Preparation of Ni - W aromatic hydrocarbon hydrogenation catalysts by breaking reverse emulsions or suspensions of a precursor in hydrocarbon feedstock

Article abstract of DOI:10.1134/S0965544116020134

Reverse emulsions (hydrocarbon feedstock)/(aqueous precursor solution) for synthesizing aromatic hydrocarbon hydrogenation catalysts have been prepared using the water-soluble salts (NH₄)₂WS₄ and Ni(NO₃)₂·6 H₂O as precursors. It has been found that the optimum stabilizer for the emulsions is the nonionic surfactant SPAN-80. The resulting emulsions exhibit low catalytic activity in the hydrogenation of aromatic hydrocarbons; it has been shown that the activity of the systems in hydrodearomatization reactions is adversely affected by the presence of water. A procedure for preparing suspensions of solid precursor particles in a hydrocarbon feedstock by the removal of water from the resulting reverse emulsions has been developed. The catalytic activity of the resulting suspensions in the hydrogenation of aromatic hydrocarbons has been studied using naphthalene, 1-methylnaphthalene, and 2-methylnaphthalene as examples. It has been shown that the catalytic activity of the suspensions is higher than that of the reverse emulsions of the same composition. It has been found that the feedstock should be subjected to additional sulfurization with elemental sulfur for further sulfiding the surface of the nickel - tungsten catalyst. The W: Ni molar ratio of 1: 1 has been found to be optimum.

Full text of DOI:10.1134/S0965544116020134

ISSN 0965ꢀ5441, Petroleum Chemistry, 2016, Vol. 56, No. 2, pp. 131–137. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © I.A. Sizova, S.I. Serdyukov, A.L. Maksimov, 2016, published in Neftekhimiya, 2016, Vol. 56, No. 2, pp. 150–157.
Preparation of Ni–W Aromatic Hydrocarbon Hydrogenation
Catalysts by Breaking Reverse Emulsions or Suspensions
of a Precursor in Hydrocarbon Feedstock
a,
a, b
a, b
I. A. Sizova *, S. I. Serdyukov , and A. L. Maksimov
a
Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow, Russia
b
Faculty of Chemistry, Moscow State University, Moscow, Russia
*
eꢀmail: isizova@ips.ac.ru
Received October 7, 2015
Abstract—Reverse emulsions (hydrocarbon feedstock)/(aqueous precursor solution) for synthesizing aroꢀ
matic hydrocarbon hydrogenation catalysts have been prepared using the waterꢀsoluble salts (NH ) WS and
4
2
4
Ni(NO ) · 6 H O as precursors. It has been found that the optimum stabilizer for the emulsions is the nonꢀ
3
2
2
ionic surfactant SPANꢀ80. The resulting emulsions exhibit low catalytic activity in the hydrogenation of aroꢀ
matic hydrocarbons; it has been shown that the activity of the systems in hydrodearomatization reactions is
adversely affected by the presence of water. A procedure for preparing suspensions of solid precursor particles
in a hydrocarbon feedstock by the removal of water from the resulting reverse emulsions has been developed.
The catalytic activity of the resulting suspensions in the hydrogenation of aromatic hydrocarbons has been
studied using naphthalene, 1ꢀmethylnaphthalene, and 2ꢀmethylnaphthalene as examples. It has been shown
that the catalytic activity of the suspensions is higher than that of the reverse emulsions of the same compoꢀ
sition. It has been found that the feedstock should be subjected to additional sulfurization with elemental sulꢀ
fur for further sulfiding the surface of the nickel–tungsten catalyst. The W : Ni molar ratio of 1 : 1 has been
found to be optimum.
Keywords: reverse emulsions, nickel–tungsten sulfide catalyst, hydrogenation of aromatic hydrocarbons
DOI: 10.1134/S0965544116020134
Owing to exceptional stability to the action of catꢀ content in the final sulfide catalyst and contributes to
alyst poisons, transition metal sulfides [1]—mostly the formation of stable fine nanometerꢀsized particles.
