Sulfonated porous organic polymer as a highly efficient catalyst for the synthesis of biodiesel at room temperature

Article abstract of DOI:10.1016/j.molcata.2015.10.016

A new functionalized porous organic polymer bearing sulfonic acid groups (PDVTA-SO₃H) at the pore surface with high surface area (S_BET = 406 m² g^-1) and Bronsted acidity is reported. The material has been synthesized via post-synthetic sulfonation of the porous co-polymer poly-divinylbenzene-co-triallylamine (PDVTA-1) using chlorosulfonic acid as sulfonating agent. A detailed characterization of the -SO₃H functionalized porous polymeric material has been carried out using N₂ sorption, FT-IR and UV-vis spectroscopy, HR-TEM, FE-SEM, thermogravimetric and elemental analyses. Temperature programmed desorption of NH₃ (TPD-NH₃ analysis) of PDVTA-SO₃H revealed a very high surface acidity of 2.3 mmol g^-1. Such high acidity of PDVTA-SO₃H has been explored to investigate its catalytic efficiency towards eco-friendly production of biodiesel via esterification of long-chain free fatty acids (FFA) to the respective fatty acid monoalkyl esters (FAMEs) at room temperature using methanol as reactant as well as solvent. The sulfonated porous polymer is found to be a very active and reusable solid acid catalyst giving high yields (～92-98%) of various biodiesel compounds under very mild reaction conditions.

Full text of DOI:10.1016/j.molcata.2015.10.016

Accepted Manuscript
Title: Sulfonated porous organic polymer as a highly efficient
catalyst for the synthesis of biodiesel at room temperature
Author: Ruth Gomes Piyali Bhanja Asim Bhaumik
PII:
S1381-1169(15)30119-9
DOI:
Reference:
http://dx.doi.org/doi:10.1016/j.molcata.2015.10.016
MOLCAA 9659
To appear in:
Journal of Molecular Catalysis A: Chemical
Received date:
Revised date:
Accepted date:
12-8-2015
9-10-2015
13-10-2015
Please cite this article as: Ruth Gomes, Piyali Bhanja, Asim Bhaumik, Sulfonated
porous organic polymer as a highly efficient catalyst for the synthesis of
biodiesel at room temperature, Journal of Molecular Catalysis A: Chemical
http://dx.doi.org/10.1016/j.molcata.2015.10.016
This is a PDF file of an unedited manuscript that has been accepted for publication.
As a service to our customers we are providing this early version of the manuscript.
The manuscript will undergo copyediting, typesetting, and review of the resulting proof
before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that
apply to the journal pertain.

Sulfonated porous organic polymer as a highly efficient
catalyst for the synthesis of biodiesel at room temperature
Ruth Gomes, Piyali Bhanja and Asim Bhaumik*
Department of Material Science, Indian Association for the Cultivation of Science, Jadavpur,
Kolkata - 700032, India
*
Corresponding author. Tel.: +91 33 2473 4971, E-mail: msab@iacs.res.in
1

GRAPHICAL ABSTRACT
A new porous organic polymer functionalized with sulfonic acid groups and high Brønsted acidity is
reported. The material showed excellent catalytic activity for the biodiesel synthesis at room temperature.
2

Research Highlights



Synthesis of a sulfonic acid grafted porous organic polymer PDVTA-SO
synthetic functionalization method.
The polymer possess high surface area (SBET = 406 m g ) and high surface acidity 2.3
3
H, by post
2
-1
-1
mmolg .
PDVTA-SO H showed high catalytic activity for the synthesis of biodiesel compounds
3
from long chain fatty acids.
3

Abstract
A new functionalized porous organic polymer bearing sulfonic acid groups (PDVTA-SO H) at
3
2
-1
the pore surface with high surface area (SBET = 406 m g ) and Brønsted acidity is reported. The
material has been synthesized via post-synthetic sulfonation of the porous co-polymer poly-
divinylbenzene-co-triallylamine (PDVTA-1) using chlorosulfonic acid as sulfonating agent. A
detailed characterization of the -SO
out using N sorption, FT-IR and UV-Vis spectroscopy, HR-TEM, FE-SEM, thermogravimetric
and elemental analyses. Temperature programmed desorption of NH (TPD-NH analysis) of
H revealed a very high surface acidity of 2.3 mmol g . Such high acidity of
H has been explored to investigate its catalytic efficiency towards eco-friendly
3
H functionalized porous polymeric material has been carried
2
3
3
-1
PDVTA-SO
3
3
PDVTA-SO
production of biodiesel via esterification of long-chain free fatty acids (FFA) to the respective
fatty acid monoalkyl esters (FAMEs) at room temperature using methanol as reactant as well as
solvent. The sulfonated porous polymer is found to be a very active and reusable solid acid
catalyst giving high yields (~92-98%) of various biodiesel compounds under very mild reaction
conditions.
Keywords: Porous organic polymer; sufonic acid functionalization; high surface acidity;
biodiesel synthesis.
4

