In this work, a rigorous heterogeneous model for the analysis of an industrial adiabatic multi-bed catalytic reactor for sulfur dioxide oxidation was developed. It was based on the Maxwell-Stefan diffusional model, which was selected from the analysis of the Maxwell-Stefan diffusivity and the thermodynamic correction factor matrix. The reactor model, implemented in MatLab, allowed evaluating truthfully the behavior of each catalytic bed (e.g., concentration, conversion, pressure and temperature profiles) with errors lower than 3%. Additionally, the effectiveness factor variation along the reactor was estimated. Thus, a better understanding of the effect of diffusional resistances on reactor performance was possible. (C) 2015 Elsevier B.V. All rights reserved.