JP2015143167A - Method for manufacturing lithium aluminate having slender particle shape - Google Patents

Method for manufacturing lithium aluminate having slender particle shape Download PDF

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JP2015143167A
JP2015143167A JP2014017406A JP2014017406A JP2015143167A JP 2015143167 A JP2015143167 A JP 2015143167A JP 2014017406 A JP2014017406 A JP 2014017406A JP 2014017406 A JP2014017406 A JP 2014017406A JP 2015143167 A JP2015143167 A JP 2015143167A
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lithium aluminate
particle shape
elongated particle
reaction
lithium
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純也 深沢
Junya Fukazawa
純也 深沢
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Nippon Chemical Industrial Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
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Abstract

PROBLEM TO BE SOLVED: To provide lithium aluminate having a slender particle shape useful for electrolyte holding plate applications of a molten carbonate fuel cell (MCFC) by an industrially useful method.SOLUTION: There is provided a method for manufacturing lithium aluminate having a slender particle shape including a reaction process of heating and reacting raw material mixture solution containing lithium hydroxide, an aluminum source, alkali hydroxide represented by MOH, where M represents Na or K, and an aqueous solvent with a molar ratio of M/Al of 2 or more and a molar ratio of Li/Al of 1.7 or more.

Description

本発明は、特に溶融炭酸塩型燃料電池（ＭＣＦＣ）の電解質保持板用として有用な細長い粒子形状を有するアルミン酸リチウム（ＬｉＡｌＯ２）の製造方法に関するものである。 The present invention relates to a method for producing lithium aluminate (LiAlO 2 ) having an elongated particle shape particularly useful for an electrolyte holding plate of a molten carbonate fuel cell (MCFC).

ＭＣＦＣの電解質保持板は、６５０℃付近の高温域において炭酸リチウム（Ｌｉ２ＣＯ３）および炭酸カリウム（Ｋ２ＣＯ３）、炭酸ナトリウム（Ｎａ２ＣＯ３）などの混合溶融炭酸塩を保持する目的で使用される。そのため、溶融炭酸塩に対する高い保持性や、粒子形状の安定性、耐アルカリ性、耐熱性などの特性が要求される。このような要求特性を満たす材料として、電解質保持板の構成材料にはアルミン酸リチウムが使用されており、とくに電解質保持力の優れた比較的比表面積の大きい微細なγ―アルミン酸リチウムが好適に用いられてきた。 The MCFC electrolyte holding plate is intended to hold mixed molten carbonates such as lithium carbonate (Li 2 CO 3 ), potassium carbonate (K 2 CO 3 ), and sodium carbonate (Na 2 CO 3 ) in a high temperature range around 650 ° C. Used in. Therefore, characteristics such as high retention with respect to molten carbonate, stability of particle shape, alkali resistance, and heat resistance are required. As a material that satisfies these requirements, lithium aluminate is used as the constituent material of the electrolyte holding plate. In particular, fine γ-lithium aluminate with excellent electrolyte retention and a relatively large specific surface area is suitable. Has been used.

電解質保持性能は、電解質保持板となるアルミン酸リチウムの粒子形状も大きく影響することが知られており、繊維状乃至棒状の細長い粒子形状を有するものを用いることも提案されている（例えば、特許文献１〜３参照）。   It is known that the electrolyte retention performance is greatly influenced by the particle shape of lithium aluminate serving as an electrolyte retention plate, and it is also proposed to use a material having a fiber or rod-like elongated particle shape (for example, a patent) References 1-3).

細長い粒子形状を有するアルミン酸リチウムを得る方法として、例えば水酸化リチウム及び第２のアルカリ金属水酸化物で被覆処理したアルミナ粒子を１００〜４５０℃で反応させる方法（特許文献１参照。）、アルミニウム源、リチウム源及び溶媒を含むスラリーを５０℃から溶媒の沸点以下の温度で乾燥を行いながら反応を行う方法（特許文献２参照。）、アルミニウム源、水酸化リチウム及び少なくとも二種以上の６５０℃以下の融点を有するアルカリ金属塩化物を含む混合物をアルカリ金属塩化物の融点以上７００℃以下の温度に加温してβ―アルミン酸リチウムを得、次いでβ―アルミン酸リチウムからアルカリ金属塩化物を洗浄で除去し、次に５５０〜１０００℃で焼成を行う方法（特許文献３参照。）等が提案されている。   As a method for obtaining lithium aluminate having an elongated particle shape, for example, a method in which alumina particles coated with lithium hydroxide and a second alkali metal hydroxide are reacted at 100 to 450 ° C. (see Patent Document 1), aluminum. A method of performing a reaction while drying a slurry containing a source, a lithium source and a solvent at a temperature from 50 ° C. to the boiling point of the solvent (see Patent Document 2), an aluminum source, lithium hydroxide and at least two or more of 650 ° C. A mixture containing an alkali metal chloride having the following melting point is heated to a temperature not lower than the melting point of the alkali metal chloride and not higher than 700 ° C. to obtain β-lithium aluminate, and then the alkali metal chloride is obtained from β-lithium aluminate. A method of removing by washing and then firing at 550 to 1000 ° C. (see Patent Document 3) has been proposed.

また、下記非特許文献１には、Ａｌ２Ｏ３ナノ粒子、水酸化リチウムとを溶媒中で水熱反応する方法が提案されている。 Non-Patent Document 1 below proposes a method of hydrothermal reaction of Al 2 O 3 nanoparticles and lithium hydroxide in a solvent.

特開昭５３−１３６６３８号公報。JP-A-53-136638. 特開平０６−１０２１４号公報。Japanese Patent Laid-Open No. 06-10214. 特開昭６０−６５７１９号公報。JP-A-60-65719.

Ｉｎｏｒｇａｎｉｃ Ｃｈｅｍｉｓｔｒｙ，Ｖｏｌ．４６，Ｎｏ．８，２００７年，３１７６−３１８４頁。Inorganic Chemistry, Vol. 46, no. 8, 2007, 3176-3184.

上記特許文献１〜３の方法によれば、製造工程が複雑であり、工業的に有利でない。また、上記非特許文献１の方法によれば、反応温度が１５０℃程度の高温を必要とし、更に工業的に有利な方法で、細長い粒子形状を有するアルミン酸リチウムを製造できる方法の開発が望まれていた。   According to the methods of Patent Documents 1 to 3, the production process is complicated, which is not industrially advantageous. Further, according to the method of Non-Patent Document 1, it is desired to develop a method capable of producing lithium aluminate having an elongated particle shape by an industrially advantageous method that requires a high reaction temperature of about 150 ° C. It was rare.

従って、本発明の目的は、溶融炭酸塩型燃料電池（ＭＣＦＣ）の電解質保持板用途として有用な細長い粒子形状を有するアルミン酸リチウムを工業的に有利な方法で提供することにある。   Accordingly, an object of the present invention is to provide lithium aluminate having an elongated particle shape useful as an electrolyte holding plate for a molten carbonate fuel cell (MCFC) in an industrially advantageous manner.

本発明者らは、上記の課題を解決すべく鋭意研究を重ねた結果、水酸化リチウム、アルミニウム源及び水溶媒を含む系に、更にＭＯＨ（式中、ＭはＮａ又はＫを示す。）で表される水酸化アルカリを含有させ、Ｍ／Ａｌ及びＬｉ／Ａｌのモル比を特定範囲に調整したものを原料混合液として用いて反応を行うことにより１２０℃以下の低温でも繊維状の細長い粒子形状を有するアルミン酸リチウムを生成させることが出来ること。また、前記反応混合液に、粒成長させるアルミン酸リチウム種結晶を含有させて粒成長工程を行うことにより、１２０℃以下の低温でも種結晶を粒成長させて棒状の細長い粒子形状を有するアルミン酸リチウムを生成させることが出来ること。更に、粒成長工程を繰り返し行うことにより、所望のさらに大きい棒状のアルミン酸リチウムを段階的に生成させることが出来ることを見出し本発明を完成するに到った。   As a result of intensive studies to solve the above problems, the present inventors have further added MOH (wherein M represents Na or K) to a system containing lithium hydroxide, an aluminum source and an aqueous solvent. Fibrous elongated particles that contain the alkali hydroxide represented and have a molar ratio of M / Al and Li / Al adjusted to a specific range as a raw material mixture to perform the reaction even at a low temperature of 120 ° C. or lower. Capable of producing lithium aluminate having a shape. In addition, by carrying out the grain growth step by containing lithium aluminate seed crystals for grain growth in the reaction mixture, the seed crystals are grown even at a low temperature of 120 ° C. or less to have a rod-like elongated grain shape. Able to generate lithium. Furthermore, it has been found that a desired larger rod-like lithium aluminate can be produced stepwise by repeating the grain growth step, and the present invention has been completed.

