If you turn on your car and it sounds like a lawn mower,
congratulations! Your catalytic converter has been stolen.
Apparently that's been happening to a lot of people lately.
[RYAN] I got in the car and turned it on and it sounded like I was starting up a drag car.
[JEAN] There was this horrendous roar, like i was at a speedway, no muffler. I called my mechanic
and he said, they stole your catalytic converter. That's all I had to tell him, and he knew.
[RYAN] I called a mechanic that was right down the street, just a few blocks away,
and I told them about it and they were like,
oh, that's the catalytic converter, we've gotten three of those this week.
[SAM] Catalytic converters were first introduced on a large scale in the 1970s in the US,
where air pollution was becoming a huge issue. They cut down on most toxic car
emissions by 99 percent, and according to the US Environmental Protection Agency they're one
of the greatest environmental inventions of all time. So why are they being stolen?
To really understand why catalytic converters are being stolen we need to start at the beginning,
with the engine. When you drive your engine burns the gasoline to produce the energy that
moves your car, and the gasoline that it burns is mostly just different types of hydrocarbons. In
a perfect world those hydrocarbons would combust completely, so they'd combine with oxygen to form
carbon dioxide and water vapor, nothing else. But in the real world gasoline doesn't combust
perfectly, and incomplete combustion can leave you with toxic gases like carbon monoxide and
nitrogen oxides coming out your tailpipe. And there used to be no regulation for that. Oh,
the air is filled with carbon monoxide? Suck it up, weaklings. But then in 1970 the Clean Air
Act allowed the EPA to regulate air pollution. That's where the catalytic converter came in.
It is right here, between the engine, and the muffler. Catalytic converters quickly became
a very effective way of cutting down on that air pollution. But what makes them so effective? They
use transition metals, specifically combinations of platinum, palladium, and rhodium. These metals
are great at giving up and taking back electrons, which makes them good catalysts. That means they
can speed up reactions in other molecules without changing themselves. When the toxic fumes from
incomplete combustion in your engine make their way to the catalytic converter, they first reach
platinum and rhodium. In this case platinum and rhodium are speeding up a reduction reaction.
In a reduction reaction a compound loses oxygen atoms and/or gains electrons. Platinum and rhodium
reduce the toxic nitrogen oxide compounds by pulling off their oxygen atoms, which are
then released as oxygen gas. Then the remaining nitrogen atoms react with each other and nitrogen
gas is released. So we went from toxic nitrogen dioxide or nitric oxide to harmless nitrogen gas
and oxygen gas. Next platinum and palladium speed up an oxidation reaction. An oxidation reaction is
the opposite of a reduction reaction, a compound gains oxygen atoms and or loses electrons.
Platinum and palladium gather up oxygens and use them to oxidize leftover gasoline hydrocarbons
and carbon monoxide, producing mostly carbon dioxide and water. So why are people stealing
catalytic converters? Over the last few decades more and more countries have been enacting
stricter and stricter emission standards, so there's more demand for catalytic converters,
which means there's more demand for their metals. Platinum, palladium, and rhodium are all extremely
rare, so their prices have gone way up. On top of that they're also used in a lot of electronics,
which boosts demand even more. Rhodium was about 600 bucks per ounce five years ago. Today it's
over 21,000 dollars per ounce, which is 10 times the price of gold. And one catalytic converter
has about 400 dollars worth of rhodium in it. So people are cutting catalytic converters out
of cars and selling them for scrap. Some states are trying to really tightly regulate scrap metal
sales to hopefully cut down on catalytic converter theft. There are also researchers looking at less
expensive metals for catalytic converters which could help a lot. Catalytic converters are really
important, but they're not perfect. Our cars are still releasing CO2 into the atmosphere,
and catalytic converters are releasing little bits of platinum, palladium, and rhodium, which could
be bad for us and other animals. Unfortunately there's still no silver bullet for solving all our
car emission problems. If you're burning gasoline, you're just gonna have emissions. Our PBS friends
across YouTube are celebrating Earth Day. Follow me over to Eons to learn the story of earth's
little ice age, and tell them Reactions sent you. One more thing, for those of you in the US,
you should check out Greta Thunberg: A Year to Change the World, a new three-hour Earth
Day broadcast event on your local PBS station. This special is going to premiere on Thursday,
April 22nd at 8, 7 central, and then will repeat starting Wednesday, April 28th at 8, 7 central.