Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 1, pp. 32−37.
Pleiades Publishing, Ltd., 2009.
Original Russian Text
T.N. Afonasenko, P.G. Tsyrul’nikov, K.N. Iost, V.L. Temerev, D.A. Shlyapin, A.B. Ayunov, D.F. Khabibullin, 2009, published in Zhurnal
Prikladnoi Khimii, 2009, Vol. 82, No. 1, pp. 34−39.
OF SYSTEMS AND PROCESSES
Effect of the Acidity of a Zeolite and Its Modiﬁ cation
with Cerium and Zirconium on the Activity
and Thermal Stability of Pd/beta in the Reaction
of Deep Toluene Oxidation
T. N. Afonasenko, P. G. Tsyrul’nikov, K. N. Iost, V. L. Temerev,
D. A. Shlyapin, A. B. Ayunov, and D. F. Khabibullin
Institute of Problems of Hydrocarbon Processing, Siberian Branch, Russian Academy of Sciences, Omsk, Russia
Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Received May 16, 2008
Abstract—Acidities of beta zeolites with various moduli and the catalytic activities of Pd/beta in the reaction of
deep toluene oxidation were compared.
It is known that ecologically important reactions
of carbon monoxide oxidation and afterburning of
hydrocarbons widely use supported palladium catalysts
in which aluminum oxide and zeolites frequently serve
as supports [1, 2]. The practical importance of these
catalysts has particularly increased recently because
of the rise in the price of platinum. As a result, a most
important task for manufacturers of catalysts for
detoxication of automobile exhaust gases is to replace
platinum in catalysts with palladium to a greater extent.
In modern automobiles equipped with afterburners, most
part of the hydrocarbon exhaust (~80%) is produced
at the so-called “cold start” , with the most noxious
part of the exhaust composed of aromatic compounds.
It is for this reason that the reaction of deep toluene
oxidation is used as a test reaction for assessment of
Typical catalysts for deep oxidation of hydrocarbons
-supported palladium catalysts. The electronic
state of palladium in these catalysts widely varies with
the preparation and process conditions. If the reaction
mixture contains an excess amount of oxygen, palladium
may be simultaneously present as crystals of metallic
palladium, phase oxide PdO, and Pd–Al
phases” [4, 5]. Presumably, it is correct to designate these
catalysts as PdO
, where x may vary from 0 to 1.
A disadvantage of this catalyst is in its comparatively
low activity at temperatures below 300°C. Promising
for the low-temperature range are Pd-zeolite catalysts,
which exhibit high activity and thermal stability . An
increase in the thermal stability of catalysts supported by
 and zeolites  is favored by presence in their
composition of zirconium(IV) and cerium(IV) oxides,
which preclude a decrease in the speciﬁ c surface area of
the support on raising the calcination temperature and
prevent caking of particles of the active component.
In view of the promise shown by palladium catalysts
on zeolite supports, the aim of this study was to examine
the activity and thermal stability of Pd–zeolite catalysts
in the reaction of deep toluene oxidation and to determine
how addition of cerium and zirconium oxides affects the
As supports served zeolites of the beta structural type
with silicate moduli (SiO
) of 11 and 25 (Angara
Plant of Catalysts and Organic Synthesis Open Joint-
Stock Company) and 36 (Tosoh, USA), preliminarily
calcined at 600°C for 4 h.