JPH0229668B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention enables the production of ethyleneamines from an aqueous solution containing ethyleneamines.
It relates to a method for recovering ethyleneamines, and more specifically, for example, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and tris-obtained by the reaction of dichloroethane and ammonia aqueous solution. The present invention relates to a method for selectively and efficiently extracting and recovering ethylene amines into an organic phase from an aqueous solution containing chain and cyclic ethylene amines such as (2-aminoethyl)-amine, piperazine, and N-aminoethylpiperazine. Generally, ethyleneamines produced by the reaction of ethane dichloride and aqueous ammonia solution are obtained as hydrochloride as a mixed aqueous solution with ammonium chloride.
Usually by adding sodium hydroxide to the above reaction solution,
It is produced by a method in which ethyleneamine hydrochloride and ammonium chloride are metathesized, then free ammonia is recovered by heating, and then evaporated and concentrated to recover ethyleneamines while crystallizing and separating sodium chloride. However, in this method of separating reaction products by adding sodium hydroxide, it is necessary to evaporate all of the extremely large amount of water used in the reaction, which requires a large amount of energy, and also requires a large amount of energy. In order to efficiently separate sodium chloride from chloride, there are problems such as requiring complicated operations and expensive equipment for crystallization and separation. Extractive separation using an organic solvent may be considered as a method to solve these problems, but ethyleneamines are extremely hydrophilic, and normal methods cannot
Transfer from the aqueous phase to the organic phase is difficult.
Therefore, as an extraction method using an organic solvent, for example, ethylene amines are extracted from an aqueous solution containing ethylene amines with a sodium hydroxide concentration of 25 to 45% by weight using a unipolar organic solvent. An extraction method under such conditions has been proposed. However, this method has problems such as the need to add a large excess of alkali, the need to reuse the aqueous phase, and the need to create special conditions. As a result of intensive studies aimed at establishing a more economical and efficient method for separating ethyleneamines, the present inventors found that ethyleneamines can be separated into the organic phase extremely efficiently using an organic solvent having a ketone group. Discovering new and completely unexpected knowledge,
The present invention has been completed. That is, the present invention provides an organic solvent having a ketone group or a ketone group from an aqueous solution containing ethyleneamines (excluding an aqueous solution containing ethyleneamines, calcium chloride, and ammonia, and an aqueous solution containing ethyleneamines hydrochloride and ammonia). This is a method for selectively recovering ethylene amines, which is characterized by selectively extracting ethylene amines using an organic solvent having the following properties and a mixed solvent with another organic solvent. The method of the present invention does not require any special requirements for aqueous solutions containing ethyleneamines (excluding aqueous solutions containing ethyleneamines, calcium chloride, and ammonia, and aqueous solutions containing ethyleneamines hydrochloride and ammonia). Since the large amount of water used in the reaction can be removed outside the process as an extraction residue, an extremely large amount of energy can be saved compared to conventional methods. complicated operations,
No expensive equipment required. The present invention will be explained in more detail below. In the method of the present invention, the use of an organic solvent having a ketone group is an essential requirement and is extremely important. That is, organic solvents having ketone groups extract ethyleneamines extremely selectively and efficiently. The reason for this, the principle, etc., cannot be clearly explained as there are some unknown points, but it is possible that ethyleneamines form some kind of adduct with an organic solvent having a ketone group.
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 such a state, making them more likely to be extracted very efficiently into the organic phase. The organic solvent having a ketone group used in the present invention may be any organic solvent as long as it has the effect of making ethyleneamines lipophilic and making them easier to extract, such as chain ketones; methyl ethyl ketone, methyl isobutyl ketone; aliphatic cyclic ketones. ; Examples include cyclopentanone, cyclohexanone, methylcyclohexanone, etc. Particularly preferred are cyclopentanone, cyclohexanone, and the like. It goes without saying that an organic solvent having a ketone group alone can be used as the organic solvent, but it is also advantageous to use it in combination with other organic solvents. Other organic solvents may be used as long as they do not react with ketone groups and ethyleneamines, mix with organic solvents having ketone groups, and phase separate from water, such as alcohols, ethers, and esters. Alcohols are preferred from the standpoint of extractability of ethyleneamines, and alcoholic organic solvents having 3 to 8 carbon atoms are more preferred from the standpoint of ease of handling, phase separation, cost, and the like. In the present invention, as described above, extraction is performed by adducts or interactions with ethyleneamines, so in order to completely extract ethyleneamines from the aqueous phase into the organic phase, the amount of It is necessary to use organic solvents with ketone groups. When an organic solvent having a ketone group is used alone as an extraction solvent, in order to form an aqueous phase and an organic phase and efficiently separate the two phases, a considerably larger amount of extraction solvent than the above conditions is required. Although there is no particular problem, when using in combination with other organic solvents, care must be taken to ensure that the amount of the organic solvent having a ketone group used is at least 1 times the mole of the ethyleneamine. The mixing ratio of the organic solvent having a ketone group and the other organic solvent is 100:0 to 1:19, preferably 100:0 to 1:9, more preferably 100:0 by volume.
~1:4. There are no restrictions on the aqueous solution containing ethyleneamines, but usually the reaction solution produced by the reaction of ethane dichloride and ammonia aqueous solution, especially an alkali hydroxide such as sodium hydroxide or an alkaline earth metal such as calcium hydroxide, is used in the reaction solution. The target is an aqueous solution obtained by adding hydroxide and metathesizing ethyleneamine hydrochloride and ammonium chloride. Free ammonia may be removed before extraction, or may coexist during extraction. However, this excludes aqueous solutions containing ethyleneamines, calcium chloride, and ammonia, and aqueous solutions containing ethyleneamines hydrochloride and ammonia. 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. Although there are no restrictions on the extraction method, countercurrent multi-stage extraction is preferred in order to efficiently recover ethyleneamines, and for example, a mixed solvent of cyclohexanone and n-butanol in a ratio of 1:2 (volume ratio) may be used as the extraction solvent. When double the volume of ethylene amines is used for multi-stage countercurrent extraction, substantially all of the ethylene amines in the aqueous solution can be recovered to the solvent phase in just a few stages. At this time, the extraction rate of sodium chloride is
It is only 1.5%, and this sodium chloride can be completely separated by washing the extraction phase with a very small amount of water. Ethylene amines extracted into the organic phase in this way can be recovered by distillation depending on the type of ketone used, but ketones with strong interactions such as cyclohexanone may turn into Schiff base during distillation. Because of its strong properties, it is usually back-extracted into the aqueous phase using an acid. As the acid, both inorganic acids and organic acids can be used, but inorganic acids are preferably used, and sulfuric acid, hydrochloric acid, carbonic acid or carbon dioxide gas, hydrofluoric acid, nitric acid, etc. are used. This back extraction is extremely efficient as it extracts into the aqueous phase with an ethyleneamine salt that is insoluble in the organic phase, and usually
Before and after extraction, ethylene amines can be concentrated more than 5 times, and the water that has been removed by evaporation using conventional methods can be concentrated.
More than 80% can be removed by extraction. The method of recovering ethyleneamines from the high concentration ethyleneamine salt aqueous solution thus recovered is not limited in the present invention, and various methods can be applied. For example, there is a method in which sodium hydroxide or calcium hydroxide is added to precipitate sodium chloride, calcium sulfate, or calcium carbonate, and these are separated. In this case, the concentration of ethyleneamines is high, the solubility of the salts produced is low, and salts with low solubility are produced, so complicated operations such as the concentration crystallization currently being carried out, No need to dazzle the device. Also,
A method of bringing an aqueous ethyleneamine salt solution into contact with an anion exchange resin or liquid may also be advantageous in some cases. As is clear from the detailed description above, the method of the present invention can be used to prepare a dilute aqueous solution of ethylene amines without consuming a large amount of thermal energy as in the past, and without complicated operations such as concentration crystallization. It is effectively applied to recover ethylene amines without the need for equipment. Further, by using the method of the present invention, a dilute solution of ethyleneamines can be effectively concentrated without consuming a large amount of thermal energy. Furthermore, by applying the method of the present invention, the deterioration of ethyleneamines due to heat, which conventionally occurs due to long-time distillation and evaporation operations at high temperatures, is significantly reduced. The present invention will be explained below with reference to Examples, but it is not limited to these Examples. Examples 1 to 5 To 100 ml of an aqueous solution containing 8.0 g of ethylenediamine (EDA) and 15.0 g of sodium chloride (NaCl), the same volume of cyclohexanone and n-butanol were added at the mixing ratio shown in the table below, and after shaking for 10 minutes, the mixture was allowed to settle. The analysis results are shown in the table below.

