Three-way catalyst design - GF49.10-P-3002-02AM
Body (schematic)
Ceramic monoliths are ceramic bodies through which pass several thousand small passages. The exhaust gas flows through these passages. The ceramic consists of high temperature-resistant magnesium aluminum silicate.
The monolith, which is extremely sensitive to voltages, is embedded in an elastic wire mesh made of high-alloy steel wires and fitted in a double-walled stainless steel housing.
Ceramic monoliths require a substrate (washcoat) of aluminum oxide (Al2 O3 ) that expands the active surface of the catalytic converter by an approximate factor of 7000.
The active catalytic layer coated on the substrate is available in three-way catalysts primarily out of platinum and rhodium. Platinum accelerates the oxidation of hydrocarbons (HC) and carbon monoxide (CO), whereas rhodium accelerates the reduction of nitrogen oxide (NOx ).
The stainless steel content in a three way catalytic converter is approximately 3 g.