JPS6310691B2 - - Google Patents
Info
- Publication number
- JPS6310691B2 JPS6310691B2 JP54167598A JP16759879A JPS6310691B2 JP S6310691 B2 JPS6310691 B2 JP S6310691B2 JP 54167598 A JP54167598 A JP 54167598A JP 16759879 A JP16759879 A JP 16759879A JP S6310691 B2 JPS6310691 B2 JP S6310691B2
- Authority
- JP
- Japan
- Prior art keywords
- acetic acid
- acrylic acid
- column
- water
- acid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 290
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 88
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 86
- 238000000926 separation method Methods 0.000 claims description 46
- 230000018044 dehydration Effects 0.000 claims description 34
- 238000006297 dehydration reaction Methods 0.000 claims description 34
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 33
- 238000004821 distillation Methods 0.000 claims description 27
- 239000003795 chemical substances by application Substances 0.000 claims description 26
- 239000007788 liquid Substances 0.000 claims description 26
- 238000000034 method Methods 0.000 claims description 19
- 239000007864 aqueous solution Substances 0.000 claims description 18
- HGINCPLSRVDWNT-UHFFFAOYSA-N Acrolein Chemical compound C=CC=O HGINCPLSRVDWNT-UHFFFAOYSA-N 0.000 claims description 14
- 239000007789 gas Substances 0.000 claims description 13
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 12
- 239000000243 solution Substances 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 11
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 claims description 8
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 claims description 8
- 238000000746 purification Methods 0.000 claims description 7
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 6
- 150000001299 aldehydes Chemical class 0.000 claims description 6
- 235000019253 formic acid Nutrition 0.000 claims description 6
- 238000007254 oxidation reaction Methods 0.000 claims description 6
- 238000009835 boiling Methods 0.000 claims description 5
- 230000003197 catalytic effect Effects 0.000 claims description 5
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 4
- 229910001882 dioxygen Inorganic materials 0.000 claims description 4
- 230000003647 oxidation Effects 0.000 claims description 4
- 238000010521 absorption reaction Methods 0.000 claims description 2
- 238000001816 cooling Methods 0.000 claims 1
- 239000011259 mixed solution Substances 0.000 claims 1
- 238000004064 recycling Methods 0.000 claims 1
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 27
- 238000010992 reflux Methods 0.000 description 12
- 238000000605 extraction Methods 0.000 description 11
- 239000012071 phase Substances 0.000 description 9
- 238000006116 polymerization reaction Methods 0.000 description 9
- 238000011084 recovery Methods 0.000 description 7
- QIGBRXMKCJKVMJ-UHFFFAOYSA-N Hydroquinone Chemical compound OC1=CC=C(O)C=C1 QIGBRXMKCJKVMJ-UHFFFAOYSA-N 0.000 description 6
- 239000008346 aqueous phase Substances 0.000 description 4
- 238000010533 azeotropic distillation Methods 0.000 description 4
- 239000003112 inhibitor Substances 0.000 description 4
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 3
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 3
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- SZNYYWIUQFZLLT-UHFFFAOYSA-N 2-methyl-1-(2-methylpropoxy)propane Chemical compound CC(C)COCC(C)C SZNYYWIUQFZLLT-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 description 2
