RU1836128C - Method of separating component from gaseous oxygen mixture with nitrogen or carbon dioxide with methane - Google Patents

Description

pack new membrane polymers that have higher penetration rates without significantly impairing their ability to separate target gas mixtures.

Literature data show that increasing the permeability of gases, such as oxygen, by varying the structure of the polymer decreases the characteristics of the separation process. those. ability to separate oxygen from nitrogen. The data also show that the current state of the art does not provide real opportunities to predict gas permeability rates or gas selectivity, even when done. There are minor changes in the chemical structure of the membrane in the same polymer class, such as polyesters or polycarbonates.

It has been shown that it is possible to modify a rigid aromatic polymer structure such as polysulfones, polycarbonates and polyesters, including some bisphenolphthalate polyesters that are not within the scope of the present invention, to increase gas permeability without significant deterioration in the separation of helium / methane mixtures and carbon dioxide / methane. However, in most cases an increase in gas permeability results in a decrease in the selectivity of the separation process.

In US patent No. 3899309, CL. In 01 O 53/22, 1975, it was shown that the combination of non-linearity of the main chain, highly aromatic structure and the prevention of free rotation around simple bonds of the main chain in the molecules of polyimides, polyamides and polyesters leads to an increased gas permeability. The description is so broad that it does not allow one skilled in the art to determine which particular structure or structures will produce the most desirable gas permeability and selectivity.

In re-issued US patent No. 30361, CL. In 01 D 53/22 1980 (reissued by U.S. Patent Isfc 3899309), widely disclosed separation membranes of aromatic polyimides, polyesters and polyamides are provided. The invention, widely disclosed and claimed in these patents, requires that polymeric aromatic imide, aromatic ester or aromatic amide repeating units meet certain requirements, namely to contain at least one hard

0

a divalent subunit connecting the two main chains; must be sterically incapable of 360 rotation around one or more of the simple bonds of the specified main chain; more than 50% of the atoms in the main chain must be members of aromatic rings.

If the polymer does not meet all the requirements, it cannot be considered to be within the scope of the invention. US Patent Requirement IV Re No. 303351 restricts membranes to those polymers in which the polymer chain contains at least one rigid mono-linear band between & rigid subunits around which the polymer chain of the subunit sterically impedes 360 ° rotation. Therefore, the polymer structure is assembled from an identified set that is not sterically obstructed by 360 ° rotation and cannot be considered within the scope of the invention (US Pat. Re No. 30351).

The aim of the invention is to increase the selectivity and rate of evolution of oxygen from its mixture with nitrogen and carbon dioxide from its mixture with methane.

The method of isolating a component from a gas mixture is based on contacting with a membrane consisting mainly of a polyester or copolyester obtained by reacting an aromatic dicarboxylic acid or its derivative and more than 50 mol. %

0

5

0

5

tetrabromobisphenol of the general formula:

40

(ABOUT

5

where R is the divalent radical 2,2,2-trifluoro-1- (trifluoromethyl) ethylidene or cyclododecyl. Moreover, said aromatic dicarboxylic acid or its derivative includes at least 80 mol. % isophthalic acid or its dichlorohydride and / or 4-bromisophthalic acid or its dichlorohydride and / or 4-bromisophthalic acid or its dichlorohydride and not more than 20 mol. % terephthalic acid or its dichloride, or includes not more than 30 mol. % isophthaloyl dichloride and / or 4-bromoisophthalic acid or its dichloride and at least 70 mol% of terephthalic acid or its dichlorohydride and / or 2-bromoterephthalic acid or its dichlorohydride.

Mostly tetrabromobisphenol contains 100 mol.% Bisphenol diols.

; One of the variants of this method j provides that the polyester I or copolyester is obtained by the interaction of aromatic dicarboxylic acid or its derivative and a mixture containing | more than 50 mol. % tetrabromobisphenol and me- | her 50 mol.% bisphenol of the General formula:

I where R is the divalent radical of 2,2,2-trif- I tor-1- (trifluoromethyl) ethylidene or cyclododecyl, R11 is methyl or chloride. 1 Mostly tetrabromobisphenol contains at least 80 mol. % mixture of diols.

