionine, and methionine is precipitated in the reaction solution. Thus, a slurry containing methionine in the solid content was obtained.

In the crystallization step 4, carbon dioxide is supplied to the reaction tank in which the reaction solution is placed. The gauge pressure in the reaction tank is usually adjusted to 0.1 to 1MPa, preferably 0.2 to 0.5MPa, by the supply of the carbon dioxide. The temperature in the reaction vessel (also referred to as crystallization temperature) is usually set to 0 to 50 ℃, preferably 10 to 30 ℃. The time required for crystallization (also referred to as crystallization time) is generally 30 minutes to 24 hours, based on the time until carbon dioxide is saturated in the reaction solution and methionine is sufficiently precipitated.

(separation step 6)

In the separation step 6, as shown in fig. 2, the slurry 14 obtained in the crystallization step 4 is put into a basket 18 of a centrifuge 16. After the introduction, the basket 18 is rotated to separate the slurry 14 into a solid and a liquid. As a result, as shown in fig. 3, the solid components in the slurry 14 are captured in the basket 18 as agglomerates (wet cake) 20. The liquid component of the slurry 14 is recovered as a filtrate.

The slurry 14 contains impurities such as an alkaline compound used for hydrolysis, a methionine dimer, glycine and alanine generated by decomposition of methionine. Thus, the mass 20 captured in the basket 18 contains this impurity in addition to methionine. In the present invention, methionine in a state in which impurities coexist is crude methionine. Thus, the slurry 14 obtained in the aforementioned reaction step 2 is a slurry of crude methionine, and the aforementioned agglomerates 20 captured in the basket 18 are wet cakes of crude methionine. That is, in the separation step 6, the slurry 14 of crude methionine is subjected to solid-liquid separation to obtain a wet cake 20 of crude methionine.

In the present invention, the solid-liquid separation of the slurry 14 is not limited to the centrifugal separation system. The conditions for solid-liquid separation are preferably set appropriately so that the water content of the wet cake 20 becomes 40 mass% or less.

(washing step 8)

In the water washing step 8, the wet cake 20 obtained in the separation step 6 is washed with water for water washing. Although not shown, in the water washing step 8, water for washing is blown against the wet cake 20 by using a sprayer. Thereby, the entire wet cake 20 is washed with water, and the aforementioned impurities are removed from the wet cake 20. In the present invention, the wet cake with impurities removed 20 is a water-washed wet cake of crude methionine 20w (also referred to as a water-washed wet cake 20 w). That is, in the water washing step 8, a wet cake 20w of water-washed crude methionine is obtained. In the water washing step 8, the temperature of the water for washing is preferably set to be generally within a range of 5 to 35 ℃.

In the present invention, the crude methionine from which impurities are removed is also referred to as pure methionine. That is, the aforementioned wet cake of crude methionine 20w washed with water is a wet cake of pure methionine.

In the present invention, the state in which impurities are removed from the wet cake 20 of crude methionine means a state in which the ratio of the total mass fraction of impurities to 100 mass parts of methionine in the wet cake 20 after water washing (i.e., the water-washed wet cake 20w) is 50% or less of the ratio of the total mass fraction of impurities to 100 mass parts of methionine in the wet cake 20 before water washing.

As described above, when the slurry 14 of crude methionine is subjected to solid-liquid separation, the wet cake 20 can be obtained, and the wet cake obtained by subjecting the wet cake 20 to -step water washing is the wet cake 20w of water-washed crude methionine.

In the water washing step 8, the mass of the water for washing blown to the wet cake 20 of crude methionine is preferably 100g or more and 300g or less with respect to 100g of the mass of the wet cake 20, from the viewpoint of sufficiently removing impurities. The mass of the water for washing is more preferably 150g or more, and still more preferably 250g or less, based on 100g of the mass of the wet cake 20.

