INFLUENCE OF THE SURROUNDING ATMOSPHERE UPON THE CATALYTIC PERFORMANCES OF 3-WAY CATALYSTS

The adaptation of the catalytic surface to the gas phase may induce mo difications of the atomic arrangement. The interaction between the gas phase composition and three-way catalyst type were investigated both by in situ EXAFS experiments and in a laboratory reactor. In both case s, experimental conditions simulating the exhaust from a catalytic con verter were reproduced, Activity measurements in an oscillating feed o f CO, NO, C3H5 and O-2 revealed that application of a traditional kine tic study was not possible owing to the transformation of the active s ite during the course of the reaction. The occurrence of a redox proce ss involving rhodium when using Pt-Rh/Al2O3 was observed as well as th at of Pt-Rh alloy formation.