G Model
CATTOD-9080; No. of Pages6
ARTICLE IN PRESS
H. Jin et al. / Catalysis Today xxx (2014) xxx–xxx
2
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performance in asymmetric hydrogenation and Sonogashira reac-
tion, respectively. However, to the best of our knowledge there is
no report on catalytic performance of sulfonic acid functionalized
mesoporous zeolites for acid catalysis.
several times with toluene and ethanol and dried at 80 C for 2 h.
Then the catalysts were oxidized with 10 ml of aqueous H O2
(30 wt%) at room temperature for 24 h under N2 atmosphere. Fur-
thermore, the sample was acidified with 0.1 M H SO for 4 h in
2
2
4
Recently, we reported a new synthetic strategy for synthe-
sis of mesoporous ZSM-5 by microwave induced assembly via
electrostatic interaction between sulfonic acid functionalized ZSM-
order to make sure that all the sulfonic acid groups was protonated.
The catalysts were filtered and washed with deionized water and
ethanol, finally dried at 60 C under vacuum overnight.
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5
nanoparticles and counter cationic alkyltrimethyl ammonium
surfactant [27]. This mesoporous ZSM-5 exhibited remarkably
enhanced catalytic activity in benzylation of aromatics with ben-
zyl alcohol compared with microporous ZSM-5 due to improved
uniform intracrystalline mesoporosity and external acid sites [28].
Owing to the significance of mesoporosity, stability and enhanced
catalytic activity, we expect this mesoporous ZSM-5 can be used as
an effective support for sulfonic acid functionalization and improve
the catalytic performance in acid catalysis.
2
.3. Characterization methods
Powder X-ray diffraction (XRD) patterns of catalysts were
obtained by using a Rigaku X-ray diffractometer with Cu K␣ radia-
tion (40 kV and 20 mA) from 0.8 to 40 . N2 adsorption–desorption
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isotherms were collected on a micromeritics ASAP 2020 at −196 C.
The specific surface areas of catalysts were calculated using
Brunauer–Emmett–Teller (BET) model and pore size distribution
was calculated by the Barrett–Joyner–Halenda (BJH) method from
In the present study, we report the preparation of sulfonic
acid functionalized mesoporous ZSM-5 (SO H-Meso ZSM-5) via
29
13
3
desorption branch of the isotherm.
Si and
C-NMR spectra
post-grafting with 3-mercaptopropyltriethoxysilane (3-MPTES)
were recorded on a Bruker 600 MHz solid-state NMR spectrom-
eter, respectively. X-ray photoelectron spectroscopy (XPS) was
recorded on Sigma Probe ThermoVG, U.K. monochromatic Al-K␣
followed by oxidation using aqueous H O2 to generate the cor-
2
responding sulfonic acid groups (Scheme 1). The influence of
mesoporosity on sulfonic acid functionalization is investigated by
comparison of the SO H-Meso ZSM-5 and SO H-ZSM-5 in the acid-
1
2 kV, 100 W, 400 m, wide scan with pass energy 50 eV and
3
3
step size 1.0 eV whereas narrow scan with pass energy 20 eV
step size 0.1 eV using (Avantage ThermoVG). Elemental analy-
ses were measured by Element Analyzer (Thermo EA1112). The
temperature-programmed adsorption and desorption reaction of
n-propylamine, the catalysts (50 mg) were pretreated at 450 C
for 2 h and exposed to n-propylamine at 200 C for 2 h. then the
ꢀ
catalyzed liquid-phase reaction of 2 -hydroxyacetophenone and
benzaldehyde. The effect of organic functional groups on the cat-
alytic activity is also investigated with various loading of 3-MPTES
in the range of 0–50 wt%.
