Preparation of NiO Nanocatalyst Supported on MWCNTs and Its Application in Reduction of Nitrobenzene to Aniline in Liquid Phase

Article abstract of DOI:10.1080/15533174.2013.862646

In this research NiO nanoparticles supported on multiwalled carbon nanotubes (MWCNTs) and activated carbon were prepared and applied as nanocatalyst in hydrogenation of nitrobenzene (NB) to aniline (AN). The nanocatalysts were prepared via homogenous depo

Full text of DOI:10.1080/15533174.2013.862646

Synthesis and Reactivity in Inorganic, Metal-Organic, and
Nano-Metal Chemistry
ISSN: 1553-3174 (Print) 1553-3182 (Online) Journal homepage: http://www.tandfonline.com/loi/lsrt20
Preparation of NiO Nanocatalyst Supported on
MWCNTs and its Application in Reduction of
Nitrobenzene to Aniline in Liquid Phase
Majid Hashemi, Mohammad Mehdi Khodaei, Mohammad Teymouri,
Alimorad Rashidi & Hadi Mohammadi
To cite this article: Majid Hashemi, Mohammad Mehdi Khodaei, Mohammad Teymouri,
Alimorad Rashidi & Hadi Mohammadi (2016): Preparation of NiO Nanocatalyst Supported
on MWCNTs and its Application in Reduction of Nitrobenzene to Aniline in Liquid Phase,
Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, DOI:
10.1080/15533174.2013.862646
To link to this article: http://dx.doi.org/10.1080/15533174.2013.862646
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Date: 10 January 2016, At: 06:06

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Preparation of NiO Nanocatalyst Supported on MWCNTs and its Application in
Reduction of Nitrobenzene to Aniline in Liquid Phase
a,b
*a
*c
d
Majid Hashemi , Mohammad Mehdi Khodaei , Mohammad Teymouri , Alimorad Rashidi
,
Hadi Mohammadi
a
Faculty of Chemistry and Nano science & Nanotechnology Research Center (NNRC), Razi
University, Kermanshah, 67149 IRAN
b
Center for Research and Development of Petroleum Technologies at Kermanshah, Kermanshah,
IRAN
c
Campus Research for Down Stream Industries, Research Institute of Petroleum Industry (RIPI),
Tehran, IRAN
d
Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), Tehran,
IRAN
e
Young Researchers Club, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran.
*
Corresponding author. E-mail: mmkhoda@razi.ac.ir
Abstract
In this research NiO nanoparticles supported on multi-walled carbon nanotubes (MWCNTs) and
activated carbon (AC) were prepared and applied as nanocatalyst in hydrogenation of
nitrobenzene (NB) to aniline (AN). The nanocatalysts were prepared via homogenous deposition
precipitation (HDP) from nickel nitrate hexahydrate using urea as reducing agent and polyvinyl
alcohol (PVA) and polyvinyl pyrolidione (PVP) as dispersant agents in aqueous media. The
nanocatalysts were characterized by FT-IR, SEM, XRD, TEM, TPR and BET. The results show
that the yield of reduction reaction of nitrobenzene (NB) to aniline (AN) in 140C and hydrogen
1
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pressure of 12 bars was 99.5% with 100% selectivity of aniline. Also the NiO/MWCNTs have
more catalytic activity than NiO/AC in nitrobenzene hydrogenation.
Keywords
Hydrogenation, Carbon Nano Tubes (CNTs), Nickel, Nanocatalyst
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1
. Introduction
Aniline is an important substance for chemical industrial such as rubber process, dyes and
pigments, pesticides, herbicides and production of Methylene Diphenyl Isocyanate (MDI). There
are several methods for the synthesis of aniline using a variety of starting materials which
nitrobenzene is the classical and the most frequently used feedstock. In the small scale, aniline
can be produced by the chemical reduction of nitrobenzene with use of iron in the presence of
HCl (Bechamp reaction) [1, 2].The major problem of iron-acid reduction is generation of large
amounts of Fe-FeO sludge. Aniline is mostly produced via hydrogenation of nitrobenzene (about
8
5%) and electrochemical synthesizing method [3-5]. Hydrogenation of nitrobenzene was
studied over Pd-B/SiO amorphous catalyst [6], Pd/C [7], Pt/CNT [8] and1% Pd supported on
hydrotalcite MgO and γ-Al at 225-300 °C [9]. Some of other researches on hydrogenation of
2
2
O
3
nitrobenzene in liquid phase [10-20] are summarized in Table 1.
