JP2012187484A - Catalyst, and method for producing the same - Google Patents
Catalyst, and method for producing the same Download PDFInfo
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- JP2012187484A JP2012187484A JP2011052184A JP2011052184A JP2012187484A JP 2012187484 A JP2012187484 A JP 2012187484A JP 2011052184 A JP2011052184 A JP 2011052184A JP 2011052184 A JP2011052184 A JP 2011052184A JP 2012187484 A JP2012187484 A JP 2012187484A
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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
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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- Y02P20/584—Recycling of catalysts
Abstract
Description
本発明の実施形態は、触媒とその製造方法に関する。 Embodiments described herein relate generally to a catalyst and a method for producing the catalyst.
環境に優しい資源の有効活用の観点から、バイオエタノールや木質チップを原料に、低コストで工業的に有用なカーボンナノ繊維を合成する試みがなされている。一般に、このカーボンの合成にはニッケルや鉄などの金属粒子が触媒として用いられ、その粒子径に合った径のカーボン繊維が作られている。したがって、均一なカーボン繊維を得るためには触媒である金属粒子のサイズをそろえることが一つの重要な要素となる。
これら金属微粒子のサイズを小さくする方法には、従来より溶液法や気相法により基板上に形成する方法が行われているが、これらの方法では昇温過程において凝集を起こしやすく、均一なカーボン生成を行うことが困難である。また、より高度な技術は高コストとなる。
From the viewpoint of effective utilization of environmentally friendly resources, attempts have been made to synthesize industrially useful carbon nanofibers at low cost from bioethanol and wood chips. In general, for synthesis of carbon, metal particles such as nickel and iron are used as a catalyst, and carbon fibers having a diameter corresponding to the particle diameter are produced. Therefore, in order to obtain uniform carbon fibers, it is an important factor to make the size of metal particles as a catalyst uniform.
In order to reduce the size of these metal fine particles, a method of forming on a substrate by a solution method or a gas phase method has been conventionally used. However, these methods tend to cause aggregation in the temperature rising process, and uniform carbon. It is difficult to generate. In addition, more advanced technology is costly.
そのような中、還元されやすい金属を含む酸化物と還元されにくい金属を含む酸化物の化合物から成る焼結体を還元することによって、還元雰囲気下でより不安定な金属成分を焼結体上に析出させる方法も提案されている。この方法によれば、酸化物焼結体上に金属微粒子を高密度に形成し、しかも基材と結合性をもって固定化させることができるため、高い熱的安定性が期待される。 Under such circumstances, by reducing a sintered body comprising an oxide containing a metal that is easily reduced and an oxide compound containing a metal that is difficult to reduce, a more unstable metal component is reduced on the sintered body in a reducing atmosphere. There has also been proposed a method of precipitating. According to this method, the metal fine particles can be formed on the oxide sintered body at a high density and can be fixed with a binding property to the base material, so that high thermal stability is expected.
しかし、この方法による金属微粒子の析出は主に焼結体を構成するセラミック粒子の粒界部にて起こるため、例えば水素雰囲気中など強い還元性の雰囲気下では気孔あるいは粒界を通じて水素ガスが焼結体の内部奥深くまで侵入し、全体的に析出反応が進行してしまう。その結果、このようにして作製した触媒を、カーボン生成用の触媒として用いると、焼結体内部からもカーボンの生成が起こり粒界を押し広げてしまうため、セラミック粒子がバラバラになってしまうという問題があった。また、仮に成形体の形を維持していたとしても、一度カーボンを生成・回収してしまうと、触媒である金属微粒子もカーボンと一緒に取り除かれてしまう可能性があり、使用は１回限りであった。実用化に向けては連続的に繰り返し使えることも不可欠である。 However, precipitation of metal fine particles by this method mainly occurs at the grain boundary portion of the ceramic particles constituting the sintered body. For example, in a highly reducing atmosphere such as a hydrogen atmosphere, hydrogen gas is burned through pores or grain boundaries. It penetrates deep into the inside of the aggregate and the precipitation reaction proceeds as a whole. As a result, when the catalyst produced in this way is used as a catalyst for carbon generation, the generation of carbon also occurs from the inside of the sintered body, and the grain boundaries are expanded, so that the ceramic particles are separated. There was a problem. Even if the shape of the compact is maintained, once the carbon is generated and recovered, the metal fine particles as the catalyst may be removed together with the carbon. Met. For practical application, it is also essential to be able to use it continuously and repeatedly.
実施形態は、再生利用可能な触媒とその製造方法を提供することを目的とする。 The embodiment aims to provide a recyclable catalyst and a method for producing the same.