即ち、本発明が提供しようとする第１の発明は、水酸化リチウム、アルミニウム源、ＭＯＨ（式中、ＭはＮａ又はＫを示す。）で表される水酸化アルカリ及び水溶媒を含み、Ｍ／Ａｌのモル比が２以上で、Ｌｉ／Ａｌのモル比が１．７以上である原料混合液を加温して反応を行う反応工程を有することを特徴とする細長い粒子形状を有するアルミン酸リチウムの製造方法である。   That is, the first invention to be provided by the present invention includes lithium hydroxide, an aluminum source, an alkali hydroxide represented by MOH (wherein M represents Na or K) and an aqueous solvent, and M An aluminate having an elongated particle shape characterized by having a reaction step in which a reaction is performed by heating a raw material mixture having a molar ratio of / Al of 2 or more and a molar ratio of Li / Al of 1.7 or more This is a method for producing lithium.

また、本発明が提供しようとする第２の発明は、水酸化リチウム、アルミニウム源、ＭＯＨ（式中、ＭはＮａ又はＫを示す。）で表される水酸化アルカリ及び水溶媒を含み、Ｍ／Ａｌのモル比で２以上で、Ｌｉ／Ａｌのモル比が１．７以上である原料混合液に、アルミン酸リチウム種結晶を添加し、加温下に反応を行う粒成長工程を有することを特徴とする細長い粒子形状を有するアルミン酸リチウムの製造方法である。   A second invention to be provided by the present invention includes a lithium hydroxide, an aluminum source, an alkali hydroxide represented by MOH (wherein M represents Na or K) and an aqueous solvent, and M A grain growth step of adding a lithium aluminate seed crystal to a raw material mixed solution having a molar ratio of / Al of 2 or more and a Li / Al molar ratio of 1.7 or more, and reacting under heating. Is a method for producing lithium aluminate having an elongated particle shape.

本発明の細長い粒子形状を有するアルミン酸リチウムの製造方法によれば、工業的に有利な方法で、溶融炭酸塩型燃料電池（ＭＣＦＣ）の電解質保持板用等として有用な繊維状乃至棒状の細長い粒子形状を有するアルミン酸リチウムを提供することが出来る。   According to the method for producing lithium aluminate having an elongated particle shape of the present invention, it is an industrially advantageous method and is a fiber or rod-like elongated useful for an electrolyte holding plate of a molten carbonate fuel cell (MCFC). Lithium aluminate having a particle shape can be provided.

実施例１で得られたアルミン酸リチウムのＳＥＭ写真。2 is an SEM photograph of lithium aluminate obtained in Example 1. 実施例１で得られたアルミン酸リチウムのＳＥＭ写真。2 is an SEM photograph of lithium aluminate obtained in Example 1. 比較例１で得られたアルミン酸リチウムのＳＥＭ写真。2 is an SEM photograph of lithium aluminate obtained in Comparative Example 1. 比較例２で得られたアルミン酸リチウムのＳＥＭ写真。3 is an SEM photograph of lithium aluminate obtained in Comparative Example 2. 実施例１で得られたアルミン酸リチウムのＸ線回折図。2 is an X-ray diffraction pattern of lithium aluminate obtained in Example 1. FIG. 実施例３で得られたアルミン酸リチウムのＳＥＭ写真。4 is an SEM photograph of lithium aluminate obtained in Example 3. 実施例４で得られたアルミン酸リチウムのＳＥＭ写真。4 is an SEM photograph of lithium aluminate obtained in Example 4. FIG. 実施例５で得られたアルミン酸リチウムのＳＥＭ写真。4 is an SEM photograph of lithium aluminate obtained in Example 5. 実施例６で得られたアルミン酸リチウムのＳＥＭ写真。4 is an SEM photograph of lithium aluminate obtained in Example 6. 実施例６で得られたアルミン酸リチウムのＸ線回折図。FIG. 6 is an X-ray diffraction pattern of lithium aluminate obtained in Example 6.

以下、本発明を好ましい実施形態に基づき説明する。
本発明の第１の発明に係る細長い粒子形状を有するアルミン酸リチウムの製造方法は、水酸化リチウム、アルミニウム源、ＭＯＨ（式中、ＭはＮａ又はＫを示す。）で表される水酸化アルカリ（以下、単に「水酸化アルカリ」ということがある）及び水溶媒を含み、Ｍ／Ａｌのモル比が２以上で、Ｌｉ／Ａｌのモル比が１．７以上である原料混合液を加温して反応を行う反応工程を有することを特徴とするものである。 Hereinafter, the present invention will be described based on preferred embodiments.
The method for producing lithium aluminate having an elongated particle shape according to the first invention of the present invention is an alkali hydroxide represented by lithium hydroxide, an aluminum source, MOH (wherein M represents Na or K). (Hereinafter, sometimes simply referred to as “alkali hydroxide”) and a water solvent, and the raw material mixture having an M / Al molar ratio of 2 or more and a Li / Al molar ratio of 1.7 or more is heated. And a reaction step for carrying out the reaction.

本発明では、この反応工程を行うことにより、細長い粒子形状を有するアルミン酸リチウムとして粒子形状が繊維状のアルミン酸リチウム（以下、単に「繊維状のアルミン酸リチウム」ということがある。）を得ることが出来る。
なお、本発明において、繊維状の粒子形状とは、長径が３〜１００μｍで、アスペクト比（長径／短径の比）が２．５〜２５のものを言う。
また、本発明において、アスペクト比は走査型電子顕微鏡写真から無作為に２００個の粒子を選出し求めたものである。 In the present invention, by carrying out this reaction step, lithium aluminate having a fibrous shape as the lithium aluminate having an elongated particle shape (hereinafter sometimes simply referred to as “fibrous lithium aluminate”) is obtained. I can do it.
In the present invention, the fibrous particle shape means one having a major axis of 3 to 100 μm and an aspect ratio (ratio of major axis / minor axis) of 2.5 to 25.
In the present invention, the aspect ratio is obtained by randomly selecting 200 particles from a scanning electron micrograph.

また、反応工程で得られる繊維状のアルミン酸リチウムは、その存在率が７０％以上、好ましくは９０％以上であることが好ましい。
繊維状のアルミン酸リチウムの存在率は、倍率１５００倍で電子顕微鏡観察したときに任意に抽出した２００個について長径が３〜１００μｍでアスペクト比が２．５〜２５の繊維状粒子の存在率［（繊維状粒子の個数／測定粒子の総数）×１００］を示す。 Further, the fibrous lithium aluminate obtained in the reaction step has an abundance of 70% or more, preferably 90% or more.
The abundance of fibrous lithium aluminate is the abundance of fibrous particles having a major axis of 3 to 100 μm and an aspect ratio of 2.5 to 25 with respect to 200 arbitrarily extracted when observed with an electron microscope at a magnification of 1500 times. (Number of fibrous particles / total number of measured particles) × 100].

また、反応工程で得られる繊維状のアルミン酸リチウムのその他の諸物性として、平均長径が３〜１００μｍ、好ましくは５〜５０μｍで、アスペクト比の平均が２．５〜２５、好ましくは３〜２０であることが好ましい。   Further, as other physical properties of the fibrous lithium aluminate obtained in the reaction step, the average major axis is 3 to 100 μm, preferably 5 to 50 μm, and the average aspect ratio is 2.5 to 25, preferably 3 to 20. It is preferable that

反応工程に係るアルミニウム源としては、水酸化アルミニウム、アルミナ等を用いることができる。アルミナには、γ 、δ 、θ 、α などの種々の結晶型があるが、本発明では、何れの結晶型のアルミナであってもよい。本製造方法において、アルミニウム源は、水酸化アルミニウムが反応性及び汎用性の観点から好ましく用いられる。   As the aluminum source for the reaction step, aluminum hydroxide, alumina or the like can be used. Alumina has various crystal types such as γ 1, δ 2, θ 1, and α 2. In the present invention, any crystal type alumina may be used. In this production method, aluminum hydroxide is preferably used as the aluminum source from the viewpoints of reactivity and versatility.

