Cleaner Air? Thank Platinum
Did you know that platinum helps combat air pollution? It’s all due to a simple yet complex invention called a catalytic converter. This small part of your vehicle’s emissions system does an enormous job, converting dangerous emissions gases into harmless ones. And it’s all done with the help of our favorite metal—platinum.
Each year, the production of catalytic converters uses more platinum than the manufacture of bridal jewelry. As a matter of fact, the majority of pure platinum mined from the earth each year is put to use in the auto industry. Since 1979, according to the United States Geological Survey (USGS), the largest consumer of platinum group metals is the automotive industry. Catalytic converters have been required on all new vehicles manufactured in the United States since 1975.
Today’s catalytic converter may look like an ordinary small metal box, but there’s an amazing chemical reaction that takes place just below its surface to control emissions. Platinum, rhodium and palladium are metal catalysts—meaning, they cause or accelerate a chemical reaction. The internal parts of the converter are coated with platinum (or a combination of platinum catalyst metals—platinum, palladium and rhodium). As hot air from the engine flows over the metals, over 90 percent of hydrocarbons, carbon monoxide and nitrogen oxides are turned into water vapor, carbon dioxide and nitrogen.
According to howstuffworks.com, most of today’s vehicles use three-way catalytic converters. The first stage of the converter occurs with the reduction catalyst, where platinum and rhodium help to reduce nitrous oxide emissions. The second stage utilizes platinum and palladium as oxidation catalysts to reduce unburned hydrocarbons and carbon monoxide. The third conversion stage monitors the exhaust of the vehicle, controlling the fuel injection system and continuously checking the overall quality of the vapors released back into the atmosphere.
The novel idea for using platinum to turn sooty emissions into water vapor came from a French-born chemical engineer by the name of Eugene Houdry. According to Tim Palucka in American Heritage (Winter 2004), Houdry never lived to see his invention change the nation’s air quality, but he would not have been surprised that it succeeded. In the 1930s, Houdry had developed a process responsible for creating automotive fuels more efficiently. After moving to Los Angeles and seeing the atmosphere sullied by pollutants, Houdry began work on an invention that would reduce the damage caused by gasoline. His U.S. patent for the first known catalytic converter was awarded in 1962, the year of his death. But it wasn’t until the passage of the Clean Air Act of 1970, that a comprehensive effort to limit vehicle emissions truly began in earnest. Engelhard Industries, 3M and Corning Glass all contributed to the effort, which produced the forerunner of the product that all U.S. vehicles use today.
So the next time you go out for a drive on a sunny, clear day, you can thank platinum—along with the ingenious inventors who saw a problem and were determined to find a solution.