Introduction
Synthesis of biofuel compounds i.e. fatty acid monoalkyl esters (FAMEs) are of huge
demand as they provide renewable, non-toxic and eco-friendly source of energy and a possible
replacement of fossil fuels [1]. Large scale use of the fossil fuels with the advancement of
today’s world would cause severe energy crisis in future due to its limited reserves, emission of
greenhouse gases and environmental pollution caused during their ignition. Biofuel compounds
can overcome such problems as they are renewable and can be produced from low cost resources
such as animal fat and vegetable oil containing free fatty acids (FFA) [2-6]. The biodiesel
compounds can be synthesized by esterification of long chain fatty acids with aliphatic alcohols.
However, the commercial production of biodiesel is associated with major problems of high
production cost, product isolation, catalyst separation etc. as the synthesis involves homogeneous
strong acid or base catalyzed esterification of fatty acids. The conventional use of concentrated
sulfuric acid as homogeneous acid catalyst is not very favorable due to its corrosive nature.
Although the base catalyzed synthesis of biodiesel via transesterification reaction occurs at low
temperature and lesser reaction time but the process requires a pre-esterification step to prevent
saponification between the FFAs and base. This is because of the fact that low-cost feedstock
containing high FFA causes saponification under basic condition, which leads to a major
problem in product separation and the process consumes large excess of catalyst. Thus, a wide
scale research focusing on the design of suitable heterogeneous solid acid catalysts has been
undertaken [7,8]. Several solid acids have been reported till date to catalyze the esterification
reaction, such as transition metal oxides [9-11], Au NP/nanoporous polymer [12], ion exchange
resins [13], molecular sieves [14], functionalized silica [15], zeolites [16], metallo phosphates
[
17,18], metal organic framework [19], functionalized porous carbons [20,21] and mesoporous
silica materials [22-24]. But for most of these cases the reaction needs high temperature and
pressure due to low concentrations of the catalytically active sites.
On the other hand porous organic polymers bearing suitable functional groups at the pore
surface are very demanding. These materials are potential candidates for a wide range of
application areas such as gas adsorption [25-27], catalysis of various important organic
transformations [28-34], drug delivery vehicle [35], sensing [35,36] and so on. Due to high
specific surface area and pore volume the target molecule can interact more easily with the
required functional group present at the surface compared to non-porous materials. Intense
5

research has being carried out on the designing of appropriate porous organic polymers for
catalytic applications. Porous polymers rich in acidic functionality are thus highly demanding for
the synthesis of biodiesels via esterification/transesterification reactions. In our present work, we
report the synthesis of a new solid acid catalyst containing –SO H group in the porous organic
3
polymer network with high surface acidity for the synthesis of biodiesel products. The catalyst is
thoroughly characterized using various instrumental techniques to investigate its BET surface
area/porosity, framework-bondings, chemical environment, thermal stability and surface acidity.
Various long chain fatty acids are used for the catalytic reactions and we have measured the
recycling efficiency of the catalyst.
Experimental Section
Materials
Divinylbenzene (DVB, monomer) and triallylamine (TAA, monomer) were obtained
from Sigma Aldrich. Azobisisobutyronitrile (AIBN, radical initiator) was obtained from SRL
and recrystallized from hot ethanol prior to use. Chlorosulfonic acid was purchased from
Spectrochem, India. All other chemicals used in the experiments were of analytical grade
produced by E-Merk.
Instrumentation
A Perkin Elmer Spectrum 100 was used to record the FT IR spectra of the PDVTA-1 and
PDVTA-SO
3
H. A UV 2401PC with an integrating sphere attachment was used to obtain the UV-
as the background standard. N
Visible diffuse reflectance spectra of the materials using BaSO
4
2
adsorption/desorption isotherms of the porous organic polymers before and after sulfonation was
recorded in a Quantachrome Autosorb 1-C at 77 K. The samples were degassed at 373 K for 8 h
under high vacuum conditions prior to the measurement. High resolution transition electron
microscopic (HR TEM) images of the catalyst were recorded using a JEOL 2010 TEM operated
at 200 kV. Morphology and particle size of the sample was analyzed by using a Jeol JEM 6700
field emission scanning electron microscope (FE SEM). Elemental analyses of the materials
were carried out using a Perkin Elmer 2400 Series II CHN analyzer. Thermogravimetric analysis
(TGA and DTA) of the catalyst was carried out between the temperature ranges from 308 to 873
6