tungsten and molybdenum sulfides promoted with
cobalt or nickel—are commonly used in hydrotreatꢀ
ment reactions involving feedstock purification for the
removal of heteroatomic (sulfur, nitrogen, and oxyꢀ
gen) impurities in a hydrogen atmosphere, the hydroꢀ
gen saturation of unsaturated hydrocarbons, and the
Most commonly, the synthesis of nanoparticles in
situ in the matrix of a heavy feedstock is conducted
using the method of the preparation of nanocatalysts
from reverse emulsions [6]. The technique of preparaꢀ
tion of a catalyst from a reverse emulsion involves the
mixing of the oil phase, an aqueous solution of the preꢀ
cursor, and a stabilizing agent—surfactant—and subꢀ
sequent breaking the resulting emulsion under cataꢀ
lytic experiment conditions. The method of preparaꢀ
tion of nanocatalysts using reverse microemulsions has
been effectively applied for the hydrotreating and
hydroconversion of heavy hydrocarbon feedstocks [7,
hydrogenation of aromatic compounds [2]. The ꢀ
γ
Al O3ꢀsupported Co(Ni)–Mo(W) sulfide hydrotreatꢀ
2
ing catalysts developed in the 1980s no longer meet the
presentꢀday requirements. Tightening of environmenꢀ
tal and economic requirements for the quality of
motor fuels has led to the design of new highꢀperforꢀ
mance catalysts and the restructuring of oil refineries
because the required performance cannot be achieved
with the use of customary petroleum refining flow
charts and conventional catalysts [3].
8
]; however, data on the use of these systems for the
hydrogenation of aromatic hydrocarbons are scarce.
In this study, a method for the in situ preparation of
a nickel–tungsten sulfide aromatic hydrocarbon
High activity of bulk sulfide catalysts in hydrotreatꢀ hydrogenation catalyst by breaking reverse emulsions
ment reactions has attracted the attention of researchꢀ (hydrocarbon feedstock)/(precursor solution in water)
ers [4]; it is significantly higher than the activity of or suspensions of solid precursor particles in a hydroꢀ
conventional supported hydrotreating catalysts [5]. carbon feedstock has been proposed. The catalytic
Unsupported sulfide catalysts are frequently prepared properties in the hydrogenation reaction have been
ex situ, whereas the in situ decomposition of precurꢀ studied using the example of model systems (naphthaꢀ
sors in the reaction medium provides a high sulfur lene and methylnaphthalenes).
131

132
SIZOVA et al.
Aqueous solution of (NH ) WS
Aqueous solution of Ni(NO3)2
4
2
4
hydrocarbon phase
hydrocarbon phase
Ultrasonic dispersing
Reverse emulsion of (NH ) WS
Ultrasonic dispersing
Reverse emulsion of Ni(NO3)2
4
2
4
Mixed reverse emulsion of
NH ) WS и Ni(NO )
(
4
2
4
3 2
5
0°С, 12 mmHg
Suspension of Ni /(NH ) WS
x
4 2
4
Fig. 1. Schematic preparation of surfactantꢀstabilized suspensions of Ni /(NH ) WS particles in a hydrocarbon feedstock.
x
4 2
4
EXPERIMENTAL
Synthesis Procedures
sure for 2 min. After that, the resulting emulsions were
mixed via slowly dripping the reverse emulsion based
on an aqueous solution of Ni(NO3)2 to the reverse
emulsion based on an aqueous solution of (NH ) WS
under vigorous stirring at room temperature.
The total water content in all the prepared reverse
Ammonium thiotungstate (NH ) WS was prepared
4 2
4
4
2
4
as described in [9]: 10 g of Na WO
·
2H O was disꢀ
2
4
2
solved in 40 mL of water; the solution was admixed
with 15 mL of hydrochloric acid; and the mixture was emulsions was 3.5 wt %. The SPANꢀ80 content was
stirred for 10 min until the formation of a yellow preꢀ 0.5–5.0 wt %.
cipitate of H WO4. The precipitate was filtered off,
twice washed with water, and evaporated in a furnace
2
Surfactantꢀstabilized suspensions of solid
Ni /(NH ) WS particles in a hydrocarbon feedstock
x
4 2
4
by one third of mass at a temperature of
Sixty milliliters of concentrated aqueous ammonia
was added to the H WO . Hydrogen sulfide was passed
T = 95°C.
were prepared by distilling water from the mixed surꢀ
factantꢀstabilized reverse emulsions based on aqueous
solutions of (NH ) WS and Ni(NO3)2 in a hydrocarꢀ
2
4
4
2
4
through the resulting solution at a temperature of
for 30 min; after that, the formed green precipiꢀ
bon feedstock (Fig. 1). Water was removed using a
rotary evaporator at a temperature of 50°С and a presꢀ
sure of 12 mm Hg for 10 min.
