Diffusive Plus Convective Mass Transport Through Catalytic Membrane Layer with Dispersed Nanometer-Sized Catalyst

Abstract

Mass transfer rates across catalytic memb rane interfaces accompanied by first-order, irreversible reactions have been investigated. The catalyst particles impregnated in the membrane mat rix are assumed to be very fine, nanometer-sized particles which are uniformly distributed in the structure of the membrane layer. Pseudo-homogeneous models have been developed to describe mass transport through this catalytic membrane layer. The models developed include the mass transport into and inside the catalytic part icles as well as through the memb rane layer taking into account convective and diffusive flows, so it is also valid in the limiting cases namely without convective flow (Pe=0), or with very large convective flow (Pe >> 1). The models describe two operating modes (with and without sweep phase on the permeate side of the catalytic memb rane layer) and apply two different boundary conditions for the feed boundary layer. One of the boundary conditions approaches the diffusive flow by the Fickian one assuming linear concentration distribution while the other one solves exactly the mass transport in the feed boundary layer. The different model results obtained are compared to each other proving the importance of the carefully decision of the operating modes and boundary conditions. The mathematical model has been verified by means of experimental data taken fro m the literature.