Which statement is true about the overall purpose of the three-way catalytic converter?

Which statement is true about the overall purpose of the three-way catalytic converter?

• A. It reduces NOx, HC, and CO emissions.
• B. It only reduces HC.
• C. It reduces NOx and HC only.
• D. It reduces HC and CO only.

Answer: (A)

The three-way catalytic converter is designed to tackle all three main gasoline exhaust pollutants at once: nitrogen oxides, unburned hydrocarbons, and carbon monoxide. It does this with a catalyst made of platinum and palladium that oxidizes hydrocarbons and carbon monoxide into carbon dioxide and water, and rhodium that reduces nitrogen oxides to nitrogen and oxygen. Because it can handle both oxidation and reduction in a single unit, it’s most effective when the engine operates near the stoichiometric air-fuel ratio, and the system uses feedback from the oxygen sensor to maintain that balance. When the engine runs too rich or too lean, the converter’s efficiency shifts and it won’t perfectly address every pollutant, but its designed function is to reduce all three simultaneously. This makes the chosen statement the best answer, since it reflects the converter’s overall purpose to lower NOx, HC, and CO emissions, rather than focusing on only one or two of them.

The three-way catalytic converter is designed to tackle all three main gasoline exhaust pollutants at once: nitrogen oxides, unburned hydrocarbons, and carbon monoxide. It does this with a catalyst made of platinum and palladium that oxidizes hydrocarbons and carbon monoxide into carbon dioxide and water, and rhodium that reduces nitrogen oxides to nitrogen and oxygen. Because it can handle both oxidation and reduction in a single unit, it’s most effective when the engine operates near the stoichiometric air-fuel ratio, and the system uses feedback from the oxygen sensor to maintain that balance. When the engine runs too rich or too lean, the converter’s efficiency shifts and it won’t perfectly address every pollutant, but its designed function is to reduce all three simultaneously. This makes the chosen statement the best answer, since it reflects the converter’s overall purpose to lower NOx, HC, and CO emissions, rather than focusing on only one or two of them.