実施形態の触媒は、アルミニウム、マグネシウム、クロムとマンガンからなる群から選ばれる一種類以上の金属である第一金属の酸化物の焼結組織と第一金属の酸化物の焼結組織の表面に分散したニッケル、鉄、コバルトと銅からなる群から選ばれる一種類以上の金属である第二金属の粒子とを有する第一の部分と、第一金属と第二金属との複合酸化物を含む焼結組織を有する第二の部分とを有するセラミックス焼結体の成形体であり、第一の部分は成形体の表層部に存在することを特徴とする。 The catalyst of the embodiment is formed on the surface of the sintered structure of the first metal oxide and the sintered structure of the first metal oxide, which are one or more metals selected from the group consisting of aluminum, magnesium, chromium, and manganese. A first portion having a second metal particle which is one or more kinds of metals selected from the group consisting of dispersed nickel, iron, cobalt and copper, and a composite oxide of the first metal and the second metal A sintered body of a ceramic sintered body having a second portion having a sintered structure, wherein the first portion exists in a surface layer portion of the molded body.
［触媒］
図１の実施形態にかかる触媒の構造概念図は、セラミックス粒子１２が焼結した成形体１０であって、成形体は第一の部分と第二の部分の焼結組織とに分けられる。第一の部分は成形体の表層部にあって、第二の部分は成形体の第一の部分を除く部分に存在する。第一金属の酸化物の焼結組織と第一金属の酸化物の焼結組織の表面に分散（点在）した第二金属の粒子１１とを有する第一の部分１３と、第一金属と第二金属との複合酸化物を含む焼結組織と有する第二の部分１４とを有する。第一金属の酸化物は第二金属の酸化物と比較して難還元性である。第一の部分は第二の部分上に設けられている。実施形態の触媒図１の概念図に示すように成形体表側にある第一の部分と、成形体内部にある第二の部分とで構成されている。
[catalyst]
The conceptual diagram of the structure of the catalyst according to the embodiment of FIG. 1 is a molded body 10 in which ceramic particles 12 are sintered, and the molded body is divided into a first portion and a sintered structure of a second portion. The first portion is in the surface layer portion of the molded body, and the second portion is present in a portion other than the first portion of the molded body. A first portion 13 having a sintered structure of a first metal oxide and a second metal particle 11 dispersed (spotted) on the surface of the sintered structure of the first metal oxide; And a second portion 14 having a sintered structure including a composite oxide with the second metal. The oxide of the first metal is difficult to reduce as compared with the oxide of the second metal. The first part is provided on the second part. Catalyst of Embodiment As shown in the conceptual diagram of FIG. 1, the catalyst is composed of a first part on the front side of the molded body and a second part inside the molded body.
［第一の部分］
第一の部分は、第一金属の酸化物の焼結組織と、第一金属の酸化物の焼結組織の表面に分散した第二金属の粒子とで少なくとも構成されている。
第一金属は、アルミニウム、マグネシウム、クロムとマンガンからなる群から選ばれる一種類以上の金属である。第一金属の酸化物は難還元性である。第二金属は、ニッケル、鉄、コバルトと銅からなる群から選ばれる一種類以上の金属である。第一金属の酸化物の表面に、第二金属の粒子が分散して存在する。
[First part]
The first portion includes at least a sintered structure of the first metal oxide and second metal particles dispersed on the surface of the sintered structure of the first metal oxide.
The first metal is one or more metals selected from the group consisting of aluminum, magnesium, chromium and manganese. The oxide of the first metal is difficult to reduce. The second metal is at least one metal selected from the group consisting of nickel, iron, cobalt and copper. The second metal particles are dispersed on the surface of the first metal oxide.
第一の部分は、第二の部分である第一金属と第二金属の複合酸化物（触媒材料）を還元して第二金属の酸化物が析出還元した部分であり、第二の部分ではこれが還元されていない。第一の部分には未還元の第二金属の酸化物や第一金属と第二金属の複合酸化物が一部に含まれる場合もある。上記の第一金属と第二金属の複合酸化物は、第一金属と第二金属の酸化物の固溶体又は第一金属と第二金属を含むスピネル型の複合酸化物である。 The first part is the part where the complex oxide (catalyst material) of the first metal and the second metal, which is the second part, is reduced and the oxide of the second metal is deposited and reduced. In the second part, This is not reduced. The first portion may include an unreduced second metal oxide or a composite oxide of the first metal and the second metal. The complex oxide of the first metal and the second metal is a solid solution of the oxide of the first metal and the second metal or a spinel type complex oxide containing the first metal and the second metal.
第一金属酸化物を主とする粒子の平均一次粒子径は、１μｍ以上５００μｍ以下である。
析出している金属粒子の平均直径は、１ｎｍ以上５００ｎｍ以下であり、より好ましくは１０ｎｍ以上であり、２００ｎｍ以下である。
ここで言う平均直径は、以下の順序で求められる。
第一に、電子顕微鏡により観察された画像を得る。
第二に、無作為に２０個以上の金属粒子を選ぶ。
第三に、選ばれた各粒子に対し、無作為に５つ以上の方向で粒子の幅を計った平均を求める。
第四に、選ばれた金属粒子すべての幅の平均値を合計し、選ばれ金属粒子の個数で除する。
第一の部分の粒子の平均一次粒子径は、１μｍ以上５００μｍ以下である。
The average primary particle size of particles mainly composed of the first metal oxide is 1 μm or more and 500 μm or less.
