JP2004002346A

JP2004002346A - Phenol purification method

Info

Publication number: JP2004002346A
Application number: JP2003084813A
Authority: JP
Inventors: Masayuki Watanabe; 渡辺　昌幸; Yasunobu Teraoka; 寺岡　康信
Original assignee: Mitsubishi Chemical Corp
Current assignee: Mitsubishi Chemical Corp
Priority date: 2002-04-09
Filing date: 2003-03-26
Publication date: 2004-01-08

Abstract

【課題】高沸点成分を含む粗フェノールから、有機酸を早い段階で除去することができるフェノールの精製方法を提供する。
【解決手段】キュメンハイドロパーオキサイドの酸分解物から軽沸点成分を留去して得られた、主としてフェノールからなり、かつフェノールに対して２重量％以上の高沸点成分、更にα−メチルスチレン及び有機酸を含有する粗フェノールを、水が供給されているα−メチルスチレン除去塔に供給して蒸留することにより、塔頂からα−メチルスチレン及び水を主体とする成分を留出させ、塔の中間から有機酸、水及びフェノールを含有する側流液を抜き出し、塔底から高沸点成分を含むフェノールを取得することを特徴とするフェノールの精製方法。
【選択図】　なしAn object of the present invention is to provide a method for purifying a phenol capable of removing an organic acid at an early stage from a crude phenol containing a high boiling component.
SOLUTION: A light-boiling component obtained by distilling a light-boiling component from an acid hydrolyzate of cumene hydroperoxide is mainly composed of phenol, and a high-boiling component of 2% by weight or more with respect to phenol, and α-methylstyrene and The crude phenol containing an organic acid is supplied to an α-methylstyrene removal column to which water is supplied and distilled to distill a component mainly composed of α-methylstyrene and water from the top of the column. A method for purifying phenol, comprising extracting a side stream containing an organic acid, water and phenol from the middle of the above, and obtaining a phenol containing a high-boiling component from the bottom of the column.
[Selection diagram] None

