Effect of the nature of the additives of metal cations (Sr, Ba, and La) on the properties of Co-Mo hydrodesulfurization catalysts

Article abstract of DOI:10.1134/S0023158411030128

The effect of the nature of the support modified with the ions of alkaline earth and rare earth elements (Sr, Ba, and La) on the properties of Co-Mo catalysts for the hydrodesulfurization of dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was studied using a set of physicochemical and catalytic techniques. It was found that the introduction of modifying additives decreased the surface concentration of Lewis acid sites (LASs) and increased the concentration of basic sites (BSs) in aluminum-containing supports; these changes were more significant upon modification with lanthanum and strontium. The modification affected the distribution and degree of dispersion of Co-Mo-S sulfide packets. It was found that the rate constants of DBT and 4-MDBT conversion increased with decreasing total surface concentration of both LASs and BSs on the support. The highest rate constant of 4,6-DMDBT conversion was reached at an optimum concentration of weak Lewis sites on Co-Mo catalysts, whose support was modified with strontium or barium.

Full text of DOI:10.1134/S0023158411030128

ISSN 0023ꢀ1584, Kinetics and Catalysis, 2011, Vol. 52, No. 4, pp. 579–594. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © E.V. Korneeva, A.S. Ivanova, G.A. Bukhtiyarova, P.V. Aleksandrov, V.I. Zaikovskii, I.P. Prosvirin, A.S. Noskov, 2011, published in Kinetika i Kataliz,
2011, Vol. 52, No. 4, pp. 589–604.
Effect of the Nature of the Additives of Metal Cations (Sr, Ba,
and La) on the Properties of Co–Mo Hydrodesulfurization Catalysts
E. V. Korneeva, A. S. Ivanova, G. A. Bukhtiyarova, P. V. Aleksandrov,
V. I. Zaikovskii, I. P. Prosvirin, and A. S. Noskov
Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
eꢀmail: kulko@catalysis.nsk.su
Received July 5, 2010
Abstract—The effect of the nature of the support modified with the ions of alkaline earth and rare earth eleꢀ
ments (Sr, Ba, and La) on the properties of Co–Mo catalysts for the hydrodesulfurization of dibenzothiophene
(DBT), 4ꢀmethyldibenzothiophene (4ꢀMDBT), and 4,6ꢀdimethyldibenzothiophene (4,6ꢀDMDBT) was studied
using a set of physicochemical and catalytic techniques. It was found that the introduction of modifying addiꢀ
tives decreased the surface concentration of Lewis acid sites (LASs) and increased the concentration of basic
sites (BSs) in aluminumꢀcontaining supports; these changes were more significant upon modification with
lanthanum and strontium. The modification affected the distribution and degree of dispersion of Co–Mo–
S sulfide packets. It was found that the rate constants of DBT and 4ꢀMDBT conversion increased with
decreasing total surface concentration of both LASs and BSs on the support. The highest rate constant of 4,6ꢀ
DMDBT conversion was reached at an optimum concentration of weak Lewis sites on Co–Mo catalysts,
whose support was modified with strontium or barium.
DOI: 10.1134/S0023158411030128
INTRODUCTION
increased the surface area of a boundary plane suitable
for promoting with cobalt. According to Wu et al. [15],
the addition of MgO effectively suppressed the formaꢀ
tion of an inactive phase of CoAl2O4 and prevented
coke formation reactions. The activity of a catalyst in
hydrodesulfurization can be considerably increased at
a high MgO content of the support. Analogous results
were obtained upon the modification of a support with
CaO [10]: Mo and Ni–Mo catalysts supported on aluꢀ
mina modified with CaO exhibited higher perforꢀ
mance characteristics in hydrodesulfurization and
hydrogenation and a lower degree of deactivation due
to coke deposition. This was due to structural differꢀ
ences between various Mo species formed on the surꢀ
face of a modified support. The presence of Ca2+ ions
inhibited the formation of MoO3 and Al2(MoO4)3
phases. It was found that the reason for the higher
observed catalytic activity of the samples on the modꢀ
ified support was a higher degree of sulfidation. Thus,
the Ni–Mo/Al–Ca sample exhibited higher catalytic
activity before and after coke formation. In this samꢀ
Numerous sources of environmental pollution
include insufficiently purified fuels containing sulfur
and other impurities. Therefore, hydrofining is a basic
largeꢀscale process of petroleum refining, and its role
increases because of stricter requirements imposed on
the sulfur contents of gasoline and diesel fuel [1, 2].
Sulfide Co(Ni)–Mo catalysts supported on Al2O3
are widely used in the hydrodesulfurization of fuels [3, 4].
The activity of the Co(Ni)–Mo catalysts depends on
the degree of dispersion of the active constituent and
its distribution on the support surface, as well as on the
ease of sulfidation. These properties mainly depend on
the nature of the support, primarily, on the degree of
its interaction with the active constituent [5–7]. In
addition to acid supports, such as Al2O3, SiO2–Al2O3
,
and zeolites [4, 7–9], basic systems are of considerable
interest, and the applicability of these systems as cataꢀ
lyst supports has been studied [10–12]. Such supports
are interesting for the following two reasons: First, the
acid–base interaction between acid МоО3 and a basic
support in an oxide precursor of sulfide catalysts facilꢀ ple, the degree of molybdenum reduction to Mo4+
itates the high and stable degree of dispersion of a Moꢀ (i.e., the ratio Mo4+/(Mo5+ + Mo6+)) was lower but the
degree of sulfidation (the ratio S/Mo4+) was higher
than those in the samples containing the unmodified
support. It is well known that the electronegativity of
the La3+, Sr2+, and Ba2+ ions is lower than that of the
Mg2+ ion. However, there are almost no published data
containing component. Second, the basic nature of
the support inhibits coking, which intensely occurs on
aluminum oxide catalysts [13].
In particular, Zdra
zil [14] demonstrated that the
introduction of MgO into an aluminum oxide support
facilitated the formation of short MoS2 packets and on the influence of La2O3, SrO, and BaO introduced
579

