Copper and Lanthanum Doped Cerium Oxide for Hot Reformate Gas Desulfurization

Hot reformate gas produced by reforming of heavy fuels, such as JP-8, must be desulfurized prior to its use in a solid oxide fuel cell (SOFC). This requires development of sorbent materials with high sulfur absorption efficiency and capacity at the SOFC operating temperature (650-800 C) to avoid heat exchanger penalties. Sorbent performance stability in cyclic operation of sulfidation and regeneration at such high temperatures imposes major constraints on the choice of suitable materials. In on-going work in our laboratory, we have been studying mixed oxides of cerium and lanthanum or copper as high-temperature regenerable sorbents for the removal of H2S upstream of the SOFC anode. The rationale behind our choice is the excellent sulfidation equilibria of lanthana and reduced cerium oxide at these temperatures, the enhanced reducibility of ceria by the addition of lanthana and copper oxide, and the potential for recovery of sulfur in elemental form during regeneration.