Iron exchanged tungstophosphoric acid supported on activated carbon derived from pinecone biomass: Evaluation of catalysts efficiency for liquid phase benzylation of anisole with benzyl alcohol

Article abstract of DOI:10.1016/j.apcata.2014.07.034

A series of iron-exchanged heteropoly tungstate (TPA-Fe) supported on activated carbon produced from pinecone biomass, have been investigated as catalysts for the benzylation reaction. Catalysts were characterized by FT-IR, XRD, Laser Raman, BET surface area, and ammonia TPD analysis. FT-IR, XRD, and Raman data revealed retention of the Keggin ion on activated carbon-supported catalysts. The catalytic activity of these catalysts was evaluated for liquid phase benzylation of anisole with benzyl alcohol. The catalytic activity was significantly dependent on the dispersion of TPA-Fe on activated carbon. The effect of TPA-Fe loading on activated carbon was studied ranging from 40 to 80 wt%. The catalyst with 70 wt% loading of TPA-Fe showed higher benzylation activity, which is related to variation in acidity of the catalysts. Thermal stability and structural properties of the catalysts were studied by treating the catalyst at different calcination temperatures. The benzyl alcohol conversion and selectivity towards benzylated products were also dependent on the anisole to benzyl alcohol molar ratio, reaction temperature, and catalyst concentration/loading. To know the effect of the benzylating agent, the reaction was carried out using benzyl chloride, benzyl alcohol, and dibenzylether. The preferential order for conversion of the benzylating agent was observed as benzyl chloride > benzyl alcohol > dibenzylether. This study indicated that biomass derived activated carbon is suitable support to disperse Keggin type heteropoly acid for the benzylation reaction.

Full text of DOI:10.1016/j.apcata.2014.07.034

Accepted Manuscript
Title: Iron exchanged tungstophosphoric acid supported on
activated carbon derived from pinecone biomass: Evaluation
of catalysts efficiency for liquid phase benzylation of anisole
with benzyl alcohol
Author: Chowdari Ramesh Kumar N. Rambabu K.C. Maheria
A.K. Dalai N. Lingaiah
PII:
S0926-860X(14)00464-5
DOI:
Reference:
http://dx.doi.org/doi:10.1016/j.apcata.2014.07.034
APCATA 14927
To appear in:
Applied Catalysis A: General
Received date:
Revised date:
Accepted date:
15-10-2013
23-7-2014
28-7-2014
Please cite this article as: C.R. Kumar, N. Rambabu, K.C. Maheria, A.K. Dalai,
N. Lingaiah, Iron exchanged tungstophosphoric acid supported on activated carbon
derived from pinecone biomass: Evaluation of catalysts efficiency for liquid phase
benzylation of anisole with benzyl alcohol, Applied Catalysis A, General (2014),
http://dx.doi.org/10.1016/j.apcata.2014.07.034
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Iron exchanged tungstophosphoric acid supported on activated carbon derived from
pinecone biomass:
Evaluation of catalysts efficiency for liquid phase benzylation of anisole with benzyl alcohol
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Chowdari Ramesh Kumar1, 2, N. Rambabu1, K.C. Maheria1, 3, A.K. Dalai1*, and N. Lingaiah2
1Department of Chemical and Biological Engineering, University of Saskatchewan,
Saskatoon, SK–S7N 5A9, Canada
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2Catalysis Laboratory, Inorganic & Physical Chemistry Division, CSIR–Indian Institute of
Chemical Technology, Hyderabad–500 007, Telangana, India
3 Department of Applied Chemistry, S.V. National Institute of Technology,
Ichchhanath, Surat–395 007, Gujarat, India
Submitted for publication in:
Applied Catalysis A: General
*Corresponding author:
Dr. Ajay K. Dalai,
University of Saskatchewan
57 Campus Drive
Saskatoon, SK Canada S7N 5A9
Email: ajay.dalai@usask.ca
Phone No. (306) 966-4771
Fax No. (306) 966-4777
http://www.engr.usask.ca/~dalai
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Highlights
41 ꢀ Synthesized the Iron exchanged TPA supported on pinecone activated carbon catalysts.
42 ꢀ Investigated the optimum dosage of TPA–Fe loading for higher conversion.
43 ꢀ Evaluated the effects of activated carbon porous structure and acidity on benzylation
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reaction.
45 ꢀ Effective and optimum conditions were investigated for benzylation reaction.
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Abstract
A series of iron–exchanged heteropoly tungstate (TPA–Fe) supported on activated carbon
produced from pinecone biomass, have been investigated as catalysts for the benzylation
reaction. Catalysts were characterized by FT–IR, XRD, Laser Raman, BET surface area, and
ammonia TPD analysis. FT–IR, XRD, and Raman data revealed retention of the Keggin ion on
activated carbon–supported catalysts. The catalytic activity of these catalysts was evaluated for
liquid phase benzylation of anisole with benzyl alcohol. The catalytic activity was significantly
dependent on the dispersion of TPA–Fe on activated carbon. The effect of TPA–Fe loading on
activated carbon was studied ranging from 40 to 80 wt%. The catalyst with 70 wt% loading of
TPA–Fe showed higher benzylation activity, which is related to variation in acidity of the
catalysts. Thermal stability and structural properties of the catalysts were studied by treating the
catalyst at different calcination temperatures. The benzyl alcohol conversion and selectivity
towards benzylated products were also dependent on the anisole to benzyl alcohol molar ratio,
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reaction temperature, and catalyst concentration/loading. To know the effect of the benzylating
agent, the reaction was carried out using benzyl chloride, benzyl alcohol, and dibenzylether. The
preferential order for conversion of the benzylating agent was observed as benzyl chloride >
benzyl alcohol > dibenzylether. This study indicated that biomass derived activated carbon is
suitable support to disperse Keggin type heteropoly acid for the benzylation reaction.
Key words: Activated carbon, Benzylation, Heteropoly tungstate, Keggin ion, Pinecone
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1
Introduction
Alkylation of aromatic compounds is a very important reaction since diphenylmethane
and substituted diphenylmethane compounds are versatile chemical feedstocks for a wide range
of industrial products such as benzophenone, substituted benzophenone, 2–/4–
nitrodiphenylmethane, diamines of diphenylmethane and diphenylmethanes which are used as
monomers for poly carbonate resins, aromatic solvents, pharmaceuticals, dyes, perfumes [1].
Synthesis of these compounds frequently involves electrophilic aromatic substitution reactions.