反応工程に係る水酸化アルカリは、水酸化ナトリウム、水酸化カリウムであり、この中で水酸化ナトリウムが汎用性の観点から好ましい。また、水酸化アルカリは、水酸化ナトリウムと水酸化カリウムとを併用して用いてもよい。   The alkali hydroxide according to the reaction step is sodium hydroxide or potassium hydroxide, and sodium hydroxide is preferable from the viewpoint of versatility. The alkali hydroxide may be used in combination with sodium hydroxide and potassium hydroxide.

反応工程に係る水溶媒は、水だけに限らず、水と親水性有機溶媒との混合溶媒であってもよい。   The water solvent related to the reaction step is not limited to water but may be a mixed solvent of water and a hydrophilic organic solvent.

本発明の反応工程でのアルミニウム源と水酸化アルカリの原料混合液への配合量は、Ｍ／Ａｌのモル比が２以上となるよう添加することが必要である。この理由は、アルミニウム源と水酸化アルカリの原料混合液への配合量がＭ／Ａｌのモル比で２未満では、アスペクト比の低い形状となるからである。なお、Ｍ／Ｌｉのモル比の上限値は６とすることが経済性な観点から好ましい。本発明では、特にＭ／Ｌｉのモル比は３〜５とすることが経済的にアスペクト比の高い形状のものを得るという観点から好ましい。   It is necessary to add the compounding amount of the aluminum source and the alkali hydroxide in the raw material mixture in the reaction step of the present invention so that the M / Al molar ratio is 2 or more. The reason for this is that when the blending amount of the aluminum source and the alkali hydroxide in the raw material mixture is less than 2 in terms of the M / Al molar ratio, the shape has a low aspect ratio. The upper limit of the M / Li molar ratio is preferably 6 from the economical viewpoint. In the present invention, it is particularly preferable that the molar ratio of M / Li is 3 to 5 from the viewpoint of economically obtaining a shape having a high aspect ratio.

また、本発明の反応工程での水酸化リチウムとアルミニウム源の原料混合液への配合量は、反応混合液中のＬｉ／Ａｌのモル比が１．７以上となるように添加することが必要である。この理由は、水酸化リチウムとアルミニウム源の原料混合液への配合量がＬｉ／Ａｌのモル比で１．７未満では、アスペクト比が低い形状となるからである。なお、Ｌｉ／Ａｌのモル比の上限値は３とすることが経済的な観点から好ましい。本発明では、特にＬｉ／Ａｌのモル比は１．７〜２．５とすることが経済的にアスペクト比の高い形状のものを得るという観点から好ましい。   Moreover, it is necessary to add the mixing amount of the lithium hydroxide and the aluminum source in the raw material mixture in the reaction step of the present invention so that the molar ratio of Li / Al in the reaction mixture is 1.7 or more. It is. This is because when the blending amount of the lithium hydroxide and the aluminum source in the raw material mixture is less than 1.7 in terms of the Li / Al molar ratio, the aspect ratio is low. The upper limit of the Li / Al molar ratio is preferably 3 from an economical viewpoint. In the present invention, it is particularly preferable that the molar ratio of Li / Al is 1.7 to 2.5 from the viewpoint of economically obtaining a shape having a high aspect ratio.

原料混合液の水酸化リチウムの濃度はリチウム換算で０．５〜５質量％、好ましくは１〜３質量％とすることが反応性及びスラリーの粘度を適切に保つという観点から好ましい。また、原料混合液のアルミニウム源の濃度はアルミ換算で０．５〜５質量％、好ましくは１〜３質量％とすることが反応性及びスラリーの粘度を適切に保つという観点から好ましい。   The concentration of lithium hydroxide in the raw material mixture is preferably 0.5 to 5% by mass, preferably 1 to 3% by mass in terms of lithium, from the viewpoint of maintaining the reactivity and the viscosity of the slurry appropriately. The concentration of the aluminum source in the raw material mixture is preferably 0.5 to 5% by mass, preferably 1 to 3% by mass in terms of aluminum, from the viewpoint of maintaining the reactivity and the viscosity of the slurry appropriately.

反応工程に係る反応は、前記原料混合液を加温し反応を行う。本発明の反応工程では１００〜１５０℃でも反応は進行するが、特に本反応は１２０℃以下でも反応が進行することから、工業的な有利性を考慮して１００〜１２０℃、いっそ好ましくは１００〜１１５℃で反応を行うことが好ましい。
本発明において、オートクレーブ等の耐圧密閉容器を用い、反応系を密閉状態にして反応を行ってもよいが、１２０℃以下で反応を行う場合は開放状態にして大気圧下で反応を行うことができ、工業的に有利となる利点も有する。 The reaction related to the reaction step is performed by heating the raw material mixture. In the reaction process of the present invention, the reaction proceeds even at 100 to 150 ° C. However, since the reaction proceeds even at 120 ° C. or less, the reaction proceeds at 100 to 120 ° C., more preferably 100 in view of industrial advantages. It is preferable to perform the reaction at ˜115 ° C.
In the present invention, the reaction may be carried out in a sealed state using a pressure-resistant airtight container such as an autoclave, but when the reaction is carried out at 120 ° C. or lower, the reaction may be carried out in an open state at atmospheric pressure. And has the advantage of being industrially advantageous.

反応工程での反応時間は本製造方法において臨界的ではなく、細長い粒子形状を有するアルミン酸リチウムが生成するまで十分な時間反応を行う。多くの場合、１時間以上、好ましくは２〜８時間で満足の行く諸物性の繊維状のアルミン酸リチウムを生成させることが出来る。   The reaction time in the reaction step is not critical in the present production method, and the reaction is performed for a sufficient time until lithium aluminate having an elongated particle shape is produced. In many cases, fibrous lithium aluminate having satisfactory physical properties can be produced in 1 hour or longer, preferably 2 to 8 hours.

反応工程の反応終了後、反応液から常法により固液分離し、必要により水等で洗浄、乾燥を行い、細長い粒子形状を有するアルミン酸リチウムとして粒子形状が繊維状のアルミン酸リチウムを得ることが出来る。   After completion of the reaction in the reaction step, solid-liquid separation is performed from the reaction solution by a conventional method, and if necessary, washing and drying with water or the like to obtain lithium aluminate having a fibrous particle shape as lithium aluminate having an elongated particle shape. I can do it.

本発明の第２の発明に係る細長い粒子形状を有するアルミン酸リチウムの製造方法では、前記反応工程の原料混合液に、アルミン酸リチウム種結晶を添加し、粒成長工程により、アルミン酸リチウム種結晶の粒成長を促進し、細長い粒子形状を有するアルミン酸リチウムとして粒子形状が棒状のアルミン酸リチウムを得るものである。
本発明に係る粒成長工程では、例えば、アルミン酸リチウム種結晶として本発明の反応工程で得られる繊維状のアルミン酸リチウムを用いた場合には、１回の反応で、通常、繊維状のアルミン酸リチウム種結晶を長軸方向に、更に３〜１５μｍ粒成長させることが出来る。従って、粒成長工程を繰り返し行うことにより、段階的に粒成長させて所望の長径の大きさの棒状のアルミン酸リチウムを得ることが出来る。
なお、本発明では、粒成長工程を行った細長い粒子形状を有するアルミン酸リチウムを便宜上、棒状のアルミン酸リチウムと言う。 In the method for producing lithium aluminate having an elongated particle shape according to the second invention of the present invention, a lithium aluminate seed crystal is added to the raw material mixture in the reaction step, and the lithium aluminate seed crystal is obtained by a grain growth step. The grain growth is promoted to obtain lithium aluminate having a rod-like particle shape as lithium aluminate having an elongated particle shape.
In the grain growth step according to the present invention, for example, when the fibrous lithium aluminate obtained in the reaction step of the present invention is used as the lithium aluminate seed crystal, it is usually a fibrous alumina in one reaction. The lithium acid seed crystal can be further grown in the major axis direction by 3 to 15 μm grains. Therefore, by repeating the grain growth step, it is possible to grow grains stepwise to obtain a rod-like lithium aluminate having a desired major axis size.
In the present invention, the lithium aluminate having an elongated particle shape subjected to the grain growth step is referred to as a rod-like lithium aluminate for convenience.

