Partial hydrogenation of benzene to cyclohexene over Ru/γ-Al2O3 nanocatalyst via w/o microemulsion using boric acid and ethanolamine additives

Article abstract of DOI:10.1007/s11164-015-2102-6

Ru/γ-Al₂O₃ nanocatalyst was synthesized by water-in-oil reverse microemulsion technique and characterized by TEM, SEM-EDX, XRD, N₂ adsorption-desorption, and H₂ chemisorption. The surface area and active sites (S _M) of 3 wt% Ru/γ-Al₂O₃ was obtained around 217.6 m²/g and 45.70 m²/g_cat, respectively. The catalyst performance of Ru/γ-Al₂O₃ was assessed in the selective hydrogenation benzene to cyclohexene in the presence of boric acid (BA) and ethanolamine (EA) additives. The effect of such specific additives alone and in combination on the activity and selectivity of benzene hydrogenation was systematically investigated. Ru catalyst displayed pre-eminent performance at 0.5 mmol ratio of BA to EA exhibiting the highest selectivity (40 %) and yield (16 %) of the intermediate product, cyclohexene at 40 % of benzene conversion.

Full text of DOI:10.1007/s11164-015-2102-6

Res Chem Intermed
DOI 10.1007/s11164-015-2102-6
Partial hydrogenation of benzene to cyclohexene
over Ru/c-Al2O3 nanocatalyst via w/o microemulsion
using boric acid and ethanolamine additives
S. U. Nandanwar1 A. A. Dabbawala2 M. Chakraborty1
•
•
•
H. C. Bajaj2 S. Mukhopadhyay3 K. T. Shenoy3
•
•
Received: 16 February 2015 / Accepted: 9 May 2015
Ó Springer Science+Business Media Dordrecht 2015
Abstract Ru/c-Al2O3 nanocatalyst was synthesized by water-in-oil reverse mi-
croemulsion technique and characterized by TEM, SEM–EDX, XRD, N2 adsorp-
tion–desorption, and H2 chemisorption. The surface area and active sites (SM) of
3 wt% Ru/c-Al2O3 was obtained around 217.6 m2/g and 45.70 m2/gcat, respectively.
The catalyst performance of Ru/c-Al2O3 was assessed in the selective hydrogena-
tion benzene to cyclohexene in the presence of boric acid (BA) and ethanolamine
(EA) additives. The effect of such specific additives alone and in combination on the
activity and selectivity of benzene hydrogenation was systematically investigated.
Ru catalyst displayed pre-eminent performance at 0.5 mmol ratio of BA to EA
exhibiting the highest selectivity (40 %) and yield (16 %) of the intermediate
product, cyclohexene at 40 % of benzene conversion.
Keywords Ruthenium nanocatalyst Á Ethanolamine (EA) Á Selective
hydrogenation Á Cyclohexene Á Intermediate
&
&
1
S. U. Nandanwar
sunandanwar@gmail.com
M. Chakraborty
mch@ched.svnit.ac.in
Department of Chemical Engineering, S.V. National Institute of Technology,
Surat 395 007, Gujarat, India
2
Discipline of Inorganic Materials and Catalysis, Central Salt and Marine Chemicals Research
Institute (CSMCRI-CSIR), Bhavnagar 364 021, Gujarat, India
3
Chemical Engineering Division, Bhabha Atomic Research Center (BARC),
Mumbai 400 085, Maharashtra, India
123

