A rare earth modified UiO-66 mixed matrix membrane and its preparation method and application

Abstract

This invention provides a rare-earth-modified UiO-66 hybrid matrix membrane, its preparation method, and its application. The hybrid matrix membrane comprises a polyamide-polyether block matrix membrane and rare-earth-modified UiO-66 filled within the matrix membrane. A casting solution is prepared by filling rare-earth-modified UiO-66 into a polyamide-polyether block (Pebax) solution, and then dried to form a membrane via solution evaporation. The introduction of rare-earth elements and amine groups improves the compatibility between UiO-66 and Pebax, and promotes the exposure of a large number of active sites for CO2 adsorption, enhancing the preferential adsorption of CO2, improving the CO2 permeability of the hybrid matrix membrane, and increasing the CO2 / N2 selectivity.

Description

Technical Field

[0001] This invention belongs to the field of gas separation technology, and particularly relates to a rare earth modified UiO-66 mixed matrix membrane, its preparation method and application. Background Technology

[0002] With rapid industrial development, human consumption of fossil fuels has increased, leading to a gradual increase in atmospheric CO2 concentration. The ever-increasing CO2 concentration in the atmosphere is one of the major challenges facing human society. CO2 is a significant contributor to the greenhouse effect, which can lead to global climate deterioration (global warming, extreme weather conditions, wildlife extinction, etc.) and seriously threaten human life and health, as well as the survival of all life forms on Earth, including humans.

[0003] Commonly used CO2 gas capture technologies include cryogenic distillation, solid adsorption, solvent absorption, and membrane separation. CN106621707A discloses a CO2 absorbent solution composed of a homogeneous mixture of amino-terminated polyether and an organic solvent, wherein the mass fraction of the amino-terminated polyether is 20-30%. However, this solution suffers from problems such as severe equipment corrosion, rapid deterioration of the absorbent, and high volatility. CN107998829A discloses a calcium-based absorbent for CO2 capture, its preparation method, and its application. The calcium-based absorbent contains 70%–90% active CaO, exhibiting advantages such as large absorption capacity and high cycle stability. However, the CaO carbonation process is prone to micropore blockage in the product layer, and the high regeneration temperature leads to CaO sintering, resulting in decreased absorption efficiency.

[0004] Membrane separation technology is a forward-looking gas separation technology that utilizes the differences in permeation rates of various gas components within a membrane, driven by a pressure difference, to achieve the separation and purification of a target gas. Compared with methods such as chemical absorption, adsorption, and cryogenic separation, membrane separation offers advantages such as no phase change, low energy consumption, simple equipment, low investment, small footprint, rapid start-up, convenient and safe operation, high operational reliability, and minimal environmental pollution, thus attracting widespread attention.

[0005] Polymers have become commonly used materials for membrane manufacturing due to their ease of processing, good film-forming properties, and high toughness. However, for most commercial polymer membranes (such as polysulfone, polyimide, and block copolymers), there is a trade-off between permeability and selectivity, known as the Robeson upper limit. Among these, polyamide-polyether block copolymers (Pebax) are alternating soft and hard segments, with polyether segments (PEO) as the soft segment and polyamide segments (PA) as the hard segment. PEO segments have strong interactions with CO2 molecules, while PA segments possess excellent mechanical properties; therefore, Pebax is widely used in CO2 separation membrane research. Hybrid matrix membranes are organic-inorganic hybrid membrane materials prepared by introducing inorganic porous particles into a polymer matrix, representing an effective method to simultaneously improve membrane permeability and selectivity. Various inorganic fillers, including nanotubes, graphene oxide, zeolites, and molecular sieves, have been widely used in hybrid matrix membranes.

[0006] CN110237726A discloses a polysulfone / graphene oxide / carbon nanotube hybrid matrix membrane and its preparation method, wherein the carbon nanotubes are acid-modified carbon nanotubes, and the graphene oxide and carbon nanotubes are dispersed in the polysulfone substrate membrane. However, the compatibility between inorganic fillers such as graphene oxide and carbon nanotubes and polymers is poor.

