Spillover on supported catalysts - Dynamic Monte Carlo study

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The kinetics of a 2A + B2 = 2AB reaction on supported metal catalyst with spillover effects is investigated using Dynamic Monte Carlo simulations. In the presented model A particles can adsorb reversibly on both metal clusters and the support whereas B2 particles can adsorb dissociatively only on metal clusters. Particles A can diffuse from the support to metal clusters and vice versa. The model describes CO oxidation on Pd/Al2O3 catalyst. Steady-state reaction rates and surface coverages are investigated as functions of partial pressures of reactants in the gas phase. Simulations show that spillover effects change the reaction rate dramatically by increasing it and widening the pressure window of the reaction. In systems with spillover the reaction driven by an adsorption channel, in addition to a spillover channel, is observed. The character of the dependence of the reaction rate on reactants' partial pressures can be controlled by changes of spillover and adsorption channel contributions.