The Catalytic Converter

Development Overseen by Robert C. Stempel, Class of 1955

Stempel has enjoyed a lifelong fascination with cars. He worked in a garage in Bloomfield, N.J., to earn money for college and fixed cars for students while he attended WPI. After graduation, his ambition was to land a job with the world's biggest automaker, General Motors. He started as a design engineer and went on to develop the front suspension and transmission of the 1966 Oldsmobile Toronado, the first American front-wheel drive automobile of the postwar era. His design for the system that joined the transmission to the front axle is considered a major engineering achievement.

In 1973, as special assistant to GM's president, Stempel was asked to oversee the development of a technology that would enable GM cars to meet strict new air pollution regulations. Their solution was the first practical catalytic converter system for production automobiles. A catalytic converter promotes the reaction of exhaust gases through a dense honeycomb coated with such precious metals as platinum, palladium and rhodium. In a complex chemical process, the catalysts convert nitrous oxides, carbon monoxide and unburned hydrocarbons into nitrogen gas, carbon dioxide and water.

In developing its system, GM built on extensive work on catalytic converters and catalyst done by other scientists and engineers at universities and in industry, including pioneering work done at Oxycatalyst Inc and Corning Inc. The work of the GM team focused on a number of innovations required to permit catalytic converters to work effectively in the harsh automotive environment and to enable them to reduce exhaust emissions over the life of a car. These included a special stainless steel to contain the catalyst and baffles that directed the exhaust flow over and through the catalyst for maximum exhaust cleanup. Knowing that the lead in leaded gas would render the catalysts inoperative, GM began working with refiners in 1971 to develop unleaded gasolines.

Catalytic converters are now included in virtually every car sold in the United States. With hundreds of millions of the devices in use since 1975, millions of tons of hydrocarbons and carbon monoxide have been eliminated from the atmosphere and airborne lead particulates have been virtually eliminated as pollutants

Stempel also participated in the development of the positive crankcase valve (PCV), which reduces unburned hydrocarbons in exhaust by 30 percent. He went on to become General Motor's youngest president, in 1987, and was named chairman three years later. In that capacity he oversaw the development of GM's first solar-powered car and its first electric vehicle. Today he is chairman of Energy Conversion Devices in Troy, Michigan, which, among other products, makes advanced nickel-metal hydride batteries for electric vehicles and advanced fuel cells-technologies that will enable vehicles to produce no harmful emissions at all.

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