Catalytic reactions with bulkmediated excursions: Mixing fails to restore chemical equilibrium
Abstract
In this paper we analyze the effect of the bulkmediated excursions (BME) of reactive species on the longtime behavior of the catalytic LangmuirHinshelwoodlike A+B→0 reactions in systems in which a catalytic plane (CP) is in contact with a liquid phase, containing concentrations of reactive particles. Such BME result from repeated particles desorption from the CP, subsequent diffusion in the liquid phase, and eventual readsorption on the CP away from the initial detachment point. This process leads to an effective superdiffusive transport along the CP. We consider both “batch” reactions, in which all particles of reactive species were initially adsorbed onto the CP, and reactions followed by a steady inflow of particles onto the CP. We show that for batch reactions the BME provide an effective mixing channel and here the meanfieldtype behavior emerges. On the contrary, for reaction followed by a steady inflow of particles, we observe essential departures from the meanfield behavior and find that the mixing effect of the BME is insufficient to restore chemical equilibrium. We show that a steady state is established as t→∞, in which the limiting value of the mean coverage of the CP depends on the particles’ diffusion coefficient in the bulk liquid phase, and that the spatial distributions of adsorbed particles are strongly correlated. Moreover, we show that the relaxation to such a steady state is a powerlaw function of time, in contrast to the exponential time dependence describing the approach to equilibrium in perfectly stirred systems.
 Publication:

Physical Review E
 Pub Date:
 March 2004
 DOI:
 10.1103/PhysRevE.69.036115
 arXiv:
 arXiv:condmat/0309656
 Bibcode:
 2004PhRvE..69c6115C
 Keywords:

 05.50.+q;
 64.60.Cn;
 68.43.De;
 82.65.+r;
 Lattice theory and statistics;
 Orderdisorder transformations;
 statistical mechanics of model systems;
 Statistical mechanics of adsorbates;
 Surface and interface chemistry;
 heterogeneous catalysis at surfaces;
 Condensed Matter  Statistical Mechanics
 EPrint:
 10 pages, 1 figure