Liquid-phase veratrole acylation and toluene alkylation over WO x/ZrO2 solid acid catalysts

Article abstract of DOI:10.1016/j.molcata.2005.11.029

The liquid-phase acylation of veratrole with acetic anhydride and alkylation of toluene with 1-dodecene were carried out over WO _x/ZrO₂ solid acid catalysts. The catalysts were prepared by wet impregnation method using zirconium oxyh

Full text of DOI:10.1016/j.molcata.2005.11.029

Journal of Molecular Catalysis A: Chemical 247 (2006) 58–64
Liquid-phase veratrole acylation and toluene alkylation over
WOx/ZrO2 solid acid catalysts
Ankur Bordoloi, Nevin T. Mathew, Biju M. Devassy,
S.P. Mirajkar, S.B. Halligudi∗
Inorganic Chemistry and Catalysis Division, National Chemical Laboratory, Pune 411008, India
Received 29 September 2005; received in revised form 14 November 2005; accepted 16 November 2005
Available online 22 December 2005
Abstract
The liquid-phase acylation of veratrole with acetic anhydride and alkylation of toluene with 1-dodecene were carried out over WOx/ZrO2 solid
acid catalysts. The catalysts were prepared by wet impregnation method using zirconium oxyhydroxide and ammonium metatungstate. Catalysts
with different WO3 loading (5–30 wt.%) were prepared and calcined at 800 ◦C and catalyst with 15% WO3 was calcined from 650 to 850 ◦C. All
the catalysts were characterized by nitrogen adsorption, XRD and NH3-TPD. The catalyst with 15% WO3 calcined at 800 ◦C (15 WZ-800) was
found to be the most active in acylation and alkylation reactions. The effect of temperature, molar ratio and catalyst weight on the conversions of
acetic anhydride and dodecene were studied in detail. The catalyst 15 WZ-800 gave 67% acetic anhydride conversion in veratrole acylation under
the reaction conditions of 70 ◦C, veratrole/acetic anhydride molar ratio 2, time 4 h and 99% dodecene conversion with >99% monododecyl toluene
selectivity at 100 ◦C, toluene/1-dodecene molar ratio 10 and time 1 h.
© 2005 Elsevier B.V. All rights reserved.
Keywords: Zirconia-supported tungsten oxide; Veratrole; Acylation; Toluene; Alkylation
1. Introduction
is long felt need and demand for replacement of conventional
¨
Lewis and Bronsted acids with easily recyclable and regenera-
Friedel–Craft acylation of aromatic compounds have gener-
ated continued interest due to their importance and versatility in
the production of aromatic ketones largely used as intermediates
in the synthesis of pharmaceuticals and fine chemicals [1–7].
Similarly, alkylations of aromatics with higher linear olefins
are industrially important as these are used for the production
of linear alkyl aromatics, which are used as the precursors in
the production of biodegradable surfactants [8]. Acylation and
alkylation of aromatics have traditionally been carried out using
homogeneous acid catalysts such as AlCl3, FeCl3, ZnCl2, and
HF, etc. [9–11]. But these catalysts are highly polluting, corro-
sive and are consumed in stoichiometric amounts in acylation
reactions due to the formation of 1:1 molar adduct with aromatic
ketones, which cannot be recovered and need to be neutral-
ized creating large salt waste [12]. These salt wastes are haz-
ardous, corrosive to equipment and non-ecofriendly. So, there
ble solid acid catalyst in view environmental limitations. Since,
solid catalysts are easy to recover, reuse and overcome corro-
sion problems, which could replace conventional catalysts and
these processes fit well in the domain of environmentally benign
chemistry.
During the past few years, different solid acid catalyst such
as zeolites [13] metal cation exchanged clays [14], ion exchange
resins [15], and supported-heteropoly acids have been used for
acylation of veratrole [16]. For the alkylation of toluene with
1-dodecene, large pore zeolites like H faujasite (HFAU), H mor-
denite (HMOR) and H beta (HBEA) were used [17].
