1. Ch 9 Gas Separation by Membranes Membrane Flow sheet of a membrane separation Separation of solvent and solute in SFE-processes Retentate Feed Permeate Problems: High pressure ( > 100 bar) Solution of Carbon Dioxide in Polymers Influence on glass transition point

2. Gas Circuit

3. CO 2 OC Permeate Retentate Membrane Process

4. GKSS-membrane (organic, active dense layer) 1.86 wt.-% < 0.06 wt.-%  p = 2.0 MPa active dense layer 1.5 mole CO 2 kg/(m 2 h) P = 18 MPa, T = 323 K Separation by membranes

5. ReferenceMembraneSystemT, P Wagner (1986) RO, (Polyamid) Kaffein 473 K, 30 MPa Semenova et al. (1992, ´93, ´94) Kapton ® (Polyimide) Ethanol, Petroleum compounds 423 K, 15 MPa Sarrade et al. (1996, ´97) Composite with Nafion ® PEG, Triglycerides 333 K, 31 MPa Nakamura et al. (1994) Ceramic, NTGS-2100 (Silikon) PEG 400-600 313 K, 20 MPa Literature overview

6. Flat sheet membranes  ROMACO, high pressure RO, (Polyamide, Pall Rochem)  PAN-Fluorinated Polymer (FP), GP, (GKSS)  PEI-FP, GP, (GKSS)  PVDF-FP, GP, (GKSS)  6-FDA-4MPD/DABA 4:1 (Polyimide, crosslinked with ethylene glycol, University of Heidelberg)  Al 2 O 3 -TiO 2, (Inocermic) Membranes

7. 6FDA-4MPD/DABA 4:1 Membranes

8. Tubular membranes  Carbone membrane, (  20 nm, Le Carbone-Lorraine)  ZrO 2 - TiO 2, (Schuchmacher)  Al 2 O3-TiO 2 -FP, (US-Filter, GKSS) Membranes

9. Mechanisms of membrane transport Membranes

10. Inorganic Membranes Membranes Pore diameter and thickness of inorganic gas separation membranes, after van Veen et al. (1996).

11. Membranes Classification of ceramic membranes (Bonekamp, 1996).

12. Polymeric, Nonporous Membranes States of polymers Membranes

13. Specific volume and free volume as a function of temperature for an amorphous polymer: A: specific volume of a liquid; B: specific volume of a glassy polymer; C: specific volume of a crystal solid; W: van der Waals volume; T g : glass transition temperature; T m : melting temperature. Effect of Temperature on the Polymeric Structure

14. Effect of Pressure on the Polymeric Structure Swelling and Plasticization of Polymers Aging of Polymers Membranes Influences on Membrane Properties

15. Gas Permeation through Membranes Steady state flux J : P e : effective permeability coefficient, (integral value over the whole membrane). with Fugacity coefficient  : z: compressibility factor.

16. The permeability coefficient for ideal–gas conditions Pressure - normalized flux Q, "membrane permeability": Separation factor  for a binary mixture of component A and B: Gas Permeation through Membranes

17. Gaspermeation: P = D H: Permeationskoeffizient, D = Diffusionskoeffizient, H = Henry-Koeffizient. Trennfaktor: Stofftransport Einheit von P:

18. Joule-Thomson effect Definition of the Joule-Thomson coefficient: Joule-Thomson coefficient of carbon dioxide Gas Permeation through Membranes

19. A: Hagen-Poiseuille's flow, B: Knudsen flow, C: surface flow, D: multilayer adsorption, E: capillary condensation, F: molecular sieving. Gas Permeation through Porous Membranes Transport mechanisms through porous membranes

20. Hagen-Poiseuille Flow The term p/RT has to be replaced by the mean density r m resulting in the following relation for Hagen-Poiseuille's flow of carbon dioxide through mesoporous membranes: Gas Permeation through Porous Membranes

21. Surface Diffusion and Capillary Condensation Surface diffusion is a poorly understood phenomenon The total molar surface flux is calculated by: with pore length l, porosity e, and density r of the solid. The surface diffusion coefficient D s is a function of the amount of gas q adsorbed on the surface. The effective surface coverage q e of gas can be described by adsorption isotherms, for monolayer adsorption: Langnuir isotherm: For multilayer adsorption BET isotherm: Gas Permeation through Porous Membranes

22. Permeability of carbon dioxide through vycor glass, after Rhim and Hwang, (1975). Maximum permeability: point where capillary condensation takes place. Gas Permeation through Porous Membranes

23. The capillary condensation pressure (p t ) can be predicted by the Kelvin equation: where t represents the thickness of the adsorbed layer. For non-cylindrical capillaries the term 2 cosq (r-t)/r 2 has to be replaced by another relation. Gas Permeation through Porous Membranes

24. Adsorption Isotherms at Sub- and Supercritical Conditions Isotherms of the total amount of adsorbed carbon dioxide on two different silica gels. Silica gel with 10 nm mean pore diameter, - - 308.15 K, - - 318,15 K, data replotted from Bamberger (1996) silica gel with 1 nm mean pore diameter, -  - 313,15 K, -  - 333,15 K, data replotted from Ozawa and Ogino (1972). Gas Permeation through Porous Membranes

25. The flux J i of component i is given by Fick’s law: Temperature dependence of the permeability coefficient P = D S: Temperature dependence of diffusivity and solubility: Gas Permeation Through Nonporous Membranes

26. Sorption of gases in all types of amorphous polymers shows that the solubility of CO 2 increases with decreasing temperature (van Krevelen, 1990): Transport mechanism of penetrants through polymers differs below and above the glass transition of polymers. The diffusion of penetrants through glassy polymers is a highly non-linear function depending on the state of the polymer. Gas Permeation Through Nonporous Membranes

