JP3384608B2 - Recovery method of lithium ion - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for recovering lithium ions. More specifically, polyarylene sulfide (PAS) useful in the fields of electricity, electronics, and high rigidity materials.
In the manufacturing process of 1., it relates to a method for efficiently recovering lithium ions from a PAS production reaction liquid containing lithium chloride.

[0002]

2. Description of the Related Art Polyarylene sulfide resin (PAS
Resin), especially polyphenylene sulfide resin (P
PS resin) has excellent mechanical strength, heat resistance, etc.
It is particularly known as an engineering resin having high rigidity and is useful as a material for electronic / electrical device parts and various high-rigidity materials. Conventionally, the production of these resins has been
Reacting a dihalogenated aromatic compound such as p-dichlorobenzene with a sodium salt such as sodium sulfide in an aprotic organic solvent such as N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as NMP). That method has been commonly used. In this case, however, sodium chloride, which is a by-product, is insoluble in a solvent such as NMP, so that it is taken into the resin and it is not easy to remove it by washing.

Therefore, when lithium salt is used in place of sodium salt for polymerization and lithium chloride is produced as a by-product, lithium chloride is soluble in many aprotic organic solvents (polymerization solvents) such as NMP. Therefore, since it becomes possible to reduce the lithium concentration in the resin relatively easily,
The method using a lithium salt has come to the fore.

However, since lithium is much more expensive than sodium, it is necessary to recover and reuse lithium ions in order to reduce the production cost of the polymer.

When using this lithium salt, PPS
As a method for producing a PAS resin that uses a resin or the like as a type,
These resins are prepared from lithium N-methylaminobutyrate (hereinafter sometimes abbreviated as LMAB) produced by the reaction of lithium hydroxide and NMP, a dihalogenated aromatic compound such as p-dichlorobenzene, and hydrogen sulfide. A method of manufacturing by a batch method or a continuous method is disclosed in US Pat. No. 4,451,643. In this method, a polymer such as a PPS resin is synthesized using LMAB which is a lithium salt instead of a sodium salt as a raw material for polymerization,
Since NMP solvent-soluble lithium chloride is produced as a by-product, it has the advantage that the amount of alkali metal component incorporated in the polymer is much smaller than the method in which sodium chloride insoluble in this solvent is produced as a by-product. is doing.

[0006]

However, in the method described in the above-mentioned US Patent, since lithium hydroxide is used as a starting material, it is attempted to recover and reuse the lithium chloride produced as a by-product during polymer synthesis. Then, it is necessary to return lithium chloride produced as a by-product to lithium hydroxide by some method. As a method for recovering this lithium chloride and converting it to lithium hydroxide, the above-mentioned specification describes that the reaction mixture after polymer synthesis or the lithium chloride (aqueous solution) recovered by washing the polymer with water is reacted with sodium hydrogen carbonate or electrolyzed. The method of making lithium hydroxide is described. However, when sodium hydrogencarbonate is used, lithium carbonate is produced, and it is a complicated process of converting it to lithium hydroxide. Electrolysis is costly and impractical in the process.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for efficiently recovering lithium ions from lithium chloride generated in a PAS manufacturing process.

[0008]

In order to achieve the above object, according to the present invention, in a method for recovering lithium ions from a reaction solution of polyarylene sulfide (PAS) containing lithium chloride, the PAS containing lithium chloride is used.
It is possible to add an alkali metal hydroxide or an alkaline earth metal hydroxide to the reaction solution for producing, to react lithium ions with hydroxide ions, and to recover lithium ions as the reaction product, lithium hydroxide. A featured method of recovering lithium ions is provided. In a preferred embodiment, the amount of the alkali metal hydroxide or alkaline earth metal hydroxide added is 0.9 as a hydroxide ion with respect to 1 mol of lithium ion of lithium chloride in the PAS formation reaction solution. In the method for recovering lithium ions, the alkali metal hydroxide or alkaline earth metal hydroxide is sodium hydroxide, potassium hydroxide or magnesium hydroxide. When the reaction temperature of the lithium ion and the hydroxide ion is the addition of an alkali metal hydroxide or an alkaline earth metal hydroxide in the form of an aqueous solution, the method for recovering lithium ions is characterized by 0 to 230. The method for recovering lithium ions is characterized in that the temperature is 60 to 230 ° C. when charged in the solid state.

The lithium ion recovery method of the present invention will be specifically described below. 1. PAS production reaction liquid containing lithium chloride The PAS production reaction liquid used in the present invention includes PAS production reaction liquid.
There is no particular limitation as long as the production reaction liquid contains lithium chloride, and any PAS production method may be used. Here, the PAS production reaction solution is
After the PAS formation reaction, it means the reaction solution after the PAS is separated by a generally used method (for example, solid-liquid or liquid-liquid separation). For example, as shown in U.S. Pat. No. 4,451,643, lithium hydroxide and N-methyl-2-
Lithium N-methylaminobutyrate (LMAB) is prepared by reacting with pyrrolidone (NMP), and a dihalogenated aromatic compound such as p-dichlorobenzene is reacted with a sulfur source such as hydrogen sulfide. By PA
The method of generating S can be mentioned.

2. Alkali metal hydroxide or alkaline earth metal hydroxide There are no particular restrictions on the alkaline earth metal hydroxide or alkaline earth metal hydroxide to be added to the PAS formation reaction solution, but, for example, hydroxylation Examples thereof include sodium, potassium hydroxide, magnesium hydroxide and the like.
Of these, sodium hydroxide is particularly preferable because it is industrially easily available and inexpensive.

