CATALYTIC PROPERTIES OF ACID-MODIFIED ALUMINOSILICATES IN GLYCEROL KETALIZATION WITH ACETONE
The catalytic properties of natural aluminosilicates from Ukrainian deposits modified with sulfuric acid were studied in glycerol ketalization with acetone. Bentonite (Bent, Dashukivske deposit), clinoptilolite (Cli, Sokyrnytske deposit) and trepel (Tr, Konoplianske deposit) were treated with sulfur...
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Ukrainian Chemistry Journal| _version_ | 1871466219915182080 |
|---|---|
| author | Davtian, Araksia Levchenko, Olha Yaremov, Pavlo Kurmach, Mykhailo |
| author_facet | Davtian, Araksia Levchenko, Olha Yaremov, Pavlo Kurmach, Mykhailo |
| author_institution_txt_mv | [
{
"author": "Araksia Davtian",
"institution": "O.V. BogatskyPhysico-Chemical Institute of National Academy of Sciences of Ukraine"
},
{
"author": "Olha Levchenko",
"institution": "O.V. BogatskyPhysico-Chemical Institute of National Academy of Sciences of Ukraine"
},
{
"author": "Pavlo Yaremov",
"institution": "L. V. Pisarzhevsky Institute of Physical Chemistry of National Academy of Sciences of Ukraine"
},
{
"author": "Mykhailo Kurmach",
"institution": "L. V. Pisarzhevsky Institute of Physical Chemistry of National Academy of Sciences of Ukraine"
}
] |
| author_sort | Davtian, Araksia |
| baseUrl_str | https://ucj.org.ua/index.php/journal/oai |
| collection | OJS |
| datestamp_date | 2026-07-22T08:23:57Z |
| description | The catalytic properties of natural aluminosilicates from Ukrainian deposits modified with sulfuric acid were studied in glycerol ketalization with acetone. Bentonite (Bent, Dashukivske deposit), clinoptilolite (Cli, Sokyrnytske deposit) and trepel (Tr, Konoplianske deposit) were treated with sulfuric acid to increase their acidity and improve catalytic performance. The influence of catalyst loading, reaction temperature and glycerol:acetone molar ratio on glycerol conversion and initial rate of its consumption was investigated. It was found that catalytic activity strongly depends on structural, adsorption and acidic characteristics of aluminosilicates. The highest catalytic activity was observed for sulfuric acid-modified bentonite (H-Bent), which provided a maximum glycerol conversion of 81% at 45 °C, catalyst loading of 3 wt.% and glycerol:acetone molar ratio 1:25. H-Tr and H-Cli exhibited lower acti-vity, reaching 71% and 60% conversion, respectively, under the same conditions. The superior performance of H-Bent is associated with its higher specific surface area (243 m2/g), developed mesoporous structure and higher concentration of Brønsted and Lewis acid sites. Nitrogen adsorption-desorption analysis showed that all investigated samples belong to type IV isotherms, characteristic of micro- mesoporous materials. H-Bent had the highest total pore volume and mesopore surface area, while H-Cli contained a noticeable fraction of micropores. Pyridine adsorption studies revealed that H-Bent contains both Brønsted and Lewis acid sites of medium and high strength, whereas H-Tr and H-Cli are characterized mainly by weak and medium-strength Brønsted sites. Kinetic analysis demonstrated that the reaction order with respect to glycerol is close to one for H-Bent and two for H-Tr, indicating differences in rate-limiting step and reaction mechanism. The pseudo-Michaelis constants and maxi¬mum reaction rates were also determined, confirming the significantly higher catalytic efficiency of H-Bent compared to other investigated samples. Furthermore, the obtained results demonstrate that sulfuric acid-modified bentonite is a promising low-cost and environmentally friendly catalyst for glycerol valorization into cyclic ketals, which can be considered valuable fuel additives and intermediates for chemical industry. |
| doi_str_mv | 10.33609/2708-129X.92.3.2026.48-59 |
| first_indexed | 2026-05-02T01:00:17Z |
| format | Article |
| fulltext |
48 ISSN 2708-129X. Укр. хім. журн., 2025
UDC 547.426.1+547-316+553.61+544.47 doi: 10.33609/2708-129X.92.3.2026.48-59
CATALYTIC PROPERTIES OF ACID-MODIFIED ALUMINOSILICATES
IN GLYCEROL KETALIZATION WITH ACETONE.
A. S. Davtian1,
O. O. Levchenko1,
P. S. Yaremov2,
M. M. Kurmach2,
G. L. Kamalov1
1O. V. Bogatsky Physico-Chemical Institute of National Academy of Science of Ukraine,
86 Lustdorfska doroga, 65080 Odesa, Ukraine;
2L. V. Pisarzhevsky Institute of Physical Chemistry of National Academy of Science of Ukraine,
31 prosp. Nauki, 03028 Kyiv, Ukraine
e-mail: araksya2103@gmail.com
The catalytic properties of natural aluminosilicates from Ukrainian deposits modified with sulfuric
acid were studied in glycerol ketalization with acetone. Bentonite (Bent, Dashukivske deposit), clinop-
tilolite (Cli, Sokyrnytske deposit) and trepel (Tr, Konoplianske deposit) were treated with sulfuric acid
to increase their acidity and improve catalytic performance. The influence of catalyst loading, reaction
temperature and glycerol:acetone molar ratio on glycerol conversion and initial rate of its consump-
tion was investigated. It was found that catalytic activity strongly depends on structural, adsorption
and acidic characteristics of aluminosilicates. The highest catalytic activity was observed for sulfuric
acid-modified bentonite (H-Bent), which provided a maximum glycerol conversion of 81% at 45 °C,
catalyst loading of 3 wt.% and glycerol:acetone molar ratio 1:25. H-Tr and H-Cli exhibited lower acti
vity, reaching 71% and 60% conversion, respectively, under the same conditions. The superior perfor-
mance of H-Bent is associated with its higher specific surface area (243 m2/g), developed mesoporous
structure and higher concentration of Brønsted and Lewis acid sites. Nitrogen adsorption-desorption
analysis showed that all investigated samples belong to type IV isotherms, characteristic of micro-
mesoporous materials. H-Bent had the highest total pore volume and mesopore surface area, while
H-Cli contained a noticeable fraction of micropores. Pyridine adsorption studies revealed that H-Bent
contains both Brønsted and Lewis acid sites of medium and high strength, whereas H-Tr and H-Cli
are characterized mainly by weak and medium-strength Brønsted sites. Kinetic analysis demonstrated
that the reaction order with respect to glycerol is close to one for H-Bent and two for H-Tr, indicating
differences in rate-limiting step and reaction mechanism. The pseudo-Michaelis constants and maxi
mum reaction rates were also determined, confirming the significantly higher catalytic efficiency of
H-Bent compared to other investigated samples. Furthermore, the obtained results demonstrate that
sulfuric acid-modified bentonite is a promising low-cost and environmentally friendly catalyst for
glycerol valorization into cyclic ketals, which can be considered valuable fuel additives and interme-
diates for chemical industry.
Keywords: glycerol, ketalization, natural aluminosilicates, acid modification, heterogeneous catalysis.