The average diameter of the deposited metal particles is 1 nm or more and 500 nm or less, more preferably 10 nm or more, and 200 nm or less.
The average diameter here is determined in the following order.
First, an image observed with an electron microscope is obtained.
Second, randomly select 20 or more metal particles.
Third, for each selected particle, determine the average of the particle widths in five or more directions at random.
Fourth, the average value of the widths of all selected metal particles is summed and divided by the number of selected metal particles.
The average primary particle diameter of the particles of the first portion is 1 μm or more and 500 μm or less.
［第二の部分］
一方、第二の部分は、上記第一金属と第二金属との複合酸化物が少なくとも含まれる焼結組織である。第二の部分の複合酸化物は、第一金属と第二金属の酸化物の固溶体又は第一金属と第二金属を含むスピネル型の複合酸化物である。前述の通り、第二の部分は、第一の部分と異なり、還元されていない触媒材料の部位である。第二の部分の複合酸化物が固溶体の場合は、第二金属酸化物と第一金属酸化物の比は、モル比で１：５００〜１：１が好ましい。第二の部分には上記の酸化物と金属粒子の他にケイ素を含む複合酸化物が含まれていることがある。第二の部分の粒子の平均一次粒子径は、１μｍ以上５００μｍ以下である。
[Second part]
On the other hand, the second part is a sintered structure containing at least a composite oxide of the first metal and the second metal. The complex oxide of the second part is a solid solution of the oxide of the first metal and the second metal or a spinel type complex oxide containing the first metal and the second metal. As described above, unlike the first portion, the second portion is a portion of the catalyst material that has not been reduced. When the composite oxide of the second part is a solid solution, the molar ratio of the second metal oxide to the first metal oxide is preferably 1: 500 to 1: 1. The second portion may contain a composite oxide containing silicon in addition to the above oxide and metal particles. The average primary particle diameter of the particles of the second portion is 1 μm or more and 500 μm or less.
［触媒の成形体］
触媒の成形体の形状は特に限定されないが、カーボンの製造に用いることを考慮すれば、板状又はハニカム状が好ましい。ハニカム状の触媒の場合は、通気性の気孔に面する部分が第一の部分にあたり、壁面の内部が第二の部分にあたるとものとする。触媒の成形体の形状が球であれば、内部に第二の部分があり、表面に第一の部分がある形態となる。成形体は、内部へ還元が進行しないように緻密質であることが好ましい。
[Catalyst compact]
The shape of the catalyst molded body is not particularly limited, but a plate shape or a honeycomb shape is preferable in consideration of use in the production of carbon. In the case of a honeycomb-shaped catalyst, the portion facing the air-permeable pores corresponds to the first portion, and the inside of the wall surface corresponds to the second portion. If the shape of the catalyst compact is a sphere, the second part is present inside and the first part is present on the surface. The molded body is preferably dense so that reduction does not proceed inside.
第一の部分の金属粒子が反応に寄与する触媒として機能するため、触媒の成形体表面の表層部に第二金属が析出した第一の部分が存在していればよい。触媒の成形体の形状にもよるが面が複数ある触媒の場合は、少なくとも１つの面に第一の部分が存在していればよい。
第一の部分と第二の部分は還元されたものか否かという違いであるため、必ずしも両者に明確な界面というものが存在する必要はない。
Since the metal particles of the first part function as a catalyst that contributes to the reaction, it is only necessary that the first part where the second metal is deposited is present on the surface layer part of the surface of the molded article of the catalyst. In the case of a catalyst having a plurality of surfaces, depending on the shape of the catalyst molded body, it is sufficient that the first portion is present on at least one surface.
Since the difference between the first part and the second part is whether or not they are reduced, it is not always necessary to have a clear interface between them.
次に、実施形態の触媒の製造方法について説明する。
［触媒材料の成形］
第一金属酸化物および第二金属酸化物により構成される固溶体あるいは第一と第二の金属を有するスピネル型の複合酸化物からなる触媒材料の成形体（セラミックス焼結体）を作製する。成形体の作成方法は公知の方法を採用することができる。これら成形体は緻密質な構造体に作製することが好ましい。成形体が緻密であれば、触媒内部への還元の進行が少ないことが好ましい。組み合わせる材料にも依るが、特に溶解等するもので無い限り、１２００℃以上の高温で焼結することが成形体の緻密性の観点から好ましい。
Next, the manufacturing method of the catalyst of embodiment is demonstrated.
[Molding of catalyst material]
A molded body (ceramic sintered body) of a catalyst material made of a solid solution composed of the first metal oxide and the second metal oxide or a spinel type complex oxide having the first and second metals is prepared. A well-known method can be employ | adopted for the preparation methods of a molded object. These molded bodies are preferably produced into a dense structure. If the molded body is dense, it is preferable that the reduction progresses into the catalyst. Although it depends on the material to be combined, it is preferable from the viewpoint of the compactness of the molded body to be sintered at a high temperature of 1200 ° C. or higher unless it is particularly dissolved.
