Monte Carlo Study of CO--NO Catalytic Surface Reaction Including CO--CO Repulsion

The CO--NO reaction on a catalytic surface is studied by using Langmuir--Hinshelwood thermal mechanism with Monte Carlo computer simulation. In this model, a novel concept of CO--CO repulsion is introduced, which has experimental evidence due to the formation of dipoles when these molecules are chemisorbed on the surface. The system is investigated by applying two approaches of NO dissociation. In the first case, NO always decomposes into N and O before adsorption on the surface. In the second case, NO adsorbs on the surface molecularly and then dissociates into N and O if a vacancy is present in its adjacent neighbourhood. The steady state reactive window (i.e. the continuous production of CO₂ and N₂) is obtained only with the diffusion of N-atoms on the surface, which extends with CO--CO repulsion in the first case. However, in the second case, reactive window is obtained with CO--CO repulsion alone. The reactive window width in this case is reasonably large. The first-order phase transition is eliminated in both the cases with CO--CO repulsion.