A friend wears a T-shirt that says: “She who must be obeyed.”
If catalytic converters wore T-shirts, it would be that one. This is because all of the other stuff, from the simplest sensor to the most complex computer, is there to serve the converter.
The catalytic converter, or “cat,” is a marvelous, magical thing. It has no moving parts and no electronics and hangs out with other exhaust plumbing, yet it is the heart of emission control. In California, cats are being installed on motorcycles.
Since they were introduced in the 1970s, they have changed little compared with many automotive components. The cat’s job is much the same today as it was back then. It takes the nasty stuff spewing from the engine and converts it to harmless stuff before it exits the tailpipe.
How does the magic cat work? Here comes the chemistry lesson, but we won’t be hurt if you skip ahead.
A catalyst promotes a chemical reaction without being affected by the reaction.
The two baddest exhaust emissions are carbon monoxide (CO) from incomplete combustion and hydrocarbon compounds (HC) from unburned fuel. CO and HC can change into harmless chemicals by adding oxygen to them. Adding oxygen (O (-2) ) to CO makes carbon dioxide (CO (-2) ). Adding oxygen to HCs turns them into water (H (-2) O) and carbon dioxide (CO (-2) ). This was all the early catalytic converters did. The catalysts are platinum and palladium.
As the emission standards were tightened to include oxides of nitrogen (NOx), a different reaction was required to separate the oxygen from the nitrogen. Removing oxygen is called a reduction reaction. In this case, the NOx compounds are separated into their components, nitrogen (N) and oxygen (O