［触媒材料（成形体）の還元］
次に、前記成形体の還元を行いたい面に炭素含有化合物を接触させて、アルゴンや窒素などの不活性ガスを流通させて、炭素含有化合物を直接接触させた面を８００℃以上１４００℃以下の温度に加熱して還元する。炭素含有化合物としては、グラファイトやアモルファスカーボンなどの炭素そのものや、高温で炭化する有機物質を塗布した材料をそのままあるいは加熱により炭化させた材料であってもよい。還元に用いる炭素含有化合物は、不活性ガス雰囲気中では還元材として働き、成形体の表層部から酸素を奪うことになる。これにより、成形体の表層部のみが選択的に還元され、炭素が供給されない成形体の内部（深部）は還元されない。よって、成形体表面の表層部のみの第二金属酸化物を還元して析出させることができる。用いる炭素含有化合物の種類、第一金属及び第二金属の種類、及び還元温度にもよるが、還元される深さは成形体の表面から１μｍ以上１５０μｍ以下であることが多い。触媒によるカーボン生成反応が成形体の表層部で進むことで、成形体内部（深部）での反応進行による成形体の崩壊を防ぐことができる。また、実際に収集される生成カーボンは成形体の表層部で反応したものが多いことから、１５０μm程度の深さまで還元されていれば充分である場合が多い。還元された部分が、第一の部分となり、還元されなかった部分が第二の部分となる。実施形態の方法で還元すると、析出する金属粒子の平均一次粒子径は、上記の範囲となり、触媒能が高く、凝集しにくい安定な触媒となることが好ましい。
[Reduction of catalyst material (molded body)]
Next, the surface of the molded body to be reduced is brought into contact with a carbon-containing compound, an inert gas such as argon or nitrogen is circulated, and the surface directly brought into contact with the carbon-containing compound is 800 ° C. or higher and 1400 ° C. or lower. Heat to the temperature and reduce. The carbon-containing compound may be carbon such as graphite or amorphous carbon, or a material obtained by carbonizing a material coated with an organic substance that is carbonized at a high temperature as it is or by heating. The carbon-containing compound used for the reduction works as a reducing material in an inert gas atmosphere, and deprives oxygen from the surface layer portion of the molded body. Thereby, only the surface layer part of the molded body is selectively reduced, and the inside (deep part) of the molded body to which no carbon is supplied is not reduced. Therefore, it is possible to reduce and deposit the second metal oxide only on the surface layer portion on the surface of the molded body. Although depending on the type of carbon-containing compound used, the types of the first metal and the second metal, and the reduction temperature, the depth to be reduced is often from 1 μm to 150 μm from the surface of the molded body. Since the carbon generation reaction by the catalyst proceeds in the surface layer portion of the molded body, it is possible to prevent the molded body from collapsing due to the progress of the reaction in the molded body (in the deep part). Further, since the produced carbon that is actually collected often reacts in the surface layer of the molded body, it is often sufficient that the carbon is reduced to a depth of about 150 μm. The reduced part becomes the first part, and the part that has not been reduced becomes the second part. When reduced by the method of the embodiment, the average primary particle diameter of the deposited metal particles is preferably in the above range, and it is preferable to be a stable catalyst that has high catalytic ability and is difficult to aggregate.
この時の熱処理の適正な温度や時間はセラミックス焼結体である成形体の成分によっても異なるが、実施形態では９００℃以上１２００℃以下が好ましい。９００℃より温度が低い場合には還元による微粒子の析出が十分ではなく、一方、１２００℃より温度が高い場合には析出が過度に進み、微粒子同士が結合して触媒として適さない大きな粒子になってしまうからである。また、還元が成形体の表層部から深さ方向により進行してしまう恐れもある。したがって、熱処理時間に関しても必要以上に長く行わないことが好ましい。具体的には、０．５時間以上５時間以内であることが好ましい。第一の部分の厚さはごく表層部のみでよく、１０μｍもあれば十分であり、１０μｍ以下でもよい。 The appropriate temperature and time for the heat treatment at this time vary depending on the components of the molded body, which is a ceramic sintered body, but in the embodiment, 900 ° C. or higher and 1200 ° C. or lower is preferable. When the temperature is lower than 900 ° C., precipitation of fine particles due to reduction is not sufficient. On the other hand, when the temperature is higher than 1200 ° C., precipitation proceeds excessively, and the fine particles are combined to become large particles that are not suitable as a catalyst. Because it will end up. Further, there is a possibility that the reduction proceeds in the depth direction from the surface layer portion of the molded body. Therefore, it is preferable not to perform the heat treatment time longer than necessary. Specifically, it is preferably 0.5 hours or more and 5 hours or less. The thickness of the first portion may be only the surface layer portion, and 10 μm is sufficient, and may be 10 μm or less.
