JP3792449B2 - Purification method of methacrylic acid - Google Patents

Purification method of methacrylic acid Download PDF

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Publication number
JP3792449B2
JP3792449B2 JP24794699A JP24794699A JP3792449B2 JP 3792449 B2 JP3792449 B2 JP 3792449B2 JP 24794699 A JP24794699 A JP 24794699A JP 24794699 A JP24794699 A JP 24794699A JP 3792449 B2 JP3792449 B2 JP 3792449B2
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Japan
Prior art keywords
methacrylic acid
containing compound
formaldehyde
ion exchange
exchange resin
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JP24794699A
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Japanese (ja)
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JP2001072639A (en
Inventor
康一 吉田
求 大北
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Mitsubishi Chemical Corp
Mitsubishi Rayon Co Ltd
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Mitsubishi Chemical Corp
Mitsubishi Rayon Co Ltd
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  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Description

【0001】
【産業上の利用分野】
本発明は、メタクロレインとメタノールからパラジウム含有化合物を用いて液相で製造されたメタクリル酸の精製法に関する。
【0002】
【従来の技術】
イソブタン、イソブチレン、第3級ブチルアルコール、メチル第3級ブチルエーテル、メタクロレイン、イソブチルアルデヒド、イソ酪酸等を気相接触酸化して得られたメタクリル酸を第1級および/または第2級のアミノ基含有化合物、強酸性イオン交換樹脂、ならびに、ホルムアルデヒド含有物および強酸性イオン交換樹脂を用いて精製する方法は、特開平11−60536号公報に記載されており公知である。
また、メタクロレインとメタノールからパラジウム含有化合物を用いて液相反応でメタクリル酸メチルおよびメタクリル酸を製造する方法(以下、液相直メタ法という。)は、たとえば、特公昭61−19090号公報、特公昭62−7902号公報、特開平5−148184号公報、特開平9−216850号公報、特開平9−221453号公報および特開平10−158214号公報等に記載されている。
【0003】
【発明が解決しようとする課題】
しかしながら、液相直メタ法で製造されたメタクリル酸は、不純物の影響で着色したり、重合性が著しく劣る等の問題がある。このような不純物には沸点がメタクリル酸に近いものがあり、通常の抽出や蒸留等運転上容易な手段でこのような不純物を含むメタクリル酸を精製することは極めて困難であった。
【0004】
本発明の目的は、メタクロレインとメタノールからパラジウム含有化合物を用いて液相反応で製造された着色要因物質および/または重合阻害要因物質を含有するメタクリル酸から、着色が少なく、重合性能に優れた高品質なメタクリル酸を高収率で得ることのできる運転上容易な精製法を提供することにある。
【0005】
【課題を解決するための手段】
本発明は、メタクロレインとメタノールからパラジウム含有化合物を用いて液相反応で製造されたメタクリル酸の精製法であって、当該メタクリル酸に第1級および/または第2級のアミノ基含有化合物を接触させる工程、当該メタクリル酸に強酸性イオン交換樹脂を接触させる工程、ならびに当該メタクリル酸にホルムアルデヒド含有物およびスルホン酸基含有化合物を接触させる工程、を含むメタクリル酸の精製法である。
【0006】
【発明の実施の形態】
本発明の精製対象であるメタクリル酸は、液相直メタ法で得られるものである。液相直メタ法の原料であるでメタクロレインの製造方法は特に限定されないが、炭素数4の化合物を気相接触酸化して得られたものが適している。炭素数4の化合物としては、例えば、イソブタン、イソブチレン、第3級ブチルアルコール、メチル第3級ブチルエーテル等が挙げられる。メチル第3級ブチルエーテルの炭素数は5であるが、気相接触酸化の際に直ちに分解して、炭素数4のイソブチレンが得られることから、ここでは炭素数4の化合物として取り扱う。
