JP6686737B2 - Method for producing anhydrous alkali metal sulfide - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a method for producing anhydrous alkali metal sulfide, and more particularly to a method for efficiently producing a highly pure and uniform anhydrous alkali metal sulfide.

In recent years, as a raw material for engineering plastics and pharmaceuticals, anhydrous alkali metal sulfides having high purity and easy to handle, especially polyarylene sulfide and anhydrous sodium sulfide as a raw material for pharmaceuticals having a sulfide bond have been required. Currently, as the sodium sulfide generally commercially available, sodium sulfide crystals (Na ₂ S · 9H ₂ O having a crystal water to crystallize by cooling or concentrating the aqueous sodium _{sulphide, Na 2 S · 6H 2 O} , Na ₂ S ・ 5.5H ₂ O, Na ₂ S ・ 5H ₂ O, etc.) or hydrous sodium sulfide obtained by solidifying a hot aqueous solution of sodium sulfide with a concentration of about 60% into pellets, flakes, chips, etc. is there. However, these sodium sulfides contain water in an amount of 30% or more, and have the drawbacks of low purity, strong deliquescent property, and easy oxidation.

  In chemical reactions using these alkali metal sulfides as raw materials, there are problems that water present in the product induces undesired side reactions and changes the equilibrium state of the reaction. An operation such as dehydration becomes necessary and the operation becomes complicated. Further, in order to allow the reaction to proceed smoothly, a fine particulate anhydrous alkali metal sulfide that is well dispersed and easily dissolved in a reaction solvent is desired.

As a method for obtaining anhydrous sodium sulfide, a method in which hydrated or hydrous sodium sulfide is heated to a temperature equal to or higher than the melting point and dehydrated is general. However, when the sodium sulfide containing water is melted, it becomes an extremely high-viscosity lump and firmly adheres to the container, making it difficult to stir or take it out. What has been known so far as a method for producing anhydrous sodium sulfide,
(1) Fill sodium hydrated sodium sulfide nonahydrate into a pipe, heat it under reduced pressure of 1 torr without stirring to heat it up to 800 ° C while avoiding melting, and force dehydration. Method (see Patent Document 1).
(2) Method for precipitating anhydrous sodium sulfide crystals from an aqueous sodium sulfide solution containing 2 to 15% by mass of sodium hydroxide at 97 ° C. or higher (see Patent Document 2).
(3) Heating the highly hydrated sodium sulfide crystals at a pressure of 500 Torr or less at a phase transition point ± 10 ° C from the highly hydrated sodium sulfide crystals to sodium sulfide monohydrate for 4 to 5 hours, and then at atmospheric pressure. Alternatively, a method of obtaining anhydrous sodium sulfide by heating under reduced pressure at 90 to 200 ° C. for 4 to 5 hours (see Patent Document 3).
(4) At least one selected from sodium sulfide hydrate and organic sulfonic acid metal salt, lithium halide, organic carboxylic acid metal salt, and phosphoric acid alkali metal salt in the presence of a hydrocarbon solvent or a polyhaloaromatic compound. There is known a method of obtaining a sodium sulfide composition by bringing a metal salt into contact with water for dehydration (see Patent Documents 4 and 5) and the like.

However, the method (1) is not practical because the heating temperature is extremely high, and the obtained anhydrous sodium sulfide becomes a skeletal crystal that retains the crystal shape of the hydrate, and has a large specific surface area and deliquescent. And was very easily oxidized. Although the methods (2) and (3) are methods that have improved these drawbacks, the method (2) strictly controls the sodium hydroxide concentration and temperature during the precipitation of anhydrous sodium sulfide crystals. It was necessary and not an easy method. In addition, the method (3) requires a long time under reduced pressure and requires several steps, and dehydration is performed while maintaining the particle shape without melting Na ₂ S.5 hydrate as a raw material. The particle size of the raw material Na ₂ S.5 hydrate was directly reflected in the particle size of anhydrous sodium sulfide, and the particle size of the obtained anhydrous sodium sulfide was 1 to 1.5 mm, which was a relatively large crystal. . When such a crystal is present, the specific surface area becomes small and the reactivity decreases when it is used as a raw material for engineering plastics and pharmaceuticals. Therefore, the crystal is separately added as fine particles (for example, 800 μm or less). In some cases, a step of crushing was required. In the method (4), it is necessary to add an organic sulfonic acid metal salt, a lithium halide, an organic carboxylic acid metal salt, an alkali metal phosphate or the like as a dispersant to the dehydrated system. It became almost impossible to take out the anhydrous sodium sulfide alone as a mixture with those metal salts.

