Polyimide composite membrane with high CO2 selectivity and permeability and preparation method thereof

Abstract

The invention relates to a polymer separation membrane technology, in particular to a polyimide composite membrane with high CO2 selectivity and permeability, which is prepared by the following steps: by taking binary or polyamine containing ether oxygen groups as a water-phase monomer and quaternary acyl chloride or dianhydride as an oil-phase monomer, polymerizing on the surface interface of a support membrane to form a polyamide acid layer; and carrying out thermal imidization conversion to obtain the composite film with a polyimide separation layer. And the prepared composite membrane has good separation performance on CO2 / CH4 and CO2 / N2.

Description

Technical Field

[0001] The present invention relates to a method for preparing a polyimide separation layer on a support membrane by interfacial polymerization by adding a diamine or polyamine containing an ether oxygen group in an aqueous phase, and preparing a composite membrane with high CO2 selectivity and permeability, belonging to the field of gas separation membrane preparation. Background Art

[0002] CO2 is an important greenhouse gas that affects environmental problems such as global warming. At present, the reduction of CO2 emissions has become a global consensus. On the other hand, CO2 is also an important resource that needs to be separated, recovered, and reused during the production process. There are various technologies available for CO2 separation, such as absorption separation, adsorption separation, membrane separation, cryogenic distillation, chemical looping combustion, etc. Currently, the absorption method is widely used on a large scale, with the most mature development and the widest application; pressure swing adsorption is gradually being promoted. Gas separation membrane method has the advantages of small floor area, low investment cost, less secondary pollution, and low energy consumption, and is a research hotspot in recent years. Especially the characteristic of low energy consumption makes it more advantageous in the field of CO2 emission reduction.

[0003] Currently, commercially available CO2 separation membranes mainly include cellulose membranes, polyimide membranes, membranes, Polyactive TM membranes, and Polaris TM membranes. Cellulose and most polyimide membranes mainly achieve the permeation separation of CO2 through the selective diffusion of CO2. The performance of such traditional polymer membranes often cannot have both high permeability and selectivity. And the membranes, Polyactive TM membranes, and Polaris TM membranes are polymer membranes containing "soft chain" polyoxyethylene (PEO), and mainly rely on the selective dissolution of CO2 by the ether oxygen groups in the PEO chain segments to achieve the separation of CO2. The membranes often have both high selectivity and permeability. Polyimide homogeneous membranes containing PEO chain segments have been reported in the literature, but there are few reports on composite membranes. The key factor restricting the application of gas separation membrane technology in the field of CO2 separation is high-performance separation membranes. Developing high-performance composite membranes has always been one of the focuses in the research field of gas separation membranes. Summary of the Invention

[0004] The purpose of the present invention is to provide a composite membrane with high CO2 permeability and selectivity and its preparation method to solve the problem of low carbon dioxide separation coefficient of gas separation membranes.

[0005] To achieve the above purpose, the present invention provides a method for preparing a polyimide composite membrane with high CO2 selectivity and permeability, including the following steps:

[0006] (1) Prepare an organic phase solution containing tetraacyl chloride or dianhydride; the concentration is 0.01 - 0.1 g / ml;

[0007] (2) Dissolve a di- or polyamine containing an ether oxygen group in water to prepare an aqueous phase solution; the concentration is 0.01 - 0.1 g / ml;

[0008] (3) After contacting the support membrane with the organic phase solution for 2 - 30 min, obtain a support membrane adsorbed with organic phase monomers;

[0009] (4) Contact the support membrane adsorbed with organic phase monomers with the aqueous phase solution, and carry out an interfacial polymerization reaction for 1 - 60 min to obtain a nascent gas separation membrane. At this time, a polyamic acid layer is formed by interfacial polymerization;

[0010] (5) Imidize the nascent gas separation membrane: Place the membrane in a constant temperature for heat treatment. The heat treatment temperature is 120 - 250 °C, and the time is 1 - 12 h. After the polyamic acid is imidized, obtain a polyimide composite membrane.

[0011] Among them, the tetraacyl chloride or dianhydride described in (1) is one or a mixture of the following:

[0012] Pyromellitic tetrachloride, the structural formula is:

[0013] 3,3′,5,5′-Biphenyltetracarbonyl chloride, the structural formula is:

[0014] 2,2′,4,4′-Biphenyltetracarbonyl chloride, the structural formula is:

[0015] 2,2′,5,5′-Biphenyltetracarbonyl chloride, the structural formula is:

[0016] Pyromellitic dianhydride, the structural formula is:

[0017] 2,3,3′,4′-Biphenyltetracarboxylic dianhydride, the structural formula is:

[0018] 3,3′,4,4′-Biphenyltetracarboxylic dianhydride, the structural formula is:

[0019] 4,4′-(Hexafluoroisopropylidene)diphthalic anhydride, the structural formula is:

[0020] 3,4,9,10-Perylenetetracarboxylic dianhydride, the structural formula is:

[0021] (2) The binary or polyamine is one or a mixture of several of the following polyetheramines:

[0022] The structural formula is:

[0023]

[0024] Structural formula:

[0025] The structural formula is:

[0026]

[0027] (3) The support membrane is a composite membrane with polydimethylsiloxane coated on the surface of a polymer porous membrane. The polymer porous membrane material is polysulfone, polyethersulfone, polyetherimide, polyimide, or a mixture of the above substances.