60°С
tate was filtered off. Hydrogen sulfide was passed
through the resulting bright yellow solution at a temꢀ
perature of 60
resulting orange precipitate of (NH ) WS was filtered
off and washed with isopropanol and diethyl ether.
°С for 8 h. The mixture was cooled; the
Catalyst Preparation Procedure by Breaking Reverse
Emulsions and Suspensions of the Precursor
4
2
4
Reverse emulsions of the precursor were prepared
Nickel–tungsten sulfide catalysts were prepared by
on the basis of aqueous solutions of (NH ) WS and in situ breaking reverse emulsions or suspensions of
4
2
4
Ni(NO3)2 6H O in a hydrocarbon feedstock and staꢀ precursors in hydrocarbon feedstock directly during
⋅
2
bilized with a surfactant (nonionic oilꢀsoluble surfacꢀ the catalytic experiment. The catalyst was formed durꢀ
tant sorbitan oleate SPANꢀ80).
ing the hydrogenation of aromatic compounds at a
temperature of 350°С
During the preparation of the precursor, Ni(NO
WS to form a (NH Ni WS
on an aqueous solution of (NH ) WS was prepared. To ammonium–nickel thiotungstate complex. The
.
The reverse emulsions based on aqueous solutions
of (NH ) WS and Ni(NO3)2
⋅
6H O were prepared in
)
3 2
4
4
2
4
2
three stages. At the first stage, a reverse emulsion based reacts with (NH
)
2
)
4
4
4
2
х
4
2
4
this end, an aqueous solution of (NH ) WS was added resulting complex undergoes singleꢀstep decomposiꢀ
4
2
4
to a surfactant solution in a hydrocarbon feedstock; tion to form Ni/WS , sulfide particles exhibiting activꢀ
2
the resulting mixture was dispersed using a LUZDꢀ1.5 ity in the hydrogenation of aromatic compounds.
laboratory ultrasonic disperser at room temperature
and atmospheric pressure for 2 min. At the second
stage, a reverse emulsion based on an aqueous solution
Precursor and Catalyst Investigation Procedures
of Ni(NO3)2 was prepared. To this end, an aqueous
The tungsten content in the prepared (NH ) WS
4 2 4
solution of Ni(NO3)2 was added to a surfactant soluꢀ was determined by atomic absorption spectroscopy
tion in a hydrocarbon feedstock; the resulting mixture using an AAnalyst 400 instrument. Analyses for C, H,
was dispersed using a LUZDꢀ1.5 laboratory ultrasonic N, and S were conducted using a CarboErba CHNSꢀ
disperser at room temperature and atmospheric presꢀ O EA 1108 elemental analyzer. The average diameter
PETROLEUM CHEMISTRY Vol. 56
No. 2
2016

PREPARATION OF Ni–W AROMATIC HYDROCARBON HYDROGENATION CATALYSTS
133
of the agglomerates of Ni/(NH ) WS precursor partiꢀ lipophilic balance of 4.3 [10]; therefore, it exhibits the
4
2
4
cles in the prepared emulsions and suspensions was ability to form and stabilize reverse emulsions.
determined by dynamic light scattering using a Malvꢀ
ern Zetasizer Nano ZS instrument.
To determine the optimum surfactant content in
the hydrocarbon feedstock by dynamic light scatterꢀ
ing, the average diameter of the aqueous precursor
solution droplets in the prepared reverse emulsions
The structure and morphology of the in situ synꢀ
thesized catalyst samples were examined using a Jeol
JEMꢀ2100 analytical electron microscope composed
of a base transmission electron microscope (TEM) for
recording electron microscopic images and electron
diffraction patterns, a computer control system with
an integrated scanning TEM image observation
device, and an energy dispersive Xꢀray spectrometer
and the agglomerates of the solid Ni /(NH ) WS preꢀ
x
4 2
4
cursor particles in the suspensions was measured
Fig. 2). The hydrocarbon medium was ꢀhexadeꢀ
cane.