炭素含有化合物は、還元の際に揮発して失われないように、還元温度で全く蒸発しない物質であることが好ましい。ただし、一部が熱分解により失われた後、炭素を含有する成分が残留する場合は適切な炭素化合物として使用することができる。還元に用いる炭素としては、グラファイト、アモルファスカーボン、カーボンナノチューブ、カーボンファイバーの成形体等が挙げられる。還元に用いる有機材料としてはショ糖、グルコース、石油ピッチ等を用いることができる。 The carbon-containing compound is preferably a substance that does not evaporate at the reduction temperature so that it is not lost by volatilization during the reduction. However, after a part is lost by thermal decomposition, when the component containing carbon remains, it can be used as a suitable carbon compound. Examples of carbon used for the reduction include graphite, amorphous carbon, carbon nanotube, and carbon fiber molded body. As the organic material used for the reduction, sucrose, glucose, petroleum pitch and the like can be used.
［触媒を用いた炭素の生成］
実施形態の触媒を用いて、公知の製造条件で炭素を生成することができる。
例えば、触媒を反応炉の中に入れ、不活性ガス雰囲気で炉内を満たし、所定の温度に加熱する。所定の温度に達したら、エタノールなどの炭化水素の蒸気を炉内に導入して、６５０℃で３０分間、炭化水素を反応させて炭素を生成する。
[Production of carbon using catalyst]
Carbon can be produced under known production conditions using the catalyst of the embodiment.
For example, the catalyst is put into a reaction furnace, the inside of the furnace is filled with an inert gas atmosphere, and heated to a predetermined temperature. When a predetermined temperature is reached, hydrocarbon steam such as ethanol is introduced into the furnace, and the hydrocarbon is reacted at 650 ° C. for 30 minutes to generate carbon.
［触媒の再生方法］
また、実施形態の触媒を用いれば、生成した炭素の回収時に炭素とともに第一の部分の第二金属の粒子が脱落してしまったとしても、表層部を再度還元処理して再び、触媒を再生することができる。上記還元の工程と同様の工程によって触媒を還元して、触媒を再生することができる。なお、還元用の炭素含有化合物として、生成した炭素を用いてもよい。生成した炭素を触媒の再生に用いる場合は、生成した炭素を回収する際に一部触媒の表面に生成した炭素を触媒に残せばよい。未還元の第二の部分が存在する間は、繰り返し再生して使用することが可能になる。これにより、触媒の生成と炭素の生成を繰り返し行うことが可能になる。
[Catalyst regeneration method]
Further, if the catalyst of the embodiment is used, even if the second metal particles in the first part are dropped together with the carbon when the produced carbon is recovered, the surface layer part is reduced again to regenerate the catalyst again. can do. The catalyst can be regenerated by reducing the catalyst by the same step as the reduction step. In addition, you may use the produced | generated carbon as a carbon containing compound for a reduction | restoration. When the produced carbon is used for regeneration of the catalyst, the produced carbon may be partially left on the surface of the catalyst when the produced carbon is recovered. While there is an unreduced second portion, it can be regenerated and used repeatedly. This makes it possible to repeatedly perform catalyst generation and carbon generation.
本実施の形態について実施例によってさらに詳細に説明する。
（比較例１）
酸化ニッケル粉末と酸化マグネシウム粉末をそれぞれモル比で１：２となるように混合し、板状にプレス成形したのち、大気中１４００℃で焼結してＮｉＯ−ＭｇＯ固溶体からなる酸化物焼結体を作製した。前記焼結体を水素雰囲気のもと、９００℃で１０分間還元処理を行い、焼結体の表面および内部にニッケル金属の微粒子を析出させた。この試料を石英製の管状炉に入れ、アルゴン雰囲気に満たしたのち、所定の温度に昇温してからエタノール蒸気を導入して６５０℃で３０分間、炭素生成試験を行った。
This embodiment will be described in more detail with reference to examples.
(Comparative Example 1)
Nickel oxide powder and magnesium oxide powder are mixed at a molar ratio of 1: 2, pressed into a plate shape, sintered in air at 1400 ° C., and an oxide sintered body made of NiO—MgO solid solution. Was made. The sintered body was subjected to a reduction treatment at 900 ° C. for 10 minutes under a hydrogen atmosphere to deposit nickel metal fine particles on the surface and inside of the sintered body. This sample was placed in a quartz tube furnace and filled with an argon atmosphere. After raising the temperature to a predetermined temperature, ethanol vapor was introduced and a carbon generation test was conducted at 650 ° C. for 30 minutes.
