Heteropoly acid supported modified Montmorillonite clay: An effective catalyst for the esterification of acetic acid with sec-butanol

Article abstract of DOI:10.1016/j.apcata.2010.02.026

Esterifications of acetic acid with sec-butanol catalysed by supported dodecatungstophosphoric acid, H₃PW₁₂O₄₀ (DTP) on acid modified Montmorillonite clay (AT-Mont) matrix have been carried out. A series of catalysts having 5%, 10%, 20% and 30% loading of DTP on different AT-Mont (15 min to 4 h) were synthesized and evaluated as catalysts; 20% DTP loaded on acid activated (15 min) clay showed the highest catalytic activity with about 80% conversion, having nearly 100% selectivity towards sec-butyl acetate. The high catalytic activity may be due to a high dispersion of the DTP on AT-Mont, providing more surface area (120 m²/g) and active sites than pure HPA. The variation of different reaction parameters, such as reaction temperature, reaction time, mole ratio of acid and alcohol and catalyst amount, on the conversion of acetic acid were studied. The samples were characterized by surface area, cation exchange capacity (CEC) measurements, TGA-DTA and FTIR spectroscopy.

Full text of DOI:10.1016/j.apcata.2010.02.026

Applied Catalysis A: General 378 (2010) 221–226
Contents lists available at ScienceDirect
Applied Catalysis A: General
journal homepage: www.elsevier.com/locate/apcata
Heteropoly acid supported modified Montmorillonite clay: An effective catalyst
for the esterification of acetic acid with sec-butanol
∗
Siddhartha Kumar Bhorodwaj, Dipak Kumar Dutta
Materials Science Division, North-East Institute of Science and Technology (CSIR), Jorhat, Assam 785006, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Esterifications of acetic acid with sec-butanol catalysed by supported dodecatungstophosphoric acid,
H3PW12O40 (DTP) on acid modified Montmorillonite clay (AT-Mont) matrix have been carried out. A
series of catalysts having 5%, 10%, 20% and 30% loading of DTP on different AT-Mont (15 min to 4 h)
were synthesized and evaluated as catalysts; 20% DTP loaded on acid activated (15 min) clay showed the
highest catalytic activity with about 80% conversion, having nearly 100% selectivity towards sec-butyl
acetate. The high catalytic activity may be due to a high dispersion of the DTP on AT-Mont, providing more
Received 21 October 2009
Received in revised form 11 February 2010
Accepted 22 February 2010
Available online 1 March 2010
Keywords:
Montmorillonite clay
Heteropoly acid
Dodecatungstophosphoric acid
Catalyst
2
surface area (120 m /g) and active sites than pure HPA. The variation of different reaction parameters,
such as reaction temperature, reaction time, mole ratio of acid and alcohol and catalyst amount, on the
conversion of acetic acid were studied. The samples were characterized by surface area, cation exchange
capacity (CEC) measurements, TGA-DTA and FTIR spectroscopy.
Esterification
Cation exchange capacity
© 2010 Elsevier B.V. All rights reserved.
1
. Introduction
Esters, which include a wide category of organic compounds
and sulphated oxides [11]. However, the systematic study of ester-
ification of sec-butanol with acetic acid using the above mentioned
solid acid catalysts is not yet adequate. Heteropoly acids (HPAs)
have been widely used in numerous acid-catalysed reactions due
to their strong Bronsted acidity [3,12]. Dodecatungstophosphoric
acid (DTP) is the most stable among all HPAs and is commonly
used for acid catalysis, since it possesses the highest Bronsted
acidity [13,14]. In homogeneous liquid-phase catalysis, the advan-
tages of the HPAs are more distinctive due to their low volatility,
low corrosiveness, high acidity, activity and flexibility. These acids
ranging from aliphatic to aromatic, are generally used as plas-
ticizers, solvents, perfumery, and flavor chemicals, and also as
precursors for a gamut of pharmaceuticals, agrochemicals and
other fine chemicals [1]. Compared to primary alcohols, esterifi-
cation of a secondary alcohol is much more difficult to achieve.