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- IKHGUXGNUITLKF-XPULMUKRSA-N acetaldehyde Chemical compound [14CH]([14CH3])=O IKHGUXGNUITLKF-XPULMUKRSA-N 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- MGNZXYYWBUKAII-UHFFFAOYSA-N cyclohexa-1,3-diene Chemical compound C1CC=CC=C1 MGNZXYYWBUKAII-UHFFFAOYSA-N 0.000 description 2
- HGCIXCUEYOPUTN-UHFFFAOYSA-N cyclohexene Chemical compound C1CCC=CC1 HGCIXCUEYOPUTN-UHFFFAOYSA-N 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- UAEPNZWRGJTJPN-UHFFFAOYSA-N methylcyclohexane Chemical compound CC1CCCCC1 UAEPNZWRGJTJPN-UHFFFAOYSA-N 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229920002125 Sokalan® Polymers 0.000 description 1
- 125000000218 acetic acid group Chemical group C(C)(=O)* 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- -1 aliphatic alcohols Chemical class 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 238000010420 art technique Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000000110 cooling liquid Substances 0.000 description 1
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 1
- GYNNXHKOJHMOHS-UHFFFAOYSA-N methyl-cycloheptane Natural products CC1CCCCCC1 GYNNXHKOJHMOHS-UHFFFAOYSA-N 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Description
本発明はアクリル酸の重合を防止しつつアクリ
ル酸を精製する方法に関するものである。さらに
詳しくは、プロピレンおよび（または）アクロレ
インを分子状酸素で接触気相酸化して得られる粗
アクリル酸水溶液から不純物の酢酸などを分離精
製するに際し、精製装置内でのアクリル酸の重合
を防止しつつ、簡略化された装置によつて、アク
リル酸を高回収率で精製する方法に関する。
プロピレンおよび（または）アクロレインを酸
化触媒を用いて、水蒸気の存在下分子状酸素によ
つて酸化すると、目的物であるアクリル酸のほ
か、酢酸、ギ酸、アセトアルデヒド、ホルムアル
デヒド、炭酸ガス、一酸化炭素等の副反応生成物
と未反応プロピレンおよびアクロレインを含む混
合ガスが得られる。この反応生成ガスを冷却およ
び（または）水で吸収するとアクリル酸と酢酸、
ギ酸とアルデヒド類を含む水溶液が得られる。酢
酸は副生成物のなかで最も多量に生成し、アクリ
ル酸の精製工程でその分離は特に重要な操作であ
る。
本発明の目的は、この様な粗アクリル酸水溶液
より、重合を防止しつつ工業的に有利に、実質的
に水および酢酸、アルデヒド類の副反応物を含ま
ないアクリル酸を分離回収するにある。
従来、工業的に実施されている粗アクリル酸水
溶液よりアクリル酸を精製するプロセスには、第
１図に示す様な方法がある（Chem.Eng.78頁、
July 14，1969）。以下この方法について説明す
る。プロピレンおよび（または）アクロレインの
接触気相酸化反応により生成した、アクリル酸を
含む酸化生成ガスを凝縮した粗アクリル酸水溶液
を導管１より抽出塔Ａに供給する、さらに導管８
より抽剤を供給し、アクリル酸などを抽出した抽
出液は導管２より得られ、抽出分離塔Ｂに供給さ
れる。抽出液中の水および抽剤は抽剤分離塔Ｂで
除かれ、水は導管５で抽剤回収塔Ｄへ供給され、
抽剤は導管４で抽出塔Ａへ戻される。抽剤分離塔
Ｂの塔底液はアクリル酸と酢酸の混合液であり、
導管３で酢酸分離塔（酢酸分離蒸留塔を意味する
以下同様）Ｃへ供給され、導管７より酢酸は廃棄
され、導管６より酢酸を含まないアクリル酸が得
られる。抽出塔Ａよりの抽残液は導管９より、抽
剤回収塔Ｄで抽剤を回収し、導管１１より抽出塔
に再循環される。抽剤を回収された水は導管１０
を通じて廃棄される。
この従来法には、次の様な欠点がある。すなわ
ち、この精製装置は抽出塔と三本の蒸留塔を有す
る複雑な装置であり、建設費がかさむうえにアク
リル酸の回収率が低い。即ち、粗アクリル酸水溶
液からアクリル酸を抽出塔で全量回収することは
困難であり、抽残液中のアクリル酸は全量損失と
なる。
また酢酸分離塔においては、アクリル酸と酢酸
の化学的類似性のため、その比揮発度は大きくな
いので多くの段数と高い還流比が必要である。そ
の様な条件を与えてもなお酢酸分離塔の塔頂から
のアクリル酸の留出は少なくない。更に重要なこ
とは、醋酸分離塔でアクリル酸の重合が生じ、塔
内にアクリル酸の重合物が堆積し、蒸留塔の塔底
圧力が上昇し、運転が不可能となるトラブルが発
生しやすいことで、この事は当業者が良く知つて
いることである（特公昭49−24898）。
一方、アクリル酸と酢酸を分離する際に、蒸留
塔に共沸剤としてトルエンを添加し、酢酸との分
離を容易にする方法が提案されているが（特公昭
41−11247）、この方法では酢酸分離塔の塔頂から
のアクリル酸は結局溶剤回収塔の塔底から排出さ
れて損失となる。この方法ではその損失を防止す
る為酢酸分離塔の段数及び還流比を大きくしなけ
ればならない欠点を有している。更に、この方法
では酢酸分離塔の塔頂液から共沸剤のトルエンを
回収するために、水を加えて共沸によりこれを回
収する必要がある。そのために蒸留塔が必要であ
り、しかも前述の通り、この蒸留塔ではアクリル
酸は回収できない。
又、上記共沸蒸留法の改良案が多数発表されて
いる。たとえば特公昭46−20372には共沸剤とし
てトルエンとアルコール類の混合物を用い、アク
リル酸水溶液から水と酢酸を同時に蒸留分離する
方法が提案されている。
しかし本発明者らの研究の結果では、この方法
は多くの欠点を有し、工業的に採用するには未解
決の問題点を含んでいることが明白となつた。即
ち、共沸剤として実質的に水には不溶であること
が有利な条件となるが、炭素数が４程度の脂肪族
アルコールは水への溶解度がかなり高く、廃水中
からのアルコールの回収が必要となる。又共沸蒸
留塔の塔底液を製品とする場合には、塔底液中に
共沸剤が含まれてはいけない。ところが蒸留塔の
塔底部に共沸剤を存在させない操作では酢酸が有
効に除去できない矛盾があり、塔底液に共沸剤が
存在しない条件下で酢酸を除去しようとすれば、
塔頂の廃水中にアクリル酸が混入してアクリル酸
の損失が増大する。さらに重要なことは、蒸留塔
の中段から塔頂付近でアクリル酸が重合し、塔の
圧損失が上昇する致命的な欠点を有することであ
る。この現象は上記従来法の酢酸分離塔と同様な
現象と推察される。
本発明者らはこれら先行技術の諸欠点をなくす
ため、種々研究を行つた結果、次に記載される新
しい方法を見出した。
(1) 塔式蒸留塔として脱水塔（脱水蒸留塔を意味
する以下同様）及び酢酸分離塔（酢酸分離蒸留
塔を意味する。以下同様）を用意する。
(2) 脱水塔において粗アクリル酸水溶液又酢酸分
離塔において醋酸を含むアクリル酸の蒸留に次
の条件を満足する共沸剤または該共沸剤の混合
物を使用する。
(a) 水と酢酸のそれぞれと共沸する。
(b) 水に難溶である。
(c) アクリル酸とは共沸しない。
(3) 脱水塔において粗アクリル酸水溶液の水の全
部及び醋酸の一部を前記共沸剤と共に塔頂より