S. U. Nandanwar et al.
Introduction
Benzene hydrogenation has significant importance in the petrochemical industry
due to stern environmental regulations established worldwide for the presence of
aromatics in fuels [1–5]. Hydrogenation of benzene produces two products
cyclohexene and cyclohexane. Cyclohexene is the intermediate product. Conven-
tionally, benzene is difficult to hydrogenate due to the resonance stabilization
energy and occurs under drastic temperature/pressure over a metal-supported
heterogeneous catalyst [6]. The two types of strategies can be realized for the
benzene hydrogenation: (1) to develop efficient catalyst systems to hydrogenate
benzene under mild conditions [7–9], and (2) to enhance the selectivity of
cyclohexene, i.e. selective hydrogenation of benzene to cyclohexene [10–29].
Generally, cyclohexene can be produced by different processes like cyclohexanol
dehydrogenation, dehydrogenation of cyclohexane and dehydrohalogenation of
cyclohexane halide but suffer from the lower efficiency and complicity to recover
the product [18, 30].
Among the reported catalysts in the literature for benzene hydrogenation
[10–31], a ruthenium-based catalyst has been indicated as being more effective than
other metal catalysts, while the addition of a second transition metal, metal salt,
NaOH, or ionic liquids are necessary to enhance cyclohexene selectivity [18–27].
Liu et al. [16] developed a novel Ru/ZnO–ZrOx(OH)y catalyst and reported 56 %
yield and 76 % selectivity of cyclohexene. Schwab et al. [25] carried out
hydrogenation of benzene using a Ru/c-Al2O3 catalyst in the presence of ionic
liquids, [B3MPyr][DCA] and achieved 11 % yield with 60 % selectivity. Zanutelo
et al. [26] reported that the catalytic performance of a Ru/C system was influenced
by functional groups (e.g. carbonyl, carboxylic group) present on the activated
carbon surface. Zhou et al. [27] reported that Ru–B/ZrO2–T produced 47 % yield
and 56 % selectivity of cyclohexene. Spinace and Vaz [28] reported that 14 % and
60 % yields of cyclohexene and conversion of benzene were obtained, respectively,
at 423 K and 5 MPa of hydrogen pressure using a Ru/SiO2 catalyst. A water–
organic mixture such as ethylene glycol/water and glycerol/water, which consist
mainly of hydrated organic molecules, can enhance the hydrophilicity around the
ruthenium particles favoring cyclohexene desorption. Schwab et al. [29] reported
70 % selectivity of cyclohexene using a Ru/La2O3 catalyst in the presence of a
small amount of sodium dicyanamide (NaDCA). The Ru–B/TNS catalyst enhances
the catalytic performance toward the selective hydrogenation of benzene to
cyclohexene, yielding 50.7 % cyclohexene without any additives [33]. Recently,
Wu et al. [34] reported that the addition of a small amount of ZnO in a NaOH
solution effectively enhanced the selectivity to cyclohexene and the yield of
cyclohexene could reach 41.5 % over a Ru/TiO2 catalyst.
A great deal of progress has been made in the recent past by developing inorganic
salts, additional transitional metal and expensive ionic liquid free catalyst systems
for selective benzene hydrogenation. The present work describes noncorrosive,
inexpensive and efficient catalyst system for selective hydrogenation of benzene. In
this context, Ru/c-Al2O3 nanocatalyst, synthesized by water-in-oil (w/o)
123

Partial hydrogenation of benzene to cyclohexene over…
microemulsion, was used in presence of BA and EA as task-specific additives.
Effect BA to EA molar ratio and different other organic additives on selective
hydrogenation of benzene in presence of BA were also studied.
Materials and methods
Materials
Ruthenium trichloride (RuCl3ÁnH2O, Ru content C37 %), cyclohexane and acetone
were purchased from Finar Chemicals, India. Benzene was purchased from
Qualigens Fine chemicals, India. Sodium borohydride (NaBH4, 95 %), boric acid
(BA), ethanolamine (EA) and polyoxyethylene octyl phenyl ether (Triton X-100)
were purchased from S.D. Fine Chemicals, India. The support, c-alumina powder,
Al2O3 of 98 % purity and 100 mesh size was purchased from National Chemicals,
India. All chemicals were used without further purification. Distilled water
(Millipore, Elix, India) was used throughout the experiments.
Synthesis of supported Ru/c-Al2O3 catalyst
Ru nanoparticles were synthesized by w/o reverse microemulsion technique
comprising cyclohexane, Triton X-100 as surfactant, aqueous solution of salt,
RuCl3 and reducing agent, NaBH4, as reported [35]. A 1–5 wt% Ru/c-Al2O3
nanocatalyst was synthesized by transferring the Ru nanoparticles onto the support
to maintain the homogeneous distribution. The concentrated colloidal Ru nanopar-
ticles (accumulated after repeated experimentation) were re-dispersed in methanol,
and a known quantity of c-Al2O3 support was added under vigorous stirring. The
mixture was mechanically stirred (6500 rpm using Ultraturax) for 24 h. After
evaporating the methanol, the mixture was washed with acetone and water to
remove the organic and inorganic impurities, and dried at 100 °C for 6 h.
Ruthenium nanoparticles supported on c-alumina (dark brown colour powder) were
calcined at 300 °C for 8 h in an oven.
Catalytic reaction
Partial hydrogenation of benzene was carried out in a 100 mL stainless steel
autoclave (model E 01055A; Autoclave Engineers, USA) equipped with a
controlling unit. The high-speed magnetic stirrer was adjusted to 1500 rpm. In a
typical experiment, 5 mL benzene (56.33 mmol), 15 mL solvent, aqueous and
synthesized catalyst, and 100 mg Ru/c-Al2O3 were charged into the reactor. Before
starting the reaction, the autoclave was flushed with nitrogen three times, followed
by flushing with hydrogen twice at room temperature, after which the autoclave was
brought to the reaction temperature and pressurized with hydrogen at the desired
pressure. After reaching the suitable temperature and pressure, the reaction was
started. After 30 min reaction time, the stirring was stopped and autoclave was
cooled in an ice bath. The catalyst was recovered by filtration, and the liquid was
123