[Table] Examples 6-9 9.0g of ethyleneamines and sodium chloride
Cyclohexanone 33 in 100ml of an aqueous solution containing 18.0g
Add 100 ml of n-butanol mixture containing 10 ml of
After shaking for a minute, static separation was performed to obtain the following analytical results.

[Table] Examples 10 to 13 The same operations as in Examples 6 to 9 were performed on an aqueous solution containing 11.0 g of calcium chloride instead of 18.0 g of sodium chloride in Examples 6 to 9.
The following analysis results were obtained.

[Table] Examples 14-17 n-butanol mixture containing 33 ml of cyclopentanone instead of cyclohexanone in Examples 6-9
Extraction was carried out in the same manner as in Examples 6 to 9 except that 100 ml was used, and almost the same results as in Examples 6 to 9 were obtained. Example 18 For an aqueous solution of 90 g of EDA and 150 g of sodium chloride, twice the volume of a mixed solvent of cyclohexanone and n-butanol (volume ratio) of 1:2 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%, while the extraction rate of sodium chloride was 1.5%. Next, 10 ml of water was added to 100 ml of the organic phase from which EDA had been extracted, and after shaking for 10 minutes, static separation was performed. No sodium chloride was present in the organic phase, and it was possible to completely remove it. Example 19 To 100 ml of the organic phase obtained in Example 18, 8.0 mL of hydrochloric acid was added.
After adding 20 ml of an aqueous solution containing g and shaking for 10 minutes,
After static separation, 23.2 ml of an aqueous phase was obtained. As a result of the analysis, the aqueous phase contained all the EDA contained in the organic phase, and the EDA concentration was 304 g/L.

Claims (1)

[Scope of Claims] 1. An organic solvent having a ketone group from an aqueous solution containing ethyleneamines (excluding an aqueous solution containing ethyleneamines, calcium chloride, and ammonia, and an aqueous solution containing ethyleneamines hydrochloride and ammonia), or A method for recovering ethyleneamines, which comprises selectively extracting ethyleneamines into the organic phase using a mixed solvent containing an organic solvent having a ketone group and another organic solvent. 2. The method according to claim 1, wherein the organic solvent having a ketone group is used in an amount of 1 mole or more relative to the ethyleneamine contained in the aqueous solution. 3. The method according to claim 1 or 2, wherein an aliphatic cyclic ketone is used as the organic solvent having a ketone group. 4. The method according to claim 3, in which cyclopentanone and/or cyclohexanone is used as the aliphatic cyclic ketone. 5. The method according to any one of claims 1 to 4, in which an alcoholic solvent having 3 to 8 carbon atoms is used as the other organic solvent. 6. The method according to any one of claims 1 to 5, wherein ethylene amines are recovered from an organic phase using an acid.