Novel synthesized microporous ionic polymer applications in transesterification of Jatropha curcas seed oil with short Chain alcohol

Article abstract of DOI:10.1016/j.apcata.2021.118335

New suites of sulfonic acid-functionalized microporous ionic polymers (PIPs) catalysts were synthesized with polymer, alkyl bromides, and 1, 3-propane sultone via a two-step procedure. The synthesized microporous PIP catalysts were characterized using FT-IR, SEM-Mapping, XPS, N₂ adsorption–desorption isotherms, solid NMR spectroscopy, and element analysis. Esterification of several fatty acids with ethanol, which was used as a model reaction in the stabilization of Jatropha curcas seed oil, was checked over functionalized PIP. We tested the catalytic performance of PIP-C₈ on the synthesis of fatty acid esters via the transesterification of J. curcas seed oil with a mixture of short-chain alcohols such as ethanol, ethanol–to–diethyl carbonate (1;1 molar ratio), and ethanol–to–dimethyl carbonate (1:1 molar ratio) with 170 mg of PIP-C₈ at reflux temperature with agitation. The PIP-C₈ catalyst was particularly effective, having achieved yields of 85%, 94%, and 70% for J. curcas seed oil with ethanol, J. curcas seed oil with ethanol–to–DEC, and J. curcas seed oil with ethanol–to–DMC, respectively, under the optimized reaction conditions. The catalyst could be recycled more than five times without significant deactivation. Kinetic studies performed at different temperatures revealed that the conversion of oleic acid to an ethyl ester follows a first-order reaction. The best catalysts with microporous structure (average pore diameter: 1.7–1.9 nm, pore volume: 0.23–0.33 cm³ g^–1) and –SO₃H density (0.70–0.84 mmol/g_cat) were obtained by 1, 3-propane sultone of the chemically activated. The results indicate that the site activity of functionalized microporous ionic polymer materials shows promising approach for the development of environmentally friendly technology.

Full text of DOI:10.1016/j.apcata.2021.118335

Applied Catalysis A, General 625 (2021) 118335
Contents lists available at ScienceDirect
Applied Catalysis A, General
journal homepage: www.elsevier.com/locate/apcata
Novel synthesized microporous ionic polymer applications in
transesterification of Jatropha curcas seed oil with short Chain alcohol
*
Balaji Panchal, Qiaojing Zhao, Cunling Zhao, Zheng Zhu, Shenjun Qin , Yongjing Hao,
*
*
Jinxi Jinxi, Kai Kai, Tao Chang , Yuzhuang Sun
Key Laboratory of Resource Exploration Research of Hebei University of Engineering, Handan, Hebei, 056038 China
A R T I C L E I N F O
A B S T R A C T
Keywords:
New suites of sulfonic acid-functionalized microporous ionic polymers (PIPs) catalysts were synthesized with
polymer, alkyl bromides, and 1, 3-propane sultone via a two-step procedure. The synthesized microporous PIP
Microporous ionic polymer (PIP)
Free fatty acids
catalysts were characterized using FT-IR, SEM-Mapping, XPS, N
2
adsorption–desorption isotherms, solid NMR
Jatropha curcas seed oil
Kinetics
spectroscopy, and element analysis. Esterification of several fatty acids with ethanol, which was used as a model
reaction in the stabilization of Jatropha curcas seed oil, was checked over functionalized PIP. We tested the
(
Trans)esterification
catalytic performance of PIP-C
with a mixture of short-chain alcohols such as ethanol, ethanol–to–diethyl carbonate (1;1 molar ratio), and
ethanol–to–dimethyl carbonate (1:1 molar ratio) with 170 mg of PIP-C at reflux temperature with agitation. The
PIP-C catalyst was particularly effective, having achieved yields of 85%, 94%, and 70% for J. curcas seed oil
8
on the synthesis of fatty acid esters via the transesterification of J. curcas seed oil
Catalyst reusability
8
8
with ethanol, J. curcas seed oil with ethanol–to–DEC, and J. curcas seed oil with ethanol–to–DMC, respectively,
under the optimized reaction conditions. The catalyst could be recycled more than five times without significant
deactivation. Kinetic studies performed at different temperatures revealed that the conversion of oleic acid to an
ethyl ester follows a first-order reaction. The best catalysts with microporous structure (average pore diameter:
3
–1) and –SO
H density (0.70–0.84 mmol/gcat) were obtained by 1, 3-
1
.7–1.9 nm, pore volume: 0.23–0.33 cm
g
3
propane sultone of the chemically activated. The results indicate that the site activity of functionalized micro-
porous ionic polymer materials shows promising approach for the development of environmentally friendly
technology.
1
. Introduction
The issues of environmental degradation and energy security are
studies have focused on an efficient and economical way to transform
non-edible J. curcas seed oil. It is generally agreed that J. curcas biodiesel
has little impact on food supply and the environment; its seeds contain
approximately 25–30 wt% of non-edible oil with high FFA content of up
to 15 wt% [8,9]. The fatty acid C16 and C18 profile present in the
J. curcas seed oil, such as polyunsaturated fatty acids (PUFA), mono-
unsaturated fatty acids (MUFA), and saturated fatty acids (SFA), as well
as the presence of impurities, such as free fatty acids (AGL), influence
the properties of biodiesel [10,11]. However, some feedstocks contain a
significant amount of fatty acids other than C16 and C18 acids, palmitic
acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid
(C18:2), and linolenic acid (C18:3) are the fatty acids commonly found
in oils [12,13].
fundamental challenges of the 21st century. Dependence on conven-
tional fossil fuels is leading to global warming and possible major dis-
ruptions in the social structure [1]. Therefore, diversification of the
energy portfolio with an emphasis on renewable fuels is an imperative
policy tool [2]. Biofuels such as biodiesel and bioalcohols (bio-
ethanol/biobutanol) have the potential to be employed as a renewable,
clean-burning substitute for petroleum diesel, and high biodegradability
with low combustion pollution emissions [3,4]. Methanol and ethanol
are more desirable than other alcohols as alternative fuels because the
resulting emissions are much lower, and impact on the environment [5,
6
]. To reduce the production cost, chief raw material such as J. curcas
Currently, homogeneous alkaline catalysts, such as KOH, NaOH and
seed oil have been identified as an attractive oil feedstock, thus
improving the economic feasibility of biodiesel production [7]. Recent
NaOCH
3
are generally being utilized in the transesterification [14].
Difficult catalyst separation and consequently high cost for product
*
Corresponding authors.
E-mail addresses: qinsj528@hebeu.edu.cn (S. Qin), changt03@sina.com (T. Chang), syz@hebeu.edu.cn (Y. Sun).
https://doi.org/10.1016/j.apcata.2021.118335
Received 22 May 2021; Received in revised form 9 August 2021; Accepted 21 August 2021
Available online 30 August 2021
0
926-860X/© 2021 Elsevier B.V. All rights reserved.

