JP5547936B2 - Ammonia decomposition catalyst, production method thereof, and ammonia treatment method - Google Patents
Ammonia decomposition catalyst, production method thereof, and ammonia treatment method Download PDFInfo
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Description
本発明は、アンモニアを窒素と水素とに分解する触媒およびその製造方法、ならびに、この触媒を用いたアンモニア処理方法に関する。 The present invention relates to a catalyst for decomposing ammonia into nitrogen and hydrogen, a method for producing the catalyst, and an ammonia treatment method using the catalyst.
アンモニアは、臭気性、特に刺激性の悪臭を有するので、ガス中に臭気閾値以上含まれる場合には、これを処理することが必要となる。そこで、従来から様々なアンモニア処理方法が検討されてきた。例えば、アンモニアを酸素と接触させて窒素と水とに酸化する方法、アンモニアを窒素と水素とに分解する方法などが提案されている。 Since ammonia has an odorous property, particularly an irritating malodor, it is necessary to treat it when the gas contains an odor threshold value or more. Therefore, various ammonia treatment methods have been conventionally studied. For example, a method in which ammonia is brought into contact with oxygen and oxidized into nitrogen and water, and a method in which ammonia is decomposed into nitrogen and hydrogen have been proposed.
例えば、特許文献１には、コークス炉から生じるアンモニアを窒素と水とに酸化するにあたり、例えば、白金−アルミナ触媒、マンガン−アルミナ触媒、コバルト−アルミナ触媒などを用いると共に、コークス炉から生じるアンモニアを窒素と水素とに分解するにあたり、例えば、鉄−アルミナ触媒、ニッケル−アルミナ触媒などを用いるアンモニア処理方法が開示されている。しかし、このアンモニア処理方法は、ＮＯｘが副生することが多いことから、新たにＮＯｘ処理設備が必要となるので、好ましくない。 For example, Patent Document 1 discloses that, for example, a platinum-alumina catalyst, a manganese-alumina catalyst, a cobalt-alumina catalyst, and the like are used to oxidize ammonia generated from a coke oven to nitrogen and water, and ammonia generated from the coke oven is used. In decomposing into nitrogen and hydrogen, for example, an ammonia treatment method using an iron-alumina catalyst, a nickel-alumina catalyst, or the like is disclosed. However, this ammonia treatment method is not preferable because NOx is often produced as a by-product and a new NOx treatment facility is required.
また、特許文献２および３には、それぞれ、有機性廃棄物を処理する工程から生じるアンモニア、または、コークス炉から生じるアンモニアを、窒素と水素とに分解するにあたり、アルミナ、シリカ、チタニア、ジルコニアなどの金属酸化物担体上にニッケルまたはニッケル酸化物を担持させ、さらにアルカリ土類金属およびランタノイド元素の少なくとも一方を金属または酸化物の形で添加した触媒を用いるアンモニア処理方法が開示されている。しかし、このアンモニア処理方法は、アンモニア分解率が低く、実用的ではない。 Patent Documents 2 and 3 disclose, for example, alumina, silica, titania, zirconia, etc. in decomposing ammonia generated from a process of treating organic waste or ammonia generated from a coke oven into nitrogen and hydrogen. Discloses an ammonia treatment method using a catalyst in which nickel or nickel oxide is supported on the metal oxide support and at least one of an alkaline earth metal and a lanthanoid element is added in the form of a metal or oxide. However, this ammonia treatment method has a low ammonia decomposition rate and is not practical.
さらに、特許文献４には、コークス炉から生じるアンモニアを窒素と水素とに分解するにあたり、アルミナ担体上のルテニウムにアルカリ金属またはアルカリ土類金属の塩基性化合物を添加した触媒を用いるアンモニア処理方法が開示されている。このアンモニア処理方法は、従来の鉄−アルミナなどの触媒に比べて、より低温でアンモニアを分解できるという利点があるにもかかわらず、活性金属種として、希少貴金属であるルテニウムを用いているので、コスト面で大きな問題を抱えており、実用的ではない。 Further, Patent Document 4 discloses an ammonia treatment method using a catalyst in which an alkali metal or an alkaline earth metal basic compound is added to ruthenium on an alumina support for decomposing ammonia generated from a coke oven into nitrogen and hydrogen. It is disclosed. This ammonia treatment method uses ruthenium, which is a rare noble metal, as an active metal species, despite the advantage that ammonia can be decomposed at a lower temperature than a conventional catalyst such as iron-alumina. It has a big problem in cost and is not practical.
その他、アンモニアの分解によって回収された水素を燃料電池用の水素源として利用することが検討されているが、この場合は、高純度の水素を得ることが必要となる。これまでに提案されてきたアンモニア分解触媒を用いて、高純度の水素を得ようとすると、非常に高い反応温度が必要となり、あるいは、高価な触媒を多量に用いる必要があるという問題があった。 In addition, it has been studied to use hydrogen recovered by decomposition of ammonia as a hydrogen source for a fuel cell. In this case, it is necessary to obtain high-purity hydrogen. When trying to obtain high-purity hydrogen using the ammonia decomposition catalysts proposed so far, there is a problem that a very high reaction temperature is required or a large amount of an expensive catalyst needs to be used. .
このような問題を解決するために、アンモニアを比較的低温（約４００〜５００℃）で分解できる触媒として、例えば、特許文献４には、鉄−セリア複合体が開示され、特許文献５には、ニッケル−酸化ランタン／アルミナ、ニッケル−イットリア／アルミナ、ニッケル−セリア／アルミナの３元系複合体が開示され、非特許文献１には、鉄−セリア／ジルコニアの３元系複合体が開示されている。 In order to solve such a problem, as a catalyst capable of decomposing ammonia at a relatively low temperature (about 400 to 500 ° C.), for example, Patent Document 4 discloses an iron-ceria complex, and Patent Document 5 discloses Nickel-lanthanum oxide / alumina, nickel-yttria / alumina, nickel-ceria / alumina ternary composites are disclosed, and Non-Patent Document 1 discloses an iron-ceria / zirconia ternary composite. ing.
しかし、これらの触媒は、いずれも、処理ガスのアンモニア濃度が低い（具体的には、特許文献４は５体積％、特許文献５は５０体積％）か、あるいは、アンモニアを基準とした空間速度が低い（具体的には、特許文献４は６４２ｈ−１、特許文献５は１，０００ｈ−１、非特許文献１は４３０ｈ−１）といった条件下で、アンモニア分解率を測定しているので、たとえ、アンモニア分解率が比較的低温で１００％であるからと言っても、必ずしも触媒性能が高いわけではない。
However, any of these catalysts has a low ammonia concentration in the processing gas (specifically, 5% by volume in
このように、従来のアンモニア分解触媒は、いずれも、アンモニアを比較的低温で、かつ、高い空間速度で効率よく分解して高純度の水素を取得することはできないという問題があった。 As described above, each of the conventional ammonia decomposition catalysts has a problem that it is not possible to obtain high-purity hydrogen by efficiently decomposing ammonia at a relatively low temperature and at a high space velocity.
上述した状況の下、本発明が解決すべき課題は、コスト面で実用上の問題がある貴金属を用いることなく、低濃度から高濃度までの広範囲なアンモニア濃度域において、アンモニアを比較的低温で、かつ、高い空間速度で窒素と水素とに効率よく分解して高純度の水素を取得できる触媒およびその製造方法、ならびに、アンモニア処理方法を提供することにある。 Under the circumstances described above, the problem to be solved by the present invention is that ammonia is used at a relatively low temperature in a wide ammonia concentration range from a low concentration to a high concentration without using a noble metal that has practical problems in terms of cost. Another object of the present invention is to provide a catalyst that can be efficiently decomposed into nitrogen and hydrogen at a high space velocity to obtain high purity hydrogen, a method for producing the catalyst, and an ammonia treatment method.
本発明者らは、種々検討の結果、鉄族金属を金属酸化物と組み合わせれば、アンモニアを比較的低温で、かつ、高い空間速度で窒素と水素とに効率よく分解して高純度の水素を取得できる触媒が得られることを見出して、本発明を完成した。 As a result of various studies, the inventors of the present invention, when combining an iron group metal with a metal oxide, efficiently decomposes ammonia into nitrogen and hydrogen at a relatively low temperature and at a high space velocity, thereby producing high purity hydrogen. The present invention has been completed by finding that a catalyst capable of obtaining the above can be obtained.
すなわち、本発明は、アンモニアを窒素と水素とに分解する触媒であって、触媒活性成分が鉄族金属および金属酸化物を含有することを特徴とするアンモニア分解触媒を提供する。本発明のアンモニア分解触媒において、前記金属酸化物は、セリア、ジルコニア、イットリア、酸化ランタン、アルミナ、マグネシア、酸化タングステンおよびチタニアよりなる群から選択される少なくとも１種であることが好ましい。また、前記触媒活性成分は、さらに、アルカリ金属および／またはアルカリ土類金属を含有していてもよい。 That is, the present invention provides a catalyst for decomposing ammonia into nitrogen and hydrogen, wherein the catalytically active component contains an iron group metal and a metal oxide. In the ammonia decomposition catalyst of the present invention, the metal oxide is preferably at least one selected from the group consisting of ceria, zirconia, yttria, lanthanum oxide, alumina, magnesia, tungsten oxide and titania. The catalytically active component may further contain an alkali metal and / or an alkaline earth metal.
また、本発明は、鉄族金属の化合物を金属酸化物に担持させた後、前記化合物を還元処理して、前記鉄族金属を形成することを特徴とするアンモニア分解触媒の製造方法を提供する。本発明によるアンモニア分解触媒の製造方法において、前記還元処理は、還元性ガスにより３００〜８００℃の温度で行うことが好ましい。 In addition, the present invention provides a method for producing an ammonia decomposition catalyst, which comprises supporting an iron group metal compound on a metal oxide and then reducing the compound to form the iron group metal. . In the method for producing an ammonia decomposition catalyst according to the present invention, the reduction treatment is preferably performed at a temperature of 300 to 800 ° C. with a reducing gas.
