Three-Way Catalytic Converter, Design

Three-way Catalytic Converter, Design




1 Substrate
4 Coating

The three way catalytic converter consists of a double-walled (insulation) stainless steel housing and the substrate (ceramic monolith) with the actual catalytic layer.

Substrate
Ceramic monoliths are ceramic bodies through which pass several thousand small passages. The exhaust gas flows through these passages. The ceramic consists of a 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 is fitted in a stainless steel housing.

Coating
In three-way catalysts, the active catalytic layer applied to the substrate consists
Three-way catalyst mainly out of platinum and rhodium (modified non-metallic coating e. g. on model 124.066 as of 1/97, model 140 (USA) as of 11/96 or at EURO3/4).
Platinum promotes the oxidation of hydrocarbons (HC) and carbon monoxide (CO), rhodium the reduction of nitrogen oxides (NOX). The content of rare metals contained in a catalytic converter is approx. 1 up to 3 grams, depending on size and design.