JP2004050111A

JP2004050111A - Catalyst for dehydrogenation of ethylbenzene in the presence of carbon dioxide

Info

Publication number: JP2004050111A
Application number: JP2002213492A
Authority: JP
Inventors: Masahiro Saito; 斉藤　昌弘; Isao Takahara; 高原　功; Kazuhisa Murata; 村田　和久; Hitoshi Inaba; 稲葉　仁; Naoki Mimura; 三村　直樹
Original assignee: National Institute of Advanced Industrial Science and Technology AIST
Current assignee: National Institute of Advanced Industrial Science and Technology AIST
Priority date: 2002-07-23
Filing date: 2002-07-23
Publication date: 2004-02-19
Anticipated expiration: 2022-07-23
Also published as: JP3837512B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst which exhibits high activity when ethylbenzene is dehydrogenated under the coexistence of carbon dioxide to produce styrene. <P>SOLUTION: The catalyst for dehydrogenation of ethylbenzene composed of iron oxide, aluminum oxide and yttrium oxide as essential components, and when the whole catalyst is considered to be 100 wt.%, preferably the contents of the iron oxide, aluminum oxide and yttrium oxide are adjusted to 5-20 wt.%, 60-94 wt.% and 1-20 wt.%, respectively. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、エチルベンゼンを二酸化炭素共存下で脱水素反応させることによりスチレンモノマーを製造する際に使用する触媒に関するものである。
【０００２】
【従来の技術】
従来、スチレンモノマーを工業的に製造するには、エチルベンゼンを、大量の水蒸気共存下に、酸化鉄とカリウムを主成分とする触媒上に６００℃程度の温度で接触させる方法が採用されている（触媒、３８巻、７号、５７２〜５７９（１９９６））。
しかしながら、この方法は、▲１▼大量の水蒸気を共存させるために、エネルギー消費量が大きいこと、▲２▼スチレンモノマーの単通収率を高くするために、反応を減圧下で行う必要があること、▲３▼反応中に触媒中のカリウムの揮散がおこることなど、改善すべき点も指摘されている。
これらの問題点を解決するために、本発明者らは、先に水蒸気の代わりに、二酸化炭素を共存ガスに用いることにより、▲１▼従来のプロセスよりエネルギー消費量が低くなる、▲２▼スチレンモノマーの単通収率が高くなる可能性を報告している（Ｃａｔａｌｙｓｉｓ　Ｔｏｄａｙ，　５５（２０００）１７３−１７８）。
しかしながら、この二酸化炭素を用いる新しい方法においても、優れた触媒が必要とされており、本発明者らは、先に、酸化鉄、酸化カルシウムおよび酸化アルミニウムからなる触媒（特許第３０３２８１６号）を開発すると共にさらにこの触媒の改良を意図とし、酸化鉄、酸化アルミニウムおよび酸化セリウムを必須成分とする触媒（特願２００１−３２１７８８）を提案した。
【０００３】
【発明が解決しようとする課題】
本発明は、上記した特願２００１−３２１７８８号の発明を更に発展・飛躍させたものであり、エチルベンゼンを二酸化炭素共存下で脱水素反応させることによりスチレンモノマーを製造する方法において、更に高性能な触媒を提供することを課題とする。
【０００４】
【課題を解決するための手段】
本発明者は、酸化鉄および酸化アルミニウムからなる触媒の性能に及ぼす種々の添加物の影響を検討した結果、意外にも酸化イットリウムを添加した触媒により、その課題を解決し得ることを見い出した。
【０００５】
即ち、本発明によれば、第一に、酸化鉄、酸化アルミニウムおよび酸化イットリウムを必須成分とする、二酸化炭素共存下でのエチルベンゼン脱水素反応において高い性能を示す触媒が提供される。
