Regeneration of Anodes Exposed to Sulfur

In any type of fuel cell, impurities in the fuel may be incompatible with either the anode material or the reforming catalyst, with potentially serious consequences. As a result a fuel-processing step is normally required before use of a commercial fuel. In the SOFC case sulfur is the element most likely to degrade a nickel cermet anode. In the present work a method based on the hydrodesulfurisation processes employed in the petrochemicals industry was used to desensitise cermet anodes to sulfur in the fuel gas stream. The mechanisms of sulfur poisoning on nickel are indicated. The desensitising catalyst is a dispersion of a refractory heavy transition metal, introduced into the pores of the cermet anode as a solution of an ammonium salt, followed by pyrolysis. A treated anode can be regenerated after several cycles of sulfur poisoning.