Thermodynamic predictions of the impact of fuel composition on the propensity of sulphur to interact with Ni and ceria-based anodes for solid oxide fuel cells

Thermodynamic calculations have been made to predict the stability of solid oxide fuel cell (SOFC) anode materials when exposed to hydrogen sulphide (H2S) in hydrogen (H2) over a range of partial pressures of sulphur (pS2) and oxygen (pO2) representative of fuel cell operating conditions. The study focussed on the behaviour of nickel and ceria, which form the basis of nickel–gadolinium-doped ceria (Ni-CGO) anodes, often used as an active layer within SOFCs. The reaction of Ni with sulphur is predicted to become more favourable as temperature and hydrogen partial pressure (pH2) decrease. Ceria is shown to become increasingly non-stoichiometric (CeOn, n < 2) as pO2 decreases and temperature increases, and it is predicted that its reaction with sulphur becomes more favourable under these conditions.