JPH0471904B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention enables the production of ethyleneamines from an aqueous solution containing ethyleneamines.
This invention relates to a method for separating ethyleneamines by an extraction method. In the present invention, ethyleneamines include chain-like ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, tris-(2-aminoethyl)-amine, piperazine, N-aminoethylpiperazine, etc. , means a single amine or a mixture of amines including cyclic ethylene amines. The EDC method is one method for producing ethylene amines. The method uses ethylene dichloride (EDC)
In this method, an aqueous ammonia solution is reacted with an aqueous ammonia solution at high temperature and pressure to obtain an aqueous hydrochloride solution of ethyleneamines. In order to separate ethyleneamines from this reaction solution, sodium hydroxide was added to the solution to metathesize the hydrochloride and ammonium chloride of ethyleneamines, and then the free ammonia was recovered by heating, and then evaporated and concentrated to convert it into chloride. There is a method to obtain ethyleneamines by crystallizing and separating sodium. However, in this method, all of the large amount of water used in the reaction must be evaporated and separated, requiring a large amount of energy, and in order to efficiently separate sodium chloride from ethylene amines, complicated and expensive equipment and equipment are required. It has problems such as requiring advanced operations. As a method for solving these problems, there is a method of extracting and separating ethylene amines using an organic solvent. For example, using a monopolar organic solvent,
A method has been proposed for extracting ethylene amines from an aqueous solution containing ethylene amines having a sodium hydroxide concentration of 45% by weight. However, this method requires the addition of extremely large amounts of sodium hydroxide, the aqueous phase containing a high concentration of sodium hydroxide must be reused, the method is complex, and special conditions are required. There are problems such as having to form a As a result of intensive studies aimed at establishing a more economical and efficient method for separating ethyleneamines, the present inventors found that when extracting ethyleneamines using alcohol, the presence of ammonia makes it extremely efficient. The present invention was completed by discovering new knowledge that ethyleneamines can be extracted. That is, the present invention is a method for separating ethyleneamines, which is characterized by selectively extracting ethyleneamines from an aqueous solution containing ethyleneamines into an alcohol phase in the presence of ammonia using alcohol. . In the method of the present invention, ethylene amines are extracted from an aqueous solution containing ethylene amines, and a large amount of water can be removed as an extraction residue, so compared to conventional methods, an extremely large amount of energy can be saved, and ethylene amines can be extracted from an aqueous solution containing ethylene amines. There is no need to separate amines and sodium chloride crystals. Furthermore, since volatile ammonia is used, its recovery is extremely easy. The present invention will be explained in more detail below. The present invention requires that amines be extracted using alcohol in the presence of ammonia. Although it is possible to extract ethyleneamines with alcohol, the extraction efficiency is poor and it is not practical. However, the presence of ammonia improved the extractability and enabled efficient separation of ethyleneamines. Although it is not possible to clearly explain the reason for this,
Ammonia is extremely hydrophilic compared to ethylene amines, with the exception that it is more concentrated in the aqueous phase.
Its physical properties are similar to ethyleneamines. Therefore, it is surmised that the presence of ammonia increases the concentration of ethyleneamines in the aqueous phase, improving the extractability of ethyleneamines. Lower alcohols are more effective in extracting ethyleneamines. However, in this case, the solubility of the alcohol in the aqueous phase increases, and in some cases, it becomes one phase. Higher alcohols solve these problems, but the extractability decreases.
From the above, it is desirable that the alcohol has 3 to 6 carbon atoms. Specifically, n-propyl alcohol, isopropyl alcohol, n-propyl alcohol,
-butyl alcohol, isobutyl alcohol,
These include sec-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, cyclohexanol, and the like. Moreover, one type of alcohol or a mixture of two or more types may be used, and ethers and hydrocarbons may be partially mixed with alcohol as other organic solvents. It should be noted that the higher the ammonia concentration in the aqueous phase during extraction, the better for extracting ethyleneamines, and 50 g/
The above is desirable. In addition, pressurization is required to maintain the ammonia concentration in the aqueous phase at a significantly high level.
Also, when recovering ammonia from the extraction residue, a lot of energy is consumed, so it is desirable to keep the amount to 300 g/or less. Furthermore, ammonia may be present in an aqueous solution containing ethyleneamines or in alcohol before extraction. Furthermore, it may be present in both. In this case, it is preferable because the ammonia concentration in the aqueous phase during extraction can be made higher at room temperature and normal pressure. There are no particular restrictions on the aqueous solution containing ethyleneamines, but it is usually a reaction solution obtained by the EDC method, especially an aqueous solution obtained by adding an alkali hydroxide such as sodium hydroxide or calcium hydroxide to the reaction solution. will be targeted. The ammonia liberated at this time may be removed before extraction and reused for the reaction with EDC, or may be left as is for extraction. When calcium hydroxide is added, an aqueous solution of ethyleneamines and calcium chloride is formed, but in this case the effect of the presence of ammonia on extractability becomes even greater. The reason for this is inferred as follows.
That is, ethyleneamines form a complex with calcium chloride in an aqueous solution, and therefore the extractability of ethyleneamines is low. However, it is believed that when ammonia is added, the ammonia forms a complex with calcium chloride, and ethyleneamines become free, improving extractability. There are no particular restrictions on the extraction conditions or extraction equipment, and any extraction equipment can be conveniently used at room temperature and normal pressure. Further, there are no particular restrictions on the extraction method, but countercurrent multi-stage extraction is effective. The alcohol phase obtained by extraction contains ammonia in addition to ethyleneamines, and a very small amount of inorganic salts when the extraction operation is performed in the coexistence of inorganic salts. However, the inorganic salts can be almost completely removed by washing the alcohol phase with a very small amount of water. Since the washing liquid contains a small amount of ethyleneamines, it is preferable to circulate it to the previous extraction step. Ammonia can be easily removed and recovered by heating the alcohol phase, and can be recycled for use in the extraction process. An alcohol phase free of ammonia and inorganic salts is thus obtained. Ethylene amines in the alcohol phase can be separated and recovered by distillation depending on the type of alcohol used, but it is more efficient to back-extract them with water. It is effective to extract it.
As the acid, both organic acids and inorganic acids can be used, but inorganic acids are preferred, and carbonic acid and carbon dioxide gas are particularly preferred. When carbonic acid or carbon dioxide gas is used, a concentrated aqueous solution of carbonate of ethyleneamines is obtained. The carbonate aqueous solution of ethyleneamines becomes an aqueous solution of ethyleneamines and carbon dioxide gas by heating. It is economical to reuse the carbon dioxide gas in the previous back extraction step. As described above, ethyleneamines are separated from an aqueous solution containing ethyleneamines. Note that the aqueous phase from which ethyleneamines are extracted, that is, the extraction residue, contains alcohol and ammonia corresponding to the solubility. These can be easily recovered by distilling the extraction residue and can be recycled for use in the extraction process. As is clear from the above detailed description, the method of the present invention has the following characteristics. (1) Ethylene amines can be separated and recovered from a dilute aqueous solution of ethylene amines without consuming a large amount of thermal energy, and the dilute aqueous solution of ethylene amines can be effectively concentrated. (2) It does not require complicated operations or equipment unlike conventional methods. (3) Since the method of the present invention is operated under relatively mild conditions, thermal deterioration of ethyleneamines is greatly reduced. The present invention will be explained below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Examples 1-2, Comparative Examples 1-2 Ethylene amines 6.0g, sodium chloride 15.0
g and aqueous solution containing 15.0 g of ammonia (NH ₃ )
100 ml of n-butanol was added to 100 ml, and after shaking for 10 minutes, static separation was performed to obtain the following results. For comparison, an aqueous solution containing 6.0 g of ethylene amines and 15.0 g of sodium chloride was operated in the same manner as in Example 1 to obtain the following results.