留去する。
(4) 酢酸分離塔において脱水塔の塔底より抜き出
される醋酸とアクリル酸を前記共沸剤と蒸留
し、該醋酸の全部と少量のアクリル酸を前記共
沸剤と共に塔頂より抜き（一部は自塔に還流す
る）脱水塔にリサイクルする。
なお、本願明細書に記載の難溶とは、20℃にお
いて水に５重量％以下の溶解度であることを意味
するものとする。
この新しい方法により従来法に比し酢酸分離塔
の段数を減少し、且その還流比を小さくすること
が可能となつた。又この方法ではアクリル酸の損
失が殆んどなく、且長期間連続運転が可能である
ことが確かめられ、本発明を完成した。
アクリル酸の精製工程で酢酸の分離が特に重要
な操作であることは既に述べた。又この分離が最
も困難な工程であることは当業者が良く知つてい
る。本発明はこの課題を解決した画期的な方法で
あるということが出来る。
本発明の要旨は、
「プロピレンおよび（または）アクロレインを
分子状酸素で接触気相酸化した生成ガスを冷却、
または（および）水に吸収して得られる粗アクリ
ル酸水溶液又は該液のアルデヒド類を予めストリ
ツピングにより除去した液と次の(a)，(b)及び(c)の
条件を満足する共沸剤
(a) 水と酢酸のそれぞれと共沸する。
(b) 水に難溶である。
(c) アクリル酸とは共沸しない。
または該共沸剤の混合物とを脱水蒸留塔に供給
して蒸留し、実質的に上記粗アクリル酸水溶液中
の全ての水及びギ酸並びに酢酸の一部をつ留去
し、酢酸の残存するアクリル酸を塔底液として抜
き出して酢酸分離蒸留塔に導き、該塔において、
残りの酢酸を前記共沸剤とともに塔頂より留去
し、塔底より精製アクリル酸を回収し、塔頂から
得られる酢酸、アクリル酸および共沸剤の混合液
を前記の脱水蒸留塔にリサイクルすることを特徴
とするアクリル酸の精製法。」である。
本発明の特徴は、要約すれば醋酸を脱水塔で一
部分離し、又醋酸分離塔の塔頂液は自塔に還流す
るほか脱水塔にリサイクルすることにより、系外
へのアクリル酸の損失を無くし醋酸分離塔の負担
を著しく軽減し（該蒸留塔の段数と還流比を減少
することを可能とする）、蒸留中のアクリル酸の
重合を防止することに成功した点にある。なお脱
水塔の塔頂から留去する酢酸の量は粗アクリル酸
水溶液中に含まれる酢酸の50重量％以上が好まし
く、更に好ましくは75重量％以上である。
又脱水塔の塔底からアクリル酸と残りの酢酸と
該酢酸を共沸蒸留に必要な量以上の共沸剤とを抜
き、この液を次の酢酸分離塔に供給するのが好ま
しい。然し若し脱水塔の塔底液中に共沸剤が全く
ないか、又は酢酸を共沸蒸留するに不足する場合
は、酢酸分離塔に別途前記の共沸剤を補給して、
酢酸分離塔に供給される酢酸を共沸蒸留出来る様
にすればよい。即ち、酢酸分離塔にはこの塔に供
給される酢酸を共沸蒸留させるに足る量以上の共
沸剤が供給されゝば良い。
本発明の実施態様を第２図によつて具体的に例
示する。まず、プロピレン、空気、水蒸気からな
る原料ガスを接触酸化して得られたガスを冷却お
よび（または）水で吸収して得られた粗アクリル
酸水溶液を導管１２より脱水塔Ｅへ供給する。こ
の粗アクリル酸水溶液は不純物として含むアルデ
ヒド類を予めストリツピングにより除去したもの
でも良く、除去しない液でも用いることができ
る。脱水塔Ｅには前記の共沸剤を導管１６より供
給し、塔頂より好ましくは重合防止剤を添加しな
がら、好ましくは減圧下で蒸留を行う。塔頂から
の蒸気は凝縮させると、水相と共沸剤相を形成す
るが、水相は実質的に前記粗アクリル酸水溶液の
全ての水、ギ酸及びアルデヒド類並びに酢酸の一
部より成り、導管１３より廃棄される。一方共沸
剤相は導管１５より脱水塔Ｅに全量還流される。
この共沸剤の還流量は、導管１６より供給される
共沸剤を加えて脱水塔において水の全部と酢酸の
一部とを共沸除去するに必要な量以上とする。ア
クリル酸、残りの酢酸および残存共沸剤を導管１
４により酢酸分離塔Ｆに供給する。この場合残存
共沸剤の量は残りの酢酸を共沸するに必要な量以
上とするのが好ましいが、不足する場合、前述の
通り供給液に別途共沸剤を補給すれば良い。酢酸
分離塔Ｆは好ましくは塔頂より重合防止剤を添加
しながら、好ましくは減圧下で蒸留し、塔底より
アクリル酸を得る。酢酸、アクリル酸を含む共沸
剤の一部を導管１８より還流し、残りは導管１６
により脱水塔Ｅにリサイクルする。
脱水塔Ｅ、酢酸分離塔Ｆの減圧度を塔底温度が
100℃以下となる様に調製するのが好ましい。用
いる水及び酢酸のそれぞれと共沸混合物をつくる
共沸剤はその沸点がアクリル酸の沸点より低く、
好ましくは120〜80℃であることが望ましい。こ
れは120℃以下であれば、酢酸分離塔においてア
クリル酸との分離が容易であり80℃以上であれば
脱水塔の塔底液に共沸剤を残し易くする為であ
る。
本発明に使用される水と酢酸のそれぞれと共沸
する共沸剤には、トルエン、ヘプタン、メチル―
シクロヘキサン、シクロヘキサン、エチルベンゼ
ン、イソブチルエーテル、シクロヘキセン、及び
シクロヘキサジエン等がある。これらの共沸剤ま
たは該共沸剤の混合物を使用すればアクリル酸水
溶液から容易に水を除去できるとともに、酢酸の
大部分を脱水塔で留去することも出来る。
又これらの共沸剤はアクリル酸と共沸混合物を
形成しないので、脱水塔でアクリル酸が塔頂に上
り難く、アクリル酸の損失を極小にすることが出
来る。
又共沸剤にはトルエン、シクロヘキサン、メチ
ルシクロヘキサン等の如く実質的に水に溶解しな
いものが特に好ましい。その理由は脱水塔の塔頂
冷却液の水相中へ移行して損失となる共沸剤が実
際上無視出来る為である。
次に実施例を示すが、本発明は実施例に限定さ
れることはない。下記実施例中、溶液の組成は重
量％を表わす。
なお本発明に使用される共沸剤の代表的なもの
を上述したが、これらの水との共沸混合物及び酢
酸との共沸混合物の常圧の沸点を第１表に示す。
このデータは“アゼオトロピツクデータ”より得
たものである。
The present invention relates to a method for purifying acrylic acid while preventing its polymerization. More specifically, when separating and purifying impurities such as acetic acid from a crude acrylic acid aqueous solution obtained by catalytic gas phase oxidation of propylene and/or acrolein with molecular oxygen, it is necessary to prevent the polymerization of acrylic acid in the purification equipment. The present invention also relates to a method for purifying acrylic acid with a high recovery rate using a simplified device. When propylene and/or acrolein are oxidized with molecular oxygen in the presence of water vapor using an oxidation catalyst, in addition to the target acrylic acid, acetic acid, formic acid, acetaldehyde, formaldehyde, carbon dioxide gas, carbon monoxide, etc. are produced. A mixed gas containing side reaction products of , unreacted propylene and acrolein is obtained. When this reaction product gas is cooled and/or absorbed with water, acrylic acid and acetic acid,
