COMPUTER-SIMULATION OF THE EFFECT OF PUMPING RATE ON THE OSCILLATORY BEHAVIOR IN CO OXIDATION ON PD(110)

Abstract

The effect of pumping rates on the oscillatory behavior of CO oxidation on Pd(110) single crystals was investigated by solving kinetic rate equations of a subsurface oxygen model coupled with gas phase mass balance equations, because a large variation of CO partial pressure was reported in a previous experiment which indicated that the negligence of the pumping rate effect was not acceptable in kinetic study. As the pumping rate in the vacuum system was decreased in this simulation study, the parameter range where oscillation exists was widened, the oscillation period increased and the amplitude of the oscillation in the reaction rate decreased, while the amplitude of the work function change increased. In some parameter regions, the oscillation disappeared as the pumping rate increased. The dependence of the oscillatory behavior on the pumping rate indicated the importance of the gas phase mass balance consideration in the theoretical work.