Ozone decomposition and electrodesorption process

• US 4,101,296 A
• Filed: 04/20/1977
• Issued: 07/18/1978
• Est. Priority Date: 04/17/1975
• Status: Expired due to Term

• Current Assignee: W.R. Grace & Co.-Conn. (WR Grace & Company)
• Original Assignee: WR Grace & Company
• Inventors: Lowther, Frank Eugene
• Primary Examiner(s): Wyse, Thomas G.
• Application Number:
  US05/789,307
• Time in Patent Office: 454 Days
• Field of Search: 210/63 Z, 250/533, 423/210, 423/219, 204/129, 204/130, 204/176, 204/186 B, 204/19 SN, 204/26 S, 204/144 S, 55/75, 55/208, 55/389, 55/29, 55/31, 55/32-35, 55/62
• US Class Current: 95/68
• CPC Class Codes: B01D 53/66 Ozone
• CPC Class Codes: B01J 20/3408 of aluminosilicate molecular sieves
• CPC Class Codes: B01J 29/90 Regeneration or reactivation
• CPC Class Codes: C01B 13/0203 from inorganic compounds
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02P 20/584 Recycling of catalysts

Abstract

An ozone decomposition system wherein moist ozone-containing gas is contacted with a bed of active zeolite molecular sieve particles for converting ozone, which comprises means for reactivating the bed by directly applying to the zeolite particles a high-voltage low-frequency electrical field having sufficient potential gradient to separate sorbed moisture as molecular water.

Claims

1. A method for decomposing ozone which comprises:

(a) contacting a gas mixture which includes ozone and water vapor with a bed of crystalline alumino-silicate zeolite, said zeolite being active for the decomposition of ozone; and

(b) maintaining the activity of said zeolite bed by the application of a 0-10³ Hz electrical field of at least 0.2 Kv/cm across the bed to maintain a current density of about 0.01 to 100 microamps/cm² to remove water from said bed as molecular water.

2. The method of claim 1 wherein said zeolite is selected from the group consisting of Type A, L, X and Y zeolites.

3. The method of claim 1 wherein the particle size of said zeolite is in the range of from about 1 micron to 500 microns.

4. The method of claim 1 wherein the activity of said bed is maintained continuously during the decomposition process.

5. The method of claim 1 wherein said activity is maintained by periodically applying said electrical field and conducting a gas through said bed to remove water from said bed.

6. The method of claim 1 wherein the temperature of said bed is maintained above -50°

C.

7. The method of claim 1 wherein said gas mixture is off-gas from a water treatment process.

8. In an improved method for decomposing ozone mixed with a moisture containing gas stream wherein the stream is contacted with a crystalline aluminosilicate zeolite which is active for the decomposition of ozone, the improvement comprising maintaining the ozone decomposition activity of the zeolite by the application of a 0-10³ Hz electrical field of at least 0.2 Kv/cm across the zeolite to maintain a current density of about 0.01 to 100 microamps/cm², whereby water is removed from said zeolite substantially as molecular water.

9. The method of claim 8 wherein said electrical field is continuously applied to said zeolite.

10. The method of claim 8 wherein said zeolite is a particulate zeolite bed selected from the group consisting of Type A, L, X and Y zeolites.

11. The method of claim 8 wherein said electrical field is applied periodically to said zeolite.

12. The method of claim 8 wherein said stream is off-gas from a water treatment process.