Modelling dimer–dimer reactions on supported catalysts

Abstract

The kinetics of the dimer–dimer reaction, \(2A_2+B_2\rightarrow 2A_2B\), proceeding on supported catalysts is studied numerically using a phenomenological model which includes: the bulk diffusion of reactants from a bounded vessel towards the adsorbent and the product bulk one from the catalyst surface into the same vessel, adsorption and desorption of particles of both reactants, and surface diffusion of adsorbed particles. Two different arrangements of adsorption sites were used: (i) the same total amount of active and inactive in the surface reaction adsorption sites, (ii) the same concentrations of active and inactive sites. Two adsorption cases of both reactants for each arrangement of adsorption sites are considered: (i) each reactant adsorbs on both active and inactive sites, (ii) both reactants adsorb only on the support. The model where concentrations of both reactants at the catalyst surface are given is also studied. Simulations were performed using the finite difference technique. The influence of the size of the catalytic particle, surface diffusivity, adsorption rate constants, and particle jump rate constants via the catalyst-support interface on the catalytic reactivity of the supported catalyst is studied.