本発明の粒成長工程に係るアルミン酸リチウム種結晶は、その粒子形状や製造履歴は特に制限されるものではないが、細長い粒子形状を有するアルミン酸リチウムを用いると効率的に棒状のアルミン酸リチウムを得ることが出来る点で好ましい。
細長い粒子形状を有するアルミン酸リチウムは、本発明の反応工程を経て得られる細長い粒子形状を有するアルミン酸リチウムを好ましく用いることが出来る。また、この粒成長工程は、所望の大きさのものが得られるまで、粒成長工程により得られた細長い粒子形状を有するアルミン酸リチウムを種結晶として用いて繰り返し行うことが出来る。
また、本発明の反応工程や粒成長工程を経て得られる細長い粒子形状を有するアルミン酸リチウムを種結晶として用いることにより、所望の大きさの棒状のアルミン酸リチウムの存在率が高いものが得られる観点からも本発明の反応工程や粒成長工程を経て得られる細長い粒子形状を有するアルミン酸リチウムを種結晶として用いることが特に好ましい。 The lithium aluminate seed crystal according to the grain growth process of the present invention is not particularly limited in its particle shape and production history, but if lithium aluminate having an elongated particle shape is used, it is efficiently rod-shaped lithium aluminate Is preferable in that it can be obtained.
As the lithium aluminate having an elongated particle shape, lithium aluminate having an elongated particle shape obtained through the reaction step of the present invention can be preferably used. In addition, this grain growth step can be repeated using lithium aluminate having an elongated particle shape obtained by the grain growth step as a seed crystal until a desired size is obtained.
Further, by using lithium aluminate having an elongated particle shape obtained through the reaction process and grain growth process of the present invention as a seed crystal, a rod-like lithium aluminate having a desired size can be obtained with a high abundance ratio. Also from the viewpoint, it is particularly preferable to use lithium aluminate having an elongated particle shape obtained through the reaction process and grain growth process of the present invention as a seed crystal.

粒成長工程を繰り返し行う方法としては、例えば、以下の２つの方法を用いることができる。
（Ａ）；第１回目の粒成長工程終了後、得られる細長い粒子形状を有するアルミン酸リチウム（１）を反応液から一旦回収し、新たに原料混合液を調製し、この原料混合液に、種結晶としてアルミン酸リチウム（１）を添加し粒成長工程を行う方法。更に、繰り返す場合は同様な操作を行えばよい。
（Ｂ）；第１回目の粒成長工程終了後、得られる細長い粒子形状を有するアルミン酸リチウム（１）を含む反応スラリーに、水酸化リチウム、アルミニウム源及び必要により水酸化アルカリ及び水溶媒を更に添加して原料混合液を調製し、粒成長工程を行う方法。更に、繰り返す場合は同様な操作を行えばよい。
本発明において、粒成長工程を繰り返して行う場合には、前記（Ｂ）の方法が経済的観点から好ましいが、使用する設備等を考慮して適宜有利な方法を選択すればよい。 As a method for repeatedly performing the grain growth step, for example, the following two methods can be used.
(A); After the completion of the first grain growth step, lithium aluminate (1) having an elongated particle shape obtained is temporarily recovered from the reaction solution, and a raw material mixture is newly prepared. A method in which lithium aluminate (1) is added as a seed crystal and a grain growth step is performed. Furthermore, when it repeats, the same operation should just be performed.
(B); After completion of the first grain growth step, lithium hydroxide, an aluminum source, and optionally an alkali hydroxide and a water solvent are further added to the reaction slurry containing lithium aluminate (1) having an elongated particle shape obtained. A method of preparing a raw material mixed solution by adding and performing a grain growth step. Furthermore, when it repeats, the same operation should just be performed.
In the present invention, when the grain growth step is repeated, the method (B) is preferable from the economical viewpoint, but an advantageous method may be selected as appropriate in consideration of the equipment to be used.

粒成長工程において、アルミン酸リチウム種結晶の原料混合液への添加量は、粒成長工程を繰り返し行う回数や用いるアルミン酸リチウム種結晶の大きさに応じて、適宜好適な範囲の添加量を選択することが好ましい。多くの場合、アルミン酸リチウム種結晶の原料混合液への添加量は、アルミ換算で５〜５００質量％の範囲である。具体的には、例えば、本発明の反応工程で得られる繊維状のアルミン酸リチウムを種結晶として用いる場合は、第１回目の反応では、アルミン酸リチウム種結晶の原料混合液への添加量はアルミ換算で、好ましくは５〜２５質量％、より好ましくは７〜２０質量％とすることが、棒状のアルミン酸リチウム（１）の存在率が高くなる観点及び経済的観点から好ましい。
また、第２回目の繰り返し反応では、例えば、第１回目の反応により得られる棒状のアルミン酸リチウム（１）を種結晶として用いる場合は、アルミン酸リチウム種結晶の原料混合液への配合量はアルミ換算で、好ましくは２０〜７０質量％、より好ましくは３０〜５０質量％とすることが、棒状のアルミン酸リチウム（２）の存在率が高くなる観点及び経済的観点から好ましい。
また、第３回目の繰り返し反応では、例えば、第２回目の反応により得られる棒状のアルミン酸リチウム（２）を種結晶として用いる場合は、アルミン酸リチウム種結晶の原料混合液への配合量はアルミ換算で、好ましくは３０〜１００質量％、より好ましくは５０〜９０質量％とすることが、棒状のアルミン酸リチウム（３）の存在率が高くなる観点及び経済的観点から好ましい。 In the grain growth process, the addition amount of the lithium aluminate seed crystal to the raw material mixture is appropriately selected depending on the number of times the grain growth process is repeated and the size of the lithium aluminate seed crystal used. It is preferable to do. In many cases, the amount of lithium aluminate seed crystals added to the raw material mixture is in the range of 5 to 500% by mass in terms of aluminum. Specifically, for example, when the fibrous lithium aluminate obtained in the reaction step of the present invention is used as a seed crystal, in the first reaction, the amount of lithium aluminate seed crystal added to the raw material mixture is It is preferably 5 to 25% by mass, more preferably 7 to 20% by mass in terms of aluminum, from the viewpoint of increasing the abundance of the rod-like lithium aluminate (1) and from the economical viewpoint.
In the second repetitive reaction, for example, when the rod-shaped lithium aluminate (1) obtained by the first reaction is used as a seed crystal, the blending amount of the lithium aluminate seed crystal in the raw material mixture is In terms of aluminum, it is preferably 20 to 70% by mass, more preferably 30 to 50% by mass, from the viewpoint of increasing the abundance of the rod-like lithium aluminate (2) and from an economical viewpoint.
In the third repetitive reaction, for example, when the rod-like lithium aluminate (2) obtained by the second reaction is used as a seed crystal, the blending amount of the lithium aluminate seed crystal in the raw material mixture is In terms of aluminum, it is preferably 30 to 100% by mass, more preferably 50 to 90% by mass, from the viewpoint of increasing the abundance of the rod-like lithium aluminate (3) and from the economical viewpoint.

本発明の粒成長工程に係る他の反応条件は、前述した本発明の反応工程と同様な反応条件で行うことができる。   Other reaction conditions relating to the grain growth step of the present invention can be carried out under the same reaction conditions as the reaction step of the present invention described above.

粒成長工程の反応終了後、反応液から常法により固液分離し、必要により水等で洗浄、乾燥を行い、細長い粒子形状を有するアルミン酸リチウムとして棒状のアルミン酸リチウムを得ることが出来る。   After the completion of the reaction in the grain growth step, solid-liquid separation is performed from the reaction solution by a conventional method, and washing and drying with water or the like are performed as necessary to obtain a rod-like lithium aluminate having a long and slender particle shape.

本発明に係る反応工程及び粒成長工程で得られる細長い粒子形状を有するアルミン酸リチウムは、β−アルミン酸リチウムであるが、該β−アルミン酸リチウムを焼成工程に付すことによりγ―アルミン酸リチウムに転換することが出来る。この焼成工程により得られるγ―アルミン酸リチウムはβ―アルミン酸リチウムに比べて熱安定性及び化学的安定性にも優れているため、溶融炭酸塩型燃料電池（ＭＣＦＣ）の電解質保持板用として一層好適に用いることが出来る。   The lithium aluminate having an elongated particle shape obtained in the reaction step and the grain growth step according to the present invention is β-lithium aluminate, but by subjecting the β-lithium aluminate to a firing step, γ-lithium aluminate Can be converted. Since γ-lithium aluminate obtained by this firing process is superior in thermal stability and chemical stability compared to β-lithium aluminate, it is used as an electrolyte holding plate for molten carbonate fuel cells (MCFC). It can be used more suitably.

