text: what is a three way catalyst?   normally it referes to a three way catalitic converter, a device used in cars for pollution control.  a three-way catalytic converter has three simultaneous tasks: reduction of nitrogen oxides to nitrogen and oxygen: 2nox → o2 + n2 oxidation of carbon monoxide to carbon dioxide: 2co + o2 → 2co2 oxidation of unburnt non-methane hydrocarbons (hc) to carbon dioxide and water: cxhy + no2 → xco2 + mh2o