Patent US2469641A successfully refreshed from Google Patents.
Patent US4151525A successfully refreshed from Google Patents.
US4157375A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Conversion of nitrogen oxides
Assignee: BASF Catalysts LLC
•
Filing: 1978-03-30
•
Granted: 1979-06-05
•
Expires: 1998-03-30
Abstract
Abstract Zeolite catalyzed reduction of nitrogen oxides in exhaust gases is conducted with catalytic elements in the form of multi-channel structures in which parallel channels are defined by thin walls constituted by refractory oxides having zeolite dispersed therein and accessable to diffusion from surfaces of the channel walls. Such structures, preferably monolithic honeycomb forms, are prepared by calcining extruded or cast forms or kaolin at elevated temperatures and treating the calcined kaolin honeycomb with a caustic solution to develop a desired zeolite within the wall members and etch the wall surfaces to provide diffusion paths to and from the embedded zeolite. Such structures are peculiarly suited to high space velocity processes such as reduction of nitrogen oxides in providing for protection of the zeolite catalyst against erosion by high velocity gas streams while also providing adequate diffusivity for reactants at the high space velocities typical of the known reaction between oxides of nitrogen and a reducing agent such as ammonia.
Inventors
- 👤 Stanley M. Brown
- 👤 Gerald M. Woltermann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 04:05
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/92; B01D53/94; B01D53/9404; B01D53/9409; B01D53/9413; B01D53/9418; B01J; B01J29/00; B01J29/04; B01J29/06; B01J29/08; B01J29/18; B01J29/40; B01D2251/00; B01D2251/20; B01D2251/204; B01D2251/206; B01D2251/2062; B01D2255/00; B01D2255/50; B01J2229/00; B01J2229/10; B01J2229/26; B01J2229/30; B01J2229/42
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
166 words
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° 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° 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.
Claim 2
Dependent Claim
166 words
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° 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° 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.
Claim 3
Dependent Claim
18 words
The process of claim 1 wherein said crystals comprise from 2 to 90 weight percent of said structure.
Claim 4
Dependent Claim
11 words
The process of claim 1 wherein said crystals comprise faujasite-type zeolite.
Claim 5
Dependent Claim
12 words
The process of claim 1 wherein said crystals comprise ZSM-5 type zeolite.
Claim 6
Dependent Claim
10 words
The process of claim 1 wherein said crystals comprise mordenite.
Claim 7
Dependent Claim
15 words
The process of claim 1 wherein said body is in the form of a honeycomb.
Claim 8
Dependent Claim
16 words
The process of claim 1 wherein said body is in the form of a thin-walled honeycomb.
Claim 9
Dependent Claim
11 words
The process of claim 1 wherein said reducing gas is ammonia.
Claim 10
Dependent Claim
13 words
The process of claim 1 wherein said zeolite is in the acid form.
Claim 11
Dependent Claim
12 words
The process of claim 1 wherein said zeolite contains transition metal cations.
References Cited (Backward Citations)
US3468815A
Cited
US3839225A
Cited
US3895095A
Cited
US4007134A
Cited
US3939246A
Cited
JPS5191868A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-06-04 | 1982-12-04 | 1983-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-06-04 | 1986-12-04 | 1987-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-06-04 | 1990-12-04 | 1991-06-05 | $7700.00 | Window Closed / Lapsed |