Isfahan University of Technology Department of Chemistry

1

Isfahan University of TechnologyDepartment of Chemistry

Continuous Synthesis and Separation of Glycerol Acetates Using Supercritical Carbon Dioxide as a

Benign Solvent

By: Marzieh Rezayat

Supervisor: Prof. H. S. Ghaziaskar Advisor: Prof. M. Yalpani

Aug 10, 2010

2

Introduction• Supercritical Fluids • SCCO2 Properties

• Chemical Reaction in SC-CO2

• Extraction & Separation by SC-CO2

• Glycerol acetates Experimental

• Synthesis of acetins• Separation using SCCO2

Conclusion

Outline

3

Supercritical Fluid18

2218

9819

1319

90s

4

Historical Development of Patents Issued in Different Fields of Supercritical Fluid Technology

5

•

SOLID

GAS

LIQUID

SUPERCRITICALFLUID

Triplepoint

Criticalpoint•

Pre

ssur

e (b

ar)

Temperature (ºC)

74

31.1ºC-56.3ºC

5.1

-78 ºC

1

Phase diagram for pure CO2

6

Chemical Reaction in SC-CO2

Low Density

and Viscosit

y

Heat transfer

7

8

Extraction & Separation by SC-CO2

Effect of extraction parameters:

• Pressure and Temperature

• Difference in density between the liquid and SC-CO2

• Time

• Feed/Solvent

9

Countercurrent Supercritical Fluid Extraction

10

Supercritical Fluid Fractionation

11

Synthesis of Glycerol acetate

R2OCOHC

CH2OCOR1

CH2OCOR3

+ 3CH3OH HOHC

CH2OH

CH2OH

+

CH3OCOR1

CH3OCOR2

CH3OCOR3

Triglyceride Methanol Glycerol Methyl esters(biodiesel)

12

Conventional Methods

Glycerol +Acetic acid

Acetic anhydride Organic Solvent

Acid Catalyst

Monoacetin(MA)

Diacetin(DA)

Triacetin(TA)

Problems

ColoredOdorous

Impure

13

Synthesis of Glycerol acetate

HO OH

OH

+

HO OCOCH3

OH

CH3COOH

HO OH

OCOCH3

HO OCOCH3

OCOCH3

H3COCO OCOCH3

OHH3COCO OCOCH3

OCOCH3

+ ++ H2O

Glycerol Acetic acid

Monoacetylglycerol(MA)

Diacetylglycerol(DA)

Triacetylglycerol(TA)

14

Continuous Flow Reactor

15

CO2 (99.95%) Glycerol (>98%) Acetic acid (99-100%) Absolute Ethanol (>99.0%) 1-hexanol (Riedel-deHaën) Triacetin (99.0%) Diacetin (50%) Monoaectin (synthesized) Amberlyst15®

Materials

16

Synthesis of Monoacetin

HO OH

OH

PTSA

Acetone - CHCl3O

OOHH3C

H3C

1 2(AcO)2O

O

O O CH3

O

H3C

H3C

3

AcOH 70%

HO

HO O CH3

O

Monoacetin

17

Analytical methodThe yield, conversion, and selectivity for each sample are calculated as follows:

Yield =Total moles of detected esters

× 100Moles of glycerol in feed solution

Conversion = Total moles of detected esters × 100Moles of detected esters and glycerol in exit flow

Selectivity =Moles of each ester

× 100Total moles of detected esters in exit flow

18

Amberlyst15®

19

Pressure Temperature Molar ratio (Acetic acid/Glycerol) Flow rate Reactor geometry Time

Continuous Synthesis of Glycerol Acetates in SC-CO2 Using

Amberlyst15®

OH

HO

HOk1

CH3COOH

HO

OH

OCOCH3k2

CH3COOH

H3COCO

OH

OCOCH3k3

CH3COOH

H3COCO

H3COCO

H3COCO

Glycerol

MonoacetinDiacetin Triacetin

HO

OCOCH3

OHH3COCO

OCOCH3

OH

20

Pressure:

