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Catalytic Converter | The Science of Precious Metals

car traffic and emissions
As cars sit in traffic, fuel use and emissions increase.

Our automobiles produce emissions that are harmful to both humans and the environment.  An automobile engine is powered by burning a mixture of air and gasoline.  When this mixture burns, combustion by-products, including nitrogen oxides, carbon monoxide, and hydrocarbons, are produced.  These gases pass from the engine to the car’s exhaust system and into the atmosphere via the car’s tailpipe.  

 

Nitrogen oxides and hydrocarbons are responsible for smog.  Nitrogen oxides also contribute to acid rain.  Carbon monoxide is dangerous for people with heart disease because it affects the body’s ability to carry oxygen.

 

catalytic converter
Catalytic converters have been installed in fuel burning vehicles since 1975. Photo courtesy of Meridian Auto Parts.

In the U.S., tailpipe emissions have been reduced by the installation of catalytic converters.  Catalytic converters were first introduced in automobiles in 1975, and they are now also regularly used in trucks, buses, trains, mining equipment, forklifts, and generators.

 

car tailpipe catalytic converter
The exhaust from car tailpipes are cleaned up by catalytic converters.

Catalytic converters work by converting the tailpipe pollutants into less harmful chemicals.  They require platinum, palladium, and rhodium as catalysts.  Platinum and rhodium are used to reduce nitrogen oxides to nitrogen and oxygen.  Platinum and palladium are used to oxidize carbon monoxide and carcinogenic hydrocarbons to a less harmful greenhouse gas (CO2) and water.  

 

Although catalytic converters have been beneficial for the environment, they are not a complete panacea.  They have reduced smog and other toxic emissions, but they require engines to run at less than optimal fuel efficiencies.  As a result, more fuel is consumed and more emissions are released.  They also contribute to the greenhouse effect by releasing nitrous oxide into the atmosphere.

 

Next, learn about Combining Jewelry Manufacturing Methods | Precious Metals in Jewelry.

 

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