Russian Journal of Applied Chemistry, Vol. 78, No. 1, 2005, pp. 96 100. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 1,
2005, pp. 97 101.
Original Russian Text Copyright
2005 by Kuz’mina, Liventsev, Sevost’yanov, Dogadina.
CATALYSIS
Modification of the Alumina-Supported Platinum
Catalyst of Reforming
R. I. Kuz’mina, V. T. Liventsev, V. P. Sevost’yanov, and N. V. Dogadina
Chernyshevsky Saratov State University, Saratov, Russia
Saratov Oil Refinery, Open Joint-Stock Company, Saratov, Russia
Received June 1, 2004
Abstract The catalytic activity of alumina-supported platinum catalysts modified with rare earth metal
(samarium, europium, gadolinium, ytterbium, yttrium) complexes in C6 hydrocarbon reforming was studied.
Production of aromatic hydrocarbons, in particular,
benzene, which is a raw material for chemical indus-
try, is an important direction of the catalytic reform-
ing, since the production of polyamide, polyester, and
other fibers and, in addition, some types of plastics
and specialty rubbers is based on conversion of ben-
zene and its nearest homologs.
ytterbium, or yttrium were considered. The activity of
the catalysts was evaluated by the content of benzene
(aromatization) and C C hydrocarbons (hydrocrack-
ing) in the catalyzate. We found that the catalytic
activity of the modified catalysts decreases in the
order Gd > Y > Eu > Sm > Yb (Table 1).
1
5
The catalysts that were more active in aromatiza-
tion also showed the elevated selectivity. Taking this
into account, we studied the properties of the gadoli-
nium-containing catalyst in the n-hexane conversion
in more detail and found that, in the presence of the
catalyst with gadolinium additives (0.1 0.4 wt %),
the yield of benzene is higher than in the case of
the REM free alumina-supported platinum catalyst
(Figs. 1, 2). Although the Gd-modified alumina-sup-
ported platinum catalyst is characterized by the ele-
vated activity in hydrocracking, the ratio of the ben-
zene concentration to the total concentration of C C
Alumina-supported platinum catalysts, which were
for many years the main catalysts of hydrocarbon
aromatization, now give place to the catalytic systems
with a low platinum content, containing other metals
(iridium, rhenium, germanium, tin) as modifiers [1].
Modifying additives introduced into the platinum
catalyst can affect the properties of both active metal
itself and a support. With regard to bifunctionality
of the alumina-supported platinum catalyst, whose
platinum catalyzes hydrogenation and dehydrogena-
tion, while alumina catalyzes paraffin isomerization
and hydrocracking, we took rare-earth metals (REMs)
differing in the dehydrogenation and dehydrocycliza-
tion power as modifying additives [2]. It was interest-
ing to find how the initial REM compound affects
the catalyst activity.
1
5
hydrocarbons [C H ]/ (C C ) on the gadolinium-
6
6
1
5
modified alumina-supported platinum catalyst is also
higher than on the unmodified alumina-supported
platinum catalyst, which indicates higher selectivity of
the former in the aromatization.
Table 1. Influence of REMs on catalytic properties of the
alumina-supported platinum catalyst at 500 C
EXPERIMENTAL
Composition of reaction product, wt %
REM
The catalyst properties were studied with a flow-
type laboratory device within 440 540 C in a hydro-
gen atmosphere. n-Hexane was used as a feed in re-
forming.
C1 C5 iso-C6H14 MCP* C6H6 C6H6/ C1 C5
Sm
Eu
Yb
Gd
Y
10.1
12.2
9.8
22.0
20.0
20.1
20.3
17.7
28.7
28.1
17.5
19.9
21.6
8.1
5.5
10.6
3.6
30.4
15.2
0.5
0.9
0.4
1.4
0.7
To study the influence of REMs on the alumina-
supported platinum catalyst and to develop a high-
performance catalyst with a low platinum content,
a series of catalysts containing 0.25 wt % platinum
and 0.1 0.4 wt % samarium, europium, gadolinium,
10.1
* Methylcyclopentane.
1070-4272/05/7801-0096 2005 Pleiades Publishing, Inc.