JPS6325569B2 - - Google Patents
Info
- Publication number
- JPS6325569B2 JPS6325569B2 JP15070682A JP15070682A JPS6325569B2 JP S6325569 B2 JPS6325569 B2 JP S6325569B2 JP 15070682 A JP15070682 A JP 15070682A JP 15070682 A JP15070682 A JP 15070682A JP S6325569 B2 JPS6325569 B2 JP S6325569B2
- Authority
- JP
- Japan
- Prior art keywords
- acrylic acid
- stage
- reaction
- concentrator
- wastewater
- 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
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 103
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 99
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 68
- 239000002351 wastewater Substances 0.000 claims description 57
- 238000006243 chemical reaction Methods 0.000 claims description 53
- 239000007789 gas Substances 0.000 claims description 48
- 238000000034 method Methods 0.000 claims description 38
- 239000002912 waste gas Substances 0.000 claims description 35
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 claims description 27
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 claims description 27
- HGINCPLSRVDWNT-UHFFFAOYSA-N Acrolein Chemical compound C=CC=O HGINCPLSRVDWNT-UHFFFAOYSA-N 0.000 claims description 24
- 238000007254 oxidation reaction Methods 0.000 claims description 21
- 239000007864 aqueous solution Substances 0.000 claims description 13
- 239000007788 liquid Substances 0.000 claims description 9
- 230000003647 oxidation Effects 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 230000003197 catalytic effect Effects 0.000 claims description 5
- 238000000926 separation method Methods 0.000 claims description 5
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 3
- 229910001882 dioxygen Inorganic materials 0.000 claims description 3
- 239000003054 catalyst Substances 0.000 description 26
- 238000010521 absorption reaction Methods 0.000 description 18
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 15
- 239000002994 raw material Substances 0.000 description 14
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 11
- 239000001301 oxygen Substances 0.000 description 11
- 229910052760 oxygen Inorganic materials 0.000 description 11
- 239000000126 substance Substances 0.000 description 11
- 238000009835 boiling Methods 0.000 description 10
- 239000007795 chemical reaction product Substances 0.000 description 8
- 230000007423 decrease Effects 0.000 description 8
- 238000000605 extraction Methods 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 238000004064 recycling Methods 0.000 description 7
- 239000002904 solvent Substances 0.000 description 7
- 239000003701 inert diluent Substances 0.000 description 6
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- IKHGUXGNUITLKF-XPULMUKRSA-N acetaldehyde Chemical compound [14CH]([14CH3])=O IKHGUXGNUITLKF-XPULMUKRSA-N 0.000 description 5
- 239000002253 acid Substances 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- 239000012141 concentrate Substances 0.000 description 4
- 238000006116 polymerization reaction Methods 0.000 description 4
- 230000002829 reductive effect Effects 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 239000006227 byproduct Substances 0.000 description 3
- 238000009841 combustion method Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 239000003112 inhibitor Substances 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- APUPEJJSWDHEBO-UHFFFAOYSA-P ammonium molybdate Chemical compound [NH4+].[NH4+].[O-][Mo]([O-])(=O)=O APUPEJJSWDHEBO-UHFFFAOYSA-P 0.000 description 2
- 239000011609 ammonium molybdate Substances 0.000 description 2
- 229940010552 ammonium molybdate Drugs 0.000 description 2
- 235000018660 ammonium molybdate Nutrition 0.000 description 2
- 238000010533 azeotropic distillation Methods 0.000 description 2
- 238000007084 catalytic combustion reaction Methods 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- XAYGUHUYDMLJJV-UHFFFAOYSA-Z decaazanium;dioxido(dioxo)tungsten;hydron;trioxotungsten Chemical compound [H+].[H+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O XAYGUHUYDMLJJV-UHFFFAOYSA-Z 0.000 description 2
- XBDQKXXYIPTUBI-UHFFFAOYSA-N dimethylselenoniopropionate Natural products CCC(O)=O XBDQKXXYIPTUBI-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 description 2
- -1 maleic acid Chemical class 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 150000007524 organic acids Chemical class 0.000 description 2
