for converting hydrocarbon feedstock to hydrogen for use as a reactant in the fuel cells for example a steam reformer may be used to convert the hydrocarbon feedstock to hydrogen however depending upon the feedstock used and the conditions within the reformer the reformer effluent may contain as much as 20 by volume carbon monoxide more typically the effluent will contain between 10 and 15 carbon monoxide note in this application all references to volume are dry gas volume 39 s the ratio of moles steam to moles carbon in the hydrocarbon feedstock at the reformer inlet may be between 3 and 8 but is preferably between 3 5 and 4 5 certain types of fuel cells such as those which use phosphoric acid as the electrolyte and platinum as the electrode catalyst suffer a considerable performance loss at high levels of carbon monoxide concentration in such a fuel cell system a shift converter is commonly used to reduce the carbon monoxide concentration to an acceptable level in one exemplary fuel cell power plant the fuel conditioning apparatus comprises a high temperature steam reforming reactor containing a nickel catalyst followed by a chromia stabilized iron oxide shift converter the reactor is designed to operate at temperatures above about 1500 u00b0 f so that hydrocarbon feedstocks containing large amounts of organic sulfur may be directly steam reformed without the necessity of reducing the sulfur content of the.