JP3831444B2 - Hydrogen selective oxidation catalyst, hydrogen selective oxidation method, and hydrocarbon dehydrogenation method - Google Patents
Hydrogen selective oxidation catalyst, hydrogen selective oxidation method, and hydrocarbon dehydrogenation method Download PDFInfo
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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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Description
【０００１】
【発明の属する技術分野】
本発明は、炭化水素を脱水素して、脱水素された炭化水素を製造する際に、生成した混合ガス中に存在する水素を選択的に酸化する方法及びそれに用いる触媒に関する。
【０００２】
【従来の技術】
炭化水素を脱水素して、脱水素された炭化水素を製造するプロセスは、従来多くの文献に記載されている。例えばエチルベンゼンを脱水素してスチレンを合成するプロセスは、鉄系の触媒を用いて工業的に実施されている。しかしながら、一般に脱水素反応では、平衡の制約を強く受け高い収率を得ることができない。また、断熱反応器での反応においては、脱水素反応が吸熱反応であるため、反応温度が反応と共に低下してしまい高い収率で目的物を得ることが困難である。
【０００３】
このような状況から、既に幾つかの方法が提案されている。例えば、英国特許第１，４０４，６４１号明細書には、エチルベンゼンを脱水素した後に、未反応エチルベンゼン、スチレン及び水素を含む混合ガス中の水素を選択的に酸化するプロセス及び触媒が開示されている。この方法はスチレン合成に有効な方法であるが、水素の選択的酸化触媒として白金を担持したＡ型ゼオライト又はアルミナを用いており、その性能は必ずしも満足しうるものではない。
【０００４】
米国特許４５６５８９８号明細書においても、同様のプロセスでアルミナ上に白金、スズ及びリチウム等を担持した触媒を用いる方法が開示されている。しかしながら、この触媒もアルミナ上に担持されたものであり、その性能は充分なものとは言えない。また、特開昭５８−８９９４５号公報及び特開平６−２９８６７８号公報には、エチルベンゼンの脱水素反応により生成される、スチレン、エチルベンゼン、水素を含有する混合ガス中の水素を酸化スズ又は酸化スズとアルカリ金属を含有する触媒を用いて選択的に酸化する方法が開示されている。これらは白金を用いない触媒として注目されるものであるが、その性能は必ずしも充分とは言えない。
【０００５】
【発明が解決しようとする課題】
炭化水素の脱水素反応により生成される、未反応の炭化水素、脱水素された炭化水素、水素を含有する混合ガス中の水素を選択的に酸化するための触媒としては、上記したように、従来知られているものは性能的に満足なものではない。従って、本発明の目的は、該混合ガス中に存在する水素をより選択的に酸化するための新規な触媒を提供することにある。
【０００６】
【課題を解決するための手段】
本発明者らは上記課題を解決すべく鋭意検討した結果、特定の酸化物担体に白金又はパラジウムを担持した成分を含有する触媒が、水素の選択的酸化を高性能で行うことを見い出して本発明を完成するに至った。即ち、本発明の第１の要旨は、水素と炭化水素とを含有する混合ガスを、酸素含有ガスと接触させて、該混合ガス中の水素を選択的に酸化するための触媒であって、酸化チタン、酸化タンタル及び酸化ニオブからなる群から選ばれる１つ以上の担体に白金及び／又はパラジウムを担持させた成分を含有することを特徴とする水素の選択的酸化触媒に存する。
【０００７】
また、本発明の第２の要旨は、炭化水素及び水素を含有する混合ガスを、酸化触媒の存在下で酸素含有ガスと接触させて、該混合ガス中の水素を選択的に酸化させる方法において、酸化触媒として、酸化チタン、酸化タンタル及び酸化ニオブからなる群から選ばれるいずれか１つ以上の担体に白金及び／又はパラジウムを担持させた成分を含有する触媒を使用することを特徴とする水素の選択的酸化方法に存する。
