JP2020044485A - Reaction method and reactor - Google Patents

Reaction method and reactor Download PDF

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JP2020044485A
JP2020044485A JP2018173652A JP2018173652A JP2020044485A JP 2020044485 A JP2020044485 A JP 2020044485A JP 2018173652 A JP2018173652 A JP 2018173652A JP 2018173652 A JP2018173652 A JP 2018173652A JP 2020044485 A JP2020044485 A JP 2020044485A
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reaction
reaction zone
reactor
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由治 嶋崎
Yoshiharu Shimazaki
由治 嶋崎
準 仙頭
Jun Sento
準 仙頭
敏勝 池之上
Toshikatsu Ikenoue
敏勝 池之上
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Nippon Shokubai Co Ltd
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Abstract

To provide, in a process where an unsaturated hydrocarbon and/or an unsaturated aldehyde as a raw material compound is subjected to a vapor phase contact oxidation reaction using a catalyst, a reactor, the structure of which can be simplified, and a reaction method capable of improving productivity by using the reactor.SOLUTION: The reaction method comprises: using, as a reactor, a fixed bed reactor with a heat transfer system suitable for each of the first half and the last half of a catalyst layer; making the reaction proceed in a tubular heat transfer fixed bed reactor until conversion of the raw material compound becomes 30% or more and less than 80%; and subsequently introducing a fluid containing the raw material compound and a reaction product into a fixed bed reactor which does not perform heat exchange to further convert the raw material compound.SELECTED DRAWING: Figure 1-a

Description

本発明は、触媒を充填した反応器に原料化合物を含有する原料流体を供給して気相接触酸化させる反応において、異なる伝熱方式の固定床反応器様式の反応帯を有する反応器を用いて反応させる方法に関する。また本発明は、気相接触酸化反応に用いる、異なる伝熱方式の固定床反応器様式の反応帯を有する反応器に関する。   The present invention uses a reactor having a reaction zone of a fixed-bed reactor type with a different heat transfer system in a reaction in which a raw material fluid containing a raw material compound is supplied to a reactor filled with a catalyst to perform gas phase catalytic oxidation. It relates to a method of reacting. The present invention also relates to a reactor having a fixed-bed reactor type reaction zone of a different heat transfer system used for a gas phase catalytic oxidation reaction.

不飽和炭化水素の気相接触酸化は大きな発熱を伴う反応であり、工業的に実施されている反応として、例えば、エチレンの酸化によるエチレンオキサイドの製造、プロピレンの酸化によるアクロレインおよび／またはアクリル酸の製造、イソブチレンの酸化によるメタクロレインおよび／またはメタクリル酸の製造、ベンゼンの酸化による無水マレイン酸の製造などが挙げられる。   The gas phase catalytic oxidation of unsaturated hydrocarbons is a reaction that generates a large amount of heat, and reactions that are industrially carried out include, for example, production of ethylene oxide by oxidation of ethylene, acrolein and / or acrylic acid by oxidation of propylene. Production, production of methacrolein and / or methacrylic acid by oxidation of isobutylene, production of maleic anhydride by oxidation of benzene, and the like.

これらの反応には、一般に、多管式熱交換型固定床反応器が用いられ、その構造は固体触媒が充填された内径２０〜５０ｍｍ、長さ１〜２０ｍの反応管を熱媒体と接触させることによって反応に係る熱の除去あるいは供給をおこなう仕組みとなっている。通常、多管式熱交換型固定床反応器の熱媒体は、反応管と接触する全域で可能な限り均一な温度になるように設計されているが、そのような反応器を用いて気相接触酸化を行なうと、反応原料が供給される反応管入口（以下、「触媒層入口」ともいう）付近では反応原料濃度が高いため触媒への負荷が大きく、反応の進行に伴って反応管出口に向かって反応原料濃度が低下するため触媒への負荷が相対的に小さくなり、結果として反応管入口から出口にかけて触媒の劣化度合いに大きな偏りが生じ、所望の反応成績を維持できなくなる時期が早まる場合がある。例えば、気相接触酸化のような発熱反応の場合は反応管入口付近の除熱が不充分となり、触媒層に局所的異常高温部が発生し、副反応の増加を招くばかりでなく触媒の損傷や反応の暴走を招く危険性もある。   For these reactions, generally, a multitubular heat exchange fixed bed reactor is used, and the structure thereof is such that a reaction tube having an inner diameter of 20 to 50 mm and a length of 1 to 20 m filled with a solid catalyst is brought into contact with a heat medium. This removes or supplies heat related to the reaction. Usually, the heating medium in a shell-and-tube heat-exchange fixed-bed reactor is designed to have a temperature that is as uniform as possible over the entire area in contact with the reaction tube. When the catalytic oxidation is performed, the load on the catalyst is large due to the high concentration of the reactant near the inlet of the reaction tube to which the reactant is supplied (hereinafter, also referred to as “catalyst layer inlet”). As the reaction raw material concentration decreases, the load on the catalyst becomes relatively small, and as a result, the degree of deterioration of the catalyst is greatly biased from the inlet to the outlet of the reaction tube, and the time at which a desired reaction result cannot be maintained is advanced. There are cases. For example, in the case of an exothermic reaction such as gas-phase catalytic oxidation, heat removal near the inlet of the reaction tube becomes insufficient, and a local abnormal high temperature portion is generated in the catalyst layer, which not only causes an increase in side reactions but also damages the catalyst. And there is a danger of runaway reaction.

このような触媒層入口付近で起こる不都合に対して、種々の解決策が提案されている。例えば、反応に不活性な物質と混合希釈した触媒あるいは触媒活性を抑えた触媒を反応管入口付近に充填して反応管入口付近の反応割合を抑制する方法（特許文献１、特許文献２）、反応管の全長の温度特性を制御するために反応管入口から出口に向けて反応管の内径を段階的に減少して反応管入口付近での反応割合を最適にする方法（特許文献３、特許文献４）、反応管の軸中心部に金属棒を設置して局所的異常高温部の発生を防ぐ方法（特許文献５）、反応管内部に、端部および／または途中から他方の端部に向けて連続的、不連続的および／または段階的に体積が減少する形状を有する反応管用充填物を触媒と共に用いる方法（特許文献６）などが開示されている。   Various solutions have been proposed for such inconvenience occurring near the entrance of the catalyst layer. For example, a method in which a catalyst mixed and diluted with a substance inert to the reaction or a catalyst with reduced catalytic activity is filled near the inlet of the reaction tube to suppress the reaction rate near the inlet of the reaction tube (Patent Documents 1 and 2), A method of optimizing the reaction rate near the inlet of a reaction tube by gradually reducing the inner diameter of the reaction tube from the inlet to the outlet of the reaction tube in order to control the temperature characteristics of the entire length of the reaction tube (Patent Document 3, Patent Reference 4), a method of installing a metal rod at the center of the axis of a reaction tube to prevent the occurrence of a local abnormal high-temperature portion (Patent Document 5), inside the reaction tube, at one end and / or halfway to the other end There is disclosed a method of using a filler for a reaction tube having a shape in which the volume is reduced continuously, discontinuously, and / or stepwise together with a catalyst (Patent Document 6).

一方で、触媒層入口付近に加えて触媒層出口側の挙動にも着目してプロセスの最適化を図った例が見受けられる。   On the other hand, there is an example in which the process is optimized by paying attention to the behavior on the catalyst layer outlet side in addition to the vicinity of the catalyst layer inlet.

例えば、少なくとも２つ以上に区画された反応帯を有する管式熱交換型反応システムにおいて、原料ガス流路における最上流反応帯を含む少なくとも１つ以上の反応帯の反応管内部に、端部または途中から他方の端部に向けて連続的または段階的に体積が減少する形状を有する構造物を、反応管のガス出口方向に向かって該構造物の体積が減少する向きに設置することが開示されている。また、前記の少なくとも２つ以上に区画された反応帯は独立して温度制御され、原料濃度が高い反応性に富んだ前半部（上流側）と、原料濃度の低い反応性の鈍い後半部（下流側）において、別々の反応温度でコントロールすることが開示されている（特許文献７）。   For example, in a tubular heat exchange type reaction system having at least two or more reaction zones, at least one end portion or at least one or more reaction zones including the most upstream reaction zone in the raw material gas flow path are provided inside the reaction tubes. It discloses that a structure having a shape whose volume decreases continuously or stepwise from the middle toward the other end is installed in a direction in which the volume of the structure decreases toward the gas outlet direction of the reaction tube. Have been. Further, the reaction zone divided into at least two or more zones is independently temperature-controlled, and the first half (upstream side) where the raw material concentration is high and the reactive half is low (the lower half where the raw material concentration is low and the reactivity is low). On the downstream side), control at different reaction temperatures is disclosed (Patent Document 7).

さらに、反応の最後部においてプロセス最適化を図った例として、副生成物低減による品質向上を目的として、反応の最終段階に断熱あるいは断熱的に反応を行う工程を組み込んだ例が見受けられる。例えば、固体触媒によりプロピレンを酸化しアクロレインを経てアクリル酸を製造するプロセスにおいて、先ず主反応として、プロピレン転化率が９５モル％以上、アクリル酸選択率が９０モル％以上、副成分形成の全選択率が１．７モル％以上となるように製造し、次いで後反応段階において前工程で得られた生成ガス混合物の温度を高めて触媒装入物に導通させることでアクリル酸が実質的に未変換のまま副成分形成の全選択率が１．５モル％以下とする方法が開示されている。この後反応段階は断熱操作されうることが開示されている。（特許文献８）。   Further, as an example of optimizing the process at the end of the reaction, there is an example in which a step of adiabatically or adiabatically conducting the reaction is incorporated in the final stage of the reaction for the purpose of improving the quality by reducing by-products. For example, in a process in which propylene is oxidized with a solid catalyst to produce acrylic acid via acrolein, first, as a main reaction, a propylene conversion rate is 95 mol% or more, an acrylic acid selectivity is 90 mol% or more, and a total selection of subcomponent formation is performed. Rate is at least 1.7 mol%, and then, in a post-reaction stage, the temperature of the product gas mixture obtained in the preceding step is increased to conduct the catalyst gas to substantially eliminate acrylic acid. A method is disclosed in which the total selectivity for forming the sub-components is 1.5 mol% or less without conversion. It is disclosed that the subsequent reaction step can be adiabatically operated. (Patent Document 8).

ｏ−キシロールを酸化して無水フタル酸を製造するプロセスにおいても、ｏ−キシロールと酸素含有ガスとのガス状混合物を主要反応器中で反応させ、未反応のｏ−キシロール、無水フタル酸酸化不足生成物および無水フタル酸を含有するガス状の中間体反応生成物を生じさせ、前記中間体反応生成物を伝熱媒体の最も低い温度より低い温度で後方反応器中に導入する方法が開示されている。その際、それぞれ中間体反応生成物中の有機成分の全質量に対して、中間体反応生成物中の未反応のｏ−キシロールの濃度が少なくとも１質量％であり、中間体反応生成物中の無水フタル酸酸化不足生成物の濃度の総和が少なくとも０．５質量％であり、後方反応器は本質的に断熱的に運転されることも開示されている（特許文献９）。   Also in the process of oxidizing o-xylol to produce phthalic anhydride, a gaseous mixture of o-xylol and an oxygen-containing gas is reacted in a main reactor, and unreacted o-xylol and phthalic anhydride deficiency are oxidized. A method is disclosed for producing a gaseous intermediate reaction product containing the product and phthalic anhydride, and introducing the intermediate reaction product into a rear reactor at a temperature lower than the lowest temperature of the heat transfer medium. ing. At this time, the concentration of unreacted o-xylol in the intermediate reaction product is at least 1% by mass, based on the total mass of the organic components in the intermediate reaction product, and It is also disclosed that the sum of the concentrations of the phthalic anhydride underoxidation underproducts is at least 0.5% by weight and that the downstream reactor is operated essentially adiabatically (US Pat. No. 5,049,059).

前記の無水フタル酸製造プロセスに類似する芳香族化合物を気相接触酸化して酸無水物を製造するプロセスにおいても、多管式固定床反応器を必須とする反応装置により芳香族化合物を含む原料を接触気相酸化する工程を含む酸無水物の製造方法が開示されている。ここで、前記多管式固定床反応器を必須とする反応装置は、温度制御されてなり、かつ原料の９０％以上が消費される第１の触媒層と、前記第１の触媒層の後に第２の触媒層とを有するものであり、前記第２の触媒層は、導入ガスの温度が前記第１の触媒層における制御温度の９５％以上の温度であり、かつ充填される触媒の活性が前記第１の触媒層における最後部の触媒の活性より小さいものであることが開示されている。さらに、前記第２の触媒層は前記第１の触媒層がある反応管の後部でかつ断熱された空間部に設置されることも開示されている（特許文献１０）。   In the process of producing an acid anhydride by subjecting an aromatic compound similar to the phthalic anhydride production process to gas phase catalytic oxidation, a raw material containing the aromatic compound is obtained by a reaction apparatus including a multitubular fixed-bed reactor. Discloses a method for producing an acid anhydride, which comprises a step of subjecting a compound to catalytic gas phase oxidation. Here, the reactor which essentially requires the multitubular fixed-bed reactor is temperature-controlled, and has a first catalyst layer in which 90% or more of the raw material is consumed, and a first catalyst layer after the first catalyst layer. A second catalyst layer, wherein the temperature of the introduced gas is 95% or more of the control temperature of the first catalyst layer, and the activity of the charged catalyst is Is smaller than the activity of the last catalyst in the first catalyst layer. Furthermore, it is also disclosed that the second catalyst layer is installed in a rear part of a reaction tube where the first catalyst layer is located and in an insulated space (Patent Document 10).

