CN100464827C - Aniline copolymer and ethyl cellulose blend film and its preparation method and application - Google Patents

Abstract

The invention belongs to the technical field of polymer membrane air separation, in particular to an aniline copolymer and ethyl cellulose blend membrane, a preparation method and application thereof. The blend membrane is a self-supporting membrane of a blend of N-ethylaniline/aniline copolymer and ethyl cellulose. It is made by casting the organic solution of N-ethylaniline/aniline copolymer and ethyl cellulose, the organic solvent used is N-methylpyrrolidone or dimethyl sulfoxide, the two kinds of copolymer and ethyl cellulose The blending weight ratio of the polymers is 5:95˜95:5. The above-mentioned blended membrane can be used for air separation to increase the oxygen concentration in the air.

Description

Aniline copolymer and ethyl cellulose blend film and its preparation method and application

technical field

The invention belongs to the technical field of polymer membrane air separation, and in particular relates to a blend membrane of N-ethylaniline/aniline copolymer and ethyl cellulose, which is easy to be processed by solution, and its preparation method and application.

Background technique

The traditional air separation methods mainly include low-temperature refrigeration rectification separation method and pressure swing adsorption method. In recent years, membrane method air separation has been developed. , fast, safe and convenient advantages make it occupy a place in the field of air separation. The oxygen-enriched air and nitrogen-enriched air produced by it are expected to be used in various fields that require high-concentration oxygen and high-concentration nitrogen. In fish and shrimp farming, Iron and steel smelting industry, boiler combustion, medical care, food preservation, oil exploration and other fields have great promotion potential.

The key to membrane separation technology lies in the membrane material itself. The search for oxygen-enriched membrane materials with high selective separation coefficient and high permeability coefficient has always been the goal pursued by researchers, and has become the most challenging subject in membrane separation technology. . The air separation membrane materials that have been reported mainly include polymer membranes, carrier-facilitated transport membranes, molecular sieve membranes, ion transport membranes and organic-inorganic blend membranes (Huang Meirong, Li Xingui, Dong Zhiqing, Application progress of large-scale membrane air separation technology, Modern Chemical Industry, 2002, 22(9): 10-15), wherein the advantages of polymer membranes in preparation and storage have become the primary object of people's competing research and development. The polymer materials currently used mainly involve polyimide, polypyrrole, cellulose derivatives, polysiloxane, polysulfone and the like. Recent studies have shown that polyaniline, a conductive polymer with a conjugated large π bond structure, also has excellent gas separation performance (Anderson MR, Mattes BR, Reiss H, Kaner R B. Science, 1991, 252: 1412). However, it is difficult to obtain a homogeneous and dense film without pinhole defects from solution processing, and its gas permeability is poor and the flow rate is low. How to improve the film-forming property and permeation flux of gas in polyaniline has become the primary problem facing researchers.

Our research group used the method of copolymerization modification to carry out chemical oxidative copolymerization of N-ethylaniline and aniline, and obtained N-ethylaniline/aniline copolymer with good solubility and easy large-scale film formation (Huang Meirong, Gui Yunneng, Li Xingui, conductive aniline copolymer self-supporting film and its preparation method, 200710037532.2), the copolymer has shown better film-forming properties than polyaniline, and can be used for air separation after secondary doping to reduce the oxygen concentration in the air From 21% to 40.6%. In order to further improve the mechanical properties of the copolymer membrane, it is blended with highly flexible ethyl cellulose and cast into a homogeneous and dense membrane without pinhole defects, which is used for air separation to obtain oxygen-enriched membranes with high oxygen concentrations. Air.

Contents of the invention

The purpose of the present invention is to provide a blend film of aniline copolymer and ethyl cellulose with good flexibility and easy solution forming process, its preparation method and application.

The blend film of aniline copolymer and ethyl cellulose proposed by the present invention is a self-supporting film of N-ethylaniline/aniline copolymer and ethyl cellulose blend, which is made of N-ethylaniline/aniline The organic solution of the copolymer and the organic solution of ethyl cellulose are casted. The organic solvent used is N-methylpyrrolidone or dimethyl sulfoxide, etc., preferably N-methylpyrrolidone. The blending weight ratio of the two polymers, the copolymer and the ethyl cellulose, is 5:95-95:5, more preferably 65:35-75:25.