B. Panchal et al.
Applied Catalysis A, General 625 (2021) 118335
◦
purification are the major drawbacks of homogeneous alkaline catalysis
systems [15], homogeneous acid catalysts are difficult to recycle and
operate at high temperatures, and also give rise to serious environmental
and corrosion problems [16]. In recent years, the emerging concept of
green chemistry using eco-friendly materials and microporous advanced
catalysts for chemical transformations has gained immense attention
and its physicochemical properties that may lead to improved reaction
activity for reactants with large molecular size and surface areas, ther-
brown porous ionic polymer (PIP) was dried at 60 C under vacuum.
2.2. PIP-Cn synthesis
Dried PIP (0.5 g), 1-bromoalkane (1.25 mmol) (99.99% purity-
Mackline) and sodium hydroxide (72 mg, 1.8 mmol) (NaOH-Mackline)
were dispersed in ethanol (C H OH-Energy chemical, 99.99%) in a glass
2
5
flask. The resulting solution was magnetically stirred for 48 h at reflux.
After reaction, the solution was cooled to room temperature and the
mixture was separated by centrifugation. The alkylated PIP was washed
with ethanol until no bromide ions were detected and dried overnight at
8
mal, and chemical stability [3,17,18]. The microporous PIP-C catalyst
have attracted much attention owing to their excellent properties such
as good thermal stability, high surface area, and unique large pore
structure. Here, we report for the first time the design and synthesis of a
◦
60 C in an oven under vacuum. In a 25 ml round bottom flask, the
functionalized microporous PIP-C
8
catalyst for the (trans)esterification
second-step products were dispersed in ethanol and 1, 3-propane sultone
(5 mmol, 0.44 ml) (99.99%-Mackline) was added to the flask; the
mixture was further heated at reflux for 48 h. After the reaction, the
mixture was cooled to room temperature and separated by centrifuga-
tion. The PIP-Cn was washed with ethanol several times and dried
process. For biomass conversions, some ILs catalysts have been reported
for the biodiesel synthesis with catalytic activities [19].
n
In the present study, [PIP-C ] acidic catalysts containing an N, N-
dimethylethylenediamine and sulfonic acid groups were prepared and
subsequently characterized by various analysis techniques. Various re-
action conditions that might influence the yield of ethyl esters, including
◦
overnight at 60 C in an oven under vacuum. The general synthesis of
PIP is shown (Scheme 1).
8
the reaction temperature, and micoporous PIP-C catalyst concentra-
tion, were explored in this study. This study aims to utilize the product of
2.3. Catalytic activity and transesterification of prepared PIP-C catalyst
8
the processing of crude J. curcas seed oil as a raw material with micro-
porous PIP-C
8
for biodiesel production, and qualities with yield as well
Oleic acid (99.9% purified-Mackline) esterification reactions were
performed in a 150 ml three-necked flask equipped with a magnetic
stirrer and a digital thermometer in an oil bath. Reactions were per-
formed using oleic acid (C18:1), which is the most commonly used FFA
to evaluate the catalytic performance [20], and 95 mg of catalyst
loading at ethanol reflux temperature with different alcohol to acid
molar ratios. The acid value of the ethyl oleate phase was determined by
titration after the removal of excess ethanol with a standard potassium
as the economic viability of the processes were evaluated. The kinetic
model for the conversion process, and the Arrhenius plot method was
used to analyze the dependence of the rate constant on temperature.
2
. Experimental
2
.1. PIPs synthesis
–
1
hydroxide (0.01 mol L ) potassium hydroxide (KOH, energy chemical,
99.0%) solution [21].
PIPs synthesis is in under argon, in a three-necked flask, 1, 4-bis(bro-
momethyl)benzene (C
8
H
8
Br
2
-Mackline) (8 mmol, 2.112 g) and ferric
The acid value (AV) was determined using Eq. (1).
chloride (2.42 g, 15 mmol) (FeCl
3
-Mackline) were dissolved in 20 ml
(
)
◦
mgKOH
g
= V
KOH
(
X
C
KOH
)
MWKOH
dichloroethane (DCE-Mackline) at 35 C with stirring. Then, N, N-
Acid value (AV)
(1)
m(biodiesel)
dimethyl ethylenediamine (Mackline) (0.22 ml, 2 mmol) was added into
◦
the flask. The mixtures were stirred for 24 h at 80 C, with the release of
where VKOH is the volume of the titrant (ml), CKOH is the concentration of
the titrant (M), MWKOH is the molar weight of the titrant (g/mol) and m
HBr gas. After the reaction, the solution was cooled to room temperature
and the mixture was filtered through a funnel. The obtained solid
product was washed with methanol until the filtrate was colorless. The
(
biodiesel) is the mass of biodiesel (g). The conversion was calculated by
comparing the acid value of the initial oleic acid to that of the ethyl
Scheme 1. Synthesis of sulfonic acid functionalized porous ionic polymers.
2