As the water for washing, water may be used, or an aqueous solution containing methionine may be used. From the viewpoint of preventing the methionine contained in the wet cake 20 from dissolving in the washing water and improving the yield of methionine in the product, the washing water is preferably an aqueous solution containing methionine. In this case, the concentration of methionine contained in the water for washing is preferably 1.0 mass% or more, and more preferably 2.0 mass% or more. Since the saturated solubility of methionine in water at normal temperature and pressure was 3.0 mass%, the upper limit of the concentration of methionine in the water for washing was 3.0 mass%. That is, the concentration of methionine contained in the water for washing is 3.0 mass% or less.

The water used in the present invention is not particularly limited. Examples of the water include distilled water, pure water, ion-exchanged water, and condensed water of steam.

(adjusting step 10)

In the adjusting step 10, the pH of the wet cake 20w of the water-washed crude methionine is adjusted using pH adjusting water. In the present invention, the wet cake 20w whose pH is adjusted with the pH adjusting water is the wet cake 20p after pH adjustment (also referred to as the adjusted wet cake 20 p).

Although not shown, in the adjustment step 10, it is preferable to adjust the pH of the wet cake 20w by blowing pH-adjusted water onto the water-washed wet cake 20w in a state of being caught in the basket 18 of the centrifuge 16 using a sprayer. The temperature of the pH-adjusted water is usually set to be within a range of 5 to 35 ℃.

In the adjustment step 10, as long as the pH of the entire wet cake 20w can be adjusted, the method of adjusting the pH is not particularly limited, for example, in terms of blowing the pH adjusting water to the wet cake 20 w.

The blowing of the pH-adjusted water to the water-washed wet cake 20w may be performed at any time before the drying step 12 described later. In the production of methionine, a wet cake obtained by solid-liquid separation is usually charged into a dryer through a hopper (not shown). Thus, the pH of the wet filter cake 20w can be adjusted by removing the wet filter cake 20w from the basket 18 and dropping the wet filter cake 20w into a hopper, and then blowing pH adjusting water into the hopper to the wet filter cake 20 w. The pH of the wet cake 20w can be adjusted by blowing pH adjusting water onto the wet cake 20w before the wet cake 20w in the hopper is charged into the dryer. The timing for adjusting the pH of the wet cake 20w may be appropriately determined in consideration of the methionine production rate.

Further, in the present invention, for example, pure methionine wet cake 20w may be put into pH-adjusted water to obtain pure methionine slurry, and the slurry may be subjected to solid-liquid separation in the same manner as in the above-described separation step 6 to obtain pH-adjusted wet cake 20 p.

(drying step 12)

In the drying step 12, the wet cake 20p after pH adjustment can be dried using a conventionally known dryer (not shown). Thus, water is removed to obtain pure methionine in powder form, i.e., purified methionine.

In the drying step 12, the method for drying the wet cake 20p is not particularly limited as long as the purified methionine in a state in which the moisture is sufficiently removed is obtained. The drying step 12 can be configured in the same manner as the drying step in the conventionally known production method. The drying temperature is usually 50 to 150 ℃, preferably 100 to 140 ℃. The drying time is usually 10 minutes to 24 hours, preferably 30 minutes to 2 hours. The state where the water content is sufficiently removed means a state where the water content of the purified methionine is 5 mass% or less.

As described above, the production method of the present invention is a method for producing purified methionine from crude methionine, and in the embodiment thereof, the method generally includes the reaction step 2, the crystallization step 4, the separation step 6, the water washing step 8, the adjustment step 10, and the drying step 12. particularly in the production method of this embodiment, a wet cake 20w of water-washed crude methionine is obtained through the series of steps from the reaction step 2 to the water washing step 8, the pH of the wet cake 20w is adjusted in the adjustment step 10, and then the pH-adjusted wet cake 20p is dried in the drying step 12. that is, the production method includes the steps of:

(1) a step for obtaining a wet cake of water-washed crude methionine (20 w);

(2) a step of adjusting the pH of the wet cake 20 w; and

(3) and a step of drying the wet cake 20p after the pH adjustment.