49https://ucj.org.ua
A. S. Davtian, O. O. Levchenko, P. S. Yaremov, M. M. Kurmach, G. L. Kamalov UCJ № 2/ Vol. 92
INTRODUCTION. Due to rapid growth
of global biodiesel production, large amounts
of glycerol are generated as the main by-pro
duct [1]. Currently, the global production of
glycerol from biodiesel exceeds its demand,
leading to market oversaturation and a de-
crease in its price. Under such conditions, the
search for efficient ways to use excess glycerol
to obtain value-added products becomes par-
ticularly relevant [2]. Therefore, the conversion
of glycerol into other commercially valuable
compounds is a promising approach to en-
hance the economic attractiveness of biodiesel
production and to make the process more sus-
tainable and environmentally friendly.
Among the possible routes for glycerol
transformation, its acetalization and ketaliza-
tion – reactions with aldehydes or ketones in
presence of acid catalysts to form acetals or
ketals have attracted considerable attention.
The obtained compounds are characterized by
a wide range of practical applications, includ-
ing use as fuel components, solvents, lubricant
additives and intermediates in organic synthe-
sis. Of particular interest is glycerol ketaliza-
tion with acetone to form solketal [3], a com-
pound considered an effective fuel additive for
improving the performance characteristics of
motor fuels.
An important aspect of implementing
such processes is development of accessible,
efficient and stable heterogeneous catalysts.
One possible solution is use of inexpensive
and readily available natural aluminosilicates,
whose structural and acid-base properties can
be purposefully modified, in particular by acid
treatment.
The aim of this work is to investigate the
catalytic properties of natural aluminosilicates
from Ukrainian deposits, namely bentonite
(Bent, Dashukivske deposit), clinoptilolite
(Cli, Sokyrnytske deposit) and trepel (Tr, Ko
noplianske deposit), modified with sulfuric
acid (H), in glycerol ketalization with acetone,
as well as to study the influence of nature of
these aluminosilicates on glycerol conversion
and catalyst stability during the process.
EXPERIMENTAL AND RESULTS DIS-
CUSSION. The modification of natural alumi-
nosilicates with sulfuric acid was carried out
according to procedure described in [4] with
some changes. A 50 g of natural Bent, Cli and
Tr (fraction 1.0–2.0 mm) was placed into a
250 mL round-bottom flask equipped with a
reflux condenser, followed by addition 100 mL
of sulfuric acid (3 mol/L). The suspension was
maintained in a water bath (~100 °C) under
constant stirring for 2 h, then stirred for an ad-
ditional 1 h without heating. The sulfuric acid
was removed by decantation, the samples were
washed with distilled water. The procedure
was repeated until a negative test for sulfate
ions was achieved (no white precipitate upon
addition of BaCl2). The samples were dried at
120 °C for 1 h, calcined at 500 °C for 5 h and
ground in an agate mortar, obtaining particles
of average size 0.05 mm (fraction 0–1.0 mm).
The acidic properties of prepared catalysts
were studied using pyridine adsorption as a
spectral probe. Tablets weighing 10 mg with a
surface area of 64 cm2 were obtained by press-
ing aluminosilicate powders without a binder.
The tablets were activated at 350 °C under va
cuum for 1 h. Pyridine adsorption was carried
out at 150 °C for 30 min, after which physically
adsorbed pyridine was removed by evacua-
tion at the same temperature for 30 min. The
samples were cooled and their IR spectra were
recorded using a «Spectrum one» Fourier-IR
spectrometer (Perkin-Elmer). The samples
50 ISSN 2708-129X. Укр. хім. журн., 2026
CATALYTIC PROPERTIES OF ACID-MODIFIED ALUMINOSILICATES IN GLYCEROL KETALIZATION WITH ACETONE.ORGANIC CHEMISTRY
were then stepwise heated to 250 °C and
350 °C, held at each temperature for 30 min,
cooled and corresponding IR spectra were re-
corded. The concentrations of Brønsted and
Lewis acid sites were calculated according to
method described in [5].
Nitrogen adsorption-desorption isotherms
at 77 K were measured by volumetric method
using an «AMI-Micro-300 Series analyzer (Al-
tamira Instruments, Micro300C-02-Analysis
Station 3)». The surface area was calculated in
relative pressure range of 0.1 ≤ p/pо ≤ 0.3 us-
ing Brunauer – Emmett – Teller (BET) equa-
tion, while the mesopore size distribution was
determined using Barrett – Joyner – Halenda
method [6]. The micropore size distribution
was determined by Saito – Foley method [7],
the micropore volume was estimated using
t-plot method [6].
The catalytic activity of prepared cata-
lysts was tested in a thermostated glass reac-
tor (25 mL) equipped with a reflux condenser
and a magnetic stirrer. Solutions with different
glycerol:acetone ratios were prepared using
1.4-dioxane to adjust the volume. The reac-
tants were placed in reactor, after reaching the
desired temperature (25 °C, 35 °C, and 45 °C),
catalyst was added and reaction time was re-
corded. Samples were taken whitin 2 h into
centrifuge tubes (2 mL), cooled to room tem-
perature to prevent further reaction and evap-
oration losses, centrifuged for 5 min using a
mini centrifuge (IKA® mini G) to separate the
catalyst from reaction mixture. Eight samples
were taken, first after 5 min, then after 15 min
and 30 min.
The samples were analyzed using a gas
chromatograph (Shimadzu GC-2030, Ja-
pan) equipped with a flame ionization detec-
tor, a ZB-624 Plus capillary column (30 m ×
0.32 mm × 1.80 μm). The initial column tem-
perature was 80 °C (held for 4 min), followed
by heating to 230 °C at a rate of 50 °C/6 min.
The detector temperature was 350 °C, the in-
jector temperature was 250 °C. The carrier gas
(helium) flow rate was 35.5 cm3/s, the split ra-
tio was 100. The analysis was performed using
the internal standard method with propanol as
the standard. To 0.5 mL of sample, 0.03 mL of
internal standard was added and 0.2 μL was in-
jected into chromatograph.
Glycerol conversion was determined af-
ter 2 h of reaction. The initial rate of its con-
sumption was determined graphically as tan-
gent of slope of concentration–time curve:
r = tg α/60, mol·L-1·s-1.
Structural and adsorption characteristics of
prepared catalysts. The structural and adsorp-
tion properties of acid-modified Bent, Cli and
Tr were investigated. In particular, nitrogen
adsorption-desorption isotherms were ana-
lyzed, the surface area was determined and
the nature of acid sites was examined in order
to evaluate the influence of these characteris-
tics on catalytic activity. According to classical
classification of adsorption-desorption iso-
therms (77 K), the obtained isotherms (Fig. 1)
can be assigned to type IV [8], which is typi-
cal of micro- mesoporous materials. Type IV
isotherms exhibit an initial uptake at low re
lative pressures, formally characteristic of ad-
sorption in micropores, as well as a region at
p/po > 0.45 corresponding to adsorption in
mesopores accompanied by capillary conden-
sation (i.e., condensation of vapor in pores
and narrow channels of solid sorbents), as
evidenced by presence of a hysteresis loop be-
tween adsorption-desorption branches.
The phenomenon of capillary condensation
is associated with condensation of adsorbate
51https://ucj.org.ua
A. S. Davtian, O. O. Levchenko, P. S. Yaremov, M. M. Kurmach, G. L. Kamalov UCJ № 2/ Vol. 92
H-Bent H-Cli
H-Tr
Fig. 1. Nitrogen adsorption-desorption isotherms by samples of prepared catalysts.
vapor in pores of sample at pressures lower
than saturation vapor pressure. The appearance
of a hysteresis loop in adsorption-desorption
isotherm is related to different mechanisms of
pore filling and desorption. The presence or ab-
sence of micropores in type IV isotherms can
be determined using the comparative t-plot
method, since adsorption in initial region of
isotherm may also occur in mesopores.
