Monte Carlo simulation of the kinetics of rapid reactions on nanometer catalyst particles

• Published in: Surface science Vol. 405; no. 1; pp. 27 - 37
• Main Authors: Zhdanov, V.P, Kasemo, B
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 12.05.1998
• Subjects: Catalysis; Computer simulations; Low index single crystal surfaces; Models of non-equilibrium phenomena; Models of surface chemical reactions; Surface diffusion; Catalysis; Models of surface chemical reactions; Surface diffusion; Computer simulations; Low index single crystal surfaces; Models of non-equilibrium phenomena
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(97)01078-9

Using an original Monte Carlo algorithm, we have analyzed the kinetics of the 2 A+ B 2→2 A B reaction, occurring via the standard Langmuir–Hinshelwood (LH) mechanism, in the two limits corresponding to the infinite surface and to interacting facets (by surface diffusion) of a nanometer-sized crystallite, respectively. The latter mimics possible kinetics on real supported catalysts, and on recent nanofabricated model catalysts. The simulations were carried out with a realistic ratio between the rates of the elementary steps (the LH step is rapid compared to A and B 2 adsorption and slow compared to A diffusion, and B particles are immobile). The results demonstrate that the kinetics for nanometer-sized particles can be remarkably different compared to those for the infinite surface. Depending on the values of model parameters, the reaction window (along the A+ B 2 gas mixture scale) on the nanometer catalyst particle may be wider or narrower than on the infinite surface, and its position may be shifted. These findings have implications for interpretation of experimental data and for the design of real catalysts and also have important consequences for the continuing efforts to bridge the so-called pressure and structure “gaps” in catalysis.