In this production method, the pH of the water-washed wet cake 20w is adjusted within the range of 5.2 to 6.1 based on the finding that "the pH of the wet cake of methionine subjected to drying treatment is closely related to the consolidation of methionine" found in the study of the technique capable of preventing the consolidation of methionine by the present inventors. In other words, the pH of the pH-adjusted wet cake 20p is 5.2 or more and 6.1 or less. The wet cake 20p after the pH adjustment is subjected to a drying treatment. The purified methionine obtained by the production method can effectively prevent solidification. As a result, formation of lump methionine can be suppressed, and thus the purified methionine has extremely good handling properties.

Furthermore, in this production method, by grasping the pH of the wet cake of methionine 20p to be subjected to drying treatment, the presence or absence of consolidation in the powdery methionine obtained by drying treatment can be predicted. The wet cake 20p may be adjusted in pH 1 time, and in some embodiments, for example, 2 to 5 times (readjustment of pH). Since the reconditioning of the intermediate state of the product can be achieved, high-quality purified methionine can be stably produced. This manufacturing method also contributes to reduction in manufacturing cost.

The pH of the pH-adjusted wet cake 20p is preferably 5.7 or more in terms of more effectively preventing the consolidation of the purified methionine, and the pH of the pH-adjusted wet cake 20p is preferably 5.9 or less in terms of further steps in terms of effectively preventing the consolidation of the purified methionine, and the pH of the pH-adjusted wet cake 20p is particularly preferably 5.7 or more and 5.9 or less.

In the present invention, the pH of the wet cake 20p is represented by the pH of an aqueous solution obtained by dissolving 1.1g of the wet cake 20p in 100mL of water. The pH of the wet cake 20p can be determined as follows. An aqueous solution of methionine was prepared by dissolving 1.1g of the wet cake 20p in 100mL of distilled water. The liquid temperature of the aqueous solution was adjusted to 25 ℃ in a thermostatic bath or the like. The glass electrode of the glass electrode type pH meter was fixed in a state in which a portion having a length of about 3cm from the tip end thereof was immersed in the aqueous solution while the aqueous solution was stirred. After maintaining this state for about 5 minutes, the pH value indicated by the pH meter was confirmed to be stable, and this indicated value, i.e., the pH value, was recorded. The recorded pH value was taken as the pH of the wet cake 20 p. For the measurement of the pH, for example, a glass electrode type pH meter manufactured by HORIBA, ltd. For example, distilled water is used under the trade name "distilled water" manufactured by Wako pure chemical industries, Ltd.

As described above, in the embodiment of the present invention, in the adjustment step 10, the pH adjustment water is blown onto the wet cake 20w of the water-washed crude methionine, whereby pH. for adjusting the wet cake 20w preferably has a mass of 50g or more, preferably 400g or less, based on 100g of the mass of the wet cake 20w, and more preferably 150g or more, more preferably 300g or less, from the viewpoint of effectively preventing the consolidation of methionine.

From the viewpoint of effectively preventing the consolidation of methionine, the pH of the pH-adjusted water is preferably 2 or more, and preferably 5 or less. The pH of the pH-adjusted water is more preferably 2.6 or more, and still more preferably 3.5 or less.

The pH adjusting water used in the adjusting step 10 is not particularly limited. In the adjusting step 10, an aqueous solution of an acid such as sulfuric acid or hydrochloric acid may be used as the pH adjusting water, or an aqueous solution obtained by adjusting the pH of the aqueous solution containing methionine as the water-washing water, that is, an acidic aqueous solution containing methionine, with an acid such as sulfuric acid or hydrochloric acid may be used as the pH adjusting water. From the viewpoint of preventing the dissolution of methionine in the pH-adjusted water and improving the yield of methionine in the product, the pH-adjusted water is preferably an acidic aqueous solution containing methionine. In this case, the concentration of methionine contained in the pH adjusted water is preferably 1.0 mass% or more, and more preferably 2.0 mass% or more. The concentration of methionine contained in the pH adjusted water is preferably 3.0 mass% or less.

Typically, the wet cake of water-washed crude methionine 20w contains water. As described above, when the pH of the wet cake 20w is adjusted so that the pH of the wet cake 20p obtained by the pH adjustment is within a specific range, the consolidation of methionine is prevented.