Structural and adsorption characteristics of prepared catalysts. The structural and
adsorption properties of acid-modified Bent, Cli and Tr were investigated. In particular, nitrogen
adsorption-desorption isotherms were analyzed, the surface area was determined and the nature of
acid sites was examined in order to evaluate the influence of these characteristics on catalytic
activity. According to classical classification of adsorption-desorption isotherms (77 K), the
obtained isotherms (Fig. 1) can be assigned to type IV [8], which is typical of micro- mesoporous
materials. Type IV isotherms exhibit an initial uptake at low relative pressures, formally
characteristic of adsorption in micropores, as well as a region at p/po > 0.45 corresponding to
adsorption in mesopores accompanied by capillary condensation (i.e., condensation of vapor in
pores and narrow channels of solid sorbents), as evidenced by presence of a hysteresis loop between
adsorption-desorption branches.
The phenomenon of capillary condensation is associated with condensation of adsorbate
vapor in pores of sample at pressures lower than saturation vapor pressure. The appearance of a
hysteresis loop in adsorption-desorption isotherm is related to different mechanisms of pore filling
and desorption. The presence or absence of micropores in type IV isotherms can be determined
using the comparative t-plot method, since adsorption in initial region of isotherm may also occur in
mesopores.
H-Bent H-Cli
H-Tr
Fig. 1. Nitrogen adsorption-desorption isotherms by samples of prepared catalysts.
The surface area values of prepared catalysts, determined using Brunauer – Emmett – Teller
(BET) equation [8, 9], are presented in Table 1. Along with specific surface area, important
characteristics include pore volume and pore size distribution. The micropore volume was
determined using the t-plot method. The mesopore diameter was calculated using the adsorption
branches of isotherms. This is due to peculiarity of adsorption-desorption hysteresis observed in
nitrogen adsorption isotherms (77 K), which typically closes at relative pressures of 0.45–0.50 and
Structural and adsorption characteristics of prepared catalysts. The structural and
adsorption properties of acid-modified Bent, Cli and Tr were investigated. In particular, nitrogen
adsorption-desorption isotherms were analyzed, the surface area was determined and the nature of
acid sites was examined in order to evaluate the influence of these characteristics on catalytic
activity. According to classical classification of adsorption-desorption isotherms (77 K), the
obtained isotherms (Fig. 1) can be assigned to type IV [8], which is typical of micro- mesoporous
materials. Type IV isotherms exhibit an initial uptake at low relative pressures, formally
characteristic of adsorption in micropores, as well as a region at p/po > 0.45 corresponding to
adsorption in mesopores accompanied by capillary condensation (i.e., condensation of vapor in
pores and narrow channels of solid sorbents), as evidenced by presence of a hysteresis loop between
adsorption-desorption branches.
The phenomenon of capillary condensation is associated with condensation of adsorbate
vapor in pores of sample at pressures lower than saturation vapor pressure. The appearance of a
hysteresis loop in adsorption-desorption isotherm is related to different mechanisms of pore filling
and desorption. The presence or absence of micropores in type IV isotherms can be determined
using the comparative t-plot method, since adsorption in initial region of isotherm may also occur in
mesopores.
H-Bent H-Cli
H-Tr
Fig. 1. Nitrogen adsorption-desorption isotherms by samples of prepared catalysts.
The surface area values of prepared catalysts, determined using Brunauer – Emmett – Teller
(BET) equation [8, 9], are presented in Table 1. Along with specific surface area, important
characteristics include pore volume and pore size distribution. The micropore volume was
determined using the t-plot method. The mesopore diameter was calculated using the adsorption
branches of isotherms. This is due to peculiarity of adsorption-desorption hysteresis observed in
nitrogen adsorption isotherms (77 K), which typically closes at relative pressures of 0.45–0.50 and
Structural and adsorption characteristics of prepared catalysts. The structural and
adsorption properties of acid-modified Bent, Cli and Tr were investigated. In particular, nitrogen
adsorption-desorption isotherms were analyzed, the surface area was determined and the nature of
acid sites was examined in order to evaluate the influence of these characteristics on catalytic
activity. According to classical classification of adsorption-desorption isotherms (77 K), the
obtained isotherms (Fig. 1) can be assigned to type IV [8], which is typical of micro- mesoporous
materials. Type IV isotherms exhibit an initial uptake at low relative pressures, formally
characteristic of adsorption in micropores, as well as a region at p/po > 0.45 corresponding to
adsorption in mesopores accompanied by capillary condensation (i.e., condensation of vapor in
pores and narrow channels of solid sorbents), as evidenced by presence of a hysteresis loop between
adsorption-desorption branches.
The phenomenon of capillary condensation is associated with condensation of adsorbate
vapor in pores of sample at pressures lower than saturation vapor pressure. The appearance of a
hysteresis loop in adsorption-desorption isotherm is related to different mechanisms of pore filling
and desorption. The presence or absence of micropores in type IV isotherms can be determined
using the comparative t-plot method, since adsorption in initial region of isotherm may also occur in
mesopores.
H-Bent H-Cli
H-Tr
Fig. 1. Nitrogen adsorption-desorption isotherms by samples of prepared catalysts.
The surface area values of prepared catalysts, determined using Brunauer – Emmett – Teller
(BET) equation [8, 9], are presented in Table 1. Along with specific surface area, important
characteristics include pore volume and pore size distribution. The micropore volume was
determined using the t-plot method. The mesopore diameter was calculated using the adsorption
branches of isotherms. This is due to peculiarity of adsorption-desorption hysteresis observed in
nitrogen adsorption isotherms (77 K), which typically closes at relative pressures of 0.45–0.50 and
The surface area values of prepared cata-
lysts, determined using Brunauer – Emmett –
Teller (BET) equation [8, 9], are presented in
Table 1. Along with specific surface area, im-
portant characteristics include pore volume
and pore size distribution. The micropore vo
lume was determined using the t-plot method.
The mesopore diameter was calculated using
the adsorption branches of isotherms. This is
due to peculiarity of adsorption-desorption
hysteresis observed in nitrogen adsorption iso-
therms (77 K), which typically closes at relative
pressures of 0.45–0.50 and corresponds to ten-
sile strength limit of liquid adsorbate meniscus
rather than to presence of mesopores of that
size.
52 ISSN 2708-129X. Укр. хім. журн., 2026
CATALYTIC PROPERTIES OF ACID-MODIFIED ALUMINOSILICATES IN GLYCEROL KETALIZATION WITH ACETONE.ORGANIC CHEMISTRY
Table 1.
Structural and adsorption characteristics of prepared catalysts.
Characteristic Н-Bent Н-Cli Н-Tr
Total pore volume (adsorption at p/po = 0.99), cm3/g 0.26 0.11 0.12
BET surface area, m2/g 243 101 74
Micropore volume, cm3/g – 0.021 –
Mesopore diameter (dV/dlogD), from adsorption
branch of isotherms, nm
5.0
–
5.0
~60
5.8
~60
Fig. 2. Total pore area of investigated catalysts.
As can be seen, H-Bent exhibits a higher
surface area (Smeso + Sexternal), which facilitates
easier diffusion (accessibility) of reactants and
reaction products to active sites. This, in turn,
affects its catalytic properties, i.e., the larger
surface area, the higher catalytic activity. Also,
H-Bent, compared to H-Tr and H-Cli, has a
larger mesopore surface area (Fig. 2), while
micropores are absent and are present only for
latter sample (Smicro = 51 m2/g). In case of inves-
tigated samples (based on shape of isotherms),
it is not possible to distinguish between ad-
sorption in mesopores and on external surface
(Smeso + Sexternal, Vmeso + Vexternal). The total ad-
sorption volume (cm3/g) at p/po = 0.99 is 0.26
for H-Bent, 0.12 for H-Tr and 0.11 for H-Cli.
