Adsorption Ensembles On Bimetallic Surface Alloys through Monte Carlo

BOSCOBOINIK, JORGE A.; CALAZA, FLORENCIA C.; GARVEY, MICHAEL T.; TYSOE, WILFRED T.

Lincolnshire, IL

Encuentro; 38TH GREAT LAKES REGIONAL MEETING ACS; 2009

AMERICAN CHEMICAL SOCIETY

Bimetallic surface alloys play an important role in heterogeneous catalysis. Usually only one of the components of the alloy provides the active sites for the adsorption of the reactants. One of the effects of the second metal is to limit the size and distribution of ensembles of atoms of the active metal, changing in this way the selectivity and activity of the catalyst. Monte Carlo simulations allow the analysis of the distribution of ensembles on alloys that range from ordered to disordered. In this work we show how the formation of the Au/Pd(111) surface alloy is simulated and how the ensembles for the adsorption of Hydrogen and Oxygen are counted. The results obtained are in very good agreement with thermal programmed desorption experiments (TPD). Furthermore, the decomposition of Ethylene to form Ethylidyne and atomic Hydrogen is studied with the same methodology giving satisfactory results. This emphasizes the potentiality of this method to facilitate the design of bimetallic catalysts.