Multilayer polycyclic aromatic hydrocarbon organic film and preparation method and application thereof

Abstract

The invention discloses a multilayer polycyclic aromatic hydrocarbon organic membrane as well as a preparation method and application thereof. The preparation method comprises the following steps: cleaning and drying a polyacrylonitrile substrate; dropwise adding a poly [1-(trimethylsilyl)-1-propyne] solution on the polyacrylonitrile substrate, and carrying out spin coating to form a uniform supporting layer; the preparation method comprises the following steps: preparing pre-prepared hexa (tripyridine) hexaphenylbenzene polycyclic aromatic hydrocarbon into a hexa (tripyridine) hexaphenylbenzene polycyclic aromatic hydrocarbon monomolecular layer compressed film by adopting a Langeron film preparation instrument, and transferring the monomolecular layer compressed film to the surface of a polyacrylonitrile substrate spin-coated with a poly [1-(trimethylsilyl)-1-propyne] layer; the multi-layer polycyclic aromatic hydrocarbon organic membrane is obtained by repeating the monomolecular layer compression and horizontal contact transfer process, the efficient size exclusion effect is achieved, and the method has the advantages of high permeability, high selectivity, rapidness and low-cost preparation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of functional materials, and relates to a gas separation membrane material, in particular to a multilayer condensed ring aromatic organic membrane as well as a preparation method and application thereof. BACKGROUND

[0002] Sulfur hexafluoride (SF6) is widely used in high-voltage electrical equipment due to its excellent insulation performance and arc extinguishing ability, usually mixed with nitrogen (N2) to form a gas insulation medium, accounting for about 80% of its global consumption. In addition, sulfur hexafluoride also has important application value in the fields of semiconductor manufacturing, metal casting and medicine. However, sulfur hexafluoride is also the greenhouse gas with the highest global warming potential (GWP), with a global warming potential of about 23,900 times that of carbon dioxide and a long atmospheric lifetime of 3200 years. Therefore, promoting the efficient recycling of sulfur hexafluoride is of great significance to mitigate its environmental impact. Currently, sulfur hexafluoride recovery mainly uses physical methods such as low-temperature distillation, liquefaction and freezing, but these methods have problems such as high energy consumption and complex equipment, especially when dealing with low-concentration sulfur hexafluoride, the efficiency is low, which limits its feasibility in large-scale applications. Therefore, developing a high-selectivity, low-energy-consumption nitrogen / sulfur hexafluoride (N2 / SF6) separation technology has become a key path to achieve resource recycling and emission reduction goals.

[0003] In recent years, membrane separation technology is considered an ideal alternative for nitrogen / sulfur hexafluoride separation due to its low energy consumption and simple process. Inorganic membranes, with their regular pore size structure and excellent thermal stability, show great potential in separation performance. For example, MFI-type zeolite membranes have a nitrogen permeance of more than 20,000 GPU, but due to their large pore size (about 0.55 nm), their nitrogen / sulfur hexafluoride selectivity is still less than 20, only at a medium level. By optimizing the template removal process, CHA-type high-silicon SSZ-13 membranes were prepared, which were thin and defect-free, and exhibited extremely high nitrogen / sulfur hexafluoride selectivity (>700) at 22°C and 200°C. However, the synthesis process of such membranes is complex, long cycle, and has poor mechanical stability, which restricts its industrial application. In contrast, organic polymer membranes such as polysulfone (PSF), polycarbonate (PC) and polyimide (PI) are more promising in industry due to their ease of film processing. CHOI et al. reported that the N2 / SF6 selectivity of PI membranes can reach 38.8, and LI et al. further tested the stability of the membranes under high temperature and high pressure conditions for 1050 hours, and the selectivity increased to 104. However, overall, the nitrogen permeance of such polymer membranes is still low (e.g. about 6.4 GPU), which cannot meet the requirements of high selectivity and high flux.

