A procedure for starting up a fuel cell system that is disconnected from
its primary load and that has air in both its cathode and anode flow
fields includes a) connecting an auxiliary resistive load across the cell
to reduce the cell voltage; b) initiating a recirculation of the anode
flow field exhaust through a recycle loop and providing a limited flow of
hydrogen fuel into that recirculating exhaust; c) catalytically reacting
the added fuel with oxygen present in the recirculating gases until
substantially no oxygen remains within the recycle loop; disconnecting
the auxiliary load; and then d) providing normal operating flow rates of
fuel and air into respective anode and cathode flow fields and connecting
the primary load across the cell. The catalytic reaction may take place
on the anode or within a catalytic burner disposed within the recycle
loop. The procedure allows start-up of the fuel cell system without the
use of an inert gas purge while minimizing dissolution of the catalyst
and corrosion of the catalyst support during the start-up process.