Журнал мембранных наук и технологий

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Evaluation of Step Resistance in Multilayered Ceramic-Supported Pd-Based Membranes for Hydrogen Purification in the Presence of Concentration Polarisation

Caravella A and Sun Y

In this work, a systematic approach is used to quantify the single-step influence in composite Pd-based membranes on hydrogen permeation in the presence of concentration polarisation. To perform this study, an already developed permeation model is applied to a membrane supported on a five-layered asymmetric porous support. The results are presented in terms of both single-layer influence (calculated using an expression involving the permeation limiting fluxes) and the here introduced Support Resistance Coefficient, SRC, which is a coefficient measuring quantitatively the extent of the driving force in the entire support, analogously to what done for the definition of the Concentration Polarisation Coefficient, CPC. Analysing the membrane behaviour in different conditions of temperature, total feed pressure and Pd-layer thickness, it is eventually shows that, the presence of polarization determine a decreasing effect of the porous support in the considered configuration, i.e., with the selective layer placed on the high-pressure side and the support placed on the permeation one. This conclusion indicates that, for sufficiently thin metal layers, the hydrogen permeation is mostly influenced by concentration polarisation and, thus, the fluid dynamic conditions in the upstream side become a crucial parameter to optimise.