INVESTIGADORES
BONIVARDI Adrian Lionel
artículos
Título:
Preparation and structural characterization of Zn and CeO2 nanocomposite materials as catalytic supports
Autor/es:
C. BARRIOS; M. BALTANÁS; R. BOLMARO; A. BONIVARDI
Revista:
POWDER TECHNOLOGY
Editorial:
ELSEVIER SCIENCE SA
Referencias:
Lugar: Amsterdam; Año: 2014 vol. 267 p. 180 - 192
ISSN:
0032-5910
Resumen:
Cerium(IV) and zinc(II) oxide nanocomposite powders (Zn-to-Ce atomic
ratio between 0.5 and 2) as well as the pure oxides were prepared by
co-precipitation of cerium(III) and zinc(II) cations with oxalate (OC)
or carbonate anions (CC), as active catalytic supports for the steam
reforming of methanol (SRM) reaction. After the study of the
decomposition of the precipitates in oxidizing atmosphere by
thermogravimetry, differential scanning calorimetry,
temperature-programmed oxidation (using infrared and mass spectrometry)
and X-ray diffraction, a global reaction pathway for the decomposition
of each type of precipitates was proposed. The nanostructural
characterization of the calcined composites at 723K was followed by
refined XRD analysis. It was possible to conclude that Zn(II) was not
incorporated into the ceria lattice in any case. The size of the CeO2 crystals was rather constant (~10?15nm) in all the ZnO?CeO2
nanocomposite powders, just as in the pure ceria (13?14nm).
Instead, the crystalline domains of ZnO were smaller in the
nanocomposites than in pure zinc oxide (31?78 vs. 103?118nm,
respectively), and even smaller in the CC than in the OC materials
(31?38 vs. 57?78nm for CC vs. OC, respectively). Upon the incorporation
of palladium to the oxides, to provide the metallic function on the
catalysts, the carbonate-derived composites showed a better catalytic
performance for the SRM reaction. Said improvement (in terms of percent
selectivity to CO2) could be attributed to the improved dispersion of zinc oxide achieved on the CC nanocomposites.