さらに、本発明は、上記のようなアンモニア分解触媒を用いて、アンモニアを含有するガスを処理して、前記アンモニアを窒素と水素とに分解して水素を取得することを特徴とするアンモニア処理方法を提供する。 Furthermore, the present invention is an ammonia treatment method characterized in that the ammonia-decomposing catalyst as described above is used to treat a gas containing ammonia to obtain hydrogen by decomposing the ammonia into nitrogen and hydrogen. I will provide a.
本発明によれば、貴金属を用いることなく、低濃度から高濃度までの広範囲なアンモニア濃度域において、アンモニアを比較的低温で、かつ、高い空間速度で窒素と水素とに効率よく分解して高純度の水素を取得できる触媒、この触媒を簡便に製造する方法、ならびに、この触媒を用いて、アンモニアを窒素と水素とに分解して水素を取得する方法が提供される。 According to the present invention, ammonia is efficiently decomposed into nitrogen and hydrogen at a relatively low temperature and at a high space velocity in a wide ammonia concentration range from a low concentration to a high concentration without using noble metals. Provided are a catalyst capable of obtaining pure hydrogen, a method for easily producing the catalyst, and a method for obtaining hydrogen by decomposing ammonia into nitrogen and hydrogen using the catalyst.
≪アンモニア分解触媒≫
本発明のアンモニア分解触媒は、触媒活性成分が鉄族金属および金属酸化物を含有することを特徴とする。
≪Ammonia decomposition catalyst≫
The ammonia decomposition catalyst of the present invention is characterized in that the catalytically active component contains an iron group metal and a metal oxide.
鉄族金属としては、コバルト、ニッケルおよび鉄よりなる群から選択される少なくとも１種が用いられる。これらの鉄族金属のうち、コバルトおよびニッケルが好ましく、コバルトがより好ましい。 As the iron group metal, at least one selected from the group consisting of cobalt, nickel and iron is used. Of these iron group metals, cobalt and nickel are preferable, and cobalt is more preferable.
鉄族金属の出発原料としては、通常、触媒の原料として用いられるものである限り、特に限定されるものではないが、好ましくは、酸化物、水酸化物、硝酸塩、硫酸塩、炭酸塩などの無機化合物；酢酸塩、シュウ酸塩などの有機酸塩；アセチルアセトナト錯体、金属アルコキシドなどの有機金属錯体；などが挙げられる。 The starting material for the iron group metal is not particularly limited as long as it is usually used as a starting material for the catalyst, but preferably, oxides, hydroxides, nitrates, sulfates, carbonates, etc. Inorganic compounds; organic acid salts such as acetates and oxalates; organometallic complexes such as acetylacetonato complexes and metal alkoxides;
具体的には、コバルト源としては、例えば、酸化コバルト、水酸化コバルト、硝酸コバルト、硫酸コバルト、硫酸アンモニウムコバルト、炭酸コバルト、酢酸コバルト、シュウ酸コバルト、クエン酸コバルト、安息香酸コバルト、２−エチルヘキシル酸コバルト、酸化リチウムコバルトなどが挙げられ、硝酸コバルトが好ましい。ニッケル源としては、例えば、酸化ニッケル、水酸化ニッケル、硝酸ニッケル、硫酸ニッケル、炭酸ニッケル、酢酸ニッケル、シュウ酸ニッケル、クエン酸ニッケル、安息香酸ニッケル、２−エチルヘキシル酸ニッケル、ビス（アセチルアセトナト）ニッケルなどが挙げられ、硝酸ニッケルが好ましい。鉄源としては、例えば、酸化鉄、水酸化鉄、硝酸鉄、硫酸鉄、炭酸鉄、酢酸鉄、シュウ酸鉄、クエン酸鉄、鉄メトキシドなどが挙げられ、硝酸鉄が好ましい。 Specifically, examples of the cobalt source include cobalt oxide, cobalt hydroxide, cobalt nitrate, cobalt sulfate, ammonium cobalt sulfate, cobalt carbonate, cobalt acetate, cobalt oxalate, cobalt citrate, cobalt benzoate, and 2-ethylhexyl acid. Examples include cobalt and lithium cobalt oxide, and cobalt nitrate is preferable. Examples of the nickel source include nickel oxide, nickel hydroxide, nickel nitrate, nickel sulfate, nickel carbonate, nickel acetate, nickel oxalate, nickel citrate, nickel benzoate, nickel 2-ethylhexylate, and bis (acetylacetonate). Nickel etc. are mentioned, Nickel nitrate is preferable. Examples of the iron source include iron oxide, iron hydroxide, iron nitrate, iron sulfate, iron carbonate, iron acetate, iron oxalate, iron citrate, and iron methoxide, and iron nitrate is preferable.
鉄族金属は、触媒活性成分の必須成分であり、鉄族金属の含有量は、触媒活性成分１００質量％に対して、好ましくは５〜９０質量％、より好ましくは１０〜８０質量％である。 The iron group metal is an essential component of the catalytically active component, and the content of the iron group metal is preferably 5 to 90% by mass, more preferably 10 to 80% by mass with respect to 100% by mass of the catalytically active component. .
なお、鉄族金属には、その他の遷移金属（貴金属を除く）および／または典型金属を添加してもよい。その他の遷移金属としては、例えば、モリブデン、タングステン、バナジウム、クロム、マンガンなどが挙げられる。その他の典型金属としては、例えば、亜鉛、ガリウム、インジウム、スズなどが挙げられる。 Note that other transition metals (excluding noble metals) and / or typical metals may be added to the iron group metal. Examples of other transition metals include molybdenum, tungsten, vanadium, chromium, manganese, and the like. Examples of other typical metals include zinc, gallium, indium, and tin.
その他の遷移金属および典型金属の出発原料としては、通常、触媒の原料として用いられるものである限り、特に限定されるものではないが、例えば、酸化物、水酸化物、硝酸塩、硫酸塩、炭酸塩、酢酸塩、シュウ酸塩、有機金属錯体などが挙げられる。 The starting materials for other transition metals and typical metals are not particularly limited as long as they are usually used as starting materials for catalysts. For example, oxides, hydroxides, nitrates, sulfates, carbonates Examples thereof include salts, acetates, oxalates, and organometallic complexes.
金属酸化物としては、特に限定されるものではないが、セリア、ジルコニア、イットリア、酸化ランタン、アルミナ、マグネシア、酸化タングステンおよびチタニアよりなる群から選択される少なくとも１種であることが好ましく、セリア、ジルコニア、イットリアおよび酸化ランタンよりなる群から選択される少なくとも１種がより好ましい。これらの金属酸化物のうち、２種類以上の金属酸化物としては、例えば、金属酸化物の混合物、複合酸化物、または、金属酸化物の固溶体を用いることができる。これらの金属酸化物のうち、セリア、ジルコニア、セリアとジルコニアとの固溶体（ＣｅＺｒＯｘ）、セリアとイットリアとの固溶体（ＣｅＹＯｘ）、セリアと酸化ランタンとの固溶体（ＣｅＬａＯｘ）が好ましく、セリアとジルコニアとの固溶体（ＣｅＺｒＯｘ）がより好ましい。 The metal oxide is not particularly limited, but is preferably at least one selected from the group consisting of ceria, zirconia, yttria, lanthanum oxide, alumina, magnesia, tungsten oxide and titania, More preferred is at least one selected from the group consisting of zirconia, yttria and lanthanum oxide. Among these metal oxides, as the two or more kinds of metal oxides, for example, a mixture of metal oxides, a composite oxide, or a solid solution of metal oxides can be used. Among these metal oxides, ceria, zirconia, solid solution of ceria and zirconia (CeZrO x ), solid solution of ceria and yttria (CeYO x ), solid solution of ceria and lanthanum oxide (CeOO x ) are preferable, and ceria and A solid solution with zirconia (CeZrO x ) is more preferable.
金属酸化物は、触媒活性成分の必須成分であり、金属酸化物の含有量は、触媒活性成分１００質量％に対して、好ましくは１０〜９５質量％、より好ましくは２０〜９０質量％である。 The metal oxide is an essential component of the catalytically active component, and the content of the metal oxide is preferably 10 to 95% by mass, more preferably 20 to 90% by mass with respect to 100% by mass of the catalytically active component. .
触媒活性成分は、鉄族金属および金属酸化物に加えて、さらに、アルカリ金属および／またはアルカリ土類金属（以下「添加成分」ということがある）を含有していてもよい。 In addition to the iron group metal and metal oxide, the catalytically active component may further contain an alkali metal and / or an alkaline earth metal (hereinafter sometimes referred to as “additive component”).
アルカリ金属としては、例えば、リチウム、ナトリウム、カリウム、セシウムなどが挙げられる。これらのアルカリ金属のうち、カリウム、セシウムが好ましい。 Examples of the alkali metal include lithium, sodium, potassium, cesium and the like. Of these alkali metals, potassium and cesium are preferable.
アルカリ土類金属としては、例えば、マグネシウム、カルシウム、ストロンチウム、バリウムなどが挙げられる。これらのアルカリ土類金属のうち、ストロンチウム、バリウムが好ましい。 Examples of the alkaline earth metal include magnesium, calcium, strontium, barium and the like. Of these alkaline earth metals, strontium and barium are preferred.
添加成分の出発原料としては、通常、触媒の原料として用いられるものである限り、特に限定されるものではないが、好ましくは、水酸化物、硝酸塩、炭酸塩、酢酸塩、シュウ酸塩などが挙げられる。これらの化合物を溶解させた水溶液を調製し、この水溶液を触媒に含浸し、添加成分の出発原料を触媒に添加した後に、この添加成分の出発原料である化合物の分解処理を行うことが好ましい。分解処理としては、例えば、窒素気流下で昇温して分解する方法、水素気流下で昇温して分解する方法などが挙げられる。これらの分解処理のうち、水素気流下で昇温して分解する方法が好ましい。 The starting material for the additive component is not particularly limited as long as it is usually used as a starting material for the catalyst. Preferably, hydroxides, nitrates, carbonates, acetates, oxalates, and the like are used. Can be mentioned. It is preferable to prepare an aqueous solution in which these compounds are dissolved, impregnate the aqueous solution into the catalyst, add the starting material of the additive component to the catalyst, and then perform the decomposition treatment of the compound that is the starting material of the additive component. Examples of the decomposition treatment include a method of decomposing by raising the temperature under a nitrogen stream, and a method of decomposing by raising the temperature under a hydrogen stream. Of these decomposition treatments, a method of decomposing by raising the temperature under a hydrogen stream is preferred.
