JP3503115B2 - Method for producing free hydroxylamine aqueous solution - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing free hydroxylamine by reacting hydroxylammonium sulfate with an alkali, in which calcium sulfate as a seed slurry is preliminarily present in the reaction system, and sulfuric acid produced by the reaction is caused. The present invention relates to a method for producing an aqueous solution of free hydroxylamine in which the particle size of salt is increased to improve the filtration efficiency.

[0002]

2. Description of the Related Art Hydroxylamine is industrially used in a wide range of applications such as intermediate raw materials for medical and agricultural chemicals and metal surface treatment agents. Particularly in recent years, as in the field of materials for electron optics, it has been desired to supply a high-purity free hydroxylamine aqueous solution having a smaller metal content.

A recent method for producing free hydroxylamine is a method of reacting hydroxylammonium sulfate with an alkali. The reaction system contains a large amount of sulfate in addition to the desired free hydroxylamine. Becomes Therefore, it is necessary to separate free hydroxylamine and sulfate to obtain a solution of free hydroxylamine with higher purity and higher concentration.

For these applications, it is desirable that the free hydroxylamine is an aqueous solution. In this case, how much salt in the aqueous solution can be removed is a problem. To solve the problem, Usually, since a method of precipitating and separating a salt in an aqueous solution is adopted, the solubility of the salt in water and the particle property of the salt are important factors.

German Patent Publication No. 3528463 discloses that hydroxylammonium sulfate having a low ammonium ion content is reacted with calcium, strontium and barium oxides and / or hydroxides in water to form an alkaline earth metal. A method for obtaining an aqueous solution of free hydroxylamine by separating the sulfate salt thereof has been proposed.
The alkaline earth metal sulphate used here generally has a low solubility in water, so that the crystal grain size is extremely small and it is difficult to perform solid separation. However, German Patent Publication No. 3528463 The publication does not show any solution to this, and it cannot be said that this is an industrial method. In addition to crystallization, no attempt has been made to separate sulfates, and the resulting aqueous solution contains sulfates having a solubility. By the way, in the hydroxylammonium sulfate used in this reaction, in order to reduce the content of ammonium ions such as ammonium sulfate in advance, it is necessary to perform the operation of crystallizing the starting aqueous solution of hydroxylammonium sulfate several times. Furthermore, since strontium compounds and barium compounds are relatively expensive and highly toxic, they cannot be said to be the optimum method in industrial production.

[0006]

The object of the present invention is to allow calcium sulfate as a seed slurry to be present in the reaction system in advance when reacting hydroxylammonium sulfate with calcium oxide and / or calcium hydroxide. Then, it is another object of the present invention to provide a method for producing an aqueous solution of free hydroxylamine in which the particle size of the sulfate generated in the reaction is increased to improve the filtration efficiency.

[0007]

The method for producing an aqueous solution of free hydroxylamine according to the present invention is a method for producing free hydroxylamine by reacting an aqueous solution containing hydroxylammonium sulfate with a slurry of calcium oxide and / or calcium hydroxide. The method for producing an aqueous solution of free hydroxylamine in which the reaction is carried out in the state that calcium sulfate as a seed slurry is always present in the reaction system.

In the present invention, in the method for obtaining free hydroxylamine by the reaction of mixing an aqueous solution containing hydroxylammonium sulfate with a slurry of calcium oxide and / or calcium hydroxide, calcium sulfate as a seed slurry is always in the system. The reaction is carried out in the state of being present in the solution to increase the particle size of the sulfate produced in the reaction. That is, since the sulfate containing calcium sulfate generated by the reaction grows as a seed crystal of calcium sulfate added in advance, crystals with a higher particle size can be obtained, and the separation from the aqueous solution containing free hydroxylamine by filtration is efficiently performed. You can do it well. Therefore, this simplifies the subsequent distillation operation of the aqueous solution containing free hydroxylamine.

In the present invention, when the reaction is carried out batchwise, calcium sulfate as a seed slurry is mixed in advance with an aqueous solution containing hydroxylammonium sulfate and / or a slurry of calcium oxide and / or calcium hydroxide. As a preferred embodiment, when carrying out the reaction continuously, it is preferable to use calcium sulfate generated by the reaction as a seed slurry and to add a stabilizer to the system containing free hydroxylamine in order to prevent decomposition of free hydroxylamine. include.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a process for synthesizing an aqueous solution of free hydroxylamine, wherein free hydroxylamine is prepared by a reaction of mixing an aqueous solution containing hydroxylammonium sulfate with a slurry of calcium oxide and / or calcium hydroxide. In the method of obtaining, in order to synthesize the free hydroxylamine aqueous solution efficiently and safely, it is preferable to carry out under the following conditions.