An aqueous solution containing formic acid and aldehydes is obtained. Acetic acid is produced in the largest amount among the by-products, and its separation is a particularly important operation in the acrylic acid purification process. An object of the present invention is to separate and recover acrylic acid substantially free of water and side-reactants such as acetic acid and aldehydes from such a crude acrylic acid aqueous solution in an industrially advantageous manner while preventing polymerization. . Conventionally, the process of purifying acrylic acid from a crude acrylic acid aqueous solution that has been carried out industrially includes the method shown in Figure 1 (Chem.Eng. p. 78,
July 14, 1969). This method will be explained below. A crude acrylic acid aqueous solution obtained by condensing the oxidized gas containing acrylic acid produced by the catalytic gas phase oxidation reaction of propylene and/or acrolein is supplied to the extraction column A through conduit 1, and further conduit 8
An extractant is supplied from the extractor, and an extract obtained by extracting acrylic acid and the like is obtained from the conduit 2 and is supplied to the extraction separation column B. Water and extractant in the extract liquid are removed in extractant separation tower B, and water is supplied to extractant recovery tower D through conduit 5,
The extractant is returned to extraction column A via conduit 4. The bottom liquid of extractant separation tower B is a mixture of acrylic acid and acetic acid,
The acetic acid is supplied through a conduit 3 to an acetic acid separation column (hereinafter referred to as an acetic acid separation and distillation column) C, the acetic acid is discarded through a conduit 7, and acrylic acid containing no acetic acid is obtained through a conduit 6. The raffinate from the extraction column A is passed through a conduit 9 to an extractant recovery column D, where the extractant is recovered, and then recycled to the extraction column via a conduit 11. The water from which the extractant has been collected is transferred to conduit 10.
will be disposed of through. This conventional method has the following drawbacks. That is, this purification device is a complicated device having an extraction column and three distillation columns, and the construction cost is high and the recovery rate of acrylic acid is low. That is, it is difficult to recover the entire amount of acrylic acid from the crude acrylic acid aqueous solution using an extraction column, and the total amount of acrylic acid in the raffinate is lost. Furthermore, in the acetic acid separation column, due to the chemical similarity between acrylic acid and acetic acid, their specific volatility is not large, so a large number of plates and a high reflux ratio are required. Even under such conditions, there is still a considerable amount of acrylic acid distilled from the top of the acetic acid separation column. More importantly, polymerization of acrylic acid occurs in the acetic acid separation column, and acrylic acid polymers accumulate inside the column, increasing the pressure at the bottom of the distillation column, which can easily cause problems that may make operation impossible. This fact is well known to those skilled in the art (Japanese Patent Publication No. 49-24898). On the other hand, when separating acrylic acid and acetic acid, a method has been proposed in which toluene is added as an azeotropic agent to the distillation column to facilitate separation from acetic acid (Tokuko Sho).