Description

【０００１】
【発明の属する技術分野】
本発明は、キュメンハイドロパーオキサイドの酸分解物からフェノールを取得する方法に関するものである。詳しくは、フェノールと共存している有機酸を、早い段階で系外に除去する方法に関するものである。
【０００２】
【従来の技術】
フェノールは工業的に極めて重要な化学品であり、その大部分はキュメン法により製造されている。この方法ではキュメンを酸化してキュメンハイドロパーオキサイドとし、次いでこれを酸で分解してフェノール及びアセトンとする。酸分解反応生成液は中和及び洗浄により無機成分を除去した後、蒸留してフェノール及びアセトンを取得する。通常は、先ず酸分解反応生成液を粗アセトン塔で蒸留することにより、塔頂からアセトンを主体とする軽沸点の成分を留出させ、塔底からα−メチルスチレン及びこれよりも沸点の高い成分、すなわちα−メチルスチレン、主としてフェノールからなり、かつアセトフェノン、クミルフェノール及びα−メチルスチレンダイマーを主成分とする高沸点物を含む粗フェノールを取得する。この粗フェノール中には蟻酸や酢酸などの有機酸が含まれている。
【０００３】
これらの有機酸は通常の金属装置材料に対する腐食性が強いので、精製工程の早い段階で除去するのが好ましい。
粗フェノールの精製方法としては、粗フェノールから蒸留により高沸点成分を除去した後、このものを水と共に水抽出塔に供給して蒸留することにより、塔頂からα−メチルスチレン、メシチルオキシド及び２−メチルベンゾフラン等の有機不純物並びにフェノールを含む水を留出させ、塔の中間から有機酸を含む水及びフェノールを含有する側流液として抜き出し、塔底から精製フェノールを取得する方法が知られている。
【０００４】
また、特許文献１には、粗フェノールを水と共に蒸留塔に供給し、塔頂からα−メチルスチレン及び水を主体とする成分を留出させ、塔底から高沸点成分を抜き出し、塔の中間からフェノールを気相の側流として抜き出すフェノールの精製方法が記載されている。なお、この文献には有機酸の除去に関する記載はないが、この方法で有機酸を含む水及びフェノールからなる液相を側流として抜き出そうとすると、高段数の蒸留塔を必要とし、かつ２種類の側流を抜き出すので、安定した運転を行うのは困難である。
【０００５】
【特許文献１】
特開２０００−８６５５９号公報
【０００６】
【発明が解決しようとする課題】
本発明は、高沸点成分を含む粗フェノールから、有機酸を早い段階で除去することができるフェノールの精製方法を提供することを課題とする。
【０００７】
【課題を解決するための手段】
本発明によれば、キュメンハイドロパーオキサイドの酸分解物からアセトンを主体する軽沸点成分を留去して得られた、主としてフェノールからなり、かつフェノールに対して２重量％以上の高沸点成分、更にα−メチルスチレン及び有機酸を含有する粗フェノールを、水が供給されているα−メチルスチレン除去塔に供給して蒸留することにより、塔頂からα−メチルスチレン及び水を主体とする成分を留出させ、塔の中間から有機酸、水及びフェノールを含有する側流液を抜き出し、塔底から高沸点成分を含むフェノールを取得するフェノールの精製方法が提供される。この方法によれば、精製の早い段階で有機酸を効率よく粗フェノールから除去することができる。
【０００８】
【発明の実施の形態】
本発明で精製の対象とする粗フェノールは、キュメンハイドロパーオキサイドの酸分解物からアセトンを主体とした軽沸点成分を留去して得られたものであって、主としてフェノールからなり、かつフェノールに対して２重量％以上の高沸点成分を含有し、更にα−メチルスチレン及び有機酸その他の不純物を含有するものである。その代表的なものは、キュメンハイドロパーオキサイドの酸分解反応液を中和及び洗浄して無機成分を除去した後、粗アセトン塔で蒸留してアセトン及びα−メチルスチレンよりも軽沸点の成分を除去したものである。その代表的な組成を表１に示す。
【０００９】
【表１】