K in a thermal analyzer TA-SDT Q-600 under N
TPD) of ammonia of the catalyst was recorded using a thermal conductivity detector (TCD) in a
Micromeritics Chemisorb 2720 instrument. For the experiment, the material was first degassed in
flow of He at a flow rate of 30 ml/min for 2 h at 373 K followed by saturating it with 10 % NH
in He at room temperature for 30 min. Then the excess NH was removed by flow of He (flow
2
flow. The temperature programmed desorption
(
3
3
rate 30 ml/min) for 45 min and the desorption pattern of ammonia (carrier gas He) was studied
by heating the sample from room temperature to 673 K at a temperature ramp of 10 ºC/ min. The
1
13
H and C NMR spectra of the biodiesel compounds were recorded in a Bruker Advance 500
MHz NMR spectrometer.
Synthesis of the catalyst PDVTA-SO H
3
The porous organic polymer PDVTA-1 was synthesized as described before [37] through
solvothermal co-polymerization of divinylbenzene and triallylamine by using AIBN as a radical
polymerization initiator. For a typical synthesis of PDVTA-1, 521 mg divinylbenzene (4 mmol)
and 137 mg triallylamine (1.0 mmol) were taken in a 50 mL round bottom flask. Then 10 mL dry
acetone was added and the mixture was continuously stirred for 10 min under inert atmosphere.
2
5 mg AIBN (0.15 mmol) was then added to the mixture and resulting slurry was stirred for 3 h
at room temperature. Finally the resultant mixture was autoclaved at 393 K for 24 h under static
conditions. The final product was washed thoroughly with acetone and dried at 373 K. For the
sulfonation step, 200 mg of the polymer was taken in a 100 mL round bottom flask and 50 mL
anhydrous dichloromethane was added to it. The mixture was cooled in an ice-salt bath and 5 mL
chlorosulfonic acid was added drop wise to it. The reaction was allowed to stir at room
temperature under inert atmosphere for 4 h. The final deep brown precipitate was filtered,
washed several times with distilled water and dried under vacuum. The thus prepared light
brown colored sulfonated polymer was then thoroughly characterized before studying its
catalytic application.
7

Esterification of long chain fatty acids
For the synthesis of biodiesel compounds 1 mmol of each of the long chain fatty acids
were taken in 5 mL of methanol. 10 mg PDVTA-SO H was added to the reaction mixtures under
3
stirring condition and the esterification was allowed to proceed at room temperature. The
progress of the reaction was monitored by TLC. After completion of the reaction, the catalyst
was filtered off and the solvent was removed in a rotary evaporator to get the desired product.
The solid compounds were characterized by H and 13C NMR spectroscopy. The separated
catalyst was washed several times with methanol, dried in vacuum and reused further to check its
recycling efficiency.
1
Results and Discussion
Nitrogen adsorption/desorption analysis
In Fig. 1 nitrogen adsorption/desorption isotherms of them porous organic polymers are
shown. As seen from this figure that PDVTA-1 gave a type IV isotherm with a significant
hysteresis loop in the high pressure region, indicating the presence of mesopores in the
framework [37]. Moreover, a large amount of nitrogen uptake is observed in the low pressure
region (below 0.1 bar). This result suggests the presence of sufficient amount of micropores in
2
-1
-1
PDVTA-1. BET surface area and pore volume of the polymer was 903 m g and 0.472 ccg
respectively. Fig. 1b showed the nitrogen adsorption/desorption isotherm of the sulfonated
polymer PDVTA-SO H, which follows similar pattern as that of the parent polymer. This
isotherm revealed a BET surface area of 406 m g and a pore volume of 0.222 ccg . The pore
size distribution of the porous organic polymer before and after grafting of SO H group is
3
2
-1
-1
3
estimated using nonlocal density functional theory (NLDFT) (Fig. 1, below). Here both the
polymers showed heirarchical porosity having pores of dimensions 1.5 nm and 4.1 nm for
PDVTA-1 and 1.5 nm, 2.6 nm and 4.8 nm for PDVTA-SO H, respectively. The micropore and
3
2
-1
mesopore contributions to the surface area of PDVTA-1 was calculated to be 779 m g and 123
m2g-1 respectively from De Boer statistical thickness (t-plot), whereas these values after
2
-1
2 -1
sulfonation was 338 m g and 68 m g , respectively.
8