- 235000005985 organic acids Nutrition 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000010802 sludge Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- JOSWYUNQBRPBDN-UHFFFAOYSA-P ammonium dichromate Chemical compound [NH4+].[NH4+].[O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O JOSWYUNQBRPBDN-UHFFFAOYSA-P 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- UNTBPXHCXVWYOI-UHFFFAOYSA-O azanium;oxido(dioxo)vanadium Chemical compound [NH4+].[O-][V](=O)=O UNTBPXHCXVWYOI-UHFFFAOYSA-O 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 description 1
- 229910001981 cobalt nitrate Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000008236 heating water Substances 0.000 description 1
- RXPAJWPEYBDXOG-UHFFFAOYSA-N hydron;methyl 4-methoxypyridine-2-carboxylate;chloride Chemical compound Cl.COC(=O)C1=CC(OC)=CC=N1 RXPAJWPEYBDXOG-UHFFFAOYSA-N 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- JMMWKPVZQRWMSS-UHFFFAOYSA-N isopropanol acetate Natural products CC(C)OC(C)=O JMMWKPVZQRWMSS-UHFFFAOYSA-N 0.000 description 1
- 229940011051 isopropyl acetate Drugs 0.000 description 1
- GWYFCOCPABKNJV-UHFFFAOYSA-N isovaleric acid Chemical compound CC(C)CC(O)=O GWYFCOCPABKNJV-UHFFFAOYSA-N 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 1
- 239000011976 maleic acid Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000011165 process development Methods 0.000 description 1
- 235000019260 propionic acid Nutrition 0.000 description 1
- IUVKMZGDUIUOCP-BTNSXGMBSA-N quinbolone Chemical compound O([C@H]1CC[C@H]2[C@H]3[C@@H]([C@]4(C=CC(=O)C=C4CC3)C)CC[C@@]21C)C1=CCCC1 IUVKMZGDUIUOCP-BTNSXGMBSA-N 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Description
本発明はプロピレンを接触気相酸化してアクリ
ル酸を製造するプロセスにおいて、発生する廃水
の有効利用ならびに無害化処理法に関するもので
ある。詳しく述べると本発明は、水蒸気および分
子状酸素含有ガスを用いて、前段反応としてプロ
ピレンから主としてアクロレイン、後段反応とし
てアクロレインからアクリル酸へそれぞれ接触気
相酸化してアクリル酸を製造するプロセスにおい
て、該酸化反応で生成したアクリル酸を水溶液と
して捕集したあとの廃ガスの一部を該前段酸化反
応用に循環使用し、一方捕集されたアクリル酸水
溶液をアクリル酸分離工程に導びき、えられた廃
水を２重効用缶を用いて濃縮し、１段目の濃縮缶
でえられる廃水の蒸気を該後段酸化反応用に循環
使用し、２段目の濃縮缶でえられる廃水蒸気を１
段目濃縮缶の熱源に用い、えられる凝縮水を生成
アクリル酸の捕集用に循環使用し、さらに２段目
の濃縮缶でえられる濃縮廃水を上記廃ガスの残部
とともに完全酸化処理せしめることを特徴とする
アクリル酸のクローズドシステム化された製造方
法に関する。
本発明者らは、すでに特願昭51−25602号（特
開昭52−108917号公報参照）「プロピレンの接触
気相酸化によるアクリル酸の製造方法」によつ
て、「プロピレンを前段および後段反応器を通し
てアクリル酸に酸化し、えられた反応生成ガスを
アクリル酸捕集装置にてアクリル酸水溶液と廃ガ
スにわけ、その廃ガスの一部を前段での反応用に
循環使用するプロセス」を提供した。そしてその
特徴とするところは「廃ガスを前段反応に再使用
する際に廃ガスの一部を含む反応用原料ガス中の
アクリル酸濃度が0.5容量％を越えないようにす
るためアクリル酸捕集装置からの廃ガスの排出温
度を35〜80℃の範囲に保持し、かつ該廃ガスの15
〜85％を前段反応器に循環せしめること」とし
た。そしてこの方法によつて「プロピレンからア
クリル酸が長期間高収率でかつ高濃度な水溶液と
してえられる目的も達成でき、その結果、反応お
よび精製工程でのユーテイリテイーの低減、排水
量の減少、アクリル酸の収率の増大等が達成さ
れ、極めて工業的に有利なプロセス」が提案され
たのである。
そこで、本発明者らは、上記発明方法をさらに
工業的に完成されたものとすべく検討した。すな
わち、廃ガスのリサイクル利用はそのまゝとして
該プロセスから排出する廃水を再使用する方法に
ついて集中して研究し、クローズドプロセス化さ
れた本発明方法を完成するに至つたものである。
プロピレンを接触気相酸化してアクリル酸を製
造するプロセスにおいては多量の廃水が排出す
る。すなわち、該酸化反応における原料ガス中に
かなりの量の水蒸気が混合使用され、反応によつ
て生成する副生水と共に反応生成物の捕集装置に
送られる。捕集装置においては、主生成物たるア
クリル酸と共に上記水蒸気も凝縮捕集されるが、
この場合、吸収水にて直接接触せしめて冷却凝縮
せしめる方法が一般的であり、かくして通常20〜
70重量％のアクリル酸水溶液が回収される。この
水溶液からはつぎの抽出または共沸蒸留工程でア
クリル酸が分離されるとき多量の廃水が排出され
てくる。この廃水の中には、未回収のアクリル酸
や副生の酢酸やプロピオン酸の他に微量のマレイ
ン酸などの有機酸、さらにアクロレイン、ホルル
アルデヒド、アセトアルデヒドなどのアルデヒド
類、あるいはこれら化合物からの種々の誘導体、
さらに抽出や共沸蒸留用の有機溶媒や重合防止剤
などが合計で0.5〜５重量％程度含有されている。
このようなかなりの量の有機物を含んだ廃水はそ
のまま河川へ放流することはできないので、活性
汚泥法とか濃縮燃焼法などで無害化処理をせねば
ならない。しかし、上記の活性汚泥法は設備費や
経費も小さくはなく、また無公害化処理も完全に
行い難く、一方、濃縮燃焼法もこのような廃水全
部をそのまま処理するにはこれもまた設備費や経
費も高くつくプロセスとならざるをえない。
したがつて、このように公害源となりやすいプ
ロセス廃水をいかに効率よく浄化するかはきわめ
て焦眉の工業上の大きな課題の一つといえるであ
ろう。
一方、上述したようにアクリル酸を製造するプ
ロセスには、水蒸気や冷却吸収水としての水の使
用量が多いためもあり、この廃水を再び該製造プ
ロセスに戻すことも、プロセス開発上強く要望さ
れていることである。
本発明者は該廃水をプロセス内に戻して再使用
する方法を種々検討した。まず、廃水をそのまゝ
アクリル酸の捕集用の吸収水として再使用する
と、この吸収水−アクリル酸水溶液−廃水の系内
に有機酸やその他種々な不純物が濃縮蓄積して行
き、遂にはある一定の平衡濃縮に達し、それ以降
はアクリル酸とともに同伴して抽出されたりして
最終製品であるアクリル酸に混入し、品質が低下
することが判明した。
さらに悪いことには、アクリル酸の捕集塔から
の廃ガスの一部を酸化反応の原料ガスの一部とし
て使用する廃ガスリサイクルプロセスにおいて、
アクリル酸捕集用の吸収水として酸濃度の高くな
つた廃水を再使用すると、アクリル酸の捕集率が
低下するばかりでなく、酸化反応における触媒の
活性も次第に低下し阻害され、アクリル酸の収率
の低下をきたすことが判明した。吸収水としての
廃水の酸分の増加によりアクリル酸捕集装置での
アクリル酸の捕集効率も低下し、その分リサイク
ルされる廃ガス中に同伴されるためである。した
がつて、廃水を無処理のままで再使用することは
不都合であることが明らかとなつた。
このような問題を解決するため、本発明者らは
２重効用缶を使つて廃水を濃縮し、廃水から蒸発
してえられる凝縮水を再利用し、濃縮される廃水
の無害化処理を検討したところ、１段目の濃縮缶
からえられる廃水からの蒸気をそのまま後段酸化
反応用に後段反応器へ循環せしめ、２段目の濃縮
缶からえられる廃水の蒸気を１段目の濃縮缶の熱
源として使用し、えられる凝縮液が吸収水として
利用できること、２段目の濃縮缶でえられる濃縮
廃水はアクリル酸を捕集したあとの廃ガスの残部
とともに完全酸化処理せしめることが有利である
ことを見出し、本発明を完成するに至つたもので
ある。