【0007】
パラジウム含有化合物は、少なくともパラジウムを含有していることが必須であり、パラジウム以外の構成元素については特に限定されない。この化合物は液相直メタ法の触媒として作用するもので、好ましくはパラジウムおよびX(ここにXはテルル、水銀、タリウム、鉛およびビスマスからなる群より選ばれた少なくとも一種の元素を示す。)、または、パラジウムおよびXおよびY(ここにYはマグネシウム、アルミニウム、カルシウム、チタン、クロム、マンガン、鉄、コバルト、ニッケル、銅、亜鉛、ゲルマニウム、銀、錫、アンチモン、バリウムおよびセリウムからなる群より選ばれた少なくとも一種の元素を示す。)である。
【0008】
パラジウム含有化合物は、通常、シリカ、アルミナ、シリカ−アルミナ、シリカ−マグネシア、酸化亜鉛、炭酸カルシウム、炭酸バリウム、活性炭、ケイソウ土、ゼオライト等の各種の担体に担持したものが触媒として用いられるが、これに限定されることはなく、構成される成分のみからなる触媒であってもよい。
【0009】
本発明によって精製されるメタクリル酸は、前記した液相直メタ法で製造されるメタクリル酸およびメタクリル酸メチルの混合物から抽出および蒸留等の分離精製工程を経て得られるものである。本発明は、該工程を経てメタクリル酸の含有率が約90重量%以上に濃縮されたものが精製対象として適切であるが、この分離精製の有無、メタクリル酸濃度に制限されることはない。すなわち、上記反応工程中で得られるメタクリル酸メチルとメタクリル酸の混合物の状態で、しかもメタクリル酸の濃度がメタクリル酸メチルより低い場合でも精製処理の対象とすることができる。このような観点から、以下、本発明の精製法の対象となるメタクリル酸をメタクリル酸含有物と表記する。これらメタクリル酸含有物は、着色要因物質および/または重合阻害要因物質を含有しており、これらは液相直メタ法で生じたものだけでなく、原料メタクロレインに由来するものもある。
【0010】
液相直メタ法を実施する際、メタノールの量はメタクロレイン1モルに対して0.1〜100モルであり、好ましくは0.5〜5モル、より好ましくは1〜3モルである。また、反応形式は特に限定されず、回分式、半回分式、連続式の何れでもよい。触媒として使用するパラジウム含有化合物の量は、所望の転化率等を考慮して決定される。反応に必要な分子状酸素の量については特に限定はないが、メタクロレイン1モルに対して通常0.05〜2モルであり、好ましくは0.1〜0.5モルである。分子状酸素源としては空気、酸素冨化した空気、酸素、反応に不活性なガスで希釈した酸素や空気が用いられる。反応温度は0〜200℃であり、好ましくは50〜150℃である。反応圧力は、常圧、加圧および減圧の何れでもよいが、好ましくは常圧〜0.4MPaである。
【0011】
本発明は、液相直メタ法で得られた着色要因物質および/または重合阻害要因物質を含むメタクリル酸含有物に、第1級および/または第2級のアミノ基含有化合物、強酸性イオン交換樹脂、ならびに、ホルムアルデヒド含有物およびスルホン酸基含有化合物を接触させることからなる。
【0012】
本発明で用いる第1級または第2級のアミノ基含有化合物としては、脂肪族、芳香族アミンの何れでもよく、1分子中に複数個のアミノ基を有するアミン類、アンモニア、ヒドラジンおよびその誘導体、さらには、ヒドロキシルアミンおよびその無機酸塩等の化合物が含まれる。第1級または第2級のアミノ基含有化合物としては、たとえばプロピルアミン、ブチルアミン、ペンチルアミン、ヘキシルアミン、ジエチルアミン、ジ−n−プロピルアミン、ジイソプロピルアミン、メチルエチルアミン、エチレンジアミン、トリメチレンジアミン、テトラメチレンジアミン、ペンタメチレンジアミン、N, N’−ジフェニルエチレンジアミン、エタノールアミン、ヘキサメチレンジアミン、ジエチレントリアミン、テトラエチレンペンタミン、アニリン、トルイジン、N−エチルアニリン、N−プロピルアミン、ジフェニルアミン、フェニレンジアミン、N−メチルフェニレンジアミン、ベンジルアミン、フェネチルアミン、アニシジン等が挙げられる。
【0013】
これら、第1級および/または第2級のアミノ基含有化合物を接触させる際の添加量は、メタクリル酸含有物100重量部に対して、0.001〜1重量部であり、特に0.005〜0.8重量部の範囲が好ましい。
【0014】
また、本発明で用いる強酸性イオン交換樹脂は、交換容量、架橋度等に関して特に規定はない。強酸性イオン交換樹脂は、回分式、連続式何れの方法で用いてもよい。その使用量は、回分式ではメタクリル酸含有物100重量部に対して、0.1〜50重量部、特に1〜30重量部の範囲が好ましい。連続式ではメタクリル酸含有物の流通量は強酸性イオン交換樹脂に対して空間速度で0.01〜10hr-1、特に0.05〜5hr-1の範囲が好ましい。
【0015】
本発明で用いるホルムアルデヒド含有物としては、ホルムアルデヒドのほか、ホルムアルデヒドを生成し得る化合物、たとえば、パラホルムアルデヒド等も用いることができる。通常は、ホルマリンとして市販されているホルムアルデヒド水溶液が用いられる。その使用量は、メタクリル酸含有物に対して、ホルムアルデヒドの重量比で10〜10000ppm、特に50〜5000ppmの範囲が好ましい。
【0016】
