In this answer to comment we pointed out that due to low residence time of reactants, there is no chance to penetrate in washcoat or the penetration depth is negligible. Therefore the reaction surface is equivalent to inner surface of channel. On the other hand uncertainties in obtaining the effective diffusion coefficients in the volumetric approach may cause a variation in simulation results. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.