[en] Type of packings and characteristics of their geometry can affect the flow behavior in the reactive distillation columns. KATAPAK SP is one the newest modular catalytic structured packings that has been used in the reactive distillation columns, recently. However, there is not any study on the hydrodynamics of this packing by using computational fluid dynamics. In the present work, a 3D VOF model was developed to evaluate dry and wet pressure drops of catalytic structured packings, modular catalytic structured packings-11 and 12. The module of modular catalytic structured packings is made of alternating vertical layers of structured packing sheets (Mellapak Plus) and catalyst bags. The goal of this paper is to illustrate the effect of geometry on the hydrodynamics and characterization of flow in the modular catalytic structured packings modules. Results showed that the mean relative errors for prediction of dry and wet pressure drops were 17% and 7% for modular catalytic structured packings-11 and 11% and 12% for modular catalytic structured packings-12, respectively. According to Computational fluid dynamics results, pressure drop in closed channels was higher than that in open channels. The catalyst bags were simulated as porous media. The simulation led to determination of the liquid velocity distribution in the catalyst bags.