反応管内の熱の偏在だけでなく、多管式熱交換型固定床反応器においてはシェル内部を循環する熱媒体についても熱の偏在が発生する。例えば、多管式熱交換型固定床反応器の触媒が充填された反応管に原料流体を導入し発熱反応を行う場合、発熱量が原料流体入口側に偏在するため、シェル内の上下で温度差が発生することは避けられない。つまり、熱媒体の制御温度と実際の温度とは相違する部分が発生している。そこで、熱媒体の流れを発熱量が異なる領域ごとに分割し独立制御することで、全ての領域にわたって所定の反応温度に維持することが可能になることが開示されている（特許文献１１）。   Not only the uneven distribution of heat in the reaction tube, but also the uneven distribution of heat occurs in the heat medium circulating inside the shell in the multi-tube heat exchange type fixed bed reactor. For example, when a raw material fluid is introduced into a reaction tube filled with a catalyst of a multitubular heat exchange type fixed bed reactor and an exothermic reaction is performed, the calorific value is unevenly distributed on the raw material fluid inlet side, and thus the temperature is increased and lowered in the shell. Differences are inevitable. That is, there is a portion where the control temperature of the heat medium is different from the actual temperature. Therefore, it has been disclosed that by dividing the flow of the heat medium into regions having different calorific values and performing independent control, it is possible to maintain a predetermined reaction temperature over all regions (Patent Document 11).

以上のように、触媒を用いて不飽和炭化水素を気相接触酸化し対応するアルデヒドおよび／またはカルボン酸を製造するプロセスにおいては、通常は多管式熱交換型固定床反応器が用いられている。このようなプロセスにおいて、反応器内での原料濃度の高い触媒層入口付近では、局所的異常高温部が発生することで、副生成物の増加や触媒の損傷だけでなく、暴走反応を起こす懸念がある。このような触媒層入口付近の不都合を解消するために上記のような種々の解決策が提案されているが、一方で、触媒層の局所的異常高温部を過ぎた反応の後半部については発熱が少ないため、この領域における反応の最適化については特段の注意が払われることは少なかった。   As described above, in a process for producing a corresponding aldehyde and / or carboxylic acid by subjecting an unsaturated hydrocarbon to gas-phase catalytic oxidation using a catalyst, a multitubular heat exchange fixed-bed reactor is usually used. I have. In such a process, local abnormally high temperature is generated near the entrance of the catalyst layer where the raw material concentration is high in the reactor, which may cause not only an increase in by-products and damage to the catalyst, but also a runaway reaction. There is. Various solutions as described above have been proposed in order to eliminate such inconvenience near the catalyst layer inlet, but on the other hand, heat is generated in the latter half of the reaction after the local abnormal high temperature part of the catalyst layer. Due to the small number of neutrons, little attention was paid to the optimization of the reaction in this region.

反応後半部における反応を最適化する方策として、例えば、上記特許文献７などに開示されているように、管式熱交換型反応システムにおいて、少なくとも２つ以上に反応帯を区画したうえで、後半部（下流側）の温度を前半部（上流側）と独立して制御する技術が挙げられる。しかしこの場合は、発熱が少ない後半部においても構造が複雑で製作費用がかかる管式熱交換型固定床反応器を用いる必要があるか検討の余地がある。また、特許文献８などのように、反応の最後部において副生成物を減ずることを目的として、断熱的に反応を行う技術も挙げられる。この場合、最後部では反応による発熱が少ないという理由から断熱的に反応を行うことは合理的ではあるが、最後部より以前の領域で既に原料の転化率は相当高い水準にまで達しているのであるから、この最後部において僅かな原料転化率の上昇を伴いながら副生成物を減ずるためだけに相当量の触媒を使用することは反応器空間の有効利用という点で課題が残る。さらに、特許文献１１のような多管式熱交換型固定床反応器において発熱量が異なる領域ごとに分割して熱媒体の流れを制御する方法では、そのための付帯設備がそれぞれの領域ごとに必要となるため、反応器が大型化すると共にその建設費用も莫大になるという問題があり、加えて、長期間の運転期間中に温度の異なる熱媒体が混合しないよう注意を払わなくてはならない。   As a measure for optimizing the reaction in the latter half of the reaction, for example, as disclosed in Patent Document 7, etc., in a tubular heat exchange reaction system, the reaction zone is divided into at least two or more, There is a technique for controlling the temperature of the section (downstream side) independently of the temperature in the first half (upstream side). However, in this case, there is room for examination as to whether it is necessary to use a tubular heat exchange type fixed bed reactor which has a complicated structure and requires a high production cost even in the latter half of the heat generation. In addition, as in Patent Literature 8, for example, there is a technique in which a reaction is performed adiabatically for the purpose of reducing by-products at the end of the reaction. In this case, it is reasonable to carry out the reaction adiabatically because the heat generated by the reaction is small in the last part, but since the conversion of the raw material has already reached a considerably high level in the region before the last part. Thus, the use of a considerable amount of catalyst only to reduce by-products with a slight increase in feed conversion at this end remains a challenge in terms of effective utilization of reactor space. Further, in the method of controlling the flow of the heat medium by dividing the heat generation amount into different regions in a multitubular heat exchange fixed bed reactor as disclosed in Patent Document 11, additional facilities for each region are required for each region. Therefore, there is a problem that the reactor becomes large and the construction cost becomes enormous, and in addition, care must be taken to prevent heat media having different temperatures from being mixed during a long operation period.

特公昭５３−３０６８８号公報JP-B-53-30688 特公昭６３−３８３３１号公報JP-B-63-38331 国際公開第０４／０５６４６３号パンフレットWO 04/056463 pamphlet 特開２０１３−１０７８７３号公報JP 2013-107873 A 特開平１１−８００５２号公報JP-A-11-80052 国際公開第２０１５／０６８６４０号パンフレットWO 2015/068640 pamphlet 特開２０１６−２０３１５０号公報JP-A-2006-203150 特表２００７−５３５５１１号公報Japanese Patent Publication No. 2007-535511 特表２００９−５３７５９３号公報Japanese Patent Publication No. 2009-535593 特開２００３−１２６６４号公報JP-A-2003-12664 特開２００５−２８８４４１号公報JP 2005-288441 A

本発明は、触媒を用いて不飽和炭化水素および／または不飽和アルデヒドを気相接触酸化するプロセスにおいて、触媒層入口付近で起こる上記の問題を解決して生産性が向上できる反応方法、および、当該プロセスに用いる固定床様式の反応器を提供する。   The present invention provides a reaction method capable of improving the productivity by solving the above-mentioned problems occurring near the entrance of a catalyst layer in a process for performing a gas phase catalytic oxidation of unsaturated hydrocarbons and / or unsaturated aldehydes using a catalyst, and A fixed bed reactor for the process is provided.

本発明者らは鋭意検討を重ねた結果、管式熱交換型固定床反応器を用いた気相接触酸化反応においては触媒層後半での発熱が相対的に少ないことに着目し、触媒層後半では熱媒体を使用した強制的な熱交換を省略して熱交換しない固定床反応器の様式とし、自己の反応熱で反応を自立させることを試みた結果、触媒層後半は断熱的に反応を進行させることができることを見出した。つまり、触媒層後半では熱媒体を使用しないので、前記のような多管式熱交換型固定床反応器に由来する問題は生じず、また、これまで多管式熱交換型固定床反応器を用いて発熱反応を行なわせる場合には発生した熱を除去するのが好ましいとされていたが、むしろ、特に触媒層後半では除熱を行わない方が好ましいことを見出した。さらに、触媒層後半の熱交換しない固定床反応器様式の反応帯に充填する触媒の活性を、触媒層前半の管式熱交換型固定床反応器様式の反応帯に充填する触媒の活性以上とすることで生産性を向上できることを見出し、本発明を完成した。   As a result of intensive studies, the present inventors have noticed that in the gas phase catalytic oxidation reaction using a tubular heat exchange fixed bed reactor, heat generation in the latter half of the catalyst layer is relatively small, and As a result, the fixed-bed reactor, which does not exchange heat by omitting the forced heat exchange using a heat medium, attempted to make the reaction self-sustaining by its own reaction heat. I found that I could make it go. That is, since the heat medium is not used in the latter half of the catalyst layer, the above-mentioned problems derived from the multitubular heat exchange fixed bed reactor do not occur. It has been considered that it is preferable to remove the generated heat when an exothermic reaction is performed by using the catalyst. However, it has been found that it is more preferable not to remove the heat particularly in the latter half of the catalyst layer. Furthermore, the activity of the catalyst packed in the reaction zone of the fixed bed reactor type without heat exchange in the latter half of the catalyst layer is higher than the activity of the catalyst packed in the reaction zone of the tubular heat exchange type fixed bed reactor type in the first half of the catalyst layer. The present inventors have found that the productivity can be improved by doing so, and completed the present invention.

すなわち本発明は、原料化合物としての不飽和炭化水素および／または不飽和アルデヒドを気相接触酸化させる反応方法において、１本以上の反応管を備える管式熱交換型固定床反応器様式の第１反応帯と熱交換しない固定床反応器様式の第２反応帯を有する反応器を使用し、前記第１反応帯に充填される触媒体積をＶ１、前記第２反応帯に充填される触媒体積をＶ２としたときに、Ｖ１／（Ｖ１＋Ｖ２）を０．３以上０．８以下とし、前記第１反応帯において原料化合物を３０％以上８０％未満の転化率で反応させ、得られた未反応原料化合物と反応生成物を含む流体を後続する前記第２反応帯に送り、前記第２反応帯において原料化合物をさらに転化させることを特徴とする反応方法である。また、前記第１反応帯中の反応管内部に、触媒層の局所的異常高温を抑制する機能を有する構造物が設置されており、前記第２反応帯に充填される触媒の活性が前記第１反応帯に充填される触媒の活性以上である反応方法である。さらに、前記気相接触酸化により前記原料化合物に対応するアルデヒドおよび／またはカルボン酸を得、前記原料化合物が、プロピレン、イソブチレン、アクロレインおよびメタクロレインから選ばれる少なくとも１つである反応方法である。   That is, the present invention provides a reaction method for subjecting an unsaturated hydrocarbon and / or an unsaturated aldehyde as a raw material compound to gas-phase catalytic oxidation, the first being a tubular heat exchange fixed bed reactor having one or more reaction tubes. Using a reactor having a second reaction zone of a fixed bed reactor type which does not exchange heat with the reaction zone, the volume of the catalyst charged in the first reaction zone is V1, and the volume of the catalyst charged in the second reaction zone is V1. When V2, V1 / (V1 + V2) is set to 0.3 or more and 0.8 or less, and the raw material compounds are reacted at a conversion of 30% or more and less than 80% in the first reaction zone. A reaction method wherein a fluid containing a compound and a reaction product is sent to the subsequent second reaction zone, and the raw material compound is further converted in the second reaction zone. In addition, a structure having a function of suppressing local abnormal high temperature of the catalyst layer is installed inside the reaction tube in the first reaction zone, and the activity of the catalyst filled in the second reaction zone is reduced by the second reaction zone. This is a reaction method in which the activity of the catalyst charged in one reaction zone is higher than that of the catalyst. Further, there is provided a reaction method wherein an aldehyde and / or a carboxylic acid corresponding to the raw material compound is obtained by the gas phase catalytic oxidation, and the raw material compound is at least one selected from propylene, isobutylene, acrolein and methacrolein.

以下、本発明をより具体的に示す。   Hereinafter, the present invention will be described more specifically.

（１）触媒を充填した反応器に原料化合物としての不飽和炭化水素および／または不飽和アルデヒドを含有する原料流体を供給して気相接触酸化させる反応方法であって、
１本以上の反応管を備える管式熱交換型固定床反応器様式の第１反応帯、および、熱交換しない固定床反応器様式の第２反応帯を有する反応器を用い、
第１反応帯に充填される触媒体積をＶ１、第２反応帯に充填される触媒体積をＶ２としたとき、Ｖ１／（Ｖ１＋Ｖ２）を０．３以上０．８以下とし、
第１反応帯の反応管入口側より前記原料流体を供給して、前記原料流体中の前記原料化合物を３０％以上８０％未満の転化率で反応させて、未反応の原料化合物および反応生成物を含む流体を得、
前記未反応の原料化合物および反応生成物を含む流体を第２反応帯に導入して原料化合物をさらに転化させる
ことを特徴とする反応方法。 (1) A reaction method in which a raw material fluid containing an unsaturated hydrocarbon and / or an unsaturated aldehyde as a raw material compound is supplied to a reactor filled with a catalyst to perform gas phase catalytic oxidation,
A reactor having a first reaction zone of a tubular heat exchange type fixed bed reactor type having one or more reaction tubes, and a second reaction zone of a fixed bed reactor type not performing heat exchange,
When the volume of the catalyst filled in the first reaction zone is V1 and the volume of the catalyst filled in the second reaction zone is V2, V1 / (V1 + V2) is 0.3 or more and 0.8 or less,
The raw material fluid is supplied from the reaction tube inlet side of the first reaction zone, and the raw material compounds in the raw material fluid are reacted at a conversion of 30% or more and less than 80%, and unreacted raw material compounds and reaction products Obtaining a fluid containing
A reaction method comprising introducing a fluid containing the unreacted raw material compound and a reaction product into a second reaction zone to further convert the raw material compound.

（２）前記第１反応帯中の前記反応管内部において、端部または途中から他方の端部に向けて連続的または段階的に体積が減少する形状を有する構造物が、前記構造物の最小端面が反応管出口側に向けて設置されている、前記（１）に記載の反応方法。   (2) Within the reaction tube in the first reaction zone, a structure having a shape in which the volume is reduced continuously or stepwise from one end or the other toward the other end is the minimum of the structure. The reaction method according to the above (1), wherein the end face is installed toward the exit side of the reaction tube.

（３）前記の第２反応帯に充填される触媒の活性が、前記第１反応帯に充填される触媒の活性以上である、前記（１）または（２）に記載の反応方法。   (3) The reaction method according to (1) or (2), wherein the activity of the catalyst charged in the second reaction zone is equal to or higher than the activity of the catalyst charged in the first reaction zone.

（４）前記気相接触酸化により、前記原料化合物に対応するアルデヒドおよび／またはカルボン酸を得る、前記（１）から（３）のいずれかに記載の反応方法。   (4) The reaction method according to any one of (1) to (3), wherein an aldehyde and / or a carboxylic acid corresponding to the raw material compound is obtained by the gas phase catalytic oxidation.

