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: MarziehRezayat Supervisor: Prof. H. S. Ghaziaskar Advisor: Prof. M. Yalpani Aug 10, 2010

2. Outline • 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

3. Supercritical Fluid 1822 1898 1913 1990s

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

5. Phase diagram for pure CO2 SOLID SUPERCRITICAL FLUID Critical • point Pressure (bar) 74 LIQUID Triple • point 5.1 GAS 1 -78 ºC -56.3ºC 31.1ºC Temperature (ºC)

6. Chemical Reaction in SC-CO2

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

12. Conventional Methods Glycerol + Monoacetin (MA) Acetic acid Acid Catalyst Diacetin (DA) Organic Solvent Acetic anhydride Triacetin (TA) Colored Odorous Problems Impure

13. Synthesis of Glycerol acetate

14. Continuous Flow Reactor

15. Materials • 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®

16. Synthesis of Monoacetin

17. AnalyticalmethodThe yield, conversion, and selectivity for each sample are calculated as follows:

18. Amberlyst15®

19. Continuous Synthesis of Glycerol Acetates in SC-CO2 Using Amberlyst15® • Pressure • Temperature • Molar ratio (Acetic acid/Glycerol) • Flow rate • Reactor geometry • Time

20. Pressure:

21. Pressure:

22. Temperature:

23. Molar ratio (acetic acid/glycerol):

24. Reactor length : • Catalyst : A without catalyst b with catalyst

25. Catalyst reusability: a acid/glycerol ratio was 6.0. b acid/glycerol ratio was 24.

26. Acetic acid/Glycerol= 30 Acetic acid/Glycerol= 40

27. 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

28. % Selectivity and %Yield vs. CO2flow rate Flow rate= 3.0 mL.min-1

29. Silica Sulfuric acid

30. Continuous Synthesis of Glycerol Acetates in SC-CO2 Using SiO2-SO3H • Catalyst bed: 4 mm (i. d.), 25 cm (length) • T = 110 °C • Flow rateSub.=0.2 mL.min-1

31. % Selectivity and Yield of the Reaction at different CO2 Flow Rates and Molar Ratio of 24 vs.Time Using Silica Sulfuric Acid as Catalyst Flow rate= 1.1 mL.min-1 Molar ratio= 24 Flow rate= 1.5 mL.min-1 Molar ratio= 24

32. % Selectivity and Yield of the Reaction at different CO2 Flow Rates and Molar Ratio of 30 vs. Time Using Silica Sulfuric Acid as Catalyst Flow rate= 1.1 mL.min-1 Molar ratio= 30 Flow rate= 2.0 mL.min-1 Molar ratio= 30

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

34. Zeolite HZSM-5 (x)

35. Continuous Synthesis of Glycerol Acetates in SCCO2Using 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

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

37. Ionic liquid Methyl Imidazolium Hydrogen Sulfate

38. 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. Methyl Imidazolium Hydrogen Sulfate (20%)

40. Methyl Imidazolium Hydrogen Sulfate (30%)

41. Methyl Imidazolium Hydrogen Sulfate (20%)

42. Conclusion: • 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%) Without Catalyst H-ZSM-5(x) [x= 30 , 170] IL , Methyl imidazolium [HSO4]

43. Separation of Glycerol acetate Selective extraction of TA from a mixture of TA, DA, and MA with the composition of 1:2:1 molar

44. Semi-continuous SFE The standard mixture of TA, DA and MA ( 1:2:1) Extraction yield (Y): %Y = (wext/w0) × 100 Selectivity (S): S = (YA/YB)

45. Central Composite Design (CCD) • Range of selected levels for four variables in the semi-continuous SFE process a Liquid CO2 flow rate at 60 bar and 0°C.

46. P = 140 bar T = 48 °C f = 1.1 mL·min-1 t = 60 min The maximum extraction yield TA = 95.6% DA = 96.9%

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

48. Response Optimizer Tools P = 109 bar T = 56 °C f = 0.86 mL·min-1 t = 61 min TA =62% DA=17%

49. (a) (b) Response Surface Plots of DA and TA % Extraction Yield f = 0.86 mL.min-1 t = 61.0 min T = 56.0 °C t = 61.0 min

50. Practicable Region of The DA and TA % Extraction Yield DA f = 0.86 mL.min-1 t = 61.0 min TA