[0004] Therefore, although the existing organic membranes meet the separation requirements to some extent, there are still obvious limitations in the comprehensive performance, and it is difficult to meet the practical application requirements of efficient separation of nitrogen / sulfur hexafluoride. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a multi-layer condensed ring aromatic organic membrane and a preparation method and application thereof, which is based on Langmuir-Blodgett assembly technology to construct a multi-layer condensed ring aromatic organic membrane, realize high-efficiency size exclusion effect, and has the advantages of high permeability, high selectivity, and fast and low-cost preparation.

[0006] In order to achieve the above-mentioned purpose, the technical scheme is adopted as follows:

[0007] A preparation method of a multi-layer condensed ring aromatic organic membrane, comprising the following steps:

[0008] Step one: washing and drying treatment is performed on a square thin sheet-shaped polyacrylonitrile substrate with a side length of 2cm;

[0009] Step two: 200-250uL of a poly[1-(trimethylsilyl)-1-propyne] solution with a concentration of 1.25%w / v is added dropwise on the polyacrylonitrile substrate treated in step one, and spin coating is performed to form a uniform support layer;

[0010] Step three: a previously prepared hexakis(triphenylphosphine)hexaphenylbenzene polycyclic aromatic compound is dissolved in chloroform to form a solution with a concentration of 1mg / mL, 25-30uL of the solution is added dropwise on a water-air interface with an area of 50cm2 of a Langmuir film preparation instrument, after the chloroform is completely volatilized, the hexakis(triphenylphosphine)hexaphenylbenzene polycyclic aromatic compound molecular interface assembly film is maintained at an interfacial pressure of 10-30mN / m by slowly pushing the baffle, and the assembly film is transferred to one side of the polyacrylonitrile substrate support layer by vertical deposition transfer through the interface;

[0011] Step four: the operation of step three is repeated for 3-5 times, and finally a hexakis(triphenylphosphine)hexaphenylbenzene polycyclic aromatic compound film with uniform thickness and integrity is formed.

[0012] Preferably, the washing method of the polyacrylonitrile substrate in step one is ultrasonic cleaning in deionized water for 3-5min, and the drying method is drying in a vacuum drying box at 60℃ for 10-15min.

[0013] Preferably, the preparation method of the hexakis(triphenylphosphine)hexaphenylbenzene polycyclic aromatic compound in step three comprises the following steps:

[0014] S1, 1.0 eq. of 4-bromobenzaldehyde, 2.0 eq. of 2-ethylpyridine and 2.5 eq. of NH4OH were stirred in ethanol at room temperature for 4 hours, and then recrystallized from hot ethanol to obtain 4'-(4-bromophenyl)-2,2':6',2"-terpyridine, denoted as compound 1;

[0015] S2, 1 eq. of compound 1 was put into a Schlenk tube, 1.1 eq. of bis(pinacolato)diboron, 0.03 eq. of Pd(dppf)Cl2 and 3.0 eq. of KOAc in dimethyl sulfoxide were added, and stirring was carried out at 80°C for 6 hours, and then the product was separated and dried to obtain 4'-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-2,2':6',2"-terpyridine, denoted as compound 2;

[0016] S3, 9.0 eq. of compound 2, 1.0 eq. of hexabromobenzene, 15 eq. of Na2CO3 and toluene were put into an oven-dried Schlenk tube under nitrogen atmosphere, degassed through 3-5 cycles of freeze-pump-thaw, 0.2 eq. of Pd(dppf)Cl2 was added, and degassing was repeated for 3-5 times, and then stirring was carried out at 110°C for 4 days, and then cooled to room temperature, extracted with dichloromethane, suction filtered and dried, and then the obtained product was purified by using a recycling gel permeation chromatography to obtain a light purple product, i.e. hexakis(tripyridine)hexaphenylbenzene polycyclic aromatic hydrocarbon.

[0017] Preferably, the product separation and drying method in S2 is that the reaction mixture is extracted with 200 mL of toluene and 3×250 mL of water, the extract is dried with magnesium sulfate, and then the organic phase is collected by vacuum suction filtration, followed by rotary evaporation of the organic phase under reduced pressure to remove the toluene solvent, and finally vacuum drying at 50-60°C for 6-8 hours.

