Nickel nanocatalyst supported single-step hydroconversion of dicyclopentadiene (DCPD) into high energy-density fuel, exo-tetrahydrodicyclopentadiene (Exo-THDCPD)

Article abstract of DOI:10.1166/jnn.2019.16870

There are several chemical methods for the synthesis of high energy-density fuel, exo-tetrahydrodicyclopentadiene (exo-THDCPD), however, still there is a challenge to synthesize exo-THDCPD conveniently. In present work, the exo-THDCPD from dicyclopentadiene (DCPD) has successfully synthesized through simplest and greener single step hydroconversion reaction over mesoporous supported nickel nanocatalyst (Ni/MCM-41). The reaction performed in autoclave under a hydrogen pressure ranging from 300–400 (Psi), temperature range 130–150° C and progress has been dissociation-recombination sure structural and monitored nanocatalyst analysis by of gas exo-THDCPD IP: have chromatography 203.56.241.128 Copyright: of been DCPD. experimentally is Delivered carried The American which major On: out reveals Fri, by by examined reaction Scientific Ingenta 1 12 H that NMR Jul parameters for the 2019 Publishers and the reaction FTIR 03:16:04 yield such techniques (85%) mechanism as of temperature, the and goes product. the through physic- pres-The ochemical properties have also been evaluated. Good quality nanocatalyst Ni/MCM-41 has been synthesized by impregnation incipient wetness method and characterized by XRD, EDAX, TEM, and BET techniques. The nanocatalyst is highly reactive due to its mesoporous structure having appropriate size and shape which gives free diffusion of the molecules. Repeatability of the nanocatalyst shows good reactivity up to the four runs.

Full text of DOI:10.1166/jnn.2019.16870

Article
Journal of
Nanoscience and Nanotechnology
Vol. 19, 7982–7992, 2019
Copyright © 2019 American Scientific Publishers
All rights reserved
Printed in the United States of America
www.aspbs.com/jnn
Nickel Nanocatalyst Supported Single-Step
Hydroconversion of Dicyclopentadiene
(
DCPD) into High Energy-Density Fuel,
Exo-Tetrahydrodicyclopentadiene (Exo-THDCPD)
Nizamuddin Khan1 , A. C. Abhyankar , Tandra Nandi , and N. Eswara Prasad
ꢀ2ꢀ∗
1
2
2
1Department of Materials Engineering, Defence Institute of Advance Technology (DIAT), Pune 411025, India
2
Fuel and Lubricant Division, Defence Materials and Stores Research & Development Establishment (DMSRDE), Kanpur 208013, India
There are several chemical methods for the synthesis of high energy-density fuel, exo-
tetrahydrodicyclopentadiene (exo-THDCPD), however, still there is a challenge to synthesize exo-
THDCPD conveniently. In present work, the exo-THDCPD from dicyclopentadiene (DCPD) has
successfully synthesized through simplest and greener single step hydroconversion reaction over
mesoporous supported nickel nanocatalyst (Ni/MCM-41). The reaction performed in autoclave under
ꢀ
a hydrogen pressure ranging from 300–400 (Psi), temperature range 130–150 C and progress has
been monitored by gas chromatography which reveals that the reaction mechanism goes through
IP: 95.181.217.46 On: Sat, 06 Jul 2019 08:02:38
dissociation-recombination of DCPD. The major reaction parameters such as temperature, pres-
Copyright: American Scientific Publishers
sure and nanocatalyst have been experimentally examined for the yield (85%) of the product. The
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1
structural analysis of exo-THDCPD is carried out by H NMR and FTIR techniques and the physic-
ochemical properties have also been evaluated. Good quality nanocatalyst Ni/MCM-41 has been
synthesized by impregnation incipient wetness method and characterized by XRD, EDAX, TEM, and
BET techniques. The nanocatalyst is highly reactive due to its mesoporous structure having appro-
priate size and shape which gives free diffusion of the molecules. Repeatability of the nanocatalyst
shows good reactivity up to the four runs.
Keywords: Dicyclopentadiene, Exo-Tetrahydrodicyclopentadiene, Hydroconversion, MCM-41.
1
. INTRODUCTION
rubber, resin and high energy density fuels [12–14].