The steric effect of these substrates and the lower nucleophilicity
of the oxygen atom hinders the formation of the corresponding
ester [2]. Conversions are also limited by slow reaction rates and
reversible reactions. Conventional homogenous catalysts widely
used in industries for esterification include H SO , HCl, HF, H PO ,
◦
have fairly high thermal stabilities and are stable up to 300–350 C
[15–17]. Depending on the reaction conditions, it has been found
that the activity/mole proton of HPA is higher by a factor of 3–100
times than sulphuric acid as far as its reactivity in Bronsted acid-
catalysed liquid-phase reactions is concerned [13]. But the main
disadvantages of such HPAs as catalysts lie in their relatively low
2
4
3
4
and ClSO OH [3,4]. They suffer, however, from several drawbacks,
2
such as their corrosive nature, the existence of side reactions and
the fact that the catalyst cannot be easily separated from the
reaction mixture [5]. Due to stringent and growing environmen-
tal regulations, the chemical industry needs the development of
more ecocompatible synthetic methodologies [6]. The use of het-
erogeneous acid catalysts offers an alternative and has received a
lot of attention in the past years [5]. The heterogeneous catalysts
reported in the literature for esterification reactions include ion
exchange resin [7], H-ZSM–5 [8], zeolites-Y [9], niobic acid [10],
2
surface area (1–10 m /g) and in separation problems from reaction
mixture [4]. HPAs on suitable supports are expected to overcome
the above mentioned problems. A number of porous supports
with high surface areas, such as silica, ZrO , active carbon, SBA-
2
15, and zeolite etc. [18–23], have been used for supporting HPAs.
Acid modified clay minerals can also be used as an efficient sup-
ports [24] because they exhibit higher surface area, pore volume,
pore diameter and higher surface acidity [25] which results in its
improved adsorption and catalytic properties. In particular, the
acid treated clay catalysts have received considerable attention in
different organic syntheses as a catalyst or as a support because
∗ Corresponding author. Tel.: +91 376 2370 081; fax: +91 376 2370 011.
E-mail address: dipakkrdutta@yahoo.com (D.K. Dutta).
0
926-860X/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.apcata.2010.02.026

2
22
S.K. Bhorodwaj, D.K. Dutta / Applied Catalysis A: General 378 (2010) 221–226
Fig. 1. FTIR spectra of (i) pure DTP, (ii) AT-Mont (15 min) and (iii) 20 wt% DTP/AT-Mont (15 min).
of their environmental compatibility, low cost and operational
simplicity. Using clay catalysts, one can conduct environmentally
benign green chemistry both at industrial level and on laboratory
scale. The acid strength of HPA supported on some of the mate-
rials mentioned above is lower than that of bulk HPA, due to the
interaction of HPA with surface functional groups of supports. In
cases of composite material, there is an influence of support on the
acidity function of HPA and vice versa [26]. Acid treated Montmoril-
lonite exhibits comparatively strong acid sites [27]. Therefore, fine
and uniform dispersion of DTP on large surface area mesoporous
AT-Mont supports will increase the overall acidity and catalytic
activity. In the present study, we report that HPA-like DTP is sup-
ported on acid modified Montmorillonite clay; it is also evaluated
as solid acid catalyst for the esterification of sec-butanol with acetic
acid.
2.3. Characterization techniques
Primary Keggin structures of bulk as well as supported HPA cata-
lysts were compared by FTIR analysis. FTIR studies were conducted
by using a PerkinElmer system 2000 FTIR spectrometer.
Specific surface area and pore volume were measured by using
Autosorb1 (Quantachrome, USA). Specific surface areas were deter-
mined by using the Brunner–Emmett–Teller (BET) method. N2
vapour adsorption data was obtained for the vapour pressure range
(p/po) of 0.03–0.3. Prior to adsorption, samples were degassed at
◦
200 C for about 1.5 h.
The TG–DTA measurements of the samples were done with a
thermal analyzer (TA Instruments, Model STD 2960, simultaneous
DTA-TGA) with about 10 mg of sample in a platinum crucible at a
◦
−1
heating rate of 10 C min in an air atmosphere.
Cation exchange capacities of different supports were deter-
mined by using standard techniques [30].