添加成分の含有量は、触媒活性成分１００質量％に対して、好ましくは０〜２５質量％、より好ましくは０．２〜１５質量％、さらに好ましくは０．４〜１０質量％未満である。 The content of the additive component is preferably 0 to 25% by mass, more preferably 0.2 to 15% by mass, and still more preferably less than 0.4 to 10% by mass with respect to 100% by mass of the catalytically active component.
触媒の耐熱性の観点から、触媒粒子の凝集を抑制することや触媒の表面積を高めることが有効であることは一般的に知られている。そこで、例えば、触媒粒子の凝集を抑制するために、金属酸化物に添加剤を加えることが考えられる。この場合には、金属酸化物および添加剤から互いに固溶しない組合せを選択することが有効である。例えば、金属酸化物として、セリアとジルコニアとの固溶体（ＣｅＺｒＯｘ）を用いる場合には、この固溶体に固溶しない添加剤として、マグネシウム、カルシウムなどのアルカリ土類金属、シリカやアルミナなどの金属酸化物の微粒子、カーボンブラックなどを添加することにより、触媒の使用時に触媒粒子の凝集が抑制されて触媒の耐熱性が向上する。 From the viewpoint of heat resistance of a catalyst, it is generally known that it is effective to suppress aggregation of catalyst particles and to increase the surface area of the catalyst. Therefore, for example, an additive may be added to the metal oxide in order to suppress aggregation of the catalyst particles. In this case, it is effective to select a combination that does not form a solid solution with each other from the metal oxide and the additive. For example, when a solid solution of ceria and zirconia (CeZrO x ) is used as the metal oxide, as an additive that does not dissolve in the solid solution, an alkaline earth metal such as magnesium or calcium, or a metal oxide such as silica or alumina. By adding fine particles of the product, carbon black, etc., aggregation of the catalyst particles is suppressed when the catalyst is used, and the heat resistance of the catalyst is improved.
＜物性＞
本発明の触媒は、比表面積が好ましくは１〜３００ｍ２／ｇ、より好ましくは５〜２６０ｍ２／ｇ、さらに好ましくは１８〜２００ｍ２／ｇである。なお、「比表面積」とは、例えば、全自動ＢＥＴ表面積測定装置（製品名「Ｍａｒｃｓｏｒｂ ＨＭ Ｍｏｄｅｌ−１２０１」、株式会社マウンテック製）を用いて測定したＢＥＴ比表面積を意味する。
<Physical properties>
The specific surface area of the catalyst of the present invention is preferably 1 to 300 m 2 / g, more preferably 5 to 260 m 2 / g, still more preferably 18 to 200 m 2 / g. The “specific surface area” means, for example, the BET specific surface area measured using a fully automatic BET surface area measuring device (product name “Marcsorb HM Model-1201”, manufactured by Mountec Co., Ltd.).
本発明の触媒は、鉄族金属の結晶子サイズが好ましくは３〜２００ｎｍ、より好ましくは５〜１５０ｎｍ、さらに好ましくは１０〜１００ｎｍであり、金属酸化物の結晶子サイズが好ましくは２〜２００ｎｍ、より好ましくは３〜１００ｎｍ、さらに好ましくは４〜２５ｎｍである。結晶子サイズの測定は、Ｘ線回折測定の結果について、結晶構造の帰属を行い、最大強度を示すピークの半値幅から下記のシェラー式を用いて算出した。 In the catalyst of the present invention, the crystallite size of the iron group metal is preferably 3 to 200 nm, more preferably 5 to 150 nm, still more preferably 10 to 100 nm, and the crystallite size of the metal oxide is preferably 2 to 200 nm. More preferably, it is 3-100 nm, More preferably, it is 4-25 nm. The crystallite size was measured by assigning the crystal structure to the result of the X-ray diffraction measurement, and calculated from the half width of the peak indicating the maximum intensity using the following Scherrer equation.
ここで、Ｋは形状ファクター（球状として０．９を代入）、λは測定Ｘ線波長（ＣｕＫα：０．１５４ｎｍ）、βは半値幅（ｒａｄ）、θはブラッグ角（回折角２θの半分；ｄｅｇ）である。 Here, K is a shape factor (0.9 is substituted as a sphere), λ is a measured X-ray wavelength (CuKα: 0.154 nm), β is a half width (rad), θ is a Bragg angle (half of the diffraction angle 2θ; deg).
＜触媒の形状＞
本発明の触媒は、触媒活性成分をそのまま触媒とするか、あるいは、従来公知の方法を用いて、触媒活性成分を担体に担持してもよい。担体としては、特に限定されるものではないが、例えば、アルミナ、シリカ、チタニア、ジルコニア、セリアなどの金属酸化物が挙げられる。
<Catalyst shape>
In the catalyst of the present invention, the catalytically active component may be used as it is, or the catalytically active component may be supported on a carrier by a conventionally known method. The support is not particularly limited, and examples thereof include metal oxides such as alumina, silica, titania, zirconia, and ceria.
本発明の触媒は、従来公知の方法を用いて、所望の形状に成形して用いてもよい。触媒の形状は、特に限定されるものではなく、例えば、粒状、球状、ペレット状、破砕状、サドル状、リング状、ハニカム状、モノリス状、網状、円柱状、円筒状などが挙げられる。 The catalyst of the present invention may be molded into a desired shape using a conventionally known method. The shape of the catalyst is not particularly limited, and examples thereof include granular, spherical, pellet-shaped, crushed, saddle-shaped, ring-shaped, honeycomb-shaped, monolith-shaped, net-shaped, columnar, cylindrical, and the like.
また、本発明の触媒は、構造体の表面に層状にコートして用いてもよい。構造体としては、特に限定されるものではないが、例えば、コージェライト、ムライト、炭化珪素、アルミナ、シリカ、チタニア、ジルコニア、セリアなどのセラミックスからなる構造体；フェライト系ステンレスなどの金属からなる構造体；などが挙げられる。構造体の形状としては、特に限定されるものではないが、例えば、ハニカム状、コルゲート状、網状、円柱状、円筒状などが挙げられる。 Further, the catalyst of the present invention may be used by coating the surface of the structure in layers. The structure is not particularly limited. For example, a structure made of a ceramic such as cordierite, mullite, silicon carbide, alumina, silica, titania, zirconia, and ceria; a structure made of a metal such as ferritic stainless steel Body; and the like. The shape of the structure is not particularly limited, and examples thereof include a honeycomb shape, a corrugated shape, a net shape, a columnar shape, and a cylindrical shape.
≪アンモニア分解触媒の製造方法≫
以下に、本発明のアンモニア分解触媒を製造する方法の好適な具体例を示すが、本発明の課題が達成される限り、下記の製造方法に限定されるものではない。
≪Method for producing ammonia decomposition catalyst≫
Hereinafter, preferred specific examples of the method for producing the ammonia decomposition catalyst of the present invention will be shown, but the present invention is not limited to the following production method as long as the object of the present invention is achieved.
（１）鉄族金属の化合物の水溶液を金属酸化物に含浸し、乾燥させ、不活性ガスにより仮焼成した後、還元性ガスにより還元処理する方法;
（２）鉄族金属の化合物の水溶液を金属酸化物に含浸し、乾燥させ、水溶性の還元剤を用いて還元処理した後、濾過し、乾燥させる方法；
（３）添加成分を含有する水溶液を金属酸化物に添加し、乾燥させ、次いで、鉄族金属の化合物の水溶液を含浸し、乾燥させ、不活性ガスにより仮焼成した後、還元性ガスにより還元処理する方法；
（４）鉄族金属の化合物の水溶液を金属酸化物に含浸し、乾燥させ、さらに、鉄族金属の化合物の水溶液を金属酸化物に含浸し、乾燥させ、次いで、不活性ガスにより仮焼成した後、還元性ガスにより還元処理する方法；
（５）鉄族金属の化合物の水溶液を金属酸化物に含浸し、乾燥させ、不活性ガスにより仮焼成した後、還元性ガスにより還元処理し、添加成分を含有する水溶液を添加し、乾燥させ、再度、還元性ガスにより還元処理する方法；
（６）鉄族金属の化合物と、金属酸化物の前駆体となる水溶性金属塩とを含有する水溶液を、過剰量のアルカリ性水溶液（例えば、アンモニア水、水酸化テトラメチルアンモニウム水溶液、水酸化カリウム水溶液など）に、撹拌しながら、滴下し、得られた固体生成物を濾過し、水洗して乾燥し、次いで、還元処理する方法；
（７）鉄族金属の化合物と、金属酸化物の前駆体となる水溶性金属塩とを含有する水溶液に、過剰量のアルカリ性水溶液（例えば、アンモニア水、水酸化テトラメチルアンモニウム水溶液、水酸化カリウム水溶液など）を、攪拌しながら、滴下し、得られた固体生成物を濾過し、水洗して乾燥させ、次いで、還元処理する方法。
(1) A method in which an aqueous solution of an iron group metal compound is impregnated in a metal oxide, dried, calcined with an inert gas, and then reduced with a reducing gas;
(2) A method in which an aqueous solution of an iron group metal compound is impregnated in a metal oxide, dried, subjected to a reduction treatment using a water-soluble reducing agent, filtered, and dried;
(3) An aqueous solution containing additive components is added to the metal oxide and dried, then impregnated with an aqueous solution of an iron group metal compound, dried, calcined with an inert gas, and then reduced with a reducing gas. How to handle;
(4) An aqueous solution of an iron group metal compound is impregnated in a metal oxide and dried. Further, an aqueous solution of an iron group metal compound is impregnated in a metal oxide, dried, and then calcined with an inert gas. Thereafter, a reduction treatment with a reducing gas;
(5) An aqueous solution of an iron group metal compound is impregnated into a metal oxide, dried, calcined with an inert gas, then reduced with a reducing gas, an aqueous solution containing an additive component is added, and dried. , Again a method of reducing with a reducing gas;
(6) An aqueous solution containing an iron group metal compound and a water-soluble metal salt that is a precursor of the metal oxide is treated with an excess amount of an alkaline aqueous solution (for example, ammonia water, tetramethylammonium hydroxide aqueous solution, potassium hydroxide). An aqueous solution, etc.) with stirring, the solid product obtained is filtered, washed with water, dried and then subjected to a reduction treatment;
(7) An excess amount of an alkaline aqueous solution (for example, aqueous ammonia, tetramethylammonium hydroxide, potassium hydroxide) is added to an aqueous solution containing an iron group metal compound and a water-soluble metal salt that is a precursor of the metal oxide. An aqueous solution or the like) is added dropwise with stirring, and the resulting solid product is filtered, washed with water, dried, and then subjected to a reduction treatment.
