SusChemE 2015
International Conference on Sustainable Chemistry & Engineering
October 8-9, 2015, Hotel Lalit, Mumbai
Sulfonated Mesoporous Polydivinylbenzene (PDVB) as Efficient Catalytic for Room
temperature Synthesis of Solketal
Sathyapal R. Churipard‡, Pandian Manjunathan‡, Prakash Chandra‡, Ganapati V. Shanbhag‡, A.B.
Halgeri‡ and Sanjeev P. Maradur*‡
‡Materials Science Division, Poornaprajna Institute of Scientific Research (PPISR), Bidalur Post, Devanahalli, Bangalore562164, Karnataka State, India.
Email : sanjeevpm@poornaprajna.org
Introduction:
Acetalization of glycerol with acetone is very significant reaction for synthesis of solketal, used as an additive in
formulation of diesel, biodiesel and gasoline fuels. [1] Various heterogeneous solid acid catalysts have been used for acetalization
of glycerol with acetone.[2] Recently, we reported room temperature synthesis of solketal using H-Beta zeolite.[3] However,
downside of the solid acid catalysts hydrophilic framework largely affecting their catalytic performance because water is formed
as a byproduct in acid-catalyzed reaction deactivates the catalyst due to competition amongst the water molecules and the
reactant species. Herein, we report the utilization of sulfonic acid functionalized mesoporous polymer catalyst (MP-SO3H) for
solketal synthesis by the reaction of glycerol with acetone.
Materials and method:
Swelling mesoporous polydivinylbenzene polymer (MP) was synthesized by using AIBN initiator by hydrothermal
method. Sulfonation was done with conc. H2SO4 and Ag2SO4 (catalyst) at 80 oC for x h (x = 4, 8, 12 and 24 h). The obtained
samples filtered, washed with water and dried overnight and the samples are designated as MP-SO3H-x (x = 4, 8, 12 and 24).
Catalytic reactions were carried out by using the required amount of glycerol and acetone in a glass reactor along with
preactivated catalyst. Samples were periodically withdrawn and analyzed by using GC and confirmed by using the product
standard.
Significant results and discussion:
The physicochemical characterization results are briefly summarized here. FT-IR spectroscopic analysis of MP-SO3H-x
show band at ~1045 cm-1 due to the stretching vibration of C-S present in -SO3H bond. Nitrogen adsorption-desorption
isotherms of MP and MP-SO3H-x catalysts show typical Type IV isotherm, which is the characteristic property of mesoporous
materials. The specific surface area, pore volume and pore diameter reduced after the sulfonation due to incorporation -SO3H
groups.
The catalytic activity of MP-SO3H resins was tested for solketal synthesis (Table 1). MP-SO3H catalysts showed an
increase in surface density of H+ from 2.8 to 4.4 H+ nm-2 and glycerol conversion from 72 to 85.6% (Fig. 1b). MP-SO3H-24
outperformed other porous and nonporous solid acid [Table 1 and Fig 1(a)] catalyst due to an enhanced accessibility of acidic
sites in larger mesoporous surface area and easy diffusion of products due to larger pore size. Heterogeneity test as well as
recycle studies confirmed that the reaction is truly heterogeneous and no leaching of active sites occurred.
Table 1. Comparison of catalytic activity of MP-SO3H-24 with various solid acid catalysts
Catalyst
Glycerol conversion
(1) (wt%)
Solketal selectivity
(3) (wt%)
Solketal Yield
(wt%)
Amberlyst-15
H-Beta
H-ZSM-5
K-10
MoO3/SiO2
SO42-/ZrO2
MP-SO3H-24
26
56
10
15
5.3
43
85.6
89
97
88
90
80
97
98.5
23.1
54.3
8.8
13.5
4.2
41.7
84.3
Reaction conditions: Glycerol: acetone = 1:2, catalyst = 0.5wt% (referred to glycerol weight), reaction
temperature = 30 °C, time 30 min.
1
SusChemE 2015
International Conference on Sustainable Chemistry & Engineering
October 8-9, 2015, Hotel Lalit, Mumbai
Fig.1. (a) Plot of catalytic activity of MP-SO3H containing different amounts of acidity; (b) Co-relation plot
for glycerol conversion vs amount of acidity (mmol H+/g) vs surface density (H + nm-2). Reaction conditions:
Glycerol: acetone = 1:2, catalyst = 0.5wt% (referred to glycerol weight), reaction temperature = 30 °C, time
30 min.
Conclusions
Sulfonic acid functionalized mesoporous polymers (MP-SO3H) were successfully prepared and applied as catalyst in
glycerol acetalization with acetone. MP-SO3H-24 showed higher activity and recyclability as compared to other conventional
solid acid catalysts due to the easy accessibility of active sites in large mesoporous surface area and facile outward diffusion of
products due to large pore size.
Reference
[1]
N. Suriyaprapadilok, B. Kitiyanan, Energy Procedia 2011, 9, 63-69.
[2]
Y. Zheng, X. Chen, Y. Shen, Chemical Reviews 2008.
[3]
P. Manjunathan, S. P. Maradur, A. Halgeri, G. V. Shanbhag, Journal of Molecular Catalysis A: Chemical 2015, 396,
47-54.
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