なお、本製造方法では、反応工程及び粒成長工程で得られた細長い粒子形状を有するアルミン酸リチウムは、焼成工程に付すに先立って、得られる細長い粒子形状を有するアルミン酸リチウムを水溶媒で洗浄し、過剰のリチウム、ナトリウム、カリウムのアルカリ分を該アルミン酸リチウムから除去しておくことがβ―アルミン酸リチウムから効率的にγ―アルミン酸リチウムへ転換でき、また高純度のアルミン酸リチウムを得る観点から好ましい。洗浄で用いる水溶媒としては、水だけに限らず、水と親水性有機溶媒との混合溶媒であってもよい。   In this production method, the lithium aluminate having elongated particle shapes obtained in the reaction step and the grain growth step is washed with an aqueous solvent prior to the firing step. The removal of excess lithium, sodium and potassium alkalis from the lithium aluminate can efficiently convert β-lithium aluminate to γ-lithium aluminate, and high purity lithium aluminate From the viewpoint of obtaining. The water solvent used for washing is not limited to water, but may be a mixed solvent of water and a hydrophilic organic solvent.

なお、洗浄方法としては、例えばデカンテーシュンを繰り返して洗浄する方法やリパルブ等の方法を適宜用いることが出来るが、アルミン酸リチウムから過剰のリチウム、ナトリウム、カリウム等のアルカリ分を除去できる方法であれば特にこれらの洗浄方法に限定されるものではない。   As a washing method, for example, a method of repeatedly washing decantation or a method such as repulb can be used as appropriate, but a method capable of removing excess alkali such as lithium, sodium and potassium from lithium aluminate. If there is, it is not limited to these cleaning methods.

焼成工程において、Ｘ線回折的に単相のγ−アルミン酸リチウムを得ることが、熱安定性ならびに化学的安定性の優れたものを得る観点から重要である。焼成工程に係る焼成温度は、７００〜９００℃、好ましくは７５０〜８５０℃である。この理由は、焼成温度が７００℃未満ではβ相とγ相の混相となる傾向があり、一方、焼成温度が９００℃を超えると粒状に形状が変化する傾向があり好ましくないためである。   In the firing step, obtaining a single-phase γ-lithium aluminate in terms of X-ray diffraction is important from the viewpoint of obtaining a product having excellent thermal stability and chemical stability. The firing temperature for the firing step is 700 to 900 ° C, preferably 750 to 850 ° C. This is because if the firing temperature is less than 700 ° C., it tends to be a mixed phase of β phase and γ phase, whereas if the firing temperature exceeds 900 ° C., the shape tends to change into a granular shape, which is not preferable.

なお、焼成温度と焼成時間との関係で、焼成時間は適宜決定することが好ましい。高い温度で行うほど短時間でγ型が生成されやすい傾向がある。このため、適宜、Ｘ線回折分析を行い単相のγ−アルミン酸リチウムが得られているかどうか確認しながら焼成を行うことが好ましい。通常は、上記した焼成温度で０．５〜４０時間焼成を行えば、単相のγ−アルミン酸リチウムを生成させることができる。   Note that it is preferable to appropriately determine the firing time based on the relationship between the firing temperature and the firing time. There is a tendency that γ-type is easily generated in a shorter time as the temperature is higher. For this reason, it is preferable to perform baking while confirming whether or not single-phase γ-lithium aluminate is obtained by performing X-ray diffraction analysis as appropriate. Usually, single-phase γ-lithium aluminate can be produced by firing at the firing temperature described above for 0.5 to 40 hours.

焼成雰囲気は、特に制限されず、不活性ガス雰囲気下、真空雰囲気下、酸化性ガス雰囲気下、大気中の何れであってもよい。   The firing atmosphere is not particularly limited, and may be any of an inert gas atmosphere, a vacuum atmosphere, an oxidizing gas atmosphere, and air.

焼成は所望により何度行ってもよい。また、焼成後、得られる焼成品を必要により粉砕及び／又は解砕を行うことができる。   Firing may be performed as many times as desired. Moreover, after baking, the obtained baked product can be pulverized and / or crushed as necessary.

前記焼成工程を得た細長い粒子形状を有するアルミン酸リチウムは、好ましくはβ型からγ型の結晶形に転換させたものであるが、粒子形状は焼成前と焼成後ではほとんど変化はない。   The lithium aluminate having an elongated particle shape obtained by the firing step is preferably converted from a β-type crystal to a γ-type crystal shape, but the particle shape hardly changes before and after firing.

本発明の製造方法で得られるアルミン酸リチウムは、繊維状乃至棒状の細長い粒子形状を有するアルミン酸リチウムであり、ＭＣＦＣの溶融炭酸塩中において、熱安定性ならびに化学的安定性にも優れる。このため本発明の製造方法で得られる細長い粒子形状を有するアルミン酸リチウムは、ＭＣＦＣの電解質保持板として好適に用いることができる。   The lithium aluminate obtained by the production method of the present invention is a lithium aluminate having a fibrous or rod-like elongated particle shape, and is excellent in thermal stability and chemical stability in MCFC molten carbonate. Therefore, lithium aluminate having an elongated particle shape obtained by the production method of the present invention can be suitably used as an electrolyte holding plate for MCFC.

以下、本発明の実施例を比較例と対比して具体的に説明する。しかし、本発明の範囲はこれら実施例に限定されるものではない。
｛実施例１｝
（反応工程）
水酸化リチウム１水塩６９ｇ、水酸化アルミニウム６１．２ｇ、２５ｗｔ％水酸化ナトリウム６００ｇ、イオン交換水１００ｍｌをテフロン（登録商標）の容器に仕込み、原料混合液を調製した。次いで攪拌下に６℃／ｈの昇温速度で１０５℃まで昇温し、１０５℃で大気圧下に８時間反応を行った。
反応終了後、得られたスラリーをろ過し、１２０℃で乾燥を行って、試料４８．０ｇを得た。 Examples of the present invention will be specifically described below in comparison with comparative examples. However, the scope of the present invention is not limited to these examples.
{Example 1}
(Reaction process)
69 g of lithium hydroxide monohydrate, 61.2 g of aluminum hydroxide, 600 g of 25 wt% sodium hydroxide, and 100 ml of ion-exchanged water were charged into a Teflon (registered trademark) container to prepare a raw material mixture. Next, the temperature was raised to 105 ° C. at a heating rate of 6 ° C./h with stirring, and the reaction was performed at 105 ° C. under atmospheric pressure for 8 hours.
After completion of the reaction, the resulting slurry was filtered and dried at 120 ° C. to obtain 48.0 g of a sample.

｛実施例２｝
（反応工程）
水酸化リチウム１水塩１１．８ｇ、水酸化アルミニウム１２．２ｇ、２５ｗｔ％水酸化ナトリウム１２０ｇ、イオン交換水２０ｍｌをテフロン（登録商標）の容器に仕込み、原料混合液を調製した。次いで攪拌下に６℃／ｈの昇温速度で１０５℃まで昇温し、１０５℃で大気圧下に８時間反応を行った。
反応終了後、得られたスラリーをろ過し、１２０℃で乾燥を行って、試料９．６ｇを得た。 {Example 2}
(Reaction process)
11.8 g of lithium hydroxide monohydrate, 12.2 g of aluminum hydroxide, 120 g of 25 wt% sodium hydroxide, and 20 ml of ion-exchanged water were charged into a Teflon (registered trademark) container to prepare a raw material mixture. Next, the temperature was raised to 105 ° C. at a heating rate of 6 ° C./h with stirring, and the reaction was performed at 105 ° C. under atmospheric pressure for 8 hours.
After completion of the reaction, the obtained slurry was filtered and dried at 120 ° C. to obtain 9.6 g of a sample.