[0018] Preferably, the waiting time for complete evaporation of chloroform in step three is 15-30 min.

[0019] The present application also protects a multilayer condensed ring aromatic hydrocarbon organic film prepared by using the method as described above and its application in high-efficiency separation of N2 / SF6 mixed gas.

[0020] Compared with the prior art, the present application has the following technical effects:

[0021] The application provides a multilayer condensed ring aromatic (hexakis (tripyrrole) hexaphenylbenzene polycyclic aromatic hydrocarbon: TPY) organic film based on a Langmuir-Blodgett assembly technology, realizes ordered accumulation of condensed ring aromatic molecules, and can quickly construct a multilayer organic film system with a regular structure, adjustable structure and accurately controlled pore size at room temperature, the TPY molecule has a rigid condensed ring skeleton, and can form a highly ordered two-dimensional arrangement structure at an interface through pi-pi stacking, and after multilayer stacking, the size is close to the critical screening range of nitrogen and sulfur hexafluoride molecules, so that high-efficiency size rejection effect is realized; meanwhile, a poly[1-(trimethylsilyl)-1-propargyl] (PTMSP) intermediate layer is used to provide mechanical support, and the lifting flux and mechanical stability of the film are improved, the selectivity of the film in a nitrogen / sulfur hexafluoride mixed gas is as high as 155, the nitrogen flux can reach 138 GPU, and the film preparation process only needs 30 minutes at room temperature, and the film has the advantages of high performance, rapidness and low cost, effectively breaks through the limitations of traditional membrane materials in the "selectivity-flux trade-off", difficulty in controlling the structure of the membrane and high energy consumption in preparation, provides a new path for low-cost and scalable preparation of high-performance separation membranes, and has broad industrial application potential.

[0022] With the aid of the Langmuir-Blodgett technology, the number of layers and arrangement mode of the separation layer can be accurately controlled, and the uniformity of the film layer and the consistency of the screening channel are ensured. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a chemical structure diagram of the TPY molecule;

[0024] Figure 2 It is a schematic diagram of the preparation of the TPY film by the LB technology;

[0025] Figure 3 It is a schematic diagram of a gas separation performance test device designed for the TPY film;

[0026] Figure 4 It is an optical image of the TPY monolayer film prepared in Example 1 on a silicon wafer;

[0027] Figure 5 It is a SEM image of the TPY monolayer prepared in Example 1 on a copper QUANTIFOIL grid;

[0028] Figure 6 It is a relationship between the permeation performance of different gases through the TPY film prepared in Example 1 and the gas kinetic diameter;

[0029] Figure 7 It is an influence of the number of layers of the TPY film prepared in Example 4 on the N2 / SF6 separation performance;

[0030] Figure 8Effect of surface pressure on N2 / SF6 separation performance of TPY membrane prepared in Example 4

[0031] Figure 9 Effect of feed pressure on N2 / SF6 separation performance of TPY membrane prepared in Example 4

[0032] Figure 10 Separation performance of TPY membrane prepared in Example 4 under cycle test

[0033] Figure 11 Comparison of separation performance of different membranes on N2 / SF6 mixture DETAILED DESCRIPTION

[0034] The specific content of the present application is further explained in detail in the following combined with examples.

[0035] All chemical raw materials in the present application are commercially purchased without purification, wherein, polyacrylonitrile (PAN) is purchased from Sigma Aldrich (Shanghai) Trading Co., Ltd., product model: GF18031711.

[0036] Poly[1-(trimethylsilyl)-1-propyne] (PTMSP) is PTMST with purity greater than 99% purchased from Sigma Aldrich (Shanghai) Trading Co., Ltd., product model: 244481.