41-11247), in this method, acrylic acid from the top of the acetic acid separation column is eventually discharged from the bottom of the solvent recovery column, resulting in a loss. This method has the disadvantage that the number of plates in the acetic acid separation column and the reflux ratio must be increased in order to prevent the loss. Furthermore, in this method, in order to recover the azeotropic agent toluene from the top liquid of the acetic acid separation column, it is necessary to add water and recover it by azeotropy. For this purpose, a distillation column is required, and as mentioned above, acrylic acid cannot be recovered using this distillation column. In addition, many proposals for improving the azeotropic distillation method described above have been published. For example, Japanese Patent Publication No. 46-20372 proposes a method for simultaneously distilling and separating water and acetic acid from an aqueous acrylic acid solution using a mixture of toluene and alcohol as an azeotropic agent. However, the results of the research conducted by the present inventors have revealed that this method has many drawbacks and includes unresolved problems before it can be adopted industrially. In other words, an advantageous condition for an entrainer is that it is substantially insoluble in water, but aliphatic alcohols with about 4 carbon atoms have a fairly high solubility in water, making it difficult to recover alcohol from wastewater. It becomes necessary. Furthermore, when the bottom liquid of the azeotropic distillation column is used as a product, the bottom liquid must not contain an azeotropic agent. However, there is a contradiction in that acetic acid cannot be effectively removed in an operation in which an azeotropic agent is not present at the bottom of the distillation column.
Acrylic acid is mixed into the wastewater at the top of the tower, increasing losses of acrylic acid. More importantly, acrylic acid polymerizes from the middle of the distillation column to near the top of the column, resulting in a fatal disadvantage of increased pressure loss in the column. This phenomenon is presumed to be similar to that of the conventional acetic acid separation column described above. The inventors of the present invention conducted various studies in order to eliminate the drawbacks of these prior art techniques, and as a result, discovered a new method as described below. (1) A dehydration column (meaning a dehydration distillation column, hereinafter the same) and an acetic acid separation column (meaning an acetic acid separation and distillation column, the same hereinafter) are prepared as column-type distillation columns. (2) For the distillation of crude acrylic acid aqueous solution in the dehydration tower or for the distillation of acrylic acid containing acetic acid in the acetic acid separation tower, an entrainer or a mixture of such entrainers that satisfies the following conditions is used. (a) Azeotropes with water and acetic acid, respectively. (b) It is sparingly soluble in water. (c) Not azeotropic with acrylic acid. (3) In the dehydration tower, all of the water and part of the acetic acid in the crude aqueous acrylic acid solution are distilled off from the top of the tower together with the azeotropic agent. (4) In the acetic acid separation tower, acetic acid and acrylic acid extracted from the bottom of the dehydration tower are distilled with the azeotropic agent, and all of the acetic acid and a small amount of acrylic acid are extracted from the top of the tower together with the azeotropic agent. part is recycled to the dehydration tower (refluxed to the own tower). Incidentally, the term "poorly soluble" as used herein means a solubility in water of 5% by weight or less at 20°C. This new method makes it possible to reduce the number of stages in the acetic acid separation column and to reduce the reflux ratio compared to the conventional method. It was also confirmed that this method causes almost no loss of acrylic acid and can be operated continuously for a long period of time, thus completing the present invention. It has already been mentioned that separation of acetic acid is a particularly important operation in the acrylic acid purification process. Also, those skilled in the art are well aware that this separation is the most difficult step. The present invention can be said to be an epoch-making method that solves this problem. The gist of the present invention is to ``cool the gas produced by catalytic gas phase oxidation of propylene and/or acrolein with molecular oxygen.
or (and) an aqueous solution of crude acrylic acid obtained by absorption in water, or a solution from which aldehydes have been removed by stripping in advance, and an azeotropic agent that satisfies the following conditions (a), (b), and (c). (a) Azeotropes with water and acetic acid, respectively. (b) It is sparingly soluble in water. (c) Not azeotropic with acrylic acid. Alternatively, the mixture of entrainers is supplied to a dehydration distillation column and distilled, substantially all of the water, formic acid and a portion of the acetic acid in the crude acrylic acid aqueous solution are distilled off, and the remaining acrylic acid of the acetic acid is distilled off. The acid is extracted as a bottom liquid and led to an acetic acid separation and distillation column, in which
The remaining acetic acid is distilled off from the top of the column together with the entrainer, purified acrylic acid is recovered from the bottom of the column, and the mixed liquid of acetic acid, acrylic acid, and entrainer obtained from the top of the column is recycled to the dehydration distillation column. A method for purifying acrylic acid characterized by: ”. In summary, the features of the present invention are that acetic acid is partially separated in a dehydration tower, and the top liquid of the acetic acid separation tower is not only refluxed to the own tower but also recycled to the dehydration tower, thereby eliminating loss of acrylic acid to the outside of the system. The present invention has succeeded in significantly reducing the load on the acetic acid separation column (making it possible to reduce the number of plates in the distillation column and the reflux ratio) and preventing polymerization of acrylic acid during distillation. The amount of acetic acid distilled off from the top of the dehydration tower is preferably 50% by weight or more, more preferably 75% by weight or more of the acetic acid contained in the crude aqueous acrylic acid solution. It is also preferable to remove the acrylic acid, the remaining acetic acid, and an amount of azeotropic agent necessary for azeotropic distillation of the acetic acid from the bottom of the dehydration tower, and then supply this liquid to the next acetic acid separation tower. However, if there is no entrainer in the bottom liquid of the dehydration tower, or if it is insufficient to azeotropically distill acetic acid, the acetic acid separation tower is supplemented with the entrainer.