[0007] Therefore, there is an urgent need to provide a membrane separation material that is easy to prepare, has good polymer compatibility, and excellent CO2 separation performance. Summary of the Invention

[0008] The purpose of this invention is to provide a rare earth modified UiO-66 hybrid matrix membrane, its preparation method and application. The filling of rare earth modified UiO-66 material improves the relationship between the permeability and selectivity of Pebax membrane, greatly improving the CO2 permeability coefficient and CO2 / N2 selectivity. The hybrid matrix membrane has good application prospects in flue gas capture and other fields.

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a rare earth modified UiO-66 filled hybrid matrix membrane, the hybrid matrix membrane comprising a polyamide-polyether block matrix membrane and rare earth modified UiO-66 filled in the matrix membrane.

[0011] In this invention, the mixed matrix membrane improves the aggregation of UiO-66 and the compatibility of the two-phase interface by introducing rare earth modified UiO-66 into the polyamide polyether block copolymer (Pebax) matrix, resulting in a mixed matrix membrane with rich microporous structure.

[0012] As a preferred technical solution of the present invention, the polyamide-polyether block includes any one or a combination of at least two of Pebax-1657, Pebax-1074 or Pebax-2533. Typical but non-limiting examples of such combinations include: a combination of Pebax-1657 and Pebax-1074, a combination of Pebax-1074 and Pebax-2533, or a combination of Pebax-1657, Pebax-1074 and Pebax-2533, etc., with Pebax-1657 being the most preferred.

[0013] As a preferred technical solution of the present invention, the rare earth in the rare earth modified UiO-66 includes any one or at least two combinations of La, Ce, Pr, Nd, Pm, Sm or Eu. Typical but non-limiting examples of such combinations include: the combination of La and Ce, the combination of Pr and Nd, or the combination of Pm and Sm, etc., with Ce being the preferred one.

[0014] In this invention, Ce is a relatively inexpensive and abundant rare earth element, making it an attractive candidate for large-scale production of MOFs. Ce-MOFs have attracted widespread attention due to their microporous structure, Ce(III) / (IV) redox properties, and unfilled 4f orbitals.

[0015] Preferably, the molar ratio of the rare earth element to Zr in UiO-66 is 1:(1-8), for example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7 or 1:8, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0016] In this invention, rare earth elements are used to partially replace the Zr element in UiO-66. Through the competition of different metal ions for the same organic ligand, various coordination modes can be obtained, which promotes the exposure of a large number of active sites for CO2 adsorption and improves CO2 adsorption performance.

[0017] Preferably, the UiO-66 includes any one of UiO66-NH2, UiO-66-F4 or UiO-66-OH, and is preferably UiO66-NH2.

[0018] In this invention, the UiO-66 is preferably UiO-66-NH2 synthesized using diaminoterephthalic acid ligands.

[0019] Preferably, the specific surface area of ​​the rare earth modified UiO-66 is 800-1800 m². 2 g -1 For example, it could be 800m 2 g -1 1000m 2 g-1 1200m 2 g -1 1400m 2 g -1 1600m 2 g -1 or 1800m 2 g -1 The values ​​are not limited to those listed; other unlisted values ​​within the range also apply.

[0020] Preferably, the particle size of the rare earth modified UiO-66 is 50nm-1μm, for example, it can be 50nm, 100nm, 300nm, 500nm, 700nm or 1μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] As a preferred technical solution of the present invention, the mass percentage of rare earth modified UiO-66 in the mixed matrix membrane is 1-7wt%, for example, it can be 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt% or 7wt%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 3wt%.