【００１０】
本発明の好ましい一態様では、フェノールの精製は、粗フェノールと水とをα−メチルスチレン除去塔に供給して蒸留し、塔頂からα−メチルスチレン及び水を主体とする成分を留出させ、塔の中間から有機酸、水及びフェノールを含有する側流液を抜き出し、塔底から高沸点成分を含むフェノールを取得するα−メチルスチレン除去工程；この工程で得られた高沸点成分を含むフェノールを高沸物除去塔に供給して蒸留し、塔頂からフェノールを留出させ、塔底から高沸点成分を抜き出す高沸点成分除去工程；及び高沸点成分除去工程で塔頂から留出したフェノールを水と共に水抽出塔に供給して蒸留し、塔頂から有機不純物、フェノール及び水を留出させ、塔底から精製フェノールを取得する第三蒸留工程の各蒸留工程を経由する。
【００１１】
粗フェノールを水が供給されているα−メチルスチレン除去塔に供給し、塔頂からα−メチルスチレン及び水を主体とする成分を留出させ、塔の中間から有機酸、水及びフェノールを含有する側流液を抜き出し、塔底からこれらの成分が除去されたフェノールを取得する。この蒸留は、理論段数３５〜５０段の蒸留塔を用い、常圧乃至若干加圧条件下で行えばよい。
【００１２】
水は、粗フェノールに対して通常は１．０〜１０重量％供給する。供給された水は、最終的には廃水処理設備で処理しなければならないので、必要最小限の量の水を供給するのが好ましい。したがって、１．０〜８重量％を供給するのが好ましい。粗フェノールの組成にもよるが、最も好ましい水の供給量は、粗フェノールに対して通常は１．０〜２．０重量％、特に１．５〜２．０重量％である。また、水は蒸留帯域の上部１０％以内の部分に供給し、粗フェノールは蒸留帯域の上から５０〜７５％の部分に供給するのが好ましい。なお、本明細書において蒸留帯域とは、蒸留塔のうち塔底部と塔頂部を除いた気液接触の行われる部分、具体的には最下段の段から最上段の段までの帯域を指す。
【００１３】
塔頂から留出したα−メチルスチレン及び水を主体とする留分は、凝縮器で凝縮させた後、油水分離槽で水相と油相とに分離する。油相中のα−メチルスチレンは、α−メチルスチレン精製工程で蒸留精製するか、又は水添してキュメンとして反応系に戻す。水相は、通常その大部分を塔に還流させ、残部は系外に排出する。なお、後続する水抽出塔でも水を必要とするので、廃水処理設備の負荷を軽減するため、この水相の一部を水抽出塔に供給するのが好ましい。
また、このα−メチルスチレン除去塔の塔頂凝縮熱は、他の反応器や蒸留塔等の加熱用熱源として利用することができる。
【００１４】
本発明者らの知見によれば、塔内の有機酸は、水濃度よりもフェノール濃度が高い液相組成の帯域に高濃度で存在している。したがって、側流液は、通常塔内の液相の水濃度が１〜４０重量％の帯域から抜き出す。水濃度が２〜３０重量％、特に５〜３０重量％の帯域から抜き出すのが好ましい。側流の抜き出し口は蒸留帯域の高さ方向に沿って複数設け、蒸留条件に応じて有機酸濃度の最も高いところから側流を抜き出せるようにしておくのが好ましい。
【００１５】
次いで、α−メチルスチレン除去塔の塔底から取得した高沸点成分を含むフェノールを、高沸物除去塔に供給して蒸留し、塔頂からフェノールを主体とする成分、すなわちフェノールに若干のメシチルオキシドや２−メチルベンゾフラン等を含む成分を留出させて取得する。このとき、塔底からアセトフェノン、クミルフェノール及びα−メチルスチレンダイマーを主体とする高沸点成分が除去される。
この蒸留は、理論段数２０〜３０段程度蒸留塔を用い、常圧乃至若干減圧で行えばよい。
【００１６】