ホルムアルデヒド含有化合物は、スルホン酸基含有化合物と共に用いなければならない。ホルムアルデヒド含有化合物を単独で用いた場合にはメタクリル酸含有物に含まれる不純物の除去効果は乏しい。スルホン酸基含有化合物は、スルホン酸基を分子内に有する無機または有機化合物を意味し、たとえば、硫酸、ベンゼンスルホン酸、p−トルエンスルホン酸、メタンスルホン酸、スルホン酸基を交換基として有する強酸性イオン交換樹脂等が挙げられる。スルホン酸基含有化合物は、回分式、連続式何れの方法で用いてもよい。使用量は、回分式ではメタクリル酸含有物100重量部に対して、0.1〜50重量部、特に1〜30重量部の範囲が好ましい。また、強酸性イオン交換樹脂を連続式で用いた場合には、メタクリル酸含有物の流通量は強酸性イオン交換樹脂に対して空間速度で0.01〜10hr-1、特に0.05〜5hr-1の範囲が好ましい。
【0017】
本発明の精製法を実施するには、第1級および/または第2級のアミノ基含有化合物を接触させる工程、強酸性イオン交換樹脂を接触させる工程、ならびに、ホルムアルデヒド含有物およびスルホン酸基含有化合物を接触させる工程をどのような順序で行ってもよいが、本発明は、これら3つの工程を必須とするところに特徴がある。
【0018】
第1級および/または第2級のアミノ基含有化合物を接触させる工程としては、たとえば、メタクリル酸含有物にアミノ基含有化合物を添加して、所定の温度に加熱した後、好ましくは混合物を撹拌しながら一定時間保持する方法が用いられる。このときの温度は50〜150℃、特に80〜130℃の範囲が好ましい。接触させる時間は5分〜5時間、特に15分〜3時間の範囲が好ましい。
【0019】
強酸性イオン交換樹脂を接触させる工程としては、回分式、連続式何れの方法でも行えるが、固定床で流通接触させる方法が好ましい。このときの温度は20〜150℃、特に40〜130℃の範囲が好ましい。回分式の場合、接触させる時間は5分〜5時間、特に15分〜3時間の範囲が好ましい。
【0020】
ホルムアルデヒド含有物およびスルホン酸基含有化合物を接触させる工程は、回分式、連続式何れの方法でも行えるが、スルホン酸基を交換基として有する強酸性イオン交換樹脂等の固体触媒を充填した固定床にホルムアルデヒド含有物を加えたメタクリル酸含有物を流通させる方法が好ましい。このときの温度は20〜150℃、特に40〜130℃の範囲が好ましい。回分式の場合、接触させる時間は5分〜5時間、特に15分〜3時間の範囲が好ましい。
【0021】
第1級および/または第2級のアミノ基含有化合物を接触させる工程を行った後の液は、そのまま次の処理工程に通してもよいが、蒸留した後に次の工程を行った方が好ましい。また、強酸性イオン交換樹脂を接触させる工程またはホルムアルデヒド含有物およびスルホン酸基含有化合物を接触させる工程後の液は、そのまま次の工程を実施しても、蒸留した後に次の工程を行ってもよい。接触させた液は、最終的に蒸留等によって未反応の第1級および/または第2級のアミノ基含有化合物、強酸性イオン交換樹脂、ホルムアルデヒド含有物およびスルホン酸基含有化合物(以下、処理剤という。)や、処理剤と着色要因物質や重合阻害要因物質との反応物をメタクリル酸から分離するが、このとき、フェノチアジン、ベンゾフェノチアジン等の重合禁止剤を添加しておくことが好ましい。
【0022】
【実施例】
以下、本発明を実施例によりさらに詳しく説明するが、本発明は、これらに限定されるものではない。
実施例および比較例中のメタクリル酸の純度は、重量百分率を意味する。また、メタクリル酸の回収率は、次式により定義される。
回収率(%)= B/A×100
式中のAおよびBは、
A:精製前のメタクリル酸含有物中のメタクリル酸の重量
B:精製後のメタクリル酸含有物中のメタクリル酸の重量
を意味する。
【0023】
[実施例1]
イソブチレンの気相接触酸化反応で得られたメタクロレインからメタノールと5重量%パラジウム−3重量%ビスマスをシリカに担持させた触媒を用いて液相反応でメタクリル酸およびメタクリル酸メチルの混合液を得た。得られた混合液から抽出および蒸留によって、純度99.0重量%のメタクリル酸含有物を得た。このものの色数はAPHA78であった。
【0024】
得られたメタクリル酸含有物100gに重合禁止剤としてフェノチアジン0.05gを添加し、次にエチレンジアミン0.05gを添加して100℃で2時間接触させた。次いで、1.3kPa減圧下で単蒸留して得たメタクリル酸に、重合禁止剤としてハイドロキノン0.02gを添加し、強酸性イオン交換樹脂「アンバーリスト15E」(商品名、ロームアンドハース社製、以下同じ)2.5gを添加し、100℃で1時間接触させた。この液からデカンテーションによってイオン交換樹脂を取り除いた後、ホルムアルデヒド35重量%を含有した水溶液を、メタクリル酸含有物に対してホルムアルデヒドの含有比が100ppmとなるように加えた。「アンバーリスト15E」5gをガラス製U字管に固定し、80℃の恒温下でホルムアルデヒドを加えたメタクリル酸含有物を空間速度0.2hr-1で流通接触させた。次いで、1.3kPa減圧下で単蒸留を行い、精製メタクリル酸を94%の回収率で回収した。
【0025】
このようにして得られた精製メタクリル酸の色数は、APHA3に改善された。さらに、得られたメタクリル酸について次の方法で重合性能の指標である誘導期間を測定した。試験管にメタクリル酸100mlとハイドロキノンモノメチルエーテル5mgおよび重合促進剤として過酸化ベンゾイル0.1gを加えて溶解する。これに水10mlを加え、温度65℃の恒温槽に浸漬し、熱電対を用いて温度を測定し、65℃より液温が上昇した時点、すなわち、重合熱の発生し始めた時点の時間を測定し、それまでに要した時間を誘導期間(以下同じ)とする。本実施例によって得た精製メタクリル酸の誘導期間は8.0分であった。
