New mesoporous silicotitaniumphosphate and its application in acid catalysis and adsorption of As(III/V), Cd(II) and Hg(II)

Article abstract of DOI:10.1016/j.molcata.2010.07.001

A new mesoporous silicotitaniumphosphate material has been synthesized by using a non-conventional phosphorous source trimethyl phosphite with the aid of Pluronic F127 as structure directing agent (SDA). The mesopores are generated due to the slow hydrolysis of the reactant materials in the presence of supramolecular-assembly of non-ionic surfactant under the evaporation induced self-assembly (EISA) process. The material has been characterized by powder XRD, N₂ sorption, TEM, SEM-EDS, TG-DTA, FT-IR, XPS, ²⁹Si, ³¹P MAS NMR and UV-vis spectroscopic techniques. This new mesoporous material has considerably high BET surface area (379 m² g ^-1) and narrow pore size distribution with a peak pore width of 5.4 nm. The material showed good catalytic activity in the liquid phase Friedel-Crafts benzylation reaction suggesting strong acidity on its surface. It can also be used as good adsorbent for the removal of toxic metal ions As(III/V), Cd(II) and Hg(II) from the contaminated water.

Full text of DOI:10.1016/j.molcata.2010.07.001

Journal of Molecular Catalysis A: Chemical 330 (2010) 49–55
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Journal of Molecular Catalysis A: Chemical
journal homepage: www.elsevier.com/locate/molcata
New mesoporous silicotitaniumphosphate and its application in acid catalysis
and adsorption of As(III/V), Cd(II) and Hg(II)
Manidipa Paula, Nabanita Pala, M. Alib, Asim Bhaumika,∗
a Department of Materials Science, Indian Association for the Cultivation of Science, 2A & B Raja S. C. Mullick Road, Jadavpur, Kolkata , West Bengal 700 032, India
b Chemistry Department, Jadavpur University, Jadavpur, Kolkata, West Bengal 700 032, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A new mesoporous silicotitaniumphosphate material has been synthesized by using a non-conventional
phosphorous source trimethyl phosphite with the aid of Pluronic F127 as structure directing agent (SDA).
The mesopores are generated due to the slow hydrolysis of the reactant materials in the presence of
supramolecular-assembly of non-ionic surfactant under the evaporation induced self-assembly (EISA)
process. The material has been characterized by powder XRD, N2 sorption, TEM, SEM–EDS, TG–DTA,
FT-IR, XPS, 29Si, 31P MAS NMR and UV–vis spectroscopic techniques. This new mesoporous material has
considerably high BET surface area (379 m2 g−1) and narrow pore size distribution with a peak pore width
of 5.4 nm. The material showed good catalytic activity in the liquid phase Friedel–Crafts benzylation
reaction suggesting strong acidity on its surface. It can also be used as good adsorbent for the removal of
toxic metal ions As(III/V), Cd(II) and Hg(II) from the contaminated water.
Received 24 December 2009
Received in revised form 2 April 2010
Accepted 1 July 2010
Available online 7 July 2010
Keywords:
Adsorption
Benzylation reaction
Heteroelement incorporation
Mesoporous materials
Titanium phosphate
© 2010 Elsevier B.V. All rights reserved.
1. Introduction
stability of these phosphate-based mesoporous materials is rela-
tively poor due to the highly charged framework structure. On the
Since the discovery of mesoporous silica molecular sieves
using the supramolecular-assembly of surfactants as SDA [1,2],
the door for a new area of research is opened to the researchers.