For the latter, the micropore volume (cm3/g) is
0.021. According to the isotherms analysis, the
mesopores in the samples are heterogeneous
in size, with distribution maxima at 5.0–5.8
and weak intensity at ~60 nm for the H-Tr and
H-CLI samples (Table 1).
The concentrations of Brønsted and Lewis
acid sites in prepared catalyst samples were
determined using stepwise pyridine adsorp-
tion. Brønsted centers arise from protonation
of surface hydroxyl groups (Si–OH–Al) after
acid treatment, while Lewis centers are formed
through the formation of coordinatively un-
saturated aluminum atoms as a result of partial
decationation and dealumination of the struc-
ture under the action of sulfuric acid. By ana-
lyzing the vibrational frequencies of pyridine,
it is possible to distinguish absorption bands
corresponding to coordinatively bound pyri-
dine adsorbed on Lewis acid sites (1455 cm-1)
and pyridinium ions formed upon interaction
of pyridine with Brønsted acid sites (1528 cm-1)
[10]. According to pyridine adsorption data
obtained at 150 °C, 250 °C, and 350 °C, the
concentration of Brønsted acid sites in H-Bent
sample decreases by 2 μmol/g with each in-
crease in temperature. For H-Cli and H-Tr
samples, concentration also decreases, and at a
pyridine desorption temperature of 350 °C, the
corresponds to tensile strength limit of liquid adsorbate meniscus rather than to presence of
mesopores of that size.
Table 1.
Structural and adsorption characteristics of prepared catalysts.
Characteristic Н-Bent Н-Cli Н-Tr
Total pore volume (adsorption at p/po =
0.99), cm3/g
0.26 0.11 0.12
BET surface area, m2/g 243 101 74
Micropore volume, cm3/g – 0.021 –
Mesopore diameter (dV/dlogD), from
adsorption branch of isotherms, nm
5.0
–
5.0
~60
5.8
~60
As can be seen, H-Bent exhibits a higher surface area (Smeso + Sexternal), which facilitates
easier diffusion (accessibility) of reactants and reaction products to active sites. This, in turn, affects
its catalytic properties, i.e., the larger surface area, the higher catalytic activity. Also, H-Bent,
compared to H-Tr and H-Cli, has a larger mesopore surface area (Fig. 2), while micropores are
absent and are present only for latter sample (Smicro = 51 m2/g). In case of investigated samples
(based on shape of isotherms), it is not possible to distinguish between adsorption in mesopores and
on external surface (Smeso + Sexternal, Vmeso + Vexternal). The total adsorption volume (cm3/g) at p/po =
0.99 is 0.26 for H-Bent, 0.12 for H-Tr and 0.11 for H-Cli. For the latter, the micropore volume
(cm3/g) is 0.021. According to the isotherms analysis, the mesopores in the samples are
heterogeneous in size, with distribution maxima at 5.0–5.8 and weak intensity at ~60 nm for the H-
Tr and H-CLI samples (Table 1).
Fig. 2. Total pore area of investigated catalysts.
The concentrations of Brønsted and Lewis acid sites in prepared catalyst samples were
determined using stepwise pyridine adsorption. Brønsted centers arise from protonation of surface
hydroxyl groups (Si–OH–Al) after acid treatment, while Lewis centers are formed through the
formation of coordinatively unsaturated aluminum atoms as a result of partial decationation and
dealumination of the structure under the action of sulfuric acid. By analyzing the vibrational
frequencies of pyridine, it is possible to distinguish absorption bands corresponding to
coordinatively bound pyridine adsorbed on Lewis acid sites (1455 cm-1) and pyridinium ions
formed upon interaction of pyridine with Brønsted acid sites (1528 cm-1) [10]. According to
pyridine adsorption data obtained at 150°C, 250°C, and 350°C, the concentration of Brønsted acid
sites in H-Bent sample decreases by 2 μmol/g with each increase in temperature. For H-Cli and H-
Tr samples, concentration also decreases, and at a pyridine desorption temperature of 350°C, the
absorption bands corresponding to pyridine adsorbed on Brønsted acid sites disappear. At the same
time, for these samples at 150°C and 250°C, concentrations of acid sites are similar magnitude (Fig.
53https://ucj.org.ua
A. S. Davtian, O. O. Levchenko, P. S. Yaremov, M. M. Kurmach, G. L. Kamalov UCJ № 2/ Vol. 92
absorption bands corresponding to pyridine
adsorbed on Brønsted acid sites disappear.
At the same time, for these samples at 150 °C
and 250 °C, concentrations of acid sites are
similar magnitude (Fig. 3). Based on obtained
data, in particular the desorption of pyridine
from Brønsted acid sites at relatively low tem-
peratures (350 °C), it can be concluded that
H-Cli and H-Tr samples contain only weak
and medium-strength Brønsted acid sites.
a)
b)
Fig. 3. Distribution of Brønsted (a) and Lewis (b)
acid centers.
At the same time, within the studied series of
modified aluminosilicates, Lewis acid sites are
absent in H-Cli, whereas for H-Tr their concent
ration does not exceed 10 μmol/g. For H-Bent,
concentration is 40 μmol/g at 150 °C and de-
creases two fold with an increase in tempera-
ture to 250 °C, remaining practically unchanged
upon further heating (250–350 °C). The H-Tr
sample is characterized predominantly by weak
and medium-strength Lewis acid sites, whereas
H-Bent is distinguished by a significant frac-
tion of strong Lewis and Brønsted acid sites.
The higher concentration and strength of the
acid centers (especially in the case of H-Bent)
provides increased catalytic activity, which is
consistent with experimental data on glycerol
conversion and initial rates of its consumption.
Catalytic activity of prepared catalysts in gly
cerol ketalization with acetone. The effects of
catalyst loading, reaction temperature and re-
actant molar ratio on glycerol conversion (X)
and its initial consumption rate (r) were investi-
gated. As shown in Fig. 4, for all three catalysts,
an increase in catalyst loading (Mcat) leads to an
increase in both X and r. H-Bent exhibits the
highest activity: conversion increases from 21%
to 81% and remains high even at lower catalyst
loadings of 0.25–0.5 wt.%. In contrast, H-Tr is
inactive at 0.25 wt.% and shows only 10% con-
version at 0.5 wt.%; with further increase in Mcat,
conversion reaches 71%. As for H-Cli, its acti
vity becomes noticeable starting from 1 wt.%,
with conversion increasing from 32% to 60%.
The initial rate of glycerol consumption in
presence of H-Bent increases two fold at 0.25–
0.5 wt.% and three fold at 0.5–1 wt.%. With a
further increase in catalyst loading (2–3 wt.%),
the rate remains practically unchanged (Fig. 4).
In presence of H-Tr, the rate increases three
fold at 0.5–1 wt.% and almost two fold at
1–2 wt.%, while further increases (2–3 wt.%)
do not significantly affect the rate. For H-Cli,
the rate increases two fold with each increase
in catalyst loading (1–3 wt.%).