すなわち、２段目の濃縮缶からえられる廃水凝
縮液のアクリル酸捕集用吸収水としての利用は、
なんら上述したような不都合を生せず、アクロレ
イン、ホルムアルデヒド、アセトアルデヒドなど
の軽沸点物の蓄積も起らず、アクリル酸の捕集も
高水準を維持しうることがわかり、一方、１段目
の濃縮缶からえられたアクロレイン、ホルムアル
デヒド、アセトアルデヒドなどの軽沸点物と少量
のアクリル酸分を同伴する廃水の水蒸気は後段反
応器へ循環使用してもなんら不都合とならないこ
とが知見されたのである。
本発明においては、反応に必要な水蒸気は実質
的に１段目の濃縮缶の廃水の蒸気により供給され
るために、アクリル酸捕集装置で吸収水が供給さ
れる吸収塔の塔頂温度は任意に設定することがで
き、できるだけ低く設定することによりアクリル
酸や水蒸気を実質的に凝縮吸収させ、廃ガス中へ
同伴されて排出される酸分がほとんどゼロとなる
ように操作しうる。工業的には一般に安価に入手
できる冷水塔水を使用しての冷却となるため、塔
頂温度40℃以下、好ましくは25〜40℃とする。吸
収塔の塔頂温度をできるだけ低く設定することに
より、吸収塔におけるアクリル酸の捕集が容易に
なり、吸収塔の塔高を低くできる。また廃水の濃
縮による凝縮水をアクリル酸を捕集する吸収水と
して使用することにより、従来廃水からそのまま
捨てられていたアクリル酸を回収することができ
る。またリサイクルされる廃ガスの温度が低いた
め、リサイクルするガス風量が小さくなり、リサ
イクル用ブロワーを小さくすることができる。
反応用水蒸気として使用する廃水の水蒸気は、
後段反応器へ好都合に循環使用される。というの
は、プロピレンを前段および後段反応器を通して
アクリル酸に酸化する反応において、反応で水蒸
気を必要とするのは主として後段触媒であり、一
方前段触媒は原料ガス中におけるアクリル酸分が
0.5容量％以下、とくに0.3容量％以下に調節しな
ければならないという制約があるからである。そ
して反応用水蒸気として後段反応器へ循環使用す
ると原料ガス中のプロピレンの濃度を高くでき
る、即ち投入する水蒸気の容量だけ前段反応器の
原料ガスの容量を小さくすることができ、結果的
には前段反応器を小さくすることができるからで
ある。
吸収水として使用する廃水の凝縮水は、２段目
の濃縮缶の水蒸気からのものを好都合に用いう
る。というのは、１段目の濃縮缶の水蒸気にはア
クロレイン、ホルムアルデヒド、アセトアルデヒ
ドなどの軽沸点物を含むゆえ吸収水として循環再
使用すると吸収水−アクリル酸水溶液−廃水の系
内に濃縮蓄積して行き、アクリル酸とともに同伴
して抽出されたりして、アクリル酸の精製工程で
の重合性の問題、最終製品であるアクリル酸にも
混入して品質が低下するからである。そこで、吸
収水としては、廃水に含まれる軽沸点物が除去さ
れた２段目の濃縮缶の廃水の凝縮水を用いる。
一方、アクロレイン、ホルムアルデヒド、アセ
トアルデヒドなどの軽沸点物を含む１段目の濃縮
缶の水蒸気は反応用水蒸気として後段反応器へ循
環使用される。軽沸点物は反応器内で酸化燃焼さ
れるため系内には軽沸点物は濃縮蓄積しない。
２段目の濃縮缶からえられる濃縮廃液中には
種々の固形物やタール状物質などが混入してお
り、必要に応じて過器を通過せしめたのち、捕
集装置からの廃ガスのうち、循環分を除いた残部
ガスとともに完全酸化処理され無公害化処理され
る。
完全酸化処理装置は、触媒燃焼方式または燃料
と混合して燃焼させる直燃方式とが採用しうる
が、有利には触媒燃焼方式が採用でき、しかもハ
ニカム状の担体に白金、パラジウムなどの貴金属
を担持せしめたモノリス触媒を充填した完全酸化
反応装置を用いるのが最適である。このモノリス
触媒は、タール状物や炭素析出の多い高沸点物を
有利に完全酸化しうるからである。
かくして本発明方法を採用することにより、廃
水量が実質的にゼロの無公害化された、しかも設
備的にもユーテイリテイの面でもきわめて経済的
な工業的に有利なプロセスが可能となつたのであ
る。
以下、本発明をより具体的に添付の第１図にし
たがつて説明する。
反応原料ガス、すなわちライン１からの空気、
ライン２からのプロピレンおよびライン３からの
廃ガスの混合した原料ガスはライン４を通り、前
段反応器１０１に入り、さらにライン５を通りラ
イン６からの１段目濃縮缶１０９からの蒸気と混
合した後ライン７を経て後段反応器１０２に入
り、反応生成ガスがライン８より出る。アクリル
酸を含有する反応生成ガスはライン８よりアクリ
ル酸捕集装置１０３の下部に入り、冷却吸収によ
りアクリル酸が捕集されライン９よりアクリル酸
水溶液がえられる。捕集用の塔の上部にはライン
１０より２段目の濃縮缶１１０で蒸発せしめられ
濃縮缶１０９で凝縮せしめられた循環水が、安定
剤を含んだ吸収水として供給されアクリル酸が冷
却吸収捕集される。
アクリル酸捕集塔１０３の塔頂のライン１１よ
り出る廃ガスの一部はライン３より反応用原料ガ
スの入口ガスとして再使用され残りのガスはライ
ン１２を経て排ガス燃焼装置１１２でライン１３
からの２段目の濃縮缶１１０の濃縮廃水とともに
燃焼無害化されライン１４より大気に放出され
る。
ライン９よりくるアクリル酸水溶液は、必要に
より軽沸点物放散塔（図示せず）に供給され、塔
頂からの軽沸点物はアクリル酸捕集塔１０３にリ
サイクルされ、塔底液のアクリル酸水溶液は抽出
塔１０４に供給される。抽出塔１０４にて供給さ
れたアクリル酸は塔底のライン１５より供給され
る有機溶媒により抽出されライン１６より溶媒放
散塔１０５に供給され塔頂より溶媒を回収してラ
イン１７，１５を通つて抽出塔１０４に再使用さ
れ、塔底から出てくるアクリル酸液はライン１８
を経て酢酸分離塔１０６に入り、酢酸は塔頂のラ
イン１９より分離取出される。塔底から出る粗ア
クリル酸はライン２０より精留塔１０７に供給さ
れ塔頂より製品のアクリル酸がライン２１より、
また塔底よりライン２２を経てとり出される重質
物はこの中の有用成分であるアクリル酸や重合防
止剤を回収（図省略）し、その残液は燃料として
系外に取り出され使用される。抽出塔１０４の塔
底から排出する抽残液はライン２３より溶媒回収
塔１０８に供給され塔頂から溶媒を回収し、ライ
ン２４，１５を経て抽出塔１０４にリサイクル使
用される。そして、溶媒回収塔１０８の塔底液
は、供給液と熱交換（図省略）された後ライン２
５より１段目の濃縮缶１０９に導かれ濃縮され
る。１段目の濃縮缶１０９からえられる蒸気はラ
イン６より後段反応器１０２に供給される。２段
目の濃縮缶１１０からえられる蒸気は１段目の濃
縮缶１０９の熱源として用いられ、凝縮されたの
ちライン１０を通つてアクリル酸捕集装置１０３
の吸収水として再使用される。また、ライン２５
からの廃水にはアクリル酸の製造プロセス中の他
の廃水、例えばエゼクタースチームの凝縮水及び
冷却水などを混入してもよい。
アクリル酸捕集装置からの廃ガスのうち反応器
へ再循環される割合は、反応条件のプロピレン濃
度、酸素濃度により決定されるが、通常は廃ガス
量の15％〜85％、好ましくは20％〜80％がよい。
この割合が多過ぎると系内に蓄積するガス状不純
物の濃度が上つてプロセス的な不都合の原因にな
つたり、また系内の酸素不足による障害が起こり
やすい。また、この割合が少ないときは系内に酸
素が過剰となつてきて、燃焼範囲の関係からプロ
ピレン濃度を高められない欠点が生じる。反応廃
ガスを不活性希釈ガスとして循環して利用する方
法は従来より広く用いられている。例えば、特開
昭47−10614号細書ではプロピレンを２段反応さ
せてアクリル酸を製造するに際し、反応廃ガスを
不活性希釈ガスとして第１段の反応に循環使用し
ているが、その際に反応廃ガス中の凝縮可能なガ
スを大部分除去して、不活性希釈ガスとしての水
蒸気の一部又は全部の代りとして使用している。
しかし、この方法には、反応廃ガスを不活性希釈
ガスとして再使用するための条件について何ら詳
細に言及していない。
本発明者らは、反応廃ガスを不活性希釈ガスと
して反応に再使用する方法について種々検討した
結果、前述したごとく廃ガスを得る条件及びその
再使用のための条件（循環割合）が非常に重要で
あることを見出しそれらの条件について鋭意研究
したところ、廃ガスを取得するアクリル酸の捕集
装置の塔頂温度を25〜40℃、循環割合を15〜85
％、好ましくは20〜80％の範囲で廃ガスを再使用
するときにはじめて工業的に有利に長期間にわた
つて高収率でアクリル酸の得られることが判明し
本発明に到達した。前述の特開昭47−10614号公
報の方法において、例えば実施例13では、プロピ
レンの転化率が79％と低く、かつアクリル酸の収
率が50％と低いのは、反応条件も含めて、廃ガス
をリサイクルする全プロセスの条件が本発明方法
の条件からはずれていることによるものと推定さ
れる。
かくのごとく、本発明の特に廃ガスをえるとこ
ろの温度条件及びその再使用する循環割合が重要
な理由は未だ十分解明されていないが、酸化反応
で生成する未確認の不純物がこれらの条件をはず
れると、リサイクル系内に蓄積濃縮することによ
るかまたは、アクリル酸や副生の酢酸等が十分に
捕集されないと廃ガスとともに反応器に再供給さ
れ、酸化反応で触媒反応を阻害するものと本発明
者らは推定している。なぜなら、本発明者らの知
見によれば、アクリル酸などの酸性物質が前段触
媒層に混入した場合、プロピレンの転化率が低下
すること、さらに低下した転化率を高めようとし
て反応温度を上げると選択性が低下する傾向をは
つきりと認めているからである。そして、反応器
に供給される原料ガス中の未捕集で循環されたア
クリル酸濃度を0.5容量％以下に制限すると、触
媒反応の経時的劣化が防止できることが知見とし
てえられたのである。
そしてまた、本発明の方法は、同伴される廃ガ
スを不活性希釈ガスとして用いることにより、反
応原料ガス組成を燃焼範囲からはずし、かつ触媒
の長期活性保持のために必要な酸素量を新たに分
子状酸素含有ガス、たとえば空気により補充する