The very high surface area, tunable pore size, easy functional-
ization and large diversity of frameworks have made this class
of material an efficient catalyst, adsorbent and an excellent host
for the nanomaterial synthesis. In the last few years attentions
have also been focused to explore different types of mesoporous
materials other than silica framework like metal oxides, phos-
phates, carbon, etc. Functionalized mesoporous materials have
received much interest in this context due to their wide applica-
tion in various catalytic reactions [3–5]. Recently several porous
metallophosphates [6–9] have been reported, which could find
important applications as catalyst in selective organic reactions
[8], exchanger [9] and photocatalysis [10]. Mesoporous mate-
rials containing different hetero-elements find various practical
applications due to the specific physical and chemical nature of
the doped element in the framework. Although the mesoporous
titanium phosphates synthesized using cationic and anionic sur-
factants as SDA have been exploited as catalysts for liquid phase
oxidation and photocatalytic reactions, their potentiality in acid
catalyzed reactions have not been studied so far. Moreover the
other hand, multi-component mesoporous phosphate-based mate-
rials [11] have better stability and high surface area. But to date,
their catalytic properties in liquid phase reactions have not been
explored so far.
This problem can be overcome by introducing Si in the meso-
porous titanium phosphate framework similar to the incorporation
of Si in the aluminophosphate [12,13] or tin(IV) phosphate mate-
rials [14]. Herein, we report the synthesis of novel mesoporous
silicotitaniumphosphate material having very high surface area and
thermal stability. The material also exhibits a good catalytic activ-
ity in benzylation reaction. To the best of our knowledge there is
no report of mesoporous silicotitaniumphosphate material in the
literature. Furthermore in this synthetic procedure we have cho-
sen Pluronic F127 as template, which generally plays a crucial role
for the formation of silica [15] and metal oxide [16] mesophases
using evaporation induced self-assembly (EISA) method. The main
advantage of this procedure is that here we can adjust the molar
ratio of the constituents in the precursor gel, as the ratio remain
almost same in gel and final calcined product. This novel material
showed good adsorption property and catalytic activity in liquid
phase benzylation reaction.
2. Experimental
∗
Mesoporous silicotitaniumphosphate has been synthesized
using titanium (IV) butoxide (Ti(BuO)4, Aldrich) as the source of
Corresponding author. Fax: +91 33 2473 2805.
E-mail addresses: msab@iacs.res.in, msab@mahendra.iacs.res.in (A. Bhaumik).
1381-1169/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.molcata.2010.07.001

50
M. Paul et al. / Journal of Molecular Catalysis A: Chemical 330 (2010) 49–55
Table 1
Physico-chemical properties of mesoporous silicotitaniumphosphate sample.
Sample
Surface Si:Ti:P mole ratio
BET surface area (m2 g−1
)
Adsorption capacity (mmol g−1
0.8
)
Gel
Solid
MSTP-Cal
1:1:0.5
0.87:0.8:0.5
379
titanium. Trimethyl phosphite (TMP, Spectrochem) and tetraethy-
lorthosilicate (TEOS, Aldrich) were used here as phosphorous and
silica precursors, respectively. Triblock co-polymer Pluronic F127
(Aldrich) was used as structure directing agent (SDA) in the pres-
ence of concentrated hydrochloric acid (HCl, Merck, 35% aqueous)
and acetic acid (AcOH, Merck, 100% glacial). In a typical synthetic
procedure, first 2.4 g Pluronic F127 was dissolved in 30 ml of abso-
lute ethanol with the addition of 2.4 g of acetic acid and 2.5 g of
conc. HCl under vigorous stirring. The mixture was covered with
a PE film and stirred at room temperature until it dissolved com-
pletely. Then 3.4 g of titanium (IV) butoxide was added to the above
mixture and the mixture was stirred for another 1 h before 2.08 g
of TEOS was added. TEOS was then allowed to hydrolyze in the
acidic medium followed by the addition of 0.62 g of TMP to the syn-
thetic gel. After gelation at 313 K (relative humidity was controlled
at ∼40%) for 1 day, the gel was transferred in an oven at 333 K and
aged for 3 days. The molar ratio of the various constituents in the
gel was 0.19 F127: 514.0 EtOH: 10.0 Ti(BuO)4: 5.0 TMP: 40.0 AcOH:
24.0 HCl: 10.0 TEOS. The resulting pale-yellow colored solid powder
material was calcined in the flow of air at 673 K for 6 h to remove
the template. The as-synthesized and calcined samples have been
designated as MSTP-As and MSTP-Cal, respectively.