[0022] As a preferred technical solution of the present invention, the thickness of the polyamide-polyether block matrix film is 50-70μm, for example, it can be 50μm, 54μm, 58μm, 60μm, 64μm, 68μm or 70μm, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0023] Preferably, the thickness of the mixed matrix membrane is 50-70 μm, for example, it can be 50 μm, 54 μm, 58 μm, 60 μm, 64 μm, 68 μm or 70 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] In this invention, by controlling the thickness of the Pebax membrane to be 50-70 μm and the thickness of the mixed matrix membrane to be 50-70 μm, the reproducibility of the membrane is ensured.

[0025] In a second aspect, the present invention provides a method for preparing the hybrid matrix membrane described in the first aspect, the method comprising the following steps:

[0026] (1) Mix the polyamide-polyether block and the solvent, and heat under reflux to obtain a polyamide-polyether block solution;

[0027] (2) The rare earth modified UiO-66 and the solvent were mixed, ultrasonically dispersed and stirred to obtain a rare earth modified UiO-66 dispersion;

[0028] (3) Stir and mix the polyamide-polyether block solution described in step (1) and the rare earth modified UiO-66 dispersion described in step (2) to obtain a casting solution;

[0029] (4) After degassing the casting solution described in step (3), pour it into a polytetrafluoroethylene mold, and allow it to stand and dry in sequence to obtain a mixed matrix membrane;

[0030] Steps (1) and (2) are not in any particular order.

[0031] As a preferred technical solution of the present invention, the solvent in step (1) includes any one or a combination of at least two of deionized water, ethanol, methanol, n-butanol, ethyl acetate, chloroform or N,N-dimethylformamide. Typical but non-limiting examples of such combinations include: a combination of deionized water and ethanol, a combination of methanol and n-butanol, or a combination of n-butanol and N,N-dimethylformamide, etc., preferably 70wt% anhydrous ethanol and 30wt% deionized water.

[0032] Preferably, the heating temperature in step (1) is 60-100℃, for example, it can be 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] Preferably, the heating time in step (1) is 1-8 hours, for example, it can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] As a preferred technical solution of the present invention, the preparation method of rare earth modified UiO-66 in step (2) includes: mixing rare earth source, zirconium source, ligand, regulator and solvent, and performing ultrasonic dispersion, solvothermal reaction and activation in sequence to obtain rare earth modified UiO-66.

[0035] Preferably, the rare earth source includes rare earth chlorides and / or rare earth nitrates.

[0036] Preferably, the zirconium source includes Zr(NO3)4 and / or ZrCl4, with ZrCl4 being the most preferred.

[0037] Preferably, the ligand comprises any one or a combination of at least two of terephthalic acid, diaminoterephthalic acid, tetrafluoroterephthalic acid, or dihydroxyterephthalic acid. Typical but non-limiting examples of such combinations include: a combination of terephthalic acid and diaminoterephthalic acid, a combination of tetrafluoroterephthalic acid and dihydroxyterephthalic acid, or a combination of terephthalic acid, diaminoterephthalic acid, and tetrafluoroterephthalic acid, etc., with diaminoterephthalic acid being the most preferred.

[0038] Preferably, the regulator comprises any one or a combination of at least two of formic acid, acetic acid, hydrochloric acid, or benzoic acid. Typical but non-limiting examples of such combinations include combinations of formic acid and hydrochloric acid, combinations of acetic acid and hydrochloric acid, or combinations of benzoic acid and hydrochloric acid, with acetic acid and hydrochloric acid being the most preferred.

[0039] Preferably, the solvent includes any one or a combination of at least two of ethanol, isopropanol, methanol, or N,N-dimethylformamide. Typical but non-limiting examples of such combinations include combinations of ethanol and isopropanol, isopropanol and methanol, or methanol and N,N-dimethylformamide, with N,N-dimethylformamide being the most preferred.

[0040] Preferably, the molar ratio of the rare earth source, zirconium source and ligand is 1:(1-8):(1-16), for example, it can be 1:1:1, 1:2:4, 1:3:5 or 1:8:16, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0041] In this invention, controlling the molar ratio of rare earth source, zirconium source and ligand within a specific range not only regulates the specific surface area and particle size of UiO-66, increasing its CO2 active adsorption performance, but also promotes its compatibility with Pebax matrix membrane.

