JP2004256366A - Manufacturing method of activated alumina shaped article - Google Patents
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は活性アルミナ成形体の製造方法に関し、詳しくはマクロ細孔容積が大きく高ＢＥＴ比表面積の活性アルミナ成形体を容易に製造し得る方法に関する。
【０００２】
【従来の技術】
活性アルミナ成形体は、乾燥剤、吸着剤、触媒、触媒担体などとして有用であり、細孔半径０．３μｍ以上で外部と連通したマクロ細孔の容積が大きく、ＢＥＴ比表面積の高いものが望まれている。
【０００３】
かかるマクロ細孔の容積が大きく、ＢＥＴ比表面積も比較的大きな活性アルミナ成形体の製造方法として、特許文献１（特開昭４９−６００６号公報）および特許文献２（特開平８−２４５２８１号公報）には、再水和性アルミナ粉末および有機起孔剤を水と混練し、賦形し、焼成する方法が開示されており、有機起孔剤としては、繊維状有機物、ポリメタクリル酸エステルなどのような、焼成時に焼失し、また水を殆ど吸収しないものが開示されている。
【０００４】
しかし、かかる従来の製造方法では、マクロ細孔の容積を大きくしようとすると有機起孔剤の使用量を増やす必要があり、有機起孔剤の使用量を増やすと、得られる活性アルミナ成形体のＢＥＴ比表面積が小さくなり易いという問題があった。
【０００５】
【特許文献１】特開昭４９−６００６号公報
【特許文献２】特開平８−２４５２８１号公報
【０００６】
【発明が解決しようとする課題】
そこで本発明者は、大きなマクロ細孔容積を示し、高ＢＥＴ比表面積の活性アルミナ成形体を容易に製造し得る方法を開発するべく鋭意検討した結果、再水和性アルミナ粉末および中心粒子径５０〜５００μｍの吸水性樹脂粉末を混合し粉砕してブレーン比表面積が１００００〜１３５００ｃｍ２／ｇの混合粉砕物を得、これに水を加え、賦形し、再水和させ、焼成することとすれば、マクロ細孔容積が大きく、高ＢＥＴ比表面積の活性アルミナ成形体が容易に得られることを見出し、本発明に至った。
【０００７】
【課題を解決するための手段】
すなわち本発明は、再水和性アルミナ粉末を中心粒子径５０μｍ以上の吸水性樹脂粉末と混合し粉砕してブレーン比表面積が１３５００ｃｍ２／ｇ以下の混合粉砕物を得、
得られた混合粉砕物に水を加え、賦形して再水和性アルミナ粉末成形体を得、
得られた再水和性アルミナ粉末成形体を再水和させて再水和アルミナ成形体を得、
得られた再水和アルミナ成形体を焼成することを特徴とする活性アルミナ成形体の製造方法を提供するものである。
【０００８】
【発明の実施の形態】
本発明の製造方法では、先ず再水和性アルミナ粉末、吸水性樹脂粉末および水を混合して再水和性アルミナ粉末組成物を得る。
【０００９】
再水和性活性アルミナ粉末とは、水和し得るアルミナであって粉末状のものである。再水和性アルミナとしては、例えばρ相を主結晶相とするρ−アルミナ、非晶質の不定形アルミナなどが挙げられる。ρ−アルミナはχ相を含んでいてもよい。かかる再水和性アルミナ粉末の粒子径は好ましくは１０μｍ以上、１００μｍ以下程度、さらに好ましくは２０μｍ以上、８０μｍ以下程度である。
【００１０】
再水和性アルミナ粉末は、例えばギブサイト型水酸化アルミニウムを瞬間仮焼する方法により得ることができる。ギブサイト型水酸化アルミニウムはバイヤー法により工業的に得られる三水酸化アルミニウムであって、通常はナトリウム含有量が酸化物換算で０．０２〜１質量％程度のものを用いることができる。また、かかる再水和性アルミナ粉末は、市販のものから適宜選択して用いることもできる。
【００１１】