The mixing ratio of hydroxylammonium sulfate and calcium oxide and / or calcium hydroxide used in the present invention is stoichiometrically: 1 mol of hydroxylammonium sulfate and 2 mol of calcium oxide and / or calcium hydroxide. However, as described below, it is desirable to control the mixing reaction at pH in order to prevent the decomposition reaction of free hydroxylamine under alkaline conditions.

Since the reaction between hydroxylammonium sulfate and calcium oxide and / or calcium hydroxide in the present invention is accompanied by heat generation, temperature control is required for safety and disaster prevention. Specifically, the reaction temperature of hydroxylammonium sulfate with calcium oxide and / or calcium hydroxide is preferably 60 ° C. or lower, and more preferably 40 ° C. or lower. A particularly practical and suitable temperature range is 20 to 40 ° C.

The above reaction is usually carried out in a facility equipped with a pH meter to reach a pH of weak alkaline conditions, especially pH 9.0.
It is desirable to stop at ~ 9.2. Since the alkali does not become excessive in the range up to pH 9.2, it is possible to suppress the decomposition reaction of free hydroxylamine under alkaline conditions and also to suppress the generation of fine sulfate. After the reaction, a liquid consisting of free hydroxylamine and the remaining sulfate containing hydroxylammonium sulfate is obtained.

When the mixing operation of hydroxylammonium sulfate and calcium oxide and / or calcium hydroxide is continuously carried out, the calcium sulfate produced in the reaction is often separated and removed continuously, but in the reaction tank, It is important that calcium sulfate is always present.

The particle size of calcium sulfate needs to be large enough to facilitate centrifugation, but for this purpose, a certain amount of calcium sulfate concentration is required in the system,
The slurry concentration of calcium sulfate is 5 of the total weight of the reaction system.
It is desirable to make it more than%. The slurry concentration of calcium sulfate is preferably 5 to 20%. By allowing the seed slurry to always be present in the reaction system in this way, the particle size of the sulfate generated from the reaction can be 50 to 100 μm.

In addition, the reaction of hydroxylammonium sulfate with calcium oxide and / or calcium hydroxide is carried out batchwise or continuously, the seed slurry is the dihydrate of calcium sulfate obtained by this reaction or It is desirable to separate and recycle the reaction slurry itself.

When the reaction of hydroxylammonium sulfate with calcium oxide and / or calcium hydroxide is carried out in a batch system, calcium sulfate as a seed slurry to be mixed is an aqueous solution containing hydroxylammonium sulfate before the reaction or an oxidation. It may be mixed with either a slurry of calcium and / or calcium hydroxide, or may be mixed with both.

When calcium hydroxide or calcium oxide is used, the solubility of calcium sulfate dihydrate obtained by the reaction in water is small and most of it precipitates in water. Therefore, sulfate in solution before simple distillation is used. The concentration can be reduced to 1 wt% or less by the operation of only separation, which is particularly advantageous for the present invention.

In order to increase the concentration of hydroxylamine in the aqueous solution after the reaction, it is preferable that a small amount of water is used as a reaction solvent, and calcium sulfate having a low solubility in water is
Similarly, it is preferably added to an aqueous solution containing hydroxylammonium sulfate having a high solubility in water, rather than being added to a slurry of calcium oxide and / or calcium hydroxide having a low solubility.

In the present invention, the filtration of sulfate is efficiently performed by centrifugal filtration. The hydroxylamine adhering to the sulfate is washed by a reslurry washing method or a cake washing method performed in a centrifuge, and the washing liquid is also collected.

During the reaction of hydroxylammonium sulfate with calcium oxide and / or calcium hydroxide, the addition of a stabilizer for free hydroxylamine improves the reaction yield. Also, after obtaining a reaction solution containing free hydroxylamine from the reaction, a stabilizer of free hydroxylamine is added, and thereafter, a distillation operation for obtaining free hydroxylamine is carried out,
It is preferable for improving the yield of the process and for safely operating the process, since the decomposition of free hydroxylamine can be prevented.

As the stabilizer for free hydroxylamine, an alcohol compound having a boiling point higher than that of free hydroxylamine is preferably used. 2-Hydroxyethyl disulfide and 1,4-dimercapto-2,3-butanediol are particularly effective as the alcohol compound. The preferred addition amount of the alcohol compound as a free hydroxylamine stabilizer depends on the amount of heavy metal ions in the reaction product before the reaction. Usually, it is preferable to add an equivalent amount or more of the heavy metal ion content, but it is preferable to add it at 2 times or more.

