Spiral wound gas filtration modules and components thereof

1. A membrane envelope stack for gas separation comprising membrane envelopes bonded together by means of an adhesive having a tensile E-modulus of at least 1600 N/mm 2 and an elongation at break of 20% or less and/or a Tg of at least 50° C., wherein:

(i) the membrane envelopes comprise one or more membrane sheets and optionally a feed spacer sandwiched between the membrane sheet(s);

(ii) the membrane sheet(s) are composite membranes comprising a discriminating layer and a porous support; and

(iii) the tensile E-Modulus, tensile strength at break and elongation at break measurements are as measured on samples of cured adhesive using a Zwick Z010 4millimeter type V test strips as per ASTM method D638 at 22° C., relative humidity of 50% and using a crosshead speed of 30 millimeters/minute.

2. The membrane envelope stack according to claim 1 wherein the adhesive has an elongation at break of 20% or less.

3. The membrane envelope stack according to claim 1 wherein the adhesive has a Tg of at least 50° C.

4. The membrane envelope stack according to claim 1 wherein the adhesive has a tensile E-modulus of at least 1600 N/mm 2 , an elongation at break of 20% or less and a Tg of at least 50° C.

5. The membrane envelope stack according to claim 1 wherein the discriminating layer(s) comprise a polyimide having —CF 3 groups.

6. The membrane envelope stack according to claim 1 wherein the discriminating layer(s) comprise groups of the Formula (1) wherein Ar is an aromatic group and R is a carboxylic acid group, a sulphonic acid group, a hydroxyl group, a thiol group, an epoxy group or an oxetane group:

7. The membrane envelope stack according to claim 1 wherein the adhesive is a multi-part adhesive comprising a polymerisable substance and a hardening agent.

8. A spiral wound gas filtration module comprising a membrane envelope stack according to claim 1 .

9. A method for preparing a membrane envelope stack according to claim 1 comprising:

(a) providing a plurality of membrane envelopes;

(b) stacking the plurality of membrane envelopes and bonding the membrane envelopes together by means of a partially cured adhesive, optionally also providing a permeate spacer between each membrane envelope; and

(c) curing the partially cured adhesive to give a cured adhesive;

wherein the cured adhesive has a tensile E-modulus of at least 1600 N/mm 2 and an elongation at break of 20% or less and/or a Tg of at least 50° C.

10. The method for preparing a spiral wound gas filtration module according to claim 8 comprising the steps:

(i) providing a permeate collection tube having perforations;

(ii) providing a membrane envelope stack comprising membrane envelopes bonded together by means of a partially cured adhesive;

(iii) winding the membrane envelope stack comprising the partially cured adhesive about the permeate collection tube; and

(iv) curing the partially cured adhesive to give a cured adhesive;

wherein the cured adhesive has a tensile E-modulus of at least 1600 N/mm 2 and an elongation at break of 20% or less and/or a Tg of at least 50° C.

11. A process for separation of a feed gas containing a target gas into a gas stream rich in the target gas and a gas stream depleted in the target gas comprising passing the feed gas through a module according to claim 8 .

12. The membrane envelope stack according to claim 1 wherein the adhesive is a multi-part adhesive comprising a polymerisable substance and a hardening agent and the discriminating layer(s) comprise a polyimide having —CF 3 groups.

13. The membrane envelope stack according to claim 1 wherein the adhesive is a multi-part adhesive comprising a polymerisable substance and a hardening agent and the discriminating layer(s) comprise groups of the Formula (1) wherein Ar is an aromatic group and R is a carboxylic acid group, a sulphonic acid group, a hydroxyl group, a thiol group, an epoxy group or an oxetane group:

14. A spiral wound gas filtration module comprising a membrane envelope stack according to claim 1 .

15. A spiral wound gas filtration module comprising a membrane envelope stack according to claim 1 wherein the adhesive is a multi-part adhesive comprising a polymerisable substance and a hardening agent and the discriminating layer(s) comprise a polyimide having —CF 3 groups.

16. The method according to claim 9 wherein the cured adhesive has a tensile E-modulus of at least 1600 N/mm 2 , an elongation at break of 20% or less and a Tg of at least 50° C.

17. The method according to claim 9 wherein the adhesive is a multi-part adhesive comprising a polymerisable substance and a hardening agent and the discriminating layer(s) comprise a polyimide having —CF 3 groups.

18. The method according to claim 10 wherein the cured adhesive has a tensile E-modulus of at least 1600 N/mm 2 , an elongation at break of 20% or less and a Tg of at least 50° C.