The PEMFC-integrated CO oxidation — a novel method of simplifying the fuel cell plant

Natural gas and methanol are the most economical fuels for residential fuel cell power generators as well as for mobile PEM-fuel cells. However, they have to be reformed with steam into hydrogen, which is to be cleaned from CO by shift-reaction and by partial oxidation to a level of no more than 30 ppm CO. This level is set by the Pt/Ru–C-anode of the PEMFC. A higher partial oxidation reaction rate for CO than those of Pt/Ru–C can be achieved in an oxidic Au–catalyst system. In the Fe2O3–Au system, a reaction rate of 2•10−3 mol CO/s g Au at 1000 ppm CO and 5% “air bleed” at 80°C is achieved. This high rate allows to construct a catalyst-sheet for each cell within a PEMFC-stack. Practical and theoretical current/voltage characteristics of PEMFCs with catalyst-sheet are presented at 1000 ppm CO in hydrogen with 5% “air bleed”. This gives the possibility of simplifying the gas processor of the plant.