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physisorbed n-propylamine was remove by evacuating the cata-
lyst for 2 h. The decomposition experiment was investigated in a
thermoanalyzer (Bruker axs 2000SA) combining thermaogravime-
try and differential thermoanalysis (TG-DTA) with a heating rate
2
. Experiment
2.1. Preparation of the ZSM-5 catalysts
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of 10 C/min to 800 C. The amount of decomposed n-propylamine
Meso ZSM-5 was synthesized according to previously
was obtained from weight loss in TGA curves in the range of
reported synthesis procedure [27]. ZSM-5 nanozeolites were
pre-crystallized with the following molar composition:
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3
00–600 C which was subtracted from the amount of organo
groups in the same temperature range.
1
Al O :60SiO :11.5TPAOH:1000H O. Aluminum isopropoxide
2 3 2 2
(
Aldrich) as alumina source was mixed with tetrapropylammo-
nium hydroxide (TPAOH; TCI, 20–25%) and deionized water. To the
resultant mixture tetraethyl orthosilicate (Aldrich, 98%) as silica
source was added to the mixture and homogenized by stirring.
The formed precursor gel was crystallized under microwave irra-
diation and functionalized with 3-mercaptopropyltriethoxysilane
2.4. Catalytic activity
ꢀ
ꢀ
The liquid-phase reaction of 2 -hydroxyacetophenone (2 -HAP)
and benzaldehyde was carried out in a bath reactor consisting of
three-necked round bottomed flask with condenser and connector
for N2 purge. Prior to the reaction, all the catalysts were activated
followed by treatment with H O2 (30 wt%). The obtained sulfonic
2
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acid functionalized ZSM-5 nanoparticles were assembled with
certyltrimethylammonium bromide cationic surfactant for 3 h,
at 150 C for 2 h. For the reaction in the absence of solvent, 10 mmol
ꢀ
of 2 -HAP and 15 mmol of benzaldehyde mixed and 100 mg of cata-
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and then move to microwave (600 W, 165 C for 2 h). Microporous
lyst were rapidly added. Before starting the reaction, the reactor
was purged by N2 in order to avoid oxidation of benzaldehyde
to benzoic acid. The reaction mixture was heated to 140 C with
simultaneously stirring. The reaction mixtures were withdrawn
at regular intervals and subjected to GC analysis equipped with
a flame ionization detector (FID) and capillary column (HP-5% sili-
cone gum). The products were confirmed by GC–MS (Agilent 5975).
The catalyst was filtered after the reaction and washed with acetone
ZSM-5 was synthesized from a clear solution with the following
molar composition: 1Al O : 60SiO : 11.5TPAOH: 1500H O under
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2
3
2
2
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microwave irradiation with 600 W of power at 165 C for 2 h. The
precipitated products were filtered and washed with deionized
water and ethanol. The catalysts were dried in an oven at 80 C for
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1
2 h and calcined in air at 550 C for 6 h.
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followed by drying at 150 C for 4 h prior to reuse.
2.2. Sulfonic acid functionalization of the ZSM-5 catalysts
Sulfonic acid functionalized mesoporous and microporous ZSM-
(SO H-Meso ZSM-5 and SO H-ZSM-5) were prepared as shown
3. Results and discussion
5
3
3
in Scheme 1. Detail procedures were followed as previous reports
3.1. Characterization of sulfonic acid functionalized ZSM-5
catalysts
[
29] with slight modification. Prior to functionalization, the cat-
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alysts were activated at 450 C for 2 h and used immediately. In a
typical synthesis, 1 g of catalysts suspended in 15 ml of toluene was
stirred for 30 min under N2 atmosphere and followed by the addi-
X-ray diffraction patterns of Meso ZSM-5 and SO H-Meso ZSM-
3
5 with different amounts of organosulfonic acid groups in the 2Â
◦
tion of amount of 3-mercaptopropyltriethoxysilane in the range of
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1
0-50 wt%. The mixture solution was refluxed at 110 C under N2
atmosphere for 24 h. The obtained catalysts were filtered, washed
patterns which was evidence for the presence of mesopore arrays
Please cite this article in press as: H. Jin, et al., Sulfonic acid functionalized mesoporous ZSM-5: Synthesis, characterization and catalytic