580
KORNEEVA et al.
into aluminum oxide on the properties of the resulting
Co–Mo hydrodesulfuriza ion catalysts.
Texture characteristics. The texture characteristics
of the samples were determined on an ASAPꢀ2400
instrument (Micromeritics) from the isotherms of
t
This work was devoted to a study of the effect of the
nature and concentration of alkalineꢀearth and rareꢀ
earth oxides introduced into aluminum on the physicꢀ
ochemical and catalytic properties of Co–Mo cataꢀ
lysts for the hydrodesulfurization of fuels.
lowꢀtemperature (–196
samples were preliminarily kept in a vacuum at 150
the error of the method was 10%
°
С) nitrogen adsorption; the
°
С;
.
Surface acid–base properties. The surface acid–
base properties of the samples were studied by the IR
spectroscopy of adsorbed probe molecules (CO and
СDCl3) [16]. The IR spectra were recorded on a Shiꢀ
madzu 8300 Fourier transform spectrometer in the
range of 1200–4000 cm–1 with a resolution of 4 cm–1;
50 scans were accumulated for each spectrum. The
samples were pressed as pellets with a density of (10–
EXPERIMENTAL
Preparation of supports. Aluminum hydroxides
modified with alkalineꢀearth and rareꢀearth cations M
(M = Sr, Ba, and La) were obtained by precipitation
from the mixed solutions of the corresponding salts with
20)
ated in an IR cell to a residual pressure of <10–4 Torr at
500 for 2 h.
×
10–3 g/cm2 without a binding agent and evacuꢀ
a solution of ammonium bicarbonate (NH4HCO3,
1.055–1.064 g/cm3) at a constant pH ~7.0–7.2 and a
temperature of 70 C with the subsequent aging of the
suspension for 3 h. Pure aluminum hydroxide was preꢀ
pared in a similar way. The salts were Al(NO3)3 9H2O,
La(NO3)3 6H2O, Sr(NO3)2, and Ba(NO3)2. After aging,
ρ
=
°
С
°
Acid sites were determined using the adsorption of
CO, which forms complexes with the Lewis and Brønꢀ
sted acid sites (LASs and BASs, respectively). The
adsorption of CO was conducted at a liquid nitrogen
⋅
⋅
the suspension was filtered and washed with distilled
water. The precipitate was dried in air and then in a
temperature (–196 С) and РСО = 0.1–10 Torr. An
°
increase in the frequency of the vibrations of adsorbed
CO relatively to the value for the gaseous molecule
ν
drying oven at 120
were calcined at 550
°
С
°
for 16–18 h. Then, the samples
С for 4 h in a flow of dried air.
(
(СО) = 2143 cm–1) was caused by the formation of
The supports were designated as AMn, where A is
Al2O3, M = S, B, or L (S is SrO, B is BaO, and L is
La2O3), and n = 1 or 5 mol %.
complexes with LASs. The shift of the band (СО) to
ν
the region of high frequencies characterizes the
strength if LASs because it is related to the heat of forꢀ
mation of complexes by the equation QCO [kJ/mol] =
Preparation of catalysts. The catalysts were preꢀ
pared by the incipient wetness impregnation of a supꢀ
10.5 + 0.5( (СО) – 2143). The concentration of
ν
port (fraction of 0.125–0.250
of corresponding salts, as which ammonium paramoꢀ
lybdate (NH4)6Mo7O24 4H2O and cobalt nitrate
Co(NO3)2 4H2O were used. The support was impregꢀ
nated in two stages. After the first stage, the samples
were dried in a drying oven at 120 for 16 h; then, the
temperature was increased to 250 and the samples
were additionally exposed for 4 h. After the second stage,
the samples were dried at 120 for 16 h and then calꢀ
cined at 550 for 4 h in an inert atmosphere. Then, the
µm) with the solutions
LASs was measured from the integrated intensity of
bands due to adsorbed CO (in the spectral region of
⋅
2185–2240 cm–1) using the formula
N
[
µmol/g] =
⋅
A/A0, where А is the integrated intensity of the band of
adsorbed CO, and А0 is the integral absorption coeffiꢀ
cient [16].
Basic sites (BSs) were determined using the
adsorption of deuterochloroform (CDCl3). Deuteroꢀ
°
С
°С
°С
chloroform was adsorbed at
to the pressure of CDCl3 vapor at 20
0
°
С
and a pressure equal
. The decomꢀ
°С
°
C
resulting oxide catalyst precursors were sulfidized. The
catalysts were designated as Co–Mo/AMn.
position of CD bands in CDCl3 was performed taking
into account the following considerations: (1) the
minimization of the number of bands, (2) the Gaussꢀ
ian line shape, and (3) the broadening of absorption
bands upon shifting to the region of low frequencies.
The IR spectra were normalized to the pellet denꢀ
sity. The accuracy of concentration measurements was
The resulting samples were studied by physicoꢀ
chemical techniques.
Xꢀray diffraction (XRD) analysis. XRD analysis was
performed on an ARL X’TRA diffractometer with
monochromatic Cu
K
radiation (
λ
= 1.5418 Å). The
measurements were performed by pointꢀbyꢀpoint
scanning in the range of angles from 10 to 75 at the
scanning step = 0.05 and an accumulation time of scopic studies of the samples were conducted on a
α
15%
.
2θ
°
Electron microscopic studies. The electron microꢀ
τ
°
3–5 s at each point. Phase analysis was carried out by JEMꢀ2010 transmission electron microscope (JEOL)
comparing the calculated values of interplanar spacing (resolution, 0.14 nm; accelerating voltage, 200 kV).
di and the corresponding intensities of diffraction Local energyꢀdispersive xꢀray analysis (EDX), which
peaks Ii with theoretical values from the JCPDS dataꢀ was carried out on an EDAX spectrometer (EDAX
base (PCPDF Win. Ver. 1.30, JCPDS ICDD, Swarthꢀ Co.), was used for determining the concentrations of
more, PA, USA, 1997).
elements and ratios between them. The test samples
KINETICS AND CATALYSIS Vol. 52
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2011

