1070-4272/03/7607-1083$25.00C 2003 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 76, No. 7, 2003, pp. 1083!1088. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 7,
2003, pp. 1116!1121.
Original Russian Text Copyright + 2003 by Erofeev, Adyaeva.
Transformations of Straight-Run Naphthas
on Indium-Modified Pentasils
V. I. Erofeev and L. V. Adyaeva
Department of Scientific and Technical Development, Tomsk Petrochemical Plant,
Joint-Stock Company, Tomsk, Russia
Institute of Petroleum Chemistry, Siberian Division, Russian Academy of Sciences, Tomsk, Russia
Received January 14, 2003
Abstract-The influence exerted by the procedure of introducing indium into high-silica zeolite of the Pen-
tasil type on its acid properties and catalytic activity in transformation of straight-run naphthas into lower
olefins and aromatic hydrocarbons was studied.
Catalytic pyrolysis is one of the most promising
procedures for commercial production of lower ole-
fins. Zeolite-containing catalysts based on high-silica
zeolites (HSZs) of the Pentasil type are widely used
in oil refining and petroleum chemistry. It is known
 that the activity and selectivity of HSZs of the
Pentasil type in transformations of various classes of
hydrocarbons are determined not only by acid proper-
ties, but also by unique molecular-sieve properties of
these zeolites. It was shown previously  that the
acid properties of any zeolite-containing catalyst cor-
relate with its catalytic activity in transformation of
hydrocarbon raw materials into definite target prod-
ucts. One of the possible ways of controlling the acid
and catalytic properties, along with appropriate pre-
treatment, is introduction of modifying elements into
the zeolite matrix.
In this work we studied how the procedure of intro-
ducing indium affects the acid properties of HSZs of
the Pentasil type in transformation of straight-run
naphthas into lower olefins and arenes.
Experiments were performed with straight-run
naphtha (SRN) from the Surgut Gas-Processing Plant.
This raw material belongs to the paraffin-naphthenic
type (onset of boiling at 131oC, density at 20oC
). The hydrocarbon composition of the
SRN is as follows (wt %): n-paraffins 29.7, branched
paraffins 27.2, and naphthenic hydrocarbons 32.8.
High-silica zeollites of the ZSM-5 type with the
silicate ratio SiO
) = 30 were pre-
pared by hydrothermal synthesis from alkaline alumi-
nosilica gels by the procedure described in . The
substances were identified by IR spectroscopy and
X-ray phase analysis (Mo anode, Ni filter).
The modifier, In(III) (1 wt % in terms of the met-
al), was introduced by the following procedures: im-
pregnation of the zeolite matrix with an indium nitrate
solution (In-HSZ-1), ion exchange of H-HSZ with
In(III) (In-HSZ-2), mechanical mixing of ultradis-
persed indium powder with H-HSZ followed by the
heat treatment (In-HSZ-3), mechanical mixing of
indium nitrate with H-HSZ followed by heat treatment
(In-HSZ-4), and hydrothermal crystallization of a
mixture containing aluminum and indium nitrates.
By the latter method, we prepared Pentasils with the
framework Al atoms isomorphously substituted by
In(III) to 10 (IAS-10 sample) and 20 wt % (IAS-20
The acid properties of HSZ samples modified with
In(III) were studied by temperature-programmed de-
sorption of ammonia. This method furnishes informa-
tion about the content and strength distribution of
acid centers .
The catalytic properties of In(III)-modified HSZs in
transformation of straight-run naphthas were studied
in a flow-through installation with a fixed catalyst bed
) at atmospheric pressure in the temperature
range 500 3700oC; the feed space velocity was 3 h
The hydrocarbon composition of the starting SRN and
reaction products was determined by gas chromatog-
raphy. The error in gas-chromatographic determina-
tion of the yield of SRN transformation products and
of the content of acid centers in the catalysts was
All the HSZ samples synthesized, according to IR