Powder X-ray diffraction patterns of the materials were
recorded on a Bruker D-8 Advance diffractometer operated at 40 kV
voltage and 40 mA current and calibrated with a standard sili-
con sample, using Ni-filtered Cu K␣ (ꢀ = 0.15406 nm) radiation.
Nitrogen adsorption/desorption isotherms were obtained using a
Beckman Coulter SA 3100 surface area analyzer at 77 K. Before
the measurement, the sample was degassed at 423 K for 3 h.
TEM images were recorded in a Jeol JEM 2010 transmission elec-
tron microscope. JEOL JEM 6700F field emission scanning electron
microscope with an energy dispersive X-ray spectroscopic (EDS)
attachment was used to record the morphology of the sample and
its surface chemical composition. FT-IR spectra of these samples
were recorded on KBr pellets by using a Nicolet MAGNA-FT IR
750 spectrometer series II. UV–visible diffuse reflectance spectra
were obtained by using a Shimadzu UV 2401PC spectrophotome-
ter with an integrating sphere attachment and BaSO4 pellet was
used as background standard. Thermogravimetry (TG) study and
differential thermal analysis (DTA) were carried out in a thermal
analyzer TA SDT Q-600. 29Si and 31P solid state magic angle spin-
ning nuclear magnetic resonance (MAS NMR) experiments were
carried out to evaluate the different chemical environment of the
Si and P atoms in the mesoporous matrix. Bruker advance 500 spec-
trometer was used here for NMR data recording. Tetramethylsilane
(TMS) and phosphoric acid were used as reference for chemical shift
measurement for 29Si and 31P, respectively. X-ray photoelectron
spectrum (XPS) of the mesoporous silicotitaniumphosphate sample
was recorded in VG Microtech Clam 2 Analyzer using Mg K-alpha
X-ray source. The spectrum was calibrated taking the reference of
C 1s peak at 284.5 eV.
lent 7890 A) equipped with a FID detector and fitted with a capillary
column. The conversion was calculated based on the amount of the
benzylating agent.
For measuring the ion-exchange efficiency of the MSTP-Cal,
0.05 g of the sample was taken in 40 ml 0.01 M KCl solution and the
mixture was stirred for 2 h. Then the solution was filtered. The Cl−
concentration in the initial KCl solution and in the final filtrate solu-
tions were determined through titration by using a 0.01 M AgNO3
solution. In the titration 5% potassium chromate aqueous solution
was used as indicator. Then the exchanged Cl− concentration and
hence the anion exchange capacity was measured by subtracting
the Cl− ion concentration in the filtrate from the initial one.
3. Results and discussion
3.1. Synthetic strategy and chemical composition
Here the synthesis of mesoporous silicotitaniumphosphate has
been carried out by the slow evaporation method. For the prepa-
ration of the synthesis gel very highly acidic medium has been
employed as only at this low pH the template F127 can form micelle
through H-bonding interactions [15,16]. Acetic acid here plays the
role of a complexing agent to stabilize Ti(IV). The key factor of this
synthesis is slow hydrolysis of the constituents. For this reason Ti(t-
BuO)4 and TMP is used here instead of other common titanium and
phosphorous sources. The gel preparation is carried out in absence
of water and absolute alcohol is used as solvent. Surface chemical
composition of the mesoporous silicotitaniumphosphate material
is given in Table 1. As seen from the table that Si/Ti mole ratio in
MSTP-Cal is 1.08, which is very similar to the synthesis gel mixture.