全く新規な技術思想によるアクリル酸を高収率で
安全に経済的に製造するための方法を提供するも
のである。
本発明が特定する前段での酸素濃度がプロピレ
ン濃度の1.6〜4.0モル倍、好ましくは1.7〜3.0モ
ル倍の範囲に規制するのは、本発明をプロピレン
からアクリル酸へ１回通過で転化させるために必
要な範囲であるためである。1.6に達しないモル
比ではプロピレンの転化率は前段と後段との反応
で上昇してもアクリル酸の単流収率の低下を招く
のである。また、4.0モル倍を越える場合は、必
然的に水蒸気量やプロピレン濃度との関係から爆
発や燃焼範囲に入つたり、あるいは工業的にきわ
めて生産性の低いプロセスを余儀なくされるので
好ましくない。
本発明に適する触媒は、前段触媒としては例え
ば特公昭47−42241号、特公昭47−42242号、特公
昭47−42813号、特公昭47−27490号、特公昭47−
41329号、特公昭48−4762号、特公昭48−4763号、
特公昭48−4764号、特開昭48−5710号、特公昭48
−4765号、特開昭50−13308号、特開昭50−47917
号、特開昭49−30308号、特公昭47−29881号、特
公昭47−32050号、特公昭47−32051号、特公昭47
−32052号、特公昭47−30163号、特開昭47−
17711号、特公昭47−21081号、特開昭49−92006
号等の各明細書に示される触媒のほか、前述の如
く高い反応条件を満足しうるものであればすべて
用いることができる。すなわち、前段の反応用と
して250〜450℃、好ましくは270〜370℃の反応温
度で、プロピレン３〜10容量％、好ましくは４〜
８容量％、酸素５〜18容量％、好ましくは７〜17
容量％、酸素とプロピレンの濃度モル比1.6〜
4.0、好ましくは1.7〜3.0の範囲のガスを接触時間
1.0〜7.2秒、好ましくは1.8〜3.6秒で反応させて
プロピレン転化率80モル％以上、好ましくは90モ
ル％以上、アクロレインおよびアクリル酸の合計
単流収率70モル％以上、好ましくは80モル％以上
を達成しうる触媒であり、後段の触媒としては、
例えば特公昭49−169号、特公昭49−11371号、特
開昭49−47276号、特開昭49−76810号、特開昭49
−133317号、特開昭50−25520号、特開昭50−
93918号、特公昭50−9768号、特開昭50−1987号、
特開昭50−83280号、特開昭50−97592号、特開昭
47−39018号等の各明細書に記載のものを用いる
ことができる。すなわち、後段の反応用として
180〜350℃、好ましくは200〜300℃の反応温度で
水蒸気を前段反応器入口基準で２〜30容量％、好
ましくは４〜25容量％に調節されたガスを接触時
間1.0〜7.2秒、好ましくは1.6〜3.0秒で反応させ
て、前段の反応から総合してプロピレンからアク
リル酸への単流収率70モル％以上、好ましくは75
モル％以上を達成しうる触媒であればよい。後段
の反応に供する原料ガス中には前段の反応で副生
したアクリル酸はそのまゝ供給されることがで
き、むしろ後段の反応に対し、水蒸気の存在と同
様な好ましい結果を与え、かつ後段の触媒の負荷
を実質的に小さくする効果を示す。
本発明は以上記述したとおりであるが、以下に
実施例および比較例を示して本発明をさらに具体
的に明らかにする。
実施例 １
前段触媒の調製
水15を加熱しつつモリブデン酸アンモニウム
10.62Kg、パラタングステン酸アンモニウム3.24
Kgを加えはげしく撹拌した（こえをＡ液とする）。
別に硝酸コバルト7.00Kgを２の水に、硝酸第
２鉄2.43Kgを２の水に、硝酸ビスマス2.92Kgを
濃硝酸0.6を加えて酸性とした水３に、それ
ぞれ溶解させ、この３種の硝酸塩溶液を混合した
液を上記Ａ液に滴下した。ついで二酸化ケイ素換
算で20重量％を含有するシリカゾル2.44Kgおよび
水酸化カリウム20.2ｇを1.5の水に溶解した液
をそれぞれ加え、かくして生じた懸濁液を加熱蒸
発せしめた後、成型し空気流通下450℃で６時間
焼成して触媒を調製した。この触媒の酸素以外の
元素による組成は原子比で、
Co4Fe1Bi1W2Mo10Si1.35K0.06
であつた。
後段触媒の調製
水60を加熱撹拌しつつその中にパラタングス
テン酸アンモニウム1.254Kg、メタバナジン酸ア
ンモニウム1.03Kg、モリブデン酸アンモニウム
4.06Kg、ついで重クロム酸アンモニウム0.14Kgを
それぞれ混入溶解し、別に硝酸銅1.03Kgを0.72
の水に溶解させた水溶液を作成し、両液を混合し
た。かくしてえられた混合溶液を蒸気加熱器付の
ステンレス製蒸発器に入れ、担体基材がα−アル
ミナからなり、表面積１m2／ｇ以下、気孔率42
％、75〜250ミクロンの孔径を有する細孔の占め
る容積が全細孔容積の92％を占める直径３〜５mm
の粒状担体12を加え撹拌しつつ蒸発乾固して担
体に付着せしめたのち、400℃で５時間焼成して
触媒を調製した。この触媒の担体を除く酸素以外
の元素による組成は、原子比で、
Mo12V4.6Cu2.2Cr0.6W2.4
であつた。
反応及びアクリル酸の捕集方法
上記前段触媒11.0を内径25mm、長さ3000mmの
鋼鉄製反応管10本からなり、シエル側は溶融塩を
循環することにより熱交換が可能な多管式反応器
に均等に充填し、325℃に加熱した。
別に前記後段触媒9.0を内径25mm、長さ3000
mmの鋼鉄製反応管10本からなり、シエル側は溶融
塩を循環することにより熱交換が可能な多管式反
応器に均等に充填し260℃に加熱した。
２つの反応器は、熱交換器を備えた導管で連結
し、前記触媒を含む反応器から出る反応生成ガス
と１段目の濃縮缶からの廃水の水蒸気とを後段触
媒を含む反応器へ導入されるようにした。後段触
媒を含む反応器から出る反応生成ガスは内径200
mmのステンレス製の塔で外壁に水蒸気ジヤケツト
を有する20段の泡鐘棚を備え、その下部に多管式
の冷却器を備えており、塔の最上部から重合禁止
剤を含む２段目の濃縮缶の廃水の凝縮水を1.0
Kg／Hr流下させることによつてアクリル酸をア
クリル酸水溶液として捕集し、さらに１段目の濃
縮缶の廃水の水蒸気1.2Nm3／Hrを反応用水蒸気
として再使用した。
えられたアクリル酸水溶液から軽沸点物を除去
したのち、該アクリル酸水溶液に1.5重量倍の酢
酸イソプロピルを用いてアクリル酸を抽出した。
抽出液にはアクロレイン換算で0.17重量％のアク
ロレイン、ホルムアルデヒド、アセトアルデヒド
などが含まれ、ついで溶媒分離、軽沸点分離最後
に精留の各工程を経て製品アクリル酸をえた。一
方、抽残液からは溶剤を除去したのち、えられた
廃水（2.4Kg／Hr）を１段目の多管式の濃縮缶に
供給し２段目の濃縮缶で発生した蒸気を加熱源と
して水蒸気1.2Nm3／Hr（1.0Kg／Hr）を発生させ
反応水蒸気として使用した。１段目で濃縮された
廃水1.4Kg／Hrを２段目の多管式の濃縮缶に供給
し、外部から導入した水蒸気を加熱源として使用
して廃水を濃縮し水蒸気1.0Kg／Hrを発生させ、
この蒸気は１段目の濃縮缶の加熱源として使用し
た。ここでえられた凝縮水はアクリル酸の吸収塔
の吸収水として使用した。１段目の濃縮缶で廃水
は1.7倍、２段目で4.7倍に濃縮された。２段目の
加熱源の水蒸気の圧力は６Kg／cm2Ｇが用いられ、
２段目および１段目の操作圧はそれぞれ３Kg／cm2
Ｇと１Kg／cm2Ｇに設定された。濃縮缶に供給され
た廃水、１段目でえられた水蒸気、２段目でえら
れた凝縮水および濃縮水の分析値は第１表の通り
であつた。
The present invention relates to a process for producing acrylic acid by catalytic gas phase oxidation of propylene, and to an effective use of wastewater and a method for detoxifying the wastewater. Specifically, the present invention provides a process for producing acrylic acid by catalytic gas phase oxidation of propylene to mainly acrolein as a first reaction and acrolein to acrylic acid as a second reaction using water vapor and a molecular oxygen-containing gas. After collecting the acrylic acid produced in the oxidation reaction as an aqueous solution, a part of the waste gas is recycled and used for the first stage oxidation reaction, while the collected acrylic acid aqueous solution is led to the acrylic acid separation process and the resulting The waste water obtained in the second stage is concentrated using a double-effect can, the waste water vapor obtained in the first stage is recycled for the subsequent oxidation reaction, and the waste water vapor obtained in the second stage is concentrated.
