KR100537809B1 - Preparation of carbon-silica membranes derived from thermally lable polymer containing blend polymer and the carbon-silica membranes - Google Patents

Abstract

The present invention relates to a carbon-silica molecular sieve separator prepared by pyrolyzing a polymer brand precursor including a polyimide siloxane and a thermally decomposable polymer, and a method for preparing the same, wherein the carbon-silica molecular sieve separator prepared by the present invention is helium, It has high permeability and efficient separation performance for gases such as hydrogen, oxygen, nitrogen, carbon dioxide and methane.

Description

Preparation of carbon-silica membranes derived from thermally lable polymer containing blend polymer and the carbon-silica membranes

The present invention relates to a carbon-silica molecular sieve separator prepared from a polymer brand precursor into which a thermally decomposable polymer is introduced, and a method for preparing the same, wherein the carbon-silica molecular sieve separator prepared according to the present invention comprises helium, hydrogen, oxygen, nitrogen, It has high permeability and efficient separation performance for gases such as carbon dioxide and methane.

The carbon molecular film was disclosed by Koresh and Soffer in 1983 in pyrolysis of an organic polymer precursor for the first time in US Pat. No. 4,685,940. After that, a carbon molecular sieve membrane for gas separation was generally manufactured using polyfurfuryl alcohol, polyvinylidene chloride, phenol formaldehyde, polyimide, etc. as a polymer precursor. As described above, the carbon molecular sieve membrane prepared by pyrolysis of the polymer precursor shows excellent permeability and separation performance with respect to gas as compared with a general polymer membrane.

Looking at the existing studies on the carbon film prepared by pyrolysis of the organic polymer precursor, the carbon film prepared by using the formaldehyde resin by W. Shusen of China in Journal of Membrane Science 109 (1996) 276-270 is oxygen The permeability was 2300 Barrer (1 × 10 ^-10 cm 3 (STP) cm / cm 2 · sec · cmHg) and the oxygen / nitrogen selectivity was 10.65, which was very good. In addition, U.S. Patent No. 4,685,940 discloses a carbon membrane prepared by carbonizing cellulose, which has a carbon / oxygen selectivity of 7.1 and an oxygen permeability of 0.71 GPU (1 × 10 ⁻⁶ cm 3 (STP) / cm 2. Sec cmHg). However, the above technologies have a problem in that the manufacturing time of the carbon molecular film is long, while increasing the temperature increase rate to shorten the manufacturing time has a disadvantage in that the mechanical strength is lowered and the practicality is lowered.

Also, in the Journal of Physical Chemistry B 101 (1997) 3988-3994, Suda et al., Japan, made a commercial polyimide Kapton film as a precursor to prepare a carbon film under vacuum and inert gas atmospheres, resulting in high selectivity of 36 with oxygen / nitrogen selectivity. Although a carbon molecular film having a film was prepared, in this case, the oxygen permeability is low as 0.96 Barrer, so there is a disadvantage that it is difficult to use.

Meanwhile, a method of preparing a carbon film by pyrolyzing not only an existing organic polymer precursor but also a silica-introduced polymer precursor in preparing a carbon molecular film has been known. In particular, the present inventors have disclosed polyimide siloxane (poly) in Korean Patent Laid-Open No. 2002-87821. (imide siloxane) A carbon-silica film having excellent performance of preparing a carbon film containing silica from a precursor and having an oxygen / nitrogen selectivity of 10 at an oxygen permeability of 168 Barrer has been disclosed.

Accordingly, the present inventors have continuously studied to find a carbon molecular sieve membrane having a high permeability without maintaining or greatly reducing the separation performance by easily controlling the porosity and the pore size of the carbon-silica molecular sieve membrane. It was found that carbon-silica molecular sieve membranes having high permeability were produced by carbonizing polymer brand precursors into which thermally decomposable polymers, such as pyrolytic polymers, were pyrolyzed under appropriate conditions. In addition, the porosity and the pore size of the carbon-silica molecular sieve membrane are affected by the content of the introduced thermally decomposable polymer, which separates gases such as helium / nitrogen, hydrogen / nitrogen, carbon dioxide / nitrogen, oxygen / nitrogen, carbon dioxide / methane, etc. It has been found that the present invention can be selectively applied in order to complete the present invention.

That is, it is an object of the present invention to provide a carbon-silica molecular sieve membrane having a high selectivity while having excellent selectivity and a method for producing the same.

The present invention for achieving the above object provides a carbon-silica molecular sieve membrane prepared using a polymer brand precursor to which a thermally decomposable polymer is introduced, and a method of manufacturing the same.

