Process for production of acrylic acid

Patent metadata

Field	Value
Publication number	US-9776940-B2
Application number	US-201615227392-A
Country	US
Kind code	B2
Filing date	Aug 3, 2016
Priority date	Aug 7, 2015
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A process for production of acrylic acid includes preparing a product gas mixture by a catalytic gas-phase oxidation of a C 3 precursor; cooling and contacting the cooled product gas mixture in an absorption column having at least two cooling loops in countercurrent with an absorbent to obtain an absorbate A, containing the absorbent and absorbed acrylic acid; condensing a high boiler fraction of the product gas mixture in a first cooling loop; condensing a low boiler fraction of the product gas mixture in a second cooling loop; maintaining a temperature of the absorbate A in the second cooling loop at a value of at least 56° C.; removing an acid water stream comprising glyoxal from the absorption column at a side take-off located above the second cooling loop; and removing a stream F of absorbate A from the absorption column at a side take-off, located at a height of the absorption column between the first cooling loop and the second cooling loop.

First claim

The invention claimed is:

1. A process for production of acrylic acid comprising:
a) preparing a product gas mixture by a catalytic gas-phase oxidation of at least one C 3 precursor compound to obtain the product gas mixture comprising acrylic acid and glyoxal;
b) cooling the product gas mixture;
c) contacting the cooled product gas mixture in an absorption column comprising at least two cooling loops in countercurrent with an absorbent to obtain an absorbate A, comprising the absorbent and absorbed acrylic acid;
d) condensing a high boiler fraction of the product gas mixture in a first cooling loop of the at least two cooling loops;
e) condensing a low boiler fraction of the product gas mixture in a second cooling loop of the at least two cooling loops;
f) maintaining a temperature of the absorbate A in the second cooling loop at a value of at least 56° C.;
g) removing an acid water stream comprising glyoxal from the absorption column at a side take-off located above the second cooling loop;
h) removing a stream F of absorbate A from the absorption column at a side take-off, located at the first cooling loop or at a height of the absorption column between the first cooling loop and the second cooling loop;
i) transferring at least part of the absorbate A removed from the absorption column in h) into a rectification column comprising a rectifying section and a stripping section;
j) enriching the absorbent in the stripping section and enriching acrylic acid in the rectifying section;
k) withdrawing a stream C of crude acrylic acid comprising at least 90% by weight of acrylic acid out of the rectifying section as a side stream.

2. The process according claim 1 , wherein the cooling in step b) is carried out as direct cooling of the product gas mixture with a finely sprayed cooling liquid, wherein a portion of the cooling liquid evaporates.

3. The process according to claim 2 , wherein the absorption column comprises a bottom space, from which a first portion of a bottom liquid, comprising the absorbent, is withdrawn and applied in the direct cooling as the cooling liquid.

4. The process according to claim 3 , wherein a second portion of the bottom liquid is fed to a distillation unit comprising a distillation column and a circulation heat exchanger.

5. The process according to claim 4 , wherein in the distillation column, the bottom liquid of the absorption column fed to the distillation unit is separated by distillation into a vapor, in which the proportion by weight of absorbent is greater than the proportion by weight of absorbent in the bottom liquid of the absorption column, and into a liquid concentrate, in which the proportion by weight of constituents with higher boiling point than the absorbent, under distillation conditions, is greater than the proportion by weight of these constituents in the bottom liquid of the absorption column.

6. The process according to claim 3 , wherein the second cooling loop is in a second position counting all cooling loops present in the absorption column from the bottom space of the absorption column upwards.

7. The process according to claim 1 , wherein the absorption column comprises three cooling loops and a third cooling loop is arranged above the first cooling loop and the second cooling loop.

8. The process according to claim 1 , wherein the second cooling loop is arranged above the first cooling loop, the first cooling loop comprises a first chimney trail and the product gas mixture is fed into the absorption column below the first chimney trail.

9. The process according to claim 1 , wherein the second cool g loop comprises an air cooler.

10. The process according to claim 1 , wherein low boilers are stripped out of the absorbate A in a stripping unit between step c) and step d).

11. The process according to claim 1 , wherein part of the absorbent, which is withdrawn from the stripping section of the rectification column is recycled into the absorption column.

12. The process according to claim 1 , wherein the boiling point of the absorbent at standard pressure is at least 50° C. above the boiling point of acrylic acid at the same pressure.

13. The process according to claim 1 , wherein the absorbent is a mixture of 75% to 99.9% by weight of a first constituent, the first constituent consisting of 70% to 75% by weight of diphenyl ether and 25% to 30% by weight diphenyl, and 0.1% to by weight of dimethyl phthalate.

14. The process according to claim 1 , wherein the at least one C 3 precursor compound is propylene, glycerol and/or acrolein.

15. The process according to claim 14 , wherein the propylene as the C 3 precursor compound is obtained by a partial dehydrogenation and/or oxydehydrogenation of propane preceding the catalytic gas phase oxidation.

Assignees

• Basf Se

Inventors

• Korn Tobias
• Blum Till
• Carline Travis
• Fuchs Christopher
• Welch Darryl
• Zurowski Peter
• Schliephake Volker
• Rissel Steffen
• Friese Thorsten
• Jaeger Ulrich
• Haremza Sylke

Classifications

• C07C51/43

  by change of the physical state, e.g. crystallisation · CPC title

• C07C57/04

  Acrylic acid; Methacrylic acid · CPC title

• C07C51/44

  by distillation · CPC title

• C07C51/235 Primary

  of —CHO groups or primary alcohol groups · CPC title

• C07C51/42

  Separation; Purification; Stabilisation; Use of additives · CPC title