3. Method for charging alkali metal hydroxide or alkaline earth metal hydroxide There is no particular limitation on the method for charging the alkali metal hydroxide or alkaline earth metal hydroxide used in the present invention, for example, aqueous solution or solid Examples of the method include a method of industrially using alkali metal hydroxide or alkaline earth metal hydroxide, which is mixed in a tank or a line. The amount of the hydroxide ion is 0.90 to 1.1 mol, relative to 1 mol of lithium ion,
It is preferably 0.95 to 1.05 mol.
If the amount exceeds 1.1 mol, it does not hinder the production of lithium hydroxide, but it causes an increase in the basic unit of alkali metal (earth metal) hydroxide and a decrease in the purity of the produced PAS in connection with the subsequent operation. It is not preferable because it may occur. On the other hand, when it is less than 0.90, lithium remains dissolved as a chloride, resulting in loss of lithium.

4. Reaction Conditions of Lithium Ions and Hydroxide Ions The conditions for reacting lithium ions and hydroxide ions are not particularly limited, but the reaction temperature is, for example, an alkali metal hydroxide or an alkaline earth metal hydroxide in an aqueous solution. When charged in the form of a sheet, it is usually 0 to 230 ° C., preferably 6
It is 5 to 150 ° C., and when it is charged in a solid state, it is usually 60 to 230 ° C., preferably 90 to 150 ° C. When the reaction temperature is low, the solubility is low and the reaction rate is remarkably slow. If the reaction temperature is high, it will be higher than the boiling point of NMP,
It has to be performed under pressure, which is a process disadvantage. The reaction time is not particularly limited.

5. Recovery of Lithium Ion The lithium ion may be recovered as solid lithium hydroxide, but when continuously used for PAS production, it is more preferable to use it as a lithium hydroxide solution in the next step. That is, when a liquid or gaseous sulfur compound is added to an aprotic organic solvent containing solid lithium hydroxide or an alkali metal or alkaline earth metal chloride, lithium hydroxide is soluble in the aprotic organic solvent. As a result, the insoluble alkali metal or alkaline earth metal chloride can be separated and removed by solid-liquid separation, and can be directly supplied to the next step of PAS production as a lithium hydroxide solution.

[0014]

【Example】

[Example 1] Hereinafter, the method for recovering lithium ions of the present invention will be described more specifically by way of examples. N-methyl-2-pyrrolidone 415.94 g (4.2 mol) and lithium chloride 63.585 g (1.5 mol) were put into a 500 ml glass separable flask equipped with a stirring blade, and lithium chloride was dissolved at 90 ° C. It was After dissolution 4
125.0 g of 8 wt% sodium hydroxide solution (NaOH
At the same time as the addition of (1.5 mol) was charged, a white solid was instantaneously produced. The dissolved water was dehydrated while raising the temperature under a nitrogen stream. After cooling the dehydrated mixture, the contents were put into a glass filter (G4) at room temperature and filtered under reduced pressure. The filtered substance on the filter was dried under reduced pressure at 150 ° C. and weighed to find that it was 123.5 g. In addition, as a result of elemental analysis Na /
Li / Cl (mol ratio) = 1.03 / 1.00 / 1.0
It was 0. Furthermore, by X-ray diffraction, LiOH, NaC
It was in agreement with the spectrum of l. Further, according to the ion chromatogram, neither lithium ion nor sodium ion was detected in the supernatant layer (NMP layer). From the above results, LiCl and NaOH are almost 100% in LiO.
It was confirmed that H and NaCl were converted.

[Example 2] 48% by weight in Example 1
Instead of 125.0 g of sodium hydroxide solution, 168.3 g of 50 wt% potassium hydroxide (1.5 mol of KOH
Equivalent). As a result, a large amount of white precipitate was obtained. Then, the same operation as in Example 1 was performed to obtain a white precipitate 14.
6.1 g was obtained. According to ion chromatography, neither potassium ions nor lithium ions were detected in the supernatant layer (NMP layer). In addition, by X-ray diffraction, LiO
It was in agreement with the spectra of H and KCl. From the above results,
It was confirmed that LiCl and KOH were converted to LiOH and KCl at a ratio of almost 100%.

[0016]

As described above, according to the method for recovering lithium ions of the present invention, lithium ions can be efficiently recovered from lithium chloride in the PAS formation reaction solution. Moreover, since the purity of the recovered lithium hydroxide is high, by recycling this lithium hydroxide in the production of PAS,
High quality PAS can be efficiently manufactured.

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) C01D 15/02 C08G 75/02

Claims (4)

(57) [Claims] 1. A method for recovering lithium ions from a polyarylene sulfide (PAS) production reaction solution containing lithium chloride, wherein the PAS production reaction solution containing lithium chloride is an alkali metal hydroxide or an alkaline earth metal water. A method for recovering lithium ions, which comprises charging an oxide, reacting lithium ions with hydroxide ions, and recovering lithium ions as a reaction product, lithium hydroxide. 2. The amount of the alkali metal hydroxide or alkaline earth metal hydroxide added is 0.9 to 1 as hydroxide ion with respect to 1 mol of lithium ion of lithium chloride in the PAS formation reaction solution. The method for recovering lithium ions according to claim 1, wherein the amount is 1 mol. 3. The lithium ion recovery according to claim 1, wherein the alkali metal hydroxide or alkaline earth metal hydroxide is sodium hydroxide, potassium hydroxide or magnesium hydroxide. Method. 4. The reaction temperature of the lithium ion and the hydroxide ion is 0 to 230 ° C. when an alkali metal hydroxide or an alkaline earth metal hydroxide is added in the form of an aqueous solution.
The method for recovering lithium ions according to claim 1, wherein the temperature is 60 to 230 ° C. when the solid state is charged.