Carbon nanotubes (CNTs) which was synthesized by Ijima in 1991 [21,22] have been used as a
novel catalyst support in both heterogeneous and electrocatalyst [23-25] as well as they are
efficiently used as a support material of fuel cell catalysts like Pt and Pt-based alloys [26-35]
which are essentially insoluble in most solvents. The small dimensions, good mechanical
strength, high external surface area and the remarkable physical properties of these structures
make them as a very unique material with a whole range of promising applications [36, 37].
Different CNTs supported catalysts such as Ru, Pt, Rh and Pd have shown good activity and
selectivity in a variety of chemical reactions, which was generally attributed to the improved
metal-support interaction and mass transfer [38-41].
3
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In this research a simple method is reported to preparation of high loaded NiO nanoparticles on
MWCNTs and activated carbon by reaction between acidic Ni precursor and urea as mild
reducing agent. PVA and PVP were used as dispersant agent to prevent agglomeration. Finally,
the resultant was calcinated and converted to NiO/MWCNTs and NiO/AC and used in
nitrobenzene hydrogenation under mild and different conditions with high conversion and
selectivity.
2
. Experimental
2
.1. Chemicals and equipment
All the reagents were obtained from commercial available purity. Multi-walled carbon
nanotubes with purity more than 95% were purchased from Research Institute of Petroleum
2
Industry (R.I.P.I) with surface area of 270 m /g, 10μm length and 10-30 nm diameter. The
Transition Electron Microscopy (TEM) images were taken on a Philips ZEISS EM900 at an
accelerating voltage of 100 KeV and SEMs were conducted with SEM-XL30- Philips
instrument. Thermogravimetric analysis (TGA) were taken on a METTLER TOLEDO TGA
SDTA 851e instrument at 30-800 °C with 10 °C/min. BET surface area of NiO/AC and
supported NiO/MWCNTs were determined by QUANTASORB at 300 °C in the presence of N
2
and He. X-ray powder diffraction (XRD) analysis was conducted by Philips instrument with
graphite monochromatic Cu Kα radiation (λ = 1.5418 Å) to verify the formation of products. The
UV-Vis spectrum of reaction was recorded on a SINCO UV-Vis 1100 diode array in the range of
1
90-1100 nm. Temperature Programmed Reduction (TPR) of NiO/MWCNTs were recorded at
the temperature range of 20-800 °C, at a heating rate of 10 °C/min using a Micrometrics 2900
4
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system. Gas chromatography (GC) was carried out by SRI 8022C instrument with FID detector
and MXT-624 capillary column (0.53 mm in diameter and 30 m long).
2
-3. Preparation of NiO nanoparticles in the presence of PVP and PVA as dispersant agents
For preparation of NiO nanoparticles, 2.9 g of nickel nitrate hexahydrate (10 mmol) and 0.5 g of
PVA in 200 ml deionized water were heated to 90 °C and stirred until transparent solution was
obtained, and then an aqueous solution (10 ml) containing 0.92 g (15 mmol) of urea was added
to solution in 1 hour at the same temperature. The mixture was refluxed overnight, and then the
resultant light-green precipitant was filtered and washed with deionized water for 5-10 times to
remove any remained unreacted starting materials. The solid was dried at 150 °C for 2 h, heated
to 250 °C for 2 hours; finally it was increased to 400 °C and remained at this temperature for 3
hours to obtain black green solid nickel oxide. Particle size of NiO was calculated by Scherrer
Equation. Different nanoparticles with 5.3-9.6 were obtained in the presence of different
amounts of PVA nd PVP as dispersant agent and results are illustrated in Table 2. It is found
from these results that the amount and kind of dispersant agent can control the particle size of
NiO nanoparticles.
