platinum, palladium, and rhodium.
http://auto.howstuffworks.com/catalytic-converter2.htm (http://auto.howstuffworks.com/catalytic-converter2.htm)
Actually, this is an interesting idea, because if it worked for hydrogenation, with rhodium, it could probably reduce aromatics to cyclic alkanes. Very handy.
Actually, it would be cool to put the beads in solution as CTH catalyst, easy to separate afterwards.