[0042] In this invention, the molar ratio of the rare earth source, zirconium source, ligand, modifier and solvent is 1:(1-8):(1-16):(90-100):(450-500).

[0043] Preferably, the temperature of the solvothermal reaction is 120-180℃, for example, it can be 120℃, 130℃, 140℃, 150℃, 160℃, 170℃ or 180℃, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] Preferably, the solvothermal reaction time is 18-30 hours, for example, 18 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours or 30 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] Preferably, the activation is performed under vacuum conditions.

[0046] Preferably, the activation temperature is 100-150℃, for example, it can be 100℃, 110℃, 120℃, 130℃, 140℃ or 150℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] Preferably, the activation time is 5-12 hours, for example, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours or 12 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0048] Preferably, the ultrasonic dispersion time in step (2) is 30-90 min, for example, it can be 30 min, 40 min, 50 min, 60 min, 70 min, 80 min or 90 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0049] Preferably, the stirring speed in step (2) is 240-320 r / min, for example, it can be 240 r / min, 260 r / min, 280 r / min, 300 r / min or 320 r / min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0050] Preferably, the stirring time in step (2) is 30-120 min, for example, it can be 30 min, 50 min, 70 min, 90 min, 100 min, 110 min or 120 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0051] In this invention, the ultrasonic dispersion and stirring in step (2) are performed alternately 3-6 times.

[0052] As a preferred technical solution of the present invention, the stirring time in step (3) is 8-36h, for example, it can be 8h, 10h, 12h, 14h, 16h, 18h, 20h, 24h, 28h, 30h, 32h or 36h, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0053] Preferably, the settling temperature in step (4) is 25-45℃, for example, it can be 25℃, 27℃, 29℃, 32℃, 34℃, 36℃, 38℃, 40℃ or 45℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0054] Preferably, the settling time in step (4) is 12-36h, for example, it can be 12h, 14h, 16h, 18h, 20h, 24h, 28h, 30h, 32h or 36h, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0055] Preferably, the drying in step (4) is carried out under vacuum conditions.

[0056] Preferably, the drying temperature in step (4) is 50-80°C, for example, it can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0057] Preferably, the drying time in step (4) is 8-16 hours, for example, 8 hours, 10 hours, 12 hours, 14 hours or 16 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0058] Thirdly, the present invention provides an application of the hybrid matrix membrane described in the first aspect, wherein the hybrid matrix membrane is used for gas separation, preferably CO2 / N2 gas separation.

[0059] In this invention, the hybrid matrix membrane is used for the separation of preferentially permeating gases and non-preferentially permeating gases.

[0060] In this invention, the preferred permeation gas includes any one or a combination of at least two of CO2, CO, or propylene, preferably CO2.

[0061] In this invention, the non-preferred permeation gas includes N2.

[0062] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] (1) The hybrid matrix membrane of the present invention improves the compatibility between UiO-66 and Pebax by introducing rare earth elements and amine groups, and promotes the exposure of a large number of active sites for CO2 adsorption, enhances the preferential adsorption of CO2, enhances the CO2 permeability of the hybrid matrix membrane, and improves the CO2 / N2 selectivity.