0 50 100 150 2000

20

40

60

80

100

300 bar

250 bar

200 bar

Time / min

Tri

acet

in S

elec

tivity

/%

0 50 100 150 2000

20

40

60

80

100

65 bar80 bar150 bar

Time / min

Dia

cetin

Sel

ectiv

ity/%

0 50 100 150 2000

20

40

60

80

100

65 bar80 bar150 bar200 bar250 bar300 bar

Time/min

Mon

oace

tin S

elec

tivity

/%

21

Pressure:

65 80 150 200 250 3000

20

40

60

80

100

Conversion / %

Yield / %

MA Selectivity

DA Selectivity

TA Selectivity

Pressure /bar

Sele

ctiv

ity, C

onve

rsio

n or

Yie

ld /

%

22

Temperature:

100 120 140 1500

20

40

60

80

100Conversion / %Yield / %MADATA

Temperature /°C

Sele

ctiv

ity, C

onve

rsio

n or

Yie

ld /

%

23

Molar ratio (acetic acid/glycerol):

1.5 4.5 6 12 18 240

20

40

60

80

100Conversion / %

Yield / %

TA

DA

MA

Substrates molar ratio (acid/glycerol)

Sele

ctiv

ity, Y

ield

or

Con

vers

tion

/ %

24

Condition Conversion (%) Yield (%) TA (%) DA (%) MA (%)1a 35 29 0 0 1002b 100 41 100 0 0

Reactor length :

A without catalystb with catalyst

Reactor Length (cm) Conversion (%) Yield (%) TA (%) DA (%) MA (%)25 100 41 100 0 0100 100 48 82 19 0

Catalyst :

25

Times catalyst recycled Conversion (%) Yield (%) TA (%) DA (%) MA (%)3a 100 82 27 42 313b 100 49 92 8 0

Catalyst reusability:

a acid/glycerol ratio was 6.0. b acid/glycerol ratio was 24.

0.0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 22.5 25.00

20

40

60

80

100 Yield / % TA DA

Time/h

Sele

ctiv

ity o

r Y

ield

/ %

26

0.0 2.0 4.0 6.0 8.0 10.00

20

40

60

80

100

Yield% Polynomial (Yield%) TA% DA%

Time/h

Sele

ctiv

ity o

r Y

ield

/ %

0.0 2.0 4.0 6.0 8.0 10.0 12.00

20

40

60

80

100


Time/h

Sele

ctiv

ity o

r Y

ield

/ %

Acetic acid/Glycerol= 30

Acetic acid/Glycerol= 40

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The result of feeding 1st reaction effluent through the fresh catalytic bed This mixture has been synthesized at the ratio of 24, 200 bar, 110

ºC with the final composition of 64.3% TA, 35.7% DA

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.00

20

40

60

80

100

TA% DA%

Time/h

Sele

ctiv

ity /

%

28

% Selectivity and %Yield vs. CO2 flow rate

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.00

20

40

60

80

100


Time / h

Sele

ctiv

ity o

r Y

ield

/ %

Flow rate= 3.0 mL.min-1

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Silica Sulfuric acid

30

Catalyst bed: 4 mm (i. d.), 25 cm (length) T = 110 °C Flow rateSub.=0.2 mL.min-1

Continuous Synthesis of Glycerol Acetates in SC-CO2 Using SiO2-

SO3H

31


Molar ratio= 24

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.50

20

40

60

80

100

Yield% TA DA

Time / h

Sele

ctiv

ity o

r Y

ield

/ %

% Selectivity and Yield of the Reaction at different CO2 Flow Rates and Molar Ratio of 24 vs.Time Using Silica Sulfuric Acid as Catalyst

