KINETICS OF CATALYTIC REACTIONS ON A UNIFORM SURFACE AND SINGLE SITES: SIMILARITY AND DIFFERENCE

To illustrate typical similarities and differences in the reaction kinetics occurring on a uniform surface and single sites (e.g. on single metal atoms incorporated into the inner walls of zeolite), we analyze a generic reaction scheme of N2O decomposition running in the presence of oxygen. In both cases, there are three reaction regimes, (i) controlled exclusively by the N2O-decomposition step, (ii) partly inhibited by oxygen, or (iii) limited by oxygen desorption. Regime (i) is kinetically similar (first order in N2O) in the two cases. The states of the catalytic sites are however different. Regime (ii) exhibits different reaction orders in oxygen (-0.5 for the surface and -1 for single sites). Regime (iii) is fully identical in both the cases.