Conversion of Ammonia in Electricity by SOFC

Proton Exchange Membrane fuel cells are adversely affected by ammonia because of reduced conductivity of Nafion and decreased activity of the catalyst layers. Alkaline fuel cells (AFC) are unaffected by ammonia but are unlikely to be commercially pursued because of the inherently poor performance associated with non-solid state technologies. Ammonia can be used as a fuel for Solid Oxide Fuel Cells (SOFC) and Protonic Ceramic Fuel Cell (PCFC). The SOFC provides high power densities (100 -1000 mW/cm² for both proton-conducting and oxygen ion-conducting electrolytes). Ammonia is fed into SOFC’s anode. Inside anode, at the high operating temperatures of SOFC ammonia is decomposed (NH3=>1.5H2+0.5N2) on Ni-based catalyst. Whereupon, in the SOFC chemical energy of hydrogen is converted into electricity due to a chemical reaction of positively charged hydrogen ions with oxygen. In fact, anode of SOFC acts the part of ammonia cracker. One of the challenges connected with using ammonia as the direct fuel for SOFC is nitrogen utilization at SOFC exhaust. We considered some ways of nitrogen utilization. Comparative analysis of nitrogen utilization had been completed.

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