The free hydroxylamine aqueous solution of the present invention is preferably used in the fields of intermediate raw materials for medicines and agricultural chemicals, metal surface treatment agents, materials for electron optics and the like.

[0024]

Example 1 A 2 L four-necked flask equipped with a reflux condenser, a dropping port, a pH meter with a thermometer, and a stirrer was used to obtain the previous reaction between hydroxylammonium sulfate and calcium hydroxide. 221.4 g of the obtained sulfate cake and 472 g of water were added. Next, 234.5 g of commercially available powdered hydroxylammonium sulfate and water 23
4.5 g was added, and 8-hydroxyquinoline was added as a chelate-forming stabilizer in an amount of about 0.0006 mol per mol of hydroxylammonium sulfate. On the other hand, 110g calcium hydroxide and water 6 in a 1L beaker
After charging with 75 g, one end of a microtube attached to a roller pump was immersed in this, and the other end was passed through the neck of a 1 L four-necked flask. Under stirring in a four-necked flask, the calcium hydroxide slurry was fed at 25 to 30 ° C. until the pH reached 9.2. After the aging time of 15 minutes, the slurry containing the precipitated solid calcium sulfate was filtered using a fine chemical filter and a Whatman glass filter (1.2 μm). At this time, the time required for the amount of the filtrate obtained by separating from the sulfate containing calcium sulfate to reach 200 ml was measured and found to be 50 seconds. The separated cake was filtered and washed with 100 g of water. The 1,478 g of filtrate combined with the wash liquor contained 92.0 g of free hydroxylamine.
0.2 g of free hydroxylamine was attached to the cake after washing. This cake is mixed with the starting material for the next reaction and used as a seed crystal. This means that a total of 92.2 g of free hydroxylamine was produced for 94.4 g of hydroxylamine content in the raw material hydroxylammonium sulfate.

When the same operation was carried out without mixing the sulfate cake during the reaction of hydroxylammonium sulfate and calcium hydroxide, it took 370 seconds to obtain 200 ml of the filtrate in the filtration operation by the fine chemical filter. Needed

(Example 2) 110 g of calcium hydroxide and 675 g of water used in Example 1 were mixed with calcium oxide 83
The same result could be obtained by performing the same operation as in Example 1 except that g and water 702 g were used instead. 75.5 g of calcium hydroxide per 100 g
The same results as in Example 1 can be obtained even if the calcium oxide of 2 is replaced with 24.5 g of water.

[0027]

According to the present invention, in a method for obtaining free hydroxylamine from a reaction of mixing an aqueous solution containing hydroxylammonium sulfate with a slurry of calcium oxide and / or calcium hydroxide, sulfuric acid as a seed slurry is used. Keeping calcium always present in the reaction system increases the particle size of the sulfate generated in the reaction to improve the filtration efficiency, and lowers the sulfate concentration of the aqueous solution containing free hydroxylamine obtained as the filtrate. Became possible. This facilitated the subsequent distillation operation.

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP 2001-261312 (JP, A) JP 2000-211906 (JP, A) JP 2000-211905 (JP, A) JP 62-216908 (JP , A) JP-A-62-171905 (JP, A) Special table 2002-504062 (JP, A) Special table 2001-522345 (JP, A) Special table 2001-513479 (JP, A) Special table 2000-505033 ( JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C01B 21/14

Claims (4)

(57) [Claims] 1. A method for producing free hydroxylamine by reacting an aqueous solution containing hydroxylammonium sulfate with a slurry of calcium oxide and / or calcium hydroxide, wherein calcium sulfate as a seed slurry is always present in the reaction system. A method for producing an aqueous solution of free hydroxylamine in which the reaction is carried out in the presence of the free hydroxylamine. 2. When the reaction between the aqueous solution containing hydroxylammonium sulfate according to claim 1 and the slurry of calcium oxide and / or calcium hydroxide is carried out in a batch system, calcium sulfate as a seed slurry is converted into hydroxylammonium sulfate. The method for producing an aqueous solution of free hydroxylamine according to claim 1, wherein the aqueous solution containing calcium hydroxide and / or the slurry of calcium oxide and / or calcium hydroxide is mixed in advance. 3. The calcium sulfate produced by the reaction when the mixed reaction of the aqueous solution containing hydroxylammonium sulfate and the slurry of calcium oxide and / or calcium hydroxide is continuously carried out is used as the seed slurry. The method for producing a free hydroxylamine aqueous solution. 4. The method for producing an aqueous solution of free hydroxylamine according to claim 1, wherein a stabilizer is added to the system containing free hydroxylamine.