[0037] Example 1:

[0038] As shown in Figure 2 The present embodiment gives a preparation method of a multi-layer condensed ring aromatic hydrocarbon organic membrane, comprising the following steps:

[0039] Step one, place a square thin sheet of polyacrylonitrile with a side length of 2 cm in deionized water and ultrasonically clean for 3 min, then place it in a vacuum drying oven and dry at 60°C for 10 min;

[0040] Step two, drop 200 uL of a poly[1-(trimethylsilyl)-1-propyne] solution with a concentration of 1.25% w / v on the polyacrylonitrile substrate treated in step one, and spin coat to form a uniform support layer;

[0041] Step three, the following method is used to prepare hexakis(tripyridine)hexaphenylbenzene polycyclic aromatic hydrocarbon:

[0042] S1, 1.0 eq. of 4-bromobenzaldehyde, 2.0 eq. of 2-ethylpyridine and 2.5 eq. of NH4OH are stirred in ethanol at room temperature for 4 hours, then recrystallized from hot ethanol to obtain 4'-(4-bromophenyl)-2,2':6',2"-terpyridine, denoted as compound 1;

[0043] S2, in a Schlenk tube, 1 eq. of compound 1 was added, followed by 1.1 eq. of bis(pinacolato)diboron, 0.03 eq. of Pd(dppf)Cl2, and 3.0 eq. of KOAc in dimethylsulfoxide, and stirred at 80 °C for 6 hours. After the mixture was cooled, the reaction mixture was extracted with 200 mL of toluene and 3 x 250 mL of water. The extract was dried over magnesium sulfate, and the organic phase was collected by vacuum filtration. The organic phase was then rotary evaporated under reduced pressure to remove the toluene solvent. Finally, the product, 4'-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-2,2':6',2"- terpyridine, was obtained by vacuum drying at 50 °C for 1 hour, and was denoted as compound 2;

[0044] The specific operation of extracting the reaction mixture with 200 mL of toluene and 3 x 250 mL of water was as follows: the mixture was transferred to a separatory funnel, 200 mL of toluene and 250 mL of water were added, then the separatory funnel was shaken to mix the contents thoroughly, and the mixture was allowed to stand until the toluene and water phases were separated, with the toluene usually on top. Then, the lower aqueous phase was drained from the separatory funnel into a beaker, 250 mL of water was added to the toluene layer, and the mixing and standing steps were repeated. This process was repeated two more times, for a total of 750 mL of water. The toluene layers were combined into a single beaker to obtain the extract;

[0045] S3, in a nitrogen atmosphere, a dried Schlenk tube was charged with 9.0 eq. of compound 2, 1.0 eq. of hexabromobenzene, 15 eq. of Na2CO3, and toluene, degassed by a cycle of sub-cooling-pump-out-thaw, followed by the addition of 0.2 eq. of Pd(dppf)Cl2, and degassed again for 3 times. After stirring at 110 °C for 4 days, the mixture was cooled to room temperature, extracted with dichloromethane, filtered, and dried. The product was then purified by a cycle gel permeation chromatography to obtain a light purple product, hexakis(tripyridine)hexaphenylbenzene polycyclic aromatic hydrocarbon, as shown in Figure 1 ;

[0046] A 5 mg of the previously prepared hexakis(tripyridine)hexaphenylbenzene polycyclic aromatic hydrocarbon was dissolved in 5 mL of chloroform to prepare a solution with a concentration of 1 mg / mL. 25 uL of the solution was added dropwise to a Langmuir-Blodgett film preparation instrument with an area of 50 cm 2 The water-air interface, after waiting for 15 min for the chloroform to evaporate completely, the baffle was slowly pushed to maintain the hexakis(tripyridine)hexaphenylbenzene polycyclic aromatic hydrocarbon molecular interfacial assembly film at an interfacial pressure of 10 mN / m, and the assembly film was transferred to the side of the polyacrylonitrile substrate support layer by vertical interfacial deposition transfer;

[0047] Step four, repeat step three for 3 times, finally form a uniform and complete six (three pyridine) hexaphenylbenzene polycyclic aromatic membrane, after deposition, the membrane is placed in a room temperature drying environment for storage, to ensure the structure stability.