B. Panchal et al.
Applied Catalysis A, General 625 (2021) 118335
oleate samples (Eq. (2).
AVoleic acid ꢀ AVethyl oleate
X(%) =
[ × ]100
(2)
AVoleic acid
Where AVoleic acid is the acid value of the oleic acid and AVethyloleate is the
acid value of the biodiesel sample given in mg KOH/g of sample.
The transesterification reaction was carried out in a 250 ml glass
three-necked flask equipped with a water-cooled condenser and a
magnetic stirrer. First, the J. curcas seed oil and catalyst were charged
into the flask and heated to the required temperature by an oil bath. In
addition, transesterification was conducted with ethanol–to–DEC
(
diethyl carbonate (C
5
H
10
O
3
), 99.9% purified Mackline) and etha-
), 99.9% purified Mackline).
nol–to–DMC (dimethyl carbonate (C
3 6 3
H O
After the reaction, excess solvent was distilled off under vacuum and the
mixture was centrifuged to separate the solid catalyst. The ester contents
in the upper layer were quantified using gas chromatography-mass
spectroscopy (GC-MS). The yield of fatty acid esters was calculated as
follows:
4 8
Fig. 1. FT-IR spectra of PIP-C , PIP-C , PIP-C12, and PIP-C16 catalysts.
Yield (%) = mesters/moil × wt
%
(3)
various, 1, 3-propane sultone concentrations in a synthetic method for
PIP production induce varying degrees of chemical interaction in PIP.
These results confirm the successful reaction of polymer and sulfonic
Where mester is the mass of the ester in the product and moil is the initial
-
+
mass of the J. curcas seed oil.
acids as well as the formation of zwitterions (–SO … N ) [26]. The band
3
–
1
at 1350 cm is assigned to sulfonic acid groups [27], which facilitates
the reaction rate of the transesterification, and this reaction can be
improved in the presence of strong acidic sites [28,29].
2
.4. Analysis of esters
8
Elemental analysis of PIP-C was conducted on a CHNS elemental
The conversion of triglycerides to esters was monitored by TLC using
analyzer (using a Perkin-Elmer analyzer, 2400 series II). The elemental
analysis results are summarized in Table 1. The acid strength plays a
crucial role in the catalytic performance of the catalysts. The acid
silica gel as the stationary phase (10 ꢀ 40 µm, Q/YJY-001-2005,
ISO9001). A small volume (20 µl) of biodiesel phase was taken and
mixed with 50 µl n-hexane (C
6
H14-energy chemical, 99.9%). Following,
8
strength of the microporous PIP-C catalyst was studied using solid
5
µl of the mixture was applied to a TLC. As a developing solvent, n-
hexane/ethyl acetate (C 10O -energy chemical, 99.9%) /acetic acid
CH COOH-energy chemical, 99.9%) (90:10:1) was utilized, and
nuclear magnetic resonance (solid-NMR) spetroscopy, a reliable tech-
nique for the evaluation of the acidity of various types of solid acid
4
H
(
3
8 8
catalysts [30,31]. Fig. 2 shows the solid NMR spectra of PIP-C . PIP-C
ethanol/sulfuric acid (1:0.5) was used as a color reagent. After spraying
the color reagent over the silica gel plate development, the plate was
heated at a high temperature and analyzed [22]. The analysis of ester
compositions was performed using a GC-MS system (Thermo Scientific
displayed resonances at approximately 10–20 ppm and 60–70 ppm
associated with the weak acid sites; the signals of the weak acid sites
were largely decreased. The resonances at approximately 30–40 ppm
and 120–150 ppm associated with strong acid sites, while the signals of
strong acid sites were largely improved [32]. These results can be
Nicolet IS10) [23]. FT-IR analysis was performed at room temperature in
the region of 4000–500 cm–1, with 45 scans and at 4 cm–1 resolution
8
attributed to the increased acidic site of PIP-C . The strong acid strength
using the total attenuated reflectance technique [24]. TGA was per-
formed using a TGA Q50 V20.13 Build 39. The samples (12 mg) were
was helpful for improving their catalytic activities in (trans)esterifica-
tion. These results can be attributed to the increased content of the
–SO H group site of PIP-C . The strong acid strength helped improve the
–
1
◦
placed in aluminum pans and heated at a rate of 10 K min to 900 C
–1
under nitrogen gas at a flow rate of 20 ml min
. Results and discussion
.1. Microporous PIPs characterization
To identify the structure of the microporous PIPs by Fourier trans-
.
3
8
catalytic activities in (trans)esterification.
The crystal morphology of the PIP-C
scanning electron microscopy (SEM)-Mapping (using the SUPRA 55 VP
Carl Zeiss) after platinum sputtering at 10 mA for 100 s). SEM images
clearly show that the morphology of the PIP-C derived microporous
8
catalyst was investigated by
3
(
3
8
materials was directly affected by the preparation method and exhibited
many porous structures with surfaces that were formed by the flake
structures, which was favorable for mass transfer and the enhancement
of its catalytic activity. This effect was observed in the SEM images
obtained from the different biomass sources showing varying sizes and
shapes of particles. As shown in the representative SEM images (Fig. 3a),
consisting of flake-like particles with 1.00 µm diameter (Fig. 3b), the
primary particles appear to be aggregated into larger clusters. PIP-C
consisted of uniformly and separated particles with 5.00 µm (Fig. 3c).
form infrared (FT-IR) spectroscopy (using KBr pellets on a Nicolet
Impact 410, FT-IR spectrophotometer) spectra confirmed the effective
functionalization of the materials through the presence of vibration
bands ascribed to different functional groups. The FT-IR spectra of PIP-
4 8
C , PIP-C , PIP-C12, and PIP-C16 are presented in Fig. 1. The peak at
–
1
3
426 cm corresponds to strong OH absorption, which is the Bronsted
–1
–1
8
acid. The absorption peaks at 1636 cm and 1589 cm were attributed
to the stretching vibrations of the C–C and C–H bonds, respectively, from
–1
–1
the phenyl unit. Strong absorption peaks at 1210 cm and 1050 cm
–
were attributed to the S
–
O asymmetric and symmetric stretching vi-
–1
Table 1
brations of the –SO
3
H group, and a peak at 860 cm assigned to the
CHNS analysis of PIPs.
–
–
S
O stretching vibration was observed in the PIP-C spectrum, which
8
PIP
N
C
H
S
illustrate the successful formation of the sulfonic acid group [25]. The
loaded acidic species can provide more easily accessible of catalytic sites
to the feedstocks, and therefore the catalytic activity was enhanced
thanks to the increased acidic sites of the synthesized catalyst. The FT-IR
spectra imply the successful synthesis of PIP. These results reveal that
PIP-C4
7.13
6.32
6.07
5.79
60.28
60.53
60.73
60.35
7.71
7.48
7.55
7.21
1.42
1.80
2.24
3.32
PIP-C
8
PIP-C12
PIP-C16
3