3). Based on obtained data, in particular the desorption of pyridine from Brønsted acid sites at
relatively low temperatures (350°C), it can be concluded that H-Cli and H-Tr samples contain only
weak and medium-strength Brønsted acid sites.
a) b)
Fig. 3. Distribution of Brønsted (a) and Lewis (b) acid centers.
At the same time, within the studied series of modified aluminosilicates, Lewis acid sites are
absent in H-Cli, whereas for H-Tr their concentration does not exceed 10 μmol/g. For H-Bent,
concentration is 40 μmol/g at 150°C and decreases two fold with an increase in temperature to
250°C, remaining practically unchanged upon further heating (250–350°C). The H-Tr sample is
characterized predominantly by weak and medium-strength Lewis acid sites, whereas H-Bent is
distinguished by a significant fraction of strong Lewis and Brønsted acid sites. The higher
concentration and strength of the acid centers (especially in the case of H-Bent) provides increased
catalytic activity, which is consistent with experimental data on glycerol conversion and initial rates
of its consumption.
Catalytic activity of prepared catalysts in glycerol ketalization with acetone. The effects of
catalyst loading, reaction temperature and reactant molar ratio on glycerol conversion (X) and its
initial consumption rate (r) were investigated. As shown in Fig. 4, for all three catalysts, an increase
in catalyst loading (Mcat) leads to an increase in both X and r. H-Bent exhibits the highest activity:
conversion increases from 21% to 81% and remains high even at lower catalyst loadings of 0.25–
0.5 wt.%. In contrast, H-Tr is inactive at 0.25 wt.% and shows only 10% conversion at 0.5 wt.%;
with further increase in Mcat, conversion reaches 71%. As for H-Cli, its activity becomes noticeable
starting from 1 wt.%, with conversion increasing from 32% to 60%.
Fig. 4. Effect of catalyst mass fraction on glycerol conversion and initial rate of its consumption (glycerol:
acetone = 1:25; 45°C; 2 h).
3). Based on obtained data, in particular the desorption of pyridine from Brønsted acid sites at
relatively low temperatures (350°C), it can be concluded that H-Cli and H-Tr samples contain only
weak and medium-strength Brønsted acid sites.
a) b)
Fig. 3. Distribution of Brønsted (a) and Lewis (b) acid centers.
At the same time, within the studied series of modified aluminosilicates, Lewis acid sites are
absent in H-Cli, whereas for H-Tr their concentration does not exceed 10 μmol/g. For H-Bent,
concentration is 40 μmol/g at 150°C and decreases two fold with an increase in temperature to
250°C, remaining practically unchanged upon further heating (250–350°C). The H-Tr sample is
characterized predominantly by weak and medium-strength Lewis acid sites, whereas H-Bent is
distinguished by a significant fraction of strong Lewis and Brønsted acid sites. The higher
concentration and strength of the acid centers (especially in the case of H-Bent) provides increased
catalytic activity, which is consistent with experimental data on glycerol conversion and initial rates
of its consumption.
Catalytic activity of prepared catalysts in glycerol ketalization with acetone. The effects of
catalyst loading, reaction temperature and reactant molar ratio on glycerol conversion (X) and its
initial consumption rate (r) were investigated. As shown in Fig. 4, for all three catalysts, an increase
in catalyst loading (Mcat) leads to an increase in both X and r. H-Bent exhibits the highest activity:
conversion increases from 21% to 81% and remains high even at lower catalyst loadings of 0.25–
0.5 wt.%. In contrast, H-Tr is inactive at 0.25 wt.% and shows only 10% conversion at 0.5 wt.%;
with further increase in Mcat, conversion reaches 71%. As for H-Cli, its activity becomes noticeable
starting from 1 wt.%, with conversion increasing from 32% to 60%.
Fig. 4. Effect of catalyst mass fraction on glycerol conversion and initial rate of its consumption (glycerol:
acetone = 1:25; 45°C; 2 h).
54 ISSN 2708-129X. Укр. хім. журн., 2026
CATALYTIC PROPERTIES OF ACID-MODIFIED ALUMINOSILICATES IN GLYCEROL KETALIZATION WITH ACETONE.ORGANIC CHEMISTRY
Fig. 4. Effect of catalyst mass fraction on glycerol conversion and initial rate
of its consumption (glycerol: acetone = 1:25; 45 °C; 2 h).
3). Based on obtained data, in particular the desorption of pyridine from Brønsted acid sites at
relatively low temperatures (350°C), it can be concluded that H-Cli and H-Tr samples contain only
weak and medium-strength Brønsted acid sites.
a) b)
Fig. 3. Distribution of Brønsted (a) and Lewis (b) acid centers.
At the same time, within the studied series of modified aluminosilicates, Lewis acid sites are
absent in H-Cli, whereas for H-Tr their concentration does not exceed 10 μmol/g. For H-Bent,
concentration is 40 μmol/g at 150°C and decreases two fold with an increase in temperature to
250°C, remaining practically unchanged upon further heating (250–350°C). The H-Tr sample is
characterized predominantly by weak and medium-strength Lewis acid sites, whereas H-Bent is
distinguished by a significant fraction of strong Lewis and Brønsted acid sites. The higher
concentration and strength of the acid centers (especially in the case of H-Bent) provides increased
catalytic activity, which is consistent with experimental data on glycerol conversion and initial rates
of its consumption.
Catalytic activity of prepared catalysts in glycerol ketalization with acetone. The effects of
catalyst loading, reaction temperature and reactant molar ratio on glycerol conversion (X) and its
initial consumption rate (r) were investigated. As shown in Fig. 4, for all three catalysts, an increase
in catalyst loading (Mcat) leads to an increase in both X and r. H-Bent exhibits the highest activity:
conversion increases from 21% to 81% and remains high even at lower catalyst loadings of 0.25–
0.5 wt.%. In contrast, H-Tr is inactive at 0.25 wt.% and shows only 10% conversion at 0.5 wt.%;
with further increase in Mcat, conversion reaches 71%. As for H-Cli, its activity becomes noticeable
starting from 1 wt.%, with conversion increasing from 32% to 60%.
Fig. 4. Effect of catalyst mass fraction on glycerol conversion and initial rate of its consumption (glycerol:
acetone = 1:25; 45°C; 2 h).
The higher activity of H-Bent may be attri
buted to its layered structure, developed mes-
oporosity and higher specific surface area
(Fig. 2, Table 1), which ensure better accessibi
lity of active sites for reactant molecules. Acid
treatment leads to formation of a significant
number of Brønsted acid sites, which provides
additional catalytic activity to H-Bent. More
over, the presence of interlayer spaces pro-
motes adsorption and diffusion of reactants,
further enhancing catalytic performance.
With increasing reaction temperature, con-
version increases as expected, reaching a ma
ximum of 81% at 45 °C in presence of H-Bent.
At 25 °C, H-Tr and H-Cli show no activity,
while at 35 °C they exhibit similar conversions
(35%). With a further increase in temperature,
conversion rises to 71% for H-Tr and 60% for
H-Cli. In presence of H-Bent, the initial rate
remains almost unchanged between 25–35 °C
and increases nearly three fold at 35–45 °C.
The rate also increases approximately three
fold in presence of H-Tr and nearly two fold in
presence of H-Cli (Fig. 5).
The initial rate of glycerol consumption in presence of H-Bent increases two fold at 0.25–0.5
wt.% and three fold at 0.5–1 wt.%. With a further increase in catalyst loading (2–3 wt.%), the rate
remains practically unchanged (Fig. 4). In presence of H-Tr, the rate increases three fold at 0.5–1
wt.% and almost two fold at 1–2 wt.%, while further increases (2–3 wt.%) do not significantly
affect the rate. For H-Cli, the rate increases two fold with each increase in catalyst loading (1–3 wt.
