The Tufts group has designed the first sorbent system for high-temperature fuel cells. First, they use new materials: rare earth oxides, known to be stable and able to absorb hydrogen sulfide at high temperatures. And, instead of filtering gas through a thick sorbent bed, they pass it over the surface of a thin sorbent layer. Flytzani-Stephanopoulos calls the new design a "simple" solution to the sulfur problem.
Rare earth oxides are inexpensive and easy to obtain. The system could be added to a SOFC using two small boxes -- one for fresh sorbents, the other for spent ones. Sulfur-free gases generated by the fuel cell would sweep the spent sorbents clean, allowing the same sorbents to be used over and over.
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