Membrane casting solution, permeable membrane and application of permeable membrane in halogenated olefin separation

Abstract

The invention relates to the technical field of membrane separation, and provides a membrane casting solution, a permeable membrane and application of the permeable membrane in halogenated olefin separation, and the membrane casting solution comprises siloxane, a cross-linking agent and a cross-linking catalyst; the siloxane is siloxane with a nitrogen-containing borane branched chain. The permeable membrane comprises a bottom membrane and a silicone rubber membrane layer positioned on the bottom membrane; the silicone rubber film layer is prepared by carrying out cross-linking reaction on the film casting solution. The permeable membrane provided by the invention has a relatively good adsorption effect on chloropropene, so that the recovery efficiency of chloropropene in the separation process of chloropropene and nitrogen is improved.

Description

Technical Field

[0001] The invention relates to the technical field of membrane separation, in particular to a membrane casting solution, a permeable membrane and applications thereof in the separation of halogenated olefins. Background Art

[0002] 3-Chloropropene (AC, hereinafter referred to as chloropropene) is an important industrial raw material for the preparation of epichlorohydrin (ECH) by hydrogen peroxide method. The tail gas produced by the hydrogen peroxide method for preparing epichlorohydrin contains about 40,000 ppm of gaseous chloropropene. Separating and recovering these chloropropenes can reduce raw material loss, reduce costs, and improve the cleanliness of the epoxidation process.

[0003] The methods commonly used in industry to recover allyl chloride are mainly adsorption and condensation. The adsorption method mainly uses adsorbents such as alkali, activated carbon, and resin to adsorb and recover allyl chloride gas molecules. It requires regular regeneration or replacement of the adsorbent, and the recovery rate is not high and the selectivity is poor. The condensation method condenses and recovers allyl chloride gas, which consumes more energy, and the recovered allyl chloride needs to be purified before use. The membrane separation method has the advantages of simple process, high permeability, and good selectivity, and is one of the development trends of the tail gas recovery process for allyl chloride.

[0004] The selection of membrane materials is the key to membrane separation. Since the tail gas flow of allyl chloride is large and the contact time between allyl chloride and the membrane surface is short, it is necessary to select a membrane material with a large gas permeation rate to ensure the recovery efficiency of allyl chloride.

[0005] Therefore, it is necessary to develop a new membrane material for the recovery of allyl chloride. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a casting solution, a permeable membrane and its application in the separation of halogenated olefins. By grafting nitrogen-containing borane on the side chain of siloxane, the polarized BC bonds and BN bonds make the electron-rich N on the N-containing group have a better adsorption effect on allyl chloride, thereby improving the recovery efficiency of allyl chloride.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a casting solution, which includes siloxane, a cross-linking agent and a cross-linking catalyst; the siloxane is a siloxane having nitrogen-containing borane side chains.

[0009] It is worth noting that silicone rubber membranes are mainly a type of siloxane polymer. Due to the high degree of rotational freedom of the silicon-oxygen bonds between siloxanes, silicone rubber membranes have good toughness and therefore have good permeability to gases. Siloxane has good plasticity, and the selectivity of silicone rubber membranes for specific substances can be improved by adding functional groups or adding complexes to the silane main chain to improve the separation effect of the membrane. The present invention significantly improves the adsorption efficiency of the membrane for allyl chloride by modifying the side chains of siloxane, thereby improving the separation efficiency of allyl chloride and nitrogen.

[0010] The nitrogen-containing borane side chain in the present invention is very critical, and the electron-rich N due to polarization can enhance the adsorption effect of the silicone rubber membrane on allyl chloride.

[0011] Preferably, the siloxane having nitrogen-containing borane side chains is obtained by modifying nitrogen-containing borane with olefin-containing siloxane.

[0012] In addition, the present invention has found that it is difficult to obtain the expected separation effect by modifying the silicon-oxygen bond in siloxane, because the formed silicon-boron bond is relatively fragile and easily broken after long-term contact with acidic substances such as allyl chloride. However, by modifying the alkenyl group of olefin-containing siloxane to form a BC bond, the adsorption effect on allyl chloride can be improved.