It has two stereoisomers, namely exo and endo, for-
mer constitutes about 0.5% and later only 99.5%. The
hydrogenated products of both the isomers have high
volumetric energy content, even though most of the
physicochemical properties are similar, except a large
The high-energy density fuels have higher volumetric
energy content than conventional aviation fuel, to provide
more propulsive energy which helps to increase the range
of missiles and aircraft [1]. Hydroconversion of dicy-
clopentadiene (DCPD) to exo-tetrahydrodicyclopentadiene
ꢀ
difference in the freezing points (endo isomer 77 C,
(
exo-THDCPD) has received much attention due to its
ꢀ
exo-isomer −79 C) [9–11, 15]. Therefore, at low tem-
excellent physicochemical properties [2–7] than conven-
tional aviation fuels. DCPD is a component resulting from
the dimerization of the cyclopentadiene (CPD) molecules
via Diels-Alder reaction, which is a very reactive com-
pound. It is self dimerized to DCPD if it is not stored
perature operation, the exo isomer is the best choice as
a liquid fuel. The exo-THDCPD is chemically known
as exo-tetrahydrodicyclopentadiene, commonly referred as
JP-10 that used as a high energy density fuel in var-
ious missile/aircraft and also use as a fuel diluent of
others like RJ-5, JP-9 and RF-1 [16]. Generally, it has
been synthesizing via a two-step process, to begin with,
hydrogenation over palladium on alumina/carbon nanocat-
alyst or nickel on alumina nanocatalyst to get of endo-
THDCPD [3, 17–19] and subsequently isomerizes over
ꢀ
at −80 C [8]. Fourteen hypothetical dimers are pos-
sible through long-range dimerization of DCPD [9–11].
DCPD is an important monomer for the production of
∗
Author to whom correspondence should be addressed.
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doi:10.1166/jnn.2019.16870

Khan et al.
Nickel Nanocatalyst Supported Single-Step Hydroconversion of DCPD into High Energy-Density Fuel, Exo-THDCPD
strong acid nanocatalyst such as aluminum chloride and
sulfuric acid to produce exo-THDCPD. The acid route
suffered from several drowbacks, polymerization, degra-
dation, black coke formation, equipment may be corroded
and produced a large number of undesirable compounds
2. EXPERIMENTAL DETAILS
2.1. Materials
The
mesoporous
aluminosilicate
(99%)
from
Sigma Aldrich, NiCl · 6H O from SD fine chemi-
2
2
cals, dicyclopentadiene from Merck (99%) and Methyl-
cyclohexane (extra pure) from SRL are purchased. These
materials are analytical grade and utilized without further
purification.
[
17, 20–24]. The two step reaction process for the synthe-
sis of Exo-THDCPD shown in Figure 1.
The acid-catalyzed route does not fulfill the user’s
requiements for real utilization, and environmental safety
is also still tough problems to be solved. In the 1980s, the
superacids, such as CF SO H and SbF -graphite are used
2
.2. Synthesis of Nanocatalyst
3
3
5
Nickel nanocatalyst has been synthesized by the incipient
wetness impregnation method [37–39] using a mesoporous
aluminosilicate MCM-41 with different nickel precursors
such as nickel nitrate, nickel chloride and nickel acetate are
utilized to understand the effect of precursor. Nickel nitrate
and nickel acetate show agglomeration and bigger particles
size are demonstrated in Figures 3(b) and (c). Whereas,
nickel chlorides demonstrate well dispersion with smaller
particles size. Therefore, nickel chloride is chosen for
preparation of the nanocatalyst.
for the conversion of endo-THDCPD to exo-THDCPD
22, 25] however, the difficulties of the nano separation
[
and corrosion remain. Ionic liquids [7, 22, 26, 27] are
also being used to isomerize the endo-THDCPD, yet, the
high prices restrict its industrial application. Another liter-
ature [15, 28–32] reported that the isomerization of endo-
THDCPD catalyzed by zeolites such as Hꢀ, HY, HZSM-5
and H-mordenite but due to the easy deactivation of these
nanocatalyst, coke formation over strong acidic site and
blockage of microspores to reduce the productivity. There-
fore, much study has been focused on synthesizing the
materials having a large pore size with the high surface
area to solve the clogging problem. Thus, the mesoporous
Nanocatalyst is prepared by using the nickel (II) chlo-
ride hexahydrate (6.15 gm) in distilled water (150 ml)
ꢀ
and heated up to 90–100 C for one hour and gradually
(
2–50 nm) materials having a well-ordered structure with
added 15 gm mesoporous supporting material with contin-
uous stirring, which turned in to the thick greenish paste.