Zirconia-based solid acids are attracting much attention in
recent years. For instance, sulfated zirconia proved to be a
highly active solid acid catalyst for various organic transforma-
tions [18]. But, its poor stability and tendency to form volatile
sulfur compounds during catalysis and regeneration limit its
applicability [19]. However, zirconia-supported tungsten oxide,
WOx/ZrO2 is shown to be an alternative to sulfated zirconia,
which is stable at high temperature and in presence of both oxi-
dizing and reducing atmosphere [20,21].
∗
Corresponding author. Tel.: +91 20 25893300; fax: +91 20 25893761.
E-mail address: sb.halligudi@ncl.res.in (S.B. Halligudi).
1381-1169/$ – see front matter © 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.molcata.2005.11.029

A. Bordoloi et al. / Journal of Molecular Catalysis A: Chemical 247 (2006) 58–64
59
The present work deals with acylation of veratrole by
acetic anhydride and alkylation of toluene by 1-dodecene using
WOx/ZrO2 as catalyst. The reactions were carried out with an
aim to maximize the conversion of acetic anhydride to acylated
product in acylation of veratrole, and monododecyl toluene in
alkylation of toluene by 1-dodecene. The influence of WO3
loading and catalyst calcination temperature over the catalyst
performance in both the reactions has been studied. The catalyst
with highest activity has been used to study the effect of reac-
tion parameters, such as reaction temperature, molar ratio of the
reactants and catalyst weight on the conversions and product
selectivity in both the reactions.
˚
equipped with Ni filtered Cu K␣ radiation (λ = 1.5418 A). The
volume percentage of tetragonal phase (Vt) of the calcined sam-
ples was estimated with the formula proposed by Toraya et al.
[22].
Im(11 − 1) + Im(1 1 1)
Xm
=
[Im(11 − 1) + Im(1 1 1) + It(1 1 1)]
1.311 Xm
Vm
=
and Vt = 1 − Vm
[1 + 0.31Xm]
where, Im (h k l) is the integral intensity of the (h k l) reflections
of the monoclinic phase and It (1 1 1) the intensity of the (1 1 1)
reflection of the tetragonal phase.
2. Experimental
¨
The nature of the acid sites (Bronsted and Lewis) of cat-
alysts with different WO3 loading was characterized by ex
situ FTIR spectroscopy with chemisorbed pyridine. A freshly
activated catalyst powder sample was saturated with pyridine
vapors placed in a desiccator containing pyridine. The pyridine-
saturated sample was then activated at 300 ◦C for 2 h and
the FTIR spectra of the samples were recorded on a Shi-
madzu (Model-820 PC) spectrophotometer under DRIFT (dif-
fuse reflectance infrared Fourier transform) mode.
The acidity of the catalysts were measured by temper-
ature programmed desorption of NH3 (NH3-TPD) using a
micromeritics AutoChem-2910 instrument. It was carried out
after ∼0.3 g of the catalyst sample was dehydrated at 500 ◦C
in He (30 cm3 min−1) for 1 h. The temperature was decreased
to 100 ◦C and NH3 was adsorbed by exposing samples treated
in this manner to a stream containing 10% NH3 in He for
1 h at 100 ◦C. It was then flushed with He for another 1 h to
remove physorbed NH3. The desorption of NH3 was carried
out in He flow (30 cm3 min−1) by increasing the temperature to
550 ◦C at 10 ◦C min−1 measuring NH3 desorption using TCD
detector.
2.1. Chemicals
Zirconium oxychloride (ZrOCl2·8H2O), ammonia (25%),
acetic anhydride (98%) and toluene (99.5%) were procured
from S.D. Fine chemicals Ltd. Mumbai. Veratrole (pyrocatechol
dimethyl ether) was obtained from Merck (India) Ltd. Mumbai.
Ammonium metatungstate hydrate ((NH4)6H2W12O40·xH2O)
and 1-dodecene were purchased from Aldrich. Zeolite USY
(Si/Al = 9) was provided by PQ Corporation. All the chemicals
were research grade and were used as received without further
purification.