第二に、第一の発明において、酸化鉄、酸化アルミニウムおよび酸化イットリウムを必須成分とする触媒であって、触媒全体を１００重量％とするとき、各酸化物の含有量が、上記の順に５〜２０重量％、６０〜９４重量％、１〜２０重量％であることを特徴とする二酸化炭素共存下でのエチルベンゼン脱水素反応用触媒が提供される。
第三に、エチルベンゼンを二酸化炭素の存在下、上記第１又は第２記載の触媒に接触させることを特徴とするスチレンモノマーの製造方法が提供される。
【０００６】
【発明の実施の形態】
以下本発明を詳細に説明する。
【０００７】
本発明の二酸化炭素共存下でのエチルベンゼン脱水素反応用触媒は、酸化鉄、酸化アルミニウムおよび酸化イットリウムを必須成分とすることを特徴とする。
【０００８】
本発明の触媒は、二酸化炭素共存下でのエチルベンゼン脱水素反応において、前記特願２００１−３２１７８８記載の触媒よりも同等以上の更に優れた性能を発揮する。
これは、新たに添加した酸化イットリウムの作用によるものである。酸化イットリウムの作用の内容が完全には明らかになっているわけではないが、酸化イットリウムが、非常に弱い塩基性を示すことにより、反応中の触媒表面に二酸化炭素を適度な強さで吸着し、反応を促進するものと推察している。
【０００９】
各触媒成分の割合は、特に限定されないが、触媒全体を１００重量％とするとき、酸化鉄が５〜２０重量％、酸化アルミニウムが６０〜９４重量％、酸化イットリウムが１〜２０重量％とされる。このような量的範囲において、組成を反応条件に応じて適切に定めることにより、その反応条件に適した触媒性能を得ることができる。
また、本発明の脱水素反応用触媒は、酸化鉄、酸化アルミニウムおよび酸化イットリウムを必須成分とするが、本発明の反応を損なわない範囲で、他の物質を含んでいても良い。このような物質としては、たとえば、酸化カルシウム、酸化マグネシウム、酸化マンガン、酸化珪素、酸化ランタン、酸化セリウムなどが挙げられる。
【００１０】
本発明の触媒成分となる酸化鉄、酸化アルミニウムおよび酸化イットリウムの原料としては、それぞれの硝酸塩、塩酸塩、硫酸鉛、有機酸塩、水酸化物等を用いることができる。触媒は、共沈法、含浸法、混合法、逐次沈殿法、アルコキシド法等の方法により、あるいは、これらの方法を組み合わせた方法により触媒前駆体を調製し、次いで、触媒前駆体を空気中で焼成することにより製造できる。触媒前駆体の焼成温度は、特に限定しないが、３００〜１０００℃の範囲が好ましく、６００〜８００℃が特に好ましい。
【００１１】
このようにして製造された触媒は、そのままで、あるいは適当な方法により造粒または打錠成型して用いる。触媒の粒子径や形状は、反応方式、反応器の形状によって任意に選択できる。すなわち、本発明による触媒は、固定床、流動床等いずれの反応方式においても用いることができる。
【００１２】
本発明による触媒を用いて、エチルベンゼンの脱水素反応によりスチレンを製造する際の反応条件は、特許第３０３２８１６号公報あるいは特願２００１−３２１７８８に記載された反応条件と同様であるが、二酸化炭素のエチルベンゼンに対する割合は、エチルベンゼン１モルあたり、０．１〜１００モル、好ましくは１〜５０モル、反応温度は５００〜６５０℃の範囲、好ましくは、５３０〜６３０℃、反応圧力は、加圧、常圧、減圧のいずれでも良く、好ましくは０．２〜１．５気圧（絶対圧力）である。また、本発明の触媒は、一定時間使用後に活性が低下した場合には、空気中で再度焼成することによりその性能を回復させることができる。
【００１３】
【実施例】
以下、実施例をあげて本発明の特徴とするところをより一層明確にする。
【００１４】
実施例１
硝酸鉄九水和物８．３ｇ、硝酸アルミニウム九水和物１０２．１ｇ、硝酸イットリウム六水和物２．８ｇを蒸留水に溶解し、３００ｍｌの水溶液を調製し、Ａ液とした。一方、無水炭酸ナトリウム５２．５ｇを蒸留水に溶解し、３００ｍｌの水溶液を調製し、Ｂ液とした。Ａ液およびＢ液を、それぞれ、８ｍｌ／分の速度で良く攪拌した８００ｍｌの室温の蒸留水に、同時に滴下して沈殿物を得た。この沈殿物を室温にて１日間熟成させた後、ろ過、洗浄を行い、沈殿物中のナトリウムを除去した。その後、沈殿物を１１０℃で乾燥し、空気中、７５０℃で２時間焼成し・た。次に、焼成後の酸化物を圧縮成型後、粉砕し、２５０〜６００μｍに粒度調製して、触媒とした。この触媒の組成は、酸化鉄１０重量％、酸化アルミニウム８５重量％、酸化イットリウム（Ｙ_２Ｏ_３）５重量％であった。
【００１５】
得られた触媒２ｇを反応管に充填し、二酸化炭素中で反応温度に昇温した後、１０容量％のエチルベンゼン蒸気および９０容量％の二酸化炭素からなる混合ガスを触媒層に通して、圧力０．１ＭＰａ、混合ガス流量６８ｍｌ／分、温度５５０℃の条件下に上記混合ガスを反応させた。反応生成ガスを−１℃で冷却して得られた液体成分をガスクロマトグラフで分析した。その結果、反応経過時間６時間後において、スチレン収率５１％、スチレン選択率９６％であった（表１参照）。
