Process for the preparation of anion exchange membrane

Patent metadata

Field	Value
Publication number	US-9527073-B2
Application number	US-201314647067-A
Country	US
Kind code	B2
Filing date	Nov 25, 2013
Priority date	Nov 23, 2012
Publication date	Dec 27, 2016
Grant date	Dec 27, 2016

Abstract

The present invention describes the process of preparation of inter-polymer film of p-methylstyrene-co-divinylbenzene and its conversion into anion exchange membrane through a greener route which dispenses with the use of chloromethyl ether. The membrane with polyethylene binder is shown to have equivalent or even superior performance to anion exchange membrane prepared from styrene-co-divinylbenzene/polyethylene through chloromethyl ether route.

First claim

We claim:

1. A process for the preparation of an inter-polymer anion exchange membrane, said process comprising:
a) preparing an inter-polymer film by adding a mixture of p-methylstyrene, divinylbenzene, benzoyl peroxide and toluene into a melted mixture of binder (PE) under constant stirring at 80−95° C. for a period ranging from 3 to 5 hours followed by increasing the temperature ranging from 130 to 140° C. to distill out the solvent from the polymer mixture to obtain noodles and cutting into small pellets subsequently keeping said pellets in an oven at 75-80° C. for a period of 12 to 16 hours and after curing converting the pellets into the inter-polymer film;
b) benzylic haloginating the inter-polymer film as obtained in step (a) by treating the inter-polymer film with a halogenations agent in a mole ratio from 1:1 to 2.5:1 in respect of p-methyl styrene, benzoyl peroxide and chlorinated solvent under stirring at a temperature from 75 to 80° C. for a period 5 to 10 hours under photo irradiation to obtain a halogenated inter polymer film;
c) providing quaternization of brominated inter-polymer film as obtained in step (a) to obtain the inter-polymer anion exchange membrane.

2. The process as claimed in claim 1 , wherein the binder used in step (a) is selected from a group consisting of polyethylene, chlorinated and fluorinated polymers, polycarbonate, and polyester.

3. The process as claimed in claim 2 , wherein polyethylene binder is selected from a group consisting of HDPE, LDPE, LLDPE and mixtures thereof.

4. The process as claimed in claim 1 , wherein the melted mixture of binder in step (a) is prepared by heating HDPE, LLDPE and xylene at a temperature ranging from 140 to 160° C. to melt PE and homogenise followed by adding toluene into the PE melt and cooling the mixture at a temperature ranging from 80 to 90° C. to obtain the melted mixture of binder.

5. The process as claimed in claim 1 , wherein a thickness of the films were from 0.1 to 0.3 mm and contained from 20 to 55% p-MS and from 40 to 80% binder by weight.

6. The process as claimed in claim 1 , wherein halogenation in step (c) at benzylic position involves:
chlorination or bromination; or
iodination and bromination.

7. The process as claimed in claim 6 , wherein bromination is carried out by N-bromosuccinimide or liquid bromine or 2:1 bromide-bromate.

8. The process as claimed in claim 1 , wherein photoirradiation in step (b) is done by tungsten lamp, solar radiation, CFL lamp, or LED lamp as a light source.

9. The process as claimed in claim 1 , wherein the degree of monobromination of p-MS is from 40 to 90%.

10. The process as claimed in claim 1 , wherein the brominated film having 8-16% bromine by weight is quaternized employing tertiary amines and phosphines.

11. The process as claimed in claim 1 , wherein the degree of quaternization is from 80 to 100%.

12. The process as claimed in claim 1 , wherein the obtained inter-polymer anion exchange membrane is conditioned prior to evaluation of membrane properties and membrane performance.

13. The process as claimed in claim 1 , wherein the obtained inter-polymer anion exchange membrane has a thickness from 0.1 to 0.3 mm, an ion exchange capacity from 0.8 to 2.0 meq·g −1 dry weight, an ionic resistance from 5 to 35 ohm·cm 2 , a water uptake from 5 to 25% by weight, and a transport number from 0.85 to 0.98.

14. A process for the preparation of an inter-polymer anion exchange membrane, said process comprising:
a) preparing an inter-polymer film of p-methylstyrene-co-divinyl benzene ((p-MS-co-DVB)/binder by adding p-methylstyrene as monomer, divinylbenzene as crosslinker, benzoyl peroxide as radical initiator either neat or into a solution of PVC in a solvent under stirring at a temperature ranging from 60 to 70° C. for a period from 3 to 5 hours followed by pouring said solution on a glass plate and casting subsequently drying at temperature from 11-14 hours at 25-35° C. to obtain the inter-polymer film;
b) benzylic haloginating the inter-polymer film as obtained in step (a) by treating the inter-polymer film with a halogenations agent in a mole ratio 1:1 to 2.5:1 in respect of p-methyl styrene, benzoyl peroxide and chlorinated solvent under stirring at temperature from 75 to 80° C. for a period of 5 to 10 hours under photo irradiation to obtain halogenated inter polymer film;
c) providing quaternization of brominated inter-polymer film as obtained in step (b) to obtain the inter-polymer anion exchange membrane.

15. The process as claimed in claim 14 , wherein the films were from 0.1 to 0.3 mm in thickness and contained from 20 to 55% p-MS and from 40 to 80% binder by weight.

16. The process as claimed in claim 14 , wherein halogenation in step (c) at benzylic position involves:
chlorination or bromination; or
iodination and bromination.

17. The process as claimed in claim 16 , wherein bromination is carried out by N-bromosuccinimide or liquid bromine or 2:1 bromide-bromate.

18. The process as claimed in claim 14 , wherein a degree of monobromination of p-MS is from 40 to 90%.

19. The process as claimed in claim 14 , wherein the brominated film having 8-16% bromine by weight is quaternized employing tertiary amines and phosphines.

20. The process as claimed in claim 14 , wherein a degree of quaternization is from 80 to 100%.

21. The process as claimed in claim 14 , wherein the obtained inter-polymer anion exchange membrane is conditioned prior to evaluation of membrane properties and membrane performance.

22. The process as claimed in claim 14 , wherein the obtained inter-polymer anion exchange membrane has a thickness from 0.1 to 0.3 mm, an ion exchange capacity from 0.8 to 2.0 meq·g −1 dry weight, an ionic resistance from 5 to 35 ohm·cm 2 , a water uptake from 5 to 25% by weight, and a transport number from 0.85 to 0/98.

Assignees

• Council Scient Ind Res

Inventors

• Ghosh Pushpito Kumar
• Sharma Saroj
• Dinda Milan
• Sharma Chiragkumar Rameshbhai
• Chatterjee Uma
• Kulshreshtha Vaibhav
• Ghosh Soumyadeb
• Makwana Babulal Surabhai
• Thampy Sreekumaran
• Desale Girish Rajanikant

Classifications

• B01J41/14 Primary

  obtained by reactions only involving unsaturated carbon-to-carbon bonds · CPC title

• C02F2103/08

  Seawater, e.g. for desalination · CPC title

• B01J47/12

  characterised by the use of ion-exchange material in the form of ribbons, filaments, fibres or sheets, e.g. membranes (electrodialysis or electro-osmosis B01D61/42) · CPC title

• C08F212/12

  Monomers containing a branched unsaturated aliphatic radical or a ring substituted by an alkyl radical · CPC title

• C08J2427/06

  Homopolymers or copolymers of vinyl chloride · CPC title