In the reduction stage of a three-way catalytic converter, what is the product of NOx after the reaction?

• A. Converts hydrocarbons to water
• B. Oxidizes carbon monoxide to carbon dioxide
• C. Reduces NOx to nitrogen and oxygen
• D. Filters particulates

Answer: (C)

In the reduction stage of a three-way catalytic converter, NOx is chemically reduced by the reducing agents in exhaust (like CO and hydrocarbons). This process breaks the nitrogen-oxygen bonds and turns NOx into nitrogen gas, with the accompanying oxygen being tied up in oxidizing CO and hydrocarbons to CO2 and H2O elsewhere on the catalyst. So the product of NOx after the reaction is nitrogen and oxygen. The other options describe oxidation of hydrocarbons or carbon monoxide, or particulate filtration, which aren’t the direct products of NOx reduction.