Process for isolating dinitrogen monoxide

• US 4,177,645 A
• Filed: 07/10/1978
• Issued: 12/11/1979
• Est. Priority Date: 07/16/1977
• Status: Expired due to Term

• Current Assignee: Bayer AG
• Original Assignee: Bayer AG
• Inventors: Schwarz, Hans-Helmut
• Primary Examiner(s): Yudkoff, Norman
• Application Number:
  US05/923,507
• Time in Patent Office: 519 Days
• Field of Search: 423/400, 62/23, 62/28, 62/31, 62/38, 62/39, 62/40
• US Class Current: 62/619
• CPC Class Codes: C01B 21/22 Nitrous oxide (N2O) C01B21/203 takes precedence

Abstract

A process for isolating dinitrogen monoxide from oxidation off-gases formed by the oxidation of a cycloalkanol or a cycloalkanone using nitric acid which off-gases contain dinitrogen monoxide in admixture with nitrogen oxide, nitrogen dioxide, nitrogen, oxygen, carbon dioxide and/or steam which comprises:

A. Drying the oxidation off-gas and if necessary removal of nitrogen monoxide, nitrogen dioxide and carbon dioxide.

B. Compressing the resultant off-gas from which water has been removed to a pressure in the range of 15 to 300 bars and cooling the same to a temperature in the range of 0° to -88° C.;

C. Removing the liquid phase obtained as a result of said compression and cooling; and

D. Cooling the resultant gas phase by expansion and passing the same in indirect heat exchange with off-gas which has been prepurified by removal of water content thereof.

Claims

1. A process for isolating dinitrogen monoxide from oxidation off-gases formed by the oxidation of a cycloalkanol or a cycloalkanone using nitric acid which off-gases contain dinitrogen monoxide in admixture with nitrogen oxide, nitrogen dioxide, nitrogen, oxygen, carbon-dioxide and/or stream which comprises:

A. Drying the oxidation off-gas;

B. Compressing the resultant off-gas from which water has been removed to a pressure in the range of 15 to 300 bars and cooling the same to a temperature in the range of 0°

to -88°

C.;

C. Removing the liquid phase obtained as a result of said compression and cooling; and

D. Cooling the resultant gas phase by expansion and passing the same in indirect heat exchange with off-gas which has been prepurified by removal of water content thereof.

2. A process according to claim 1 wherein the off-gas which has been prepurified to remove water is passed through successive zones maintained at 15 to 300 bars pressure and at a temperature in the range from 0°

to -88°

C.

3. A process according to claim 2 wherein the gas mixture obtained after removal of the liquid phase is passed through said successive zones in a generally inverse order to the passage of prepurified off-gas.

4. A process according to claim 1 wherein prior to step B nitrogen monoxide, nitrogen dioxide, and carbon dioxide are removed from the off-gas.