EFFECT OF THE NATURE OF THE ADDITIVES OF METAL CATIONS
581
were supported onto a carbon substrate immobilized with a JAS atomicꢀemission detector (from the emisꢀ
on copper gauze.
Xꢀray photoelectron spectroscopy (XPS). The Xꢀray
photoelectron spectra of Co–Mo/AMn were obtained
sion line of sulfur atoms at 181 nm). The components
were separated on an HPꢀ1MS capillary column
(60.0 m
×
250
µm
×
1.00 m). The rate constants were
µ
calculated from the pseudoꢀfirstꢀorder equation with
respect to the concentration of sulfurꢀcontaining
compounds:
on a SPECS spectrometer using Al
1486.6 eV). The samples were supported onto doubleꢀ
sided conducting copper Scotch tape. The C1 line
K
radiation (
h =
ν
α
s
(284.8 eV) from carbon, which was present on the catꢀ
alyst surface, was used for calibration. Survey spectra
were written at a transmission energy of 50 eV; individꢀ
ual sections were written at 20 eV. The relative concenꢀ
trations of elements on the catalyst surfaces and the
ratios between their atomic concentrations were deterꢀ
mined from the integrated intensities of photoelectron
lines corrected for the appropriate atomic sensitivity
coefficients [17].
Catalytic activity. The activity of catalysts in the
reactions of dibenzothiophene (DBT), 4ꢀmethꢀ
yldibenzothiophene (4ꢀMDBT), and 4,6ꢀdimethꢀ
yldibenzothiophene (4,6ꢀDMDBT) hydrodesulfurꢀ
ization was determined in a 300ꢀml batch reactor
(Autoclave Engineers type MagneꢀDrive), which was
equipped with a system for sampling liquids at regular
intervals in the course of reaction. The experiments
were carried out at a hydrogen pressure of 3.5 MPa,
−ln(1 − x)
Ki =
,
t
where
x
is conversion, t is time, and i refers to DBT, 4ꢀ
MDBT, or 4,6ꢀDMDBT.
RESULTS AND DISCUSSION
Characteristics of the Supports
Phase composition and texture. According to XRD
data (Fig. 1), samples AMn containing 1 and 5 mol %
MxOy calcined at 550 С are Xꢀray amorphous; that
is, the modification of aluminum oxide with the
specified components leads to its amorphization
regardless of the nature and concentration of the
introduced additive.
Table 1 summarizes the texture characteristics aluꢀ
minum oxide modified with Sr, Ba, and La cations and
°
calcined at 550 C. It is evident that the introduction of
°
340 С, and 1000 rpm; the duration of the experiments
°
1 mol % MxOy considerably decreased the specific surꢀ
face area of the modified samples (AS1, AB1, and
AL1; 135–200 m2/g), as compared with aluminum
oxide (A, 300 m2/g). Simultaneously, an insignificant
decrease in the pore volume from 1.00 cm3/g for samꢀ
ple A to 0.85 cm3/g for AS1 and AL1 was observed; in
this case, the mean pore diameter increased from
14 nm for Al2O3 to 17.5–25.5 nm in the modified
samples.
An increase in the concentration of a modifying
additive to 5 mol % MxOy resulted in a further decrease
in the specific surface area of modified samples AS5
and AL5 (115–120 m2/g) (Table 1); furthermore, the
pore volume further decreased. Bariumꢀmodified
sample AB5 is the exception: the specific surface area
and pore volume remained almost the same as those
upon the introduction of 1 mol % BaO (Table 1). A
possible reason for the observed effect is that barium
carbonate is formed as the fraction of barium in the
sample is increased. Barium carbonate is characterꢀ
ized by insignificant degree of dispersion; conseꢀ
quently, it does not exert a noticeable effect on the texꢀ
ture characteristics of the sample.
was 6 h. For determining the catalytic activity, 3 g of a
catalyst and 150 ml of a reaction mixture were used in
each particular cycle. Test samples were taken at reguꢀ
lar intervals of 1 h.
The reaction mixture containing 500 ppm of DBT,
250 ppm of 4ꢀMDBT, and 80 ppm of 4,6ꢀDMDBT
was prepared by the dissolution of the model subꢀ
stances in diesel fuel, which was obtained as a result of
the hydrofining of straightꢀrun gas oil containing
8 ppm of S, 7 ppm of N, and monoꢀ, diꢀ, and polycyꢀ
clic aromatic compounds (21.7, 1.89, and 0.81 wt %,
respectively). In order to eliminate the effect H2S on
the activity of the samples, an excess amount of dimeꢀ
thyl disulfide, which corresponded to 1.2 wt % sulfur,
was added to the reaction mixture. Under these condiꢀ
tions, the absence of external and/or internal diffusion
limitations was confirmed by additional experiments.
In an individual series of experiments performed with
catalyst fractions of 0.08–0.125, 0.125–0.18, 0.18–
0.25, and 0.25–0.50 mm under the same conditions,
we found that the catalyst activity does not depend on
particle size in the range of 0.08–0.25 mm; this sugꢀ
gests the kinetic region of the reaction.
Acid–base properties of the supports. Figure 2
shows the spectra of the samples after evacuation at
500°С. In the spectra of samples AS1, AS5, AB1,
AB5, AL1, and AL5, absorption bands at 1380–1480
and 2340 cm–1 indicate the presence of the carbonate
Before testing the catalysts, their oxide precursors
were sulfidized in a tube reactor at 400 С for 4 h in a
°
flow of 10 vol % H2S in H2 at atmospheric pressure.
The concentrations of the sulfurꢀcontaining comꢀ
pounds (DBT, 4ꢀMDBT, and 4,6ꢀDMDBT) in the test
samples were determined by gas chromatography with
the use of an Agilent 6890N chromatograph equipped
ion
2− and СО2, respectively (it is likely that the latꢀ
CO3
ter was due to the encapsulation of СО2 in closed
KINETICS AND CATALYSIS Vol. 52
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2011

582
KORNEEVA et al.
AL5
AL1
AB5
AB1
AS5
AS1
A
10
20
30
40
50
60
70
80
2θ, deg
Fig. 1. Diffraction patterns of aluminum oxide modified with cations of alkalineꢀearth and rareꢀearth elements.
pores). These structures were absent from the specꢀ 3770, and 3785 cm–1. The samples modified with alkaꢀ
trum of the parent aluminum oxide. We can conclude
that carbonate species are formed on the surface of the
modified samples. Therefore, the modification of the
Al2O3 surface with alkalineꢀearth or rareꢀearth metal
ions leads to a considerable increase in the number of
basic sites, which are sufficiently strong to interact
with СО2 at room temperature.
lineꢀearth or rareꢀearth metal ions exhibited a considꢀ
erable decrease in the intensity of the corresponding
bands. Furthermore, it is likely that an absorption
band at 3600 cm–1 was due to the presence of an M–
OH bond in the modified samples.
According to data given in Table 2, the total concenꢀ
tration of OH groups decreases in the following order:
In the spectrum of Al2O3 in the region of hydroxyl
groups, absorption bands due to the vibrations of
hydroxyl groups (ν(ОН)) were observed at 3680, 3730,
sample
mol/g
A > AL1 > AS1
≈
AB1 > AS5 > AB5 > AL5
μ
675 348 232 229 205 187 175.
Table 1. Texture characteristics of the supports according to data on lowꢀtemperature nitrogen adsorption
Modifier
and its concentration
Sample
Designation
S
BET, m2/g
V
pore, cm3/g
D
av, nm
14.0
M
–
MxOy, mol %
Al O
–
1
A
300
1.00
2
3
Al O –SrO(1)
Sr
Ba
La
AS1
AB1
AL1
135
155
200
0.85
1.00
0.85
25.5
25.0
17.5
2
3
Al O –BaO(1)
2
3
Al O –La O (1)
2
3
2 3
Al O –SrO(5)
Sr
Ba
La
5
AS5
AB5
AL5
115
155
120
0.65
0.90
0.55
22.5
22.5
19.0
2
3
Al O –BaO(5)
2
3
Al O –La O (5)
2
3
2 3
KINETICS AND CATALYSIS Vol. 52
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2011

EFFECT OF THE NATURE OF THE ADDITIVES OF METAL CATIONS
583
(а)
Al2O3
AB1
AB5
1200
1600
2000
2400
3200
3400
3600
3800
ν
, cm–1
(b)
AS1
AS5
AL1
AL5
AS1
AS5
AL1
AL5
1200
1600
2000
2400
3200
3400
3600
3800
ν
, cm–1
Fig. 2. IR spectra of support samples after evacuation at 500°C: (a) Al O , AB1, and AB5; (b) AS1, AS5, AL1, and AL5.
2 3
In this case, the total concentration of terminal caused by the nature and concentration of the modiꢀ
(3700–3790 cm–1) and bridging (3660–3680 cm–1) fier additive were insignificant (Table 2).
OH groups changed in the following order:
Figure 3 shows the spectra of adsorbed CO in the
regions of (СО) and hydroxyl groups; the pressure of
CO was changed from 0.1 to 10 Torr. In the spectra of
CO adsorbed on the samples modified with MxOy, an
absorption band appeared at 2165–2175 cm–1 (Fig. 3)
ν
Cterm A > AL1 > AB5 > AS1 > AL5 > AS5 > AB1
Cbridg A > AL1 > AS1 >AL5 > AB5 > AB1 > AS5.
Note that the concentration of bridging OH groups due to CO complexes with weaker LASs (as compared
in the modified samples was much lower than that in with Al2O3); this absorption band did not manifest
the parent aluminum oxide; in this case, differences itself in the spectra of CO on Al2O3. It is likely that it
KINETICS AND CATALYSIS Vol. 52
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2011