B. Panchal et al.
Applied Catalysis A, General 625 (2021) 118335
8
Fig. 2. Solid NMR spectra of PIP-C catalyst.
Fig. 3. SEM images (a) SEM images, (b)1.0 µm diameter, (c) 5.0 µm diameter, and (d) 500 nm of PIP-C8.catalyst.
The morphology were very similar to that of the microporous ionic
liquid, PIP-C consisted of nanoparticles with 500 nm size (Fig. 3d). It
was confirmed that the materials possessed uniform pore structures.
To confirm the validity of PIP-C results, X-ray photoelectron spec-
troscopy (XPS) analysis (performed using a K-alpha XPS spectrometer
surface, and the intensity of the higher-binding energy regions of the
carbon element levels is much stronger than that of the original surfaces.
8
Fig. (4c) shows the spectrum of PIP-C
399–404eV, which was due to the N bonds. Fig. (d) shows the S2p
spectrum of PIP-C at 168.2 eV which belongs to sulfur element of sul-
fonic acid group. The catalytic effects of sulfonated materials has been
H groups, thus its density has a distinct effect on catalyst
8
, divided into multiple N1s peak at
8
8
(
Thermo) with a monochromatic Al K
Fig. 4a-e). Fig. (4a) shows the O1s spectra of PIP-C
exhibits only one O1s peak at
α
X-ray source) was carried out
(
8
microporous
credited to –SO
3
catalyst. The XPS spectrum of PIP-C
8
activity [33]. Generally, the S2p photoelectron peak is of particular
significance in the sulfonated materials and has been used to confirm the
5
32.2 eV, which was attributed to the C–O bond. Fig. (4b) shows the C1s
spectrum of PIP-C
8
, divided into two single peaks at binding energies of
presence of –SO
PIP-C , divided into three peaks at binding energies of 70.6, 71.4, and
71.7 eV, which, respectively, belong to the Br–C and Br anion. XPS
3
H groups [34]. Fig. (4e) shows the Br2d spectrum of
2
85 eV, which belong to the C–C bond. From the XPS analysis, the
8
functional groups containing oxygen, such as R-OH, were found on the
4

B. Panchal et al.
Applied Catalysis A, General 625 (2021) 118335
8
Fig. 4. XPS spectra of the PIP-C catalyst.
results shows that the saturated solution peak is larger than that of the
known concentration. The O1s signal at 1.50 eV was used to calibrate
the spectral frequency whenever minor charging effects were observed
[
35].
2 2
N adsorption-desorption isotherm (using nitrogen N adsorption at
liquid nitrogen temperatures on a Carlo Erba Sorptomatic 1990 instru-
ment) curves of the acid-activated PIPs show that these materials have
microporous structures (Fig. 5) and surface area values that are higher
4
than those of PIP-C , PIP-C12, and PIP-C16 (Table 3). This results from
acid leaching, and consequently, the presence of micropore in the
2
–1
sample, with PIP-C
8
presenting the largest surface area (480 m /g ).
was more effective
The measured particle size values showed that PIP-C
8
than other PIPs. These results are coherent with the surface area values
of each PIP. The specific surface areas, total pore volume, and average
pore volume are presented in Table 2. The catalyst possessed a surface
2
–1
2
–1
2
–1
2
–1
area of 660 m g , 480 m g , 564 m g , and 448 m g , for PIP-C
PIP-C
4
,
8
, PIP-C12, and PIP-C16, respectively. The total pore volumes were
.2739 cm3
–1, 0.2332 cm3
–1, 0.2378 cm3
–1, and 0.2342 cm3 –1
Fig. 5. Nitrogen adsorption-desorption isotherm and pore size distribution of
the PIP-C , PIP-C , PIP-C12, and PIP-C16 catalysts.
0
g
g
g
g
,
4
8
for PIP-C
diameter of 1.7 nm, 1.9 nm, 1.7 nm, and 1.9 nm was obtained for PIP-
, PIP-C , PIP-C12, and PIP-C16, respectively. PIP-C exhibits a high
4 8
, PIP-C , PIP-C12, and PIP-C16, respectively. An average pore
catalytic activity [36]. Mostly, the small size of the porous support re-
sults in a highly share of the catalytically active sites located on the
support surface, which can obtain more contact opportunities between
the active sites and substrates and thus greatly improve the catalytic
C
4
8
8
surface area and total pore volume that enhance the efficiency of mass
transfer and prevents the release of acid sites. The large surface area and
pore volume, and small pore diameters, are favorable for enhanced
5

