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FOSS et al.
a concentration of ~10–3 g/μL. The sample volume
was 0.1 μL. The mass spectrometry data were pro-
cessed using the XcaliburTM software program.
filtered off on a Buchner funnel and washed with dis-
tilled water until neutral to litmus. The resulting sulfo-
cationite was dried at a temperature of 25°C for 96 h.
The treatment with oleum was conducted as fol-
lows: 2 g of sulfonated asphaltenes were added to 40 g
of sulfuric acid under permanent stirring. The mixture
was held for 10 min; after that, 20 mL of oleum were
added dropwise. The temperature was increased to
100°C, and the reaction was run for 0.5, 1, or 2 h. The
sulfocationite was isolated in accordance with the
above procedure.
Asphaltenes are a polyaromatic product that read-
ily undergoes electrophilic substitution in the aromatic
ring. According to [9, 11], the sulfonation of polynu-
clear hydrocarbons can occur via two routes with the
localization of the sulfonic acid group in different
positions (α or β) depending on reaction conditions,
which are subject to a kinetic or thermodynamic con-
trol. To determine the maximum degree of sulfonation
of asphaltenes, some products were treated with
oleum. The resulting sulfocationites were studied by a
set of physicochemical analysis methods; the samples
exhibiting the highest SEC values were studied by the
MALDI method (Fig. 1).
Infrared (IR) spectra of the sulfonated cation
exchangers were recorded on a Vector-22 spectropho-
tometer (Bruker) in the range of 4000–400 cm–1 at a
resolution of 4 cm–1. To study the structural-group
composition of the original asphaltenes and the sul-
fonated cation exchangers, the following spectral
coefficients (SCs) were calculated: aliphaticity, Al =
D1450/D1600; aromaticity, Ar = D1600/D720 + 1380; degree
of condensation, Cn = D1600/D740 + 860; degree of oxi-
dation, Ox = D1700/D1600; degree of sulfonation, Sf =
For asphaltene sulfonation, temperatures corre-
sponding to a kinetic and thermodynamic control of
the reaction were selected. Based on experimental
data, the product with the highest SEC value was
tested as an ethylene glycol acetalization catalyst.
D1030/D1600; and hydroxylity, Hd = D3425/D1600
.
RESULTS AND DISCUSSION
To determine the molecular weight of the original
asphaltenes and the reaction products, the matrix-
assisted laser desorption/ionization (MALDI)
method was used. The studies were conducted
on a Ultraflex III TOF/TOF mass spectrometer
(Bruker) using a 1,8,9-trihydroxyanthracene matrix.
The derived data were processed using the Flex Anal-
ysis 3.0 software package (Bruker Daltonik GmbH).
The elemental composition of the samples was
analyzed on a EuroEA 3028-HT-OM high-tempera-
ture CHNS-O analyzer (Eurovector S.p.A.). The
degree of carbonization (carbon enrichment) of the
asphaltene structure and the sulfur and oxygen con-
tent relative to carbon was calculated. In calculating
the oxygen content, the metal content was not taken
into account.
The main characteristic of reaction products as
potential acid catalysts is the total SEC value. In the
case of a kinetic control of the reaction, it was found
that, at 80°С, the SEC parameter increases with an
increase in the reaction time. The maximum SEC
value achieves 2.8 meq/g within 10 h (product 10-80).
The SEC values for sulfonated asphaltenes at 100 and
120°C are 3.6 and 3.8 meq/g, respectively (products 6-
100 and 6-120) and described by a unimodal distribu-
tion with extreme points at 6 h. In the case of a ther-
modynamic control of the reaction (Fig. 1), the SEC
value also has a unimodal pattern with a maximum of
3.8 meq/g at 6 h of sulfonation. It should be noted that
a long-term heating apparently leads to the occurrence
of oxidative desulfonation reactions (Fig. 2). The sul-
fonated cation exchangers with a high SEC value (6-
120 and 6-160) were subjected to an oleum treatment
(further sulfonation) at a temperature of 100°C and a
time of 0.5, 1, and 2 h.
The oleum treatment of samples 6-120 and 6-160
leads to an increase in the SEC values (Fig. 3). The
maximum SEC value of 4.3 meq/g was found for sam-
ples 6-160-0.5 and 6-160-2.
The broad SEC value range of the resulting sulfon-
ated cation exchangers provides their use as catalysts in
various reactions determined by the feedstock and the
strength of the sulfocationite, such as the hydrolysis of
esters, carbohydrates, and proteins; the hydration of
unsaturated hydrocarbons, the elimination of alco-
hols, and the synthesis of ethers and esters [6–8].
Static exchange capacity (SEC) was determined in
accordance with ASTM D 2187–94.
The chromatography–mass spectrometry analysis
of the alcohol acetalization reaction products was con-
ducted on a Thermo Electron Corporation DFS
instrument (Shimadzu) using electron impact as the
ionization method at an ionizing electron energy of
70 eV and an ion source temperature of 280°C. A
30 m × 0.25 mm Thermo TG-5MS capillary column
was used to separate the substances. Helium was used
as the carrier gas. The flow rate was 2.8 mL/min. The
injector temperature was 230°C. The following tem-
perature programming was used: an initial tempera-
ture of 90°C (isotherm for 3 min), heating to 200°C at
a heating rate of 6 deg/min (1 min), heating to 280°C
at 20 deg/min (30 min), and exposure at the final tem-
To characterize the structural-group composition
perature of 280°C for 15 min. Prior to introducing the of petroleum objects, the IR spectroscopy method
test sample into the instrument, it was diluted in chro- involving the calculation of SCs is used. These param-
matographically pure (HPLC) carbon tetrachloride at eters make it possible to determine the structural
PETROLEUM CHEMISTRY
Vol. 60
No. 6
2020