584
KORNEEVA et al.
Table 2. Positions of absorption band maximums due to support hydroxyl groups and concentrations of these groups
ν
, cm–1
∑OH
Sample
3660–3665 3670–3680 3700–3710
3730
3750
mol/g
80
3773
3790
(
Cterm Cbridg)
/
Concentration of OH groups,
μ
A
132
28
12
10
17
9
176
11
20
41
11
22
9
58
71
163
41
43
77
39
45
46
35
–
–
–
–
–
–
31
24
45
38
24
–
675 (367/308)
232 (193/39)
229 (197/32)
348 (297/51)
205 (178/28)
187 (156/31)
175 (186/33)
AS1
AB1
AL1
AS5
AB5
AL5
56
33
77
50
63
44
76
105
65
48
24
75
21
Table 3. Positions of absorption band maximums due to CO adsorbed on the supports and the concentrations of LASs
, cm–1
ν
Σ
LASs,
μ
mol/g
Sample
2165–2175
2185–2200
2214
mol/g (
2225
(
μ
mol/m2)
Concentration of LASs,
625 (2.08)
μ
μ
mol/m2)
A
–
7.2 (0.03)
4 (0.01)
636 (2.12)
AS1
AB1
AL1
125 (0.91)
62 (0.40)
112 (0.56)
212 (1.55)
188 (1.20)
269 (1.35)
16 (0.12)
8 (0.12)
–
–
–
353 (2.58)
268 (1.70)
395 (1.98)
14.5 (0.07)
AS5
AB5
AL5
188 (1.61)
125 (0.79)
375 (3.12)
125 (1.07)
162 (1.02)
88 (0.73)
13.6 (0.12)
23 (0.14)
11 (0.09)
–
–
–
327 (2.79)
310 (1.95)
474 (3.95)
belongs to the complexes of CO with the coordinaꢀ Al2O3 has a low intensity, and it does not appear in the
tively unsaturated modifying ions Sr2+, Ba2+, and La3+
.
spectra of CO on the modified samples.
Furthermore, the intensity of bands in the region of
2185–2200 cm–1 for the modified samples was much
lower than that for Al2O3, and, on the contrary, the
intensity of bands at 2214 cm–1 was higher. The
absorption band with a frequency of 2225 cm–1, which
Table 3 summarizes the concentrations of LASs of
different strengths and the total concentrations of
LASs in the test samples. The experimental data sugꢀ
gest that the concentration of LASs (on a square meter
basis) corresponding to an absorption band at 2165–
characterizes strong LASs, in the spectrum of CO on 2175 cm–1 decreases in the order AL5 > AS5 > AS1
≈
KINETICS AND CATALYSIS Vol. 52
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2011

EFFECT OF THE NATURE OF THE ADDITIVES OF METAL CATIONS
(а) (b)
585
Al2O3
AS5
AS1
2050
2100
2150
, cm–1
2200
2250
2050 2100 2150 2200 2250 2050 2100 2150 2200 2250
, cm–1
ν
ν
(c)
(d)
AL5
AL1
AВ5
AВ1
2050 2100 2150 2200
2050 2100 2150 2200 2250 2050 2100 2150 2200 2250 2050 2100 2150 2200 2250
, cm–1
2250
ν
, cm–1
ν
Fig. 3. IR spectra of CO adsorbed on the following supports at pressures changed from 0.1 to 10 Torr: (a) Al O , (b) AS1 and AS5,
2
3
(c) AB1 and AB5, and (d) AL1 and AL5.
AB5 > AL1 > AB1; that is, the smallest concentration range of 0.03–0.14
µ
mol/m2 (Table 3). The total conꢀ
LASs) (on a square meter basis)
changes as follows: AL5 > AS5 > AS1 > A > AL1
centrations of LASs (
Σ
of these sites is observed in the samples modified with
barium. This is additional evidence for the fact that
barium primarily interacts with СО2 to form carbonate
≈
AB5 > AB1. Thus, the modification aluminum oxide
with the cations of alkalineꢀearth and rareꢀearth eleꢀ
ments leads to the appearance of weaker LASs and a
decrease in the concentration of mediumꢀstrength
LASs. Furthermore, the total concentration of LASs
increases upon the introduction of strontium and lanꢀ
thanum cations into Al2O3 and decreases upon the
introduction of barium cations.
and, to a lesser degree, with Al2O3 at 550 С. The conꢀ
°
centration of LASs (on a square meter basis) correꢀ
sponding to an absorption band at 2185–2200 cm–1
decreases in the order A > AS1 > AL1 > AB1 > AS5 >
AB5 > AL5. Consequently, the introduction of modiꢀ
fying additives and an increase in their fraction faciliꢀ
tate the monotonic decrease in the concentration of
these LASs. The concentration of LASs (on a square
meter basis) corresponding to an absorption band at
The basicity of samples was characterized using the
spectra of adsorbed deuterochloroform (Fig. 4). Deuꢀ
terated chloroform forms hydrogen bonds with surface
2214 cm–1 decreases in the order AB5 > AS1
≈
AB1
≈
AS5 > AL5 > AL1 > A; in this case, it varies in the BSs. As the strength of sites increased, the frequency
KINETICS AND CATALYSIS Vol. 52
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2011

