O. Kortlüke

Kinetic oscillations in the catalytic CO oxidation on Pt single crystal surfaces: Theory and simulation

A simple lattice gas model is studied for the description of the kinetic oscillations in the CO oxidation on the Pt(100) and Pt(110) surfaces. It takes CO diffusion and surface reconstruction into account and exhibits very interesting phenomena such as synchronized oscillations and mesoscopic pattern formation. The model uses only few parameters, the CO gas phase concentration y, the CO diffusion constant D, the surface phase propagation velocity V, and the ratio of the O2 sticking coefficients on the two surface phases. This enables the study of the whole parameter regime and the theoretical stability analysis for the kinetic oscillations. It can be shown that it is only the ratio of the O2 sticking coefficients on the reconstructed and non–reconstructed surfaces which determines the type of oscillations and the parameter range where these oscillations exist.

Simulation of kinetic oscillations in surface reactions on reconstructing surfaces

A recently introduced lattice gas model [Kuzovkov et al., J. Chem. Phys. 108, 5571 (1998)] is used for the microscopic description of surface reactions on reconstructing surfaces. The model can easily be adapted to different surface reaction systems, e.g., the CO+O2, CO+NO, NO+H2, and NO+NH3 reactions. In addition many reconstructing single crystal surfaces such as Pt(100), Pt(110), Rh(100), and Rh(110) can be simulated because only those properties of the different surface phases are considered which carry the essential physics. Changes in the coordination number are neglected for the different surface phases. In the present study the CO oxidation on Pt single crystal catalysts is investigated for illustration. The model takes CO diffusion and surface reconstruction into account. Very interesting phenomena are observed besides the kinetic oscillations in the particle densities: formation of mesoscopic patterns and synchronization. Only few parameters, as there are the CO gas phase concentration y, the CO...

Monte Carlo simulation of the CO+NO reaction

In this paper a simple lattice gas model for the catalytic CO+NO→CO2+1/2N2 surface reaction is studied by means of Monte Carlo simulations. In the simulations we take into consideration the diffusion of all particles and the desorption of CO. The square and triangular lattices are used to model the surface of an ideal catalyst, whereas percolation clusters, diffusion limited aggregates (DLA), the Sierpinski carpet, and the Sierpinski gasket are introduced as better models for supported catalysts. In many simulations an interval of the gas phase concentration yCO∈[y1,y2] exists, where the simulation remains in a reactive state. The kinetic phase transitions of second (y1) and first‐order (y2) which appear in this reaction system are studied as a function of the system parameters. The above interval is broadened with increasing diffusion of the adsorbed particles. Desorption of CO results in a shift of y2 to yCO=1. On the Sierpinski lattices only very small reactive intervals appear, whereas on DLA and perc...