(
n
An increase in the surfactant concentration leads to
a decrease in the size of water droplets in the reverse
emulsions and thus affects the size of the solid particles
in the resulting suspensions. With an increase in the
surfactant content, the diameter of the solid precursor
particles decreases; however, in all the cases, the averꢀ
age diameter of the aqueous precursor solution dropꢀ
lets is slightly lower than the diameter of the agglomꢀ
erates of solid precursor particles in suspensions of the
same composition. At an optimum SPANꢀ80 concenꢀ
tration (2.5 wt %), an increase in the surfactant conꢀ
centration does not lead to an improvement of the staꢀ
bility of the emulsion and the formation of smaller
droplets.
(
JEDꢀ2300). The phase composition of the resulting
particles was studied according to electron diffraction
patterns (a JEMꢀ2100 TEM).
Xꢀray photoelectron spectroscopy (XPS) studies of
the samples were conducted on a Physical Electronics
PHIꢀ5500 ESCA XPS instrument. Photoemission was
excited using 300ꢀW nonmonochromatized Al
K
α
radiation ( = 1486.6 eV). The powders were pressed
h
ν
in an indium plate. The diameter of the analyzed area
was 1.1 mm. Photoelectron peaks were calibrated
against the carbon C 1s line with a binding energy of
2
84.9 eV. The spectra were deconvoluted by the nonꢀ
Reverse emulsions and suspensions containing
wt % SPANꢀ80 were selected for the catalytic experꢀ
linear leastꢀsquare method using the Gaussian–
Lorentzian function.
5
iments to provide a high stability of the resulting colꢀ
loidal systems. At this concentration of SPANꢀ80, the
average diameter of the droplets in the reverse emulꢀ
sions is 385 nm, while the average diameter of the
agglomerates of the solid precursor particles is 473 nm.
The activity of the catalysts prepared by breaking
emulsions and suspensions of a waterꢀsoluble precurꢀ
sor in a hydrocarbon feedstock can be affected by varꢀ
ious factors, such as the nature and concentration of
the surfactant in the hydrocarbon feedstock. To select
an optimum composition, the activity of catalysts synꢀ
thesized in situ by the breaking reverse emulsions and
suspensions of the precursor in the hydrogenation of
aromatic hydrocarbons was studied using the example
of model systems composed of 10% solutions of naphꢀ
thalene, 1ꢀmethylnaphthalene, and 2ꢀmethylnaphꢀ
Catalytic Testing Procedure
Catalytic hydrogenation tests were conducted in a
steel autoclave in a hydrogen atmosphere under a high
pressure and vigorous stirring of the reaction mixture.
Two milliliters of the reverse emulsion or the suspenꢀ
sion was placed into the glass cartridge of the autoꢀ
clave. After that, the autoclave was filled with hydroꢀ
gen to a pressure of 50 atm and held at a temperature
of 350°С for 10 h; the hydrogen/substrate molar ratio
was 60 mol/mol. The hydrogenation products
were analyzed on a 4000 M Kristallyuks chromatoꢀ
graph equipped with a flame ionization detector and a
SPBꢀ1 capillary column coated with the polydimethꢀ
ylsiloxane stationary liquid phase (dimensions, 30 m
.25 mm; carrier gas, helium; split ratio, 1 : 90). Chroꢀ
×
thalene in
W–S–Ni particles prepared by breaking an emulsion
containing 3.5 wt % of water) or a suspension preꢀ
nꢀhexadecane. Primarily, the activities of
0
matograms were processed using the NetChromWin
software program.
(
pared from an emulsion of the same composition by
removing water on a rotary evaporator at a temperaꢀ
ture of 50°С and a pressure of 12 mm Hg were comꢀ
pared (Fig 3); a W : Ni molar ratio of 1 : 1 was selected
for the studies.
RESULTS AND DISCUSSION
The catalyst prepared by breaking the reverse
emulsions of an aqueous precursor solution in a
Catalytic Properties
The selection of surfactants for the preparation of hydrocarbon feedstock did not exhibit high activity in
an emulsion with required characteristics was based on the hydrogenation of all the studied substrates (Fig. 3).
the hydrophilic–lipophilic balance value. Since 10% It has been previously shown [11] that the activity of
solutions of aromatic compounds in nꢀhexadecane nickel–tungsten sulfide catalysts in the hydrogenation
were used as a hydrocarbon phase, sorbitan of aromatic hydrocarbons is adversely affected by
monooleate SPANꢀ80 was selected as an oilꢀsoluble water. The removal of water from the emulsions proꢀ
nonionic surfactant; this substance has a hydrophilic– vided the formation of suspensions of solid precursor
PETROLEUM CHEMISTRY Vol. 56
No. 2
2016

134
SIZOVA et al.