That is, the present invention is to raise the polymer brand precursor consisting of polyimide siloxane and pyrolytic polymer to 300 to 400 ℃ at a heating rate of 3 to 10 ℃ / min, then 400 to 550 at a heating rate of 1 to 5 ℃ / min Raising the temperature to 0 ° C. and carbonizing the same through an isothermal process of 0 to 3 hours at the same temperature, and heating the carbon-silica molecular sieve membrane subjected to the isothermal process to a temperature of 1 to 5 ° C./min to a temperature of 550 to 900 ° C. The present invention relates to a method for producing a carbon-silica molecular sieve membrane from a polymer brand in which a thermally decomposable polymer is introduced, comprising a step of carbonizing through an isothermal process of 0 to 3 hours at the same temperature.

The present invention also relates to a method for producing a carbon-silica molecular sieve membrane from a polymer brand in which a pyrolytic polymer is introduced, wherein the pyrolytic polymer is polyvinylpyrrolidone.

The present invention also provides a polymer in which the thermally decomposable polymer is polyvinylpyrrolidone, wherein the content of polyvinylpyrrolidone in the polymer brand precursor is 1 to 10% by weight based on the polymer brand precursor solution. A method for producing a carbon-silica molecular sieve membrane from a brand.

The present invention also relates to a gas-separated carbon-silica molecular sieve membrane prepared by the method of claim 1 using a polymer brand precursor composed of polyvinylpyrrolidone and polyimidesiloxane, which are pyrolytic polymers.

The present invention also relates to a carbon-silica molecular sieve membrane for gas separation, characterized in that the content of the thermally decomposable polymer in the polymer brand precursor is 1 to 10% by weight based on the polymer brand precursor solution.

Hereinafter, the carbon-silica molecular sieve membrane of the present invention and a manufacturing method thereof will be described in detail.

The polymer brand precursor for preparing the carbon-silica molecular sieve membrane of the present invention can be prepared using a mixture of thermally decomposable polymers of various compositions and polyimidesiloxane, wherein the polyimidesiloxane is an anhydride, a diamine and an amine group at the sock end. Contained siloxane oligomer can be produced by condensation.

Anhydrides include pyromellitic anhydride, benzophenone anhydride, 2,2-bis (3,4-dicarbophenyl) propane anhydride, 3,3 ', 4,4'-bisphenyl tetracarboxylic anhydride, bis (3 , 4-dicarboxylphenyl) ether anhydride, bis (3,4-dicarboxyphenyl) thioether anhydride, 2,3,6,7-naphthalene tetracarboxylic anhydride and bis (3,4-dicarboxylphenyl One or more may be selected from the group consisting of sulfone anhydrides.

Diamine monomers include meta- or para-phenylenediamine, 2,4- or 2,6-diaminotoluene, 4,4'-diamino phenylether, 4,4'-diaminobenzophenone, 4,4 ' One or more selected from the group consisting of -diamino phenyl sulfide, 4,4'-diamino phenylmethane, 3,3'-dimethylbenzidine, 4,4'-isopropylidene diamine.

As the siloxane oligomer containing an amine group at the sock end, preferably, one or more selected from the group consisting of dimethyl siloxane having a number average molecular weight of 900 to 1600 and the sock end is diamine can be used.

The thermally decomposable polymer is a polymer that decomposes at a low temperature of 500 degrees or less, and polyvinylpyrrolidone, polyethylene glycol, and phenol resin can be added according to the number average molecular weight, and preferably polyvinylpyrrolidone is a polymer. The content of the pyrolytic polymer in the brand precursor is preferably 1 to 10% by weight based on the polymer brand precursor solution.

For the synthesis of the polyimide siloxane precursor, polar solvents such as N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) or tetrahydrofuran (THF) A non-polar solvent such as a mixture is used, and a polymer brand precursor film is prepared by adding a thermally decomposable polymer, preferably polyvinylpyrrolidone, to the polyimidesiloxane solution thus prepared.

Meanwhile, the polyimidesiloxane / polyvinylpyrrolidone polymer brand precursor, which is a precursor of the carbon-silica molecular sieve membrane of the present invention, is equipped with a temperature program capable of controlling a temperature of up to 1500 degrees for carbonization through pyrolysis under various conditions. Pyrolysis is carried out in a tubular pyrolysis electric furnace. The pyrolysis step may be performed in an inert gas atmosphere, preferably under helium or argon at a flow rate of 100 cc / min or more.

In the present invention, in order to know the desirable temperature increase rate and final pyrolysis temperature for the carbonization process, a weight loss curve equipped with a mass spectrometer was used to analyze the type of gas generated in the weight loss curve and the weight loss portion. Temperature and final pyrolysis temperature of the present invention were determined.

