Catalytic Converter: Description and Operation

Three Way Converter Cutaway:

Exhaust System:

Purpose
The purpose of three-way catalytic converters is to neutralize carbon monoxide, hydrocarbons and oxides of nitrogen in the exhaust gases. This is achieved by converting carbon monoxide and hydrocarbons to carbon dioxide and water. Oxides of nitrogen are converted to nitrogen and water.

Operation
This chemical conversion is caused by the platinum and rhodium metals in the converter. The exhaust gases are forced by these noble metals in the converter, inducing the chemical reaction. The noble metal content is about two grams.

Operating Temperature
The effective conversion of pollutants begins at an operating temperature of about 250°C (450°F). The ideal operating temperature is 400°C-800°C (750°F-1500°F). Engine malfunctions such as misfires can cause the temperature of the converter to increase to more than 1400°C (2500°F). Such temperatures lead to the complete destruction of the converter through the melting of the substrate material.

Cautions
Using leaded fuel will damage the converter and quickly render it ineffective by coating the noble metals with lead deposits.