【００１６】
実施例２
硝酸鉄九水和物８．５ｇ、硝酸アルミニウム九水和物９９．０ｇ、硝酸イットリウム六水和物５．７ｇを蒸留水に溶解し、３００ｍｌの水溶液を調製し、Ａ液とした。一方、無水炭酸ナトリウム５２．５ｇを蒸留水に溶解し、３００ｍｌの水溶液を調製し、Ｂ液とした。Ａ液およびＢ液を、それぞれ、８ｍｌ／分の速度で良く攪拌した８００ｍｌの室温の蒸留水に、同時に滴下して沈殿物を得た。この沈殿物を室温にて１日間熟成させた後、ろ過、洗浄を行い、沈殿物中のナトリウムを除去した。その後、沈殿物を１１０℃で乾燥し、空気中、７５０℃で２時間焼成した。次に、焼成後の酸化物を圧縮成型後、粉砕し、２５０〜６００μｍに粒度調製して、触媒とした。この触媒の組成は、酸化鉄１０重量％、酸化アルミニウム８０重量％、酸化イットリウム（Ｙ_２Ｏ_３）１０重量％であった。
【００１７】
得られた触媒２ｇを反応管に充填し、実施例１と同様なエチルベンゼンの脱水素反応を行った。その結果、反応経過時間６時間後において、スチレン収率５０％、スチレン選択率９６％であった（表１参照）。
【００１８】
実施例３
硝酸鉄九水和物８．８ｇ、硝酸アルミニウム九水和物９５．７ｇ、硝酸イットリウム六水和物８．８ｇを蒸留水に溶解し、３００ｍｌの水溶液を調製し、Ａ液とした。一方、無水炭酸ナトリウム５２．５ｇを蒸留水に溶解し、３００ｍｌの水溶液を調製し、Ｂ液とした。Ａ液およびＢ液を、それぞれ、８ｍｌ／分の速度で良く攪拌した８００ｍｌの室温の蒸留水に、同時に滴下して沈殿物を得た。この沈殿物を室温にて１日間熟成させた後、ろ過、洗浄を行い、沈殿物中のナトリウムを除去した。その後、沈殿物を１１０℃で乾燥し、空気中、７５０℃で２時間焼成した。次に、焼成後の酸化物を圧縮成型後、粉砕し、２５０〜６００μｍに粒度調製して、触媒とした。この触媒の組成は、酸化鉄１０重量％、酸化アルミニウム７５重量％、酸化イットリウム（Ｙ_２Ｏ_３）１５重量％であった。
【００１９】
得られた触媒２ｇを反応管に充填し、実施例１と同様なエチルベンゼンの脱水素反応を行った。その結果、反応経過時間６時間後において、スチレン収率５０％、スチレン選択率９７％であった（表１参照）。
【００２０】
比較例１
硝酸アルミニウム九水和物１０７．２ｇ、硝酸イットリウム六水和物５．５ｇを蒸留水に溶解し、３００ｍｌの水溶液を調製し、Ａ液とした。一方、無水炭酸ナトリウム５２．５ｇを蒸留水に溶解し、３００ｍｌの水溶液を調製し、Ｂ液とした。Ａ液およびＢ液を、それぞれ、８ｍｌ／分の速度で良く攪拌した８００ｍｌの室温の蒸留水に、同時に滴下して沈殿物を得た。この沈殿物を室温にて１日間熟成させた後、ろ過、洗浄を行い、沈殿物中のナトリウムを除去した。その後、沈殿物を１１０℃で乾燥し、空気中、７５０℃で２時間焼成した。次に、焼成後の酸化物を圧縮成型後、粉砕し、２５０〜６００μｍに粒度調製して、触媒とした。この触媒の組成は、酸化アルミニウム９０重量％、酸化イットリウム１０重量％であった。
【００２１】
得られた触媒２ｇを反応管に充填し、実施例１と同様なエチルベンゼンの脱水素反応を行った。その結果、反応経過時間６時間後において、スチレン収率３％、スチレン選択率８７％であった（表１参照）。
この結果から、酸化アルミニウムと酸化イットリウムからなる触媒はほとんど活性を示さず、酸化イットリウムを添加した本発明の触媒における酸化イットリウムは、酸化鉄と酸化アルミニウムからなる触媒の性能を高める役割を果たしていることが判る。
【００２２】
比較例２
硝酸鉄九水和物８．３ｇ、硝酸アルミニウム九水和物１０３．０ｇ、硝酸セリウム六水和物２．１ｇを蒸留水に溶解し、３００ｍｌの水溶液を調製し、Ａ液とした。一方、無水炭酸ナトリウム５２．５ｇを蒸留水に溶解し、３００ｍｌの水溶液を調製し、Ｂ液とした。Ａ液およびＢ液を、それぞれ、８ｍｌ／分の速度で良く攪拌した８００ｍｌの室温の蒸留水に、同時に滴下して沈殿物を得た。この沈殿物を室温にて１日間熟成させた後、ろ過、洗浄を行い、沈殿物中のナトリウムを除去した。その後、沈殿物を１１０℃で乾燥し、空気中、７５０℃で２時間焼成した。次に、焼成後の酸化物を圧縮成型後、粉砕し、２５０〜６００μｍに粒度調製して、触媒とした。この触媒の組成は、酸化鉄１０重量％、酸化アルミニウム８５重量％、酸化セリウム（ＣｅＯ_２）５重量％であった。
【００２３】
得られた触媒２ｇを反応管に充填し、実施例１と同様なエチルベンゼンの脱水素反応を行った。その結果、反応経過時間６時間後において、スチレン収率４８％、スチレン選択率９６％であった（表１参照）。
この結果から、酸化イットリウムを添加した本発明の触媒は、酸化セリウムを添加した特願２００１−３２１７８８号発明の触媒より触媒活性が高いことが判る。
【００２４】
【表１】

【００２５】
【発明の効果】