[0013] Preferably, the modification reaction comprises: mixing nitrogen-containing borane, olefin-containing siloxane and an organic solvent, performing static polymerization, and drying to obtain siloxane with nitrogen-containing borane side chains. The static polymerization temperature is 20-30°C, for example, 20°C, 22°C, 24°C, 26°C, 28°C or 30°C, etc., and the static polymerization time is 0.5-2h, for example, 0.5h, 0.7h, 0.9h, 1h, 1.2h, 1.4h, 1.5h, 1.7h, 1.9h or 2h, etc., but not limited to the listed values, and other values ​​not listed in this range are also applicable; the drying temperature is 50-80°C, for example, 50°C, 54°C, 57°C, 60°C, 64°C, 67°C, 70°C, 74°C, 77°C or 80°C, etc., but not limited to the listed values, and other values ​​not listed in this range are also applicable. The organic solvent includes any one of tetrahydrofuran, dioxane or methyl tert-butyl ether or a combination of at least two of them, wherein typical but non-limiting combinations are a combination of tetrahydrofuran and dioxane, a combination of methyl tert-butyl ether and dioxane, and a combination of tetrahydrofuran and methyl tert-butyl ether.

[0014] Preferably, the nitrogen-containing borane comprises dimethylaminoborane and / or 4-dimethylaminopyridineborane.

[0015] After many studies and explorations, the present invention has found that the above two nitrogen-containing boranes have a better separation effect on chloropropylene after polymerization with olefin-containing siloxanes. On the one hand, when the chain length of the alkyl group is relatively long, it is easy to weaken the interaction between boron and nitrogen, so that the adsorption capacity of the final permeable membrane to halogenated olefins decreases; on the other hand, the boron-nitrogen bond of the above two nitrogen-containing boranes is highly stable and can exist stably during the modification reaction, ensuring the modification effect.

[0016] Preferably, the mass ratio of the nitrogen-containing borane to the olefin-containing siloxane is (0.005-0.05):1, for example, it can be 0.005:1, 0.006:1, 0.01:1, 0.02:1, 0.025:1, 0.03:1, 0.035:1, 0.04:1, 0.045:1 or 0.05:1, etc.

[0017] Preferably, the olefin-containing siloxane comprises any one or a combination of at least two of methylvinylsiloxane, acrylsiloxane or phenylvinylsiloxane, wherein typical but non-limiting combinations are a combination of methylvinylsiloxane and acrylsiloxane, a combination of phenylvinylsiloxane and acrylsiloxane, and a combination of methylvinylsiloxane and phenylvinylsiloxane.

[0018] Preferably, the molecular weight of the olefin-containing siloxane is 20,000 to 50,000, for example, 20,000, 23,300, 26,600, 30,000, 33,300, 36,600, 40,000, 43,300, 46,000 or 50,000, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0019] Preferably, the vinyl content of the methyl vinyl siloxane is 1 to 10%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0020] In the present invention, the vinyl content determines the number of modification sites in the modification process. By controlling the vinyl content within the above range, it is possible to ensure the modification effect while avoiding the situation where some modification sites are bound due to the enhancement of intramolecular cross-chain boron-nitrogen interactions.

[0021] Preferably, the crosslinking agent is a hydroxyl-containing siloxane. Preferably, the crosslinking agent includes any one of polymethyl hydrogen siloxane, polyphenyl hydrogen siloxane or polymethyl phenyl hydrogen siloxane, or a combination of at least two thereof, wherein a typical but non-limiting combination is a combination of polymethyl hydrogen siloxane and polyphenyl hydrogen siloxane, a combination of polymethyl phenyl hydrogen siloxane and polyphenyl hydrogen siloxane, and a combination of polymethyl hydrogen siloxane and polymethyl phenyl hydrogen siloxane.

[0022] The present invention preferably uses polymethyl hydrogen siloxane as a crosslinking agent, which can provide appropriate steric hindrance and has a better crosslinking effect.