2
. Experimental
2.1. Support preparation
2.4. Esterification reactions
Natural Montmorillonite clay (procured from Gujarat, India)
that contains silica sand, iron oxide, etc. as impurities was puri-
fied by a standard sedimentation method [28] to collect the <2 ␮m
fraction before use. The oxide compositions of the clay as deter-
mined by weight chemical and flame photometric methods were
SiO : 49.42; Al O : 20.02; Fe O : 7.49; MgO: 2.82; CaO: 0.69; LOI:
Into a pressure autoclave were taken 0.3 g of freshly activated
◦
catalyst (dried at 120 C for 2 h in an oven), 0.15 mol of acetic acid
(Merck, 99.8%), 0.05 mol of sec-butanol (Merck, 98%). The autoclave
◦
temperature was then slowly raised to 100–150 C (autogeneous
pressure 1–3 atm.) and maintained at the desired temperature dur-
ing the specified reaction periods (1–12 h). The reaction products
were collected from the autoclave and analyzed by GC (Chemito
GC, Model 8510, FID). The catalyst was then washed with water
and activated for the next experiments.
2
2
3
2
3
1
7.51; others (Na O, K O and TiO ) 2.05%.
2 2 2
The purified clay (1 g) was refluxed with 4 M HCl acid (100 ml)
for various time intervals (15 min, 1 h, 2 h and 4 h). The slurry was
cooled, filtered and washed thoroughly with water and then was
dried in an air oven at 393 K for 12 h [25,29]. The clay samples thus
prepared are designated as AT-Mont (time).
3. Results and discussion
2.2. Catalyst preparation
3.1. Characterization of catalysts
A series of catalysts having 5%, 10%, 20% and 30% loading of DTP
(
Aldrich, 99.9%) on different AT-Mont (time) samples were syn-
3.1.1. FTIR
Bulk DTP shows the characteristic IR bands at 1080 cm (P–O
−
−1
1
thesized. DTP was supported on AT-Mont by means of incipient
wetness impregnation method [12]. A known amount of DTP was
dissolved in water and the hot support (dried at 120 C for 6 h in an
−
1
in central tetrahedral), 984 cm (terminal W O), 894 cm and
◦
−1
801 cm (W–O–W) associated with the asymmetric vibrations of
oven) was added to the solution. The slurry was shaken for 15 min
at room temperature, washed with water and dried in the oven at
the Keggin polyanion. After the materials were supported on AT-
Mont, some of the characteristic Keggin bands were observed at
982 cm and 893 cm and other bands were merged up with the
AT-Mont bands (Fig. 1).
−
1
−1
3
73 K for 12 h. The samples are designated as wt% DTP/AT-Mont
(
time).

S.K. Bhorodwaj, D.K. Dutta / Applied Catalysis A: General 378 (2010) 221–226
223
Fig. 2. (a) Pore size distribution curves of different samples determined by applying BJH method. (b) N2 adsorption–desorption isotherms for AT-Mont (15 min) and 30%
DTP/AT-Mont (15 min).
3
.1.2. Nitrogen adsorption
The surface area and pore volume of AT-Mont (15 min) and dif-
adsorbed water molecule. A gradual weight loss of about 3% up to
500 C was also observed, such a result indicates an increase in the
◦
ferent wt% of DTP on AT-Mont (15 min) are given in Table 1. The
surface area (390 m /g) and total pore volume (0.30 cc/g) of AT-
thermal stability of DTP on AT-Mont support. This may be due to
the formation of intermolecular bondings between the support and
heteropoly acid and indicates the presence of chemical interaction
between the support and heteropoly acid.
2
Mont (15 min) decreases as the amount of DTP loading increases.
2
For 30% DTP loading the surface area becomes 101 m /g while the
total pore volume becomes 0.10 cc/g only. The acid-leaching has
fundamentally transformed the layered Montmorillonite into an
amorphous silica-like structure. The high surface area of 15 min
acid treated clay is related to the removal of some of the aluminum
from octahedral sites in the clay. The reduction in surface area and
pore volume upon DTP loading may be due to the blockage of pores
by DTP molecules. The pore size distribution plot in Fig. 2(a) shows
that the average pore sizes of AT-Mont (15 min) and different wt%
of DTP on AT-Mont (15 min) fall in the range of 35–50 Å suggest-
ing that pore sizes of the catalysts lie in the mesoporous region, i.e.
3
.1.4. Cation exchange capacity
The cation exchange capacities of different supports were deter-
mined and are given in Fig. 4. It is evident that as the time of acid
treatment increases, the cation exchange capacity of the support
decreases from a value of 95.8 meq/100 g of clay to 6.7 meq/100 g
of clay only. This reduction in CEC is due to the destruction of the
layered structure of the clay as the time of acid treatment increases.
