JP2005008429A - Synthetic method of active oxygen species-including clathrate substance - Google Patents
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、活性酸素種包接物質の合成方法、特に、比表面積が高く、多量に活性酸素種を包接する物質の合成方法に関する。
なお、本発明における部や％は特に規定しない限り質量基準で示す。
【０００２】
【従来の技術とその課題】
１２ＣａＯ・Ａｌ２Ｏ３と表されるカルシウムアルミネート系化合物の一種は、その結晶格子中に空隙（ケージ）を有している。
一方、活性酸素種として、Ｏ２ −イオンラジカルやＯ−イオンラジカルが知られている。
一般に、Ｏ２ −イオンラジカルは、固体構造中では常にカチオンで配位されており、フリーな状態になることはほとんどない。しかしながら、１２ＣａＯ・７Ａｌ２Ｏ３結晶中では、Ｏ２ −イオンラジカルは、ケージ内に存在し、カチオンと結合できず、フリーな状態になっている。このような状態を「包接」といい、この状態は、固体表面に吸着した状態と類似しており、化学的に非常に活性な状態である。
【０００３】
そして、１２ＣａＯ・Ａｌ２Ｏ３と表されるカルシウムアルミネート系化合物の一種には１×１０１９ｃｍ−３程度のＯ２ −が包接されていることを電子スピン共鳴の測定から見いだし、フリー酸素の一部がＯ２ −の形でケージ内に存在することが発表されている（非特許文献１参照）。
【０００４】
近年、活性酸素種を多量に包接する化合物が見出され、酸化触媒、イオン伝導体、及び固体電解質燃料電池用電極等への利用が期待されている（特許文献１、非特許文献２参照）。
【０００５】
この方法は、１２ＣａＯ・Ａｌ２Ｏ３と表されるカルシウムアルミネート系化合物の一種を、酸素分圧１０４Ｐａ以上、水蒸気分圧１０２Ｐａ以下の条件下で、１，２００〜１，４１５℃で加熱処理することにより得られるもので、活性酸素種を１０２０ｃｍ−３以上の高濃度に包接するものであった。
しかしながら、従来の方法で得られる活性酸素種を包接する化合物は、その比表面積が小さく、例えば、触媒用途へ用いる場合においては、充分なものではなかった。
【０００６】
この方法は、ＣａＯ原料とＡｌ２Ｏ３原料を所定の割合で混合して熱処理することにより、１２ＣａＯ・Ａｌ２Ｏ３を生成せしめるものであるが、この場合、得られる１２ＣａＯ・Ａｌ２Ｏ３は焼成反応により結晶成長を起す。このため、このような方法で得た１２ＣａＯ・Ａｌ２Ｏ３を機械的に粉砕しても、触媒用途などに利用できるほどの高い比表面積を持つものを得ることは不可能で、このような方法で得られる１２ＣａＯ・Ａｌ２Ｏ３の比表面積は、ＢＥＴ比表面積で表して、せいぜい２ｍ２／ｇ程度のものであった。
【０００７】
例えば、触媒用途などに用いることを想定すれば、少なくともその比表面積は５ｍ２／ｇ以上が必要であり、好ましくは１０ｍ２／ｇ以上、最も好ましくは２０ｍ２／ｇが望まれる。
また、従来の活性酸素種包接化合物の活性酸素包接量は、多くても５×１０２１ｃｍ−３程度であった。
さらに、従来法は、焼成温度１，２００℃以上を必要するものであり、エネルギー原単位や炭素排出量原単位の観点からは必ずしも環境負荷の小さい合成方法ではなかった。
【０００８】
今日では、触媒用途などにも利用可能な、より比表面積の高い、しかもより多くの活性酸素種を包接し、さらにより低温で合成できる環境負荷の小さい合成方法の開発が強く求められている。
【０００９】