[0023] Preferably, the mass ratio of siloxane, crosslinking agent and crosslinking catalyst in the casting solution is 1:(0.01-0.05):(0.005-0.01), wherein the mass fraction of the crosslinking agent can be, for example, 0.01, 0.015, 0.019, 0.024, 0.028, 0.033, 0.037, 0.042, 0.046 or 0.05, etc.; the mass fraction of the crosslinking catalyst can be, for example, 0.005, 0.006, 0.007, 0.008, 0.009 or 0.01, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0024] Preferably, the cross-linking catalyst comprises a Karstedt catalyst and / or chloroplatinic acid, preferably a Karstedt catalyst.

[0025] Preferably, the content of the cross-linking catalyst in the casting solution is 500-4500 ppm, for example, it can be 500 ppm, 550 ppm, 600 ppm, 700 ppm, 800 ppm, 1000 ppm, 1500 ppm, 1830 ppm, 2160 ppm, 2500 ppm, 2830 ppm, 3160 ppm, 3500 ppm, 3830 ppm, 4160 ppm or 4500 ppm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0026] Preferably, the solvent in the casting solution includes any one of n-hexane, cyclohexane or dichloromethane or a combination of at least two of them, wherein typical but non-limiting combinations are a combination of n-hexane and cyclohexane, a combination of dichloromethane and cyclohexane, and a combination of n-hexane and dichloromethane.

[0027] The present invention has no special restrictions on the preparation method of the casting solution, and the preparation process for the casting solution well known to those skilled in the art can be used. For example, siloxane, a crosslinking agent and a crosslinking catalyst are dissolved in a solvent, and the casting solution is obtained by standing and reacting. The standing temperature is 20 to 30°C, for example, it can be 20°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C or 30°C, etc., but it is not limited to the listed values, and other values ​​not listed in this range are also applicable; the standing time is 0.5 to 2h, for example, it can be 0.5h, 0.7h, 0.9h, 1h, 1.2h, 1.4h, 1.5h, 1.7h, 1.9h or 2h, etc., but it is not limited to the listed values, and other values ​​not listed in this range are also applicable.

[0028] In a second aspect, the present invention provides a permeable membrane, comprising a base membrane and a silicone rubber membrane layer located on the base membrane; the silicone rubber membrane layer is obtained by cross-linking the casting solution described in the first aspect.

[0029] The permeable membrane provided by the present invention can specifically adsorb allyl chloride, thereby realizing efficient separation of allyl chloride and nitrogen, and has broad application prospects.

[0030] Preferably, the base film is made of polyimide and / or polysulfone.

[0031] Preferably, the thickness of the base film is 5 to 20 μm, for example, it can be 5 μm, 7 μm, 9 μm, 10 μm, 12 μm, 14 μm, 15 μm, 17 μm, 19 μm or 20 μm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0032] Preferably, the total thickness of the permeable membrane is 10 to 40 μm, for example, 10 μm, 14 μm, 17 μm, 20 μm, 24 μm, 27 μm, 30 μm, 34 μm, 37 μm or 40 μm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0033] Preferably, the separation coefficient of the permeable membrane for allyl chloride and nitrogen is 34 to 67, for example, 34, 38, 42, 45, 49, 53, 56, 60, 64 or 67, but is not limited to the listed values, and other values ​​not listed in the range are also applicable. The separation coefficient α is the ratio of the permeability of allyl chloride to nitrogen.

[0034] The present invention has no special restrictions on the preparation method of the permeable membrane, and the preparation process for the permeable membrane well known to those skilled in the art can be used. For example, the preparation method of the permeable membrane includes: setting the casting liquid on the base film and drying to obtain the permeable membrane. The drying temperature can be, for example, 60 to 80°C, for example, 60°C, 63°C, 65°C, 67°C, 69°C, 72°C, 74°C, 76°C, 78°C or 80°C, but is not limited to the listed values, and other values ​​not listed in the range are also applicable; the drying time can be, for example, 6 to 12h, for example, 6h, 6.7h, 7.4h, 8h, 8.7h, 9.4h, 10h, 10.7h, 11.4h or 12h, but is not limited to the listed values, and other values ​​not listed in the range are also applicable.

