Contribution of Electron Microscopy to the characterization of ceria based catalysts

J.J. DELGADO; T. MONTINI; S. COLLINS; X. CHEN; A. BONIVARDI; H. PAN; J.J. CALVINO; E. DEL RÍO; M. LÓPEZ-HARO; I. ROMERO; P. FORNASIERO

Barcelona

Workshop; 3rd General Meeting COST Actin CM1104, Reducible oxide chemistry, structure and functions; 2014

It is unquestionable that one of the most important challenges of our society is thedevelopment of new energy strategies to tackle global warming and exhaustion of fossil fuels.In this context, catalysis has been proven as a critical enabling science for developing the useof alternative feedstocks, such as biomass or hydrogen, and increasing energy productionefficiency.Real catalysts commonly are complex multicomponent systems whose characterizationusually demands an insight at the atomic level, and they are continuously posing newchallenges and calling for further improvements in Electron Microscopy techniques. On theother hand, real catalysts contain morphological, structural and compositional heterogeneitiesand it is also obvious the need of developing new methodologies, based in statistical studies,that will give us a real picture of our catalyst. This point is really crucial for the rationalizationof structure-activity relationships and understanding the deactivation processes.The major goal of this contribution will be to review the possibilities of (Scanning)Transmission Electron Microscopy to reveal the ultimate details of the structure ofnanostructured catalysts and how this information allow us gaining some understanding ofhow they work as catalysts. Data obtained between the labs at University of Cadiz andUniversity of Trieste will be shown. We will specially focus on the use of an environmentalreaction cell specific for an anaerobic-transfer TEM holder is an alternative approach thatallows carrying out the pre-treatment of the sample under more realistic conditions andsubsequently transferring it to the TEM, under conditions which prevent any ulterior samplemodification. Although the dynamic aspects of the gas-solid interactions are lost in thisalternative approach, the characterization of those structural and compositional features whichare induced by realistic thermo-chemical treatments, which could be lost by interaction withair components but which are not reversed by evacuation or cooling, can be investigated.