本発明の触媒は、二酸化炭素共存下でのエチルベンゼンの脱水素反応において、長時間その触媒活性が低下せず極めて高い触媒活性を示すものである。従って、スチレンモノマーを工業的有利に製造することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a catalyst used for producing a styrene monomer by subjecting ethylbenzene to a dehydrogenation reaction in the presence of carbon dioxide.
[0002]
[Prior art]
Conventionally, in order to industrially produce a styrene monomer, a method has been employed in which ethylbenzene is brought into contact with a catalyst containing iron oxide and potassium as main components at a temperature of about 600 ° C. in the presence of a large amount of steam ( Catalyst, Vol. 38, No. 7, 572-579 (1996)).
However, in this method, (1) the energy consumption is large in order to coexist a large amount of water vapor, and (2) the reaction needs to be performed under reduced pressure in order to increase the single-pass yield of styrene monomer. (3) It is pointed out that points to be improved such as volatilization of potassium in the catalyst during the reaction.
In order to solve these problems, the present inventors have previously used carbon dioxide instead of water vapor as a coexisting gas, thereby reducing (1) energy consumption compared to conventional processes, (2). It is reported that the single yield of styrene monomer may be increased (Catalysis Today, 55 (2000) 173-178).
However, even in this new method using carbon dioxide, an excellent catalyst is required, and the present inventors have previously developed a catalyst composed of iron oxide, calcium oxide, and aluminum oxide (Japanese Patent No. 3032816). In addition, with the intention of further improving this catalyst, a catalyst (Japanese Patent Application No. 2001-321788) containing iron oxide, aluminum oxide and cerium oxide as essential components was proposed.
[0003]
[Problems to be solved by the invention]
The present invention is a further development and leap of the invention of Japanese Patent Application No. 2001-321788 described above. In the method for producing a styrene monomer by subjecting ethylbenzene to a dehydrogenation reaction in the presence of carbon dioxide, a further high-performance method is provided. It is an object to provide a catalyst.