3.2. Powder XRD
The small angle powder XRD pattern of MSTP-Cal sample is
shown in Fig. 1. A single peak for d100 plane is observed at 2ꢁ value
1.05, which indicates that sample has mesopores in the framework
The liquid phase benzylation reactions were carried out in a
50 ml two necked round bottom flask equipped with a reflux con-
denser and septum. The reactions were carried out at 348 K by using
a temperature controlled oil-bath. The substrate and the benzylat-
ing agent i.e. benzyl chloride was added to the catalyst in a required
molar ratio (10:1). The catalyst was pretreated at 673 K for 4 h prior
to the reaction. Aliquots were withdrawn at a regular interval from
the reaction mixture and analyzed using a gas chromatograph (Agi-
Fig. 1. Powder XRD pattern of the MSTP-Cal.

M. Paul et al. / Journal of Molecular Catalysis A: Chemical 330 (2010) 49–55
51
Fig. 3. TEM image of the MSTP-Cal.
Fig. 2. N2 adsorption (᭹)/desorption (ꢀ) isotherms and pore size distribution (inset)
of the MSTP-Cal.
structure but devoid of any long range mesoscopic ordering. The 2ꢁ
value corresponds to an average inter-pore separation of 8.1 nm.
The wide angle XRD pattern (not shown) clearly indicates amor-
phous nature of the sample and absence of any impurity TiO2 and/or
condensed phosphate phases.
3.3. Surface area and pore size distribution
In Fig. 2 N2 adsorption–desorption isotherms of MSTP-Cal sam-
ple are shown. As seen from the figure that the isotherms are of
type IV in nature, having capillary rise at higher P/P0 together with
hysteresis loop, indicating the existence of large cylindrical meso-
pores [17,18]. Brunauer–Emmett–Teller (BET) surface area of the
sample calculated from this isotherm is 379 m2 g−1. Pore size dis-
tribution (PSD) of the sample estimated from these isotherms by
using non-local density functional theory (NLDFT, inset of Fig. 2)
suggested the average pore width is ca. 5.4 nm.
3.4. Morphology study
The transmission electron microscopy (TEM) image of this
calcined MSTP-Cal sample is shown in Fig. 3. The presence of
low electron density spherical spots of 5.0–6.0 nm diameters,
corresponding to the large size mesopores and their disordered
wormhole-like arrangements. Thus from TEM images and the small
angle XRD data we can conclude that this mesoporous silicotita-
niumphosphate material has disordered wormhole structure. The
average mesopore dimension obtained from the PSD pattern of the
N2 sorption isotherms is also nearly same with that obtained from
the TEM image analysis. Textural property and particle size of the
mesoporous material were investigated from the scanning electron
microscopy (SEM). Typical morphology of the sample is displayed
in Fig. 4, showing large aggregates formed with very tiny spherical
nanoparticles having dimensions of 15–20 nm. Chemical analysis
data (using EDS) is shown in the bottom of Fig. 4, confirming that
Ti, Si, P and O distributed uniformly in MSTP-Cal sample.
3.5. Metal–template interaction
The nature of framework and bonding of the as-synthesized
and calcined mesoporous silicotitaniumphosphate samples (Fig. 5)
Fig. 4. SEM image of the MSTP-Cal (a) and its EDS pattern (b).

52
M. Paul et al. / Journal of Molecular Catalysis A: Chemical 330 (2010) 49–55
Fig. 6. UV–visible diffuse reflectance spectra of the MSTP-Cal (a) and TiO2 (b).
Fig. 5. FT-IR spectra of the as-synthesized MSTP-As (a) and calcined MSTP-Cal (b).
the DTA curve at the temperature range 302–496 K which suggests
that the sample is stable upto 496 K. A sharp wt loss of ca. 44.2%
is occurred at the temperature range 496–650 K, which is mainly
due to the removal of the organic SDA molecules from the MSTP-
As. In the DTA curve also we observed a sharp exotherm at 641 K,
indicating the decomposition of F127 molecules.
are obtained from FT-IR spectral analysis. According to the litera-
ture [19] the broad band coming near 3400 cm−1 attributed to O–H
stretching vibration and a low intense peak near 1630 cm−1 is the
deformation vibration for H–O–H bonds of the physically adsorbed
moisture. The peak coming at 2850–3000 and 1115 cm−1 for the
as-synthesized sample are assigned to the C–H and C–O–C stretch-
ing vibration of F127, which is absent in the calcined sample due to
the removal of surfactant after high temperature heat treatment.