2
the high surface area (600–1000 m /g) such as MCM-41,
SBA-15 and MCM-48 may perhaps appropriate for hydro-
conversion reactions. Among these mesoporous materials
the aluminosilicate (MCM-41) is an attractive candidate
because of its regular hexagonal structure with the high
ꢀ
Finally, dried at 120 C in an oven for 12 hours to remove
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ꢀ
all the moisture content and calcined at 450 C for 4 hours
Copyright: American Scientific Publishers
in a muffle furnace, the reaction scheme for the same is
mentioned in Figure 2.
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2
surface area (1000 m /g) and porosity ranges 1–10 nm.
It may be used for the hydroconversion [33–35] of bulky
molecules like DCPD and NBD. Al-grafted MCM-41 [36]
was used to isomerize the endo-DCPD to exo-DCPD but
so many side products are also produced, and also need
hydrogenation to convert from solid endo to liquid exo-
THDCPD. Sibi et al. [5] reported the conversion of DCPD
to JP-10 in a single step route using a silica-alumina sup-
ported gold nanocatalyst, due to its high cost limits no use
on an industrial scale.
In this study, we report the most straight forward greener
approach for a single step hydroconversion of DCPD to
Exo-THDCPD using a catalytic system Ni/MCM-41using
pressure autoclave. The hydroconversion pathway and
related influencing factors have been analyzed in detail.
The nanocatalyst shows the activity up to four cycles with-
out any loss of yield. Present approach is useful for the
bulk production.
2
.3. Characterization of Nanocatalyst
Transmission electron microscope (TEM) has been used
to study the size distribution of nickel nano particles
over MCM-41 using Model-Tecnai 20 G 2U-Twin, Make-
FEI Netherland, with an accelerating voltage of 120 kV.
The sample has been prepared by dispersing the parti-
cles in methanol by ultra-sonic technique before putting it
on carbon coated copper grids (300 Mesh) manufactured
by TED PELLA, INC. The texture properties, (surface
areas and pore volume) are measured by nitrogen adsorp-
tion/desorption on Micromeritics (Model: ASAP 2020) at
ꢀ
−
196 C using BET and BJH methods. The chemical com-
position of nanocatalyst used to confirm through energy
dispersive X-ray analysis (EDAX) on EDS EVO-50 (Carl
Zeiss) and X-ray diffraction patterns (XRD) was obtained
ꢀ
in the 2ꢁ range of 5–80 using CuKꢂ radiation at 40 kV
(
Rigaku Ru 200B diffractometer).
Figure 1. Reaction scheme for the synthesis of exo-THDCPD via a
two-step process.
Figure 2. Preparation process of nanocatalyst (Ni/MCM-41).
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Nickel Nanocatalyst Supported Single-Step Hydroconversion of DCPD into High Energy-Density Fuel, Exo-THDCPD
Khan et al.
has also been checked with the reaction without any fur-
ther reactivation. The reaction contents such as DCPD,
methylcyclohexane (MCH) as a solvent and nanocatalyst
are taken in a defined amount and placed inside the reac-
tor then system has purged with nitrogen to create an inert
atmosphere. Initially, the reaction heated in the tempera-
ꢀ
ture range of 50–130 C in the N atmosphere to carry out
2
the isomerization reaction of DCPD to exo-DCPD in one
hour with stirring (800 rpm), during the reaction, sample
is taken out from the reactor time to time for the moni-
toring of reaction progress. Gradually the hydrogen gas is
passed in the pressure range of 0–400 psi to complete the
hydroconversion reaction. At the end of the reaction, the
mixture is allowed to cool down up to room temperature
and after that the material is taken out from the reactor,
and then filtered with the help of vacuum filtration assem-
bly. The reaction mixture distilled to remove the solvent
and unreacted DCPD. Finally, the product exo-THDCPD
is obtained by fractional distillation at temperature range
ꢀ
of 180–182 C. Purity of the distilled compound (exo-
THDCPD) is checked by using gas chromatography and
found more than 99% (shown in Fig. 10).
