Coupled oscillations of H2/O2/CO on silica supported rhodium catalyst

Self-sustained oscillations obtained during the catalytic oxidation of CO and H2 were studied over Rh/SiO2 by an FTIR-mass spectrometric technique. An average oscillatory period of 7.1±0.5 minutes was obtained for the CO/O2 reaction at 348 K. For the H2/O2 oscillatory reaction the period was observed to be 1.3±0.8 minutes. When the oscillations were coupled at the same temperature, the period for both the CO/O2 and the H2/O2 reactions was observed to be 7.9±0.8 minutes. The kinetic coupling of the reaction rates is explained by considering the periodic fluctuations in surface temperature which occur as a result of the more exothermic CO/O2 reaction.