本発明者は、鋭意努力を重ねた結果、特定の化合物を出発物質として、特定の条件で処理することにより、比表面積が高く、しかも活性酸素種をこれまでにないほど多量に包接した活性酸素種包接物質が得られること、さらにその物質を８００℃程度の熱処理温度でも得ることが可能となることなどを知見し、本発明を完成するに至った。
【００１０】
【特許文献１】
特開平１４−００３２１８号公報
【非特許文献１】
Ｈ．Ｈｏｓｏｎｏ ａｎｄ Ｙ．Ａｂｅ，Ｉｎｏｒｇ．Ｃｈｅｍ．２６，１１９３，１９９７
【非特許文献２】
細野秀雄他、ケミカルエンジニアリング、２００２年４月号、ｐｐ２４９〜２５２
【００１１】
【課題を解決するための手段】
即ち、本発明は、２ＣａＯ・Ａｌ２Ｏ３・８Ｈ２Ｏを主体とするカルシウムアルミネート水和物を、酸素分圧４×１０４Ｐａ以上、水蒸気分圧１０２Ｐａ以下の条件下で、８００〜１，１５０℃で加熱処理する活性酸素種包接物質の合成方法であり、８００℃以下の温度から、酸素分圧４×１０４Ｐａ以上、水蒸気分圧１０２Ｐａ以下に保ち、８００〜１，１５０℃の温度範囲まで昇温して加熱処理する該活性酸素種包接物質の合成方法である。
【００１２】
【発明の実施の形態】
以下、本発明を詳細に説明する。
【００１３】
本発明で言う活性酸素種包接物質とは、一般的に１２ＣａＯ・７Ａｌ２Ｏ３と呼ばれるカルシウムアルミネート系化合物を含む物質を総称するものである。
本発明の活性酸素種包接物質は、１２ＣａＯ・７Ａｌ２Ｏ３を、例えば、５０％以上含んでいれば良く、その他のカルシウムアルミネート類が混在していても何ら差し支えない。
カルシウムアルミネート類とは、ＣａＯとＡｌ２Ｏ３を主体とする化合物を総称するものであり、その具体例としては、例えば、ＣａＯ・Ａｌ２Ｏ３、１１ＣａＯ・７Ａｌ２Ｏ３・ＣａＦ２、１１ＣａＯ・７Ａｌ２Ｏ３・ＣａＣｌ２、３ＣａＯ・Ａｌ２Ｏ３、及び３ＣａＯ・３Ａｌ２Ｏ３・ＣａＳＯ４などが混在する場合がある。
また、カルシウムアルミネートのほかにも、４ＣａＯ・Ａｌ２Ｏ３・Ｆｅ２Ｏ３、６ＣａＯ・２Ａｌ２Ｏ３・Ｆｅ２Ｏ３、及び６ＣａＯ・Ａｌ２Ｏ３・２Ｆｅ２Ｏ３などのカルシウムアルミノフェライト類、ダイカルシウムシリケート２ＣａＯ・ＳｉＯ２、ランキナイト３ＣａＯ・２ＳｉＯ２、及びワラストナイトＣａＯ・ＳｉＯ２などのカルシウムシリケート類、ゲーレナイト２ＣａＯ・Ａｌ２Ｏ３・ＳｉＯ２などのカルシウムアルミノシリケート類、並びに、遊離石灰等が混在する場合もある。
【００１４】
本発明は、２ＣａＯ・Ａｌ２Ｏ３・８Ｈ２Ｏ（以下、Ｃ２ＡＨ８という）を出発物質として１２ＣａＯ・７Ａｌ２Ｏ３（以下、Ｃ１２Ａ７という）を含む活性酸素種包接物質を得るものである。
Ｃ２ＡＨ８はカルシウムアルミネート水和物の一種であり、通常でも、５ｍ２／ｇ以上の比表面積を有し、生成条件を変えることで比表面積をより高いものに調整することが可能である。
Ｃ２ＡＨ８は加熱すると脱水・分解し、７００〜８００℃程度でＣ１２Ａ７を形成する。この際、得られるＣ１２Ａ７を主体とする活性酸素種包接物質の比表面積は、出発物質のＣ２ＡＨ８の比表面積に依存する。
【００１５】
Ｃ２ＡＨ８を得る方法としては、カルシウムアルミネート類を水和させる方法や、カルシウム塩とアルミン酸塩を加水分解させる方法等が挙げられ、その代表例としては、ＣａＯ・Ａｌ２Ｏ３と、水酸化カルシウム及び／又は酸化カルシウムを、ＣａＯとＡｌ２Ｏ３のモル比が２対１となるように配合して水和させる方法や、水酸化カルシウムとアルミン酸ナトリウムをＣａＯとＡｌ２Ｏ３のモル比が１以下となるように配合して加水分解させる方法等を挙げることができる。
【００１６】
