JP6103499B2 - Method for producing lithium sulfide - Google Patents

Description

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

  In recent years, high-purity metal sulfides are required as intermediate raw materials for ion-conducting solid electrolytes for batteries, engineering plastics, lubricants and chemicals. Among them, lithium sulfide is a white powder having a specific 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 of producing from lithium sulfate, lithium hydroxide and lithium carbonate is known.

As a method for producing lithium sulfide from lithium hydroxide, a method in which a gaseous sulfur source such as hydrogen sulfide or sulfur vapor is reacted with solid lithium hydroxide at a temperature of 130 to 445 ° C. or lower (see Patent Document 1), A method is known in which lithium hydroxide is dissolved in water or an organic solvent and hydrogen sulfide is blown into the reaction to obtain lithium hydrosulfide, followed by dehydrogenation (see Patent Documents 2 to 4). As a method for producing lithium sulfide, a method of reacting hydrogen sulfide with lithium carbonate heated to 600 ° C. has been known (see Patent Document 5).

  However, the method in which hydrogen sulfide gas or the like is reacted with a solid raw material has a problem that high-quality lithium sulfide required for battery materials cannot be obtained. When the reaction is carried out with an organic solvent, impurities derived from the organic solvent remain in the lithium sulfide, and it has been necessary to carry out purification using a large amount of the organic solvent in order to purify it. Moreover, when reacting in water, it was not necessarily an efficient method, such as having to remove water using a lot of energy.

JP 09-278423 A Japanese Patent Laid-Open No. 11-209122 Japanese Patent Application Laid-Open No. 07-330312 International Publication No. 2005/040039 Pamphlet US Pat. No. 4,126,666

Accordingly, an object of the present invention is to provide a method for producing high-purity lithium sulfide safely without purification and solvent removal.

In achieving the above objective, as a result of intensive studies, by reacting lithium carbonate with hydrogen sulfide in the presence of a specific catalyst and hydrogen, it is possible to safely perform high-purity sulfurization without purification or solvent removal. It has been found that lithium can be obtained.

According to the method for producing lithium sulfide of the present invention, high-purity lithium sulfide can be obtained, so that no particular purification or the like is required, which is economically advantageous.

High purity lithium sulfide can be safely synthesized by the method for producing lithium sulfide of the present invention.

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

Lithium sulfide obtained by the production method of lithium sulfide of the invention can be raw materials and engineering plastics, ion-conductive solid electrolytes for batteries, lubricants, be suitably used as an intermediate material for chemical .

Since lithium sulfide obtained by using the method for producing lithium sulfide of the present invention has high purity, when used as an ion conductive solid electrolyte, an ion conductive solid electrolyte having high electric conductivity is obtained, which is preferable.

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, lithium carbonate and hydrogen sulfide are reacted in the presence of a specific catalyst and hydrogen.

The catalyst and the in the present invention, without changing its own chemical, a substance to increase the rate of the chemical equilibrium achieved flop Rachina catalyst, palladium catalyst, a platinum-palladium alloy catalyst. Two or more kinds of catalysts may be used.

  In the present invention, the reaction rate is increased by reacting in the presence of a catalyst. Productivity increases because the reaction is completed in a short time. Moreover, it can be made to react at a low temperature and energy can be saved. Further, the heat resistance of the apparatus can be lowered, and the apparatus can be manufactured with an inexpensive apparatus. In addition, even if the concentration of hydrogen in the atmospheric gas is low, a high-purity metal sulfide can be obtained and can be produced safely without handling a gas with an explosion risk.

  The hydrogen used in the present invention is preferably steam reforming, in which hydrocarbon raw materials such as electrolysis of water, thermal decomposition of hydrogen sulfide, methane, naphtha, methanol and dimethyl ether are reacted with steam on a nickel-based catalyst. What is obtained by a method such as an aquatic gas shift reaction in which carbon dioxide is removed by a garbotol method from hydrogen and carbon dioxide produced by reacting carbon monoxide with water can be used. Hydrogen may be supplied from a cylinder to the reactor, or may be generated in the reaction system by thermally decomposing hydrogen sulfide. It is preferable to use hydrogen in the nascent state generated in the reaction system because the reaction proceeds rapidly and the generation of impurities is suppressed.

  The purity of hydrogen used in the present invention is preferably 80% or more, more preferably 90% or more, and still more preferably 95% or more. A hydrogen purity of 80% or more is preferable because the reaction is sufficiently completed and impurities contained in the resulting metal sulfide are reduced.