[0065] (2) The preparation method provided by the present invention is simple to operate, has low energy consumption, low raw material price, wide applicability, and is expected to be applied in the industrial field. Attached Figure Description

[0066] Figure 1 SEM images of the separation membranes prepared in Examples 1, 4 and Comparative Example 2 of this invention;

[0067] Wherein, (a) is a surface view of the pure Pebax membrane described in Comparative Example 2, (b) is a cross-sectional view of the pure Pebax membrane described in Comparative Example 2, (c) is a surface view of the Pebax / CeZrUiO66-NH2 (3wt%) mixed matrix membrane described in Example 1, (d) is a cross-sectional view of the Pebax / CeZrUiO66-NH2 (3wt%) mixed matrix membrane described in Example 1, (e) is a surface view of the Pebax / CeZrUiO66-NH2 (5wt%) mixed matrix membrane described in Example 4, and (f) is a cross-sectional view of the Pebax / CeZrUiO66-NH2 (5wt%) mixed matrix membrane described in Example 4. Detailed Implementation

[0068] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0069] Example 1

[0070] This embodiment provides a method for preparing a hybrid matrix membrane, the method comprising the following steps:

[0071] (1) 2.57g Pebax-1657 was mixed with 17.5mL deionized water and 51.8mL anhydrous ethanol and heated and stirred in a water bath at 80℃ for 4h to obtain solution A;

[0072] (2) Mix 0.5 mmol CeCl3, 1.0 mmol ZrCl4, 2.0 mmol diaminoterephthalic acid and 74.34 mL N,N-dimethylformamide, then add 10.28 mL acetic acid and 0.34 mL 37 wt% hydrochloric acid, sonicate for 5 min, transfer to a 100 mL hydrothermal reactor and react at 150 °C for 24 h. Centrifuge the mixture to obtain a solid product, wash three times alternately with N,N-dimethylformamide and acetone, and finally vacuum dry and activate at 120 °C for 12 h to obtain CeZrUiO66-NH2; mix 0.079 g of ground CeZrUiO66-NH2 with 7.5 mL deionized water and 22.2 mL anhydrous ethanol, sonicate for 30 min, magnetically stir at 320 r / min for 30 min, and then repeat the process 5 times to obtain dispersion B;

[0073] (3) Add the dispersion B from step (2) to the solution A from step (1) and stir for 8 hours to obtain the casting solution;

[0074] (4) After degassing the casting solution in step (3), pour it into a polytetrafluoroethylene mold, let it stand at 30°C for 12 hours, and then vacuum dry it at 60°C for 8 hours to obtain a mixed matrix membrane.

[0075] Steps (1) and (2) are not in any particular order.

[0076] The specific surface area of ​​CeZrUiO66-NH2 prepared in this embodiment is 909 m². 2 g -1 The pore volume is 0.358 cm³. 3 g -1 The particle size is 80-150nm.

[0077] Example 2

[0078] This embodiment provides a method for preparing a mixed matrix membrane. Except for replacing "diaminoterephthalic acid" with "terephthalic acid" in step (2) to obtain CeZrUiO66, all other conditions are the same as in Example 1.

[0079] The specific surface area of ​​CeZrUiO66 prepared in this embodiment is 1120 m². 2 g -1 The pore volume is 0.397 cm³. 3 g -1 The particle size is 550-700nm.

[0080] Example 3

[0081] This embodiment provides a method for preparing a mixed matrix membrane. Except for replacing “0.079g CeZrUiO66-NH2” in step (2) with “0.026g CeZrUiO66-NH2”, all other conditions are the same as in Example 1.

[0082] Example 4

[0083] This embodiment provides a method for preparing a mixed matrix membrane. Except for replacing “0.079g CeZrUiO66-NH2” in step (2) with “0.135g CeZrUiO66-NH2”, all other conditions are the same as in Example 1.

[0084] Example 5

[0085] This embodiment provides a method for preparing a mixed matrix membrane. Except for replacing “0.079g CeZrUiO66-NH2” in step (2) with “0.193g CeZrUiO66-NH2”, all other conditions are the same as in Example 1.

[0086] Example 6

[0087] This embodiment provides a method for preparing a mixed matrix membrane. Except for replacing “0.079g CeZrUiO66” in step (2) with “0.026g CeZrUiO66”, all other conditions are the same as in Example 3.

[0088] Example 7

[0089] This embodiment provides a method for preparing a mixed matrix membrane. Except for replacing “0.079g CeZrUiO66” in step (2) with “0.135g CeZrUiO66”, all other conditions are the same as in Example 3.