上記方法でＣ２ＡＨ８を合成する際の温度は２５℃以下が好ましく、２０℃以下がより好ましい。２５℃を超えると３ＣａＯ・Ａｌ２Ｏ３・６Ｈ２Ｏが生成する場合がある。３ＣａＯ・Ａｌ２Ｏ３・６Ｈ２ＯはＣ２ＡＨ８と比べて比表面積が小さい傾向にあり、また、得られるＣ１２Ａ７の純度が低くなるため好ましくない。
【００１７】
なお、比表面積の高いＣ２ＡＨ８を得るためには、より低い温度で反応させることが好ましく、また、水酸化物イオン濃度の高い条件下で反応させることが好ましい。このため、水酸化ナトリウムや水酸化カリウムなどのアルカリ金属塩を併用することが好ましい。
【００１８】
本発明の合成方法によって得られる活性酸素種包接物質の比表面積は、出発物質のＣ２ＡＨ８の比表面積に依存する。そのため、出発物質のＣ２ＡＨ８の比表面積は高いものほど好ましく、５ｍ２／ｇ以上が好ましく、１０ｍ２／ｇ以上がより好ましく、２０ｍ２／ｇ以上が最も好ましい。
【００１９】
Ｃ２ＡＨ８を工業的に得る場合、不純物が含まれることがある。その具体例としては、例えば、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２Ｏ、ＭｇＯ、ＴｉＯ２、ＭｎＯ、Ｆｅ２Ｏ３、Ｂ２Ｏ３、ＳｉＯ２、Ｐ２Ｏ５、Ｓ、フッ素、及び塩素等が挙げられる。
また、Ｃ２ＡＨ８には、Ｃ２ＡＨ８以外の他のカルシウムアルミネート系水和物として、例えば、ＣａＯ・Ａｌ２Ｏ３・１０Ｈ２Ｏ、３ＣａＯ・Ａｌ２Ｏ３・６Ｈ２Ｏ、４ＣａＯ・Ａｌ２Ｏ３・ｎＨ２Ｏ、及び４ＣａＯ・Ａｌ２Ｏ３・ＣＯ３・１１Ｈ２Ｏなどが共存する場合もある。
【００２０】
本発明の活性酸素種包接物質の合成方法において、Ｃ２ＡＨ８を主体とするカルシウムアルミネート水和物を熱処理する。
熱処理方法は、Ｃ２ＡＨ８を主体とするカルシウムアルミネート水和物を８００〜１，１５０℃で加熱処理することが必要であり、８００〜１，０００℃で加熱処理することが好ましい。８００℃未満で加熱処理してもＣ１２Ａ７がほとんど生成しないため活性酸素種の包接量が極めて少なく、１，１５０℃を超えると焼結反応が進み比表面積が小さくなるばかりでなく、３ＣａＯ・Ａｌ２Ｏ３の生成量が増加し、やはり活性酸素種を包接しにくくなる。３ＣａＯ・Ａｌ２Ｏ３の生成は１，０００℃を超えると顕在化し、Ｃ１２Ａ７の純度が低下して活性酸素包接量が少なくなる傾向にある。活性酸素種を多く包接させる観点からは、熱処理温度は８００〜１，０００℃の範囲が最も好ましい。
【００２１】
また、熱処理の際、酸素分圧を４×１０４Ｐａ以上、水蒸気分圧を１０２Ｐａ以下の条件下で行う必要がある。上記の条件を満たさないと活性酸素種の包接量を多くすることができない。
【００２２】
なお、熱処理の過程で昇温するが、本発明では、昇温の段階から、酸素分圧を高めておくことが望ましい。
即ち、Ｃ１２Ａ７が生成する８００℃程度の温度よりも低い温度領域から酸素分圧を４×１０４Ｐａ以上にし、水蒸気分圧を１０２Ｐａ以下に保つことが好ましく、このような方法を行うことで、より多量の活性酸素種を包接することができるＣ１２Ａ７を生成することが可能である。
【００２３】
【実施例】
以下、本発明の実験例に基づいてさらに説明する。
【００２４】
実験例１
表１に示す比表面積のＣ２ＡＨ８を合成した。
合成したＣ２ＡＨ８を昇温速度２０℃／ｍｉｎ．で９００℃まで加熱し、３時間保持した。この際、加熱開始から酸素分圧を５×１０４Ｐａ、水蒸気分圧を１０２Ｐａに保った。得られた物質を粉末Ｘ線回折法により同定した。また、ＢＥＴ比表面積と活性酸素種の包接量を測定した。結果を表１に併記する。
【００２５】
＜使用材料＞
Ｃ２ＡＨ８▲１▼ ：ＣａＯ・Ａｌ２Ｏ３と水酸化カルシウムをＣａＯとＡｌ２Ｏ３のモル比が２対１となるように配合して水／（ＣａＯ・Ａｌ２Ｏ３と水酸化カルシウム）比（以下、水／粉体比という）１００％で２８日間水和させたもの。ＢＥＴ比表面積４．５ｍ２／ｇ