【０００８】
さらに、本発明の第３の要旨は、原料炭化水素を脱水素触媒の存在下で脱水素反応させることにより得られた、脱水素された炭化水素、未反応原料炭化水素、及び水素を含有する混合ガスを、酸化触媒の存在下で酸素含有ガスと接触させて、該混合ガス中の水素を選択的に酸化させ、前記酸化反応により得られた炭化水素含有ガスをさらに脱水素反応させる炭化水素の脱水素方法において、酸化触媒として、酸化チタン、酸化タンタル及び酸化ニオブからなる群から選ばれるいずれか１つ以上の担体に白金及び／又はパラジウムを担持させた成分を含有する触媒を使用することを特徴とする炭化水素の脱水素方法に存する。
【０００９】
【発明の実施の形態】
本発明の方法で用いられる水素の選択的酸化触媒は、白金及び／又はパラジウムを担持した酸化チタン、酸化タンタル、又は酸化ニオブを含有する触媒である。本発明で用いられる酸化物担体は、触媒の製造に通常使用されている適当な方法で製造することができる。例えば、チタン、タンタル又はニオブの塩の水溶液にアンモニア水、炭酸アルカリ、重炭酸アルカリ等のアルカリ水溶液を攪拌しながら加えるか、チタン、タンタル又はニオブの有機塩溶液に水を攪拌しながら加え、水酸化物の沈澱を作り、沈澱の濾過、洗浄を行なう。この水酸化物を乾燥し、酸化物形態になる適当な温度、例えば２００〜１５００℃で焼成する。このようにして調製される酸化物は必要に応じて打錠成形又は押し出し成形して使用する。チタン、タンタル又はニオブの原料塩としては特に制限はなく、それらの塩化物、硝酸塩、硫酸塩、有機塩、水酸化物を用いることができる。また、これらの塩を直接焼成することにより酸化物形態の触媒担体を調製することもできる。
【００１０】
これらの酸化物担体に白金及び／又はパラジウムを担持する方法としては、焼成後の酸化物に白金及び／又はパラジウムの塩の水溶液を含浸し、これを５０〜１０００℃の温度で乾燥及び焼成する方法が挙げられる。白金及び／又はパラジウムの原料塩としては特に制限はなく、それらのハロゲン化物、水酸化物、硫酸塩、有機塩等を用いることができる。
【００１１】
白金及び／又はパラジウムの担持量は、担体酸化物に対し、０．０１〜１０重量％、好ましくは０．０５〜５重量％である。担持量が少なすぎると、酸化反応の活性が低下する可能性があり、また、これ以上担持量を多くしても反応特性に殆ど影響を与えないのでコストの面で不利となる。
【００１２】
本発明の酸化触媒は、水素と炭化水素とを含有する混合ガスを、酸素含有ガスと接触させて、該混合ガス中の水素を選択的に酸化する反応に用いられる。前記の反応は３００〜８００℃で行われることが好ましく、更に好ましくは４００〜７００℃の温度範囲である。温度が高すぎると、水素の選択率が減少し、炭化水素の燃焼が多くなるので好ましくない。温度が低すぎる場合には、選択率にはあまり影響を与えないが、活性が低下する可能性があるので好ましくない。
【００１３】
水素と炭化水素とを含有する混合ガスの具体例としては、原料炭化水素を脱水素触媒により脱水素反応させて得られる、脱水素された炭化水素、未反応原料炭化水素及び水素からなる混合ガスが挙げられる。酸素含有ガスとしては、分子状酸素を１〜１００％含有するガスが用いられ、具体的には空気、酸素富化空気、不活性ガスで希釈した空気などが好適に用いられる。また、酸素含有ガスに水蒸気を含有させることもできる。
【００１４】
本発明の選択的酸化触媒及び選択的酸化方法が適用される代表的なプロセスは次のようなものである。第１段反応器において脱水素触媒により原料炭化水素の脱水素反応を行った後に、この第１段の反応層から出る脱水素された炭化水素、未反応原料炭化水素及び水素を含む混合ガスは第２段の反応層へ送られる。この第２段反応層において、本発明の選択的酸化触媒の存在下で、新たに導入された酸素含有ガスを用いて、水素の選択的酸化を行う。これにより第１段の、吸熱反応である脱水素反応により低下した温度を上昇させ、且つ、水素を消費することにより脱水素反応の平衡的制約を除去する。更に、この第２段反応層から出たガスを第１段反応層と同様の第３段の脱水素反応層に送り、未反応の炭化水素の脱水素を実施する。既に第２段反応層において反応に必要な温度が回復されており、かつ平衡的制約も解除されているので、第３段脱水素反応層において更に高い収率を得ることができる。
