Process for purifying propylene oxide

Patent metadata

Field	Value
Publication number	US-10544116-B2
Application number	US-201716315680-A
Country	US
Kind code	B2
Filing date	Jul 19, 2017
Priority date	Jul 20, 2016
Publication date	Jan 28, 2020
Grant date	Jan 28, 2020

Abstract

Disclosed herein is a process for purifying propylene oxide, including the steps of: (i) providing a stream S0 containing propylene oxide, acetonitrile, water, and an organic compound containing a carbonyl group —C(═O)—; and (ii) separating propylene oxide from the stream S0 by subjecting the stream S0 to distillation conditions in a distillation column to obtain a gaseous top stream S1c which is enriched in propylene oxide compared to the stream S0, a liquid bottoms stream S1a which is enriched in acetonitrile and water compared to the stream S0, and a side stream S1b containing propylene oxide which is enriched in the carbonyl compound compared to the stream S0.

First claim

The invention claimed is:

1. A process for purifying propylene oxide, the process comprising:
(i) providing a stream S0 comprising propylene oxide, acetonitrile, water, and comprising at least one of acetone and propionaldehyde; and
(ii) separating propylene oxide from the stream S0 by distillation, comprising subjecting the stream S0 to distillation conditions in a distillation column, obtaining a gaseous top stream S1c which is enriched in propylene oxide compared to the stream S0, a liquid bottoms stream S1a which is enriched in acetonitrile and water compared to the stream S0, and a side stream S1b comprising propylene oxide which is enriched in at least one of acetone and propionaldehyde compared to the stream S0;
wherein:
the distillation column is operated at an absolute pressure at the top of the distillation column in the range of from 0.1 to 2.0 bar and an internal reflux ratio in the range of from 2.0 to 6.0; and
the distillation column exhibits at least 100 theoretical trays, a rectifying section of the distillation column consists of from 30 to 70% of the theoretical trays and a stripping section of the distillation column consists of from 70 to 30% of the theoretical trays.

2. The process of claim 1 , wherein the distillation column is operated at an absolute pressure at the top of the distillation column in the range of from 0.2 to 1.5 bar.

3. The process of claim 1 , wherein the distillation column is operated at a reflux ratio in the range of from 2.5 to 5.5.

4. The process of claim 1 , wherein the distillation column exhibits from 100 to 150 theoretical trays.

5. The process of claim 1 , wherein the side stream S1b is removed from the rectifying section of the distillation column.

6. The process of claim 1 , wherein the side stream S1b is removed from the rectifying section of the distillation column at a position which is at least 1 theoretical tray above the stripping section of the distillation column.

7. The process of claim 1 , wherein the side stream S1b is removed from the rectifying section of the distillation column at a position which is from 1 to 20 theoretical tray above the stripping section of the distillation column.

8. The process of claim 1 , wherein the stream S0 further comprises at least one of an aldehyde and a ketone.

9. The process of claim 1 , wherein the stream S0 further comprises at least one selected from the group consisting of acetaldehyde, formaldehyde, butyraldehyde, isobutyraldehyde, 2-butanon, 1-pentanal, 2-pentanon, 3-pentanon, and 2-methylpentanone.

10. The process of claim 1 , wherein the stream S0 is obtained by a process comprising:
(a) providing a liquid feed stream comprising propene and optionally propane, hydrogen peroxide or a source of hydrogen peroxide, water, and acetonitrile;
(b) passing the liquid feed stream into an epoxidation zone comprising an epoxidation catalyst comprising a titanium zeolite, and subjecting the liquid feed stream to epoxidation reaction conditions in the epoxidation zone, obtaining a reaction mixture comprising propene and optionally propane, propylene oxide, water, acetonitrile, and at least one of acetone and propionaldehyde;
(c) removing an effluent stream from the epoxidation zone, the effluent stream comprising propylene oxide, water, acetonitrile, propene and optionally propane, and at least one of acetone and propionaldehyde; and
(d) separating propene and optionally propane from the effluent stream by distillation, comprising subjecting the effluent stream to distillation conditions in a distillation unit, obtaining a gaseous stream which is enriched in propene and optionally propane compared to the effluent stream subjected to distillation conditions, and a liquid bottoms stream which is enriched in propylene oxide, water, acetonitrile and at least one of acetone and propionaldehyde compared to the effluent stream subjected to distillation conditions;
wherein said liquid bottoms stream obtained according to (d) is the stream S0.