Ｃ２ＡＨ８▲２▼ ：水酸化カルシウムの１モル／リットルのスラリーと、アルミン酸ナトリウムの１モル／リットルの溶液を２０℃で加水分解して沈殿物を生成させ、攪拌しながら１６時間反応させた。その後、固液分離してアセトンを用いて余剰水を除去し、アスピレータにて減圧乾燥した。ＢＥＴ比表面積９．３ｍ２／ｇ
Ｃ２ＡＨ８▲３▼ ：水酸化カルシウムの２モル／リットルのスラリーと、アルミン酸ナトリウムの２モル／リットルの溶液を１０℃で加水分解して沈殿物を生成させ、攪拌しながら、１６時間反応させた。その後、固液分離してアセトンを用いて余剰水を除去し、アスピレータにて減圧乾燥した。ＢＥＴ比表面積１８．７ｍ２／ｇ
Ｃ１２Ａ７イ ：従来法で得た活性酸素包接Ｃ１２Ａ７、試薬１級の炭酸カルシウム１２モルと酸化アルミニウム７モルを混合粉砕して原料を調製し、電気炉で１，３５０℃で３時間焼成する工程を２回繰り返して合成した。得られたＣ１２Ａ７を振動式ボールミルにて可能なまで粉砕した。ブレーン比表面積５，５００ｃｍ２／ｇ、ＢＥＴ比表面積１ｍ２／ｇ
Ｃ１２Ａ７ロ ：従来法で得た活性酸素包接Ｃ１２Ａ７、活性酸素包接Ｃ１２Ａ７イをアセトン溶媒中でさらに湿式粉砕し、可能なまで微粉化した。ＢＥＴ比表面積２ｍ２／ｇ
【００２６】
＜測定方法＞
活性酸素種の包接量：電子スピン共鳴（ＥＳＲ）とラマンスペクトル法により定量
【００２７】
【表１】
実験例２
Ｃ２ＡＨ８▲２▼を使用し、表２に示す温度で熱処理したこと以外は実験例１と同様に行った。結果を表２に併記する。
【００２９】
【表２】
実験例３
Ｃ２ＡＨ８の代わりに他のカルシウムアルミネート水和物を使用したこと以外は実験例１と同様に行った。結果を表３に併記する。
【００３１】
＜使用材料＞
Ｃ３ＡＨ６ ：３ＣａＯ・Ａｌ２Ｏ３・６Ｈ２Ｏ、水酸化カルシウムの２モル／リットルのスラリーとアルミン酸ナトリウムの１モル／リットルの溶液を２０℃で加水分解して沈殿物を生成させ、攪拌しながら、１６時間反応させた。その後、固液分離してアセトンを用いて余剰水を除去し、５０℃で乾燥した。ＢＥＴ比表面積１．２ｍ２／ｇ
Ｃ４ＡＨ１３ ：４ＣａＯ・Ａｌ２Ｏ３・１３Ｈ２Ｏ、ＣａＯ・Ａｌ２Ｏ３と水酸化カルシウムをＣａＯとＡｌ２Ｏ３のモル比が４対１となるように配合して水／粉体比１００％で２８日間水和させたもの。ＢＥＴ比表面積４．１ｍ２／ｇ
【００３２】
【表３】
実験例４
Ｃ２ＡＨ８▲２▼を使用し、酸素分圧を高める温度のタイミングを表４に示すように変化したこと以外は実験例１と同様に行った。結果を表４に併記する。
【００３４】
【表４】
実験例５
Ｃ２ＡＨ８▲２▼を使用し、表５に示すように酸素分圧を変化させたこと以外は実験例１と同様に行った。結果を表５に併記する。
【００３６】
【表５】
【発明の効果】
本発明の活性酸素種を包接する物質の合成方法によれば、比表面積が非常に高く、活性酸素種の包接量も多い活性酸素種を包接する物質が得られる。
また、従来よりも低い熱処理温度で合成でき、エネルギー原単位が小さく環境負荷の小さい合成方法でもある。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for synthesizing a reactive oxygen species inclusion substance, and more particularly to a method for synthesizing a substance having a high specific surface area and a large amount of reactive oxygen species.
