IP Library › Granted Patent US 12662376
Granted Patent B2
US 12662376 · App. 18/277,415 · Granted Jun 23, 2026

Method of separating phosgene and hydrogen chloride

Inventors: Torsten Mattke (Ludwigshafen am Rhein, DE); Kai Thiele (Antwerp, BE); Jens Ferbitz (Ludwigshafen am Rhein, DE); Peter Van Den Abeel (Antwerp, BE); Hans-Juergen Pallasch (Ludwigshafen am Rhein, DE)
Assignee: BASF SE
C01B7/0712B01D53/002C01B7/0731C01B32/80C07C263/20B01D2256/26B01D2257/2064
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Quick Facts
Patent No.
US 12662376
App. No.
18/277,415
Granted
Jun 23, 2026
Kind
B2
Abstract

A process of separating phosgene and hydrogen chloride, comprises: conveying a mixed stream containing hydrogen chloride and phosgene into a distillation column; withdrawing from the distillation column a bottom stream containing phosgene; withdrawing a top stream containing hydrogen chloride; compressing at least a portion of the top stream and at least partially condensing the compressed top stream to form a liquid stream, decompressing at least a portion of the liquid stream to form a cooled liquid stream and a cooled gas stream; and recycling the cooled liquid stream to the top of the distillation column as a reflux; the process additionally comprising temporarily introducing an absorbing solvent into the distillation column, in particular during starting-up and/or shutting-down of the process. The process allows for safe operation even when hydrogen chloride production only gradually begins or decreases, without the necessity of storing hydrogen chloride.

Claims (17)

1 . A process of separating phosgene and hydrogen chloride, comprising:

conveying a mixed stream containing hydrogen chloride and phosgene into a distillation column;

withdrawing from the distillation column a bottom stream containing phosgene;

withdrawing a top stream containing hydrogen chloride;

compressing at least a portion of the top stream and at least partially condensing the compressed top stream to form a liquid stream, decompressing at least a portion of the liquid stream to form a cooled liquid stream and a cooled gas stream; and

recycling the cooled liquid stream to the top of the distillation column as a reflux;

the process additionally comprising temporarily introducing an absorbing solvent into the distillation column, wherein the absorbing solvent is introduced at the top of the distillation column and/or into the reflux liquid.

2 . The process according to claim 1 , wherein the absorbing solvent is introduced during starting-up and/or shutting-down of the process.

3 . The process according to claim 1 , wherein the absorbing solvent is selected from monochlorobenzene and dichlorobenzene.

4 . The process according to claim 1 , wherein the absorbing solvent is mixed with the liquid stream before decompressing and is introduced into the distillation column with the recycled cooled liquid stream.

5 . The process according to claim 1 , wherein the pressure drop during decompressing is at least 5 bar.

6 . The process according to claim 1 , wherein the mixed stream is conveyed into the distillation column as a side feed, the distillation column having a rectifying section above the side feed and a stripping section below the side feed.

7 . The process according to claim 1 , wherein the compressed top stream is directed to a rectifying column and a stream obtained at the bottom of the rectifying column is recycled to the top of the distillation column.

8 . The process according to claim 1 , wherein the liquid stream is heat-exchanged in a heat exchanger with the top stream before the top stream is compressed.

9 . The process according to claim 1 , wherein an uncondensed portion of the top stream is heat-exchanged in a heat exchanger with the compressed top stream that is to be condensed.

10 . The process according to claim 1 , comprising withdrawing a gaseous side stream from the distillation column via a side takeoff, at least partially condensing the side stream in a first cooler, recycling a liquid fraction into the distillation column and supplying a gaseous portion to a second cooler, wherein in the second cooler the gaseous portion is heat-exchanged with the top stream.

11 . The process according to claim 10 , wherein the top stream, before being fed to the second cooler, is heat-exchanged with the condensed top stream.