JPH0226619B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for selectively extracting ethyleneamines and separating them from inorganic chlorides from an aqueous solution containing ethyleneamines and inorganic chlorides such as ammonium chloride, sodium chloride, or calcium chloride. More specifically, monohydrochloric acid of ethylene amines including ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, etc. obtained by the reaction of dichloroethane and aqueous ammonia solution, and chain/cyclic amines such as piperazine. salt, and a reaction product liquid containing ammonia and ammonium chloride,
Alternatively, from an aqueous solution containing free ethyleneamines and chlorides such as sodium chloride or calcium chloride obtained by adding sodium hydroxide, calcium hydroxide, etc. to the reaction product liquid, ethyleneamines can be efficiently purified using benzyl alcohol. It relates to a method for extracting into an organic phase and separating it from inorganic chlorides. Currently, separation of ethylene amines (EA) and inorganic chlorides is possible through the reaction of ethane dichloride with aqueous ammonia solution, since the inorganic chlorides produced are extremely stable and have alkaline strength that can produce free amines. The product is made caustic by the action of sodium hydroxide according to the following formula, EA・HCl + NH ₄ Cl + 2NaOH → EA + NH ₃ + 2NaCl + 2H ₂ O After removing free ammonia, crystallize sodium chloride by evaporation and concentration. A method has been adopted to recover ethyleneamines. In other words, ammonia has low alkaline strength and does not have the ability to convert monohydrochloride of ethyleneamines into free ethyleneamines.When calcium hydroxide is used, it is difficult to evaporate and concentrate to crystallize and separate by-product calcium chloride. , at high temperatures, a reverse reaction occurs as shown in the following equation, 2EA + CaCl ₂ + 2H ₂ O→ 2EA・HCl + Ca(OH) ₂ ↓ As ethyleneamines cannot be recovered, the use of sodium hydroxide is essential. . The current methods for separating ethyleneamines and inorganic chlorides are as follows: 1) A large amount of expensive sodium hydroxide is required. 2) In order to separate the by-product sodium chloride, all of the large amount of water required during the reaction must be removed by evaporation, which requires a large amount of thermal energy. 3) Efficient separation of sodium chloride requires complex operations and expensive equipment for crystallization and separation. It has problems such as: In light of the above circumstances, the present inventors have conducted intensive studies to establish a method for separating ethyleneamines and inorganic chlorides that solves the above problems. As a result, the use of benzyl alcohol allows ethyleneamines to be separated from the organic phase very efficiently. The present invention was achieved based on the completely unexpected discovery that That is, in the present invention, ethylene is extracted from an aqueous solution containing ethylene amines and an inorganic chloride using benzyl alcohol or a mixed solvent consisting of benzyl alcohol and an aliphatic alcohol having 3 to 8 carbon atoms and/or an organic solvent having a ketone group. This is a method for separating ethylene amines and inorganic chlorides, which is characterized by selectively extracting amines into an organic phase. The present invention will be explained in more detail below. As mentioned above, ethyleneamines in the present invention is a general term for various amines produced using ethylenediamine as a unit, and the number of carbon-carbon bonds in the molecules of these ethyleneamines gives organophilicity. Since they contain a high proportion of extremely hydrophilic amino groups, ethyleneamines as a whole have strong hydrophilic properties and cannot be extracted into the organic phase with various general organic solvents. However, when benzyl alcohol is used, ethyleneamines can be efficiently extracted into the organic phase. The mechanism behind why benzyl alcohol can efficiently extract ethyleneamines is unknown, but judging from the properties of ethyleneamines, benzyl alcohol reacts with the amino groups of ethyleneamines to form adducts. Alternatively, by acting on the amino group, the amino group of ethylene amines is inactivated, and as a result, the hydrophilicity due to the amino group is lost, making the whole organophilic (hereinafter referred to as organic solvent phase). )
It is presumed that this was to become Although it is essential for the present invention to use benzyl alcohol for the above reasons, there are no particular limitations on the manner in which it is used. That is, the amount of benzyl alcohol necessary for the ethyleneamine to become organophilic, in other words, it varies somewhat depending on the composition of the ethyleneamine, but is preferably at least 0.3 times the amino group of the ethyleneamine. 0.5 mole or more of benzyl alcohol may be used. The solvent for forming the organic phase and extracting ethyleneamines is not limited to benzyl alcohol alone, but can be used in combination with various organic solvents. The solvents that can be used are those that can form an organic phase and do not react with benzyl alcohol.In particular, aliphatic solvents having 3 to 8 carbon atoms in the molecule are suitable for extractability, phase separation, ease of handling, price, etc. Alcohol is preferred. For example, benzyl alcohol/n-butanol, benzyl alcohol/i-amyl alcohol, etc. are used, and the benzyl alcohol in the mixed solvent is 5 to 80% by volume.
