Theoretical Study of H2 Permeation through Supported Pd-Based Membranes

In this work, the hydrogen permeation through Pd-based membranes is described by considering the entire process as divided into its elementary steps, each one modeled by its own equations. The diffusion through the selective layer is modeled by the irreversible thermodynamics theory. The surface phenomena (adsorption and desorption) are described by the equations developed by King and Wells [1] for dissociation of N2 on tungsten and used by Behm et al. [2] for H2 dissociation on palladium. The transitions from adsorbed state to absorbed one and vice-versa are modeled by the equations of Ward and Dao [3]. A multicomponent approach is used for modeling the mass transport in the fluid phases (feed film, permeate film and porous support), calculating the film thicknesses at various operating conditions (Table 1). In the porous support, convective, conductive and Knudsen transport are taken into account. At the moment, no chemical reactions, thermal decompositions or surface inhibition phenomena are considered.