[0004]
[Means for Solving the Problems]
As a result of examining the effects of various additives on the performance of a catalyst composed of iron oxide and aluminum oxide, the present inventors have surprisingly found that a catalyst containing yttrium oxide can solve the problem.
[0005]
That is, according to the present invention, firstly, there is provided a catalyst containing iron oxide, aluminum oxide and yttrium oxide as essential components and exhibiting high performance in an ethylbenzene dehydrogenation reaction in the presence of carbon dioxide.
Secondly, in the first invention, the catalyst containing iron oxide, aluminum oxide and yttrium oxide as essential components. When the whole catalyst is 100% by weight, the content of each oxide is 5% in the above order. A catalyst for dehydrogenation of ethylbenzene in the presence of carbon dioxide, which is characterized by being in the range of -20% by weight, 60-94% by weight, and 1-20% by weight.
Thirdly, there is provided a method for producing a styrene monomer, which comprises contacting ethylbenzene with the catalyst according to the first or second aspect in the presence of carbon dioxide.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
[0007]
The catalyst for dehydrogenation of ethylbenzene in the presence of carbon dioxide according to the present invention is characterized by containing iron oxide, aluminum oxide and yttrium oxide as essential components.
[0008]
The catalyst of the present invention exhibits, in an ethylbenzene dehydrogenation reaction in the presence of carbon dioxide, a performance that is equal to or better than the catalyst described in Japanese Patent Application No. 2001-321788.
This is due to the action of newly added yttrium oxide. Although the nature of the action of yttrium oxide has not been completely elucidated, yttrium oxide exhibits a very weak basicity, and adsorbs carbon dioxide with moderate strength on the catalyst surface during the reaction. It is speculated that it promotes the reaction.
[0009]
Although the ratio of each catalyst component is not particularly limited, when the whole catalyst is 100% by weight, iron oxide is 5 to 20% by weight, aluminum oxide is 60 to 94% by weight, and yttrium oxide is 1 to 20% by weight. You. In such a quantitative range, by appropriately determining the composition according to the reaction conditions, it is possible to obtain a catalyst performance suitable for the reaction conditions.
The catalyst for dehydrogenation reaction of the present invention contains iron oxide, aluminum oxide and yttrium oxide as essential components, but may contain other substances as long as the reaction of the present invention is not impaired. Examples of such a substance include calcium oxide, magnesium oxide, manganese oxide, silicon oxide, lanthanum oxide, and cerium oxide.
[0010]
As a raw material of iron oxide, aluminum oxide and yttrium oxide which are the catalyst components of the present invention, respective nitrates, hydrochlorides, lead sulfates, organic acid salts, hydroxides and the like can be used. The catalyst is prepared by a method such as a coprecipitation method, an impregnation method, a mixing method, a sequential precipitation method, an alkoxide method, or a method combining these methods, and then the catalyst precursor is prepared in the air. It can be manufactured by firing. The firing temperature of the catalyst precursor is not particularly limited, but is preferably in the range of 300 to 1000C, and particularly preferably 600 to 800C.
[0011]
The catalyst thus produced is used as it is or after granulation or tableting by an appropriate method. The particle size and shape of the catalyst can be arbitrarily selected depending on the reaction system and the shape of the reactor. That is, the catalyst according to the present invention can be used in any reaction system such as a fixed bed and a fluidized bed.
[0012]
The reaction conditions for producing styrene by dehydrogenation of ethylbenzene using the catalyst according to the present invention are the same as the reaction conditions described in Japanese Patent No. 3032816 or Japanese Patent Application No. 2001-321788. The ratio to ethylbenzene is 0.1 to 100 mol, preferably 1 to 50 mol, per mol of ethylbenzene, the reaction temperature is in the range of 500 to 650 ° C, preferably 530 to 630 ° C, and the reaction pressure is The pressure may be either pressure or reduced pressure, preferably 0.2 to 1.5 atm (absolute pressure). Further, when the activity of the catalyst of the present invention decreases after use for a certain period of time, the performance can be recovered by calcining again in air.
[0013]
【Example】
Hereinafter, features of the present invention will be further clarified with reference to examples.
