A PEMFC and H 2 membrane purification integrated plant

Abstract

In this work an integrated system composed of a Pd–Ag membrane module and a polymeric electrolyte fuel cell (PEMFC) was studied. The Pd–Ag membrane module, allowing a pure hydrogen permeate stream to be fed directly to the PEMFC, was used as an H 2 purification step with a mixture containing also CO and CO 2. The CO poisoning effect on the Pd–Ag membrane and its consequences on the hydrogen permeation were analysed in a temperature range 300–450 °C in terms of permeance reduction conditioning also the H 2 recovery index (RI). A comparison between the experimental data obtained feeding the fuel cell (FC) with pure H 2 from a cylinder and from the purification step was also performed in order to evaluate the PEMFC performance stability. After the experimental study of each single step, particular attention was devoted to the analysis of the integrated system Pd–Ag membrane purification step—PEMFC, focusing on the influence of the Pd–Ag membrane module operating conditions on the electrical performance of the PEMFC. The PEMFC internal crossover was also considered and its effects on the electrical performance were taken into account by means of a PEMFC actual efficiency. Furthermore, integrated membrane plant chemical efficiency was defined considering the H 2 converted into electricity with respect to the total amount of H 2 contained in the mixture. The integrated Pd–Ag membrane purification with PEMFC shows very good results: the hydrogen is well purified and the PEMFC performance is very high near the nominal value.