Process of forming a permeable gas separation material

Details Process of forming a permeable gas separation material Process of forming a permeable gas separation material

2000-08-15

2002-07-16

Spitzer, Robert H. (Department: 1724)

Gas separation: processes

Selective diffusion of gases

Selective diffusion of gases through substantially solid...

C095S048000, C095S051000, C096S013000, C096S014000, C055S524000, C055SDIG005

Reexamination Certificate

active

06419725

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a process of forming a permeable gas separation material.
BACKGROUND OF THE INVENTION
Poly(phenylene oxide) (PPO) is known as a moderately permeable polymer membrane material having alternating aromatic cycles and C-O linkages in the main chain. Among the many aromatic polymers having a high glass transition temperature, PPO shows the highest permeability to gases, higher than polysulfone or bisphenyl-A-polycarbonate which have rather similar structures of repeat units. Whatever the reason for this, PPO has received significant attention as a permselective material.
However, measurements of separation factors for PPO have not been fully consistent, possibly because PPO can crystallise under some conditions and variations in crystallinity can cause variations in permeability.
It has been proposed to increase the permeability of PPO by the introduction of bulky substituents.
Thus, European patent application EP 0 360 318 (Eniricerche SpA) describes a modified poly (2,6-dimethyl-p-oxyphenylene) with a glass transition temperature in the range 180° to 220° C. containing a hydroxy butyl group replacing the methyl group in the 2-position, or a hydroxyethyl group in the 3-position.
United States patent U.S. Pat. No. 5,169,416 (Pedretti et al. / Snam SpA et al.) describes a process of modifying PPO by introducing a trialkylsilyl halide substituent group.
United States patent U.S. Pat. No. 4,586,939 (Li / The Standard Oil Company) describes PPO which is substituted in the 3-and 5-positions with a radical larger than chloride, such as bromide.
Gas separation membranes prepared from PPO of low molecular weight have a tendency to rupture.
An important property of a gas separation membrane is its permselectivity, especially if one or more components of the gas mixture comprise polar molecules. In fact, for such mixtures, permselectivity is more important than permeability.
It is an object of the present invention to provide a permeable gas separation material having good mechanical strength and good permselectivity.
SUMMARY OF THE INVENTION
We have discovered that this object, and other useful benefits, can be achieved by sulphonating a partially brominated PPO.
Thus, according to the invention there is provided a process of forming a permeable gas separation material characterised by sulfonating a partially brominated poly(phenylene oxide).
The partially brominated PPO, which is used as a starting material for the sulfonation process, preferably is from 20% to 60% brominated PPO.
The partially brominated PPO is preferably partially brominated poly (2,6dimethyl-1,4-phenylene oxide), although the invention is equally applicable to partially brominated poly (phenylene oxide)s after other structures, for example where the substituents at the 2- and 6- positions are selected independently from C
1
to C
8
aliphatic, C
5
to C
7
cycloaliphatic, C
1
to C
8
alkoxy; C
6
to C
12
aromatic radicals or inert substituted derivatives thereof.
The process may comprise reacting the partially brominated PPO with a sulfonating agent in a non-polar solvent, for example using a procedure similar to the known procedure for sulfonating low MW PPO. The sulfonating agent is typically chlorosulfonic acid. The non-polar solvent may be chloroform. The concentration of the PPO in the non-polar solvent is preferably less than 10% by weight. Sufficient sulfonating agent may be used to nominally sulfonate un-reacted repeat units in the partially brominated PPO.
The gas separation material formed by the process according to the invention may be made into a membrane. A membrane may be formed by coating a flat surface or the lumen or the shell side of hollow fibres with dilute solutions of the modified polymer in a suitable solvent and allowing the solvent to evaporate.
The invention also provides a method of separating component gases from a gas mixture, comprising contacting the gas mixture with a gas separation material formed by sulfonating a partially brominated PPO.
The preferred gas separation material as formed by sulfonating a partially brominated PPO, has a CO
2
/CH
4
permeability ratio of at least 51.0 for pure gases and/or a CO
2
/CH
4
separation factor of at least 22, measured with a CO
2
/ CH
4
mixture containing 19.3% CO
2
.


REFERENCES:
patent: 3528858 (1970-09-01), Hodgdon, Jr. et al.
patent: 3735559 (1973-05-01), Salemme
patent: 3780496 (1973-12-01), Ward, II et al.
patent: 4530703 (1985-07-01), Malon et al.
patent: 4586939 (1986-05-01), Li
patent: 4652283 (1987-03-01), Zampini et al.
patent: 4840646 (1989-06-01), Anand et al.
patent: 4971695 (1990-11-01), Kawakami et al.
patent: 5000763 (1991-03-01), Sanders, Jr. et al.
patent: 5348569 (1994-09-01), Bikson et al.
patent: 5364454 (1994-11-01), Bikson et al.
patent: 0301597 (1989-02-01), None
patent: 0409265 (1991-01-01), None
patent: 1039443 (1966-08-01), None
patent: 1267167 (1972-03-01), None
R.T. Chern, “A note on the effects of mono- and di-bromination on the effects of properties of poxide)”, J. Membr. Sci. vol. 48, No. 23, pp. 333-341, Feb. 1990.*
H. Fu, “Studies on the Sulfonation of Poly(phenylene Oxide) (PPO) & Permeation Behaviour of Gases and Water-Vapour Through Sulfonated PPO Membranes II”, J. Applied Polymer Sci., vol. 51, No. 8, pp. 1405-1409, Feb. 22, 1994.*
Chemical Abstracts, vol. 114, No. 24, Abstacts No. 229415, Jun. 17, 1991.*
Chemical Abstracts, vol. 105, No. 20, Abstract No. 173182, Nov. 17, 1986.

Affiliated with

Also associated with

Rating

Process of forming a permeable gas separation material does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process of forming a permeable gas separation material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process of forming a permeable gas separation material will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2873100