0.0 1.0 2.0 3.0 4.00

20

40

60

80

100

Yield % TA DA

Time / h

Sele

ctiv

ity o

r Y

ield

/ %


Molar ratio= 24

32


Molar ratio= 30

0.0 1.0 2.0 3.0 4.0 5.00

20

40

60

80

100

Yield% TA% DA%

Time / hSe

lect

ivity

ot Y

ield

/ %

% Selectivity and Yield of the Reaction at different CO2 Flow Rates and Molar Ratio of 30 vs. Time Using Silica Sulfuric Acid as Catalyst


Molar ratio= 30

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.00

20

40

60

80

100

TA DA Yield

Time / h

Sele

ctiv

ity o

r Y

ield

/ %

33

% Selectivity and Yield of the Reaction at different CO2 Flow Rates and Molar Ratio of 30 vs. Time Using Silica

Sulfuric Acid as Catalyst at Pressure of 250 bar

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.00

20

40

60

80

100

Yield TA DA

Time / h

Sele

ctiv

ity o

r Y

ield

/ %

34

Zeolite HZSM-5 (x)

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Continuous Synthesis of Glycerol Acetates in SCCO2 Using H-ZSM-

5(x) T = 110 °C P = 200 bar Molar ratio = 24 1 g catalyst was dispersed within crushed glass (~12 g) Catalyst bed = 9 mm i. d., 15 cm long

Catalyst Conversion (%) Yield (%) TA (%) DA (%) MA (%)H-ZSM-5(30) 75 31 0 2 97H-ZSM-5(170) 92 51 0 8 92

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Catalyst Conversion (%) Yield (%) TA (%) DA (%) MA (%)H-ZSM-5(80) 57 43 0 0 100H-ZSM-5(120) 100 43 0 0 100

0 50 100 150 200 2500

20

40

60

80

100

MA Conversion% Yield%

Time / min

Sele

ctiv

ity o

r Y

ield

or

Con

vers

ion

/ %

Catalyst bed: 4 mm (i. d.), 25 cm (length)

37

Ionic liquid Methyl Imidazolium Hydrogen Sulfate

NN

HH3C

HSO4

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Continuous Synthesis of Glycerol Acetates in SC-CO2 Using Methyl Imidazolium HSO4

⊝

T = 110 °C P = 200 bar Molar ratio = 24 and 30 Catalyst dispersed on SiO2

Catalyst bed = 4 mm i. d., 25 cm long

39

0 50 100 150 2000

20

40

60

80

100

DA Yield% MA

Time / min

Sele

ctiv

ity o

r Y

ield

/ %

Methyl Imidazolium Hydrogen Sulfate (20%)

40

0 50 100 150 2000

20

40

60

80

100

DA Yield

Time / min

Sele

ctiv

ity o

r Y

ield

/ %


41

0 50 100 150 2000

20

40

60

80

100

DA Yield

Time / min

Sele

ctiv

ity o

r Y

ield

/ %


42

Pressure The molar ratio of acetic acid to glycerol CO2 flow rate Substrates flow rate TA synthesized selectively (100%) MA synthesized selectively(100%) MA synthesized selectively (<100%) DA Synthesized selectively (100%)

• Gly.• AcOH

-H2O

Conclusion:

Without Catalyst

H-ZSM-5(x) [x= 30 , 170]

IL , Methyl imidazolium [HSO4]

43

Selective extraction of TA from a mixture of TA, DA, and MA with the composition of 1:2:1 molar

Separation of Glycerol acetate

44

Semi-continuous SFE

%Y = (wext/w0) × 100Extraction yield (Y):

Selectivity (S): S = (YA/YB)

The standard mixture of TA, DA and MA ( 1:2:1)

45

Central Composite Design (CCD)

exxbxbxbbY ji

ji

i jij

k

iiii

k

iii

1

2

10

Variables Low level (-1) Medium level (0) High level (+1)

P (bar) 100 120 140

T (oC) 48 60 72

f (mL·min-1)a 0.5 0.8 1.1

t (min) 30 45 70a Liquid CO2 flow rate at 60 bar and 0°C.