本発明によるアンモニア分解触媒の製造方法は、鉄族金属の化合物を還元処理して、前記鉄族金属を形成することを特徴とする。 The method for producing an ammonia decomposition catalyst according to the present invention is characterized in that an iron group metal compound is reduced to form the iron group metal.
還元処理は、鉄族金属の化合物を還元して鉄族金属を形成することができる限り、特に限定されるものではない。具体的には、例えば、一酸化炭素、炭化水素、水素などの還元性ガスを用いる方法；ヒドラジン、リチウムアルミニウムハイドライド、テトラメチルボロハイドライドなどの還元剤を添加する方法；などが挙げられる。なお、還元性ガスを用いる場合は、その他のガス（例えば、窒素、二酸化炭素）により還元性ガスを希釈して用いることもできる。これらの方法のうち、還元性ガスとして水素を用いた還元処理が好ましい。 The reduction treatment is not particularly limited as long as the iron group metal compound can be formed by reducing the iron group metal compound. Specifically, for example, a method using a reducing gas such as carbon monoxide, hydrocarbon or hydrogen; a method of adding a reducing agent such as hydrazine, lithium aluminum hydride or tetramethylborohydride; In addition, when using reducing gas, reducing gas can also be diluted and used with other gas (for example, nitrogen, carbon dioxide). Of these methods, reduction treatment using hydrogen as the reducing gas is preferable.
還元性ガスを用いる場合、好ましくは３００〜８００℃、より好ましくは４００〜６００℃の温度で加熱を行う。還元時間は、好ましくは０．５〜５時間、より好ましくは１〜３時間である。また、還元性ガスによる還元処理に先立ち、窒素、二酸化炭素などの不活性ガスを用いて、好ましくは２００〜４００℃の温度で、好ましくは１〜７時間、より好ましくは３〜６時間にわたり仮焼成することもできる。 When reducing gas is used, heating is preferably performed at a temperature of 300 to 800 ° C, more preferably 400 to 600 ° C. The reduction time is preferably 0.5 to 5 hours, more preferably 1 to 3 hours. Prior to the reduction treatment with the reducing gas, an inert gas such as nitrogen or carbon dioxide is used, preferably at a temperature of 200 to 400 ° C., preferably 1 to 7 hours, more preferably 3 to 6 hours. It can also be fired.
還元処理を行うと、鉄族金属の化合物は、原理的には、原子価０の金属状態を示す鉄族金属に変換される。還元処理が不充分であると、鉄族金属の化合物が部分的にしか還元されず、触媒が低い活性しか示さない。しかし、このような場合であっても、アンモニア分解反応中に水素が発生することから、還元処理を行っている状態と同じ環境になるため、かかる反応を継続することにより、不充分に還元された部分の還元処理が進行して、原子価０の金属状態になり、触媒が高い活性を示すようになる。 When the reduction treatment is performed, the compound of the iron group metal is converted into an iron group metal showing a metal state of zero valence in principle. If the reduction treatment is insufficient, the iron group metal compound is only partially reduced and the catalyst exhibits low activity. However, even in such a case, since hydrogen is generated during the ammonia decomposition reaction, it becomes the same environment as the state where the reduction treatment is performed. Therefore, by continuing such a reaction, it is insufficiently reduced. The reduction treatment of the remaining portion proceeds to a metal state with a valence of 0, and the catalyst becomes highly active.
≪アンモニア処理方法≫
本発明のアンモニア処理方法は、上記のようなアンモニア分解触媒を用いて、アンモニアを含有するガスを処理して、前記アンモニアを窒素と水素とに分解して水素を取得することを特徴とする。処理対象となる「アンモニアを含有するガス」としては、特に限定されるものではないが、アンモニアガスやアンモニア含有ガスだけでなく、尿素などのように熱分解によりアンモニアを生じる物質を含有するガスであってもよい。また、アンモニアを含有するガスは、触媒毒にならない程度であれば、他の成分を含有していてもよい。
≪Ammonia treatment method≫
The ammonia treatment method of the present invention is characterized in that a gas containing ammonia is treated using the ammonia decomposition catalyst as described above, and the ammonia is decomposed into nitrogen and hydrogen to obtain hydrogen. “Ammonia-containing gas” to be treated is not particularly limited, but is not limited to ammonia gas and ammonia-containing gas, but is a gas containing a substance that generates ammonia by thermal decomposition, such as urea. There may be. Moreover, the gas containing ammonia may contain other components as long as it does not become a catalyst poison.
触媒あたりの「アンモニアを含有するガス」の流量は、空間速度で、好ましくは１，０００〜２００，０００ｈ−１、より好ましくは２，０００〜１５０，０００ｈ−１、さらに好ましくは３，０００〜１００，０００ｈ−１である。ここで、触媒あたりの「アンモニアを含有するガス」の流量とは、触媒を反応器に充填した際に触媒が占める体積あたりの単位時間あたりに触媒を通過する「アンモニアを含有するガス」の体積を意味する。 The flow rate of the “gas containing ammonia” per catalyst is a space velocity, preferably 1,000 to 200,000 h −1 , more preferably 2,000 to 150,000 h −1 , more preferably 3,000 to 3,000. 100,000h- 1 . Here, the flow rate of the “gas containing ammonia” per catalyst means the volume of the “gas containing ammonia” passing through the catalyst per unit time per volume occupied by the catalyst when the catalyst is charged into the reactor. Means.
反応温度は、好ましくは１８０〜９５０℃、より好ましくは３００〜９００℃、さらに好ましくは４００〜８００℃である。反応圧力は、好ましくは０．００２〜２ＭＰａ、より好ましくは０．００４〜１ＭＰａである。 Reaction temperature becomes like this. Preferably it is 180-950 degreeC, More preferably, it is 300-900 degreeC, More preferably, it is 400-800 degreeC. The reaction pressure is preferably 0.002 to 2 MPa, more preferably 0.004 to 1 MPa.
本発明のアンモニア処理方法によれば、アンモニアを分解して得られた窒素および水素を、従来公知の方法を用いて、窒素と水素とに分離することにより、高純度の水素を取得することができる。 According to the ammonia treatment method of the present invention, high-purity hydrogen can be obtained by separating nitrogen and hydrogen obtained by decomposing ammonia into nitrogen and hydrogen using a conventionally known method. it can.
以下、実験例を挙げて本発明をより具体的に説明するが、本発明はもとより下記の実験例により制限を受けるものではなく、前・後記の趣旨に適合し得る範囲で適当に変更を加えて実施することも可能であり、それらはいずれも本発明の技術的範囲に包含される。 Hereinafter, the present invention will be described more specifically with reference to experimental examples.However, the present invention is not limited by the following experimental examples, and appropriate modifications are made within a range that can meet the purpose described above and below. Any of these can be carried out and are included in the technical scope of the present invention.
なお、比表面積の測定には、全自動ＢＥＴ表面積測定装置（製品名「Ｍａｒｃｓｏｒｂ ＨＭ Ｍｏｄｅｌ−１２０１」、株式会社マウンテック製）を用いた。また、Ｘ線回折測定および結晶子サイズの測定には、Ｘ線回折装置（製品名「Ｘ’Ｐｅｒｔ Ｐｒｏ ＭＰＤ」、スペクトリス株式会社製）を用いた。Ｘ線源には、ＣｕＫα（０．１５４ｎｍ）を用い、測定条件として、Ｘ線出力４５ｋＶ、４０ｍＡ、ステップサイズ０．０１７°、スキャンステップ時間１００秒、測定温度２５℃であり、測定範囲は測定すべき鉄族金属および金属酸化物に応じて適宜選択して実施した。さらに、触媒組成の定量は、蛍光Ｘ線分析装置（製品名「ＲＩＸ２０００」、株式会社リガク製）による元素分析測定により行った。測定条件は、Ｘ線出力５０ｋＶ、５０ｍＡであり、計算法はＦＰ法（ファンダメンタル・パラメータ法）を用いた。 For the measurement of the specific surface area, a fully automatic BET surface area measuring device (product name “Marcsorb HM Model-1201”, manufactured by Mountec Co., Ltd.) was used. An X-ray diffractometer (product name “X′Pert Pro MPD”, manufactured by Spectris Co., Ltd.) was used for X-ray diffraction measurement and crystallite size measurement. CuKα (0.154 nm) is used as the X-ray source. The measurement conditions are an X-ray output of 45 kV, 40 mA, a step size of 0.017 °, a scan step time of 100 seconds, a measurement temperature of 25 ° C., and a measurement range is measured. It carried out by selecting suitably according to the iron group metal and metal oxide which should be performed. Further, the catalyst composition was quantified by elemental analysis using a fluorescent X-ray analyzer (product name “RIX2000”, manufactured by Rigaku Corporation). The measurement conditions were an X-ray output of 50 kV and 50 mA, and the calculation method used was the FP method (fundamental parameter method).
