Its spelled Palladium, and the main ingredient in oxidation catcons is platinum anyway. And they haven't used beads in catalysts since 1980.
act as a catylist to convert pollutants to, uh, less
Reduction cats convert nitrogen oxides to nitrogen (N2) and free oxygen (O2). Oxidation catcons convert Carbon Monoxide and un-burned hydrocarbons to carbon dioxide and water. Oxidation catcons need free oxygen to work, and that's what air injection pumps are for. But with better fuel management systems like we have today, the free oxygen released by the reduction section of the cat is usually enough to fuel the oxidation section of the cat. Kinda neat, that.