Ni–YSZ SOFC anodes—Minimization of carbon deposition

An advantage of solid oxide fuel cells (SOFC) over some other types of fuel cells is the extended range of fuels they can use. Besides hydrogen, hydrocarbons are often used. A problem that may arise on a prolonged operation of cells using hydrocarbons is the formation of carbon deposits on the anodes. These deposits deteriorate the cell performance by blocking the access of reactants to the anode surface and into its pores, thus changing the micromorphology of the anode. The behavior of anodic material during the extended contact with such fuels must be tested and if needed modifications must be made in its composition in order to reduce the rate of carbon deposition.Ni–YSZ cermet materials prepared by different processes (sol–gel and combustion synthesis) with variations in composition and presence of dopants were tested by exposing these materials to methane at elevated temperatures. The thermal dissociation of methane, which leads to carbon deposits on the cermet surface, was studied by the analysis of the gas phase using mass spectrometry and gas chromatography. The influence of anode composition and its microstructure on carbon deposition was studied as well as the influence of some dopants. The amount of the deposited carbon was determined by temperature programmed oxidation.