586
KORNEEVA et al.
(а)
Al2O3
AS1
AS5
AL1
AL5
Al2O3
AB1
AB5
AL1
AB1
AB5
AL5
AS5
AS1
2150
2200
2250
2300 2150
, cm–1
2200
2250
2300
ν
(b)
Al2O3
AS1
2233
2245
2200
2200
2150
2200
2250
2300
2150
, см–1
2250
2300
ν
Fig. 4. (a) IR spectra of CDCl adsorbed on aluminum oxide and modified samples; (b) examples of the deconvolution of the
3
spectrum of CDCl adsorbed on Al O and АS1.
3
2 3
of an absorption band due to the C–D bond of strong BSs. In this case, the greatest effect is
decreased. Three components can be recognized in achieved upon the introduction of strontium and lanꢀ
the spectra of adsorbed CDCl3 (Fig. 4b); they correꢀ thanum rather than barium cations into Al2O3. This
spond to BSs of different strengths. The first, second, result is somewhat unexpected, if one takes into
and third ones components with
ν(CD) = 2245, account the electronegativity values of the introduced
2227–2233, and 2200 cm–1 have strengths of 860, 890, cations of alkalineꢀearth and rareꢀearth elements [18],
and 930 kJ/mol, respectively. Table 4 summarizes the according to which barium is characterized by the
concentrations of the strongest BSs, for which PA = greatest basicity. It is likely that a lowered concentraꢀ
930 kJ/mol, and the total concentrations of BSs. The tion of strong BSs on the surfaces of samples ABn is
surface concentration of strong BSs (on a square meter caused by the fact that they easily interact with atmoꢀ
basis) increases in the order A < AL1 < AB5 < AS1 < spheric CO2 with the formation of surface carbonate
AB1 < AL5
≈
AS5; that is, the introduction of modifyꢀ species, and they cannot be detected in a study with
ing additives leads to an increase in the concentration probes like CDCl3. Weaker BSs, which are close to the
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EFFECT OF THE NATURE OF THE ADDITIVES OF METAL CATIONS
587
Table 4. Positions of absorption band maximums due to
CDCl3 adsorbed on the supports and the concentrations
of BSs
surface sites of Al2O3 in strength, slowly react with
atmospheric carbon dioxide.
According to data given in Table 4, the total conꢀ
centration of BSs on the surface of the samples under
investigation changes in the order AL5 > AS5 > AB1 >
Concentration of BSs,
μmol/g
Σ
BSs,
μ
mol/g
Samꢀ
ple
(μ
mol/m2) – ( , cm–1)
ν
(μ
mol/m2)
AB5 > AL1 AS1 > A. The found total concentrations
≈
A
50 (0.17) – (2198)
530 (1.8)
of BSs on the surfaces of the specified samples are
comparable in the absolute value with the total conꢀ
centration of LASs (Table 3).
AS1
AB1
AL1
40 (0.29) – (2200)
48 (0.31) – (2205)
40 (0.20) – (2200)
293 (2.1)
390 (2.5)
423 (2.1)
AS5
AB5
AL5
40 (0.34) – (2202)
42 (0.26) – (2198)
40 (0.33) – (2198)
300 (2.6)
383 (2.4)
366 (3.1)
Catalyst Characterization
Pure aluminum oxide and Al2O3 modified with the
cations of alkalineꢀearth and rareꢀearth elements in
amounts of 1 and 5 mol % were used as supports for
Co–Mo hydrodesulfurization catalysts. The concenꢀ
trations of active components in the catalysts were
6 0.2) wt % CoO and (19 0.2) wt % MoO3. The
resulting Co–Mo catalysts were characterized after
performing a hydrodesulfurization process.
Highꢀresolution transmission electron microscopy
(HRTEM). According to electronꢀmicroscopic data,
the support of sample Co–Mo/A has a spongy
(block/mesoporous) morphology and consists of
agglomerated partially coalesced isometric crystallites
with a characteristic size of ~7 nm. The active compoꢀ
nent as Co–Mo–S sulfide packets is located on the
surface of Al2O3 particles and has a diameter of 5–
7 nm and a thickness from one (predominantly) to
three monolayers (more rarely) (Fig. 5).
The morphology of the support particles of sample
Co–Mo/AS1 (Fig. 6) differed from the above in an
increase in the porosity (the observed mesopore size
was about 5 nm). Taking into account the results of
XRD analysis, we can assume that a modifying addiꢀ
tive (strontium) partially interacts with aluminum
The Co–Mo–S sulfide packets of this sample are
identical to those of sample Co–Mo/A in terms of
morphology; however, their degree of dispersion is
higher. The particle size distribution of Co–Mo–S
shows an increase in the number of islets with diameters
to 2 nm.
(
The morphology and particle size of sample Co–
Mo/AB1 (Fig. 7) are almost identical to those of samꢀ
ple Co–Mo/AS1 (Fig. 6). However, in this sample, a
portion of barium unreacted with aluminum oxide
forms a highly dispersed Baꢀcontaining compound
with the particle sizes of 2–3 nm (Fig. 7c), which
manifests itself in an increase in the concentration of
this compound. In this case, large BaO particles were
not detected in the sample. According to EDX analysis
data, the concentrations of Ba determined in different
chosen sections (Figs. 7a, 7b) proved to be the same
(Fig. 7d) and equal to 0.88–0.84 at % at an Al concenꢀ
tration of 99.16–99.12 at %.
For sample Co–Mo/AL1, the morphology of supꢀ
oxide. Another portion of strontium forms the oxide port particles and the morphology and size of Co–
SrO, whose particle size is as great as 10 nm (Fig. 6). Mo–S sulfide packets (Fig. 8a) are analogous to those
20 nm
20 nm
(a)
(b)
Fig. 5. HRTEM images of (a, b) different areas of Co–Mo/A.
KINETICS AND CATALYSIS Vol. 52 No. 4 2011

588
KORNEEVA et al.
20 nm
(b)
10 nm
(a)
Fig. 6. HRTEM images of Co–Mo/AS1: (a) sulfide packets on the catalyst surface and (b) formation of SrO particles.
in sample Co–Mo/A. However, large particles C 1s, O 1s, Co 2p3/2, Sr 3d5/2, Ba 3d5/2, and La 3d5/2) in
(~10 nm) (Fig. 8b), were present in this sample; order to determine their chemical states (Table 5). The
according to EDXꢀanalysis data, these particles can be comparison of the binding energies of the correspondꢀ
attributed to the oxide compounds of La. Conseꢀ ing elements indicates that the values of Eb (Al 2
p),
quently, the promotion of aluminum oxide with lanꢀ (Al 2 ), (S 2 ), (C 1 , and (O 1 ) are 74.7, 119.5,
s
p
s)
s
thanum does not change the morphology and particle 162.3, 284.8, and 531.7 eV, respectively, regardless of
size of Al2O3, but it is accompanied by the formation of the nature of the catalyst.
bulky large Laꢀcontaining particles. The sizes of Co–
Mo–S sulfide packets located on the surface of the
large oxide Laꢀcontaining particles are increased: the
diameters are as great as 20 nm, and the thickness is to
five sulfide layers. This can suggest that the introducꢀ
tion of La leads to a strengthening of the bond of a sulꢀ
fide component with the modified support.
From an analysis of the S 2s + Mo 3d5/2 XPS spectra
of the test samples (Fig. 9), it follows that a peak with
the lowest binding energy (Eb = 226.3 eV) belongs to
sulfur (the S 2s level). In order to more accurately
determine the ratio between the sulfide and oxide
forms of molybdenum, we performed the deconvoluꢀ
tion of the Mo 3d5/2 line into individual spectral comꢀ
Xꢀray photoelectron spectroscopy (XPS). For the ponents with the use of the XPSꢀPeak software taking
catalysts prepared with the use of unmodified alumiꢀ into account the contribution of S 2 peaks to the total
num oxide and aluminum oxide modified with 1 mol % S 2 + Mo 3d5/2 spectrum (Fig. 9). The Mo 3d5/2 specꢀ
s
s
МхОy, XPS spectra were measured in the spectral trum exhibited two main peaks with Eb = 229.2 and
regions corresponding to the binding energies of eleꢀ 232.8 eV, which can be attributed to molybdenum in a
ments present in the samples (Al 2
p
, S 2
p
, Mo 3d5/2
,
sulfide environment (for example, in the compound
Table 5. Binding energies for the elements in catalyst samples according to XPS data
b, eV
O 1
E
Sample
Al 2p
Al 2
s
S 2
p
Mo 3
d
C 1
s
s
Co 2
p
Sr 3d
Ba 3d
La 3d
779.3
782.0
Co–Mo/A
74.7
119.6
162.4
229.2
284.8
531.7
–
–
–
779.2
781.9
Co–Mo/AS1
Co–Mo/AB1
Co–Mo/AL1
74.7
74.7
74.7
119.5
119.5
119.6
162.3
162.3
162.3
229.2
229.1
229.1
284.8
284.8
284.8
531.7
531.7
531.7
134.5
–
–
–
–
779.4
780.6
–
779.3
781.9
–
835.7
2011
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EFFECT OF THE NATURE OF THE ADDITIVES OF METAL CATIONS
589
200 nm
(b)
200 nm
(а)
20 nm
(c)
(d)
BaL
AlK
O K
3.0 3.3 3.6 3.9 4.2 4.5 4.8 5.1 5.4 5.7
E
S K
, keV
CuL
CoL
C K
CoK
P K
2.25
BaL
4.50
FeK
0
0.75
1.50
3.00
3.75
5.25
6.00 6.75
E
b, keV
Fig. 7. HRTEM images of Co–Mo/AB1: (a, b) EDX analysis areas, (c) sulfide packets on the catalyst surface, and (d) EDX analꢀ
ysis (see the text for details).
MoS2), where the formal state of molybdenum is
The Co 2p3/2 XPS spectra of the test samples (Fig. 10)
Mo4+, and to molybdenum in the state Mo6+ in an also contain two peaks with the binding energies of
oxygen environment, respectively (for example, 779.2 and 782.0 eV; the smaller value (779.1 0.1 eV) is
MoO3, Al2(MoO4)3, or CoMoO4) [19–23].
characteristic of cobalt in a sulfide environment, and
KINETICS AND CATALYSIS Vol. 52
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2011