【0026】
[実施例2]
エチレンジアミン0.05gの代わりに、N,N’−ジフェニルエチレンジアミン0.10gを使用したほかは実施例1と同じ条件で精製を行った。得られた精製メタクリル酸の回収率は93.1%で、色数はAPHA4であり、誘導期間は8.5分であった。
【0027】
[実施例3]
エチレンジアミン0.05gの代わりに、ヒドラジン0.03gおよびN,N’−ジフェニルエチレンジアミン0.05gを使用したほかは実施例1と同じ条件で精製を行った。得られた精製メタクリル酸の回収率は92.8%で、色数はAPHA3であり、誘導期間は8.0分であった。
【0028】
[実施例4]
イソブチレンの気相接触酸化で得られたメタクロレインからメタノールと5重量%パラジウム−3重量%ビスマスをシリカに担持させた触媒を用いて液相反応でメタクリル酸およびメタクリル酸メチルの混合液を得た。得られた混合液から抽出および蒸留によって純度99.1重量%のメタクリル酸含有物を得た。このものの色数はAPHA80であった。
【0029】
得られたメタクリル酸含有物100gに重合禁止剤としてハイドロキノン0.02gを添加し、強酸性イオン交換樹脂「アンバーリスト15E」2.5gを添加して、100℃で1時間接触させた。デカンテーションによってイオン交換樹脂を取り除いた後、エチレンジアミン0.05gを添加して100℃で2時間接触させた。次いで、1.3kPa減圧下で単蒸留を行い、得られたメタクリル酸にホルムアルデヒド35重量%を含有した水溶液をメタクリル酸含有物に対しホルムアルデヒドの含有比が100ppmとなるように加えた。「アンバーリスト15E」5gをガラス製U字管に固定し、80℃の恒温下でホルムアルデヒドを加えたメタクリル酸含有物を空間速度0.2hr-1で流通接触させた。次いで1.3kPa減圧下で単蒸留を行い、精製メタクリル酸を93.2%の回収率で回収した。得られた精製メタクリル酸の色数はAPHA3であり、誘導期間は8.5分であった。
【0030】
[実施例5]
イソブチレンの気相接触酸化で得られたメタクロレインからメタノールと5重量%パラジウム−3重量%ビスマスをシリカに担持させた触媒を用いて液相反応でメタクリル酸およびメタクリル酸メチルの混合液を得た。得られた混合液から抽出および蒸留によって純度99.0%のメタクリル酸含有物を得た。このものの色数はAPHA72であった。
【0031】
このメタクリル酸含有物100gに重合禁止剤としてフェノチアジン0.05gを添加し、次にエチレンジアミン0.05gを添加して100℃で2時間接触させた。次いで、1.3kPa減圧下で単蒸留して得たメタクリル酸含有物に、重合禁止剤としてハイドロキノン0.02gを添加し、ホルムアルデヒド35重量%を含有した水溶液をメタクリル酸含有物に対してホルムアルデヒドの含有比が100ppmとなるように加えた。「アンバーリスト15E」5gをガラス製U字管に固定し、80℃の恒温下でホルムアルデヒドを加えたメタクリル酸含有物を空間速度0.2hr-1で流通接触させた。この液に対して強酸性イオン交換樹脂「アンバーリスト15E」2.5gを添加し、100℃で1時間接触させた。次いで、1.3kPa減圧下で単蒸留を行い、精製メタクリル酸を94%の回収率で回収した。得られた精製メタクリル酸の色数はAPHA2であり、誘導期間は7.9分であった。
【0032】
[比較例1]
ホルムアルデヒドを添加しなかった以外は実施例1と同様にしてメタクリル酸を精製した。その結果、精製メタクリル酸の回収率は93.0%、色数はAPHA20、誘導期間は10.0分であった。この例では、実施例1に比べて色数が悪化した。
【0033】
[比較例2]
強酸性イオン交換樹脂「アンバーリスト15E」2.5gを添加し、100℃で1時間接触させる処理を行わなかった以外は、実施例1と同様にしてメタクリル酸含有物を精製した。その結果、精製メタクリル酸の回収率は93.5%、色数はAPHA7、誘導期間は18.0分であった。この例では、実施例1に比べて色数および誘導期間がともに悪化した。
【0034】
[比較例3]
エチレンジアミンを接触させる処理を行わなかった以外は、実施例1と同様にしてメタクリル酸含有物を精製した。その結果、精製メタクリル酸の回収率は93.0%、色数はAPHA15、誘導期間は12.0分であった。この例では、実施例1に比べて色数および誘導期間がともに悪化した。
【0035】
【発明の効果】
本発明によれば、メタクロレインとメタノールからパラジウム含有化合物を用いて液相反応で製造された着色要因物質および/または重合阻害要因物質を含有するメタクリル酸含有物から、従来の方法に比較して少量の処理剤で着色が少なく、重合性能に優れた高品質なメタクリル酸を運転上容易に高収率で得ることができる。
[0001]
[Industrial application fields]
The present invention relates to a method for purifying methacrylic acid produced in a liquid phase from methacrolein and methanol using a palladium-containing compound.
