Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 9, pp. 1339−1344.
Pleiades Publishing, Ltd., 2012.
Original Russian Text © T.L. Rakitskaya, T.A. Kiose, L.P. Oleksenko, L.V. Lutsenko, R.M. Dlubovskii, V.J. Volkova, 2012, published in Zhurnal Prikladnoi
Khimii, 2012, Vol. 85, No. 9, pp. 1422−1428.
AND CORROSION PROTECTION OF METALS
Inﬂ uence of Water Content in the Pd(II)–Cu(II) Catalyst Fixed
on Acid-Modiﬁ ed Basalt Tuff on Its Activity in the Carbon
Monoxide Oxidation by Oxygen
T. L. Rakitskaya, T. A. Kiose, L. P. Oleksenko, L. V. Lutsenko,
R. M. Dlubovskii, and V. J. Volkova
Mechnikov Odessa National University, Odessa, Ukraine
Taras Shevchenko Kiev National University, Kiev, Ukraine
Research Institute of Physics, Mechnikov Odessa National University, Odessa, Ukraine
Received February 9, 2012
Abstract—Samples of natural and acid-modiﬁ ed basalt tuff and also of the Pd(II)–Cu(II)/N-BT catalyst were
characterized by the methods of thermogravimetry and water vapor adsorption. It was shown that at the water
contents in the samples of the catalyst from 1.6 up to 7.2 wt % their activity in the reaction of low-temperature
CO oxidation by air oxygen decreases only by 2–4%.
One of disadvantages of catalysts (metallic, oxide,
and metal-complex) limiting their application in low-
temperature oxidation of carbon monoxide by oxygen,
for example, in environment and human protection, is
a possibility of their poisoning by water vapor . The
most promising catalysts based on Pd(II) and Cu(II)
halide complexes and various supports (SiO
natural zeolites, basalt tuffs, and disperse silica) are rather
sensitive to variation of water content in them, however
in this case, in contrast to oxide and metal catalysts,
it is possible to observe not only decrease [Pd(II)–
], but also increase [Pd(II)–Cu(II)/tripoli] in
the catalyst activity . Such complicated inﬂ uence of
water on the activity of the speciﬁ ed catalysts is caused
by different physicochemical properties of the supports
leading to a variation of thermodynamic activity of
adsorbed water (а
), which in turn inﬂ uences the
composition of surface complexes and, consequently,
their catalytic activity .
When zeolites are applied as supports the role of water
becomes more important because of its inﬂ uence on the
mobility of cations, and hence on their migration (self-
diffusion) and distribution in zeolite channels and cells
[3–5]. Furthermore, because of distinctions in heats of the
adsorption of water molecules, for example in the cases
of natural and chemically modiﬁ ed basalt tuffs (N-BT)
, it should be expected that after drying at 100–110°С
the samples of Pd(II)–Cu(II)/N-BT catalyst prepared by
the method of incipient wetness impregnation can differ
widely in residual water contents.
The purpose of the work was to determine limits of
water contents in Pd(II)–Cu(II)/N-BT catalysts, at which
their activity in the reaction of carbon monoxide oxida-
tion is maximal.
In the work we used samples of natural basalt tuff
(P-BT) from different deposits of Ukraine modiﬁ ed by
3 M HNO
within 6 h at 373 K (N-BT-6) and catalysts
of the composition K
[Pd(II)–Cu(II)/N-BT-6] obtained by impregnating
(Table 1). Techniques of the chemical BT modiﬁ cation
[acid-thermal processing and ﬁ xation of Pd(II) and Cu(II)
acido complexes] are described in the works [7, 8].
The standard sample of the catalyst was obtained by
the impregnating method [7, 9]. Damp friable samples
were held in a closed Petri dish at a room temperature