Acetonitrile separation process

Patent metadata

Field	Value
Publication number	US-2022251030-A1
Application number	US-202217668830-A
Country	US
Kind code	A1
Filing date	Feb 10, 2022
Priority date	Feb 11, 2021
Publication date	Aug 11, 2022
Grant date	—

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:
dehydrating a feedstock stream comprising acetonitrile, allyl alcohol, and water to produce a dehydrated stream comprising allyl alcohol and less than 1 wt % water; reacting allyl alcohol in the dehydrated stream with a strong acid in a reactor to yield a reactor output stream, and purifying the reactor output stream to yield a product acetonitrile stream.

2 . The process of claim 1 , wherein the feedstock stream comprises more than 0.02 wt % allyl alcohol, and wherein the reactor output stream comprises less than 7 ppm allyl alcohol.

3 . The process of claim 1 , wherein allyl alcohol in the dehydrated stream reacts with the strong acid to form a protonated salt species.

4 . The process of claim 1 , wherein the dehydrated stream further comprises oxazole, wherein oxazole in the dehydrated stream reacts with the strong acid to form oxazole sulfate.

5 . The process of claim 4 , wherein the reactor output stream comprises greater than 0.01 wt % protonated salt species and/or greater than 0.1 wt % oxazole sulfate.

6 . The process of claim 1 , wherein the feedstock stream comprises more than 38 wt % water and wherein the dehydrated stream comprises less than 0.4 wt % water.

7 . The process of claim 1 , wherein the strong acid comprises sulfuric acid.

8 . The process of claim 1 , wherein the mass ratio of the acetonitrile to the water in the dehydrated stream is greater than 60:1.

9 . The process of claim 1 , wherein the mass ratio of the acetonitrile to allyl alcohol in the reactor output stream is greater than 100,000:1.

10 . The process of claim 1 , wherein the dehydrating comprises:
distilling the feedstock stream in a dehydration distillation column to yield a dehydration distillate stream and a dehydration bottoms stream.

11 . The process of claim 10 , wherein the dehydration distillation column is operated at a pressure less than 85 kPa.

12 . The process of claim 10 , wherein the dehydrating further comprises:
extracting the dehydration distillate stream to yield an extract stream and a raffinate stream.

13 . The process of claim 12 , wherein the raffinate stream comprises more than 0.08 wt % allyl alcohol and/or more than 0.4 wt % oxazole.

14 . The process of claim 1 , wherein the purifying further comprises
distilling the reactor output stream in a lights removal distillation column to yield a lights removal distillate stream and a lights removal bottoms stream.

15 . The process of claim 14 , wherein the purifying further comprises
distilling the lights removal bottoms stream in a heavies removal distillation column to yield the product acetonitrile stream, wherein the product acetonitrile stream comprises more than 98 wt % acetonitrile.

16 . The process of claim 15 , wherein the feedstock stream and the lights removal distillate stream comprise methanol.

17 . The process of claim 15 , wherein the lights removal distillate stream comprises more than 15 wt % methanol.

18 . A process for producing acetonitrile, the process comprising:
distilling a feedstock stream comprising acetonitrile, allyl alcohol, and water in a dehydration distillation column to yield a dehydration distillate stream and a dehydration bottoms stream; extracting the dehydration distillate stream to yield an extract stream and a raffinate stream; distilling the raffinate stream in a lights removal distillation column to yield a lights removal distillate stream and a lights removal bottoms stream comprising allyl alcohol and less than 1 wt % water; reacting allyl alcohol from the lights removal bottoms stream with a strong acid in a reactor to yield a reactor output stream comprising less than 7 ppm allyl alcohol; and purifying the reactor output stream to yield a product acetonitrile stream comprising greater than 98 wt % acetonitrile.

19 . The process of claim 18 , further comprising:
treating an intermediate stream comprising acetonitrile, hydrogen cyanide, and water in a digester to remove hydrogen cyanide and produce the feedstock stream

20 . The process of claim 18 , wherein the purifying comprises:
distilling the reactor output stream in a heavies removal distillation column to yield the product acetonitrile stream.

Assignees

• Ascend Performance Mat Operations Llc

Inventors

• Kissell Kyle
• Michaels Basil

Classifications

• C07C255/03 Primary

  Mononitriles · CPC title

• C07C253/34 Primary

  Separation; Purification · CPC title

• B01D3/10

  Vacuum distillation (B01D3/12 takes precedence) · CPC title

• C07C253/32

  Separation; Purification; Stabilisation; Use of additives · CPC title