[0028] The advantages of the present invention are as follows: Binary amines and polyamines containing ether oxygen groups are used as aqueous phase monomers, and polyimide is prepared by interfacial polymerization. The ether oxygen groups endow the polyimide separation layer with a high CO2 solubility coefficient and dissolution selectivity; at the same time, due to the rigid structure of the imide ring, which helps to improve the diffusion selectivity, the prepared polyimide composite membrane has higher CO2 permeability and selectivity. Description of the Drawings

[0029] Figure 1 It is the surface electron microscope photograph of the composite membrane prepared in Example 1

[0030] Figure 2 It is the cross-sectional electron microscope photograph of the composite membrane prepared in Example 1 Specific Embodiments

[0031] The composite membrane prepared by the present invention is tested with pure gases of CO2, N2, and CH4 to characterize the membrane performance. The tests are all carried out at 25°C and 0.2 MPa. The permeation performance of the membrane is expressed by the permeation rate, which is defined as the volume of gas passing through the membrane per unit time and per unit membrane area (volume under standard conditions), and the unit is GPU (1 GPU = 10 -6 cm 3 (STP) / cm 2 / s / cmHg). The selectivity of the membrane is expressed by the ideal separation factor, which is defined as the ratio of the permeation rates of two gases.

[0032] Example 1

[0033] The oil phase is an o-dichlorobenzene solution of 4,4′-(hexafluoroisopropylidene) diphthalic anhydride with a concentration of 0.025 g / ml; the aqueous phase is An aqueous solution with a concentration of 0.036 g / ml. The support membrane is a polydimethylsiloxane / polyetherimide composite membrane. When the polymerization reaction time is 25 min, the thermal imidization temperature is 180 °C and the time is 4 h, the CO2 permeation rate of the composite membrane is 149 GPU, the CO2 / N2 selectivity is 441, and the CO2 / CH4 selectivity is 190.

[0034] Example 2

[0035] The oil phase is a dichloromethane solution of 3,3′,5,5′-biphenyltetracarbonyl chloride with a concentration of 0.072 g / ml; the aqueous phase is An aqueous solution with a concentration of 0.055 g / ml. The support membrane is a polydimethylsiloxane / polyimide composite membrane. When the polymerization reaction time is 30 min, the thermal imidization temperature is 185 °C and the time is 4 h, the CO2 permeation rates of the composite membrane are 160 GPU, the CO2 / N2 selectivity is 444, and the CO2 / CH4 selectivity is 179.

[0036] Example 3

[0037] The oil phase is a dichloromethane solution of 2,2′,4,4′-biphenyltetracarbonyl chloride with a concentration of 0.015 g / ml; the aqueous phase is and An aqueous solution of T-3000 (mass ratio 9:1) with a total concentration of 0.079 g / ml for the two amines. The support membrane is a polydimethylsiloxane / polyethersulfone composite membrane. When the polymerization reaction time is 20 min, the thermal imidization temperature is 140 °C and the time is 2 h, the CO2 permeation rates of the composite membrane are 241 GPU, the CO2 / N2 selectivity is 303, and the CO2 / CH4 selectivity is 140.

[0038] Example 4

[0039] The oil phase is a dichloromethane solution of 2,2′,5,5′-biphenyltetracarbonyl chloride and pyromellitic tetracarbonyl chloride (mass ratio 1:2) with a total concentration of 0.081 g / ml for the two acid chlorides; the aqueous phase is An aqueous solution with a concentration of 0.078 g / ml. The support membrane is a polydimethylsiloxane / polysulfone composite membrane. When the polymerization reaction time is 15 min, the thermal imidization temperature is 120 °C and the time is 12 h, the CO2 permeation rate of the composite membrane is 275 GPU, the CO2 / N2 selectivity is 449, and the CO2 / CH4 selectivity is 257.

[0040] Example 5

[0041] The oil phase is a dichloromethane solution of 3,4,9,10-perylenetetracarboxylic dianhydride with a concentration of 0.088 g / ml; the aqueous phase is An aqueous solution with a concentration of 0.045 g / ml. The support membrane is a polydimethylsiloxane / polyetherimide composite membrane. When the polymerization reaction time is 20 min, the thermal imidization temperature is 190 °C and the time is 3 h, the CO2 permeation rate of the composite membrane is 355 GPU, the CO2 / N2 selectivity is 180, and the CO2 / CH4 selectivity is 83.

