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Heterogeneous Catalysis for Biodiesel Synthesis and Valorization of Glycerol
Presented by
Dheerendra Singh
Under the guidance of
Prof. Sanjay M. Mahajani
Prof. Anuradda Ganesh
4thInternational Conference on "Advances in Energy Research"
Introduction
Biodiesel is a mixture of fatty acid methyl esters (FAME)
Transesterification of vegetable oils in presence of NaOH/KOH as catalyst
Heterogeneous catalysts have an added advantage i. e. ease of separation
ZnO & PbO on zeolite are promising catalysts for producing biodiesel using jatropha oil.
Catalysts are characterized by XRD, BET, TEM, SEM and TPD/TPR.
The leaching of metal ions is minimized with zeolite as support material.
Glycerol is obtained as a by-product (~10 wt %) in biodiesel production
Mono-glyceride and Glycerol carbonate are synthesized by esterification and
transesterification of glycerol.
2 / 18
Glycerol
Vegetable oil + Methanol Biodiesel Glycerol+
Fatty acid
UreaDMC
Mono-glyceride
Glycerol carbonate
Glycerol carbonate+
+NH3
Methanol
Urea Methanol DMC NH3
NH3 CO2 Urea
+ +
+
General schematic of reactions considered in the present work
3 / 18
Methodology
Schematic of continuous packed bed reactor
Materials:Jatropha oil and sunflower oil for Biodiesel Synthesis and oleic acid for esterification of glycerol
Catalyst Preparation: Precipitation HIP Method1 Modified citrate technique2
4 / 18
Batch Reactor
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 802
ZSM5
ZnO
(1 0
3)
ZnO
(1 1
0)
ZnO
(1 0
2)
ZnO
(1 0
1)
ZnO
(0 0
2)
ZnO
(1 0
0)
ZnO/ZSM5
Inte
nsity
(a.
u.)
PbO/ZSM5
MgO
(3 1
1)
MgO
(2 2
0)
MgO
(2 0
0)
MgO
(1 1
1)
MgO
(2 2
2)
MgO
1. X-Ray Diffraction
Two separate phases (ZnO and Zeolite) are observed
The average crystallite size of ZnO is estimated with the help of Scherrer equation
and is found to be 22.15 nm.
Intensity of PbO in PbO/ZSM-5 very small 5 / 18
Catalyst Characterization
SEM imaging of the catalyst ZnO/zeolite, PbO/zeolite and MgO
2. Scanning electron microscopy (SEM)
The shape of zeolite (support) particles were non-uniform and the particle size
distribution was large with size varying from 50 to 300 nm.
MgO catalyst has porous texture with uniform particle size of 20 nm.
6 / 18
14 16 18 20 22 24 26
Cou
nts
Particle size (nm)
2 3 4 5 6 7
Cou
nts
Particle size (nm)
TEM imaging of the catalyst ZnO/zeolite, PbO/zeolite and MgO
3. Transmission electron microscopy (TEM)
ZnO particle size varies from 14 nm to 26 nm and the average particle size is 19.54 nm
The particle size of PbO varies from 2.9 nm to 6.8 nm with an average particle size of 4.2 nm
Particle size of MgO is ~ 20 nm.
0 10 20 30 40 50 600
10
20
30
40
50
60
70
80
90
100
Wt %
of c
ompo
nent
s
Time (min)
Wt% MG Wt% FFA Wt% DG Wt% TG Wt % BD
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200 250 3000
10
20
30
40
50
60
70
80
90
100
% T
G conversion
Zn
leac
hing
(pp
m)
TG conversion
Zn leaching
Time (hr)
Performance Evaluation of 3ZnO/ZSM-5 catalyst in batch and continuous reactors
[Reaction temperature, 200°C; methanol: jatropha oil molar ratio, 6:1]
[Oil (Jatropha): Methanol 1:30, Temperature 200 °C, Catalyst loading 0.50 wt %, RPM 500]
Sample Zn/Pb (ppm)
Blank (perchloric acid) Not detected
ZnO powder >1238.15
ZnO/γ-alumina 920.575
ZnO/α-alumina 614.033
ZnO/ZSM-5 127.523
PbO powder >3400
PbO/γ-alumina >464
PbO/β-zeolite 9.29
Comparison of Zn/Pb leaching on different supports
The conversion of jatropha oil and the yield of
biodiesel using ZnO/zeolite and PbO/zeolite are
found to be approximately 100 % and 93.8 % at
optimum reaction conditions.