【００１５】
必要に応じて更に上記の選択的酸化反応層と脱水素反応層との組み合わせを追加して反応を実施することもできる。一般に脱水素反応では水素気を共存させることが多いが、上記反応プロセスにおいても水蒸気を共存させることができる。
【００１６】
上記脱水素プロセスの代表的具体例としてエチルベンゼンの脱水素プロセスを挙げることができる。例えばエチルベンゼンと水蒸気の混合ガスを鉄とアルカリ金属を主要活性成分とした鉄系触媒が存在する第１段反応層に送り、５００℃〜８００℃の範囲の温度、０．０５〜１０気圧の範囲の圧力で脱水素反応を行う。この後、未反応エチルベンゼン、生成したスチレン、水素、水蒸気の混合ガスを第２段反応層へ送る。第２段反応層で本発明の酸化触媒の存在下で新たに導入された酸素含有ガスを用いて水素の選択的酸化を行う。次に、この反応ガスを第３段反応層へ送り、ここで再び鉄系触媒により未反応のエチルベンゼンの脱水素を行いより高い収率でスチレンを得る。
【００１７】このように本発明の方法を用いれば、平衡的制約が除かれ、かつ反応温度の低下を補償することができるため、通常の脱水素反応に比較して遙かに高い収率でスチレンを得ることができる。
【００１８】
【実施例】
以下に示す実施例により、本発明を更に具体的に説明するが、本発明はこれらの実施例により限定されるものではない。
【００１９】
比較例１
（触媒調製）
粒径０．８５〜１．０ｍｍの酸化アルミナ（α−Ａｌ2Ｏ3）５．２ｇを、白金として０．００２１ｇを含有する塩化白金酸（Ｈ2ＰｔＣｌ6・６Ｈ2Ｏ）水溶液２ｇに浸漬後、ロータリーエバポレーターにて６０℃の減圧下、乾燥させた。乾燥品は乾燥器中１２０℃で１晩乾燥後、マッフル炉に入れ６５０℃で３時間焼成した。このようにして白金を０．４重量％含む白金担持酸化アルミナ触媒を得た。
【００２０】
上記のようにして調製した触媒１ｍｌを、内径６．７ｍｍの石英製反応管に充填した。この上部に石英チップを充填した後、水素ガスを約５０ｍｌ／分の流量で反応管に流しながら５００℃まで昇温後１時間保持し触媒還元処理を施した。
【００２１】
（反応）次に、水素を窒素に切り換え反応系内を窒素にて充分置換してからスチレン（以下ＳＭということがある）、エチルベンゼン（以下ＥＢということがある）、水、水素及び空気混合ガスを反応管に導入して反応を開始した。混合ガス組成および反応器における空間速度は次の通りであった。
【００２２】
【数１】
【数２】
反応開始２時間後に、反応管出口のガス及び液受器でトラップされた液についてガスクロマトグラフで分析を行って、水素転化率、酸素転化率、スチレン及びエチルベンゼン燃焼率を算出した。結果を表１に示す。ここでスチレン及びエチルベンゼン燃焼率とは反応層に供給されたスチレンとエチルベンゼンのモル数に対して燃焼反応で消失したスチレンとエチルベンゼンのモル数の比率を示すものである。
【００２５】
【表１】
実施例１
（触媒調製）
氷水で５℃以下に冷却したイオン交換水２Ｌにチタンイソプロポキシド５００ｍｌを攪拌しながら徐々に加え水酸化物を生成した。生成した水酸化チタンの沈澱物を濾別し、イオン交換水で洗浄した後、乾燥器中で１２０℃で一晩乾燥した。乾燥品に少量のイオン交換水を加え３時間擂潰後、直径３ｍｍのペレットに押し出し成型した。成型品は、乾燥器中１２０℃で１晩乾燥し、更に、マッフル炉にて１２００℃で３時間焼成した。
【００２７】
得られた酸化チタンを砕いて０．８５〜１．０ｍｍ粒径とし、これに０．４重量％相当量の塩化白金酸の水溶液を均一に添加してロータリーエバポレーターにて６０℃で減圧乾燥した。乾燥品は、乾燥器にて１２０℃で１晩乾燥後、マッフル炉中６５０℃で３時間焼成して０．４重量％Ｐｔ／ＴｉＯ2触媒を得た。
【００２８】
（反応）
上記のようにして調製した触媒１ｍｌを上下に触媒と略同粒径の石英チップを充填した内径約７ｍｍの石英製反応管に充填した後、水素と窒素の混合ガス流通下５００℃で１時間還元処理を施した。還元処理後同雰囲気下所望の温度に触媒層温度を変化させてから窒素ガスで反応器系内を置換した。次いで、スチレン、エチルベンゼン、水、水素及び空気混合ガスを反応管に導入して、比較例１と同様にして反応、評価を行った。結果を表２に示す。
【００２９】
【表２】
実施例２
（触媒調製）