B. Panchal et al.
Applied Catalysis A, General 625 (2021) 118335
Table 2
3.3. Esterification over PIP-C
8
The BET analysis results of PIP catalyst.
a
2
–1
b
p
3
–1
c
The catalytic activity of the sulfonic acid-functionalized PIP-C
PIPs
S
BET (m
g
)
V
(cm g
)
Dave (nm)
8
catalyst was tested for the esterification reaction of oleic acid with
ethanol into ethyl oleate. First, the catalytic behavior of the microporous
PIP-C
PIP-C
PIP-C
0
4
8
715
660
480
564
448
0.3238
0.2739
0.2332
0.2378
0.2342
1.7
1.7
1.9
1.7
1.9
8
PIP-C as a function of the reaction was studied using the following
PIP-C12
PIP-C16
experimental conditions. The experimental results showed that the yield
increased with increasing catalyst concentration and reached 88.7%
a
b
BET surface area,
8
when the PIP-C concentration was 170 mg (Fig. 6a). As shown in
,
Total pore volume
Fig. 6b, the yield increased with increasing molar ratio of oleic acid to
ethanol up to 1:6. This is due to the inductive effect of the increased
carbon chain of alcohol. Fig. 6c shows the reaction time of yield change.
The yield increased with reaction time, reaching a maximum of 93.6%
c
Average pore size
2
–1
.
(
trans)esterification efficiency. The BET surface of PIP-C
8
is 480 m /g
The PIP material exhibited several disordered nanopores with uniform
pore sizes ranging from 1.7 to 1.9 nm, in accordance with the BET
surface analysis [37], high surface area, which was favorable for the
catalytic (trans)esterification reaction. Thus, although various research
groups have proved the existence of microporous PILs, the micropores
PILs active sites remains a great challenge despite an enormous devel-
opment in the catalyst synthesis. Also the generation of microporosity is
a promising strategy for endowing with a specific functionality. Such PIL
catalysts catalytically active sites in micropores within the walls of
mesopores would be ideal catalysts, because organic molecules are first
freely diffused through the main channels and then strongly interact
with the active sites located in the micropores for better reactivity [38].
8
after 7.5 h. A high conversion was achieved using PIP-C in a short time;
this is because of its high acidity and number of strong acid sites. The
yield increased with increasing reaction temperature, and reaching
79.9% at 85 ºC (Fig. 6d). This is probably due to the better solubility and
miscibility of oleic acid with ethanol at higher temperatures, which fa-
cilitates the protonation of the carbonyl group of oleic acid and lowers
the mass transfer limit, resulting in the increased yield of the product.
Roman et al. [40] evaluated a novel 1-methylimidazolium hydrogen
4
sulfate, [HMIM]HSO , ionic liquid was successfully applied as a catalyst
in the biodiesel production through the esterification reaction of oleic
acid with methanol. The yield of 90% was achieved for product after 8 h.
3
.4. Catalytic performance of PIP-C
8
on various fatty acids with short-
3
.2. Selection of a high-activity PIP catalyst
chain alcohol yields
In this study, four PIP catalysts were prepared by adding respective
8
The PIP-C catalyst was evaluated for the esterification of various
acids, i.e., sulfonic acid, 1-bromobutane (C
9.9%), 1-bromooctane (C 17Br-energy chemical 99.9%), 1-bromo-
hexadecane (C16 33Br-energy chemical 99.9%), 1-bromododecane
25Br-energy chemical 99.9%), and 1, 3-propane sultone
S-energy chemical 99.9%). During the reaction, it was observed
catalyst could be used to prepare the desired products.
4
H
9
Br-energy chemical
fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid,
linoleic acid, and oleic acid with ethanol and methanol to produce es-
ters. Optimum reaction conditions were explored by examining the
9
8
H
H
(
C
C
12
H
impact of a PIP-C
alcohols (90 mmol), and a reaction time of 7.5 h at the reflux temper-
ature with agitation. The PIP-C catalyst is highly active in the esteri-
8
catalyst loading of 145 mg, fatty acids (15 mmol),
(
3
H
6
O
3
that the PIP-C
8
8
Each experiment was conducted under the same conditions: a catalyst
fication reaction. Thus, the esterification yields of lauric acid, myristic
acid, palmitic acid, stearic acid, and linoleic acid under optimized re-
action conditions with ethanol were 90.7%, 93.1%, 91.5%, 92.9%, and
91.7%, respectively (Table 4, entry nos. 1–5). The esterification yields of
oleic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and
linoleic acid under optimized reaction conditions with methanol were
92.3%, 92.0%, 93.5%, 92.2%, 92.5%, and 92.4%, respectively and are
concentration of 95 mg based on the lipid molar, oleic acid (4.23 g,
◦
1
5 mmol), and ethanol (3.78 m, 90 mmol), at 65 C, for 3 h with
agitation. Under these conditions, the catalytic activities of PIP-C
4
, PIP-
C
8, PIP-C12, and PIP-C16 were compared; the obtained oleic acid con-
version results using these four ionic PIPs are presented in Table 3. The
catalyst acidity is the primary factor impacting catalyst efficiency during
the esterification reaction, namely, the PIP-C
8
catalyst, which has the
presented in Table 4 (entry nos. 6–11). PIP-C
8
exhibited outstanding
highest acidity as well as the largest number of strong acid sites among
all the PIP catalysts. The ethyl oleate yield (61.5%) was much higher
catalytic performance with a high yield under mild conditions, which
was comparable to that of ethanol and methanol. The catalytic perfor-
when catalyzed by the PIP-C
4
, PIP-C12, and PIP-C16 catalysts. Under the
8
mance of PIP-C could be ascribed to its remarkable properties, such as
same reaction conditions, an ethyl oleate yield above 44.2% was ob-
tained in the presence of the PIP-C12 catalyst. The yield of 39.4% and
strong acidity and a larger number of acid sites. The esterification of
palmitic acid with methanol was studied over microporous sulfated
zirconia solid acid catalyst; the catalyst showed 88–90% yield of methyl
palmitate after 5–7 h [36]. It is important to mention that the loading of
2
7.1% were obtained with PIP-C16 and PIP-C
The PIP-C acidity and structure had significant effects on oleic acid
conversion into ethyl oleate. It is already understood that the nature of
H functionalized PILs [39].
4
catalysts, respectively.
8
functional groups (–SO
improved hydrophilicity and increase the accessibility of raw material
(FFAs, ethanol, and methanol) to the –SO H groups in the esterification.
3 8
H) on the surface of PIP-C may lead to
the anion affect the catalytic activity of –SO
Therefore, the sulfonic acid-functionalized PIP-C
further studies.
3
8
was selected for
3
3
.5. Recycling experiments for PIP-C
8
As the cost of biodiesel production is a major concern nowadays, the
Table 3
recyclability of PIL catalysts used in the biodiesel process should be
taken into account. Recycling of PILs reduces the cost of biodiesel pro-
duction. In the recycling process, we were able to easily separate the PIP-
Effect of porous ionic polymers on esterification of oleic acid and ethanol.
Entry
PIP- catalyst
Conversion (%)
C
8
catalyst from the resultant mixture products owing to the insolubility
of the PIP-C catalyst. The PIP-C catalyst with sufficient functionality
and high oxidation stability exhibited a high conversion yield with high
recyclability. The PIP-C catalyst has a large surface area and a large
1
2
3
4
PIP-C
PIP-C
4
8
27.1
61.5
44.2
39.4
8
8
PIP-C12
PIP-C16
8
Reaction conditions: catalyst (95 mg), oleic acid (4.23 g, 15 mmol), ethanol
number of acidic sites, which help in separating the polar compounds
effectively from the acidic sites and preventing the acidic sites from
◦
(
3.78 m, 90 mmol), 80 C, 3 h.
6

