AGING OF AN AUTOCATALYST UNDER SIMULATED HIGH-SPEED CONDITIONS

A three-way autocatalyst has been submitted to aging in the exhaust of an engine on a dynamometer stand with simulation of high speed driving, frequent acceleration and deceleration and increased oil consumption. The objective of these experiments was to correlate at different stages of evolution, the catalytic properties with the physico-chemical characteristics of the catalyst. The light-off temperatures, the mean conversions around stoichiometry in steady state or with air-fuel perturbations were followed as a function of time. Rate equations describing these evolutions are given in some cases. Sintering of the catalyst oxides and noble metals as well as poison deposit was simultaneously checked and associated with catalytic efficiency decrease. © 1990.