2
.5. Characterization and Properties
Evaluation of Exo-THDCPD
The hydroconversion reaction is conducted in a 750-ml
capacity SS-316 autoclave pressure reactor, Make-Amar
Figure 3. TEM images (a) MCM-41 (b) nickel nitrate/MCM-41
IP: 95.181.217.46 On: Sat, 06 Jul 2019 08:02:38
Equipments Pvt. Ltd. India. The reactor has equipped
Copyright: American Scientific Publishers
with a mechanical stirrer and an internal water cool-
(c) nickel acetate/MCM-41. (d) 5 wt.% Ni/MCM-41 (e) 10 wt.%
Ni/MCM-41 (f) 15 wt.% Ni/MCM-41.
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ing system. A programmable PID controller controls the
temperature and pressure. The reactions are monitred
by gas chromatography fitted out with a flame ioniza-
tion detector (FID) and a capillary column (0.25 mm ×
0.25 ꢃm × 30 m). The structural elucidation of the prod-
2
.4. Hydroconversion Reaction from
DCPD to Exo-THDCPD
Hydroconversion reaction of DCPD to Exo-THDCPD is
performed over pressure autoclave catalysed with a synthe-
sized mesoporous supported nickel nanocatalyst. All the
parameters such as temperature, pressure and nanocata-
lyst concerning conversion and selectivity have been opti-
mized. Reaction monitoring has been carried out using
gas chromatography and repeatibility of the nanocatalyst
uct has been confirmed by proton nuclear magnetic reso-
1
nance ( H NMR, (JEOL), spectra is recorded in CDCl at
3
500 MHz field strength. Chemical shift values are reported
in ppm relative to tetramethylsilane (0.0 ppm) as an inter-
nal reference. Fourier transforms infrared (FTIR) spec-
troscopy (Model: Perkin Elmer, Spectrum GX) is also used
(a)
(b)
Figure 4. Surface area and pore volume analysis of nanocatalyst (a) N adsorption desorption curve (b) pore size distribution curve.
2
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Khan et al.
Nickel Nanocatalyst Supported Single-Step Hydroconversion of DCPD into High Energy-Density Fuel, Exo-THDCPD
(a)
(b)
Figure 5. XRD pattern of nanocatalyst (a) low angle (b) wide-angle.
(a)
IP: 95.181.217.46 On: Sat, 06 Jul 2019 08:02:38
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(b)
Figure 6. EDAX images (a) MCM-41 (b) Ni/MCM-41.
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Nickel Nanocatalyst Supported Single-Step Hydroconversion of DCPD into High Energy-Density Fuel, Exo-THDCPD
Khan et al.
(
a)
3. RESULTS AND DISCUSSION
.1. Characterization of Mesoporous Supported
Nickel Nanocatalyst (Ni/MCM-41)
3
TEM image Figure 3(a) of neat supporting material is
looking like honey comb structure (hexagonal with open
pores) since besides support itself works as a nanocatalyst,
therefore, it must retain their structure. There is a special
requirement of maximum open pores and acidic sites to be
present for the hydroconversion reaction of the supporting
material. To study the effect of particle size distribution on
the mesoporous supporting material concerning different
precursor materials have been employed. The precursors
such as nickel nitrate and nickel acetate show agglomer-
ated particles, as shown in Figures 3(b) and (c) whereas,
the nickel chloride exhibited well dispersion with smaller
particle size. Therefore, nickel chloride has been choice
for the synthesis of nanocatalyst. Nickel chloride leaves a
thin film on the surface of pore walls, which break-up into
small nickel nanoparticle during drying and calcination.
The loading of metal (5–15 wt.%) on supporting material
have been optimized as shown in Figures 3(d) to (f) which
indicates that, particles getting agglomerated and bigger in
size by increasing the metal loadings after 10 wt.%. Metal
loading less than 10 wt.% retains the structural integrity
of supporting material. This precursor leaves a strongly
adhering thin film on the surface of pore walls, which
upon drying, calcination, and reduction break-up into small
(
b)
Figure 7. (a) Reaction scheme for synthesis of exo-THDCPD through
single step process (b) reaction mechanism (single step process) of exo-
THDCPD.
to characterize the ingredient and product. The FTIR spec-
tra are recorded in the range of 4000–400 cm using
KBr pellets. The physicochemical properties such as den-
sity (Anton Parr DMA 35), freezing point, and heat
of combustion measured by bomb calorimeter Model-
200 (Parr Inst. Company USA) have also been evaluated
and compared with the MIL standard (MIL-DTL-87107D)
specification.
