Operation of phosphoric acid fuel cells on coal gases

The authors describe a project to develop electrocatalysts that enable phosphoric acid fuel cells (PAFCs) to operate on coal-derived gases and thus increase coal utilization. The specific improvement sought is tolerance to poisoning by coal-gas contaminants such as carbon monoxide and hydrogen sulfide. The approach used for reducing poisoning effects is to increase catalyst dispersion and decrease the adsorption affinity of the catalytic surface for CO and H₂S through the use of Pt alloys. Twenty-five electrocatalysts have been evaluated. The effect on anode polarization of catalyst composition, catalyst support, fuel gas composition, and specific surface area has been investigated. Results to date have identified a group of Pt alloy catalysts with significantly lower anode polarization than Pt in the presence of CO and H₂S. Further improvements have been achieved by increasing the dispersion of Pt alloys over a range of compositions