2
-2. Preparation of 58% NiO/MWCNT
The multi-walled carbon nanotubes was synthesized previously through a special chemical
vapor deposition (CVD) method by decomposing of methane on Co-Mo/MgO catalyst at a
temperature of 1000 °C [42,43]. The high purity MWCNTs were obtained through (I) acid
treatment to dissolve remained metal catalysts impurities (II) oxidation to remove amorphous
carbons. Initially, MWCNTs immersed in 18% HCl solution and stirred at 55 °C for 12 h, then
5
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treated in 6M nitric acid (HNO ) at 50 °C for 6 h and finally filtered and washed filtrate with
3
distilled deionized water until pH reached neutral. The residue dried at 100 °C for 3 h, and then
resultant MWCNTs were oxidized at 400 °C for 20 min to burn out all amorphous carbons.
Preparation of NiO on MWCNTs and AC carried out similar to NiO preparation in the
presence of 0.5 g of PVA. To dispersing of supports in solution, the reaction sonicated for 10
min. Thermal decomposition and calcinations process was performed with purging of reactor
under N
2
for 10 min to prevent support damaging The catalysts at loading of 20, 40 and 60% of
NiO were prepared on supports.
2
-3. Hydrogenation of Nitrobenzene
At first, 0.1 g of NiO/MWCNTs nanocatalyst was introduced to the 100 ml stainless steel
-
1
autoclave reactor and reduced by 100 ml.min of H
the room temperature, 1 ml of nitrobenzene and 10 ml of toluene as solvent were added to the
reactor under N Atmosphere. In order to remove any oxygen, the mixture purged with N for 10
2
at 400 °C for 1 h. After gradual cooling to
2
2
min. The reaction carried out in different pressure, temperature, time and loading of active
catalyst. Yield of reaction was determined using gas chromatography (GC) with flame ionization
detector (FID).
3
. Resaults and discussion
3
-1. Synthesis of NiO nanocatalyst
The catalysts were prepared via homogenous deposition precipitation (HDP) method by using of
urea as precipitant agent. Urea hydrolyzed slowly at above 90 C in aqueous media as shown in
below.
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T90C
(
1)
CO(NH ) +3H O CO +2NH OH
2
2
2
2
4
+
2
As slow formation of hydroxyl regarding to slow rate of urea decomposition in solution, Ni
ions are free to be dispersing by PVA and PVP then react slowly with hydroxyl ions to produce
the bright green precipitates. The probably formula of the solid precipitate was identified as
Nickel Carbonate Hydroxide Hydrate NiCO
3
·Ni (OH)
2
·4H O and it completely converted into
2
NiO nanoparticles below 450 C [44].
As illustrated in Figure 1, the end of the reaction was determined by Uv-Vis spectrum of solution
that the peak of nickel ions was disappeared in 466.7 nm.
The bright green solid filtered and washed with water to remove any remained dispersant
agent and impurities, then dried at oven for 4 h at 100 °C. Then NiO nanoparticles were prepared
and Calinated simultaneously according to the following procedure. The solid precipitates were
introduced to the reactor, heated to 150C and hold for 1.5 hours. Then the mixture gradually
heated to 250 C over 30 minutes and hold for 2 hours and at last, temperature rose to 400 C
and remained for 3 hours. Preparation of NiO/MWCNTs has a similar protocol but at first, the
reactor must be purged with N
2
for 10 minutes to prevent damaging of MWCNTs structure.
Decomposition steps can be summarized as follows:
1
50C/- nH O
2
NiCO . Ni(OH) · nH2O NiCO .Ni(OH)
3
2
3
2
(
(
(
2)
3)
4)
1
50250C / H O
2
NiCO .Ni

OH 2 NiCO .NiO

3
3
2
50400C / CO
2
NiCO .NiO NiO
3
3
-2. FT-IR Analysis of the synthesized substances
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The FT-IR spectra of the light green powder (dried at 105 °C for 2 h) are shown in Figure
-
1
2
a.The broad absorption band at 3300-3650 cm was attributed to the O–H bond stretching
vibrations, and the peak near 1625 was assigned to H–O–H bending vibrations of H O in
structure. This provided the evidence for the water of hydration in the structure, and it also
2
-
1
implied the presence of hydroxyl in the structure. The wide absorption band around 1384 cm
2
-
indicated the existence of CO
3
ions, and the three bands appearing around 1290, 995, and 640
-1
cm were correlated with the stretching and bending vibrations of the intercalated C–O species
2
-
in the substance. This confirmed the presence of CO
3
ions. The broad absorption bands at 2216
which derived from the powder samples prepared in air [44].