｛比較例１｝
（反応工程）
水酸化リチウム１水塩１９．８ｇ、水酸化アルミニウム１２．２ｇ、イオン交換水１２０ｍｌをテフロン（登録商標）の容器に仕込み、原料混合液を調製した。次いで攪拌下に６℃／ｈの昇温速度で１１５℃まで昇温し、１１５℃で大気圧下に８時間反応を行った。
反応終了後、得られたスラリーをろ過して、１２０℃で乾燥を行って、試料２５．１ｇを得た。 {Comparative Example 1}
(Reaction process)
19.8 g of lithium hydroxide monohydrate, 12.2 g of aluminum hydroxide, and 120 ml of ion-exchanged water were charged into a Teflon (registered trademark) container to prepare a raw material mixture. Next, the temperature was raised to 115 ° C. at a rate of 6 ° C./h with stirring, and the reaction was performed at 115 ° C. under atmospheric pressure for 8 hours.
After completion of the reaction, the obtained slurry was filtered and dried at 120 ° C. to obtain 25.1 g of a sample.

｛比較例２｝
（反応工程）
水酸化リチウム１水塩９．９ｇ、水酸化アルミニウム１２．２ｇ、２５ｗｔ％水酸化ナトリウム１２０ｇ、イオン交換水２０ｍｌをテフロン（登録商標）の容器に仕込み、原料混合液を調製した。次いで攪拌下に６℃／ｈの昇温速度で１０５℃まで昇温し、１０５℃で大気圧下に８時間反応を行った。
反応終了後、得られたスラリーをろ過して、１２０℃で乾燥を行って、試料１０．３ｇを得た。 {Comparative Example 2}
(Reaction process)
9.9 g of lithium hydroxide monohydrate, 12.2 g of aluminum hydroxide, 120 g of 25 wt% sodium hydroxide, and 20 ml of ion-exchanged water were charged into a Teflon (registered trademark) container to prepare a raw material mixture. Next, the temperature was raised to 105 ° C. at a heating rate of 6 ° C./h with stirring, and the reaction was carried out at 105 ° C. under atmospheric pressure for 8 hours.
After completion of the reaction, the obtained slurry was filtered and dried at 120 ° C. to obtain 10.3 g of a sample.

＜アルミン酸リチウムの物性評価＞
実施例及び比較例で得られたアルミン酸リチウム試料について、ＢＥＴ比表面積、長径の長さ、アスペクト比の平均及び繊維状のアルミン酸リチウムの存在率を測定した。その結果を表２に示した。
また、図１〜図４に、実施例１（図１〜２）、比較例１（図３）及び比較例２（図４）で得られたアルミン酸リチウムの走査型電子顕微鏡（ＳＥＭ）写真を示す。
また、実施例及び比較例で得られたアルミン酸リチウムをＸＲＤにより、その結晶系を確認した。実施例１で得られたアルミン酸リチウムのＸ線回折図を図５に示した。
なお、アスペクト比の平均は走査型電子顕微鏡写真から無作為に２００個の粒子を選出し、それぞれの長径と短径の長さを測定し、この測定した長径（Ａ）と短径（Ｂ）の比（Ａ／Ｂ）を粒子ごとに求め、その平均値から算出した。また、長径、平均長径も同様に２００個の粒子の測定値である。
また、繊維状のアルミン酸リチウムの存在率は、倍率１５００倍で電子顕微鏡観察したときに任意に抽出した２００個について長径が３〜１００μｍでアスペクト比（長径／短径の比）が２．５以上の繊維状粒子の存在率［（繊維状粒子の個数／測定粒子の総数）×１００］を示す。 <Evaluation of physical properties of lithium aluminate>
For the lithium aluminate samples obtained in the examples and comparative examples, the BET specific surface area, the length of the major axis, the average aspect ratio, and the abundance of fibrous lithium aluminate were measured. The results are shown in Table 2.
1 to 4 show scanning electron microscope (SEM) photographs of lithium aluminate obtained in Example 1 (FIGS. 1 and 2), Comparative Example 1 (FIG. 3) and Comparative Example 2 (FIG. 4). Indicates.
Moreover, the crystal system of the lithium aluminate obtained in Examples and Comparative Examples was confirmed by XRD. The X-ray diffraction pattern of the lithium aluminate obtained in Example 1 is shown in FIG.
In addition, the average aspect ratio selected 200 particles at random from the scanning electron micrograph, measured the length of each major axis and minor axis, and measured the major axis (A) and minor axis (B). The ratio (A / B) was calculated for each particle and calculated from the average value. Similarly, the major axis and the average major axis are measured values of 200 particles.
The abundance ratio of the fibrous lithium aluminate is such that 200 of the arbitrarily extracted samples when observed with an electron microscope at a magnification of 1500 times have a major axis of 3 to 100 μm and an aspect ratio (major axis / minor axis ratio) of 2.5. The abundance ratio of the above fibrous particles [(number of fibrous particles / total number of measured particles) × 100] is shown.

｛実施例３｝
（粒成長工程；１回目）
テフロン（登録商標）の容器に、水酸化リチウム６９ｇ、水酸化アルミニウム６１．２ｇ、２５ｗｔ％水酸化ナトリウム６００ｇ、イオン交換水１００ｍｌ及び実施例１で得られた繊維状のアルミン酸リチウムをアルミ換算で原料混合液に対して８質量％になるように仕込んだ。次に、攪拌下に６℃／ｈの昇温速度で１０５℃まで昇温し、１０５℃で大気圧下に８時間反応を行った。
反応終了後、得られたスラリーをろ過してアルミン酸リチウムを回収し、１２０℃で乾燥を行って、棒状のアルミン酸リチウム試料５１．９ｇを得た。
実施例１〜２と同様に得られたアルミン酸リチウム試料について、ＢＥＴ比表面積、倍率１５００倍で電子顕微鏡観察したときに任意に抽出した２００個について長径の長さ、アスペクト比の平均及び長径が３〜１００μｍでアスペクト比が２．５以上の棒状粒子の存在率［（棒状粒子の個数／測定粒子の総数）×１００］を求めた。その結果を表３に示した。また、図６に得られたアルミン酸リチウムの走査型電子顕微鏡（ＳＥＭ）写真を示す。 {Example 3}
(Grain growth process; 1st time)
In a Teflon (registered trademark) container, 69 g of lithium hydroxide, 61.2 g of aluminum hydroxide, 600 g of 25 wt% sodium hydroxide, 100 ml of ion-exchanged water, and fibrous lithium aluminate obtained in Example 1 were converted into aluminum. It charged so that it might become 8 mass% with respect to a raw material liquid mixture. Next, the temperature was raised to 105 ° C. at a heating rate of 6 ° C./h with stirring, and the reaction was performed at 105 ° C. under atmospheric pressure for 8 hours.
After completion of the reaction, the resulting slurry was filtered to recover lithium aluminate and dried at 120 ° C. to obtain 51.9 g of a rod-like lithium aluminate sample.
About the lithium aluminate sample obtained in the same manner as in Examples 1 and 2, the BET specific surface area, the length of the major axis, the average aspect ratio and the major axis of the 200 samples arbitrarily extracted when observed with an electron microscope at a magnification of 1500 times The existence ratio [(number of rod-like particles / total number of measured particles) × 100] of rod-like particles having an aspect ratio of 2.5 or more at 3 to 100 μm was determined. The results are shown in Table 3. Moreover, the scanning electron microscope (SEM) photograph of the lithium aluminate obtained in FIG. 6 is shown.