The conventional acid catalysts like HCl, H2SO4, AlCl3, ZnCl2, and FeCl3 are required in
stoichiometric ratio to carry out such reactions [2]. The use of these catalysts leads to many
limitations concerning handling, safety, corrosion, and waste disposal. The development of
efficient methods for recovery and reuse of the catalysts is very important in chemistry. One
solution is to heterogenize the homogeneous catalysts by supporting them onto solid supports,
thus providing facile recovery from the reaction mixture and the possibility of reusing them.
Furthermore, Active components supported on a solid material, the surface area increases
effectively and subsequently enhance the reactivity of the catalysts.
Heteropoly acid (HPA) compounds are known to be active catalysts for many acid
catalyzed reactions. HPA compounds have attracted increasing interest due to their high acidity,
redox properties, pseudo–liquid behaviour, physico–chemical properties, and catalytic activity.
HPAs have very strong Brønsted acidity, approaching the super acid region, high stability, and
high proton mobility. The Hammett acidity (H0 = -13.2) of tungstophosphoric acid is much
stronger than 100% sulfuric acid (H0 = -11.94). Heteropoly compounds with a Keggin structure
are the most studied in the polyoxometalate class because they possess relatively high thermal
stability and high intrinsic acidity [3,4]. Among the Keggin type HPAs, tungstophosphoric acid
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(TPA) is the usual catalyst of choice because of its high acidic strength and relatively high
thermal stability. The main disadvantages of HPAs include their low surface area and high
solubility in polar solvents, especially in aqueous solutions [5]. HPAs can be made into
heterogeneous catalyst by exchanging their protons with metal ions such as Cs+ [6], Ag+ [7],
Sn4+/2+ [8,9], and Sm3+ [10] or by supporting them onto suitable supports like silica [11], zirconia
[12], niobia [13], titania [14], tin oxide [15], and zeolite [16]. Activated carbons are also
recommended for impregnation of heteropoly acids due to their high surface area (>1000 m2/g),
their ability to entrap certain amounts of heteropoly acid, and due to thermal stability in a wide
range of pH [17].
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Activated carbons with a high surface area and porous structure have attracted increasing
interest due to their novel catalytic applications. Agricultural and forest waste materials are
increasingly popular for use in lightweight hybrid materials/biocomposites, chemical and food
industries, as well as in the area of catalysis. Commercial activated carbons are generally
prepared from coal, wood, peat, and coconut shells [18]. The demand for novel and more
efficient, low–cost, and locally available renewable materials as alternative precursors in
activated carbon production has led researchers to use many agricultural and forest waste
materials such as fruit stones [19], pyrolyzed coffee residues [20], pine bark [21], nutshells [22]
and olive stones [23] as precursors for production of activated carbons. The pinecone is a
common biomass in North America and it can be converted into activated carbon using different
activation methods. Huge quantities of pine trees and cones are produced throughout the world,
especially in pine plantations for paper and pulp industries. Pinecones are generally discarded or
burned in winter for heat generation after seed collection. The utilization of seedless waste
pinecones is great potential for the production of value added products such as activated carbon.
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Chimienti et al. (2001) reported the impregnation of Keggin type TPA and STA on
carbon for the isopropanol dehydration reaction using up to 50% [24]. Their results indicated an
increase in catalyst activity with increased loading up to 30%. Timofeeva et al. (2004), used
filamentous type carbons as supports for Dawson and Keggin type tungstophosphoric acid and
tested the activity of the synthesized catalysts in a reaction of 2, 6–ditert–butyl–4–methylphenol
with toluene [25]. Their results showed that the activity of supported catalysts had increased due
to an increase in activity of surface protons of the catalysts. Degirmenci et al. (2011) used
activated carbon–supported silicotungstic acid and cesium salt of silicotungstic acid catalysts for
synthesis of ethyl–tert–butyl ether [26]. Park et al. (2012) reported the effect of coke–capture in
a Pd lattice on coking resistance in carbon–supported tungstophosphoric acid catalysts for
dehydration of glycerol into acrolein reaction [27]. To the best of our knowledge, the synthesis
of Fe–exchanged TPA supported on AC and the detailed characterization of these catalysts and
their application to benzylation reactions has not been studied.
The objective of the present work was the preparation of iron salt of tungstophosphoric
acid supported on activated carbon derived from pinecone biomass and the investigation of its
activity for liquid phase benzylation of anisole with benzyl alcohol. The effects of the
benzylating agent on benzylation of anisole and catalytic activity of the optimized catalyst
compared with the activity of tungstophosphoric acid supported on activated carbon were also
studied. Reaction parameters such as catalyst weight, reaction temperature, and molar ratio were
optimized.
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Materials and methods
The following analytical grade chemicals were used for catalyst preparation and
benzylation of anisole reaction: Iron nitrate (Sigma–Aldrich, Canada), 12–tungstophosphoric
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acid (Sigma–Aldrich, Canada), Benzyl alcohol (EM Science, Canada), dibenzylether and
phosphoric acid (Alfa–Aesar, Canada), 4–methoxydiphenylmethane (Matrix Scientific,
Columbia), Anisole (Alfa–Aesar, Canada). Ammonia balanced with helium, hydrogen, air, and
nitrogen gases were procured from Praxair Canada.
2.1
Production of activated carbon
Pinecone activated carbon was prepared according to the procedure available in the
literature [28]. Pinecones were collected from the University of Saskatchewan campus, Canada.
The cones were repeatedly washed with hot distilled water to remove adhering dirt and soluble
impurities and dried at overnight. The cleaned and dried pinecones were grounded and sieved to
particle size >350 µm for the production of activated carbon. Activated carbon was prepared in a
two–step process. In the first step, twenty grams of pinecone powder was impregnated with 60 g
of 85 wt% H3PO4 (weight ratio 1:3). The mixture was stirred and kept overnight in a 100 °C
oven. In the second step, H3PO4 impregnated pinecone material was placed in a fixed–bed
reactor and heated under inert atmosphere of nitrogen. Initially, the temperature was raised to
150 °C at a heating rate of 10 °C/min and maintained at this temperature for 1 h. Then, the
temperature was increased at the same ramping rate to reach the desired activation temperature
of 500 °C and maintained at the same temperature for 2 h. Thereafter, it was allowed to cool to
room temperature, followed by repeated washing with distilled water until it was free of any
residual phosphoric acid (up to pH 6.8–7.0), and the product was then dried at 110 °C for 24 h.
This product was denoted as activated carbon (AC).
