Hydrogen production in zirconia membrane reactors for use in PEM fuel cells

A yttria-stabilized zirconia (YSZ) membrane was formed on the surface of a porous α -alumina support tube by a sol–gel procedure. The membrane was then impregnated with an aqueous solution of H 2 PtCl 6 or RhCl 3 · 3 H 2 O and calcined in air at 500 ∘ C , to produce a Pt- or Rh-loaded YSZ membrane. Methane steam reforming (MSR) over the Rh-loaded Ce 0.15 Zr 0.85 O 2 catalyst was carried out in a membrane reactor using the Pt-loaded YSZ membrane. Methane conversion in the membrane reactor was 20% higher than that in a packed bed reactor due to the high permeation rate of hydrogen compared to the reaction rate. In addition, Pt- and Rh-loaded YSZ membranes were also examined for the selective oxidation of CO from a mixture of H 2 and CO without any packed catalysts. When O 2 was added to the feed, CO was oxidized in the Pt-loaded YSZ layer and the CO concentration of 10,000 ppm on the feed side was decreased to below 30 ppm (detection limit) at 150 ∘ C . Meanwhile the oxidation of CO was suppressed at higher temperatures because of the consumption of O 2 as a result of the catalytic oxidation of H 2 .