≪実験例１≫
１２０℃で一晩乾燥させたγ−アルミナ（Ｓｔｒｅｍ Ｃｈｅｍｉｃａｌｓ Ｉｎｃ．製）９．０１ｇに、硝酸ニッケル六水和物５．５１ｇを蒸留水４．５５ｇに溶解させた水溶液を滴下して混合した。この混合物を密閉して１時間静置した後、湯浴上で乾燥させた。この乾燥した混合物を、窒素気流下、３５０℃で５時間焼成した後、空気気流下、５００℃で３時間焼成した。この焼成物を環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、４５０℃で５時間還元処理して、触媒１を得た。なお、触媒１のニッケル担持量は、１１質量％であった。
≪Experimental example 1≫
An aqueous solution in which 5.51 g of nickel nitrate hexahydrate was dissolved in 4.55 g of distilled water was added dropwise to 9.01 g of γ-alumina (manufactured by Strem Chemicals Inc.) dried overnight at 120 ° C. and mixed. The mixture was sealed and allowed to stand for 1 hour, and then dried on a hot water bath. The dried mixture was baked at 350 ° C. for 5 hours under a nitrogen stream, and then baked at 500 ° C. for 3 hours under an air stream. The fired product was filled in an annular furnace and reduced at 450 ° C. for 5 hours using 10% by volume hydrogen gas (diluted with nitrogen) to obtain catalyst 1. The amount of nickel supported on catalyst 1 was 11% by mass.
≪実験例２≫
硝酸セシウム１．００１ｇを蒸留水５．０４７６ｇに溶解させて水溶液１を得た。２．６７８７ｇの触媒１に、１．４７６８ｇの水溶液１を添加して混合した後、９０℃で一晩乾燥させた。この乾燥した混合物に、再度、１．４８０４ｇの水溶液１を添加して混合した後、９０℃で一晩乾燥させた。この乾燥した混合物を、窒素気流下、３５０℃で５時間焼成した後、空気気流下、５００℃で３時間焼成した。この焼成物を環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、４５０℃で５時間還元処理して、触媒２を得た。
«Experimental example 2»
Aqueous solution 1 was obtained by dissolving 1.001 g of cesium nitrate in 5.0476 g of distilled water. 1.4768 g of aqueous solution 1 was added to 2.6787 g of catalyst 1 and mixed, followed by drying at 90 ° C. overnight. To this dried mixture, 1.4804 g of the aqueous solution 1 was added again and mixed, and then dried at 90 ° C. overnight. The dried mixture was baked at 350 ° C. for 5 hours under a nitrogen stream, and then baked at 500 ° C. for 3 hours under an air stream. The fired product was filled in an annular furnace, and reduced at 450 ° C. for 5 hours using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 2.
≪実験例３≫
硝酸セシウム２．００１１ｇを蒸留水４．９９３６ｇに溶解させて水溶液２を得た。２．８５９５ｇの触媒１に、１．５１３０ｇの水溶液２を添加して混合した後、９０℃で一晩乾燥させた。この乾燥した混合物に、再度、１．４３６７ｇの水溶液２を添加して混合した後、９０℃で一晩乾燥させた。この乾燥した混合物を、窒素気流下、３５０℃で５時間焼成した後、空気気流下、５００℃で３時間焼成した。この焼成物を環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、４５０℃で５時間還元処理して、触媒３を得た。
«Experimental example 3»
Aqueous solution 2 was obtained by dissolving 2.0011 g of cesium nitrate in 4.9936 g of distilled water. After 1.5130 g of aqueous solution 2 was added to 2.8595 g of catalyst 1 and mixed, it was dried at 90 ° C. overnight. To this dried mixture, 1.4367 g of the aqueous solution 2 was again added and mixed, and then dried at 90 ° C. overnight. The dried mixture was baked at 350 ° C. for 5 hours under a nitrogen stream, and then baked at 500 ° C. for 3 hours under an air stream. The calcined product was filled in an annular furnace and subjected to reduction treatment at 450 ° C. for 5 hours using 10 vol% hydrogen gas (diluted with nitrogen) to obtain Catalyst 3.
≪実験例４≫
１２０℃で一晩乾燥させたγ−アルミナ（Ｓｔｒｅｍ Ｃｈｅｍｉｃａｌｓ Ｉｎｃ．製）１０．００ｇに、硝酸ニッケル六水和物２．６１ｇを蒸留水５．１４ｇに溶解させた水溶液を滴下して混合した。この混合物を密閉して１時間静置した後、湯浴上で乾燥させた。この乾燥した混合物を、窒素気流下、３５０℃で５時間焼成した後、空気気流下、５００℃で３時間焼成した。この焼成物を環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、４５０℃で５時間還元処理して、触媒４を得た。なお、触媒４のニッケル担持量は、５質量％であった。
<< Experimental Example 4 >>
An aqueous solution prepared by dissolving 2.61 g of nickel nitrate hexahydrate in 5.14 g of distilled water was added dropwise to 10.00 g of γ-alumina (manufactured by Strem Chemicals Inc.) dried overnight at 120 ° C. and mixed. The mixture was sealed and allowed to stand for 1 hour, and then dried on a hot water bath. The dried mixture was baked at 350 ° C. for 5 hours under a nitrogen stream, and then baked at 500 ° C. for 3 hours under an air stream. This fired product was filled in an annular furnace and reduced at 450 ° C. for 5 hours using 10% by volume hydrogen gas (diluted with nitrogen) to obtain catalyst 4. The amount of nickel supported on catalyst 4 was 5% by mass.
≪実験例５≫
１２０℃で一晩乾燥させたγ−アルミナ（Ｓｔｒｅｍ Ｃｈｅｍｉｃａｌｓ Ｉｎｃ．製）１０．０２ｇに、硝酸ニッケル六水和物１２．３９ｇを蒸留水５．００ｇに溶解させた水溶液を滴下して混合した。この混合物を密閉して１時間静置した後、湯浴上で乾燥させた。この乾燥した混合物を、窒素気流下、３５０℃で５時間焼成した後、空気気流下、５００℃で３時間焼成した。この焼成物を環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、４５０℃で５時間還元処理して、触媒５を得た。なお、触媒５のニッケル担持量は、２０質量％であった。
<< Experimental Example 5 >>
An aqueous solution in which 12.39 g of nickel nitrate hexahydrate was dissolved in 5.00 g of distilled water was added dropwise to 10.02 g of γ-alumina (manufactured by Strem Chemicals Inc.) dried at 120 ° C. overnight. The mixture was sealed and allowed to stand for 1 hour, and then dried on a hot water bath. The dried mixture was baked at 350 ° C. for 5 hours under a nitrogen stream, and then baked at 500 ° C. for 3 hours under an air stream. The fired product was filled in an annular furnace, and reduced at 450 ° C. for 5 hours using 10% by volume hydrogen gas (diluted with nitrogen) to obtain catalyst 5. The amount of nickel supported on the catalyst 5 was 20% by mass.
≪実験例６≫
γ−アルミナ（住友化学株式会社製）を９５０℃で１０時間熱処理した後、粉砕し、１２０℃で一晩乾燥させた。この熱処理により、アルミナの結晶相は、γ相からκ相に転移していた。この熱処理アルミナ３５ｇに、硝酸ニッケル六水和物１７．３４ｇを蒸留水２８．０ｇに溶解させた水溶液を滴下して混合した。この混合物を湯浴上で乾燥後、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、４５０℃で２時間還元処理して、触媒６を得た。なお、触媒６のニッケル担持量は、１０質量％であった。
«Experimental example 6»
γ-alumina (manufactured by Sumitomo Chemical Co., Ltd.) was heat treated at 950 ° C. for 10 hours, pulverized, and dried at 120 ° C. overnight. By this heat treatment, the crystal phase of alumina was changed from the γ phase to the κ phase. An aqueous solution in which 17.34 g of nickel nitrate hexahydrate was dissolved in 28.0 g of distilled water was added dropwise to 35 g of this heat treated alumina and mixed. This mixture was dried on a hot water bath, filled in an annular furnace, and reduced at 450 ° C. for 2 hours using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 6. The amount of nickel supported on the catalyst 6 was 10% by mass.
≪実験例７≫
実験例６において、硝酸ニッケル六水和物１７．３４ｇを硝酸コバルト六水和物１７．２８ｇに変更したこと以外は、実験例６と同様にして、触媒７を得た。
<< Experimental Example 7 >>
A catalyst 7 was obtained in the same manner as in Experimental Example 6, except that 17.34 g of nickel nitrate hexahydrate was changed to 17.28 g of cobalt nitrate hexahydrate in Experimental Example 6.
≪実験例８≫
γ−アルミナ（住友化学株式会社製）を９５０℃で１０時間熱処理した後、粉砕し、１２０℃で一晩乾燥させた。この熱処理により、アルミナの結晶相は、γ相からκ相に転移していた。この熱処理アルミナ３０ｇに、硝酸マグネシウム１０．０５ｇを蒸留水２４．０ｇに溶解させた水溶液を滴下して混合した。この混合物を湯浴上で乾燥させた後、空気気流下、５００℃で２時間焼成して、酸化マグネシウムが添加された熱処理アルミナを得た。この酸化マグネシウム添加熱処理アルミナ２０ｇに、硝酸ニッケル六水和物６．７ｇを蒸留水１６．０ｇに溶解させた水溶液を含浸して、酸化マグネシウム添加熱処理アルミナに硝酸ニッケル六水和物を均一に担持させた。この混合物を湯浴上で乾燥後、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、４５０℃で２時間還元処理して、触媒８を得た。
<< Experimental Example 8 >>
γ-alumina (manufactured by Sumitomo Chemical Co., Ltd.) was heat treated at 950 ° C. for 10 hours, pulverized, and dried at 120 ° C. overnight. By this heat treatment, the crystal phase of alumina was changed from the γ phase to the κ phase. An aqueous solution prepared by dissolving 10.05 g of magnesium nitrate in 24.0 g of distilled water was added dropwise to 30 g of this heat treated alumina and mixed. The mixture was dried on a hot water bath and then calcined at 500 ° C. for 2 hours in an air stream to obtain heat treated alumina to which magnesium oxide was added. 20 g of magnesium oxide-added heat-treated alumina is impregnated with an aqueous solution obtained by dissolving 6.7 g of nickel nitrate hexahydrate in 16.0 g of distilled water, and the nickel nitrate hexahydrate is uniformly supported on the magnesium oxide-added heat-treated alumina. I let you. This mixture was dried on a hot water bath, filled into an annular furnace, and reduced at 450 ° C. for 2 hours using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 8.