  Therefore, as a method of obtaining a particulate highly pure anhydrous alkali metal sulfide, dehydration is performed by contacting an aqueous alkali metal sulfide solution with a dispersion medium having a melting point equal to or lower than the boiling point of the aqueous solution. A method for producing a mixture of dispersion media is known (see Patent Document 6). However, this method also has low energy efficiency and cannot produce anhydrous alkali metal sulfide with good productivity.

US Pat. No. 2,533,163 JP-A-64-28207 JP-A-2-51404 JP-A-60-200807 JP-A-60-210509 Japanese Patent Laid-Open No. 9-67108

  Therefore, the problem to be solved by the present invention is to produce high-purity anhydrous alkali metal sulfide in the form of fine particles with high productivity.

  The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, a water-containing alkali metal sulfide is dropped into liquid paraffin at high temperature to dehydrate the water of crystallization in the alkali metal sulfide. It has become possible to obtain the anhydrous alkali metal sulfide efficiently, and has completed the present invention.

  That is, the present invention relates to a method for producing anhydrous alkali metal sulfide, which comprises the step of dropping hydrous alkali metal sulfide into liquid paraffin at 250 ° C. or higher.

  According to the present invention, a highly pure anhydrous alkali metal sulfide in the form of fine particles can be produced with good productivity.

The method for producing an anhydrous alkali metal sulfide of the present invention is characterized by including a step (1) of dropping a hydrous alkali metal sulfide into liquid paraffin at 250 ° C. or higher.

  Examples of the hydrated alkali metal sulfide used in the present invention include liquid or solid hydrates of compounds such as lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, and cesium sulfide, and the solid content concentration is not particularly limited. Is 10 to 80% by mass, and particularly preferably 35 to 65% by mass. As the hydrous alkali metal sulfide, preferred is hydrous sodium sulfide. The form of hydrous sodium sulfide used may be any of crystals, flakes, solids, liquids and aqueous solutions.

The hydrated alkali metal sulfide may be prepared from, for example, a hydrated alkali metal hydrosulfide and an alkali metal hydroxide. Examples of the hydrated alkali metal hydrosulfide include liquid or solid hydrates of compounds such as lithium hydrosulfide, sodium hydrosulfide, potassium hydrosulfide, rubidium hydrosulfide, and cesium hydrosulfide. Although not limited, it is preferably 10 to 80% by mass, and particularly preferably 35 to 65% by mass. As the hydrous alkali metal hydrosulfide, preferred is hydrous sodium hydrosulfide. The shape of the hydrous sodium hydrosulfide used may be any of crystals, flakes, solids, liquids and aqueous solutions. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, and aqueous solutions thereof. When used as the aqueous solution, it is preferably an aqueous solution having a concentration of 20% by mass or more. Among these, lithium hydroxide, sodium hydroxide and potassium hydroxide are particularly preferable, and sodium hydroxide is particularly preferable. The amount of the alkali metal hydroxide used is preferably in the range of 0.8 to 1.2 mol, and particularly preferably 0.9, per mol of the alkali metal hydrosulfide, from the viewpoint of promoting the production of anhydrous alkali metal sulfide. The range of up to 1.1 mol is more preferable.

  The hydrous alkali metal sulfide to be dropped may be an aqueous solution, but preferably, it may be dissolved to be a solution or dispersed to be a dispersion in the presence of an organic solvent soluble in water.

  Examples of the organic solvent soluble in water include ketones such as acetone (solubility: compatible with water in all proportions; boiling point: 56.1 ° C.); methanol (solubility: compatible with water in all proportions) , Boiling point: 64.7 ° C.), ethanol (solubility: compatible with water in all proportions, boiling point: 78.3 ° C.), isopropyl alcohol (solubility: compatible with water in all proportions, boiling point: 82. 26 ° C.), alcohols such as ethylene glycol (solubility: compatible with water in all proportions, boiling point: 197 ° C.); esters such as methyl acetate (solubility: 24% by mass, boiling point: 56.9 ° C.) Is mentioned. These organic solvents may be used alone or in combination of two or more. Preferred organic solvents are ketones and alcohols, more preferred are ethanol, acetone, isopropyl alcohol and ethylene glycol, and most preferred are ethanol, acetone and ethylene glycol.

  The liquid paraffin used in the present invention contains liquid paraffin having an initial boiling point of 300 ° C. or higher, and is a mixed liquid of liquid paraffin (a) having an initial boiling point of 300 ° C. or higher and normal paraffin having 14 to 16 carbon atoms (b). Is more preferable. By using the mixed solution, particles of the hydrated alkali metal sulfide formed by dropping into liquid paraffin do not aggregate, and quickly settle down, and each particle efficiently absorbs heat to dehydrate crystal water, It is preferable because it is possible to prevent the aggregation of the anhydrous alkali metal sulfide. The ratio of the liquid paraffin (a) having an initial boiling point of 300 ° C. or higher and the normal paraffin (b) having 14 to 16 carbon atoms in the mixed solution is (a) / (b) = 99/1 on a mass basis. The range is preferably from 50 to 50/50, more preferably from 90/10 to 70/30.

