SPATIOTEMPORAL TEMPERATURE PATTERNS ON AN ELECTRICALLY HEATED CATALYTIC RIBBON

Oscillatory and chaotic variations in the overall reaction rate were observed during the oxidation of propylene in air on a thin platinum ribbon, the average temperature (resistance) of which was kept at a preset value via electrical heating. A thermal image showed that back and forth movement of a high-temperature wave on the ribbon and the dynamic change in the length and temperature of the ignited zone were the cause of the variation in the overall reaction rate. The overall reaction rate in the chaotic region oscillates at a much higher frequency than the local temperature. The corresponding power spectrum of the reaction rate decays exponentially, while that of the local temperature decays as a power law.