Therefore, the synthesized precursor could be the nickel salt of hydrated basic carbonates as
Ni CO
-1
cm indicated the existence of CO
2
2
3
(OH) 2.nH2O.
The FT-IR spectra of gray powder nickel oxide resulted from decomposition of nickel
-1
carbonate is shown in Figure 2(b). Remove the peaks at 3445 and 1620 cm show that the
-1
elimination of H
2
O and hydroxyl and the absence of three peaks at 1114, 833, and 620 cm
2
-
confirm the elimination of CO
3
ions in the structure of product. The strong absorption band
-1
around 410 cm was assigned to Ni–O stretching vibration which indicates the NiO was
produced. The FT-IR spectrum of NiO/MWCNTs and NiO/AC are shown in Figure 2c and 2d
respectively.
3
-3. X-ray powder diffraction (XRD)
o
The XRD pattern of pristine MWCNTs and synthesized NiO/MWCNTs in the range of 10-80
are shown in Figure 3a and 3b respectively. In Figure 4a the peak at 2θ = 26.08 can be assigned
8
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to plane of MWCNTs. In Figure 4b three characteristic peaks of nickel compound (2θ=36.89,
4
3.04, 62.50) marked by Miller indices ( (1,1,1), (2,0,0), (2,2,0) are in agreement with NiO
structure based on comparison with standard spectrum (JCPDS, NO.4-835) [44].
The mean nickel particle sizes of various samples were calculated using Debye–Scherrer
equation:
0
.9
(
5)
D

nm 


Cos
Where D is the average particle size in nm, λ the wavelength of the X-ray (1.54056Å for CuK),
θ the angle at the maximum of the peak, and β2θ is the width of the peak at half-height. The peak
of Ni (111) is used to calculation of NiO particle size in Scherrer equation for overlapping of
(
200) NiO peak with peak of pure MWCNTs. The NiO particle size calculated by Scherrer
equation is shown in Table 2.
As shown in the Table 2, the NiO Nanoparticles were in the range of 5.3-9.6 nm in different
media with use of two dispersant agents which is confirmed by TEM image. The best result was
obtained when 0.5 g of PVA was used as dispersant agent. In the absence of dispersant agents
(
PVA and PVP) the particle size of NiO is 10.2 nm. This material reduces particles size thorough
prevention of agglomeration. The excessive wideness of diffraction peaks is due to the very fine
nature of metal particles.
3
-4. BET Analysis of NiO Nanocatalyst and NiO/MWCNTs
The specific surface area of the NiO nanoproducts calculated by the BET method was 274.0,
9
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2
1
82.7 and 503.67 m /g for NiO and NiO/MWCNTs and NiO/AC respectively. The smaller size
of particles caused much higher external surface area of NiO nanoparticles. The larger external
surface area of a catalyst and mesoporous structure of support, enhanced chance of hydrogen
absorption, better mass transfer and lead to higher activity of NiO/MWCNTs in comparison with
2
NiO/AC that has higher surface area (503.67 m /g). In overall, mesoporous structure of support
(
MWCNTs) and nanostructure of active metal (Ni), improved yield of reaction and caused the
reaction carried out in mild conditions including temperature, pressure and time. Result of
accelerated surface area and porosimetry (ASAP) of NiO/MWCNTs and NiO/AC are shown in
Table 3.