 The above polymer membranes have excellent properties in the separation of gaseous mixtures of acid | genus / nitrogen and carbon dioxide / methane. The preparation of polyesters is well known and some methods may | to be used. So, it’s known that they | can be prepared by reacting a dihydroxyl compound with an aromatic dicarboxylic acid or a derivative thereof, such as an acid chloride. A) a method for producing polyesters, which is a gas separator; membranes of the present invention, non | is part of the present invention and any complex polyesterification process 1 may be used. Typical pro | the procedure used to obtain the complex i polyester membranes of the present | the invention is the reaction of a tetrabromobisphenol compound (I) with terephthaloyl yl chloride, isophthaloyl chloride or the like; a mixture. Kramer et al. Phthaloylic Soy- | dinhenes are used in the molar ratio of terephthaloyl compound to I isophthaloyl compound from 80:20 to 1 0: 100, preferably from 20:80 to 0: 100, and | even more preferably 0: 100, for complex | polyesters based on 50 mol% or I more than tetrabromobisphenol (I), for oxygen / nitrogen separation (e.g. air separation). The molar ratio of terephthaloyl to isophthaloyl compound | 100: 0 to 0: 100, preferably 90:10 to 170: 30, and even more preferably 85:15 I to 75:25 for | 50 mol% or more of tetrabromobisphenol j (I) to separate a carbon dioxide / methane mixture. In addition, as is known to those skilled in the art, there may be

a minor amount of another suitable dicarboxylic acid, acid chloride or ester thereof has been used in the polyesterification process; further, a small amount of aromatic dicarboxylic acid may be replaced by aliphatic dicarboxylic acid. Further, mixtures of tetrabromobisphenols of the formula (I) with minor amounts of other bisphenols or other aromatic and / or aromatic diols can be used, with up to about 10 mol 3 of tetrabromobisphenol (1) being replaced by other bisphenols or diols. Preferred polyesters are prepared by condensation polymerization of tetrabromobisphenols (I) with terephthalic acid, isophthalic acid, or mixtures thereof, or salts or esters such as acid chlorides. The polyester gas separation membranes of the present invention contain, as the predominant repeating fragment, a group of common

structural formula:

thirty

C |

where R is hydrogen or bromine, and x is an integer having a value equal to 20-200 or more, preferably 25-175. The polyester preferably has an average molecular weight of the order of 20,000-15,000, more preferably 30,000-125,000.

The gas separation membrane of the invention may be a dense film or any other form known to those skilled in the art. Further, it can be a composite, asymmetric, homogeneous or isotropic membrane.

The membranes can be spiral, flat, tubular or other configuration, as well as in the form of hollow fibers.

Preferred membranes of the present invention are asymmetric or composite membranes with separation layers less than 10,000 A thick, preferably less than 5,000 X thick, more preferably 200 to 2,000 A.

Membranes of the isotropic and asymmetric type usually consist of a single permeable membrane material capable of selectively separating mixtures of oxygen and carbon dioxide / methane.

The polyester membranes based on the tetrabromobisphenols of the present invention, as shown by the experimental data in the examples, have a good combination of both high selectivity and high penetration rate. As can be seen from the data below, the permeability of oxygen is about 4.7-11.8 Barrera in combination with a separation factor or oxygen-nitrogen selectivity of about 5.6-7.0.

It was found that a high percentage of isophthalic acid with respect to terephthalic acid in tetrabromohexafluorobisphenol A polyesters A (1) significantly increases the selectivity of the oxygen-nitrogen mixture compared to polyesters with a high amount of terephthalic acid without obtaining low oxygen permeability (less than 4.5 Barrera }. Preferably, the content of isophthalic acid should be 80 mol% or higher, and more preferably 100 mol% of isophthalic acid ester. In contrast, to separate the mixture and carbon dioxide / methane, a surprisingly optimal combination of separation and permeability is achieved when the content of terephthalic acid ester is about 75 mol% or more and the content of isophthalic acid ester is 25 mol,% or less with the same tetra- Romhexafluorobisphenol. The oxygen / nitrogen separation is significantly less effective when the terephthalic acid ester is high. Therefore, a high isophthalic content is preferred for the separation of the oxygen / nitrogen mixture. isloty whereas for separating a mixture of carbon dioxide / methane is preferably a high content of ester of terephthalic acid.

Copolyesters based on 50 mol% or higher, and preferably 60 mol% or higher, of compounds of formula (I), such as tetrabromhexafluorobisphenol A, and one or more other bisphenols (compound III in table 3) can also provide useful gas separation membranes with less favorable permeability and gas separation properties than the previously mentioned tetrabromobisphenol ethers. However, many of these copolymers provide slightly more favorable solubility characteristics than bromobmsphenol polyesters for preparing composite membranes by coating polysulfone hollow fibers, with some deterioration in selectivity and usually with improved permeability. The solubility of polyesters in certain solvents and solvent systems is an important characteristic because polysulfone full fibers are sensitive to many common solvents used to dissolve many membrane polymers. Therefore, even if the polyester

it has excellent characteristic separation and permeability, but if it cannot be applied as a coating to substrates such as polysulfone or other porous hollow fibrous substrates, its usefulness becomes limited. Chemically resistant porous hollow fibers as substrates for such coatings should be ideal if cost, coatability and other

factors make them useful for use with composite membranes. Of course, asymmetric hollow fiber membranes can be made entirely of these polymers, but the cost will be too high.

