# 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. - **Patent:** US 2742437 - **Original title:** Catalytic structure and composition - **Owner:** Oxy Catalyst Inc - **Granted:** 1956 - **Status:** Public domain (expired) - **Times cited:** 55 - **Field:** automotive, mechanical, energy ## What it does 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 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 ## 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. ## Real-world examples 1. Automotive catalytic converters 2. Industrial emission control systems 3. Air purification units for factories ## Why it matters 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. ## 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 **Full plain-English explainer:** https://patentbrief.org/patent/us/2742437/catalytic-converter-houdry **Original patent:** https://patents.google.com/patent/US2742437 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How Alfred Nobel Stabilized Nitroglycerin with Dynamite](https://patentbrief.org/patent/us/78317/dynamite-nobel) — Alfred Nobel's 1868 patent for dynamite, which made the volatile liquid explosive nitroglycerin safe to handle by mixing it with an absorbent material. - [How Early Vehicle Airbag Safety Systems Work](https://patentbrief.org/patent/us/3552770/automotive-airbag-safety-device) — A 1968 patent describing an early vehicle safety system that uses a rapidly inflating confinement to protect passengers during a collision. - [Robert Goddard's Early Design for Liquid-Fueled Rocket Engines](https://patentbrief.org/patent/us/1102653/liquid-fuel-rocket-goddard) — A foundational 1914 patent by Robert Goddard detailing the basic mechanical structure of a rocket engine using liquid fuel. - [How William Burton Invented Modern Gasoline Refining](https://patentbrief.org/patent/us/1049667/petroleum-cracking-burton) — A 1913 patent by William Burton that describes a thermal cracking process to turn heavy crude oil into usable gasoline for automobiles. - [How Joseph-Armand Bombardier Designed the Modern Snowmobile](https://patentbrief.org/patent/us/3023824/snowmobile-bombardier) — A 1962 patent by Joseph-Armand Bombardier describing a lightweight, engine-driven vehicle using an endless track system for travel over snow.