S. U. Nandanwar et al.
separated into two layers in aqueous and oil. The product was analysed by GC
(Shimadzu 17A, Japan) with a flame ionization detector (FID). A 5 % diphenyl and
95 % dimethyl siloxane universal capillary column (60 m length and 0.32 mm
diameter) was used to analyze the reactant and product. The product was analyzed
by GC (Shimadzu 17A, Japan) with FID. The initial column temperature was
increased from 40 to 200 °C at the rate of 10 °C/min. N2 gas was used as a carrier
gas. Conversion of benzene (CBenzene), selectivity of cyclohexene (SCyclohexene) and
yield of cyclohexene (YCyclohexene) were calculated by the following equation:
Mole of reacted benzene
% CBenzene
¼
 100
ð1Þ
ð2Þ
ð3Þ
Mole of initial benzene
Mole of cyclohexene formed
Mole of reacted benzene
% SCyclohexene
¼
 100
 100
Mole of cyclohexene formed
¼
Mole of initial benzene
% YCyclohexene
Characterization
The surface morphology and size of the Ru/c-Al2O3 catalyst was analyzed by using
transmission electron microscopy (TEM) (JEOL, JEM 2100) and scanning electron
microscopy (SEM–EDX) (LEO SUPRA 35VP). Powder X-ray diffraction (P-XRD)
measurement of supported Ru/c-Al2O3 was carried out using a Philips X’Pert-MPD
diffractometer employing Ni-filtered Cu Ka radiation with 40 kV and 30 mA at a
scanning rate of 5°/min. N2 adsorption–desorption were measured at liquid nitrogen
temperature by a Micromeritics ASAP 2010. The specific active metal surface area
was determined by hydrogen chemisorption using an Autochem 2920 Chemisorp-
tion analyzer (Micromeritics, USA).
Results and discussion
Characterization of Ru/c-Al2O3 nanocatalyst
A TEM image of the 3 wt% Ru/c-Al2O3 catalyst is shown in Fig. 1. It was observed
that monodispersed and spherical-shaped ruthenium nanoparticles, which were
obtained by the water-in-oil microemulsion method, were highly dispersed on the
support, c-Al2O3. The average size of the ruthenium nanoparticles was in the range
of 10–20 nm. SEM–EDX was performed in order to study the morphology and
elemental distribution of the synthesized 3 wt% Ru/c-Al2O3 nanocatalyst (Fig. 2).
Figure 2a represents the view of the sample at 12.93 KX magnification (Ru
nanoparticles were not clearly visible and might be the white spots), and tiny
ruthenium nanoparticles cover the whole surface of the support, c-Al2O3. EDX
indicated the presence of ruthenium, aluminium and oxygen on the surface of the
123