It is sufficient if the acetic acid supplied to the acetic acid separation column can be azeotropically distilled. That is, it is sufficient that the acetic acid separation column is supplied with an amount of the azeotropic agent that is at least sufficient to carry out azeotropic distillation of the acetic acid supplied to this column. An embodiment of the present invention will be specifically illustrated with reference to FIG. First, a crude acrylic acid aqueous solution obtained by catalytically oxidizing a raw material gas consisting of propylene, air, and steam is cooled and/or absorbed with water, and is supplied to the dehydration tower E through a conduit 12. This crude acrylic acid aqueous solution may be one in which aldehydes contained as impurities have been removed by stripping in advance, or a solution without removal may also be used. The above-mentioned azeotropic agent is supplied to the dehydration tower E through the conduit 16, and distillation is preferably carried out under reduced pressure while preferably adding a polymerization inhibitor from the top of the tower. When the vapor from the top of the column is condensed, it forms an azeotropic agent phase with the aqueous phase, which consists essentially of all the water, formic acid and aldehydes, and a portion of acetic acid in the crude aqueous acrylic acid solution; It is discarded through conduit 13. On the other hand, the entire amount of the entrainer phase is refluxed to the dehydration tower E through the conduit 15.
The reflux amount of the entrainer is greater than the amount necessary to azeotropically remove all of the water and part of the acetic acid in the dehydration tower with the addition of the entrainer supplied through conduit 16. Transfer acrylic acid, remaining acetic acid and remaining entrainer to conduit 1
4 to the acetic acid separation column F. In this case, it is preferable that the amount of the remaining entrainer be at least the amount necessary to azeotropically distill the remaining acetic acid, but if it is insufficient, the entrainer may be separately replenished to the feed liquid as described above. The acetic acid separation column F carries out distillation, preferably under reduced pressure, while adding a polymerization inhibitor from the top of the column, and obtains acrylic acid from the bottom of the column. A portion of the azeotropic agent containing acetic acid and acrylic acid is refluxed through conduit 18, and the remainder is refluxed through conduit 16.
It is recycled to dehydration tower E. The degree of pressure reduction in dehydration tower E and acetic acid separation tower F is determined by the bottom temperature.
Preferably, the temperature is adjusted to 100°C or less. The azeotropic agent that forms an azeotropic mixture with each of water and acetic acid used has a boiling point lower than the boiling point of acrylic acid;
The temperature is preferably 120 to 80°C. This is because if the temperature is 120°C or lower, separation from acrylic acid is easy in the acetic acid separation tower, and if it is 80°C or higher, the azeotropic agent is likely to remain in the bottom liquid of the dehydration tower. The azeotropic agents used in the present invention that are azeotropic with water and acetic acid include toluene, heptane, methyl-
Examples include cyclohexane, cyclohexane, ethylbenzene, isobutyl ether, cyclohexene, and cyclohexadiene. If these entrainers or a mixture of these entrainers are used, water can be easily removed from an aqueous acrylic acid solution, and most of the acetic acid can also be distilled off in a dehydration tower. Furthermore, since these entrainers do not form an azeotrope with acrylic acid, acrylic acid is difficult to rise to the top of the dehydration tower, and loss of acrylic acid can be minimized. Further, it is particularly preferable that the entrainer is one that is substantially insoluble in water, such as toluene, cyclohexane, methylcyclohexane, and the like. The reason for this is that the loss of the entrainer that is transferred to the aqueous phase of the top cooling liquid of the dehydration tower can be practically ignored. Examples will be shown next, but the present invention is not limited to the examples. In the following examples, the composition of the solution is expressed in % by weight. Typical azeotropic agents used in the present invention have been described above, and Table 1 shows the boiling points at normal pressure of these azeotropic mixtures with water and acetic acid.
This data was obtained from "Azeotropic Data".
【表】
実施例 １
脱水塔は塔頂圧110mmＨｇで操作し、アクリル
酸45.5％、酢酸3.2％、キ酸0.4％と若干のホルム
アルデヒドを含む水溶液を、毎時16.7Kg脱水塔に
供給した。このアクリル酸水溶液は、プロピレン
の接触気相酸化反応によつて得られた生成ガスを
凝縮させ、さらにアセトアルデヒド、アセトン、
アクロレイン等の軽沸点物を除去したものであ
る。さらに脱水塔には酢酸分離塔の留出液である
アクリル酸、酢酸を含むトルエン溶液を添加して
蒸留を行つた。塔頂液は２相に分離し、共沸剤の
トルエン相は全て還流した。還流量は毎時64Kgで
あつた。この還流液に重合防止剤として、ハイド
ロキノンを毎時20ｇ添加した。一方、水相は酢酸
5.7％、ギ酸0.8％、アクリル酸0.2％であつた。塔
底液としてアクリル酸82.9％、酢酸1.8％を毎時
10.2Kg得た。このとき塔頂温度は約40℃、塔底温
度は約80℃であつた。酢酸分離塔は段数30段の棚
段塔を用い塔頂圧60mmＨｇで操作し、上記脱水液
を供給して、還流比を2.0で運転したところ、塔
頂よりアクリル酸33.2％、酢酸6.6％を含むトル
エン溶液を留出し、これを脱水塔のアクリル酸水
液の供給配管に戻した。還流液には重合防止剤と
して、ハイドロキノンを毎時20ｇ添加した。塔底
より酢酸濃度0.1％以下のアクリル酸を毎時7.6Kg
