Method for treating a substance mixture comprising an aromatic amine, in particular a substance mixture of raw aniline

Patent metadata

Field	Value
Publication number	US-9682917-B2
Application number	US-201314397914-A
Country	US
Kind code	B2
Filing date	Apr 29, 2013
Priority date	May 4, 2012
Publication date	Jun 20, 2017
Grant date	Jun 20, 2017

Abstract

The present invention relates to a method for treating a substance mixture comprising an aromatic amine, wherein the aromatic amine is aniline or 2,4-diaminotoluene, preferably aniline. The substance mixture comprises an aromatic amine and compounds having a higher boiling point than the aromatic amine. The method for treating the substance mixture requires I) separating the first substance mixture by means of distillation in a first distillation unit ( 110, 1130 ), to at least partially remove some of the aromatic amine in the process, and to obtain a first bottom product which is removed from the first distillation unit ( 110, 1130 ). After removal from the first distillation unit ( 110, 1130 ), the bottom product is diluted with a condensed top product from a distillation unit that is different from the first distillation unit and/or with a composition that comprises methanol.

First claim

What is claimed is:

1. A process for treating a substance mixture comprising an aromatic amine, wherein said aromatic amine comprises aniline or 2,4-diaminotoluene,
wherein the substance mixture is a first substance mixture and comprises an aromatic amine and compounds having a higher boiling point than the aromatic amine,
comprising:
I) distillatively separating said first substance mixture in a first distillation unit to separate off at least some of said aromatic amine and to additionally obtain a first bottom product, with said first bottom product being discharged from said first distillation unit;
wherein once discharged said bottom product from said first distillation unit is diluted with a condensed top product from a distillation unit which is distinct from said first distillation unit and/or with a composition comprising methanol; wherein said condensed top product originating from a distillation unit which is distinct from said first distillation unit comprises ≧80% by weight to <100% by weight of low-boilers and ≧0% by weight to <20% by weight of water, and wherein the content of said aromatic amine in said bottom product from said first distillation unit ( 110 , 1130 ) is ≧5% by weight to ≦70% by weight, based on the total weight of the bottom product.

2. The process as claimed in claim 1 , further comprising steps Ia) and Ib), wherein Ia) and Ib) are carried out prior to I):
Ia) providing a second substance mixture, wherein the said second substance mixture comprises said aromatic amine, compounds having a lower boiling point than said aromatic amine and compounds having a higher boiling point than said aromatic amine and the aromatic amine content is different from the aromatic amine content in said first substance mixture;
Ib) distillatively separating said second substance mixture in an upstream distillation unit to separate off compounds having a lower boiling point than said aromatic amine as top product and to additionally obtain said aromatic amine as sidestream and said first substance mixture as bottom product.

3. The process as claimed in claim 1 , further comprising steps IIa), IIb) and III), wherein IIa) and IIb) are carried out prior to III) and III) is carried out prior to I):
IIa) providing a second substance mixture, wherein said second substance mixture comprises said aromatic amine, compounds having a lower boiling point than said aromatic amine and compounds having a higher boiling point than said aromatic amine and the aromatic amine content is different from the aromatic amine content in said first substance mixture;
IIb) distillatively separating said second substance mixture in a second distillation unit to separate off compounds having a lower boiling point than said aromatic amine as top product and to additionally obtain a bottom product comprising said aromatic amine;
III) distillatively separating said bottom product from said second distillation unit in a third distillation unit to separate off at least some of said aromatic amine as top product and to additionally obtain said first substance mixture as bottom product.

4. The process as claimed in claim 1 , wherein once discharged said bottom product from said first distillation unit is diluted with said top product from a distillation unit distinct from said first distillation unit and/or with said composition comprising methanol such that the mixture obtained has a viscosity at 20° C. of from ≧0.3 mPas to ≦1000 mPas.

5. The process as claimed in claim 1 , wherein said composition comprising methanol is a composition comprising methanol and water which has been obtained from a process for producing methylenediphenyldiamine.

6. The process as claimed in claim 1 , wherein said composition comprising methanol comprises ≧20% by weight to ≦95% by weight of methanol.

7. The process as claimed in claim 1 , wherein the flow rate of said composition comprising methanol is chosen such that the theoretical flow rate of pure methanol is ≧30% by weight based on the flow rate of discharged bottom product from said first distillation unit.

8. The process as claimed in claim 1 , wherein once discharged said bottom product from said first distillation unit is diluted only with one composition comprising methanol.

9. The process as claimed in claim 1 , wherein said bottom product from said first distillation unit is incinerated once it has been diluted.

Assignees

• Bayer Materialscience Ag
• Covestro Deutschland Ag

Inventors

• Merkel Michael
• Knauf Thomas
• Peters Cliff Andre
• Schmidt Thorsten

Classifications

• C07C209/84 Primary

  Purification · CPC title

• C07C211/46

  Aniline · CPC title

• C07C211/50

  with at least two amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton · CPC title