更に、高沸物除去塔の塔頂から取得したフェノールを、水が供給されている水抽出塔に供給して蒸留し、塔頂から水と共にメシチルオキシドや２−メチルベンゾフラン等の有機不純物を留出させて除去し、塔底から精製フェノールを取得する。水はフェノールに対して１重量％以上、特に１．５重量％以上供給するのが好ましい。また、供給量の上限は通常１０重量％であり、好ましくは８重量％、特に５重量％である。なお、供給する水としては前述のα−メチルスチレン除去塔の塔頂留出液を油水分離して得られた水相を用いるのが好ましい。
【００１７】
また、この水抽出塔には、α−メチルスチレン除去塔で除去できなかった有機酸が蓄積するので、塔の中間部から有機酸を含む水とフェノールを含有する側流液を抜き出し、有機酸の蓄積を防止するのが好ましい。この側流液の抜き出しも塔内の液相の水濃度が１〜４０重量％の帯域から行えばよい。水濃度が、２〜３０重量％、特に５〜３０重量％の帯域から行うのが好ましい。
この蒸留は理論段数４５〜５５段程度の蒸留塔を用い、例えば塔頂圧力２２０ＫＰａ、塔底温度２１０〜２２０℃程度で行えばよい。なお、本明細書中の圧力は絶対圧を示す。
【００１８】
フェノールは蒸留帯域の上部、好ましくは蒸留帯域の上部１０〜２０％の帯域に供給し、水は蒸留帯域の上部、好ましくは蒸留帯域の上部１０％以内の帯域に供給する。水抽出塔の塔底から取得した精製フェノールは、通常は製品塔で更に蒸留して製品とする。
【００１９】
水抽出塔の好ましい一操作方法では、水抽出塔にフェノールを加えてキュメン及び／又はα−メチルスチレンを供給する。これにより塔頂からの有機不純物の留出を助長することができる。キュメン及び／又はα−メチルスチレンは、フェノールに対して合計で１〜７重量％、特に１〜３重量％となるように供給するのが好ましい。キュメン及び／又はα−メチルスチレンは、フェノールを主体とする成分に混合して供給してもよく、またフェノールとは別に供給してもよい。
【００２０】
また、水抽出塔に供給するフェノールを予め固体酸等の酸性触媒と接触させて、フェノール中の不純物の一部を重質化させておくのも好ましい。用いられる酸性触媒は固体酸が一般的であり酸性イオン交換樹脂やゼオライト、シリカアルミナなどを用いることができる。代表的な処理方法は、固体酸の充填床にフェノールを７０〜１５０℃、ＳＶ＝２〜１０ｈｒ^−１で通過させればよい。
【００２１】
本発明は、α−メチルスチレン除去工程と高沸点成分除去工程の順序を入れ替えた態様で行うこともできる。すなわち、この態様では粗フェノールを高沸物除去塔に供給して蒸留し、塔頂からα−メチルスチレンを含むフェノールを留出させ、塔底から高沸点成分を抜き出す高沸点除去工程；高沸点除去工程で得られたα−メチルスチレンを含むフェノール及び水をα−メチルスチレン除去塔に供給して蒸留し、塔頂からα−メチルスチレン及び水を主体とする成分を留出させ、塔の中間から有機酸、水及びフェノールを含有する側流液を抜き出し、塔底からフェノールを取得するα−メチルスチレン除去工程；及びα−メチルスチレン除去工程で得られたフェノールを水と共に水抽出塔に供給して蒸留し、塔頂から有機不純物、フェノール及び水を留出させ、塔底から精製フェノールを取得する第三蒸留工程の各蒸留工程を経由する。
【００２２】
この態様における各蒸留工程は、前述した態様における対応する蒸留工程に準じて行えばよい。
【００２３】
【実施例】
本発明を実施例により更に詳細に説明するが、本発明は、その要旨を超えない限り、以下の実施例に限定されるものでない。
（実施例１）
理論段数４２段の蒸留塔に、表２に示す組成の粗フェノールを３０段目に、水を２段目に供給し、３０段目から側流液を抜き出した。蒸留塔への供給量及び蒸留塔からの抜き出し量は表３のとおりとした。
【００２４】
【表２】

