Palladium

[glasshopper]

[aftercolumbia]

Palladium is one of the catalysts that can trigger the Sabatier reaction:

4H2 + CO2 -> CH4 + 2H2O

It isn't as good as Ruthenium and Platinum at it though. It is mentioned in Tom Clancy's The Sum Of All Fears as a method to filter 3He from tritium. Several of the details of the book's homemade nuclear bomb were altered to prevent its information from being practically useful (as if that would do much good), but this is one I'm pretty sure let be. The palladium would absorb the tritium, but not the helium, and then you'd stick the palladium block in a vacuum oven and bake the tritium out.

Palladium is used in the Planck telescopes sorption cryocooler beds (I think its palladium, anyway.) This is used to cool Planck's infrared radiometers to low enough temperatures that they work properly while at the same time, are completely vibration free so they don't disturb the telescope.