≪実験例９≫
実験例８において、硝酸マグネシウム１０．０５ｇをメタタングステン酸アンモニウム水溶液（略称「ＭＷ−２」、日本無機化学工業株式会社製；酸化タングステンとして、５０質量％含有）２．１０４ｇに変更したこと以外は、実験例８と同様にして、触媒９を得た。
≪Experimental example 9≫
In Experimental Example 8, except that 10.05 g of magnesium nitrate was changed to 2.104 g of an ammonium metatungstate aqueous solution (abbreviation “MW-2”, manufactured by Nippon Inorganic Chemical Industry Co., Ltd .; containing 50% by mass as tungsten oxide). In the same manner as in Experimental Example 8, a catalyst 9 was obtained.
≪実験例１０≫
実験例６において、硝酸ニッケル六水和物１７．３４ｇを硫酸ニッケル六水和物６．６１ｇに変更し、環状炉での１０体積％水素ガスを用いた還元処理を行わなかったこと以外は、実験例６と同様にして、触媒１０を得た。
«Experimental example 10»
In Experimental Example 6, except that 17.34 g of nickel nitrate hexahydrate was changed to 6.61 g of nickel sulfate hexahydrate, and reduction treatment using 10 vol% hydrogen gas in the annular furnace was not performed,
≪実験例１１≫
硝酸ニッケル六水和物３４．８９ｇ、硝酸セリウム六水和物５．２１ｇおよびオキシ硝酸ジルコニウム水溶液（商品名「ジルコゾールＺＮ」、第一稀元素化学工業株式会社製；酸化ジルコニウムとして２５質量％含有）５．９１ｇを蒸留水５００ｍＬに添加して混合し、均一な水溶液を調製した。この水溶液を、攪拌している蒸留水５００ｍＬに水酸化カリウム８８．６ｇを溶解させた水溶液に滴下して、沈殿物を生成させた。この沈殿物を濾過し、水洗した後、１２０℃で一晩乾燥させた。この乾燥した沈殿物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒１１を得た。得られた触媒１１のＸ線回折パターンを図１に示す。
«Experimental example 11»
Nickel nitrate hexahydrate 34.89 g, cerium nitrate hexahydrate 5.21 g, and zirconium oxynitrate aqueous solution (trade name “Zircosol ZN”, manufactured by Daiichi Rare Element Chemical Industries, Ltd .; containing 25% by mass as zirconium oxide) 5.91 g was added to 500 mL of distilled water and mixed to prepare a uniform aqueous solution. This aqueous solution was dropped into an aqueous solution in which 88.6 g of potassium hydroxide was dissolved in 500 mL of distilled water being stirred, thereby generating a precipitate. The precipitate was filtered, washed with water, and dried overnight at 120 ° C. The dried precipitate was pulverized, filled in an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 11. The X-ray diffraction pattern of the obtained catalyst 11 is shown in FIG.
≪実験例１２≫
実験例１１において、硝酸ニッケル六水和物３４．８９ｇを硝酸コバルト六水和物３４．９２ｇに変更したこと以外は、実験例１１と同様にして、触媒１２を得た。得られた触媒１２のＸ線回折パターンを図２に示す。
«Experimental example 12»
In Example 11, the catalyst 12 was obtained in the same manner as in Example 11 except that 34.89 g of nickel nitrate hexahydrate was changed to 34.92 g of cobalt nitrate hexahydrate. The X-ray diffraction pattern of the obtained catalyst 12 is shown in FIG.
≪実験例１３≫
硝酸鉄九水和物４８．４８ｇ、硝酸セリウム六水和物５．２１ｇおよびオキシ硝酸ジルコニウム水溶液（商品名「ジルコゾールＺＮ」、第一稀元素化学工業株式会社製；酸化ジルコニウムとして、２５質量％含有）５．９１ｇを蒸留水５００ｍＬに添加して混合し、均一な水溶液を調製した。この水溶液に２５質量％アンモニア水８８．９ｇを滴下して、沈殿物を生成させた。この沈殿物を濾過し、水洗した後、１２０℃で一晩乾燥させた。この乾燥した沈殿物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒１３を得た。
<< Experimental Example 13 >>
48.48 g of iron nitrate nonahydrate, 5.21 g of cerium nitrate hexahydrate, and an aqueous solution of zirconium oxynitrate (trade name “Zircosol ZN”, manufactured by Daiichi Rare Elemental Chemical Co., Ltd .; 25% by mass as zirconium oxide) ) 5.91 g was added to 500 mL of distilled water and mixed to prepare a uniform aqueous solution. To this aqueous solution, 88.9 g of 25% by mass aqueous ammonia was added dropwise to produce a precipitate. The precipitate was filtered, washed with water, and dried overnight at 120 ° C. The dried precipitate was pulverized, filled in an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 13.
≪実験例１４≫
硝酸鉄九水和物４８．４８ｇ、硝酸セリウム六水和物５．２１ｇおよびオキシ硝酸ジルコニウム水溶液（商品名「ジルコゾールＺＮ」、第一稀元素化学工業株式会社製；酸化ジルコニウムとして、２５質量％含有）５．９１ｇを蒸留水５００ｍＬに添加して混合し、均一な水溶液を調製した。この水溶液を２５質量％アンモニア水６００ｇに、撹拌下、滴下して、沈殿物を生成させた。この沈殿物を濾過し、水洗した後、１２０℃で一晩乾燥させた。この乾燥した沈殿物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒１４を得た。
«Experimental example 14»
48.48 g of iron nitrate nonahydrate, 5.21 g of cerium nitrate hexahydrate, and an aqueous solution of zirconium oxynitrate (trade name “Zircosol ZN”, manufactured by Daiichi Rare Elemental Chemical Co., Ltd .; 25% by mass as zirconium oxide) ) 5.91 g was added to 500 mL of distilled water and mixed to prepare a uniform aqueous solution. This aqueous solution was dropped into 600 g of 25% by mass aqueous ammonia under stirring to produce a precipitate. The precipitate was filtered, washed with water, and dried overnight at 120 ° C. The dried precipitate was pulverized, filled in an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 14.
≪実験例１５≫
硝酸鉄九水和物２０．２０ｇ、硝酸ニッケル六水和物１４．５４ｇ、硝酸セリウム六水和物４．３４ｇおよびオキシ硝酸ジルコニウム水溶液（商品名「ジルコゾールＺＮ」、第一稀元素化学工業株式会社製；酸化ジルコニウムとして２５質量％含有）４．９３ｇを蒸留水５００ｍＬに添加して混合し、均一な水溶液を調製した。この水溶液を、攪拌している蒸留水５００ｍＬに水酸化カリウム８７．９ｇを溶解させた水溶液に滴下して、沈殿物を生成させた。この沈殿物を濾過し、水洗した後、１２０℃で一晩乾燥させた。この乾燥した沈殿物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒１５を得た。
<< Experimental Example 15 >>
Iron nitrate nonahydrate 20.20 g, nickel nitrate hexahydrate 14.54 g, cerium nitrate hexahydrate 4.34 g, and zirconium oxynitrate aqueous solution (trade name “Zircosol ZN”, Daiichi Rare Element Chemical Co., Ltd. (Made; containing 25% by mass as zirconium oxide) was added to 500 mL of distilled water and mixed to prepare a uniform aqueous solution. This aqueous solution was dropped into an aqueous solution in which 87.9 g of potassium hydroxide was dissolved in 500 mL of distilled water being stirred to produce a precipitate. The precipitate was filtered, washed with water, and dried overnight at 120 ° C. The dried precipitate was pulverized, filled into an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 15.
≪実験例１６≫
硝酸コバルト六水和物３２．１７ｇ、硝酸亜鉛六水和物０．３３ｇ、硝酸セリウム六水和物４．８７ｇおよびオキシ硝酸ジルコニウム水溶液（商品名「ジルコゾールＺＮ」、第一稀元素化学工業株式会社製；酸化ジルコニウムとして、２５質量％含有）５．４２ｇを蒸留水６４０ｍＬに添加して混合し、均一な水溶液を調製した。この水溶液を、攪拌している蒸留水６４０ｍＬに水酸化カリウム１１２．７ｇを溶解させた水溶液に滴下して、沈殿物を生成させた。この沈殿物を濾過し、水洗した後、１２０℃で一晩乾燥させた。この乾燥した沈殿物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒１６を得た。
<< Experimental Example 16 >>
Cobalt nitrate hexahydrate 32.17 g, zinc nitrate hexahydrate 0.33 g, cerium nitrate hexahydrate 4.87 g and zirconium oxynitrate aqueous solution (trade name “Zircosol ZN”, Daiichi Rare Element Chemical Co., Ltd. (Made by: 25% by mass as zirconium oxide) 5.42 g was added to 640 mL of distilled water and mixed to prepare a uniform aqueous solution. This aqueous solution was dropped into an aqueous solution in which 112.7 g of potassium hydroxide was dissolved in 640 mL of stirring distilled water to produce a precipitate. The precipitate was filtered, washed with water, and dried overnight at 120 ° C. The dried precipitate was pulverized, filled in an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 16.
≪実験例１７≫
硝酸コバルト六水和物３４．９２ｇ、硝酸セリウム六水和物５．２１ｇおよび硝酸イットリウム六水和物４．６０ｇを、蒸留水５００ｍＬに添加して混合し、均一な水溶液を調製した。この水溶液を、攪拌している蒸留水５００ｍＬに水酸化カリウム８７．５ｇを溶解させた水溶液に滴下して、沈殿物を生成させた。この沈殿物を濾過し、水洗した後、１２０℃で一晩乾燥させた。この乾燥した沈殿物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒１７を得た。
<< Experimental Example 17 >>
Cobalt nitrate hexahydrate 34.92 g, cerium nitrate hexahydrate 5.21 g and yttrium nitrate hexahydrate 4.60 g were added to 500 mL of distilled water and mixed to prepare a uniform aqueous solution. This aqueous solution was dropped into an aqueous solution in which 87.5 g of potassium hydroxide was dissolved in 500 mL of distilled water being stirred, thereby generating a precipitate. The precipitate was filtered, washed with water, and dried overnight at 120 ° C. The dried precipitate was pulverized, filled into an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 17.