【００２５】
【表３】

【００２６】
蒸留は次の条件で行った。
塔頂：圧力；１４０ＫＰａ、温度；１０５℃
塔底：圧力；１８４ＫＰａ、温度；２０６℃
水の還流比：２３
塔頂から抜き出した油相及び塔底から抜き出したフェノールの組成、並びにメシチルオキシド及び２−メチルベンゾフランのそれぞれへの分配率は表４，表５のとおりであった。また有機酸の側流液への分配率は８２％であった。
【００２７】
【表４】

【００２８】
【表５】

【００２９】
この塔底から抜き出したフェノールを理論段数２４段の蒸留塔の１９段目に供給し、塔頂温度１５５℃、塔底温度２０１℃、塔頂圧力４５ＫＰａ、還流比０．４で蒸留すると、塔頂から純度９９．７重量％程度のフェノールが約９２％の収率で取得できる。
次いで、この塔頂から取得したフェノール及びこれに対して２重量％のキュメンを混合したものを、理論段数４８段の蒸留塔の６段目に供給し、２段目にフェノールに対して１．５重量％の水を供給して、塔頂温度１２３℃、塔底温度２１８℃、塔頂圧力２２０ＫＰａで蒸留し、かつ３９段目からフェノール供給量に対して１．５重量％の側流液を抜き出すことにより、塔底から純度９９．９８重量％程度のフェノールを取得することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for obtaining phenol from an acid hydrolyzate of cumene hydroperoxide. More specifically, the present invention relates to a method for removing an organic acid coexisting with phenol out of the system at an early stage.
[0002]
[Prior art]
Phenol is an industrially important chemical, most of which is produced by the cumen method. In this method, cumene is oxidized to cumene hydroperoxide, which is then decomposed with acid to phenol and acetone. The acid decomposition reaction product liquid is neutralized and washed to remove inorganic components, and then distilled to obtain phenol and acetone. Usually, the acid decomposition reaction product is first distilled in a crude acetone column to distill a low-boiling component mainly composed of acetone from the top of the column, and α-methylstyrene and a boiling point higher than α-methylstyrene from the bottom of the column. A crude phenol is obtained which is composed of components, that is, α-methylstyrene, mainly phenol, and contains a high-boiling substance mainly composed of acetophenone, cumylphenol and α-methylstyrene dimer. This crude phenol contains organic acids such as formic acid and acetic acid.
[0003]
Since these organic acids are highly corrosive to ordinary metal equipment materials, they are preferably removed early in the purification process.
As a method for purifying crude phenol, after removing high boiling components from crude phenol by distillation, this is supplied to a water extraction column together with water and distilled, whereby α-methylstyrene, mesityl oxide and A method is known in which water containing organic impurities such as 2-methylbenzofuran and phenol is distilled off, and water is removed from the middle of the column as a side stream containing water and phenol containing organic acids to obtain purified phenol from the bottom of the column. ing.
[0004]
Patent Document 1 discloses that a crude phenol is supplied to a distillation column together with water, a component mainly composed of α-methylstyrene and water is distilled from the top of the column, and a high-boiling component is extracted from the bottom of the column. Discloses a method for purifying phenol from which phenol is extracted as a gaseous side stream. Although there is no description in this document regarding the removal of organic acids, if a liquid phase consisting of water and phenol containing organic acids is to be extracted as a side stream by this method, a high number of distillation columns is required, and Since two types of sidestreams are extracted, it is difficult to perform stable operation.
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-86559
[Problems to be solved by the invention]
An object of the present invention is to provide a method for purifying phenol that can remove an organic acid at an early stage from crude phenol containing a high-boiling component.
[0007]
[Means for Solving the Problems]
According to the present invention, a high-boiling component consisting mainly of phenol, obtained by distilling a light-boiling component mainly composed of acetone from an acid hydrolyzate of cumene hydroperoxide, and having a boiling point of 2% by weight or more based on phenol, Further, a crude phenol containing α-methylstyrene and an organic acid is supplied to an α-methylstyrene removal tower to which water is supplied and distilled, whereby a component mainly composed of α-methylstyrene and water is supplied from the top of the tower. , A sidestream liquid containing an organic acid, water and phenol is withdrawn from the middle of the column to obtain a phenol containing a high-boiling component from the bottom of the column. According to this method, the organic acid can be efficiently removed from the crude phenol at an early stage of the purification.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The crude phenol to be purified in the present invention is obtained by distilling a light-boiling component mainly composed of acetone from an acid hydrolyzate of cumene hydroperoxide, and is mainly composed of phenol and converted into phenol. On the other hand, it contains 2% by weight or more of high boiling components and further contains α-methylstyrene, organic acids and other impurities. The typical one is to neutralize and wash the acid decomposition reaction solution of cumene hydroperoxide to remove inorganic components, and then distill in a crude acetone column to remove components having a boiling point lower than acetone and α-methylstyrene. It has been removed. Table 1 shows the typical composition.
[0009]
[Table 1]

