Catalytic and redox properties of bimetallic Cu-Ni systems combined with CeO2 or Gd-doped CeO2 for methane oxidation and decomposition

Two catalysts combining Cu-Ni with CeO2 and Gd-doped CeO2, respectively, are comparatively examined with respect to redox and catalytic properties towards interaction with CH4. For this, catalysts in oxidised starting states are explored by means of CH4-TPR tests up to 973 K. Characterization of initial and final states of the catalysts is accomplished by means of XRD, Raman spectroscopy and EXAFS while carbon deposits formed during interaction with CH4 are examined by TPO, Raman spectroscopy and SEM-EDX. Oxygen handling characteristics of the catalysts are examined by means of oxygen isotopic exchange experiments. In turn, redox changes produced during the course of CH4-TPR tests are explored by operando-XANES. Methane oxidation or decomposition processes are observed as a function of redox state of the catalysts and sites involved in each of the processes are identified on the basis of the multitechnique approach employed. (C) 2011 Elsevier B.V. All rights reserved.