（比較例２）
酸化ニッケル粉末と酸化アルミニウム粉末をそれぞれモル比で１：１となるように混合し、板状にプレス成形したのち、大気中１４００℃で焼結してスピネル型酸化物ＮｉＡｌ２Ｏ４を５０重量％以上含有する焼結体を得た。前記焼結体を水素雰囲気のもと、９００℃で１０分間還元処理を行い、焼結体の表面および内部にニッケル金属の微粒子を析出させた。この試料を石英製の管状炉に入れ、アルゴン雰囲気に満たしたのち、所定の温度に昇温してからエタノール蒸気を導入し、６５０℃で３０分間、炭素生成試験を行った。
(Comparative Example 2)
Nickel oxide powder and aluminum oxide powder were mixed at a molar ratio of 1: 1, pressed into a plate shape, sintered in air at 1400 ° C., and spinel-type oxide NiAl 2 O 4 of 50 wt. A sintered body containing at least% was obtained. The sintered body was subjected to a reduction treatment at 900 ° C. for 10 minutes under a hydrogen atmosphere to deposit nickel metal fine particles on the surface and inside of the sintered body. This sample was placed in a quartz tube furnace and filled with an argon atmosphere. After raising the temperature to a predetermined temperature, ethanol vapor was introduced, and a carbon generation test was performed at 650 ° C. for 30 minutes.
（実施例１）
比較例１と同様の方法にて作製したＮｉＯ−ＭｇＯ固溶体の板状焼結体の上に耐火性のカーボン板を接触させてアルゴン雰囲気中、１０００℃にて１時間熱処理を行った。この試料を石英製の管状炉に入れ、アルゴン雰囲気に満たしたのち、所定の温度に昇温してからエタノール蒸気を導入し、６５０℃にて炭素生成試験を行った。
Example 1
A refractory carbon plate was brought into contact with a NiO—MgO solid solution plate-like sintered body produced by the same method as in Comparative Example 1, and heat treatment was performed at 1000 ° C. for 1 hour in an argon atmosphere. This sample was placed in a quartz tube furnace and filled with an argon atmosphere. After raising the temperature to a predetermined temperature, ethanol vapor was introduced and a carbon generation test was conducted at 650 ° C.
（実施例２）
実施例１と同様の方法にて作製したＮｉＯ−ＭｇＯ固溶体の板状焼結体の上に耐火性のカーボン板を接触させてアルゴン雰囲気中、１２００℃にて１時間熱処理を行った。この試料を石英製の管状炉に入れ、アルゴン雰囲気に満たしたのち、所定の温度に昇温してからエタノール蒸気を導入し、６５０℃にてカーボン生成試験を行った。
(Example 2)
A refractory carbon plate was brought into contact with a NiO—MgO solid solution plate-like sintered body produced by the same method as in Example 1 and heat-treated at 1200 ° C. for 1 hour in an argon atmosphere. This sample was placed in a quartz tube furnace and filled with an argon atmosphere. After raising the temperature to a predetermined temperature, ethanol vapor was introduced and a carbon generation test was conducted at 650 ° C.
（実施例３）
実施例１と同様の方法にて作製したＮｉＯ−ＭｇＯ固溶体の板状焼結体の上に耐火性のカーボン板を接触させてアルゴン雰囲気中、９００℃にて１時間熱処理を行った。この試料を石英製の管状炉に入れ、アルゴン雰囲気に満たしたのち、所定の温度に昇温してからエタノール蒸気を導入し、６５０℃にてカーボン生成試験を行った。
(Example 3)
A refractory carbon plate was brought into contact with a NiO—MgO solid solution plate-like sintered body produced by the same method as in Example 1, and heat treatment was performed at 900 ° C. for 1 hour in an argon atmosphere. This sample was placed in a quartz tube furnace and filled with an argon atmosphere. After raising the temperature to a predetermined temperature, ethanol vapor was introduced and a carbon generation test was conducted at 650 ° C.
（比較例３）
カーボン板と接触させての熱処理温度を８００℃としたこと以外はすべて同様に試料を作製し、同様に炭素生成試験を行った。
(Comparative Example 3)
Samples were prepared in the same manner except that the heat treatment temperature in contact with the carbon plate was 800 ° C., and the carbon generation test was similarly conducted.
（比較例４）
カーボン板と接触させての熱処理温度を１４００℃としたこと以外はすべて同様に試料を作製し、同様に炭素生成試験を行った。
(Comparative Example 4)
Samples were prepared in the same manner except that the heat treatment temperature in contact with the carbon plate was 1400 ° C., and the carbon generation test was similarly conducted.
（実施例４）
比較例２と同様の方法にて作製したＮｉＡｌ２Ｏ４スピネル型酸化物焼結体の上に耐火性のカーボン板を接触させてアルゴン中、１０００℃にて１時間熱処理を行った。この試料を石英製の管状炉に入れ、実施例１と同様の方法にて炭素生成試験を行った。
Example 4
A refractory carbon plate was brought into contact with the NiAl 2 O 4 spinel oxide sintered body produced by the same method as in Comparative Example 2, and heat treatment was performed at 1000 ° C. for 1 hour in argon. This sample was placed in a quartz tubular furnace, and a carbon production test was conducted in the same manner as in Example 1.