[0010]
In a preferred embodiment of the present invention, in the purification of phenol, crude phenol and water are fed to an α-methylstyrene removal column and distilled, and a component mainly composed of α-methylstyrene and water is distilled from the column top. Extracting a side stream containing an organic acid, water and phenol from the middle of the column, and removing α-methylstyrene from the bottom of the column to obtain phenol containing a high-boiling component; including the high-boiling component obtained in this process Phenol is supplied to a high-boiling substance removal column and distilled, and phenol is distilled from the top and a high-boiling component removing step of extracting a high-boiling component from the bottom; Phenol is supplied to a water extraction column together with water to be distilled, and organic impurities, phenol and water are distilled off from the top of the column, and the purified phenol is obtained from the bottom of the column.
[0011]
The crude phenol is supplied to an α-methylstyrene removal tower to which water is supplied, and a component mainly composed of α-methylstyrene and water is distilled from the top of the tower, and contains an organic acid, water and phenol from the middle of the tower. The effluent from which the components are removed is obtained from the bottom of the column. This distillation may be performed using a distillation column having 35 to 50 theoretical plates under normal pressure or slightly pressurized conditions.
[0012]
Water is usually supplied at 1.0 to 10% by weight relative to the crude phenol. Since the supplied water must be finally treated in a wastewater treatment facility, it is preferable to supply a minimum necessary amount of water. Therefore, it is preferable to supply 1.0 to 8% by weight. Although it depends on the composition of the crude phenol, the most preferable water supply is usually 1.0 to 2.0% by weight, especially 1.5 to 2.0% by weight based on the crude phenol. Further, it is preferable that water is supplied to a portion within the upper 10% of the distillation zone, and that the crude phenol is supplied to a portion of the distillation zone from the uppermost portion to 50 to 75%. In this specification, the distillation zone refers to a portion of the distillation column where gas-liquid contact is performed except for the bottom and the top, specifically, a zone from the lowest stage to the highest stage.
[0013]
The fraction mainly composed of α-methylstyrene and water distilled off from the tower top is condensed by a condenser, and then separated into a water phase and an oil phase in an oil / water separation tank. The α-methylstyrene in the oil phase is purified by distillation in the α-methylstyrene purification step, or is hydrogenated and returned to the reaction system as cumene. Most of the aqueous phase is usually refluxed to the column, and the remainder is discharged outside the system. Since the subsequent water extraction tower also requires water, it is preferable to supply a part of this aqueous phase to the water extraction tower in order to reduce the load on the wastewater treatment equipment.
Further, the heat of condensation at the top of the α-methylstyrene removal tower can be used as a heat source for heating other reactors, distillation towers and the like.
[0014]
According to the findings of the present inventors, the organic acid in the column is present at a high concentration in a zone having a liquid phase composition in which the phenol concentration is higher than the water concentration. Therefore, the sidestream liquid is usually withdrawn from the zone where the water concentration of the liquid phase in the column is 1 to 40% by weight. It is preferred to withdraw from the zone where the water concentration is 2 to 30% by weight, especially 5 to 30% by weight. It is preferable that a plurality of outlets for the side stream are provided along the height direction of the distillation zone so that the side stream can be extracted from a place where the concentration of the organic acid is highest according to the distillation conditions.
[0015]
Next, the phenol containing the high-boiling component obtained from the bottom of the α-methylstyrene removal tower is supplied to the high-boiling substance removal tower and distilled, and the phenol-based component, that is, a small amount of phenol is removed from the top of the tower. It is obtained by distilling out components including tyl oxide and 2-methylbenzofuran. At this time, high boiling components mainly composed of acetophenone, cumylphenol and α-methylstyrene dimer are removed from the bottom of the column.
This distillation may be carried out under normal pressure or slightly reduced pressure using a distillation column having about 20 to 30 theoretical plates.
[0016]
Further, phenol obtained from the top of the high-boiling substance removal tower is supplied to a water extraction tower to which water is supplied and distilled, and organic impurities such as mesityl oxide and 2-methylbenzofuran are removed together with water from the tower top. It is distilled off and the purified phenol is obtained from the bottom of the column. Water is preferably supplied in an amount of 1% by weight or more, particularly 1.5% by weight or more based on phenol. The upper limit of the supply amount is usually 10% by weight, preferably 8% by weight, particularly 5% by weight. In addition, as the water to be supplied, it is preferable to use an aqueous phase obtained by subjecting the overhead distillate of the α-methylstyrene removal tower to oil-water separation.
[0017]
Further, organic acids that could not be removed by the α-methylstyrene removal tower accumulate in the water extraction tower, so that a sidestream liquid containing water and phenol containing organic acids was extracted from the middle part of the tower, and the organic acid was removed. Is preferably prevented. The withdrawal of the side stream may be performed from the zone where the water concentration of the liquid phase in the column is 1 to 40% by weight. It is preferable to carry out from the zone where the water concentration is 2 to 30% by weight, particularly 5 to 30% by weight.
This distillation may be performed using a distillation column having about 45 to 55 theoretical plates, for example, at a top pressure of 220 KPa and a bottom temperature of about 210 to 220 ° C. In addition, the pressure in this specification shows an absolute pressure.
[0018]
Phenol is fed to the upper part of the distillation zone, preferably to the upper 10-20% of the distillation zone, and water is fed to the upper part of the distillation zone, preferably to the zone within the upper 10% of the distillation zone. Purified phenol obtained from the bottom of the water extraction column is usually further distilled in a product column to produce a product.
[0019]
In one preferred method of operating the water extraction tower, phenol is added to the water extraction tower to supply cumene and / or α-methylstyrene. Thereby, the distillation of the organic impurities from the top of the column can be promoted. The cumene and / or α-methylstyrene are preferably supplied in a total amount of 1 to 7% by weight, particularly 1 to 3% by weight, based on phenol. The cumene and / or α-methylstyrene may be supplied as a mixture with a component mainly composed of phenol, or may be supplied separately from phenol.
[0020]
It is also preferable that the phenol supplied to the water extraction column is brought into contact with an acidic catalyst such as a solid acid in advance to make some of the impurities in the phenol heavier. The acidic catalyst used is generally a solid acid, and an acidic ion exchange resin, zeolite, silica alumina or the like can be used. As a typical treatment method, phenol may be passed through a packed bed of solid acid at 70 to 150 ° C. and SV = 2 to 10 hr ⁻¹ .
[0021]
The present invention can also be carried out in a mode in which the order of the α-methylstyrene removing step and the high boiling point component removing step is reversed. That is, in this embodiment, a high-boiling point removing step in which crude phenol is supplied to a high-boiling substance removal column and distilled to distill phenol containing α-methylstyrene from the top of the column and extract high-boiling components from the bottom of the column; The phenol and water containing α-methylstyrene obtained in the removal step are supplied to the α-methylstyrene removal tower and distilled, and a component mainly composed of α-methylstyrene and water is distilled from the top of the tower, and A side stream containing organic acid, water and phenol is withdrawn from the middle, and phenol obtained in the α-methylstyrene removal step is obtained in the water extraction column together with water. It feeds and distills, and the organic impurities, phenol, and water are distilled off from the top of the column, and the purified phenol is obtained from the bottom of the column.
[0022]
Each distillation step in this embodiment may be performed according to the corresponding distillation step in the above-described embodiment.
[0023]
【Example】
The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.
(Example 1)
Crude phenol having the composition shown in Table 2 was supplied to the distillation column having 42 theoretical plates at the 30th plate, water was supplied to the 2nd plate, and the sidestream liquid was extracted from the 30th plate. Table 3 shows the supply amount to the distillation column and the extraction amount from the distillation column.
[0024]
[Table 2]

