Importance

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Abstract

A fuel cell power plant (110) has a fuel cell stack assembly (CSA) (16) including an anode (18), and a fuel processing system (FPS) (120) providing a hydrogen-rich reformate/fuel stream (34, 134, 62) for the anode (18) of the CSA (16). A relatively active metal catalyst is associated with one or both of the anode (18) and the FPS (120), and is subject to degradation by the presence of even low levels, e.g. 100 ppb to 5 ppb-wt. reformate, of sulfur in the fuel stream. A guard bed (70) containing a guard material (72) is provided in the FPS (120) for protecting the relatively active metal catalysts by adsorbing, and further reducing the level of, sulfur in the fuel stream. The guard material (72) is a metal or metal oxide capable of forming a stable sulfide in the presence of low levels of H.sub.2S in the fuel stream (34), and is preferably selected from the group consisting of: ZnO, CuO on CeO.sub.2-based support, NiO on CeO.sub.2-based support, and Cu/ZnO. Provision is also made (80, 74, 75, 76, 78, 82) for regenerating the guard material (72) in situ.

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First Claim