Partial hydrogenation of benzene to cyclohexene over…
Fig. 1 TEM image of 3 wt% Ru/c-Al2O3 catalyst
catalyst, no other peak was observed, which indicates that the purity of catalyst was
very high (Fig. 2b).
Powder X-ray diffraction (P-XRD) of pure c-Al2O3 and 3 wt% Ru/c-Al2O3
catalyst are represented in Fig. 3. The highest peak of alumina was observed at
2h = 67.5 (Fig. 3a). The smaller peaks of ruthenium were observed due to low
content of Ru mainly present on the surface of the support (Fig. 3b). The diffraction
peaks at 2h = 44.7° can be attributed to metallic ruthenium which represented (101)
planes of the crystal structure of ruthenium metal. The size of the ruthenium
nanoparticles was calculated by the Debey Scherrer formula; it was close to the
average diameter (16.7 nm) observed by TEM analysis. A new peak appeared at
2h = 288 and was assigned to RuO2 due to the oxidation of air at the time of drying
of the catalyst [11].
The nitrogen adsorption–desorption of 3 wt% Ru/c-Al2O3 catalyst curve is
shown in Fig. 4. It can be concluded from the hysteresis curves that the shape of the
pores of this catalyst was capillary cubic with both sides open and the pore size
distribution ranged from 4 to 57 nm. The relative pressure (P/P0) at the separate
region in the adsorption curve and desorption curves was 0.4. BET surface area of
the 3 wt% Ru/c-Al2O3 catalyst was 217.6 m2/g. It was found to be higher when
associated with 1–2 wt% Ru loading (not shown). The metal surface area (SM) and
ruthenium dispersion of the catalyst was determined by hydrogen chemisorption, as
presented in Table 1. It was observed that 4 wt% Ru/c-Al2O3 catalyst has maximum
active sites (1 % more than 3 wt% Ru loading), but metal clusters were observed
due to agglomeration of the particles [36]. Prior to that, 3 wt% Ru/c-Al2O3 has
123

S. U. Nandanwar et al.
Fig. 2 (a) SEM analysis and (b) EDX analysis of 3 wt% Ru/c-Al2O3 catalyst
similar active sites (SM = 45.70 m2/gcat) for the reaction. Therefore, the 3 wt% Ru/
c-Al2O3 prepared catalyst was selected for partial hydrogen of benzene to
cyclohexene.
Effect of amount of boric acid and ethanolamine
The selective hydrogenation of benzene to cyclohexene is a complex process and,
usually, Zn salts are added to enhance cyclohexene selectivity. It is also reported
123

Partial hydrogenation of benzene to cyclohexene over…
Fig. 3 Powder—XRD of (a) c-Al2O3, (b) 3 wt% Ru/c-Al2O3 catalyst
Fig. 4 Nitrogen adsorption–desorption isotherm for 3 wt% Ru/c-Al2O3 catalyst
that the addition of various organic additives to Zn salts such as ethanolamine,
diethanolamine, PEG-6000 and 1,3-propanediol, i.e. combination of both, aug-
mented cyclohexene selectivity more than their counterparts [11]. Such organic
additives and inorganic salts are dissolved in the aqueous phase to increase the
hydrophilicity of the catalyst and reduce the solubility of cyclohexene, which
precludes further cyclohexene hydrogenation. Moreover, the interaction between N
or O atoms of organic additives with ruthenium assists the desorption of
123

S. U. Nandanwar et al.
Table 1 Hydrogen chemisorption of Ru/c-Al2O3 catalyst
Sr. No.
Ru (wt%)
Supported metal surface area
per g of catalyst (SM, m2/gcat
)
1
2
3
4
5
1
2
3
4
5
22.53887
35.68495
45.69873
46.17428
10.14869
cyclohexene, crucial for enhancing the selectivity toward cyclohexene. On the other
hand, boron-modified Ru/Al2O3 catalyst, especially the colloidal RuB/Al2O3ÁxH2O
catalyst, displayed high activity and cyclohexene selectivity in the hydrogenation of
benzene due to the existence of structural water and surface hydroxyl groups on the
RuB/Al2O3ÁxH2O catalyst [37]. Encouraged by the above results and to replace Zn-
based inorganic salts, we selected specific additives, boric acid B(OH)3 (BA) and
ethanolamine (EA).
The influence of such specific additives alone and in combination on the activity
and selectivity of benzene hydrogenation was systematically investigated using the
most commonly used Ru/c-Al2O3 catalyst (with 3 wt% of Ru) in aqueous. Addition
of BA, a mild acidic in nature, considerably increased the conversion of benzene
although obvious selectivity to cyclohexene was not realized (Table 2). In the
absence of any additives, the hydrogenation of benzene catalyzed by Ru/c-Al2O3
showed 38 % conversion without the formation of cyclohexene in water due to a
faster rate of conversion to cyclohexane. When a small amount of BA, 0.74 mmol,
was introduced into the system, benzene conversion increased from 38 to 49 %
(entry 2), but 0.8 % selectivity of cyclohexene was observed. The opposite trend
was observed in the case of EA, with the addition of 1.47 mmol of EA resulting in a
decrease in the conversion of benzene from 38 to 34 % (entry 3), and increased the
selectivity of cyclohexene up to 16 %. From the individual results of BA and EA, it
can be concluded that the catalytic activity was influenced by BA while EA affected
Table 2 Effect of amount of boric acid (BA) and ethanolamine (EA) on selective hydrogenation of
benzene to cyclohexene
Entry
BA (mmol)
EA (mmol)
BA/EA
mmol ratio
% CBenzene
% Scyclohexene
% Ycyclohexene
1
2
3
4
5
6
0
0
0
38
49
34
41
45
48
0
0.8
16
25
27
23
0
0.74
0
0
–
0.7
1.47
1.47
1.47
1.47
–
5.4
0.147
0.74
1.47
0.1
0.5
1.0
10.2
12.1
11.0
Reaction conditions: temp. = 150 °C, H2 pressure = 5.0 MPa
123