[0014]
Example 1
8.3 g of iron nitrate nonahydrate, 102.1 g of aluminum nitrate nonahydrate, and 2.8 g of yttrium nitrate hexahydrate were dissolved in distilled water to prepare a 300 ml aqueous solution, which was used as solution A. On the other hand, 52.5 g of anhydrous sodium carbonate was dissolved in distilled water to prepare a 300 ml aqueous solution, which was used as solution B. The solution A and the solution B were simultaneously dropped into 800 ml of room temperature distilled water, which was well stirred at a rate of 8 ml / min, to obtain a precipitate. This precipitate was aged at room temperature for one day, and then filtered and washed to remove sodium in the precipitate. Thereafter, the precipitate was dried at 110 ° C. and calcined in air at 750 ° C. for 2 hours. Next, the oxide after firing was compression-molded, pulverized, and adjusted to a particle size of 250 to 600 μm to obtain a catalyst. The composition of this catalyst was 10% by weight of iron oxide, 85% by weight of aluminum oxide, and 5% by weight of yttrium oxide (Y ₂ O ₃ ).
[0015]
After filling 2 g of the obtained catalyst in a reaction tube and raising the temperature to a reaction temperature in carbon dioxide, a mixed gas composed of 10% by volume of ethylbenzene vapor and 90% by volume of carbon dioxide was passed through the catalyst layer to obtain a pressure of 0%. The above mixed gas was reacted under the conditions of 0.1 MPa, a mixed gas flow rate of 68 ml / min, and a temperature of 550 ° C. The liquid component obtained by cooling the reaction product gas at -1 ° C was analyzed by gas chromatography. As a result, 6 hours after the reaction elapsed time, the styrene yield was 51% and the styrene selectivity was 96% (see Table 1).
[0016]
Example 2
8.5 g of iron nitrate nonahydrate, 99.0 g of aluminum nitrate nonahydrate, and 5.7 g of yttrium nitrate hexahydrate were dissolved in distilled water to prepare a 300 ml aqueous solution, which was used as solution A. On the other hand, 52.5 g of anhydrous sodium carbonate was dissolved in distilled water to prepare a 300 ml aqueous solution, which was used as solution B. The solution A and the solution B were simultaneously dropped into 800 ml of room temperature distilled water, which was well stirred at a rate of 8 ml / min, to obtain a precipitate. This precipitate was aged at room temperature for one day, and then filtered and washed to remove sodium in the precipitate. Thereafter, the precipitate was dried at 110 ° C. and calcined in air at 750 ° C. for 2 hours. Next, the oxide after firing was compression-molded, pulverized, and adjusted to a particle size of 250 to 600 μm to obtain a catalyst. The composition of this catalyst was 10% by weight of iron oxide, 80% by weight of aluminum oxide, and 10% by weight of yttrium oxide (Y ₂ O ₃ ).
[0017]
2 g of the obtained catalyst was filled in a reaction tube, and the same dehydrogenation reaction of ethylbenzene as in Example 1 was performed. As a result, after 6 hours of the reaction elapsed time, the styrene yield was 50% and the styrene selectivity was 96% (see Table 1).
[0018]
Example 3
8.8 g of iron nitrate nonahydrate, 95.7 g of aluminum nitrate nonahydrate, and 8.8 g of yttrium nitrate hexahydrate were dissolved in distilled water to prepare a 300 ml aqueous solution, which was used as solution A. On the other hand, 52.5 g of anhydrous sodium carbonate was dissolved in distilled water to prepare a 300 ml aqueous solution, which was used as solution B. The solution A and the solution B were simultaneously dropped into 800 ml of room temperature distilled water, which was well stirred at a rate of 8 ml / min, to obtain a precipitate. This precipitate was aged at room temperature for one day, and then filtered and washed to remove sodium in the precipitate. Thereafter, the precipitate was dried at 110 ° C. and calcined in air at 750 ° C. for 2 hours. Next, the oxide after firing was compression-molded, pulverized, and adjusted to a particle size of 250 to 600 μm to obtain a catalyst. The composition of this catalyst was 10% by weight of iron oxide, 75% by weight of aluminum oxide, and 15% by weight of yttrium oxide (Y ₂ O ₃ ).
