JPS5920253A - Recovery of ethyleneamines from organic phase - Google Patents

Abstract

PURPOSE:To obtain the titled compound in high yield, in a highly concentrated free state, by extracting ethyleneamines from an aqueous solution containing ethyleneamines with a specific solvent, recovering the ethyleneamines in the form of carbonate using carbon dioxide gas, etc., and thermally decomposing the carbonate. CONSTITUTION:Ethyleneamines (abbreviated as EA) is extracted from an aqueous solution containing EA (e.g. ethylenediamine) with an organic solvent (e.g. carboxylic acid, benzyl alcohol, etc.), and the extracted EA is recovered from the extract phase in the form of carbonate using carbon dioxide gas or carbonated water. The recovered carbonate is thermally decomposed to obtain free EA. The process has various advantages, e.g. ethyleneamines can be concentrated with reduced energy consumption, inexpensive CaOH can be used because the chlorine ions are separated by the extraction, the acid for the recovery process and the alkali for the decomposition of produced salt are unnecessary, the particular apparatuses and operation for the crystallization and separation, etc. of sodium chloride are unnecessary, etc.

Description

[Detailed description of the invention]

The present invention relates to a method for efficiently recovering ethyleneamines as a highly concentrated aqueous solution from an organic phase containing them. For more details. For example, from a reaction solution obtained by the reaction of ethane dichloride and aqueous ammonia, or a solution obtained by causticizing the reaction solution with an alkali such as sodium hydroxide or calcium hydroxide, ethylene amine The present invention relates to a method for selectively extracting ethyleneamines and efficiently recovering them as a highly concentrated aqueous solution from the surrounding organic phase. In the present invention, ethyleneamines include ethylenediamine, diethylenetriamine, triethylenetetramine,
Chains such as tetraethylenepentamine and viverazine, R
amines, including amines, singly or in mixtures. As mentioned above, ethyleneamines have at least 2 molecules in the molecule.
Because it has more than one amine group, it is extremely hydrophilic in nature and is virtually difficult to transfer from the aqueous phase to the organic phase using the solvents commonly used in extraction methods. However, the present inventors have discovered that ethylene amines can be extracted selectively and efficiently into the solvent phase by using a specific organic solvent, and that specific organic solvents include, for example, carboxylic acids having 6 or more carbon atoms, cyclohexanone, etc. ,
We discovered that there are aliphatic ketones such as cycloR-tanone, and even benzyl alcohol. It is not clear why ethyleneamines are easily extracted when such specific organic solvents are used. It is presumed that this was achieved by relaxing the hydrophilic effect of the group and changing the ethylene amines to organophilic properties (hereinafter referred to as organic solvent phase/transferability). Ethylene amines extracted into the solvent phase by such an extraction mechanism that involves a certain type of chemical reaction are made to have affinity properties, so when recovering ethylene amines from the solvent phase, the normal reverse method is used. Ethyleneamines cannot be recovered by extraction methods, ie, by contacting the solvent phase with water. Therefore, in order to recover ethyleneamine from the solvent phase mentioned above, it is necessary to use an acid instead of water to form a salt of ethyleneamine and transfer it from the organic phase to the aqueous phase. . Method 5) is a very effective method when the final target is a salt of ethyleneamines, but
When free ethyleneamines are the desired objective (this is usually the case), the recovered ethyleneamine salts are causticized with an alkali such as sodium hydroxide or calcium hydroxide, and the by-produced sodium and calcium salts are removed. This is not desirable as it requires separation. Under these circumstances, the inventors of the present invention have made repeated efforts to find a method that does not require the supply of alkali necessary for causticization and the separation of by-product salts. We discovered that free ethyleneamines can be easily returned by recovering ethyleneamines as carbonates and then thermally decomposing the carbonates.1