｛実施例４｝
（粒成長工程；２回目）
テフロン（登録商標）の容器に、水酸化リチウム６９ｇ、水酸化アルミニウム６１．２ｇ、２５ｗｔ％水酸化ナトリウム６００ｇ、イオン交換水１００ｍｌ及び実施例３で得られた棒状のアルミン酸リチウムをアルミ換算で原料混合液に対して５０質量％になるように仕込んだ。次に、攪拌下に６℃／ｈの昇温速度で１０５℃まで昇温し、１０５℃で大気圧下に８時間反応を行った。
反応終了後、得られたスラリーを一部ろ過してアルミン酸リチウムを回収し、１２０℃で乾燥を行って、更に粒成長させた棒状のアルミン酸リチウム試料７２．６ｇを得た。
実施例１〜２と同様に得られたアルミン酸リチウム試料について、ＢＥＴ比表面積、倍率１５００倍で電子顕微鏡観察したときに任意に抽出した２００個について、長径の長さ、アスペクト比の平均及び長径が３〜１００μｍでアスペクト比が２．５以上の棒状粒子の存在率［（棒状粒子の個数／測定粒子の総数）×１００］を求めた。その結果を表３に示した。また、図７に得られたアルミン酸リチウムの走査型電子顕微鏡（ＳＥＭ）写真を示す。 {Example 4}
(Grain growth process; second time)
In a Teflon (registered trademark) container, 69 g of lithium hydroxide, 61.2 g of aluminum hydroxide, 600 g of 25 wt% sodium hydroxide, 100 ml of ion-exchanged water, and rod-like lithium aluminate obtained in Example 3 are used as raw materials in terms of aluminum. It charged so that it might become 50 mass% with respect to a liquid mixture. Next, the temperature was raised to 105 ° C. at a heating rate of 6 ° C./h with stirring, and the reaction was performed at 105 ° C. under atmospheric pressure for 8 hours.
After completion of the reaction, the resulting slurry was partially filtered to recover lithium aluminate, dried at 120 ° C., and 72.6 g of a rod-like lithium aluminate sample with further grain growth was obtained.
For the lithium aluminate samples obtained in the same manner as in Examples 1 and 2, the length of the major axis, the average aspect ratio and the major axis of the 200 samples arbitrarily extracted when observed with an electron microscope at a BET specific surface area of 1500 times magnification Was 3 to 100 μm and the abundance of rod-shaped particles having an aspect ratio of 2.5 or more [(number of rod-shaped particles / total number of measured particles) × 100]. The results are shown in Table 3. Moreover, the scanning electron microscope (SEM) photograph of the lithium aluminate obtained in FIG. 7 is shown.

｛実施例５｝
（粒成長工程；３回目）
テフロン（登録商標）の容器に、水酸化リチウム６９ｇ、水酸化アルミニウム６１．２ｇ、２５ｗｔ％水酸化ナトリウム６００ｇ、イオン交換水１００ｍｌ及び実施例４で得られた棒状のアルミン酸リチウムをアルミ換算で原料混合液に対して８０質量％になるように仕込んだ。次に、攪拌下に６℃／ｈの昇温速度で１０５℃まで昇温し、１０５℃で大気圧下に８時間反応を行った。
反応終了後、得られたスラリーをろ過してアルミン酸リチウムを回収し、１２０℃で乾燥を行って、更に粒成長させた棒状のアルミン酸リチウム試料８６．８ｇを得た。
実施例１〜２と同様な手法で得られたアルミン酸リチウム試料について、ＢＥＴ比表面積、倍率１５００倍で電子顕微鏡観察したときに任意に抽出した２００個について、長径の長さ、アスペクト比の平均及び長径が３〜１００μｍでアスペクト比が２．５以上の棒状粒子の存在率［（棒状粒子の個数／測定粒子の総数）×１００］を求めた。その結果を表３に示した。また、図８に得られたアルミン酸リチウムの走査型電子顕微鏡（ＳＥＭ）写真を示す。 {Example 5}
(Grain growth process; third time)
In a Teflon (registered trademark) container, 69 g of lithium hydroxide, 61.2 g of aluminum hydroxide, 600 g of 25 wt% sodium hydroxide, 100 ml of ion-exchanged water, and rod-like lithium aluminate obtained in Example 4 are used as raw materials in terms of aluminum. It charged so that it might become 80 mass% with respect to a liquid mixture. Next, the temperature was raised to 105 ° C. at a heating rate of 6 ° C./h with stirring, and the reaction was performed at 105 ° C. under atmospheric pressure for 8 hours.
After completion of the reaction, the obtained slurry was filtered to recover lithium aluminate, dried at 120 ° C., and 86.8 g of rod-shaped lithium aluminate sample with further grain growth was obtained.
About lithium aluminate samples obtained in the same manner as in Examples 1 and 2, 200 samples arbitrarily extracted when observed with an electron microscope at a BET specific surface area of 1500 times magnification, the length of major axis, the average of aspect ratio And the abundance ratio of the rod-shaped particles having a major axis of 3 to 100 μm and an aspect ratio of 2.5 or more [(number of rod-shaped particles / total number of measured particles) × 100] was determined. The results are shown in Table 3. Moreover, the scanning electron microscope (SEM) photograph of the lithium aluminate obtained in FIG. 8 is shown.

｛実施例6｝
（洗浄工程）
実施例５で得られた反応終了後のスラリー２００ｇを１時間静置後、テフロン（登録商標）の容器から上澄み液を除去した。次いで、イオン交換水をテフロン（登録商標）の容器に１５０ｇ添加し、デカンテーションを行い、上澄み液を除去した。この操作をもう２回繰り返した後、ろ過して棒状のアルミン酸リチウムを回収し、１２０℃で乾燥を行った。
（焼成工程）
前記で得た棒状のアルミン酸リチウムを大気雰囲気で８００℃で７時間焼成した。
実施例１〜２と同様に焼成工程後の棒状のアルミン酸リチウム試料について、ＢＥＴ比表面積、倍率１５００倍で電子顕微鏡観察したときに任意に抽出した２００個について、長径の長さ、アスペクト比の平均及び長径が３〜１００μｍでアスペクト比が２．５以上の棒状粒子の存在率［（棒状粒子の個数／測定粒子の総数）×１００］を求めた。その結果を表３に示した。また、図９に得られたアルミン酸リチウムの走査型電子顕微鏡（ＳＥＭ）写真を示す。また、ＸＲＤ分析の結果、γ型の単相のものが得られていることが確認できた。図１０に得られた棒状のアルミン酸リチウムのＸ線回折図を示す。 {Example 6}
(Washing process)
After leaving the reaction slurry 200 g obtained in Example 5 for 1 hour, the supernatant was removed from the Teflon (registered trademark) container. Next, 150 g of ion-exchanged water was added to a Teflon (registered trademark) container, decanted, and the supernatant was removed. This operation was repeated twice more, followed by filtration to collect rod-like lithium aluminate and drying at 120 ° C.
(Baking process)
The rod-like lithium aluminate obtained above was calcined at 800 ° C. for 7 hours in an air atmosphere.
About the rod-shaped lithium aluminate sample after a baking process similarly to Examples 1-2, about 200 pieces arbitrarily extracted when observed with an electron microscope at a BET specific surface area and a magnification of 1500 times, the length of the major axis and the aspect ratio The abundance [(number of rod-like particles / total number of measured particles) × 100] of rod-like particles having an average and major axis of 3 to 100 μm and an aspect ratio of 2.5 or more was determined. The results are shown in Table 3. Moreover, the scanning electron microscope (SEM) photograph of the lithium aluminate obtained in FIG. 9 is shown. As a result of XRD analysis, it was confirmed that a γ-type single phase was obtained. FIG. 10 shows an X-ray diffraction pattern of the rod-shaped lithium aluminate obtained.


＜安定性の評価＞
実施例６で得られたγ−アルミン酸リチウム試料について、熱安定性及び化学的安定性を評価した。
<Evaluation of stability>
The γ-lithium aluminate sample obtained in Example 6 was evaluated for thermal stability and chemical stability.

＜熱安定性試験＞
実施例６で得られたγ−アルミン酸リチウム試料１０ｇを大気雰囲気にて電気炉に入れ、７５０℃で２００時間加熱し、加熱処理後のアルミン酸リチウム試料について、長径が３〜１００μｍでアスペクト比が２．５以上の棒状粒子の存在率［（棒状粒子の個数／測定粒子の総数）×１００］を求めた。また、加熱処理後のγ−アルミン酸リチウムについて、Ｘ線回折分析を行って異相の存在の有無を確認した。 <Thermal stability test>
10 g of the γ-lithium aluminate sample obtained in Example 6 was placed in an electric furnace in the atmosphere and heated at 750 ° C. for 200 hours. The lithium aluminate sample after the heat treatment had a major axis of 3 to 100 μm and an aspect ratio. The abundance of rod-like particles having a particle size of 2.5 or more [(number of rod-like particles / total number of measured particles) × 100] was determined. Further, the γ-lithium aluminate after the heat treatment was subjected to X-ray diffraction analysis to confirm the presence or absence of heterogeneous phases.