[0090] Example 8

[0091] This embodiment provides a method for preparing a mixed matrix membrane. Except for replacing “0.079g CeZrUiO66” in step (2) with “0.193g CeZrUiO66”, all other conditions are the same as in Example 3.

[0092] Comparative Example 1

[0093] This comparative example provides a method for preparing a mixed matrix membrane. Except for replacing “0.5mmol CeCl3, 1.0mmol ZrCl4” in step (2) with “1.5mmol ZrCl4”, all other conditions are the same as in Example 1.

[0094] The specific surface area of ​​ZrUiO66-NH2 prepared in this comparative example is 878 m². 2 g -1 The pore volume is 0.345 cm³. 3 g -1 The particle size is 150-250nm.

[0095] Comparative Example 2

[0096] This comparative example provides a method for preparing a pure Pebax membrane. The preparation method includes: mixing 2.57g of Pebax-1657 with 25mL of deionized water and 74mL of anhydrous ethanol, heating and stirring in a water bath at 80℃ for 4h to obtain solution A, degassing the solution and pouring it into a polytetrafluoroethylene mold, letting it stand at 30℃ for 12h, and then vacuum drying it at 60℃ for 8h to obtain a pure Pebax membrane.

[0097] Comparative Example 3

[0098] This comparative example provides a method for preparing a pure Pebax membrane. Except for replacing "2.57g Pebax-1657" with "4.39g Pebax-1657" in Comparative Example 2, all other conditions are the same as in Comparative Example 2.

[0099] The microstructure of the separation membranes provided in Examples 1, 4, and Comparative Example 2 was tested using a JSM-7001F scanning electron microscope (SEM) manufactured by Hitachi, Japan. The test parameters were: voltage 10 kV, current 10 μA. Figure 1 In Figures (a) and (b), the test results of the separation membrane in Comparative Example 2 are shown. Figure 1 Images (c) and (d) show the test results for the separation membrane in Example 1. Figure 1 (e) and (f) are the test results of the separation membrane in Example 4.

[0100] Depend on Figure 1 SEM images of the surface and cross-section of the separation membranes showed that none of the membranes had obvious defects. In Example 1, CeZrUiO66-NH2 was uniformly dispersed in the Pebax matrix, exhibiting good interfacial compatibility with the polymer matrix. In Comparative Example 1, the pure Pebax membrane surface was dense and smooth. Compared to Example 1, in Example 4, as the CeZrUiO66-NH2 loading increased, the filler aggregated, and the performance decreased.

[0101] The membrane materials prepared in the above embodiments and comparative examples were used for CO2 / N2 gas separation. The permeation performance of the membrane materials was obtained by the pressure difference method. The testing device was the VAC-V2 gas permeator of Jinan Langguang Company. The testing steps were to attach the membrane between the high-pressure chamber (upper chamber) and the low-pressure chamber (lower chamber) and perform vacuum degassing on the upstream and downstream volumes.

[0102] The formula for the permeability coefficient is shown in (1).

[0103]

[0104] Where P(Bareer) is the gas permeability coefficient (1 Barrer = 10⁻⁶). -10 cm 3 (STP)cm cm -2 s -1 cmHg -1 ); A(cm 2 ) is the membrane area; l is the membrane thickness (cm); V is the volume of the lower chamber of the test chamber (cm²). 3 Δp (cmHg) is the pressure difference across the membrane; T is the temperature (K) under test conditions; dp / dt is the permeation rate (cmHg / s) of gas during stable permeation in the membrane.

[0105] The formula for the ideal selectivity of a gas is shown in (2).

[0106]

[0107] The specific test results are shown in Table 1.