2.2
Preparation of the iron salt of tungstophosphoric acid
The iron–exchanged 12–tungstophosphoric acid catalyst was prepared with a nominal
Fe3+:TPA ratio of 1:1. TPA was dissolved in distilled water and the calculated amount of
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Fe(NO3)3.9H2O was added to this solution and the resultant mixture was kept at 60 °C, with
continuous stirring. At this stage, the solid particles grew slowly in size and yellow colour
precipitates were obtained. The resultant mixture was stirred for 2 h and the excess water was
evaporated on a rotary evaporator. The dried catalyst was kept for further drying in hot air oven
and finally calcined at 300 ºC for 2 h. This catalyst was denoted as TPA–Fe.
2.3
Preparation of iron salt of tungstophosphoric acid supported on activated carbon
Synthesis of supported metal salt of tungstophosphoric acid prepared by the method
reported in the literature [29]. A series of AC–supported variants of TPA–Fe (40–80 wt%) were
prepared by the impregnation method with a nominal Fe3+:TPA ratio of 1:1. The typical
procedure for the preparation of 40 wt% H3PW12O40/Fe–AC catalyst is as follows: In a 100 ml
round bottom flask, 1.14 g of activated carbon (AC) was stirred in 10 ml of distilled water. 50
mg of Fe(NO3)3.9H2O was dissolved in distilled water and subsequently added drop–wise to the
activated carbon with vigorous stirring. The required amount of aqueous solution of TPA was
added drop–wise to give 40 wt% TPA–Fe on AC and the reaction mixture was stirred for a
further 2 h. The excess water was removed by rotary evaporator, followed by drying the obtained
powder overnight in a hot air oven at 100 ºC and then calcined at 300 ºC for 2 h under nitrogen
flow. The obtained catalyst is denoted as 40TF–AC. Similarly, 50–80 wt% loading of TPA–Fe
on activated carbon was prepared by varying TPA–Fe content. The obtained catalysts were
denoted as xTF–AC, where x represents the amount (wt%) of loading of TPA–Fe on activated
carbon.
TPA supported on activated carbon catalyst also has prepared by simple impregnation
method as described above without addition of Fe(NO3)3.9H2O and denoted this catalyst as 70T–
AC to compare the efficiency of 70TF-AC.
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2.4
Characterization
The Fourier transform infrared (FT–IR) spectra were recorded in the range of 400–4000
cm-1 wave numbers using 16 scans and a resolution of 4 cm-1 with a Perkin–Elmer Spectrum GX
instrument, using spectroscopic grade potassium bromide (KBr) pellets.
The Raman spectra of the prepared catalysts were recorded at room temperature in the
range of 100–2500 cm-1 using a Renishaw inVia Raman Microscope (Spectra–Physics model
163) equipped with a He/Ne laser operated at the laser diode wavelength of 785 nm. The laser
spot size was approximately 1 mm with a power of 10 mW. The catalyst samples in powder form
(about 5–10 mg) were spread loosely onto a glass slide below the microscope for Raman
measurements.
The total acidity of the catalysts was measured by temperature programmed desorption of
ammonia (TPD–NH3) using a Quantachrome Autosorb–iQ instrument. In a typical experiment,
0.1 g of catalyst was loaded and pretreated in helium gas at 300 ºC for 2 h, then cooled to room
temperature. The adsorption of NH3 was carried out by passing a mixture of 3% NH3 balanced
He gas over the catalyst for 2 h. The catalyst was flushed in helium gas at100 ºC for 2 h to flush
off the physisorbed NH3. The TPD analysis of the catalysts was carried out in a He gas flow (30
ml/min) with a temperature ramp of 10 ºC/min. The NH3 desorption was monitored using a
thermal conductivity detector (TCD).
BET surface area of the samples was measured with a Micromeritics ASAP 2000
instrument using low temperature N2 adsorption–desorption isotherms. Before measurement, the
samples were degassed in vacuum condition at 200 ºC. The surface area was computed from the
isotherms using the multi–point Brunauer–Emmett–Teller (BET) method based on the adsorption
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data in the partial pressure P/Po range from 0.01 to 0.2. The value of 0.1620 nm2 was taken for
the cross–section of the physically adsorbed N2 molecule.
The particle size distribution of different activated carbons was measured by laser
diffraction (Malvern Mastersizer S Long Bench Particle Size Analyzer, Malvern Instruments
Ltd., U.K.) using the wet feeder method. The 1000 mm lens (particle size range can be measured
4.2–3480 µm) and approximately 50 mg of sample were mixed with 100 ml of water in a sample
cell and analysis was performed at 2000 sweeps. The average particle size distribution was
determined from 3 replicates of each sample. The polydispersity of the powder was expressed by
the span value using following equation.
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D[v,0.9]− D[v,0.1]
Span =
D[v,0.5]
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Where D(v,0.9), D(v,0.1), and D(v,0.5) are the equivalent volume diameters at 90, 10 and
50% cumulative volume, respectively. The particle size of the primary powders was described by
the volume mean diameter (VMD).
2.5
Benzylation reaction procedure
The alkylation reaction was performed in a 50 ml two–necked round bottom flask
provided with a reflux condenser and nitrogen inlet. In a typical run, anisole (10 g) and benzyl
alcohol (3.37 g), and catalyst (0.1 g) were placed in a flask. The reactions were performed in the
temperature range of 80–140 ºC and the reaction mixture was withdrawn at different intervals
and then analyzed by a gas chromatography (Agilent–7890A) equipped with a stabilwax column
(30 m × 0.25 mm × 0.5 µm) and flame ionization detector (Injector temperature 280 °C, detector
temperature 280 °C and column temperature range was 80–240 °C at a heating rate of 20 °C/min
by holding at 80 °C for 4 min. and carrier gas (He) flow rate was 2.2 mL min-1). The products
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were identified using the retention times of the corresponding standard sample and confirmed by
GC–MS (SHIMADZU–2010) analysis.