3.2. Catalytic activity
>20 Å. The adsorption–desorption isotherms of AT-Mont (15 min)
and 30% DTP/AT-Mont (15 min) in Fig. 2(b) show that they have
the form of Type IV isotherms with the hysteresis loop of type H3,
which is a characteristic of a mesoporous solid.
The esterification of acetic acid with sec-butanol is an elec-
trophilic substitution reaction; it is a relatively slow reaction and
needs activation either by higher temperature or by a catalyst to
achieve higher conversion.
3.1.3. Thermal analysis
The thermal analyses have been carried out on bulk DTP, AT-
Mont (15 min) and on 20% DTP/AT-Mont (15 min) samples. The
results of these analyses are reported in Fig. 3. The TGA of 12-
tungstophosphoric acid shows a weight loss of about 8% up to a
◦
temperature of 180 C, indicating loss of free and adsorbed water.
◦
The gradual weight loss of about 3% up to 500 C corresponds to
the mass loss due to the reaction between acidic protons and struc-
tural oxygen from phosphotungstic acid, releasing water, followed
by decomposition to WO3 and POx species [31]. The thermal data
of AT-Mont (15 min) shows a steady loss of weight of about 17%
◦
up to 500 C; such a loss is attributed to the loss of physisorbed
and interlayer water and also due to dehydroxylation caused by
the breaking of structural OH-groups of the support [32]. The TGA
of supported DTP onto AT-Mont (15 min) shows about 18% weight
◦
loss within the temperature range of 80–150 C due to a loss of
Table 1
Surface area and pore volume of different samples.
Catalyst
BET surface area
Total pore
volume (cc/g)
2
(
m /g)
AT-Mont (15 min)
390
140
120
101
0.30
0.15
0.12
0.10
1
2
3
0% DTP/AT-Mont (15 min)
0% DTP/AT-Mont (15 min)
0% DTP/AT-Mont (15 min)
Fig. 3. Thermal analyses of bulk DTP, AT-Mont (15 min) and 20% DTP/AT-Mont
(
15 min) samples.

2
24
S.K. Bhorodwaj, D.K. Dutta / Applied Catalysis A: General 378 (2010) 221–226
Fig. 6. Effects of different catalysts on esterification of acetic acid with sec-butanol.
◦
Reaction conditions: temperature: 100 C, catalyst amount: 0.3 g, acid: alcohol:
:1(mole ratio).
3
to 30% DTP on AT-Mont (15 min). It is interesting to note that the
activity of DTP is significantly lower than that of the same amount
supported on AT-Mont (15 min) [e.g. esterification reaction with
Fig. 4. Cation exchange capacities of different supports.
◦
2
0% DTP alone, gives about 22% conversion at 100 C (not shown in
the figure) with a selectivity of about 97%, while 20% DTP/AT-Mont
15 min), shows about 31% conversion (Fig. 5) with a selectivity of
(
about 99.5%] under the same reaction conditions. The enhanced
activity may be ascribed to a high dispersion of the DTP on AT-
Mont, providing more surface area and active sites than pure HPA.
Fig. 6 shows that, with the increase in acid treatment time of the
support, the corresponding conversions decrease. This may be due
to the decrease of surface area (Table 1) with the increased amount
of loading and also due to decrease in CEC of the AT-Mont sup-
ports (Fig. 4). In view of the above, all further evaluations were
carried out using 20% DTP/AT-Mont (15 min) catalyst. Thus, AT-
Mont impregnated with DTP appeared to be a very active catalyst
for the liquid-phase esterification of sec-butanol with acetic acid.
In the present study, comparative results for the esterification of
sec-butanol with acetic acid over some reported typical solid acid
catalysts [33–35] are given in Table 2.
Fig. 5. The effects of different loading of DTP on the esterification of acetic acid with
sec-butanol. Reaction conditions: temperature: 100 C, catalyst amount: 0.3 g, acid:
alcohol: 3:1 (mole ratio).
