Chemical Oscillation and Chaos in Catalytic Oxidation of Carbon Monoxide on Pt（110）

A mathematical model was established on base of elementary reaction steps adsorption, desorption, reaction, and diffusion. The model can describe the nonlinear behavior during catalytic oxidation of carbon monoxide on Pt（110）. By numerical simulation, chemical oscillation and kinetic phase transition can be reproduced successfully. While the oscillator presents with a kind of periodic foring: on-off control tO partial pressure of CO, the system shows different oscillatory behavior, even chaos. The routine to chaos and out of chaos were both recognized as periodic doubling process through analysis of Lyapunov exponential spectrum. The reason to cause the complex nonlinear behavior was understood as there exists delay effect of structure phase transformation between 1×1 and 1×2 phases. The reaction processes respond quickly to the input modulation, but the structure transformation does slowly. More detail studies on the delay effect of structare transform are expected to result in the final understanding of the chaos behavior in autonmous system.