[0048] Example 2:

[0049] The present embodiment gives a preparation method of a multi-layer fused ring aromatic organic membrane, comprising the following steps:

[0050] Step one, place a square thin slice of polyacrylonitrile with a side length of 2 cm in deionized water for ultrasonic cleaning for 5 min, and then place it in a vacuum drying oven at 60°C for 15 min;

[0051] Step two, drop 250 uL of 1.25% w / v poly[1-(trimethylsilyl)-1-propyne] solution on the polyacrylonitrile substrate treated in step one, and spin-coat to form a uniform support layer;

[0052] Step three, prepare six (three pyridine) hexaphenylbenzene polycyclic aromatic membrane by the following method:

[0053] S1, stir 1.0 eq. of 4-bromobenzaldehyde, 2.0 eq. of 2-ethylpyridine and 2.5 eq. of NH4OH in ethanol at room temperature for 4 hours, then recrystallize from hot ethanol to obtain 4'-(4-bromophenyl)-2,2':6',2"-terpyridine, denoted as compound 1;

[0054] S2, put 1 eq. of compound 1 into a Schlenk tube, add 1.1 eq. of bis(pinacolato)diboron, 0.03 eq. of Pd(dppf)Cl2 and 3.0 eq. of KOAc in dimethyl sulfoxide, stir at 80°C for 6 hours, after the mixture is cooled, extract the reaction mixture with 200 mL of toluene and 3×250 mL of water, dry the extract with magnesium sulfate, then collect the organic phase by vacuum filtration, then perform rotary evaporation on the organic phase under reduced pressure, evaporate the toluene solvent, and finally dry at 60°C under vacuum for 8 hours to obtain 4'-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-2,2':6',2"-terpyridine, denoted as compound 2;

[0055] S3, under nitrogen atmosphere, 9.0 eq. of compound 2, 1.0 eq. of hexa bromobenzene, 15 eq. of Na2CO3 and toluene were charged into an oven-dried Schlenk tube, after 5 freeze-pump-thaw cycles degassing, 0.2 eq. of Pd(dppf)Cl2 was added, and after 5 more degassing cycles, the mixture was stirred at 110 °C for 4 days, then cooled to room temperature, extracted with dichloromethane, filtered and dried, the product was purified by recycling gel permeation chromatography to obtain a light purple product, hexakis(tripyridine)hexaphenylbenzene polycyclic arene;

[0056] A 5 mg of the previously prepared hexakis(tripyridine)hexaphenylbenzene polycyclic arene was dissolved in 5 mL of chloroform to make a solution with a concentration of 1 mg / mL, and 30 uL of the solution was dropped onto the Langmuir film preparation instrument with an area of 50 cm 2 The water-air interface was prepared, and after 30 min of waiting for the chloroform to completely volatilize, the baffle was slowly pushed to maintain the hexakis(tripyridine)hexaphenylbenzene polycyclic arene molecular interface assembly film at an interfacial pressure of 30 mN / m, and the assembly film was transferred to one side of the polyacrylonitrile substrate support layer by vertical interfacial deposition transfer;

[0057] Step four, repeat step three 5 times to form a uniform and complete hexakis(tripyridine)hexaphenylbenzene polycyclic arene film, after deposition, the film is placed in a room temperature drying environment for storage to ensure structural stability.

[0058] Example 3:

[0059] The present embodiment provides a method for preparing a multilayer condensed ring arene organic film, comprising the following steps:

[0060] Step one, a square sheet of polyacrylonitrile substrate with a side length of 2 cm was ultrasonically cleaned in deionized water for 4 min, and then dried in a vacuum drying oven at 60 °C for 12 min;

[0061] Step two, 200 uL of a 1.25% w / v solution of poly[1-(trimethylsilyl)-1-propyne] was dropped onto the polyacrylonitrile substrate treated in step one, and spin-coated to form a uniform support layer;

[0062] Step three, hexakis(tripyridine)hexaphenylbenzene polycyclic arene was prepared by the following method:

[0063] S1, 1.0 eq. of 4-bromobenzaldehyde, 2.0 eq. of 2-ethylpyridine and 2.5 eq. of NH4OH were stirred in ethanol at room temperature for 4 hours, and then recrystallized from hot ethanol to obtain 4'-(4-bromophenyl)-2,2':6',2"-terpyridine, denoted as compound 1;

