Effects of thermal aging on microstructure and activity of automotive catalytic converters

In this study the thermal deactivation of a ceramic supported catalytic converter was investigated through laboratory thermal aging experiments and accelerated engine/dynamometer tests in order to evaluate the actual dependence of the conversion efficiency on the specific surface area of the catalytic converter. It was found that a sintering process with competitive mechanisms of coarsening and densification was always responsible for the significant reduction in the specific surface area of the converter. However, a direct relationship between sintering and conversion efficiency was found only when the converter was working under transient engine operating conditions.