H2 for PEM-FC: effect of CO in the purification by means of Pd-based membranes

Membrane technologies offer a valuable alternative to traditional ones for H2 purification to be used in proton exchange membrane fuel cell (PEM-FC) (with CO < 10 ppm) in small-scale plants. Pd-based membranes can be used for their infinite H2 selectivity. The knowledge of the membrane performance is necessary in order to design a separation/purification unit, in terms of installed membrane area for the required H2 recovery factor (RF). In this work, H2 permeation through a Pd-based membrane and dilution/inhibition effects of other gases (e.g. N2 and CO, present in reformate stream) were measured using a commercial blind tubular Johnson Matthey membrane (Pd Ag 77 23% w, thickness = 60 mm, length = 10 cm, ID = 1.6 mm). The importance of the use of commercial membranes, in spite of their high thickness, depends on the high resistance to embrittlement and on their capacity to support high transmembrane pressure differences (with significant improvements in H2 RF).