（実施例５）
実施例１で作製した試料をカーボン生成用の大型加熱炉内に設置し、実施例１と同様の条件にて蒸気化したエタノールを導入し炭素生成試験を行った。炭素生成後、焼結体表面に生成した炭素を払い取り回収したのち、試料にカーボン板を接触させるようにして窒素ガスを導入し１０００℃で１時間熱処理を行った。その後、再びエタノールを蒸気化して導入してカーボンの生成試験を行った。
(Example 5)
The sample produced in Example 1 was placed in a large heating furnace for carbon production, and ethanol produced under the same conditions as in Example 1 was introduced to conduct a carbon production test. After carbon generation, the carbon generated on the surface of the sintered body was wiped and collected, and then nitrogen gas was introduced so that the carbon plate was brought into contact with the sample and heat treatment was performed at 1000 ° C. for 1 hour. Thereafter, ethanol was again vaporized and introduced to conduct a carbon production test.
（実施例６）
試料の再生（再還元処理）に、炭素を生成し回収した後に残留した炭素を用いて窒素ガスを導入し１０００℃で１時間熱処理を行った。その後、再びエタノールを蒸気化して導入し、炭素の生成試験を行った。
以下に結果について示す。
(Example 6)
For regeneration (re-reduction treatment) of the sample, nitrogen gas was introduced using carbon remaining after carbon was generated and recovered, and heat treatment was performed at 1000 ° C. for 1 hour. Thereafter, ethanol was again vaporized and introduced, and a carbon production test was conducted.
The results are shown below.
（比較例１、２）
いずれも還元処理により重量減少が起こり、ニッケル微粒子の析出が確認された。しかし、炭素生成試験後、（比較例１）では炭素の生成とともに基材となる焼結体の部分的な崩壊が見られた。一方、（比較例２）では多量の炭素の生成とともに焼結体そのものの崩壊が生じた。走査型電子顕微鏡（ＳＥＭ）による観察の結果、生成した炭素中に多数の焼結体を構成していたセラミックス粒子（大きさ約１μｍ）が観察され、焼結体は炭素の生成とともに粒子界面（粒界）でバラバラにされているのがわかった。
(Comparative Examples 1 and 2)
In all cases, weight reduction occurred due to reduction treatment, and precipitation of nickel fine particles was confirmed. However, after the carbon generation test, in (Comparative Example 1), partial collapse of the sintered body serving as the base material was observed along with the generation of carbon. On the other hand, in (Comparative Example 2), the sintered body itself collapsed along with the generation of a large amount of carbon. As a result of observation by a scanning electron microscope (SEM), ceramic particles (size: about 1 μm) constituting a large number of sintered bodies were observed in the generated carbon. It was found that the grain boundaries were broken apart.
（実施例１）
カーボン板を接触させ還元処理した焼結体は、表層部の深さ１０μｍ程度に渡ってニッケル微粒子の析出が観察された。ニッケル粒子の大きさは平均８０ｎｍ程度であった。ニッケル微粒子は基材である焼結体と結合しており、適度な感覚を持って分散していた。
この試料を用いて炭素合成を行った結果、直径１００ｎｍ程度の均一な炭素ナノ繊維の生成が確認された。なお、焼結体の崩壊は起こらず、硬いままであった。
Example 1
In the sintered body subjected to the reduction treatment by contacting the carbon plate, precipitation of nickel fine particles was observed over a depth of about 10 μm of the surface layer portion. The average size of the nickel particles was about 80 nm. The nickel fine particles were bonded to the sintered body as the base material and were dispersed with an appropriate feeling.
As a result of carbon synthesis using this sample, formation of uniform carbon nanofibers having a diameter of about 100 nm was confirmed. The sintered body did not collapse and remained hard.
（実施例２）
実施例１と同様に焼結体の表層部分に２００ｎｍサイズ程度のニッケル微粒子が確認された。この試料を用いてカーボン合成を行った結果、直径２００ｎｍ程度の均一な炭素ナノ繊維が生成した。なお、焼結体の崩壊は起こっていない。
(Example 2)
Similar to Example 1, nickel fine particles having a size of about 200 nm were confirmed on the surface layer portion of the sintered body. As a result of carbon synthesis using this sample, uniform carbon nanofibers having a diameter of about 200 nm were produced. Note that the sintered body did not collapse.
（実施例３）
カーボン板を接触させ還元処理した焼結体は、表層部の深さ５μｍ程度に渡ってニッケル微粒子の析出が観察された。ニッケル粒子の大きさは平均５０ｎｍ程度であった。ニッケル微粒子は基材である焼結体と結合しており、適度な感覚を持って分散していた。
この試料を用いて炭素合成を行った結果、直径５０ｎｍ程度の均一な炭素ナノ繊維の生成が確認された。なお、焼結体の崩壊は起こらず、硬いままであった。
(Example 3)
In the sintered body subjected to the reduction treatment by contacting the carbon plate, precipitation of nickel fine particles was observed over a depth of about 5 μm of the surface layer portion. The average size of the nickel particles was about 50 nm. The nickel fine particles were bonded to the sintered body as the base material and were dispersed with an appropriate feeling.
