II International Symposium on Carbon for Catalysis ABSTRACTS

PP-I-11
We suppose that the active OCP are the three-dimensional polymer presented by
graphitized and condensed aromatic structures cross-linked by alkyl or sulfur bridges. The
quinone, C=S, lactone, carboxyl, and alkyl groups in oxidative condensation products were
detected by DRIFTS. There are probably the terminal substituents of polynuclear structures.
The sulfate groups were found at the surface of carbonized alunima.
The catalytic properties of OCP depends on the oxygen functional surface groups
composition. It is not revealed lactone groups in deactivated coke.
The coke morphology on the surface of silica is significantly different from one on
alumina or Si - Al oxides. Aggregated clusters of OCP were formed on silica, but total
coverage of coke was formed on alumina surface.
It was found that the acidity of oxide catalysts influence on the accumulating coke
condensation. The OCP having a lower degree of condensation and less C/H ratio (1:0,6 for
OCP/γ-Al 2 O 3 ) was formed at the week acidic sites. At the strong acidic sites of Al-Si catalysts
was formed the coke with more C/H ratio (1:0,3). It was found that the maximum exothermic
effect of coke burning increases with increasing the strength of Lewis acidic centers for
Al-Si-O catalysts (Fig. 2). The OCP/silica samples are the most selective catalysts. The
highest selectivity to propene and selectivity to alkenes (propene and ethene) are 74,5% and
85% at the propane conversion of 35% in the oxidative dehydrogenation of propane by SО 2 .
-CH 3
, >CH 2 Ar-H
4
-CH 3
, >CH 2
>C=O
1
880
F (R)
2
0
-C=Cin
Aromatic
1400 1600 1800
0
2850 3000
-C(O)-O-C-
0,5 wt.%
3,5 wt.%
ν,см -1
9 wt.%
T max
, K
860
840
820
30 40 50
Q CO
, kJ/mol
Fig.1. The coke transformation in course of
carbonization of silica.
Fig. 2. The dependence of the T max of OCP
on oxides Lewis acidic centers strength.
References
1 Niva, M., Sago, M., and Murakami, Y., J. Catal., 69 (1981), 69.
2 Alkhazov, T.G. and Lisovskii, A.E., Oxidative Dehydrogenation of Hydrocarbons,
Moscow: Khimiya, 1980.
3 Danilova, I.G., Paukshtis, E. A., Kalinkin, A. V. et all.: Kinetics and Catalysis, 43 (2002),
747.
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