The N-ethylaniline and aniline copolymers used above are prepared by chemical oxidative polymerization. It is made into a self-supporting film by solution casting method, and the specific steps can be found in the patent (Huang Meirong, Gui Yunneng, Li Xingui, Conductive aniline copolymer self-supporting film and its preparation method, 200710037532.2). The preparation steps of the blended membrane are:

(1) Preparation of copolymer: Dissolve N-ethylaniline and aniline in the acidic reaction medium according to the feeding molar ratio of 5:95-95:5, then add the oxidizing agent at a constant temperature of 0-5°C and keep stirring , make the reaction complete, and post-treat the reaction product to obtain a copolymer powder;

(2) The copolymer of step (1) and ethyl cellulose are respectively dissolved in the organic solvent according to the aforementioned weight ratio, and then the two parts of the solution are mixed evenly; then the mixed solution is cast on the template, and the solvent is volatilized to form a film (available Infrared lamp drying at 60°C-70°C), and then stripping. Finally, the film is dried at a drying temperature of 90° C. to 110° C. to obtain a blend film of N-ethylaniline, aniline copolymer and ethyl cellulose.

In the above step (1), the oxidizing agent used is ammonium persulfate, sodium persulfate or potassium dichromate hydrochloric acid solution, nitric acid solution or acetic acid solution, etc., and the molar ratio of oxidizing agent to monomer is preferably 1:4-2 :1, most preferably 1:1, acidic reaction medium concentration is 0.01-3.0mol/L, preferably aqueous hydrochloric acid solution with a concentration of 1.0mol/L, and the reaction time is generally 2-48h.

In the above-mentioned step (2), the organic solvent used may be N-methylpyrrolidone or dimethyl sulfoxide or the like. When removing the film, just immerse the template cast with the copolymer in distilled water, and the temperature when the film is dried is preferably 90-100°C. Said template can be a glass plate, a plastic plate, etc., preferably a template with a low surface energy ratio, such as a glass plate or a polytetrafluoroethylene plate. The thickness of the cast membrane is controlled by the concentration of the casting solution, so that the thickness is 10-50 μm. If the membrane is too thick, the flow rate will be too low. If the membrane is too thin, the mechanical properties will be poor. The preferred thickness is 20-30 μm.

The blend membrane provided by the invention can be used for air separation to increase the oxygen concentration in the air. The specific method is to place the blend membrane in the oxygen-enriched membrane separation performance test device, control the temperature of the permeation tank at 15-50°C, and after the temperature is constant, turn on the air compressor and adjust the output air to 200-606KPa. After using the permeated gas to wash the measuring tube more than 10 times, time and start to collect the permeated gas to the scale line. The oxygen concentration in the gas in the trachea was measured by inhaling oxygen with cuproammonia solution. Calculate the oxygen-enriched air flow rate Q[mL(STP)/s cm ² ] from formula (1), and calculate the oxygen-enriched air concentration Y _O2 (%) from formula (2):

Oxygen-enriched air flow: Q＝V ₀ /t·A (1)

In the formula: t is the time required to collect V ₀ mL of gas in the burette, in s; A: the effective area of the permeation cell, in cm ² .

The concentration of oxygen in the permeated gas is: $Y_{o_2}=(V_0-V_1)/V$ (2)

In the formula: V ₀ is the total volume of permeated gas collected in the burette, in mL; V ₁ is the volume of residual gas in the burette after oxygen inhalation, in mL.

For details, please refer to the test method of oxygen-enriched membrane separation performance, see Chinese Patent No.: ZL 03114757.7.

Beneficial effects of the present invention:

The present invention uses chemical oxidation copolymerization modified N-ethylaniline/aniline copolymer and ethyl cellulose blend membrane as air separation membrane material, utilizes the flexibility of ethyl cellulose membrane to further improve N-ethylaniline/aniline The film-forming property of the aniline copolymer has excellent oxygen and nitrogen separation performance and is easy to prepare. The obtained blend film is in an amorphous state or a partially crystalline state, and has a certain free volume between molecules, which is favorable for oxygen to permeate, thereby increasing the gas flow rate. Using the blended membrane of the invention as an air separation membrane can increase the concentration in the air to more than 25%, reaching 25%-40%. When the blending weight ratio of copolymer and ethyl cellulose is 70/30, the blended membrane has the best gas separation performance. When the operating temperature is 47℃ and the operating pressure is 606kPa, the oxygen enrichment concentration can reach 47.6%.

