Method for processing hydrogen chloride from isocyanate preparation

Patent metadata

Field	Value
Publication number	US-10307727-B2
Application number	US-201514722666-A
Country	US
Kind code	B2
Filing date	May 27, 2015
Priority date	May 27, 2014
Publication date	Jun 4, 2019
Grant date	Jun 4, 2019

Abstract

A method for processing hydrogen chloride from isocyanate preparation comprises the steps: a) providing hydrogen chloride; b) purifying the hydrogen chloride provided; and furthermore step c) or step d): c) bringing the purified hydrogen chloride into contact with water and/or with hydrochloric acid which is not saturated with respect to uptake of hydrogen chloride, d) further processing the purified hydrogen chloride to chlorine by partial oxidation. The hydrogen chloride provided in step a) contains organic and/or nitrogen-containing impurities and in step b) the purification is carried out by bringing hydrogen chloride into contact with hydrochloric acid which is saturated to the extent of ≥90% with respect to uptake of hydrogen chloride at least in a first gas scrubber ( 10 ) and circulating this hydrochloric acid at least partially through the first gas scrubber ( 10 ).

First claim

The invention claimed is:

1. A system for processing hydrogen chloride from isocyanate preparation, comprising:
at least a first gas scrubber having a first pump assigned to it, wherein the gas scrubber brings into contact hydrogen chloride gas and hydrochloric acid which is saturated to the extent of ≥90% with respect to uptake of hydrogen chloride;
wherein the first pump assigned to the particular gas scrubber allows hydrochloric acid which is saturated to the extent of ≥90% with respect to uptake of hydrogen chloride to circulate at least partially through the particular gas scrubber;
and an absorption column or an oxidation reactor, wherein
the absorption column brings hydrogen chloride removed from a gas scrubber of the system into contact with water and/or with hydrochloric acid which is not saturated with respect to uptake of hydrogen chloride;
the oxidation reactor converts hydrogen chloride removed from a gas scrubber into chlorine by partial oxidation.

2. The system according to claim 1 , wherein the hydrochloric acid which is saturated to the extent of ≥90% with respect to uptake of hydrogen chloride and the hydrogen chloride gas are led in counter-current to one another in the first gas scrubber.

3. The system according to claim 1 , wherein the first gas scrubber is configured as a packed column.

4. The system according to claim 1 , wherein a first hydrochloric acid tank is furthermore provided, in which hydrochloric acid which is saturated with respect to uptake of hydrogen chloride and which has passed through the first gas scrubber is collected and introduced on to the first gas scrubber again by means of the first pump.

5. The system according to claim 1 , further comprising:
a second gas scrubber having a second pump assigned to it, wherein the gas scrubber brings into contact hydrogen chloride gas and hydrochloric acid which is saturated to the extent of ≥90% with respect to uptake of hydrogen chloride;
wherein the second pump assigned to the second gas scrubber allows hydrochloric acid which is saturated to the extent of ≥90% with respect to uptake of hydrogen chloride to circulate at least partially through the second gas scrubber;
wherein the system passes hydrogen chloride removed from the first gas scrubber into the second gas scrubber.

Assignees

• Covestro Deutschland Ag

Inventors

• Weber Ralph
• Ehrig Martin
• Leonhäuser Johannes
• Weiβenberg Dirk

Classifications

• B01D53/1406

  Multiple stage absorption · CPC title

• C01B7/0706

  of hydrogen chloride · CPC title

• C01B7/0737

  hydrogen chloride being extracted · CPC title

• B01J19/24 Primary

  Stationary reactors without moving elements inside (B01J19/08, B01J19/26 take precedence; with stationary particles B01J8/02) · CPC title

• B01D53/1493

  Selection of liquid materials for use as absorbents · CPC title