%).
The higher activity of H-Bent may be attributed to its layered structure, developed
mesoporosity and higher specific surface area (Fig. 2, Table 1), which ensure better accessibility of
active sites for reactant molecules. Acid treatment leads to formation of a significant number of
Brønsted acid sites, which provides additional catalytic activity to H-Bent. Moreover, the presence
of interlayer spaces promotes adsorption and diffusion of reactants, further enhancing catalytic
performance.
With increasing reaction temperature, conversion increases as expected, reaching a
maximum of 81% at 45°C in presence of H-Bent. At 25°C, H-Tr and H-Cli show no activity, while
at 35°C they exhibit similar conversions (35%). With a further increase in temperature, conversion
rises to 71% for H-Tr and 60% for H-Cli. In presence of H-Bent, the initial rate remains almost
unchanged between 25–35°C and increases nearly three fold at 35–45°C. The rate also increases
approximately three fold in presence of H-Tr and nearly two fold in presence of H-Cli (Fig. 5).
Fig. 5. Effect of reaction temperature on glycerol conversion and initial rate of its consumption
(glycerol:acetone = 1:25; Mcat = 3 wt.%; 2 h).
In presence of H-Tr and H-Cli, at a glycerol:acetone molar ratio lower than 1:12, the activity
of these catalysts is rather low. For H-Tr, conversion is 25%, while for H-Cli it is 14%. With an
increase in molar ratio (1:25), conversion increases for both samples, reaching 71% for H-Tr and
60% for H-Cli. In contrast, H-Bent loses its activity only at a molar ratio of 1:1.3, where glycerol
conversion is as low as 2%. At a ratio of 1:3, conversion increases significantly (38%) and
continues to rise with a further increase of reactant ratio. The initial reaction rates also increase with
an excess of acetone (Fig. 6). In presence of H-Tr, rate increases significantly by 5 times when the
glycerol:acetone molar ratio increases from 1:12 to 1:25, while in presence of H-Cli it increases by
nearly 2.5 times. All investigated catalysts withstand only two reaction cycles.
Fig. 5. Effect of reaction temperature on glycerol conversion and initial rate
of its consumption (glycerol:acetone = 1:25; Mcat = 3 wt.%; 2 h).
55https://ucj.org.ua
A. S. Davtian, O. O. Levchenko, P. S. Yaremov, M. M. Kurmach, G. L. Kamalov UCJ № 2/ Vol. 92
In presence of H-Tr and H-Cli, at a glyce
rol:acetone molar ratio lower than 1:12, the ac-
tivity of these catalysts is rather low. For H-Tr,
conversion is 25%, while for H-Cli it is 14%.
With an increase in molar ratio (1:25), con-
version increases for both samples, reaching
71% for H-Tr and 60% for H-Cli. In contrast,
H-Bent loses its activity only at a molar ratio
of 1:1.3, where glycerol conversion is as low
as 2%. At a ratio of 1:3, conversion increases
significantly (38%) and continues to rise with
a further increase of reactant ratio. The initial
reaction rates also increase with an excess of
acetone (Fig. 6). In presence of H-Tr, rate in-
creases significantly by 5 times when the gly
cerol:acetone molar ratio increases from 1:12
to 1:25, while in presence of H-Cli it increases
by nearly 2.5 times. All investigated catalysts
withstand only two reaction cycles.
Fig. 6. Effect of glycerol:acetone molar ratio on glycerol conversion and initial rate of its consumption
(45°C; Mcat = 3% wt.; 2 h).
The features of reaction between glycerol and acetone in presence of prepared catalysts were
conditionally studied according to Michaelis-Menten model. Graphically, the Michaelis-Menten
equation represents a hyperbola. It can be linearized using the method of double reciprocal values
(Lineweaver – Burk method), i.e., by plotting 1/r versus 1/C, or by other methods. This approach
allows determination of Michaelis constant (KM) and the maximum reaction rates (rmax). By
constructing such a plot, a straight line is obtained with a slope of KM/rmax and an intercept on
ordinate axis at 1/rmax. As shown in Table 2, the pseudo KM and rmax values are significantly higher
for H-Bent. In this case, the formation of [acetone-catalyst] complex occurs at a higher rate, after
which it interacts with glycerol. Subsequently, the [acetone-catalyst-glycerol] complex decomposes
into reaction product, and the catalyst is regenerated.
Table 2.
Pseudo Michaelis constants and maximum reaction rates of glycerol with acetone
(glycerol:acetone = 1:25; 45oC; Mcat = 3 wt.%; 2 h).
Catalyst КМ rmax
H-Bent 1.65 12.3
H-Tr 0.54 0.32
H-Cli – –
In determining the concentration order of reaction with respect to glycerol (nGL), it was
found that H-Bent catalyzes the process stably over a wide range (five points) of glycerol
concentrations (0.1–0.48 mol/L). In presence of H-Tr, this range covers three concentrations (0.2–
0.55 mol/L), while for H-Cli it is limited to only two values – 0.24 mol/L and 0.6 mol/L. Therefore,
determining the concentration order with respect to glycerol in presence of H-Cli is not appropriate.
In contrast, the order is equal to one for H-Bent and two for H-Tr. The obtained values of
concentration order indicate different mechanisms of interaction between glycerol and active sites
of investigated catalysts. A first-order for glycerol in presence of H-Bent suggests that a single
glycerol molecule participates in rate-limiting step, which may be associated with better
accessibility of acid sites and effective adsorption of reactant on catalyst surface. The second-order
dependence observed for H-Tr may indicate a more complex rate-limiting step, possibly involving
two glycerol molecules, or a more significant role of adsorption effects on catalyst surface. For H-
Cli, determination of concentration order is not reliable due to narrow range of studied
concentrations and low catalytic activity, which may be attributed to a lower number of accessible
active sites.
Thus, it should be noted that in presence of investigated catalyst samples, the mechanism of
reaction between glycerol and acetone is realized differently. Based on general scheme of ketal
Fig. 6. Effect of glycerol:acetone molar ratio on glycerol conversion and initial rate
of its consumption (45 °C; Mcat = 3 wt.%; 2 h).
The features of reaction between glyce
rol and acetone in presence of prepared cata
lysts were conditionally studied according to
Michaelis-Menten model. Graphically, the
Michaelis-Menten equation represents a hy-
perbola. It can be linearized using the method
of double reciprocal values (Lineweaver – Burk
method), i.e., by plotting 1/r versus 1/C, or by
other methods. This approach allows deter-
mination of Michaelis constant (KM) and the
maximum reaction rates (rmax). By construct-
ing such a plot, a straight line is obtained with
a slope of KM/rmax and an intercept on ordinate
axis at 1/rmax. As shown in Table 2, the pseu-
do KM and rmax values are significantly higher
for H-Bent. In this case, the formation of [ace-
tone-catalyst] complex occurs at a higher rate,
after which it interacts with glycerol. Subse-
quently, the [acetone-catalyst-glycerol] comp
lex decomposes into reaction product, and the
catalyst is regenerated.
Table 2.
Pseudo Michaelis constants and maximum
reaction rates of glycerol with acetone (glyce
rol:acetone = 1:25; 45 oC; Mcat = 3 wt.%; 2 h).
