Russian Journal of Applied Chemistry, 2013, Vol. 86, No. 5, pp. 654−657.
Pleiades Publishing, Ltd., 2013.
Original Russian Text © S.N. Shishkin, A.A. Gaile, D.A. Bakaushina, N.V. Kuzichkin, 2013, published in Zhurnal Prikladnoi Khimii, 2013, Vol. 86, No. 5,
Extractive Puriﬁ cation of Light Visbreaker Gasoil
S. N. Shishkin, A. A. Gaile, D. A. Bakaushina, and N. V. Kuzichkin
St. Petersburg State Technological Institute, St. Petersburg, Russia
Received March 26, 2013
Abstract—Results of a study of the counterﬂ ow ﬁ ve-stage extraction of light visbreaker gasoil with N-methylpyr-
rolidone and phenol are reported. To preclude formation of azeotropes, gasoil was preliminarily separated into light
and heavy fractions. Phenol with 10% water was used as a solvent for the light fraction, and N-methylpyrrolidone,
for the heavy fraction. It is shown that the rafﬁ nates obtained can be used to produce diesel fuel of K-5 ecologi-
cal class according to the technical regulations of the Customs Union by subsequent hydrotreatment at moderate
The manufacture of diesel fuels can be raised by
processing distillates of thermal and thermocatalytic
processes (visbreaking, delayed coking, catalytic
cracking). However, gasoils produced in secondary
processes differ from straight-run fractions in the
increased content of sulfur, nitrogen, aromatic
compounds, and unstable diene hydrocarbons . The
increased content of diene hydrocarbons and nitrogen
compounds markedly complicates the hydrotreatment
Nitrogen compounds are much more difﬁ cultly
removed than sulfur compounds and deactivate the
hydrotreatment process, and, in addition, they are
tarring promoters. Diene hydrocarbons are polymerized
under hydrotreatment conditions to give polymers that
also deactivate catalysts .
To obtain low-sulfur products with a sulfur content
lower than 10 mg g
(ppm), it is necessary to construct
high-pressure (8–10 MPa) hydrotreatment installation
with high-efﬁ ciency catalysts.
Installation of this kind will require a twofold rise
in investment and a 80% increase in maintenance
expenditure, compared with the existing hydrotreatment
installations , mostly due to the higher hydrogen
pressure in the system and more intricate equipment.
An alternative to hydrogenation methods for
improving the quality of diesel fuel are combined
techniques including extraction processes in the ﬁ rst
stage and hydrotreatment in the second .
Extraction with polar electron-acceptor solvents most
readily yields benzothiophenes, dibenzothiophenes,
nitrogen-containing compounds of aromatic nature,
polycycloarenes, and tars.
The reactivity of organosulfur compounds in
hydrotreatment decreases in the following order:
mercaptans > sulﬁ des > disulﬁ des > alkylthiophenes >
benzothiophenes > dibenzothiophenes.
If the content of sulfur is reduced in the extractive
puriﬁ cation stage to 0.4–0.45 wt %, the rafﬁ nate can be
processed in the second hydrotreatment stage under a
medium pressure (up to 4 MPa), with the sulfur content
of diesel fuel lower than 10 mg kg
Previously, production of diesel fuel and raw
materials for manufacture of technical-grade carbon
from light visbreaker and delayed-coking gasoils by
extraction with dimethylformamide (DMFA) has been
The goal of our present paper was to verify the
possibility of extractive puriﬁ cation of light visbreaker
gasoil with N-methylpyrrolidone.
As raw material served visbreaker gasoil (VBGO) from