27. Concentration polarization at steady state conditions; left: normal concentration polarization; right: gel-layer formation Concentration Polarization

28. Solubility of fatty acid ethyl esters in carbon dioxide (Riha, 1996). Concentration Polarization A liquid layer forms on the retentate surface of the membrane when the solubility ís reached 1 phase 2 phases Change in concentration when CO 2 is removed by a membrane process

29. Membrane Test Cell Membrane

30. Flat Sheet Test Cell

31. Experimental Set Up For Testing Flat Sheet Membranes

32. Tubular membrane test cell. Experimenatal Membrane Test

33. Experimental Set-Up

34. Pure Gas Permeation TEOS, pressure-normalized CO 2 flux vs. upstream pressure –  – 34 °C, – – 49 °C,–  – 66 °C –  – 0.1 MPa 25 °C manufacturer,  p = 0.3–1.9 MPa, 20-mm TC, membrane #2, values taken after 30 minutes.

35. Membranes Inorganic Membranes: Titania-Alumina Composite Membranes Schematic representation of titania-alumina membrane cross-sections TEOS Substructure: commercially available  -Al 2 O 3 membrane of 18 mm in diameter, mean pore diameter of 5 nm, porosity 50%, surface roughness appr.  0.2  m. Substructure modified by tetraethylorthosilicate (TEOS) treatment.

36. Polymeric Membranes PEI-Teflon Membranes Chemical structure of polyetherimide (PEI), trademark Ultem by GE. An intermediate ultrafiltration layer of polyetherimide (PEI) is applied to a polyester support fleece. The PEI- layer is then coated with a selective layer of poly (tetrafluoroethylene) (PTFE). Repeat unit of poly (2,2-bistrifluoromethyl-4,5-difluoro-1,3-dioxole) [PDD] / PTFE, commercially available under the trademark (AF 2400 Du Pont)

37. 1 Barrer = 10- 10 (cm 3 cm)/(cm Hg s cm 2 ) GasTeflon ® PTFE AF2400 CO 2 280012 O 2 9904.2 H 2 4100# He2700# H 2 22009.8 N 2 3501.4 CH 4 340# C 2 H 4 350# C 2 H 6 180# Structure of Monomers of the AF2400-polymer Gas Permeabilities of PTFE-Polymers

38. TEOS membranes: pressure-normalized CO 2 flux vs. upstream pressure, – – #1 increasing pressures, –  – #1 decreasing pressures, –  – #2 increasing pressures,  p = 0.3–1 MPa; T = 50 °C, 20-mm TC. Pure Gas Permeation

39. PEI-TE10x pressure-normalized CO 2 flux as a function of upstream and permeate pressure for increasing upstream pressures (solid symbols), and decreasing upstream pressure (open symbols): – – 1 MPa transmembrane pressure difference,–  – downstream pressure at atmospheric pressure, T = 50 °C, 47-mm TC. Pure Gas Permeation: Organic Membranes

40. CO 2 flux at different upstream pressures as a function of transmembrane pressure difference for PEI-TE1x, – – 7 MPa, –  – 9 MPa, –  – 12 MPa, –  – 14 MPa, –  – 15.9 MPa, –  – 18.1 MPa, T = 50 °C, 47-mm TC. Pure Gas Permeation: Organic Membranes

41. Influence of Repeated Use PAN-AF2400- Membran, 50 °C

42. CO 2 -Permeate Flow of PEI-AF2400-1x Related to PEI-AF2400-10x – – increasing retentate Pressure (Feed side), –  – decreasing retentate pressure (Feed side), T = 50 °C, 47-mm test cell.

43. Solubility of CO 2 in Teflon AF 2400

44. Diffusion Coefficient of CO 2 7-  m Teflon AF 2400 layer on a PEI-AF2400-10x Membran, 50 °C,  p = 1 MPa; 50 °C, p 2 = atmospheric pressure;  35 °C, p 2 = atmospheric pressure (after Merkel et al. (1999).

45. CO 2 Permeate Flow 2-HHU-1 TEOS - membrane Sartorelli 2001

46. TEOS-Membrane: Feed: P = 23 MPa; T = 60° C Sartorelli 2001

47. TEOS-Membrane Separation Factors 2-HHU-1 Sartorelli 2001

48. Permeate flows of CO 2 at 50 °C, 60 °C and 70 °C, Exp. series: 2-FP-X10 (18 MPa/50 °C) and 3-FP-X10 (23 MPa/60 °C). Permeate Flow AF 2400 - Membrane

49. CO 2 Permeate Flow: AF 2400 membrane Sartorelli 2001

50. Separation Factor: AF 2400 membrane Sartorelli 2001

51. Determination of Transport Coefficients Sartorelli 2001 Nanofiltration Membrane, AF 2400 coated

52. 0123456 0 1 2 3 4 5 6 7 MPa 9 MPa 12 MPa 14 MPa 16 MPa 18 MPa J CO 2 [kmol 3 m -2 h ]  p [MPa] Pressure Difference, PEI-FP, 323

53. Membrane Comparison, 323 K

54. T = 323 K  P = 2 MPa Hysteresis in the PEI-FP 2,5 and 10 Membranes

55.  Mixture Results Overview

56. T = 323 K P f = 18 MPa  P = 2 MPa PEI-FP 10 Membrane

57. Scale Up: Plate and Frame Construction

60. 18 MPa 323 K 6 MPa 323 K 273 K Supercritical Fluid Extraction

61. 18 MPa 323 K  P = 2 MPa Coupling With a Membrane Separation Unit

62. 53 kJ/ kg CO2 21 kJ/ kg CO2 7.6 kJ/ kg CO2 Like in 2 Energy For Different Solvent Cycles Pump-Cycle Compressor-Cycle Membrane-Cycle Sartorelli 2001