3
-5. Temperature-programmed reduction (TPR)
A TPR profile of NiO/MWCNTs is shown in Figure 4. The TPR was carried out in a quarts
reactor, 100 mg of catalyst sample was filled into the reactor, heated from 25 to 830 °C at the
-
1
-
rate of 10 °C.min , and swept with 95% Ar-5% H (by volume) stream at flow rate of 40 ml.min
2
1
.
The hydrogen concentration was detected by the TCD detector. Reduction of NiO to Ni active
species was happened at low temperature in 281.7 °C that can be attributed to high activity of
NiO nanostructure while NiO generally reduce at 450-550 °C. TPR analysis results of
synthesized NiO/MWCNTs nanocatalyst are shown in Table 4. From this results, the reduction
carried out in two steps: first reduction is happened at 281.7 °C that attributed to NiO (81.53%)
species and second reduction happened at 546 °C which can be assigned to remained
unconverted nickel carbonate hydroxide (18.41 %) in thermal decomposition process. TPR
results revealed that mostly of catalyst (81.5 %) is reduced at less than 300 °C.
3
-6. TEM Analysis of synthesized Nano NiO/MWCNTs
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TEM of the purified Multi-walled carbon nanotubes as a supported catalyst and NiO/MWCNTs
are shown in Figure 5a and 5b respectively. Well dispersion and deposition of nanoparticles with
weak agglomeration on MWCNTs surface is clear obvious in Figure 5b. The mean particle size
of 5.3-9.6 nm in different conditions was calculated through XRD in agreement with TEM
image. According to the TEM image, it could be concluded that this preparation method of the
precursor obtained by homogeneous precipitation with use of dispersant agent had successfully
overcome the problem of agglomeration to obtain the NiO nanoparticles below 10 nm.
3
-7. TGA and DTG analysis of NiO/MWCNTs
Thermal decomposition behavior of synthesized nanocatalyst was determined using thermal
gravimetric analyzer (TGA) in an inert atmosphere of nitrogen. In a typical experiment, 1.5 mg
of the synthesized catalyst (NiO/MWCNTs) was placed in sample pan and the temperature was
increased from 30-800 °C at a rate of 10 °C/min and weight changes were recorded as function
of temperature. Figure 6 shows TGA and DTG curves. The results show that a little loss of
weight happened at 50-100 °C due to lose of moisture in sample, and after that, there was no
obvious weight lose with further increase in temperature until 600 °C. Most of weight lose
happened upper 600 °C to 800 °C due to lose of amorphous carbon in nanotubes structure and at
8
00 °C about 83.16 % of MWCNTs structure remained. It is found that the catalyst is resistant to
thermal decomposition until 600 °C and capable to use at ambient to 600 °C in both liquid and
gas phase reactions.
3
-7. Hydrogenation of nitrobenzene to aniline
Reduction of nitrobenzene to aniline proceeds according to scheme1.
-7-1. Effect of pressure on the reaction
3
11
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Reactions were carried out in 8, 10 and 12 bars of hydrogen pressure. According to the Table 5
with 60% NiO Loading, it is obvious that 4 bars
increasing in the hydrogen
pressure, provide increasing of 58% in the yield of the reaction. At first two bars from 8-10, 66%
of reactions have increased higher than 50% while at last two bars 10-12, 33% of reactions have
such increase in reaction yield. It is revealed that first increasing in pressure(8 to 10) has more
effect on yield of reaction. Increasing in the yield is reasonable concerning to this fact that
increasing of pressure lead to increase in solubility of hydrogen in toluene which provided larger
molecular interaction of hydrogen with surface of the catalyst.
3
-7-2. Effect of temperature on yield of reaction
Reactions were carried out in 100, 120 and 140 °C. Influence of temperature on yield and rate
of reaction is listed in Table 5. As temperature is increased, the nitrobenzene conversion is found
to increase in all the pressures. It is obvious that the increasing of temperature has more effects in
shorter times (t = 60 min). Since the reaction was carried out in liquid phase and relatively low
temperature, the Coke formation is not important but water generated during the reaction may be
poised the catalyst meanwhile the hydrophobicity nature of MWCNTs aids to decrease these
phenomena. As toluene has higher vapor pressure due to its phase diagram [46], the reaction in
all conditions was carried out in liquid phase.