The wide band near 1050–1130 cm−1 could be attributed to Ti–O–P
framework vibration [20] and the band obtained at 1230 cm−1 due
to P–O–H bond. Another band obtained at 665 cm−1 indicates the
presence of O–P–O stretching, whereas vibration at 568 cm−1 [21]
indicates the presence of Ti–O bond. The peak at 946 cm−1 could be
attributed to the Si–O–H stretching. Absence of peak at 1090 cm−1
suggests that no Si–O–Si bond is present in the framework structure
[22] of silicotitanium phosphate.
3.8. XPS study
Fig. 8a shows the high-resolution XPS spectra of Ti 2p electron
on our calcined mesoporous silicotitaniumphosphate material.
The XPS spectra of the Ti 2p region are composed of two peaks. The
binding energies for Ti 2p3/2 and Ti 2p1/2 are 459.2 and 465.4 eV.
Titanium (IV) atoms located at the tetrahedral positions in the
titanium silicate framework of TS-1 have Ti 2p3/2 and Ti 2p1/2
binding energies of 460 and 466 eV, respectively [26,27] whereas
for octahedral co-ordination these energies correspond to 458 and
464 eV, respectively. As in our sample the peaks come at 459.2
and 465.4 eV so it confirms that a majority of the titanium species
3.6. Optical study
Fig. 6 represents the UV–visible spectra of MSTP-Cal along with
bulk titania. Compared to bulk titania, MSTP-Cal shows a blue shift
in absorption band (331 and 300 nm, respectively). The absorption
band coming in the wavelength region 300 nm is mainly due to
the electronic transition from O2− 2p to Ti4+ 3d orbital. A similar
high-energy absorption edge due to tetrahedral co-ordination of Ti
has been observed for mesoporous titanosilicate [23], Ti-exchanged
Y-zeolites [24] and heteroelement doped TiO2 nanostructured
materials [25]. The high-energy absorption band indicates that the
tetrahedral co-ordination of Ti is dominant in mesoporous silicoti-
taniumphosphate sample.
3.7. Thermal analysis
In Fig. 7, the thermogravimetric (TG) and differential thermal
analysis (DTA) data are shown for the as-synthesized mesoporous
silicotitaniumphosphate sample. From the figure it is seen that ca.
10 wt.% loss has taken place up to 495 K in the TGA curve, which is
actually composed of two steps. The first step is accompanied with a
sharp wt. loss of ca. 7.3% followed by a gradual decrease at elevated
temperature. This is because of the removal of the adsorbed water
molecule from the surfaces. No such distinct peak is observed in
Fig. 7. TG (a) and DTA (b) curves for the as-synthesized MSTP-As sample.

M. Paul et al. / Journal of Molecular Catalysis A: Chemical 330 (2010) 49–55
53
Fig. 9. 29Si (up) and 31P (down) MAS NMR of MSTP-Cal.