The data table. Table 2 below shows that certain polyesters and copolyesters provide an incomparable combination of very good oxygen / nitrogen separation factors and high permeability of gaseous oxygen when compared with previously known literature examples.

 As can be seen from the table, for example, tetrabromohexafluorobisphenol A polyisophthalate from experiment 1 has a high oxygen-nitrogen mixture separation factor of 6.7 and a high oxygen permeability of 5.25 Barrera compared to experiment 7 (the values are, respectively, 1.87 and 6 ,9).

The separation of the carbon dioxide / methane mixture was difficult because the factors that lead to high

carbon dioxide permeability, give low separation factors for the carbon dioxide / methane mixture. Table 3 shows that commercially available cellulose acetate and polysulfone membranes give

good separation factors for this gas vapor, but the permeability of carbon dioxide is low.

The membranes of the present invention show a remarkable combination of very

high permeability and separation factor carbon / methane mixtures. With an optimal membrane structure for the separation of an oxygen / nitrogen mixture, tetrabromhexafluorobisphenol A with a high content of isophthalic ester

acid provides the best combination of separation and permeability. An unexpectedly unusually high permeability of carbon dioxide was shown for an ester with a 25/75 ratio of isophthalic / tephthalic acid with a slight decrease in gas selectivity for a carbon dioxide / methane vapor.

Note that the tetrabromohexafluorobisphenol A ester membrane with a 25/75 ratio of isophthalic / terephthalic acid of the present invention has significantly improved properties compared to other known polymer membranes and the same 100% isophthalic acid based polyester.

Although the data are limited by various combinations of isophthalic / tephthalic acid ratios in the ester, they show that we can vary the permeability and gas selectivity by varying the structure of bisphenol and the isophthalic / terephthalic acid ratio.

The viscosities of the polyesters were determined at 25 ° C. using a polymer solution containing 0.200 g of polymer per 100 ml of chloroform, and calculated by the equation

Rv

A-B

Tctw

where A is the passage time of a sample in a chloroform solution through a viscometer; B is the transit time of chloroform through the viscometer, and C is the mass of the sample of the chloroform solution.

Polyesters are film forming at a reduced viscosity in chloroform of about 0.25 and higher. For processes related to gas permeability, a polyester having a viscosity of about 0.25 and higher provides adequately strong films with a thickness of about 2-5 mils, preferred viscosities of about 0.25-1.6, most preferred about 0.45-1.3. The film thickness can be varied in the range of about 1-10 mils, preferably 2-5 mils.

Polysulfone porous hollow fiber substrates are useful for preparing composite membranes. It is advisable that the walls of the porous polysulfone hollow fibers be sufficiently thick so that no special processing equipment is required and they can be conveniently packed in cartridges.

The outer diameter of the porous hollow sulfonic fibers can be varied in the range of about 1-100 mils or more, preferably 2-80 mils. The wall thickness 5 of the porous hollow polysulfone fiber may be on the order of 0.1-25 mils or more, preferably 0.2-20 mils. Conjugated polysulfone fibers are considered to be practically isotropic, but typically there is some degree of asymmetry. The porosity of the hollow fibers can be modified by the annealing technique, especially thermal annealing. This is conveniently accomplished by passing the dried polysulfone porous hollow fiber through a hot air oven at a temperature of from about 160 ° C to close to the glass transition temperature of the polysulfone (195-200 ° C) for a period of time less than 30 s but not more than 10 s.

The measurement of gas permeability or penetration rate on flat film membranes, the values of which are given in the following examples, was carried out in a working cell on the membrane in the form of a small disk of known thickness at 25 ° C, constant volume and variable pressure. Both sides of the membrane are degassed in vacuo overnight, and then one

0 side of the membrane is exposed to gas at a pressure of 25 psi 1.758 kg / cm2. Leaked gas is collected in a container on the other side of the membrane and then the gas pressure is measured using a sensitive sensor.

5 The pressure increase is recorded on the recorder as a function of time and this data is used to determine the steady-state penetration rate P. The penetration rate P is expressed in units

0 Barrera, which is:

(cm3 (5TR) cm / cm2-s-cm RT g)

Membranes are prepared from May 2-10. % solutions

polymer in methylene chloride with a thickness of 2

to about 10 mil. The solvent is removed.

5 in vacuo at 40 ° C and then at 125 ° C for 5 days before evaluation.

Experiments 1-5 show the preparation of intermediates used to make polyester membranes.