  The normal paraffin is preferably a linear hydrocarbon having 14 to 16 carbon atoms. Each of these hydrocarbons may be used alone, or a normal paraffin mixture which is a mixture of these hydrocarbons may be used.

  The heating temperature of the dropped liquid paraffin is preferably in the range of 250 ° C. or higher and 300 ° C. or lower. It is preferable to heat the liquid paraffin to prevent dropping of the temperature of the liquid paraffin with respect to the dropwise addition of the hydrated alkali metal sulfide to maintain the above temperature range.

 Dropping of the water-containing alkali metal sulfide or the aqueous solution containing the water-containing alkali metal sulfide into the liquid paraffin is preferably carried out by a dropping nozzle. In the nozzle, the hydrous alkali metal sulfide may be dropped into the liquid paraffin so as to be dropped from the gas phase, or the tip of the nozzle may be immersed in the liquid paraffin and directly put into the liquid paraffin. You may drop.

Further, by adjusting the nozzle diameter at the time of dropping, the particle diameter of the dropped droplet, and thus the particle diameter of the anhydrous alkali metal sulfide, can be adjusted. The nozzle diameter is preferably 0.5 to 5 mm, more preferably 1 to 2 mm.

  As described above, in the present invention, by adjusting the particle diameter of the droplet when the hydrous alkali metal sulfide is dropped and the ratio of the liquid paraffin (a) and the normal paraffin, for example, a range of 30 to 500 μm is obtained. Further, anhydrous alkali metal sulfide having a desired particle size range of 100 to 300 μm can be obtained.

  The anhydrous alkali metal sulfide obtained through the above step (1) is then subjected to solid-liquid separation using an appropriate filter, and then an organic solvent that dissolves liquid paraffin, and a fluid attached to the surface of the anhydrous alkali metal sulfide. It may have a step of removing paraffin.

The organic solvent used for the removal may be any as long as it can dissolve the liquid paraffin well, but among them, the paraffinic hydrocarbon has good compatibility with the liquid paraffin and completely removes the liquid paraffin on the surface of the anhydrous alkali metal sulfide. It is preferable because it can be washed.

As the paraffinic hydrocarbon for removal, a linear hydrocarbon having 6 to 10 carbon atoms, that is, hexane, heptane, octane, nonane, and decane can be particularly preferably used. You may use these individually or in mixture of 2 or more types.

  The anhydrous alkali metal sulfide thus obtained can be dried to prepare a powdery or granular anhydrous alkali metal sulfide. Anhydrous alkali metal sulfide has a deliquescent property and reacts with carbon dioxide in the air. Therefore, it is desirable to store it in an airtight manner and shield it from the air.

  Since the anhydrous alkali metal sulfide of the present invention obtained by the above method is highly pure and uniform, it can be used as a raw material for engineering plastics and pharmaceuticals.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto. In addition, unless otherwise specified,% represents mass%.

(Measurement Method) Moisture Content Using a coulometric Karl Fischer moisture meter (manufactured by Kyoto Electronics Manufacturing Co., Ltd.) equipped with a moisture vaporizer, the obtained anhydrous sodium sulfide was heated at 280 ° C. for 20 minutes to evaporate the moisture into nitrogen gas. Was sent to the Karl Fischer solution and the water content was measured by the Karl Fischer method.

(Measurement Method) Purity Measurement of Anhydrous Sodium Sulfide in Crystals The purity measurement of anhydrous sodium sulfide was determined by measurement according to JIS K1435-1986.

(Measurement Method) Secondary Particle Diameter of Anhydrous Sodium Sulfide The secondary particle diameter of anhydrous sodium sulfide was determined by measurement according to JIS Z8815-1994.

[Example 1]
In a flask equipped with a stirrer and a decanter, hydrous sodium hydrosulfide (48.30% sodium hydrosulfide aqueous solution) 116.1 g (sodium hydrosulfide 1.000 mol), 48.64% sodium hydroxide aqueous solution 82.22 g (sodium hydroxide) 1.000 mol) was added and mixed, and the mixture was maintained at 120 ° C. to prepare an aqueous solution in which sodium sulfide was dissolved.

  Next, using a glass instrument equipped with a decanter, 500 g of liquid paraffin (Wako Pure Chemical Industries, Ltd. “liquid paraffin”) was charged, and the temperature was raised to 250 ° C. with stirring.