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Results and discussion
3.1
FT–IR spectral analysis
Figure 1 shows the FT–IR spectra of TF–AC catalysts. The characteristic bands of the
heteropoly anion were observed in the finger print region (700–1100 cm−1), indicating that the
Keggin structure of PW12O403- was maintained. The characteristic bands of PW12O403- appearing
at 1081, 962, 910, and 796.5 cm-1 correspond to νas (P–O), νas (W–Ot), νas(W–Oc–W), and νas(W–
Oe–W) vibrations, respectively [15]. In the activated carbon–supported TPA–Fe catalysts, some
of the characteristic Keggin bands were also observed and other bands merged with the bands
corresponding to AC. In the case of catalysts prepared with lower TPA–Fe loadings, absorption
bands at about 3550 and 1620 cm-1 were assigned to the stretching and bending vibrations of the
O–H bond, respectively. From the FT–IR patterns also noticed that with an increase in TPA–Fe
loading on AC, intensity of the characteristic peak of Keggin ion was also increased. FT–IR
patterns of TF–AC catalysts confirmed the presence of Keggin ion in all catalysts. The spent
catalyst (70TF-AC used) was analyzed by FT-IR to determine the stability of heteropoly acid
after the reaction. The FT–IR spectrum of the spent catalyst Figure 1(i) clearly shows the
characteristic bands of Keggin ion indicating that the TPA–Fe remains as in case of fresh catalyst
and was not affected during the reaction. Retention of the Keggin ion structure on AC–supported
catalysts was further confirmed by Laser Raman and XRD techniques.
3.2
Laser Raman spectroscopy
Figure 2 shows the Laser Raman spectra of pure TPA, TPA–Fe and AC–supported TPA–
Fe catalysts. Pure crystalline TPA showed peaks at 1010, 990, 893, 528, 234, and 216 cm-1
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related to characteristic peaks of Keggin ion [10,30,31]. TPA–Fe showed a band at 1004 cm-1
corresponding to asymmetric vibration of W=Ot bond [8]. The Raman bands at 903 and 535 cm-1
ascribed to asymmetric stretching vibration of W–Oc–W (Oc–corner sharing bridging oxygen
atom) and symmetric stretching vibrations of W–Oe–W (Oe–edge sharing bridging oxygen
atom), respectively [30,31]. The band observed at 231 cm-1 corresponds to W–O–W bending
mode of vibrations, which might be due to the coupling between symmetric stretching mode of
W, four co–ordinated oxygen, and the bending mode of W–O–W vibrations [32]. These results
indicate that the primary structure of the Keggin ion is maintained after exchanging the protons
with Fe3+. Activated carbon showed two strong bands at 1330 and 1595 cm-1 (Figure 2a) related
to the D– and G– bands, respectively [33]. These two bands were observed in all activated
carbon–supported TPA–Fe catalysts. The sharp Keggin ion band (1004 cm-1) was observed from
60 wt% loading of TPA–Fe on activated carbon (Figure 2d). No sharp Keggin bands were
observed at less than 60 wt% TPA–Fe loading on AC, which might be due to the incorporation
of TPA–Fe into the pores of AC because of its high surface area (Table 1). The most intense
bands are those related to AC. Intensity of the Keggin ion band (1004 cm-1) also increased with
an increase in TPA–Fe loading from 60 to 80%. Figure 2 shows that the D–band corresponding
to AC is shifted to higher wave number in all the catalysts, indicating the strong interaction of
TPA–Fe with AC. These results indicate that the Keggin ion structure of TPA–Fe was
maintained even after supporting onto AC.
3.3
XRD patterns
The existence of Keggin ion was further confirmed by X–ray diffraction technique. XRD
pattern of the AC (a), 70TF–AC (b), TPA–Fe (c) and TPA (d), are shown in Figure 3. AC
showed two broad peaks centered at 2θ of 23.8° and 29.8°, corresponding to the graphitic basal
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plane. In the case of iron salt of TPA (TPA–Fe), the characteristic peaks related to Keggin ion
were shown at 2θ of 10.5°, 14.7°, 18.1°, 21°, 23.4°, 25.7°, 29.8°, 35.2° and 38.3° which
confirmed that the presence of Keggin ion in Fe exchanged TPA (TPA–Fe) catalyst [34,35]. The
presence of Keggin ions clearly shown in (>60%) of TPA-Fe on activated carbon in FT-IR and
Raman analysis results. In order to further confirm the presence of Keggin ion structure on
activated carbon supported catalysts, XRD analysis has been performed only for the 70TF-AC
catalyst because it was found to be the most active catalyst with maximum conversion. The
presence of characteristic peaks of the Keggin ion was observed in the 70TF–AC catalyst,
indicating that the Keggin ion structure of TPA–Fe is still maintained even after being supported
on activated carbon.
3.4
BET Surface area and particle size measurements
The textural properties such as surface area, pore size, and pore volume are presented in
Table 1. AC showed a high surface area of 838.4 m2/g, whereas pure TPA–Fe showed a surface
area of 1.8 m2/g. As the TPA loading increases surface area, pore diameter and pore volume all
strongly decreases relative to the support, AC. It was observed that with increased loading of
TPA–Fe onto AC from 40 to 80 wt%, the surface area of the catalysts was decreased. The reason
being, as the TPA–Fe loading increases on AC, TPA–Fe species enters the pores of AC it
decrease the pore diameter, and the average pore volume as well as the surface area.
Typical laser diffraction technique (LDT) volume–based particle diameter distributions
curves are illustrated in Figure 4. All the distribution curves have a traditional bell shape and
distribution of particles sizes depended on TPA–Fe loading on AC. From Figure 4, particles sizes
were distributed in a wide range (10–900 µm) for AC. On the other hand bulk TPA–Fe, particle
sizes are in the range of 1–50 µm. When 40 wt% of TPA–Fe impregnated on AC, the particle
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size range of the catalyst was decreased to 8–300 µm (Figure 4b). Similar trend was observed for
the catalysts with higher loadings of TPA–Fe and the particle size distribution range is
decreasing towards lower values. The average particle size of all the powder samples was
calculated in terms of span value, as discussed in the section 2.4 and span values are presented in
Table 1. Span value for AC is 4.52, which is decreased upon loading of TPA–Fe. Catalyst with
60 and 70 wt% of TPA–Fe possesses high span values compared to other supported catalysts,
this is due to wide range particle distribution compared to other catalysts (Figure 4). The bulk
TPA–Fe also possesses high span value (4.72). However the particle size of TPA–Fe catalyst
was distributed in the range of 1–50 µm only (Figure 4).
