SAE International considers it among the top inventions since the dawn of the automobile. The EPA says it has saved thousands of lives and prevented hundreds of thousands of throat and lung ailments. In California, it is responsible for abating much of the yellow air, first studied in the 1950s, that has hovered over the greater Los Angeles basin for decades.
The modern catalytic converter, which scrubs smog- and soot-producing hydrocarbons, carbon monoxide and nitrogen oxides from automobile exhausts, has revolutionized air pollution controls with its invention in the 1970s.
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, is credited with the big breakthrough.
Catalytic converter development began in the '50s, was 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 oxides.
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.
Keith later sent Mooney around the world with an assignment: Convince automakers to add an oxygen sensor to their engines. The sensor would monitor fuel-to-air ratios so each engine could be tuned to optimize where Mooney's one-stage converter would engage.
"It was a challenging experience," Mooney said in a 2001 interview with New Jersey's The Record newspaper. "You had to look at things inside and out and upside down. Nothing ever flowed perfectly."
He later called his discovery — widely used today in wood stoves, leaf blowers, chain saws and weed trimmers, in addition to millions of cars, light trucks and motorcycles worldwide — pure magic.
"No one really believed me," he told Seton Hall. "Probably our competitors didn't either."