1070-4272/03/7602-0229 $25.00 C 2003 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 76, No. 2, 2003, pp. 229!233. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 2, 2003,
Original Russian Text Copyright + 2003 by Lamberov, Romanova, Sitnikova, Gil’manov, Trifonov.
Changes in the Composition, Structure, and Activity
of Catalysts in Hydrogenation of Diene Hydrocarbons
of the C
Fraction of Pyrolysis Naphtha
A. A. Lamberov, R. G. Romanova, E. Yu. Sitnikova, Kh. Kh. Gil’manov, and S. V. Trifonov
Kazan State Technological University, Kazan, Tatarstan, Russia
Nizhnekamskneftekhim Open Joint-Stock Company, Nizhnekamsk, Tatarstan, Russia
Received June, 13, 2002
Abstract-A comparative study was performed of changes in the composition, structure, and catalytic activity
of catalysts in selective hydrogenation of C
fraction of pyrolysis naphtha. The main reasons for catalyst
deactivation in the course of industrial exploitation were considered.
At present, the stringent requirements are imposed
on the quality and purity of pyrolysis naphtha frac-
tion, in particular, on the content of diene hydrocar-
bon impurities. One of the most widespread methods
for removing such impurities is catalytic hydrogena-
tion . Catalysts containing palladium supported by
aluminum oxide are the most efficient in hydrogena-
tion of diene hydrocarbons . In spite of success-
ful exploitation of these catalysts in hydrogenation of
diene, the decrease in the catalyst activity is a serious
problem. Unfortunately, the reasons for catalyst de-
activation have not been analyzed previously, and
here we try to fill this gap.
It is known  that deactivation can occur because
of catalyst poisoning with toxic inorganic substances.
Another reason is blocking of the active centers of
the catalyst surface through deposition of coke.
In this work, we studied deactivation of catalysts
for selective hydrogenation of dienes of the C
Samples of a deactivated catalyst were taken from
various levels of a reactor, as shown in the scheme
Low-temperature nitrogen adsorption, IR spectros-
copy, thermogravimetry, photocolorimetry, X-ray fluo-
rescence analysis, emission spectroscopy, and chemi-
cal analysis were used to study the composition, struc-
ture, and surface characteristics of the catalyst.
The specific surface area, porosimetric volume, and
pore volume distribution were measured by low-tem-
perature nitrogen adsorption on an ASAP-2400 Mi-
cromeritics device. To obtain adsorption-desorption
isotherms at 77 K, 0.831.0 g of the finely crushed cat-
alyst was placed in the analyzer ampule, which was
heated to 523 K, evacuated to 0.1 mm Hg for 4 h, and
then filled with nitrogen and weighed. Degassing was
performed to 0.03 mm Hg. In calculations, r(N
taken to be 0.808 g cm
, and the crosssection area of
the nitrogen molecule S, 0.1620 nm
. The pore vol-
ume and size distribution of pores were measured with
relative error of +13%, and the specific surface area,
with error of +3%. The curves of pore volume distri-
bution with respect to pore diameter were calculated
in terms of the cylindrical pore model .
Fig. 1. Scheme of the reactor and points of catalyst sampl-
ing (samples nos. 1311).