ISSN 0036ꢀ0244, Russian Journal of Physical Chemistry A, 2010, Vol. 84, No. 7, pp. 1122–1126. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © A.L. Tarasov, O.A. Kirichenko, N.N. Tolkachev, I.V. Mishin, A.N. Kalenchuk, V.I. Bogdan, L.M. Kustov, 2010, published in Zhurnal Fizicheskoi Khimii,
2010, Vol. 84, No. 7, pp. 1244–1248.
CHEMICAL KINETICS
AND CATALYSIS
The Influence of the Dispersion of Metals on the Activity of Pt/C
and Pd/C Catalysts in the Dehydrogenation of Perhydroterphenyl
A. L. Tarasov, O. A. Kirichenko, N. N. Tolkachev, I. V. Mishin, A. N. Kalenchuk,
V. I. Bogdan, and L. M. Kustov
Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Leninskii pr. 47, Moscow, 119991 Russia
eꢀmail: lmk@ioc.ac.ru; bogdan@ioc.ac.ru
Received May 12, 2009
Abstract—The activity of Pt/C and Pd/C catalysts in the dehydrogenation of perhydroterphenyl was studied
at conversions lower than 30% depending on the dispersion of platinum and palladium metals, which was
estimated by two independent methods (adsorption of CO and Xꢀray diffraction).
DOI: 10.1134/S0036024410070071
INTRODUCTION
determining the effectiveness of a catalyst for use in
devices for hydrogen storage and should be taken into
account in its development.
Hydrogen and systems for its storage attract ever
increasing interest in relation to the search for new
energy sources and creation of environmentally
friendly transport and fuel cells. One of the methods
for the storage of hydrogen [1] is based on performing
reversible hydrogenationꢀdehydrogenation of conꢀ
densed aromatic compounds in catalytic composite
systems. Substrates can be accessible chemical comꢀ
pounds containing aromatic nuclei (condensed and
polycyclic and aromatic polymers, for instance,
polyphenylenes) capable of being reversibly and mulꢀ
tiply hydrogenatedꢀdehydrogenated. Perhydroterpheꢀ
nyl (PHT) is most promising in this respect [2]. These
materials have exceedingly high capacities with
respect to hydrogen, of ~6–8 wt %.
The specific catalytic activity of metallic supported
catalysts can change substantially as the size of metal
nanoparticles changes depending on the type of the
reaction. For structurally sensitive reactions, which
supposedly occur on ensembles of atoms on the surꢀ
face of metals, and which include aromatic compound
hydrogenationꢀdehydrogenation reactions, the activꢀ
ity of a catalyst depends on the structure of the surface
of the metal and is determined not only by the total
number of surface metal atoms accessible to the reacꢀ
tion.
The purpose of this work was to compare catalytic
activity in the dehydrogenation of perhydroterphenyl
In was shown [3] that catalysts containing noble with the results of physicochemical studies of catalysts
metals (Pt, Pd, etc.) on carbon carriers with high speꢀ and reveal the rules that governed the influence of the
cific surface areas (for instance, Sibunite and activated size of nanoparticles on specific catalytic activity. The
carbon) are of the greatest interest for the storage of catalysts were synthesized using original procedures
hydrogen in catalytic composite materials. A high developed by the authors.
activity of catalysts, which provides a short time of
hydrogen discharge from devices for its storage and the
EXPERIMENTAL
possibility of decreasing the temperature of the proꢀ
cess, is most important. A high selectivity is the condiꢀ
tion of the possibility of multiply using these systems
without substrate loss, which is possible if side crackꢀ
Catalysts and Preparation
The influence of the dispersion of platinum and
ing, hydrogenolysis, and coke formation processes palladium on the dehydrogenation of PHT was studied
occur. The catalytic activity of Pt and Pd catalysts in using a series of catalysts containing 1 wt % platinum
the hydrogenation [3] and dehydrogenation [4] of or palladium on Sibunite carbon carrier. All the methꢀ
some substrates depends on the dispersion of the supꢀ ods for depositing palladium and platinum were based
ported metal. The question of the influence of the size on the deposition of metal precursors from aqueous
of metal nanoparticles on their catalytic activity in the solutions of chloride complexes followed by reduction
dehydrogenation of polycyclic naphthene hydrocarꢀ with hydrogen. The dispersion of metals was varied by
bons is therefore of considerable interest for both funꢀ the method and conditions of the deposition of the
damental science (for the determination of the mechꢀ corresponding metal salt (Table 1). The initial reagents
anism of the reaction) and practical applications, were PdCl2 and a solution of H2PtCl6 ( (Pt) = 36.3%)
ω
because this dependence is one of the main parameters of ch. (pure) grade. Solutions of H2PdCl4 were preꢀ
1122