Spectroscopic analysis
The FT IR spectra of the polymer PDVTA-1 before and after sulfonation is shown in Fig.
-1
2
, where both the spectrum exhibited similar type of peaks in the region 3100-3000 cm due to
-1
the aromatic stretching vibration. The peaks at 2932 and 2848 cm could be assigned due to the
methylene C-H stretching vibrations. The aromatic C=C stretching vibration of the benzene ring
-1
-1
appeared at 1512 and 1605 cm , whereas the C-N stretching comes at 1370 cm . The other
peaks at 794 and 710 cm-1 could be assigned to the aromatic C-H bending vibration.
Additionally, the FT-IR spectrum of the sulfonated polymer PDVTA-SO
3
H exhibited strong
-1
-1
peaks at 1170 cm (SO
3
- stretching) and 1040 cm (O=S=O stretching in SO H), which
3
indicated the successful incorporation of sulfonic acid group in the polymer [38]. Further, the
UV-Vis spectra of porous PDVTA-1 before and after sulfonation are shown in Fig. 3a and 3b,
respectively. The spectra shows absorption peaks corresponding to different aliphatic and
aromatic chromophoric moieties. After sulfonation the absorption maxima has been shifted to
higher wavelength, which confirms that the –SO H group has been successfully grafted on the
3
polymer surface. The broad band at 298 nm could originate due to the chromophoric -SO
3
H
group.
Temperature programmed desorption of NH and thermogravimetric analysis
3
The plot for the TCD (thermal conductivity detector) signal versus temperature obtained
from the temperature programmed desorption profile of NH for the sulfonated polymer
PDVTA-SO H is shown in Fig. 4A. The profile showed two distinct peaks at temperatures 349
and 583 K. The first peak corresponds to a NH
3
3
-1
3
uptake of volume 51.52 mL g , which
-1
corresponds to a total acidity of 2.3 mmol g . The second peak at higher temperature could be
assigned due to the desulfonation of the material, which is also confirmed from the
thermogravimetric analysis. The TGA-DTA plot of PDVTA-SO
sulfonated polymer starts decomposing after 473 K, whereas the parent polymer is stable up to
63 K. Elemental analysis of PDVTA-1 and PDVTA-SO H gives the C, H and N contents as: C
88.95%, H = 6.56%, N = 2.15%, and C = 85.03%, H = 5.94% and N = 1.34, respectively.
3
H (Fig. 4B) showed that the
5
3
=
9

Electron microscopic studies
The porous structure and morphology of sulfonated polymer have been analyzed by using
high resolution transmission electron microscopy and field emission scanning electron
microscopy. The TEM image of PDVTA-SO H is shown in Fig. 5A, which showed micropores
3
of dimension 1.4 nm and these are randomly arranged all over the framework. This result
matches well with the micropore dimension obtained applying the NLDFT model on the nitrogen
adsorption/desorption isotherm of the material (Fig. 1). On the other hand, the FE-SEM image of
the polymeric material PDVTA-SO H shown in Fig. 5B revealed self-assembled particles of
3
spherical morphology, the dimension of which lies between 1.2-2.0 µm. Each of the spherical
structure is made of small spherical nanoparticles having average dimensions ca. 25 nm.
Catalysis
The catalytic activity of the solid acid catalyst PDVTA-SO H has been estimated for the
3
synthesis of biodiesel products, which involves esterification of long-chain fatty acid under very
mild reaction conditions. We have carried out the reactions with different long chain mono and
dicarboxylic acids at room temperature in methanol, where methanol was used both as solvent as
well as reagent. The yields for each of the reactions are listed in Table. 1. From the table it is
clear that the yields of the desired fatty acid methyl esters for lauric, myristic, palmitic, stearic
and oleic acids are above 92%. Among the dicarboxylic acids, we have used adipic and sebacic
acids, and for them the yields for the respective methyl esters are 95 and 97%, respectively.
1
13
These FAMEs are biodiesel compounds and these are characterized using H and C NMR
spectroscopy (ESI Fig. 1 to Fig. 14). We have also carried out the esterification of adipic acid in
the absence of any catalyst (entry 8, Table. 1), which gave very poor yield of the product (5 %).
The effect of reaction time on the yield of different fatty acid ester is shown in Fig. 6. As seen
from the figure that reaction rate steadily increases from 60 to 95 wt% during 2 to 12 h reaction
time for various fatty acids and reached the plateau. The recycling ability of PDVTA-SO H for
3
the esterification of adipic acid is shown in Fig. 7. The catalyst has been successfully recycled
for six consecutive cycles for the esterification of adipic acid and it was found that no significant
loss of catalytic activity occurs after sixth cycle. The yield of methyl adipate decreased only 2.3
1
0