≪実験例１８≫
実験例１７において、硝酸イットリウム六水和物４．６０ｇを硝酸ランタン六水和物５．２０ｇに変更したこと以外は、実験例１７と同様にして、触媒１８を得た。
<< Experimental Example 18 >>
A catalyst 18 was obtained in the same manner as in Experimental Example 17, except that 4.60 g of yttrium nitrate hexahydrate was changed to 5.20 g of lanthanum nitrate hexahydrate in Experimental Example 17.
≪実験例１９≫
硝酸コバルト六水和物３４．９２ｇ、硝酸セリウム六水和物１７．４ｇおよびオキシ硝酸ジルコニウム水溶液（商品名「ジルコゾールＺＮ」、第一稀元素化学工業株式会社製：酸化ジルコニウムとして、２５質量％含有）１９．８ｇを蒸留水５００ｍＬに添加して混合し、均一な水溶液を調製した。この水溶液を、攪拌している蒸留水５００ｍＬに水酸化カリウム１３８ｇを溶解させた水溶液に滴下して、沈殿物を生成させた。この沈殿物を濾過し、水洗した後、１２０℃で一晩乾燥させた。この乾燥した沈殿物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒１９を得た。
<< Experimental Example 19 >>
Cobalt nitrate hexahydrate 34.92 g, cerium nitrate hexahydrate 17.4 g and zirconium oxynitrate aqueous solution (trade name “Zircosol ZN”, manufactured by Daiichi Rare Element Chemical Industries, Ltd .: 25% by mass as zirconium oxide ) 19.8 g was added to 500 mL of distilled water and mixed to prepare a uniform aqueous solution. This aqueous solution was added dropwise to an aqueous solution in which 138 g of potassium hydroxide was dissolved in 500 mL of stirring distilled water to produce a precipitate. The precipitate was filtered, washed with water, and dried overnight at 120 ° C. The dried precipitate was pulverized, filled in an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 19.
≪実験例２０≫
硝酸コバルト六水和物３４．９２ｇ、硝酸セリウム六水和物２．６０ｇおよびオキシ硝酸ジルコニウム水溶液（商品名「ジルコゾールＺＮ」、第一稀元素化学工業株式会社製：酸化ジルコニウムとして、２５質量％含有）２．９５ｇを蒸留水５００ｍＬに添加して混合し、均一な水溶液を調製した。この水溶液を、攪拌している蒸留水５００ｍＬに水酸化カリウム７７．９ｇを溶解させた水溶液に滴下して、沈殿物を生成させた。この沈殿物を濾過し、水洗した後、１２０℃で一晩乾燥させた。この乾燥した沈殿物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒２０を得た。
«Experimental example 20»
Cobalt nitrate hexahydrate 34.92 g, cerium nitrate hexahydrate 2.60 g and zirconium oxynitrate aqueous solution (trade name “Zircosol ZN”, manufactured by Daiichi Rare Element Chemical Industries, Ltd .: 25% by mass as zirconium oxide ) 2.95 g was added to 500 mL of distilled water and mixed to prepare a uniform aqueous solution. This aqueous solution was dropped into an aqueous solution in which 77.9 g of potassium hydroxide was dissolved in 500 mL of distilled water being stirred to produce a precipitate. The precipitate was filtered, washed with water, and dried overnight at 120 ° C. The dried precipitate was pulverized, filled into an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain
≪実験例２１≫
硝酸コバルト六水和物２９．１ｇおよびオキシ硝酸ジルコニウム水溶液（商品名「ジルコゾールＺＮ」、第一稀元素化学工業株式会社製：酸化ジルコニウムとして、２５質量％含有）９．８６ｇを蒸留水５００ｍＬに添加して混合し、均一な水溶液を調製した。この水溶液を、攪拌している蒸留水５００ｍＬに水酸化カリウム７５．０ｇを溶解させた水溶液に滴下して、沈殿物を生成させた。この沈殿物を濾過し、水洗した後、１２０℃で一晩乾燥させた。この乾燥した沈殿物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒２１を得た。
<< Experimental Example 21 >>
Add 29.1 g of cobalt nitrate hexahydrate and 9.86 g of zirconium oxynitrate aqueous solution (trade name “Zircosol ZN”, manufactured by Daiichi Rare Element Chemical Industries, Ltd .: 25% by mass as zirconium oxide) to 500 mL of distilled water. And mixed to prepare a uniform aqueous solution. This aqueous solution was added dropwise to an aqueous solution in which 75.0 g of potassium hydroxide was dissolved in 500 mL of stirring distilled water to produce a precipitate. The precipitate was filtered, washed with water, and dried overnight at 120 ° C. The dried precipitate was pulverized, filled into an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 21.
≪実験例２２≫
硝酸コバルト六水和物３４．９２ｇ、硝酸セリウム六水和物１．７４ｇおよびオキシ硝酸ジルコニウム水溶液（商品名「ジルコゾールＺＮ」、第一稀元素化学工業株式会社製：酸化ジルコニウムとして、２５質量％含有）９．８６ｇを蒸留水５００ｍＬに添加して混合し、均一な水溶液を調製した。この水溶液を、攪拌している蒸留水５００ｍＬに水酸化カリウム４５．０ｇを溶解させた水溶液に滴下して、沈殿物を生成させた。この沈殿物を濾過し、水洗した後、１２０℃で一晩乾燥させた。この乾燥した沈殿物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒２２を得た。
<< Experimental Example 22 >>
Cobalt nitrate hexahydrate 34.92 g, cerium nitrate hexahydrate 1.74 g and zirconium oxynitrate aqueous solution (trade name “Zircosol ZN”, manufactured by Daiichi Rare Element Chemical Industries, Ltd .: 25% by mass as zirconium oxide ) 9.86 g was added to 500 mL of distilled water and mixed to prepare a uniform aqueous solution. This aqueous solution was dropped into an aqueous solution in which 45.0 g of potassium hydroxide was dissolved in 500 mL of stirring distilled water, thereby generating a precipitate. The precipitate was filtered, washed with water, and dried overnight at 120 ° C. The dried precipitate was pulverized, filled in an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 22.
≪実験例２３≫
硝酸コバルト六水和物２９．１ｇおよび硝酸セリウム六水和物８．６８ｇを蒸留水５００ｍＬに添加混合して、均一な水溶液を調製した。この水溶液を、攪拌している蒸留水５００ｍＬに水酸化カリウム７３．０ｇを溶解させた水溶液に滴下して、沈殿物を生成させた。この沈殿物を濾過し、水洗した後、１２０℃で一晩乾燥させた。この乾燥した沈殿物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒２３を得た。
<< Experimental Example 23 >>
A uniform aqueous solution was prepared by adding 29.1 g of cobalt nitrate hexahydrate and 8.68 g of cerium nitrate hexahydrate to 500 mL of distilled water. This aqueous solution was dropped into an aqueous solution in which 73.0 g of potassium hydroxide was dissolved in 500 mL of stirring distilled water, thereby generating a precipitate. The precipitate was filtered, washed with water, and dried overnight at 120 ° C. The dried precipitate was pulverized, filled in an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 23.
≪実験例２４≫
蒸留水２０ｍＬに硝酸セシウム０．０２９５ｇを溶解させた水溶液に、実験例１２で調製した４ｇの触媒１２を加え、湯浴上で加熱して乾固させ、触媒１２に硝酸セシウムを含浸させた。この含浸物を１２０℃で一晩乾燥させた。この乾燥した含浸物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒２４を得た。
«Experimental example 24»
4 g of the catalyst 12 prepared in Experimental Example 12 was added to an aqueous solution in which 0.0295 g of cesium nitrate was dissolved in 20 mL of distilled water, and the mixture was heated to dryness in a hot water bath to impregnate the catalyst 12 with cesium nitrate. The impregnation was dried at 120 ° C. overnight. The dried impregnated product was pulverized, filled in an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 24.
≪実験例２５≫
実験例２４において、硝酸セシウム０．０２９５ｇを硝酸セシウム０．０５９３ｇに変更したこと以外は、実験例２４と同様にして、触媒２５を得た。得られた触媒２５のＸ線回折パターンを図３に示す。
<< Experimental Example 25 >>
In Example 24, catalyst 25 was obtained in the same manner as Example 24 except that 0.0295 g of cesium nitrate was changed to 0.0593 g of cesium nitrate. An X-ray diffraction pattern of the obtained catalyst 25 is shown in FIG.
≪実験例２６≫
実験例２４において、硝酸セシウム０．０２９５ｇを硝酸セシウム０．１２ｇに変更したこと以外は、実験例２４と同様にして、触媒２６を得た。
«Experimental example 26»
In Example 24, catalyst 26 was obtained in the same manner as Example 24, except that 0.0295 g of cesium nitrate was changed to 0.12 g of cesium nitrate.
≪実験例２７≫
実験例２４において、硝酸セシウム０．０２９５ｇを硝酸セシウム０．２４４ｇに変更したこと以外は、実験例２４と同様にして、触媒２７を得た。
≪Experimental example 27≫
In Example 24, catalyst 27 was obtained in the same manner as Example 24, except that 0.0295 g of cesium nitrate was changed to 0.244 g of cesium nitrate.
≪実験例２８≫
実験例２４において、硝酸セシウム０．０２９５ｇを硝酸セシウム０．３７４ｇに変更したこと以外は、実験例２４と同様にして、触媒２８を得た。
«Experimental example 28»
In Example 24, catalyst 28 was obtained in the same manner as Example 24, except that 0.0295 g of cesium nitrate was changed to 0.374 g of cesium nitrate.
≪実験例２９≫
実験例２４において、硝酸セシウム０．０２９５ｇを硝酸セシウム０．６５２ｇに変更したこと以外は、実験例２４と同様にして、触媒２９を得た。
≪Experimental example 29≫
A catalyst 29 was obtained in the same manner as in Experimental Example 24 except that 0.0295 g of cesium nitrate was changed to 0.652 g of cesium nitrate in Experimental Example 24.
