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 H2PtCl6 or RhCl3·3H2O and calcined in air at 500∘C, to produce a Pt- or Rh-loaded YSZ membrane. Methane steam reforming (MSR) over the Rh-loaded Ce0.15Zr0.85O2 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 H2and CO without any packed catalysts. When O2 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 O2 as a result of the catalytic oxidation of H2.