Description of drawings

Wide-angle X-ray diffraction patterns of blend films with blend ratios of 20/80, 50/50, and 70/30.

Detailed ways

Example 1

Weigh 0.1g of N-ethylaniline/aniline copolymer and 0.4g of ethyl cellulose, and dissolve them in N-methylpyrrolidone respectively. After the polymer is completely dissolved, filter the copolymer solution with a sand core funnel, and then separate the two parts Mix the solution evenly, cast the mixed solution on a horizontal glass plate at room temperature, dry it with an infrared lamp at 60-70°C, remove the film in distilled water, and then heat-treat the blend film at 90-110°C for 2-4 hours, a blend film with a weight ratio of the blend to ethylcellulose of 20/80 was obtained, and the film thickness was 26.5 μm. The stress-strain curve test shows that the breaking strength and breaking elongation of the film are 44.5MPa and 3.67%, respectively.

Weigh 0.25g of N-ethylaniline/aniline copolymer and 0.25g of ethyl cellulose, and other operations are the same as above to obtain a blend film with a weight ratio of the blend to ethyl cellulose of 50/50, and the film thickness is 26.3 μm . The stress-strain curve test shows that the breaking strength and breaking elongation of the film are 52.6MPa and 3.31%, respectively.

Weigh 0.35g of N-ethylaniline/aniline copolymer and 0.15g of ethyl cellulose, and other operations are the same as above to obtain a blend film with a weight ratio of the blend to ethyl cellulose of 70/30, and the film thickness is 26.3 μm . The stress-strain curve test showed that the breaking strength and breaking elongation of the film were 59.1MPa and 3.0%, respectively.

The wide-angle X-ray diffraction spectra of the blended films of the above three blending ratios are shown in Figure 1. The blended film has no sharp diffraction peaks in the entire scanning range, and only a very broad peak appears at about 22° , exhibiting amorphous or partially crystalline character.

Example 2

Place the 20/80 blend membrane prepared in Example 1 in the osmosis cell with an effective permeation area of ^70.9 cm in the oxygen-enriched membrane separation performance testing device, tighten the screws, and control the temperature of the osmosis cell at 25°C , and strictly check whether the device is leaking. Turn on the air compressor and adjust the output air to 101KPa. After using the permeated gas to wash the gas tube for more than 10 times, start to collect the permeated gas to the scale line. After the collection is completed, count the time and close the air inlet. The flow rate of the oxygen-enriched air was measured to be 1.5×10 ^-5 mL (STP)/s cm ² , and the oxygen concentration in the gas in the trachea was measured to be 32.1% by inhaling oxygen with cuproammonia solution. Changing the operating pressure to 202KPa, 303KPa, 404KPa, 505KPa, the measured oxygen-enriched air flow rate is 1.5×10 ^-5 mL(STP)/scm ² , 1.8×10 ^-5 mL(STP)/s cm ² , 2.4× 10 ^-5 mL (STP)/s cm ² , 3.3×10 ^-5 mL (STP)/s cm ² . The oxygen concentrations were 32.0%, 34.1%, 34.9%, and 35.2%, respectively.

Example 3

Place the 50/50 blend membrane prepared in Example 1 in the osmosis cell with an effective permeation area of ^70.9 cm in the oxygen-enriched membrane separation performance testing device, tighten the screws, and control the temperature of the osmosis cell at 25°C , and strictly check whether the device is leaking. Turn on the air compressor and adjust the output air to 202KPa. After using the permeated gas to wash the gas tube for more than 10 times, start to collect the permeated gas to the scale line. After the collection is completed, count the time and close the air inlet. The flow rate of the oxygen-enriched air was measured to be 5.0×10 ^-7 mL(STP)/s cm ² , and the oxygen concentration in the gas in the trachea was measured to be 34.8% by inhaling oxygen with cuproammonia solution. Changing the operating pressure to 350KPa, 400KPa, 500KPa, and 606KPa, the measured oxygen-enriched air flow rates were 5.2×10 ^-7 mL(STP)/s cm ² , 6.1×10 ^-7 mL(STP)/s cm ² , 6.3 ×10 ^-7 mL(STP)/s cm ² , 6.5×10 ^-7 mL(STP)/s cm ² . The oxygen concentrations were 36.1%, 36.8%, 37.0%, and 39.3%, respectively.