（５）前記原料化合物が、プロピレン、イソブチレン、アクロレインおよびメタクロレインから選ばれる少なくとも１つである、前記（１）から（４）のいずれかに記載の反応方法。   (5) The reaction method according to any one of (1) to (4), wherein the raw material compound is at least one selected from propylene, isobutylene, acrolein, and methacrolein.

（６）気相接触酸化反応に用いるための反応器であって、１本以上の反応管を備える管式熱交換型固定床反応器様式の第１反応帯、および、熱交換しない固定床反応器様式の第２反応帯を有することを特徴とする反応器。   (6) A reactor for use in a gas phase catalytic oxidation reaction, wherein the first reaction zone is a tubular heat exchange type fixed bed reactor having one or more reaction tubes, and a fixed bed reaction without heat exchange. A reactor having a second reaction zone in a vessel type.

（７）前記第１反応帯と前記第２反応帯を同一反応器内に備えてなる、前記（６）に記載の反応器。   (7) The reactor according to (6), wherein the first reaction zone and the second reaction zone are provided in the same reactor.

（８）前記第１反応帯と前記第２反応帯がそれぞれ独立した反応器であって、各反応器が導管によって接続されてなる、前記（６）に記載の反応器。   (8) The reactor according to (6), wherein the first reaction zone and the second reaction zone are independent reactors, and each reactor is connected by a conduit.

（９）前記第１反応帯中の前記反応管内部において、端部または途中から他方の端部に向けて連続的または段階的に体積が減少する形状を有する構造物が、前記構造物の最小端面が反応管出口側に向けて設置されている、前記（６）から（８）のいずれかに記載の反応器。   (9) In the inside of the reaction tube in the first reaction zone, a structure having a shape whose volume decreases continuously or stepwise from one end or the other toward the other end is the minimum of the structure. The reactor according to any one of (6) to (8), wherein the end face is provided toward the reaction tube outlet side.

（１０）前記気相接触酸化反応が、触媒を充填した反応器に原料化合物としての不飽和炭化水素および／または不飽和アルデヒドを含有する原料流体を供給して対応するアルデヒドおよび／またはカルボン酸を得る反応である、前記（６）から（９）のいずれかに記載の反応器。   (10) In the gas phase catalytic oxidation reaction, a raw material fluid containing an unsaturated hydrocarbon and / or an unsaturated aldehyde as a raw material compound is supplied to a reactor filled with a catalyst to convert a corresponding aldehyde and / or carboxylic acid into a raw material fluid. The reactor according to any one of the above (6) to (9), which is a reaction to be obtained.

不飽和炭化水素を気相接触酸化し対応するアルデヒドおよびカルボン酸を製造するプロセス、不飽和アルデヒドを気相接触酸化し対応するカルボン酸を製造するプロセスにおいて、従来は触媒層全域を多管式熱交換型固定床反応器に収めて反応させることで原料化合物を高い水準の転化率まで高めていたが、触媒層後半、すなわち、触媒層下流側を熱交換しない固定床反応器様式に替えることで、反応器の構造を簡便にかつ設置容積をコンパクトにでき、プラントの建設費用を抑制することができる。加えて、触媒層後半を熱交換しない固定床反応器様式とすることで、触媒自体の発熱によって反応が自立して進行するため、当該領域における触媒の反応への寄与が高くなり、その結果、触媒層全域にわたって効率よく反応を行わせることができる。また、触媒層前半、すなわち、触媒層上流側は従来の管式熱交換型固定床反応器様式とし、加えて、局所的異常高温部を分散する機能を有する構造物を設置することで、触媒層上流側での副生成物生成や触媒の損傷を抑制し、暴走反応の懸念も減ずることができる。さらに、触媒層下流側の熱交換しない固定床反応器様式の反応帯に充填する触媒の活性を、触媒層上流側の反応帯中の反応管に充填する触媒の活性以上とすることで生産性も向上できる。以上の結果、局所的な触媒の劣化が抑制され、触媒層全域において触媒が効率よく反応に寄与できるため、気相接触反応によるアルデヒドおよびカルボン酸の製造を長期間安定して操業することができる。   In the process of producing the corresponding aldehyde and carboxylic acid by gas-phase catalytic oxidation of unsaturated hydrocarbons, and the process of producing the corresponding carboxylic acid by gas-phase catalytic oxidation of unsaturated aldehydes, the entire catalyst layer has conventionally been multitubular heat treatment. Although the raw material compounds were increased to a high level of conversion by allowing them to react in an exchange-type fixed-bed reactor, the latter half of the catalyst layer, that is, the fixed-bed reactor type in which heat exchange was not performed on the downstream side of the catalyst layer was changed. In addition, the structure of the reactor can be made simple and the installation volume can be made compact, and the plant construction cost can be suppressed. In addition, since the reaction proceeds independently by the heat generation of the catalyst itself by setting the latter half of the catalyst layer to a fixed bed reactor type that does not exchange heat, the contribution of the catalyst to the reaction in the region becomes higher, and as a result, The reaction can be efficiently performed over the entire area of the catalyst layer. In addition, the first half of the catalyst layer, that is, the upstream side of the catalyst layer is a conventional tubular heat exchange type fixed bed reactor type, and in addition, by installing a structure having a function of dispersing a local abnormal high temperature part, The formation of by-products and damage to the catalyst on the upstream side of the bed can be suppressed, and the fear of runaway reaction can be reduced. Furthermore, the productivity of the catalyst packed in the reaction zone of the fixed bed reactor type downstream of the catalyst layer without heat exchange is made higher than the activity of the catalyst packed in the reaction tube in the reaction zone upstream of the catalyst layer. Can also be improved. As a result, local deterioration of the catalyst is suppressed, and the catalyst can efficiently contribute to the reaction in the entire area of the catalyst layer, so that the production of aldehyde and carboxylic acid by the gas phase contact reaction can be stably operated for a long period of time. .

またさらに、反応器の伝熱方式を熱交換型から熱交換しない方式に変更することで、熱媒体が不要となり、反応器内に反応管周辺の熱媒体の流路を設ける必要がなくなる。そして、反応器に付随した熱媒体を循環させるための装置や熱交換器が不要となるため、反応器の構造を簡便にでき、設置容積をコンパクトにでき、反応器の製作費用を抑えることもできる。また、熱媒体の温度維持が不要となるため、そのための電力などのユーティリティ費用も不要となり、環境負荷を低減できる。   Further, by changing the heat transfer system of the reactor from the heat exchange type to a system that does not exchange heat, a heat medium is not required, and it is not necessary to provide a flow path of the heat medium around the reaction tube in the reactor. In addition, since there is no need for a device or heat exchanger for circulating the heat medium attached to the reactor, the structure of the reactor can be simplified, the installation volume can be reduced, and the production cost of the reactor can be reduced. it can. Further, since it is not necessary to maintain the temperature of the heat medium, utility costs such as electric power for the maintenance are not required, and the environmental load can be reduced.

第１反応帯と第２反応帯とを有する反応器の模式図である。It is a schematic diagram of a reactor having a first reaction zone and a second reaction zone. 第１反応帯と第２反応帯と中間層とを有する反応器の模式図である。It is a schematic diagram of a reactor having a first reaction zone, a second reaction zone, and an intermediate layer. 第１反応帯からなる反応器と第２反応帯からなる反応器とを連結した模式図である。It is the schematic diagram which connected the reactor which consists of a 1st reaction zone, and the reactor which consists of a 2nd reaction zone.

以下に本発明をさらに詳細に説明する。   Hereinafter, the present invention will be described in more detail.

＜反応器の説明＞
本発明の反応器は、１本以上の反応管を備える管式熱交換型固定床反応器様式の第１反応帯と、熱交換しない固定床反応器様式の第２反応帯を有する反応器である。 <Description of reactor>
The reactor of the present invention is a reactor having a first reaction zone of a tubular heat exchange type fixed bed reactor type having one or more reaction tubes and a second reaction zone of a fixed bed reactor type without heat exchange. is there.

第１反応帯の管式熱交換型固定床反応器様式とは、反応管を収容した反応器シェルに溶融塩などの熱媒体を循環させ、触媒を充填した反応管に原料流体を供給した際に発生する熱を、前記熱媒体を通じて回収する仕組みを持つものであり、従来公知の反応器の形式が参照されうる。なお、第１反応帯における反応管の本数は特に制限されず、反応管数が１本の単管式熱交換型固定床反応器様式であってもよいし、２本以上、さらには数百から数万本の多管式熱交換型固定床反応器様式であってもよいが、化合物を工業的に製造する目的で２本以上の反応管を備える多管式熱交換型固定床反応器様式とすることが好ましい。   The tubular heat exchange type fixed bed reactor type in the first reaction zone means that a heating medium such as a molten salt is circulated through a reactor shell containing a reaction tube and a raw material fluid is supplied to a reaction tube filled with a catalyst. This has a mechanism for recovering the heat generated in the reactor through the heat medium, and a conventionally known reactor type can be referred to. The number of reaction tubes in the first reaction zone is not particularly limited, and may be a single tube heat exchange type fixed bed reactor having one reaction tube, or two or more, and even several hundreds. A multi-tubular heat-exchange fixed-bed reactor having two or more reaction tubes for the purpose of industrially producing a compound may be used. It is preferable to use a style.

第２反応帯の熱交換しない固定床反応器様式とは、触媒層と外部との熱交換がない様式のものである。具体的には、流体通過方向に対する垂直方向において熱の出入りがなく、触媒反応に伴う発熱のみで反応を自立させることができるようになっており、従来公知の広義の断熱反応器の形式が参照されうる。前記断熱反応器では、反応管からの熱の出入りを遮断するため、反応管の周囲は断熱材などの断熱層で厳重に保温される。しかし、現実的には若干の放熱が発生するため、そのような放熱を補償するための電気ヒーターやスチームジャケットなどを断熱層に加えてあるいは断熱層に替えて備えていてもよい。当該第２反応帯のサイズは、触媒活性、発熱量、ガス線速等を考慮して設計すればよい。   The fixed bed reactor mode without heat exchange in the second reaction zone is a mode where there is no heat exchange between the catalyst layer and the outside. Specifically, there is no flow of heat in the direction perpendicular to the fluid passage direction, and the reaction can be made independent by only the heat generated by the catalytic reaction, and a conventionally known broad adiabatic reactor type is referred to. Can be done. In the adiabatic reactor, the surroundings of the reaction tube are strictly kept warm by a heat insulating layer such as a heat insulating material in order to block the flow of heat from the reaction tube. However, since some heat radiation actually occurs, an electric heater, a steam jacket, or the like for compensating such heat radiation may be provided in addition to or instead of the heat insulating layer. The size of the second reaction zone may be designed in consideration of the catalyst activity, the calorific value, the gas linear velocity, and the like.

本発明の反応器は、前記の第１反応帯と第２反応帯が連結されていることが好ましく、直結されていることがより好ましい。原料化合物を含有する原料流体は、前記第１反応帯の原料流体供給口から供給されて反応に供される。前記の２つの異なる反応帯を接続する接続部は、基本的には保温された状態で最短距離で設置することが好ましいが、両反応帯の間に熱交換器などを設置して前記第２反応帯で反応が維持できる範囲で流体温度を調節してもよい。   In the reactor of the present invention, the first reaction zone and the second reaction zone are preferably connected, more preferably directly connected. The raw material fluid containing the raw material compound is supplied from the raw material fluid supply port of the first reaction zone to be subjected to the reaction. The connecting part for connecting the two different reaction zones is basically preferably installed at the shortest distance in a state where the temperature is maintained. The fluid temperature may be adjusted within a range where the reaction can be maintained in the reaction zone.

本発明の反応器の態様は、図１および図２に示すように、管式熱交換型固定床反応器様式の第１反応帯および熱交換しない固定床反応器様式の第２反応帯は、一体化されて同一反応器内に備わっていてもよく、それぞれ独立した反応器であってもよい。   As shown in FIGS. 1 and 2, the embodiment of the reactor of the present invention comprises a first reaction zone of a tubular heat exchange type fixed bed reactor type and a second reaction zone of a fixed bed reactor type without heat exchange. The reactors may be integrated and provided in the same reactor, or may be independent reactors.

一体化した構造としては、一つの反応器を管式熱交換型固定床の下流側管板面で区切る構造を示すことができる。（図１−ａ）。上流側の管式熱交換型固定床部分である第１反応帯は反応管の外部を熱媒体が流通する機構を有し、下流側の熱交換しない固定床反応部である第２反応帯は熱媒体が流通する機構を有していない。後者の触媒層は、単一の区画であってもよく、仕切り板などにより複数の区画に分かれていてもよい。また、第１反応帯と第２反応帯との境界には担体等を充填することで、第１反応帯から出てきた反応ガスを第２反応帯に均一に分散させる機構を有していてもよい。なお、図１−ａにおいて、第２反応帯の断熱層は第１反応帯の保温材と共有する構造としているため、表示を省略している。   As an integrated structure, there can be shown a structure in which one reactor is divided by a tube sheet surface on the downstream side of a tubular heat exchange fixed bed. (FIG. 1-a). The first reaction zone, which is a tubular heat exchange type fixed bed portion on the upstream side, has a mechanism through which a heat medium flows outside the reaction tube, and the second reaction zone, which is a fixed bed reaction portion on the downstream side that does not exchange heat, is Does not have a mechanism through which the heat medium flows. The latter catalyst layer may be a single section, or may be divided into a plurality of sections by a partition plate or the like. Further, a mechanism is provided in which a boundary between the first reaction zone and the second reaction zone is filled with a carrier or the like so that the reaction gas coming out of the first reaction zone is uniformly dispersed in the second reaction zone. Is also good. In FIG. 1-a, the heat insulating layer of the second reaction zone has a structure shared with the heat insulating material of the first reaction zone, and thus the illustration is omitted.

