JP6150229B2 - Method for producing lithium sulfide - Google Patents

Description

  The present invention relates to a method for producing lithium sulfide useful as an intermediate raw material for ion conductive solid electrolytes for batteries, engineering plastics, lubricants and chemicals.

  In recent years, lithium sulfide has attracted attention as an intermediate raw material for ion conductive solid electrolytes for batteries, engineering plastics, lubricants and chemicals. Lithium sulfide is a white powder with a characteristic odor, and is used as a raw material for polymerization of polyarylene sulfide resin and a raw material for ion conductive solid electrolyte for batteries.

  Lithium sulfide is not produced as a natural mineral product due to its deliquescent nature, and is thus synthesized by synthesis from other lithium compounds. Conventionally, a method for producing metal lithium, lithium hydroxide, and lithium carbonate is known.

  As a method for producing lithium sulfide from metallic lithium, a method of reacting solid metallic lithium with sulfur vapor or hydrogen sulfide at 300 ° C. to 1100 ° C. has been known (Patent Document 1).

  Moreover, as a method of producing lithium sulfide from lithium hydroxide, a method of reacting solid lithium hydroxide with a gaseous sulfur source such as hydrogen sulfide or sulfur vapor at a temperature of 130 to 445 ° C. or lower (Patent Document 2) A method is known in which lithium hydroxide is dissolved in water or an organic solvent, hydrogen sulfide is blown into the reaction to obtain lithium hydrosulfide, and then dehydrogenated (Patent Documents 3 to 5).

  Furthermore, as a method for producing lithium sulfide from lithium carbonate, a method in which lithium carbonate and hydrogen sulfide are subjected to a gas-solid reaction at a temperature of 450 ° C. to 700 ° C. (Patent Documents 6 and 7) has been known.

  However, when metallic lithium is used as a raw material, solid metallic lithium has a smaller surface area than a thin film or powder, and cannot be sufficiently brought into contact with a gaseous sulfur source, resulting in a long reaction time. Furthermore, since lithium metal is highly active and reacts with moisture, oxygen, and the like at room temperature, processing into a thin film or powder is disadvantageous in terms of cost.

  The method of producing lithium sulfide from lithium hydroxide is based on a gas-liquid reaction in which lithium hydroxide is dissolved in water or a solvent and reacted by blowing hydrogen sulfide, and solid lithium hydroxide and a gaseous sulfur source are directly combined. It can be divided into those due to gas-solid reaction. The gas-liquid reaction is disadvantageous in terms of cost because a large amount of energy is required to remove the solvent, and the removed solvent needs to be treated as waste. On the other hand, in the case of the gas-solid reaction, lithium hydroxide has deliquescence, so the particles are fused and it is difficult to obtain a raw material having a particle diameter of less than 0.1 mm, and the reaction proceeds because the surface area is small. It sometimes became difficult. In addition, it is difficult to handle the raw materials because it is necessary to handle in a dry atmosphere in order to prevent particle fusion and moisture content.

  When lithium carbonate is used as a raw material, the reaction conditions are extremely harsh conditions in which moisture is generated by reaction when heated from 450 ° C. to 700 ° C. in the presence of hydrogen sulfide, and can withstand the conditions. There was a subject that there were few materials and it was difficult to produce a manufacturing apparatus.

JP 09-110404 A JP 09-278423 A Japanese Patent Application Laid-Open No. 07-330312 International Publication No. 2005/040039 Pamphlet JP 2011-84438 A US Pat. No. 4,126,666 JP2013-75816A

  Accordingly, an object of the present invention is to provide a method for producing lithium sulfide under relatively mild conditions without removing the solvent.

  In achieving the above object, as a result of intensive studies, it was found that lithium sulfide can be obtained under relatively mild conditions by reacting lithium oxide and hydrogen sulfide without purification and removal of the solvent.

  The method for producing lithium sulfide of the present invention is a method of reacting lithium oxide and a hydrogen sulfide-containing gas. By this method, lithium sulfide can be obtained under relatively mild conditions without removing the solvent.

  Furthermore, since the reaction is performed under relatively mild conditions, the burden on the equipment material is small, and the equipment can be produced with an inexpensive material, which is economically advantageous.

  Since lithium oxide is used as a raw material, it does not need to be deliquescent like lithium hydroxide or to remove crystal water or adhering water, and is easy to handle. Since lithium oxide does not deliquesce, it can be easily crushed and crushed and fine particles can be obtained. Fine particles have a large surface area and a high reaction rate. Since it can be manufactured in a short time, it is economically advantageous.

  According to the method for producing lithium sulfide of the present invention, the obtained lithium sulfide is produced in powder form. Since the shape of the raw material lithium oxide is inherited as it is and can be taken out from the reaction vessel, workability is good.