%
after sixth cycle compared to the yield in the first catalytic cycle. This result suggested that
sulfonated poly-divinylbenzene-co-triallylamine polymer is a very efficient catalyst for the
esterification of long chain fatty acids under very mild reaction conditions. A comparison of
PDVTA-SO H with other reported solid acid catalysts used for the biodiesel production reaction
3
is provided in Table 2. Although the catalyst sPS-S resulted maximum product yield, but much
higher temperature is required to carry out the esterification reaction [39]. The higher BET
surface area, pore volume and surface acidity of PDTA-SO H with respect to the related solid
3
acid catalysts [40] could be responsible for higher yield of the desired biodiesel compounds
under relatively milder reaction conditions.
Characterization of the reused catalyst
The reused porous polymer catalyst has been further characterized after six reaction
cycles by using FT-IR, N
respectively). The BET surface area of the reused catalyst was found to be 403 m g with similar
pore size distribution pattern to that of the fresh PDVTA-SO H material. The FT-IR and HR-
2
-sorption and HR-TEM analysis (ESI Fig. S15, S16 and S17,
2
-1
3
TEM analysis of the reused catalyst revealed no significant change in the morphology and
nanostructure of the catalyst. The surface acidity of the polymeric material after the catalytic
-1
reactions was checked using NH -TPD analysis and it has been estimated as 2.26 mmol g (ESI
3
-1
Fig. S18), which is very close to the acidity of the fresh catalyst (2.26 mmol g ). These results
suggested that the sulfonated porous polymer catalyst is highly stable and it retained its activity
under the liquid phase reaction conditions.
Conclusions
A new sulfonic acid functionalized porous organic polymer has been synthesized via
post-synthetic sulfonation of the porous polymer poly-divinylbenzene-co-triallylamine. The
materials showed high BET surface area, presence of a wide range of pores in nanoscale
dimensions and high Brønsted acidity. It showed excellent catalytic efficiency for the production
of biodiesel products via esterification of long-chain free fatty acids at room temperature. High
1
1

catalytic efficiency for the sulfonated porous polymer may open its future potential as
heterogeneous acid catalyst for a wide range of reactions under eco-friendly conditions.
Acknowledgements
RG and PB thanks CSIR, New Delhi for respective senior and junior research
fellowships, respectively. AB wishes to thank DST, New Delhi for instrumental facilities
through DST Unit on Nanoscience and DST-SERB project grants.
1
2