得た。この時塔頂温度は約55℃、塔底温度は約85
℃であつた。アクリル酸の回収率は99.5％以上で
あり、アクリル酸の純度は99％以上であつた。
この様にして、脱水塔と酢酸分離塔を１ケ月連
続運転したところ、運転開始時から塔底温度が約
0.5℃上昇したのみで、蒸留塔の運転続行には何
ら支障がなかつた。
比較例
実施例で用いた脱水塔、酢酸分離塔を用い、は
じめ実施例と同様に運転し、其の後脱水塔での共
沸剤の還元量を減少させ、該塔底に共沸剤を存在
させない様にし、これを次の酢酸分離塔に供給し
且この塔に共沸剤を補給することなく運転を継続
したところ、酢酸分離塔の塔頂液中の酢酸濃度が
徐々に増加するとともに、該塔底液中のアクリル
酸に酢酸が混入した。このため酢酸分離塔の塔頂
液抜出量を２倍とし、還流比を5.0まで上昇させ
たところ、初め塔底圧100mmＨｇで、塔底温度が
約87℃であつたものが、塔底圧が120mmＨｇまで
上昇し、フラツデングが生じ運転続行が不可能と
なつた。運転停止後、酢酸分離塔を開放したとこ
ろ、供給段から塔頂付近にアクリル酸の重合物が
あつた。
なお以上の比較例においても各塔の還流液にハ
イドロキノンをそれぞれ毎時20ｇ添加した。[Table] Example 1 The dehydration tower was operated at a tower top pressure of 110 mmHg, and 16.7 kg of an aqueous solution containing 45.5% acrylic acid, 3.2% acetic acid, 0.4% phosphoric acid, and some formaldehyde was supplied to the dehydration tower every hour. This acrylic acid aqueous solution is produced by condensing the gas produced by the catalytic gas phase oxidation reaction of propylene, and further producing acetaldehyde, acetone,
Light boiling point substances such as acrolein have been removed. Furthermore, a toluene solution containing acrylic acid and acetic acid, which was a distillate from the acetic acid separation tower, was added to the dehydration tower to perform distillation. The top liquid was separated into two phases, and the toluene phase of the entrainer was all refluxed. The reflux rate was 64 kg/hour. To this reflux liquid, 20 g of hydroquinone was added per hour as a polymerization inhibitor. On the other hand, the aqueous phase is acetic acid
5.7%, formic acid 0.8%, and acrylic acid 0.2%. 82.9% acrylic acid and 1.8% acetic acid per hour as bottom liquid
I gained 10.2Kg. At this time, the tower top temperature was about 40°C and the tower bottom temperature was about 80°C. The acetic acid separation column was a tray column with 30 plates and was operated at a column top pressure of 60 mmHg, and the above dehydrated liquid was supplied and the column was operated at a reflux ratio of 2.0. As a result, 33.2% of acrylic acid and 6.6% of acetic acid were removed from the top of the column. The toluene solution containing the toluene solution was distilled out and returned to the acrylic acid aqueous solution supply pipe of the dehydration tower. 20 g of hydroquinone was added per hour to the reflux liquid as a polymerization inhibitor. 7.6 kg of acrylic acid with an acetic acid concentration of 0.1% or less from the bottom of the tower per hour.
Obtained. At this time, the tower top temperature is approximately 55℃, and the tower bottom temperature is approximately 85℃.
It was warm at ℃. The recovery rate of acrylic acid was 99.5% or more, and the purity of acrylic acid was 99% or more. When the dehydration tower and acetic acid separation tower were operated continuously in this way for one month, the bottom temperature of the tower was approximately
The temperature rose only by 0.5°C, and there was no problem in continuing operation of the distillation column. Comparative Example Using the dehydration tower and acetic acid separation tower used in the example, the operation was initially performed in the same manner as in the example, and then the amount of reduction of the entrainer in the dehydration tower was reduced, and the entrainer was added to the bottom of the tower. When the acetic acid was supplied to the next acetic acid separation column and the operation was continued without replenishing the azeotropic agent, the acetic acid concentration in the top liquid of the acetic acid separation column gradually increased. , acetic acid was mixed into the acrylic acid in the bottom liquid. For this reason, when the amount of top liquid withdrawn from the acetic acid separation column was doubled and the reflux ratio was raised to 5.0, the bottom pressure was 100 mmHg and the bottom temperature was approximately 87°C, but the bottom pressure The temperature rose to 120mmHg, and flattening occurred, making it impossible to continue operation. After the operation was stopped, the acetic acid separation tower was opened, and a polymer of acrylic acid was found near the top of the tower from the feed stage. In the above comparative examples, 20 g of hydroquinone was added per hour to the reflux liquid of each tower.
第１図は従来法によるアクリル酸精製装置のフ
ローシート、第２図は本発明の実施態様のフロー
シートの例示である。
１…導管（粗アクリル酸水溶液）、２…導管
（抽出液）、３…導管（アクリル酸、酢酸混液）、
４…導管（抽剤）、５…導管（水）、６…導管（ア
クリル酸）、７…導管（酢酸）、８…導管（抽剤）、
９…導管（抽残液）、１０…導管（水）、１１…導
管（抽剤）、Ａ…抽出塔、Ｂ…抽剤分離塔、Ｃ…
酢酸分離塔、Ｄ…抽剤回収塔、１２…導管（粗ア
クリル酸水溶液）、１３…導管（水相）、１４…導
管（アクリル酸、酢酸及び共沸剤混液）、１５…
導管（共沸剤相）、１６…導管（リサイクル液）、
１７…導管（アクリル酸）、１８…導管（還流
液）、Ｅ…脱水塔、Ｆ…酢酸分離塔。
FIG. 1 is a flow sheet of an acrylic acid purification apparatus according to a conventional method, and FIG. 2 is an example of a flow sheet of an embodiment of the present invention. 1... Conduit (crude acrylic acid aqueous solution), 2... Conduit (extract liquid), 3... Conduit (acrylic acid, acetic acid mixture),
4... Conduit (extraction agent), 5... Conduit (water), 6... Conduit (acrylic acid), 7... Conduit (acetic acid), 8... Conduit (extraction agent),
9... Conduit (raffinate liquid), 10... Conduit (water), 11... Conduit (extraction agent), A... Extraction column, B... Extractant separation column, C...