with a SiO4 tetrahedral unit [31]. 29Si MAS NMR spectrum of MSTP-
Cal is shown in Fig. 9 (up). From the figure it is clear that there are
two major Si species corresponding to chemical shifts at ca. −105.2
and −95.6 ppm. These could be attributed to the Ti(IV) substitution
in Si(OSi)4 (Q4) and Si(OH)(OSi)3 (Q3) environments, respectively
[31]. Considerable downfield chemical shifts for all these peak max-
imas vis-à-vis pure mesoporous silica SBA-15 [32] suggested P
and Ti incorporation adjacent to the SiO4 tetrahedral units. The
presence of Ti and P atoms in the vicinity of SiO4 tetrahedra may
also create Si(3Si, Ti/P) and Si(2Si, 2Ti/P) like local environments,
which could contribute significantly to the large downfield chem-
ical shifts. On the other hand the 31P MAS NMR spectra of the
titanium phosphate samples showed a broad signal with chemi-
cal shifts between 10 and −25 ppm (Fig. 9, down). This peak can be
assigned to a mixture of tetrahedral P environments with connec-
tivity 3 and 4 [P(OTi)3OH and P(OTi)4]. Tetrahedral phosphorous in
mesoporous titanium phosphate materials shows a strong sharp
band at ca. −5.4 to −9.8 ppm [9]. Thus these 29Si and 31P MAS
NMR experiments revealed the presence of tetrahedral Si and P
species inside the network of mesoporous silicotitaniumphosphate
material.
Fig. 8. PS of Ti 2p (a), P 2p (b) and Si 2p (c) of MSTP-Cal.
in our sample is Ti(IV) and they are tetrahedrally co-ordinated. P
2p binding energy for MSTP-Cal (Fig. 8b) is observed at 134.4 eV,
indicating the pentavalent state of P in the material. Absence of
any peak near 128.6 eV, which is usually attributed to the binding
energy of Ti–P bond [28,29] suggested that there is no bonding
between Ti and P present in our MSTP-Cal material. In Fig. 8c XPS
spectrum of Si 2p is shown. As seen from the spectrum that signal
observed at 104.23 eV [30], confirms the presence of tetrahedral Si
in the framework of mesoporous silicotitaniumphosphate.
3.10. Adsorption studies
Mesoporous silicotitaniumphosphate has been used as adsor-
bent for the removal of toxic metal ions like As(III/V), Cd(II) and
Hg(II) from their respective aqueous solutions. In Table 1 chloride
exchange capacity for MSTP-Cal sample is given. For metallophos-
phate materials due to the presence of imbalanced positive charge
in the framework could be responsible for the anion exchange
capacity as observed for mesoporous titanium- [33], tin- [34] and
niobiumphosphate [35] materials. Moderately good ion-exchange
capacity of the mesoporous silicotitaniumphosphate material has
motivated us to explore its potential in removing pollutant metals
3.9. 29Si and 31P solid state MAS NMR study
29Si chemical shifts of silicates are often utilized as an important
tool to understand the local environment of the T-atoms connected

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M. Paul et al. / Journal of Molecular Catalysis A: Chemical 330 (2010) 49–55
Table 2
Toxic metal uptake by mesoporous silicotitaniumphosphate.a.
Entry
Solution type
Metal content (mg/l)
Before
Metal adsorption efficiency (%)
After
1
2
3
4
5
6
7
∼200 ppb As(III)
0.208
0.208
0.203
0.205
0.832
0.941
1.034
0.0856
0.015
0.061
0.058
0.359
0.227
0.235
57.2
92.5
69.2
71.7
56.8
75.9
74.3
∼200 ppb As(III) + 0.05 g H2O2
∼200 ppb Hg(II)
∼200 ppb Cd(II)
∼1000 ppb As(III)
∼1000 ppb Hg(II)
∼1000 ppb Cd(II)
a
As(III/V), Cd(II) and Hg(II) concentrations before and after the adsorption studies are measure by AAS.
from the waste water. Arsenic is found in its most common valence
state as arsenate As(V), in aerobic surface water and as arsenite,
As(III), in anaerobic ground water. In t−he low pH range (4–8) the
exchanger. In other hand, As(III) remained mostly in nonionised
form H3AsO3 can easily be oxidized by mild oxidants like H2O2. In
Table 2 arsenic removal efficiencies of MSTP-Cal from ∼200 ppb
arsenic containing NaAsO2 solution with or without addition of
small amount of H2O2 have been given. As seen from the results
2−
predominant As(V) species are H2AsO4 and HAsO4 [36], which
are negatively charged and thus easy to get exchanged by an ion
Table 3
Liquid phase benzylation reactions over mesoporous silicotitaniumphosphate.a.
