In situ simultaneous synchrotron powder diffraction and mass spectrometry study of methane anaerobic combustion on iron-oxide-based oxygen carriers

Reduction of iron oxide/CeO2 solid due to methane anaerobic combustion has been studied using in situ time-resolved synchrotron X-ray powder diffraction and mass spectrometry measurements. All the chemical reactions involved in the process have been mapped. Rietveld profile fitting analysis has given a quantitative estimation of the different phases at every step of the reaction. The reaction temperature has been estimated using thermal expansion of both Fe2O3 and CeO2. From the structural parameters of CeO2 it has been possible to claim that CeO2 participates in the reduction process by transforming into a reduced CeO x form. The number, x, of O atoms per formula unit has been estimated by measuring the percentage variation of the unit-cell parameters.