Example 4

^Place the 70/30 blend membrane prepared in Example 1 in the osmosis pool with an effective permeation area of 70.9 cm in the oxygen-enriched membrane separation performance testing device, tighten the screws, and control the temperature of the osmosis pool at 25°C , and strictly check whether the device is leaking. Turn on the air compressor and adjust the output air to 250KPa. After using the permeated gas to wash the gas tube for more than 10 times, start to collect the permeated gas to the scale line. After the collection is completed, count the time and close the air inlet. The flow rate of the oxygen-enriched air was measured to be 2.0×10 ^-5 mL (STP)/s cm ² , and the oxygen concentration in the gas in the trachea was measured to be 34.6% by inhaling oxygen with cuproammonia solution. Change the operating pressure to 300KPa, 400KPa, 500KPa, 606Kpa, and 700KPa, and the measured oxygen-enriched air flow rate is 3.1×10 ^-5 mL(STP)/s cm ² , 3.8×10 ^-5 mL(STP)/s cm ^{2 respectively} , 4.6×10 ^-5 mL (STP)/s cm ² , 8.1×10 ^-5 mL (STP)/s cm ² , 8.3×10 ^-5 mL (STP)/s cm ² . The oxygen concentrations were 35.0%, 39.1%, 41.1%, 44.6%, and 41.9%, respectively.

Example 5

Place the 20/80 blend membrane prepared in Example 1 in the permeation tank with an effective permeation area of ^70.9 cm in the oxygen-enriched membrane separation performance testing device, tighten the screws, and control the temperature of the permeation tank at 20°C , and strictly check whether the device is leaking. Turn on the air compressor and adjust the output air to 101KPa. After using the permeated gas to wash the gas tube for more than 10 times, start to collect the permeated gas to the scale line. After the collection is completed, count the time and close the air inlet. The flow rate of the oxygen-enriched air was measured to be 3.4×10 ^-6 mL (STP)/s cm ² , and the oxygen concentration in the gas in the trachea was measured to be 31.3% by inhaling oxygen with cuproammonia solution. Changing the operating temperature to 30°C, 40°C, 50°C, and 60°C, the measured oxygen-enriched air flow rates were 6.9×10 ^-6 mL(STP)/s cm ² , 1.0×10 ^-5 mL(STP)/s respectively cm ² , 1.5×10 ^-5 mL(STP)/s cm ² , 1.6×10 ^-5 mL(STP)/s cm ² . The oxygen concentrations were 30.8%, 27.8%, 26.1%, and 25.0%, respectively.

Example 6

Place the 50/50 blend membrane prepared in Example 1 in the osmosis cell with an effective permeation area of ^70.9 cm in the oxygen-enriched membrane separation performance testing device, tighten the screws, and control the temperature of the osmosis cell at 16°C , and strictly check whether the device is leaking. Turn on the air compressor and adjust the output air to 505KPa. After using the permeated gas to wash the gas tube for more than 10 times, start to collect the permeated gas to the scale line. After the collection is completed, count the time and close the air inlet. The flow rate of the oxygen-enriched air was measured to be 2.0×10 ^-6 mL (STP)/s cm ² , and the oxygen concentration in the gas in the trachea was measured to be 37.1% by inhaling oxygen with cuproammonia solution. Changing the operating temperature to 30°C, 40°C, 50°C, and 60°C, the measured oxygen-enriched air flow rates were 2.0×10 ^-6 mL(STP)/s cm ² , 2.5×10 ^-6 mL(STP)/s respectively cm ² , 3.3×10 ^-6 mL(STP)/s cm ² , 6.2×10 ^-6 mL(STP)/s cm ² . The oxygen concentrations were 37.2%, 37.5%, 36.8%, and 35.9%, respectively.

