ISSN 0012-5008, Doklady Chemistry, 2009, Vol. 424, Part 2, pp. 27–30. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © V.Sh. Fel’dblyum, T.N. Antonova, N.S. Zefirov, 2009, published in Doklady Akademii Nauk, 2009, Vol. 424, No. 4, pp. 489–492.
CHEMISTRY
Cyclization and Dehydrocyclization
of C5 Hydrocarbons over Platinum Nanocatalysts
and in the Presence of Hydrogen Sulfide
V. Sh. Fel’dblyuma, T. N. Antonovaa, and Academician N. S. Zefirovb
Received July 15, 2008
DOI: 10.1134/S0012500809020025
Transformation of aliphatic C6–C8 hydrocarbons perse platinum catalyst onAl2O3 or SiO2 and (ii) hydro-
into cyclic ones (mainly benzene and its homologues) gen sulfide as an initiator [6].
is well studied for a long time due to works by
N.D. Zelinskii and his school [1]. In the case of C6
hydrocarbons, such as n-hexane and n-hexenes (and
RESULTS AND DISCUSSION
higher linear hydrocarbons), the use of platinum dehy-
drocyclization catalysts affords aromatic hydrocarbons
in reasonable yields and the corresponding technologi-
cal process (“platforming”) was accomplished in indus-
try long ago.
Dehydrocyclization of piperylene over heteroge-
neous platinum nanocatalysts. We developed a proce-
dure for the preparation of a new supported platinum
catalyst under conditions providing a high degree of
dispersion of deposited platinum. The choice of the
method agrees with the recent studies on nanocatalyst
preparation [7]. In particular, the preparation of 2.2-nm
platinum nanoparticles by reduction of platinum salts
with alcohols and their use as hydrogenation catalysts
has been reported [8]. To obtain platinum nanoparti-
cles, we used the reduction or thermal decomposition
of metal complexes [9, 10]. The platinum-on-alumina
catalyst (2% Pt on Al2O3) was prepared by impregna-
tion of calcined Al2O3 grains with an aqueous solution
of chloroplatinic acid H2[PtCl6] followed by drying at
100°C and activation in a hydrogen flow at 400–500°C.
Samples of the platinum-on-silica catalyst (2% Pt on
SiO2) were obtained by our procedure via impregnation of
calcined silica gel grains with a benzene solution of tet-
rakis(triphenylphosphine)platinum(0) Pt[(C6H5)3P]4 and
tetrakis(triphenyl phosphite)platinum(0) Pt[(C6H5O)3P]4
in a carefully purified nitrogen atmosphere followed by
removal of benzene in vacuo and thermal activation at
150–200°C in a nitrogen flow.
However, the yields of dehydrocyclization products
from C5 hydrocarbons are very low when common plat-
inum catalysts are used. Nonetheless, the cyclization of
C5 hydrocarbons is a rather new field of research of
practical interest. Indeed, C5 cyclic products, such as
cyclopentadiene (CPD), its dimer (dicyclopentadiene,
DCPD), cyclopentene (CPE), and cyclopentane (CPA)
are used for synthesizing various products with valu-
able properties [2]. One of the interesting fields in the
application of CPD and DCPD is the synthesis of
strained hydrocarbons [3, 4]. Recently, an interest is
shown in the epoxidation of DCPD for further prepara-
tion of synthetic resins, additives to petroleum prod-
ucts, etc. [5].
At present, CPD and DCPD are isolated from the
by-products of gasoline pyrolysis and coal carboniza-
tion. The extension of sources is possible only using
synthetic methods. In this context, the synthesis of
cyclic C5 hydrocarbons by the cyclization of linear pre-
cursors becomes urgent.
Under these conditions, we obtained a highly dis-
persed platinum catalyst with the expected increased
1
activity. The control analyzes of the samples of plati-
In this work, we have studied the dehydrocycliza-
tion of C5 hydrocarbons—piperylene (pentadiene-1,3),
pentenes, and pentane—with the use of (i) nanodis-
num on silica gel prepared by the above procedure
showed that the samples contain nanoparticles with
sizes in the range 3–7 nm. This corresponds to nano-
sized Ptn clusters (1 ≤ n ≤ 20) containing valence-unsat-
urated platinum atoms. These nanocatalysts stabilized
a Yaroslavl State Technical University, Moskovskii pr. 88,
Yaroslavl, 150023 Russia
b Moscow State University, Moscow, 119992 Russia
1
We are grateful to Professor G.R. Kotel’nikov (Yarsintez
Research Institute) for his help in analyzing the samples of the
catalysts by electron microscopy.
27