FTIR studies of catalyst preparation effects on spatial propagation of oscillations during CO oxidation on

In situ selected-area FTIR spectroscopy and localized catalyst temperature measurement techniques have been utilized to show that the oscillatory behavior of a PtSiO2 catalyst during CO oxidation is related to the spatial distribution of crystallites. Various catalyst preparation techniques have been used to prepare catalysts with different crystallite sizes and different separations among the crystallites, these catalysts being characterized by chemisorption and optical microscopy. It is shown that the occurrence of oscillations is affected by the crystallite size distribution and by the separation among crystallites. The results are explained in terms of a model which relates the separation and size distribution of crystallites to the spatial propagation of oscillatory states.