Acetic acid separation column, D... Extractant recovery column, 12... Conduit (crude acrylic acid aqueous solution), 13... Conduit (aqueous phase), 14... Conduit (acrylic acid, acetic acid and azeotropic agent mixture), 15...
Conduit (azeotropic agent phase), 16... Conduit (recycle liquid),
17... Conduit (acrylic acid), 18... Conduit (reflux liquid), E... Dehydration tower, F... Acetic acid separation tower.
Claims (1)
分子状酸素で接触気相酸化した生成ガスを冷却、
または（および）水に吸収して得られる粗アクリ
ル酸水溶液又は該液のアルデヒド類を予めストリ
ツピングにより除去した液と次の(a)，(b)及び(c)の
条件を満足する共沸剤 (a) 水と酢酸のそれぞれと共沸する。 (b) 水に難溶である。 (c) アクリル酸とは共沸しない。 または該共沸剤の混合物とを脱水蒸留塔に供給
して蒸留し、実質的に上記粗アクリル酸水溶液中
の全ての水及びギ酸並びに酢酸の一部を留去し、
酢酸の残存するアクリル酸を塔底液として抜き出
して酢酸分離蒸留塔に導き、該塔において、残り
の酢酸を前記共沸剤とともに塔頂より留去し、塔
底より精製アクリル酸を回収し、塔頂から得られ
る酢酸、アクリル酸および共沸剤の混合液を前記
の脱水蒸留塔にリサイクルすることを特徴とする
アクリル酸の精製法。 ２ 水及び酢酸それぞれと共沸混合物を形成する
共沸剤の沸点が80〜120℃の範囲内にある共沸剤
を使用する特許請求の範囲第１項記載の精製法。 ３ 脱水蒸留塔および酢酸分離蒸留塔の塔底温度
を100℃以下とする特許請求の範囲第１項又は同
第２項記載の精製法。[Claims] 1. Cooling the gas produced by catalytic gas phase oxidation of propylene and/or acrolein with molecular oxygen,
or (and) an aqueous solution of crude acrylic acid obtained by absorption in water, or a solution from which aldehydes have been removed by stripping in advance, and an azeotropic agent that satisfies the following conditions (a), (b), and (c). (a) Azeotropes with water and acetic acid, respectively. (b) It is sparingly soluble in water. (c) Not azeotropic with acrylic acid. or the mixture of the entrainers is supplied to a dehydration distillation column and distilled, substantially all of the water and part of the formic acid and acetic acid in the crude acrylic acid aqueous solution are distilled off;
Acrylic acid remaining in acetic acid is extracted as a bottom liquid and guided to an acetic acid separation and distillation column, in which the remaining acetic acid is distilled off from the top of the column together with the entrainer, and purified acrylic acid is recovered from the bottom of the column, A method for purifying acrylic acid, which comprises recycling a mixed solution of acetic acid, acrylic acid, and an entrainer obtained from the top of the column to the dehydration distillation column. 2. The purification method according to claim 1, which uses an azeotropic agent that forms an azeotrope with water and acetic acid and has a boiling point within the range of 80 to 120°C. 3. The purification method according to claim 1 or 2, wherein the bottom temperature of the dehydration distillation column and the acetic acid separation/distillation column is 100°C or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16759879A JPS5690034A (en) | 1979-12-25 | 1979-12-25 | Purification of acrylic acid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16759879A JPS5690034A (en) | 1979-12-25 | 1979-12-25 | Purification of acrylic acid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5690034A JPS5690034A (en) | 1981-07-21 |
| JPS6310691B2 true JPS6310691B2 (en) | 1988-03-08 |
Family
ID=15852729
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16759879A Granted JPS5690034A (en) | 1979-12-25 | 1979-12-25 | Purification of acrylic acid |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5690034A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0695736A1 (en) | 1994-08-04 | 1996-02-07 | Mitsubishi Chemical Corporation | Purification of acrylic acid by areotropic distillation |
| US6407287B2 (en) | 2000-03-08 | 2002-06-18 | Nippon Shokubai Co., Ltd. | Method for production of acrylic acid |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0615496B2 (en) * | 1983-08-12 | 1994-03-02 | 株式会社日本触媒 | Method for producing acrylic acid |
| JPH0615495B2 (en) * | 1983-08-11 | 1994-03-02 | 株式会社日本触媒 | Acrylic acid purification method |
| GB2146636B (en) * | 1983-08-11 | 1987-02-04 | Nippon Catalytic Chem Ind | Process for producing acrylic acid |
| EP1065197B1 (en) * | 1999-06-28 | 2002-11-06 | Rohm And Haas Company | Process for preparing (meth)acrylic acid |
| JP2007176951A (en) * | 2007-02-26 | 2007-07-12 | Nippon Shokubai Co Ltd | Method for producing (meth)acrylic acid |
-
1979
- 1979-12-25 JP JP16759879A patent/JPS5690034A/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0695736A1 (en) | 1994-08-04 | 1996-02-07 | Mitsubishi Chemical Corporation | Purification of acrylic acid by areotropic distillation |
| US6407287B2 (en) | 2000-03-08 | 2002-06-18 | Nippon Shokubai Co., Ltd. | Method for production of acrylic acid |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5690034A (en) | 1981-07-21 |
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