3
-7-2. Activity of catalyst supported on MWCNTs and AC on the reaction
The liquid phase hydrogenation of nitrobenzene to aniline was carried out over NiO/MWCNTs
2
and NiO/AC at 60% loading. Activity of NiO catalyst supported on MWCNTs with 182.7 m /g
2
surface area and activated carbon with 503.7 m /g surface area at 60% loading are presented in
12
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Table 6 and depicted in Figure 7. In spite of the NiO/AC have higher surface area than
NiO/MWCNTs (more than 2.7 times), results revealed that yield of reaction with NiO supported
on MWCNTs in all conditions almost three times higher than NiO supported on activated carbon
under similar conditions that attributed to surface mesoporosity and better mass transfer of
carbon nanotubes than activated carbon.
3
-7-1. Reaction representation in mathematics
Operating conditions have widely effects on the reaction yield. Aniline yield of reaction has been
represented in mathematical from through simplified estimating optimal transformations for
multiple regressions [47] as:
3
2
YAniline %  AX  BX CX  D
A  -0.000142
B  0.0229817
C  -0.004947
D 10
X  -175.287  0.9497 NiO Loading% 9.2647P  0.4631T  0.1813t
(
7)
This equation can estimate aniline yield of reaction with good precision (R =0.848) and accuracy
AAD% = 17.32). The effects of parameters in equation 7 at average conditions (120 °C, 10 bar,
80 min) for NiO loading at 20, 40, and 60% are shown in Figure. 8. Results revealed that
2
(
1
increasing of pressure, NiO loading and temperature lead to higher yield and conversion over
shorter time. However, regarding to this figure and equation 7, it is clear that pressure has most
important effect. NiO loading percent, temperature and time almost have the same effects.
Conclusion
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In this research, we have demonstrated that the NiO/MWCNTs nanocatalyst is very efficient and
active catalyst for reduction of nitrobenzene in liquid phase with a 99.5 % yield and selectivity
toward aniline. The activity of catalyst depends on type of support so that the yield of reaction
with NiO supported on MWCNTs in best conditions were three times more active than the
catalyst supported on activated carbon. The MWCNTs due their mesopore structures perform
better mass transfer than activated carbon with micropore structure. In comparison to other
methods reported in the literature, our novel methodology in nanocatalyst preparation has mild
conditions, high isolated yields and high conversion without any by products, clean reactions,
easy workup and reusability of the used catalyst. All these features make this method as
attractive and useful alternative in catalytic preparation of aniline.
Acknowledgments
The authors thank the Razi University Research Council and research institute of petroleum
industry (RIPI) for financial support of this work.
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Table 1. Reduction of nitrobenzene to aniline using various catalysts in liquid phase
ttCatalyst
conditions
%Conv %
AN
Time
Ref
a
Pd
Pt
PMHS /KF/THF, RT
90-100
100
90
50
99
0.5-12h
2h
10
11
12
13
10 bar, RT-50C
b
Rh
Re
RhCl(PPh3)
ReIO (PPh
3
, Toluene,TES
86
2h
2
3
)
2, PhMe
2
SiH, Toluene,
80
100
4h
Reflux
5
Pd or Pt
Pt/c
Pt/glass fiber 7×10 Pa, 50C
100
73
100
56
50min
30min
4 h
14
15
16
17
18
40 bar,35C
Sn
Sn/HCl, C
Mo(CO) , EtOH, Reflux
CO2: 400bar, H :20-60 bar,EtOH,
2
H
5
OH, Reflux
80
60
Mo
6
-
54
24 h
Ni/Al
2
O
3
2
13-73