This invention has been achieved. That is, the present invention involves selectively extracting ethyleneamines from an aqueous solution containing ethyleneamines using an organic solvent. After recovering the carbonate as a salt, the carbonate is thermally decomposed to obtain free ethyleneamines. The present invention will be explained in more detail below. As mentioned above, it is not possible to selectively extract ethyleneamine from a mixture of ethyleneamines and chlorides using ordinary organic solvents, but certain solvents, such as amine groups and adducts of ethyleneamines or discovered that ethyleneamines could be selectively extracted extremely efficiently by using an organic solvent with an ability to interact similar to that of adducts, and had already proposed this. For example, cyclo-\keelinone is thought to be extracted as a solvent with a ketone group, and cyclopentanone, acetone, methyl ethyl cytonone, etc. can be used as an extraction solvent and 1 through this mechanism. and so on. As can be easily imagined from the fact that such adducts or intermediates are easily extracted when exposed to a solvent phase, they are extremely stable in organic solvents (and have low solubility in water, e.g. Ethylene amines cannot be recovered by methods such as distillation of organic phase or fusion of organic phase with water. Therefore, in order to recover ethylene amines, it is necessary to use the solvents mentioned above to bond more firmly with amine groups and to A reagent such as an acid that makes the substance water-soluble must be used. In the present invention, it is an essential requirement to use carbon dioxide gas or carbonated water as the acid for recovering ethylene amines from the solvent phase. As is clear from the explanation, ethyleneamines extracted into the solvent phase by an extraction mechanism using a chemical reaction must be recovered as ethyleneamine salts from the organic phase, so it is difficult to obtain free ethyleneamines. It is necessary to causticize the salt by adding an alkali and remove the by-product salt at this time.However, the method of the present invention employs a preferable method that does not require causticization by adding alkali and separation of the by-product salt. That is, the present inventors found that ethyleneamine carbonates are thermally unstable compounds, and as a result of studying the thermal decomposition of carbonates, for example, for ethyleneamine, the following formula We found that carbonates decompose, carbon dioxide gas evaporates, and free ethyleneamines can be easily recovered. (CH2NH,), H, Co, → (CHtNHt)
t +COz↑+H,0 Therefore, in the present invention, it is also an essential requirement to heat-treat the recovered carbonate of ethyleneamines. The water tδ liquid containing ethyleneamines in the present invention is C
Although not limited to 1, usually ethyleneamines produced by the reaction of dibasic ethane and aqueous ammonia, a mixture of aqueous ammonia chloride and free ammonia, or a mixture of calcium hydroxide, Liquids made by adding alkali such as sodium hydroxide to causticize ethyleneamines 1-batate, and also low-concentration 11 generated in various processes.
amine aqueous solution/

[This is the main target. In this aqueous solution containing ethyleneamine, ethyleneamines and an organic solvent having Ji-responsiveness are mixed and allowed to settle, and the ethyleneamines are extracted into several groups. Any substance that interacts with 1 may be used.For example, other than solvents with ketone groups, benzyl alcohol and ethylene amine, which are known to interact with ethylene amines, although the intermediate composition is unknown.
There are carboxylic acids and the like that form organic salts. Usually, carboxylic acids commonly used as extractants can be used, such as those having 6 or more carbon atoms, preferably 9 to 20 carbon atoms,
For example, naphthenic acid, pelargonic acid, etc. In addition, Versatic acid (Versa-), which is a tertiary fatty acid,
tic acid (manufactured by Nigel Kagaku Co., Ltd., product name)
etc. That is, the "organic solvent" referred to in the present invention is one that can extract ethyleneamines extremely efficiently and selectively.
In addition, it is an organic solvent that cannot separate ethyleneamines from the organic phase when it comes into contact with water, and from the properties of ethyleneamines and the organic solvent, it can be inferred that the extraction mechanism is due to some kind of reactivity. be. Of course, the solvents used in the present invention can be used alone, but they can also be used in combination. In addition, even though ethyleneamines cannot be extracted alone, the method of using a mixture of 30 to 90 volumes of a solvent such as haftyl alcohol or amyl alcohol can also improve ease of handling, improve phase separation, and in some cases improve extractability. This is the preferred method because it can also be effective. The extraction conditions include the type of solvent used, ethyleneamine concentration, etc.
