Effect of Ethane and Propane in Simulated Natural Gas on the Operation of Ni-YSZ Anode Supported Solid Oxide Fuel Cells

Solid oxide fuel cells with Ni-yittria-stabilised zirconia (YSZ) anode supports were tested on surrogate natural gas fuels (methane containing 2.5-10% ethane and 1.25-5% propane) and compared with results for pure methane. Inert anode-side diffusion barriers were found to help suppress coking on the Ni-YSZ anodes. However, carbonaceous deposits were observed on anode compartment surfaces and the barrier layers for all of the natural gas compositions tested. The addition of air to the natural gas was shown to suppress this coking. For natural gas with 5% ethane and 2.5% propane, the addition of 33% air yielded stable, coke-free operation at 750 degrees C and 800 mA cm(-2). Cell performance on this fuel was only slightly worse than for the same cell operated with dry hydrogen.