How Eugene Houdry Invented the Modern Catalytic Converter
A 1952 patent for a durable, thin-film catalyst structure that allows gases to flow freely over reactive surfaces, forming the foundation for modern vehicle exhaust systems.
Original patent title: “Catalytic structure and composition”
A 1952 patent for a durable, thin-film catalyst structure that allows gases to flow freely over reactive surfaces, forming the foundation for modern vehicle exhaust systems. Granted to Oxy Catalyst Inc in 1956 with 2 claims and 55 forward citations, and it is now in the public domain.
Coverage
What does this patent actually cover?
The patent describes a rigid, inert support structure shaped to fit inside a reaction chamber, such as an exhaust pipe. A thin, tightly adherent film of metal oxide is applied only to the outside of this support, with a thickness between 0.0005 and 0.015 inches. This film is then impregnated with finely divided active metal particles. By keeping the film on the surface and ensuring the structure is shaped to avoid contact with neighboring surfaces, the design maximizes the exposure of exhaust gases to the catalyst while maintaining structural integrity.
The gap
What does this patent NOT cover?
- Does not cover catalysts where the active material is mixed throughout the entire body of the support rather than just the surface film
- Does not cover catalytic structures where the active film is thicker than 0.015 inches or thinner than 0.0005 inches
- Does not cover systems where the catalytic surface is in direct contact with other surfaces that would block gas flow
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
Instead of wasting expensive catalytic material by packing it deep inside a solid block, Houdry realized you only need a microscopic, superficial film on the surface to achieve the same chemical reaction, provided the support remains physically strong.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Automotive catalytic converters
Industrial emission control systems
Air purification units for factories
Why it matters
The bigger picture
Eugene Houdry was a pioneer in catalytic science. This specific design enabled the practical use of catalysts in high-flow environments like automobile exhaust systems, which eventually became a standard requirement for reducing smog and toxic emissions globally.
Filed
September 29, 1952
Granted
April 17, 1956
Market context
Who's building on this
Companies in this space
Major automotive suppliers like BASF, Johnson Matthey, and Umicore continue to refine the surface chemistry and substrate geometry of catalytic converters. Houdry's foundational work on surface-active films remains the standard approach for these components.
Market impact
This patent helped move catalytic technology from laboratory theory to mass-market industrial application. It enabled the development of effective emission control systems that have been legally mandated in most countries, fundamentally changing the environmental impact of the internal combustion engine.
Claim 1 — Plain English
What this patent covers
The patent describes a rigid, inert support structure shaped to fit inside a reaction chamber, such as an exhaust pipe. A thin, tightly adherent film of metal oxide is applied only to the outside of this support, with a thickness between 0.0005 and 0.015 inches. This film is then impregnated with finely divided active metal particles. By keeping the film on the surface and ensuring the structure is shaped to avoid contact with neighboring surfaces, the design maximizes the exposure of exhaust gases to the catalyst while maintaining structural integrity.
The clever bit
Instead of wasting expensive catalytic material by packing it deep inside a solid block, Houdry realized you only need a microscopic, superficial film on the surface to achieve the same chemical reaction, provided the support remains physically strong.
What it does not cover
- Does not cover catalysts where the active material is mixed throughout the entire body of the support rather than just the surface film
- Does not cover catalytic structures where the active film is thicker than 0.015 inches or thinner than 0.0005 inches
- Does not cover systems where the catalytic surface is in direct contact with other surfaces that would block gas flow
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
This patent is in the public domain
See the Freedom to Build guide — what is free to use, what is not, and how to cite this patent.
PatentBrief Score
Impact Score
Early stage
Citation count
35/40
Highly cited
Claim breadth
1/20
Narrow claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$19K – $62K
Midpoint $39K · expired or expiring · industry ×0.9
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Patent Claims
1 independent claim · 0 dependent
Claims are the legal boundaries of the patent. An independent claim stands alone. A dependent claim adds limitations to its parent, narrowing — but not broadening — the scope.
The original legal language
Original claims
2 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Houdry, E. J. (1956). How Eugene Houdry Invented the Modern Catalytic Converter (U.S. Patent No. 2,742,437). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/2742437/catalytic-converter-houdry
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Eugene Houdry Invented the Modern Catalytic Converter cover?
A 1952 patent for a durable, thin-film catalyst structure that allows gases to flow freely over reactive surfaces, forming the foundation for modern vehicle exhaust systems.
Who owns patent US 2742437?
Oxy Catalyst Inc owns this patent, granted in 1956.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 2742437 cited by?
This patent has been cited by 55 later patents that build on its ideas.
What problem does this patent solve?
Eugene Houdry was a pioneer in catalytic science. This specific design enabled the practical use of catalysts in high-flow environments like automobile exhaust systems, which eventually became a standard requirement for reducing smog and toxic emissions globally.
What does this patent NOT cover?
Does not cover catalysts where the active material is mixed throughout the entire body of the support rather than just the surface film
Patent monitoring