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

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.

1 .- 21 . (canceled)  
   
   
       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 .- 31 . (canceled)