The document discusses guidelines for selecting and optimizing materials for electrochemical conversion of fuels. It addresses the reducing conditions imposed by fuels like hydrogen and methane. The stability limits of solid oxide fuel cell cathode materials and catalysts are examined under reducing atmospheres. Predictions of carbon deposition and strategies to minimize it, such as steam reforming and alternative catalysts, are also covered.

1. Guidelines for materials selection and optimization in electrochemical conversion of fuels J.R.Frade University of Aveiro, Portugal Economia de H 2 : Un desafio para Portugal, Vimeiro, Nov.17, 2008

2. Fuel cells Clean; High  Hydrocarbons Partial oxidation or Reforming e.g. CH 4 +1/2O 2  CO+2H 2 Electricity Chemicals Economia de H 2 : Un desafio para Portugal, Vimeiro, Nov.17, 2008 Purification H 2

4. Economia de H 2 : Un desafio para Portugal, Vimeiro, Nov.17, 2008 Reducing cnditions imposed by H 2 2H 2 + O 2  2H 2 O; Po 2 = (pH 2 O/pH 2 ) 2 exp(-  G/RT)

5. Economia de H 2 : Un desafio para Portugal, Vimeiro, Nov.17, 2008 Reducing cnditions imposed by CH 4 , ...

6. Economia de H 2 : Un desafio para Portugal, Vimeiro, Nov.17, 2008 Guidelines for redox tolerance of metallic electrocatalysts in H 2 atmospheres

7. Economia de H 2 : Un desafio para Portugal, Vimeiro, Nov.17, 2008 Stability limits of SOFC cathode materials and catalysts under reducing conditions 2LaMnO 3  La 2 O 3 + 2MnO + 1/2O 2 2LaCoO 3  La 2 CoO 4 + CoO + 1/2O 2 ...

8. Structural changes and property degradation under reducing conditions LSMCT2 = (La 0.55 Sr 0.45 ) 0.95 Mn 0.5 Cr 0.3 Ti 0.2 O 3-δ ; LSMCT4 = (La 0.35 Sr 0.65 ) 0.95 Mn 0.5 Cr 0.1 Ti 0.4 O 3-δ ... Economia de H 2 : Un desafio para Portugal, Vimeiro, Nov.17, 2008

9. Stability range estimated from sudden changes in conductivity and Seebeck coefficient. Stability limits Economia de H 2 : Un desafio para Portugal, Vimeiro, Nov.17, 2008

10. Typical dependence of ionic and electronic conductivity of CGO20 solid electrolytes Economia de H 2 : Un desafio para Portugal, Vimeiro, Nov.17, 2008

11. Predictions of methane conversion of ionic transport number and open cell voltage of a CGO-based cell Economia de H 2 : Un desafio para Portugal, Vimeiro, Nov.17, 2008

13. Economia de H 2 : Un desafio para Portugal, Vimeiro, Nov.17, 2008 Better S-tolerance Poorer S-tolerance Is thermodynamics useful to predict Sulphur tolerance?

15. Thermal expansion mismatch and ionic conductivity at 800ºC, in air Economia de H 2 : Un desafio para Portugal, Vimeiro, Nov.17, 2008 Composition       I ;S/cm T, K E a (kJ/mol) La 2 Ni 0.8 Cu 0.2 O 4+  13.3 0.11* - - LSFC 12.9 0.01 1073-1223 206 LSM 11.7 1.3  10 -5 - - LSFC - 50 wt% CGO 12.6 0.04 1023-1223 82 LSM - 50 wt% CGO 11.7 0.03 1023-1223 104 La 10 Si 5 AlO 26.5 9.1 0.08 973-1223 56

17. Chemical expansion under air/5%H 2 Economia de H 2 : Un desafio para Portugal, Vimeiro, Nov.17, 2008  L/L o;  E/(1-  ) for  =0.005  200MPa (risks of fracture!)

18. EDS spectra showing cation diffusion accross the CGO buffer layer in apatite/CGO/ LSMCT4 and LSGM/CGO/LSMCT4 arrangements Interdiffusion between cell materials Economia de H 2 : Un desafio para Portugal, Vimeiro, Nov.17, 2008