Catalyst КМ rmax
H-Bent 1.65 12.3
H-Tr 0.54 0.32
H-Cli – –
56 ISSN 2708-129X. Укр. хім. журн., 2026
CATALYTIC PROPERTIES OF ACID-MODIFIED ALUMINOSILICATES IN GLYCEROL KETALIZATION WITH ACETONE.ORGANIC CHEMISTRY
In determining the concentration order of
reaction with respect to glycerol (nGL), it was
found that H-Bent catalyzes the process sta-
bly over a wide range (five points) of glycerol
concentrations (0.1–0.48 mol/L). In presence
of H-Tr, this range covers three concentrations
(0.2–0.55 mol/L), while for H-Cli it is limited
to only two values – 0.24 mol/L and 0.6 mol/L.
Therefore, determining the concentration or-
der with respect to glycerol in presence of
H-Cli is not appropriate. In contrast, the order
is equal to one for H-Bent and two for H-Tr.
The obtained values of concentration order in-
dicate different mechanisms of interaction be-
tween glycerol and active sites of investigated
catalysts. A first-order for glycerol in presence
of H-Bent suggests that a single glycerol mo
lecule participates in rate-limiting step, which
may be associated with better accessibility of
acid sites and effective adsorption of reactant
on catalyst surface. The second-order depen
dence observed for H-Tr may indicate a more
complex rate-limiting step, possibly involving
two glycerol molecules, or a more significant
role of adsorption effects on catalyst surface.
For H-Cli, determination of concentration or-
der is not reliable due to narrow range of stu
died concentrations and low catalytic activity,
which may be attributed to a lower number of
accessible active sites.
formation (A-D) under acid catalysis, a trimolecular cyclic transition state A is formed, in which the
second alcohol molecule in rate-limiting step facilitates the removal of water, leading to formation
of intermediate C. According to Michaelis-Menten model (Fig. 7), in presence of H-Tr, since the
reaction order is equal to two, a trimolecular cyclic transition state N is realized, in which a second
glycerol molecule promotes water elimination, forming intermediate O. In case of H-Bent, a similar
role in molecular bicyclic transition state Q is played by secondary hydroxyl group of the same
attacking glycerol molecule, which accounts for difference in reaction orders observed in presence
of investigated acid catalysts.
Fig. 7. Scheme of mechanism of glycerol ketalization with acetone.
It should be noted that the Brønsted acid centers are responsible for protonation of acetone
carbonyl group, which is a key step in the glycerol ketalization mechanism and contributes to the
formation of a reactive carbocationic intermediate. In turn, the Lewis acid centers act as electron-
withdrawing centers capable of coordinating the oxygen-containing functional groups of the
reagents, which facilitates the activation of molecules on the catalyst surface.
CONCLUSIONS. The catalytic properties of natural aluminosilicates modified with sulfuric
acid (H-Bent, H-Cli, H-Tr) in glycerol ketalization with acetone were investigated. It was
established that their activity is determined by structural-adsorption characteristics and the
concentration of acid sites. H-Bent is characterized by highest specific surface area (243 m2/g), a
developed mesoporous structure and a higher concentration of Brønsted and Lewis acid sites, which
ensures the maximum glycerol conversion of 81% at 45°C, 3 wt.%, and a 1:25 molar ratio, as well
as a higher initial glycerol consumption rate.
Kinetic analysis revealed differences in rate-limiting step and reaction mechanism: in
presence of H-Bent, the reaction order with respect to glycerol is equal to one, whereas for H-Tr it
is equal to two. Thus, acid-modified bentonite (H-Bent) is the most promising among the
investigated aluminosilicates as an effective heterogeneous catalyst for glycerol ketalization with
Fig. 7. Scheme of mechanism of glycerol ketalization with acetone.
57https://ucj.org.ua
A. S. Davtian, O. O. Levchenko, P. S. Yaremov, M. M. Kurmach, G. L. Kamalov UCJ № 2/ Vol. 92
Thus, it should be noted that in presence of
investigated catalyst samples, the mechanism
of reaction between glycerol and acetone is
realized differently. Based on general scheme
of ketal formation (A-D) under acid cataly-
sis, a trimolecular cyclic transition state A is
formed, in which the second alcohol molecule
in rate-limiting step facilitates the removal
of water, leading to formation of intermedi-
ate C. According to Michaelis-Menten model
(Fig. 7), in presence of H-Tr, since the reac-
tion order is equal to two, a trimolecular cyclic
transition state N is realized, in which a second
glycerol molecule promotes water elimination,
forming intermediate O. In case of H-Bent, a
similar role in molecular bicyclic transition
state Q is played by secondary hydroxyl group
of the same attacking glycerol molecule, which
accounts for difference in reaction orders ob-
served in presence of investigated acid cata-
lysts.
It should be noted that the Brønsted acid
centers are responsible for protonation of ace-
tone carbonyl group, which is a key step in the
glycerol ketalization mechanism and contribu
tes to the formation of a reactive carbocationic
intermediate. In turn, the Lewis acid centers
act as electron-withdrawing centers capable of
coordinating the oxygen-containing functio
nal groups of the reagents, which facilitates the
activation of molecules on the catalyst surface.
CONCLUSIONS. The catalytic properties
of natural aluminosilicates modified with sul-
furic acid (H-Bent, H-Cli, H-Tr) in glycerol
ketalization with acetone were investigated.
It was established that their activity is deter-
mined by structural-adsorption characteristics
and the concentration of acid sites. H-Bent is
characterized by highest specific surface area
(243 m2/g), a developed mesoporous structure
and a higher concentration of Brønsted and
Lewis acid sites, which ensures the maximum
glycerol conversion of 81% at 45 °C, 3 wt.%,
and a 1:25 molar ratio, as well as a higher initial
glycerol consumption rate.
Kinetic analysis revealed differences in
rate-limiting step and reaction mechanism: in
presence of H-Bent, the reaction order with
respect to glycerol is equal to one, whereas
for H-Tr it is equal to two. Thus, acid-modi-
fied bentonite (H-Bent) is the most promising
among the investigated aluminosilicates as an
effective heterogeneous catalyst for glycerol
ketalization with acetone.
AUTHOR CONTRIBUTIONS STATE-
MENT:
Davtian A. S.: Conceptualization, Data cu-
ration (literature analysis), Methodology and
Investigation (conducting experimental re-
search, modification of natural aluminosilicates
with sulfuric acid), Writing – original draft.
Levchenko O. O.: Investigation (conduc
ting experimental research), Writing – review
& editing (discussing the results).
Yaremov P. S.: Methodology and Investiga-
tion (study of nitrogen adsorption-desorption
by catalyst samples, determination of surface
area, pore area).
Kurmach M. M.: Conceptualization, Me
thodology and Investigation (study of Brønsted
and Lewis acid centers on catalysts surface).
Kamalov G. L.: Supervision, Funding ac-
quisition.
All authors have read the results of the study
and approved the final version of the manu-
script.
CONFLICT OF INTEREST. The authors de-
clare no conflict of interest.
58 ISSN 2708-129X. Укр. хім. журн., 2026
CATALYTIC PROPERTIES OF ACID-MODIFIED ALUMINOSILICATES IN GLYCEROL KETALIZATION WITH ACETONE.ORGANIC CHEMISTRY
FUNDING. This work was carried out
within the framework of the state-fun
ded research project «Transformation
of glycerol (a waste product of bio-
diesel production) under conditions
of hetero- and homogeneous catalysis
in acetalization, acetylation and oxida-
tion reactions with oxygen», state re
gistration number: 0124U000204.