  Hydrogen may be supplied after being mixed with an inert gas so as to have an appropriate partial pressure. As the inert gas, a rare gas such as nitrogen, helium, neon, argon, krypton, xenon, or radon is used. Among these, nitrogen is preferable in terms of cost. By introducing hydrogen diluted in an inert gas, the risk of explosion is reduced, the reaction is allowed to proceed gently, or when it is sufficiently heated, it undergoes thermal decomposition, producing hydrogen in the nascent state, and reacting. It is preferable because it promotes or suppresses the generation of impurities. Two or more kinds of inert gases may be used.

In the present invention, the partial pressure of hydrogen brought into contact with lithium carbonate is preferably 0.1% to 99%, more preferably 0.5% to 90%. If it is 0.1% or more, the effect of promoting the reaction and reducing impurities can be obtained, and if it is 99% or less, it can coexist with hydrogen sulfide gas at a sufficient concentration.

In the present invention, lithium carbonate acid.

The particle size of lithium carbonate is preferably 0.1 μm to 1 mm, more preferably 1 μm to 100 μm. If the particle size is 0.1 μm or more, the reaction rate is large because the surface area is large. Moreover, if it is 1 mm or less, it accompanies atmospheric gas and is preferable, without scattering outside the apparatus.

Lithium carbonate may be dried prior to reaction with hydrogen sulfide. Drying is preferable because the resulting lithium sulfide 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, and further preferably 450 ° C. to 725 ° C. 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 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 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. When the purity of hydrogen sulfide is 80% or more, the reaction is sufficiently completed, and there are few impurities in the resulting metal sulfide.

In the present invention, the supply amount of hydrogen sulfide brought into contact with lithium carbonate is preferably 0.5 to 8 mol times, more preferably 0.8 to 6 mol times with respect to the charged amount of lithium carbonate. is there. If it is 0.5 mol times or more, high-purity lithium sulfide can be 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.

  Hydrogen sulfide may be mixed with an inert gas and supplied so as to have an appropriate partial pressure. As the inert gas, a rare gas such as nitrogen, helium, neon, argon, krypton, xenon, or radon is used. Among these, nitrogen is preferable in terms of cost. By diluting and introducing hydrogen sulfide into an inert gas, the risk of explosion is suppressed, the reaction is allowed to proceed gently, or when hydrogen sulfide is sufficiently heated, it is thermally decomposed, and This is preferable because it may promote the reaction and suppress the generation of impurities. Two or more kinds of inert gases may be used.

  The partial pressure of hydrogen sulfide is preferably 0.1% to 99%. If it is 0.1% or more, the reaction proceeds in a short time, and if it is 99% or less, other coexistence can be achieved with a sufficient partial pressure, and effects such as improvement in reaction rate and reduction in impurities can be obtained. is there.

The temperature at which lithium carbonate and hydrogen sulfide are reacted is preferably 200 ° C to 725 ° C. More preferably, it is 300-700 degreeC. More preferably, it is 400 degreeC-675 degreeC. If temperature is 200 degreeC or more, reaction will fully advance, and if it is 725 degrees C or less, lithium carbonate of a raw material will melt | dissolve and a particle | grain will not adhere, and it is preferable.

Lithium carbonate may be reacted in motion. The state in which the lithium carbonate is in motion is a state in which the lithium carbonate is in a macro motion that can be visually confirmed, and is a state in which the lithium carbonate particles are in motion due to an external force. . The force is applied by gravity, introduction of gas into a container filled with metal carbonate, or movement of a container filled with lithium carbonate . Therefore, the micro motion represented by the Brownian motion is not included. For example, the fixed bed reaction in which lithium carbonate is stopped and reacted by flowing gas is not in a state where lithium carbonate is in motion.

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

In the method for producing lithium sulfide of the present invention, the reaction between lithium carbonate and hydrogen sulfide is preferably a gas-solid reaction. A gas-solid reaction is a reaction between a gas and a solid. More preferably, the method for producing lithium sulfide of the present invention is a gas-solid reaction in which hydrogen sulfide, which is a gas, is reacted with solid lithium carbonate , and since no solvent is used, it is not necessary to remove the solvent. This is economically advantageous because no waste liquid such as a solvent is generated.

  As the reaction apparatus in the present invention, a moving bed, a rolling bed, a fluidized bed and an air flow bed are preferably used.

The moving bed in the present invention is a form of a reaction apparatus in which lithium carbonate is continuously supplied from the top of the tower, slowly lowered, and brought into contact with a gas in a countercurrent or a parallel 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 lithium carbonate is moved by moving a container or lattice filled with lithium carbonate 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 a metal carbonate is suspended and suspended in a gas to be brought into contact with the gas and reacted 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.

  These reactor configurations may be combined with two or more types.