[0002]
[Prior art]
Methacrylic acid obtained by gas phase catalytic oxidation of isobutane, isobutylene, tertiary butyl alcohol, methyl tertiary butyl ether, methacrolein, isobutyraldehyde, isobutyric acid, etc. is converted into primary and / or secondary amino groups. Methods for purification using a compound containing compound, a strongly acidic ion exchange resin, and a formaldehyde-containing material and a strongly acidic ion exchange resin are described in JP-A-11-60536 and are known.
Further, a method for producing methyl methacrylate and methacrylic acid by liquid phase reaction using methacrolein and methanol from a palladium-containing compound (hereinafter referred to as liquid phase direct meta method) is disclosed in, for example, Japanese Patent Publication No. 61-19090, These are described in JP-B-62-2902, JP-A-5-148184, JP-A-9-216850, JP-A-9-212453, JP-A-10-158214, and the like.
[0003]
[Problems to be solved by the invention]
However, methacrylic acid produced by the liquid phase direct meta method has problems such as coloring due to the influence of impurities and extremely poor polymerization. Some of these impurities have a boiling point close to that of methacrylic acid, and it has been extremely difficult to purify methacrylic acid containing such impurities by means that are easy to operate such as normal extraction and distillation.
[0004]
An object of the present invention is that methacrylic acid containing a color factor substance and / or a polymerization inhibitory factor substance produced by liquid phase reaction from methacrolein and methanol using a palladium-containing compound is less colored and has excellent polymerization performance. It is an object of the present invention to provide a purification method which is easy to operate and can obtain high quality methacrylic acid in a high yield.
[0005]
[Means for Solving the Problems]
The present invention relates to a method for purifying methacrylic acid produced by liquid phase reaction from methacrolein and methanol using a palladium-containing compound , wherein the methacrylic acid is mixed with a primary and / or secondary amino group-containing compound. A method for purifying methacrylic acid, comprising a step of bringing a methacrylic acid into contact with a strongly acidic ion exchange resin, and a step of bringing the methacrylic acid into contact with a formaldehyde-containing substance and a sulfonic acid group-containing compound.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The methacrylic acid which is the purification target of the present invention is obtained by a liquid phase direct meta method. The method for producing methacrolein, which is a raw material for the liquid phase direct meta method, is not particularly limited, but a product obtained by vapor phase catalytic oxidation of a compound having 4 carbon atoms is suitable. Examples of the compound having 4 carbon atoms include isobutane, isobutylene, tertiary butyl alcohol, and methyl tertiary butyl ether. Although methyl tertiary butyl ether has 5 carbon atoms, it is immediately decomposed during vapor-phase catalytic oxidation to obtain isobutylene having 4 carbon atoms. Therefore, it is treated here as a compound having 4 carbon atoms.
[0007]
It is essential that the palladium-containing compound contains at least palladium, and constituent elements other than palladium are not particularly limited. This compound acts as a catalyst for a liquid phase direct meta method, preferably palladium and X (where X represents at least one element selected from the group consisting of tellurium, mercury, thallium, lead and bismuth). Or palladium and X and Y (where Y is from the group consisting of magnesium, aluminum, calcium, titanium, chromium, manganese, iron, cobalt, nickel, copper, zinc, germanium, silver, tin, antimony, barium and cerium) Represents at least one selected element).
[0008]
The palladium-containing compound is usually used as a catalyst supported on various carriers such as silica, alumina, silica-alumina, silica-magnesia, zinc oxide, calcium carbonate, barium carbonate, activated carbon, diatomaceous earth, zeolite, It is not limited to this, The catalyst which consists only of the component comprised may be sufficient.
[0009]
The methacrylic acid purified by the present invention is obtained from a mixture of methacrylic acid and methyl methacrylate produced by the liquid phase direct meta method, through a separation and purification process such as extraction and distillation. In the present invention, a product obtained by concentrating the content of methacrylic acid to about 90% by weight or more through this step is suitable as a purification target, but is not limited to the presence or absence of this separation purification and the methacrylic acid concentration. That is, even in the state of a mixture of methyl methacrylate and methacrylic acid obtained in the above reaction step, and when the concentration of methacrylic acid is lower than that of methyl methacrylate, it can be subjected to purification treatment. From such a point of view, hereinafter, methacrylic acid which is the subject of the purification method of the present invention will be referred to as a methacrylic acid-containing substance. These methacrylic acid-containing materials contain a color-causing substance and / or a polymerization-inhibiting substance, which are not only those produced by the liquid-phase direct meta method but also derived from raw material methacrolein.
[0010]
When carrying out the liquid phase direct meta process, the amount of methanol is 0.1 to 100 mol, preferably 0.5 to 5 mol, more preferably 1 to 3 mol, relative to 1 mol of methacrolein. The reaction format is not particularly limited, and may be any of batch, semi-batch and continuous. The amount of the palladium-containing compound used as the catalyst is determined in consideration of the desired conversion rate and the like. Although there is no limitation in particular about the quantity of molecular oxygen required for reaction, it is 0.05-2 mol normally with respect to 1 mol of methacrolein, Preferably it is 0.1-0.5 mol. As the molecular oxygen source, air, oxygen-enriched air, oxygen, oxygen diluted with a gas inert to the reaction, or air is used. The reaction temperature is 0 to 200 ° C, preferably 50 to 150 ° C. The reaction pressure may be any of normal pressure, pressurization, and reduced pressure, but is preferably normal pressure to 0.4 MPa.