0 Compound structures were exposed to both the proton and C-13 nuclear magnetic resonance spectra and melting points.

Experiment 1, Use the method described by F. S. Holahan et at., Macromd

5 Chem. 103/1 /, 36-46, (1967).

201.76 g of 4., 2.2-trifluoro-1- / trifluoromethyl / ethylidene bisphenol, 300 ml of ethanol and 140 ml are charged into a 2-necked 2-liter flask equipped with a stirrer, dropping funnel, condenser, thermometer and trap with 10% sodium hydroxide. water, To this reaction mixture were added 124.84 ml of bromine with good stirring over 3 hours at 15 ° C. The reaction mixture was stirred overnight, then about 3 g of sodium thiosulfate was added to decompose the excess bromine. 3 L of distilled water was added to precipitate the product. The product is filtered and washed 3 times with water, dried in a vacuum oven at 80 ° C. The yield of 4.4 - 2,2,2-trifluoromethyl / ethyleneide bis 2,6-di-bromophenol (compound 1) is 388 g. The product was recrystallized from chlorobenzene to give a total yield of 87%, mp. 25b, 5-258 ° C. Literary 256-257 ° C.

Experiment. 2. 67.25 g of 4.4- (hexafluoroisopropyl) is charged into a 1-liter three-necked flask equipped with a stirrer, a tube for introducing gaseous chlorine with a fused glass plate, a dry ice-acetone condenser and a lead-out tube leading to a trap with 10% sodium hydroxide - den) diphenyl and 600 ml of dichloromethane, cooled in an ice water bath to about 20 ° C. Gaseous chlorine is bubbled at such a rate as to maintain a saturated solution, the temperature is controlled at 20 ° C. After 8 hours, dichloromethane was removed using a rotary evaporator in vacuo to give 88 g (93% yield) of 4,4,2-trifluoro-1- (trifluoromethyl) ethylidene bis 2,6-dichlorophenol (compound II) . Recrystallization from methanol / water leads to a total yield of 80% of the purified product, mp. 225-227 ° C. (Literary, mp 223-224 °, see experiment 1).

Experiment 3. In a three-necked flask with a capacity of 1000 ml, equipped with a dropping funnel, a thermometer, a temperature-clock controller and a dry ice-acetone condenser, closed with a glass stopper, 457.5 g of 2,6-dimethylphenol, 75 g of methanesulfonic acid are charged and the reaction mixture is heated to 95 ° C. Then, 75 g of 1,1,1,3,3,3-hexafluoro-2-propanone sesquihydrate are added dropwise over 1 hour. The reaction mixture is heated for 2 hours to 148 ° C; within 3 additional hours, the temperature is raised to 160 ° C. The progress of the reaction was determined by taking 10 g of a sample, and the acid was removed with water and sodium bicarbonate, and dimethyl phenol with methylene chloride, dried, and the melting point was determined. After 15 hours at 160 ° C, the melting point is 208-217 ° C. After 22 hours at 1 ° C, the melting point is 221-223 ° C. The reaction mixture is treated by pouring

warm semi-solid product into a 4000 ml beaker and rinse it 5 times with 2000 ml portions of water each, then 400 ml of methylene chloride are added and the sample is washed

still 3 times in portions of 20 ml of water. Complete acid neutralization is obtained by adding several grams of sodium bicarbonate. Separate a layer of methylene chloride with some solid.

0 product and remove the solvent and residual dimethylphenol on a rotary evaporator in vacuo at temperatures up to 165 ° C. Yield 4,, 2,2-trifluoro-1- (trifluoromethyl) ethyl, 6-dimethyl-phenol (compound

5 III) is 117 g. The sample is washed with 500 ml of methylene chloride and 500 ml of toluene, and finally 150 ml of methylene chloride, dried under vacuum in an oven at 80 ° C. Yield 64 g. T. pl. equal to 219-221.5 ° C. According to literature data from U.S. Patent Mg 4358624, mp. 218-219 ° C.

Experiment 4. In a three-necked flask with a capacity of 3000 ml. equipped with a mechanical stirrer, gas distributor, thermometer, temperature control unit, a container with hydrogen chloride and a trap with 10% sodium hydroxide for hydrogen chloride, which leaves the reactor, and an ice bath to maintain the temperature at 20 ° C, added 273.45 g of cyclododecanone, 837.0 g

2,6-dimethylphenol, 27.0 ml n-octyl mercaptan, 315.0 ml methylene chloride. Hydrogen chloride is bubbled through a solution in

5 for 7.5 hours at such a rate as to obtain a saturated solution. The resulting solid products were filtered off after 2 days at room temperature and washed 4 times with 2000 ml of methylene x 0 loride each. Recrystallization from toluene was carried out twice, to obtain 19.7% of the total yield of bisphenol, 1,1-bis- (3,5-dimethyl-4-hydroxyphenol) cyclododecane (compound IV), m.p. 250.5-242.5RS. Literature data from