3.5
TPD of ammonia analysis
Ammonia TPD profiles are shown in Figure 5. All AC–supported TPA–Fe catalysts
showed broad ammonia desorption peaks in the range of 200–400 ºC, but activated carbon
showed a small desorption peak at 220 ºC, due to the low acidity of AC compared to other
catalysts. When iron salt of TPA were supported onto AC, the desorption peaks shifted to higher
temperatures. In the case of the 40 wt% TPA–Fe catalyst, the desorption peak shifted to 290 ºC
(Figure 5b). With increased TPA–Fe loading on AC, intensity of the desorption peak also
increased. Compared to other catalysts, the 70TF–AC catalyst showed a broad desorption peak
and with a further increase in TPA–Fe loading, the desorption peak shifted to lower temperatures
(Figure 5f). Among these, 70TF–AC catalyst was found to possess strong surface acidity
strength.
3.6
Catalyst efficiency for benzylation of anisole
Both surface area and acidity of the catalysts are important for benzylation reactions.
Figure 6 shows the catalytic activities of TF–AC samples for benzylation of anisole with benzyl
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alcohol. The activated carbon support and TPA–Fe individually showed very low activity for the
benzylation of anisole. Conversion of benzyl alcohol in the case of AC and TPA–Fe catalysts
was 2.7 and 2.5%, respectively. The low catalytic activity of the TPA–Fe might be due to the
low surface area of the TPA–Fe catalyst and the Fe3+ sites caged by microcrystallite Keggin units
of heteropoly tungstate, resulting in less availability of acidic sites for reactant molecules. Since,
TPA exhibits different packing arrangements as the hydration water is lost [36]. Pore size and
acidity of the heteropoly acid salt can be precisely controlled by the cation content [37]. As
shown in Figure 4, TPA–Fe particle sizes are in the range of 1–50 µm and average pore
diameter, pore volumes of the bulk TPA–Fe is very low compared to TPA–Fe supported on AC
(Table 1). Since, the particle size, pore structure and surface area are the elements of the tertiary
structure and the tertiary structure is the assembly of secondary structure (which is three
dimensional structure of counter ions and Keggin ion) of heteropoly acid [38]. Due to the small
pore structure for TPA–Fe, the benzyl alcohol might have not been diffused through the pores.
Similar type of diffusion limitations of benzyl alcohol were observed for the catalysts with
microporous network (zeolites) and poor performance was reported for benzylation reaction [39–
41].
Although AC possess high pore volume and pore diameter, the catalytic activity was low
this is because of the low acidity of the AC, as it showed a small desorption peak in the TPD
profile (Figure 5a). However, in the case of supported catalysts, the pore diameter and pore
volumes are higher than that of TPA–Fe results in drastic improvement for benzylation reaction.
For the TF–AC catalysts, the alkylation activity increased as a function of active component
(TPA–Fe) loading on AC. With an increase in the TPA–Fe loading from 40 to 70 wt%,
conversion of benzyl alcohol also has increased from 24.5 to 98%. Higher benzyl alcohol
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conversion of 98% was observed when 70TF–AC catalyst was used. This might be due to the
high surface area of 70TF–AC compared to TPA–Fe and monolayer coverage of the active
component (TPA–Fe) on AC might be achieved at 70 wt% loading. A further increase in TPA–
Fe loading (80 wt%) leads to agglomeration of the active component (BET surface area Table 1),
which results in low catalytic activity. The conversion of benzyl alcohol in the case of 80TF–AC
catalyst was only 65.3%. Results of the TPD of ammonia analysis also agreed with the observed
catalytic activity. The catalyst with 70 wt% TPA–Fe on AC showed strong and broad desorption
peaks at higher temperatures compared to other catalysts (Figure 5). The 80TF–AC catalyst
desorption peak shifted to a lower temperature compared to the 70TF–AC catalyst. BET surface
area analysis results also supported that the 80 wt% loading catalyst had a low surface area
(Table 1). Results of the benzylation activity and selectivity towards benzylated product were
correlated with the acidity of the catalysts. Catalytic activity and selectivity towards the
benzylated product also increased with TPA–Fe loading and attained maximum at 70 wt%
loading. A further increase in loading the selectivity of by–product dibenzyl ether also increased.
Thermal stability and structural changes of the most active catalyst (70TF–AC) were
studied by treating the sample at different calcination temperatures ranging from 400–750 ºC
under nitrogen flow. The catalytic activity of the catalysts was evaluated for benzylation of
anisole with benzyl alcohol.
3.7
Characterization of 70TF–AC catalyst calcined at different temperatures
3.7.1 Effect of calcination temperature
Figure 7 shows the catalytic activity of 70TF–AC calcined at different temperatures
(400–750 ºC). The catalyst calcined at 300 ºC exhibited higher benzyl alcohol conversion
compared to the catalyst calcined at temperatures beyond 300 ºC. With an increase in the
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calcination temperature from 300 to 600 °C, conversion of the benzyl alcohol was decreased
from 98% to 1%. There was no conversion of benzyl alcohol for the catalyst calcined at 750 °C.
In addition, selectivity towards benzylated product was also decreased. This might be due to
decomposition of the Keggin units of heteropoly tungstate and/or a loss in synergy between the
support and active component at higher temperatures. FT–IR, Raman, and TPD characterization
techniques were employed for these catalysts to gain insight of the mechanism involved in the
catalytic reactions.
3.7.2 FT–IR spectroscopy
Figure 8 shows the FT–IR spectra of 70TF–AC calcined at different temperatures
between 300–750 ºC. The catalysts calcined at 300 and 400 ºC exhibited peaks owing to the
Keggin ion. The catalyst calcined at 500 ºC showed sharper and more intense peaks than the
catalyst calcined at lower temperatures, which might be due to a decrease in the interaction
between activated carbon and metal salt of heteropoly tungstate to give aggregates of iron
exchange TPA. When calcination temperature was increased to 600 and 750 ºC, the
characteristic bands of the Keggin ion were disappeared, which was attributed to decomposition
of the Keggin ion into its constituent metal oxides at higher temperatures [15].
3.7.3 Raman analysis
Figure 9 shows the Laser Raman spectra of the 70TF–AC catalyst calcined at 300–750
ºC. All the catalysts showed characteristic D– and G– bands related to carbon. The catalyst
calcined at 300 and 400 ºC showed characteristic bands related to the Keggin ion at 1004 cm-1,
owing to the asymmetric stretching frequency of the W=Ot bond [15], indicating retention of the
primary Keggin ion structure at these temperatures. The catalyst calcined at 500 ºC showed
bands at 270 cm-1 ascribed to the bending mode of vibration and another broad band at 783 cm-1
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412
that corresponds to W–O–W stretching mode vibrations of tungsten oxide [42]. A weak band
observed at 1004 cm-1 corresponds to the W=Ot asymmetric vibration of heteropoly tungstate.