Reactor forms for reacting lithium carbonate in motion are described in pages 959 to 964 of the Chemical Engineering Handbook, Revised Sixth Edition. Among them Utatedoso is the motion state of the feed rate or lithium carbonate gas, without being affected by the specific gravity and particle diameter of the lithium carbonate particles can be freely set, and performing the continuous reaction Further, it is preferable because the particles do not stick. A rotary kiln is preferably used as the device.

In the method for producing lithium sulfide of the present invention, a gas other than an inert gas (hereinafter referred to as other gas) is used as long as the object of obtaining high-purity lithium sulfide can be achieved without purification or removal of the solvent. Yes) may coexist. Other gases are substances that are gases at the reaction temperature. Specifically, oxygen, carbon dioxide, nitrous oxide, nitrogen monoxide, nitrogen dioxide, nitrogen trifluoride, ammonia, carbon monoxide, phosgene , Arsine, diarsenic trioxide, diarsenic trichloride, arsenic trifluoride, arsenic pentafluoride, boron trichloride, boron tribromide, boron trifluoride, diborane, germanium tetrachloride, germane, phosphorus trichloride, three Phosphorus fluoride, phosphorus pentafluoride, phosphine, phosphorus oxychloride, acetylene, stibine, hydrogen selenide, tin tetrachloride, hydrogen telluride, titanium tetrachloride, silicon tetrachloride, trichlorosilane, dichlorosilane, silicon tetrafluoride, Silane, tungsten hexafluoride, chlorine, bromine, hydrogen chloride, hydrogen fluoride, chlorosulfonic acid, hydrogen cyanide, sulfur dioxide, sulfur tetrafluoride, sulfur hexafluoride, Yellow vapor, natural gas, formaldehyde, acrolein, methanol, methyl mercaptan, benzene, phenol, methylene chloride, chloroform, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene, trichlorofluoromethane, trimethylamine, fluoroform, propane , Hexafluoropropane, hexafluoroethane, fluorocarbons and the like. Other gases may be generated in the reaction system. Two or more kinds of other gases may be used.

  The partial pressure of other gases is preferably 0.1% to 90%. If it is 0.1% or more, the reaction proceeds in a short time, and if it is 90% or less, hydrogen sulfide and the like can coexist with a sufficient partial pressure, and the desired reaction rate acceleration, impurity reduction, etc. An effect is obtained.

For the purpose of homogenizing the lithium sulfide particles obtained by the method for producing lithium sulfide of the present invention, a crushing treatment may be performed. 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 particle size of the particles obtained by the crushing treatment is preferably 0.1 μm to 1 mm, more preferably 1 μm to 100 μm.

According to the method for producing lithium sulfide of the present invention, generation of impurities is suppressed, and high-purity lithium sulfide can be obtained. The total of sulfites, sulfates, and thiosulfates, which are impurities contained in the obtained lithium sulfide , can be preferably suppressed to 0.5 wt% or less, more preferably 0.3 wt% or less. Since high-purity lithium sulfide can be obtained, no purification or the like is required, which is economically advantageous.

  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.

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.

Flow rate: 1.25 mL / min
Suppressor: ASRS-300 (130 mA / recycle)
Column temperature: 30 ° C
Introduced volume: 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 is filled in a reactor equipped with an eye plate with 9 holes with a diameter of 2 mm in the center of a quartz glass tube with an inner diameter of 21 mm and a length of 500 mm, and a platinum / palladium alloy catalyst (NS-6A, JGC Universal). Ltd.) 0.02 g, and lithium carbonate (high purity lithium carbonate PLC-4N, manufactured by Pacific Lithium Co., Ltd.) 2.01 g were charged. 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. From the gas supply pipe at the bottom of the reactor, 1% hydrogen-containing nitrogen (manufactured by Japan Fine Products Co., Ltd.) was introduced as an atmosphere gas at 25 ml / min and heated to 625 ° C. by external heating. After confirming that the temperature reached 625 ° C., hydrogen sulfide gas (manufactured by Japan Fine Products Co., Ltd.) was supplied at a supply rate of 2 ml / min along with the atmospheric gas and reacted for 10 hours. After completion of the reaction, the mixture was cooled to room temperature to obtain 1.19 g of white massive lithium sulfide. When X-ray diffraction was measured, a peak of lithium sulfide was obtained, and it was confirmed that the product was lithium sulfide. The conversion rate of the obtained lithium sulfide was 100%, the impurity content measured by ion chromatography was 0.3 wt% lithium sulfite, 0.1 wt% lithium sulfate, and less than 0.1 wt% lithium thiosulfate, and the total content was 0.00. It was 5 wt%.

