US4303612A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gas sensitive devices
Assignee: Diffracto Ltd Canada
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Filing: 1980-06-04
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Granted: 1981-12-01
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Expires: 2000-06-04
Abstract
Abstract Catalytic gas sensors comprise a noble metal filament onto which is applied alumina having a particle size of not greater than 100 A and a catalyst material is impregnated into the dried alumina. The alumina may be dried by passage of an electric current through the filament and, prior to coating the filament may be stabilized by coating with a thermally decomposable aluminium salt and decomposed by passing a pulsed electric current.
Inventors
- 👤 John M. Sonley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 10:57
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/14; G01N27/16
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
113 words
A catalytic gas sensing element comprising a noble metal filament having a porous coating of alumina which coating is impregnated with a material which catalyses the oxidation of hydrocarbons wherein said element is formed by applying a slurry of alumina onto the filament, drying the applied slurry, applying a solution of the catalytic material to the dried alumina, drying the thus impregnated alumina and activating the catalytic material, wherein the particle size of the alumina, in at least the outer regions of the coating, is not more than 100 A and wherein the alumina contains up to 0.6% by weight of sulphate ions present in at least the outer regions of the coating.
Claim 2
Dependent Claim
113 words
A catalytic gas sensing element comprising a noble metal filament having a porous coating of alumina which coating is impregnated with a material which catalyses the oxidation of hydrocarbons wherein said element is formed by applying a slurry of alumina onto the filament, drying the applied slurry, applying a solution of the catalytic material to the dried alumina, drying the thus impregnated alumina and activating the catalytic material, wherein the particle size of the alumina, in at least the outer regions of the coating, is not more than 100 A and wherein the alumina contains up to 0.6% by weight of sulphate ions present in at least the outer regions of the coating.
Claim 3
Dependent Claim
29 words
An element as claimed in claim 1 wherein the alumina particles are conglomerates formed from smaller particles, the average size of said conglomerate being not greater than 100 A.
Claim 4
Dependent Claim
15 words
An element as claimed in claim 1 wherein the particle size is from 50-70 A.
Claim 5
Dependent Claim
20 words
An element as claimed in claim 1 wherein there is a further coating of alumina on the catalyst impregnated coating.
Claim 6
Dependent Claim
27 words
An element as claimed in claim 1 wherein the filament is a stabilised filament produced by coating the noble metal with aluminium nitrate and decomposing the nitrate.
Claim 7
Dependent Claim
17 words
An element as claimed in claim 1 wherein the catalyst material is selected from platinum and palladium.
Claim 8
Dependent Claim
12 words
An element is claimed in claim 1 wherein the alumina is gamma-alumina.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-11-30 | 1985-06-01 | 1985-12-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-11-30 | 1989-06-01 | 1989-12-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-11-30 | 1993-06-01 | 1993-12-01 | $7700.00 | Window Closed / Lapsed |