5 US patent No. 4554309, so pl. 239-240.5 ° C. Experiment 5. Procedures for the preparation of 4-bromophthaloyl and 2-bromisophthaloyl chloride from the corresponding acids,

A 500 ml three-necked round bottom flask equipped with a mechanical stirrer, dropping funnel, condenser, heating bath with silicone oil, nitrogen inlet and outlet leading to the absorbing solution

5 sodium hydroxide, 1000 g (0.408 mol) of monobromiso- or monobromo-rephthalic diacid and 1 ml of pyridine are added. Then, 202 ml (328.5 g, 2.77 mol) of thionyl chloride are added dropwise. After all materials were added, the mixture was refluxed for 24 hours with the removal of hydrochloric acid and sulfur dioxide. For this

time get a yellow solution. After you - -. during the night, the absence of crystals indicates that the acid chlorides are liquid. The excess of SOCI2 was distilled off and the yellowish oily crude 1 product was boiled with a seven-fold excess; p-hexane. The hot solution is filtered to remove unreacted diacids. | Hexane was distilled off. Then the samples are cleaned | distillation under reduced pressure at 13-4 mm RT. Art. at 125-132 ° C. In some experiments, about 70 g

of each of the yellowish 4-bromisoph. thaloyl-j chloride and the reddish 2-bromoterephthaloyl and chloride. Oily appearance I is obtained and used directly in the polymerizations.

i The following examples serve to further illustrate the invention. In the examples of aromatic dicarboxylic acid derivatives used, is - jthophthaloyl chloride, terephthaloyl chloride or mixtures thereof, unless otherwise indicated. i Flat membranes are obtained from 3-7 | wt.% polymer solutions in methylene- | loride. A portion of the solution was poured onto a glass plate and left with an aluminum lid closed overnight under room j conditions. The film is removed from the plate and dried in a vacuum oven at 40 ° C for one day. Then the film is additional-) but dried at 125 ° C in vacuum for 5 | days and measure its thickness. The membrane is tested at 25 ° C and a pressure of 2 atm pure | gas permeability to oxygen and nitrogen,

i Polyesters are prepared according to known polymerization techniques at the phase boundary in a Waring mixer and in a i three-necked round-bottom flask with a mechanical stirrer and cooling in an ice bath i. Mixing speed is not always | regulated, but usually it is about 1000 rpm. The rate of addition of the acid chloride is based on controlling the heat of reaction. J. The molecular weight is the higher, the faster the acid chloride is added to the reaction mixture. Also very useful | faster mixing speed and

use of the Morton flask to obtain higher molecular weights.

Example 1.A. Obtaining polyarylate i from 4, 2,2-trifluoro-1- / trifluoromethyl / ethylidene bis 2,6-dibromophenol (compound 1) and 100% isophthaloyl chloride.

To a Morton three-necked round-bottomed flask with a capacity of 500 ml, equipped with a mechanical stirrer, thermometer, a dropping funnel, a nitrogen inlet and an oxygen ture, load 26.07 g of compound I, 0.4 g of β-het-butylammonium acid sulfate, 10.25 g of a 45.9% aqueous solution of potassium hydroxide, 40 ml of distilled water and 40 ml of methylene chloride. A solution of 8.12 g of isophthaloyl chloride in 80 ml of methylene chloride was charged for 15 minutes with very rapid stirring and cooling in an ice bath. After stirring for about 2 hours, 100 ml of methylene chloride was added and the mixture was acidified by adding 0.5% sulfuric acid. The polymer solution is washed three times with 1000 ml of distilled water. The polymer is coagulated in methanol and dried in a vacuum oven at 80 ° C. overnight. The yield is 27.2 g of polyester. The reduced viscosity is 0.42.

B. A flat gas permeable membrane having a thickness of 2.06 mils is prepared and evaluated for the permeability of oxygen, nitrogen, carbon dioxide, methane and gel.

P oxygen 5, cm3 (STP) - cm / cm2-s-cm RT. Art. (Barrera), The selectivity of oxygen / nitrogen is 6.7,

P of carbon dioxide 19.9 Barrera and the selectivity of the mixture of carbon dioxide / methane at 35 lb / in / 2,462 kg / cm2 / when using pure gazop is equal to 50.

P gels of 0.57 Barrers and the selectivity of the helium / methane mixture is 133.

P of nitrogen is 0.787 Barrera and the selectivity of the nitrogen / methane mixture is 1.8.

PRI me R 2. A. Obtaining polyarylate from compounds I and a mixture of 80/20 of isthphthaloyl / terephthaloyl chloride.

