Method for purifying nitrogen trifluoride gas

• US 4,933,158 A
• Filed: 10/24/1989
• Issued: 06/12/1990
• Est. Priority Date: 10/25/1988
• Status: Expired due to Term

• Current Assignee: Mitsui Chemicals Incorporated (Mitsui Chemicals)
• Original Assignee: Mitsui Toatsu Chemicals Incorporated (Mitsui Chemicals)
• Inventors: Aritsuka, Makoto, Iwanaga, Naruyuki
• Primary Examiner(s): Doll, John
• Assistant Examiner(s): Langel, Wayne A.
• Application Number:
  US07/425,957
• Time in Patent Office: 231 Days
• Field of Search: 423/210, 423/230, 423/236, 423/239, 423/240 S, 423/406
• US Class Current: 423/210
• CPC Class Codes: C01B 21/0837 Purification

Abstract

There is here disclosed a method for removing nitrous oxide (N₂ O), carbon dioxide (CO₂) and dinitrogen difluoride (N₂ F₂) from a nitrogen trifluoride gas. The present invention is directed to a method for purifying a nitrogen trifluoride gas which comprises the steps of thermally treating, at a temperature of 250° to 700° C., a zeolite selected from the group consisting of analcime, clinoptilolite, mordenite, ferrierite, phillipsite, chabazite, erionite and laumotite; forming a packed bed of the treated zeolite; and passing the nitrogen trifluoride gas containing the gaseous impurities at a temperature of -125° to 50° C. through the filler layer.

Claims

1. A method for purifying a nitrogen trifluoride gas which comprises the steps of thermally treating, at a temperature of 250°

to 700°

C., a natural zeolite selected from the group consisting of analcime, clinoptilolite, mordenite, ferrierite, phillipsite, chabazite, erionite and laumontite;

forming a packed bed of said treated zeolite; and

passing said nitrogen trifluoride gas containing gaseous impurities at a temperature of -125°

to 50°

C. through said packed bed.

2. The method for purifying a nitrogen trifluoride gas according to claim 1 wherein said gaseous impurities in said nitrogen trifluoride gas are N₂ O, CO₂ and N₂ F₂.

3. The method for purifying a nitrogen trifluoride gas according to claim 1 wherein said thermal treatment of said zeolite is carried out for a period of 10 minutes to 80 hours.

4. The method for purifying a nitrogen trifluoride gas according to claim 1 wherein said thermal treatment of said zeolite is carried out while an inert gas is fed.

5. The method for purifying a nitrogen trifluoride gas according to claim 1 wherein said thermal treatment of said zeolite is carried out by heating said packed bed of said zeolite, and successively said nitrogen trifluoride gas containing said gaseous impurities is passed through said packed bed.