≪実験例３０≫
蒸留水２０ｍＬに硝酸セシウム０．０２９５ｇを溶解させた水溶液に、実験例１１で調製した４ｇの触媒１１を加え、湯浴中で加熱して乾固させ、触媒１１に硝酸セシウムを含浸させた。この含浸物を１２０℃で一晩乾燥させた。この乾燥した含浸物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒３０を得た。
<< Experimental Example 30 >>
4 g of the catalyst 11 prepared in Experimental Example 11 was added to an aqueous solution in which 0.0295 g of cesium nitrate was dissolved in 20 mL of distilled water, and heated to dryness in a hot water bath, and the catalyst 11 was impregnated with cesium nitrate. The impregnation was dried at 120 ° C. overnight. The dried impregnated product was pulverized, filled in an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain
≪実験例３１≫
蒸留水２０ｍＬに硝酸カリウム０．０５２ｇを溶解させた水溶液に、実験例１２で調製した４ｇの触媒１２を加え、湯浴中で加熱して乾固させ、触媒１２に硝酸カリウムを含浸させた。この含浸物を１２０℃で一晩乾燥させた。この乾燥した含浸物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒３１を得た。
≪Experimental example 31≫
4 g of the catalyst 12 prepared in Experimental Example 12 was added to an aqueous solution in which 0.052 g of potassium nitrate was dissolved in 20 mL of distilled water, heated in a hot water bath to dryness, and the catalyst 12 was impregnated with potassium nitrate. The impregnation was dried at 120 ° C. overnight. The dried impregnated product was pulverized, filled in an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 31.
≪実験例３２≫
実験例３１において、硝酸カリウム０．０５２ｇを硝酸カリウム０．１０４ｇに変更したこと以外は、実験例３１と同様にして、触媒３２を得た。
<< Experimental Example 32 >>
A catalyst 32 was obtained in the same manner as in Experimental Example 31, except that 0.052 g of potassium nitrate was changed to 0.104 g of potassium nitrate in Experimental Example 31.
≪実験例３３≫
実験例３１において、硝酸カリウム０．０５２ｇを硝酸カリウム０．２１１ｇに変更したこと以外は、実験例３１と同様にして、触媒３３を得た。
<< Experimental Example 33 >>
A catalyst 33 was obtained in the same manner as in Experimental Example 31, except that 0.052 g of potassium nitrate was changed to 0.211 g of potassium nitrate in Experimental Example 31.
≪実験例３４≫
蒸留水２０ｍＬに硝酸バリウム０．０７７ｇを溶解させた水溶液に、実験例１２で調製した４ｇの触媒１２を加え、湯浴中で加熱して乾固させ、触媒１２に硝酸バリウムを含浸させた。この含浸物を１２０℃で一晩乾燥させた。この乾燥した含浸物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒３４を得た。
«Experimental example 34»
4 g of the catalyst 12 prepared in Experimental Example 12 was added to an aqueous solution in which 0.077 g of barium nitrate was dissolved in 20 mL of distilled water, and heated to dryness in a hot water bath, and the catalyst 12 was impregnated with barium nitrate. The impregnation was dried at 120 ° C. overnight. The dried impregnated product was pulverized, filled in an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain a catalyst 34.
≪実験例３５≫
実験例３４において、硝酸バリウム０．０７７ｇを硝酸バリウム０．１５５ｇに変更したこと以外は、実験例３４と同様にして、触媒３５を得た。
<< Experimental Example 35 >>
A catalyst 35 was obtained in the same manner as in Experimental Example 34 except that 0.077 g of barium nitrate was changed to 0.155 g of barium nitrate in Experimental Example 34.
≪実験例３６≫
実験例３４において、硝酸バリウム０．０７７ｇを硝酸バリウム０．８４６ｇに変更したこと以外は、実験例３４と同様にして、触媒３６を得た。
<< Experimental Example 36 >>
In Example 34, catalyst 36 was obtained in the same manner as Example 34, except that 0.077 g of barium nitrate was changed to 0.846 g of barium nitrate.
≪実験例３７≫
蒸留水２０ｍＬに硝酸ストロンチウム０．１２７ｇを溶解させた水溶液に、実験例１２で調製した４ｇの触媒１２を加え、湯浴中で加熱して乾固させ、触媒１２に硝酸ストロンチウムを含浸させた。この含浸物を１２０℃で一晩乾燥させた。この乾燥した含浸物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒３７を得た。
≪Experimental example 37≫
4 g of the catalyst 12 prepared in Experimental Example 12 was added to an aqueous solution in which 0.127 g of strontium nitrate was dissolved in 20 mL of distilled water, and heated to dryness in a hot water bath, and the catalyst 12 was impregnated with strontium nitrate. The impregnation was dried at 120 ° C. overnight. The dried impregnated product was pulverized, filled into an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 37.
≪実験例３８≫
蒸留水２０ｍＬに硝酸セシウム０．０５９３ｇを溶解させた水溶液に、実験例１３で調製した４ｇの触媒１３を加え、湯浴中で加熱して乾固させ、触媒１３に硝酸セシウムを含浸させた。この含浸物を１２０℃で一晩乾燥させた。この乾燥した含浸物を粉砕し、環状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて、６００℃で１時間還元処理して、触媒３８を得た。
<< Experimental Example 38 >>
4 g of the catalyst 13 prepared in Experimental Example 13 was added to an aqueous solution in which 0.0593 g of cesium nitrate was dissolved in 20 mL of distilled water, and heated to dryness in a hot water bath, and the catalyst 13 was impregnated with cesium nitrate. The impregnation was dried at 120 ° C. overnight. The dried impregnated product was pulverized, filled in an annular furnace, and reduced at 600 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain a catalyst 38.
≪アンモニア分解触媒の物性測定≫
実験例１〜３８で得られた触媒１〜３８について、触媒組成の定量、比表面積および結晶子サイズの測定を行った。結果を表１に示す。
≪Measurement of physical properties of ammonia decomposition catalyst≫
The catalysts 1 to 38 obtained in Experimental Examples 1 to 38 were subjected to quantitative determination of the catalyst composition, specific surface area, and crystallite size. The results are shown in Table 1.
≪アンモニア分解反応≫
実験例１〜３８で得られた触媒１〜３８、および、純度９９．９体積％以上のアンモニアを用いて、アンモニア分解反応を行い、アンモニアを窒素と水素とに分解した。
≪Ammonia decomposition reaction≫
Using the catalysts 1 to 38 obtained in Experimental Examples 1 to 38 and ammonia having a purity of 99.9% by volume or more, an ammonia decomposition reaction was performed to decompose the ammonia into nitrogen and hydrogen.
なお、アンモニア分解率は、アンモニアの空間速度６，０００ｈｒ−１、反応温度４００℃、４５０℃、５００℃、５５０℃、６００℃、または、７００℃、反応圧力０．１０１３２５ＭＰａ（常圧）の条件下で測定した（下記式により算出した）。その結果を表１に示す。 The ammonia decomposition rate is a condition in which the space velocity of ammonia is 6,000 hr −1 , the reaction temperature is 400 ° C., 450 ° C., 500 ° C., 550 ° C., 600 ° C., or 700 ° C., and the reaction pressure is 0.101325 MPa (normal pressure). Measured below (calculated by the following formula). The results are shown in Table 1.
表２から明らかなように、触媒１〜３８は、一部の例外を除いて、純度９９．９体積％以上という高濃度のアンモニアを、４００〜６００℃という比較的低温で、かつ、６，０００ｈ−１という高い空間速度で効率よく窒素と水素とに分解することができる。また、触媒１１、１２および１５〜３７は、鉄族金属であるコバルトまたはニッケル、および、金属酸化物であるセリア、ジルコニア、セリアとジルコニアとの固溶体、セリアとイットリアとの固溶体またはセリアと酸化ランタンとの固溶体を含有するので、アンモニア分解率が比較的高い。さらに、触媒２４〜２９、触媒３１〜３３および触媒３４〜３６を比較すると、鉄族金属であるコバルトおよび金属酸化物であるセリアとジルコニアとの固溶体に添加成分であるセシウム、カリウムまたはバリウムを適切な量（具体的には、セシウムの場合は、２〜４質量％、カリウムの場合は、約１質量％、バリウムの場合は、約２質量％）で添加すれば、アンモニア分解率が向上することがわかる。しかも、触媒１３〜１４および触媒３８を比較すると、鉄族金属である鉄および金属酸化物であるセリアとジルコニアとの固溶体に添加成分であるセシウムを適切な量（具体的には、１質量％）で添加すれば、アンモニア分解率が向上することがわかる。 As is apparent from Table 2, with a few exceptions, the catalysts 1 to 38 were prepared with a high concentration of ammonia having a purity of 99.9% by volume or higher at a relatively low temperature of 400 to 600 ° C. and 6, It can be efficiently decomposed into nitrogen and hydrogen at a high space velocity of 000 h −1 . Further, the catalysts 11, 12 and 15 to 37 are composed of cobalt or nickel which is an iron group metal and ceria, zirconia which is a metal oxide, a solid solution of ceria and zirconia, a solid solution of ceria and yttria, or ceria and lanthanum oxide. Therefore, the ammonia decomposition rate is relatively high. Further, when the catalysts 24-29, 31-33 and 34-36 are compared, the cesium, potassium or barium which is an additive component is appropriately added to the solid solution of cobalt, which is an iron group metal, and ceria, which is a metal oxide, and zirconia. Addition of a small amount (specifically, 2 to 4% by mass in the case of cesium, about 1% by mass in the case of potassium, and about 2% by mass in the case of barium) improves the ammonia decomposition rate. I understand that. Moreover, when the catalysts 13 to 14 and the catalyst 38 are compared, an appropriate amount (specifically, 1% by mass) of cesium, which is an additive component, is added to the solid solution of iron, which is an iron group metal, and ceria, which is a metal oxide, and zirconia. ), The ammonia decomposition rate is improved.
本発明は、アンモニアの分解に関するものであり、アンモニアを含有するガスを処理して無臭化する環境分野や、アンモニアを窒素と水素とに分解して水素を取得するエネルギー分野などにおいて、多大の貢献をなすものである。 The present invention relates to the decomposition of ammonia, and makes a great contribution in the environmental field in which ammonia-containing gas is treated and non-brominated, and in the energy field in which ammonia is decomposed into nitrogen and hydrogen to obtain hydrogen. It is what makes.
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