Example 7

Place the 70/30 blend membrane prepared in Example 1 in the osmosis cell with an effective permeation area of ^70.9 cm in the oxygen-enriched membrane separation performance testing device, tighten the screws, and control the temperature of the osmosis cell at 30°C , and strictly check whether the device is leaking. Turn on the air compressor and adjust the output air to 505KPa. After using the permeated gas to wash the gas tube for more than 10 times, start to collect the permeated gas to the scale line. After the collection is completed, count the time and close the air inlet. The flow rate of the oxygen-enriched air was measured to be 1.9×10 ^-6 mL (STP)/s cm ² , and the oxygen concentration in the gas in the trachea was measured to be 41.0% by inhaling oxygen with cuproammonia solution. Changing the operating temperature to 40°C, 50°C, 63°C, and 68°C, the measured oxygen-enriched air flow rates were 2.1×10 ^-6 mL(STP)/s cm ² , 2.3×10 ^-6 mL(STP)/s respectively cm ² , 2.5×10 ^-6 mL(STP)/s cm ² , 2.6×10 ^-6 mL(STP)/s cm ² . The oxygen concentrations were 43.1%, 45.2%, 45.0%, and 44.8%, respectively.

Example 8

Place the 70/30 blend membrane prepared in Example 1 in the permeation tank with an effective permeation area of ^70.9 cm in the oxygen-enriched membrane separation performance testing device, tighten the screws, and control the temperature of the permeation tank at 47°C , and strictly check whether the device is leaking. Turn on the air compressor and adjust the output air to 303KPa. After using the permeated gas to wash the gas tube for more than 10 times, start to collect the permeated gas to the scale line. After the collection is completed, count the time and close the air inlet. The flow rate of the oxygen-enriched air was measured to be 5.4×10 ^-7 mL(STP)/s cm ² , and the oxygen concentration in the gas in the trachea was measured to be 41.7% by inhaling oxygen with cuproammonia solution. Changing the operating pressure to 404KPa, 505KPa, 606KPa, and 707KPa, the measured oxygen-enriched air flow rates were 7.8×10 ^-7 mL(STP)/s cm ² , 1.3×10 ^-6 mL(STP)/s cm ² , 1.5 ×10 ^-6 mL(STP)/s cm ² , 1.9×10 ^-6 mL(STP)/s cm ² . The oxygen concentrations were 44.5%, 46.6%, 47.6%, and 45.1%, respectively.

Claims (6)

1, the blend film of a kind of aniline and ethyl cellulose, it is characterized in that described blend film is the self-supported membrane of N-ethylaniline/aniline and ethyl cellulose blend, form by the copolymer organic solution of N-ethylaniline/aniline and the organic solution casting system of ethyl cellulose; Used organic solvent is N-methyl pyrrolidone or dimethyl sulfoxide (DMSO), and the weight ratio of these two kinds of polymer of copolymer and ethyl cellulose is 5:95～95:5.

2, the preparation method of the blend film of aniline according to claim 1 and ethyl cellulose is characterized in that concrete steps are as follows:

(1) preparation of copolymer: is that 5:95～95:5 is dissolved in the acid reaction medium with N-ethylaniline and aniline according to the feeding mol ratio, when 0～5 ℃ of constant temperature, add oxidant then, do not stop to stir, make to react completely, product is carried out post processing obtain copolymer powder;

(2) copolymer and the ethyl cellulose with step (1) is dissolved in respectively in the organic solvent according to described part by weight, two parts solution mixed again; Then mixed solution is cast on the template, the solvent evaporates film forming, demoulding again, at last with the film drying, baking temperature is 90 ℃-110 ℃, promptly gets N-ethylaniline and aniline and ethyl cellulose blend membrane.

3, the preparation method of the blend film of aniline according to claim 2 and ethyl cellulose, it is characterized in that in the step (1), used oxidant is hydrochloric acid solution, salpeter solution or the acetic acid solution of ammonium persulfate, sodium peroxydisulfate or potassium bichromate, the mol ratio of oxidant and monomer is 1:4～2:1, acid reaction medium concentration is 0.01～3.0mol/L, and the reaction time is 2～48h.

4, the preparation method of the blend film of aniline according to claim 2 and ethyl cellulose, it is characterized in that used organic solvent is N-methyl pyrrolidone or dimethyl sulfoxide (DMSO) in the step (2), described demoulding is that the template that will be cast with copolymer is dipped in the distilled water; Temperature when described film is dry is 90-100 ℃.

5, according to the application of blend film in air separation of described aniline of claim 1 and ethyl cellulose.

6, application according to claim 5 is characterized in that blend membrane places oxygen permeable membrane separating property testing arrangement, and the temperature of osmotic cell is controlled at 15-50 ℃, treat temperature constant after, open air compressor machine, delivery air is transferred to 200～606KPa.

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