These results suggest that the Keggin ion of heteropoly tungstate decomposition began at the
calcination temperature of 500 ºC. For the catalyst calcined at 600 and 750 ºC, the Keggin ion
bands were diminished and showed only bands related to WO3 activated carbon (Figure 8d&e).
The Raman spectroscopy results suggest that the 70TF–AC catalyst was thermally stable upto
400 ºC. Thereafter, decomposition was observed beyond 500 ºC.
3.7.4 TPD of ammonia
The effect of calcination temperature on benzylation of anisole was studied as a function
of acidity. Figure 10 shows ammonia TPD profiles of 70TF–AC catalyst calcined at various
temperatures, ranging from 300–600 ºC. With an increase in the calcination temperature from
300 to 600 ºC, the intensity of the desorption peak in the range of 200–400 ºC was decreased and
shifted to lower temperatures. The catalyst calcined at a lower temperature (300 ºC) showed a
broader and more intense desorption peak than catalysts calcined at higher temperatures. The
catalyst calcined at 600 ºC showed a narrow desorption peak and very low catalytic activity
(Figure 6). This might be due to decomposition of the Keggin ion of heteropoly tungstate into its
constituent metal oxides at higher temperatures.
The decrease in benzylation activity with an increase in the catalyst (70TF–AC)
calcination temperature can be explained on the basis of results obtained from the FT–IR, Raman
and ammonia TPD. From the FT–IR and Raman results it was concluded that Keggin ion of the
TPA–Fe was stable upto 500 °C. However, a drastic change was observed in the TPD profiles of
70TF–AC catalyst calcined in the range of 300–500 °C. This was due to partial degradation of
Keggin ion and loss in synergy between the support and active component with increase in
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435
calcination temperature from 300 to 500 °C. Therefore decrease in benzyl alcohol conversion
with an increase in catalyst calcination temperature can be correlated with the acidity of the
catalysts. Benzyl alcohol conversion depends on acidity of the catalyst which in turn is
proportional to the presence of Keggin ion structure. Conversion of benzyl alcohol was only 1%
in the case of catalyst calcined at 600 °C and there was no conversion of benzyl alcohol for the
catalyst calcined at 750 °C this was due to complete decomposition of Keggin ion. High benzyl
alcohol conversion in the case of 70TF–AC (calcined at 300 °C) catalyst was due to synergistic
effect between TPF–Fe and activated carbon, and high acidity.
3.8
Optimization of reaction parameters
Reaction parameters such as catalyst weight, reaction temperature, and molar ratio were
studied in order to get optimum conversion of benzyl alcohol and high selectivity towards
benzylated products.
3.8.1 Effect of catalyst weight
To optimize the reaction parameters, the benzylation of anisole was carried out by taking
various amounts of catalyst, ranging from 0.05–0.2 g, as shown in Table 2. It was observed that
with an increase in catalyst weight from 0.05 g to 0.1 g, the conversion of benzyl alcohol
increased from 55 to 98% and with a further increase in catalyst weight to 0.15 and 0.2 g, the
conversion of benzyl alcohol reached 99.5%. Maximum conversion of benzyl alcohol conversion
was observed with catalyst loading of 0.1 g, but selectivity of the products varied with increased
catalyst weight. With catalyst loading of 0.05 g, the selectivity ratio of o- to p- benzylated
products was observed in the ratio of 31:35 and 34% of the by–product dibenzylether was
observed. Whereas, with 0.2 g of catalyst loading, the o-:p- ratio was 48:50 and only 2% of
dibenzylether was found.
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458
3.8.2 Effect of molar ratio
The effect of anisole to benzyl alcohol molar ratio was studied by varying the anisole to
benzyl alcohol molar ratio, and the results are presented in Table 3. Conversion of benzyl alcohol
was 97% at a 15:1 anisole to benzyl alcohol molar ratio. When anisole to benzyl alcohol molar
ratio was increased to 15:5, no significant benzyl alcohol conversion was observed; whereas, at a
15:10 molar ratio, conversion of benzyl alcohol decreased. It was also observed that with an
increase in benzyl alcohol concentration, selectivity towards benzylated products was decreased
and the formation of by–product increased due to the dehydration reaction [43]. At higher
concentrations of benzyl alcohol, more benzyl alcohol molecules were available, which resulted
in the formation of dibenzylether.
3.8.3 Effect of reaction temperature
Table 4 shows the effect of reaction temperature on benzylation of anisole with benzyl
alcohol. When the reaction temperature was maintained at 80 ºC, the conversion of benzyl
alcohol was only 2%. With an increase in the reaction temperature from 80 to 100, 120, and 140
ºC the conversion of benzyl alcohol increased from 2 to 18, 50, and 100%, respectively.
Selectivity towards benzylated products also followed the same trend, with an increase in
reaction temperature, the yield of benzylated products also increased. When the reaction was
carried out at 80 ºC, the selectivity of dibenzylether was 53% and for reactions carried out at 100
and 120 ºC, the selectivity was 40 and 36%, respectively. At 140 ºC, no formation of by–
products (dibenzylether) was observed, indicating that 140 ºC is the optimum reaction
temperature for this reaction.
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481
3.9
Effect of Fe
To investigate the effect of iron salt of TPA, catalytic activity of 70TF–AC was
compared with 70T–AC (TPA supported on activated carbon without Fe), and the results are
presented in Table 5. The 70TF–AC catalyst showed 98% of benzyl alcohol conversion with
selectivity of 40:38 (o-:p-). 70TAC showed only 51% of benzyl alcohol conversion and
selectivity towards benzylated products, o- and p- were 38 and 33%, respectively under the same
experimental conditions. These results confirmed that the iron salt of TPA supported on AC was
more active compared to parent TPA supported on AC. This might be due to the generation of
Lewis acidic sites (Fe3+ ions), leading to an increase in total acidity of the 70TF–AC catalyst.