In the present invention, “parts” and “%” are based on mass unless otherwise specified.
[0002]
[Prior art and its problems]
One type of calcium aluminate compound represented by 12CaO.Al 2 O 3 has voids (cages) in its crystal lattice.
On the other hand, as the active oxygen species, O 2 - ion radical and O - ion radicals are known.
In general, O 2 - ion radical is always cations in the solid structure are coordinated, it is unlikely to become a free state. However, in the 12CaO · 7Al 2 O 3 crystal, O 2 - ion radical is present in the cage can not bind to the cation, which is a free state. Such a state is referred to as “inclusion”, and this state is similar to the state of being adsorbed on the solid surface and is a chemically very active state.
[0003]
And it was found from the measurement of electron spin resonance that one kind of calcium aluminate compound represented by 12CaO.Al 2 O 3 was clad with O 2 − of about 1 × 10 19 cm −3. It has been announced that some oxygen is present in the cage in the form of O 2 − (see Non-Patent Document 1).
[0004]
In recent years, compounds that include a large amount of active oxygen species have been found and are expected to be used for oxidation catalysts, ionic conductors, solid electrolyte fuel cell electrodes, and the like (see Patent Document 1 and Non-Patent Document 2). .
[0005]
In this method, a calcium aluminate-based compound represented by 12CaO.Al 2 O 3 is subjected to 1,200 to 1,415 under conditions of an oxygen partial pressure of 10 4 Pa or more and a water vapor partial pressure of 10 2 Pa or less. It was obtained by heat treatment at 0 ° C. and included active oxygen species at a high concentration of 10 20 cm −3 or more.
However, the compound that includes the active oxygen species obtained by the conventional method has a small specific surface area, and is not sufficient, for example, when used for a catalyst.
[0006]
In this method, a CaO raw material and an Al 2 O 3 raw material are mixed at a predetermined ratio and heat-treated to produce 12CaO · Al 2 O 3. In this case, the obtained 12CaO · Al 2 O 3 is obtained. Causes crystal growth by a firing reaction. For this reason, even if 12CaO · Al 2 O 3 obtained by such a method is mechanically pulverized, it is impossible to obtain a material having such a high specific surface area that it can be used for catalyst applications. The specific surface area of 12CaO.Al 2 O 3 obtained by the method was represented by the BET specific surface area and was at most about 2 m 2 / g.
[0007]
For example, assuming that it is used for catalyst applications, at least its specific surface area is required to be 5 m 2 / g or more, preferably 10 m 2 / g or more, and most preferably 20 m 2 / g.
Moreover, the active oxygen inclusion amount of the conventional active oxygen species inclusion compound was at most about 5 × 10 21 cm −3 .
Furthermore, the conventional method requires a firing temperature of 1,200 ° C. or higher, and is not necessarily a synthesis method with a small environmental load from the viewpoint of energy intensity and carbon emission intensity.
[0008]
Today, there is a strong demand for the development of a synthesis method that can be used for catalysts and the like, has a higher specific surface area, includes more active oxygen species, and can be synthesized at a lower temperature and has a lower environmental impact.
[0009]
As a result of intensive efforts, the present inventor has been able to treat a specific compound as a starting material under a specific condition, thereby increasing the specific surface area and including an active oxygen species in a large amount as never before. The inventors have found that an oxygen species inclusion substance can be obtained, and that the substance can be obtained even at a heat treatment temperature of about 800 ° C., thereby completing the present invention.
[0010]
[Patent Document 1]
JP-A-14-003218 [Non-Patent Document 1]
H. Hosono and Y. Abe, Inorg. Chem. 26, 1193, 1997
[Non-Patent Document 2]
Hideo Hosono et al., Chemical Engineering, April 2002, pp 249-252
[0011]
[Means for Solving the Problems]
That is, the present invention provides a calcium aluminate hydrate mainly composed of 2CaO · Al 2 O 3 · 8H 2 O under the conditions of an oxygen partial pressure of 4 × 10 4 Pa or more and a water vapor partial pressure of 10 2 Pa or less. This is a method for synthesizing an active oxygen species inclusion material that is heat-treated at 800 to 1,150 ° C., and maintains a partial pressure of oxygen of 4 × 10 4 Pa or higher and a partial pressure of water vapor of 10 2 Pa or lower from a temperature of 800 ° C. or lower. This is a method for synthesizing the reactive oxygen species inclusion material, which is heated to a temperature range of ˜1,150 ° C. and heat-treated.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0013]
The active oxygen species inclusion substance referred to in the present invention is a generic term for substances containing a calcium aluminate compound generally called 12CaO · 7Al 2 O 3 .
