A catalyst is a material that makes a chemical reaction happen easily. In a catalytic converter, precious metals are the catalyst, and their function is to make dangerous things in the exhaust break down into safer things before being released out the tailpipe.
Most of a catalytic converter’s value is the scrap value of the precious metals in the catalyst – platinum, palladium, and rhodium. They’re valuable because they’re rare, resistant to corrosion, and make really good catalysts for all sorts of processes.
TLDR: There’s a few hundred dollars worth of platinum in there.
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