Fuel cells also require an essentially sulfur-free feed stream in order to prevent poisoning of fuel cell anode catalyst, which requires effective desulfurization of either the liquid fuel or the synthesis gas feed converted from gasoline, diesel or jet fuels using a reformer. Even the more robust high temperature solid oxide fuel cells (SOFCs) are poisoned with low levels of sulfur contaminants. Although the U.S. Environmental Protection Agency (EPA) has announced new regulations that mandate refineries to reduce sulfur levels of transportation fuels down to 30 parts per million on weight basis (ppmw) in gasoline and 15 ppmw in diesel; even with meeting these reduction levels, sulfur concentrations in transportation fuels will still exceed the levels tolerable by state of the art SOFCs, about 100 ppbv, preferably 10 ppbv or less.
While sorbent technologies are currently available for removing sulfur from reformate gas, they are not very suitable for use at the very high temperature needed for feed gas to solid oxide fuel cells (greater than 500oC and typically 700-800oC). The currently available sorbents exhibit higher sulfur capacity, removal rate and stability at more moderate temperatures below about 500oC.