さらに、第２反応帯において、その反応条件を制御するために、反応ガスの流れ方向と直交する断面を第１反応帯の管板径よりも小さくすることができる。この場合、反応ガスが第２反応帯に均一に供給されるように、第１反応帯と第２反応帯との間に中間層として、担体、ラシヒリング、整流板等を設置することが好ましい（図１−ｂ）。   Furthermore, in order to control the reaction conditions in the second reaction zone, the cross section orthogonal to the flow direction of the reaction gas can be made smaller than the tube plate diameter of the first reaction zone. In this case, it is preferable to install a carrier, a Raschig ring, a rectifying plate, and the like as an intermediate layer between the first reaction zone and the second reaction zone so that the reaction gas is uniformly supplied to the second reaction zone ( FIG. 1-b).

管式熱交換型固定床反応器様式の第１反応帯および熱交換しない固定床反応器様式の第２反応帯がそれぞれ独立した反応器である場合は、第１反応帯から出るガスを第２反応帯へ送るための導管によって両反応器が接続されている態様を示すことができる。その際、第２反応帯の反応器の安全対策として、接続導管の任意の箇所から窒素や水蒸気などの不活性ガスを導入してもよい（図２）。   When the first reaction zone of the tubular heat exchange type fixed bed reactor type and the second reaction zone of the fixed bed reactor type without heat exchange are independent reactors, the gas exiting from the first reaction zone is supplied to the second reaction zone. It can be shown that both reactors are connected by a conduit to the reaction zone. At that time, as a safety measure for the reactor in the second reaction zone, an inert gas such as nitrogen or water vapor may be introduced from an arbitrary portion of the connecting conduit (FIG. 2).

上記いずれの態様においても、第１反応帯中における局所的異常高温部の発生を防止あるいは抑制するために、後述する反応熱制御用構造物が第１反応帯中の反応管内部に設置されることが好ましい。   In any of the above embodiments, a reaction heat control structure described later is installed inside the reaction tube in the first reaction zone in order to prevent or suppress the occurrence of a local abnormal high temperature portion in the first reaction zone. Is preferred.

本発明の反応器を用いて行なわれる反応としては、触媒による気相接触酸化反応であれば原料化合物および目的生成物については特に限定されないが、そのなかでも、後述するように、原料化合物としての不飽和炭化水素および／または不飽和アルデヒドを含有する原料流体を供給して対応するアルデヒドおよび／またはカルボン酸を得る反応に好適に用いることができる。   The reaction performed using the reactor of the present invention is not particularly limited as to the raw material compound and the target product as long as it is a gas phase catalytic oxidation reaction using a catalyst. It can be suitably used in a reaction in which a raw material fluid containing an unsaturated hydrocarbon and / or an unsaturated aldehyde is supplied to obtain a corresponding aldehyde and / or carboxylic acid.

＜構造物の説明＞
本発明において、管式熱交換型固定床反応器様式の第１反応帯中の反応管内には、局所的異常高温部の発生を防ぐ効果を有する反応熱制御用の構造物が設置されることが好ましい。当該構造物としては、具体的には、例えば、国際公開第２０１５／０６８６４０号パンフレットに開示されているような反応管用充填物を参照することができる。当該構造物の形状および構造としては、端部または途中から他方の端部に向けて体積が減少する形状を有していればどのような外形でもよく、その体積変化は連続的または段階的でもよい。また、当該構造物は、その内部から外表面方向に原料流体が通過可能な開孔部を有することが好ましい。 <Description of structure>
In the present invention, a reaction heat control structure having an effect of preventing the occurrence of a local abnormal high temperature portion is installed in a reaction tube in a first reaction zone of a tubular heat exchange type fixed bed reactor type. Is preferred. As the structure, specifically, for example, a filler for a reaction tube as disclosed in WO 2015/068640 pamphlet can be referred to. As the shape and structure of the structure, any shape may be used as long as it has a shape in which the volume decreases from the end or the middle toward the other end, and the volume change may be continuous or stepwise. Good. Further, the structure preferably has an opening through which the raw material fluid can pass from the inside toward the outer surface.

当該構造物は底面部といえる部分を有する。かかる底面部は、当該構造物の高さ方向に直交する方向で最も大きな断面積を有する端部である。例えば当該構造物が側面部に加えてさらに上面部を有する場合には、底面部は上面部よりも大きな面積を有する。当該構造物を、最小端面が反応管出口側に向くように、すなわち、当該底面部が反応管の触媒層における原料流体入口側に存在するように反応管内部に設置した場合、当該底面部の面積に応じて反応管内触媒層の原料流体入口側における触媒量を減らし、触媒層入口側における局所的異常高温部の発生を抑制することが可能になる。かかる底面部は完全な面である必要はなく、凹凸を有していたり、あるいは触媒が内部に侵入しない範囲で孔を有していたり網目状になっていてもよい。   The structure has a portion that can be called a bottom portion. Such a bottom portion is an end portion having the largest cross-sectional area in a direction orthogonal to the height direction of the structure. For example, when the structure has an upper surface in addition to the side surface, the bottom surface has a larger area than the upper surface. When the structure is installed inside the reaction tube such that the minimum end face faces the reaction tube outlet side, that is, the bottom surface is located on the raw material fluid inlet side in the catalyst layer of the reaction tube, It is possible to reduce the amount of the catalyst on the raw material fluid inlet side of the catalyst layer in the reaction tube according to the area, and to suppress the occurrence of a local abnormally high temperature portion on the catalyst layer inlet side. Such a bottom surface does not need to be a complete surface, and may have irregularities, or may have holes or a mesh shape as long as the catalyst does not enter the inside.

当該構造物は、端部または途中から他方の端部に向けて連続的または段階的に体積が減少する形状を有する。ここで、上記の「端部」とは上記底面部に相当し、当該構造物の高さ方向に直交する方向の断面積が最も大きな端部をいう。なお、ここでの「構造物の高さ方向」とは、当該構造物のある一つの端部からその反対側の端部までの長さが最も長い方向をいうものとする。また、「他方の端部」とは、上記底面部の反対側の端部であり、例えば、当該構造物が上面部を有する場合は上面部をいい、当該構造物が錐体である場合は頂点をいう。一方の端部から他方の端部に向けて段階的に体積が減少する場合、体積が減少し始める当該構造物の高さ方向における底面部からの位置としては、当該構造物の高さ方向において底面部の位置を０％、他方の端部の位置を１００％とした場合に、７０％以下、６０％以下または５０％以下が好ましく、４０％以下、３０％以下または２０％以下がより好ましく、１５％以下または１０％以下が特に好ましい。   The structure has a shape in which the volume decreases continuously or stepwise from one end or the other toward the other end. Here, the “end” corresponds to the bottom surface, and refers to the end having the largest cross-sectional area in the direction orthogonal to the height direction of the structure. Here, the “height direction of the structure” means the direction in which the length from one end of the structure to the opposite end is the longest. The `` other end '' is an end on the opposite side of the bottom surface, for example, when the structure has an upper surface, it refers to the upper surface, and when the structure is a cone, The vertex. When the volume decreases stepwise from one end to the other end, as the position from the bottom surface in the height direction of the structure where the volume starts to decrease, in the height direction of the structure When the position of the bottom portion is 0% and the position of the other end is 100%, 70% or less, 60% or less, or 50% or less is preferable, and 40% or less, 30% or less, or 20% or less is more preferable. , 15% or less or 10% or less is particularly preferred.

上記の「連続的に体積が減少する形状」とは、当該構造物の高さ方向に直交する方向の断面積が、当該構造物の底面部からの距離が大きいほど小さくなる形状をいう。また、「段階的に体積が減少する形状」とは、当該構造物の底面部面積に比べて他方の端部における面積が小さく、かつ、当該構造物の高さ方向に直交する方向の断面積が、底面部からの距離が異なる位置において同一である箇所が１以上存在するが、底面部からの距離がより大きな位置における当該断面積がより小さな位置に比べて大きいことはない形状をいう。すなわち、上記の「体積」は、当該構造物の高さ方向に直交する方向の断面積に相当する。   The “shape in which the volume continuously decreases” refers to a shape in which the cross-sectional area in the direction orthogonal to the height direction of the structure decreases as the distance from the bottom surface of the structure increases. Further, “a shape in which the volume decreases stepwise” means that the area at the other end is smaller than the area of the bottom surface of the structure, and the cross-sectional area in the direction orthogonal to the height direction of the structure However, there is one or more locations that are the same at different distances from the bottom surface, but does not have a larger cross-sectional area at a position at a larger distance from the bottom surface than at a smaller position. That is, the “volume” corresponds to a cross-sectional area in a direction orthogonal to the height direction of the structure.

本発明において反応熱制御のために用いられる構造物の材質は、反応温度において耐熱性を有するものであれば特に制限はなく、金属やセラミックスを用いることができる。   In the present invention, the material of the structure used for controlling the reaction heat is not particularly limited as long as it has heat resistance at the reaction temperature, and a metal or ceramic can be used.

本発明に係る構造物の大きさは、使用する反応管の大きさ（径）や反応の種類などに応じて適宜決定すればよい。一般的には、例えば、底面部の円相当直径が５ｍｍ以上、４０ｍｍ以下程度、高さを２０ｍｍ以上、１０ｍ以下程度とすることができる。より具体的には、構造物の大きさは、当該構造物を挿入すべき反応管中の触媒層の断面積や層長に応じて適宜決定すればよい。例えば、反応管の内部断面積、すなわち触媒層の断面積に対する構造物の最大断面積、すなわち構造物の底面部の面積の割合としては、１０％以上が好ましく、３０％以上がより好ましい。当該割合が１０％以上であれば、反応管の入口側、すなわち触媒層の原料流体入口側における触媒への負荷をより確実に軽減することができる。また、当該割合としては、１００％以下が好ましく、６０％以下がより好ましい。後述するように構造物の底面部に開孔部を設ければ、当該割合が１００％であっても、触媒層へ原料流体を導入することができる。   The size of the structure according to the present invention may be appropriately determined according to the size (diameter) of the reaction tube to be used, the type of reaction, and the like. Generally, for example, the circle equivalent diameter of the bottom portion can be about 5 mm or more and about 40 mm or less, and the height can be about 20 mm or more and about 10 m or less. More specifically, the size of the structure may be appropriately determined according to the cross-sectional area and the layer length of the catalyst layer in the reaction tube into which the structure is to be inserted. For example, the internal cross-sectional area of the reaction tube, that is, the maximum cross-sectional area of the structure relative to the cross-sectional area of the catalyst layer, that is, the ratio of the area of the bottom portion of the structure is preferably 10% or more, and more preferably 30% or more. When the ratio is 10% or more, the load on the catalyst on the inlet side of the reaction tube, that is, the raw material fluid inlet side of the catalyst layer can be reduced more reliably. The ratio is preferably 100% or less, more preferably 60% or less. If an opening is provided on the bottom surface of the structure as described later, the raw material fluid can be introduced into the catalyst layer even if the ratio is 100%.

反応管の内部断面積、すなわち触媒層の断面積に対する構造物の最小断面積、すなわち構造物の底面部の反対側端部の断面積の割合としては、０％以上、５０％以下が好ましく、３０％以下がより好ましい。当該割合が０％の場合は、当該構造物の底面部の反対側端部の断面積がゼロであり、当該構造物の形状は錐体などとなる。また、当該割合が５０％以下であれば、反応効率の低下をより確実に抑制することができる。   The internal cross-sectional area of the reaction tube, that is, the minimum cross-sectional area of the structure with respect to the cross-sectional area of the catalyst layer, that is, the ratio of the cross-sectional area of the opposite end of the bottom surface of the structure is preferably 0% or more and 50% or less, 30% or less is more preferable. When the ratio is 0%, the cross-sectional area of the end opposite to the bottom of the structure is zero, and the shape of the structure is a cone or the like. In addition, when the ratio is 50% or less, a decrease in reaction efficiency can be more reliably suppressed.

構造物の高さとしては、第１反応帯中の反応管に充填された触媒層長に対して１０％以上が好ましく、２０％以上がより好ましい。当該割合が１０％以上であれば、反応管の入口部、すなわち触媒層の原料流体入口側における触媒への負荷をより確実に軽減することができる。一方、当該割合としては、９０％以下が好ましく、６０％以下がより好ましい。当該割合が９０％以下であれば、反応効率の低下をより確実に抑制できる。   The height of the structure is preferably 10% or more, more preferably 20% or more, with respect to the length of the catalyst layer filled in the reaction tube in the first reaction zone. When the ratio is 10% or more, the load on the catalyst at the inlet of the reaction tube, that is, at the raw material fluid inlet side of the catalyst layer can be reduced more reliably. On the other hand, the ratio is preferably 90% or less, more preferably 60% or less. When the ratio is 90% or less, a decrease in reaction efficiency can be suppressed more reliably.

本発明に係る構造物は、その内部から外表面方向に原料流体が通過可能な開孔部を有することが好ましい。そのような開孔部を有した構造にすることにより、原料流体が当該開孔部を通過して分散し、当該構造物周囲の触媒と接触するため、さらに反応割合の偏りを抑制できる。この場合、当該構造物は触媒層の空隙率を向上させる効果を有し、触媒層の圧力損失を低減することができる。   The structure according to the present invention preferably has an opening through which the raw material fluid can pass from the inside toward the outer surface. With the structure having such an opening, the raw material fluid passes through the opening and is dispersed and comes into contact with the catalyst around the structure, so that the bias in the reaction rate can be further suppressed. In this case, the structure has an effect of improving the porosity of the catalyst layer, and can reduce the pressure loss of the catalyst layer.