  The metal sulfide obtained by using the method for producing lithium sulfide of the present invention can be suitably used as an engineering plastics raw material, an ion conductive solid electrolyte for batteries, a lubricant, or an intermediate raw material for chemicals. .

  Below, the manufacturing method of the lithium sulfide of this invention is described in detail.

  In the method for producing lithium sulfide of the present invention, hydrogen sulfide and lithium oxide are reacted.

  The hydrogen sulfide used in the present invention is, for example, separated and recovered from a gas containing hydrogen sulfide obtained by hydrodesulfurization reaction of fuel oil such as petroleum, or reacted with hydrogen and sulfur vapor in a heating reactor. And those obtained by allowing an inorganic acid to act on iron sulfide or sodium sulfide.

  Hydrogen sulfide may be supplied from a cylinder to the reactor or may be generated in the reaction system. The use of nascent hydrogen sulfide generated in the reaction system is preferable because the reaction proceeds rapidly.

  The partial pressure of hydrogen sulfide is preferably 0.1% to 99%. Preferably, it is 1% to 85%, and more preferably 3% to 70%. If it is 0.1% or more, the reaction proceeds in a short time, and if it is 99% or less, the amount of unreacted hydrogen sulfide discharged is small, which is economically advantageous.

  The purity of hydrogen sulfide used in the present invention is preferably 80% or more, more preferably 90% or more, and still more preferably 95% or more. It is preferable that the purity of hydrogen sulfide is 80% or more because the reaction is sufficiently completed, and there are few impurities in the obtained lithium sulfide.

  In the present invention, the supply amount of hydrogen sulfide to be brought into contact with lithium oxide is preferably 0.5 to 8 mol times, more preferably 0.8 to 6 mol times with respect to the charged amount of lithium oxide. is there. More preferably, it is 1.0 mol times-4 mol times. If it is 0.5 mol times or more, lithium sulfide is obtained, and if it is 8 mol times or less, the reaction time is short and the loss of hydrogen sulfide is reduced, which is economical.

  The lithium oxide used in the present invention is an oxide of lithium. For example, it can be obtained by burning metallic lithium in air or oxygen, thermal decomposition of lithium hydroxide, decarboxylation of lithium carbonate, or the like.

  The particle diameter of lithium oxide is preferably 20 mesh (aperture opening 0.85 mm) or less, and more preferably 60 mesh (aperture opening 0.25 mm) or less. If it is 20 mesh or less, since the surface area is large, the reaction rate is large and preferable.

  Lithium oxide usually contains dissimilar metals and other impurities, but preferably has a purity as high as possible in order to suppress side reactions.

  Lithium oxide may be dried prior to reaction with hydrogen sulfide. Drying is preferable because the obtained lithium oxide does not agglomerate and the by-product of hydrosulfide is suppressed. The end point of drying can be performed by measuring the outdoor atmosphere gas.

  The drying temperature is preferably 100 ° C. or higher, more preferably 200 ° C. or higher. A temperature of 100 ° C. or higher is preferable because water is sufficiently removed.

  As the atmospheric gas during drying, hydrogen, nitrogen, or a rare gas such as helium, neon, argon, krypton, xenon, or radon is preferably used. Among these, nitrogen and hydrogen-containing nitrogen are preferable because they are inexpensive. Two or more kinds of atmospheric gases at the time of drying may be used.

The temperature at the time of making lithium oxide and hydrogen sulfide react is 150 degreeC- 450 degreeC . If temperature is 150 degreeC or more, reaction will fully advance .

  The time for contacting lithium oxide and hydrogen sulfide is not particularly limited as long as unreacted lithium oxide does not remain.

  The reaction of lithium oxide and hydrogen sulfide according to the present invention is as follows.

Li ₂ O + H ₂ S → Li ₂ S + H ₂ O
Therefore, water is by-produced. In the present invention, the reaction temperature is 0.99 ° C. to 450 ° C.. When the reaction temperature is 150 ° C. to 450 ° C., the water is water vapor. In the method for producing lithium sulfide of the present invention, it is preferable to carry out the reaction while supplying a gas such as hydrogen sulfide into the reaction system and discharging the water vapor in the reaction system, thereby preventing corrosion of the equipment and adhesion of particles. More preferably, the water vapor is discharged together with the gas.

  In the present invention, other gases may coexist as long as the object of obtaining lithium sulfide can be achieved under relatively mild conditions without removing the solvent. For other gases, it is preferable to use a reducing gas because impurities contained in lithium sulfide are reduced. Examples include hydrogen, carbon monoxide, methane and other gaseous alkanes.