B. Panchal et al.
Applied Catalysis A, General 625 (2021) 118335
◦
Fig. 6. (a). The effect of PIP-C
8
concentration on the ethyl oleate yield. Reaction conditions: oleic acid (4.23 g, 15 mmol), ethanol (3.78 ml, 90 mmol), 85 C for
7
.5 h, and various catalyst Concentrations of 45–170 mg (b) The effect of oleic acid: ethanol molar ratio on the ethyl oleate yield. Reaction conditions:catalyst PIP-C
8
◦
(
95 mg), oleic acid (4.23 g, 15 mmol), 85 C for 7.5 h, and various molar ratio of oleic acid and ethanol of 1:2–1:10. (c) The effect of reaction time on the ethyl oleate
◦
yield. Reaction conditions: catalyst PIP-C
8
(95 mg), oleic acid (4.23 g, 15 mmol), ethanol (3.78 ml, 90 mmol), 85 C, and various reaction time of 1.5–7.5 h. (d) The
8
effect of reaction temperature on the ethyl oleate yield. catalyst PIP-C (95 mg), oleic acid (4.23 g, 15 mmol), ethanol (3.78 ml, 90 mmol), 7.5 h, various reaction
temperature of 50–85 ◦C.
being released. PIP-C
significant decrease in the catalytic activity, as shown in Fig. 7. For the
novel PIP-C catalyst, the yields were 92.3% (first run), 92.1% (second
8
could be recycled at least five times without any
Table 4
Catalytic performance of PIP-C
8
on esterification of fatty acids and short-chain
8
alcohols.
run), 91.8% (third run), 91.2% (fourth run) and 88.9% in the fifth run,
mostly due to the unavoidable leaching of the catalyst during the reac-
Entry
Fatty acids
Alcohols
Conversion (%)
1
2
3
4
5
6
7
8
9
Lauric acid
Myristic acid
Palmitic acid
Stearic acid
Linoleic acid
Oleic acid
Ethanol
90.7
93.1
91.5
92.9
91.7
92.3
92
tion, blockage of acid sites by adsorbed organic species [41]. The PIP-C
8
Ethanol
was more active; the spent catalyst showed no structural changes and,
hence, could be efficiently recycled with almost no loss in performance.
Ethanol
Ethanol
8
This work suggests that J. curcas seed oil with PIP-C catalyst is a
Ethanol
Methanol
Methanol
Methanol
Methanol
Methanol
Methanol
promising process that can sustain biodiesel growth.
Lauric acid
Myristic acid
Palmitic acid
Stearic acid
Linoleic acid
93.5
92.2
92.5
92.4
3
.6. Testing of PIP-C
8
on J. curcas seed oil with different alcohol yields
1
1
0
1
Fatty acids are J. curcas seed oil compounds that vary in chain length,
degree of unsaturation, and structure. Fatty acids were determined by
GC-MS using AOAC (969.33), and compared with the available GC
standards. J. curcas seed oil was distinguished from the plant lipids with
straight-chain carbon compounds like C14-C18 and C20 saturated and
unsaturated fatty acids. Long-chains polyunsaturated fatty acids (LC-
Reaction conditions: catalyst PIP-C
8
(145 mg), fatty acids (15 mmol), alcohols
(
90 mmol), reflux temperature at 7.5 h.
7

B. Panchal et al.
Applied Catalysis A, General 625 (2021) 118335
A PIP-C
8
catalyst loading of 170 mg (based on the molar concentration
of lipids) and a J. curcas oil: alcohol molar ratio of 1:6, with a constant
agitation speed of 500 rpm after 5 h of reaction at reflux temperature.
8
The results showed that the acid-functionalized PIP-C catalyst could
efficiently trigger biodiesel production. Thus, the transesterification
yields for J. curcas seed oil with ethanol, ethanol–to–DEC, and etha-
nol–to–DMC under optimized reaction conditions were 85%, 94%, and
7
0%, respectively. In addition to biodiesel production, the prepared
active PIP-C catalyst is applicable to a wide range of solvents. The PIP-
catalyst with a high surface area improves the catalytic activity
because the accessibility of reactant molecules to active sites is relatively
high on microporous PIP-C catalyst. Being a stronger organic acid,
sulfonic acid could ionize a proton quickly because of the negative in-
duction effect of the atoms between the CH H groups. The
and –SO
8
C
8
8
3
3
proton, then, combines with the triglyceride carbonyl group to form a
carbocation intermediate, which reacts through a nucleophilic substi-
tution reaction with alcohol. It has been reported that the dimensions of
triglyceride, methyl ester, and glycerin are approximately 5.8, 2.5 and
0
.6 nm, respectively [43]. It was understood that the glycerin molecules
can easily infiltrate the pores of the catalyst and most of the active sites
will be utilized during the transesterification reaction [44,45]. ILs
functionalized with sulfonic acid groups are one of the most useful types
of functional ILs because they are highly effective in many
Fig. 7. PIP-C
8
catalyst recyclability for esterification of oleic acid with ethanol.
◦
acid-catalyzed reactions [46,47]. The results indicate that the PIP-C
8
Reaction conditions: reaction temperature at 85 C for 7.5 h.
catalyst is a good choice for different alcohol; the catalyst could effi-
ciently catalyze raw oil.
PUFA) such as C18:1 and C18:2 with greater double bonds are also
found in J. curcas seed oil. The different fatty acids identified in this
study are listed in Table 5. J. curcas seed oil contents myristic acid (14:0;
3
.7. Analysis of biodiesel
0
.1%), palmitic acid (16:0; 14.2%), palmitoleic acid (16:1; 0.7%),
margaric acid (17:0;0.1%), steric acid (18:0;7.0%), oleic acid (18:1;
4.7%), linoleic acid (18:2; 32.8%), linolenic acid (18:3; 0.2%),
We tested the transesterification of J. curcas seed oil with a mixture
4
of short-chain alcohols such as ethanol, ethanol–to–DEC, and etha-
nol–to–DMC with 170 mg of PIP-C at reflux temperature with agitation.
arachidic acid (20:0; 0.2%), total saturated fatty acids (21.6%), total
mono-unsaturated fatty acids (45.4%), and total polyunsaturated fatty
acids (33.0%). The non-edible characteristics of oil play a vital role for
their utilization as ideal feedstocks in biodiesel production [42].
8
GC-MS was used for the characterization of synthesized biodiesel and
J. curcas seed oil. The most important factor relevant to catalytic activity
is the total ester content (%), which indicates how much J. curcas seed
oil is converted to biodiesel. Overall, when the reaction temperature
matches the reflux temperature, catalyst show improved catalytic
properties due to enhanced activation energy and mass transfer resis-
J. curcas seed oil has
a better perspective due to its high
mono-unsaturated content (45.4%) and its abundant availability in
China.
The catalytic activity of the porous ionic polymer (PIP) solid catalyst
was evaluated in the transesterification of J. curcas seed oil. As expected,
the transesterification could not occur under the employed reaction
tance. The PIP-C
conversion due to acidity, whereas the PIP-C
nol–to–DEC (1:1 mol/mol) showed high catalytic activation with a high
ester concentration (94%); whereas PIP-C with ethanol exhibited low
catalytic activation with a low esters concentration (85%), especially the
PIP-C
catalyst with ethanol–to–DMC which was not exhibited the
activation with a high esters concentration (70%). In Fig. 8, PIP-C with
8
catalyst exhibited a significant increase in the ester
8
catalyst with etha-
conditions. When the prepared PIP-C
transesterification, the conversion to esters could be obtained. The cat-
alytic activity of the PIP-C catalyst was tested for the transesterification
reaction of J. curcas seed oil into biodiesel using short-chain alcohol
ethanol, DEC, DMC). The catalytic activity of PIP-C on the trans-
8
was used as a catalyst for the
8
8
8
8
(
8
2
–1
a large surface area of 480 m /g , and ethanol–to–DEC achieved the
highest ester conversion, probably resulted from the strong acidity of
esterification of J. curcas seed oil with ethanol, ethanol–to–DEC (1:1
molar ratio), and ethanol–to–DMC (1:1 molar ratio) were also studied.
The catalyst was particularly effective, achieving a high biodiesel yield
from J. curcas seed oil. Parameter condition was same in all experiments.
8
these solvents. These results indicate that PIP-C has synergetic effects
on ester conversion efficiency in the transesterification process. Zhu
et al. [48], reported the ethanol–to–DEC was investigated by an efficient
Table 5
Fatty acids composition of Jatropha curcas seed oil used in this study.
a
Fatty acids
Structure
Formula
Oil (wt%)
Saturated (wt%)
Mono-unsaturated (wt%)
Poly-unsaturated (wt%)
Myristic
Plamitic
Palmitoliec
Margaric
Steric
14:0
16:0
16:1
17:0
18:0
18:1
18:2
18:3
20:0
C
C
C
C
C
C
C
C
C
14
16
16
17
18
18
18
18
20
H
28
H
32
H
30
H
34
H
36
H
34
H
34
H
30
H
40
O
2
O
2
O
2
O
2
O
2
O
2
O
2
O
2
O
2
0.1
14.2
0.7
0.1
14.2
–
–
–
–
–
0.7
–
0.1
0.1
7
–
–
–
7
–
Oleic
44.7
32.8
0.2
–
44.7
–
Linoleic
Linolenic
Arachidic
Total
–
–
32.8
0.2
–
–
–
0.2
0.2
21.6
–
100
45.4
33
a
The former number represents the number of the carbons in the hydrocarbon chain while the latter represents the number of the double bond in the respective fatty
acid.
8