塩基性水酸化ニオブ（ＮｂＯ（ＯＨ）3）１００ｇに少量のイオン交換水を加え１時間擂潰後、直径３ｍｍのペレットに押し出し成型した。成型品は、乾燥器中１２０℃で１晩乾燥し、更にマッフル炉にて１０００℃で３時間焼成した。
【００３１】
得られた酸化ニオブ成型体を砕いて０．８５〜１．０ｍｍ粒径とし、これにＰｔとして０．４重量％相当量の塩化白金酸の水溶液を均一に添加してロータリーエバポレーターにて６０℃で減圧乾燥した。乾燥品は、乾燥器にて１２０℃で１晩乾燥後、マッフル炉中６５０℃で３時間焼成して０．４重量％Ｐｔ／Ｎｂ2Ｏ5触媒を得た。
【００３２】
（反応）
上記のようにして調製した触媒１ｍｌを上下に触媒と略同粒径の石英チップを充填した内径約７ｍｍの石英製反応管に充填した後、水素と窒素の混合ガス流通下５００℃で１時間還元処理を施した。還元処理後同雰囲気下所望の温度に触媒層温度を変化させてから窒素ガスで反応器系内を置換した。次いで、スチレン、エチルベンゼン、水、水素及び空気混合ガスを反応管に導入して比較例１と同様にして反応、評価を行った。結果を表３に示す。
【００３３】
【表３】
実施例３
（触媒調製）
酸化タンタル（Ｔａ2Ｏ5）１００ｇに少量のイオン交換水を加え１時間擂潰後、直径３ｍｍのペレットに押し出し成型した。成型品は、乾燥器中１２０℃で１晩乾燥し、更にマッフル炉にて１０００℃で３時間焼成した。得られた酸化タンタル成型体を砕いて０．８５〜１．０ｍｍ粒径とし、これにＰｔとして０．４重量％相当量の塩化白金酸の水溶液を均一に添加してロータリーエバポレーターにて６０℃で減圧乾燥した。乾燥品は、乾燥器にて１２０℃で１晩乾燥後、マッフル炉中６５０℃で３時間焼成して０．４重量％Ｐｔ／Ｔａ2Ｏ5触媒を得た。
【００３５】
（反応）
上記のようにして調製した触媒１ｍｌを上下に触媒と略同粒径の石英チップを充填した内径約７ｍｍの石英製反応管に充填した後、水素と窒素の混合ガス流通下５００℃で１時間還元処理を施した。還元処理後同雰囲気下所望の温度に触媒層温度を変化させてから窒素ガスで反応器系内を置換した。次いで、スチレン、エチルベンゼン、水、水素及び空気混合ガスを反応管に導入して、参考例１と同様にして反応、評価を行った。結果を表４に示す。
【００３６】
【表４】
【発明の効果】
上記実施例に示されるように、本発明の方法により、水素を選択的に酸化することができ、共存する炭化水素類の燃焼による消失を実質上問題の無いレベルに低く押えることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for selectively oxidizing hydrogen present in a mixed gas produced when a hydrocarbon is dehydrogenated to produce a dehydrogenated hydrocarbon, and a catalyst used therefor.
[0002]
[Prior art]
Processes for producing hydrocarbons by dehydrogenating hydrocarbons have been described in many documents. For example, a process for synthesizing styrene by dehydrogenating ethylbenzene is industrially carried out using an iron-based catalyst. However, in general, in the dehydrogenation reaction, a high yield cannot be obtained due to strong constraints on equilibrium. Further, in the reaction in the adiabatic reactor, since the dehydrogenation reaction is an endothermic reaction, the reaction temperature decreases with the reaction, and it is difficult to obtain the target product with a high yield.
