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nary good performance, a higher adsorption capacity, and better
desorption performance for toluene. Gao et al. [13] reported the
synthesis of mesoporous SBA-15 silicas with different morpholo-
gies. Using SBA-15 with sphere morphology as the support, the
Al-SBA-15 supported NiMo hydrodesulfurization (HDS) catalyst
exhibited the highest activities than the others (hexagonal prisms
and rods morphologies). They ascribed the influence to the superior
diffusion of the supports with sphere morphology and its better
dispersion of the active components. Liu et al. [14] synthesized
mesoporous silicas with various morphologies by modulating the
weight ratios of 2,2,4-trimethylpentane (TMP)/P123. The results
showed that mesoporous silica materials with hollow spheres mor-
phology could greatly accelerate the adsorption rate of the enzyme
during the adsorption process. Johansson et al. [15] found that par-
ticle morphology of mesoporous silica SBA-15 could be tuned by
varying the HCl concentration.
FDU-12 mesoporous silicas with highly ordered face-centred
cubic (Fm3m) structure were firstly synthesized by Zhao and
coworkers[16] using F127 as a template under strong acidic con-
ditions. Due to their large surface areas and uniformly adjustable
pore size, the materials have received much attention in the fields
of adsorption, catalysis and pharmaceutic. Besides, the morphol-
ogy of FDU-12 also has great influence on the activity of catalytic
reactions [17,18].
Zhao et al. [19] reported that the macroscopic morphology
of the mesoporous FDU-12 materials largely depended on the
local curvature energy, which was manifested in the interface of
local curvature energy could be tuned by adding different strong
inorganic salts, which facilitated the formation of various mor-
phologies. FDU-12 mesoporous matrials with the morphologies
of doughnut-like, hard/hollow sphere and hexagonal disk crystals
have been reported [20]. It was found that divalent sulfates like
CuSO4, NiSO4, ZnSO4 or MgSO4 were indispensable for the forma-
tion of ordered Fm3 m pore structure, while K2SO4 and Na2SO4 is
beneficial to generate hollow nanospheres.
In this research, a series of mesoporous silicas FDU-12 with
remarkable morphologies were successfully synthesized by intro-
ducing different inorganic salts under acidic condition. The
corresponding NiMo catalysts supported on the above mesoporous
materials were prepared by two-step incipient-wetness impregna-
tion method. The FDU-12 supports with different morphologies and
the corresponding catalysts were characterized by SAXS, BET, SEM,
TEM, UV–vis, Raman, pyridine-FTIR and XPS techniques. Further-
more, the effect of morphology on the HDS activity was investigated
at different WHSVs using DBT as probe molecules. The DBT HDS
activity followed the order: hexagonal prism catalyst (NiMo/F-
HP) > spiral catalyst (NiMo/F-SP) > brick-like catalyst (NiMo/F-BL).
and brick-like morphologies were denoted as F-HP, F-SP and F-BL,
respectively.
The corresponding NiMo catalysts were prepared by two-step
incipient-wetness impregnation of ammonium heptamolybdate
((NH4)6Mo7O24·4H2O, Sinopharm Chemical Reagent, 99.9 wt%) and
nickel nitrate ((Ni(NO3)2·6H2O, Tianjin Guangfu Fine Chemical
Research Institute, 99.99 wt%). After each impregnation, the sam-
ples were dried overnight in an oven at 80 ◦C and calcined in air at
550 ◦C for 6 h. The obtained catalysts were crushed into 40–60 mesh
particles. The metal composition was 12 wt% of MoO3 and 3 wt% of
NiO. The resulting catalysts were denoted as NiMo/F-HP, NiMo/F-SP
and NiMo/F-BL, respectively.
2.2. Characterization of supports and catalysts
Small-angle X-ray scattering (SAXS) patterns carried out on a
NanoSTAR Small-Angle X-ray scattering system (Bruker, Germany)
using Cu K␣ radiation (40 kV, 35 mA).