The active oxygen species inclusion substance of the present invention may contain, for example, 50% or more of 12CaO · 7Al 2 O 3 , and other calcium aluminates may be mixed.
Calcium aluminates are generic names of compounds mainly composed of CaO and Al 2 O 3 , and specific examples thereof include, for example, CaO · Al 2 O 3 , 11CaO · 7Al 2 O 3 · CaF 2 , sometimes 11CaO · 7Al 2 O 3 · CaCl 2, 3CaO · Al 2 O 3, and the like 3CaO · 3Al 2 O 3 · CaSO 4 are mixed.
Furthermore, addition to the calcium aluminate, 4CaO · Al 2 O 3 · Fe 2 O 3, 6CaO · 2Al 2 O 3 · Fe 2 O 3, and calcium, such as 6CaO · Al 2 O 3 · 2Fe 2 O 3 alumino Ferrites, calcium silicates such as dicalcium silicate 2CaO · SiO 2 , lanquinite 3CaO · 2SiO 2 , and wollastonite CaO · SiO 2 , calcium aluminosilicates such as galenite 2CaO · Al 2 O 3 · SiO 2 , and In some cases, free lime and the like are mixed.
[0014]
The present invention relates to an active oxygen species inclusion material containing 12CaO · 7Al 2 O 3 (hereinafter referred to as C 12 A 7 ) starting from 2CaO · Al 2 O 3 · 8H 2 O (hereinafter referred to as C 2 AH 8 ). Is what you get.
C 2 AH 8 is a kind of calcium aluminate hydrate, and usually has a specific surface area of 5 m 2 / g or more, and it is possible to adjust the specific surface area to a higher one by changing the production conditions. is there.
C 2 AH 8 dehydrates and decomposes when heated, and forms C 12 A 7 at about 700 to 800 ° C. At this time, the specific surface area of the obtained active oxygen species inclusion material mainly composed of C 12 A 7 depends on the specific surface area of C 2 AH 8 as a starting material.
[0015]
Examples of the method for obtaining C 2 AH 8 include a method of hydrating calcium aluminates, a method of hydrolyzing calcium salts and aluminates, and representative examples thereof include CaO · Al 2 O 3 and Calcium hydroxide and / or calcium oxide is mixed and hydrated so that the molar ratio of CaO and Al 2 O 3 is 2: 1, or calcium hydroxide and sodium aluminate are mixed with CaO and Al 2 O. Examples of the method include mixing and hydrolyzing so that the molar ratio of 3 is 1 or less.
[0016]
The temperature at which C 2 AH 8 is synthesized by the above method is preferably 25 ° C. or less, and more preferably 20 ° C. or less. Sometimes 3CaO · Al 2 O 3 · 6H 2 O is generated exceeds 25 ° C.. 3CaO · Al 2 O 3 · 6H 2 O tends to have a smaller specific surface area than C 2 AH 8, and the purity of C 12 A 7 obtained is low, which is not preferable.
[0017]
In order to obtain a high C 2 AH 8 specific surface area is preferably reacted at lower temperatures, also, the reaction is preferably carried out at a high hydroxide ion concentration conditions. For this reason, it is preferable to use together alkali metal salts, such as sodium hydroxide and potassium hydroxide.
[0018]
The specific surface area of the active oxygen species inclusion material obtained by the synthesis method of the present invention depends on the specific surface area of the starting material C 2 AH 8 . Therefore, the higher the specific surface area of C 2 AH 8 as the starting material is, the more preferable, 5 m 2 / g or more is preferable, 10 m 2 / g or more is more preferable, and 20 m 2 / g or more is most preferable.
[0019]
When C 2 AH 8 is obtained industrially, impurities may be contained. Specific examples thereof include, for example, Li 2 O, Na 2 O, K 2 O, MgO, TiO 2 , MnO, Fe 2 O 3 , B 2 O 3 , SiO 2 , P 2 O 5 , S, fluorine, and Examples include chlorine.