2.2. Catalyst preparation
The catalysts were prepared by wet impregnation method
using zirconium oxyhydroxide as the support and ammonium
metatungstate as tungsten precursor. The support was prepared
by the hydrolysis of an aqueous solution of zirconium oxychlo-
ride with aqueous NH3. The precipitate obtained was washed till
free from chloride and dried at 120 ◦C. To an aqueous solution
of ammonium metatungstate, zirconium oxyhydroxide powder
was added and the mixture was stirred for 8–10 h. The excess
water was evaporated to dryness and the obtained product was
dried at 120 ◦C and calcined in air at different temperatures.
A series of catalysts with different WO3 loading (5–30 wt.%
of zirconium oxyhydroxide) were prepared and calcined at
800 ◦C. In order to study the influence of calcination temper-
ature on catalytic activity, the catalyst 15% WO3/ZrO2 was
calcined from 600 to 900 ◦C. The catalysts are represented by
xWZ-T, where, x represents wt.%, W represents tungsten oxide,
Z represents zirconia and T denotes calcination temperature
in ◦C.
2.4. Catalytic activity measurements
The liquid-phase acylation and alkylation reactions were car-
ried out under atmospheric pressure in 50 ml glass batch reactor.
The reaction mixture containing a mixture of veratrole and acetic
anhydride in acylation reaction and toluene/1-dodecene in alky-
lation reaction together with WZ catalyst were charged into the
round bottom flask fitted with a reflux condenser and CaCl2
guard tube, equipped with a magnetic stirrer and immersed in
a thermostated oil bath. The catalyst was activated at 500 ◦C
for 2 h in flow of dry air and cooled to the reaction temper-
ature prior to its use in the reaction. The clear solution of
the reaction mixture was withdrawn periodically, centrifuged
and analyzed by Shimadzu 14B gas chromatograph, equipped
with a flame ionization detector using HP-5 capillary column
(cross linked 5% ME silicone, 30 m × 0.53 × 1.5 ␮m film thick-
ness). The products were identified by GC-MS and by com-
paring with authentic samples. Conversions were defined as
the conversion of acetic anhydride into ketone and dodecene
into alkylated products in acylation and alkylation reactions,
respectively.
2.3. Characterization
The specific surface area of the catalysts was measured by
N2 physisorption at liquid nitrogen temperature using a Quanta
chrome Nova-1200 surface area analyzer and standard multi
point BET analysis methods. Samples were out gassed at 300 ◦C
in N2 flow for 2 h before N2 physisorption measurements.
X-ray diffraction (XRD) measurements of the catalyst pow-
der were recorded using a Rigaku Geigerflex diffractometer

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A. Bordoloi et al. / Journal of Molecular Catalysis A: Chemical 247 (2006) 58–64
Table 1
3. Results and discussion
Surface area, surface density, phase composition and acidity of various catalysts
3.1. Characterization of the catalysts
Sample
Surface area Surface density Vol.% t-ZrO2 Acidity
(m2 g−1
)
(W nm−2
)
(NH3 nm−2
)
3.1.1. Surface area
Z-800
5 WZ-800
12
38
0
6
9
n. e.
n. e.
2.6
2.5
2.7
3.1
n.e.
3
The pure zirconium oxyhydroxide dried at 120 ◦C showed
a surface area of 331.6 m2 g−1. After calcination at 800 ◦C,
the surface area decreased to 10 m2 g−1. Addition of WO3 to
the support results in an increase of the surface area, which
becomes maximum at ca. 61 m2 g−1 for 15% WO3 loading
(Fig. 1). This can be explained as the added WO3 strongly inter-
act with zirconia that reduces the surface diffusion of zirconia
and inhibits sintering [23] and stabilizes the tetragonal phase
of zirconia, which leads to an increase in surface area. Above
15% WO3 loading, XRD indicates the formation of crystalline
WO3, which probably narrows or plugs the pores of the sam-
ples, thus leading to the decrease in the specific surface area
[24]. The WO3 loading corresponding to each loading and cal-
cination temperature is determined to calculate the nominal
tungsten (W) surface density using the measured surface area.