Nitrogen sorption isotherms of the samples were measured
by a Micromeritics TriStar II 2020 porosimetry analyzer at 77 K.
The specific surface areas of the samples were calculated using
the Brunauer-Emmett-Teller (BET) method. The total volumes of
micro- and mesopores were calculated from the amounts of nitro-
gen adsorbed at p/p0 = 0.98. The pore size distribution (PSD) was
derived from the desorption branches of the isotherms using the
Barrett-Joyner-Halenda (BJH) method.
Scanning electron microscopy (SEM) images were recorded on
a Cambridge S-360 apparatus operating at 20 kV. Transmission
electron microscopy (TEM) measurements were carried out via a
JEOL2010 electron microscope at an acceleration voltage of 200 kV.
The surface acid types and amounts over the catalysts were
carried out by pyridine-FTIR spectroscopy in an in situ FTIR cell
(MAGNAIR 560) with a resolution of 1 cm−1. The FTIR spectra were
obtained after the system was degassed at different temperatures
(200 ◦C and 350 ◦C) for 2 h.
The UV–vis diffuse reflectance spectroscopy (UV–vis DRS)
experiments were recorded in the wave number of 200–800 nm
using a Hitachi U-4100 UV–vis spectrophotometer with the inte-
gration sphere diffuse reflectance attachment.
The Raman spectra were obtained using a Raman spectrom-
eter (Renishaw Micro-Raman System 2000), operating with the
laser wavelength of 325 nm. The laser spot size was approximately
1–2 mm with a power of 8 mW.
The X-ray photoelectron spectra (XPS) of the sulfided catalysts
were acquired on a PerkinElmer PHI-1600 ESCA spectrometer.
2.3. Catalytic activity measurement
The HDS reactions of DBT were carried out in a continuous flow,
fix-bed reactor (8 mm inner diameter and 400 mm in length) loaded
with 0.5 g catalyst (40–60 mesh) diluted in 3 g quartz particles. All
the fresh catalysts needed to be presulfided in situ for 4 h with a
mixture of H2 and 2 wt% CS2 in cyclohexane solution at 340 ◦C and
4 MPa.
2. Experimental
2.1. Preparation of supports and catalysts
The synthesis procedure follows: 2.0 g of triblock copolymers
F127, a certain amount of inorganic salt(KCl/MgSO4/MnCl2), 2.0
of 1,3,5-trimethylbenzene (TMB, Sinopharm Chemical Reagent,
98.0 wt%) were dissolved in 120 mL of 2.0 M HCl aqueous solution
with vigorous stirring for 24 h. Then 8.3 g of tetraethyl orthosili-
cate (TEOS, Sinopharm Chemical Reagent, 99.0 wt%) as the silicate
source was added dropwise into the above surfactant solution
for another 24 h. Afterwards the mixture was transferred into a
Teflon bottle and heated statically at 100 ◦C for 72 h. The final
as-synthesized product was obtained by filtering, washing with dis-
tilled water, and drying at 80 ◦C for 24 h in air, ultimately, calcined
at 550 ◦C for 6 h. The FDU-12 samples with hexagonal prism, spiral
After sulfidation, a reactant (DBT) with the sulfur contents of
500 ppm dissolved in the solvent cyclohexane was fed into the
reactor by a SP-D-3201 double-piston pump. The catalysts were
evaluated under the conditions of 340 ◦C, 4 MPa, H2/Oil ratio of
200 mL/mL and WHSV of 20–150 h−1
.
The sulfur contents of the feedstock and products were tested in
a sulfur and nitrogen analyzer (RPP-2000SN, Taizhou Central Ana-
lytical Instruments Co. Ltd., P.R.China). To corroborate the product
compositions, the liquid products were analyzed by using gas chro-
matography with a mass spectrometer (GC–MS, Thermo-Finnigan
Trace DSQ) with a HP-5MS column (60 m × 0.25 mm × 0.25 m).
Please cite this article in press as: X. Wang, et al., Synthesis of NiMo catalysts supported on mesoporous silica FDU-12 with different