[0108] Table 1

[0109]

[0110]

[0111] The following points can be observed from Table 1:

[0112] (1) The preparation method provided in Example 1 of this invention produces a mixed matrix membrane with excellent CO2 permeability and CO2 / N2 selectivity. As the feed pressure increases, the plasticizing effect of CO2 on the Pebax matrix membrane is enhanced, leading to an increase in the CO2 permeability. Since the N2 permeability does not change significantly, the CO2 / N2 selectivity also increases with increasing pressure. At 35°C and 0.3 MPa, the CO2 permeability of Example 1 is 100.70 Barrer, and the CO2 / N2 selectivity is 76.29, which is close to the upper limit of Robeson (2008).

[0113] (2) As can be seen from Examples 1 and 2, the introduction of amine groups improves the compatibility between the filler and the polymer, enhances the adsorption of CO2, enhances the CO2 permeability coefficient of the mixed matrix membrane, and improves the selectivity of CO2 / N2.

[0114] (3) Based on Examples 1 and 3-5, it can be seen that when the CeZrUiO66-NH2 filling amount is too low, the amount of micropores and amine groups introduced into the polymer is small, resulting in a decrease in the CO2 permeability coefficient and a decrease in CO2 / N2 selectivity; when the CeZrUiO66-NH2 filling amount is too high, due to the aggregation of CeZrUiO66-NH2, there are rigid chains between CeZrUiO66-NH2 and the polymer interface, resulting in a decrease in the CO2 permeability coefficient and a decrease in CO2 / N2 selectivity.

[0115] (4) Based on the comprehensive examples 1 and 1 comparative example, when ZrUiO66-NH2 is not modified with rare earth, ZrUiO66-NH2 has a smaller specific surface area, smaller pore volume, larger particle size, and fewer active sites for CO2 adsorption, which is not conducive to improving CO2 adsorption and separation performance.

[0116] (5) Based on the combined results of Example 1 and Comparative Example 2, it can be seen that by introducing CeZrUiO66-NH2 into the polyamide-polyether block copolymer (Pebax) matrix membrane, the aggregation of MOFs and the compatibility of the two-phase interface are improved. The resulting mixed matrix membrane has a rich microporous structure, which can enhance the preferential adsorption of CO2. Moreover, the CO2 permeability coefficient and CO2 / N2 selectivity of Example 1 are increased by 52.9% and 45.2% respectively compared with Comparative Example 2.

[0117] The applicant declares that the detailed structural features of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components selected in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A rare-earth-modified UiO-66-filled hybrid matrix membrane for CO2 / N2 gas separation, characterized in that, The hybrid matrix membrane comprises a polyamide-polyether block matrix membrane and rare earth modified UiO-66 filled in the matrix membrane; In the rare earth modified UiO-66, the molar ratio of rare earth to Zr in UiO-66 is 1:(2-8); The rare earth element in the rare earth modified UiO-66 is Ce, and UiO-66 is UiO66-NH2; The mass percentage of rare earth modified UiO-66 in the hybrid matrix membrane is 3-5 wt%.

2. The hybrid matrix membrane according to claim 1, characterized in that, The polyamide-polyether block includes any one or a combination of at least two of Pebax-1657, Pebax-1074, or Pebax-2533.

3. The hybrid matrix membrane according to claim 2, characterized in that, The polyamide-polyether block is Pebax-1657.

4. The hybrid matrix membrane according to claim 1, characterized in that, The specific surface area of ​​the rare earth modified UiO-66 is 800-1800 m². 2 g -1 .

5. The hybrid matrix membrane according to claim 1, characterized in that, The particle size of the rare earth modified UiO-66 is 50nm-1μm.

6. The hybrid matrix membrane according to claim 1, characterized in that, The thickness of the polyamide-polyether block matrix film is 50-70 μm.

7. The hybrid matrix membrane according to claim 1, characterized in that, The thickness of the hybrid matrix membrane is 50-70 μm.

