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.

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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

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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

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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.

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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

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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

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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

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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

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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 %)

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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.

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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

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Thank you 18 / 18