Methane steam reforming in the absence and presence of H2S over Ce0.8Pr0.2O2 − δ, Ce0.85Sm0.15O2 − δ and Ce0.9Gd0.1O2 − δ SOFCs anode materials

•Ce1-xAxO2-d, (A = Pr, Sm and Gd) anode materials for IT-SOFCs.•Red-ox and spreading action of praseodymium in cerium oxide host structure.•Hydrogen sulfide promotes hydrogen formation.•High propensity of materials to sulfur adsorption and stability with time.

We report here on the activity and stability of low-content praseodymium–, samarium– and gadolinium–cerium oxide catalysts for the steam reforming of methane under water deficient conditions. These materials display different methane reforming activities, and remain free of praseodymium, samarium and gadolinium oxide phases respectively after use in a reaction gas stream composed of 50% CH4–5% H2O – (in the absence and presence of 50 or 200 ppm H2S) – balance He at 740 °C. The results show that Ce0.8Pr0.2O2 − δ, Ce0.85Sm0.15O2 − δ and Ce0.9Gd0.1O2 − δ are effective catalysts for reforming of methane and H2S in the feed promotes the catalytic activity. Ce0.8Pr0.2O2 − δ appeared to attain the highest activity for methane reforming, a feature that is associated with the ability of praseodymium to undergo a red–ox (Pr4 +/Pr3 +) and spreading action in the cerium oxide host structure, possibly resulting in a red–ox relationship between the components.

Graphical abstractMethane steam reforming over Ce0.8Pr0.2O2 − δ at 740°C in the absence and presence of H2S.Figure optionsDownload full-size imageDownload as PowerPoint slide