Partial hydrogenation of benzene to cyclohexene over…
the cyclohexene selectivity. The surprising result was observed when both BA to
EA were added into the system (entries 4–6). The mmol ratio of BA to EA was
varied from 0.1 to 1. The conversion of benzene increased constantly (41–48 %)
with an increased mmol ratio of BA to EA from 0.1 to 1.0, whereas the selectivity
and yield of cyclohexene increased from 0.1 to 0.5. The selectivity and yield of
cyclohexene attained up to 27 and 12 %, respectively, at 0.5 mmol ratio of BA to
EA (entry 5). Therefore, further reaction optimizations were carried out at 0.5 mmol
ratio of BA to EA. The selectivity and yield of cyclohexene were increased with an
increase in the amount of BA and EA at 0.5 mmol ratio. The highest cyclohexene
selectivity (40 %) and yield of cyclohexene (16 %) were achieved at 1.44 mmol of
BA and 2.88 mmol of EA with a concentration mmol ratio of 0.5 at 40 %
conversion of benzene (Table 3, entry 3). The question remains as to why the BA
and EA combined at 0.5 mmol ratio causes such an enhancement in the selectivity
and yield of cyclohexene. The exact reason is not yet clear, but the authors think that
BA enhanced the activity of the catalyst resulted in a higher rate of reaction and
proportionally the EA increased the hydrophilicity of the catalyst that controlled the
rate of reaction.
Effect of organic additives
The influence of organic additives on the Ru-based catalyst for hydrogenation of
benzene by keeping BA concentration constant is shown in Table 4. In the absence
of any organic additives, the conversion of benzene up to 49 and 0.5 % selectivity
was observed (entry 1). EA imparted pre-eminent cyclohexene selectivity (27 %)
and yield (12 %) at 45 % conversion of benzene in the presence of boric acid at BA/
EA = 0.5 (entry 2). But some amine groups did not show promising results (entries
3–6). The alcoholic additives were not very effective (entries 7–9) for selective
hydrogenation of benzene. In all cases, no cyclohexene was formed. From the above
results, it can be concluded that the presence of both free amine (–NH2) and free
hydroxy (–OH) groups in organic additives are necessary for high cyclohexene
selectivity compared to organic additives having substituted amine or hydroxy
groups alone.
The pre-adsorption of additives on the surface of ruthenium could enhance the
selectivity to cyclohexene. It has been proposed that the formation of a hydrogen
bond (-3 to -5 kJ/mol) between cyclohexene and a modifier molecule weakened
Table 3 Effect of BA/EA—0.5 molar ratio amount on selective hydrogenation of benzene
Entry
BA (mmol)
EA (mmol)
% CBenzene
% SCyclohexene
% YCyclohexene
1
2
3
4
0.37
0.74
1.44
2.16
0.72
1.44
2.88
4.32
49
45
40
25
12
27
40
36
5.9
12.1
16
9
Reaction conditions: temp. = 150 °C; H2 pressure = 5.0 MPa
123