吸水性樹脂粉末は、水分を吸収して膨潤し得る樹脂の粉末であって、例えばポリアクリル酸塩系吸水性樹脂、ポリアルキレンオキサイド系吸水性樹脂、グラフトデンプン系吸水性樹脂、ポリビニルアルコール系吸水性樹脂、ビニルアセトアミド重合体系吸水性樹脂、ポリアスパラギン酸塩系吸水性樹脂、イソブチレン・無水マレイン酸共重合物金属塩系吸水性樹脂などの粉末が挙げられる。かかる吸水性樹脂の吸水倍率は通常１００以上２００以下程度である。
【００１２】
かかる吸水性樹脂としては中心粒子径が５０μｍ以上、好ましくは８０μｍ以上であり、通常５００μｍ以下、好ましくは２００μｍ以下程度のものが用いられる。中心粒子径が５０μｍ未満では、マクロ細孔が形成しにくくなる傾向にある。また、５００μｍを超えると、マクロ細孔の径が大きくなり過ぎて、得られる活性アルミナ成形体の機械的強度が低下する傾向にある。目的とする活性アルミナ成形体が、例えば触媒担体などとして用いられる場合には、不純物金属の含有量を少なくする点で、吸水性樹脂として金属含有量の少ないものを用いることが好ましい。
【００１３】
かかる吸水性樹脂粉末の使用量は、再水和性アルミナ粉末１００質量部に対して、より容易にマクロ細孔が形成される点で０．１質量部以上であることが好ましく、またＢＥＴ比表面積が大きくなり易い点で０．５質量部以下程度であることが好ましい。
【００１４】
本発明の製造方法では、かかる再水和性アルミナ粉末および吸水性樹脂粉末を混合粉砕する。混合粉砕は通常、乾燥状態で行なわれる。混合粉砕する方法は特に限定されるものではなく、例えばナフターミキサー、オムニミキサー、コンクリートミキサー、リボンミキサーなどの混合装置を用いても混合した後に、粉砕してもよいし、粉砕装置に再水和性アルミナ粉末および吸水性樹脂を投入して、混合しながら粉砕してもよい。粉砕装置としては、例えばボールミル、振動ミル、ジェットミル、流動媒体ミル、自由粉砕機、擂潰機などを用いることができる。また、混合粉砕はバッチ式で行なってもよいし、連続的に行なってもよいが、連続的に混合粉砕することで工業的に安価に混合粉砕することができて、好ましい。混合し粉砕することにより、通常は再水和性アルミナ粉末が粉砕されると同時に吸水性樹脂も粉砕される。
【００１５】
混合し粉砕することにより得られる混合粉砕物のブレーン比表面積は１３５００ｃｍ２／ｇ以下である。混合粉砕物のブレーン比表面積が１３５００ｃｍ２／ｇを超えると、得られる活性アルミナ成形体のマクロ細孔の容積が小さくなる傾向にある。また、８０００ｃｍ２／ｇ未満では、得られる活性アルミナ成形体の機械的強度が低下する傾向にあるため、８０００ｃｍ２／ｇ以上であることが好ましい。
【００１６】
混合粉砕物に水を加える。加える水の量は、吸水性樹脂粉末が飽和し得る程度であって、賦形し得る程度であり、再水和性アルミナ粉末および吸水性樹脂粉末の合計量１００質量部に対して通常は５０質量部以上、８０質量部以下程度である。
【００１７】
水と共に、添加剤を加えてもよい。添加剤としては、例えば非再水和性アルミナ粉末、例えばα−アルミナ粉末、アルミニウムの塩、シリカ、粘土、タルク、ベントナイト、ゼオライト、コーディエライト、チタニア、アルカリ金属の塩、アルカリ土類金属の塩、希土類金属の塩、ジルコニア、ムライト、シリカアルミナなどが挙げられる。
【００１８】
水を加えた後、賦形することで、再水和性アルミナ成形体を得る。水を加え、賦形するには、例えば混合し粉砕した後の混合粉砕物をマルメライザー、転動造粒機などの成形装置を用いて水を加えながら賦形してもよい。これらの成形装置を用い、水を加えながら造粒することで、球状の再水和性アルミナ成形体を得ることができる。
【００１９】