3.10 Effect of benzylating agent
The effect of benzylating agents such as benzyl alcohol, benzyl chloride, and
dibenzylether were studied on benzylation of anisole. Scheme 1 shows the benzylation of anisole
with different benzylating agents such as benzyl alcohol, dibenzyl ether, and benzylchloride. To
know the effect of the benzylating agent, a 15:5 molar ratio of anisole to benzylating agent
(benzyl alcohol or benzyl chloride) was used. To compare the benzyl alcohol and dibenzylether
conversion, the amount of dibenzylether was half the moles of benzyl alcohol used in the
benzylation of anisole with the benzyl alcohol reaction. Table 6 shows the experimental results
of benzylation of anisole with different benzylating agents. When dibenzylether was used as
benzylating agent, 40% conversion was observed at a reaction time of 2.5 h. The selectivity of o-
and p- benzylated products were 20 and 18%, respectively and 2% of benzyl alcohol was
obtained as a by–product. Whereas, in the case of benzyl alcohol as the benzylating agent, 98%
of benzyl alcohol conversion was observed at 2.5 h of reaction time and selectivity of o- and p-
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503
benzylated products were found to be 39 and 38%, respectively. The by–product dibenzylether
was also observed with a selectivity of 21%. In the case of benzyl chloride, 100% conversion
was achieved within 30 min of reaction time.
It is observed that, benzyl chloride is more active as compared to benzyl alcohol in the
benzylation of anisole reaction. This is because of the –Cl group, which makes benzyl chloride
more reactive than the benzyl alcohol. The major disadvantage of using benzyl chloride as a
benzylating agent is that it produces HCl as a by–product. At 2.5 h of reaction time, less
conversion of dibenzylether was observed as compared to benzyl alcohol, which might be due to
easier adsorption of benzyl alcohol molecules on the catalyst surface than the dibenzylether
molecules, as shown in the reaction mechanism (Figure 11). Conversion of the benzylating
agents were found in the order of benzyl chloride > benzyl alcohol > dibenzylether.
3.11 Leaching test of the catalyst
To know the TPA–Fe leaching from the activated carbon support, the benzylation of
anisole reaction was carried out and after completion of the reaction where the conversion of
benzyl alcohol was 100%, the catalyst was separated from the reaction mixture by centrifugation.
A calculated amount of benzyl alcohol was added to the filtrate (reaction mixture) and the
reaction was carried out (without addition of catalyst) to check if there was any leaching of the
active component (TPA–Fe) from the support into reaction mixture. The reaction was continued
for a period of 4 h. There was no benzyl alcohol conversion, indicating that there was no
leaching of the active component during the reaction and that the reaction took place on the
catalyst surface.
4
Conclusions
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526
Iron exchanged TPA supported on pinecone activated carbon catalysts were prepared
with retention of the Keggin ion structure of TPA–Fe. Pure TPA–Fe catalyst did not show
considerable activity, whereas supporting the TPA–Fe on activated carbon increased the catalytic
activity. Benzylation of anisole activity depended on the loading amount of TPA–Fe on activated
carbon (AC). With increased TPA–Fe loading on AC, catalytic activity for benzylation anisole
was increased and achieved maximum conversion (98%) of benzyl alcohol for 70 wt% loading
calcined at 300 °C. Benzylation activity of anisole also depended on the surface area, acid
strength distribution, and total acidity of the catalysts related to the content of TPA–Fe on AC.
The role of Fe was studied by comparing the activity of the 70TF–AC catalyst with the 70T–AC
(catalyst without Fe). Higher benzylation activity was observed for the 70TF–AC than the one
without Fe. The effect of the benzylating agent was studied by using benzyl chloride, benzyl
alcohol, and dibenzylether, with the preferential order for activity as benzyl chloride > benzyl
alcohol > dibenzylether. The effect of reaction parameters such as reaction temperature, catalyst
weight, and anisole to benzyl alcohol molar ratio were also studied for benzylation of anisole.
The catalyst was found stable throughout, with no leaching of active content (TPA–Fe) from the
AC support.
Acknowledgements
The authors greatly acknowledge the Canadian Bureau for International Education
(CBIE) and Canadian Commonwealth Scholarship Program–2012 for financial assistance for
facilitating this research.
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References
[1] Olah, GA: Friedel-Crafts Chemistry. Wiley, New York, 1973.
[2] A. Schriesheim, Friedel–Crafts and Related Reactions, ed. G.A. Olah, Interscience, London,
1964, vol. II, Part I, p. 447–495.
[3] R.S. Drago, J.A. Dias, T.O. Maier, J. Am. Chem. Soc. 119 (1997) 7702–7710.
[4] J.A. Dias, S.C.L. Dias, N.E. Kob, J. Chem. Soc. Dalton Trans. 3 (2001) 228–231.
[5] G.A. Tsigdinos, Top. Curr. Chem. 76 (1978) 1–64.
[6] J.S. Santos, J.A. Dias, S.C.L. Dias, F.A.C. Garcia, J.L. Macedo, F.S.G. Sousa, L.S. Almeida,
Appl. Catal., A 394 (2011) 138–148.
[7] K.T. Venkateswara Rao, P.S. Sai Prasad, N. Lingaiah, Green Chem. 14 (2012) 1507–1514.
[8] Ch. Ramesh Kumar, K.T. Venkateswara Rao, P.S. Sai Prasad, N. Lingaiah, J. Mol. Catal., A
337 (2011)17–24.
[9] K. Shimizu, K. Niimi, A. Satsuma, Appl. Catal., A 349 (2008) 1–5.
[10] Ch. Ramesh Kumar, K. Jagadeeswaraiah, P.S. Sai Prasad, N. Lingaiah, ChemCatChem 4
(2012) 1360–1367.
[11] A. Jha, A.C. Garade, S.P. Mirajkar, C.V. Rode, Ind. Eng. Chem. Res. 51 (2012) 3916–3922.
[12] F. Su, L. Ma, Y. Guo, W. Li, Catal. Sci. Technol. 2 (2012) 2367–2374.
[13] K. Srilatha, N. Lingaiah, B.L.A. Prabhavathi Devi, R.B.N. Prasad, S. Venkateswar, P.S. Sai
Prasad, Appl. Catal., A 365 (2009) 28–33.
[14] Ch. Ramesh Kumar, P.S. Sai Prasad, N. Lingaiah, J. Mol. Catal., A 350 (2011) 83–90.
[15] Ch. Ramesh Kumar, P.S. Sai Prasad, N . Lingaiah, Appl. Catal., A 384 (2010) 101–106.
24
Page 24 of 47

550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
[16] G. Bai, T. Li, Y. Yang, H. Zhang, X. Lan, F. Li, J. Han, Z. Ma, Q. Chen, G. Chen, Catal.
Commun. 29 (2012) 114–117.
[17] Y. Izumi, R. Hasebe, K. Urabe. J. Catal. 84(2) (1983) 402–409.
[18] I. Salame, T. Bandosz, J. Colloid Interface Sci. 240 (2001) 252–258.