[0019]
2 g of the obtained catalyst was filled in a reaction tube, and the same dehydrogenation reaction of ethylbenzene as in Example 1 was performed. As a result, 6 hours after the reaction elapsed time, the styrene yield was 50% and the styrene selectivity was 97% (see Table 1).
[0020]
Comparative Example 1
107.2 g of aluminum nitrate nonahydrate and 5.5 g of yttrium nitrate hexahydrate were dissolved in distilled water to prepare a 300 ml aqueous solution. On the other hand, 52.5 g of anhydrous sodium carbonate was dissolved in distilled water to prepare a 300 ml aqueous solution, which was used as solution B. The solution A and the solution B were simultaneously dropped into 800 ml of room temperature distilled water, which was well stirred at a rate of 8 ml / min, to obtain a precipitate. This precipitate was aged at room temperature for one day, and then filtered and washed to remove sodium in the precipitate. Thereafter, the precipitate was dried at 110 ° C. and calcined in air at 750 ° C. for 2 hours. Next, the oxide after firing was compression-molded, pulverized, and adjusted to a particle size of 250 to 600 μm to obtain a catalyst. The composition of this catalyst was 90% by weight of aluminum oxide and 10% by weight of yttrium oxide.
[0021]
2 g of the obtained catalyst was filled in a reaction tube, and the same dehydrogenation reaction of ethylbenzene as in Example 1 was performed. As a result, 6 hours after the reaction elapsed time, the styrene yield was 3% and the styrene selectivity was 87% (see Table 1).
From these results, the catalyst comprising aluminum oxide and yttrium oxide shows almost no activity, and the yttrium oxide in the catalyst of the present invention to which yttrium oxide is added plays a role of enhancing the performance of the catalyst comprising iron oxide and aluminum oxide. I understand.
[0022]
Comparative Example 2
8.3 g of iron nitrate nonahydrate, 103.0 g of aluminum nitrate nonahydrate, and 2.1 g of cerium nitrate hexahydrate were dissolved in distilled water to prepare a 300 ml aqueous solution, which was used as solution A. On the other hand, 52.5 g of anhydrous sodium carbonate was dissolved in distilled water to prepare a 300 ml aqueous solution, which was used as solution B. The solution A and the solution B were simultaneously dropped into 800 ml of room temperature distilled water, which was well stirred at a rate of 8 ml / min, to obtain a precipitate. This precipitate was aged at room temperature for one day, and then filtered and washed to remove sodium in the precipitate. Thereafter, the precipitate was dried at 110 ° C. and calcined in air at 750 ° C. for 2 hours. Next, the oxide after firing was compression-molded, pulverized, and adjusted to a particle size of 250 to 600 μm to obtain a catalyst. The composition of this catalyst was 10% by weight of iron oxide, 85% by weight of aluminum oxide, and 5% by weight of cerium oxide (CeO ₂ ).
[0023]
2 g of the obtained catalyst was filled in a reaction tube, and the same dehydrogenation reaction of ethylbenzene as in Example 1 was performed. As a result, 6 hours after the reaction elapsed time, the styrene yield was 48% and the styrene selectivity was 96% (see Table 1).
From this result, it is understood that the catalyst of the present invention to which yttrium oxide is added has higher catalytic activity than the catalyst of the invention of Japanese Patent Application No. 2001-321788 to which cerium oxide is added.
[0024]
[Table 1]

[0025]
【The invention's effect】
The catalyst of the present invention exhibits an extremely high catalytic activity without deteriorating its catalytic activity for a long time in the dehydrogenation reaction of ethylbenzene in the presence of carbon dioxide. Therefore, a styrene monomer can be produced industrially advantageously.

Claims

A catalyst for an ethylbenzene dehydrogenation reaction in the presence of carbon dioxide, comprising iron oxide, aluminum oxide and yttrium oxide as essential components.

A catalyst composed of a metal oxide containing iron oxide, aluminum oxide and yttrium oxide as essential components. When the entire catalyst is 100% by weight, the content of each oxide is 5 to 20% by weight in the above order. The catalyst for dehydrogenation of ethylbenzene in the presence of carbon dioxide according to claim 1, wherein the catalyst is used in an amount of 60 to 94% by weight or 1 to 20% by weight.

3. A method for producing a styrene monomer, comprising contacting ethylbenzene with the catalyst according to claim 1 in the presence of carbon dioxide.