It is used as a heat source for the stage concentrator, the resulting condensed water is recycled to collect the produced acrylic acid, and the concentrated wastewater obtained in the second stage concentrator is completely oxidized together with the remainder of the waste gas. The present invention relates to a closed system production method for acrylic acid characterized by the following. The present inventors have already disclosed a method for producing acrylic acid by catalytic gas phase oxidation of propylene in Japanese Patent Application No. 51-25602 (see Japanese Patent Application Laid-open No. 52-108917). A process in which the resulting reaction product gas is separated into an acrylic acid aqueous solution and waste gas by an acrylic acid collection device, and a portion of the waste gas is recycled for use in the previous reaction. provided. The feature is that acrylic acid is collected to prevent the concentration of acrylic acid in the raw material gas for the reaction, which includes a part of the waste gas, from exceeding 0.5% by volume when the waste gas is reused in the first-stage reaction. Maintain the exhaust temperature of the waste gas from the equipment in the range of 35 to 80℃, and
~85% of the reactor should be recycled to the first stage reactor. This method also achieves the goal of obtaining acrylic acid from propylene in high yield over a long period of time as a highly concentrated aqueous solution, resulting in reduced utility in the reaction and purification process, reduced amount of waste water, They proposed an extremely industrially advantageous process that achieved increased yields of acrylic acid. Therefore, the present inventors investigated the method of the invention in order to make it more industrially complete. That is, we have concentrated on researching methods for reusing the waste water discharged from the process while recycling waste gas, and have completed the method of the present invention, which is a closed process. In the process of producing acrylic acid by catalytic gas phase oxidation of propylene, a large amount of waste water is discharged. That is, a considerable amount of water vapor is used mixed with the raw material gas in the oxidation reaction, and is sent to a reaction product collection device together with by-product water produced by the reaction. In the collection device, the water vapor is condensed and collected together with the main product, acrylic acid.
In this case, it is common to bring the water into direct contact with absorbed water to cool and condense it.
A 70% by weight aqueous acrylic acid solution is recovered. A large amount of waste water is discharged from this aqueous solution when acrylic acid is separated in the next extraction or azeotropic distillation step. In addition to unrecovered acrylic acid and by-product acetic acid and propionic acid, this wastewater contains trace amounts of organic acids such as maleic acid, as well as aldehydes such as acrolein, formaldehyde, and acetaldehyde, and substances derived from these compounds. various derivatives,
Furthermore, organic solvents for extraction and azeotropic distillation, polymerization inhibitors, and the like are contained in a total amount of about 0.5 to 5% by weight.
Since wastewater containing such a large amount of organic matter cannot be directly discharged into rivers, it must be detoxified by activated sludge method or concentrated combustion method. However, the above-mentioned activated sludge method requires not a small amount of equipment and expenses, and it is difficult to achieve complete pollution-free treatment.On the other hand, the concentrated combustion method also requires equipment costs to treat all of this wastewater as it is. This inevitably leads to an expensive process. Therefore, how to efficiently purify process wastewater, which tends to be a source of pollution, can be said to be one of the most pressing industrial issues. On the other hand, as mentioned above, the process of manufacturing acrylic acid uses a large amount of water as steam and cooling absorption water, and there is a strong desire in process development to return this wastewater to the manufacturing process. This is what is happening. The present inventor investigated various methods of returning the wastewater to the process and reusing it. First, if wastewater is directly reused as absorption water for collecting acrylic acid, organic acids and various other impurities will concentrate and accumulate in the system of absorption water - acrylic acid aqueous solution - wastewater, and eventually It has been found that after reaching a certain equilibrium concentration, it is extracted together with acrylic acid and mixed into the final product, acrylic acid, resulting in a decrease in quality. To make matters worse, in the waste gas recycling process where part of the waste gas from the acrylic acid collection tower is used as part of the raw material gas for the oxidation reaction,
If wastewater with a high acid concentration is reused as absorption water for acrylic acid collection, not only will the acrylic acid collection rate decrease, but the activity of the catalyst in the oxidation reaction will gradually decrease and be inhibited, resulting in It was found that this resulted in a decrease in yield. This is because an increase in the acid content of the wastewater as absorbed water also reduces the efficiency of collecting acrylic acid in the acrylic acid collection device, and that amount is entrained in the recycled waste gas. Therefore, it has become clear that it is inconvenient to reuse wastewater in an untreated state. In order to solve such problems, the present inventors concentrated wastewater using a dual-effect can, reused the condensed water obtained by evaporation from the wastewater, and considered detoxifying the concentrated wastewater. As a result, the steam from the wastewater obtained from the first-stage concentrator is circulated as it is to the second-stage reactor for the second-stage oxidation reaction, and the steam from the wastewater obtained from the second-stage concentrator is recycled to the first-stage concentrator. It is advantageous to use it as a heat source and use the resulting condensate as absorption water, and to completely oxidize the concentrated wastewater obtained in the second-stage concentrator together with the remainder of the waste gas after collecting acrylic acid. This discovery led to the completion of the present invention. In other words, the wastewater condensate obtained from the second stage concentrator can be used as absorption water for collecting acrylic acid.
It was found that the above-mentioned disadvantages did not occur, there was no accumulation of light-boiling substances such as acrolein, formaldehyde, and acetaldehyde, and the collection of acrylic acid could be maintained at a high level. It was discovered that the waste water vapor obtained from the concentrator, which contains light boiling substances such as acrolein, formaldehyde, and acetaldehyde, and a small amount of acrylic acid, could be recycled to the subsequent reactor without causing any inconvenience. In the present invention, since the water vapor necessary for the reaction is substantially supplied by the vapor of waste water from the first-stage concentrator, the temperature at the top of the absorption tower to which absorbed water is supplied by the acrylic acid collector is It can be set arbitrarily, and by setting it as low as possible, it can be operated so that acrylic acid and water vapor are substantially condensed and absorbed, and the acid content entrained in the waste gas and discharged becomes almost zero. Since cooling is performed industrially using cold water tower water, which is generally available at low cost, the tower top temperature is set to 40°C or less, preferably 25 to 40°C. By setting the top temperature of the absorption tower as low as possible, acrylic acid can be easily collected in the absorption tower, and the height of the absorption tower can be reduced. Furthermore, by using condensed water resulting from concentration of wastewater as absorption water for collecting acrylic acid, it is possible to recover acrylic acid, which has conventionally been discarded as is from wastewater. Furthermore, since the temperature of the recycled waste gas is low, the air volume of the recycled gas is small, and the recycling blower can be made smaller. The waste water vapor used as reaction steam is
It is conveniently recycled to the subsequent reactor. This is because, in the reaction of propylene being oxidized to acrylic acid through the front and rear reactors, it is mainly the rear catalyst that requires water vapor for the reaction, while the front catalyst requires water vapor because the acrylic acid content in the raw material gas is oxidized.
This is because there is a restriction that it must be adjusted to 0.5% by volume or less, particularly 0.3% by volume or less. By circulating the propylene into the subsequent reactor as reaction steam, the concentration of propylene in the raw material gas can be increased.In other words, the volume of the raw material gas in the first reactor can be reduced by the amount of water vapor input, and as a result, This is because the reactor can be made smaller. The waste water condensate used as absorption water can advantageously be from the steam of the second stage concentrator. This is because the water vapor in the first stage concentrator contains light boiling point substances such as acrolein, formaldehyde, and acetaldehyde, so if it is recycled and reused as absorption water, it will concentrate and accumulate in the system of absorption water - acrylic acid aqueous solution - wastewater. This is because they may be extracted together with acrylic acid, leading to problems with polymerizability during the acrylic acid purification process, and contamination with the final product of acrylic acid, resulting in a decrease in quality. Therefore, as the absorbed water, the condensed water of the waste water from the second stage concentrator from which the light boiling point substances contained in the waste water have been removed is used. On the other hand, the steam in the first stage concentrator containing light boiling substances such as acrolein, formaldehyde, and acetaldehyde is recycled to the subsequent stage reactor as reaction steam. Since the light boiling point substances are oxidized and burned in the reactor, they do not concentrate and accumulate in the system. The concentrated waste liquid obtained from the second-stage concentrator contains various solids and tar-like substances, and if necessary, after passing through a filter, some of the waste gas from the collection device is collected. The gas is completely oxidized together with the remaining gas after removing the circulating gas, and is treated to make it non-polluting. The complete oxidation treatment equipment can adopt a catalytic combustion method or a direct combustion method in which it is mixed with fuel and combusted, but the catalytic combustion method can be advantageously adopted. Optimally, a full oxidation reactor packed with a supported monolithic catalyst is used. This is because this monolithic catalyst can advantageously completely oxidize tar-like substances and high-boiling substances that deposit a lot of carbon. Thus, by adopting the method of the present invention, it has become possible to achieve an industrially advantageous process that is pollution-free, with virtually no wastewater volume, and is extremely economical in terms of equipment and utility. . Hereinafter, the present invention will be explained in more detail with reference to the attached FIG. 1. Reaction raw material gas, i.e. air from line 1,
The raw material gas, which is a mixture of propylene from line 2 and waste gas from line 3, passes through line 4, enters the pre-stage reactor 101, and further passes through line 5, where it mixes with steam from the first stage concentrator 109 from line 6. After that, it enters the second stage reactor 102 via line 7, and the reaction product gas exits from line 8. The reaction product gas containing acrylic acid enters the lower part of the acrylic acid collection device 103 through line 8, acrylic acid is collected by cooling and absorption, and an aqueous acrylic acid solution is obtained through line 9. Circulating water that has been evaporated in the second concentrator 110 and condensed in the concentrator 109 is supplied from the line 10 to the upper part of the collection tower as absorption water containing a stabilizer, and the acrylic acid is cooled and absorbed. be captured. A part of the waste gas coming out from the line 11 at the top of the acrylic acid collection tower 103 is reused as the inlet gas for the reaction raw material gas from the line 3, and the remaining gas passes through the line 12 to the exhaust gas combustion device 112 and is sent to the line 13.