[0003]
Under such circumstances, several methods have already been proposed. For example, British Patent 1,404,641 discloses a process and catalyst for selectively oxidizing hydrogen in a mixed gas containing unreacted ethylbenzene, styrene and hydrogen after dehydrogenating ethylbenzene. Yes. This method is an effective method for synthesizing styrene, but uses A-type zeolite or alumina carrying platinum as a selective hydrogen oxidation catalyst, and its performance is not always satisfactory.
[0004]
US Pat. No. 4,565,898 also discloses a method of using a catalyst in which platinum, tin, lithium and the like are supported on alumina by the same process. However, this catalyst is also supported on alumina, and its performance cannot be said to be sufficient. JP-A-58-89945 and JP-A-6-298678 describe the formation of hydrogen in a mixed gas containing styrene, ethylbenzene and hydrogen produced by dehydrogenation of ethylbenzene as tin oxide or tin oxide. And a method of selectively oxidizing using a catalyst containing an alkali metal. These are noted as catalysts that do not use platinum, but their performance is not necessarily sufficient.
[0005]
[Problems to be solved by the invention]
As described above, as a catalyst for selectively oxidizing unreacted hydrocarbons, dehydrogenated hydrocarbons, and hydrogen in a mixed gas containing hydrogen produced by a hydrocarbon dehydrogenation reaction, What is conventionally known is not satisfactory in terms of performance. Accordingly, an object of the present invention is to provide a novel catalyst for more selectively oxidizing hydrogen present in the mixed gas.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that a catalyst containing a component in which platinum or palladium is supported on a specific oxide support performs selective oxidation of hydrogen with high performance. The invention has been completed. That is, the first gist of the present invention is a catalyst for selectively oxidizing hydrogen in a mixed gas by bringing a mixed gas containing hydrogen and a hydrocarbon into contact with an oxygen-containing gas, A selective hydrogen oxidation catalyst comprising a component in which platinum and / or palladium is supported on one or more supports selected from the group consisting of titanium oxide, tantalum oxide and niobium oxide.
[0007]
The second gist of the present invention is a method in which a mixed gas containing hydrocarbon and hydrogen is brought into contact with an oxygen-containing gas in the presence of an oxidation catalyst to selectively oxidize hydrogen in the mixed gas. In addition, a hydrogen containing a component in which platinum and / or palladium is supported on any one or more carriers selected from the group consisting of titanium oxide, tantalum oxide, and niobium oxide is used as the oxidation catalyst. In the selective oxidation method.
[0008]
Furthermore, the third gist of the present invention contains dehydrogenated hydrocarbons, unreacted raw material hydrocarbons, and hydrogen obtained by dehydrogenating a raw material hydrocarbon in the presence of a dehydrogenation catalyst. A hydrocarbon in which the mixed gas is brought into contact with an oxygen-containing gas in the presence of an oxidation catalyst, hydrogen in the mixed gas is selectively oxidized, and the hydrocarbon-containing gas obtained by the oxidation reaction is further dehydrogenated. In this dehydrogenation method, a catalyst containing a component in which platinum and / or palladium is supported on any one or more carriers selected from the group consisting of titanium oxide, tantalum oxide and niobium oxide is used as the oxidation catalyst. The hydrocarbon dehydrogenation method is characterized by the following.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The selective hydrogen oxidation catalyst used in the method of the present invention is a catalyst containing titanium oxide, tantalum oxide or niobium oxide supporting platinum and / or palladium. The oxide carrier used in the present invention can be produced by an appropriate method usually used for producing a catalyst. For example, an aqueous alkaline solution such as aqueous ammonia, alkali carbonate, alkali bicarbonate or the like is added to an aqueous solution of titanium, tantalum or niobium salt while stirring, or water is added to an organic salt solution of titanium, tantalum or niobium while stirring. An oxide precipitate is formed, and the precipitate is filtered and washed. The hydroxide is dried and calcined at an appropriate temperature to form an oxide, for example, 200-1500 ° C. The oxide thus prepared is used after being tableted or extruded as necessary. The raw material salt of titanium, tantalum or niobium is not particularly limited, and chlorides, nitrates, sulfates, organic salts and hydroxides thereof can be used. It is also possible to prepare a catalyst support in the form of an oxide by directly calcining these salts.
[0010]
As a method of supporting platinum and / or palladium on these oxide carriers, the oxide after firing is impregnated with an aqueous solution of platinum and / or palladium salt, and this is dried and fired at a temperature of 50 to 1000 ° C. A method is mentioned. The raw material salt of platinum and / or palladium is not particularly limited, and halides, hydroxides, sulfates, organic salts and the like thereof can be used.
