You can freely build on How Eugene Houdry Invented the Modern Catalytic Converter
This patent expired in 1973. Every claim — 1 independent, 0 dependent — is now unenforceable. Anyone can use, reproduce, manufacture, sell, or offer for sale this technology without a license.
Original assignee
Oxy Catalyst Inc
Patent granted
1956
Expired
1973
Forward citations
55
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.
What is now free to use
All 1 claims of US 2742437 are in the public domain. Specifically:
Claim 1: A CATALYTIC STRUCTURE — 1 specific element
The 0 dependent claims add narrowing limitations and are also free.
What is NOT covered
Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.
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
Who is building on this today
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.
Products built on expired version of this technology
Automotive catalytic converters
Industrial emission control systems
Air purification units for factories
How to cite this patent in your documentation
Oxy Catalyst Inc. US Patent 2742437. Catalytic structure and composition. Granted 1956, expired 1973. Now in the public domain.
Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.
PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.