◦
A plausible mechanism that is involved in the esterification of
acetic acid with sec-butanol reaction is as follows:
Some other factors such as reaction time, mole ratio of acid
to alcohol, and catalyst amount also influence the conversion and
selectivity of the reaction. The variation of different reaction param-
eters was studied on 20% DTP/AT-Mont (15 min) catalyst using
sec-butyl alcohol and acetic acid. Moreover, control of water con-
tent in HPA catalysts is essential for their efficient performance.
This can be achieved by thermal pretreatment of the catalysts [36],
◦
typically at 130–200 C. Excess water causes a decrease in the HPA
acid strength, and thus lowers its activity. At higher calcination
temperature, dehydration/dehydroxylation of the catalyst occurs
[
37]. Dehydration of the catalyst increases the acid strength but
decreases the number of acid sites, which may reduce the overall
catalytic activity [15]. Therefore, the catalysts were activated at an
◦
optimum temperature, i.e. 120 C before use.
Table 2
Results of esterification of sec-butanol with acetic acid catalysed by different solid
acid catalysts.
The reaction, following the Eley–Rideal mechanism, takes place
between acetic acid and protons chemisorbed on the active sites
Catalyst
Zirconia
Conversion (%)
References
a
38
71
57
74
27
[33]
[33]
[34]
[35]
[35]
(
Brønsted acid sites) of the catalyst surface, resulting in a stable car-
0% STA/Zirconiaa
2
b
bocation. The positive charge on the carbon atom is then attacked
by one of the lone pairs on the oxygen of the sec-butanol to form an
unstable intermediate. In the final step removal of a water molecule
from the intermediate gives the final product, i.e. sec-butyl acetate
along with the regeneration of the catalyst.
30% STA/Hydrous Zirconia
Amberlite IR-120c
Crosslinked
poly-(4-vinylpyridine)
hydrochloridec
20% DTP/AT-Mont.(15 min)
80
Present work
The conversion and selectivity of different catalysts are given
in Figs. 5 and 6. It can be seen from Fig. 5 that, on increasing the
loading from 5% DTP to 20% DTP on AT-Mont (15 min), the conver-
sion increases; thereafter, however it decreases on further loading
STA: Silicotungstic acid.
Reaction conditions: Time: 4 h, reaction temperature: 98 C, catalyst amount:
0.025 g, acid: alcohol: 1:16; Catalyst amount: 0.5 g; alcohol: acid 1:2; cTime: 1 h,
a
◦
b
◦
reaction temperature: 80 C, catalyst amount: 0.125 g, acid: alcohol: 1:2.

S.K. Bhorodwaj, D.K. Dutta / Applied Catalysis A: General 378 (2010) 221–226
225
Fig. 7. The effects of reaction time on the esterification of acetic acid with sec-
◦
butanol using 20% DTP/AT-Mont (15 min). Reaction conditions: temperature: 150
closed system), pressure: 3 atm., catalyst amount: 0.3 g, acid: alcohol: 3:1 (mole
ratio).
C
Fig. 9. The effects of mole ratio on the esterification of acetic acid with sec-butanol
using 20% DTP/AT-Mont (15 min). Reaction conditions: temperature: 150 C (closed
◦
(
system), pressure: 3 atm., catalyst amount: 0.3 g.
3.2.1. Influence of reaction time
The influence of reaction time on the acetic acid conversion
using 20% DTP/AT-Mont (15 min) as catalyst is given in Fig. 7. A
gradual rise in the conversion is seen with increase in duration
of the reaction period. Fig. 7 reveals that in 9 h of reaction time,
about 79% of conversion was observed, which enhanced to 79.9% at
the end of 12 h. The selectivity towards sec-butyl acetate remains
almost 100% in all cases.
3.2.2. Influence of reaction temperature
The reaction was carried out at various reaction temperatures,
◦
◦
ranging from 100 C to 150 C at a given acetic acid to sec-butanol
ratio of 3:1 for 1 h, 6 h and 9 h. The conversion amount of sec-butyl
acetate versus reaction temperature is given in Fig. 8. From the
figure it is evident that the conversion of acetic acid increases with
the increase in reaction temperature. This suggests that increase in
reaction temperature favors the formation of carbonium ion from
acetic acid, this ion can reacts with sec-butyl alcohol to produce
sec-butyl acetate. The selectivity remains nearly 100%.
