Recirculation and disposal of aqueous catalyst solutions in amine catalytic processes

Patent metadata

Field	Value
Publication number	US-9816703-B2
Application number	US-201414904898-A
Country	US
Kind code	B2
Filing date	Jul 15, 2014
Priority date	Jul 24, 2013
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

The present invention relates to the oxidative combustion of amine-containing wastewaters, especially in a process for preparing methacrolein. Methacrolein is used in chemical synthesis particularly as an intermediate for preparation of methacrylic acid, methyl methacrylate, or else of active ingredients, odorants or flavorings. More particularly, the present invention relates to an oxidative combustion of the amine-containing wastewaters with only low nitrogen oxide formation.

First claim

The invention claimed is:

1. A method for disposing of amine-containing water of reaction, where the amine-containing water is obtained from an amine-catalyzed process in which propanal is reacted with formaldehyde to give methacrolein, the method comprising:
combusting the amine-containing water of reaction in a thermal oxidizer consisting of:
a first zone comprising a burner, a fuel supply and an air supply;
a second, oxidative zone; and
a third, reductive zone having an oxygen content less than 3% by volume,
wherein a transition between the first and second zone is at a point in the thermal oxidizer where a temperature in the thermal oxidizer falls below 1100° C., and
wherein a transition between the second and third zone is at a point in the thermal oxidizer where the oxygen content within the thermal oxidizer falls below 3% by volume,

wherein the amine-containing water of reaction is not sprayed into the second, oxidative zone of the thermal oxidizer, and
wherein the amine-containing water of reaction is sprayed into the third, reductive zone of the thermal oxidizer.

2. The method of claim 1 , comprising conducting a Mannich reaction continuously in the presence of 0.1 to 20 mol % of an organic amine base and 0.1 to 20 mol % of an acid, based in each case on propanal, at a temperature of 100 to 300° C. and at a pressure of 5 to 100 bar.

3. The method of claim 1 , wherein the amine-containing water of reaction is taken from the bottom of a distillation column and the rest of the bottoms is passed into a reaction space of a plant.

4. The method of claim 1 , wherein the amine-containing water of reaction is a retentate from the bottoms of a distillation column which have been passed through a membrane separation stage.

5. The method of claim 1 , wherein a temperature between 850 and 1100° C. and an oxygen content between 5 and 21% by volume are present in the oxidative zone of the thermal oxidizer.

6. The method of claim 1 , wherein the amine-containing water of reaction is sprayed directly into a flame of the first zone.

7. The method of claim 1 , wherein ammonia, urea or an amine is additionally metered into the third, reductive zone of the thermal oxidizer.

8. The method of claim 1 , wherein at least one liquid to be combusted, comprising an organic constituent, from another process is additionally metered into the first or second zone of the thermal oxidizer.

9. The method of claim 8 , wherein the other process is a process for converting methacrolein to methyl methacrylate or methacrylic acid.

10. The method of claim 8 , wherein the other process is a process for preparing propionaldehyde proceeding from ethylene and synthesis gas, which gives rise to a liquid waste phase comprising by-products and high boilers that are combusted in the thermal oxidizer.

11. The method of claim 1 , wherein at least one gaseous phase to be combusted, comprising an organic constituent and/or hydrogen, from another process is additionally metered into the first or second zone of the thermal oxidizer.

12. The method of claim 11 , wherein the other process is a process for preparing formalin proceeding from methanol, which gives rise to a hydrogenous offgas which is combusted in the thermal oxidizer.

13. The method of claim 1 , wherein no ammonia, no urea, and no amine is metered into the third, reductive zone of the thermal oxidizer.

14. A method for disposing of amine-containing water of reaction, where the amine-containing water is obtained from an amine-catalyzed process in which propanal is reacted with formaldehyde to give methacrolein, the method comprising:
combusting the amine-containing water of reaction in a thermal oxidizer consisting of:
a first zone comprising a burner, a fuel supply and an air supply;
a second, oxidative zone; and
a third, reductive zone having an oxygen content less than 3% by volume,
wherein a transition between the first and second zone is at a point in the thermal oxidizer where a temperature in the thermal oxidizer falls below 1100° C., and
wherein a transition between the second and third zone is at a point in the thermal oxidizer where the oxygen content within the thermal oxidizer falls below 3% by volume,

wherein the amine-containing water of reaction is sprayed into the second, oxidative zone of the thermal oxidizer, and
wherein ammonia is metered into the third, reductive zone of the thermal oxidizer.

15. The method of claim 14 , wherein a temperature between 850 and 1100° C. and an oxygen content between 5 and 21% by volume are present in the oxidative zone of the thermal oxidizer.

16. The method of claim 14 , wherein the amine-containing water of reaction is additionally sprayed directly into a flame of the first zone.

Assignees

• Evonik Roehm Gmbh

Inventors

• Krill Steffen
• Balduf Torsten
• Burghardt Rudolf
• Koelbl Gerhard
• Zhao Reed

Classifications

• F23G7/065

  using gaseous or liquid fuel · CPC title

• F23G5/14

  including secondary combustion · CPC title

• F23G7/008 Primary

  for liquid waste (waste oil F23G7/05, waste liquors F23G7/04, sludges F23G7/001) · CPC title

• F23G7/001

  for sludges or waste products from water treatment installations (F23G5/008 takes precedence) · CPC title

• C07C45/82

  by distillation · CPC title