−
1
™
6
IP: 95.181.217.46 On: Sat, 06 Jul 2019 08:02:38
nickel nanoparticle.
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(b)
(c)
Figure 8. Influence of reaction parameters for hydroconversion of DCPD to exo-THDCPD (a) composition percentage of reactant and intermediate
in N2 atmosphere with catalyst (b) composition percentage of intermediate and product with temperature and hydrogen pressure (c) composition
ꢀ
percentage of intermediate and product with time at pressure (400 psi), temperature (150 C) and 2 wt.% catalyst.
7986
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Khan et al.
Nickel Nanocatalyst Supported Single-Step Hydroconversion of DCPD into High Energy-Density Fuel, Exo-THDCPD
a)
(b)
(
(c)
Figure 9. GC analysis of hydroconversion reaction from DCPD to exo-THDCPD (a) hydroconversion of DCPD to exo-DCPD in 20 minutes (b) hydro-
conversion of DCPD to exo-DCPD in 40 mI Pi n :u t 9e s5 (. c1 ) 8h 1y d. 2r o 1c o7 n. v4e 6r si Oo nno:f SD aC tP ,D0 t6o eJ xuo l- D2 C0 P1D 9i n0 86 0: 0m2 i n: 3u t8e s.
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3
The texture properties (porosity and surface area) are
reduces from 0.916 to 0.428 cm /g and surface area from
2
measured by N adsorption/desorption isotherm by using
1086 to 505 m /g. The pore sizes are affecting the activ-
2
BET and BJH methods. Figure 4(a) MCM-41 shows
ity of nanocatalyst significantly, further, it depends upon
the presence of accessible active centers which sited in
the internal pore of the nanocatalyst. Therefore, the metal
loadings are optimized with supporting material to overall
catalytic performance for hydroconversion. The pore size
and surface area of the nanocatalyst significantly affect
the performance of the hydroconversion reaction. The low
angle XRD pattern of each sample signifies two major
adsorption volume P/P at 0.3–0.5 that attributed to capil-
o
lary condensation due to mesopores and regular pore size
distribution. Ni/MCM-41 shows the difference of adsorp-
tion volume due to the presence of metal at the meso-
porous supporting material. The surface area of supporting
material is reduced with increasing metal loading, as sum-
marized in Table II. The pore size distribution curve in
Figure 4(b) is indicating the reduced pore volume with
metal loading. At 15 wt. % nickel loading the pore volume
Table I. Optimized reaction parameter of hydroconversion reaction.
Reaction parameter
Catalyst(Ni/MCM-41)
Reaction temperature
Reaction time
2.5–3.5 Weight%
ꢀ
130–150 C
5–7 hrs.
300–400 Psi
(0.5–1:1)
H pressure
2
MCH:DCPD
Table II. Textural properties of catalyst.
Mesoporous
materials
Metal loading
(wt. %)
Surface area
(m /g)
Pore volume
(cm /g)
2
3
MCM-41
MCM-41
MCM-41
–
10
15
1086
869
505.9
0.916
0.670
0.428
Figure 10. GC spectrum of exo-THDCPD.
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Nickel Nanocatalyst Supported Single-Step Hydroconversion of DCPD into High Energy-Density Fuel, Exo-THDCPD
Khan et al.
reflections (100), (110), corresponds to the ordered hexag-
onal pore structure [40, 41] of supporting material as
shown in Figure 5(a). After the loading of metal and sub-
sequent calcination, the intensity of these reflections is
diminished with the increase in metal loading due to pores
blocking of MCM-41. The well-resolved peaks at wide
angle 2ꢁ values of 37, 43, 63 and 76 correspond to nickel
and nickel oxide nanoparticle planes (111), (200), (220)
and (222) respectively shown in Figure 5(b). The inten-
sity of peaks increases with increasing the metal load-
ing reveals large size of crystals. The wide width along
with the small intensity represented as smaller crystallites
observed that the temperature increased significantly due
to the exothermic reaction. Therefore, a suitable solvent
MCH is used which can serve as a heat sink. Experimen-
tal results show that the catalyst is highly selective for the
synthesis of Exo-THDCPD (JP-10) as compared to a two-
step process with sulphuric acid/aluminium chloride and
another rest of the process.
