Process for the purification of hydrogen cyanide

Patent metadata

Field	Value
Publication number	US-11939281-B2
Application number	US-201917256861-A
Country	US
Kind code	B2
Filing date	Jul 17, 2019
Priority date	Jul 30, 2018
Publication date	Mar 26, 2024
Grant date	Mar 26, 2024

Abstract

The present invention relates to a process for the purification of hydrogen cyanide, comprising the steps of a) splitting a liquid feed stream ( 1 ) comprising hydrogen cyanide into at least a first liquid stream ( 2 ) and a second liquid stream ( 3 ), b) introducing the first liquid stream ( 2 ) into a distillation column ( 4 ) at a point between the top and the bottom of the distillation column, c) introducing the second liquid stream ( 3 ) into the distillation column ( 4 ) at the top of the distillation column, d) withdrawing an overhead vapor stream ( 5 ) enriched in hydrogen cyanide from the distillation column ( 4 ), and e), withdrawing a bottom stream ( 6 ) depleted in hydrogen cyanide, wherein the temperature of the second liquid stream ( 3 ) in step c) is lower than the temperature of the first liquid stream ( 2 ) in step b).

First claim

The invention claimed is:

1. A process for the purification of hydrogen cyanide, comprising:
a) splitting a liquid feed stream comprising hydrogen cyanide into at least a first liquid stream and a second liquid stream,
b) introducing the first liquid stream with a temperature T 1 into a distillation column at a point between the top and the bottom of the distillation column,
c) introducing the second liquid stream with a temperature T 2 into the distillation column at the top of the distillation column,
d) withdrawing an overhead vapor stream enriched in hydrogen cyanide from the distillation column, and
e) withdrawing a bottom stream ( 6 ) depleted in hydrogen cyanide from the distillation column,
wherein the temperature T 2 of the second liquid stream in step c) is lower than the temperature T 1 of the first liquid stream in step b).

2. The process of claim 1 , wherein the distillation column is operated with a temperature of at least 30° C. at the top of the distillation column.

3. The process of claim 1 , wherein the distillation column is operated with a temperature in the range of from 30 to 50° C. at the top of the distillation column.

4. The process of claim 1 , wherein the mass flow ratio of the first liquid stream to the second liquid stream ranges from 95:5 to 50:50.

5. The process of claim 1 , wherein the mass flow ratio of the first liquid stream to the second liquid stream ranges from 90:10 to 70:30.

6. The process of claim 1 , wherein the temperature T 2 of the second liquid stream in step c) is less than 25° C.

7. The process of claim 1 , wherein the first liquid stream is heated prior to its introduction into the distillation column.

8. The process of claim 7 , wherein the first liquid stream is heated to a temperature T 1 of from 25° C. to 130° C. at the most.

9. The process of claim 7 , wherein the first liquid stream is heated by heat exchange with the bottom stream from the distillation column.

10. The process of claim 1 , further comprising:
f) introducing at least one further liquid stream, which is also split from the liquid feed stream comprising hydrogen cyanide, in addition to the first liquid stream and second liquid stream, into the distillation column at a point between the points of induction of the first and second liquid streams,
wherein the temperature T 3 of the at least one further stream is between the temperature T 2 of the second liquid stream in step c) and the temperature T 1 of the first liquid stream in step b).

11. The process of claim 10 , wherein the first liquid stream is introduced into the distillation column in step b) at a larger mass flow rate than the at least one further stream, which is introduced into the distillation column in addition to the first liquid stream.

12. The process of claim 1 , wherein the overhead vapor stream withdrawn from the distillation column in step d) is not condensed.

13. The process of claim 1 , further comprising:
g) condensing at least a part of the overhead vapor stream withdrawn from the distillation column to give a liquefied stream and, optionally, a residual vapor stream, and
h) feeding the liquefied stream of step g) to a further processing or to a storage tank.

14. The process of claim 13 , wherein the residual vapor stream of step h) is not condensed.

15. The process of claim 1 , further comprising:
reacting the overhead vapor stream enriched in hydrogen cyanide with 3-mercaptopropionaldehyde to produce 2-hydroxy-4-(methylthio)butyronitrile.

Assignees

• Evonik Operations Gmbh

Inventors

• Körfer Martin
• Eicker Michael
• Becker Catrin Dorothee
• Merker Thorsten
• Bussmann Marko

Classifications

• C07C319/20 Primary

  by reactions not involving the formation of sulfide groups · CPC title

• B01D3/007

  Energy recuperation; Heat pumps · CPC title

• B01D3/008

  Liquid distribution · CPC title

• C01C3/0295 Primary

  Purification · CPC title

• C07C319/28

  Separation; Purification · CPC title