本発明に係る構造物の好ましい一様態として、例えば、径の異なる複数の円管を、中心軸および底面を同じくし、大径管の内部に小径管を挿入して同心円状に配置し、管径が小さくなるに連れて管長が長くなる構造を有する多重管を挙げることができる。この場合、外周部から中心部に向けて径が段階的に減少し、且つ内側に設置した円管の外壁と、隣接して外側に配置した円管の内壁との間に空隙ができ、開孔部を有する構造となる。かかる円管を構成する管の壁厚は、通常、０．０５ｍｍ以上、０．３ｍｍ以下とすることができる。   As a preferred embodiment of the structure according to the present invention, for example, a plurality of circular pipes having different diameters, the central axis and the bottom surface are the same, a small-diameter pipe is inserted inside a large-diameter pipe, and the pipes are arranged concentrically. A multiple tube having a structure in which the tube length becomes longer as the diameter becomes smaller can be exemplified. In this case, the diameter decreases stepwise from the outer peripheral portion toward the central portion, and a gap is formed between the outer wall of the circular tube installed inside and the inner wall of the circular tube arranged adjacently outside. The structure has a hole. The wall thickness of the tube constituting such a circular tube can be generally 0.05 mm or more and 0.3 mm or less.

＜触媒＞
本発明で用いる触媒の材質は特に制限されず、目的とする反応を促進するものを選択すればよい。例えば、プロピレンをアクロレインに酸化するための触媒の活性成分としては、以下の組成を有するものを挙げることができる。活性成分は担体に担持してもよい。 <Catalyst>
The material of the catalyst used in the present invention is not particularly limited, and a material that promotes a desired reaction may be selected. For example, as an active component of a catalyst for oxidizing propylene to acrolein, those having the following composition can be mentioned. The active ingredient may be carried on a carrier.

前記触媒の活性成分の組成は、Ｍｏ１２ＢｉａＦｅｂＡｃＢｄＣｅＤｆＯｘで表される。
（ここで、Ｍｏはモリブデン、Ｂｉはビスマス、Ｆｅは鉄、Ａはコバルトおよびニッケルからなる群より選ばれる少なくとも一種の元素、Ｂはアルカリ金属、アルカリ土類金属およびタリウムからなる群より選ばれる少なくとも一種の元素、Ｃはタングステン、ケイ素、アルミニウム、チタンおよびジルコニウムからなる群より選ばれる少なくとも一種の元素、Ｄはリン、テルル、アンチモン、スズ、セリウム、鉛、ニオブ、マンガン、砒素および亜鉛からなる群より選ばれる少なくとも一種の元素、Ｏは酸素を表し、ａ、ｂ、ｃ、ｄ、ｅ、ｆおよびｘはそれぞれＢｉ、Ｆｅ、Ａ、Ｂ、Ｃ、Ｄ及びＯの原子数を表し、０＜ａ≦１０、０＜ｂ≦２０、２≦ｃ≦２０、０＜ｄ≦１０、０≦ｅ≦３０、０≦ｆ≦４であり、ｘは各元素の酸化状態により定まる値をとる。）
また、アクロレインをアクリル酸に酸化するための触媒の活性成分としては、以下の組成を有するものを挙げることができる。活性成分は担体に担持してもよい。 The composition of the active ingredient of the catalyst is represented by Mo 12 Bi a Fe b A c B d C e D f O x.
(Where Mo is molybdenum, Bi is bismuth, Fe is iron, A is at least one element selected from the group consisting of cobalt and nickel, and B is at least one element selected from the group consisting of alkali metals, alkaline earth metals and thallium. One kind of element, C is at least one kind of element selected from the group consisting of tungsten, silicon, aluminum, titanium and zirconium, and D is a group consisting of phosphorus, tellurium, antimony, tin, cerium, lead, niobium, manganese, arsenic and zinc At least one element selected from the group consisting of O represents oxygen, a, b, c, d, e, f, and x each represent the number of atoms of Bi, Fe, A, B, C, D, and O; a ≦ 10, 0 <b ≦ 20, 2 ≦ c ≦ 20, 0 <d ≦ 10, 0 ≦ e ≦ 30, 0 ≦ f ≦ 4, and x depends on the oxidation state of each element. It takes a determined value.)
The active component of the catalyst for oxidizing acrolein to acrylic acid includes those having the following composition. The active ingredient may be carried on a carrier.

前記触媒の活性成分の組成は、ＭｏａＶｂＷｃＣｕｄＳｂｅＸｆＹｇＺｈＯｉで表される。
（ここで、Ｍｏはモリブデン、Ｖはバナジウム、Ｗはタングステン、Ｃｕは銅、Ｓｂはアンチモン、Ｘはニオブ、テルルおよびスズから選ばれる少なくとも一種の元素、Ｙはマグネシウム、カルシウム、ストロンチウム、バリウムおよびアルカリ金属から選ばれる少なくとも一種の元素、Ｚはシリコン、アルミニウム、チタン、ジルコニウムおよびセリウムから選ばれる少なくとも一種の元素、そしてＯは酸素を表し、ａ、ｂ、ｃ、ｄ、ｅ、ｆ、ｇ、ｈおよびｉは、Ｍｏ、Ｖ、Ｗ、Ｃｕ、Ｓｂ、Ｘ、Ｙ、ＺおよびＯの原子数を表し、ａ＝１２のとき、２≦ｂ≦１４、０＜ｃ≦１２、０＜ｄ≦６、０＜ｅ≦５、０≦ｆ≦５、０≦ｇ≦３、０≦ｈ≦５０であり、ｉは各々の元素の酸化状態によって定まる値をとる。）
触媒の形状は特に限定されず、ペレット、リング、球、サドルなど、反応特性に応じて従来公知の形状から選択すればよい。 The composition of the active ingredient of the catalyst is represented by Mo a V b W c Cu d Sb e X f Y g Z h O i.
(Where Mo is molybdenum, V is vanadium, W is tungsten, Cu is copper, Sb is antimony, X is at least one element selected from niobium, tellurium and tin, Y is magnesium, calcium, strontium, barium and alkali. At least one element selected from metals, Z represents at least one element selected from silicon, aluminum, titanium, zirconium and cerium, and O represents oxygen; a, b, c, d, e, f, g, h And i represent the number of atoms of Mo, V, W, Cu, Sb, X, Y, Z and O. When a = 12, 2 ≦ b ≦ 14, 0 <c ≦ 12, 0 <d ≦ 6 , 0 <e ≦ 5, 0 ≦ f ≦ 5, 0 ≦ g ≦ 3, 0 ≦ h ≦ 50, and i takes a value determined by the oxidation state of each element.)
The shape of the catalyst is not particularly limited, and may be selected from conventionally known shapes such as pellets, rings, spheres, and saddles according to the reaction characteristics.

本発明の第１反応帯および第２反応帯に形成される触媒層において、後者に充填される触媒の活性が前者に充填される触媒の活性以上であることが好ましい。すなわち、第１反応帯および第２反応帯には同じ活性の触媒を充填してもよいし、第２反応帯に第１反応帯より高い活性の触媒を充填してもよい。触媒の活性序列は、同一の反応温度および触媒体積において、同一組成の原料流体を同一流量で触媒に供給したときの原料転化率を比較して、判別することができる。原料転化率の計算は、基本的には、反応した原料のモル数を供給した原料のモル数で除したもので表される。なお、第２反応帯に第１反応帯より高い活性の触媒を充填する場合、第２反応帯に充填する触媒の活性は、第１反応帯に充填する触媒の活性よりも、上記転化率として０．５％以上、好ましくは１．０％以上、より好ましくは２％以上高くする。   In the catalyst layers formed in the first reaction zone and the second reaction zone of the present invention, it is preferable that the activity of the latter catalyst is higher than the activity of the former catalyst. That is, the first reaction zone and the second reaction zone may be filled with a catalyst having the same activity, or the second reaction zone may be filled with a catalyst having a higher activity than the first reaction zone. The activity sequence of the catalyst can be determined by comparing the raw material conversion when the raw material fluid having the same composition is supplied to the catalyst at the same flow rate at the same reaction temperature and the same catalyst volume. The calculation of the raw material conversion rate is basically expressed by dividing the number of moles of the reacted raw material by the number of moles of the supplied raw material. When the second reaction zone is charged with a catalyst having a higher activity than the first reaction zone, the activity of the catalyst charged in the second reaction zone is higher than the activity of the catalyst charged in the first reaction zone in the conversion rate. 0.5% or more, preferably 1.0% or more, more preferably 2% or more.

第２反応帯に充填する触媒の活性が第１反応帯に充填する触媒の活性よりも高い場合、前者と後者の触媒の組成は、同じでも異なっていてもよい。具体的には以下の従来公知の方法で第２反応帯に充填する触媒を得ることができる。例えば、反応物質の触媒表面への吸着、あるいは反応生成物の触媒表面からの脱離を制御することにより触媒活性を調整することが可能であるため、触媒の酸塩基量を制御する目的で、触媒へのアルカリ金属および／またはアルカリ土類金属の添加量を調整する手法が広く用いられる。さらに簡便には、同じ組成で第２反応帯に充填する触媒の大きさを第１反応帯に充填する触媒より小さくすること、あるいは、第１反応帯に充填する触媒の焼成温度よりも第２反応帯に充填する触媒の焼成温度を低くすることによっても、第２反応帯に充填するための相対的に高活性な触媒を得ることができる。   When the activity of the catalyst charged in the second reaction zone is higher than the activity of the catalyst charged in the first reaction zone, the former and the latter may have the same or different compositions. Specifically, a catalyst to be filled in the second reaction zone can be obtained by the following conventionally known method. For example, since it is possible to adjust the catalytic activity by controlling the adsorption of the reactants on the catalyst surface or the desorption of the reaction product from the catalyst surface, for the purpose of controlling the acid-base amount of the catalyst, Techniques for adjusting the amount of alkali metal and / or alkaline earth metal added to the catalyst are widely used. More simply, the size of the catalyst filled in the second reaction zone with the same composition may be made smaller than that of the catalyst filled in the first reaction zone, or the second temperature may be lower than the calcination temperature of the catalyst filled in the first reaction zone. By lowering the firing temperature of the catalyst to be charged into the reaction zone, a relatively highly active catalyst to be charged into the second reaction zone can be obtained.

触媒の形状は特に限定されず、ペレット、リング、球、サドルなど、反応特性に応じて従来公知の形状から選択すればよい。触媒の大きさは反応管の形状や内容積に応じて充填可能なサイズであればよく、反応管に上記構造物を設置する場合は反応管と当該構造物との空隙に充填可能なサイズであれば特に限定されることはない。なお、第１反応帯および第２反応帯に充填する触媒について、それぞれ形状の異なる触媒を選択した場合、等体積球相当直径に換算して大きさを比較することができる。この場合、触媒の大きさは、等体積球相等直径で１ｍｍ以上９ｍｍ以下とすることができる。等体積球相等直径は、例えば、目的の触媒の体積を触媒の形状から種々の立体体積を算出する公式に当て嵌めて算出した後、前記の立体体積と等しい体積を占める球の直径を算出することによって導出することができる。   The shape of the catalyst is not particularly limited, and may be selected from conventionally known shapes such as pellets, rings, spheres, and saddles according to the reaction characteristics. The size of the catalyst may be a size that can be filled according to the shape and the internal volume of the reaction tube, and when the above structure is installed in the reaction tube, a size that can be filled in the gap between the reaction tube and the structure. If there is, there is no particular limitation. When catalysts having different shapes are selected for the catalysts to be filled in the first reaction zone and the second reaction zone, the sizes can be compared in terms of equivalent volume sphere equivalent diameter. In this case, the size of the catalyst may be equal to or greater than 1 mm and equal to or less than 9 mm in terms of equal volume spherical phase equal diameter. The equivalent volume spherical phase equivalent diameter is calculated, for example, by fitting the volume of the target catalyst to a formula for calculating various solid volumes from the shape of the catalyst, and then calculating the diameter of a sphere occupying the same volume as the solid volume. Can be derived by

＜触媒充填＞
本発明にかかる触媒層の形成は通常の方法、すなわち、反応管上部から触媒を注ぐ方法で実施できる。具体的には、第１反応帯においては、反応熱制御用の構造物を反応管内に設置する場合、当該構造物の軸中心と反応管の軸中心部とをほぼ一致させる位置に設置し、そこに当該構造物を包囲する状態となるように触媒を注ぎ入れることによって形成される。第２反応帯においては、熱交換しない固定床反応器様式の装置内に必要量の触媒を均一に展開し充填するだけでよい。 <Catalyst filling>
The formation of the catalyst layer according to the present invention can be carried out by a usual method, that is, a method of pouring the catalyst from the upper portion of the reaction tube. Specifically, in the first reaction zone, when a structure for controlling reaction heat is installed in the reaction tube, the structure is installed at a position where the axial center of the structure substantially coincides with the axial center of the reaction tube, It is formed by pouring the catalyst into a state surrounding the structure. In the second reaction zone, it is only necessary to uniformly deploy and fill the required amount of catalyst in a fixed bed reactor type apparatus without heat exchange.

第１反応帯に充填される触媒の体積Ｖ１は、第１反応帯において原料化合物の転化率が３０％以上８０％未満となるように設定すればよい。また、第２反応帯に充填される触媒の体積Ｖ２は、原料化合物の最終的な転化率が第１反応帯での転化率を上回り所望の水準となるように調整すればよい。ただし、第１反応帯において原料化合物の転化率が３０％未満であれば、第２反応帯での反応割合が極端に増加し、反応を自立させる以上の熱が発生し、暴走反応を起こすおそれがあるため危険である。一方、第１反応帯において原料化合物の転化率が８０％以上となると、第２反応帯での反応割合が極端に少なくなり、反応を自立させることが不可能となって所望の転化率が得られなくなるおそれがある。   The volume V1 of the catalyst filled in the first reaction zone may be set so that the conversion rate of the starting compound in the first reaction zone is 30% or more and less than 80%. Further, the volume V2 of the catalyst filled in the second reaction zone may be adjusted so that the final conversion rate of the raw material compound exceeds the conversion rate in the first reaction zone to a desired level. However, if the conversion rate of the raw material compound is less than 30% in the first reaction zone, the reaction rate in the second reaction zone is extremely increased, generating more heat than the reaction becomes independent and may cause a runaway reaction. It is dangerous because there is. On the other hand, when the conversion of the starting compound in the first reaction zone is 80% or more, the reaction ratio in the second reaction zone becomes extremely small, and it becomes impossible to make the reaction self-supporting, and a desired conversion ratio is obtained. It may not be possible to do so.