Range of selected levels for four variables in the semi-continuous SFE process

46

0 20 40 60 80 1000

20

40

60

80

100

R² = 0.965317385558961

Experimental values / %

Pred

icte

d va

lues

/ %

0 20 40 60 80 1000

20

40

60

80

100

f(x) = 1.04018292672914 x − 4.32649469029693R² = 0.93638795721442

Experimental values /%

Pred

icte

d va

lues

/ %

P = 140 barT = 48 °Cf = 1.1 mL·min-1

t = 60 min

TA = 95.6%DA = 96.9%

The maximum extraction yield

47

Term%DA %TA

Coefficient t-value p-value Coefficient t-value p-value

Constant 128.401 1.269 0.224 -157.482 -1.388 0.185

P (bar) -1.180 -1.046 0.312 1.885 1.490 0.157

T (°C) -1.448 -0.969 0.348 0.520 -0.310 0.761

f (mL·min-1) -45.396 -0.855 0.406 48.278 0.811 0.430

t (min) -0.848 -0.788 0.443 2.300 1.905 0.076

P2 (bar)2 0.012 2.754 0.015 -0.013 -2.689 0.017

T2 (°C)2 0.048 5.328 0.000 -0.016 -1.557 0.140

f2 (mL·min-1)2 2.579 0.179 0.860 -26.138 -1.619 0.126

t (min)2 -0.001 -0.239 0.814 -0.010 -1.551 0.142

P (bar)*T (°C) -0.037 -5.147 0.000 0.020 2.569 0.021

P (bar)*f (mL·min-1) 1.057 3.714 0.002 0.780 2.443 0.027

P (bar)*t (min) 0.015 2.711 0.016 0.005 0.842 0.413

T (°C)*f (mL·min-1) -1.043 -2.198 0.044 -0.689 -1.295 0.215

T (°C)*t (min) -0.009 -0.978 0.343 -0.018 -1.707 0.108

f (mL·min-1)*t (min) 0.134 0.345 0.728 -0.387 -0.910 0.377

Regression coefficients, t-test, and significance p-values for the model estimated by Minitab software.

48

P = 109 barT = 56 °C f = 0.86 mL·min-1

t = 61 min

Response Optimizer Tools

TA =62%DA=17%

49

80

0

50

80 100 120 14080 100100 120120

100

150

0.5160

1.00.5

1.5

P (bar)

f (mL/min)

% DA

-50

50

35 45 55 65 7535

-50

45

0

50

5555

50

100

50

100

10075 80

8580

160140120

10080

160

T (°C)

P (bar)

% T A

800

50

80 100 120 14080 100 120120

100

0.5160

1.00.5

1.5

f (mL/min)

P (bar)

% TA

80

0

50

80 100 120 14080 100100 120120

100

150

0.5160

1.00.5

1.5

P (bar)

f (mL/min)

% DA

(a)

(b)

Response Surface Plots of DA and TA % Extraction Yield

f = 0.86 mL.min-1

t = 61.0 min

T = 56.0 °Ct = 61.0 min

50

40 50 60 70 8080

90

100

110

120

130

140

150

160

T (°C)

P (b

ar)

10

95

(a)

8070605040

160

150

140

130

120

110

100

90

80

T(°C)

P (b

ar)

10

100

(b)

DA

TA

Practicable Region of The DA and TA % Extraction Yield

f = 0.86 mL.min-1 t = 61.0 min

51

Continuous –SCF Fractionation

56 °C

70 °C The standard mixture:TA, DA , MA( 1:2:1)

52

Experimental matrix for a 2×3 general factorial design and experimental data obtained for continuous scCO2 fractionation.