The conversion rate for the carbonation reaction can be measured using FT-IR and Elemental Analyzer (EA), which can be identified by the height of the peaks of 1360, 1600 cm ^-1 for FT-IR, and carbon, hydrogen for EA. This can be confirmed by comparing the relative element contents with respect to oxygen, oxygen and nitrogen. In addition, the porosity, pore size, and pore volume of the final carbon-silica molecular sieve membrane due to thermal decomposition of the pyrolytic polymer can be confirmed by measuring the nitrogen gas adsorption amount using the BET method. The prepared carbon-silica molecular sieve membrane was confirmed gas separation performance by measuring the gas permeability for helium, carbon dioxide, oxygen and nitrogen, but the molecular sieve membrane of the present invention can not be used only for separation of the gas.

Hereinafter, one embodiment of the present invention will be described in more detail with reference to the following examples, which are intended for the purpose of description and are not intended to limit the present invention.

Example 1, Example 2 and Comparative Example 1

The polymer brand precursor solution in which polyvinylpyrrolidone was added in 2% and 5% by weight ratio in Examples 1 and 2 and the polymer brand precursor in which polyvinylpyrrolidone was not added in Comparative Example 1 were prepared. Same as

8 mol of 4,4'-diamino phenyl ether powder was added to a mixed solvent of N-methylpyrrolidone (NMP) and tetrahydrofuran (THF) to dissolve by stirring in a nitrogen atmosphere. To the completely dissolved solution, 2 mol of dimethylsiloxane oligomer (ODMS) having a number average molecular weight of 900 was added and stirred to dissolve. Slowly injecting 10 mol of pyromellitic anhydride powder into the completely dissolved solution and reacting for 6 hours, a solution having a yellow transparent viscosity is prepared. To the above solution, polyvinylpyrrolidone having a molecular weight of 10,000 was added to the polyimide siloxane solution in a weight ratio of 0% (Comparative Example 1), 2% and 5% (Examples 1 and 2), respectively, and stirred for 6 hours. A brand solution was prepared. The solution was cast on a glass plate, and then thermally cured for 1 hour at 100 ° C., 1 hour at 200 ° C., and 30 minutes at 250 ° C. to prepare a polymer brand precursor. The precursor prepared above was pyrolyzed to 550 ° C. at an elevated temperature rate of 3 ° C./min in an argon atmosphere at a flow rate of 300 cc / min using a tubular pyrolysis electric furnace to prepare a carbon-silica molecular sieve membrane. The permeability of helium, carbon dioxide, oxygen, and nitrogen was measured for the carbon-silica molecular sieve membrane prepared above, and the selectivity was calculated and shown in Table 1 below. Gas permeability was measured using a reduced pressure method and the pressure difference between the top and bottom of the permeation cell was adjusted to the range of 200-760torr. The calculation of permeability was calculated from the slope with respect to the increase in the bottom pressure over time in the defined bottom volume. The selectivity is also expressed as permeability / nitrogen permeability of the select gas. Meanwhile, in FIG. 1, nitrogen gas adsorption amount and adsorption behavior of the carbon-silica molecular sieve membrane according to the present invention according to the content of polyvinylpyrrolidone are shown together with Comparative Example 1 (a) and (b). And (c) show the results of Comparative Example 1, Example 1 and Example 2, respectively.

TABLE 1

Final pyrolysis temperature ( ^o C) Polyvinylpyrrolidone content (%) Permeability ^* Selectivity helium carbon dioxide Oxygen nitrogen Helium / nitrogen Carbon dioxide / nitrogen Oxygen / nitrogen Comparative Example 1 550 0 1113 523 135 15 74 35 9 Example 1 550 2 2523 1253 331 39 65 32 8 Example 2 550 5 5695 3129 1081 133 43 24 8

* Transmittance unit (Barrer), 1 Barrer = 10 ^-10 cm 3 (STP) cm / ㎠ · sec · cmHg

According to the above table, when 2% by weight and 5% by weight of polyvinylpyrrolidone are contained, respectively, it can be seen that the permeability for each gas is significantly improved without maintaining or significantly decreasing the selectivity.

Examples 3-4

The polymer brand precursor prepared in the same manner as in Example 2 was pyrolyzed, but the carbon-silica molecular sieve membrane was prepared by changing the final pyrolysis temperature to 600, 700 and 800 degrees instead of 550 degrees. The permeability of helium, carbon dioxide, oxygen, and nitrogen was measured for the prepared carbon-silica molecular sieve membrane, and selectivity was calculated and shown in Table 2 together with the values of Example 2. Gas permeability was measured in the same manner as in Example 1.