[0011]
The supported amount of platinum and / or palladium is 0.01 to 10% by weight, preferably 0.05 to 5% by weight, based on the carrier oxide. If the supported amount is too small, the activity of the oxidation reaction may be reduced, and even if the supported amount is increased further, the reaction characteristics are hardly affected, which is disadvantageous in terms of cost.
[0012]
The oxidation catalyst of the present invention is used for a reaction in which a mixed gas containing hydrogen and hydrocarbon is brought into contact with an oxygen-containing gas to selectively oxidize hydrogen in the mixed gas. The reaction is preferably performed at 300 to 800 ° C, more preferably in the temperature range of 400 to 700 ° C. If the temperature is too high, the hydrogen selectivity decreases and the combustion of hydrocarbons increases, which is not preferable. If the temperature is too low, the selectivity is not greatly affected, but the activity may be lowered, which is not preferable.
[0013]
As a specific example of the mixed gas containing hydrogen and hydrocarbon, a mixed gas composed of dehydrogenated hydrocarbon, unreacted raw material hydrocarbon and hydrogen obtained by dehydrogenating raw material hydrocarbon with a dehydrogenation catalyst Is mentioned. As the oxygen-containing gas, a gas containing 1 to 100% of molecular oxygen is used. Specifically, air, oxygen-enriched air, air diluted with an inert gas, or the like is preferably used. Further, water vapor can be contained in the oxygen-containing gas.
[0014]
A typical process to which the selective oxidation catalyst and the selective oxidation method of the present invention are applied is as follows. After performing the dehydrogenation reaction of the raw material hydrocarbon by the dehydrogenation catalyst in the first stage reactor, the mixed gas containing the dehydrogenated hydrocarbon, the unreacted raw material hydrocarbon and the hydrogen coming out of the first stage reaction layer is To the second stage reaction layer. In this second stage reaction layer, hydrogen is selectively oxidized using the newly introduced oxygen-containing gas in the presence of the selective oxidation catalyst of the present invention. As a result, the temperature lowered by the dehydrogenation reaction, which is an endothermic reaction in the first stage, is increased, and the equilibrium restriction of the dehydrogenation reaction is removed by consuming hydrogen. Further, the gas coming out of the second-stage reaction layer is sent to a third-stage dehydrogenation reaction layer similar to the first-stage reaction layer, and unreacted hydrocarbons are dehydrogenated. Since the temperature necessary for the reaction has already been recovered in the second stage reaction layer and the equilibrium restriction has been released, a higher yield can be obtained in the third stage dehydrogenation reaction layer.
[0015]
If necessary, the reaction can be carried out by further adding a combination of the selective oxidation reaction layer and the dehydrogenation reaction layer. In general, hydrogen gas often coexists in the dehydrogenation reaction, but water vapor can coexist in the reaction process.
[0016]
A typical example of the dehydrogenation process is a dehydrogenation process of ethylbenzene. For example, a mixed gas of ethylbenzene and water vapor is sent to the first stage reaction layer in which an iron-based catalyst containing iron and alkali metal as main active components is present, and the temperature is in the range of 500 ° C. to 800 ° C., in the range of 0.05 to 10 atm. The dehydrogenation reaction is performed at a pressure of. Thereafter, a mixed gas of unreacted ethylbenzene, generated styrene, hydrogen and water vapor is sent to the second stage reaction layer. In the second-stage reaction layer, hydrogen is selectively oxidized using the oxygen-containing gas newly introduced in the presence of the oxidation catalyst of the present invention. Next, this reaction gas is sent to the third stage reaction layer, where unreacted ethylbenzene is dehydrogenated again with an iron-based catalyst to obtain styrene in a higher yield.
As described above, when the method of the present invention is used, the equilibrium constraint is removed and the decrease in the reaction temperature can be compensated, so that the yield is much higher than that in the normal dehydrogenation reaction. Styrene can be obtained.
[0018]
【Example】
The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples.