From the viewpoint of ensuring the purity of methionine and reducing variable costs, the moisture content of the wet cake 20w is preferably 40 mass% or less. Here, the water content of the wet cake 20w can be obtained by a heat drying gravimetric method.

[ method for preventing methionine from being fixed ]

The aforementioned findings that the pH of a wet cake of methionine to which a drying treatment is applied is closely related to the consolidation of methionine may also be applied to a method of preventing the consolidation of methionine. The method for preventing the consolidation of methionine according to the present invention will be described below.

The method for preventing the consolidation of methionine is a method for preventing the consolidation of methionine, and is characterized by comprising the following steps:

(1) a step for obtaining a wet cake of methionine;

(2) adjusting the pH of the wet filter cake; and

(3) a step of drying the wet filter cake after pH adjustment,

here, the pH of the wet cake after pH adjustment is 5.2 or more and 6.1 or less.

In the step of obtaining a wet cake of methionine (also referred to as a wet cake forming step), a slurry containing methionine is prepared, and the slurry is subjected to solid-liquid separation in the same manner as the solid-liquid separation of the slurry 14 in the separation step 6 described above. Thus, a wet cake of methionine was obtained.

In the step of adjusting the pH of the wet cake (also referred to as an adjusting step), the pH of the wet cake is adjusted in the same manner as described in the adjusting step 10 in the above-described production method. Then, in the step of drying the pH-adjusted wet cake (also referred to as a drying step), the pH-adjusted wet cake is dried in the same manner as described for the drying step 12 in the above-described production method. Thus, methionine was obtained in the form of powder.

In this method for preventing consolidation, the pH of the wet cake of methionine to be dried is adjusted to a range of 5.2 to 6.1, in the same manner as in the above-mentioned production method. In other words, the pH of the wet cake after pH adjustment is 5.2 or more and 6.1 or less. That is, in this consolidation prevention method, the wet cake adjusted to a specific pH is also subjected to a drying treatment. Therefore, in methionine to which the method for preventing consolidation is applied, consolidation can be effectively prevented. This can suppress the formation of lump methionine, and therefore the methionine has extremely good handling properties.

In this method for preventing consolidation, the pH of the pH-adjusted wet cake is preferably 5.7 or more in terms of more effectively preventing consolidation of methionine, and the pH of the pH-adjusted wet cake is preferably 5.9 or less in terms of further steps in terms of effectively preventing consolidation of methionine, and the pH of the pH-adjusted wet cake is particularly preferably 5.7 or more and 5.9 or less.

The methionine to be subjected to the consolidation prevention method is preferably methionine from which impurities such as the above-described basic compound are removed, that is, pure methionine, from the viewpoint of effectively preventing consolidation. That is, in the wet cake forming step, a wet cake of pure methionine is prepared, and the conditioning step and the drying step are performed on the wet cake, thereby effectively preventing the consolidation of methionine.

In this case, it is preferable to wash the crude methionine with water to remove impurities and then prepare a wet cake of pure methionine, from the viewpoint of effectively preventing the consolidation.

Further, the solidification prevention method can be applied to methionine (hereinafter, referred to as product methionine) stored as a product. In this case, when impurities have been removed from the product methionine, a slurry of the product methionine can be obtained, and a wet cake of pure methionine can be prepared by solid-liquid separation of the slurry in the same manner as in the separation step 6. In the case where the product methionine contains impurities, from the viewpoint of effective prevention of consolidation, it is preferable to remove the impurities by washing with water and prepare a wet cake of pure methionine in the same manner as in the case of applying the consolidation preventing method of the present invention to crude methionine.

As described above, the consolidation prevention method of the present invention can be applied to methionine in various conditions. In particular, when formation of methionine lumps is confirmed during storage of methionine in a product methionine, the use of the consolidation preventing method can eliminate consolidation of methionine and regenerate high-quality purified methionine.

As is clear from the above description, the production method of the present invention can provide purified methionine in which the solidification is prevented, and the application of the solidification prevention method of the present invention can prevent or eliminate the solidification of methionine. That is, the present invention can provide a method for producing purified methionine and a method for preventing the solidification of methionine, which can prevent (or eliminate) the solidification of methionine.