[0011]
The present invention relates to a methacrylic acid-containing material containing a coloring factor substance and / or a polymerization inhibitory factor substance obtained by a liquid phase direct meta method, a primary and / or secondary amino group-containing compound, and a strongly acidic ion exchange. The resin and the formaldehyde-containing material and the sulfonic acid group-containing compound are contacted.
[0012]
The primary or secondary amino group-containing compound used in the present invention may be any of aliphatic and aromatic amines, amines having a plurality of amino groups in one molecule, ammonia, hydrazine and derivatives thereof. Furthermore, compounds such as hydroxylamine and its inorganic acid salt are included. Examples of the primary or secondary amino group-containing compound include propylamine, butylamine, pentylamine, hexylamine, diethylamine, di-n-propylamine, diisopropylamine, methylethylamine, ethylenediamine, trimethylenediamine, and tetramethylene. Diamine, pentamethylenediamine, N, N'-diphenylethylenediamine, ethanolamine, hexamethylenediamine, diethylenetriamine, tetraethylenepentamine, aniline, toluidine, N-ethylaniline, N-propylamine, diphenylamine, phenylenediamine, N-methyl Examples include phenylenediamine, benzylamine, phenethylamine, and anisidine.
[0013]
The amount of the primary and / or secondary amino group-containing compound to be brought into contact is 0.001 to 1 part by weight, particularly 0.005, per 100 parts by weight of the methacrylic acid-containing compound. A range of ˜0.8 parts by weight is preferred.
[0014]
Further, the strongly acidic ion exchange resin used in the present invention is not particularly defined with respect to the exchange capacity, the degree of crosslinking and the like. The strongly acidic ion exchange resin may be used by either a batch method or a continuous method. The amount used is preferably in the range of 0.1 to 50 parts by weight, particularly 1 to 30 parts by weight, based on 100 parts by weight of the methacrylic acid-containing material in batch mode. Circulation amount of the methacrylic acid content in the continuous mode 0.01~10Hr -1 in space velocity relative to the strongly acidic ion-exchange resin, in particular in the range of 0.05~5Hr -1 are preferred.
[0015]
As the formaldehyde-containing material used in the present invention, in addition to formaldehyde, compounds capable of generating formaldehyde, such as paraformaldehyde, can be used. Usually, a formaldehyde aqueous solution marketed as formalin is used. The amount of use is preferably in the range of 10 to 10000 ppm, particularly 50 to 5000 ppm by weight of formaldehyde with respect to the methacrylic acid-containing material.
[0016]
Formaldehyde-containing compounds must be used with sulfonic acid group-containing compounds. When the formaldehyde-containing compound is used alone, the effect of removing impurities contained in the methacrylic acid-containing material is poor. The sulfonic acid group-containing compound means an inorganic or organic compound having a sulfonic acid group in the molecule. For example, sulfuric acid, benzenesulfonic acid, p-toluenesulfonic acid, methanesulfonic acid, a strong acid having a sulfonic acid group as an exchange group Ion exchange resin and the like. The sulfonic acid group-containing compound may be used by either a batch method or a continuous method. The amount used is preferably in the range of 0.1 to 50 parts by weight, particularly 1 to 30 parts by weight, based on 100 parts by weight of the methacrylic acid-containing material in batch mode. Further, when the strong acid ion exchange resin is used in a continuous manner, the flow rate of the methacrylic acid-containing material is 0.01 to 10 hr −1 , particularly 0.05 to 5 hr in space velocity with respect to the strong acid ion exchange resin. A range of -1 is preferred.
[0017]
In order to carry out the purification method of the present invention, a step of contacting a primary and / or secondary amino group-containing compound, a step of contacting a strongly acidic ion exchange resin, and a formaldehyde-containing substance and a sulfonic acid group-containing The steps of contacting the compounds may be performed in any order, but the present invention is characterized in that these three steps are essential.
[0018]
As the step of bringing the primary and / or secondary amino group-containing compound into contact, for example, the amino group-containing compound is added to the methacrylic acid-containing material and heated to a predetermined temperature, and then the mixture is preferably stirred. A method of holding for a certain time is used. The temperature at this time is preferably in the range of 50 to 150 ° C, particularly 80 to 130 ° C. The contact time is preferably in the range of 5 minutes to 5 hours, particularly 15 minutes to 3 hours.
[0019]
The step of bringing the strongly acidic ion exchange resin into contact can be carried out by either a batch method or a continuous method, but a method of making a flow contact on a fixed bed is preferable. The temperature at this time is preferably in the range of 20 to 150 ° C, particularly 40 to 130 ° C. In the case of a batch system, the contact time is preferably in the range of 5 minutes to 5 hours, particularly 15 minutes to 3 hours.
