1070-4272/05/7809-1403+2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 9, 2005, pp. 1403!1407. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 9,
2005, pp. 1428!1432.
Original Russian Text Copyright + 2005 by Gaile, Kostenko, Semenov, Koldobskaya.
OF SYSTEMS AND PROCESSES
Extraction of 1-Methylnaphthalene, Benzothiophene, and Indole
with N-Methylpyrrolidone from Their Mixtures with Alkanes
A. A. Gaile, A. V. Kostenko, L. V. Semenov, and L. L. Koldobskaya
St. Petersburg State Technological Institute, St. Petersburg, Russia
Kirishinefteorgsintez Production Association, Limited Liability Company, Kirishi, Leningrad oblast, Russia
Received September 1, 2004; in final form, July 2005
Abstract-Extraction of 1-methylnaphthalene, benzo[b]thiophene, and indole with N-methylpyrrolidone from
their model mixtures with hexadecane in the absence and in the presence of lower-boiling n-alkanes (hexane,
decane, dodecane) was studied.
The requirements to the environmental safety of
motor and boiler fuels became considerably more
stringent in the past 5310 years. The permissible
concentration of sulfur and aromatic hydrocarbons in
automobile gasolines, diesel fuel, black oil for ships,
and boiler fuel is restricted.
The content of nitrogen in fuels is not restricted.
However, nitrogen compounds in fuels are catalytic
poisons, and with an increase in their content the
efficiency of hydrorefining decreases. Also decreases
the yield of light petroleum products in catalytic
cracking and hydrocracking of vacuum gas oils and
Exhaustive removal of sulfur and nitrogen com-
pounds from fuels using traditional hydrogenation
methods requires elevation of partial hydrogen pres-
sures and upgrade of installations with inclusion of
additional hydrorefining reactors because of low feed
space velocities; this requires large investments and
increases the power consumption. Hydrogenolysis of
4,6-dialkyl derivatives of dibenzothiophene is espe-
cially difficult because of steric hindrance .
In the alternative extraction procedure for fuel
treatment, on the contrary, such heteroatomic aromatic
or partially aromatic compounds should be readily
removed, as suggested by higher, compared to arenes,
stability constants of the complexes with polar sol-
vents, low enthalpies of mixing, and low activity coef-
ficients. In particular, the formation constants of com-
plexes of N-methylpyrrolidone with benzo[b]thio-
phene and naphthalene at 20oC are 1.9 and 0.6 l mol
respectively . The activity coefficients of benzo[b]-
thiophene and naphthalene at infinite dilution in dieth-
ylene glycol at 30oC are 6.6 and 11.2 . The enthal-
pies of specific interaction of 1-methylnaphthalene,
benzo[b]thiophene, and indole with N-methylpyrroli-
done at 25oCare333.5, 338.4, and 354.4 kJ mol
However, data on the extractive recovery of hetero-
atomic compounds and arenes are contradictory. For
example, Podolyak et al.  report that benzothio-
phene is extracted better than naphthalene. At the
same time, data obtained by Bikkulov et al.  indi-
cate that naphthalene homologs are extracted from
kerosene3gas oil fractions with N-methylpyrrolidone
better than benzothiophene homologs.
Therefore, taking also into account problems with
the determination of nitrogen compounds (whose con-
tent in petroleum fractions is by an order of magni-
tude lower than that of organosulfur compounds), it is
urgent to examine the relative efficiency of extraction
of arenes and aromatic sulfur and nitrogen compounds
from model mixtures with saturated hydrocarbons.
The goals of this study were to compare the effi-
ciency of the extraction of heterocyclic sulfur- and
nitrogen-containing compounds and polycyclic arenes
from model mixtures with n-alkanes and to elucidate
the influence exerted by various nonpolar diluents on
the efficiency of the extraction of heterocyclic com-
pounds and arenes.
As a polar solvent for the extraction of heterocyclic
compounds and arenes we chose N-methylpyrrolidone.
This extractant is commercially used both for extrac-
tion of benzene, toluene, and xylene from reformer
naphthas and for selective refining of oil fractions .
We found previously  that the separation
factors of hydrocarbons substantially increase when
the extraction of benzene and naphthalene homologs
with polar extractants (acetonitrile, methyl Cellosolve,