They work according to the procedure of Example 1, but with two changes in the amount of reagents. 10.734 g of a 45.9% aqueous solution of potassium hydroxide, 6.5 g of isophthaloyl chloride and 1.625 gerephthaloyl chloride are charged. The yield of the polyester is 28 g; the reduced viscosity is 0.37. This example has a ratio of 80/20 iso / ter.

B. A gas-permeable flat membrane having a thickness of 1.24 mils is prepared and evaluated for the permeability of oxygen, nitrogen, carbon dioxide, methane and gel.

P oxygen 5.7 Barrera. The selectivity of the oxygen / nitrogen mixture is 6.4.

P of carbon dioxide is 24 Barreram and the selectivity of the carbon dioxide / methane mixture using pure gases is 48.

R gels are 57 Barrers and the selectivity of the helium / methane mixture is 113.

Example 3 A, Preparation of polyrylates from 4.4 .2,2-trifluoro-1- / trifluoromethyl / ethylidene Zbis 2,6-dibromophenol (compound I and 25/75 isophthaloyl) of terephthaloyl chloride.

A 500 ml three-necked Morton flask equipped with a mechanical stirrer, thermometer, dropping funnel, nitrogen inlet and condenser was charged with 52.15 g of compound I, 0.8 g of tetrabutylammonium acid sulfate, 19.94 g of 45.9% aqueous hydroxide potassium, 160 ml of distilled water and 80 ml of methylene chloride. A solution of 12.18 g of terephthaloyl chloride and 4.06 g of isophthaloyl chloride in 160 ml of methylene chloride is charged over 15 minutes with very strong stirring and cooling in an ice bath. After stirring for 80 minutes, 100 ml of methylene chloride was added and a mixture of 0.5% sulfuric acid was acidified. The polymer solution is washed three times with 500 ml of distilled water. The polymer is coagulated in methanol and dried in a vacuum oven at 80 ° C. overnight. Yield 54.5 g of polyester. Reduced viscosity, 0.89.

B. They work according to the procedure of Example 1, and a gas-permeable flat membrane with a thickness of 2.7 mils is prepared. It has been found that there is a combination of high rates of permeability and selectivity in both gas separation processes.

R. oxygen 9.0 Barrers. The selectivity of the oxygen / nitrogen mixture is 6.1.

P of 42 barrera of carbon dioxide and a carbon dioxide / methane selectivity of 42; measurements were made on the basis of pure gases at a pressure of 35 psi / 2.461 kg / cm2.

R gels are 75 Barrers and the selectivity of the helium / methane mixture is 75.

P of nitrogen is 1.5 Barrera and the selectivity of the nitrogen / methane mixture is 1.5.

For comparison, the tetrabromobisphenol A-polycarbonate resin of Example 1 of EPA Ns 0242147 shows an oxygen P of 0.8 Barrera and an oxygen / nitrogen mixture selectivity of 7.4. The tetrabromobisphenol A-polycarbonate resin of Example 4 from ERA No. 0244126 shows an oxygen P of 1.23 Barrera and an oxygen / nitrogen mixture selectivity of 7.2.

The data for the bisphenol polyesters of the present invention show a better combination of permeability and oxygen / nitrogen separation factor compared to the values given in these two references. The polyester membranes of the present invention show permeability 11.25 times higher than polycarbonate and 7.32 times higher than polyester carbonate in references.

PRI me R 4. A. Obtaining polyarylate from compound I and 100% 4-bromisophthaloyl chloride.

They work according to the procedure of Example 1, but with two changes. 22.554 g of 4-bromisophthaloyl chloride are used and all the amounts are half less than those given in Example 1. The reduced viscosity is 0.29 in chloroform.

0 V. A gas-permeable flat membrane having a thickness of 3.91 mil is prepared and evaluated for the permeability of oxygen, nitrogen, carbon dioxide, methane and gel.

P of oxygen 4.7 Barrera, the selectivity of the oxygen / nitrogen mixture is 6.8.

P of carbon dioxide 19.4 Barrera and the selectivity of the mixture of carbon dioxide / methane is 49 at a pressure of 35 psi - 2,461 kg / cm2 when using pure gases. The mixed gas gives a carbon dioxide P of 17.2 Barrera and a selectivity of 48 at a pressure of 167 psi of 11.6 kg / cm2 using a 50/50 gas mixture.

R gels 51 Barrera and selectivity 5 of the mixture of helium / methane is 130.

P of nitrogen is 0.68 Barrera and the selectivity of the nitrogen / methane mixture is 1.7.

PRI me R 5. A. Obtaining polyarylate from compound I and 100% 2-bromoterephthaloyl-0 chloride.