[0064] S2, 1 eq. of compound 1 was put into a Schlenk tube, then 1.1 eq. of bis(pinacolato)diboron, 0.03 eq. of Pd(dppf)Cl2 and 3.0 eq. of KOAc in dimethyl sulfoxide were added, and the mixture was stirred at 80℃ for 6 hours. After the mixture was cooled, the reaction mixture was extracted with 200 mL of toluene and 3x250 mL of water. The extracted solution was dried over magnesium sulfate, and then the organic phase was collected by vacuum filtration. Subsequently, the organic phase was rotary evaporated under reduced pressure to remove the toluene solvent, and finally, the product was dried under vacuum at 55℃ for 7 hours to obtain 4'-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-2,2':6',2"-terpyridine, denoted as compound 2;

[0065] S3, 9.0 eq. of compound 2, 1.0 eq. of hexabromobenzene, 15 eq. of Na2CO3 and toluene were put into an oven-dried Schlenk tube under nitrogen atmosphere, and the mixture was degassed by 4 cycles of freeze-pump-thaw. Then, 0.2 eq. of Pd(dppf)Cl2 was added, and the mixture was degassed again for 4 cycles. After the mixture was stirred at 110℃ for 4 days and then cooled to room temperature, the product was extracted with dichloromethane, filtered and dried, and then purified by recycling gel permeation chromatography to obtain a light purple product, i.e., hexakis(tripyridine)hexaphenylbenzene polycyclic arene;

[0066] A solution of 5 mg of the previously prepared hexakis(tripyridine)hexaphenylbenzene polycyclic arene in 5 mL of chloroform was prepared to have a concentration of 1 mg / mL. 28 uL of the solution was added dropwise to a Langmuir film apparatus with an area of 50 cm 2 After waiting for 20 min for the chloroform to completely evaporate, the baffle was slowly pushed to maintain the hexakis(tripyridine)hexaphenylbenzene polycyclic arene molecular interfacial assembly film at an interfacial pressure of 20 mN / m, and the assembly film was transferred to one side of the polyacrylonitrile substrate support layer by vertical interfacial deposition transfer.

[0067] Step four, the operation of step three was repeated 4 times to finally form a hexakis(tripyridine)hexaphenylbenzene polycyclic arene film with uniform thickness and integrity. After the deposition was completed, the film was stored in a room temperature drying environment to ensure structural stability.

[0068] Example 4:

[0069] The present embodiment provides a method for preparing a multilayer condensed arene organic film, comprising the following steps:

[0070] Step one, a square thin sheet of polyacrylonitrile with a side length of 2 cm was ultrasonically cleaned in deionized water for 3-5 min, and then dried in a vacuum drying oven at 60℃ for 12 min.

[0071] Step two, 200-250 uL of 1.25% w / v poly[1-(trimethylsilyl)-1-propyne] solution was dropped on the polyacrylonitrile substrate treated in step one, and spin-coated to form a uniform support layer;

[0072] Step three, the following method was used to prepare hexakis(tripyridine)hexaphenylbenzene polycyclic aromatic hydrocarbon:

[0073] S1, 1.0 eq. of 4-bromobenzaldehyde, 2.0 eq. of 2-ethylpyridine and 2.5 eq. of NH4OH were stirred in ethanol at room temperature for 4 hours, and then recrystallized from hot ethanol to obtain 4'-(4-bromophenyl)-2,2':6',2"-terpyridine, denoted as compound 1;

[0074] S2, 1 eq. of compound 1 was put into a Schlenk tube, and then 1.1 eq. of bis(pinacolato)diboron, 0.03 eq. of Pd(dppf)Cl2 and 3.0 eq. of KOAc in dimethyl sulfoxide were added, and stirred at 80°C for 6 hours. After the mixture was cooled, the reaction mixture was extracted with 200 mL of toluene and 3×250 mL of water. The extracted solution was dried over magnesium sulfate, and then the organic phase was collected by vacuum filtration. Then, the organic phase was rotary evaporated under reduced pressure to remove the toluene solvent, and finally dried at 60°C under vacuum for 8 hours to obtain 4'-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-2,2':6',2"-terpyridine, denoted as compound 2;