2
2
1
1
500
000
500
000
60
emulsion
suspension
emulsion
suspension
4
0
0
0
2
5
00
1
2
3
0
Fig. 3. Comparison of the conversion of aromatic hydroꢀ
carbons in the cases of using a suspension or a reverse
emulsion of precursor particles in a hydrocarbon feedꢀ
0.5
1.0
2.5
5.0
SPANꢀ80 concentration, %
stock: (
2ꢀmethylnaphthalene. Reaction conditions:
H2 = 5.0 MPa; = 10 h; substrate : tungsten = 105.3 :
1 mol/mol; W : Ni = 1 : 1 mol/mol; and SPANꢀ80 concenꢀ
tration, 5 wt %.
1
) naphthalene, (
2
) 1ꢀmethylnaphthalene, and (
3)
Fig. 2. Dependence of the average diameter of the agglomꢀ
T
= 350°C;
erates of Ni /(NH ) WS precursor particles in the reverse
P
t
x
4 2
4
emulsions and suspensions on the SPANꢀ80 concentraꢀ
tion.
particles in a hydrocarbon feedstock, which exhibited the naphthalene conversion from 87 to 6%. The negaꢀ
higher activity in the hydrogenation of aromatic tive effect of an increase in the surfactant concentraꢀ
hydrocarbons. Thus, in the case of the catalyst in situ tion can be eliminated by the introduction of sulfurꢀ
synthesized by breaking a suspension of precursor parꢀ containing compounds into the feedstock for sulfiding
ticles, the conversion of naphthalene and 1ꢀmethylꢀ the catalyst surface. Additional sulfurization of the
naphthalene increased more than 35ꢀfold and feedstock was provided by the addition of 2.5 wt % of
achieved 36 and 48%, respectively; the conversion of elemental sulfur. A 10% solution of naphthalene in
2
ꢀmethylnaphthalene also increased and achieved benzene was used as a model feedstock. The naphthaꢀ
4
2% (Fig. 3). These data confirm the previous concluꢀ lene conversion significantly increases with the addiꢀ
sions about the negative effect of water on the activity tional sulfurization of the feedstock in the case of using
of nickel–tungsten sulfide catalysts; the presence of both reverse emulsions of an aqueous precursor soluꢀ
water in the hydrocarbon feedstock leads to a decrease tion and suspensions of solid precursor particles in a
in the degree of promotion of the WS2 phase with Ni hydrocarbon feedstock. In the case of reverse emulꢀ
atoms, to a decrease in the stability of the Ni–W–S sions, the catalytic activity is lower and the naphthaꢀ
phase, and the formation of a catalyst with a less sulꢀ lene conversion does not exceed 45%. In the case of
fidized surface owing to the substitution of oxygen the catalyst synthesized by breaking a suspension of
atoms for the sulfur atoms in the composition of the solid precursor particles in a hydrocarbon feedstock,
thioꢀprecursor.
the catalytic activity significantly increases with the
additional sulfurization of the feedstock. The naphꢀ
thalene conversion achieves 98%; the main reaction
product is tetralin; the amount of decalins formed in
the system is on the order of 20% (cisꢀ and transꢀstereꢀ
oisomers); the ratio between cisꢀ and transꢀdecalins is
The substitution of oxygen atoms for sulfur atoms
can also occur during the breaking a precursor suspenꢀ
sion at high surfactant concentrations in the absence
of additional sulfurꢀcontaining compounds. Figure 4
shows the dependence of the conversion of aromatic
hydrocarbons on the SPANꢀ80 surfactant concentraꢀ
tion in the case of preparation of a catalyst by in situ
breaking suspensions of solid precursor particles in the
absence of a sulfiding agent.
1
: 2.8.
