Catalytic Converter Design for Two Wheelers

Abstract:

The perpetually increasing global warming, the ever changing stringent vehicular emission norms and PGM prices have always been the major driving force behind catalytic converter design. In India, where two wheelers form a majority of on-road vehicles, the controls of their emissions assume substantial significance.

Unlike other catalytic systems, a catalytic converter has to perform efficiently under adverse conditions of fluctuating temperatures, space velocity and composition of the engine out emissions. Thus, the major challenge, during the design of catalytic converter, lies in both materials chemistry as well as engine design.

The catalytic converter design is ideally the outcome of a joint developmental activity involving the catalyst designer, (usually a material scientist) and the automobile manufacturer. The key input parameters for the catalytic converter design such as the composition of engine out emissions, temperature at the location of catalytic converter
in the exhaust assembly, availability of oxygen, etc are the outcome of engine design.

The catalyst designer, then, uses these vehicle / fuel specific inputs to develop an appropriate catalytic converter, by proper choice & engineering of available materials.

The proper compositional choice of washcoat material would render not only the necessary thermal stability but also serves as an oxygen storage material for the catalyst
to operate in oxygen starved conditions.

The choice of PGM, its precursors, the methodology of PGM Incorporation onto the washcoat & its stabilization will have a direct influence on the PGM inventory, performance & durability of the automobile exhaust catalyst.

This paper briefly reviews the different facets of catalytic converter design and demonstrates that mutual developmental activity between the automobile manufacturer and the catalyst designer is vital to achieve a common social goal of preserving the environment for future generations.