THE MECHANISM OF THE INTERACTION BETWEEN CO AND AN SNO2 SURFACE - THE ROLE OF WATER-VAPOR

A model for the interaction between CO and an SnO2 surface, which takes into account the role of water vapour, is presented. An assumption, supported by literature data, about the interaction of water vapour with the SnO2 surface as a generating process of chemisorption sites for oxygen is made. By means of the quasi-chemical reaction formalism and of an originally written rule of conservation of the number of electrons, we find an equation in agreement with experimental data. We conclude that in the conditions in which the model is valid (working temperature of about 600 K, etc.) the reacting chemisorbed species of oxygen is doubly ionized oxygen atoms and that their interaction with reducing gases is enhanced by the presence of water vapour.