Fig. 10. The effects of catalyst amount on the esterification of acetic acid with sec-
◦
butanol using 20% DTP/AT-Mont (15 min). Reaction conditions: temperature: 150
(closed system), pressure: 3 atm., acid: alcohol: 3:1 (mole ratio).
C
3.2.4. Influence of catalyst amount
The effects of catalyst amounts on the esterification of acetic
3
.2.3. Influence of molar ratio of reactants
The effect of the mole ratio of reactants on the esterification
acid with sec-butanol for 1 h and 9 h are shown in Fig. 10. With
the increase in catalyst amount, the conversion of sec-butyl alco-
hol increases marginally; this increase may be due to diffusional
resistance in catalyst pores [38]. It is well known that reactions
on Montmorillonites generally involve adsorption and diffusion of
reactants through the pores and interlayers [39]. The diffusion of
the reactants to the active sites can become a limiting process in
such porous solid acids [5]. The product molecules remain adsorbed
within the pores/channels of the catalyst and may restrict diffusion
for the fresh reactants. The selectivity, however, towards sec-butyl
acetate is nearly 100% in all cases.
of acetic acid with sec-butanol for 1 h and 9 h are shown in Fig. 9.
For all mole ratios of acetic acid to sec-butanol, sec-butyl acetate
is observed as the main product. With the increase in acetic acid:
sec-butanol mole ratio from 1:2 to 3:1, the conversion increases
because the increased acid amounts enhance the conversion of sec-
butanol. With further increase in mole ratio to 4:1, a decrease in
conversion was observed. This decrease may be due to leaching of
HPA from clay support; this is likely to occur in the course of the
reaction because of its higher solubility in a more polar medium.
The selectivity towards sec-butyl acetate remained nearly 100% in
all cases.
3
.3. Recyclability of the catalyst
In order to regenerate a catalyst like 20% DTP/AT-Mont (15 min)
after 9 h reaction, we separated it by filtration, washed it with con-
◦
ductivity water several times, dried it at 120 C in an air oven and
then used it in the esterification reaction with a fresh reaction
mixture. The results obtained are shown in Table 3. A decrease in
conversion was observed with its subsequent reuse, i.e. the conver-
Table 3
Esterification of acetic acid with sec-butanol using recovered catalyst.
Cycle
Conversion (%)
Selectivity (%)
1
2
3
st run
nd run
rd run
79
74
68
>99
>99
>99
Fig. 8. The effects of reaction temperature on the esterification of acetic acid with
sec-butanol using 20%DTP/AT-Mont (15 min). Reaction conditions:catalyst amount:
◦
Reaction conditions: temperature: 150 C (closed system), pressure: 3 atm., acid:
Alcohol: 3:1 (mole ratio), reaction time: 9 h.
0
.3 g, acid: alcohol: 3:1 (mole ratio), pressure: autogeneous.

2
26
S.K. Bhorodwaj, D.K. Dutta / Applied Catalysis A: General 378 (2010) 221–226
sion of 79% in the first run decreases to about 74% in the 2nd run
and to 68% in the third run. That decrease in catalytic activity is due
to the subsequent leaching of DTP (of about 3–5%) from the support
into the liquid phase during the catalytic reactions was confirmed
by a well-known ascorbic acid test [40]. However, the selectivity
remains almost unchanged, i.e. >99.5%.
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3
2
on AT-Mont acts as an efficient stable solid acid catalyst for ester-
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is attributed to the high surface area and BrÖnsted acid sites of the
catalyst. The highly dispersed DTP on AT-Mont may provide higher
active sites for the esterification. In all the esterification reactions
the selectivity was nearly 100% while the conversion was about 80%
within 12 h of reaction time. The 20% loading of DTP on AT-Mont
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(
15 min) shows the highest efficacy. The catalyst can be regenerated
and reused for several runs.
[
[
(
(
Acknowledgement
[
[
24] O.S. Ahmed, D.K. Dutta, Langmuir 19 (13) (2003) 5540–5541.
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The authors are grateful to Dr. P. G. Rao, Director, North-East
Institute of Science and Technology (CSIR), Jorhat, Assam, India,
for his kind permission to publish the work. Thanks are due to
Head, Materials Science Division, NEIST, Jorhat, for encouragement.
Thanks are also due to CSIR, New Delhi for granting a fund through
a Network Project (No. NWP-0010).
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