C 2 AH 8 includes calcium aluminate hydrates other than C 2 AH 8 , such as CaO · Al 2 O 3 · 10H 2 O, 3CaO · Al 2 O 3 · 6H 2 O, 4CaO · Al 2 O 3 · nH 2 O, and 4CaO · Al 2 O 3 · CO 3 · 11H 2 may O and coexist there.
[0020]
In the method for synthesizing a reactive oxygen species inclusion material of the present invention, a calcium aluminate hydrate mainly composed of C 2 AH 8 is heat-treated.
In the heat treatment method, it is necessary to heat-treat calcium aluminate hydrate mainly composed of C 2 AH 8 at 800 to 1,150 ° C., and preferably heat-treat at 800 to 1,000 ° C. Even if heat treatment is performed at a temperature lower than 800 ° C., C 12 A 7 is hardly generated, so that the amount of inclusion of active oxygen species is extremely small. If the temperature exceeds 1,150 ° C., the sintering reaction proceeds and not only the specific surface area is reduced, The production amount of 3CaO.Al 2 O 3 increases, and it becomes difficult to include active oxygen species. The production of 3CaO.Al 2 O 3 becomes obvious when the temperature exceeds 1,000 ° C., and the purity of C 12 A 7 tends to decrease and the amount of active oxygen inclusion tends to decrease. From the viewpoint of including many active oxygen species, the heat treatment temperature is most preferably in the range of 800 to 1,000 ° C.
[0021]
In addition, it is necessary to perform the heat treatment under the conditions of an oxygen partial pressure of 4 × 10 4 Pa or more and a water vapor partial pressure of 10 2 Pa or less. If the above conditions are not satisfied, the amount of inclusion of active oxygen species cannot be increased.
[0022]
Although the temperature is raised during the heat treatment, in the present invention, it is desirable to increase the oxygen partial pressure from the stage of temperature rise.
That is, it is preferable to set the oxygen partial pressure to 4 × 10 4 Pa or higher and the water vapor partial pressure to 10 2 Pa or lower from a temperature range lower than the temperature of about 800 ° C. generated by C 12 A 7. It is possible to generate C 12 A 7 that can include a larger amount of active oxygen species.
[0023]
【Example】
Hereinafter, further description will be given based on experimental examples of the present invention.
[0024]
Experimental example 1
C 2 AH 8 having a specific surface area shown in Table 1 was synthesized.
The synthesized C 2 AH 8 was heated at a heating rate of 20 ° C./min. And heated to 900 ° C. and held for 3 hours. At this time, the oxygen partial pressure was maintained at 5 × 10 4 Pa and the water vapor partial pressure was maintained at 10 2 Pa from the start of heating. The resulting material was identified by powder X-ray diffraction. Moreover, the inclusion amount of the BET specific surface area and the active oxygen species was measured. The results are also shown in Table 1.
[0025]
<Materials used>
C 2 AH 8 ( 1): CaO · Al 2 O 3 and calcium hydroxide are mixed so that the molar ratio of CaO and Al 2 O 3 is 2: 1 and water / (CaO · Al 2 O 3 and water Hydrated with 100% calcium oxide) ratio (hereinafter referred to as water / powder ratio) for 28 days. BET specific surface area 4.5 m 2 / g
C 2 AH 8 ( 2): A 1 mol / liter slurry of calcium hydroxide and a 1 mol / liter solution of sodium aluminate are hydrolyzed at 20 ° C. to form a precipitate, which is reacted for 16 hours with stirring. I let you. Then, it separated into solid and liquid, excess water was removed using acetone, and it dried under reduced pressure with the aspirator. BET specific surface area 9.3 m 2 / g
C 2 AH 8 ( 3): A 2 mol / liter slurry of calcium hydroxide and a 2 mol / liter solution of sodium aluminate were hydrolyzed at 10 ° C. to form a precipitate, and stirred for 16 hours. Reacted. Then, it separated into solid and liquid, excess water was removed using acetone, and it dried under reduced pressure with the aspirator. BET specific surface area 18.7 m 2 / g
C 12 A 7 B: Active oxygen inclusion C 12 A 7 obtained by a conventional method, 12 mol of first grade calcium carbonate and 7 mol of aluminum oxide are mixed and pulverized to prepare a raw material, and 1,350 ° C. in an electric furnace The process of baking for 3 hours was repeated twice and synthesized. The obtained C 12 A 7 was pulverized with a vibrating ball mill until possible. Blaine specific surface area 5,500 cm 2 / g, BET specific surface area 1 m 2 / g
C 12 A 7 B: Active oxygen inclusion C 12 A 7 and active oxygen inclusion C 12 A 7 I obtained by the conventional method were further wet-pulverized in an acetone solvent and pulverized as much as possible. BET specific surface area 2m 2 / g
[0026]
<Measurement method>
Inclusion amount of reactive oxygen species: quantified by electron spin resonance (ESR) and Raman spectroscopy
[Table 1]
Experimental example 2
The same procedure as in Experimental Example 1 was conducted except that C 2 AH 8 ( 2) was used and heat treatment was performed at the temperature shown in Table 2. The results are also shown in Table 2.