本発明において、反応器全体に充填される触媒体積に対する第１反応帯に充填される触媒体積の比（Ｖ１／（Ｖ１＋Ｖ２））は、０．３以上０．８以下である。Ｖ１／（Ｖ１＋Ｖ２）が０．３未満であれば、第２反応帯での反応割合が極端に増加し、反応を自立させる以上の熱が発生し、暴走反応を起こすおそれがあるため危険である。一方、Ｖ１／（Ｖ１＋Ｖ２）が０．８を上回れば、第２反応帯での反応量が極端に少なくなり、反応を自立させることが不可能となり、所望の転化率が得られなくなるおそれがある。上記比については、０．３５以上がより好ましく、０．４以上がさらに好ましく、また、０．７以下がより好ましく、０．６以下がさらに好ましい。   In the present invention, the ratio (V1 / (V1 + V2)) of the catalyst volume charged in the first reaction zone to the catalyst volume charged in the entire reactor is 0.3 or more and 0.8 or less. If V1 / (V1 + V2) is less than 0.3, the reaction rate in the second reaction zone is extremely increased, and heat is generated beyond the self-sustaining reaction, which may cause a runaway reaction, which is dangerous. . On the other hand, if V1 / (V1 + V2) is more than 0.8, the reaction amount in the second reaction zone becomes extremely small, the reaction cannot be made independent, and a desired conversion rate may not be obtained. . About the said ratio, 0.35 or more is more preferable, 0.4 or more is more preferable, 0.7 or less is more preferable, and 0.6 or less is further more preferable.

＜反応方法＞
本発明の反応方法は、化合物を工業的に製造する場合に好適に使用することができる。本発明の反応方法では、上述した反応器、すなわち、１本以上の反応管を備える管式熱交換型固定床反応器様式の第１反応帯と熱交換しない固定床反応器様式の第２反応帯を有する反応器を用い、第１反応帯の反応管入口側より原料化合物を含有する原料流体を供給して、原料流体中の原料化合物を３０％以上８０％未満の転化率で反応させて、未反応の原料化合物および反応生成物を含む流体を得、この得られた未反応の原料化合物および反応生成物を含む流体を第２反応帯に導入して原料化合物をさらに転化させる。なお、上記第１反応帯における原料化合物の転化率については、３５％以上がより好ましく、４０％以上がさらに好ましく、また、７５％未満がより好ましく、７０％未満がさらに好ましい。また、第２反応帯には未反応の原料化合物を含む流体が導入され、ここで原料化合物がさらに転化される。このとき、第１反応帯および第２反応帯を通した原料化合物の総転化率については、限りなく１００％に近いことが好ましいが、副生成物や未反応原料の量を勘案しつつ、所望のプロセスに応じて経済性の高い領域を設定すればよい。 <Reaction method>
The reaction method of the present invention can be suitably used when a compound is industrially produced. In the reaction method of the present invention, the above-mentioned reactor, that is, the second reaction in the fixed bed reactor mode in which heat exchange is not performed with the first reaction zone in the tubular heat exchange fixed bed reactor mode having one or more reaction tubes. A raw material fluid containing a raw material compound is supplied from a reaction tube inlet side of a first reaction zone using a reactor having a zone, and the raw material compounds in the raw material fluid are reacted at a conversion of 30% or more and less than 80%. A fluid containing the unreacted raw material compound and the reaction product is obtained, and the obtained fluid containing the unreacted raw material compound and the reaction product is introduced into the second reaction zone to further convert the raw material compound. The conversion of the raw material compound in the first reaction zone is more preferably 35% or more, still more preferably 40% or more, more preferably less than 75%, and even more preferably less than 70%. A fluid containing an unreacted raw material compound is introduced into the second reaction zone, where the raw material compound is further converted. At this time, the total conversion rate of the raw material compounds passing through the first reaction zone and the second reaction zone is preferably as close as possible to 100%. However, while considering the amount of by-products and unreacted raw materials, It is sufficient to set a highly economical region according to the process.

本発明の反応方法において、第１反応帯中の反応管には、その全容積にわたって触媒を充填してもよいが、触媒層における反応熱を制御して局所的異常高温部の発生を防ぐために、その内部に上述した構造物が設置された反応管に触媒を充填して反応を行なわせることが好ましい。   In the reaction method of the present invention, the reaction tube in the first reaction zone may be filled with a catalyst over its entire volume. However, in order to control the heat of reaction in the catalyst layer and prevent the occurrence of local abnormal high-temperature portions. It is preferable that the reaction is performed by filling a catalyst into a reaction tube in which the above-mentioned structure is installed.

本発明の反応方法では、原料化合物として不飽和炭化水素および／または不飽和アルデヒドを用いる。本発明の反応方法により、原料化合物として不飽和炭化水素を用いた場合は対応するアルデヒドおよび／またはカルボン酸を得ることが好ましく、原料化合物として不飽和アルデヒドを用いた場合は対応するカルボン酸を得ることが好ましい。   In the reaction method of the present invention, an unsaturated hydrocarbon and / or an unsaturated aldehyde is used as a raw material compound. According to the reaction method of the present invention, it is preferable to obtain a corresponding aldehyde and / or carboxylic acid when an unsaturated hydrocarbon is used as a raw material compound, and to obtain a corresponding carboxylic acid when an unsaturated aldehyde is used as a raw material compound. Is preferred.

前記不飽和炭化水素は好適にはプロピレン、イソブチレン、ベンゼンおよびキシレンであり、前記不飽和アルデヒドは好適にはアクロレインおよびメタクロレインである。具体的には、プロピレンの酸化によるアクロレインおよび／またはアクリル酸の製造、アクロレインの酸化によるアクリル酸の製造、イソブチレンの酸化によるメタクロレインおよび／またはメタクリル酸の製造、メタクロレインの酸化によるメタクリル酸の製造、ベンゼンの酸化による無水マレイン酸の製造、キシレンの酸化による無水フタル酸の製造など、発熱の大きい気相酸化反応を挙げることができる。本発明の反応方法は、これらのうち、プロピレン、イソブチレン、アクロレインおよびメタクロレインから選ばれる少なくとも一つを原料化合物として使用する反応に特に好適である。   The unsaturated hydrocarbon is preferably propylene, isobutylene, benzene and xylene, and the unsaturated aldehyde is preferably acrolein and methacrolein. Specifically, production of acrolein and / or acrylic acid by oxidation of propylene, production of acrylic acid by oxidation of acrolein, production of methacrolein and / or methacrylic acid by oxidation of isobutylene, production of methacrylic acid by oxidation of methacrolein Gas-phase oxidation reactions that generate a large amount of heat, such as production of maleic anhydride by oxidation of benzene and production of phthalic anhydride by oxidation of xylene. The reaction method of the present invention is particularly suitable for a reaction using at least one selected from propylene, isobutylene, acrolein and methacrolein as a starting compound.

本発明の反応帯に供給される原料流体は、前記原料化合物と分子状酸素を含む混合ガスであることが好ましく、反応帯に供給された前記ガスは触媒層で発熱を伴う気相酸化反応を起こし、前記原料化合物が酸化され、主生成物として対応するアルデヒドおよび／またはカルボン酸を生成する。分子状酸素としては、好適には、空気中の酸素分子が用いられる。また、原料流体は前記の原料化合物および分子状酸素の他、反応に不活性な窒素、二酸化炭素、水蒸気、あるいは、メタン、エタン、プロパンなどの飽和炭化水素を含んでいてもよい。   The raw material fluid supplied to the reaction zone of the present invention is preferably a mixed gas containing the raw material compound and molecular oxygen, and the gas supplied to the reaction zone undergoes a gas phase oxidation reaction accompanied by heat generation in the catalyst layer. The starting compound is oxidized to produce a corresponding aldehyde and / or carboxylic acid as a main product. As molecular oxygen, oxygen molecules in the air are preferably used. The raw material fluid may contain nitrogen, carbon dioxide, water vapor, or a saturated hydrocarbon such as methane, ethane, or propane, which is inert to the reaction, in addition to the raw material compound and molecular oxygen.

本発明の反応方法において、上記した以外の条件については、従来公知の方法と同様の条件で行うことができる。例えば、プロピレンの酸化反応であれば、プロピレン１〜１２容量％、分子状酸素２〜２０容量％、水蒸気０〜２５容量％、残りは窒素、二酸化炭素などの不活性ガスおよびプロパンなどからなる混合ガスを、熱媒体温度２８０〜４５０℃、空間速度（ＧＨＳＶ）３００〜５０００ｈ−１、反応圧力０．１〜１．０ＭＰａで触媒層を通過させることによって行うことができる。 In the reaction method of the present invention, conditions other than those described above can be performed under the same conditions as those of a conventionally known method. For example, in the case of an oxidation reaction of propylene, 1 to 12% by volume of propylene, 2 to 20% by volume of molecular oxygen, 0 to 25% by volume of steam, and the balance consisting of an inert gas such as nitrogen and carbon dioxide and propane. The gas can be performed by passing the gas through the catalyst layer at a heat medium temperature of 280 to 450 ° C., a space velocity (GHSV) of 300 to 5000 h −1 , and a reaction pressure of 0.1 to 1.0 MPa.

また、例えばアクロレインの酸化反応であれば、アクロレイン１〜１２容量％、分子状酸素２〜２０容量％、水蒸気０〜２５容量％、残りは窒素、二酸化炭素などの不活性ガスおよびプロパンからなる混合ガスを、熱媒体温度２００〜４００℃、空間速度（ＧＨＳＶ）３００〜８０００ｈ−１、反応圧力０．１〜１．０ＭＰａで触媒層を通過させることによって行なうことができる。 For example, in the case of an oxidation reaction of acrolein, 1 to 12% by volume of acrolein, 2 to 20% by volume of molecular oxygen, 0 to 25% by volume of steam, and the balance consisting of an inert gas such as nitrogen and carbon dioxide and propane. The gas can be carried out by passing the gas through the catalyst layer at a heating medium temperature of 200 to 400 ° C., a space velocity (GHSV) of 300 to 8000 h −1 , and a reaction pressure of 0.1 to 1.0 MPa.

以下、実施例を挙げて本発明をさらに具体的に説明するが、本発明はこれに限定されるものではない。なお、プロピレン転化率、ＣＯ２＋ＣＯ選択率、アクロレイン転化率、および、アクリル酸選択率の定義は、それぞれ次のとおりである。 Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited thereto. The definitions of the propylene conversion, the CO 2 + CO selectivity, the acrolein conversion, and the acrylic acid selectivity are as follows.

プロピレン転化率（モル％）＝（反応したプロピレンのモル数／供給したプロピレンのモル数）×１００
ＣＯ２＋ＣＯ選択率（モル％）＝［｛（生成したＣＯ２のモル数＋生成したＣＯのモル数）／３｝／（反応したプロピレンのモル数）］×１００
アクロレイン転化率（モル％）＝（反応したアクロレインのモル数）／（供給したアクロレインのモル数）×１００
アクリル酸選択率（モル％）＝（生成したアクリル酸のモル数）／（反応したアクロレインのモル数）×１００
＜プロピレン酸化用反応器＞
第１反応帯の管式熱交換型反応器として、ガス供給および排出用側管を備えた、内径３０ｍｍのステンレス製Ｕ字型反応管を用い、その内部に（１）外径１０ｍｍ、内径９．４ｍｍ、長さ６０ｍｍ、（２）外径８ｍｍ、内径７．４ｍｍ、長さ９０ｍｍ、（３）外径６ｍｍ、内径５．４ｍｍ、長さ１１０ｍｍの各サイズのステンレス管を外周部から中心部に向けて、管径が段階的に減少し管長が段階的に増大する順序で同心円状に配置してなる構造物を設置した。該構造物の中心部には、反応時に温度を計測する熱電対保護管（内径２ｍｍ、外径３ｍｍ、長さ３２０ｍｍ）を通した。該構造物は、触媒支持用目皿を有する熱電対保護管の目皿部に底面が接する位置に固定することによって反応管内部に設置した。 Propylene conversion (mol%) = (mol number of reacted propylene / mol number of supplied propylene) × 100
CO 2 + CO selectivity (mol%) = [{(mol number of generated CO 2 + mol number of generated CO) / 3} / (mol number of reacted propylene)] × 100
Acrolein conversion (mol%) = (mol number of reacted acrolein) / (mol number of supplied acrolein) × 100
Acrylic acid selectivity (mol%) = (mol number of generated acrylic acid) / (mol number of reacted acrolein) × 100
<Reactor for propylene oxidation>
As a tubular heat exchange reactor of the first reaction zone, a stainless U-shaped reaction tube having an inner diameter of 30 mm and a side pipe for gas supply and discharge was used, and (1) an outer diameter of 10 mm and an inner diameter of 9 were used. 0.4mm, length 60mm, (2) outer diameter 8mm, inner diameter 7.4mm, length 90mm, (3) outer diameter 6mm, inner diameter 5.4mm, stainless steel tube of each size 110mm in length from the outer periphery to the center In order to this, a structure was installed in which concentrically arranged pipes were arranged in the order in which the pipe diameter gradually decreased and the pipe length increased stepwise. A thermocouple protection tube (inner diameter 2 mm, outer diameter 3 mm, length 320 mm) for measuring the temperature during the reaction was passed through the center of the structure. The structure was installed inside the reaction tube by fixing it at a position where the bottom surface was in contact with the perforated portion of the thermocouple protective tube having a perforated plate for supporting the catalyst.

第２反応帯の熱交換しない反応器として、内径２８ｍｍのステンレス製管を用いた。なお、第１反応帯から排出される反応ガスが第２反応帯へ移動する際に、第２反応帯入口におけるガス温度が第１反応帯の熱媒体温度以上で維持されるよう、放熱を補償するためのヒーターを第２反応帯の反応器入口の前部に備えた。加えて、第２反応帯からの放熱を最小限に抑制するため、前記ステンレス製管の全周囲を巻きつけるように保温材を施した。   A stainless steel tube having an inner diameter of 28 mm was used as a reactor in the second reaction zone without heat exchange. When the reaction gas discharged from the first reaction zone moves to the second reaction zone, the heat radiation is compensated so that the gas temperature at the inlet of the second reaction zone is maintained at a temperature equal to or higher than the heat medium temperature of the first reaction zone. A heater was provided in front of the reactor inlet in the second reaction zone. In addition, in order to minimize the heat radiation from the second reaction zone, a heat insulating material was applied so as to wind around the entire stainless steel tube.

