Catalyst stolen? It’s the rhodium – a dreaded chemistry lesson from hell


Hey chemistry fans. It’s time to live the good life!. I know that an alarming number of you rely on the regular appearance of The dreaded chemistry lesson from hellTM Filling your otherwise empty life is probably a few days after the DTs because I haven’t done any in a while. So as a New York humanist (1) It’s only right that I stop producing a stream of boring chatter about COVID drugs and vaccines and go back to my roots as a chemist. It’s the least I can do to placate you Everyone both my faithful followers of chemistry. Today we are going to talk about rhodium – one of the rarest and most valuable of all elements.

Chances are you know someone, or at least have heard of someone who walks up to their car, pulls away and doesn’t handle it well, like it’s pulling a brontosaurus on a skateboard. What happened? There’s a pretty good chance your catalyst is gone. How stolen. Yes, someone stole the platinum, ripped off the rhodium, and poached the palladium. That is now very ordinary. Catalytic converter thefts increased by 325% from 2019 to 2020. Both performance and emissions suffer from the absence of this vital car component. Good luck passing an inspection without one.

The real reason dinosaurs went extinct. Photo credit: maxipixel, maxipixel, Wikimedia Commons,

A recycled catalytic converter from a car, stolen or not, can fetch anywhere from $150 to $250, but catalytic converters from trucks can be worth as much as $1,500. The value is derived from the rare metals required to operate the converter: palladium, rhodium and platinum. Most of you would probably guess that platinum is the most valuable of metals. It is not; it’s quite the opposite. The most valuable metal in a converter is (by far) rhodium; it is also the most valuable metal in the world. As of today (01/31/22) here are the Prices of selected precious metals (per ounce)

  • Silver – $22
  • Platinum – $1,019
  • Gold – $1,796
  • Palladium – $2,437
  • Rhodium – $16,850

Source: money metals

What is special about rhodium that makes it so valuable? To answer that question, it’s time for…

But first since they are mine DCLFH Hosts for years, it’s time to give Steve and Irving some credit for their service. Maybe you get to know her a little bit? How did they end up in such a horrible place? Here are their stories:

How Steve and Irving became your hosts for the Dreaded Chemistry Lesson From Hell.

Steve was a Reno blackjack dealer cursed with poor impulse control and an outrageous temper. During one night shift, he was in a particularly bad mood when a woman at his table said, “Hit me,” and he did just that. Unfortunately, the woman was the wife of a beloved local pastor, which years later caused Steve an elevator ride in headed into the hot zone when he was run over by a 92-year-old narcoleptic Uber driver in the casino parking lot. Irving, a feisty New York City deli executive, secured his spot at the perennial broiler when his wife asked if he would mind if she hosted an Amway event in their 500-square-foot studio apartment in Queens, and he replied, “I’d rather burn in hell.” Irving apparently complied.

Now let’s get to the rhodium chemistry lesson!

Facts about Rhodium:

  1. rhodium is very Rarely. Of the 78 elements found in the earth’s crust, Rh is #77only ahead of osmium, which is in last place.
  2. Rhodium is a noble metal, meaning it is chemically inert, like gold and platinum. Therefore, any tiny amount of rhodium found on earth (1 part in 200 million) is found as the metal itself and not as a chemical compound. But there is a very rare mineral, Rhodplumsite, which is a complex of rhodium, lead, and sulfur with the rather odd chemical formula Rh3pb2S2.

(Left) A 78 gram cube of rhodium is worth $1.3 million. (Right) A sample of Rhodplumsite looks unremarkable but is valuable. Photos: Wikipedia, at least

3. Rhodium’s inert properties make it suitable for use in exhaust systems. Metals such as rhodium, platinum and palladium are not used for nothing. More common metals such as iron, aluminum or copper are more chemically reactive and would quickly oxidize (and decompose) under the conditions required to clean gasoline exhaust fumes – a temperature of around 600°F.

4. Speaking of oxidation, this is one of the two chemical reactions that these metal catalysts perform (1) support financially:

Rhodium is responsible for this to reduce (deprivation of oxygen) from nitrous oxide pollutants such as nitrous oxide, which cause smog and acid rain.

NOx + Rh Catalyst ——-> N2 + O2 (a reduction reaction)

Platinum and palladium are responsible for promoting oxidation reactions that neutralize pollutants carbon monoxide and unburned hydrocarbons such as methane.

CO+O2 + Pt/Pd catalyst ——-> CO2

CH4 + O2 + Pt/Pd catalyst ——-> H2O + CO2

In this way, some rather unpleasant pollutants are converted into non-toxic gases. It works out.

5. Rhodium is badass, even more so than gold or platinum

There is noble and there is noble. All three metals are chemically inert, but gold and platinum have one notable weakness. They can boil both metals in nitric acid (nearly nothing in the world will survive that) and they sit there laughing. But if you add hydrochloric acid, you get a terrible concoction called aqua regia (Latin for “Royal Water”) they no longer laugh. Aqua regia also dissolves platinum and gold. But it doesn’t touch rhodium.

6. Rhodium forms some crazy looking complexes with organic molecules. Here’s one of them.

Image: Wikipedia

I don’t know (or care) what it’s used for, but the image is interesting. Maybe a helicopter propeller? Feel free to make a guess.

What to do to protect your catalytic converter in New York?

If you’re parking on the street in NYC – a form of torture unparalleled in modern society – there’s not much you can do. A thief just crawls under your car and cuts it off. The current leadership in the city is considering how to proceed treat armed robbery as a misdemeanor a joker under a car with a saw is unlikely to draw much attention.

Or you could get robbed by garages (about $800/month per car in Manhattan) and protect the converter (3). Which one is worse? The math here is beyond my feeble ability.

Or you leave the car and ride a bike. But the probability that the bike will be stolen varies between 100% and 100%. It used to be fine to get a heavy duty lock and bolt the bike to a tall street sign. No longer.

Bike thieves in NYC have learned to detach the sign from the top of the pole. Then they lift the bike over the empty bar. Pretty smart if you ask me. Photos: EVGrieve

Let’s wrap this up. I have more nonsense to write and Steve and Irving are gearing up for their next DCLFH® solo performance. Also, they’re both on HVAC duty tonight. In hell. Might be some technical challenges.


(1) A New York humanist is defined as someone who pushes an elderly person in a wheelchair across a busy street. On the half way.

(2) ACSH friend Dr. Joe Schwarcz, director of McGill University’s Office for Science and Society, made a very nice YouTube video about catalysts. You can view it here. OSS has a virtually identical mission to ACSH – “separate sense from nonsense”.

(3) When my brother Billy lived in Manhattan, he had to store his car. I naively asked him how safe it was to leave your belongings in the car. He replied, “They’re going to steal a wrapper of gum.”


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