КАТАЛІТИЧНІ ВЛАСТИВОСТІ КИСЛОТНО-
МОДИФІКОВАНИХ АЛЮМОСИЛІКАТІВ
У КЕТАЛІЗАЦІЇ ГЛІЦЕРИНУ АЦЕТОНОМ
А. С. Давтян1, О. О. Левченко1,
П. С. Яремов2, М. М. Курмач2,
Г. Л. Камалов1
1Фізико-хімічний інститут ім. О. В. Богат
ського Національної академії наук України,
Люстдорфська дорога, 86, Одеса 65080,
Україна;
2Інститут фізичної хімії ім. Л. В. Писаржев
ського Національної академії наук України,
просп. Науки, 31, Київ 03028, Україна
e-mail: araksya2103@gmail.com
Зазначено каталітичні властивості при-
родних алюмосилікатів українських родо-
вищ у кеталізації гліцерину ацетоном. З’я-
совано вплив масової частки каталізатора,
температури реакції та мольного співвідно-
шення реагентів на конверсію гліцерину та
початкову швидкість його витрати. Макси-
мальну конверсію 81% досягнуто у присут-
ності H-Bent за 45 °С, 3 мас.% каталізатора
та співвідношенні гліцерин : ацетон = 1:25.
Вивчено структурно-адсорбційні та кис-
лотні характеристики каталізаторів (роз-
мір пор, площа поверхні, концентрація та
співвідношення Бренстедівських та Льюї-
сівських кислотних центрів) і співставлено
вплив цих характеристик на їхні каталітич-
ні властивості.
Ключові слова: гліцерин, кеталізація,
природні алюмосилікати, кислотна моди-
фікація, гетерогенний каталіз.
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Стаття надійшла: 30.03.2026.
Статтю прийнято до друку: 09.04.2026.
Статтю опубліковано: 30.04.2026.
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| id | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-774 |
| institution | Ukrainian Chemistry Journal |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-07-23T01:14:27Z |
| publishDate | 2026 |
| publisher | V.I.Vernadsky Institute of General and Inorganic Chemistry |
| record_format | ojs |
| resource_txt_mv | ucjorgua/6f/586e9cc1ccc8283c34705fa7e81b9f6f.pdf |
| spelling | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-7742026-07-22T08:23:57Z CATALYTIC PROPERTIES OF ACID-MODIFIED ALUMINOSILICATES IN GLYCEROL KETALIZATION WITH ACETONE Davtian, Araksia Levchenko, Olha Yaremov, Pavlo Kurmach, Mykhailo glycerol, ketalization, natural aluminosilicates, acid modification, heterogeneous catalysis. The catalytic properties of natural aluminosilicates from Ukrainian deposits modified with sulfuric acid were studied in glycerol ketalization with acetone. Bentonite (Bent, Dashukivske deposit), clinoptilolite (Cli, Sokyrnytske deposit) and trepel (Tr, Konoplianske deposit) were treated with sulfuric acid to increase their acidity and improve catalytic performance. The influence of catalyst loading, reaction temperature and glycerol:acetone molar ratio on glycerol conversion and initial rate of its consumption was investigated. It was found that catalytic activity strongly depends on structural, adsorption and acidic characteristics of aluminosilicates. The highest catalytic activity was observed for sulfuric acid-modified bentonite (H-Bent), which provided a maximum glycerol conversion of 81% at 45 °C, catalyst loading of 3 wt.% and glycerol:acetone molar ratio 1:25. H-Tr and H-Cli exhibited lower acti-vity, reaching 71% and 60% conversion, respectively, under the same conditions. The superior performance of H-Bent is associated with its higher specific surface area (243 m2/g), developed mesoporous structure and higher concentration of Brønsted and Lewis acid sites. Nitrogen adsorption-desorption analysis showed that all investigated samples belong to type IV isotherms, characteristic of micro- mesoporous materials. H-Bent had the highest total pore volume and mesopore surface area, while H-Cli contained a noticeable fraction of micropores. Pyridine adsorption studies revealed that H-Bent contains both Brønsted and Lewis acid sites of medium and high strength, whereas H-Tr and H-Cli are characterized mainly by weak and medium-strength Brønsted sites. Kinetic analysis demonstrated that the reaction order with respect to glycerol is close to one for H-Bent and two for H-Tr, indicating differences in rate-limiting step and reaction mechanism. The pseudo-Michaelis constants and maxi¬mum reaction rates were also determined, confirming the significantly higher catalytic efficiency of H-Bent compared to other investigated samples. Furthermore, the obtained results demonstrate that sulfuric acid-modified bentonite is a promising low-cost and environmentally friendly catalyst for glycerol valorization into cyclic ketals, which can be considered valuable fuel additives and intermediates for chemical industry. V.I.Vernadsky Institute of General and Inorganic Chemistry 2026-04-30 Article Article Organic chemistry Органическая xимия Органічна xімія application/pdf https://ucj.org.ua/index.php/journal/article/view/774 10.33609/2708-129X.92.3.2026.48-59 Ukrainian Chemistry Journal; Vol. 92 No. 3 (2026): Ukrainian Chemistry Journal; 48-59 Украинский химический журнал; ##issue.vol## 92 ##issue.no## 3 (2026): Ukrainian Chemistry Journal; 48-59 Український хімічний журнал; Том 92 № 3 (2026): Ukrainian Chemistry Journal; 48-59 2708-129X 2708-1281 en https://ucj.org.ua/index.php/journal/article/view/774/407 Copyright (c) 2026 Araksia Davtian, Olha Levchenko, Pavlo Yaremov, Mykhailo Kurmach https://creativecommons.org/licenses/by-nc/4.0 |
| spellingShingle | Davtian, Araksia Levchenko, Olha Yaremov, Pavlo Kurmach, Mykhailo CATALYTIC PROPERTIES OF ACID-MODIFIED ALUMINOSILICATES IN GLYCEROL KETALIZATION WITH ACETONE |
| title | CATALYTIC PROPERTIES OF ACID-MODIFIED ALUMINOSILICATES IN GLYCEROL KETALIZATION WITH ACETONE |
| title_full | CATALYTIC PROPERTIES OF ACID-MODIFIED ALUMINOSILICATES IN GLYCEROL KETALIZATION WITH ACETONE |
| title_fullStr | CATALYTIC PROPERTIES OF ACID-MODIFIED ALUMINOSILICATES IN GLYCEROL KETALIZATION WITH ACETONE |
| title_full_unstemmed | CATALYTIC PROPERTIES OF ACID-MODIFIED ALUMINOSILICATES IN GLYCEROL KETALIZATION WITH ACETONE |
| title_short | CATALYTIC PROPERTIES OF ACID-MODIFIED ALUMINOSILICATES IN GLYCEROL KETALIZATION WITH ACETONE |
| title_sort | catalytic properties of acid-modified aluminosilicates in glycerol ketalization with acetone |
| topic_facet | glycerol ketalization natural aluminosilicates acid modification heterogeneous catalysis. |
| url | https://ucj.org.ua/index.php/journal/article/view/774 |
| work_keys_str_mv | AT davtianaraksia catalyticpropertiesofacidmodifiedaluminosilicatesinglycerolketalizationwithacetone AT levchenkoolha catalyticpropertiesofacidmodifiedaluminosilicatesinglycerolketalizationwithacetone AT yaremovpavlo catalyticpropertiesofacidmodifiedaluminosilicatesinglycerolketalizationwithacetone AT kurmachmykhailo catalyticpropertiesofacidmodifiedaluminosilicatesinglycerolketalizationwithacetone |