62-
99
20 min
Reflux
Ni/TiO
Fe
2
20bar, 140C
99
80
100
99
4h
19
20
Fe(acac)
3
/N
2
H
4
/MeOH, Microwave,
50C
Toluene, 12bar, 140C
10 min
1
NiO/MCNTs
100
100
4h
This
article
a: Polymethylhydrosiloxane
b: triethylsilane( Et SiH)
3
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Table 2. Particle size of NiO in different media with use of 0.05 M of Ni (NO
3
)
2
.6H O
2
Run Conc. of disp.agent as g/200 ml PVA PVP
Particle Size( nm)
1
2
3
4
5
6
7
-
-
+
+
+
-
-
-
10.2
5.3
5.6
6.3
8.6
9.1
9.6
0.5
1.0
2.0
0.5
1.0
2.0
-
-
+
+
+
-
-
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Table 3. Accelerated surface area and porosimetry (ASAP) of synthesized catalysts
Catalyst
BET
Pore
Volum A.P.D( A
)
A.A.P.D ( D.A.P.D( A
A
)
2
3
m /g
(cm /g)
)
NiO/MWCNTs
NiO/AC
182.71
503.67
0.56
0.35
121.59
37.79
117.9
71.8
106.54
66.24
A.P.D= Average Pore Diameter(4V/A by BET)
AAPD= Adsorption Average Pore Diameter(4V/A)
DAPD= Desorption Average Pore Diameter(4V/A)
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Table 4. Results of TPR analysis
Peak
Area
Height
1923.4
1032.1
Temp(°C)
281.7
Time
sec)
Total
Total
(
Qty,Unit
Qty/g,Unit
1
2
6.930E+05
1.571E+05
1406
0.30 mmole 5.58 mmole H
2
2
/g
/g
H
2
546.0
2756
0.12 mmole 2.32 mmole H
H
2
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Table 5. Nitrobenzene hydrogenation with different loadings of NiO/MWCNTs
°
Entry NiO/MWCNTs
Loading %
Pressure(bar T( C) time(min) Yield(Aniline)
)
%
1
2
3
4
5
6
7
8
9
20
20
20
20
20
20
40
40
40
40
40
40
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
10
10
10
12
12
12
10
10
10
12
12
12
8
8
8
8
8
8
8
8
8
10
10
10
10
10
10
10
10
10
12
12
12
12
12
12
120
120
120
140
140
140
120
120
120
140
140
140
100
100
100
120
120
120
140
140
140
100
100
100
120
120
120
140
140
140
100
100
100
120
120
120
60
180
300
60
180
300
60
180
300
60
180
300
60
180
300
60
180
300
60
180
300
60
180
300
60
180
300
60
180
300
60
180
300
60
180
300
8.8
21.3
37.4
28.6
45.7
63.8
19.6
66.4
84.9
53.2
74.6
96.5
20.2
28.2
34.3
28.8
37.6
43.1
42.5
53.2
65.7
25.1
68.2
92.5
29.1
78.3
97.2
36.8
88.2
99.0
38.1
71.2
93.5
45.5
88.1
98.1
1
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
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3
3
3
7
8
9
60
60
60
12
12
12
140
140
140
60
180
300
63.4
98.5
99.5
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Table 6. Nitrobenzene reduction using NiO suppoted MWCNTs and AC
°
a
b
Entry
T( C)
t(min)
60
180
300
60
180
300
60
180
300
Yield(AN) %
25.1
Yield(AN) %
9.3
1
2
3
4
5
6
7
8
9
100
100
100
120
120
120
140
140
140
68.2
92.5
29.1
78.3
97.2
36.8
88.2
99.0
16.5
26.3
14.2
21.3
34.1
19.5
27.8
38.5
Conditions: 1gr NB, 10 ml toluene, 0.1 gr cat.60%, 12 bar H
2
a: NiO/ MWCNTs b: NiO/AC AN: Aniline
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Scheme 1: In this reaction, three mole of hydrogen and one mole of nitrobenzene are consumed
to produce one mole of aniline and two mole of water [45]. Reaction carried out in toluene as
solvent in the presence of nanocatalyst with different loading of NiO on MWCNTs that overall
results are shown in Table 5.
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Figure 1. Uv-Vis spectrum of reaction.
27
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Figure 2. FT-IR Spectrum of (a) NiCO
3
. Ni (OH)
2
.4H O (b) NiO (c) NiO/MWCNTs (d)
2
NiO/AC.
28
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Figure 3. XRD-Spectrum of (a) MWCNTs (b) NiO/MWCNTs.
29
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