S. U. Nandanwar et al.
Table 4 Effect of different organic additives on selective hydrogenation of benzene in the presence of
boric acid
Entry
Organic additive
% CBenzene
% SCyclohexene
% YCyclohexene
1
2
3
4
5
6
7
8
9
–
49
45
63
71
69
70
73
73
74
0.5
27
12
5
0.3
12.1
7.6
3.7
2.4
1.5
0
Ethanolamine
Diethanolamine
Triethanolamine
Dimethyl ethanolamine
Diethyl ethanolamine
Diethylamine
Triethylamine
Ethanol
3
2
0
0
0
0
0
Reaction conditions: boric acid = 0.74 mmol; organic additive = 1.44 mmol; temp. = 150 °C; H2
pressure = 5.0 MPa
the overlap of the p-electrons of the C=C double bond in the cyclohexene molecule
with the d orbital of ruthenium, so that it caused the hydrogen-bonded cyclohexene
to desorb rapidly on the surface of the ruthenium and improved the selectivity to
cyclohexene [38, 39]. The additive EA is completely soluble in water and has a high
boiling point, and this additive forms a strong interaction with the ruthenium metal
Fig. 5 Effect of temperature on selective hydrogenation of benzene to cyclohexene at BA/EA mmol
ratio = 0.5, H2 pressure = 5 MPa
123

Partial hydrogenation of benzene to cyclohexene over…
catalyst. The metal components and the EA interact creating a water layer around
the active metal centers, which might be an important reason for the enhancing of
the selectivity toward cyclohexene. Due to the interaction between EA and
ruthenium, the electron transfer from N or O to d orbital of ruthenium probably
occurs and makes ruthenium become an electron-riched center, in which the
desorption of cyclohexene becomes easy [11].
Effect of temperature
The temperature of the reaction was varied from 110 to 160 °C at constant hydrogen
pressure (5.0 MPa) (Fig. 5) keeping the BA/EA mmol ratio at 0.5 (1.44 mmol BA
and 2.88 mmol EA). With the increase of reaction temperature from 110 to 150 °C,
there was an increase of the selectivity of cyclohexene from 7 to 40 %, but it was
dropped to 18 % at 160 °C. Wang et al. [18] suggested that the solubility of benzene
and cyclohexene increased in a stagnant water film around the catalyst with raising
the reaction temperature, which resulted in the enhancement of the rate of
cyclohexene hydrogenation. Also, Struijk et al. [40] suggested that the higher
reaction temperature ([150 °C) facilitated the desorption of cyclohexene and
hydrogen from the catalyst surface. The best performance for the hydrogenation of
benzene to cyclohexene was optimized at 150 °C.
Fig. 6 Effect of pressure on selective hydrogenation of benzene to cyclohexene at BA/EA mmol
ratio = 0.5; temp. = 150 °C
123

S. U. Nandanwar et al.
Effect of pressure
The effects of hydrogen pressure on the conversion of benzene and selectivity of
cyclohexene were studied between 1 and 6 MPa at 150 °C and mmol ratio BA/
EA = 0.5 (1.44 mmol BA and 2.88 mmol EA) (Fig. 6). The selectivity of
cyclohexene was increased with an increase in the hydrogen pressure, whereas
the benzene conversion was increased gradually with the increase in the hydrogen
pressure. The selectivity of cyclohexene at 5 MPa was highest (40 %) compared
with the other hydrogen pressures, but, above 5 MPa, the selectivity of cyclohexene
decreased. This could be attributed to a decrease in the adsorption of benzene on the
catalyst surface due to the excessive coverage of hydrogen on the surface [40].
Moreover, the hydrogenation of cyclohexene to cyclohexane is facilitated at high
pressures [16, 42]. As a result, the yield of cyclohexene decreases at high hydrogen
pressure, corresponding to 6 MPa in the pressure range studied. The results indicate
that 5 MPa is an optimum pressure which gives the highest selectivity of
cyclohexene.
Conclusions
From present work, it was observed that fine-tuning with both and BA and
ethanolamine (EA) would improve the yield and selectivity of the intermediate
product. Though the obtained result showed a lower yield (16 %) and selectivity
(40 %) compared to other reported data, our noncorrosive, inexpensive and efficient
catalyst system has proven to be an effective green catalytic process for selective
hydrogenation of benzene to cyclohexene.
Acknowledgment The authors wish to acknowledge the Board of Research in Nuclear Science
(BRNS), Mumbai, India, for financial support through Project Ref. No. 2011/36/02-BRNS/0080.
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