is common. Further, as long as the raw materials are aqueous solutions containing ethyleneamines and inorganic chlorides, the present invention does not limit the formation conditions, concentrations, component ratios, etc. of these aqueous solutions; however, the embodiment in which the present invention can be most advantageously used is ,
A mixed aqueous solution of ethylene amines, monohydrochloride, ammonia, and ammonium chloride produced by the reaction of ethane dioxide and aqueous ammonia solution, or ethylene amines/chloride obtained by reacting the mixed aqueous solution with sodium hydroxide, calcium hydroxide, etc. It is a mixed aqueous solution of sodium or calcium chloride. Ethyleneamines in the aqueous solution obtained by causticizing with sodium hydroxide, calcium hydroxide, etc. are in a free state, so naturally the ethyleneamines extracted into the organic phase are also extracted in a free state, but the reaction products Ethyleneamines extracted into the organic phase from a mixed aqueous solution of ethyleneamine monohydrochloride, ammonia, and ammonium chloride are in a free state. The reason for this is still speculation, but due to the interaction between the amino groups of ethyleneamine monohydrochloride that are not bonded to hydrochloric acid and benzyl alcohol, the alkaline strength is lower than that of ammonia, and as a result, ammonia It is thought that free ethyleneamines are extracted because dehydrochlorination is achieved. One of the features of the present invention is that ethyleneamines can be selectively separated without causticization. The extractability of ethyleneamines in the method of the present invention is expressed by the distribution coefficient expressed as the concentration ratio of (organic phase)/(aqueous phase). Although it varies depending on the ratio of inorganic chlorides, etc., a value of at least 0.5 and usually 1 to 3 can be obtained. The factor that most influences this partition coefficient is the type of inorganic chloride, and especially when the coexisting salt is calcium chloride, the extractability of ethyleneamines is inferior to other salts. Water coordinates with Ca ²⁺ ions to form aqua ions that have weak acid properties, and the interaction between these aqua ions and ethyleneamines, which are bases, reduces extractability into the organic phase. It is thought that then. Therefore, in a system where calcium chloride coexists, if ammonia is coexisting to remove the influence of the above aqua ions, the extractability of ethyleneamines will be 2 to 6.
Therefore, it is preferable to perform the extraction without removing ammonia from the solution causticized with calcium hydroxide. Further, in order to further improve the extractability of ethyleneamine, it is preferable to use an organic solvent having a ketone group, such as acetone, methyl ethyl ketone, cyclohexanone, cyclopentanone, etc., in combination with benzyl alcohol. The present inventors have already proposed that the above-mentioned organic solvent containing a ketone group is a solvent that can selectively extract ethyleneamines even when used alone. (Special Application No. 57-94952). However, compared to using a mixed solvent and benzyl alcohol or an organic solvent having a ketone group alone,
Although the mechanism is not completely clear, the extractability for ethyleneamines is further improved, so this is one of the more preferred embodiments of the present invention. In the method of the present invention, as mentioned above, ethyleneamines can be extracted extremely efficiently. For example, if the extraction solvent is used 2 to 10 times the volume of the raw material aqueous solution and brought into countercurrent contact with the number of extraction stages from 3 to 10, Substantially all ethyleneamines contained in the raw material can be extracted. The distribution coefficient of chloride coexisting in the raw material is extremely small, at most 0.1, but usually 0.02 or less, and the amount of chloride extracted into the organic phase together with ethyleneamines is extremely small. This co-extracted chloride also
The extracted phase can be easily removed from the organic phase by simply contacting it with a small amount of water or a small amount of an aqueous solution of ethyleneamines. There is no particular limitation on the method for recovering ethyleneamines from the organic phase containing ethyleneamines thus obtained. For example, a method in which the ethyleneamines are recovered as an aqueous solution by contacting them with pure water, a method in which the ethyleneamines are recovered by distilling the organic phase, etc. can be employed, but the most preferred method is a method using an acid. That is, this method involves bringing an organic phase into contact with an acid aqueous solution to produce salts of ethyleneamines.This method involves contacting an organic phase with an aqueous acid solution to produce salts of ethyleneamines. This is because it can be recovered as an aqueous salt solution. For example, an aqueous solution having a concentration of ethyleneamines of 200g/or more, usually 300g/or more, can be easily recovered from an aqueous solution of 100g/or more. If the final target is a salt of ethyleneamines, select an acid that forms the target salt; if the target is free ethyleneamines, use carbon dioxide gas or carbonated water as the acid. The method is preferred. In this case, ethyleneamines are recovered as a carbonate aqueous solution, but this carbonate is
It thermally decomposes at a temperature of around 100℃ and releases carbon dioxide gas,
Since free ethyleneamines are produced, free ethyleneamines can be easily recovered. As is clear from the above explanation, the method of the present invention: 1. Does not particularly require expensive sodium hydroxide;
Inexpensive alkalis such as calcium hydroxide and magnesium hydroxide can be used. 2 Ethylene amines can be concentrated 2 to 5 times during the extraction operation, which is extremely energy-saving. 3. Since crystallization and separation are not required, complicated operations and expensive equipment are not required. It solves the problems of conventional methods, such as, and is extremely superior industrially. The present invention will be further explained below with reference to Examples, but the present invention is not limited to these Examples. Examples 1 to 4 200 ml of benzyl alcohol was added to 200 ml of an aqueous solution containing 20.0 g of ethylene amines and 40.0 g of sodium chloride (NaCl), and after shaking for 10 minutes, static separation was performed to obtain the following results. In addition, NaCl in the organic phase
In all cases, the amount was 1 g/or less.