The tungsten surface densities, expressed as the number of W
atoms per nanometer square area (W atoms nm−2) and were
calculated using the equation: surface density of W = {[WO3
loading (wt.%)/100] × 6.023 × 1023}/{[231.8 (formula weight
of WO3) × BET surface area (m2 g−1) × 1018]} and are given
in Table 1. It is seen that an increase of WO3 loading results in
an increase of the W surface density. The specific surface area of
WZ catalysts also depends on the calcination temperature. The
W surface density increased with the calcination temperature,
because of the concominant decrease in the ZrO2 surface area
(Fig. 1).
3.9
5.5
7.3
10.9
14.9
18.7
5.3
6.4
10
10 WZ-800 54
15 WZ-800 61
20 WZ-800 55
25 WZ-800 50
30 WZ-800 48
15 WZ-700 84
15 WZ-750 70
15 WZ-850 44
66
93
89
96
95
100
95
19
2.6
3
n.e.: not evaluated.
strongly influences the crystallization of zirconium oxyhydrox-
ide into zirconia. Pure zirconia calcined at 800 ◦C is mainly
monoclinic with only a small amount of the tetragonal phase.
For catalysts with low WO3 loading calcined at 800 ◦C, the XRD
pattern can be described as the sum of the monoclinic and tetrag-
onal phases of zirconia, this latter phase becoming dominant
for catalyst with 15% WO3. The tetragonal content of zirconia
at a fixed loading depends on the calcination temperature and
for 15% catalyst, zirconia exists mainly in the tetragonal form
up to 800 ◦C and the tetragonal content decreases with further
increaseincalcinationtemperature. Athighcalcinationtempera-
ture, WOx speciesagglomerateintomonoclinicWO3 crystallites
and becomes less effective sintering inhibitors. Thus, the added
WO3 stabilizes the tetragonal phase of zirconia and such stabi-
lization of tetragonal ZrO2 in presence of WO3 and other oxides
has been reported in the literature [23,24]. It can also be seen
that up to a 10% WO3 loading for catalysts calcined at 800 ◦C
and for 15% catalyst, up to 750 ◦C calcination, no diffraction
lines, whichcouldbeattributedtocrystallineWO3, areobserved,
indicating that WO3 is highly dispersed on the support. When
3.1.2. X-ray diffraction
The XRD pattern of the catalysts with different WO3 loading
calcined at 800 ◦C (Fig. 1) showed that, the presence of WO3
Fig. 1. X-ray diffractograms of (A) catalysts with different WO3 loading (a) Z-800, (b) 5 WZ-800, (c) 10 WZ-800, (d) 15 WZ-800, (e) 20 WZ-800, (f) 25 WZ-800;
and (B) 15 WZ catalyst calcined at different temperatures (a) 700, (b) 750, (c) 800, and (d) 850 ◦C.

A. Bordoloi et al. / Journal of Molecular Catalysis A: Chemical 247 (2006) 58–64
61
WO3 loading is higher than 10%, or when the calcination tem-
perature exceeds 750 ◦C for 15% loading, new diffraction lines
appear in the 2θ region of 23–25◦, characteristic of monoclinic
WO3 [24]. Thus, when the tungsten surface density exceeds
the theoretical monolayer capacity of ZrO2 (7 nm−2), i.e., WO3
loading exceeds monolayer coverage, X-ray diffractogram show
the presence of bulk crystalline WO3.
3.1.3. FTIR pyridine adsorption
Adsorption of pyridine as a base on the surface of solid acids
is one of the most frequently applied methods for the character-
ization of surface acidity. The use of IR spectroscopy to detect
adsorbed pyridine enables us to distinguish among different acid
sites. FTIR pyridine adsorption spectra of catalysts with differ-
ent WO3 loading calcined at 800 ◦C are shown in Fig. 2. The
catalysts showed Brønsted (B) and Brønsted (B) + Lewis (L)
acidity at 1543 cm−1 and at 1489 cm−1, respectively [25].
Fig. 2. FTIR pyridine adsorption spectra of catalysts with different WO3 loading
(a) 10 WZ-800, (b) 15 WZ-800, (c) 20 WZ-800, (d) 25 WZ-800.