[0019]
Comparative Example 1
(Catalyst preparation)
Immerse alumina oxide (α-Al 2 O 3 ) having a particle size of 0.85 to 1.0 mm in 2 g of chloroplatinic acid (H 2 PtCl 6 .6H 2 O) aqueous solution containing 0.0021 g as platinum. Then, it was made to dry under reduced pressure of 60 degreeC with a rotary evaporator. The dried product was dried overnight at 120 ° C. in a drier, then placed in a muffle furnace and baked at 650 ° C. for 3 hours. In this way, a platinum-supported alumina oxide catalyst containing 0.4% by weight of platinum was obtained.
[0020]
1 ml of the catalyst prepared as described above was packed in a quartz reaction tube having an inner diameter of 6.7 mm. After filling the upper part with a quartz chip, the temperature was raised to 500 ° C. and kept for 1 hour while flowing hydrogen gas through the reaction tube at a flow rate of about 50 ml / min, and a catalytic reduction treatment was performed.
[0021]
(Reaction) Next, after switching the hydrogen to nitrogen and sufficiently replacing the inside of the reaction system with nitrogen, styrene (hereinafter sometimes referred to as SM), ethylbenzene (hereinafter sometimes referred to as EB), water, hydrogen and air mixed gas Was introduced into the reaction tube to initiate the reaction. The mixed gas composition and the space velocity in the reactor were as follows.
[0022]
[Expression 1]
[Expression 2]
Two hours after the start of the reaction, the gas at the outlet of the reaction tube and the liquid trapped in the liquid receiver were analyzed with a gas chromatograph to calculate the hydrogen conversion rate, oxygen conversion rate, styrene and ethylbenzene combustion rate. The results are shown in Table 1. Here, the styrene and ethylbenzene combustion rate indicates the ratio of the number of moles of styrene and ethylbenzene lost in the combustion reaction to the number of moles of styrene and ethylbenzene supplied to the reaction layer.
[0025]
[Table 1]
Example 1
(Catalyst preparation)
To 2 L of ion-exchanged water cooled to 5 ° C. or lower with ice water, 500 ml of titanium isopropoxide was gradually added with stirring to form a hydroxide. The resulting titanium hydroxide precipitate was filtered off, washed with ion exchanged water, and dried overnight at 120 ° C. in a drier. A small amount of ion-exchanged water was added to the dried product and crushed for 3 hours, and then extruded into a 3 mm diameter pellet. The molded product was dried overnight at 120 ° C. in a dryer, and further calcined at 1200 ° C. for 3 hours in a muffle furnace.
[0027]
The obtained titanium oxide was crushed to a particle diameter of 0.85 to 1.0 mm, and an aqueous solution of 0.4% by weight of chloroplatinic acid was uniformly added thereto and dried under reduced pressure at 60 ° C. with a rotary evaporator. . The dried product was dried overnight at 120 ° C. in a drier and then calcined at 650 ° C. for 3 hours in a muffle furnace to obtain a 0.4 wt% Pt / TiO 2 catalyst.
[0028]
(reaction)
After filling 1 ml of the catalyst prepared as described above into a quartz reaction tube having an inner diameter of about 7 mm filled with a quartz chip having the same particle size as that of the catalyst, the mixture is mixed and mixed with hydrogen and nitrogen at 500 ° C. for 1 hour. A reduction treatment was performed. After the reduction treatment, the temperature of the catalyst layer was changed to the desired temperature under the same atmosphere, and the inside of the reactor system was replaced with nitrogen gas. Subsequently, styrene, ethylbenzene, water, hydrogen and air mixed gas were introduced into the reaction tube, and the reaction and evaluation were performed in the same manner as in Comparative Example 1. The results are shown in Table 2.
[0029]
[Table 2]
Example 2
(Catalyst preparation)
A small amount of ion-exchanged water was added to 100 g of basic niobium hydroxide (NbO (OH) 3 ), and the mixture was crushed for 1 hour, and then extruded into a 3 mm diameter pellet. The molded product was dried overnight at 120 ° C. in a dryer and further baked at 1000 ° C. for 3 hours in a muffle furnace.
[0031]
The obtained niobium oxide molded body was crushed to a particle diameter of 0.85 to 1.0 mm, and an aqueous solution of chloroplatinic acid equivalent to 0.4% by weight as Pt was uniformly added thereto, and a rotary evaporator was used at 60 ° C. And dried under reduced pressure. The dried product was dried overnight at 120 ° C. in a drier and then calcined at 650 ° C. for 3 hours in a muffle furnace to obtain a 0.4 wt% Pt / Nb 2 O 5 catalyst.
