Energy & Industry / Transport & Mobility

Catalytic Converter

From the 1975 model year US cars carry platinum-metal catalysts in the exhaust; three-way converters with engine control (1977-81) help make new cars roughly 99% cleaner than in 1970.

Eugene Houdry patented converters for petrol engines in the 1950s; after the US Clean Air Act of 1970 set limits, Engelhard engineers including Carl Keith and John Mooney built the first production converter in 1973, and most US petrol cars had one from the 1975 model year. Lead destroys the catalyst, so leaded petrol had to go; the US banned it fully after 1995. Volvo was first with a three-way converter in 1977, and nearly all makers used one with engine control from 1981; the EU required converters on new petrol cars from 1993. The EPA puts today's cars, SUVs and pickups at roughly 99% cleaner than 1970 models for common pollutants, a result of converters together with fuel injection and engine computers.