[0020]
The step of bringing the formaldehyde-containing material and the sulfonic acid group-containing compound into contact can be carried out by either a batch method or a continuous method. However, a fixed bed filled with a solid catalyst such as a strongly acidic ion exchange resin having a sulfonic acid group as an exchange group is used. A method of circulating a methacrylic acid-containing material added with a formaldehyde-containing material is preferable. The temperature at this time is preferably in the range of 20 to 150 ° C, particularly 40 to 130 ° C. In the case of a batch system, the contact time is preferably in the range of 5 minutes to 5 hours, particularly 15 minutes to 3 hours.
[0021]
The liquid after the step of bringing the primary and / or secondary amino group-containing compound into contact may be passed through the next treatment step as it is, but it is preferable to carry out the next step after distillation. . In addition, the liquid after the step of contacting the strongly acidic ion exchange resin or the step of contacting the formaldehyde-containing material and the sulfonic acid group-containing compound may be subjected to the next step as it is, or may be subjected to the next step after distillation. Good. The contacted solution is finally subjected to unreacted primary and / or secondary amino group-containing compound, strongly acidic ion exchange resin, formaldehyde-containing compound and sulfonic acid group-containing compound (hereinafter referred to as treating agent) by distillation or the like. And the reaction product of the treatment agent with the color-causing substance or the polymerization-inhibiting substance is separated from methacrylic acid. At this time, it is preferable to add a polymerization inhibitor such as phenothiazine or benzophenothiazine.
[0022]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.
The purity of methacrylic acid in Examples and Comparative Examples means weight percentage. The recovery rate of methacrylic acid is defined by the following equation.
Recovery rate (%) = B / A × 100
A and B in the formula are
A: Weight of methacrylic acid in methacrylic acid-containing material before purification B: Means weight of methacrylic acid in methacrylic acid-containing material after purification.
[0023]
[Example 1]
A mixed liquid of methacrylic acid and methyl methacrylate was obtained by liquid phase reaction from a methacrolein obtained by gas phase catalytic oxidation reaction of isobutylene using a catalyst in which methanol and 5 wt% palladium-3 wt% bismuth were supported on silica. It was. A methacrylic acid-containing product having a purity of 99.0% by weight was obtained from the resulting mixture by extraction and distillation. The color number of this product was APHA78.
[0024]
To 100 g of the resulting methacrylic acid-containing product, 0.05 g of phenothiazine as a polymerization inhibitor was added, and then 0.05 g of ethylenediamine was added and contacted at 100 ° C. for 2 hours. Next, 0.02 g of hydroquinone was added as a polymerization inhibitor to methacrylic acid obtained by simple distillation under a reduced pressure of 1.3 kPa, and a strongly acidic ion exchange resin “Amberlyst 15E” (trade name, manufactured by Rohm and Haas, The same applies hereinafter) 2.5 g was added and contacted at 100 ° C. for 1 hour. After removing the ion exchange resin from this liquid by decantation, an aqueous solution containing 35% by weight of formaldehyde was added so that the content ratio of formaldehyde with respect to the methacrylic acid-containing material was 100 ppm. 5 g of “Amberlyst 15E” was fixed to a glass U-shaped tube, and a methacrylic acid-containing material added with formaldehyde at a constant temperature of 80 ° C. was brought into flow contact at a space velocity of 0.2 hr −1 . Subsequently, simple distillation was performed under a reduced pressure of 1.3 kPa, and purified methacrylic acid was recovered at a recovery rate of 94%.
[0025]
The number of colors of the purified methacrylic acid thus obtained was improved to APHA3. Furthermore, the induction period which is a parameter | index of superposition | polymerization performance was measured with the following method about the obtained methacrylic acid. To a test tube, 100 ml of methacrylic acid, 5 mg of hydroquinone monomethyl ether and 0.1 g of benzoyl peroxide as a polymerization accelerator are added and dissolved. Add 10 ml of water, immerse it in a thermostatic bath at a temperature of 65 ° C., measure the temperature using a thermocouple, and determine the time when the liquid temperature rises from 65 ° C., that is, when the polymerization heat starts to be generated. Measure and use the time taken so far as the induction period (the same shall apply hereinafter). The induction period of purified methacrylic acid obtained by this example was 8.0 minutes.
[0026]
[Example 2]
Purification was carried out under the same conditions as in Example 1 except that 0.10 g of N, N′-diphenylethylenediamine was used instead of 0.05 g of ethylenediamine. The recovery rate of the obtained purified methacrylic acid was 93.1%, the color number was APHA4, and the induction period was 8.5 minutes.
[0027]
[Example 3]
Purification was carried out under the same conditions as in Example 1 except that 0.03 g of hydrazine and 0.05 g of N, N′-diphenylethylenediamine were used instead of 0.05 g of ethylenediamine. The recovery rate of the obtained purified methacrylic acid was 92.8%, the color number was APHA3, and the induction period was 8.0 minutes.
[0028]
[Example 4]
A mixed liquid of methacrylic acid and methyl methacrylate was obtained by a liquid phase reaction from a methacrolein obtained by gas phase catalytic oxidation of isobutylene using a catalyst in which methanol and 5 wt% palladium-3 wt% bismuth were supported on silica. . A methacrylic acid-containing product having a purity of 99.1% by weight was obtained from the resulting mixture by extraction and distillation. The color number of this product was APHA80.
