NO--CO--O₂ Reaction on a Metal Catalytic Surface using Eley--Rideal Mechanism

Interactions among the reacting species NO, CO and O₂ on metal catalytic surfaces are studied by means of Monte Carlo simulation using the Eley--Rideal (ER) mechanism. The study of this three-component system is important for understanding of the reaction kinetics by varying the relative ratios of the reactants. It is found that contrary to the conventional Langmuir--Hinshelwood (LH) thermal mechanism in which two irreversible phase transitions are obtained between active states and poisoned states, a single phase transition is observed when the ER mechanism is combined with the LH mechanism. The phase diagrams of the surface coverage and the steady state production of CO₂, N₂ and N₂O are evaluated as a function of the partial pressures of the reactants in the gas phase. The continuous production of CO₂ starts as soon as the CO pressure is switched on and the second order phase transition at the first critical point is eliminated, which is in agreement with the experimental findings.