Synthesis and Characterization of Ordered CuO–CeO2 Mixed Oxides Using KIT-6 Silica as a Hard Template
Petar Djinović,a Urška Kocjan,a Jurka Batistaa and Albin Pintara,b,*
a Laboratory for Catalysis and Chemical Reaction Engineering,
National Institute of Chemistry, Hajdrihova 19, P.O. Box 660, SI-1001 Ljubljana,
Slovenia
b Chair of Chemical, Biochemical and Environmental Engineering,
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva
5, P.O. Box 537, SI-1001 Ljubljana, Slovenia
* Corresponding author: E-mail:
albin.pintar@ki.si;
Tel.: +386-1-47-60-237, fax: +386-1-47-60-300
Abstract
This study focuses on the synthesis of CuO–CeO2 mixed oxides
containing 10, 15 and 20 mol % CuO using hard template method with KIT-6 silica
acting as a template. The obtained solids exhibited ordered mesoporous structure,
which was identified by N2 adsorption/desorption and XRD analyses as
a negative mold of the KIT-6 silica pore system. The materials were additionally
characterized by H2-TPR/TPD, H2-TPR/TPO/TPR, selective N2O
chemisorption and NH3 chemisorption/TPD methods. These methods
revealed very high surface area being in the range of 147–166 m2/g,
depending on CuO content and calcination temperature. CuO dispersion values
between 28 and 40% were determined by N2O decomposition with
corresponding CuO particle size between 1.3 and 1.9 nm. H2/TPR-TPO-TPR
tests revealed negligible alterations in pore size/volume of calcined solids,
indicating good thermal stability of CeO2 framework under tested
conditions. On the other hand, migration and stabilization of surface CuO
clusters was detected upon redox cycling, which resulted in noticeable
differences in redox behavior. Nevertheless, the ordered and highly porous CuO–Ce-
O2 materials exhibited superior thermal stability, good redox
properties and surface acidity, which render hard template preparation method
very useful for the synthesis of ordered mesoporous mixed metal oxides with vast
possibilities for future applications in catalysis.
Keywords: Hard template synthesis method, KIT-6 silica, CuO–CeO2 mixed oxides