METHOD FOR PRODUCING HIGH PURITY (METH)ACRYLIC ACID

Claims

1. A method for producing (meth)acrylic acid, the method includes introducing a mixed gas containing (meth)acrylic acid into reaction with water in an absorption column to obtain an aqueous solution of (meth)acrylic acid; directing an aqueous solution of (meth)acrylic acid into a crystallizer, carrying out crystallization and obtaining purified (meth)acrylic acid, and directing the mother liquor separated from the purified (meth)acrylic acid into a water separation column; separating into an upper effluent stream of the water separation column comprising water and into a lower effluent stream of the water separation column comprising (meth)acrylic acid and high boiling point by-products, in a water separation column; and pumping the lower outlet stream of the water separation column to the high-boiling by-product separation column and feeding the upper outlet stream of the high-boiling by-product separation column containing (meth)acrylic acid to the crystallizer.

2. A method for producing (meth)acrylic acid according to claim 1, wherein an aqueous solution of (meth)acrylic acid is fed into a degassing column and the bottom discharge stream of the degassing column, from which low-boiling by-products have been removed, is fed into a crystallizer.

3. A method for producing (meth)acrylic acid according to claim 2, wherein the content of (meth)acrylic acid in the lower discharge stream of the degassing column is from 85 to 99 wt.%.

4. A method for producing (meth)acrylic acid according to claim 1, wherein the mother liquor contains (meth)acrylic acid, water, acetic acid and high-boiling by-products.

5. A method for producing (meth)acrylic acid according to claim 1, wherein the upper outlet stream of the water separation column is fed to a layer separator, part of the aqueous phase, including water and acetic acid, is pumped into an absorption column and the remainder is removed as wastewater.

6. A method for producing (meth)acrylic acid according to claim 1, wherein the content of (meth)acrylic acid in the upper output stream of the high-boiling by-product separation column is from 95 to 99 wt.%.

7. The method for producing (meth)acrylic acid according to claim 1, wherein the flow rate of acetic acid withdrawn from the upper part of the absorption column is from 30 to 60 wt.% based on the flow rate of acetic acid introduced into the absorption column.

8. A method for producing (meth)acrylic acid according to claim 1, wherein the mother liquor comprises from 50 to 80 wt.% (meth)acrylic acid and from 20 to 50 wt.% water.

9. The method for producing (meth)acrylic acid according to claim 1, wherein the flow rate of water included in the mother liquor is from 35 to 45 wt.% based on the flow rate of water introduced into the absorption column.

10. The method for producing (meth)acrylic acid according to claim 1, where the mixed gas including (meth)acrylic acid is the product of a gas-phase oxidation reaction of a reactant including air, the starting compound and the recirculation gas in the reactor, and recycle gas is that which, after a portion of the absorption column overhead stream is fed to the cooling tower and cooled, is withdrawn as the cooling tower overhead stream and pumped to the reactor.