Heterogeneously catalyzed reactions involving a gas and a liquid phase are frequently achieved in fixed bed reactors.Despite their wide application,the catalyst selection step remains a long and tedious process.Due to the complex interplay between phases,a thorough understanding of hydrodynamics,mass and heat transfers are required to determine intrinsic catalyst activity.To meet these requirements,an ideal tool would allow access to highly resolved space and temporal information as well as the direct study of industrial catalyst.Nevertheless,few attempts to access local characterization have been proposed yet.1,2 In this work,we propose to mimic slices of fixed bed reactor by using two-dimensional porous media.