Gas-Separation Membranes

Abstract

A gas-separation membrane obtainable from curing a composition comprising one or more curable monomers at least 30 wt % of which are monomer(s) comprising oxyethylene groups, oxypropylene groups and at least two polymerizable groups.

Claims

1-24. (canceled)

25. A gas-separation membrane obtainable from curing a composition comprising at least 30 wt % one or more curable monomer(s) comprising oxyethylene groups, oxypropylene groups and at least two polymerizable groups relative to the total amount of used curable monomers in the composition wherein the polymerizable groups are each independently selected from (meth)acrylic groups and vinyl groups.

26. A gas-separation membrane according to claim 25 wherein all of the curable monomers present in the composition comprise oxyethylene groups, oxypropylene groups and at least two polymerizable groups.

27. A gas-separation membrane obtainable from curing a composition comprising at least 50 wt % one or more curable monomer(s) comprising oxyethylene groups, oxypropylene groups and at least two polymerizable groups relative to the total amount of used curable monomers in the composition wherein the polymerizable groups are each independently selected from (meth)acrylic groups and vinyl groups.

28. A gas-separation membrane according to claim 25 wherein the monomer comprising oxyethylene groups, oxypropylene groups and at least two polymerizable groups is of Formula (1):
H2C═CH—CO2-L-CO—CH═CH2  Formula (1) wherein L is a divalent organic linking group comprising oxypropylene groups and oxyethylene groups.

29. A gas-separation membrane according to claim 25 wherein the oxyethylene groups and the oxypropylene groups are distributed randomly in the monomer.

30. A gas-separation membrane according to claim 27 wherein the number of oxyethylene groups in the monomer is greater than the number of oxypropylene groups in the monomer.

31. A gas-separation membrane according to claim 25 wherein the number of oxyethylene groups in the monomer is a factor of 4 to 5 times the number of oxypropylene groups in the monomer.

32. A gas-separation membrane according to claim 25 wherein the monomer has a NAMW of 500 to 5,000.

33. A gas-separation membrane according to claim 25 wherein the composition comprises a further monomer, said further monomer comprising at least one polymerizable group and being free from oxypropylene groups.

34. A gas-separation membrane according to claim 33 wherein the further monomer comprises oxyethylene groups.

35. A gas-separation membrane according to claim 27 wherein the polymerizable groups are acrylate groups.

36. A gas-separation membrane according to claim 28 wherein the divalent organic linking group represented by L comprises 4 to 20 of the oxypropylene groups and 10 to 60 of the oxyethylene groups

37. A gas-separation membrane according to claim 28 the oxypropylene groups and the oxyethylene groups are distributed randomly in the divalent organic linking group represented by L.

38. A gas-separation membrane according to claim 25 wherein: (a) the oxypropylene groups are of the formula —CH.sub.2CH(CH.sub.3)O—; and (b) the oxyethylene groups are of the formula —CH.sub.2CH.sub.2O—.

39. A gas-separation membrane according to claim 25 which has a H.sub.2S/CH.sub.4 selectivity (α(H.sub.2S/CH.sub.4)) of at least 30 and a permeability to H.sub.2S of at least 300 Barrer.

40. A gas-separation membrane according to claim 25 which further comprises a porous support.

41. A gas-separation membrane according to claim 27 which has a H.sub.2S/CH.sub.4 selectivity (α(H.sub.2S/CH.sub.4)) of at least 30 and a permeance to H.sub.2S of at least 150 GPU.

42. A process for preparing a gas-separation membrane comprising curing a composition as defined in claim 25.

43. A process for separating a feed gas comprising polar and non-polar gases into a gas stream rich in polar gases and a gas stream depleted in polar gases comprising bringing the feed gas into contact with a membrane according to claim 25.

44. A gas separation module comprising a gas-separation membrane according to claim 25.

Description

EXAMPLES

(a) Preparation of Compositions and Comparative Compositions

[0163] Compositions C1 to C5 and comparative compositions CC1 to CC6 were prepared by mixing the ingredients shown in Table A below at 40° C.:

TABLE-US-00001 TABLE A EO-PO Other Wt % EO-PO monomer Monomer monomer (s) relative to all Initiator Solvent Composition (parts) (parts) curable monomers (parts) (parts) C1 A-1000PER (49) — 100 HMPP (1) EtAc (50) C2 A-1000PER (24.5) PEG600DA (24.5) 50 HMPP (1) EtAc (50) C3 A-1000PER (24.5) ABPE30 (24.5) 50 HMPP (1) EtAc (50) C4 A-3000PER (49) — 100 HMPP (1) EtAc (50) C5 A-3000PER (24.5) PEG600DA (24.5) 50 HMPP (1) EtAc (50) CC1 (Comparative) — PEG600DA (49) 0 HMPP (1) EtAc (50) CC2 (Comparative) — PPG700DA (49) 0 HMPP (1) EtAc (50) CC3 (Comparative) — PPG700DA (9.8) 0 HMPP (1) EtAc (50) PEG600DA (39.2) CC4 (Comparative) — PPG700DA (24.5) 0 HMPP (1) EtAc (50) PEG600DA (24.5) CC5 (Comparative) — ABPE30 (49) 0 HMPP (1) EtAc (50) CC6 (Comparative) A-1000PER (10) PEG600DA (39) 20.4 HMPP (1) EtAc (50) Note: In CC6 the curable monomers comprise < 30 wt % EO-PO monomer

