# US 10,307,727 B2 · Method for processing hydrogen chloride from isocyanate preparation

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 10,307,727 B2
- Document ID: US10307727B2
- Status: Granted
- Kind: B2
- Application number: 14/722,666
- Filed: 2015-05-27
- Published: 2015-12-03
- Granted: 2019-06-04
- Earliest claimed: 2014-05-27
- Assignees: Covestro Deutschland AG
- Applicants: Covestro Deutschland AG
- Inventors: Ralph Weber; Martin Ehrig; Johannes Leonhäuser; Dirk Weiβenberg
- Web page: https://patentgrep.com/patent/US10307727B2

## CPC

- B01J 19/24: Stationary reactors without moving elements inside (B01J19/08, B01J19/26 take precedence; with stationary particles B01J8/02)
- B01D 47/14: Packed scrubbers (packing elements B01J19/30, B01J19/32)
- B01D 53/1406: {Multiple stage absorption}
- B01D 53/1431: {Pretreatment by other processes}
- B01D 53/1456: {Removing acid components}
- B01D 53/1493: {Selection of liquid materials for use as absorbents}
- C01B 7/04: Preparation of chlorine from hydrogen chloride
- C01B 7/0706: {of hydrogen chloride}
- C01B 7/0737: {hydrogen chloride being extracted}
- C01B 7/0743: {of gaseous or dissolved chlorine}
- B01D 2252/103: Water
- B01J 2219/24: Stationary reactors without moving elements inside
- Y02P 20/20: Improvements relating to chlorine production
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## 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).

## Claims

### Claim 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 1)

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

### Claim 4 (depends on 1)

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.

### Claim 5 (depends on 1)

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.