Catalytic converter

The catalytic converter emerged because Eugene Houdry saw Los Angeles smog and understood its source. Around 1950, early studies linked automobile exhaust to air pollution. Houdry—the French-born engineer who had invented catalytic cracking in the 1930s, providing high-octane aviation fuel that helped win World War II—founded Oxy-Catalyst to develop catalytic converters for gasoline engines.

The adjacent possible aligned through Houdry's mastery of catalysis. His refining process used catalysts to break heavy petroleum molecules into lighter ones, producing more and better gasoline from crude oil. The same principle could work in reverse: catalysts could speed the oxidation of exhaust pollutants, converting carbon monoxide and unburned hydrocarbons into carbon dioxide and water.

Houdry first developed catalytic converters for industrial smokestacks, then for warehouse forklifts running on unleaded gasoline. In the mid-1950s, he began research on automobile applications and received United States Patent 2,742,437. His solution was elegant: a metal casing whose insides were coated with platinum catalyst, which accelerated the oxidation of exhaust gases.

But a chemistry problem blocked adoption. Tetraethyl lead, introduced in the 1920s to boost octane levels, poisoned any catalyst. The lead coated platinum surfaces, preventing exhaust gases from contacting the metal. Houdry's automotive converters couldn't work with leaded gasoline—and leaded gasoline was universal. He shifted focus to industrial applications and indoor forklifts, where unleaded fuel was already used.

Houdry died in 1962, never seeing his invention's triumph. The Clean Air Act of 1970 created air-quality standards that made catalytic converters essential. The EPA required them on all gasoline vehicles starting with the 1975 model year. This mandate simultaneously forced the elimination of leaded gasoline—solving the catalyst-poisoning problem Houdry couldn't overcome in his lifetime.

Today, catalytic converters are mandatory on virtually every internal combustion vehicle worldwide. They typically use platinum, palladium, and rhodium as catalysts—precious metals whose theft from parked cars has become a significant crime. The device Houdry invented to clean Los Angeles air became a core component of every vehicle's exhaust system, reducing automotive emissions by over 90%.