Surface effects and CO/CO2 influence in the H2 permeation through a Pd-Ag membrane: A comprehensive model

Abstract

The permeability of a 0.175 mm thick PdeAg tubular membrane to pure H2 and binarymixtures of H2/CO or H2/CO2 was studied. The tests were performed in a wide range oftemperature (523e723 K) and pressure (200e800 kPa).Pure H2-permeation through a dense metal membrane is described by the Sieverts' law.However, it was already found that the H2 permeation does not follow the Sieverts' lawwhen other components are present in the feed and namely CO or CO2. In this work, it isproposed a new permeation model based on the Sieverts' law considering: i) the masstransfer resistance due to the surface effects and ii) the barrier effect due to the presence ofeither CO or CO2. The model was successfully validated against experimental data ofhydrogen permeation for binary (H2/CO and H2/CO2) experiments for every working temperature and pressure.