[0029]
[Table 2]
Experimental example 3
Except for using other calcium aluminate hydrates in place of C 2 AH 8 was conducted in the same manner as in Experimental Example 1. The results are also shown in Table 3.
[0031]
<Materials used>
C 3 AH 6 : 3CaO · Al 2 O 3 · 6H 2 O, a 2 mol / liter slurry of calcium hydroxide and a 1 mol / liter solution of sodium aluminate are hydrolyzed at 20 ° C. to form a precipitate. The mixture was allowed to react for 16 hours with stirring. Then, it separated into solid and liquid, the excess water was removed using acetone, and it dried at 50 degreeC. BET specific surface area 1.2 m 2 / g
C 4 AH 13 : 4CaO · Al 2 O 3 · 13H 2 O, CaO · Al 2 O 3 and calcium hydroxide are mixed so that the molar ratio of CaO to Al 2 O 3 is 4 to 1, and water / powder Hydrated for 28 days at a body ratio of 100%. BET specific surface area 4.1 m 2 / g
[0032]
[Table 3]
Experimental Example 4
The same procedure as in Experimental Example 1 was conducted except that C 2 AH 8 ( 2) was used and the temperature timing for increasing the oxygen partial pressure was changed as shown in Table 4. The results are also shown in Table 4.
[0034]
[Table 4]
Experimental Example 5
The same procedure as in Experimental Example 1 was conducted except that C 2 AH 8 ( 2) was used and the oxygen partial pressure was changed as shown in Table 5. The results are also shown in Table 5.
[0036]
[Table 5]
【The invention's effect】
According to the method for synthesizing a substance that includes an active oxygen species of the present invention, a substance that includes an active oxygen species having a very high specific surface area and a large amount of active oxygen species can be obtained.
Moreover, it is a synthesis method that can be synthesized at a lower heat treatment temperature than the conventional one, has a small energy basic unit, and has a small environmental load.
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| JP2006240954A (en) * | 2005-03-07 | 2006-09-14 | Denki Kagaku Kogyo Kk | Oxidization acceleration material, and oxidization acceleration method using the same |
| WO2010090266A1 (en) * | 2009-02-05 | 2010-08-12 | 旭硝子株式会社 | Method for manufacturing mayenite-containing oxides and method for manufacturing conductive mayenite-containing oxides |
| WO2010095552A1 (en) * | 2009-02-17 | 2010-08-26 | 旭硝子株式会社 | Process for producing mayenite-containing oxide, and process for producing electrically conductive mayenite-containing oxide |
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| JP2006240954A (en) * | 2005-03-07 | 2006-09-14 | Denki Kagaku Kogyo Kk | Oxidization acceleration material, and oxidization acceleration method using the same |
| WO2010090266A1 (en) * | 2009-02-05 | 2010-08-12 | 旭硝子株式会社 | Method for manufacturing mayenite-containing oxides and method for manufacturing conductive mayenite-containing oxides |
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| JP5569399B2 (en) * | 2009-02-05 | 2014-08-13 | 旭硝子株式会社 | Method for producing mayenite-containing oxide and method for producing conductive mayenite-containing oxide |
| WO2010095552A1 (en) * | 2009-02-17 | 2010-08-26 | 旭硝子株式会社 | Process for producing mayenite-containing oxide, and process for producing electrically conductive mayenite-containing oxide |
| JP2020142202A (en) * | 2019-03-07 | 2020-09-10 | 太平洋マテリアル株式会社 | Catalyst support and method for producing catalyst |
| JP7269562B2 (en) | 2019-03-07 | 2023-05-09 | 太平洋マテリアル株式会社 | Catalyst carrier and catalyst manufacturing method |
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