Process for recovering acetonitrile

Patent metadata

Field	Value
Publication number	US-11814337-B2
Application number	US-202117466882-A
Country	US
Kind code	B2
Filing date	Sep 3, 2021
Priority date	Sep 3, 2020
Publication date	Nov 14, 2023
Grant date	Nov 14, 2023

Abstract

A process for producing acetonitrile, the process comprising: treating a feedstock stream comprising methanol, allyl alcohol, oxazole, acetonitrile, water, and hydrogen cyanide to remove hydrogen cyanide and produce an acetonitrile stream comprising less than 1 wt. % hydrogen cyanide. The process further comprises the step of distilling the acetonitrile stream in a first distillation column to produce a first distillate comprising oxazole and methanol; a first intermediate acetonitrile stream comprising acetonitrile and oxazole and less than 1 wt % allyl alcohol; a first bottoms stream comprising allyl alcohol and water. The process further comprises the step of purifying the first intermediate acetonitrile stream to produce an acetonitrile product stream and a recycle stream comprising allyl alcohol.

First claim

We claim:

1. A process for producing acetonitrile, the process comprising:
treating a feedstock stream comprising methanol, allyl alcohol, oxazole, acetonitrile, water, and hydrogen cyanide with a caustic solution to remove hydrogen cyanide and produce an acetonitrile stream comprising less than 1 wt. % hydrogen cyanide,
distilling the acetonitrile stream in a first distillation column operated at a pressure ranging from 100 kPa to 175 kPa to produce:
a first distillate comprising oxazole and methanol;
a first intermediate acetonitrile stream comprising acetonitrile and oxazole and less than 1 wt % allyl alcohol;
a first bottoms stream comprising allyl alcohol, and water; and
purifying the first intermediate acetonitrile stream to produce an acetonitrile product stream and a recycle stream comprising allyl alcohol.

2. The process of claim 1 , wherein the first intermediate acetonitrile stream is a sidedraw, optionally taken in the upper 70% of the first distillation column.

3. The process of claim 1 , wherein:
the first distillate comprises greater than 1 wt % oxazole and greater than 5 wt % methanol;
the first intermediate acetonitrile stream comprises greater than 25 wt % acetonitrile, less than 5 wt % oxazole, and less than 50 wt % water;
the first bottoms stream comprises greater than 0.01 wt % allyl alcohol and greater than 75 wt % water.

4. The process of claim 1 , wherein the recycle stream comprise a smaller amount of allyl alcohol than the first bottoms stream.

5. The process of claim 1 , wherein the acetonitrile product stream comprising greater than 98 wt % acetonitrile.

6. The process of claim 1 , wherein the first column comprises at least 30 trays.

7. The process of claim 1 , wherein the first column comprises a condenser and wherein the condenser uses chilled water.

8. The process of claim 1 , wherein the acetonitrile product stream comprises less than 1 wt. % methanol, wherein the feedstock stream further comprises oxazole and propionitrile, wherein the acetonitrile stream comprises less than 0.01 wt. % hydrogen cyanide, and wherein the acetonitrile product stream comprises greater than 99.5 wt. % acetonitrile.

9. The process of claim 1 , wherein the purifying comprises:
treating the first intermediate acetonitrile stream comprising acetonitrile, oxazole, and hydrogen cyanide to produce a second intermediate acetonitrile stream comprising less than 1 wt % acrylonitrile and less than 1 wt % hydrogen cyanide.

10. The process of claim 9 , wherein the purifying comprises:
distilling the second intermediate acetonitrile stream to produce a third distillate comprising acetonitrile, less than 50 wt % water and greater than 0.1 wt % oxazole; and
a third bottoms comprising greater than 90 wt % acetonitrile and allyl alcohol.

11. The process of claim 10 , wherein the purifying comprises:
distilling the third bottoms to produce:
a fourth distillate comprising greater than 95 wt % acetonitrile; and
a fourth bottoms comprising greater than 1 wt % allyl alcohol and greater than 5 wt % propionitrile.

12. The process of claim 11 , wherein the purifying comprises:
treating the fourth distillate in a resin bed to remove oxazole.

13. The process of claim 1 , wherein the feedstock stream comprises greater than 0.05 wt. % methanol, less than 25 wt. % acetonitrile, and propionitrile.

14. The process of claim 1 , wherein the acetonitrile stream comprises less than 0.05 wt. % hydrogen cyanide.

15. A process for producing acetonitrile, the process comprising:
treating a feedstock stream comprising methanol, allyl alcohol, oxazole, acetonitrile, water, and hydrogen cyanide with a caustic solution to remove hydrogen cyanide and produce an acetonitrile stream comprising less than 1 wt. % hydrogen cyanide,
distilling the acetonitrile stream in a first distillation column operated at a pressure ranging from 100 kPa to 175 kPa to produce to yield at least a first intermediate acetonitrile stream comprising acetonitrile and oxazole and less than 1 wt % allyl alcohol;
treating the first intermediate acetonitrile stream to produce a second intermediate acetonitrile stream comprising less than 1 wt % acrylonitrile and less than 1 wt % hydrogen cyanide; and
distilling the second intermediate acetonitrile stream to produce:
a third distillate comprising acetonitrile, less than 50 wt % water and greater than 0.1 wt % oxazole; and
a third bottoms comprising greater than 90 wt % acetonitrile and allyl alcohol.

16. The process of claim 15 , wherein the first intermediate acetonitrile stream is a sidedraw, optionally taken in the upper 70% of the first distillation column.

17. The process of claim 15 , wherein the third bottoms comprises greater than 98 wt % acetonitrile.

18. The process of claim 15 , further comprising distilling the third bottoms to produce:
a fourth distillate comprising greater than 95 wt % acetonitrile; and
a fourth bottoms comprising greater than 1 wt % allyl alcohol and greater than 5 wt % propionitrile.

19. The process of claim 18 , wherein the fourth distillate comprises greater than 98 wt % acetonitrile.

20. The process of claim 1 , wherein the caustic solution comprises sodium hydroxide, potassium hydroxide, magnesium hydroxide; calcium hydroxide, or combinations thereof.

Assignees

• Ascend Performance Mat Operations Llc

Inventors

• Kissell Kyle
• Michaels Basil

Classifications

• C07C253/34 Primary

  Separation; Purification · CPC title

• B01D3/143

  by two or more of a fractionation, separation or rectification step · CPC title

• C07C255/03 Primary

  Mononitriles · CPC title