The promoting effect of Ni and Co atoms directly
depends on the amount of the promoter added to
molybdenum or tungsten sulfides. An increase in the
An increase in the surfactant concentration leads to amount of the promoter atoms above an optimum
a decrease in the catalytic activity of the studied sysꢀ value results in a decrease in the catalytic activity in
tems; the conversion of the all the used substrates hydrotreatment reactions owing to the formation of an
decreases because an increase in the surfactant conꢀ individual bulk NiS phase which blocks the promoted
centration from 0.5 to 5.0 wt % leads to a decrease in active sites on the catalyst surface [12, 13]. In the conꢀ
PETROLEUM CHEMISTRY Vol. 56
No. 2
2016

PREPARATION OF Ni–W AROMATIC HYDROCARBON HYDROGENATION CATALYSTS
135
1
00
100
80
60
40
20
0
naphthalene
1
2
ꢀmethylnaphthalene
ꢀmethylnaphthalene
8
6
4
2
0
0
0
0
0
0.5
2.5
SPANꢀ80 concentration, %
5.0
no Ni 2 : 1 1.5 : 1 1 : 1 1 : 1.5 1 : 2 1 : 3 1 : 4
W : Ni molar ratio, mol/mol
Fig. 4. Dependence of the conversion of aromatic hydroꢀ
carbons on the surfactant concentration. Reaction condiꢀ
Fig. 5. Dependence of the naphthalene conversion on the
W : Ni molar ratio. Reaction conditions: = 350°C;
PH2 = 5.0 MPa; t = 10 h; substrate : tungsten = 105.3 :
tions:
T
= 350°C; PH2 = 5.0 MPa;
t
= 10 h; substrate :
T
tungsten = 105.3 : 1 mol/mol; W : Ni = 1 : 1 mol/mol; no
sulfiding agent additive.
1 mol/mol; and SPANꢀ80 concentration, 5 wt %.
text of the above, it was of interest to study the effect of
The structure and morphology of the in situ synꢀ
the W : Ni ratio on the catalytic activity of the resulting thesized Ni–W–S particles was studied by HR TEM.
materials. Figure 5 shows the dependence of the naphꢀ Figure 6a shows typical TEM images of the prepared
thalene conversion on the tungsten/nickel molar ratio catalysts. The TEM images show a characteristic layꢀ
in a suspension of solid precursor particles in a hydroꢀ ered structure of the resulting phase, which is comꢀ
carbon feedstock. The optimum ratio was determined posed of WS2 nanosheets united in agglomerates (500–
with the additional sulfurization of the feedstock 1000 nm). In addition, the micrographs show thin
with elemental sulfur at a SPANꢀ80 concentration of lines (an interplanar spacing of 2.85 Å), which indicate
5
wt %.
the presence of a NiS nickel sulfide phase.
It was shown that the catalyst synthesized by breakꢀ
The phase composition of the synthesized Ni–W–S
ing a suspension containing no nickel exhibits low catꢀ particles was estimated from electron diffraction patꢀ
alytic activity; the naphthalene conversion does not terns (Fig. 6b). Analysis of the electron diffraction patꢀ
exceed 10%. The addition of nickel as a promoter terns showed that the recorded reflections correspond
leads to a significant increase in the catalytic activity of to interplanar spacings characteristic of the (002),
the studied systems; the optimum W : Ni molar ratio is (100), (103), and (110) planes of the hexagonal phase
1
: 1. In this case, the naphthalene conversion is 98%; of tungsten disulfide. The high intensity of the reflecꢀ
the decalin selectivity achieves 18%; and the ratio tion characteristic of the (002) plane (
2 = 14°) indiꢀ
θ
between cisꢀ and transꢀdecalins is 1 : 2.8. A further cates the vertical ordering of the WS2 crystallites,
increase in the nickel nitrate concentration leads to a which assumes a multilayer packaging of single WS2
decrease in the naphthalene conversion; at a molar layers along the
c
axis [14]. The recorded Xꢀray diffracꢀ
ratio of W : Ni = 1 : 4, the naphthalene conversion tion pattern exhibits a lowꢀintensity reflection characꢀ
does not exceed 35%.
teristic of a nickel sulfide phase (an interplanar spacing
of 1.86 Å). The low intensity of this reflection suggests
a uniform distribution of nickel in the active phase and
the formation of a Ni–W–S phase [15].