B. Panchal et al.
Applied Catalysis A, General 625 (2021) 118335
Fig. 8. GC-MS spectra of synthesized esters, synthesis conditions ( a) J. curcas seed oil, (b) J. curcas seed oil: ethanol molar ratio of 1:6, (c) J. curcas seed oil: ethanol-
to-DEC (1:1) molar ration of 1:6, (d) J. curcas seed oil: ethanol-to-DMC (1:1) molar ratio of 1:6, PIP-C catalyst loading of 170 mg, with a constant agitation speed of
00 rpm after 5 h of reaction at reflux temperature.
8
5
solvent system comprising of other solvent system. We further investi-
gated the changes in the composition of the main products, such as ethyl
myristate (14:0), ethyl palmitate (16:0), ethyl palmitate (16:1), ethyl
margariate (17:0), ethyl stearate (18:0), ethyl oleate (18:1), ethyl lino-
leiate (18:2), ethyl linolenicate (18:3), and ethyl arachidicate (20:0)
ethyl esters. Generally, this is because the double bonds have an
electron-donating group, which can facilitate the reaction rate of the
transesterification, and this reaction can be improved in the presence of
strong acidic sites. Therefore, we believe that the strong acidity with
sufficient acidic sites can facilitate the formation of esters, which de-
termines the total amount and quality of ester through synergetic effect
of PIP-C8. Interestingly, DEC and DMC-based esters is reported to have
better lubricating properties and oxidation stability vis-a-vis conven-
tional esters due to miscibility of formed synthesized intermediate,
glycerol carbonate, glycerol dicarbonate by product in the DEC and
DMC-esters phase [49].
with respect to PIP-C
tions are similar to the expected ratio. However, there are some changes
in each composition depending on the PIP-C and a mixture of solvents,
8
and ethanol–to–DEC. The overall ester composi-
8
which may indicate a high catalytic activity. The conversion levels were
found to be higher; this could be due to their inherent FFA composition
of mono-unsaturation, leading to a higher reactivity with novel PIP-C
This clearly shows that the transesterification reaction rate in the pres-
ence of PIP-C is the highest for the triglycerides of mono-unsaturated
8
.
FT-IR spectroscopy was used for the synthesized esters and J. curcas
seed oil characterization, and spectra are shown in Fig. 9. The peaks at
8
–
1
–1
and poly-unsaturated fatty acids, followed by that of saturated acids.
The ester compositions of the saturated fatty acids (16:0 and 18:0)
decreased and the shorter chains converted to the longer chain esters.
However, it was found that the ester contents of ethanol, etha-
nol–to–DEC and ethanol–to–DMC consisted primarily of ethyl oleate
2920.30 cm and 2851.91 cm are assigned to the stretching vibra-
tions of symmetric and asymmetric aliphatic C–H in the CH and the
groups, respectively. At 1743.10 cm , there is a strong
2
–
1
terminal CH
absorption peak, which is attributed to the carbonyl group (C
3
–
–
O)
–
1
stretching vibration of triglycerides. The peaks in 1200–1400 cm are
mostly assigned to CH and CH aliphatic group bending vibrations,
such as symmetric H-C-H bending at 1377.25 cm and CH
(
C18:1) and ethyl stearate (C18:0). In particular, the esters containing
2
3
–
1
double bonds, such as C18:1, C18:2, and C18:3, are easily converted to
2
scissoring at
Fig. 9. FT-IR spectra of synthesized esters, compared with (b) J. curcas seed oil with (c) J. curcas seed oil: ethanol molar ratio of 1:6, (d) J. curcas seed oil: ethanol-to-
DEC (1:1) molar ration of 1:6, and (e) J. curcas seed oil: ethanol-to-DMC (1:1) molar ratio of 1:6, PIP-C8 catalyst loading of 170 mg, with a constant agitation speed of
5
00 rpm after 5 h of reaction at reflux temperature.
9

B. Panchal et al.
Applied Catalysis A, General 625 (2021) 118335
–
1
463.79 cm 1. The peaks in the region 1096–1116 cm–1 are assigned to
ethanol–to–DMC). The observed peaks of the J. curcas seed oil and
–
1
–1
1377.26 cm ,
the C-O ester group stretching vibration and CH
2
wagging. However,
ethanol–to–DEC
appeared
at
1743.10 cm
,
–
1
–1
–1
there are very few differences between the FT-IR spectrum of J. curcas
seed oil and three esters (used ethanol, ethanol–to–DEC, and
1157.19 cm , 1031.96 cm , 871.18 cm are transesterification into
1743.95 cm–1,
1361.91 cm
–1
,
1170.91 cm
–1
,
1016.31 cm ,
–1
Fig. 10. Thermal stability of synthesized esters, (a) J. curcas seed oil: ethanol molar ratio of 1:6, (b) J. curcas seed oil: ethanol-to-DEC (1:1) molar ration of 1:6, (c)
8
J. curcas seed oil: ethanol-to-DMC (1:1) molar ratio of 1:6, PIP-C catalyst loading of 170 mg, with a constant agitation speed of 500 rpm after 5 h of reaction at reflux
temperature.
1
0