[19] D.J. Malik, V. Strelko Jr., M. Streat, A.M. Puziy, Water Res. 36 (2002) 1527–1538.
[20] V. Boonamnuayvitaya, C. Chaiya, W. Tanthapanichakoon, S. Jarudilokkul, Sep. Purif.
Technol. 35 (2004) 11–22.
[21] L.A.T. Vasconcelos, C.G.G. Beca, Eur. Water Poll. Control 4 (1994) 41–51.
[22]M. Ahmedna, W.E. Marshall, A.A. Husseiny, R.M. Rao, I. Goktepe, Water Res.38 (2004)
1062–1068.
[23] A.H.E. Sheikh, A.P. Newman, H.K.A. Daffaee, S. Phull, N. Cresswell, J. Anal. Appl. Pyrol.
71(2004) 151–164.
[24] M.E. Chimienti, L.R. Pizzio, C.V. Caceres, M.N. Blanco, Appl. Catal., A 208 (2001) 7–19.
[25] M.N. Timofeeva, M.M. Matrasova, T.V. Reshetenko, L.B. Avdeeva, A.A. Budneva, A.B.
Ayupov, E.A. Paukshtis, A.L. Chuvilin, A.V. Volodin, V.A. Likholobov, J. Mol. Catal., A
211 (2004) 131–137.
[26] L. Degirmenci, N. Oktar, G. Dogu, AIChE Journal 57 (2011) 3171–3181.
[27] D.S. Park, B.K. Kwak, N.D. Kim, J.R. Park, J.H. Cho, S. Oh, J. Yi, ChemCatChem 4 (2012)
836–843.
[28] M. Momcilovic, M. Purenovic, A. Bojic, A. Zarubica, M. Randelovic, Desalination 276
(2011) 53–59.
[29] A.M. Alsalme, P.V. Wiper, Y.Z. Khimyak, E.F. Kozhevnikova, I.V. Kozhevnikov, J. Catal.
276 (2010) 181–189.
25
Page 25 of 47

573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
[30] K. Mohan Reddy, N. Seshu Babu, P.S. Sai Prasad, N. Lingaiah, Catal. Commun. 9 (2008)
2525–2531
[31] E. Caliman, J.A. Dias, S.C.L. Dias, F.A.C. Garcia, J.L. Macedo, L.S. Almeida, Microporo.
Mesopor. Mater. 132 (2010) 103–111.
[32] T. Takashima, R. Nakamura, K. Hshimoto, J. Phys. Chem. C. 113 (2009) 17247–17253.
[33] X. Li, J. Yang, Y. Hu, J. Wang, Y. Li, M. Cai, R. Li, X. Sun, J. Mater. Chem. 22 (2012)
18847–18853.
[34] K. Jagadeeswaraiah, Ch. Ramesh Kumar, P.S. Sai Prasad, N. Lingaiah, Catal. Sci. Technol.
(DOI: 10.1039/C4CY00253A)
[35] Chowdari Ramesh Kumar, N. Rambabu, N. Lingaiah, P.S. Sai Prasad, A.K. Dalai, Appl.
Catal., A 471 (2014) 1–11.
[36] I.V. Kozhevnikov, Catalysts for Fine Chemical Synthesis: Catalysis by Polyoxometalates,
Vol. 2, John Wiley & Sons Inc. 2002.
[37] T. Okuhara, Appl. Catal., A 256 (2003) 213–224.
[38] N. Mizuno, M. Misono, M. Chem. Rev. 98 (1998) 199–218.
[39] B. Coq, V. Gourves, F. Figueras, Appl. Catal., A 100 (1993) 69–75.
[40] V.R. Choudhary, S.K. Jana, B.P. Kiran, Catal. Lett. 59 (1999) 217–219.
[41] V.D. Chaube, Catal. Commun. 5 (2004) 321–326.
[42] A. Mirgorodsky, M. Colas, M. Smirnov, T.M. Mejean, R.E. Mallawany, P. Thomas, J.
Solid State Chem. 190 (2012) 45–51.
[43] A.B. Deshpande, A.R. Bajpai, S.D. Samant, Appl. Catal., A 209 (2001) 229–235.
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595
Table 1 Textural properties of TF–AC catalysts.
Avg.
pore
diameter
(Å)
BET
*Particle
size span
value
Pore
Particle volume mean diameter (µm)
surface
area
volume
Catalyst
(cm3/g)
D[v,0.1]
D[v,0.5]
D[v,0.9]
(m2/g)
AC
38.8
36.7
34.4
30.9
30.6
26.6
17.8
0.7210
0.3042
0.2214
0.1547
0.0623
0.0335
0.0035
838.4
313.6
241.3
200.1
81.4
23.09
16.30
16.42
19.24
4.80
90.08
52.81
47.19
67.83
49.85
36.16
3.61
430.54
171.66
113.41
223.54
219.66
102.28
17.31
4.52
2.94
2.06
3.01
4.31
2.69
4.72
40TF–AC
50 TF–AC
60 TF–AC
70 TF–AC
80 TF–AC
TPA–Fe
49.8
4.93
1.8
0.29
596
597
598
599
600
*Particle size span values calculated by using laser diffraction technique.
27
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600
601
602
603
604
605
606
607
608
Table 2 Effect of catalyst concentration on conversion of benzyl alcohol.
Product selectivity (%)
Catalyst
Conversion of
weight (g) benzyl alcohol (%)
o-
p-
Ether
34.0
21.5
8.3
0.05
0.10
0.15
0.20
55.3
98.0
99.5
99.4
31.0
38.4
45.3
48.0
35.0
40.1
46.5
50.0
2.0
609
610
611
Reaction conditions: Anisole 10 g, Benzyl alcohol 3.37 g, Catalyst calcination temperature 300
ºC, Reaction temperature 120 ºC, Reaction time 2.5 h.
612
613
614
615
616
617
618
619
620
621
622
623
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624
625
626
627
628
629
630
631
632
Table 3 Effect of molar ratio on conversion of benzyl alcohol.
Anisole to
benzyl alcohol
molar ratio
Product selectivity (%)
Conversion of
benzyl alcohol (%)
o-
p-
Ether
4.8
15:1
15:5
96.8
98.0
90.2
46.7
38.4
28.2
48.5
40.1
31.2
21.5
40.6
15:10
633
634
635
Reaction conditions: Catalyst calcination temperature 300 ºC, Catalyst loading 0.1 g, Reaction
temperature 120 ºC, and Reaction time 2.5 h.
636
637
638
639
640
641
642
643
644
645
646
647
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