8. A method for preparing a hybrid matrix membrane as described in any one of claims 1-7, characterized in that, The preparation method includes the following steps: (1) Mix the polyamide-polyether block and the solvent, and heat under reflux to obtain a polyamide-polyether block solution; (2) The rare earth modified UiO-66 and the solvent were mixed, ultrasonically dispersed and stirred to obtain a rare earth modified UiO-66 dispersion; The rare earth element in the rare earth modified UiO-66 is Ce, and UiO-66 is UiO66-NH2; (3) Stir and mix the polyamide-polyether block solution described in step (1) and the rare earth modified UiO-66 dispersion described in step (2) to obtain a casting solution; (4) After degassing the casting solution described in step (3), pour it into a polytetrafluoroethylene mold, and allow it to stand and dry in sequence to obtain a mixed matrix membrane; Steps (1) and (2) are not in any particular order.

9. The preparation method according to claim 8, characterized in that, The solvent in step (1) includes any one or a combination of at least two of the following: deionized water, ethanol, methanol, n-butanol, ethyl acetate, chloroform, or N,N-dimethylformamide.

10. The preparation method according to claim 8, characterized in that, The heating temperature in step (1) is 60-100°C.

11. The preparation method according to claim 8, characterized in that, The heating time in step (1) is 1-8 hours.

12. The preparation method according to claim 8, characterized in that, The preparation method of rare earth modified UiO-66 in step (2) includes: mixing rare earth source, zirconium source, ligand, regulator and solvent, and performing ultrasonic dispersion, solvothermal reaction and activation in sequence to obtain rare earth modified UiO-66.

13. The preparation method according to claim 12, characterized in that, The rare earth source includes rare earth chlorides and / or rare earth nitrates.

14. The preparation method according to claim 12, characterized in that, The zirconium source includes Zr(NO3)4 and / or ZrCl4.

15. The preparation method according to claim 12, characterized in that, The ligand includes any one or a combination of at least two of terephthalic acid, diaminoterephthalic acid, tetrafluoroterephthalic acid, or dihydroxyterephthalic acid.

16. The preparation method according to claim 15, characterized in that, The ligand is diaminoterephthalic acid.

17. The preparation method according to claim 12, characterized in that, The regulator includes any one or a combination of at least two of formic acid, acetic acid, hydrochloric acid, or benzoic acid.

18. The preparation method according to claim 12, characterized in that, The solvent includes any one or a combination of at least two of ethanol, isopropanol, methanol, or N,N-dimethylformamide.

19. The preparation method according to claim 12, characterized in that, The molar ratio of the rare earth source, zirconium source and ligand is 1:(1-8):(1-16).

20. The preparation method according to claim 12, characterized in that, The temperature of the solvothermal reaction is 120-180°C.

21. The preparation method according to claim 12, characterized in that, The solvothermal reaction takes 18-30 hours.

22. The preparation method according to claim 12, characterized in that, The activation is performed under vacuum conditions.

23. The preparation method according to claim 12, characterized in that, The activation temperature is 100-150°C.

24. The preparation method according to claim 12, characterized in that, The activation time is 5-12 hours.

25. The preparation method according to claim 8, characterized in that, The ultrasonic dispersion time in step (2) is 30-90 min.

26. The preparation method according to claim 8, characterized in that, The stirring speed in step (2) is 240-320 r / min.

27. The preparation method according to claim 8, characterized in that, The stirring time in step (2) is 30-120 min.

28. The preparation method according to claim 8, characterized in that, The stirring time in step (3) is 8-36 hours.

29. The preparation method according to claim 8, characterized in that, The temperature for standing in step (4) is 25-45°C.

30. The preparation method according to claim 8, characterized in that, The settling time in step (4) is 12-36 hours.

31. The preparation method according to claim 8, characterized in that, The drying in step (4) is carried out under vacuum conditions.

32. The preparation method according to claim 8, characterized in that, The drying temperature in step (4) is 50-80°C.

33. The preparation method according to claim 8, characterized in that, The drying time in step (4) is 8-16 hours.

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