また、混合粉砕物に水を加えて混練したのち、押出成形法、金型による圧縮成形法などの通常の方法により賦形してもよい。賦形後の最水和性アルミナ粉末成形体の形状は、目的の活性アルミナ成形体の用途に応じて適宜選択され、例えば球状、円柱状、リング状、板状、ハニカム状、塊状などが挙げられる。
【００２０】
かくして得られた再水和性アルミナ粉末成形体を再水和させて再水和アルミナ成形体を得る。再水和させるには、例えば再水和性アルミナ粉末成形体を水蒸気と接触させればよい。再水和性アルミナ粉末成形体は通常、０℃以上、２００℃以下、より機械的強度に優れた活性アルミナ成形体が得られる点で、好ましくは８０℃以上で水蒸気と接触させる。接触させる時間は、用いた再水和性アルミナ粉末の種類、形状、粒子径、再水和性アルミナ粉末成形体の形状、大きさなどによって異なるが、例えば１分以上１週間以下程度である。再水和性アルミナ粉末成形体は水蒸気と接触することで、そのままの形状で再水和して再水和アルミナ成形体となる。
【００２１】
得られた再水和アルミナ成形体は、酸性水溶液と接触させてもよい。酸性水溶液と接触させることで、ナトリウムなどのアルカリ金属成分が溶出してナトリウム分の少ない活性アルミナ成形体を得ることができる。また、得られる活性アルミナ成形体の表面を酸性にすることができる。また、ランタンなどのランタノイド元素、バリウムなどのアルカリ土類金属、珪素化合物、セリウム化合物、ジルコニウム化合物などの水溶液と接触させてもよい。かかる水溶液と接触させることで、耐熱性に優れた活性アルミナ成形体を得ることができる。
【００２２】
得られた再水和アルミナ成形体を焼成する。焼成温度は通常３００℃以上１０００℃以下程度、好ましくは３５０℃以上８００℃以下程度であり、添加物として塩を用いた場合にはその分解温度以上の温度で焼成することが好ましい。焼成方法は特に限定されるものではなく、燃焼ガス、電気ヒーターによる間接加熱、遠赤外線による加熱などの通常の加熱方法で加熱することで焼成できる。
【００２３】
再水和アルミナ成形体には再水和において付着した水分が含まれていることもあるが、かかる水分を除去した後に焼成してもよい。水分を除去するには、例えば自然乾燥、熱風乾燥、真空乾燥などの通常の方法で乾燥すればよい。
【００２４】
かくして活性アルミナ成形体を得るが、得られた活性アルミナ成形体は、例えば細孔半径０．３μｍ以上で外部と連通したマクロ細孔の容積が０．０４ｃｍ３／ｇ以上０．２ｃｍ３／ｇ以下、ＢＥＴ比表面積が１００ｍ２／ｇ以上４００ｍ２／ｇ以下程度である。
【００２５】
かかる活性アルミナ成形体は、マクロ細孔容積が大きく、またＢＥＴ比表面積も高いので、そのままで、例えば吸着剤などとして用いることができる。また触媒担体としても有用であり、貴金属等の触媒成分を担持して触媒として用いることもできる。
【００２６】
【発明の効果】
本発明の製造方法によれば、細孔半径０．３μｍ以上のマクロ細孔の容積が大きく、ＢＥＴ比表面積も高い活性アルミナ成形体を容易に製造することができる。
【００２７】
【実施例】
以下、実施例によって本発明をより詳細に説明するが、本発明は係る実施例に限定されるものではない。
【００２８】
なお、各実施例において得た活性アルミナ成形体は、以下の方法で評価した。
マクロ細孔容積：水銀圧入法によって測定した細孔分布から、細孔半径０．３μｍ以上１００μｍ以下の細孔の容積を求めた。
ＢＥＴ比表面積：マウンテック社製ＢＥＴ比表面積測定装置を用いて測定した。
中心粒子径：Ｌｅｅｄｓ ＆ Ｎｏｒｔｈｒｕｐ社製マイクロトラック粒度分布計を用いて質量基準で求めた。
ブレーン比表面積：島津製作所社製ブレーン比表面積測定装置「ＳＳ−１００」を用いて、恒圧空気式測定法により求めた。
充填密度：ＪＩＳ Ｈ １９０２に準拠して、資料をメスシリンダーに取り、タッピングを１００回行なった後の試料容積から求めた。