反応に際しては、各々の反応器に触媒を充填し、第１反応帯の反応器は溶融塩浴に浸漬して熱供給および除去されるようにし、この排出用測管と第２反応帯の反応器の入口を連結して性能を評価した。   During the reaction, each reactor is filled with a catalyst, and the reactor in the first reaction zone is immersed in a molten salt bath so that heat is supplied and removed. The inlet of the vessel was connected to evaluate the performance.

＜アクロレイン酸化用反応器＞
第１反応帯の管式熱交換型反応器として、ガス供給および排出用側管を備えた、内径２５ｍｍのステンレス製Ｕ字型反応管を用い、その内部に（１）外径１０ｍｍ、内径９．４ｍｍ、長さ５０ｍｍ、（２）外径８ｍｍ、内径７．４ｍｍ、長さ７０ｍｍ、（３）外径６ｍｍ、内径５．４ｍｍ、長さ８０ｍｍの各サイズのステンレス管を外周部から中心部に向けて、管径が段階的に減少し管長が段階的に増大する順序で同心円状に配置してなる構造物を設置したこと以外は、前記プロピレン酸化用反応器と同じであった。 <Acrolein oxidation reactor>
As a tubular heat exchange reactor of the first reaction zone, a stainless U-shaped reaction tube having an inner diameter of 25 mm and having a side pipe for gas supply and discharge was used, and (1) an outer diameter of 10 mm and an inner diameter of 9 were used. 0.4mm, length 50mm, (2) outer diameter 8mm, inner diameter 7.4mm, length 70mm, (3) outer diameter 6mm, inner diameter 5.4mm, stainless steel pipe of each size of 80mm length from the outer periphery to the center The reactor was the same as the propylene oxidation reactor described above, except that a structure was arranged concentrically in the order in which the tube diameter gradually decreased and the tube length increased stepwise.

＜プロピレン酸化用触媒＞
プロピレン酸化用触媒として特開２０１４−０６９１２８号公報の実施例１記載の方法に準じて球状アルミナ担持触媒を調製した。得られた触媒の外径は６ｍｍであった。一方、押出成形触媒として、同公報の実施例４記載の方法に準じて外径３ｍｍ、内径１ｍｍ、長さ３ｍｍのリング状触媒を調製した。前記リング状触媒の等体積球相当直径は約３．３ｍｍであった。なお、両触媒の触媒成分のみの金属元素組成は原子比でＭｏ１２Ｂｉ１．４Ｆｅ１．１Ｃｏ５．８Ｎｉ１．７Ｋ０．０９で同一となるよう、各原料の仕込み量を調整した。 <Propylene oxidation catalyst>
A spherical alumina-supported catalyst was prepared as a propylene oxidation catalyst according to the method described in Example 1 of JP-A-2014-069128. The outer diameter of the obtained catalyst was 6 mm. On the other hand, a ring-shaped catalyst having an outer diameter of 3 mm, an inner diameter of 1 mm, and a length of 3 mm was prepared as an extruded catalyst according to the method described in Example 4 of the publication. The equivalent volume sphere equivalent diameter of the ring-shaped catalyst was about 3.3 mm. The amount of each raw material was adjusted so that the metal element composition of only the catalyst components of both catalysts was the same in atomic ratio of Mo 12 Bi 1.4 Fe 1.1 Co 5.8 Ni 1.7 K 0.09. It was adjusted.

触媒活性序列の判定は、以下の手順で行なった。内径２５ｍｍのステンレス製Ｕ字型反応管に上記の触媒を５０ｍｌ充填した後、反応管を３００℃の溶融塩浴に浸した。反応管に、原料ガスとしてプロピレン２容量％、空気５８容量％、水蒸気４０容量％からなる混合ガスを６７．５ＮＬ／ｈの速度で供給することによってプロピレンの酸化を行った。原料ガス供給開始１時間後のプロピレン転化率は、球状アルミナ担持触媒が９３．９％、リング状触媒が９８．３％であった。   The determination of the catalytic activity order was performed according to the following procedure. After filling 50 ml of the above catalyst into a stainless U-shaped reaction tube having an inner diameter of 25 mm, the reaction tube was immersed in a 300 ° C. molten salt bath. Propylene was oxidized by supplying a mixed gas comprising 2% by volume of propylene, 58% by volume of air, and 40% by volume of steam as a raw material gas at a rate of 67.5 NL / h. One hour after the start of the supply of the raw material gas, the conversion of propylene was 93.9% for the spherical alumina-carrying catalyst and 98.3% for the ring catalyst.

＜プロピレンの酸化＞
（実施例１）
前記の構造物を充填した第１反応帯の反応器に、プロピレン酸化用触媒として前記の球状アルミナ担持触媒を５０ｍＬ充填した後、該反応管を３００℃の溶融塩浴に浸した。次いで、第２反応帯の反応器に、同じく前記の球状アルミナ担持触媒５０ｍＬを充填した後、両反応管を接続した。 <Oxidation of propylene>
(Example 1)
After filling 50 mL of the above-mentioned spherical alumina-supported catalyst as a catalyst for propylene oxidation into the reactor of the first reaction zone filled with the above structure, the reaction tube was immersed in a 300 ° C. molten salt bath. Next, the reactor in the second reaction zone was charged with 50 mL of the above-mentioned spherical alumina-supported catalyst, and then both reaction tubes were connected.

第１反応帯の反応器に、原料ガスとしてプロピレン２容量％、空気５８容量％、水蒸気４０容量％からなる混合ガスを２１０ＮＬ／ｈの速度で供給し、第２反応帯の反応器の入口のガス温度を３００℃に制御することでプロピレンの酸化を行った。原料ガス供給開始１時間後の第１反応帯出口のプロピレン転化率は６８．０％、ＣＯ２＋ＣＯ選択率は２．４％であり、第２反応帯出口のプロピレン転化率は８８．１％、ＣＯ２＋ＣＯ選択率は３．２％であった。 A mixed gas consisting of 2% by volume of propylene, 58% by volume of air, and 40% by volume of steam as a raw material gas is supplied to the reactor in the first reaction zone at a rate of 210 NL / h, and the gas at the inlet of the reactor in the second reaction zone is supplied. Propylene was oxidized by controlling the gas temperature to 300 ° C. One hour after the start of the supply of the raw material gas, the propylene conversion at the outlet of the first reaction zone was 68.0%, the CO 2 + CO selectivity was 2.4%, and the propylene conversion at the outlet of the second reaction zone was 88.1%. , CO 2 + CO selectivity was 3.2%.

（実施例２）
第２反応帯の反応器の入口のガス温度を３２０℃に制御したこと以外は実施例１と同様にして、プロピレンの酸化を行った。原料ガス供給開始１時間後の第１反応帯出口のプロピレン転化率、ＣＯ２＋ＣＯ選択率は実施例１と同じであり、第２反応帯出口のプロピレン転化率は９１．４％、ＣＯ２＋ＣＯ選択率は４．０％であった。 (Example 2)
Propylene was oxidized in the same manner as in Example 1 except that the gas temperature at the inlet of the reactor in the second reaction zone was controlled at 320 ° C. One hour after the start of the supply of the raw material gas, the propylene conversion and the CO 2 + CO selectivity at the outlet of the first reaction zone are the same as those in Example 1, and the propylene conversion at the outlet of the second reaction zone is 91.4% and CO 2 + CO. The selectivity was 4.0%.

（実施例３）
第２反応帯の反応器に充填する触媒として前記のリング状触媒５０ｍＬを用いたこと以外は実施例１と同様にして、プロピレンの酸化を行なった。原料ガス供給開始１時間後の第１反応帯出口のプロピレン転化率、ＣＯ２＋ＣＯ選択率は実施例１と同じであり、第２反応帯出口のプロピレン転化率は９１．５％、ＣＯ２＋ＣＯ選択率は２．８％であった。 (Example 3)
Propylene was oxidized in the same manner as in Example 1 except that 50 mL of the above-described ring catalyst was used as the catalyst charged in the reactor in the second reaction zone. One hour after the start of the feed of the raw material gas, the propylene conversion and the CO 2 + CO selectivity at the outlet of the first reaction zone are the same as those in Example 1, and the propylene conversion at the outlet of the second reaction zone is 91.5% and CO 2 + CO The selectivity was 2.8%.

（実施例４）
第２反応帯の反応器の入口のガス温度を３２０℃に制御したこと以外は実施例３と同様にして、プロピレンの酸化を行った。原料ガス供給開始１時間後の第１反応帯出口のプロピレン転化率、ＣＯ２＋ＣＯ選択率は実施例３と同じであり、第２反応帯出口のプロピレン転化率は９５．２％、ＣＯ２＋ＣＯ選択率は３．２％であった。 (Example 4)
Propylene was oxidized in the same manner as in Example 3 except that the gas temperature at the inlet of the reactor in the second reaction zone was controlled at 320 ° C. One hour after the start of the supply of the raw material gas, the propylene conversion and the CO 2 + CO selectivity at the outlet of the first reaction zone were the same as those in Example 3, and the propylene conversion at the outlet of the second reaction zone was 95.2% and CO 2 + CO. The selectivity was 3.2%.

（比較例１）
第１および第２反応帯の反応器をいずれも管式熱交換型反応器とし、ガス供給および排出用側管を備えた、内径２５ｍｍのステンレス製Ｕ字型反応管を用いた。プロピレン酸化用触媒として、前記の球状アルミナ担持触媒を第１および第２反応帯の反応器にそれぞれ５０ｍＬずつ充填し、それぞれの反応管を溶融塩浴に浸した後、それぞれを連結した。第１反応帯および第２反応帯の熱媒体温度を３００℃に設定し、第１反応帯の反応器に、原料ガスとしてプロピレン２容量％、空気５８容量％、水蒸気４０容量％からなる混合ガスを２１０ＮＬ／ｈの速度で供給し、プロピレン酸化を行なった。原料ガス供給開始１時間後の第１反応帯出口のプロピレン転化率は７６．９％、ＣＯ２＋ＣＯ選択率は２．４％であり、第２反応帯出口のプロピレン転化率は９２．０％、ＣＯ２＋ＣＯ選択率は３．０％であった。 (Comparative Example 1)
Each of the reactors in the first and second reaction zones was a tubular heat exchange reactor, and a stainless U-shaped reaction tube having an inner diameter of 25 mm and a gas supply and discharge side tube was used. As a catalyst for propylene oxidation, the above-mentioned spherical alumina-supported catalyst was charged into the reactors of the first and second reaction zones in a volume of 50 mL each, and the respective reaction tubes were immersed in a molten salt bath and then connected. The temperature of the heat medium in the first reaction zone and the second reaction zone was set to 300 ° C., and a mixed gas composed of 2% by volume of propylene, 58% by volume of air, and 40% by volume of steam as a raw material gas was supplied to a reactor in the first reaction zone. Was supplied at a rate of 210 NL / h to perform propylene oxidation. One hour after the start of the supply of the raw material gas, the propylene conversion at the outlet of the first reaction zone was 76.9%, the CO 2 + CO selectivity was 2.4%, and the propylene conversion at the outlet of the second reaction zone was 92.0%. , CO 2 + CO selectivity was 3.0%.

前記の実施例１〜４および比較例１の結果を、各反応帯の触媒層最高温度と共に表１に示す。   Table 1 shows the results of Examples 1 to 4 and Comparative Example 1 together with the maximum temperature of the catalyst layer in each reaction zone.

表１より、第１反応帯の反応器に構造物を設置することで触媒層の発熱抑制効果が発現されていることを確認できる。また、第２反応帯の触媒層最高温度は熱交換しない反応器の方が高くなっていることから、熱媒体を使用しなくとも触媒自体の発熱によって反応が自立し、断熱的に反応が進行していることが示された。これにより、第１および第２反応帯に充填されている触媒層全体にわたって効率的に反応を行なわせることが可能となっていることが分かる。さらに、第２反応帯出口における性能は、第２反応帯の反応器に第１反応帯の反応器よりも活性の高い触媒を充填した際に高くなり、特に実施例３と比較例１の比較において、通常の熱交換型反応器を使用した場合と同等の性能を示している。   From Table 1, it can be confirmed that the effect of suppressing the heat generation of the catalyst layer is exhibited by installing the structure in the reactor in the first reaction zone. In addition, since the maximum temperature of the catalyst layer in the second reaction zone is higher in the reactor that does not exchange heat, the reaction becomes independent by the heat generated by the catalyst itself without using a heating medium, and the reaction proceeds adiabatically. It was shown that. This indicates that the reaction can be efficiently performed over the entire catalyst layers filled in the first and second reaction zones. Further, the performance at the outlet of the second reaction zone becomes higher when the reactor in the second reaction zone is charged with a catalyst having a higher activity than the reactor in the first reaction zone. Shows the same performance as when a normal heat exchange reactor is used.

Figure 2020044485
Figure 2020044485

＜アクロレイン酸化用触媒＞
アクロレイン酸化用触媒として特開２０１５−１２０１３３号公報の実施例２記載の方法に準じて球状アルミナ担持触媒（大）を調製した。得られた触媒の外径は６ｍｍであった。また、同公報の同実施例の方法に準じて、平均粒径約１ｍｍの球状アルミナ担体を用い、球状アルミナ担持触媒（小）を調製した。得られた触媒の外径は外径３ｍｍであった。なお、両触媒の触媒成分のみの金属元素組成は原子比でＭｏ１２Ｖ５Ｗ１．４Ｃｕ１．８Ｓｂ０．５Ａｌ２．０で同一となるよう、各原料の仕込み量を調整した。 <Acrolein oxidation catalyst>
A spherical alumina-supported catalyst (large) was prepared as an acrolein oxidation catalyst according to the method described in Example 2 of JP-A-2015-120133. The outer diameter of the obtained catalyst was 6 mm. Further, a spherical alumina-supported catalyst (small) was prepared using a spherical alumina carrier having an average particle size of about 1 mm according to the method of the same example in the publication. The outer diameter of the obtained catalyst was 3 mm. The amounts of the raw materials charged were adjusted so that the metal element compositions of only the catalyst components of both catalysts were the same in atomic ratio of Mo 12 V 5 W 1.4 Cu 1.8 Sb 0.5 Al 2.0 . .