RunP

(bar)

f

(mL/min)

Feed

(g)

Extracted

(g)

Compound extracted(g) Recovery a

Sc

TA DA MA TA DA MA

1 140 0.86 7.137 0.650 0.5740 0.0800 N.D.b 28.69 2.24 0.00 18

2 140 1.5 7.020 0.889 0.8224 0.1072 N.D. 41.79 3.05 0.00 23

3 100 1.5 7.020 0.130 0.0890 0.0305 0.0050 4.52 0.87 0.33 5

4 109 1.5 7.371 0.288 0.2242 0.0508 N.D. 10.85 1.38 0.00 9

5 109 0.86 7.020 0.124 0.1042 0.0233 N.D. 5.29 0.66 0.00 8

6 100 0.86 7.254 0.093 0.0607 0.0220 0.0039 2.98 0.61 0.25 5a Recovery is the weight percent of recovered compound by scCO2 to the original weight % in the feed.b N.D. = No MA was detected at this conditions.c S is the selectivity defined as the weight % of TA to DA in the extract.

53

100

109 140

0.86

1.50

50

60

70

50

60

70Pressure

Flow rate

100

109

140

0.86

1.50

(b)

1.50

0.86

140

109100

22

17

1222

17

12

Pressure

Flow rate1.50

0.86

140

109

100

(a)

The interaction plots for the continuous supercritical fluid fractionation set up:

DA

TA

54

Continuous –SCF Fractionation

45 °C

85 °C TA (8.9 %)DA (4.9 %)AcOH (86 %)

70 °C

55

Raffinate (%) Extracted (%) Variabls

RunMA DA TA AcOH DA TA AcOHF

(mL.min-

1)

T(°C)

P(bar)

0.00 6.50 10.07 85.17 1.80 2.08 73.37 1 45 70 1

0.00 5.94 10.33 82.32 8/76 4.31 87.37 1.5 45 70 2

0.00 5.97 10.43 81.84 2.59 1.97 98.99 1 70 70 3

0.00 7.74 12.99 78.13 0.00 0.00 103.19 1.5 70 70 4

0.00 7.01 13.54 84.58 0.00 1.03 114.79 1 45 100 5

0.00 10.54 17.83 70.45 0.00 1.65 101.28 1.5 45 100 6

0.00 7.45 12.76 83.27 0.00 0.79 127.87 1 70 100 7

2.27 17.33 22.15 53.20 0.00 3.60 97.72 1.5 70 100 8

2.14 13.88 8.76 88.17 0.00 1.47 110.31 1 45 100 9

2.70 15.36 20.04 61.15 0.00 3.71 101.94 1.5 45 120 10

0.00 13.55 22.46 72.47 0.00 1.06 106.85 1 70 120 11

2.04 19.51 21.73 50.31 0.00 4.84 100.06 5/1 70 120 12

0.00 12.14 13.25 69.02 1.06 5.80 94.17 1 45 140 13

0.00 14.73 10.57 67.80 1.61 9.20 94.10 1.5 45 140 14

0.00 14.13 14.87 72.91 0.00 5.95 102.94 1 70 140 15

2.14 17.7 11.88 64.17 1.52 7.64 94.12 1.5 70 140 16

Experimental matrix for a 2×4×2 general factorial design and experimental data obtained for continuous scCO2 fractionation

56

The interaction plots for the continuous supercritical fluid fractionation set up:

Raffinate

Extract

57

?TA

DAMA

Conclusion: Removal of MA from the mixture of TA, DA and MA using a

semi-continuous SFE. Prediction of the best condition toward TA 100% extraction

selectively. A mixture of 31.50 and 19 (w/w %) 62% of TA & 17%

of DA. Continuous fractionation process 41.8% of TA & 3.0%

DA. Continuous fractionation process for selective extraction of AcOH

from the esterification product.

58

Removal of produced water by using proper azeotrope. Catalyst screening towards the synthesis of TA, DA, and MA

selectively. Variation of packing and column size towards selective extraction of

TA. Reduction of pressure and/or temperature for extracting excess

AcOH from the esterification products before entering into packed column.

On-line Continuous synthesis and separation of glycerol acetate Using SCF technology to convert glycerol to the other valuable

products.

Recommendations

59

I WOULD LIKE TO THANK

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Isfahan University of Technology Department of Chemistry