Structural, catalytic/redox and electrical characterization of systems combining Cu–Fe with CeO2 or Ce1−xMxO2−δ (M = Gd or Tb) for direct methane oxidation

The present work analyses bimetallic Cu–Fe formulations combined with CeO2 or other structurally related mixed oxides resulting from doping of the former with Gd or Tb, focusing to its possible use as anodes of solid oxide fuel cells (SOFC) for direct oxidation of methane. The main objective is the characterization of the various formulations at structural level as well as with regard to redox changes taking place in the systems upon interaction with methane, in order to evaluate the effects induced by the presence of the mentioned dopants. In the same sense, an analysis of thermal expansion and electrical properties of the systems as well as their chemical compatibilities with several electrolytic materials is performed, considering its possible implantation in SOFC single cells. For the mentioned purposes, the systems have been analysed by means of CH4-TPR tests subsequently followed by TPO tests, as well as by XRD, Raman and XPS, with the aim of exploring structural and redox changes produced in the systems and the formation of carbon deposits during interaction with methane. The results reveal significant modifications in the structural, catalytic/redox and electrical properties of the systems as a function of the presence of Fe and/or Gd and Tb dopants in the formulation.