B. Panchal et al.
Applied Catalysis A, General 625 (2021) 118335
8
80.38 cm 1 in the esters, respectively. So, the disappearance of the
–
–
1
–1
–1
peak at 1463.79 cm , 1096.86 cm , and 965.93 cm from the J. curcas
seed oil spectrum and in the biodiesel sample and the obtained of the
–
1
–1
novel peaks at 1436.14 cm , and 1196.25 cm clearly show the
transesterification of J. curcas seed oil into biodiesel. It is noted that the
peaks of the J. curcas seed oil and ethanol that presented at
–
1
–1
–1
–1
1
8
1
648.10 cm
,
1272.22 cm
,
1067.13 cm
,
1000.12 cm
,
and
–
1
–1
–1
52.22 cm are transesterification to 1678.95 cm , 1287.91 cm
,
070.91 cm–1, 1010.35 cm ,and 860.34 cm
–1
–1
in the esters,
respectively.
The TGA curves of the three esters and J. curcas seed oil are presented
in Fig. 10a. The thermal stability curve shows that esters (J. curcas seed
oil with ethanol–to–DEC) are less thermally stable than J. curcas seed oil.
◦
The onset temperature of J. curcas seed oil is 385 C whereas that of the
◦
◦
ester is 191 C, and the ester is completely volatilized at 250 C.
Fig. 10b, the thermal stability curve shows that esters (J. curcas seed oil
with ethanol) are less thermally stable than J. curcas seed oil; the ester is
◦
◦
Fig. 12. Arrhenius plot of the conversion process catalyzed by the prepared
1
87 C and is completely volatilized at 242 C (Fig. 10c). The thermal
◦ ◦ ◦ ◦
microporous PIP-C at 50 C, 60 C, 70 C, and 80 C.
8
stability curve shows that the esters (J. curcas seed oil with etha-
nol–to–DMC) are less thermally stable than J. curcas seed oil while for
◦
◦
ester is 167 C and the ester is completely volatilized at 234 C. There-
fore, the synthesized esters from J. curcas seed oil with ethanol–to–DEC
as an alternative fuel [50,51].
Table 6
Rate constants and the activation energy of the reaction process.
◦
1
1
Temperature ( C)
Rate constant (minˉ )
Activation energy (kJ molˉ )
5
6
7
8
0
0
0
0
0.09527
0.14364
0.20075
0.29315
36.5
32.8
30.3
22.3
4
. Kinetic model
Kinetic models have been used to describe the ethyl oleate produc-
tion from oleic acid esterification with ethanol using the PIP-C
8
catalytic
system. The kinetics of the conversion process was simulated as a
◦
◦
(approximately 90%) for ethyl oleate production can be theoretically
function of temperature ranging from 50 to 80 C (Fig. 11). According to
our previous research, the process of ethyl oleate production was proven
to be a first-order reaction, and the exponential equation was fitted using
Eq. (4) for the experimental data to represent the kinetic behavior
throughout the reaction duration. The rate of the esterification reaction
was independent of the ethanol concentration and was assumed to
follow first-order kinetics as represented in the following equation.
◦
achieved at 80 C. Because of the significant effect of temperature on the
conversion process, their correlation was represented and analyzed
using the Arrhenius plot, which correlates the rate constant ln(k) with
temperature (1/T). Moreover, the activation energy (Ea) of the reaction
was calculated using the Arrhenius Eq. (5).
In(k) = ꢀ E + In(A)
a
(5)
RT
ꢀ
In (1 ꢀ Xoleic acid) = kt
(4)
Where, R is the ideal gas constant and A is the pre-exponential factor.
where, Xoleic acid esterification is at time ‘t’ and k is the rate constant.
2
Fig. 12, shows the Arrhenius plot of the conversion process catalyzed
As shown in Fig. 11, the correlation coefficient (R = 0.98) of
◦
by the prepared microporous PIP-C
8
at 50–80 C. It was confirmed that
ANOVA statistics demonstrates that the model is well fitted for the
experimental data. The results of constant values at different tempera-
tures indicate that the conversion process is significantly and positively
affected by the increasing temperature, and a high conversion yield
ln(k) changes linearly with 1/T in the studied temperature range, as
2
expected for a single rate-limited thermally activated process (R
=
ꢀ
1
0
.99). In this study, the activation energy value (22.3 kJ mol ) is
ꢀ 1
consistent with the reported range of 17.9–51.9 kJ mol [52]. The
activation energy is relatively low in comparison with previous report
[
53]. As evident from Table 6, the results of rate constants under
different temperatures prove that temperature is closely related to the
efficiency of the conversion process.
5
. Conclusion
8
Microoporous PIP-C catalyst with a high specific surface area of
4
80 m2
g , and an acidic nature enables the catalysis of the (trans)
ꢀ 1
esterification reaction. The best property of this new catalyst is its sta-
◦
bility during (trans)esterification in at 250 C. The chosen catalyst, PIP-
8
C displayed better catalytic activity in the esterification of several FFAs
into esters; its recyclability was successfully proven in five consecutive
runs. Therefore, it is suitable and promising catalyst in the context of
ester production, primarily for the treatment of oleic acid, lauric acid,
8
myristic acid, palmitic acid, stearic acid, and linoleic acid. PIP-C has
also been used for the transesterification of J. curcas seed oil with
ethanol, ethanol–to–DEC, and ethanol–to–DMC. The factors affecting
the conversion of FFAs were determined to be the reaction time, tem-
perature, molar ratio of FFA–to–alcohol, and catalyst loading; GC-MS,
FT-IR, and TGA analyses showed that the triglycerides of the J. curcas
◦
Fig. 11. Kinetics of the conversion process at different temperature: 50 C,
◦ ◦ ◦
6
0 C, 70 C and 80 C.
1
1

B. Panchal et al.
Applied Catalysis A, General 625 (2021) 118335
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(
[
Balaji Panchal: Data curation, Formal analysis, Writing – original
draft. Tao Chang: Data curation, Formal analysis, Methodology, Writing
2
1
–
review & editing. Shenjun Qin: Methodology, Supervision, Writing –
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The authors declare that they have no known competing financial
interests or personal relationships that could have appeared to influence
the work reported in this paper.
Acknowledgments
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China no. 21902041, the Natural Science Foundation of Hebei province
no. D2018402093, B2020402002, and the Science and Technology
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