As a result of carbon synthesis using this sample, formation of uniform carbon nanofibers having a diameter of about 50 nm was confirmed. The sintered body did not collapse and remained hard.
（比較例３）
焼結体のごく表層部にニッケル粒子の析出が見られた。サイズは微細で１０ｎｍ程度であり、数もまばらであった。この試料を用いた炭素生成試験では、焼結体の崩壊は起こらないものの、炭素の生成はほとんど確認されなかった。
(Comparative Example 3)
Precipitation of nickel particles was observed on the very surface portion of the sintered body. The size was fine, about 10 nm, and the number was sparse. In the carbon production test using this sample, although the sintered body did not collapse, almost no carbon production was confirmed.
（比較例４）
焼結体の奥深く、約２００μｍの深さまでニッケル粒子の析出が見られた。ニッケル粒子のサイズもミクロン単位の大きさにまで成長していた。この試料を用いた炭素生成試験ではナノサイズの微細な炭素繊維を得ることはできなかった。
(Comparative Example 4)
Precipitation of nickel particles was observed to a depth of about 200 μm deep in the sintered body. The size of the nickel particles has grown to a micron size. In the carbon production test using this sample, it was not possible to obtain nano-sized fine carbon fibers.
（実施例４）
実施例１と同様に焼結体の表層部分に１００ｎｍサイズ程度のニッケル微粒子が確認された。この試料を用いて炭素合成を行った結果、直径３０ｎｍ程度の均一な炭素ナノ繊維が生成した。なお、焼結体の崩壊は起こっていない。
なお、鉄酸化物およびコバルト酸化物を用いて複合酸化物焼結体を作製し、カーボン板による還元後、同様の炭素生成試験を行ったが、いずれも１００ｎｍ以下のサイズの炭素ナノ繊維が合成され、焼結体の崩壊が起こらないことを確認した。
Example 4
Similar to Example 1, nickel fine particles having a size of about 100 nm were confirmed on the surface layer portion of the sintered body. As a result of carbon synthesis using this sample, uniform carbon nanofibers having a diameter of about 30 nm were produced. Note that the sintered body did not collapse.
A composite oxide sintered body was prepared using iron oxide and cobalt oxide, and after a reduction with a carbon plate, a similar carbon generation test was performed. In each case, carbon nanofibers having a size of 100 nm or less were synthesized. It was confirmed that the sintered body did not collapse.
（実施例５、６）
実施例５および６においても、一度炭素生成試験を行った試料は崩壊せずそのままで、再度カーボンによる還元後、再び炭素の生成が行えることを確認した。
本発明によれば、カーボン生成炉の中で炉を開けることなく触媒の還元およびカーボンの生成が行えるようになり、製造工程が簡略化でき、効率が向上する。
(Examples 5 and 6)
Also in Examples 5 and 6, it was confirmed that the sample once subjected to the carbon generation test was not collapsed and was able to generate carbon again after reduction with carbon again.
According to the present invention, the reduction of the catalyst and the generation of carbon can be performed without opening the furnace in the carbon generating furnace, the manufacturing process can be simplified, and the efficiency is improved.
本発明のいくつかの実施形態を説明したが、これらの実施形態は、例として提示したものであり、発明の範囲を限定することは意図していない。これら実施形態は、その他の様々な形態で実施されることが可能であり、発明の要旨を逸脱しない範囲で、種々の省略、置き換え、変更を行うことができる。これら実施形態やその変形は、発明の範囲や要旨に含まれると同様に、特許請求の範囲に記載された発明とその均等の範囲に含まれるものである。 Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.
１０・・・焼結成形体
１１・・・金属微粒子
１２・・・成形体を構成するセラミックス粒子
１３・・・第一の部分
１４・・・第二の部分
DESCRIPTION OF SYMBOLS 10 ... Sintered compact 11 ... Metal fine particle 12 ... Ceramic particle 13 which comprises a compact | molding | casting ... 1st part 14 ... 2nd part
Claims (5)
前記第一金属と前記第二金属との複合酸化物を含む焼結組織を有する第二の部分と、
を有するセラミックス焼結体の成形体であり、
前記第一の部分は前記成形体の表層部に存在することを特徴とする触媒。 Sintered structure of one or more kinds of first metal oxides selected from the group consisting of aluminum, magnesium, chromium and manganese, and nickel, iron and cobalt dispersed on the surface of the sintered structure of the first metal oxides And a first portion having one or more kinds of second metal particles selected from the group consisting of copper,
A second portion having a sintered structure containing a composite oxide of the first metal and the second metal;
A ceramic sintered compact having
Said 1st part exists in the surface layer part of the said molded object, The catalyst characterized by the above-mentioned.
The method for producing a catalyst according to claim 4, wherein the carbon-containing compound is carbon or an organic compound.
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