Together with the concentrated wastewater from the second-stage concentrator 110, the waste water is burnt and rendered harmless and discharged into the atmosphere through the line 14. The aqueous acrylic acid solution coming from line 9 is supplied to a light boiling point stripping tower (not shown) as necessary, and the light boiling point matter from the top of the tower is recycled to the acrylic acid collection tower 103. is supplied to the extraction column 104. The acrylic acid supplied to the extraction tower 104 is extracted with an organic solvent supplied from line 15 at the bottom of the tower, and is supplied from line 16 to a solvent stripping tower 105, where the solvent is recovered from the top of the tower and passed through lines 17 and 15. The acrylic acid liquid that is reused in the extraction column 104 and comes out from the bottom of the column is sent to the line 18.
The acetic acid is passed through the acetic acid separation column 106, and the acetic acid is separated and taken out through a line 19 at the top of the column. The crude acrylic acid discharged from the bottom of the column is supplied to the rectification column 107 through line 20, and the product acrylic acid is supplied from the top of the column through line 21.
In addition, from the heavy material taken out from the bottom of the column via line 22, useful components such as acrylic acid and polymerization inhibitor are recovered (not shown), and the residual liquid is taken out of the system and used as fuel. The raffinate discharged from the bottom of the extraction column 104 is supplied to the solvent recovery column 108 via line 23, the solvent is recovered from the top of the column, and recycled to the extraction column 104 via lines 24 and 15. Then, the bottom liquid of the solvent recovery column 108 is heated through a line 2 after being heat exchanged with the feed liquid (not shown).
5 to the first stage concentration can 109 and concentrated. Steam obtained from the first stage concentrator 109 is supplied to the second stage reactor 102 through line 6. The steam obtained from the second-stage concentrator 110 is used as a heat source for the first-stage concentrator 109, and after being condensed, it passes through the line 10 to the acrylic acid collector 103.
The absorbed water is reused as water. Also, line 25
The wastewater may be mixed with other wastewater from the acrylic acid production process, such as ejector steam condensate and cooling water. The proportion of the waste gas from the acrylic acid collector that is recycled to the reactor is determined by the propylene concentration and oxygen concentration of the reaction conditions, but is usually 15% to 85% of the waste gas amount, preferably 20%. %~80% is good.
If this ratio is too high, the concentration of gaseous impurities accumulated in the system will increase, causing process problems, and failures due to lack of oxygen in the system will likely occur. Furthermore, when this ratio is small, there will be an excess of oxygen in the system, resulting in the disadvantage that the propylene concentration cannot be increased due to the combustion range. A method of recycling and utilizing reaction waste gas as an inert diluent gas has been widely used. For example, in JP-A No. 47-10614, when producing acrylic acid through a two-stage reaction of propylene, the reaction waste gas is recycled as an inert diluent gas for the first stage reaction. Most of the condensable gases in the reaction waste gas are removed and used as part or all of the steam as an inert diluent gas.
However, this method does not mention in any detail the conditions for reusing the reaction waste gas as an inert diluent gas. As a result of various studies on methods for reusing reaction waste gas in the reaction as an inert diluent gas, the present inventors found that the conditions for obtaining waste gas and the conditions for its reuse (circulation ratio) are extremely poor, as described above. After discovering that these conditions are important and conducting intensive research on these conditions, we found that the top temperature of the acrylic acid collection device that collects the waste gas should be 25 to 40℃, and the circulation rate should be 15 to 85℃.
%, preferably in the range of 20 to 80%, it has been found that acrylic acid can be industrially advantageously obtained in high yield over a long period of time, and the present invention has been achieved. In the method of JP-A-47-10614 mentioned above, for example, in Example 13, the conversion rate of propylene is as low as 79% and the yield of acrylic acid as low as 50%, including the reaction conditions. It is presumed that this is because the conditions of the entire process of recycling waste gas deviate from the conditions of the method of the present invention. Thus, the reasons why the temperature conditions at which the waste gas is collected and the recycling rate for its reuse are important in the present invention have not yet been fully elucidated, but unidentified impurities generated in the oxidation reaction may deviate from these conditions. This may be due to accumulation and concentration in the recycling system, or if acrylic acid and by-product acetic acid are not sufficiently collected, they may be re-supplied to the reactor along with the waste gas, inhibiting the catalytic reaction in the oxidation reaction. The inventors estimate that This is because, according to the findings of the present inventors, when an acidic substance such as acrylic acid is mixed into the front catalyst layer, the conversion rate of propylene decreases, and if the reaction temperature is increased in an attempt to further increase the decreased conversion rate. This is because it is clearly recognized that selectivity tends to decrease. It was discovered that by limiting the concentration of uncollected, recycled acrylic acid in the raw material gas supplied to the reactor to 0.5% by volume or less, deterioration of the catalytic reaction over time could be prevented. In addition, the method of the present invention uses the entrained waste gas as an inert diluent gas to remove the reaction raw gas composition from the combustible range and to newly increase the amount of oxygen necessary for maintaining the catalyst's long-term activity. The object of the present invention is to provide a method for safely and economically producing acrylic acid in high yield based on a completely new technical concept in which gas containing molecular oxygen, such as air, is used for replenishment. The reason why the oxygen concentration in the first stage specified by the present invention is regulated to a range of 1.6 to 4.0 times the propylene concentration, preferably 1.7 to 3.0 times the mole, is because the present invention converts propylene to acrylic acid in one pass. This is because it is within the necessary range. If the molar ratio does not reach 1.6, even if the conversion rate of propylene is increased by the reaction between the first and second stages, the single flow yield of acrylic acid will decrease. Moreover, if it exceeds 4.0 moles, it is undesirable because it will inevitably fall into the explosion or combustible range due to the relationship with the water vapor amount and propylene concentration, or an industrially extremely low productivity process will be forced. Catalysts suitable for the present invention include, for example, Japanese Patent Publication No. 47-42241, Japanese Patent Publication No. 42242, Japanese Patent Publication No. 42813, Japanese Patent Publication No. 27490, Japanese Patent Publication No. 47-27490, and Japanese Patent Publication No. 47-27490.