  Then, 50 g of the prepared sodium sulfide aqueous solution was charged into liquid paraffin from a dropping nozzle (nozzle diameter 1 mm) at a rate of 1 g / min while maintaining the temperature at 120 ° C. After stirring at 120 ° C. under a nitrogen atmosphere for 1 hour, the mixture was cooled to 60 ° C., anhydrous sodium sulfide was separated by filtration, and then washed with hexane three times. Then, it was spread on a petri dish and placed in a glass desiccator, the pressure was reduced to 13.3 kPa, hexane was volatilized, and anhydrous sodium sulfide was dried.

  The obtained dried product was collected to obtain 77.20 g (yield 99.50%) of a granular product. The product contained 99.99% anhydrous sodium sulfide and 0.001% water. The particle size of the obtained anhydrous sodium sulfide is shown in Table 1 below.

[Example 2]
240.2 g (1.0 mol of sodium sulfide) of water-containing sodium sulfide nonahydrate (Wako Pure Chemical Industries, Ltd., “Wako first grade”) and 79.20 g of water were added and heating was started. The internal temperature was maintained at 140 ° C for 2 hours. Then, it cooled at 120 degreeC and prepared the aqueous solution which melt | dissolved the produced | generated sodium sulfide.

  Next, using a glass device equipped with a decanter, a liquid mixture of liquid paraffin (Wako Pure Chemical Industries “liquid paraffin”) and normal paraffin (“Super Oil N460” manufactured by JX Energy Co., Ltd.) at a mass ratio of 90:10. 500 g was charged and the temperature was raised to 250 ° C. with stirring.

  Then, 50 g of a hydrous sodium sulfide aqueous solution was charged into the liquid paraffin from a dropping nozzle (nozzle diameter 1 mm) at a rate of 1 g / min while maintaining the temperature at 120 ° C. After stirring at 120 ° C. under a nitrogen atmosphere for 5 hours, the mixture was cooled to 60 ° C., anhydrous sodium sulfide was separated by filtration, and then washed with hexane three times. Then, it was spread on a petri dish and placed in a glass desiccator, the pressure was reduced to 13.3 kPa, hexane was volatilized, and anhydrous sodium sulfide was dried.

  The obtained dried product was collected to obtain 77.20 g (yield 99.50%) of a granular product. The product contained 99.99% anhydrous sodium sulfide and 0.001% water. The particle size of the obtained anhydrous sodium sulfide is shown in Table 1 below.

[Comparative Example 1]
In a flask equipped with a stirrer and a decanter, hydrous sodium hydrosulfide (48.30% sodium hydrosulfide aqueous solution) 116.1 g (sodium hydrosulfide 1.000 mol), 48.64% sodium hydroxide aqueous solution 82.22 g (sodium hydroxide) 1.000 mol) and 147.0 g (1.000 mol) of p-dichlorobenzene as a dispersion medium were added and the temperature rise was started. When the internal temperature reached 140 ° C, distillation of water and p-dichlorobenzene started. The p-dichlorobenzene was separated by a decanter and continuously returned to the system. After a while from the start of distillation, particles began to disperse in the system. After 2 hours, 90.0 g of water was distilled out and the internal temperature rose to 174 ° C., which is the boiling point of p-dichlorobenzene, so that the dehydration was completed. At the end of the dehydration, fine particles of anhydrous sodium sulfide were dispersed in p-dichlorobenzene. After cooling, the particles were collected by filtration and dried under reduced pressure at 100 ° C. for 2 hours to obtain 77.2 g (yield 99.0%) of a granular product. The product contained 98% sodium sulfide and 0.001% water. The particle size of the obtained anhydrous sodium sulfide is shown in Table 1 below.

Claims (6)

A method for producing anhydrous alkali metal sulfide, which comprises a step (1) of dropping a hydrated alkali metal sulfide into liquid paraffin at 250 ° C. or higher. The method for producing anhydrous alkali metal sulfide according to claim 1, wherein the liquid paraffin contains liquid paraffin having an initial boiling point of 300 ° C. or higher. The method for producing an anhydrous alkali metal sulfide according to claim 1, wherein the liquid paraffin is a mixed liquid of liquid paraffin having an initial boiling point of 300 ° C. or higher and normal paraffin having 14 to 16 carbon atoms. The ratio of the liquid paraffin (a) having an initial boiling point of 300 ° C. or higher and the normal paraffin (b) having 14 to 16 carbon atoms in the mixed solution is (a) / (b) = 99/1 on a mass basis. The method for producing anhydrous alkali metal sulfide according to claim 3, which is in the range of 50 to 50/50. The anhydrous alkali metal sulfide according to any one of claims 1 to 4, further comprising a step of removing the liquid paraffin attached to the surface of the anhydrous alkali metal sulfide with an organic solvent that dissolves the liquid paraffin after the step (1). Method of manufacturing things. The method for producing anhydrous alkali metal sulfide according to claim 5, wherein the organic solvent that dissolves the liquid paraffin is a linear hydrocarbon having 6 to 10 carbon atoms.