REFERENCES
[
1] H. Baumann, M. Buhler, H. Fochem, F. Hirsinger, H. Zoebelein, J. Falbe, Angew, Chem.
Int. Ed. Engl. 27 (1988) 41-62.
[
[
2] H. J. Berchmans, S. Hirata, Bioresour. Technol. 99 (2008) 1716-1721.
3] L. T. H. Nam, T. Q. Vinh, N. T. T. Loan, V. D. S. Tho, X.Y. Yang, B. L. Su, Fuel 90
(2011) 1069–1075.
[
[
[
[
[
[
4] L. Soh, J. Zimmerman, Green Chem. 13 (2011) 1422-1429.
5] D. Elhamifar, B. Karimi, A. Moradi, J. Rastegar, ChemPlusChem 79 (2014) 1147-1152.
6] P. Hidalgo, G. Ciudad, M. Mittelbach, R. Navia, Fuel 153 (2015) 544-551.
7] F. Su, Y. Guo, Green Chem. 16 (2014) 2934-2957.
8] C. Poonjarernsilpa, N. Sanoa, H. Tamon, Appl. Catal., A: Gen. 497 (2015) 145-152.
9] M. L. Grecea, A. C. Dimian, S. Tanase, V. Subbiah and G. Rothenberg, Catal. Sci.
Technol. 2 (2012) 1500-1506.
[
10] Y. Kuwahara, W. Kaburagi, K. Nemoto, Tadahiro Fujitani, Appl. Catal. A: Gen. 476
(2014) 186-196.
[
[
[
[
11] S. Xia, X. Guo, D. Mao, Z. Shi, G. Wu, G. Lu, RSC Adv. 4 (2014) 51688-51695.
12] A. Buonerba, A. Noschese, A. Grassi, Chem. Eur. J. 20 (2014) 5478-5486.
13] J. Fu, L. Chen, P. Lv, L. Yang, Z. Yuan, Fuel 154 (2015) 1-8.
14] E. E. Macias, C. A. Deshmane, J. B. Jasinski, M. A. Carreon, P. Ratnasamy, Catal.
Commun. 12 (2011) 644-650.
[
15] Y. D. Chiang, S. Dutta, C. T. Chen, Y. T. Huang, K. S. Lin, J. C. S. Wu, N. Suzuki, Y.
Yamauchi, K. C. W. Wu, ChemSusChem 8 (2015) 789-794.
[
[
[
16] N. Narkhede, A. Patel, RSC Adv. 4 (2014) 64379-64387.
17] S. K. Das, M. K. Bhunia, A. K. Sinha, A. Bhaumik, ACS Catal. 1 (2011) 493-501.
18] H. Q. Yang, H. Y. Song, H. Zhang, P. Chen, Z. X. Zhao, J. Mol. Catal. A: Chem. 381
(2014) 54-60.
[
[
19] F. G. Cirujano, A. Corma, F. X. L. I. Xamena, Chem. Eng. Sci. 124 (2015) 52-60.
20] L. J. Konwar, R. Das, A. J. Thakur, E. Salminen, P. Maki-Arvela, N. Kumar, J. P. Mikkola,
D. Deka, J. Mol. Catal. A: Chem. 388 (2014) 167-176.
[
21] R. A. Arancon, H. R. B. Jr, A. M. Balu, C. Vargas, R. Luque, Green Chem. 13 (2011)
3
162-3167.
1
3

[
[
[
22] H. Wan, Z. Wu, W. Chen, G. Guan, Y. Cai, C. Chen, Z. Li, X. Liu, J. Mol. Catal. A: Chem.
98 (2015) 127-132.
23] L. Wei, M. Fengyan, S. Fang, M. Ling, Z. Shengqu, G. Yihang, ChemSusChem 4 (2011)
44-756.
3
7
24] S. Y. Chen, T. Yokoi, C. Y. Tang, L. Y. Jang, T. Tatsumi, J. C. C. Chan, S. F. Cheng,
Green Chem. 13 (2011) 2920-2930.
[
[
25] X. Zhang, J. Lu, J. Zhang, Chem. Mater. 26 (2014) 4023-4029.
26] R. L. Martin, C. M. Simon, B. Smit, M. Haranczyk, J. Am. Chem. Soc. 136 (2014) 5006-
5
022.
27] A. Modak, M. Pramanik, S. Inagaki, A. Bhaumik, J. Mater. Chem. A 2 (2014) 11642-
1650.
[
1
[
[
[
[
[
28] A. Modak, J. Mondal, A. Bhaumik, ChemCatChem 5 (2013) 1749-1753.
29] A. Modak, J. Mondal, A. Bhaumik, Appl. Catal. A: Gen. 459 (2013) 41-51.
30] A. Schade, L. Monnereau, T. Muller, S. Braese, ChemPlusChem 79 (2014) 1176-1182.
31] Y. Wang, L. Wang, C. Liu, R. Wang, ChemCatChem 7 (2015) 1559-1565.
32] Q. Sun, Z. Dai, X. Liu, N. Sheng, F. Deng, X. Meng, F. S. Xiao, J. Am. Chem. Soc. 137
(
2015) 5204-5209.
33] J. Mondal, M. Nandi, A. Modak, A. Bhaumik, J. Mol. Catal. A: Chem. 363-364 (2012)
54-264.
[
2
[
[
34] P. Borah, J. Mondal, Y. Zhao, J. Catal. 330 (2015) 129-134.
35] S. Bhunia, N. Chatterjee, S. Das, K. Das Saha, A. Bhaumik, ACS Appl. Mater. Interfaces 6
(
2014) 22569-22576.
36] S. H. Wibowo, A. Sulistio, E. H. H. Wong, A. Blencowe, G. G. Qiao, Adv. Funct. Mater.
2015) DOI: 10.1002/adfm.201404091.
[
(
[
[
37] R. Gomes, A. Bhaumik, J. Solid State Chem. 222 (2015) 7-11.
38] L. Peng, A. Philippaerts, X. X. Ke, J. Van Noyen, F. De Clippel, G. Van Tendeloo, P. A.
Jacobs, B. F. Sels, Catal. Today 150 (2010) 140-146.
[
[
39] Y. Chang, C. Lee, C. Bae, RSC Adv. 4 (2014) 47448-47454.
40] S. K. Kundu, A. Bhaumik, ACS Sustainable Chem. Eng. 3 (2015) 1715-1723.
1
4

