JPH0229069B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a method for selectively extracting ethyleneamines into an organic phase from an aqueous solution containing ethyleneamines and calcium chloride to separate them from calcium chloride. More specifically, for example, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and tris-( Extraction of aliphatic cyclic ketones from aqueous solutions containing linear and cyclic ethylene amines such as 2-aminoethyl)-amine, piperazine, and N-aminoethylpiperazine and calcium chloride. Ethylene amines are selectively and efficiently extracted from the organic phase using a solvent. The present invention relates to a method for extracting calcium chloride and separating it from calcium chloride. Currently, the typical manufacturing method for ethyleneamines is to react an aqueous solution of ethyleneamine hydrochloride and ammonium chloride, which is produced by the reaction of ethane dichloride with an aqueous ammonia solution, to double decompose it with sodium hydroxide, and then remove free ammonia by heating. In this method, ethyleneamines are recovered while the sodium chloride is then crystallized and separated by evaporation and concentration. However, this method requires an extremely large amount of water during the reaction, and all of this water must be removed by evaporation, which requires a large amount of thermal energy. The only method is to separate it as crystals, which requires the use of expensive sodium hydroxide.Furthermore, in order to efficiently separate sodium chloride from ethyleneamines, complicated operations and expensive procedures are required for crystallization and separation. This method has problems such as the need for equipment. As a means to solve these problems, it is possible to carry out double decomposition using calcium hydroxide instead of sodium hydroxide, but in reality it is not possible to separate ethyleneamines and calcium chloride for the following reasons. For example, when concentrating to crystallize calcium chloride, calcium chloride and ethyleneamines react with each other due to crystallization due to temperature, precipitating calcium hydroxide, and ethyleneamines cannot be recovered. A method of extracting ethyleneamines into the organic phase is also considered, but ethyleneamines are extremely hydrophilic and it is difficult to transfer them from the aqueous phase to the organic phase using normal methods. For these reasons, the technique of double decomposition using calcium hydroxide has not been used to date. The present inventors conducted intensive studies to establish a method for separating ethyleneamines and calcium chloride under the above circumstances, and found that ethyleneamines can be extracted into the organic phase extremely efficiently when an aliphatic cyclic ketone is used. The present invention was completed based on the completely unexpected discovery that the extractability of ethyleneamines is further improved when ammonia coexists. That is,
The present invention selectively extracts ethylene amines into an organic phase from an aqueous solution containing ethylene amines and calcium chloride using an aliphatic cyclic ketone or a mixed solvent of an aliphatic cyclic ketone and an alcoholic organic solvent in the presence of ammonia. This is a method for separating ethyleneamines and calcium chloride. The present invention will be explained in more detail below. In the present invention, it is essential and extremely important to use an aliphatic cyclic ketone as an extraction solvent. The reasons and principles by which aliphatic cyclic ketones extract ethylene amines extremely selectively and efficiently are unclear and cannot be clearly explained; For example, given ethylenediamine and cyclohexanone, It is presumed that the hydrophilicity of ethyleneamines is weakened by adducts such as these or interactions similar to these, making them more likely to be extracted very efficiently into the organic phase. The ketone used in the present invention is not particularly limited as long as it is an aliphatic cyclic ketone, but cyclopentanone and cyclohexanone are preferred in consideration of ease of handling, availability, price, etc. In some cases, it is also advantageous to use a mixture of an aliphatic cyclic ketone and another organic solvent. The preferred organic solvent is an alcoholic solvent that does not react with aliphatic cyclic ketones and ethyleneamines and is effective in extracting ethyleneamines. alcohol is more preferred. There is no practical problem with the amount of aliphatic cyclic ketone used when the ketone is used alone, but when used in combination with an alcoholic solvent, the extraction may be an adduct of ethylene amine and ketone or each other as described above. In order to completely extract ethyleneamines from the aqueous phase to the organic phase, the amount of aliphatic cyclic ketone must be at least 1 mole or more relative to the ethyleneamines. Care must be taken with the amount. The mixing ratio of aliphatic cyclic ketone and alcohol solvent is by volume.
100:0 to 1:19, preferably 100:0 to 1:9,
More preferably, the ratio is 100:0 to 1:4. Furthermore, in the present invention, it is also an essential requirement to perform the extraction in the coexistence of ammonia. When an aliphatic cyclic ketone is used as an extraction solvent, ethylene amines can be selectively extracted into the organic phase and separated from calcium chloride. However, when attempting to further extract ethyleneamines from the raffinate containing some of the ethyleneamines and substantially all of calcium chloride, the ethyleneamines are extracted into the organic phase. sex is greatly reduced. In order to prevent such a decrease in extractability, it is necessary that ammonia be present during extraction.