[Table] Example 3, Comparative Example 3 100 ml of n-butanol was added to 100 ml of an aqueous solution containing 9.0 g of TETA, 15.0 g of calcium chloride, and 13.0 g of ammonia (NH ₃ ), and the following results were obtained by performing the same procedure as in Example 1. I got it. Also, for comparison, TETA6.0g, calcium chloride
An aqueous solution containing 15.0 g was operated in the same manner as in Example 3 to obtain the following results.

[Table] Example 4 EDA 90g/, Sodium chloride 170g/,
An aqueous solution of 180 g of NH ₃ was subjected to 7 stages of countercurrent extraction using 5 times the volume of a solvent prepared by adding 150 ml of aqueous ammonia of 230 g to n-butanol. As a result, EDA17g/, NaCl2.5g/,
An alcohol phase containing 36 g of NH ₃ was obtained, and the extraction rate of EDA was 98%. Next, 50 ml of water was added to 1000 ml of the alcohol phase from which EDA had been extracted, and after shaking for 10 minutes, static separation was performed to obtain an alcohol phase substantially free of sodium chloride. Furthermore, the alcohol phase after removing ammonia by distilling the alcohol phase from which sodium chloride has been removed
Add 10ml of water to 200ml to make 100ml of water-saturated carbon dioxide.
When back-extracted by introducing at ml/min for 30 days,
EDA can be almost completely back-extracted, and 200
g/g of an aqueous solution of ethylenediamine carbonate was obtained.

Claims (1)

[Claims] 1. A method for separating ethyleneamines, which comprises selectively extracting ethyleneamines from an aqueous solution containing ethyleneamines into an alcohol phase in the presence of ammonia using alcohol. . 2 During extraction, reduce the ammonia concentration in the aqueous phase to 50g/
The method according to claim 1, wherein the method is as described above. 3. The method according to claim 1 or 2, wherein the alcohol is an alcohol having 3 to 6 carbon atoms.