[0075] S3, 9.0 eq. of compound 2, 1.0 eq. of hexabromobenzene, 15 eq. of Na2CO3 and toluene were put into an oven-dried Schlenk tube, and degassed by 5 cycles of freeze-pump-thaw. Then, 0.2 eq. of Pd(dppf)Cl2 was added, and degassed again for 5 cycles. After stirring at 110°C for 4 days and cooling to room temperature, the product was extracted with dichloromethane, filtered and dried, and then purified by recycling gel permeation chromatography to obtain a light purple product, which was hexakis(tripyridine)hexaphenylbenzene polycyclic aromatic hydrocarbon;

[0076] 5 mg of the previously prepared hexakis(tripyridine)hexaphenylbenzene polycyclic aromatic hydrocarbon was dissolved in 5 mL of chloroform to prepare a solution with a concentration of 1 mg / mL. 30 uL of the solution was dropped on a Langmuir film preparation instrument with an area of 50 cm 2 The water-air interface was prepared, and 30 min was waited for the chloroform to completely volatilize. Then, the baffle was slowly pushed to maintain the hexakis(tripyridine)hexaphenylbenzene polycyclic aromatic hydrocarbon molecular interfacial assembly film at an interfacial pressure of 25 mN / m, and the assembly film was transferred to one side of the polyacrylonitrile substrate support layer by interfacial vertical deposition transfer.

[0077] Step four, repeat step three for 4 times, finally form a uniform and complete six (three pyridine) hexaphenylbenzene polycyclic aromatic hydrocarbon film, after deposition, the film is placed in room temperature drying environment for storage, ensure the structure stability.

[0078] Figure 3 The schematic diagram of gas separation performance test device designed for TPY film;

[0079] Figure 4 The optical image of TPY single layer film prepared for example 1 on silicon wafer; as shown, the film is transferred to the silicon wafer, the optical image of TPY film shows a flat morphology. Figure 4

[0080] Figure 5 The SEM image of TPY single layer film prepared for example 1 on copper QUANTIFOIL grid; as shown, TPY film on copper QUANTIFOIL grid shows good mechanical strength, can stably cross the hole with a diameter of at least 2μm, maintain the integrity of single layer structure; Figure 5

[0081] The relationship between permeation performance of different gases through TPY film prepared for example 1 and gas kinetic diameter, confirm that there is a huge difference in single gas permeability of N2 and SF6; Figure 6

[0082] The influence of layer number of TPY film prepared for example 4 on N2 / SF6 separation performance; Figure 7 The influence of surface pressure on N2 / SF6 separation performance of TPY film prepared for example 4; as shown, Figure 8 and Figure 7 It can be seen that when the layer number is only 4 layers and the surface pressure is 25mN / m, the film shows relatively high N2 permeability (138GPU) and moderate N2 / SF6 selectivity (155). Figure 8

[0083] The influence of feed pressure on N2 / SF6 separation performance of TPY film prepared for example 4; as shown, Figure 9 It can be seen that TPY film shows good pressure stability in N2 / SF6 separation. Figure 9

[0084] The separation performance of TPY film prepared for example 4 under cycle test; as shown, Figure 10 It can be seen that after long time cycle, TPY film still maintains excellent N2 / SF6 separation performance. Figure 10

[0085] Figure 11 ​​For comparison of separation performance of different membranes to N2 / SF6 mixture, the membrane material prepared in the application shows higher permeation rate in N2 permeability, while maintaining higher N2 selectivity, showing excellent separation performance.

