ОС-23: Sonochemical Synthesis of (Ce,Zr)O2 Based Nanocatalysts

Oral Communications
ESS-13
ОС-23: Sonochemical Synthesis of (Ce,Zr)O 2 Based Nanocatalysts
Camille Cau a,b , Yannick Guari b , Tony Chave a , Joulia Larionova b , Sergey I. Nikitenko a*
a Institut de Chimie Séparative de Marcoule (ICSM),
UMR 5257 – CEA – CNRS – UMII - ENSCM, Centre de Marcoule,
BP 17171, 30207 Bagnols sur Cèze, Cedex, France
b Institut Charles Gherhardt (ICG), UMR 5253 – UMII – UMIII – CNRS – ENSCM, Université de Montpellier II,
Bât 17 – CC 1700, 34095 Montpellier Cedex 5
* serguei.nikitenko@cea.fr
Ceria-zirconia mixed oxide (Ce,Zr)O 2 is mainly used as a three-way catalyst for vehicles (Kaspar et al.
1999), as a material for intermediate-temperature solid oxide fuel cells(Murray et al. 1999), and as a catalyst for wet
air oxidation (WAO) of organic pollutants (Leitenburg 1996). The redox properties and the oxygen storage capacity
of this material strongly depend on the method of its synthesis. Herein, we reported the preparation of high-surface
area Ce 0,5 Zr 0,5 O 2 oxide via the thermolysis and sonolysis of Ce(III) and Zr(IV) β-diketonates in organic solvents.
The catalytic activity of obtained oxide doped with Pt nanoparticles was tested in WAO of formic acid.
1. Experimental part
1.1. Thermolysis
For those syntheses, two solvents were chosen (oleylamine and hexadecylamine) with different ratios R of
solvent/precursors (263 and 106). Therefore 8 samples where obtain named after the synthesis method employed (M
or S), the solvent used (O or H) and the R used (263 or 106). Cerium acetylacetonate and zirconium acetylacetonate
in stoichiometric quantity were placed in a determinate volume of solvent under argon. To eliminate volatile
impurities, the reagents were heated under continuous stirring at 100 °C during 1h under vacuum. Afterwards, the
compounds were heat at 285 °C during 1h under argon. Methanol is added to the mixture to precipitated
Ce 0.5 Zr 0.5 O 2 . After being centrifuged, washed and dried, the products were calcinated at 450°C during 2h on air. The
obtained mixed oxides were called MO 263, MO 106, MH 263 and MH 106.
1.2. Sonochemical synthesis
Cerium acetylacetonate and zirconium acetylacetonate in stoichiometric quantity were placed in a
determinate volume of solvent sparged with Ar at a 100 ml.min -1 rate maintained during the ultrasonic treatment.
The mixture was then irradiated with a high-intensity ultrasonic probe during 3 h (20 kHz, I=?). The temperature
was stabilized at 198 °C after 1h30 of treatment. After being centrifuged, washed and dried, the products were
calcinated at 450°C during 2h on air. The obtained mixed oxides were called SO 263, SO 106, SH 263 and SH 106.
2. Support characterizations
In order to know if the stoichiometry between the reaction mixture and the obtain materials was conserved,
the products was first analyzed by EDX. Then, to confirm the formation of Ce 0,5 Zr 0,5 O 2 mixed oxide, and not a two
simple oxides intimate mixture, different characterization methods were used. The analyzes of X-ray diffraction
(XRD) and Raman spectroscopy, showed the formation of crystallized mixed oxide with 0.5/0.5 Ce/Zr ratio
(Figure 1)
The specific surface area of obtained products was measured by the BET method and the highest was
obtained for MO 106 (149m²/g). To compare the influence of the synthesis method, the rest of the study was equally
made with SO 106 (107 m²/g). The observation of the both materials by transmission electron microscopy (TEM)
shows nanoparticles of respectively 3-4 nm and 1-2 nm for MO 106 and SO 106 (Figure 2).
Platinum was then deposited under the both supports and a cerium oxide CeO 2 take as a reference by
sonochemical reduction of Pt(IV) in formic acid. The catalytic activities of the catalysts were tested by the formic
acid degradation and following by TOC meter. The both catalysts obtained from the β-diketonate degradation have a
faster degradation of formic acid. The highest activity was obtained with SO 106.
13 th Meeting of the European Society of Sonochemistry
73
July 01–05, 2012, Lviv – Ukraine
Lviv Polytechnic National University Institutional Repository http://ena.lp.edu.ua

ESS-13
Oral Communications
(a)
(b)
Figure 1: XRD profiles (a) and Raman spectra (b) of the Ce0,5 Zr0,5O2
prepared by the thermal and sonochemical routes
Figure 2: TEM of (a) MO 106 and (b) SO 106
Conclusion
For the first time, the synthesis of nanosized Ce 0,5 Zr 0,5 O 2 was realized by β-diketonate decomposition
induced by ultrasounds. Although this material has a lower specific area than the ones prepared by the thermolysis,
its catalytic activity was found to be higher. .
This study shows the importance of the synthesis parameters as the solvent choice or the reagents ratio.
References
Kašpar J., Fornasiero P., Graziani M., 1999, Use of CeO 2 -based oxides in the three-way catalysis, Catalysis
today 50, 285-298
Leitenburg C., Goi D., Primavera A., Trovarelli A., Dolcetti G, 1996, Wet oxidation of acetic acid catalyzed
by doped ceria, Applied catalysis 11, 29-35
Murray E.P., Tsai T.Barnett S.A, 1999, A direct-methane fuel cell with a ceria-based anode, Nature 400, 649-
651
74
13 th Meeting of the European Society of Sonochemistry
July 01–05, 2012, Lviv – Ukraine
Lviv Polytechnic National University Institutional Repository http://ena.lp.edu.ua