TABLE 2

Final pyrolysis temperature ( ^o C) Polyvinylpyrrolidone content (%) Transmittance Selectivity helium carbon dioxide Oxygen nitrogen Helium / nitrogen Carbon dioxide / nitrogen Oxygen / nitrogen Example 2 550 5 5695 3129 1081 133 43 24 8 Example 3 600 5 1182 603 242 17 70 35 14 Example 4 700 5 1033 469 155 11 94 43 14 Example 5 800 5 405 86 34 2 203 43 17

According to the results, as the pyrolysis temperature was increased, the permeability of each gas was slightly decreased, but the selectivity was increased.

Examples 6 and 7

The polymer brand precursor prepared in the same manner as in Example 2 was pyrolyzed to prepare a carbon-silica molecular sieve membrane, but the retention time at the final pyrolysis temperature of 550 degrees was adjusted to 120 and 240 minutes instead of 60 minutes. Gas permeability and selectivity of the prepared carbon-silica molecular sieve membrane are shown in Table 3, and the measurement was performed in the same manner as in Example 1.

TABLE 3

Final pyrolysis temperature ( ^o C) Isothermal Time (min) Permeability ^* Selectivity helium carbon dioxide Oxygen nitrogen Helium / nitrogen Carbon dioxide / nitrogen Oxygen / nitrogen Example 2 550 60 5695 3129 1081 133 43 24 8 Example 6 550 120 4783 1413 815 60 80 24 14 Example 7 550 240 4191 1324 801 46 91 29 17

As described above, the carbon-silica molecular sieve membrane into which the thermally decomposable polymer of the present invention is introduced has an improved gas permeability compared with the carbon-silica molecular sieve membrane derived from the polyimidesiloxane to which the pyrolytic polymer is not introduced. It can be used as a gas separation membrane. In general, the gas permeation performance and separation performance of the carbon-silica molecular sieve membrane derived from polyimide siloxane is determined in consideration of the final pyrolysis temperature, temperature increase rate, pyrolysis atmosphere, etc. In the case of using the carbon-silica molecular sieve membrane, the gas permeability and separation performance of the carbon-silica molecular sieve membrane can be controlled by controlling the content of the thermally decomposable polymer.

1 is a graph showing the nitrogen gas adsorption amount and the adsorption behavior of the carbon-silica molecular sieve membrane of Comparative Example 1 by the BET method.

FIG. 2 is a graph showing nitrogen gas adsorption amount and adsorption behavior of the carbon-silica molecular sieve membrane of Example 1 by the BET method. FIG.

3 is a graph showing the nitrogen gas adsorption amount and the adsorption behavior of the carbon-silica molecular sieve membrane of Example 2 by the BET method.

Claims (6)

The polymer brand precursor including the polyimide siloxane and the thermally decomposable polymer is heated to 300 to 400 ° C. at a heating rate of 3 to 10 ° C./min, and then to 400 to 550 ° C. at a heating rate of 1 to 5 ° C./min. Carbonization through an isothermal process of 0 to 3 hours at the same temperature, and the carbon-silica molecular sieve membrane subjected to the isothermal process is heated up to 550 to 900 ° C. at a temperature increase rate of 1 to 5 ° C./min and 0 at the same temperature. Method for producing a carbon-silica molecular sieve membrane from a polymer brand introduced with a thermally decomposable polymer, characterized in that the step of carbonizing through an isothermal process for 3 hours. The method of claim 1, wherein the thermally decomposable polymer is polyvinylpyrrolidone. The method of claim 2, wherein the content of the polyvinylpyrrolidone in the polymer brand precursor is 1 to 10% by weight based on the polymer brand precursor solution. . The method according to any one of claims 1 to 3, wherein the polymer brand precursor is heated to 350 ° C at a heating rate of 3 to 10 ° C / min, and then to 500 to 550 ° C at a heating rate of 1 to 5 ° C / min. Heating the carbon-silica molecular sieve membrane through an isothermal process of 0-2 hours at the same temperature, and isothermally increasing the temperature to a temperature of 550-800 ° C. at a heating rate of 1-5 ° C./min Method for producing a carbon-silica molecular sieve membrane from a polymer brand introduced with a pyrolytic polymer, characterized in that the step of carbonizing through an isothermal process of 0 to 2 hours. A gas-separated carbon-silica molecular sieve membrane prepared by the method of claim 1 using a polymer brand precursor comprising a thermally decomposable polymer and a polyimide siloxane. The carbon-silica for gas separation according to claim 5, wherein the thermally decomposable polymer is polyvinylpyrrolidone and the content of polyvinylpyrrolidone in the polymer brand precursor is 1 to 10% by weight based on the polymer brand precursor solution. Molecular sieve membrane.