  In the present invention, preferably, solid lithium oxide and gaseous hydrogen sulfide are gas-solid reacted. The gas-solid reaction is economically advantageous because there is no need to remove the solvent and no waste liquid is produced.

  A preferable gas-solid reaction reactor in the present invention has any one of a fixed bed, a moving bed, a rolling bed, a fluidized bed, and an air flow bed.

  The fixed bed in the present invention is an apparatus in which a solid component of a raw material is filled in a reaction apparatus, and a raw material gas is continuously supplied and reacted. For the fixed layer, an axial flow method, a radial flow method, a parallel flow method, or the like is used. As the heat transfer method of the fixed bed reactor, an adiabatic type, a multistage adiabatic type, a self-heat exchange type, and a multi-tube heat exchange type are suitably used. Examples of the apparatus include a fixed furnace, a pusher kiln, a mesh belt kiln, and a roller hearth kiln.

  The moving bed in the present invention is a form of a reaction apparatus in which metal carbonate particles are continuously supplied from the top of the tower, gently lowered, and brought into contact with gas in a countercurrent or cocurrent flow to react. Examples of the apparatus include a vertical moving bed and a cross-flow vertical moving bed. The vertical moving bed is applied to metal refining, cement production, coal gasification, etc., and the cross-flow vertical moving bed is applied to exhaust gas treatment.

  The rolling layer in the present invention is a reaction device form in which a metal carbonate is rolled by moving a container or a lattice filled with metal carbonate particles and brought into contact with a gas to react. Examples of the apparatus include a sliding grate and a rotary kiln. Sliding grate and rotary kiln are applied to cement production, metal refining, thermal decomposition, etc., respectively.

  The fluidized bed in the present invention is a reaction device form in which metal carbonate particles are suspended and suspended in a gas and brought into contact with the gas to cause a reaction by ejecting the gas upward. The gas force acting on the solid particles balances with gravity, and the whole behaves like a uniform fluid. Examples of the reaction apparatus include a bubble fluidized bed, a spouted bed, and a high-speed fluidized bed. The bubbling fluidized bed is applied to coal combustion, waste treatment, particle synthesis, and thermal decomposition, and the spouted bed is applied to coating, particle synthesis, and the like.

  The airflow layer in the present invention is a reactor configuration in which lithium oxide having a large specific surface area is uniformly mixed with a gas and both are passed through the reaction atmosphere at substantially the same speed. The airflow layer is applied to pulverized coal combustion, gas phase synthesis, coal gasification, and the like.

  The gas-solid reaction reactor in the present invention may have a configuration in which two or more kinds of moving bed, rolling layer, fluidized bed, and airflow layer are combined.

  The reactor for gas-solid reaction in the present invention is preferably a reactor having a fixed bed and a rolling bed. The gas supply speed and the movement state of lithium oxide can be freely set without being influenced by the specific gravity or particle diameter of the lithium oxide particles, and the reaction can be continuously performed. Is preferred because it does not stick. As the gas-solid reaction reactor in the present invention, a fixed furnace, a pusher kiln, a roller hearth kiln, and a rotary kiln are more preferably used.

  It is desirable to use a material that can withstand hydrogen sulfide containing highly corrosive moisture as the material of the equipment. Specifically, materials other than metals, such as an alloy which has nickel, cobalt, chromium, etc. as a main component, titanium, and glass, are mentioned. Examples of alloys mainly composed of nickel, cobalt, chromium, etc. include Hastelloy C-22, Hastelloy C-276, Hastelloy B, Hastelloy B-2, Hastelloy G, Hastelloy G-3, Inconel 600, Inconel 625, Incoloy 825. MC alloy and UMCo50. Examples of titanium include TP270, TP340, and TP480. Quartz glass is mentioned as materials other than metals, such as glass. Of these, quartz glass and titanium are preferable because of their good corrosion resistance.

  In the method for producing lithium sulfide of the present invention, the reaction may be carried out under atmospheric pressure or under high pressure.

  The lithium sulfide obtained by the method for producing lithium sulfide of the present invention may be crushed for the purpose of homogenizing particles. A general apparatus can be used for the apparatus used for the crushing treatment. Specifically, a bead mill, a ball mill, a high-speed rotary mill, a jet mill, and the like. The average particle diameter of the particles obtained by the crushing treatment is preferably 0.1 μm to 1 mm, more preferably 1 μm to 300 μm. More preferably, it is 20 micrometers-200 micrometers. If the average particle size is 0.1 μm or more, the surface area is large and the reaction rate is high. Moreover, if it is 1 mm or less, it is hard to scatter, it does not adhere to the wall surface of an apparatus with static electricity, and is easy to handle. Further, the bulk density is increased, and the weight that can be charged in the apparatus having a constant volume is increased, so that the productivity is increased.