The coexistence of ammonia not only reduces the extractability due to the coexistence ratio of ethyleneamines and calcium chloride, but also has the advantage that the extractability of ethyleneamines is improved compared to the case where ammonia is not coexisting. Although it is not clear what the reason for the effect of ammonia coexistence is, it is thought to be as follows. In other words, Ca ²⁺ ions in the aqueous phase are coordinated with water as shown in the following equation. It forms aqua ions that have properties as weak acids, and the interaction between these aqua ions and ethyleneamines, which are bases, reduces the extractability to the organic phase. However, when ammonia coexists, the acidic properties of aqua ions are neutralized by ammonia, which eliminates the above-mentioned interaction, and it is presumed that the extractability of ethyleneamines improves. As described above, in the present invention, the coexistence of ammonia is essential, but no special treatment is required to achieve this requirement except in special cases. This is because the reaction between ethane dichloride and ammonia aqueous solution requires a large excess of ammonia compared to the theoretically required amount, so the reaction solution contains a large amount of ammonia, and calcium hydroxide is added to the reaction solution. It is sufficient to add the compound to metathesize ethyleneamine hydrochloride and ammonium chloride, and then perform extraction. The coexisting amount of ammonia should be at least 2.0 times the amount of Ca ²⁺ ions present, and more preferably 6.0 times or more by mole relative to the existing Ca 2+ ions. Furthermore, since the extractability of ammonia into the organic phase is very low, it is not necessary to adjust the amount of ammonia present in the extraction process. There are no particular restrictions on the extraction conditions or extraction equipment, and any extraction equipment can be conveniently used at room temperature and pressure, and there are no restrictions on the extraction method. However, in order to efficiently recover ethyleneamines, countercurrent multistage extraction is preferable, and it is preferable to use a mixed solvent of cyclohexanone and n-butanol (volume ratio: 1:2) as the extraction solvent, which is twice the volume of the raw material aqueous solution. In the case of multi-stage extraction, substantially all of the ethyleneamines in the aqueous solution can be recovered in the solvent phase in just a few stages. At this time, the extraction rate of calcium chloride is only 5-6%.
This calcium chloride can also be completely separated by washing the extraction phase with a very small amount of water. Ethylene amines extracted into the organic phase are usually back-extracted into the aqueous phase using an acid. Both inorganic acids and organic acids can be used as the acid, but inorganic acids are easier to use and are recovered as an aqueous solution using sulfuric acid, carbonic acid, carbon dioxide gas, hydrofluoric acid, nitric acid, etc. This back extraction is extremely efficient because it extracts the ethylene amine salt that is insoluble in the organic phase, and in general, it is possible to achieve concentration of more than 5 times before and after extraction, and currently more than 80% of the water that is evaporated is removed. can be removed without the need for thermal energy. There are no restrictions on the method for recovering ethyleneamines from the high concentration ethyleneamine salt aqueous solution thus recovered, and various methods can be applied. for example,
There is a method in which calcium hydroxide is added to precipitate calcium sulfate, calcium carbonate, and calcium fluoride, and these are separated. In the method of the present invention, the solubility of the salt produced is low, so complicated operations and equipment such as currently employed concentration crystallization are not required. Further, a method of bringing an aqueous ethylene amine salt solution into contact with an anion exchange resin or liquid may also be advantageously applied in some cases. As is clear from the above detailed description, the method of the present invention consumes a large amount of thermal energy from a dilute aqueous solution of ethyleneamines obtained, for example, by the reaction of ethane dichloride and an aqueous ammonia solution. It can be effectively applied to recover ethylene amines without using expensive sodium hydroxide, and without requiring complicated operations and equipment such as concentration crystallization. By the method of the present invention, the thermal deterioration of ethyleneamines, which conventionally occurs due to long-time distillation and evaporation operations at high temperatures, can be greatly reduced. The present invention will be explained below with reference to Examples, but it is not limited to these Examples. Example 1 To 100 ml of an aqueous solution containing 90 g of ethylenediamine (EDA), 150 g of calcium chloride (CaCl ₂ ), and 140 g of ammonia (NH ₃ ), the same volumes of cyclohexanone and 1:2 (volume ratio) of cyclohexanone and n-butanol were added. ) was added, shaken for 10 minutes, statically separated, and analyzed. The results are shown in Tables 1 and 2. Table 1 shows the case where ammonia is not coexisting, and Table 2 shows the case where ammonia is coexisting.
The effects of the present invention are clear.