They work practically according to the procedure of Example 1. Two changes were made: 2-bromisophthaloyl chloride was used instead of isophthaloyl chloride in Example 1, 5 only half the molar amounts of Example 1 were used. The yield was 31.7 g and R, 51.

B. Since the films look very cloudy, possibly due to the high crystallinity, no permeability measurements were made.

PRI me R 6. A. Obtaining polyarylate from compound 1 and 100% terephthaloyl chloride.

They work practically according to the method 5 of Example 1. The only difference is the use of 8.12 g of terephthaloyl chloride instead of isophthaloyl chloride in Example 1. The yield is 29 g of a polymer insoluble in methylene chloride; it appears to have a 0 crystalline structure.

Example. A Preparation of Polyarylate

from a mixture with a molar ratio of 80/20

bisphenol compounds I and III and mixtures with

a molar ratio of 75/25 terephthalo5 of chloride and isophthaloyl chloride.

They work according to the procedure of Example 3. The polyester yield is 27.8 g, and the viscosity is 0.39.

C. They work according to the procedure of Example 1, prepare a gas permeable membrane with a thickness of 2.3 mil and evaluate it. A combination of high values of both permeability rate and selectivity for gas separation processes has been found. P oxygen 9.3 Barrera. Selective | the oxygen / nitrogen mixture is 5.8. | Gels 73 Berrera and selectivity {helium / nitrogen mixture equal to 46. Example 8. A. Preparation of polyarylate from a mixture with a molar ratio of 70/30 bisphenol compounds I and III and a mixture with a molar ratio of 75/25 terephthalo - Ilchloride and Ieophthaloyl chloride,

They work according to the method of example 3. You I stroke of the polyester is 24.93 g, reduced viscosity 0.34.

I Work as described in Example 1, prepare a 4.1 mils gas permeable flat membrane and evaluate it. I found a combination of high values of both the permeability rate and the selective | gas separation processes. P oxygen 11.5 Barrera. The selectivity of the oxygen / nitrogen mixture is 5.6.

P gels are 88 Barrers and the selectivity of the helium / nitrogen mixture is 43. | Example 9. A. Preparation of polyarylate I from a mixture with a molar ratio of 60/40 of the bisphenol compounds I and IV and a mixture with a molar ratio of 75/25 of terephthaloyl chloride and isophthaloyl chloride. Work by the method of example 3, is- | the benefit of 10.78 g of 46 wt.%) aqueous potassium hydroxide and 40 ml of water. The yield of polyester is 25.74 g, reduced viscosity 0.57. i V. Work according to the method of example 1, | a gas-permeable flat membrane i i, 4.2 mil thick is prepared and evaluated. A combination of high values of I permeability rate and selectivity c was found; gas separation processes. | P oxygen 8.63 Barrera and selective | the oxygen / nitrogen mixture is 5.6. Gels 68.5 Barrera and the selectivity i of the helium / nitrogen mixture is 44. Example Example 10. A Preparation of Polyarylate from a mixture with a molar ratio of 70/30; bisphenol compounds I and II and mixtures with a polar ratio of 75/25 terephthalo-1-yl chloride and isophthaloyl chloride.

My method of example 9 works. You-; the course of the polyester is 27.1 g; the reduced viscosity is 0.59.

B. They work according to the procedure of Example 1, prepare a 4.1 mils flat permeable membrane and evaluate it. A combination of high values of permeability rate and selectivity in gas separation processes was found.

P of oxygen is 9.95 Barrera and the oxygen / nitrogen selectivity is 5.82.

R gels are 78 Barrers and the selectivity of the helium / nitrogen mixture is 46.

5P carbon dioxide, pure gas 42

Barrera, the selectivity of the carbon dioxide / methane mixture is 46. The separation of the 50/50 COa / SB gas mixture at a pressure of 3 atm has a selectivity of 44. This composition has a combination of both higher carbon dioxide permeability and better COa / SB permeability than known at this level of technology. If plasticization of these polyarylates does not occur as indicated, these membranes have an unexpected and unpredictable separation advantage.

CO2 / CH4.

Example 11. Preparation of polyarylate 0 from a mixture of bisphenols in a molar ratio of 60/40 of compounds I and II and a mixture of terephthaloyl chloride and isophthaloyl chloride in a molar ratio of 75/25.

They work according to the procedure of Example 9. The permeable flat membranes can be prepared according to the procedure of Example 1.

Example 12 A. Preparation of a polyarylate from a mixture of terephthaloyl chloride and isophthaloyl chloride in a molar ratio of 75/25. 0 Work according to the method of example 9. The output of the polyester 26.3 g, reduced viscosity of 0.38.