590
KORNEEVA et al.
20 nm
(b)
20 nm
(a)
Fig. 8. HRTEM images of Co–Mo/AL1: (a) sulfide packets on the catalyst surface and (b) formation of lanthanum oxide particles.
the greater value (782.0 0.1 eV) is characteristic of the 134.5 eV. According to published data [24–30], the
state Co2+ in an oxygen environment [19–23]. It binding energy of Sr 3d5/2 lies in the ranges of 131.7–
should be noted that, for sample Co–Mo/AB1, the 132.4, 132.8, 133.4–133.8, and 133.6–134.1 eV for
analysis of the chemical state of cobalt is considerably
difficult to perform as a result of the overlapping of
strontium as the constituent of SrO, Sr(OH)2, SrCO3
and strontium hydroxo carbonates, respectively. Conꢀ
sequently, the observed peak can be attributed to a
hydroxo carbonate form of strontium [24, 25].
Co 2
the catalyst and support containing BaO and the difꢀ
ference spectrum normalized to the Al 2 peak intenꢀ
p and Ba 3d peaks. Figure 11 shows the spectra of
p
For all of the test samples, the S 2p spectrum
sity. We found that the qualitative pattern obtained
after the measurement of the difference spectrum was
approximately the same as that for the other samples;
however, the ratio between the sulfide and oxide forms
of cobalt cannot be reliably determined.
Some difficulties appear in the identification of
strontium in sample Co–Mo/AS1 as a result of the
low intensity of photoelectron peaks characteristic of
strontium (Fig. 12). The binding energy of Sr 3d5/2 is
(Fig. 13) exhibited two peaks with the binding energies
of 162.2 0.2 and 169.3 eV. The binding energy of the
former peak is characteristic of sulfide ions (sulfur is in
the state S2–), and that of the latter peak is characterꢀ
istic of sulfate ions (S
O24– ), which are likely bound to
aluminum in the form of Al2(SO4)3 [22, 31, 32]. It is
evident from the above spectra that the fractions of sulꢀ
fide (Sd is sulfide) and sulfate (St is sulfate) states of
232.8
229.2
S 2s
+ Mo 3d5/2
779.2
Co 2p3/2
782.0
226.3
Co–Mo/AS1
Co–Mo/AS1
Co–Mo/AB1
Co–Mo/AL1
Co–Mo/A
Co–Mo/AB1
Co–Mo/AL1
Co–Mo/A
224 226 228 230 232 234 236 238 240
Binding energy, eV
765 770 775 780 785 790 795 800 805 810 815
Binding energy, eV
Fig. 9. The Mo 3
d
XPS spectra of Co–Mo/AM1 samples
5/2
and the decomposition of lines into individual spectral comꢀ
ponents.
Fig. 10. The Co 2
p
XPS spectra of Co–Mo/AM1 samples.
3/2
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EFFECT OF THE NATURE OF THE ADDITIVES OF METAL CATIONS
591
Co 2
p
+ Ва 3
779.0
780.5
782.3
d
134.5
1
2
3
– Co–Mo/AB1
– AB1
Difference
spectrum
Sr 3d5/2
–
2
1
3
775 780 785 790 795 800 805 810
Binding energy, eV
126 128 130 132 134 136 138 140 142
Binding energy, eV
Fig. 11. The Co 2
p
XPS spectra of AB1 samples and
3/2
Fig. 12. The Sr 3
d
XPS spectra of Co–Mo/AS1 samples.
Co–Mo/AB1 (see the text for details).
5/2
sulfurs are different in different samples, and the ratio
Sd/St varies over the range of 1.96–2.50 (Table 6).
A comparison of the rate constants of conversion of
DBT and 4ꢀMDBT on the test catalysts and the conꢀ
centrations of LASs and BSs on the surfaces of correꢀ
sponding supports AMn shows (Table 8) that the conꢀ
The relative concentrations of the elements on the
catalyst surfaces and the ratios between atomic conꢀ
centrations were determined from the integrated
intensities of lines in the XPS spectra corrected for the
appropriate atomic sensitivity coefficients. According
to the experimental results (Table 6), the Co : Mo surꢀ
face ratio decreases in the following order of the cataꢀ
stants kDBT and k4ꢀMDBT change in the same sequence:
the greatest value was observed on the catalysts preꢀ
pared with the use of supports AM1, where M is Sr or
La. In this case, the lower the total surface concentraꢀ
tion of LASs and BSs, the higher the rate constant of
conversion with few exceptions (which are acceptable
with consideration for current errors in the determinaꢀ
tion of rate constants and surface concentrations of
acid and basic sites).
lysts: Co–Mo/A > Co–Mo/AL1
≈
Co–Mo/AB1 >
Co–Mo/AS1. The fraction of the sulfide form of
molybdenum (Mo4+/Mototal) decreases in the same
order. In this case, the Mo : Al, O : Al, and S : Al surꢀ
face ratios are almost independent of the nature of the
modifying additive and change within the limits of
experimental error.
The above sequence changes for the rate constants
of conversion of 4,6ꢀDMDBT, namely, the highest
Catalytic activity tests. Table 7 lists the rate conꢀ
stants of the hydrodesulfurization reaction for three
model substances and seven catalysts. According to
the results obtained, an increase in the rate constants
of conversion of all of the three reaction mixture comꢀ
ponents was observed on Co–Mo catalysts prepared
with the use of samples AMn containing ~1 mol %
MxOy as supports, as compared with catalyst Co–
Mo/A. An increase in the concentration of MxOy to
5 mol % was accompanied by a decrease in the rate
constants of conversion of all of the three reaction
mixture components, as compared with Со–
Мо/Al2O3; moreover, the conversion of 4,6ꢀDMDBT
on Co–Mo/AL5 did not occur. Another behavior is
162.2
S 2p
169.3
Co–Mo/AS1
Co–Mo/AB1
Co–Mo/AL1
Co–Mo/A
characteristic of Co–Mo/AB5, for which k4,6ꢀDMDBT is
154 156 158 160 162 164 166 168 170 172 174 176
Binding energy, eV
3.3 h–1, which is greater than that for Co–Mo/A by a
factor of about 1.4 (Table 7). It is believed that the
above reaction mixture components are converted at
different surface sites of a catalyst.
Fig. 13. The S 2p XPS spectra of Co–Mo/AM1 samples.
KINETICS AND CATALYSIS Vol. 52
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2011

