US4426262A
Expired / Lapsed
US
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Promotion of Pt-Ir catalytic electrodes with lead, tantalum, ruthenium and oxygen
Assignee: BASF Catalysts LLC
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Filing: 1982-04-29
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Granted: 1984-01-17
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Expires: 2002-04-29
Abstract
Abstract Platinum and iridium in catalytic electrodes for electrochemical uses is partially replaced with lead ruthenate-tantalum oxide composite. Electrodes are fabricated by first coating a film-forming metal substrate with a platinum-iridium composite undercoat, then overcoating with a composite containing lead, ruthenium, tantalum, platinum, iridium and oxygen. The most preferred anodes have a titanium substrate initially coated with approximately at least 2 gm/m 2 of 70:30 w /o Pt:Ir composite, followed by about 20 gm/m 2 of a composite having the nominal composition of 22.2 w /o Pb 2 Ru 2 O 6 ; 66.6 w /o Ta 2 O 5 ; 7.9 w /o Pt and 3.4 w /o Ir. The outer layer of the prepared anode contains from about 10 to about 16 w /o lead, from about 40 to about 65 w /o tantalum, from about 5 to about 7.5 w /o ruthenium, from about 6.0 to about 10 w /o platinum, from about 2.5 to about 5 w /o iridium, and from about 10 to about 20 w /o oxygen. These electrodes may be used in acidic, neutral or alkaline solutions. Typical uses include production of chlorine and chlorine compounds and electrowinning of metals, such as zinc.
Inventors
- 👤 Robert C. Langley
- 👤 Herbert Myers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 09:08
CPC Classifications
C; C25; C25B; C25B11/00; C25B11/04; C25B11/051; C25B11/073; C25B11/091; C25B11/093
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
55 words
An electrode having a valve metal substrate and a lead-tantalum-titanium-platinum iridium ruthenium-oxygen composite layer formed on said valve metal substrate, the composite layer having a platinum-iridium rich zone adjacent the substrate, the concentrations of platinum and iridium being higher in the platinum-iridium rich zone than throughout the rest of the lead-tantalum-titanium-platinum iridium ruthenium-oxygen composite layer.
Claim 2
Dependent Claim
55 words
An electrode having a valve metal substrate and a lead-tantalum-titanium-platinum iridium ruthenium-oxygen composite layer formed on said valve metal substrate, the composite layer having a platinum-iridium rich zone adjacent the substrate, the concentrations of platinum and iridium being higher in the platinum-iridium rich zone than throughout the rest of the lead-tantalum-titanium-platinum iridium ruthenium-oxygen composite layer.
Claim 3
Dependent Claim
50 words
An electrode having a valve metal substrate and a catalytic layer formed thereon, the catalytic layer having a platinim-iridium rich zone and a lead-ruthenium-tantalum-oxygen rich zone, the platinum-iridium rich zone being adjacent to the valve metal substrate and the lead-ruthenium-tantalum-oxygen rich zone being disposed exterior to the platinum iridium zone.
Claim 4
Dependent Claim
50 words
An electrode having a valve metal substrate and a catalytic layer formed thereon, the catalytic layer having a platinim-iridium rich zone and a lead-ruthenium-tantalum-oxygen rich zone, the platinum-iridium rich zone being adjacent to the valve metal substrate and the lead-ruthenium-tantalum-oxygen rich zone being disposed exterior to the platinum iridium zone.
Claim 5
Dependent Claim
43 words
The electrode of claim 2 wherein the lead-ruthenium-tantalum-oxygen rich zone containing from about 10 to about 16 w/o lead; from about 40 to about 65 w/o tantalum; from about 5 to about 7.5 w/o ruthenium; from about 10 to about 20 w/o oxygen.
Claim 6
Dependent Claim
223 words
The electrode of claim 2 wherein the catalytic layer is formed by the process comprising: (a) applying from about 2 to about 6 g/m 2 (calculated as metal) of an admixture of platinum-iridium compounds to the valve metal substrate, the platinum-iridium compound admixture consisting essentially of from about 20 to about 40 w/o thermally decomposable iridium compound, and from about 60 to 80 w/o thermally decomposable platinum compound (both calculated as metal) (b) firing the electrode at a temperature of from about 350° C. to about 550° C.; (c) then applying an admixture of lead-ruthenate and thermally decomposable tantalum and platinum group metal compounds, the admixture of lead ruthenate and thermally decomposable tantalum and platinum group metal compounds consisting essentially of: from about 20 to about 25 w/o lead ruthenate; from about 60 to about 75 w/o thermally decomposable tantalum compound from about 6 to about 11 w/o thermally decomposable platinum compound; and from about 2.5 to about 5 w/o thermally decomposable iridium compound (the respective percentage being calculated as lead ruthenate, tantalum oxide, platinum and iridium) (d) firing the electrode at a temperature of from about 350° to about 550° C., the total amount of lead ruthenate and thermally decomposable tantalum and platinum and iridium compounds applied being sufficient to result in a loading of at least about 10 g/m 2 .
Claim 7
Dependent Claim
11 words
The electrode of claim 4 wherein said valve metal is titanium.
Claim 8
Dependent Claim
11 words
The electrode of claim 2 wherein said valve metal is titanium.
Claim 9
Dependent Claim
19 words
The electrode of claim 2 wherein the total thickness of said catalytic layer is less than about 5 microns.
Claim 10
Independent Claim
63 words
A method of electrolyzing an aqueous halide salt solution, comprising passing an electrolysis current through the halide salt solution between an anode and a cathode, said anode comprising a valve metal substrate having a catalytic layer thereon, the catalytic layer having a platinum-iridium rich zone adjacent the valve metal substrate and a lead-ruthenium valve metal oxygen rich zone upon the platinum-iridium rich zone.
Claim 11
Independent Claim
63 words
A method of electrolyzing an aqueous halide salt solution, comprising passing an electrolysis current through the halide salt solution between an anode and a cathode, said anode comprising a valve metal substrate having a catalytic layer thereon, the catalytic layer having a platinum-iridium rich zone adjacent the valve metal substrate and a lead-ruthenium valve metal oxygen rich zone upon the platinum-iridium rich zone.
Claim 12
Dependent Claim
17 words
The method of claim 8 wherein the valve metal is titanium and said halide is a chloride.
Claim 13
Dependent Claim
40 words
The method of claim 9 wherein the electric current is passed through the chloride solution at a current density of between about 1 and 7 amp/in 2 , based on the geometric area of the catalytically-coated portion of the substrate.
Claim 14
Dependent Claim
21 words
The electrode of claim 1 wherein at least a portion of said lead-tantalum-titanium-platinum iridium ruthenium-oxygen composite is present as lead ruthenate.
Claim 15
Dependent Claim
26 words
The electrode of claim 2 wherein at least a portion of the lead, ruthenium and oxygen in said lead-ruthenium-tantalum-oxygen rich zone is present as lead ruthenate.
Claim 16
Dependent Claim
27 words
The electrode of claim 3 wherein at least a portion of the lead, ruthenium and oxygen in said lead-tantalum-ruthenium oxygen rich zone is present as lead ruthenate.
Claim 17
Dependent Claim
28 words
The method of claim 8 wherein at least a portion of the lead, ruthenium and oxygen in said lead-ruthenium valve metal-oxygen rich zone is present as lead ruthenate.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-01-16 | 1987-07-18 | 1988-01-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-01-16 | 1991-07-18 | 1992-01-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-01-16 | 1995-07-18 | 1996-01-17 | $7700.00 | Window Closed / Lapsed |