Catalytic converters cut down on toxic car emissions, and, according to the U.S. Environmental Protection Agency, they’re one of the greatest environmental inventions of all time. Today, catalytic converter theft is on the rise, and that’s partly because of their chemistry.
Video Transcript: If you turn on your car and it sounds like a lawnmower, 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.