(Example 2)
In Example 1, 1.17 g of lithium sulfide was obtained by synthesizing in the same manner as in Example 1 except that the atmospheric gas was changed from 1% hydrogen-containing nitrogen to 3% hydrogen-containing nitrogen. The conversion rate of the obtained lithium sulfide was 97%, and the impurity contents measured by ion chromatography were 0.2 wt% lithium sulfite, 0.1 wt% lithium sulfate, and lithium thiosulfate, respectively, and the total content was 0.3 wt% %Met.

(Example 3)
In Example 1, except that the atmosphere gas was changed from 1% hydrogen-containing nitrogen to 3% hydrogen-containing nitrogen and the amount of catalyst charged was changed from 0.02 g to 0.05 g, synthesis was performed in the same manner as in Example 1, 1.47 g of lithium sulfide was obtained. The conversion rate of the obtained lithium sulfide was 56%, and the impurity contents measured by ion chromatography were 0.1 wt% lithium sulfite, 0.1 wt% lithium sulfate, and lithium thiosulfate, respectively, and the total content was 0.2 wt% %Met.

(Comparative Example 1)
In Example 1, 1.16 g of lithium sulfide was obtained by synthesizing in the same manner as in Example 1 except that the atmosphere gas was changed from nitrogen containing 1% hydrogen to nitrogen. The conversion rate of the obtained lithium sulfide was 86%, and the impurity contents measured by ion chromatography were 0.4 wt% lithium sulfite, 1.0 wt% lithium sulfate, and 0.1 wt% lithium thiosulfate, respectively. It was 5 wt%.

(Comparative Example 2)
In Example 1, the synthesis was performed in the same manner as in Example 1 except that the atmospheric gas was changed from nitrogen containing 1% hydrogen to nitrogen, and the flow rate of the atmospheric gas was changed from 25 ml / min to 50 ml / min. 13 g was obtained. The conversion rate of the obtained lithium sulfide was 90%, and the impurity contents measured by ion chromatography were lithium sulfite 0.4 wt%, lithium sulfate 1.4 wt%, and lithium thiosulfate, respectively, and a total of 1.8 wt% %Met.

(Comparative Example 3)
In Example 1, instead of the platinum / palladium alloy catalyst NS-6A (manufactured by JGC Universal Co., Ltd.), 16.2 g of zirconia balls having no catalytic activity (YTZ balls, manufactured by Nikkato Co., Ltd.) were used, and the atmosphere gas was 1 By synthesizing in the same manner as in Comparative Example 1 except that the hydrogen content was changed from nitrogen containing% hydrogen to nitrogen, 1.02 g of lithium sulfide was obtained. The conversion rate of the obtained lithium sulfide was 100%, and the impurity contents measured by ion chromatography were 0.3 wt% lithium sulfite, 1.1 wt% lithium sulfate, and 0.1 wt% lithium thiosulfate, respectively. It was 5 wt% (Comparative Example 4)
In Example 1, instead of the platinum / palladium alloy catalyst NS-6A (manufactured by JGC Universal Co., Ltd.), a comparative example except that 16.2 g of zirconia balls having no catalytic activity (YTZ balls, manufactured by Nikkato Co., Ltd.) was used. 1 was obtained in the same manner as 1 to obtain 1.22 g of lithium sulfide. The conversion rate of the obtained lithium sulfide was 81%, and the impurity content measured by ion chromatography was 0.2 wt% lithium sulfite, 0.9 wt% lithium sulfate, and lithium thiosulfate, respectively, and the total content was 1.1 wt% % (Comparative Example 5)
In Example 1, instead of the platinum / palladium alloy catalyst NS-6A (manufactured by JGC Universal Co., Ltd.), 16.2 g of zirconia balls having no catalytic activity (YTZ balls, manufactured by Nikkato Co., Ltd.) were used, and the atmosphere gas was 1 By synthesizing in the same manner as in Example 1 except that the hydrogen content was changed from 3% hydrogen-containing nitrogen to 3% hydrogen-containing nitrogen, 1.02 g of lithium sulfide was obtained. The conversion rate of the obtained lithium sulfide was 100%, and the impurity contents measured by ion chromatography were 0.4 wt% lithium sulfite, 0.2 wt% lithium sulfate, and 0.1 wt% lithium thiosulfate, respectively, for a total of 0.001. It was 7 wt%.

  Tables 2 and 3 summarize the experimental conditions of Examples and Comparative Examples and the list of quality.

Claims (2)

A method for producing lithium sulfide in which lithium carbonate and hydrogen sulfide are reacted in the presence of a catalyst and hydrogen, wherein the catalyst is any one of a platinum catalyst, a palladium catalyst, and a platinum / palladium alloy catalyst . The method for producing lithium sulfide according to claim 1, wherein the reaction temperature is 200 to 725 ° C.