Reaction parameters are optimized for hydroconversion
of DCPD to exo-THDCPD by varying reaction conditions
such as temperature, reaction time, nanocatalyst, and pres-
sure can be seen in Figure 8. The isomerization of DCPD
to exo-DCPD is possible by heating at a high temperature
for a prolonged period [32, 43, 44]. Exo isomer of DCPD
shows more stable than endo isomer. When it is heated at
[
42]. The elemental mapping of MCM-41 and synthesized
nanocatalyst Ni/MCM-41 has been carried out by EDAX
for elemental analysis as shows in Figure 6. The MCM-41
contains Al, Si, and oxygen elements, whereas, nanocata-
lyst consists of Al, Si, Oxygen, and nickel elements.
ꢀ
110–150 C temperature in the presence of the nanocata-
lyst with temperature, rearranged (isomerizes) into its exo-
DCPD through dissociation into CPD molecule. If further
temperature is increased, numbers of the oligomer may
be formed because of the double bonds of DCPD, when
3
.2. Performance of Nanocatalyst for
Hydroconversion Reaction
ꢀ
the temperature raise above 175 C again CPD forms by
The superior performance of nanocatalyst Ni/MCM-41
could be attributed for the conversion of DCPD to exo-
THDCPD due to its mesoporous hexagonal channel and
its acidic sites are responsible for isomerization and
nickel helps to hydrogenation. During the reaction, it has
decomposing exo-DCPD. Initially, (30 minutes) the reac-
tion shows the concentration of DCPD to exo-DCPD are
in 60:40 ratios and again taken out the sample after one
hour indicating maximum (90–95% exo-DCPD) conver-
sion occurs in the inert atmosphere. The yield of the
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(a)
(b)
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(c)
Figure 11. (a and b) FTIR spectra of DCPD, exo-DCPD (c) FTIR spectra of exo-THDCPD.
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Khan et al.
Nickel Nanocatalyst Supported Single-Step Hydroconversion of DCPD into High Energy-Density Fuel, Exo-THDCPD
product analyses at different intervals indicates that hydro-
gen pressure effectively influences the conversion of exo-
DCPD to exo-THDCPD. The concentration of exo-DCPD
is decreased with increasing the pressure (300–400 psi)
as shown in Figure 8(b). Long reaction time with high
temperature also reduces the yield of the product due to
the formation of oligomer. Therefore, the short reaction
time is advantageous. Gas chromatography is particularly
used to examine the reaction progress as mentioned in
Figure 9. Initially, within 20 minutes shows the response
IP: 95.181.217.46 On: Sat, 06 Jul 2019 08:02:38
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Figure 12. 1H NMR spectra (a) DCPD (b) exo-DCPD (c) exo-THDCPD.
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Nickel Nanocatalyst Supported Single-Step Hydroconversion of DCPD into High Energy-Density Fuel, Exo-THDCPD
Khan et al.
of conversion from DCPD to exo-DCPD through dissoci-
ation into CPD molecules. Another sample has been ana-
lyzed after 40 minutes shows the conversion of exo-DCPD
about 75% and almost one-hour reaction time shows the
conversion of 95–98% of exo-DCPD. Analyzes the data of
peaks (retention time with area percentage) which shows
the purity 99% of exo-THDCPD shown in Figure 10.