(b) Preparation of Gas-Separation Membranes

[0164] Membranes M1 to M5 and Comparative Membranes CM1 to CM6 were prepared by coating each of the compositions C1 to C6 and CC1 to CC5 respectively onto a non-porous support (Toretec™ from Toray, a polyethylene sheet of thickness 50 μm) using a block coater (Film applicator, 75 μm gap, from supplier BVES). Each resultant layer of composition had a thickness of 75 μm and was dried for 30 minutes at 40° C. and then cured by exposure to UV light using a Light-Hammer™ UV lamp fitted in a bench-top conveyor LC6E (both supplied by Fusion UV Systems) set at 100% UV power (D-bulb) and moving the polyethylene sheets carrying the composition under the UV lamp at a speed of 15 m/minutes. The resultant polymer sheets derived from curing the compositions was removed from the polyethylene plate to give membranes M1 to M5 according to the invention (when using compositions C1 to C5) and comparative membranes CM1 to CM6 (when using comparative compositions CC1 to CC6). The gas-separation membranes in these examples were all free from porous supports. In each case the resultant gas-separation membrane had a dry thickness of 30 μm.

(c) Testing of the Gas-Separation Membranes

[0165] The membranes obtained in step (b) (M1 to M5 according to the invention and comparative membranes CM1 to CM6) were tested using the methods described above to determine their H.sub.2S permeability (P(H.sub.2S)) and their H.sub.2S/CH.sub.4 selectivity (α(H.sub.2S/CH.sub.4)). The results are shown in Table B below. A H.sub.2S permeability (P(H.sub.2S)) above 300 Barrer was deemed to be good. A H.sub.2S/CH.sub.4 selectivity (α(H.sub.2S/CH.sub.4)) from 30 was deemed to be good.

[0166] From Table B it can be seen that the membranes according to the present invention have good H.sub.2S permeability (>300 barrer) and H.sub.2S/CH.sub.4 selectivity (30).

TABLE-US-00002 TABLE B Results Results P α Composition Membrane (H.sub.2S) (Barrer) (H.sub.2S/CH.sub.4) C1 M1 588 31 C2 M2 485 45 C3 M3 510 35 C4 M4 601 30 C5 M5 535 41 CC1 (Comparative) CM1 (Comparative) 160 52 CC2 (Comparative) CM2 (Comparative) 290 15 CC3 (Comparative) CM3 (Comparative) 190 33 CC4 (Comparative) CM4 (Comparative) 240 25 CC5 (Comparative) CM5 (Comparative) 259 19 CC6 (Comparative) CM6 (Comparative) 180 49

Examples 6 to 8 and Comparative Example 7

(a) Preparation of Compositions and Comparative Compositions

[0167] Compositions C6 to C8 and comparative composition CC7 were prepared by mixing the ingredients shown in Table A below at 40° C.:

TABLE-US-00003 TABLE C EO-PO Other Wt % EO-PO monomer Monomer monomer (s) relative to all Initiator Solvent Composition (parts) (parts) curable monomers (parts) (parts) C6 A-1000PER (10) — 100 HMPP (0.1) EtAc (89.9) C7 A-1000PER (50) PEG600DA (5) 90.9 HMPP (0.1) EtAc (89.9) C8 A-1000PER (50) ABPE30 (5) 90.9 HMPP (0.1) EtAc (89.9) CC7 — ABPE30 (10) 0 HMPP (0.1) EtAc (89.9)

(b) Preparation of Gas-Separation Membranes

[0168] Membranes M6 to M8 and Comparative Membrane CM7 were prepared by coating each of the compositions C6 to C8 and CC7 respectively continuously and at 30° C. onto a porous support (GMT-L14) using just one slot of a slide bead coating machine. The resultant, coated porous support passed was cured by passing it under an irradiation source (a Light Hammer LH6 from Fusion UV Systems fitted with a D-bulb working at 100% intensity) and then to a drying zone at 40° C. and 8% relative humidity. The resultant dried, gas-separation membrane then travelled to the collecting station. A section through the resultant composite membranes was examined by a scanning electron microscope (SEM) and the coating layer in each case was found to have a thickness of 2.5 μm.

(c) Testing of the Gas-Separation Membranes

[0169] The membranes obtained in step (b) (M6 to M8 according to the invention and comparative membrane CM7) were tested using the methods described above to determine their H.sub.2S permeance Q(H.sub.2S) and their H.sub.2S/CH.sub.4 selectivity (α(H.sub.2S/CH.sub.4). The results are shown in Table D below. A H.sub.2S permeance (Q(H.sub.2S)) above 150 GPU was deemed to be good. A α(H.sub.2S/CH.sub.4) from 30 was deemed to be good.

[0170] From Table C it can be seen that the membranes according to the present invention have good H.sub.2S permeance (>150 GPU) and H.sub.2S/CH.sub.4 selectivity (≥30).

TABLE-US-00004 TABLE D Results Results Q α Composition Membrane (H.sub.2S) (GPU) (H.sub.2S/CH.sub.4) C6 M6 230 31 C7 M7 184 45 C8 M8 202 35 CC7 (Comparative) CM7 (Comparative) 98 18