Method for purifying (meth)acrylic acid

Patent metadata

Field	Value
Publication number	US-12116339-B2
Application number	US-202117914387-A
Country	US
Kind code	B2
Filing date	Mar 23, 2021
Priority date	Apr 6, 2020
Publication date	Oct 15, 2024
Grant date	Oct 15, 2024

Abstract

The invention relates to a process for the continuous production of acrylic acid, in the absence of organic solvent and in the absence of chemical treatment of the aldehydes, and without employing a dividing-wall column, from a gaseous reaction mixture comprising acrylic acid obtained by gas-phase oxidation of a precursor of acrylic acid.

First claim

The invention claimed is:

1. A process for the purification of (meth)acrylic acid in an absence of organic solvent and in an absence of a chemical treatment of aldehydes, from a gaseous reaction mixture comprising (meth)acrylic acid obtained by gas-phase oxidation of a precursor of (meth)acrylic acid, said process comprising the following stages:
subjecting said reaction mixture to a dehydration, without using azeotropic solvent, in a dehydration column, resulting in a top stream and a bottom stream being obtained,
sending at least a portion of said bottom stream from the dehydration column into an upper part of a finishing column, where light products are distilled, heavy products are removed at a bottom of the finishing column and a side stream is withdrawn,
sending said side stream from the finishing column to a lower third of a third distillation column, resulting in a top stream, a side stream and a bottom stream being obtained, said top stream being subjected to a condensation and then returned after condensation, partly in the third distillation column in reflux form and partly being recovered, said side stream being withdrawn in a half of a lower part of said third distillation column.

2. The process as claimed in claim 1 , in which at least a portion of the top stream from the dehydration column is subjected to condensation, then is returned to the dehydration column in reflux form.

3. The process as claimed in claim 1 in which a portion of the bottom stream from the dehydration column is returned in reflux form to a lower part of the dehydration column to form a recirculation loop.

4. The process as claimed in claim 3 in which said light products, composed of water and acetic acid, extracted at a top of the finishing column, are subjected to a condensation forming a condensate, at least a portion of the condensate thus obtained being returned to the dehydration column to be mixed with a stream of said recirculation loop.

5. The process as claimed in claim 1 in which a residual stream recovered at a bottom of the third distillation column is recycled to an esterification plant manufacturing C 1 -C 8 (meth)acrylic esters, without additional purification.

6. The process as claimed in claim 1 in which the side stream withdrawn from the finishing column comprises a solution containing at least 98.5% of acrylic acid, less than 0.3% of water, less than 0.075% of acetic acid, and having a furfural content of greater than 50 ppm and less than 0.05%, a benzaldehyde content of greater than 50 ppm and less than 0.05%, and a protoanemonin content of greater than 50 ppm and less than 0.05%.

7. The process as claimed in claim 1 in which the top stream from the third distillation column comprises, after condensation, a solution containing at least 99.7% of acrylic acid and contents of impurities as follows: furfural content of less than 2 ppm, a content of total aldehydes (furfural, benzaldehyde, acrolein) of less than 10 ppm, and a protoanemonin content of less than 2 ppm.

8. The process as claimed in claim 1 in which the side stream withdrawal stream from the third distillation column comprises, after condensation, a solution containing at least 99.7% of acrylic acid, less than 0.3% of water, a furfural content of greater than 50 ppm, a benzaldehyde content of greater than 50 ppm and a protoanemonin content of greater than 50 ppm.

9. The process as claimed in claim 1 in which the bottom stream from the third distillation column containing at least 97% of acrylic acid is mixed with an acrylic acid stream obtained in side stream withdrawal from the third distillation column or recycled to an esterification unit without additional treatment.

10. The process as claimed in claim 1 in which the dehydration column comprises from 5 to 50 theoretical plates and operates at atmospheric pressure or higher, up to an absolute pressure of 1.5×10 5 Pa.

11. The process as claimed in claim 1 in which the temperature in the upper part of the dehydration column is at least 40° C. and the temperature of the bottom stream from the dehydration column is less than 120° C.

12. The process as claimed in claim 1 in which the finishing column comprises from 5 to 30 theoretical plates and operates under an absolute pressure ranging from 5 kPa to 60 kPa, the temperature of the top stream being between 40° C. and approximately 90° C. and the temperature of the bottom stream being between 60° C. and 120° C.

13. The process as claimed in claim 1 in which the distillation column operates under an absolute pressure ranging from 5 kPa to approximately 60 kPa, the temperature of the top stream being between 40° C. and approximately 90° C. and the temperature of the bottom stream being between 60° C. and 120° C.

14. The process as claimed in claim 1 in which the reflux ratio of the distillation column, defined as the flow rate of recycling from the top to the column, with respect to that of the withdrawal of (meth)acrylic acid at the column top, is between 1.5 and 4.

15. The process as claimed in claim 1 in which a polymerization inhibitor chosen from hydroquinone methyl ether, manganese acetate, hydroquinone, phenothiazine and mixtures thereof are injected at the top of all the columns.

16. The process as claimed in claim 1 in which the ratio for obtaining glacial acrylic acid/technical acrylic acid varies from 10% to 90%.

Assignees

• Arkema France

Inventors

• Tretjak Serge
• Huve Aurelien

Classifications

• C07C57/04 Primary

  Acrylic acid; Methacrylic acid · CPC title

• C07C51/46

  by azeotropic distillation · CPC title

• B01D3/4205

  Reflux ratio control splitter · CPC title

• B01D3/34

  with one or more auxiliary substances · CPC title

• B01D3/143

  by two or more of a fractionation, separation or rectification step · CPC title