Claims
- 1. In a process for reducing oxides of nitrogen contained in an exhaust gas by passing said gas in admixture with a gaseous reducing agent in contact with a synthetic zeolitic molecular sieve catalyst at an elevated temperature above about 200.degree. C., the improvement which comprises contacting said gas at a space velocity of 3,000 to 60,000 volumes of gas per volume of catalyst per hour and a temperature below about 700.degree. C. with said catalyst in the form of a monolithic body having channels extending therethrough, said body consisting essentially of fine crystals of a synthetic zeolite molecular sieve formed in situ by calcining a monolithic body of kaolin, treating the calcined body of kaolin with a caustic solution to develop a synthetic zeolitic molecular sieve therein and etch the surfaces thereof, said crystals of molecular sieve being disseminated throughout said body in an essentially amorphous alumina-silica porous residue of anhydrous calcined clay having etched diffusion paths to and from the embedded synthetic zeolitic molecular sieve.
- 2. The process of claim 1 wherein said crystals comprise from 2 to 90 weight percent of said structure.
- 3. The process of claim 1 wherein said crystals comprise faujasite-type zeolite.
- 4. The process of claim 1 wherein said crystals comprise ZSM-5 type zeolite.
- 5. The process of claim 1 wherein said crystals comprise mordenite.
- 6. The process of claim 1 wherein said body is in the form of a honeycomb.
- 7. The process of claim 1 wherein said body is in the form of a thin-walled honeycomb.
- 8. The process of claim 1 wherein said reducing gas is ammonia.
- 9. The process of claim 1 wherein said zeolite is in the acid form.
- 10. The process of claim 1 wherein said zeolite contains transition metal cations.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of copending application Ser. No. 856,658, filed Dec. 2, 1977.
US Referenced Citations (5)
Foreign Referenced Citations (1)
Number |
Date |
Country |
51-91868 |
Aug 1976 |
JPX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
856658 |
Dec 1977 |
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