[0025]
[Table 3]

[0026]
Distillation was performed under the following conditions.
Top: pressure: 140 KPa, temperature: 105 ° C
Column bottom: pressure: 184 KPa, temperature: 206 ° C
Water reflux ratio: 23
Tables 4 and 5 show the compositions of the oil phase extracted from the top and the phenol extracted from the bottom, and the distribution ratios of mesityl oxide and 2-methylbenzofuran, respectively. The distribution ratio of the organic acid to the sidestream liquid was 82%.
[0027]
[Table 4]

[0028]
[Table 5]

[0029]
The phenol extracted from the bottom of the column is supplied to the 19th stage of a distillation column having 24 theoretical plates, and distilled at a top temperature of 155 ° C., a bottom temperature of 201 ° C., a top pressure of 45 KPa, and a reflux ratio of 0.4. Phenol having a purity of about 99.7% by weight can be obtained from the top with a yield of about 92%.
Next, a mixture of phenol obtained from the top of the column and 2% by weight of cumene based on the phenol was supplied to the sixth stage of a distillation column having 48 theoretical plates. 5% by weight of water was supplied, distillation was carried out at a top temperature of 123 ° C., a bottom temperature of 218 ° C., and a top pressure of 220 KPa. Phenol having a purity of about 99.98% by weight can be obtained from the bottom of the column.