yL, it varies depending on the mixing ratio of the solvent, etc., and cannot be absolutely defined, but under conditions of room temperature and normal pressure, the volume ratio of the solvent to the aqueous solution containing ethyleneamines is usually 1:1 to 1O:1, and the number of extraction stages is 2 to 1. With four stages, ethyleneamines in the aqueous solution can be extracted substantially completely. The solvent phase thus obtained generally contains 50 to 300 t/l of ethylene amines. This solvent phase is transferred directly or after contacting with a small amount of water to remove a small amount of inorganic salt co-extracted into the solvent phase, to the ethyleneamine recovery step. In the recovery step, the organic phase containing ethyleneamines is brought into contact with carbon dioxide gas or carbonated water to form carbonates of ethyleneamines. This reaction progresses very quickly, so it does not pose any operational problems, but if the ffI agent phase is brought into direct contact with carbon dioxide gas, extremely fine carbonate crystals of ethyleneamines will precipitate, and the viscosity will decrease. Since the carbon dioxide tends to increase and the contact with carbon dioxide gas tends to be poor, a more preferable method is to bring it into contact with carbon dioxide gas in the coexistence of water and recover it as an aqueous carbonate solution of ethyleneamines. As a contact method (i.e., there are no restrictions, a solvent phase containing ethylene amines, water,
Air Lift that simultaneously supplies carbon dioxide gas
ft) method, or mixing carbonated water prepared by dissolving carbon dioxide gas in water under pressure in advance with the solvent phase. After the reaction, the mixed solution is stabilized and separated into an aqueous phase and a solvent phase. The carbonate of ethylene amines is not substantially dissolved in the solvent phase, and the entire amount is recovered as an aqueous solution, and the concentration of ethylene amines varies depending on the amount of water used, but is at least 2009/2. The separated solvent phase is recycled as an extraction solvent for ethylene amines, and the aqueous phase is sent to the decarboxylation process. The carbon dioxide gas used in the recovery process can range from nearly 100% concentrated gas, which is a by-product in ammonia synthesis 1-oil chemistry, to 40% gas obtained in a lime furnace, but most of the carbon dioxide gas used in this process is usually In this part, 100% carbon dioxide gas generated in the decarboxylation process is recycled and used, so the carbon dioxide gas supplied to the first recovery process is actually highly concentrated, even if the carbon dioxide gas supplied from outside the system is dilute. This means that carbon dioxide gas can be used. Further, since the amount of carbon dioxide gas that is consumed is small, the method of the present invention can be carried out satisfactorily even without a source of carbon dioxide gas such as a lime furnace. In the decarboxylation process, the purpose is achieved simply by heating the aqueous solution of carbonate of ethyleneamines at normal pressure, so no special equipment or operations are required. Thermal decomposition temperature is usually 60-120°C, preferably 80-1
It is carried out at 20° C., and the carbonate decomposes very efficiently, producing carbon dioxide gas. The decarboxylation rate varies somewhat depending on the concentration of ethyleneamine supplied, treatment temperature, and reaction time, but the decarboxylation rate of ethyleneamines is 2009/l under decomposition conditions of 1 hour at the boiling point. More than 90 g of carbon dioxide gas supplied, 80 at 300 y/l
% or more can be removed. Furthermore, when an organic solvent such as butyl alcohol is mixed, the decarboxylation rate is further improved and substantially all of the carbon dioxide gas can be removed. As mentioned above, in the present invention, a solvent reactive with ethylene amines and a solvent such as butyl alcohol can be used in combination, and butyl alcohol has the property of being soluble in water to some extent. Therefore, in the aqueous solution of ethylene amine carbonate obtained in the first recovery step, a portion of the solvent such as butyl alcohol is generally heated.