592
KORNEEVA et al.
Table 6. Atomic concentrations of the elements on the surface of Co–Mo/AM1 samples according to XPS data
[Mo4+]/[Mo5++
[Mo4+]/[Mototal
]
[Sd]/[Mo4+]
[Sd]/[St]
Sample [Co]/[Mo] [Mo]/[Al] [Co]/[Al] [O]/[Al] [S]/[Al]
+ Mo6+]
Co–Mo/A
0.39
0.31
0.35
0.35
0.109
0.101
0.098
0.105
0.042
0.032
0.035
0.037
1.98
1.94
2.01
2.02
0.28
0.25
0.23
0.25
0.73
0.66
0.69
0.73
1.75
1.43
1.28
1.68
2.98
3.05
3.14
2.69
2.50
1.96
2.13
2.17
Co–Mo/AS1
Co–Mo/AB1
Co–Mo/AL1
Table 7. Dependence of the pseudoꢀfirstꢀorder rate constants of hydrodesulfurization on the nature of the catalyst for the
reactions of DBT, 4ꢀMDBT, and 4,6ꢀDMDBT
k
, h–1
Sample
DBT
4ꢀMDBT
4,6ꢀDMDBT
Co–Mo/A
13.3
14.0
13.0
14.2
7.3
5.9
6.7
6.0
6.3
3.9
5.8
1.6
2.4
3.2
2.8
3.1
2.0
3.3
0
Co–Mo/AS1
Co–Mo/AB1
Co–Mo/AL1
Co–Mo/AS5
Co–Mo/AB5
10.5
4.3
Co–Mo/AL5
rate of conversion was observed on Co–Mo/AB5 catꢀ ions. We found that an optimum concentration of the
alyst. In this case, the rate of conversion of this reacꢀ above sites, which is 0.8–0.9
mol/m2 (AS1 and AB5), is
4,6ꢀDMDBT. A
µ
tion mixture component depends on the concentration necessary for reaching the greatest value of
k
of weak LASs (absorption band at 2165–2175 cm–1), decrease and, especially, an increase in the concentraꢀ
+
formed by coordinatively unsaturated Мn modifying tion of weak LASs leads to a decrease in the values of
Table 8. Comparison between the rate constants of conversion of DBT, 4ꢀMDBT, and 4,6ꢀDMDBT on the test catalysts
and the concentrations of LASs and BSs on the surface of corresponding supports
LASs (absorption band
kDBT
,
k
4ꢀMDBT
,
k4,6ꢀDMDBT,
Σ
LASs,
Σ
BSs,
Sample
at 2165–2175 cm–1),
mol/m2
μ
mol/m2
h–1
h–1
h–1
μ
μ
mol/m2
Co–Mo/AL5
Co–Mo/AS5
Co–Mo/AB5
Co–Mo/AB1
Co–Mo/A
4.3
7.3
1.6
3.9
5.8
6.0
5.9
6.7
6.3
3.9
2.8
2.0
1.7
2.0
2.6
2.0
3.1
2.6
2.5
2.4
1.8
2.1
2.1
0
3.12
1.61
0.79
0.40
0
2.0
3.3
2.8
2.4
3.2
3.1
10.5
13.0
13.3
14.0
14.2
Co–Mo/AS1
Co–Mo/AL1
0.91
0.56
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EFFECT OF THE NATURE OF THE ADDITIVES OF METAL CATIONS
593
k4,6ꢀDMDBT; in particular, the conversion of 4,6ꢀ La) in 1 and 5 mol % concentrations showed that the
DMDBT does not occur at a concentration of these nature and concentration of M is responsible for both
sites of 3.12
µ
mol/m2 (AL5).
the structural, textural, and acid–base properties of
the support and the surface properties and degree of
dispersion of Co–Mo–S sulfide packets and hence for
activity in the conversion of DBT, 4ꢀMDBT, and 4,6ꢀ
DMDBT.
Consequently, for the effective transformation of
DBT and 4ꢀMDBT, the surface concentration of both
LASs and BSs of the support should be minimal,
whereas an optimum concentration of weak LASs
(absorption band at 2165–2175 cm–1) is required for
the conversion of 4,6ꢀDMDBT. It is likely that the
observed behaviors were caused by the fact that, at a
minimum surface acidity and basicity, conditions that
minimize the interaction of a Moꢀcontaining compoꢀ
nent with the support are created to facilitate the more
complete interaction between Coꢀ and Moꢀcontaining
components and the formation of less dispersed particles.
In turn, it is likely that the presence of a highly dispersed
Moꢀcontaining compound is required for the effective
transformation of 4,6ꢀDMDBT, which is ensured by its
partial interaction with the coordinatively unsaturated
Мn+ ions of the support.
ACKNOWLEDGMENTS
We are grateful to our colleagues from the Boreskov
Institute of Catalysis, Siberian Branch, Russian Acadꢀ
emy of Sciences: A.A. Budneva for her assistance in perꢀ
forming IRꢀspectroscopic experiments, D.A. Zyuzin for
performing XRD analysis, and T.Ya. Efimenko for
measuring the texture characteristics of the samples.
REFERENCES
1. Song, C., Catal. Today, 2003, vol. 86, p. 211.
2. Babich, I.V. and Moulijn, J.A., Fuel, 2003, vol. 82,
It was noted above that the rate constants of conversion
kDBT and k4ꢀMDBT increase in the order Co–Mo/AB1 <
Co–Mo/A < Co–Mo/AS1 < Co–Mo/AL1, whereas
k4,6ꢀDMDBT increase in the other order Co–Mo/A <
Co–Mo/AB1 < Co–Mo/AL1 < Co–Mo/AS1. This
means that the effective transformation of DBT and 4ꢀ
MDBT was observed on Co–Mo/AL1, whose Co–
Mo–S sulfide packets are characterized by the greatest
sizes: along with singleꢀlayer packets with a diameter
of 5–7 nm, fiveꢀlayer packets to 20 nm in diameter
were also present. Catalyst Co–Mo/AS1, which is the
most active in the conversion of 4,6ꢀDMDBT, conꢀ
tains the most dispersed Co–Mo–S sulfide packets,
whose size can be as small as 2 nm. It is necessary to
note that the [Co] : [Mo] surface atomic ratio and the
fraction of molybdenum sulfide species decrease in the
p. 607.
3. Topsøe, H., Clausen, B.S., and Massoth, F.E.,
Hydrotreating Catalysis: Science and Technology, Catalꢀ
ysis Science and Technology, vol. 11, Berlin: Springer,
1996.
4. Breysse, M., Afanasiev, P., Geantet, C., and Vrinat, M.,
Catal. Today, 2003, vol. 86, p. 5.
5. Pratt, K.C., Sanders, J.V., and Christov, V., J. Catal.
,
1990, vol. 124, p. 416.
6. Iwamoto, R. and Grimblot, J., J. Catal., 1997, vol. 17,
p. 252.
7. Ramirez, J., Fuentes, S., Diaz, J.R., Fuentes, G., Vriꢀ
nat, M., Breysse, M., and Lacroix, M., Appl. Catal., A
1989, vol. 52, p. 211.
8. Okamoto, Y., Catal. Today, 1997, vol. 39, p. 45.
9. Rawat, K.S., Rana, M.S., and Murali Dhar, G., Stud.
Surf. Sci. Catal., 2001, vol. 135, p. 301.
,
order Co–Mo/A > Co–Mo/AB1
≈
Co–Mo/AL1 >
10. Andonova, S., Vladov, Ch., Pawelec, B., Shtereva, I.,
Tyuliev, G., Damyanova, S., and Petrov, L., Appl.
Catal., A, 2007, vol. 328, p. 201.
11. Caloch, B., Mohan S. Rana, and Ancheyta, J., Catal.
Today, 2004, vol. 98, p. 91.
12. GuevaraꢀLara, A., CruzꢀPérez Alida, E., Contrerasꢀ
Valdez, Z., MogicaꢀBetancourt, J., AlvarezꢀHernanꢀ
dez, A., and Vrinat, M., Catal. Today, 2010, vol. 149,
p. 288.
Co–Mo/AS1; that is, the smallest degree of molybdeꢀ
num reduction was observed in Co–Mo/AS1. Howꢀ
ever, for this catalyst, the degree of sulfidation, which
is characterized by the [Sd] : [Mo4+] ratio, is somewhat
higher than that for other catalysts (Table 6), and it is
the greatest for k4,6ꢀDMDBT (Table 7). The regularities
obtained are consistent with the results of Andonova
et al. [10], who observed a higher catalytic activity on
catalyst Ni–Mo/Al–Ca, where the degree of molybꢀ
denum reduction to Mo4+ is lower and the degree of
sulfidation (the S : Mo4+ ratio) is higher than those in a
sample on the unmodified support. Thus, for the effective
conversion of DBT, 4ꢀMDBT, and 4,6ꢀDMDBT, differꢀ
ent degree of dispersion of Co–Mo–S sulfide packets
and specific [Co] : [Mo] and [S] : [Mo4+] surface
atomic ratios are necessary.
13. Klicpera, T. and Zdrazil, M., J. Catal., 2002, vol. 206,
p. 314.
14. Zdrazil, M., Catal. Today, 2003, vol. 86, p. 151.
15. Wu, L., Jiao, D., Wang, J., Chen, L., and Cao, F.,
Catal. Commun., 2009, vol. 11, p. 302.
16. Paukshtis, E.A., Infrakrasnaya spektroskopiya v geteroꢀ
gennom kislotnoꢀosnovnom katalize (Infrared Spectrosꢀ
copy in Heterogeneous Acid–Base Catalysis), Novosiꢀ
birsk: Nauka, 1992.
Thus, the above study of Co–Mo catalysts supꢀ
ported on aluminum oxide modified with the cations
of alkalineꢀearth and rareꢀearth elements (Sr, Ba, and
17. Scofield, J.H., J. Electron Spectrosc. Relat. Phenom.
,
1976, vol. 8, p. 129.
KINETICS AND CATALYSIS Vol. 52
No. 4
2011