[0042] Example 6

[0043] The oil phase is a toluene solution of pyromellitic dianhydride with a concentration of 0.09 g / ml, and the water phase is and (with a mass ratio of 5:3) aqueous solution with a total concentration of 0.030 g / ml. The support membrane is a polydimethylsiloxane / polyimide composite membrane. When the polymerization reaction time is 30 min, the thermal imidization temperature is 250 °C and the time is 1 h, the CO2 permeation rate of the composite membrane is 164 GPU, the CO2 / N2 selectivity is 160, and the CO2 / CH4 selectivity is 51.

[0044] Example 7

[0045] The oil phase is a toluene solution of 2,3,3′,4′-biphenyltetracarboxylic dianhydride with a concentration of 0.085 g / ml; the water phase is aqueous solution with a concentration of 0.075 g / ml. The support membrane is a polydimethylsiloxane / polyimide composite membrane. When the polymerization reaction time is 25 min, the thermal imidization temperature is 220 °C and the time is 5.5 h, the CO2 permeation rate of the composite membrane is 580 GPU, the CO2 / N2 selectivity is 155, and the CO2 / CH4 selectivity is 64.

[0046] Example 8

[0047] The oil phase is a toluene solution of 3,3′,4,4′-biphenyltetracarboxylic dianhydride and pyromellitic tetrachloride with a total concentration of 0.080 g / ml, and the mass ratio of the dianhydride to the acyl chloride is 5:1; the water phase is and (with a mass ratio of 2:3) aqueous solution with a total concentration of 0.072 g / ml. The support membrane is a polydimethylsiloxane / polyetherimide composite membrane. When the polymerization reaction time is 2 min, the thermal imidization temperature is 130 °C and the time is 6 h, the CO2 permeation rate of the composite membrane is 792 GPU, the CO2 / N2 selectivity is 83, and the CO2 / CH4 selectivity is 56.

[0048] Finally, it should be noted that the above examples do not represent the limited scope of this patent. Any professional familiar with this field can very easily modify or make equivalent substitutions for the technical solutions of the present invention according to the content described in the patent, and these modifications or equivalent substitutions cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a polyimide composite membrane with high CO2 selectivity and permeability; characterized in that It includes the following steps: (1) Prepare an organic phase solution containing tetracarboxylic acid chloride or dianhydride; (2) Dissolve a binary or polyamine containing an ether oxygen group in water to form an aqueous phase solution; (3) After contacting the support membrane with the organic phase solution for 2 - 30 min, obtain a support membrane adsorbed with organic phase monomers; (4) Contact the support membrane adsorbed with organic phase monomers with the aqueous phase solution, and carry out an interfacial polymerization reaction for 1 - 60 min to obtain a nascent separation membrane. At this time, a polyamic acid layer is formed by interfacial polymerization; (5) Carry out thermal imidization on the nascent separation membrane: the thermal imidization temperature is 120 - 250 °C, and the time is 1 - 12 h, to convert the polyamic acid into polyimide and form a polyimide composite membrane.

2. The preparation method of a polyimide composite membrane with high CO2 selectivity and permeability according to claim 1, characterized in that: In step (1), the organic phase solution contains 0.01 - 0.1 g / ml of tetracarboxylic acid chloride or dianhydride.

3. The preparation method of a polyimide composite membrane with high CO2 selectivity and permeability according to claim 1, characterized in that: In step (1), the tetracarboxylic acid chloride or dianhydride contained in the organic phase solution is one or more of pyromellitic tetracarboxylic acid chloride, 3,3′,5,5′-biphenyltetracarboxylic acid chloride, 2,2′,4,4′-biphenyltetracarboxylic acid chloride, 2,2′,5,5′-biphenyltetracarboxylic acid chloride, pyromellitic dianhydride, 2,3,3′,4′-biphenyltetracarboxylic dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 4,4′-(hexafluoroisopropylidene)diphthalic anhydride, 3,4,9,10-perylenetetracarboxylic dianhydride.

4. The preparation method of a polyimide composite membrane with high CO2 selectivity and permeability according to claim 1, characterized in that: In step (2), the aqueous phase solution contains 0.01 - 0.1 g / ml of a binary or polyamine containing an ether oxygen group.

5. The preparation method of a polyimide composite membrane with high CO2 selectivity and permeability according to claim 1, characterized in that: In step (2), the binary or polyamine containing an ether oxygen group in the aqueous solution is: One or more of them.

6. The preparation method of a polyimide composite membrane with high CO2 selectivity and permeability according to claim 1, characterized in that: The support membrane described in step (3) is a composite membrane with a polydimethylsiloxane coating on the surface of a polymer porous membrane; the polymer porous membrane material is polysulfone, polyethersulfone, polyetherimide, polyimide, or a mixture of the above substances.

7. A composite membrane prepared by the preparation method of a polyimide composite membrane with high CO2 selectivity and permeability as described in any one of claims 1 - 6.

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