Therefore, it effectively removes carbon dioxide gas during the decarboxylation process. The free aqueous solution of ethyleneamines obtained in this manner usually contains 2 ooy/or more of ethyleneamines. If this aqueous solution of ethyleneamines contains a small amount of carbonate, it can be removed as sodium carbonate or calcium carbonate by adding a small amount of sodium hydroxide, calcium hydroxide, or the like. When sodium hydroxide is used, it is an industrially preferred method because two phases, an aqueous sodium carbonate phase and an ethyleneamine normal phase, are formed. The ethyleneamine aqueous solution obtained by the method of the present invention has a concentration of 300? Since / is in such a high concentration and almost no components other than ethylene amine/ and water are contained, various ethylene amines can be easily obtained by ordinary distillation operations. The advantages of the method of the present invention are listed below: 1) Ethylene amines can be concentrated in an extremely energy-saving operation. ]
...The concentration of ethyleneamines obtained by this method is about 1009
/l, and in order to heat and concentrate it to 3ooy/l, it is necessary to remove 6 times the weight of water relative to ethylene amines. Does not require the use of sodium. Low grade calcium hydroxide can be used. 3) It is extremely economical as it does not require acid required in the recovery process or alkali to decompose the salts produced. 4) It is a simple process that does not require special equipment or operations unlike conventional methods such as crystallization and separation of sodium chloride. 5) A product of extremely high purity can be obtained. etc. The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples. Example work~4 Ethylene amines 18.0y and sodium chloride (Na
cl) 36.0? 200m7 of aqueous solution containing! 20 n-butanol mixture containing cyclohexano/67
After adding 0rrt and shaking for 10 minutes, static separation was performed. Next, 160 ml of K pure water 20-ml of the organic phase obtained by static separation was added, and water-saturated carbon dioxide gas was blown in at a rate of 100 mL for 2 hours to carbonate the ethylene amines in the organic phase. After back extraction into the aqueous phase as a salt, static separation was performed. Next, 20 ml of the aqueous phase obtained by static separation was placed in a 50 ml three-necked round bottom flask equipped with a condenser. The carbonates of ethyleneamines were thermally decomposed by heating in a mantle router for 2 hours in a total reflux system with boiling, and the results shown in Table 1 were obtained. Example 5 Add benzyl alcohol 2'OOm to 200 rne of an aqueous solution of TETA: 106 r/l, -NaCl: 225 f/l.
Add l'jl, shake for 10 minutes, and then quietly separate.
1'ETA: 55.2? /l- organic phase 228
m/! and TETA: 5 (1, i V /L, N
a C6262y/l water phase 172m7! I got it. Next, 15 ml of pure water was added to 150 rng of the organic phase. Water-saturated carbon dioxide gas was blown in at a rate of 100 me/m for 2 hours, and static separation was carried out to form TETA as all m carbonate groups. Back extracted into the aqueous phase. Historically, when 15 mg of the paddy was thermally decomposed in the same manner as in Example 1, 1'ETA: 360 liters/l-CO2: 1
One portion of the B9/l aqueous solution was removed. Example 6 ■ Aqueous solution 2 (1(l) of
d-10J (manufactured by Shell Chemical Co., Ltd., trade name, carbon number 10
): 1.5 mole/l n-butanol solution 30
0 ml was added, shaken for 10 minutes, statically separated, and E
An organic phase 376- of DA: 38.3 V/l was obtained. Then 200 mI of the organic phase! Add 15 liters of pure water to 100 m7 of water-saturated carbon dioxide! After blowing at a speed of /-4s for 2 hours and statically separating, EDA: 2659/L