  Hereinafter, specific examples will be described. In addition, the analytical value of the metal sulfide obtained in each example was measured by the following method.

Purity measurement Measured by oxidation-reduction titration. A sample solution was obtained by dissolving 0.2 g of lithium sulfide with 25 ml of ion-exchanged water. 50 ml of 0.1N iodine solution was added to 10 ml of the sample solution to reduce lithium sulfide, and the remaining iodine was back titrated with 0.1N sodium thiosulfate solution to determine purity.

Ion chromatography measurement device: ICS-2000 (manufactured by Nippon Dionex)
Column: IonPac AG-11-HC / IonPac AS11-HC
Eluent: The following KOH gradient was used. The curve is a gradient density change pattern, and the curve 5 is a pattern in which the density changes linearly.

Flow rate: 1.25 mL / min
Suppressor: ASRS-300 (130 mA / recycle)
Column temperature: 30 ° C
Amount introduced: 25 μL
Measurement method A 37% formalin solution was diluted to 1% with ultrapure water, and then degassed for 10 minutes using an ultrasonic cleaner and an aspirator to obtain a 1% formalin aqueous solution. About 0.1 g of the sample was precisely weighed and made up to 100 ml with 1% formalin solution. Samples were measured immediately after adjustment.

  The conversion rate described in Examples and Comparative Examples is a value obtained by quantifying carbonate ions in the product by ion chromatography, converting to lithium carbonate, obtaining a weight ratio with respect to the whole sample, and subtracting from 100.

Example 1
Glass wool was filled into a reactor in which a center plate of a 21 mm inner diameter and 500 mm long quartz glass tube was fitted with a glass plate with nine holes with a diameter of 2 mm, and lithium oxide (purity 97%, manufactured by Sigma-Aldrich) ) Was filled with 1.02 g. A gas supply pipe and an exhaust pipe are attached to the upper and lower parts of the reactor, and protective tubes are attached so that the thermocouple reaches the vicinity of the eye plate. That is a fixed bed reaction. Nitrogen was introduced at 50 ml / min from the gas supply pipe at the bottom of the reactor and heated to 450 ° C. by external heating. After confirming that the temperature reached 450 ° C., hydrogen sulfide (manufactured by Japan Fine Products Co., Ltd.) was supplied along with nitrogen at a supply rate of 2 ml / min, and reacted for 6.5 hours while exhausting the exhaust gas. It was. After completion of the reaction, the mixture was cooled to room temperature to obtain 1.01 g of a brown lump solid. When X-ray diffraction was measured, a lithium sulfide peak was obtained, and it was confirmed that lithium sulfide was generated. The purity of the obtained lithium sulfide was 58.3%, and the impurity contents measured by ion chromatography were 2.4 wt% lithium sulfite, 0.1 wt% lithium sulfate, and 0.1 wt% lithium thiosulfate, respectively. It was 6 wt%.

(Example 2)
In Example 1, except that the supply rate of nitrogen was changed from 50 ml / min to 25 ml / min, the reaction was performed in the same manner as in Example 1 to obtain 1.11 g of a brown lump solid. The purity of the solid lithium sulfide obtained was 36.0%, and the impurity content measured by ion chromatography was 0.7 wt% lithium sulfite, 0.1 wt% lithium sulfate, and 0.1 wt% lithium thiosulfate, respectively. The total was 0.9 wt%.

( Comparative Example 1 )
In Example 1, the reaction was carried out in the same manner as in Example 1 except that the nitrogen supply rate was changed from 50 ml / min to 25 ml / min, and the reaction temperature was changed from 450 ° C. to 500 ° C. .81 g was obtained. The purity of the obtained lithium sulfide was 56.8%, and the impurity contents measured by ion chromatography were 2.1 wt% lithium sulfite, 1.1 wt% lithium sulfate, and 0.1 wt% lithium thiosulfate, respectively. It was 3 wt%.

(Comparative Example 2 )
In Example 1, the reaction was performed in the same manner as in Example 1 except that lithium oxide was changed to lithium carbonate (PLC-4N, manufactured by Pacific Lithium Corporation) and the reaction time was changed from 6.5 hours to 5 hours. A white powder was obtained, but lithium sulfide was not detected in redox titration, and lithium sulfide was not obtained.

Claims (3)

A method for producing lithium sulfide, in which lithium oxide and hydrogen sulfide are reacted at 150 to 450 ° C. 2. The method for producing lithium sulfide according to claim 1, wherein solid lithium oxide and gaseous hydrogen sulfide are subjected to a gas-solid reaction. The method for producing lithium sulfide according to claim 1 or 2, wherein the reaction is carried out while removing water vapor from the reactor.