Substrate
Product
Time (h)
Conversion (%)
Selectivity (%)
24
98.9
48.7
51.3
24
43.5
100
24
29.2
100
a
Reaction conditions: temperature 353 K, substrate: benzyl chloride = 10:1.

M. Paul et al. / Journal of Molecular Catalysis A: Chemical 330 (2010) 49–55
55
that As(V) is more effectively adsorbed over the sample than As(III),
which agrees quite well with our previous results on mesoporous
silicotinphosphate material [14]. A relatively higher concentration
of As(III) (∼1000 ppb) similarly show moderate uptake efficiency
(Table 2). For the determination of the Hg removal efficiency ∼200
and 1000 ppb HgCl2 solutions has been taken as stock solutions.
After stirring these solutions with MSTP-Cal sample for 2 h each,
the concentrations of Hg(II) has been analyzed. Under this con-
dition Hg(II) could exist in the solution as a divalent cation [37]
and this could be efficiently adsorbed at the defect P–O− sites. A
considerably high Hg(II) adsorption efficiencies (69.2 and 75.9%)
has been observed over our mesoporous silicotitaniumphosphate
material. Similarly MSTP-Cal showed good Cd(II) adsorption effi-
ciencies for the respective Cd(II) containing solutions (Table 2).
These As(III/V), Cd(II) and Hg(II) adsorption efficiencies are com-
parable to the mesoporous PMO material LHMS-2 [38] containing
electron donor sites in the pore walls. Due to good adsorption effi-
ciencies for As(III/V) and Hg(II), the MSTP-Cal material can be used
as adsorbent for the removal of toxic metals from contaminated
water.
characterization results revealed the wormhole-like disordered
mesopores in the sample with an average pore dimension of 5.4 nm.
The spectroscopic data suggest that most of the Ti sites present
in this sample are tetrahedrally co-ordinated Ti(IV). Adsorption
of environmentally toxic As(III/V), Cd(II) and Hg(II), and catalytic
activity in liquid phase Friedel–Crafts benzylation of aromatics over
this novel mesoporous material could open up new opportunities
in future.
Acknowledgements
AB wishes to thank Department of Science and Technology, India
for financial supports. MP and NP are thankful to the CSIR, New
Delhi for their senior research fellowships.
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The liquid phase acid catalyzed Friedel–Crafts benzylation reac-
tion is carried out over this MSTP-Cal material to explore the
catalytic performance of it. The result of the reaction is shown in
Table 3. As seen from the table, 98.9% m-cresol, 43.5% p-xylene,
29.2% mesitylene have been benzylated over mesoporous silicotita-
niumphosphate over a period of 24 h. For m-cresol two benzylated
products corresponding to the para-adduct of the phenolic-OH and
methyl groups (Table 3) are formed in almost equal proportions.
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monobenzylated product is formed exclusively. This result indi-
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material AlSBA-15 [39]. Our synthesized catalyst MSTP-Cal shows
much higher activity with respect to this mesoporous material.
For p-xylene and mesitylene the conversions are 43.5 and 29.2,
respectively, over our MSTP-Cal, while it was 23.55 and 17.52%,
respectively, over AlSBA-15(45). Hence it can be concluded that
compared to the other representative solid acid catalysts with
mesopores and similar range of surface area our mesoporous MSTP-
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(due to framework charge) and the metal ion adsorption efficien-
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bonding interaction with F127 molecules at the surface) could be
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4. Conclusions
From our experimental observations we can conclude that
mesoporous silicotitaniumphosphate material having a good sur-
face area can be synthesized using triblock co-polymer F127 as the
SDA and an unconventional phosphorous source trimethylphos-
phite under evaporation induced self-assembly method. Detailed