耐圧強度：試料１０粒の直径をマイクロメーターで測定した後、硬度試験機にて破壊強度を測定し、断面積あたりの強度を求め、平均値を求めた。
【００２９】
実施例１
バイヤー法により得たギブサイト型水酸化アルミニウムの粉末〔中心粒子径は４０μｍ、水分含有量は１質量％以下〕を７００℃の熱ガス気流中に投入して瞬間仮焼して、再水和性アルミナ粉末〔粒子径は２０μｍ〜１００μｍの範囲〕を得た。この再水和性アルミナ粉末の結晶系は、ρ相およびχ相であった。
【００３０】
上記で得た再水和性アルミナ粉末１００質量部を吸水性樹脂粉末〔クラレ社製「ＫＩゲル−２０１Ｋ」、中心粒子径は１２０μｍ、吸水倍率１８３倍〕０．３質量部とナフターミキサーを用いて１時間かけて混合したのち、振動ボールミルを用いて粉砕した。粉砕後の混合粉砕物のブレーン比表面積は１３０００ｃｍ２／ｇであった。直径１ｍの皿型造粒機を用いて上記で得た粉砕物に水をスプレーしながら加えて造粒して、直径１〜３ｍｍの球状の再水和性アルミナ粉末成形体を得た。得られた再水和性アルミナ粉末成形体をオートクレーブ中で大気圧下に１０５℃で飽和水蒸気を含む空気と４時間接触させて再水和アルミナ成形体を得た。得られた再水和アルミナ成形体をアルミナ製ルツボに入れ、電気炉で４００℃に昇温し、同温度で２時間保持して焼成して、活性アルミナ成形体を得た。
【００３１】
得られた活性アルミナ成形体のマクロ細孔容積は０．０６ｃｍ３／ｇ、ＢＥＴ比表面積は２７８ｍ２／ｇであり、充填密度は０．７１ｇ／ｃｍ３、耐圧強度は１４４０Ｎ／ｃｍ２であった。
【００３２】
比較例１
吸水性樹脂粉末を用いない以外は実施例１と同様に操作して、活性アルミナ成形体を得た。得られた活性アルミナ成形体のマクロ細孔容積は０．０３ｃｍ３／ｇ、ＢＥＴ比表面積は２７０ｍ２／ｇであり、充填密度は０．８１ｇ／ｃｍ３、耐圧強度は１７１０Ｎ／ｃｍ２であった。
【００３３】
比較例２
吸水性樹脂粉末〔ＫＩゲル２０１Ｋ〕に代えて、吸水性樹脂粉末〔クラレ社製「ＫＩゲル−２０１−Ｆ２」、中心粒子径は１８μｍ、吸水倍率１８４倍〕０．３質量部を用いる以外は実施例１と同様に操作して、活性アルミナ成形体を得た。得られた活性アルミナ成形体のマクロ細孔容積は０．０２ｃｍ３／ｇ、ＢＥＴ比表面積は２７５ｍ２／ｇであり、充填密度は０．７８ｇ／ｃｍ３、耐圧強度は１７７０Ｎ／ｃｍ２であった。
【００３４】
比較例３
ブレーン比表面積が１４００００ｃｍ２／ｇとなるまで粉砕した以外は実施例１と同様に操作して、活性アルミナ成形体を得た。得られた活性アルミナ成形体のマクロ細孔容積は０．０３ｃｍ３／ｇ、ＢＥＴ比表面積は３０８ｍ２／ｇであり、充填密度は０．７７ｇ／ｃｍ３、耐圧強度は１３２０Ｎ／ｃｍ２であった。
【００３５】
実施例２
吸水性樹脂粉末の使用量を０．４質量部とし、再水和アルミナ成形体の焼成温度を８５０℃とする以外は実施例１と同様に操作して、活性アルミナ成形体を得た。得られた活性アルミナ成形体のマクロ細孔容積は０．０７ｃｍ３／ｇ、ＢＥＴ比表面積は１０６ｃｍ３／ｇであり、充填密度は０．６７ｇ／ｃｍ３、耐圧強度は５９０Ｎ／ｃｍ２であった。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing an activated alumina molded article, and more particularly, to a method for easily producing an activated alumina molded article having a large macropore volume and a high BET specific surface area.