The probable reaction pathway of single step hydroconver-
sion of DCPD to exo-THDCPD is mentioned in reaction
scheme Figure 7(b). The reaction mechanism of hydrocon-
version indicates that the reaction selectively goes through
isomerization followed by hydrogenation in the presence
of a nanocatalyst. The summary of the optimized param-
eter is shown in Table I. The following parameters have
been obtained for the maximum (85%) yield. FTIR tech-
Figure 13. Repeatability of catalyst.
nique has been used to investigate the hydroconversion
of DCPD. The characteristic peak (stretching frequency)
3
.3. Reusability of Nanocatalyst
The performance of nanocatalyst was checked by repeat-
ing/recycling, it can be reused up to four cycles without
affecting the yield and selectivity. Since fresh nanocatalyst
has a maximum catalytic site with open pores offers more
reactivity, however, in later performance of the nanocat-
alyst getting reduced because of some byproducts accu-
mulated inside the pores of the nanocatalyst during the
reaction as mentioned in Figure 13. The used nanocat-
alyst can be regenerated after washing of the solvent
−
1
−1
of DCPD is 2967 cm shifted to 2920 cm in exo-
−1
DCPD, this peak difference can vary from 40–70 cm
for the conversion of endo to exo isomer. The C C bond
stretching frequency 1570–1644 cm is almost disap-
peared indicates complete hydrogenation as demonstrates
in Figure 11. It is also observed that the melting point of
DCPD and exo-DCPD is 32 C and 19 C respectively.
After hydroconversion only liquid product is obtained, it
also confirms that during the hydroconversion only exo
isomer is formed, however, the endo isomer is solid in
−1
ꢀ
ꢀ
(
MCH, decahydronaphthalene, and n-hexane) and again
calcination.
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nature at room temperature. Proton nuclear magnetic res-
onance ( H NMR) technique is especially used to iden-
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1
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4
. CONCLUSIONS
tify the isomerization of DCPD to exo-DCPD [32]. The
chemical shift of DCPD, characteristic peaks at ꢄ 3.2 and
ꢄ 2.7 are shifted to ꢄ 2.8 and ꢄ 2.5 after isomerization
into exo-DCPD at carbon two and six position due to the
deshielding of protons. Spectra of the final product are
obtained from ꢄ 1.2 to ꢄ 2.4 ppm, which indicates only
saturated bonds are presents in the compound which is
exo-THDCPD as shown in Figure 12. The physicochem-
ical properties of synthesized high energy density fuel
Exo-THDCPD has been evaluated and compared with the
existing MIL standard specification (MIL-DTL-87107D)
for JP-10, mentioned in Table III.
The high energy-density fuel (Exo-THDCPD) synthesized
through a single step process over a mesoporous sup-
ported nickel nanocatalyst. There is no additional separa-
tion and purification are required at an intermediate stage
of the reaction. The experimental outcome shows that the
nanocatalyst has enormous potential to scaled-up the pro-
cess for the bulk production. The nanocatalyst showed
a well ordered structure with the high surface area and
porosity that responsible for the hydroconversion at opti-
mized reaction condition. It proceeds via two important
consecutive steps isomerization (dissociation and recom-
bination mechanism) and hydrogenation. The study of the
reaction parameter confirmed that suitable reaction con-
dition is (nanocatalyst two wt.%, pressure 400 Psi and
Table III. Physico-chemical properties of exo-THDCPD.
ꢀ
temperature of 150 C) gives 98% conversion and 85%
Physicochemical
properties
Synthesized
exo-THDCPD
selectivity. Since it is synthesized through a single step
with a short time (4–5 hrs.) and ease of separation makes
it more capable and economical for bulk production. The
nanocatalyst can be reused four runs without activity loss
and regenerate again through calcination.
MIL-DTL-87107D
Physical state
Colorless and odor
like Naphtha
42.3
Colorless and odor
like Naphtha
42.1
Net heat
combustion (MJ/kg)
Viscosity (centistokes) at
41
11
40
10
Acknowledgments: The authors are grateful to IIT,
Kanpur for material characterization. The authors are
thankful to Defence Research Development Organization
for funding the present work through the grant no. ST/15-
ꢀ
ꢀ
−
54 C −18 C
ꢀ
Freezing point, C
−79
−79
ꢀ
Flashpoint,
C
54
54
ꢀ
Density 15 C kg/L
0.93
0.93–0.94
1
6/DRM-553.
7990
J. Nanosci. Nanotechnol. 19, 7982–7992, 2019

Khan et al.
Nickel Nanocatalyst Supported Single-Step Hydroconversion of DCPD into High Energy-Density Fuel, Exo-THDCPD
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Received: 14 November 2018. Accepted: 12 January 2019.
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