[0035] The present invention has no special limitation on the drying in the above process. Any device and method known to those skilled in the art for drying can be used, and can also be adjusted according to the actual process. For example, it can be air drying, vacuum drying or oven drying, or a combination of different methods, preferably oven drying.

[0036] In a third aspect, the present invention provides a use of the permeable membrane described in the first aspect in the separation of halogenated olefins.

[0037] The permeable membrane provided by the present invention can specifically adsorb halogenated olefins during the separation process of halogenated olefins and nitrogen, thereby realizing efficient separation of halogenated olefins from other gases, especially high separation efficiency of allyl chloride from nitrogen, and can be used for effective recovery of allyl chloride in tail gas.

[0038] Preferably, the halogenated olefin comprises allyl chloride and / or allyl dichloride.

[0039] Compared with the prior art, the present invention has at least the following beneficial effects:

[0040] (1) The casting solution provided by the present invention adopts siloxane with nitrogen-containing borane side chains, and then cross-links with a cross-linking agent to form a silicone rubber membrane. The electron-rich organic N in the nitrogen-containing borane side chains can enhance the adsorption effect of the silicone rubber membrane on allyl chloride due to polarization, thereby forming a permeable membrane with excellent separation efficiency for separating allyl chloride and nitrogen, wherein the separation coefficient α for allyl chloride and nitrogen is greater than 20, preferably greater than 25, and more preferably greater than 30;

[0041] (2) The permeable membrane provided by the present invention has good selectivity for separation of allyl chloride / nitrogen in allyl chloride tail gas, and can be used for effective recovery of allyl chloride in tail gas; and the process method of the present invention is simple, has the potential for industrialization, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is the nuclear magnetic resonance boron spectrum of the permeable membrane prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0043] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0044] Example 1

[0045] This embodiment provides a casting solution, and the preparation of the casting solution includes: taking 0.50g of dimethylaminoborane and dissolving it in 2.5g of tetrahydrofuran, and evenly mixing it with 10.03g of methylvinylsiloxane with a weight average molecular weight of 43000 (vinyl content of 5%), standing it at 20°C for 1h, and then drying it at 50°C to obtain siloxane with nitrogen-containing borane side chains;

[0046] In 100 g of n-hexane, 10.54 g of the siloxane having nitrogen-borane side chains, 0.11 g of polymethyl hydrogen siloxane (molecular weight of 3200), and 0.08 g of Karstedt catalyst were added, and the mixture was allowed to react at 30° C. for 0.5 h to obtain the casting solution.

[0047] Example 2

[0048] This embodiment provides a casting solution, and the preparation of the casting solution includes: taking 0.21g of dimethylaminoborane and dissolving it in 4.1g of tert-butyl methyl ether, and evenly mixing it with 10.01g of methylvinylsiloxane with a weight average molecular weight of 20000 (vinyl content is 1%), standing at 24°C for 0.5h, and then drying at 80°C to obtain siloxane with nitrogen-containing borane side chains;

[0049] 10.22 g of the siloxane having nitrogen-borane side chains, 0.40 g of polymethyl hydrogen siloxane (molecular weight of 3200), and 0.10 g of Karstedt catalyst were added to 100 g of cyclohexane, and the mixture was allowed to react at 20° C. for 0.5 h to obtain the casting solution.

[0050] Example 3

[0051] This embodiment provides a casting solution, and the preparation of the casting solution includes: taking 0.053g of dimethylaminoborane and dissolving it in 1.0g of dioxane, and mixing it evenly with 10.01g of methylvinylsiloxane with a weight average molecular weight of 41000 (vinyl content of 10%), standing it at 24°C for 0.5h, and then drying it at 80°C to obtain siloxane with nitrogen-containing borane side chains;

[0052] In 100 g of dichloromethane, 10.06 g of the siloxane having nitrogen-borane side chains, 0.50 g of polymethyl hydrogen siloxane (molecular weight of 3200), and 0.10 g of Karstedt catalyst were added, and the mixture was allowed to react at 30° C. for 2 h to obtain the casting solution.

