Adsorption ensembles and catalysis: a mathematical method

Abstract

Adsorption and subsequent catalytic reactions of large molecules (e.g. higher hydrocarbons) usually require an ensemble of adsorption sites, i.e. a number of surface atoms being of the active species. The probabilities of certain ensembles (bridge sites and triangles) on a plane triangular lattice are calculated for fixed surface concentration of one atomic species depending on the interactions between different kinds of atoms. In a similar way the surface coverage of interacting adsorbed atoms on a perfect triangular lattice of adsorption sites is investigated with respect to its dependence on the partial pressure and the interaction energies. In both cases ordered surface structures can be found; the conditions of their formation and their consequences are pointed out.