＜化学的安定性試験＞
実施例６で得られたγ−アルミン酸リチウム試料と電解質（成分組成Li2CO3:K2CO3=53:47mol%) を重量比１：２で混合し、体積比で空気／窒素／ＣＯ2＝５０／４０／１０に混合された雰囲気に保持された電気炉中で６７０℃の温度に２０時間加熱した試料を酢酸と無水酢酸を等量混合した溶液で洗浄し、炭酸塩を除去し、ろ過後エタノールで洗浄し、乾燥し、得られた棒状のアルミン酸リチウムについて、長径が３〜１００μｍでアスペクト比が２．５以上の棒状粒子の存在率［（棒状粒子の個数／測定粒子の総数）×１００］を求めた。また、加熱処理後のγ−アルミン酸リチウムについて、Ｘ線回折分析を行って異相の存在の有無を確認した。 <Chemical stability test>
The γ-lithium aluminate sample obtained in Example 6 and the electrolyte (component composition Li 2 CO 3 : K 2 CO 3 = 53: 47 mol%) were mixed at a weight ratio of 1: 2, and the volume ratio of air / nitrogen / A sample heated to 670 ° C. for 20 hours in an electric furnace maintained in an atmosphere mixed with CO 2 = 50/40/10 was washed with a mixed solution of acetic acid and acetic anhydride to remove carbonate. Then, after filtration, washing with ethanol and drying, the obtained rod-shaped lithium aluminate has a ratio of rod-shaped particles having a major axis of 3 to 100 μm and an aspect ratio of 2.5 or more [(number of rod-shaped particles / measured particles ) × 100]. Further, the γ-lithium aluminate after the heat treatment was subjected to X-ray diffraction analysis to confirm the presence or absence of heterogeneous phases.

本発明の細長い粒子形状を有するアルミン酸リチウムの製造方法によれば、工業的に有利な方法で、溶融炭酸塩型燃料電池（ＭＣＦＣ）の電解質保持板用等として有用な繊維状乃至棒状の細長い粒子形状を有するアルミン酸リチウムを提供することが出来る。




According to the method for producing lithium aluminate having an elongated particle shape of the present invention, it is an industrially advantageous method and is a fiber or rod-like elongated useful for an electrolyte holding plate of a molten carbonate fuel cell (MCFC). Lithium aluminate having a particle shape can be provided.




Claims (13)

水酸化リチウム、アルミニウム源、ＭＯＨ（式中、ＭはＮａ又はＫを示す。）で表される水酸化アルカリ及び水溶媒を含み、Ｍ／Ａｌのモル比が２以上で、Ｌｉ／Ａｌのモル比が１．７以上である原料混合液を加温して反応を行う反応工程を有することを特徴とする細長い粒子形状を有するアルミン酸リチウムの製造方法。   Lithium hydroxide, an aluminum source, an alkali hydroxide represented by MOH (wherein M represents Na or K) and an aqueous solvent, the molar ratio of M / Al is 2 or more, and the molar ratio of Li / Al A method for producing lithium aluminate having an elongated particle shape, comprising a reaction step in which a reaction is performed by heating a raw material mixture having a ratio of 1.7 or more. 反応温度が１００〜１２０℃であることを特徴とする請求項１記載の細長い粒子形状を有するアルミン酸リチウムの製造方法。   The method for producing lithium aluminate having an elongated particle shape according to claim 1, wherein the reaction temperature is 100 to 120 ° C. アルミニウム源が水酸化アルミニウムであることを特徴とする請求項１又は２の何れか１項に記載の細長い粒子形状を有するアルミン酸リチウムの製造方法。   The method for producing lithium aluminate having an elongated particle shape according to any one of claims 1 and 2, wherein the aluminum source is aluminum hydroxide. 請求項１乃至３の何れか１項に記載の製造方法で得られることを特徴とする長径が３〜１００μｍで、アスペクト比が２．５〜２５の細長い粒子形状を有するアルミン酸リチウム。   A lithium aluminate having an elongated particle shape having a major axis of 3 to 100 µm and an aspect ratio of 2.5 to 25, which is obtained by the production method according to any one of claims 1 to 3. 水酸化リチウム、アルミニウム源、ＭＯＨ（式中、ＭはＮａ又はＫを示す。）で表される水酸化アルカリ及び水溶媒を含み、Ｍ／Ａｌのモル比が２以上で、Ｌｉ／Ａｌのモル比が１．７以上である原料混合液に、アルミン酸リチウム種結晶を添加し、加温下に反応を行う粒成長工程を有することを特徴とする細長い粒子形状を有するアルミン酸リチウムの製造方法。   Lithium hydroxide, an aluminum source, an alkali hydroxide represented by MOH (wherein M represents Na or K) and an aqueous solvent, the molar ratio of M / Al is 2 or more, and the molar ratio of Li / Al A method for producing lithium aluminate having an elongated particle shape, comprising a grain growth step of adding a lithium aluminate seed crystal to a raw material mixture having a ratio of 1.7 or more and reacting under heating . アルミン酸リチウム種結晶が、細長い粒子形状を有するアルミン酸リチウムであることを特徴とする請求項５記載の細長い粒子形状を有するアルミン酸リチウムの製造方法。   6. The method for producing lithium aluminate having an elongated particle shape according to claim 5, wherein the lithium aluminate seed crystal is lithium aluminate having an elongated particle shape. アルミン酸リチウム種結晶が請求項４記載の細長い粒子形状を有するアルミン酸リチウムであることを特徴とする請求項６記載の細長い粒子形状を有するアルミン酸リチウムの製造方法。   The method for producing lithium aluminate having an elongated particle shape according to claim 6, wherein the lithium aluminate seed crystal is lithium aluminate having the elongated particle shape according to claim 4. 原料混合液へのアルミン酸リチウム種結晶の添加量がアルミ換算で５〜５００質量％であることを特徴とする請求項７記載の細長い粒子形状を有するアルミン酸リチウムの製造方法。   The method for producing lithium aluminate having an elongated particle shape according to claim 7, wherein the amount of the lithium aluminate seed crystal added to the raw material mixture is 5 to 500% by mass in terms of aluminum. 粒成長工程により得られた細長い粒子形状を有するアルミン酸リチウムをアルミン酸リチウム種結晶として用いて粒成長工程を繰り返し行うことを特徴とする請求項６記載の細長い粒子形状を有するアルミン酸リチウムの製造方法。   7. The production of lithium aluminate having an elongated particle shape according to claim 6, wherein the grain growth step is repeated using lithium aluminate having an elongated particle shape obtained by the grain growth step as a lithium aluminate seed crystal. Method. 反応工程後又は粒成長工程後に、得られる細長い粒子形状を有するアルミン酸リチウムの焼成を行う焼成工程を設けることを特徴とする請求項１乃至９の何れか１項に記載の細長い粒子形状を有するアルミン酸リチウムの製造方法。   The elongated particle shape according to any one of claims 1 to 9, further comprising a firing step for firing the obtained lithium aluminate having an elongated particle shape after the reaction step or the grain growth step. Method for producing lithium aluminate. 反応工程後又は粒成長工程後に、得られる細長い粒子形状を有するアルミン酸リチウムを水溶媒で洗浄し、次いで焼成工程に付すことを特徴とする請求項１０記載の細長い粒子形状を有するアルミン酸リチウムの製造方法。   The lithium aluminate having an elongated particle shape according to claim 10, wherein the lithium aluminate having an elongated particle shape obtained after the reaction step or the grain growth step is washed with an aqueous solvent and then subjected to a firing step. Production method. 焼成温度が７００〜９００℃であることを特徴とする１０又は１１の何れか１項に記載の細長い粒子形状を有するアルミン酸リチウムの製造方法。   The method for producing lithium aluminate having an elongated particle shape according to any one of 10 and 11, wherein the firing temperature is 700 to 900 ° C. 生成される細長い粒子形状を有するアルミン酸リチウムがγ―アルミン酸リチウムであることを特徴とする請求項１０乃至１２の何れか１項に記載の細長い粒子形状を有するアルミン酸リチウムの製造方法。   13. The method for producing lithium aluminate having an elongated particle shape according to claim 10, wherein the lithium aluminate having an elongated particle shape is γ-lithium aluminate.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105084399A (en) * 2015-08-11 2015-11-25 无锡桥阳机械制造有限公司 Technology for preparing lithium aluminate powder

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105084399A (en) * 2015-08-11 2015-11-25 无锡桥阳机械制造有限公司 Technology for preparing lithium aluminate powder

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