Method for purifying hydrogen in a reformed gas

A method for purifying hydrogen by oxidizing and removing carbon monoxide in a reformed gas containing carbon monoxide in addition to a main component of hydrogen gas, the method comprising:

• supplying an oxidant gas to the reformed gas for reacting with carbon monoxide in the catalyst bed for oxidizing carbon monoxide,
• passing a stream of the reformed gas through a reformed gas pathway having a surrounding portion, wherein the surrounding portion of the reformed gas pathway at least partially surrounds an outer periphery of the catalyst bed and is separated from the catalyst bed by a heat transfer wall, so as to effect heating of a downstream side of the catalyst bed before passing through an upstream side of the catalyst bed,
• cooling the reformed gas upstream of the catalyst bed, and
• passing the stream of reformed gas through the catalyst bed.