[0002]
[Prior art]
Activated alumina compacts are useful as desiccants, adsorbents, catalysts, catalyst carriers, etc., and those with large pore radii of 0.3 μm or more, large macropores communicating with the outside, and high BET specific surface areas are desired. It is rare.
[0003]
As a method for producing an activated alumina molded body having a large macropore volume and a relatively large BET specific surface area, Patent Document 1 (Japanese Patent Application Laid-Open No. 49-6006) and Patent Document 2 (Japanese Patent Application Laid-Open No. 8-245281) ) Discloses a method in which a rehydratable alumina powder and an organic pore-forming agent are kneaded with water, shaped, and calcined. Examples of the organic pore-forming agent include fibrous organic substances and polymethacrylates. Such materials that burn off during firing and hardly absorb water are disclosed.
[0004]
However, in such a conventional manufacturing method, it is necessary to increase the amount of the organic pore-forming agent in order to increase the volume of the macropores. There is a problem that the BET specific surface area tends to be small.
[0005]
[Patent Document 1] JP-A-49-6006 [Patent Document 2] JP-A-8-245281
[Problems to be solved by the invention]
The inventor of the present invention has conducted intensive studies to develop a method that can easily produce an activated alumina molded body having a large macropore volume and a high BET specific surface area. A water-absorbent resin powder of ~ 500 µm is mixed and pulverized to obtain a mixed and pulverized product having a Blaine specific surface area of 10,000 to 13500 cm 2 / g, to which water is added, shaped, rehydrated, and fired. For example, they have found that an activated alumina molded article having a large macropore volume and a high BET specific surface area can be easily obtained, and the present invention has been accomplished.
[0007]
[Means for Solving the Problems]
That is, in the present invention, a re-hydratable alumina powder is mixed with a water-absorbent resin powder having a central particle diameter of 50 μm or more and pulverized to obtain a mixed and pulverized product having a Blaine specific surface area of 13500 cm 2 / g or less.
Water is added to the obtained mixed and pulverized product, and shaped to obtain a rehydratable alumina powder molded body,
The obtained rehydratable alumina powder compact was rehydrated to obtain a rehydrated alumina compact,
An object of the present invention is to provide a method for producing an activated alumina molded body, which comprises firing the obtained rehydrated alumina molded body.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
In the production method of the present invention, first, a rehydratable alumina powder composition, a water-absorbent resin powder and water are mixed to obtain a rehydratable alumina powder composition.
[0009]
The rehydratable activated alumina powder is alumina that can be hydrated and is in a powder form. Examples of the rehydratable alumina include ρ-alumina having a ρ phase as a main crystal phase, amorphous amorphous alumina, and the like. ρ-alumina may include a χ phase. The particle size of the rehydratable alumina powder is preferably about 10 μm or more and about 100 μm or less, more preferably about 20 μm or more and about 80 μm or less.
[0010]
The rehydratable alumina powder can be obtained, for example, by a method of instantaneously calcining gibbsite-type aluminum hydroxide. Gibbsite-type aluminum hydroxide is aluminum trihydroxide obtained industrially by the Bayer method, and usually has a sodium content of about 0.02 to 1% by mass in terms of oxide. In addition, such rehydratable alumina powder can be appropriately selected from commercially available ones and used.
[0011]
The water-absorbing resin powder is a resin powder capable of absorbing water and swelling, such as a polyacrylate-based water-absorbing resin, a polyalkylene oxide-based water-absorbing resin, a graft starch-based water-absorbing resin, and a polyvinyl alcohol-based water-absorbing resin. Powders such as a water-soluble resin, a vinylacetamide polymer-based water-absorbent resin, a polyaspartate-based water-absorbent resin, and an isobutylene / maleic anhydride copolymer metal salt-based water-absorbent resin. The water absorption capacity of such a water-absorbent resin is usually about 100 or more and 200 or less.
