The utilization of the isotopic exchange technique in redox heterogeneous catalysis
Nicolas BION, CNRS permanent Researcher
Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP) – University of Poitiers / CNRS 4 rue Michel Brunet 86073 Poitiers Cedex 9 (FRANCE), nicolas.bion@univ-poitiers.fr
The phenomena of
surface active species mobility are crucial in catalysis : it may correspond to
one step of the catalytic mechanism or may influence the steps of activation
and regeneration of the catalysts. Therefore species migration play a key role
in numerous processes like the reforming reaction, the 3-way catalysis as well
as reactions involving a spillover of active species. The Laboratoire
de Catalyse en Chimie Organique (LACCO), recently re-organized in the Institut
de Chimie des Milieux et Matériaux de Poitiers (IC2MP) developed the isotopic
exchange technique, a powerful technique to study the reaction between gas
phase (oxygen or hydrogen) and metal oxide or oxide catalysts[1]. In such studies,
two general reaction types have been investigated: (i) homomolecular exchange
in which a mixture of labeled molecules is scrambled over a surface, and (ii)
heterolytic exchange in which a labeled molecule is scrambled with the
“lattice” atom of the catalyst isotopes). From the curves which register the
partial pressures of the different isotopomers of the exchanged molecules,
information on the exchange mechanism and on surface and bulk diffusion
coefficient of active species can be obtained. Coupling this technique with
spectroscopic characterization techniques such as FTIR or NMR gives
complementary data on the nature of the active species or the active sites in
the exchange process. In the seminary,
earlier studies dealing with the oxygen mobility in ceria-based 3-way catalysts
will be presented. Some more recent works carried out in oxidation catalysis
(CO PrOx, CH4
combustion,
partial oxidation of CH4) will be also
exposed.
[1] D.
Duprez, Isotopes in Heterogeneous Catalysis, Catalytic Science Series Vol. 4,
Imperial College Press, London, 2006, 133 –181.
日時:2014年5月30日(金)開催
場所:名古屋工業大学先進セラミックス研究センター旭ヶ丘地区講義室
(研究会の様子) (全体写真)
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