Catalytic converters clean up car exhaust by burning any fuel that didn't get burned up properly in the engine. It's better to emit a little more carbon dioxide and water than to emit unburned or partially burned hydrocarbons, which turn into smog. The converters work by using the unique ability of certain precious metals, notably platinum, palladium, and rhodium, to catalyze the burning of hydrocarbons at temperatures below their normal ignition point.
The exhaust gas is passed through a ceramic honeycomb coated with fine particles of one or the other of the metals, cleaning it up and in the process heating the converter up to a fairly high temperature (which has the useful side effect of making it work better).
To be honest, I have no idea if this particular catalytic converter actually uses palladium rather than one of the other possible metals. I have it under palladium just because of the story about Ford's ill-fated attempt to stockpile palladium for use in their catalytic converters.
I decided to see if I could use this converter to catalytically burn propane from a propane torch. It worked. I started by pointing a lit plumbing torch at the ceramic unit from a new catalytic converter. After it was glowing red hot next to the flame, I turned the gas off long enough for the flame to go out, then quickly turned it back on. Sure enough the ceramic quickly turned red hot again, and depending on how I positioned the unlit torch, the glowing area grew and moved around. It was quite obviously burning the propane, even though there was absolutely no open flame. The fact that there was no smell of propane also confirmed that it was being consumed quite effectively.
To be perfectly clear: In the picture for this sample, the torch is not lit: It is simply sending out a stream of cold propane gas. The ceramic element is consuming the fuel catalytically. There's probably something really useful you could do with this effect.
Here's what the whole cartridge looks like. The converter contains two of these:
Source: Farm & Fleet
Contributor: Theodore Gray
Acquired: 26 April, 2003
Text Updated: 29 January, 2009