41329, Special Publication No. 48-4762, Special Publication No. 48-4763,
Special Publication No. 48-4764, Special Publication No. 5710 (1977), Special Publication No. 1973
-4765, JP-A-50-13308, JP-A-50-47917
No., JP-A-49-30308, JP-A-47-29881, JP-A-47-32050, JP-A-47-32051, JP-A-47
−32052, Tokuko No. 1972-30163, Tokukai No. 1973 –
No. 17711, Special Publication No. 1977-21081, Japanese Patent Publication No. 49-92006
In addition to the catalysts shown in each specification such as No. 1, any catalyst can be used as long as it can satisfy the high reaction conditions as described above. That is, for the first stage reaction, at a reaction temperature of 250 to 450°C, preferably 270 to 370°C, 3 to 10% by volume of propylene, preferably 4 to
8% by volume, oxygen 5-18% by volume, preferably 7-17
Volume %, concentration molar ratio of oxygen and propylene 1.6 ~
4.0, preferably gas contact time in the range 1.7 to 3.0
React for 1.0 to 7.2 seconds, preferably 1.8 to 3.6 seconds to achieve a propylene conversion of 80 mol% or more, preferably 90 mol% or more, and a total single-stream yield of acrolein and acrylic acid of 70 mol% or more, preferably 80 mol%. This is a catalyst that can achieve the above, and as a subsequent catalyst,
For example, JP-A-49-169, JP-A-49-11371, JP-A-49-47276, JP-A-49-76810, JP-A-49
−133317, Japanese Patent Application Publication No. 1973-25520, Japanese Patent Application Publication No. 1973-
93918, JP 50-9768, JP 50-1987,
JP-A-50-83280, JP-A-50-97592, JP-A-Sho
Those described in each specification such as No. 47-39018 can be used. In other words, for the subsequent reaction
At a reaction temperature of 180 to 350°C, preferably 200 to 300°C, water vapor is adjusted to 2 to 30% by volume, preferably 4 to 25% by volume, based on the inlet of the first stage reactor, and a contact time of 1.0 to 7.2 seconds, preferably. is reacted in 1.6 to 3.0 seconds, and the single flow yield from propylene to acrylic acid from the previous reaction is 70 mol% or more, preferably 75 mol% or more.
Any catalyst may be used as long as it can achieve mol% or more. The acrylic acid by-produced in the first-stage reaction can be supplied as is into the raw material gas to be used in the second-stage reaction. Rather, it gives the same favorable result to the second-stage reaction as the presence of water vapor, and shows the effect of substantially reducing the catalyst load. Although the present invention has been described above, the present invention will be clarified more specifically by showing Examples and Comparative Examples below. Example 1 Preparation of first-stage catalyst Ammonium molybdate while heating water 15
10.62Kg, ammonium paratungstate 3.24
Kg was added and stirred vigorously (the remaining liquid is referred to as liquid A). Separately, 7.00 kg of cobalt nitrate was dissolved in water 2, 2.43 kg of ferric nitrate was dissolved in water 2, and 2.92 kg of bismuth nitrate was dissolved in water 3 made acidic by adding 0.6 g of concentrated nitric acid. The mixed solution was dropped into the above A solution. Next, 2.44 kg of silica sol containing 20% by weight in terms of silicon dioxide and 20.2 g of potassium hydroxide dissolved in 1.5 parts water were added, and the resulting suspension was heated and evaporated, then molded and molded under air circulation. A catalyst was prepared by calcining at 450°C for 6 hours. The composition of this catalyst with elements other than oxygen was Co 4 Fe 1 Bi 1 W 2 Mo 10 Si 1.35 K 0.06 in atomic ratio. Preparation of second-stage catalyst While heating and stirring 60 g of water, add 1.254 kg of ammonium paratungstate, 1.03 kg of ammonium metavanadate, and ammonium molybdate.
4.06Kg, then 0.14Kg of ammonium dichromate were mixed and dissolved, and separately 1.03Kg of copper nitrate was added to 0.72Kg.
An aqueous solution was prepared by dissolving it in water, and both solutions were mixed. The thus obtained mixed solution was placed in a stainless steel evaporator equipped with a steam heater, and the carrier base material was made of α-alumina, had a surface area of 1 m 2 /g or less, and a porosity of 42.
%, the volume occupied by pores with a pore diameter of 75 to 250 microns accounts for 92% of the total pore volume, with a diameter of 3 to 5 mm.
A granular carrier 12 was added thereto, and the mixture was evaporated to dryness while stirring to adhere to the carrier, and then calcined at 400°C for 5 hours to prepare a catalyst. The composition of this catalyst with elements other than oxygen excluding the carrier was Mo 12 V 4.6 Cu 2.2 Cr 0.6 W 2.4 in atomic ratio. Reaction and acrylic acid collection method The above-mentioned first stage catalyst 11.0 was put into a multi-tubular reactor consisting of 10 steel reaction tubes with an inner diameter of 25 mm and a length of 3000 mm, and the shell side was capable of heat exchange by circulating molten salt. Filled evenly and heated to 325°C. Separately, the latter stage catalyst 9.0 has an inner diameter of 25 mm and a length of 3000 mm.
A multi-tubular reactor consisting of 10 steel reaction tubes with a diameter of 1.5 mm and a shell side capable of heat exchange by circulating molten salt was evenly packed and heated to 260°C. The two reactors are connected by a conduit equipped with a heat exchanger, and the reaction product gas discharged from the reactor containing the catalyst and the waste water vapor from the first stage concentrator are introduced into the reactor containing the second stage catalyst. I made it so that it would be done. The reaction product gas coming out of the reactor containing the post-catalyst has an inner diameter of 200 mm.
The tower is made of stainless steel and is equipped with a 20-stage bubble rack with a steam jacket on the outer wall, a multi-tubular cooler at the bottom, and a second stage containing a polymerization inhibitor from the top of the tower. Condensate of waste water in concentrator can 1.0
Acrylic acid was collected as an aqueous acrylic acid solution by flowing down Kg/Hr, and 1.2 Nm 3 /Hr of waste water vapor from the first-stage concentrator was reused as reaction steam. After removing light boilers from the obtained acrylic acid aqueous solution, acrylic acid was extracted from the acrylic acid aqueous solution using 1.5 times the weight of isopropyl acetate.
The extract contained 0.17% by weight of acrolein, formaldehyde, acetaldehyde, etc. in terms of acrolein, and was then subjected to solvent separation, light boiling point separation, and finally rectification to obtain the product acrylic acid. On the other hand, after removing the solvent from the raffinate, the resulting wastewater (2.4Kg/Hr) is supplied to the first-stage multi-tube concentrator, and the steam generated in the second-stage concentrator is used as a heating source. 1.2Nm 3 /Hr (1.0Kg/Hr) of steam was generated and used as reaction steam. The 1.4Kg/Hr of wastewater concentrated in the first stage is supplied to the multi-tube concentrator in the second stage, and the water vapor introduced from the outside is used as a heating source to concentrate the wastewater and generate 1.0Kg/Hr of water vapor. let me,
This steam was used as a heating source for the first stage concentrator. The condensed water obtained here was used as absorption water in an acrylic acid absorption tower. The wastewater was concentrated 1.7 times in the first stage concentrator, and 4.7 times in the second stage. The pressure of the steam in the second stage heating source is 6Kg/cm 2 G.
The operating pressure of the 2nd stage and the 1st stage is 3Kg/cm 2 respectively.
G and 1Kg/cm 2 G. The analytical values of the wastewater supplied to the concentrator, the steam obtained in the first stage, the condensed water obtained in the second stage, and the concentrated water were as shown in Table 1.