[0012]
As such a water-absorbent resin, those having a center particle diameter of 50 μm or more, preferably 80 μm or more, and usually 500 μm or less, preferably about 200 μm or less are used. If the center particle diameter is less than 50 μm, it tends to be difficult to form macropores. On the other hand, if it exceeds 500 μm, the diameter of the macropores becomes too large, and the mechanical strength of the obtained activated alumina molded article tends to decrease. When the intended activated alumina molded body is used, for example, as a catalyst carrier, it is preferable to use a water-absorbing resin having a low metal content from the viewpoint of reducing the content of impurity metals.
[0013]
The amount of the water-absorbing resin powder used is preferably 0.1 part by mass or more in that macropores are more easily formed with respect to 100 parts by mass of the rehydratable alumina powder, and the BET ratio The content is preferably about 0.5 part by mass or less from the viewpoint that the surface area is easily increased.
[0014]
In the production method of the present invention, the rehydratable alumina powder and the water-absorbent resin powder are mixed and pulverized. The mixing and grinding is usually performed in a dry state. The method of mixing and pulverizing is not particularly limited.For example, after mixing using a mixing device such as a naphtha mixer, an omni mixer, a concrete mixer, a ribbon mixer, or the like, pulverization may be performed. The humid alumina powder and the water-absorbing resin may be charged and pulverized while mixing. As the pulverizer, for example, a ball mill, a vibration mill, a jet mill, a fluid medium mill, a free pulverizer, a crusher, and the like can be used. Further, the mixing and pulverization may be performed in a batch system or may be performed continuously. However, continuous mixing and pulverization is preferable because industrially inexpensive mixing and pulverization can be performed. By mixing and pulverizing, usually, the rehydratable alumina powder is pulverized and the water-absorbent resin is also pulverized.
[0015]
The mixed pulverized product obtained by mixing and pulverizing has a Blaine specific surface area of 13500 cm 2 / g or less. When the Blaine specific surface area of the mixed and pulverized product exceeds 13500 cm 2 / g, the volume of macropores of the obtained activated alumina molded article tends to be small. If it is less than 8000 cm 2 / g, the mechanical strength of the obtained activated alumina molded body tends to decrease, so that it is preferably 8000 cm 2 / g or more.
[0016]
Add water to the mixed grounds. The amount of water to be added is such that the water-absorbent resin powder can be saturated and can be shaped, and is usually 50 parts by mass based on 100 parts by mass of the total amount of the rehydratable alumina powder and the water-absorbent resin powder. It is about not less than 80 parts by mass.
[0017]
Additives may be added with the water. Additives include, for example, non-rehydratable alumina powders, such as α-alumina powder, aluminum salts, silica, clay, talc, bentonite, zeolites, cordierite, titania, alkali metal salts, alkaline earth metal salts Salts, salts of rare earth metals, zirconia, mullite, silica alumina, and the like.
[0018]
After adding water, the resulting mixture is shaped to obtain a rehydratable alumina molded body. In order to add and shape water, for example, the mixed and pulverized product after mixing and pulverization may be shaped while adding water using a molding device such as a marmellaizer or a tumbling granulator. By using these molding apparatuses and granulating while adding water, a spherical rehydratable alumina molded article can be obtained.
[0019]
Alternatively, after mixing and kneading the mixed and pulverized product with water, the mixture may be shaped by an ordinary method such as an extrusion molding method or a compression molding method using a mold. The shape of the rehydratable alumina powder compact after shaping is appropriately selected depending on the intended use of the activated alumina compact, and examples thereof include spherical, columnar, ring, plate, honeycomb, and lump shapes. Can be
[0020]
The rehydrated alumina powder molded body thus obtained is rehydrated to obtain a rehydrated alumina molded body. For rehydration, for example, the rehydratable alumina powder compact may be brought into contact with steam. The rehydratable alumina powder molded body is usually brought into contact with water vapor at a temperature of 0 ° C. or higher and 200 ° C. or lower, preferably at 80 ° C. or higher in order to obtain an activated alumina molded body having more excellent mechanical strength. The contacting time varies depending on the type, shape and particle size of the rehydratable alumina powder used, the shape and size of the rehydratable alumina powder compact, and is, for example, about 1 minute to 1 week. When the rehydratable alumina powder compact comes into contact with water vapor, it is rehydrated in its original shape to form a rehydrated alumina compact.