[Table] Example 5 200 ml of an n-butanol mixture containing 130 ml of benzyl alcohol was added to 200 ml of an aqueous solution of TETA: 100 g/, NaCl: 200 g/, and after shaking for 10 minutes,
Separated statically. As a result, TETA: 53.8g/, NaCl: 0.5
g/230ml of organic phase and TETA: 44.8g/,
170 ml of an aqueous phase containing 235 g of NaCl was obtained. Next, 15 ml of pure water was added to 150 ml of the organic phase, water-saturated carbon dioxide gas was blown in at a rate of 100 ml/min for 2 hours, static separation was performed, and the entire amount of TETA was back-extracted into the aqueous phase as carbonate. Furthermore, 15 ml of the aqueous phase obtained by back extraction was thermally decomposed in the same manner as in the reference example, and TETA: 355 g/,
CO ₂ :32 g/aqueous solution was obtained. Example 6 Aqueous solution of EDA: 90g/, _CaCl2 : 111g/
Add 200 ml of cyclohexanone mixture containing 133 ml of benzyl alcohol to 200 ml and shake for 10 minutes.
Separated statically. As a result, EDA: 61.8g/, _CaCl2 : 0.4g/
222ml of organic phase and EDA: 24.0g/, _CaCl2 :
178 ml of 124 g/aqueous phase was obtained. Example 7 EDA: 90g/, CaCl ₂ : 170g/, NH ₃ :
Add benzyl alcohol to 200ml of 170g/aqueous solution.
200 ml of a cyclohexanone mixture containing 133 ml was added, shaken for 10 minutes, and then statically separated. As a result, 240 ml of organic phase with EDA: 66.9 g/
EDA: 12.2g/, CaCl ₂ : 210g/, NH ₃ :
160 ml of 185 g/aqueous phase was obtained. Example 8 200 ml of a cyclohexanone mixture containing 133 ml of benzyl alcohol was added to 200 ml of an aqueous solution of 145 g of EDA/HCl and 170 g of NH ₃ , and after shaking for 10 minutes, static separation was performed. As a result, 224 ml of organic phase with EDA: 64.9 g/
EDA: 19.7g/, HCl: 61.1g/, _NH3 :
171 g/176 ml of aqueous phase were obtained. Example 9 EDA: 65 obtained by adding 50% calcium hydroxide cake to the reaction aqueous solution obtained by the reaction of ethane dichloride (EDC) and ammonia aqueous solution
g/, DETA: 28g/, TETA: 16g/,
TEPA: 6.0g/, Pentaethylenehexamine (PEHA): 4.0g/, N-aminoethylpiperazine (N-AEP): 4.0g/, CaCI ₂ : 176g/
, cyclohexanone mixture containing 133 ml of benzyl alcohol in 200 ml of an aqueous solution of 108 g/NH ₃
After adding 200 ml and shaking for 10 minutes, static separation was performed. As a result, EDA: 47.2g/, DETA: 18.4
g/, TETA: 10.5g/, TEPA: 3.8g/
240 ml of an organic phase containing 2.5 g/PEHA and 2.2 g/N-AEP was obtained. Example 10 For an aqueous solution of EDA: 90 g/, CaCl ₂ : 111 g/, twice the volume of a mixed solvent of benzyl alcohol and cyclohexanone (2:1 (volume ratio)) was used,
A three-stage countercurrent multi-stage extraction was performed. As a result, the extraction rate of EDA into the organic phase was 99% or more, and the extraction rate of calcium chloride was 1.0%. Next, add 10ml of water to 100ml of the organic phase from which EDA was extracted.
In addition, after shaking for 10 minutes, static separation was performed, and no calcium chloride was present in the organic phase, which could be completely removed. Reference example 15 ml of pure water was added to 180 ml of the organic phase obtained in Example 1, and water-saturated carbon dioxide gas was blown in at a rate of 100 ml/min for 2 hours for static separation, and the entire amount of EDA was converted into carbonate and added to the aqueous phase. Back extracted. Next, 15 ml of the aqueous phase was put into a 50 ml three-necked round bottom flask equipped with a condenser, heated with a mantle heater, and the EDA carbonate was thermally decomposed at the boiling point by a total reflux method for 2 hours. 335g/,
An aqueous solution containing 50 g of CO ₂ was obtained.

Claims (1)

[Claims] 1. Benzyl alcohol or benzyl alcohol and aliphatic alcohol having 3 to 8 carbon atoms and/or benzyl alcohol from an aqueous solution containing ethylene amines and inorganic chlorides.
Alternatively, a method for separating ethyleneamines and chlorides, which comprises selectively extracting ethyleneamines into an organic phase using a mixed solvent with an organic solvent having a ketone group. 2. The method according to claim 1, wherein the benzyl alcohol is used in an amount of 0.3 times or more by mole relative to the amino group of the ethyleneamine.