【表】
た濃縮水
アクリル酸捕集装置から排出されるガスは、一
部分をパージする以外は送風機により前段触媒を
含む反応器入口に戻され、これに、プロピレンと
空気を加え、混合して前段反応器に導入するよう
にした。前段反応器へプロピレン6.0容量％、酸
素13.5容量％、その他少量の反応生成物と窒素か
らなる混合ガスを15.0m3／ｈ（NTP換算）で導入
した。その時、アクリル酸捕集装置の塔頂温度は
35℃、廃ガスの循環率は42.5％であつた。そし
て、前段反応器からの反応生成ガスに１段目の濃
縮缶からの水蒸気を加え、前段反応入口基準で水
蒸気10容量％となつた混合ガスを後段反応器へ導
入した。
かくしてプロピレンの転化率95.7モル％、アク
リル酸の収率は84.2モル％で安定して運転が行な
えた。なお、アクリル酸捕集装置の塔頂からの流
下水は1.0Kg／hr、アクリル酸捕集率は98〜99％
であつた。またこのとき原料ガス中の酸濃度はア
クリル酸として0.06容量％であつた。そしてこの
アクリル酸水溶液からの後工程での分離精製して
えられた製品のアクリル酸の純度、重合性能はき
わめて満足すべきものであり、この装置は３ケ月
間の連続運転後も装置になんらのトラブルも認め
なかつた。
実施例 ２
実施例１において用いたのと同じ装置およびプ
ロセスを用いて以下の如く実施した。すなわち、
反応条件として前後反応器へ導入される原料ガス
組成を、プロピレン7.3容量％、酸素16.7容量％、
残りは窒素、炭酸ガスなどの不活性および廃ガス
とともに混入された微量の水蒸気などとなるよう
にして反応せしめ、そして後段反応器へ導入され
るガス組成を前段反応器入口基準で水蒸気15容量
％に調節して後段反応器にて反応せしめ、アクリ
ル酸捕集装置での塔頂温度を40℃、廃ガスの循環
率を24.9％と設定した。プロピレン転化率95.4モ
ル％、アクリル酸の収率は84.0モル％で安定した
運転を行なつた。アクリル酸捕集装置へは２段目
の濃縮缶からの廃水水蒸気を１段目の濃縮缶で濃
縮させてえた吸収水を1.7Kg／Hr流下させ、また
１段目の濃縮缶からえられた水蒸気を2.6Nm3／
Hr（1.7Kg／Hr）、酸化反応用として前段反応器へ
供給した。アクリル酸の捕集率は96〜97％、原料
ガス中の酸分はアクリル酸として0.05％であつ
た。また１段目の濃縮缶では廃水は1.8倍に、２
段目の濃縮缶では8.8倍にそれぞれ濃縮された。
濃縮缶へ供給された廃水（3.8Kg／Hr）、１段目
でえられた水蒸気、２段目でえられた水蒸気の凝
縮水および２段目で濃縮された缶液の分析値は第
２表に示すとおりであつた。[Table] Concentrated water The gas discharged from the acrylic acid collector is returned to the inlet of the reactor containing the front stage catalyst by a blower, except for a portion of it being purged. was introduced into the reactor. A mixed gas consisting of 6.0% by volume of propylene, 13.5% by volume of oxygen, other small amounts of reaction products, and nitrogen was introduced into the first reactor at a rate of 15.0 m 3 /h (in terms of NTP). At that time, the top temperature of the acrylic acid collector is
At 35°C, the waste gas circulation rate was 42.5%. Then, water vapor from the first-stage concentrator was added to the reaction product gas from the first-stage reactor, and the mixed gas containing 10% by volume of steam based on the first-stage reaction inlet was introduced into the second-stage reactor. Thus, stable operation was possible with a propylene conversion rate of 95.7 mol% and an acrylic acid yield of 84.2 mol%. The effluent from the top of the acrylic acid collection device is 1.0Kg/hr, and the acrylic acid collection rate is 98-99%.
It was hot. Further, at this time, the acid concentration in the raw material gas was 0.06% by volume as acrylic acid. The purity and polymerization performance of the acrylic acid obtained by separating and purifying this acrylic acid aqueous solution in the post-process are extremely satisfactory, and this equipment shows no problems even after three months of continuous operation. He didn't even acknowledge any trouble. Example 2 The same equipment and process used in Example 1 was used as follows. That is,
As reaction conditions, the raw material gas composition introduced into the front and rear reactors was 7.3% by volume of propylene, 16.7% by volume of oxygen,
The remainder is inert gas such as nitrogen and carbon dioxide, and a trace amount of water vapor mixed in with waste gas is reacted, and the gas composition introduced into the second reactor is adjusted to 15% by volume of water vapor based on the inlet of the first reactor. The temperature at the top of the acrylic acid collector was set at 40°C, and the waste gas circulation rate was set at 24.9%. Stable operation was performed with a propylene conversion rate of 95.4 mol% and an acrylic acid yield of 84.0 mol%. To the acrylic acid collection device, 1.7Kg/Hr of absorbed water obtained by concentrating the waste water vapor from the second-stage concentrator in the first-stage concentrator flows down, and also the absorbed water obtained from the first-stage concentrator Water vapor 2.6Nm 3 /
Hr (1.7Kg/Hr) was supplied to the first stage reactor for the oxidation reaction. The collection rate of acrylic acid was 96 to 97%, and the acid content in the raw material gas was 0.05% as acrylic acid. In addition, in the first stage concentrator, the wastewater is increased by 1.8 times, and by 2 times.
The concentration cans in the third stage were each concentrated 8.8 times.
The analysis values of the wastewater (3.8Kg/Hr) supplied to the concentrator, the steam obtained in the first stage, the condensed water of the steam obtained in the second stage, and the can liquid concentrated in the second stage are as follows. It was as shown in the table.
第１図は本発明を実施するための１つのフロー
シートを示したものである。
FIG. 1 shows one flow sheet for implementing the invention.
Claims (1)
前段反応としてプロピレンから主としてアクロレ
イン、後段反応としてアクロレインからアクリル
酸へそれぞれ接触気相酸化してアクリル酸を製造
するプロセスにおいて、該酸化反応で生成したア
クリル酸を水溶液として捕集したあとの廃ガスの
一部を該前段酸化反応用に循環使用し、一方捕集
されたアクリル酸水溶液をアクリル酸分離工程に
導びき、そこで排出される廃水を２重効用缶を用
いて濃縮し、１段目の濃縮缶でえられる廃水の蒸
気を該後段酸化反応用に循環使用し、その濃縮液
は２段目の濃縮缶に供給し、２段目の濃縮缶でえ
られる廃水の蒸気を１段目の濃縮缶の熱源として
使用し、えられた凝縮水を生成したアクリル酸の
捕集用に循環使用しさらに２段目の濃縮缶でえら
れる濃縮廃水を上記廃ガスの残部とともに完全酸
化処理せしめることを特徴とするアクリル酸の製
造方法。1 Using water vapor and molecular oxygen-containing gas,
In the process of producing acrylic acid by catalytic gas phase oxidation of propylene to mainly acrolein as the first reaction and acrolein to acrylic acid as the second reaction, the waste gas after collecting the acrylic acid produced in the oxidation reaction as an aqueous solution. A part of it is recycled for the first stage oxidation reaction, while the collected acrylic acid aqueous solution is led to the acrylic acid separation process, and the wastewater discharged there is concentrated using a double-effect tank and The wastewater vapor obtained from the concentrator is recycled for the latter stage oxidation reaction, the concentrated liquid is supplied to the second-stage concentrator, and the wastewater vapor obtained from the second-stage concentrator is used for the first-stage oxidation reaction. Use it as a heat source for the concentrator, recirculate the resulting condensed water to collect the produced acrylic acid, and then completely oxidize the concentrated wastewater obtained in the second-stage concentrator together with the rest of the waste gas. A method for producing acrylic acid, characterized by:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15070682A JPS5942340A (en) | 1982-09-01 | 1982-09-01 | Preparation of acrylic acid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15070682A JPS5942340A (en) | 1982-09-01 | 1982-09-01 | Preparation of acrylic acid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5942340A JPS5942340A (en) | 1984-03-08 |
| JPS6325569B2 true JPS6325569B2 (en) | 1988-05-26 |
Family
ID=15502628
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15070682A Granted JPS5942340A (en) | 1982-09-01 | 1982-09-01 | Preparation of acrylic acid |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5942340A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19624674A1 (en) * | 1996-06-20 | 1998-01-02 | Basf Ag | Process for the disposal of secondary components resulting from the production of acrylic acid or methacrylic acid |
| JP2003238485A (en) * | 2001-12-10 | 2003-08-27 | Nippon Shokubai Co Ltd | Method and equipment for collecting (meth)acrylic acid |
| MX2020012737A (en) * | 2018-05-28 | 2021-05-14 | Pierson Capital Environmental Beijing Ltd | Efficient methods and compositions for recovery of products from organic acid pretreatment of plant materials. |
| FR3089222A1 (en) * | 2018-11-29 | 2020-06-05 | Arkema France | PURIFICATION OF AQUEOUS SOLUTIONS CONTAINING FORMALDEHYDE, AND USE OF THE PURIFIED SOLUTION IN A PROCESS FOR THE PRODUCTION OF ACRYLIC ACID |
| KR20220078275A (en) * | 2020-12-03 | 2022-06-10 | 주식회사 엘지화학 | Process for manufacturing acrylic acid |
-
1982
- 1982-09-01 JP JP15070682A patent/JPS5942340A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5942340A (en) | 1984-03-08 |
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