An aqueous phase of 20.4 m, t of :co, :x92y/l was obtained. Furthermore, 15rnl of the aqueous phase was thermally decomposed in the same manner as in Example 1 to obtain an aqueous solution of EDA:26 (1/l) and Co:2 (1/l). Examples 7 to 10 Examples 1 to The same operations as in Examples 1 to 4 were performed except that 200 ml of n-butanol mixture containing 67 ml of cyclopentanone was used in place of cyclohexanone in Step 4, and almost the same results as in Examples 1 to 4 were obtained. 50 g of calcium hydroxide cake was added to the reaction aqueous solution obtained by the reaction of ethane chloride (EDC) and ammonia aqueous solution in Example 1, and EDA: 65 y/l. DETA', 2Bf/l, TETA :16r/l, TE
PA: 6, Oy/l, pentaethylenehexamine (PE
HA): 4, Q Y/l, N-aminoethylpiprazine (N-AEP): 4, Of/l, CaCA2: 176
f/l, NH3: An aqueous solution of 108 f/l was obtained. Add 200ml of n-butanol mixture containing 67ml of cyclohexanone to 200m6 of the aqueous solution, shake for 10 minutes, statically separate, EDA: 46 V/l, DETA: 1
7t/L, TETA: 9.2? /L,'rE
PA: 3.0? /l, PEHA: 2.1
'i'/l, N-AEP: J, 230me of organic phase of 8 y/l was obtained. Next, 30 g of pure water was added to 200 ml of the organic phase, water-saturated carbon dioxide gas was blown in at a rate of 100 mt/wLfR for 2 hours, static separation was carried out, and all ethyleneamines were back-extracted into the aqueous phase as carbonates. did. Furthermore, 20- in the aqueous phase was thermally decomposed in the same manner as in Example 1, resulting in EDA: 204f/7. DETA', 759/L. TETA: 41? /l, TEPA: 13 f/
l, PEIIA: 9.3? /L,N-AEP:
8. Ot/4. CO2: 50? /L of an aqueous solution was obtained. Example 12 Reaction solution obtained by reaction of EDC and ammonia aqueous solution, composition f-11, EDA: 66 f/l, DETA
”, 29f/l, TETA: 16f/L, TEPA:
6.4? /l, PEHA: 4.3f/l, N-AEP”
, 4.39/l, HCl: 117y/l, NH,: 16
1'/l, 200rnt of an n-furinol mixture containing cyclohexanone 67- is added to the aqueous solution 200-, shaken for 10 minutes, and subjected to static separation.EDA: 3
8. Of/l, DETA: 15.3 S'/l, T
ETA: 7.4 f/l, TEPA: 3.1
f/l, PEHA: 2.1 Y/l, N-AEP
: 1.4 y/l of organic phase 230- was obtained. Next, 30ml of pure water was added to 200ml of the organic phase. Water-saturated carbon dioxide gas at a rate of 100 me/-=rg 2
Bubbling was carried out for a period of time, static separation was performed, and the entire amount of ethyleneamines was converted into carbonate and back-extracted into the aqueous phase. Furthermore, 20 ml of the aqueous phase was thermally decomposed in the same manner as in Example 1, and EDA: 175 f/l, DETA near 05'/7
．． . TE”rA:a4f,/l, TEPA:14r/l,
pEHA: 9.7f/l, N-AEP: 6.4
An aqueous solution of f/l, CO,: 35 y/l was obtained. Example 13 EDA: 335 g/l, Co as prepared in Example 1. : 240 Y/l to 56 S//L aqueous solution LM
4.7 ml of NaOH aqueous solution was added, shaken for 10 minutes, and statically determined to 11 ffl. As a result, 10.8 ml of 3109/1 EDA aqueous solution containing almost no CO7 was obtained.
and contains almost no EDA, 350? /LN a,
co, an aqueous solution of 3.9 me was obtained. Example 14 Reverse extract (EDA: 320
r/z, co, :235 f/l) 15m1K
n-Butanol 15- was added and thermally decomposed in the same manner as in Example 1, resulting in EDA: 325? /l, Co2: 1.0
A 9/l aqueous solution was obtained.

Claims (1)

[Scope of Claims] (1) From an extraction phase obtained by selectively extracting ethylene amines from an aqueous solution containing ethylene amines using an organic solvent, ethylene A method for recovering ethyleneamines from an organic phase, which comprises converting amines into carbonates, recovering them at °C, and then thermally decomposing the carbonates to obtain free ethyleneamines. (2) Claim No. 1 in which the organic solvent is a mixed solvent
) method described in section. 0) The method according to claim (1) or (2), wherein part or all of the organic solvent is a solvent having a ketone group. (4) The method according to claim (1) or (2), wherein part or all of the organic solvent is benzyl alcohol. (5) The method according to claim (1) or (2), wherein a part of the organic solvent is a carboxylic acid.