Characterization of the Catalyst Synthesized
in situ in Hydrocarbon Feedstock by Breaking
NH ) Ni WS Precursor Suspension
The distribution of the sulfide particles with respect
to the particle length (Fig. 6c) and the number of layꢀ
(
4
2
x
4
The catalyst prepared by in situ breaking SPANꢀ ers in the multilayer agglomerates (Fig. 6d) was deterꢀ
0ꢀstabilized suspensions of solid precursor particles mined from the statistical estimation of more than 300
8
in a hydrocarbon feedstock subjected to additional particles of the active component in different TEM
sulfurization with 2.5 wt % of elemental sulfur (the images. The average length of the active component is
SPANꢀ80 concentration in the hydrocarbon feedstock 6.1 nm; the average number of layers is 1.9. These data
of 5 wt %) exhibited the highest catalytic activity in the suggest that the use of a surfactant in the preparation
hydrogenation of aromatic hydrocarbons. The W : Ni of a Ni–W–S catalyst leads to the formation of partiꢀ
molar ratio was 1 : 1.
cles with a small number of layers in the multilayer
PETROLEUM CHEMISTRY Vol. 56
No. 2
2016

136
SIZOVA et al.
002
(b)
*
– NiS
1
00
1
03
*
110
30
60
2θ, deg
90
120
5
nm
(а)
2
5
0
5
0
5
0
(c)
40
(d)
35
30
25
20
15
10
5
0
2
1
1
1
2
3
4
5 6 7 8 9
Number of WS2 sheets
Particle length, Å
Fig. 6. (a) Micrograph of the synthesized Ni–W–S catalyst, (b) electron diffraction pattern, and distribution of sulfide particles
with respect to (c) particle length and (d) the number of layers in multilayer agglomerates.
agglomerate, yet with a broad distribution with respect
to the length of the layers.
The studied catalyst contains tungsten in three
forms: sulfide, oxysulfide, and oxide. The major porꢀ
The elemental composition of the synthesized catꢀ tion of tungsten present on the surface is in a sulfide
alyst, which was determined by XPS (C, 40.9%; W, environment (56%); however, a significant amount of
6
.1%; Ni, 5.6%; S, 19.7%; O, 25.6%; and N, 2.1%) tungsten is in an oxygen environment. The nickel
indicates the presence of a carbide phase on the cataꢀ present on the catalyst surface is also in both a sulfide
lyst surface, despite the absence of carbon atoms in the and oxygen environment. Almost a third of the nickel
Ni/(NH ) WS precursor. Similar results have been is in the sulfide form; 15% of nickel is included in the
≈
4
2
4
shown in some studies on the in situ synthesis of Co– composition of the Ni–W–S complex sulfide, where
Mo and Ni–Mo–W catalysts by the decomposition of nickel atoms are surrounded by tungsten atoms.
Co/(NH ) MoS and Ni/(NH ) MoWS8 precursors
containing no carbon [16, 17].
The deconvolution of the S2
the sulfur is in three states: S , oxysulfide, and sulfate.
p
level has shown that
4
4
4
4 4
2
⎯
A higher content of oxygen atoms on the surface of The sulfur present on the catalyst surface is mostly in
the catalyst synthesized by breaking a suspension of the form of sulfide (42.9%). The amount of sulfur in
solid particles in a hydrocarbon feedstock can indicate the +6 oxidation state achieves 18.1%
an insufficient degree of sulfiding of the catalyst surꢀ
Thus, in this study, a Ni–W sulfide catalyst has
face owing to the substitution of oxygen atoms for the been first prepared by the in situ breaking reverse
sulfur atoms in the thioꢀprecursor during the dissoluꢀ emulsions of an aqueous precursor solution and susꢀ
tion of it in water and in contact with an oxygenꢀconꢀ pensions of solid (NH ) Ni WS precursor particles in
4
2
x
4
taining surfactant.