Caption for figures
Figure 1.(A) N2 adsorption (filled)–desorption (empty) isotherms of (a) PDVTA-1 and (b)
PDVTA-SO3H at 77 K. (B) Their pore size distribution using the Non Local Density Functional
Theory (NLDFT) Model is shown respectively.
1
5

Figure 2.FT-IR spectra of PDVTA-1 (black) and PDVTA-SO3H (red).
Figure 3.UV-Vis spectra of PDVTA-1 (black) and PDVTA-SO3H (red).
1
6

Figure 4.(A) Temperture programmed desorption profile of NH3 for PDVTA-SO3H. (B) TGA
and DTA profile of PDVTA-1 (black) and PDVTA-SO3H (red).
1
7

Figure 5.(A) HR-TEM image of PDVTA-SO3H. (B) FE-SEM image of PDVTA-SO3H.
Figure 6.Effect of reaction time on the yield of different fatty acid ester.
1
8

Figure 7.Recycling efficiency of PDVTA-SO3H for transesterification of adipic acid.
1
9

Scheme 1: Schematic representation of the synthesis of sulfonated porous organic co-polymer
PDVTA-SO H.
3
2
0

Table 1. PDVTA-SO
3
H catalyzed esterification of different long-chain free fatty acids with
methanol.a
Yield
Acid :
of
Entr
MeOH Tim
produc
t (%)
Fatty acid
y
Esters of fatty acid
(mmol e (h)
)
1
2
CH
3
3
(CH
2
2
)
10COOH
12COOH
1:10
1:10
10
10
98
97
CH
(CH
)
3
4
CH
3
(CH
2
)
14COOH
1:10
1:10
10
12
98
95
CH
3
3
(CH
2
2
)
)
16COOH
CH
H
(CH
7
CH=CH(CH
2
7
) COO
5
6
1:10
1:20
10
10
92
95
HOOC-(CH
HOOC-(CH
HOOC-(CH
2
)
)
)
4
-COOH
-COOH
-COOHb
7
8
2
8
1:20
1:20
12
24
97
2
4
5.0
aReaction condition: fatty acid (1 mmol), methanol (5 mL), PDVTA-SO
H (10 mg), Reaction
3
b
temperature 298 K, Reaction was carried out in absence of any catalyst.
2
1

Table 2. Comparison of solid acid catalyst for esterification of fatty acid.
Catalyst
BET
Pore
Acidity
Feedstoc Reaction
Yield Reusability
(%)
Ref
39
surface volume (mmol g-
k
condition
(ccg ) 1)
-
1
area
2
-1
(
m g )
Amberlyst 45
15
_
4.8
Lauric
acid
20.0 g FFA, 57
FFA/MeOH
_
-
=1/16 (molar
ratio),
catalyst (0.5
wt%), 338 K,
6
h
sPS-S
0.10
_
1.67
Lauric
acid
20.0 g FFA, 100
FFA/MeOH
Checked up 39
to 10 catalytic
cycle
=1/16 (molar
ratio),
catalyst (0.5
wt%), 338 K,
8
h
SPPOP-1 280
0.181
0.222
2.15
Lauric
acid
1 mmol FFA, 90
1.6 g MeOH,
Reusable up 40
to 6 catalytic
cycle,
2
5
mg
catalyst, 298
K, 10h
PDVTA-
SO
406
2.3
Lauric
acid
1 mmol FFA, 98
5 mL MeOH,
Checked up This
to 6 catalytic wor
3
H
1
0
mg
cycle,
k
catalyst, 298
K, 10h
no significant
loss is activity
2
2