[0021]
The obtained rehydrated alumina compact may be brought into contact with an acidic aqueous solution. By contacting with an acidic aqueous solution, an alkali metal component such as sodium is eluted, so that an activated alumina compact having a low sodium content can be obtained. Further, the surface of the obtained activated alumina molded body can be made acidic. Further, it may be brought into contact with an aqueous solution of a lanthanoid element such as lanthanum, an alkaline earth metal such as barium, a silicon compound, a cerium compound, a zirconium compound, or the like. By contacting with such an aqueous solution, an activated alumina molded body having excellent heat resistance can be obtained.
[0022]
The obtained rehydrated alumina compact is fired. The firing temperature is usually about 300 ° C. or more and 1000 ° C. or less, preferably about 350 ° C. or more and 800 ° C. or less. When a salt is used as an additive, it is preferable that the firing be performed at a temperature equal to or higher than the decomposition temperature. The firing method is not particularly limited, and firing can be performed by heating using a normal heating method such as combustion gas, indirect heating using an electric heater, or heating using far infrared rays.
[0023]
The rehydrated alumina molded body may contain moisture attached during rehydration, but may be fired after removing such moisture. In order to remove water, drying may be performed by a normal method such as natural drying, hot air drying, or vacuum drying.
[0024]
Thus although obtain an active alumina compact, the resulting activated alumina formed body, for example, the volume of macro pores communicates with the outside at a pore radius 0.3μm or 0.04 cm 3 / g or more 0.2 cm 3 / g Hereinafter, the BET specific surface area is about 100 m 2 / g or more and about 400 m 2 / g or less.
[0025]
Since such an activated alumina molded body has a large macropore volume and a high BET specific surface area, it can be used as it is, for example, as an adsorbent. It is also useful as a catalyst carrier, and can be used as a catalyst by carrying a catalyst component such as a noble metal.
[0026]
【The invention's effect】
According to the production method of the present invention, it is possible to easily produce an activated alumina molded body having a large volume of macropores having a pore radius of 0.3 μm or more and a high BET specific surface area.
[0027]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to such Examples.
[0028]
The activated alumina compact obtained in each example was evaluated by the following method.
Macropore volume: The volume of pores having a pore radius of 0.3 μm or more and 100 μm or less was determined from the pore distribution measured by the mercury intrusion method.
BET specific surface area: It was measured using a BET specific surface area measuring device manufactured by Mountech.
Central particle diameter: Determined on a mass basis using a Microtrac particle size distribution meter manufactured by Leads & Northrup.
Blaine specific surface area: It was determined by a constant-pressure pneumatic measurement method using a Brain specific surface area measuring device “SS-100” manufactured by Shimadzu Corporation.
Packing density: In accordance with JIS H 1902, a sample was taken in a measuring cylinder, and the packing density was determined from the sample volume after tapping was performed 100 times.
Pressure strength: After measuring the diameter of 10 samples with a micrometer, the breaking strength was measured with a hardness tester, the strength per cross-sectional area was determined, and the average value was determined.
[0029]
Example 1
Gibbsite-type aluminum hydroxide powder obtained by the Bayer method (central particle size: 40 μm, water content: 1% by mass or less) is put into a hot gas stream at 700 ° C. and instantaneously calcined to be rehydrated. Alumina powder [particle diameter in the range of 20 μm to 100 μm] was obtained. The crystal system of the rehydratable alumina powder was a ρ phase and a χ phase.