To determine the fraction of individual valence and catalytic experiment conditions have been
forms of the elements, deconvolution of the W4 selected. It has been shown that the catalytic activity of
Ni2 , and S2 levels was conducted. The weight ratios the resulting suspensions is higher than that of the
a hydrocarbon feedstock; an optimum composition
f,
p
p
of the resulting phases and the binding energies are reverse emulsions of the same composition. It has been
listed in the table. The binding energy values are conꢀ determined that the feedstock should be subjected to
sistent with the literature data [18, 19].
additional sulfurization with elemental sulfur for furꢀ
PETROLEUM CHEMISTRY Vol. 56
No. 2
2016

PREPARATION OF Ni–W AROMATIC HYDROCARBON HYDROGENATION CATALYSTS
137
XPS data for the W 4
f
, Ni 2
p
, and S 2
p
levels of the catalysts
Binding energy, eV
Element
Weight fraction, %
56.3
State
W4
f
4
4
4
4
4
4
f7/2
f5/2
f7/2
f5/2
f7/2
f5/2
32.3
WS2
34.3
33.5
16.0
27.7
27.0
15.5
57.5
WOxSy
WO3
NiS
35.3
36.1
38.0
Ni2
p
p
2p3/2
2p1/2
2p3/2
2p1/2
2p3/2
2p1/2
2p3/2
2p3/2
2p3/2
852.6
869.8
853.7
870.9
856.2
873.6
161.8
163.1
168.4
NiWS
NiO
S2–
Ni2
S2p
42.9
38.9
18.1
6–
(O S)
2
(SO4)2–
ther sulfiding the surface of the nickel–tungsten cataꢀ
lyst, the W : Ni molar ratio of 1 : 1 has been found to
be optimum. TEM studies have revealed that the Ni–
W–S catalyst particles are Niꢀpromoted WS2
nanosheets united in multilayer agglomerates. The
average number of layers in the multilayer packaging is
6. S. N. Khadzhiev, Kh. M. Kadiev, and M. Kh. Kadieva,
Pet. Chem. 54, 323 (2014).
7. I. Capek, Adv. Colloid Interface Sci. 110, 49 (2004).
8. P. Pereira, R. Marzin, L. Zacarias, et al., US Patent
No. 5 885 441 (1999).
9. W. McDonald, G. D. Friesen, L. D. Rosenhein, and
1
.9; the average length of the Ni–W–S particles is
W. E. Newton, Inorg. Chim. Acta 72, 205 (1983).
6
.1 nm. The resulting catalyst exhibits high activity in 10. M. M. Gacek and J. C. Berg, J. Colloid Interface Sci.
449, 192 (2015).
the selective hydrogenation of aromatic hydrocarbons,
as shown using the example of hydrogenation of naphꢀ 11. I. A. Sizova, S. I. Serdyukov, and A. L. Maksimov, Pet.
thalene and methylnaphthalenes.
Chem. 55, 468 (2015).
1
2. H. Topsoe, B. S. Clausen, and F. E. Massoth,
Hydrotreating Catalysis: Science and Technology
ACKNOWLEDGMENTS
(Springer, Berlin, 1996).
This work was supported by the Russian Science 13. P. Gajardo, A. Mathieux, P. Grange, and B. Delmon,
Appl. Catal., A
4. Y. G. Hur, M.ꢀS. Kim, D.ꢀW. Lee, et al., Fuel 137, 237
2014).
5. Z. Le, P. Afanasiev, D. Li, et al., Catal. Today 130, 24
(2008).
16. H. Nava, C. Ornelas, A. Aguilar, et al., Catal. Lett. 86
257 (2003).
sis, Structure, and Properties (Geo, Novosibirsk, 2007). 17. H. Nava, F. Pedraza, and G. Alonso, Catal. Lett. 99, 65
3, 347 (1982).
Foundation, agreement no. 15ꢀ13ꢀ00123.
1
1
(
REFERENCES
1
2
3
4
5
. R. R. Chianelli and M. Daage, Adv. Catal. 40, 177
1994).
. A. N. Startsev, Sulfide Hydrotreating Catalysts: Syntheꢀ
(
,
(2005).
. N. N. Tomina, A. A. Pimerzin, and I. K. Moiseev, Ross.
Khim. Zh. 52 (4), 41 (2008).
18. K. Tayeb, C. Lamonier, C. Lancelot, et al., Catal.
Today 150 (34) (2010).
19. D. Zuo, M. Vrinat, H. Nie, F. Mauge, et al., Catal.
. Y. Yi, X. Jin, L. Wang, et al., Catal. Today 175, 460
(2011).
Today 93 (2004).
. A. Olivas, T. A. Zepeda, I. Villalpando, and S. Fuentes,
Catal. Commun. , 1317 (2008).
9
Translated by M. Timoshinina
PETROLEUM CHEMISTRY Vol. 56
No. 2
2016