触媒活性序列の判定は、以下の手順で行なった。内径２５ｍｍのステンレス製Ｕ字型反応管に上記の触媒を５０ｍｌ充填した後、反応管を２３０℃の溶融塩浴に浸した。反応管に、原料ガスとしてアクロレイン２容量％、空気４８容量％、水蒸気１０容量％、窒素４０容量％からなる混合ガスを１００ＮＬ／ｈの速度で供給することによってアクロレインの酸化を行った。原料ガス供給開始１時間後のアクロレイン転化率は、球状アルミナ担持触媒（大）が８９．９％、球状アルミナ担持触媒（小）が９５．１％であった。   The determination of the catalytic activity order was performed according to the following procedure. After filling 50 ml of the above catalyst into a U-shaped stainless steel reaction tube having an inner diameter of 25 mm, the reaction tube was immersed in a molten salt bath at 230 ° C. Acrolein was oxidized by supplying a mixed gas consisting of 2% by volume of acrolein, 48% by volume of air, 10% by volume of steam, and 40% by volume of nitrogen as a raw material gas at a rate of 100 NL / h. One hour after the start of the supply of the raw material gas, the conversion of acrolein was 89.9% for the spherical alumina-supported catalyst (large) and 95.1% for the spherical alumina-supported catalyst (small).

＜アクロレインの酸化＞
（実施例５）
上記アクロレイン酸化用反応器を用い、第１反応帯の反応器に、アクロレイン酸化用触媒として前記の５０ｍＬの球状アルミナ担持触媒（大）を充填した後、該反応管を２３０℃の溶融塩浴に浸した。次いで、第２反応帯の反応器に、同じく５０ｍＬの球状アルミナ担持触媒（大）を充填した後、両反応管を接続した。第１反応帯の反応器に、原料ガスとしてアクロレイン２容量％、空気１９容量％、水蒸気１０容量％、残りが窒素からなる混合ガスを２００ＮＬ／ｈの速度で供給し、第２反応帯の熱交換しない反応器の入口のガス温度を２４０℃に制御することでアクロレインの酸化を行った。原料ガス供給開始１時間後の第１反応帯出口のアクロレイン転化率は５６．２％、アクリル酸選択率は９６．２％であり、第２反応帯出口のアクロレイン転化率は９２．３％、アクリル酸選択率は９６．０％であった。 <Acrolein oxidation>
(Example 5)
Using the above reactor for acrolein oxidation, the reactor in the first reaction zone was charged with the above-mentioned 50 mL of spherical alumina-supported catalyst (large) as a catalyst for acrolein oxidation, and then the reaction tube was placed in a 230 ° C. molten salt bath. Soaked. Next, the reactor in the second reaction zone was charged with 50 mL of the spherical alumina-supported catalyst (large) in the same manner, and then both reaction tubes were connected. A mixed gas consisting of 2% by volume of acrolein, 19% by volume of air, 10% by volume of steam, and the balance of nitrogen was supplied at a rate of 200 NL / h to the reactor in the first reaction zone at a rate of 200 NL / h. Acrolein was oxidized by controlling the gas temperature at the inlet of the reactor not to be exchanged to 240 ° C. One hour after the start of the supply of the raw material gas, the conversion of acrolein at the outlet of the first reaction zone was 56.2%, the selectivity of acrylic acid was 96.2%, and the conversion of acrolein at the outlet of the second reaction zone was 92.3%. The acrylic acid selectivity was 96.0%.

（実施例６）
第２反応帯の反応器に充填する触媒として前記の球状アルミナ担持触媒（小）５０ｍＬを用いたこと以外は実施例５と同様にして、アクロレインの酸化を行なった。原料ガス供給開始１時間後の第１反応帯出口のアクロレイン転化率、アクリル酸選択率、および触媒層出口側末端の温度は実施例５と同じであり、第２反応帯出口のアクロレイン転化率は９７．８％、アクリル酸選択率は９５．８％であった。 (Example 6)
Acrolein was oxidized in the same manner as in Example 5, except that 50 mL of the above-mentioned spherical alumina-supported catalyst (small) was used as the catalyst charged in the reactor in the second reaction zone. The acrolein conversion at the outlet of the first reaction zone, the selectivity of acrylic acid, and the temperature at the end of the catalyst layer at the outlet of the first reaction zone one hour after the start of the feed of the source gas were the same as those in Example 5, and the acrolein conversion at the outlet of the second reaction zone was 97.8%, acrylic acid selectivity was 95.8%.

前記の実施例５および６の結果を、各反応帯の触媒層最高温度と共に表２に示す。   Table 2 shows the results of Examples 5 and 6 together with the maximum temperature of the catalyst layer in each reaction zone.

表２より、上述の実施例１〜４と同様に、第２反応帯を熱交換しない反応器としても、自立して断熱的に反応が進行し、第１および第２反応帯を通して効率的に反応を行なわせることが可能となっていることを確認できる。加えて、第２反応帯出口の性能は、第２反応帯の反応器に第１反応帯よりも活性の高い触媒を充填した際により高い結果となっていることが示された。   From Table 2, similarly to Examples 1 to 4 described above, even in a reactor that does not exchange heat in the second reaction zone, the reaction proceeds independently and adiabatically, and efficiently proceeds through the first and second reaction zones. It can be confirmed that the reaction can be performed. In addition, the performance at the outlet of the second reaction zone was shown to be higher when the reactor in the second reaction zone was charged with a catalyst having higher activity than the first reaction zone.

Figure 2020044485
Figure 2020044485

本発明により、原料化合物として不飽和炭化水素および／または不飽和アルデヒドを気相接触酸化して対応するアルデヒドおよび／またはカルボン酸を製造するプロセスにおいて、触媒層前半は管式熱交換型固定床反応器様式の反応帯とし、触媒層後半を熱交換しない固定床反応器様式の反応帯とすることで、反応器全体を熱交換型の管式反応器とする場合に比べて、全体の反応バランスを維持しつつ、反応器全体の構造を簡便にかつ設置容積をコンパクトにでき、プラント建設費用を抑制できる。また、触媒層前半の反応帯中の反応管に局所的異常高温部を分散する機能を有する構造物を触媒と共に収めることで、触媒層前半の副生成物生成や触媒の損傷を抑制し、暴走反応の危険性を避けることができ、安全性の面からも優れている。さらに、触媒層後半の反応帯に充填する触媒の活性を、触媒層前半の反応帯に充填する触媒の活性以上とすることで、生産性も向上でき、経済性の面から、その産業上の利用価値はきわめて高い。   According to the present invention, in a process for producing a corresponding aldehyde and / or carboxylic acid by subjecting an unsaturated hydrocarbon and / or unsaturated aldehyde as a raw material compound to gas phase catalytic oxidation, the first half of the catalyst layer is a tubular heat exchange fixed bed reaction. By using a reactor type reaction zone and a fixed bed reactor type reaction zone that does not exchange heat in the latter half of the catalyst layer, the overall reaction balance can be reduced compared to the case where the entire reactor is a heat exchange type tubular reactor. , The structure of the whole reactor can be simplified and the installation volume can be made compact, and the plant construction cost can be suppressed. In addition, the structure that has the function of dispersing the local abnormally high temperature part in the reaction tube in the reaction zone in the first half of the catalyst layer together with the catalyst suppresses the formation of by-products in the first half of the catalyst layer and damage to the catalyst, resulting in runaway. The danger of reaction can be avoided, and it is excellent in terms of safety. Furthermore, by setting the activity of the catalyst packed in the reaction zone in the latter half of the catalyst layer to be higher than the activity of the catalyst packed in the reaction zone in the first half of the catalyst layer, productivity can be improved, and from the economical aspect, the industrial The utility value is extremely high.

１．第１反応帯
２．第２反応帯
３．反応管
４．構造物
５．第１反応帯の充填触媒
６．管板
７．第２反応帯の充填触媒
８．断熱層
９．中間層 1. 1. First reaction zone Second reaction zone 3. Reaction tube 4. Structure 5. 5. Packed catalyst in first reaction zone Tube sheet7. 7. Packed catalyst in second reaction zone Thermal insulation layer 9. Middle class

Claims (10)

触媒を充填した反応器に原料化合物としての不飽和炭化水素および／または不飽和アルデヒドを含有する原料流体を供給して気相接触酸化させる反応方法であって、
１本以上の反応管を備える管式熱交換型固定床反応器様式の第１反応帯、および、熱交換しない固定床反応器様式の第２反応帯を有する反応器を用い、
第１反応帯に充填される触媒体積をＶ１、第２反応帯に充填される触媒体積をＶ２としたとき、Ｖ１／（Ｖ１＋Ｖ２）を０．３以上０．８以下とし、
第１反応帯の反応管入口側より前記原料流体を供給して、前記原料流体中の前記原料化合物を３０％以上８０％未満の転化率で反応させて、未反応の原料化合物および反応生成物を含む流体を得、
前記未反応の原料化合物および反応生成物を含む流体を第２反応帯に導入して原料化合物をさらに転化させる
ことを特徴とする反応方法。 A reaction method for supplying a raw material fluid containing an unsaturated hydrocarbon and / or an unsaturated aldehyde as a raw material compound to a reactor filled with a catalyst and performing gas phase catalytic oxidation,
A reactor having a first reaction zone of a tubular heat exchange type fixed bed reactor type having one or more reaction tubes, and a second reaction zone of a fixed bed reactor type not performing heat exchange,
When the volume of the catalyst filled in the first reaction zone is V1 and the volume of the catalyst filled in the second reaction zone is V2, V1 / (V1 + V2) is 0.3 or more and 0.8 or less,
The raw material fluid is supplied from the reaction tube inlet side of the first reaction zone, and the raw material compounds in the raw material fluid are reacted at a conversion of 30% or more and less than 80%, and unreacted raw material compounds and reaction products Obtaining a fluid containing
A reaction method comprising introducing a fluid containing the unreacted raw material compound and a reaction product into a second reaction zone to further convert the raw material compound. 前記第１反応帯中の前記反応管内部において、端部または途中から他方の端部に向けて連続的または段階的に体積が減少する形状を有する構造物が、前記構造物の最小端面が反応管出口側に向けて設置されている、請求項１に記載の反応方法。 In the inside of the reaction tube in the first reaction zone, a structure having a shape in which the volume is reduced continuously or stepwise from one end or the other end toward the other end is such that the minimum end face of the structure reacts. The reaction method according to claim 1, wherein the reaction method is installed toward a pipe outlet side. 前記の第２反応帯に充填される触媒の活性が、前記第１反応帯に充填される触媒の活性以上である、請求項１または請求項２に記載の反応方法。 The reaction method according to claim 1 or 2, wherein the activity of the catalyst charged in the second reaction zone is equal to or higher than the activity of the catalyst charged in the first reaction zone. 前記気相接触酸化により、前記原料化合物に対応するアルデヒドおよび／またはカルボン酸を得る、請求項１から請求項３のいずれか一項に記載の反応方法。 The reaction method according to any one of claims 1 to 3, wherein an aldehyde and / or a carboxylic acid corresponding to the raw material compound is obtained by the gas phase catalytic oxidation. 前記原料化合物が、プロピレン、イソブチレン、アクロレインおよびメタクロレインから選ばれる少なくとも１つである、請求項１から請求項４のいずれか一項に記載の反応方法。 The reaction method according to any one of claims 1 to 4, wherein the raw material compound is at least one selected from propylene, isobutylene, acrolein, and methacrolein. 気相接触酸化反応に用いるための反応器であって、１本以上の反応管を備える管式熱交換型固定床反応器様式の第１反応帯、および、熱交換しない固定床反応器様式の第２反応帯を有することを特徴とする反応器。 A reactor for use in a gas phase catalytic oxidation reaction, wherein a first reaction zone of a tubular heat exchange fixed bed reactor type having one or more reaction tubes and a fixed bed reactor type of no heat exchange are provided. A reactor having a second reaction zone. 前記第１反応帯と前記第２反応帯を同一反応器内に備えてなる、請求項６に記載の反応器。 The reactor according to claim 6, wherein the first reaction zone and the second reaction zone are provided in the same reactor. 前記第１反応帯と前記第２反応帯がそれぞれ独立した反応器であって、各反応器が導管によって接続されてなる、請求項６に記載の反応器。 The reactor according to claim 6, wherein the first reaction zone and the second reaction zone are independent reactors, and each reactor is connected by a conduit. 前記第１反応帯中の前記反応管内部において、端部または途中から他方の端部に向けて連続的または段階的に体積が減少する形状を有する構造物が、前記構造物の最小端面が反応管出口側に向けて設置されている、請求項６から請求項８のいずれか一項に記載の反応器。 In the inside of the reaction tube in the first reaction zone, a structure having a shape in which the volume is reduced continuously or stepwise from one end or the other end toward the other end is such that the minimum end face of the structure reacts. The reactor according to any one of claims 6 to 8, which is installed toward a pipe outlet side. 前記気相接触酸化反応が、触媒を充填した反応器に原料化合物としての不飽和炭化水素および／または不飽和アルデヒドを含有する原料流体を供給して対応するアルデヒドおよび／またはカルボン酸を得る反応である、請求項６から請求項９のいずれか一項に記載の反応器。 The gas phase catalytic oxidation reaction is a reaction in which a raw material fluid containing an unsaturated hydrocarbon and / or an unsaturated aldehyde as a raw material compound is supplied to a reactor filled with a catalyst to obtain a corresponding aldehyde and / or carboxylic acid. The reactor according to any one of claims 6 to 9, wherein
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