Claims

The light-boiling component is distilled off from the acid hydrolyzate of cumene hydroperoxide, which is mainly composed of phenol and contains a high-boiling component of 2% by weight or more based on phenol, and further contains α-methylstyrene and an organic acid. The crude phenol is supplied to an α-methylstyrene removal tower to which water is supplied, and is distilled to distill a component mainly composed of α-methylstyrene and water from the top of the tower. A method for purifying phenol, comprising extracting a side stream containing acid, water and phenol, and obtaining phenol containing a high-boiling component from the bottom of the column.

The light-boiling component is distilled off from the acid hydrolyzate of cumene hydroperoxide, which is mainly composed of phenol and contains a high-boiling component of 2% by weight or more based on phenol, and further contains α-methylstyrene and an organic acid. The crude phenol is supplied to an α-methylstyrene removal column to which water is supplied and distilled, and a component mainly composed of α-methylstyrene and water is distilled from the top of the column, and an organic acid, Withdrawing a side stream containing water and phenol and obtaining a phenol containing a high boiling component from the bottom of the column; removing the phenol containing a high boiling component obtained in the α-methyl styrene removing step; A high-boiling component removing step in which the high-boiling component is removed by feeding to a high-boiling substance removing column and distilling phenol from the top and extracting a high-boiling component from the bottom; A third distillation step in which phenol distilled from the top is supplied to a water extraction column to which water is supplied and distilled, and organic impurities, phenol and water are distilled from the top of the column to obtain purified phenol from the bottom of the column. A method for purifying phenol, wherein the method comprises the steps of:

The light-boiling component is distilled off from the acid hydrolyzate of cumene hydroperoxide, which is mainly composed of phenol and contains a high-boiling component of 2% by weight or more based on phenol. A crude phenol containing an acid is fed to a high-boiling substance removal column and distilled, and a component mainly composed of phenol containing α-methylstyrene is distilled from the top of the column, and a high-boiling point is obtained by extracting a high-boiling component from the bottom of the column. Component removal step: The phenol containing α-methylstyrene obtained in the high-boiling-point component removal step is supplied to an α-methylstyrene removal tower to which water is supplied and distilled, and α-methylstyrene and water are supplied from the top of the tower. An α-methylstyrene removing step of distilling a component mainly comprising, extracting a sidestream liquid containing an organic acid, water and phenol from the middle of the column and obtaining phenol from the bottom of the column; And the phenol obtained in the α-methylstyrene removal step is supplied to a water extraction column to which water is supplied and distilled, and organic impurities, phenol and water are distilled from the top of the column, and purified phenol is purified from the bottom of the column. A method for purifying phenol, which goes through each distillation step of the third distillation step to be obtained.

The method for purifying phenol according to claim 2 or 3, wherein a sidestream liquid comprising water containing an organic acid and phenol is withdrawn from the middle of the water extraction column.

The water supplied to the water extraction tower is characterized by containing water obtained by oil-water separation of α-methylstyrene and water-based components distilled from the top of the α-methylstyrene removal tower. The method for purifying phenol according to any one of claims 2 to 4.

The method according to any one of claims 1 to 5, wherein the sidestream liquid is withdrawn from the α-methylstyrene removal tower from a zone where the water concentration of the liquid phase in the tower is 1 to 40% by weight. A method for purifying phenol.

An oil-water separation of a fraction mainly composed of α-methylstyrene and water distilled off from the top of the α-methylstyrene removal tower, and refluxing the aqueous phase to the α-methylstyrene removal tower. 7. The method for purifying phenol according to any one of 1 to 6.