11. The process of claim 1 , wherein providing the stream S0 according to (i) comprises:
(a) providing a liquid feed stream comprising propene and optionally propane, hydrogen peroxide or a source of hydrogen peroxide, water, and acetonitrile;
(b) passing the liquid feed stream provided in (a) into an epoxidation zone comprising an epoxidation catalyst comprising a titanium zeolite, and subjecting the liquid feed stream to epoxidation reaction conditions in the epoxidation zone, obtaining a reaction mixture comprising propene and optionally propane, propylene oxide, water, acetonitrile, and at least one of acetone and propionaldehyde;
(c) removing an effluent stream from the epoxidation zone, the effluent stream comprising propylene oxide, water, acetonitrile, propene and optionally propane, and at least one of acetone and propionaldehyde;
(d) separating propene and optionally propane from the effluent stream by distillation, comprising subjecting the effluent stream to distillation conditions in a distillation unit, obtaining a gaseous stream which is enriched in propene and optionally propane compared to the effluent stream subjected to distillation conditions, and a liquid bottoms stream which is enriched in propylene oxide, water, acetonitrile and at least one of acetone and propionaldehyde compared to the effluent stream subjected to distillation conditions;
wherein said liquid bottoms stream obtained according to (d) is the stream S0.

12. The process of claim 1 , wherein the top stream S1c obtained in (ii) contains at least 99.00 weight propylene oxide based on the total weight of the stream S1c.

13. The process of claim 1 , wherein the top stream S1c obtained in (ii) contains at the outmost 50 weight-ppm of at least one of acetone and propionaldehyde based on the total weight of the stream S1c.

14. The process of claim 1 , wherein the top stream S1c obtained in (ii) contains at the outmost 100 weight-ppm water based on the total weight of the stream S1c.

15. The process of claim 1 , wherein bottoms stream S1a contains at least one of acetone and propionaldehyde in an amount of at most 20 weight-ppm based on the weight of S1a.

16. The process of claim 1 , wherein at least 95 weight-% of bottoms stream S1a consist of acetonitrile and water.

17. The process of claim 1 , wherein bottoms stream S1a contains at most 10 weight-ppm of the propylene oxide, based on the weight of S1a.

18. The process of claim 1 , wherein:
the side stream S1b comprises at least one of acetone and propionaldehyde in an amount of ≥10 weight-%, based on the total weight of the side stream S1b; and
the at least one of acetone and propionaldehyde optionally comprises propionaldehyde in an amount of ≥10 weight-% based on the total weight of the side stream S1b and acetone in an amount of ≥5 weight-% based on the total weight of the side stream S1b.

19. The process of claim 1 , wherein at least 95 weight-% of the side stream S1b consist of propylene oxide, acetonitrile, water, and at least one of acetone and propionaldehyde.

20. The process of claim 1 , which is a continuous process.

Assignees

• Basf Se

Inventors

• Teles Joaquim Henrique
• Kramp Marvin
• Mueller Christian
• Woerz Nicolai Tonio
• Metzen Bernd
• Keller Tobias
• Riedel Dominic
• Weber Markus
• Urbanczyk Daniel
• Parvulescu Andrei-Nicolae
• Wegerle Ulrike
• Mueller Ulrich

Classifications

• C07D303/04

  containing only hydrogen and carbon atoms in addition to the ring oxygen atoms · CPC title

• C07D301/12

  with hydrogen peroxide or inorganic peroxides or peracids · CPC title

• C07D303/02

  Compounds containing oxirane rings · CPC title

• C07D301/32 Primary

  Separation; Purification · CPC title