G Model
CATTOD-10312; No. of Pages10
ARTICLE IN PRESS
L. Rivoira et al. / Catalysis Today xxx (2016) xxx–xxx
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environmentally benign properties [20,21]. In the field of catal-
ysis, various acids [23–25], metallic ionic liquids (ILs) [26–29],
homogeneous and heterogeneous polyoxometalate (POM) cata-
lysts [30,31], and solid catalysts including activated carbon [32–34],
titanium micro/mesoporous silica materials [20,35–39], homoge-
2.1.3. Synthesis of CMK-3 carbon
The synthesis of CMK-3 mesoporous carbon was carried out
using SBA-15 as the hard template and sucrose as the carbon pre-
cursor, following the synthesis procedure described in our previous
work [46]. Briefly 1.1 g of sucrose was dissolved in a solution of
neous and heterogeneous rhenium catalyst [21], VOx/Al O [16],
H SO (0.14 g) in water (5 g). 1 g of SBA-15 was added to the solu-
2
3
2 4
◦
WOx/ZrO2 [40,41] and Mo/Al O3 [42] have been used. Molecular
tion. The resulting mixture was dried at 100 C and then was heated
2
◦
sieves show good activity in the oxidation of different S-bearing
compounds, and higher surface area materials such as V-MCM-
up and kept at 160 C for 6 h. A second impregnation was performed
in order to ensure the filling of the template pores with the carbon
precursor, using an H SO solution with 0.75 g of sucrose. The mix-
4
1[35], Ti-modified SBA-15 [36], Ti-modified SBA-16 [20] and
2
4
◦
◦
activated carbons [34] were also used as catalysts for the ODS.
Many attempts have been made to develop adsorbents for desul-
furization of commercial fuels using metal-based porous materials
such as zeolites, activated carbon and mesoporous silica. Meso-
porous silicate materials are a suitable adsorbent due to their
superior properties such as high surface area, tuneable and large
pore size and high thermal stability which facilitate the diffusion of
large molecules into the pores and overcome the pore-size limita-
tion of zeolites [43]. Recently, we tested sulfur removal of different
desulfurization systems; using several Ti modified mesoporous cat-
alysts (TiO , TiO /SBA-16 and Ti-SBA-16) [20].
ture was dried at 100 C and heated up and kept at160 C for 6 h.
Then, the brown powder obtained was heated up to 900 C under
◦
nitrogen flow (20 mL/min).
The silica removal was performed using a HF solution (5 wt.%)
at room temperature. The carbon sample was filtered, washed with
◦
ethanol solution and dried at 120 C.
2.1.4. Synthesis of V-CMK-3 and Ti-CMK-3
Vanadium was incorporated into the ordered mesoporous car-
bon CMK-3 by wetness impregnation using VCl3 as the source of
Vanadium. The metal precursor (VCl ) was dissolved in 20 mL of
2
2
3
Mesoporous carbon materials are of interest in many appli-
cations because of their high surface area and physicochemical
properties. With its well-ordered pore structure and tunable pore
diameters in the mesopore range, ordered mesoporous carbon
ethanol under vigorous stirring.The solution was placed in a rotary
◦
evaporator to remove excess of ethanol at about 50 C and 50 rpm.
◦
The obtained powder was then dried at 100 C, overnight. The dried
◦
process of the V-CMK-3 samples at 100 C in a furnace in presence
(
OMC) is suitable for applications in catalysis. Mesostructured car-
of air is sufficient to oxidize the vanadium species to vanadium
pentoxide and prevent the carbon combustion. Then, the resulting
material was heated in a dynamic inert atmosphere (nitrogen flow
bon CMK-3 has been obtained by template synthesis using SBA-15
mesostructured silicate. Our propose is to use a good sorbent mate-
rial such as a mesoporous carbon as a support for the catalyst,
functionalized with well known transition metals as active sites
for ODS. There are a few reports in literature of the application of
these materials as sorbents for S-compounds [44,45]. However, we
have not found any report of mesoporous ordered carbon material
as catalyst support applied in ODS process.
