Acetonitrile separation process

Patent metadata

Field	Value
Publication number	US-11976025-B2
Application number	US-202117466880-A
Country	US
Kind code	B2
Filing date	Sep 3, 2021
Priority date	Sep 4, 2020
Publication date	May 7, 2024
Grant date	May 7, 2024

Abstract

Provided herein are processes for the separation of acetonitrile from low-purity feedstock streams. The provided processes are particularly useful for isolating acetonitrile at high purity from chemical manufacturing waste streams that include methanol, water, and allyl alcohol.

First claim

We claim:

1. A process for producing acetonitrile, the process comprising:
digesting a feedstock stream comprising acetonitrile, methanol, hydrogen cyanide, and water to remove hydrogen cyanide in a digester to produce an intermediate acetonitrile stream comprising less than 1 wt % hydrogen cyanide;
distilling the intermediate acetonitrile stream in a first distillation column to yield a first bottoms stream comprising water, and a first distillate stream comprising acetonitrile, wherein the first distillation column is operated at a pressure less than 150 kPa; and
purifying the first distillate stream to yield a product acetonitrile stream and a recycle stream.

2. The process of claim 1 , wherein the feedstock stream comprises more than 50 wt % water and wherein the first distillate stream comprises less than 45 wt % water.

3. The process of claim 1 , wherein the feedstock stream and the first bottoms stream each further comprises from 0 to 1.0 wt. % allyl alcohol.

4. The process of claim 3 , wherein the feedstock stream comprises more than 0.05 wt % allyl alcohol and wherein the first distillate stream comprises less than 0.05 wt % allyl alcohol.

5. The process of claim 3 , wherein the mass ratio of the acetonitrile in the first distillate stream to the allyl alcohol in the first distillate stream is greater than 1000:1.

6. The process of claim 1 , wherein the mass ratio of the acetonitrile in the first distillate stream to the water in the first distillate stream is greater than 3:1.

7. The process of claim 1 , wherein sodium hydroxide and the feedstock stream are fed to the digester.

8. The process of claim 1 , wherein the feedstock stream and the first distillate stream each further comprises oxazole.

9. The process of claim 8 , wherein the feedstock stream comprises more than 0.09 wt % oxazole and wherein the first bottoms comprises less than 0.1 wt % oxazole.

10. The process of claim 1 , wherein the feedstock stream further comprises acrylonitrile.

11. The process of claim 1 , wherein the first distillation column is operated at a pressure less than 80 kPa.

12. The process of claim 1 , wherein the product acetonitrile stream comprises more than 98 wt % acetonitrile.

13. The process of claim 1 , wherein the purifying comprises:
distilling the first distillate stream in a second distillation column to yield a second distillate stream comprising methanol, and a second bottoms stream comprising acetonitrile.

14. The process of claim 13 , wherein the second distillation column is operated at a pressure less than 200 kPa.

15. The process of claim 13 , wherein the second distillate stream comprises more than 25 wt % methanol.

16. The process of claim 13 , wherein the purifying comprises:
distilling the second bottoms stream in a third distillation column to yield the recycle stream comprising acetonitrile, and a third bottoms stream comprising acetonitrile.

17. The process of claim 16 wherein the third distillation column is operated at a pressure less than 550 kPa.

18. The process of claim 16 , wherein the purifying comprises:
distilling the third bottoms stream in a fourth distillation column to yield the product acetonitrile stream, wherein the fourth distillation column is operated at a pressure less than 80 kPa.

19. The process of claim 1 , wherein the feedstock stream comprises more than 0.7 wt % methanol.

20. The process of claim 1 , wherein the feedstock comprises propionitrile.

Assignees

• Ascend Performance Mat Operations Llc

Inventors

• Kissell Kyle
• Michaels Basil

Classifications

• C07C253/34 Primary

  Separation; Purification · CPC title

• C07C255/03 Primary

  Mononitriles · CPC title