C. They work according to the procedure of Example 1, prepare a flat gas-permeable membrane 5 mm in thickness 4 mils and evaluate it. A combination of high rates of permeability and selectivity in gas separation processes was found.

The P of oxygen is 11.8 Barrera and the selectivity of oxygen / nitrogen is 5.53.

P gels of 85.1 Barrera and a helium / nitrogen mixture selectivity of 40.

PRI me R 13. Obtaining polyarylate

from a mixture of bisphenols in a molar ratio of 60/40 of compounds I and II and a mixture of tere.phthaloyl chloride and isophthaloyl chloride in

molar ratio 75/25.

They work according to the procedure of Example 9, using 4.06 g of each of terephthaloyl chloride and isophthaloyl chloride. The yield of polyester 25.2 g, the reduced viscosity is 0.29. According to the method of example 1, a flat permeable membrane can be prepared. 5

PRI me R 14. Obtaining polyarylate from a mixture of bisphenols in molar L; a ratio of 60/40 of compounds I and IV and skl .. l of terephthaloyl chloride and isoPhthaloyl oride in a molar ratio of 75/25.

They work as described in Example 1 using 6.091 g of isophthaloyl chloride and 2.03 terephthaloyl chloride. The yield of polyester is 25.3 g, and the viscosity is 0.75. A gas permeable flat membrane can be prepared according to the method of example 1.

Comparative experience 1.

A. Preparation of a polyarylate from compound II and 100% isophthaloyl chloride.

They work practically according to the procedure of Example 1 to obtain 19.9 g of polyester from 18.96 g of compound II and 8.12 g of isophthaloyl chloride. The viscosity is 0.46 in chloroform.

B. A 1.88 mil thick gas permeable flat membrane was prepared and evaluated for separation of a mixture of oxygen and nitrogen.

P oxygen is 5.64 Barrera and the oxygen / nitrogen selectivity is 6.1.

The permeability values / P in Barrers / and the selectivity of oxygen / nitrogen and helium / nitrogen mixtures for the polyesters of the present invention / first nine lines / and comparative literature data / last eight lines / as obtained by the present inventors are given in tab. 4.

Claims (4)

1. A method of separating a component from a gas mixture of oxygen with nitrogen or carbon dioxide with methane by contacting it with one side of the gas separation membrane, characterized in that, in order to increase the selectivity and rate of evolution of oxygen from its mixture with nitrogen and carbon dioxide from its mixture with with methane, a membrane comprising a thin layer consisting mainly of a polyester or copolyester obtained by reacting an aromatic dicarbonic acid is used as a gas separation membrane. or a derivative thereof and more than 50 mol. % tetrabromobisphenol of the general formula Vgvg where R1 is a divalent radical of 2,2,2-trifluoro-1- (trifluoromethyl) ethylidene or cyclododecyl, (wherein said aromatic dicarboxylic acid or its derivative includes at least 80 mol.% of isophthalic acid or its dichlorohydride and / or 4-bromisophthalic acid or its dichlorohydride and not more than 20 mol.% of terephthalic acid or its dichlorohydride and / or 2 - bromoterephthalic acid or its dichloride or either includes not more than 30 mol.% isophthaloyl dichloride and / or 4-bromisophthalic acid or its dichlorohydride and not less than 70 mol.% of terephthalic acid or its dichlorohydride and / or 2-bromoterephthalic acid or its a. 2. A method according to claim 1, with the fact that tetrabromobisphenol contains 100 mol.% Bisphenol diols. 3. A method according to claim 1, characterized in that the polyester or copolyester is obtained by reacting an aromatic dicarboxylic acid or its derivative and a mixture containing more than 50 mol.% Tetrabromobisphenol. And less than 50 mol.% Bisphenol of the General formula . to Rr where R1 is the divalent radical 2,2,2 trifluoro-1- (trifluoromethyl) ethylidene or cyclododecyl. R is methyl or chloride, 4. A method according to claim 3, characterized in that tetrabromobisphenol contains at least 80 mol. % mixture of diols. Table 1 Comparison of gas membranes to separate an oxygen / nitrogen mixture  - US patent No. 4818254. cl. B 01 D 53/22. 1989. C- US Patent No. 3899308, cl. B 01 D 53/22, 1975, US Pat. US Re No. 30351. - Commercial gas separation membranes I - Compound I of experiment 1, III - Tetrachlorhexafluorobisphenol-A. Comparison of gas membranes to separate a mixture of carbon dioxide / metam  - US Patent No. 4818254, cl. B 01 D 53/22. 1989. I - compound I from experiment 1., T a 6 l and 2 Table 3 Notes. EPA - - For EPO application, EPA-6 - For EPO application (, Texas - Tetrabromhexafluorobisphenol A-polycarbonate