3.1.4. TPD of NH3
This adsorption–desorption technique permits the determina-
tion of the strength of acid sites present on the catalyst surface,
together with total acidity. The TPD profiles of the catalysts
with different WO3 loading, the amounts of adsorbed NH3 per
square nanometer of the catalysts with different WO3 loading
and of catalyst with 15% WO3 calcined at different temper-
atures are shown in Fig. 3. All samples show a broad TPD
profile, revealing that the surface acid strength is widely dis-
tributed. It is evident from the data that there is an initial
increase in the acidity up to 15% loading, and thereafter the
acidity decreases. For 15% WZ catalysts, calcined at differ-
ent temperatures, the amount of adsorbed ammonia increases
with calcination temperature and reaches a maximum at
800 ◦C.
Scheme 1.
3.2. Veratrole acylation
The acylation of veratrole with acetic anhydride gave ace-
toveratrone (3,4-dimethoxy acetophenone) as the acylated prod-
uct (Scheme 1). The conversion is expressed as the percentage
of acetic anhydride converted into the acylated product.
Fig. 3. NH3-TPD profiles of (A) catalysts with different WO3 loading (a) 10 WZ-800, (b) 15 WZ-800, (c) 20 WZ-800, (d) 25 WZ-800; and (B) 15 WZ catalyst
calcined at different temperatures (a) 650, (b) 700, (c) 750, (d) 800, (e) 850 ◦C.

62
A. Bordoloi et al. / Journal of Molecular Catalysis A: Chemical 247 (2006) 58–64
Fig. 4. Effect of WO3 loading on Ac2O conversion (reaction conditions: reaction
temperature, 70 ◦C; total weight of the reaction mixture, 10 g; veratrole/Ac2O
molar ratio = 2; catalyst weight, 3 wt.% of the reaction mixture).
Fig. 6. Initial reaction rate vs. tungsten surface density of catalysts with differ-
ent WO3 loading calcined at 800 ◦C and 15 WZ catalyst calcined at different
temperatures.
In order to investigate the effect of WO3 loading, 5–30 WZ-
800 catalysts are used in acylation of veratrole with acetic
anhydride (Ac2O) at 70 ◦C (Fig. 4). Among the catalysts with
different WO3 loading, the catalyst 5 WZ-800 showed no acetic
anhydride conversion, while the catalyst 15 WZ-800 gave the
highest conversion (67%). Further, increase in WO3 loading
decreases the Ac2O conversion and for 25 WZ it is 50%.
The catalyst 15 WZ calcined different temperatures are used
to study the change in catalytic activity with calcination temper-
ature. It is clear from Fig. 5, that calcination temperature has a
profound effect on the catalytic activity. The catalyst calcined
at 650 ◦C shows 31% conversion of acetic anhydride, which
increases to 67% after calcination at 800 ◦C. Further increase in
catalyst calcination temperature, decreases Ac2O conversion.
The initial reaction rate versus tungsten surface density for
catalysts with different WO3 loading calcined at 800 ◦C and 15
WZ catalyst calcined at different temperatures in acylation of
veratrole is shown in Fig. 6. The change in initial reaction rate
with loading and calcination temperature shows that the catalyst
15 WZ-800 has the highest catalytic activity. The surface den-
sity of 15 WZ-800 catalyst is found to be 7.34 W nm−2, which
is slightly higher than the monolayer coverage of WO3 on zirco-
nia. Iglesia and co-workers, from in situ acidity measurements
showed that Brønsted acidity of WZ catalysts increases up to
monolayer coverage of WO3 on zirconia [26]. At high W surface
densities, XRD shows the presence of bulk crystalline WO3 and
hence the active sites are inaccessible to the reactants and this
decreases the catalytic activity. The highest catalytic activity at
surface density of 7.3 W nm−2 clearly indicated that irrespective
of WO3 loading and calcination temperature, catalytic activity
depended on WO3 coverage and the catalyst with WO3 loading
slightly higher than that required for monolayer coverage had
the highest catalytic activity.
