Process for producing (meth)acrylic acids and process for distilling the same

• US 20070021633A1
• Filed: 09/26/2006
• Published: 01/25/2007
• Est. Priority Date: 10/09/2001
• Status: Active Grant

• Current Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Original Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Inventors: Ogawa, Yasushi, Suzuki, Yoshiro, Yada, Shuhei, Jinno, Kimikatsu, Hosaka, Hirochika, Takasaki, Kenji, Goriki, Masayasu
• Granted Patent: US 7,368,601 B2
• Time in Patent Office: Days
• US Class Current: 562/600
• CPC Class Codes: B01D 3/14 Fractional distillation or use of a fractionation or rectification column
• CPC Class Codes: B01D 3/146 Multiple effect distillation
• CPC Class Codes: B01D 3/42 Regulation; Control
• CPC Class Codes: B01D 3/4211 of columns
• CPC Class Codes: C07C 51/44 by distillation
• CPC Class Codes: C07C 57/04 Acrylic acid; Methacrylic acid
• CPC Class Codes: C07C 67/54 by distillation
• CPC Class Codes: C07C 69/54 Acrylic acid esters; Methacrylic acid esters

Abstract

In the stopping and starting operations of a distillation column used for producing (meth)acrylic acids according to the present invention, upon stopping the operation of the distillation column, the heating of a reboiler attached thereto is interrupted and then the reboiler is rapidly cooled; and/or upon starting the operation of the distillation column for production of the (meth)acrylic acids, an inner wall surface of the distillation column is heated to a temperature higher than a condensation temperature of the (meth)acrylic acids and the operation of the distillation column is started under the heated condition. According to the present invention, it is possible to early and safely stop the operation of the distillation column while preventing the occurrence of polymerization within the distillation column, and stably perform an operation for distillation of acrylic monomers for a long period of time.

Claims

1-12. -12. (canceled)

13. A process for producing purified (meth)acrylic acids by distilling acrylic acid or methacrylic acid (both hereinafter referred to merely as “

(meth)acrylic acid”

) or esters of these acids (hereinafter referred to as “

(meth)acrylic acids”

) using a distillation column, comprising;

in stopping and starting operations of the distillation column,

successively washing the distillation column with the following washing agents;

(1) water;

(2) an aqueous alkali solution; and

(3) an organic solvent.

15. A process according to claim 13, wherein an azeotropic agent used upon condensation of an aqueous solution containing (meth)acrylic acid is used as the organic solvent.

16. A process according to claim 13, wherein crude (meth)acrylic acids obtained before stopping the operation of the distillation column are used as the organic solvent.

17. A process according to claim 13, wherein the purified (meth)acrylic acids obtained before stopping the operation of the distillation column are used as the organic solvent.

18. A process according to claim 13, wherein a bottom liquid of the distillation column, which is obtained before stopping the operation of the distillation column is used as the organic solvent.

19. process according to claim 13, wherein said organic solvent contains water in an amount of not more than 2% by weight.

20. A process according to claim 13, wherein said aqueous alkali solution is an aqueous alkali hydroxide solution having a concentration of 1 to 25% by weight.

21. A process according to claim 13, wherein said aqueous alkali solution is aqueous ammonia having a concentration of 1 to 25% by weight.

14. A process for producing purified (meth)acrylic acids by distilling (meth)acrylic acids using a distillation column, comprising:

in stopping and starting operations of the distillation column, successively washing the distillation column with the following washing agents;

(1) water;

(2) an aqueous alkali solution;

(2a) water; and

(3) an organic solvent.

22. A method for distilling acrylic acid, methacrylic acid and esters of these acids using a distillation column, comprising:

previously wetting an inner wall surface of the distillation column with a polymerization inhibitor-containing liquid; and

then starting an operation of the distillation column.

23. A method according to claim 22, wherein said polymerization inhibitor-containing liquid is an aqueous solution of the polymerization inhibitor.

24. A method according to claim 22, wherein said polymerization inhibitor-containing liquid is a solution of an azeotropic agent.

25. A method according to claim 22, wherein said polymerization inhibitor-containing liquid is a solution of the acrylic acid, methacrylic acid or esters of these acids.

26. A method according to claim 22, wherein said inner wall surface of the distillation column is wetted by feeding said polymerization inhibitor-containing liquid from a reflux tank connected to the distillation column.

27. A method according to claim 22, wherein said inner wall surface of the distillation column is wetted by feeding said polymerization inhibitor containing liquid from a liquid dispersing device fitted to the distillation column.

28. A method according to claim 22, wherein said acrylic acid, methacrylic acid or esters of these acids are fed together with the polymerization inhibitor to the distillation column.

29. A method according to claim 22, wherein said inner wall surface of the distillation column is wetted with the polymerization inhibitor-containing liquid, and then the operation of the distillation column is started under the wetted condition.

30. A method for washing out and removing polymerizable compounds including (meth)acrylic acid and/or (meth)acrylic esters by washing out and removing solid derived from said polymerizable compounds which are adhered onto surface of a handling device including conduits, comprising:

using a volatile base substance as a washing agent therefor.

31. A method according to claim 30, further comprising circulating aqueous ammonia into an absorption column or a distillation column whose operation is stopped and which is used for a process for producing the (meth)acrylic acid and/or (meth)acrylic esters.