◦
◦
of 20 mL/min) from 25 to 200 C with a slope of 4 C/min and then,
◦
◦
the temperature was increased to 470 C with a slope of 10 C/min
and kept at this temperature during 5 h. Samples with different load
of vanadium were prepared. The samples were named V-CMK-3 (1,
3 and 7 wt.%).
Similarly, titanium was incorporated into the ordered meso-
porous carbon CMK-3 by wetness impregnation using Tetrabuty-
lortotitanate (TBOT) as the source of titanium. The metal precursor
(TBOT) was dissolved in 10 mL of ethanol under vigorous stirring,
in order to have a nominal content of 7 wt.% of Ti in the final solid.
CMK-3 was incorporated to the solution and placed in a rotary
In this work we evaluate vanadium and titanium-based catalysts
supported over a mesoporous carbon with large surface area (CMK-
3
) in the ODS of dibenzothiophene as a model sulfur compound.
2
2
2
. Experimental
◦
evaporator to remove excess of ethanol at about 40 C and 60 rpm.
◦
The powder obtained was then dried at 100 C, overnight. Finally,
.1. Synthesis of the catalysts
the resulting material was heated in a dynamic inert atmosphere
◦
(
4
nitrogen flow of 20 mL/min) from 25 to 200 C with a slope of
.1.1. Materials
◦
◦
C/min and then the temperature was increased to 470 C with
a slope of 10 C/min and kept at this temperature during 5 h. The
sample was named Ti-CMK-3.
Tetraethylorthosilicate
(TEOS,
98%,
Sigma–Aldrich),
◦
Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly
(
(
ethylene glycol), (EO20PO70EO20, P123-Sigma–Aldrich), Sucrose
≥99.0%, FLUKA), Vanadium(III) chloride (99.999%, Sigma–Aldrich).
2.2. Characterization of the catalysts
Tetrabutylortotitanate (TBOT, 99.0%, Sigma–Aldrich).
XRD patterns were collected by using a continuous scan
◦
2
.1.2. Synthesis of Si-SBA-15
SBA-15 was used as the template in the synthesis of CMK-
. The synthesis of the ordered mesoporous silica SBA-15 was
mode.The scan speed was 0.02 (2)/min in the Philips X’Pert PRO
PANalytical diffractometer, operating with CuKa X-ray radiation (X-
ray generator current and voltage set at 40 mA and 45 kV), using
small divergence and scattering slits of 1/32 mm and a goniome-
3
prepared according to a previous work [46]. Typically, 20 g of
P123 (Poly(ethylene glycol)-block-poly(propylene glycol)-block-
poly (ethylene glycol)) was dissolved at 50 C in 1 M HCl solution.
Then, 40 g of TEOS were added and the resulting mixture was
stirred at 50 C for 24 h. The milky mixture was transferred into
◦
−1
ter speed of 1.2 (2) min . The scanning range was set between
◦
◦
◦
0.5 and 5 . The sample was crushed previously and placed in an
aluminum sample holder. Elemental analysis was performed by
inductively coupled plasma-atomic emission spectroscopy (VISTA-
MPX) operated with high frequency emission power of 1.5 kW
and plasma airflow of 12.0 L/min. TPR was performed using a
Micromeritics Chemisorb 2720 apparatus, with a flow of 14 mL/min
of 10 mol% of H /N heating up 500 C, with a preheating treatment
at 380 C in an inert atmosphere (N ). N adsorption/desorption
surface area and pore volume; pore size distribution was estimated
◦
◦
a Polypropylene bottle and it was kept at 100 C for 72 h. The solid
was filtered, washed with deionized water until pH ∼6. The molar
composition was Si: 0.018 EO2 PO EO : 2.08 HCl: 112 H O. To
0
70
20
2
◦
extract the template, the material was first immersed in ethanol
reflux for 6 h. Then, the product was filtered, washed, and dried
agent, the sample was heated under N flow of 20 mL/min at 300 C
and then a calcined at 550 C in air for 6 h.
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2
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2
2
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2
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Please cite this article in press as: L. Rivoira, et al., Vanadium and titanium oxide supported on mesoporous CMK-3 as new catalysts for