Thus, the catalyst with highest activity is used to study dif-
ferent reaction parameters. The reaction is studied in the tem-
perature range of 50–90 ◦C using the most active catalyst 15
WZ-800 (Fig. 7). At 50 ◦C, Ac2O conversion is 22% and it
increases to 67% at 70 ◦C. Further increase in reaction tem-
perature to 90 ◦C has no appreciable effect on Ac2O conversion.
The effect of molar ratio on Ac2O conversion is studied at 70 ◦C
with veratrole/Ac2O molar ratio of 1:3 (Fig. 8). At a molar ratio
of 1, conversion is 25%, which increased to 67% at a molar ratio
of 2. Further increase in molar ratio has no appreciable effect in
Ac2O conversion. The effect of catalyst weight on Ac2O con-
version was studied using 1–5% (Fig. 9) of total weight of the
reaction mixture as catalyst. The 1-wt.% catalyst concentration
gave Ac2O conversion of 21% and it increased to 67% with
3 wt.% catalyst concentrations.
In order to study the recyclability of the catalyst, the reac-
tion was conducted at 70 ◦C with 3 wt.% catalyst using verat-
role/acetic anhydride molar ratio 2 for 2 h. Fresh catalyst showed
58% Ac2O conversion in 2 h. For recycling, the catalyst used in
Fig. 5. Effect of catalyst calcination temperature on Ac2O conversion (reac-
tion conditions: temperature, 70 ◦C; total weight of the reaction mixture, 10 g;
veratrole/Ac2O molar ratio = 2; catalyst weight, 3 wt.% of the reaction mixture).

A. Bordoloi et al. / Journal of Molecular Catalysis A: Chemical 247 (2006) 58–64
63
Fig. 7. Effect of reaction temperature on Ac2O conversion (reaction conditions:
total weight of the reaction mixture, 10 g; veratrole/Ac2O molar ratio = 2; cata-
lyst weight, 3 wt.% of the reaction mixture).
Fig. 8. Effect of veratrole/Ac2O molar ratio on Ac2O conversion (reaction con-
ditions: temperature, 70 ◦C; total weight of the reaction mixture, 10 g; catalyst
weight, 3 wt.% of the reaction mixture).
be due to partial loss of acid sites of the catalyst during reac-
tion/regeneration.
the first cycle was separated by filtration, washed with methanol
and dried at 100 ◦C for 3 h and rerun with fresh reaction mixture.
The methanol washed catalyst showed 16% Ac2O conversion in
2 h. The lower activity of the separated catalyst after washing
may be due to the presence of surface bound acetate species
formed from the by-product acetic acid, which is difficult to
remove by washing [27,28]. However, after regeneration of the
catalyst by calcination, Ac2O conversion was increased to 53%.
The activity loss observed with the regenerated catalyst could
Finally the activity of 15 WZ-800 catalyst is compared with
that of zeolite HY in acylation of veratrole with acetic anhydride
at90 ◦Cfor2 husingveratrole/Ac2Omolarratioof1andcatalyst
concentration of 1 wt.% of total weight of the reaction mixture.
The HY zeolite gave 63% Ac2O conversion, while 15 WZ-800
catalyst gave 56% Ac2O conversion. Thus, the activity of 15
WZ-800 catalyst is slightly lower than that of zeolite HY.
Table 2
Effects of different parameters on WZ catalyzed alkylation of toluene by 1-dodecene
No.