[4] Singh et al. (under review) 8 / 18
1. Biodiesel synthesis
0 100 200 300 400 500 600
TCD
Sig
nal
Temperature (oC)
ZnO/ZSM-5
ZSM-5
0 100 200 300 400 500 600 700 800 900
0 100 200 300 400 500 600 700 800 900
Temperature oC
PbO
25 % PbO/Alumina
25 % PbO/ZSM-5
30 % PbO/ZSM-5
4. Thermal program method
TPD of ZSM-5 and ZnO/ZSM-5
TPR of PbO supported catalyst
9 / 18
Metal support interaction
OH
OH
OH R C
O
OH
O
OH
OH
C R
O
O
OH
O
C R
O
O
O
O
C R
O
C
O
R
C
O
R
+ n H2OC
O
R
, ,
+
MG DG TGGlycerol Oleic acid
2. Esterification of oleic acid with glycerol
Mono-glyceride is a good surfactant and has a wide range of applications as emulsifier
in food, pharmaceutical, and cosmetic industries.
Reaction can take place even in the absence of catalyst but zeolite alone does not show
any catalytic activity. ZnO supported on zeolite shows a significant rise in the reaction rate
Product can be formed through parallel or series reaction pathway
10 / 18
Esterification of glycerol with oleic acid
0 50 100 150 200 250 300 350 4000
10
20
30
40
50
60
70
80
90
100
without catalyst
with zeolite
2.0 wt % ZnO
2 wt % ZnO Zeolite
Amberlyst 35
Time (min)
Conv
ersio
n %
15 25 35 45 55 65 75 85 95
0
10
20
30
40
50
60
70
80
90
100
without catalyst (MG) with zeolite (MG) ZnO (MG)ZnO/Zeolite (MG) Without catalyst (DG) with Zeolite (DG)ZnO (DG) ZnO/Zeolite (DG) without cat (TG)with zeolite (TG) ZnO (TG) ZnO/Zeolite (TG)amberlyst 35 (MG) amberlyst 35 (DG) Amberlyst 35 (TG)
conversion %OA
Sele
ctivi
ty %
(Gly:OA mole ratio 4:1; Reaction temperature 150 °C; zeolite, Amberlyst 35 and ZnO loading 2.0 wt % each)
Esterification of oleic acid exhibited selectivity
as high as 70-80 % for mono-glyceride in the
conversion range 60-90 %.
The results indicate that the zeolite supported
catalyst is equally active as ZnO powder.
Both mono-and di-glyceride concentrations
increase with time
[5] Singh et al. (2013)11 / 18
HO OH
OH
Glycerol
H2N
O
NH2
HO O
OH
O
NH2
Glycerol carbonate
Catalyst
-NH3
Catalyst-NH3
+
Urea
O O
O
OH
H3C
O O
CH3
O
HO OH
OHH3C
O O
O
HO
OH O O
O
OH
Catalyst-CH3OH
Catalyst
-CH3OH
Glycerol carbonateGlycerolDimethyl carbonate
+
3. Synthesis of glycerol carbonate (GC)
Glycerol carbonate has wide usage in adhesive, surfactant, and elastomer production
The conventional method for GC synthesis is by direct carbonation of glycerol with
phosgene or carbon monoxide and oxygen
Green way: with Glycerol and Di-methyl Carbonate (DMC) or with Glycerol and Urea
12 / 18
Synthesis of glycerol carbonate
0 1 2 3 4 5 60
10
20
30
40
50
60
70
80
With out catalyst
ZnO
MgO
Time (hr)
Glyc
erol
conv
ersio
n %
(Reaction condition: Temp 140oC, cat. loading 0.5 wt %, Urea: glycerol mol ratio 1.4:1)
0 0.5 1 1.5 2 2.5 3 3.5 4 4.50
10
20
30
40
50
60
70
80
90
100
150 C
160 C
170 C
180 C
Time (hr)
Conv
ersio
n %
Gly
cero
l
(DMC : glycerol molar ratio 4:1, catalyst (MgO) loading 0.5 wt % )
With Urea and Glycerol
With DMC and Glycerol
Without catalyst, glycerol conversion was
39 % after 6 hr.
