Integrated membrane system for pure hydrogen production: A Pd–Ag membrane reactor and a PEMFC

In this work, an integrated system consisting of single stage hydrogen production and a commercial PEMFC was investigated experimentally. The CO-free hydrogen fed to the PEMFC was produced in a Pd–Ag membrane reactor (MR), upgrading a syngas stream with a composition similar to that coming out of a reformer (CO 45%; H2 50%; CO2 4%; N2 balance, on dry basis). The performance of the MR was evaluated in terms of CO conversion and H2 recovery as a function of the feed pressure (up to 600 kPa) and space velocity; no sweep gas was used for promoting the H2 permeation, since this role was assigned exclusively to the feed pressure.Special attention was paid to the analysis of the integrated system, focusing on the influence of the Pd–Ag MR operating conditions on the electrical performance of the PEMFC. The PEMFC internal crossover was also considered to have an effect on the electrical performance and this was taken into account estimating the PEMFC actual efficiency. Furthermore, the chemical efficiency of the integrated membrane plant was evaluated, considering the H2 converted into electricity with respect to the total amount of H2 contained in the feed mixture. An interesting performance was shown by the integrated system since the PEMFC performance was close to the power nominal value.