What is the correct description of oxidizing, reducing, dual-bed, and three-way catalytic converters?

• A. Three-way and dual-bed converters are both oxidizing and reducing.
• B. All are exclusively oxidizing.
• C. All are exclusively reducing.
• D. They are not catalytic converters.

Answer: (A)

Catalytic converters work by using catalysts to speed up reactions that neutralize exhaust pollutants. An oxidizing catalyst promotes the conversion of carbon monoxide and hydrocarbons into carbon dioxide and water. A reducing catalyst promotes the conversion of nitrogen oxides into nitrogen and oxygen. A dual-bed converter physically places both types in separate sections, so the exhaust passes through oxidation-friendly material and then through reduction-friendly material, delivering both cleanup actions. A three-way catalyst handles both oxidation and reduction within the same substrate, but it relies on the engine operating near the stoichiometric air–fuel ratio to balance the available oxygen for these opposing reactions. Because of this, three-way and dual-bed configurations are described as capable of both oxidizing and reducing, which is why that option is the best description.