Catalyst
Toluene/1-dodecene molar ratio
Catalyst weight (%)a
Reaction temperature (◦C)
Conversion of dodecene (%)
(A) Effect of WO3 loading
1
2
3
4
10WZ-800
15WZ-800
20WZ-800
25WZ-800
10:1
5
5
5
5
90
90
90
90
15
49
40
38
10:1
10:1
10:1
(B) Effect of catalyst calcination temperature
5
7
8
9
10
15WZ-650
15WZ-700
15WZ-750
15WZ-800
15WZ-850
10:1
10:1
10:1
10:1
10:1
5
5
5
5
5
90
90
90
90
90
3
12
45
49
23
(C) Effect of reaction temperature
11
12
13
15WZ-800
15WZ-800
15WZ-800
10:1
10:1
10:1
5
5
5
80
90
100
9
49
99
(D) Effect of toluene/1-dodecene molar ratio
14
15
16
17
15WZ-800
15WZ-800
15WZ-800
15WZ-800
2.5:1
5:1
7.5:1
5
5
5
5
90
90
90
90
18
21
36
49
10:1
(E) Effect of catalyst weight
18
19
20
21
15WZ-800
15WZ-800
15WZ-800
15WZ-800
10:1
10:1
10:1
10:1
1
3
5
7
90
90
90
90
26
28
49
67
Conditions: total weight of the reaction mixture, 10 g; time, 1 h, acatalyst weight with respect to total weight of the reaction mixture.

64
A. Bordoloi et al. / Journal of Molecular Catalysis A: Chemical 247 (2006) 58–64
WOx/ZrO2 catalyst. The most active catalyst 15 WZ-800 gave
67% acetic anhydride conversion in veratrole acylation under the
reaction conditions of 70 ◦C, veratrole/acetic anhydride molar
ratio 2, time 4 h and 99% dodecene conversion with > 99%
monododecyl toluene selectivity at 100 ◦C, toluene/1-dodecene
molar ratio 10 and time 1 h. The 15 WZ-800 catalyst shows
slightly lower activity than that of HY zeolite in acylation of
veratrole. This catalyst system is easy to prepare and the deacti-
vated catalyst can be reused without appreciable lose in catalytic
activity after regeneration by calcination.
Acknowledgements
This work was carried under DST-SERC project. A.B. and
B.M.D. acknowledge CSIR, New Delhi (India) for Junior
Research Fellowship and Research Associateship, respectively.
Fig. 9. Effect of catalyst weight on Ac2O conversion (reaction conditions: tem-
perature, 70 ◦C; total weight of the reaction mixture, 10 g; veratrole/Ac2O molar
ratio = 2).
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3.3. Alkylation of toluene by 1-dodecene
The main reactions obtained with these catalysts were alkene
double bond shift isomerization and toluene alkylation giving
monododecyltoluene as the alkylated product. The formation
of dialkylated products was not observed under the reaction
conditions studied here. The conversion was expressed as the
percentage of alkene converted into alkylated products. The
effect of WO3 loading on dodecene conversion was investigated
using 10–25 WZ-800 catalysts with toluene to 1-dodecene molar
ratio of 10 at 90 ◦C for 1 h (Table 2). The 15WZ-800 catalyst
shows dodecene conversion of 49% and 25 WZ-800 catalyst
gave 38% conversion under the reaction conditions studied. It
is clear that calcination temperature has a profound effect on
conversion of dodecene. The 15 WZ-650 catalyst gave very low
dodecene conversion and the conversion increased to 49% with
15 WZ-800 catalyst (Table 2). The highest catalytic activity at
surface density of 7.3 W nm−2 clearly indicated that irrespective
of WO3 loading and calcination temperature, catalytic activity
depended on WO3 coverage.
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The catalyst with highest activity 15 WZ-800 used to study
different reaction parameters. The effect of reaction tempera-
ture on dodecene conversion was studied from 80 to 100 ◦C
(Table 2). As expected, the conversion of dodecene increased
with an increase in temperature and reached 99% with >99%
monododecyltoluene selectivity at 100 ◦C (Table 2). As the
toluene/1-dodecene molar ratio increased from 2.5 to 10, conver-
sion of dodecene increased from 18 to 49%, and further increase
in molar ratio to 12, had no appreciable effect. The conversion
of dodecene was 26% with 1 wt.% catalyst (total weight of the
reaction mixture), which increased to 67% with 7 wt.% catalyst.
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Iglesia, J. Catal. 227 (2004) 470.
4. Conclusions
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Kemnitz, Catal. Lett. 83 (2002) 271.
The liquid-phase acylation of veratrole with acetic anhydride
and alkylation of toluene with 1-dodecene were studied using