[0029]
To 100 g of the resulting methacrylic acid-containing product, 0.02 g of hydroquinone was added as a polymerization inhibitor, 2.5 g of strongly acidic ion exchange resin “Amberlyst 15E” was added, and contacted at 100 ° C. for 1 hour. After removing the ion exchange resin by decantation, 0.05 g of ethylenediamine was added and contacted at 100 ° C. for 2 hours. Subsequently, simple distillation was performed under a reduced pressure of 1.3 kPa, and an aqueous solution containing 35% by weight of formaldehyde in the obtained methacrylic acid was added so that the content ratio of formaldehyde was 100 ppm with respect to the methacrylic acid-containing product. 5 g of “Amberlyst 15E” was fixed to a glass U-shaped tube, and a methacrylic acid-containing material added with formaldehyde at a constant temperature of 80 ° C. was brought into flow contact at a space velocity of 0.2 hr −1 . Subsequently, simple distillation was performed under reduced pressure of 1.3 kPa, and purified methacrylic acid was recovered at a recovery rate of 93.2%. The number of colors of the obtained purified methacrylic acid was APHA3, and the induction period was 8.5 minutes.
[0030]
[Example 5]
A mixed solution of methacrylic acid and methyl methacrylate was obtained from the methacrolein obtained by gas phase catalytic oxidation of isobutylene by a liquid phase reaction using a catalyst in which 5 wt% palladium-3 wt% bismuth was supported on silica. . A methacrylic acid-containing product having a purity of 99.0% was obtained from the obtained mixed solution by extraction and distillation. The color number of this product was APHA72.
[0031]
To 100 g of this methacrylic acid-containing product, 0.05 g of phenothiazine was added as a polymerization inhibitor, and then 0.05 g of ethylenediamine was added and contacted at 100 ° C. for 2 hours. Next, 0.02 g of hydroquinone was added as a polymerization inhibitor to the methacrylic acid-containing product obtained by simple distillation under a reduced pressure of 1.3 kPa, and an aqueous solution containing 35% by weight of formaldehyde was added to the methacrylic acid-containing product. It added so that a content ratio might be 100 ppm. 5 g of “Amberlyst 15E” was fixed to a glass U-shaped tube, and a methacrylic acid-containing material added with formaldehyde at a constant temperature of 80 ° C. was brought into flow contact at a space velocity of 0.2 hr −1 . To this solution, 2.5 g of strongly acidic ion exchange resin “Amberlyst 15E” was added and contacted at 100 ° C. for 1 hour. Subsequently, simple distillation was performed under a reduced pressure of 1.3 kPa, and purified methacrylic acid was recovered at a recovery rate of 94%. The number of colors of the purified methacrylic acid obtained was APHA2, and the induction period was 7.9 minutes.
[0032]
[Comparative Example 1]
Methacrylic acid was purified in the same manner as in Example 1 except that no formaldehyde was added. As a result, the recovery rate of purified methacrylic acid was 93.0%, the number of colors was APHA20, and the induction period was 10.0 minutes. In this example, the number of colors deteriorated compared to Example 1.
[0033]
[Comparative Example 2]
The methacrylic acid-containing material was purified in the same manner as in Example 1 except that 2.5 g of the strongly acidic ion exchange resin “Amberlyst 15E” was added and the treatment for contact at 100 ° C. for 1 hour was not performed. As a result, the recovery rate of purified methacrylic acid was 93.5%, the number of colors was APHA7, and the induction period was 18.0 minutes. In this example, both the number of colors and the induction period deteriorated as compared to Example 1.
[0034]
[Comparative Example 3]
The methacrylic acid-containing material was purified in the same manner as in Example 1 except that the treatment with contacting ethylenediamine was not performed. As a result, the recovery rate of purified methacrylic acid was 93.0%, the number of colors was APHA15, and the induction period was 12.0 minutes. In this example, both the number of colors and the induction period deteriorated as compared to Example 1.
[0035]
【The invention's effect】
According to the present invention, from a methacrylic acid-containing material containing a coloring factor substance and / or a polymerization inhibitory factor substance produced by liquid phase reaction from methacrolein and methanol using a palladium-containing compound, compared to a conventional method. High-quality methacrylic acid with little coloration and excellent polymerization performance can be easily obtained in high yield with a small amount of treatment agent.

Claims (1)

メタクロレインとメタノールからパラジウム含有化合物を用いて液相反応で製造されたメタクリル酸の精製法であって、当該メタクリル酸に第1級および/または第2級のアミノ基含有化合物を接触させる工程、当該メタクリル酸に強酸性イオン交換樹脂を接触させる工程、ならびに当該メタクリル酸にホルムアルデヒド含有物およびスルホン酸基含有化合物を接触させる工程、を含むメタクリル酸の精製法。A method for purifying methacrylic acid produced by liquid phase reaction from methacrolein and methanol using a palladium-containing compound , wherein the methacrylic acid is contacted with a primary and / or secondary amino group-containing compound , A method for purifying methacrylic acid, comprising a step of bringing a strongly acidic ion exchange resin into contact with the methacrylic acid , and a step of bringing the methacrylic acid into contact with a formaldehyde-containing substance and a sulfonic acid group-containing compound.
JP24794699A 1999-09-01 1999-09-01 Purification method of methacrylic acid Expired - Fee Related JP3792449B2 (en)

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