Improved model of lattice gas in the adsorption of carbon monoxide and oxygen

Abstract

The adsorption and subsequent oxidation of carbon monoxide (CO) on a platinum (Pt) surface has been studied using computational methods. The Monte Carlo method is used to this end through the lattice model. This study focuses on the improvement of this first theoretical model (ZGB) proposed for the oxidation of CO. In this work, four different models are revised in detail with the objective of establishing a comparison between the obtained results on the oxidation of CO on the Pt with an orientation (111) surface. The variance between the models lies on the nature of the sticking coefficient of the CO and oxygen (O2) molecules on Pt (111). This adsorption depends on the initial concentration of CO in the gas phase and the number of vacant sites on the platinum surface. The results obtained in these simulations show that the first model, the ZGB model, differs considerably from the other models, and thus the results with the second and third model have a better adjustment to the adsorption of the CO and O2 molecules, since they take into account the gas concentration, the sticking coefficient and the interaction with the neighboring particles. In this sense, the oxidation reaction occurs in a wider theoretical range around 0.5 mole fraction of CO and 0.2 mole fraction of O atomic, and the poisoning of the platinum catalytic surface can be inhibited if the concentration of carbon monoxide is included as a control parameter.