Modelling of the “surface explosion” of the $$\hbox {NO}+\hbox {H}_{2}$$ reaction over supported catalysts

Abstract

We propose and numerically solve a phenomenological model for reduction of nitric oxide NO by hydrogen $$\hbox {H}_2$$ over supported catalysts. The model is based on the coupled system of PDEs with nonclassic conjugate conditions at the catalyst–support interface and includes the adsorption and desorption of particles of both reactants, surface diffusion of adsorbed molecules, and their surface reaction. We study the influence of the surface diffusivity, the particle jumping rate constants via the catalyst–support interface, and the concentration of reactants on the catalytic reactivity of the catalyst. We find that under specific values of kinetic rate constants, the turnover frequency of molecules of both reactants into $$\hbox {H}_2$$ O can possess one, two, or three peaks, whereas the turnover frequency of the reactant particles into $$\hbox {N}_2$$ , $$\hbox {N}_2$$ O, and $$\hbox {NH}_3$$ can have one or two peaks. We also give the other model based on the coupled system of ODEs. We show that turnover frequencies obtained by both models differ slightly only for large values of the surface diffusivity.