[0032]
(reaction)
1 ml of the catalyst prepared as described above was filled in a quartz reaction tube having an inner diameter of about 7 mm filled with quartz chips of approximately the same particle size as the catalyst, and then at 500 ° C. for 1 hour under a mixed gas flow of hydrogen and nitrogen. A reduction treatment was performed. After the reduction treatment, the temperature of the catalyst layer was changed to the desired temperature under the same atmosphere, and the inside of the reactor system was replaced with nitrogen gas. Subsequently, styrene, ethylbenzene, water, hydrogen and air mixed gas were introduced into the reaction tube, and the reaction and evaluation were performed in the same manner as in Comparative Example 1. The results are shown in Table 3.
[0033]
[Table 3]
Example 3
(Catalyst preparation)
A small amount of ion exchange water was added to 100 g of tantalum oxide (Ta 2 O 5 ), and the mixture was crushed for 1 hour, and then extruded into a 3 mm diameter pellet. The molded product was dried overnight at 120 ° C. in a dryer and further baked at 1000 ° C. for 3 hours in a muffle furnace. The obtained tantalum oxide molded body was crushed to a particle diameter of 0.85 to 1.0 mm, and an aqueous solution of chloroplatinic acid equivalent to 0.4% by weight as Pt was uniformly added thereto, followed by 60 ° C. using a rotary evaporator. And dried under reduced pressure. The dried product was dried overnight at 120 ° C. in a drier and then calcined at 650 ° C. for 3 hours in a muffle furnace to obtain a 0.4 wt% Pt / Ta 2 O 5 catalyst.
[0035]
(reaction)
1 ml of the catalyst prepared as described above was filled in a quartz reaction tube having an inner diameter of about 7 mm filled with quartz chips of approximately the same particle size as the catalyst, and then at 500 ° C. for 1 hour under a mixed gas flow of hydrogen and nitrogen. A reduction treatment was performed. After the reduction treatment, the temperature of the catalyst layer was changed to the desired temperature under the same atmosphere, and the inside of the reactor system was replaced with nitrogen gas. Subsequently, styrene, ethylbenzene, water, hydrogen and air mixed gas were introduced into the reaction tube, and the reaction and evaluation were performed in the same manner as in Reference Example 1. The results are shown in Table 4.
[0036]
[Table 4]
【The invention's effect】
As shown in the above embodiments, hydrogen can be selectively oxidized by the method of the present invention, and the disappearance of the coexisting hydrocarbons due to combustion can be suppressed to a level at which there is substantially no problem.
Claims (9)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP04592196A JP3831444B2 (en) | 1995-03-08 | 1996-03-04 | Hydrogen selective oxidation catalyst, hydrogen selective oxidation method, and hydrocarbon dehydrogenation method |
Applications Claiming Priority (11)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4874095 | 1995-03-08 | ||
| JP6985595 | 1995-03-28 | ||
| JP11705595 | 1995-05-16 | ||
| JP7-117055 | 1995-05-16 | ||
| JP7-69855 | 1995-05-16 | ||
| JP7-117053 | 1995-05-16 | ||
| JP7-117054 | 1995-05-16 | ||
| JP11705495 | 1995-05-16 | ||
| JP7-48740 | 1995-05-16 | ||
| JP11705395 | 1995-05-16 | ||
| JP04592196A JP3831444B2 (en) | 1995-03-08 | 1996-03-04 | Hydrogen selective oxidation catalyst, hydrogen selective oxidation method, and hydrocarbon dehydrogenation method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0929095A JPH0929095A (en) | 1997-02-04 |
| JP3831444B2 true JP3831444B2 (en) | 2006-10-11 |
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| KR100500182B1 (en) * | 1997-07-17 | 2005-07-12 | 미쓰비시 가가꾸 가부시키가이샤 | Process for producing styrene |
| KR100435438B1 (en) * | 1999-12-23 | 2004-06-10 | 주식회사 포스코 | Palladium-platinum/titania catalyst and a method for removing hydrocarbon by using the catalyst |
| KR100670015B1 (en) * | 2005-05-25 | 2007-01-16 | 동양제철화학 주식회사 | Pd-nb catalyst for hydrogenation of 2,4-dinitrotoluene and its preparing method |
| WO2006132370A1 (en) | 2005-06-10 | 2006-12-14 | Mitsubishi Chemical Corporation | Process for production of styrene |
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