[0030]
100 parts by mass of the rehydratable alumina powder obtained above was mixed with 0.3 parts by mass of a water-absorbing resin powder (“KI gel-201K” manufactured by Kuraray Co., Ltd., central particle diameter 120 μm, water absorption ratio 183 times) and a naphtha mixer. And mixed for 1 hour, and then pulverized using a vibration ball mill. The Blaine specific surface area of the ground mixture after grinding was 13000 cm 2 / g. Water was added to the pulverized product obtained above by spraying using a dish-type granulator having a diameter of 1 m while spraying to obtain a spherical rehydratable alumina powder compact having a diameter of 1 to 3 mm. The obtained rehydrated alumina powder compact was brought into contact with air containing saturated steam at 105 ° C. under atmospheric pressure in an autoclave for 4 hours to obtain a rehydrated alumina compact. The obtained rehydrated alumina compact was placed in an alumina crucible, heated to 400 ° C. in an electric furnace, kept at the same temperature for 2 hours, and fired to obtain an activated alumina compact.
[0031]
The macropore volume of the obtained activated alumina compact was 0.06 cm 3 / g, the BET specific surface area was 278 m 2 / g, the packing density was 0.71 g / cm 3 , and the pressure resistance was 1440 N / cm 2. Was.
[0032]
Comparative Example 1
An activated alumina compact was obtained in the same manner as in Example 1 except that the water-absorbent resin powder was not used. The macropore volume of the obtained activated alumina molded body was 0.03 cm 3 / g, the BET specific surface area was 270 m 2 / g, the packing density was 0.81 g / cm 3 , and the pressure resistance was 1710 N / cm 2. Was.
[0033]
Comparative Example 2
Instead of using a water-absorbent resin powder [KI gel 201K] instead of 0.3 parts by mass of a water-absorbent resin powder [Kuraray Co., Ltd. “KI gel-201-F2”, center particle diameter 18 μm, water absorption ratio 184 times] By operating in the same manner as in Example 1, an activated alumina molded body was obtained. The macropore volume of the obtained activated alumina molded body was 0.02 cm 3 / g, the BET specific surface area was 275 m 2 / g, the packing density was 0.78 g / cm 3 , and the pressure resistance was 1770 N / cm 2. Was.
[0034]
Comparative Example 3
An activated alumina molded body was obtained in the same manner as in Example 1 except that pulverization was performed until the Blaine specific surface area became 140000 cm 2 / g. The macropore volume of the obtained activated alumina molded body was 0.03 cm 3 / g, the BET specific surface area was 308 m 2 / g, the packing density was 0.77 g / cm 3 , and the pressure resistance was 1320 N / cm 2. Was.
[0035]
Example 2
An activated alumina compact was obtained in the same manner as in Example 1, except that the amount of the water-absorbent resin powder used was 0.4 parts by mass and the firing temperature of the rehydrated alumina compact was 850 ° C. The resulting macro pore volume of activated alumina formed body is 0.07cm 3 / g, BET specific surface area of 106cm 3 / g, a packing density of 0.67 g / cm 3, compressive strength is 590N / cm 2 met Was.
Claims (6)
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| JP2018140907A (en) * | 2017-02-28 | 2018-09-13 | 住友化学株式会社 | Particle for laminated molding, molding, and method for producing molding |
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| JP2007001836A (en) * | 2005-06-27 | 2007-01-11 | Ngk Insulators Ltd | Method of manufacturing honeycomb structure |
| JP2018140907A (en) * | 2017-02-28 | 2018-09-13 | 住友化学株式会社 | Particle for laminated molding, molding, and method for producing molding |
| WO2019167898A1 (en) * | 2018-02-28 | 2019-09-06 | 住友化学株式会社 | Particle composition |
| JPWO2019167898A1 (en) * | 2018-02-28 | 2021-03-04 | 住友化学株式会社 | Particle composition |
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| CN109384458A (en) * | 2018-10-26 | 2019-02-26 | 湖北斯曼新材料股份有限公司 | A kind of green compact calcining preparation method and applications of active alpha-alumina powder |
| CN112028612A (en) * | 2020-09-02 | 2020-12-04 | 江苏苏嘉集团新材料有限公司 | Magnesia carbon brick applying reinforcing material |
| CN112028612B (en) * | 2020-09-02 | 2022-07-19 | 江苏苏嘉集团新材料有限公司 | Magnesia carbon brick applying reinforcing material |
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