Claims

1. A method for preparing a multilayer condensed ring aromatic hydrocarbon organic film, characterized in that: The following steps are involved: Step 1: Clean and dry a 2 cm square sheet of polyacrylonitrile substrate; Step 2: dropwise add 200-250 μL of a 1.25% w / v poly[1-(trimethylsilyl)-1-propyne] solution onto the polyacrylonitrile substrate treated in step 1, and spin-coat to form a uniform support layer; Step 3: Dissolve the pre-prepared hexa(tripyridine)hexaphenylbenzene polycyclic aromatic hydrocarbons in chloroform to prepare a solution with a concentration of 1 mg / mL, and drop 25-30 μL of the solution onto a 50 cm2 Langmuir film preparation instrument. 2 At the water-air interface, after the chloroform is completely evaporated, the baffle is slowly pushed to maintain the interface assembly film of hexa(tripyridine)hexaphenylbenzene polycyclic aromatic hydrocarbon molecules at an interface pressure of 10 to 30 mN / m, and the assembled film is transferred to one side of the polyacrylonitrile substrate support layer by vertical deposition transfer at the interface; Step 4: Repeat the operation of step 3 for 3 to 5 times to finally form a hexa(tripyridine)hexaphenylbenzene polycyclic aromatic hydrocarbon film with uniform thickness and integrity.

2. The method for preparing a multilayer condensed-ring aromatic hydrocarbon organic film according to claim 1, wherein: The polyacrylonitrile substrate in step 1 is cleaned by ultrasonic cleaning in deionized water for 3 to 5 minutes, and dried in a vacuum drying oven at 60° C. for 10 to 15 minutes.

3. The method for preparing a multilayer condensed-ring aromatic hydrocarbon organic film according to claim 1, wherein: The preparation method of the hexa(tripyridine)hexaphenylbenzene polycyclic aromatic hydrocarbons described in step 3 comprises the following steps: S1. 1.0 eq. of 4-bromobenzaldehyde, 2.0 eq. of 2-ethylpyridine, and 2.5 eq. of NH4OH were stirred in ethanol at room temperature for 4 hours, and then recrystallized from hot ethanol to obtain 4'-(4-bromophenyl)-2,2':6',2"-terpyridine, recorded as compound 1; S2. Place 1 eq. of compound 1 in a Schlenk tube, then add 1.1 eq. of bis(pinacolato)diboron, 0.03 eq. of Pd(dppf)Cl2, and 3.0 eq. of KOAc in dimethyl sulfoxide, and stir at 80°C for 6 hours. After the mixture is cooled, separate and dry the product to obtain 4'-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-2,2':6',2"-terpyridine, recorded as compound 2. S3. Under a nitrogen atmosphere, 9.0 eq. of compound 2, 1.0 eq. of hexabromobenzene, 15 eq. of Na2CO3 and toluene were charged into a dried Schlenk tube. After degassing through 3 to 5 freeze-pump-thaw cycles, 0.2 eq. of Pd(dppf)Cl2 was added, and the degassing operation was repeated 3 to 5 times. The mixture was then stirred at 110°C for 4 days and then cooled to room temperature. The mixture was extracted with dichloromethane, filtered and dried, and then purified by cyclic gel permeation chromatography to obtain a light purple product, which was hexa(tripyridine)hexaphenylbenzene polycyclic aromatic hydrocarbon.

4. The method for preparing a multilayer condensed-ring aromatic hydrocarbon organic film according to claim 3, wherein: The product separation and drying method described in S2 is to extract the reaction mixture with 200 mL of toluene and 3×250 mL of water, dry the extract over magnesium sulfate, collect the organic phase by vacuum filtration, then perform reduced pressure rotary evaporation on the organic phase to remove the toluene solvent, and finally vacuum dry at 50-60°C for 6-8 hours.

5. The method for preparing a multi-layer condensed-ring aromatic hydrocarbon organic film according to claim 1, wherein: The waiting time for the chloroform described in step 3 to completely evaporate is 15 to 30 minutes.

6. A multilayer condensed-ring aromatic hydrocarbon organic film prepared by the method according to any one of claims 1 to 5.

7. Use of the multilayer condensed-ring aromatic hydrocarbon organic membrane as claimed in claim 6 in the efficient separation of N2 / SF6 mixed gas.

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