594
KORNEEVA et al.
18. Tanaka, K. and Ozaki, A., J. Catal., 1967, vol. 8, p. 1.
Kuznetsov, P.A., and Polukhina, I.A., Appl. Catal., A,
2009, vol. 357, p. 193.
19. Okamoto, Y., Nakano, H., Shimokawa, T., Imanaka, T.,
26. Rousseau, S., Loridant, S., Delichere, P., Boreave, A.,
Deloume, J.P., and Vernoux, P., Appl. Catal., B, 2009,
vol. 88, p. 438.
27. Sosulnikov, M.I. and Teterin, Yu.A., J. Electron Specꢀ
trosc. Relat. Phenom., 1992, vol. 59, p. 111.
28. Dupin, J.ꢀC., Gonbeau, D., Vinatier, P., and
Levasseur, A., Phys. Chem. Chem. Phys., 2000, vol. 2,
p. 1319.
29. Van der Heide, P.A.W., J. Electron Spectrosc. Relat.
Phenom., 2006, vol. 151, p. 79.
and Teranishi, S., J. Catal., 1977, vol. 50, p. 447.
20. Brinen, J.S. and Armstrong, W.D., J. Catal., 1978,
vol. 54, p. 57.
21. De Jong, A.M., de Beer, V.H.J., van Veen, J.A.R., and
Niemantsverdriet, J.W., J. Phys. Chem., 1996, vol. 100,
p. 17722.
22. Sanders, A.F.H., de Jong, A.M., de Beer, V.H.J., van
Veen, J.A.R., and Niemantsverdriet, J.W., Appl. Surf.
Sci., 1999, vols. 144–145, p. 380.
23. Saih, Y. and Segawa, K., Appl. Catal., A, 2009, vol. 353,
30. Hueso, J.L., Caballero, A., Ocaña, M., and Gonzálezꢀ
p. 258.
Elipe, A.R., J. Catal., 2008, vol. 257, p. 334.
24. Rida, A., Benabbas, F., Bouremmad, F., Peña, M.A.,
and MartínezꢀArias, A., Catal. Commun., 2006, vol. 7,
p. 963.
31. Zhuang, S.ꢀX., Yamazaki, M., Omata, K.,
Takahashi, Y., and Yamada, M., Appl. Catal., B, 2001,
vol. 31, p. 133.
25. Bukhtiyarova, M.V., Ivanova, A.S., Plyasova, L.M., Litꢀ 32. RodríguezꢀCastellón, E., JiménezꢀLópez, A., and Eliꢀ
vak, G.S., Rogov, V.A., Kaichev, V.V., Slavinskaya, E.M., cheꢀQuesada, D., Fuel, 2008, vol. 87, p. 1195.
KINETICS AND CATALYSIS Vol. 52
No. 4
2011