Dynamics of catalytic oxidation of CO on Pt with account for exodiffusional retardation

We study for the first time the process of dynamic oxidation of CO on a spherical Pt catalyzer with account for the influence of exodiffusion. In contrast to the case when exodiffusional retardation is neglected and there exists only a single basic form of the catalyzer phase plane, in the present work (thanks to account for the influence of exodiffusion), we find four additional regimes of catalyzer operation. These additional regimes make it possible to explain the discontinuous nature of the dependence of the steady-state reaction rate on the mixture pressure and the reagent concentrations. It is established that the time dependence of the reaction rate upon catalyzer transition to the stationary state may be nonmonotonic and influenced by the initial state of the catalyzer and the dimensionless governing parameters. It is shown that (depending on the values of the external governing parameters) there may exist six, five, four, and two stationary states, which are singular points of the “saddle” or “nodal” type in the phase plane.