Catalytic performance of MgO is better
than ZnO
No by-product formed in the reaction
Another value added product, Glycidol
is formed in the reaction.
There is observed dependency of
selectivity for GC on molar feed ratio of
DMC to glycerol13 / 18
4. Synthesis of DMC from methanol and urea
(1)
(2)
(3)
Di-methyl carbonate (DMC) is an important, environmentally benign building block
and is widely used in industry. (2009, world production capacity was 1.8 x 1014 lit/day)
Conventionally DMC was manufactured from phosgene and methanol.
Synthesis of DMC using urea and methanol is an attractive alternative route
14 / 18
Slow step thus need cat.
Synthesis of DMC
Time (hr) DMC yield MC yield1 0.63 862 0.83 86.274 1.08 876 2.14 87
Amberlyst 36
Glass beads (4 mm)
18 g molecular sieve with (Si/Al 2.5, acidic Zeolite) was
used to absorb the ammonia formed during the reaction.
A maximum 6.7 % yield of DMC was obtained in this case.
(Reaction temp 180 oC, Methanol/Urea 15, (ZnO/ZSM5) catalyst loading 1 wt %)
15 / 18
Conclusion
ZnO/zeolite, PbO/zeolite catalysts have exhibited good performance in biodiesel synthesis
using vegetable oils
Glycerol obtained as a byproduct can be used further in many useful reactions.
Mono-glyceride can be synthesized by esterification of glycerol with fatty acid.
Esterification of oleic acid showed selectivity as high as 70-80 % for mono-glyceride in
the conversion range 60-90 %.
The performance of MgO in the synthesis of glycerol carbonate via urea glycerol and
DMC glycerol route is better than ZnO.
A maximum of 6.7 % yield of DMC was obtained in the reaction of urea and methanol,
which may further increase by continuous and efficient removal of ammonia.
16 / 18
References
[1] Lu, W., Lu, G., Luo, Y. and Chen, A. (2002) A novel preparation method of ZnO/MCM-41 for hydrogenation of
methyl benzoate, Journal of Molecular Catalysis A: Chemical, 188(1), pp. 225–231.
[2] Chen, L., Sun, X., Liu, Y. and Li, Y. (2004) Preparation and characterization of porous MgO and NiO/MgO nano
composites, Applied Catalysis A: General, 265, pp. 123–128.
[3] Mahajani, S. M., Ganesh, A., Singh, D. K. and Gupta, P. D. (2010) Heterogeneous acid catalyst for producing
biodiesel from vegetable oils and process for the preparation thereof, Indian Patent Application No 2134/MUM/2010.
[4] Singh, D., Bhoi, R., Ganesh, A. and Mahajani, S. M. (2013) Synthesis of Biodiesel from vegetable oil Using
supported metal oxide catalyst. Applied catalysis A: General, under review
[5] Singh, D., Patidar, P., Ganesh, A. and Mahajani, S. M. (2013) Esterification of oleic acid with glycerol in the
presence of supported zinc oxide as catalyst, Industrial and Engineering Chemistry Research, 52 (42), pp.14776-14786
17 / 18
Thank you 18 / 18
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