It was the brainchild of two chemical engineers, John Mooney and his boss, Carl Keith, as well as a small team of their colleagues at Engelhard Corp.
Mooney, who died June 16 at home in Wyckoff, N.J., at age 90, was credited with the big breakthrough.
Catalytic converter development began in the 1950s, spurred by federal regulations that mandated lead-free gasoline, which hampered and, in some cases, disintegrated antipollution devices. The three-way converter was a major advance over the oxidizing converter, which General Motors patented and began installing in vehicles in 1974.
Early catalytic converters developed by Mooney and Keith cut carbon monoxide and hydrocarbon emissions, but the Clean Air Act of 1970 imposed new limits on another pollutant, nitrogen oxide.
Mooney and Keith, who died in 2008 at 88, worked with colleagues Antonio Eleazar and Phillip Messina and successfully experimented on a 1973 Volvo station wagon to create a three-way catalytic converter that reduced all three pollutants.
The device they created — a ceramic honeycomb coated with various oxides, platinum and rhodium using a single catalyst bed — was introduced on assembly lines in 1976.
The chemical reactions required to clear a light vehicle's most noxious and harmful pollutants are different. Oxygen has to be stripped away from nitrous oxide but must be added to carbon monoxide and unburned hydrocarbons. Most engineers determined the solution for cleaner light-vehicle emissions would require a bulky, two-stage system.
Mooney thought he could tackle the problem in one step and hoped to prove it by doing something unexpected, he recalled in a 2013 interview with Seton Hall Magazine.
Rather than look at the exhaust, he focused on the gasoline piped into the engine. If it was mixed with the right amount of air, the exhaust would offer a one-stage converter and just enough oxygen to simultaneously render the three pollutants harmless.