Method for purifying (meth)acrylic acid

Abstract

A method for purifying a crude (meth)acrylic acid obtained by a vapor phase catalytic oxidation method, characterized in that the crude (meth)acrylic acid having most parts of water and acetic acid removed therefrom, is fed to and distilled in a first distillation column of a purification system comprising first to third three distillation columns, the top fraction from the first distillation column is fed to and distilled in the second distillation column, the resulting top fraction is recovered as a high purity (meth)acrylic acid product, the bottoms from the first and second distillation columns are fed to and distilled in the third distillation column, and the resulting top fraction is fed to the first distillation column.

1 . A method for producing (meth)acrylic acid, comprising:
 feeding a crude (meth)acrylic acid obtained by vapor phase catalytic oxidation to a distillation column to continuously distil and purify it in the presence of a hydrazine,   wherein the hydrazine is added to the crude (meth)acrylic acid prior to feeding to the distillation column, and the crude (meth)acrylic acid having the hydrazine added thereto is heated to a feeding temperature of from 60° C. to 80° C. and then fed to the distillation column at the feeding temperature.   
     
     
         2 . The method according to  claim 1 , wherein the feeding temperature is from 60° C. to 75° C. 
     
     
         3 . The method according to  claim 1 , wherein the feeding temperature is from 62° C. to 80° C. 
     
     
         4 . The method according to  claim 1 , wherein the feeding temperature is from 62° C. to 75° C.