【table】

[Table] Examples 2 to 5 To 100 ml of an aqueous solution containing 9.0 g of ethylene amines, 17.1 g of calcium chloride (CaCl ₂ ), and 17.0 g of ammonia (NH ₃ ), 100 ml of n-butanol mixture containing 33 ml of cyclohexanone was added, and the mixture was heated for 10 minutes. After shaking, static separation was performed to obtain the following results.

[Table] Example 6 EDA 90g/, CaCl ₂ 150g/, NH ₃ 40g/
When 100 ml of a mixed solvent of cyclohexanone and n-butanol (volume ratio) of 1:2 was added to 100 ml of an aqueous solution of
110 ml of organic phase containing 56.2 g of EDA was obtained, and the extraction rate of EDA was 68.8%. Example 7 A 50% calcium hydroxide cake was added to the reaction aqueous solution obtained by the reaction of ethane dichloride (EDC) and ammonia aqueous solution, and EDA65g/,
DETA28g/, TETA16g/, TEPA6.0
g/, pentaethylenehexamine (PEHA)
4.0g/, N-aminoethylpiperazine (N-
AEP) 4.0g/, CaCl ₂ 176g/, NH ₃ 108
A solution of g/g was obtained. 100 ml of n-butanol mixture containing 33 ml of cyclohexanone was added to 100 ml of the aqueous solution, shaken for 10 minutes, and statically separated.
EDA45g/, DETA17g/, TETA9.3g/
, TEPA3.2g/, PEHA2.0g/, N-
115 ml of organic phase with 1.8 g of AEP/extraction rate was obtained.
EDA80%, DETA71%, TETA67%, TEPA62
%, PEHA 58%, and N-AEP 52%.

Claims (1)

[Claims] 1. From an aqueous solution containing ethylene amines and calcium chloride, using an aliphatic cyclic ketone or a mixed solvent of an aliphatic cyclic ketone and an alcoholic organic solvent,
A method for separating ethyleneamines and calcium chloride, characterized by selectively extracting ethyleneamines into an organic phase in the coexistence of ammonia. 2. The method according to claim 1, wherein the coexisting amount of ammonia is 2.0 times or more moles or more relative to calcium chloride. 3 Cyclopentanone or cyclohexanone as an aliphatic cyclic ketone for ethyleneamines
Claim 1 or 2 using more than twice the mole
The method described in section. 4 Claims 1 to 3 which use an aqueous solution containing ethylene amines, calcium chloride, and ammonia obtained by adding calcium hydroxide to a reaction aqueous solution obtained by the reaction of ethane dichloride and an ammonia aqueous solution. The method described in any one of the paragraphs. 5. The method according to any one of claims 1 to 4, wherein the ethylene amines extracted into the organic phase are back-extracted into the aqueous phase using an acid.