[0053] Example 4

[0054] This embodiment provides a casting solution, and the preparation of the casting solution includes: taking 0.13g of dimethylaminoborane and dissolving it in 2.0g of tetrahydrofuran, and mixing it evenly with 10.02g of methylvinylsiloxane with a weight average molecular weight of 35000 (vinyl content of 5.5%), standing it at 26°C for 0.5h, and then drying it at 50°C to obtain siloxane with nitrogen-containing borane side chains;

[0055] In 100 g of dichloromethane, 10.15 g of the siloxane having nitrogen-borane side chains, 0.43 g of polymethyl hydrogen siloxane (molecular weight of 3200), and 0.10 g of Karstedt catalyst were added, and the mixture was allowed to react at 20° C. for 2 hours to obtain the casting solution.

[0056] Example 5

[0057] The present embodiment provides a casting solution, and the preparation of the casting solution includes: taking 0.42g of 4-dimethylaminopyridine borane and dissolving it in 2.3g of tetrahydrofuran, and mixing it evenly with 10.01g of methyl vinyl siloxane with a weight average molecular weight of 25000 (vinyl content of 6.0%), standing at 28°C for 2h, and then drying at 80°C to obtain siloxane with nitrogen-containing borane side chains;

[0058] In 100 g of n-hexane, 10.00 g of the siloxane having nitrogen-borane side chains, 0.12 g of polymethyl hydrogen siloxane (molecular weight of 3400), and 0.05 g of Karstedt catalyst were added, and the mixture was allowed to react at 30° C. for 2 h to obtain the casting solution.

[0059] Example 6

[0060] This embodiment provides a casting solution, and the preparation of the casting solution includes: taking 0.35g of 4-dimethylaminopyridine borane and dissolving it in 1.8g of tetrahydrofuran, and mixing it evenly with 9.97g of methyl vinyl siloxane with a weight average molecular weight of 34000 (vinyl content of 2.3%), standing at 30°C for 1h, and then drying at 80°C to obtain siloxane with nitrogen-containing borane side chains;

[0061] In 100 g of cyclohexane, 10.32 g of the siloxane having nitrogen-borane side chains, 0.22 g of polymethyl hydrogen siloxane (molecular weight of 3200), and 0.06 g of Karstedt catalyst were added, and the mixture was allowed to react at 30° C. for 2 hours to obtain the casting solution.

[0062] Example 7

[0063] This embodiment provides a casting solution, and the preparation of the casting solution includes: taking 0.12g of 4-dimethylaminopyridine borane and dissolving it in 1.1g of tert-butyl methyl ether, and evenly mixing it with 10.00g of methyl vinyl siloxane with a weight average molecular weight of 50000 (vinyl content of 3.5%), standing at 20°C for 0.5h, and then drying at 80°C to obtain siloxane with nitrogen-containing borane side chains;

[0064] 10.12 g of the siloxane having nitrogen-borane side chains, 0.48 g of polymethyl hydrogen siloxane (molecular weight 3200), and 0.09 g of Karstedt catalyst were added to 100 g of cyclohexane, and the mixture was allowed to react at 30° C. for 0.5 h to obtain the casting solution.

[0065] Example 8

[0066] This embodiment provides a casting solution, and the preparation of the casting solution includes: taking 0.23g of 4-dimethylaminopyridine borane and dissolving it in 4.5g of dioxane, and mixing it evenly with 9.98g of methyl vinyl siloxane with a weight average molecular weight of 47000 (vinyl content of 6.3%), standing at 28°C for 2h, and then drying at 60°C to obtain siloxane with nitrogen-containing borane side chains;

[0067] In 100 g of n-hexane, 10.20 g of the siloxane having nitrogen-containing borane side chains, 0.35 g of polymethyl hydrogen siloxane (molecular weight of 3200), and 0.06 g of Karstedt catalyst were added, and the mixture was allowed to react at 25° C. for 1 hour to obtain the casting solution.

[0068] Example 9

[0069] This embodiment provides a casting solution, which is the same as that of Embodiment 1 except that dimethylaminoborane is replaced by N-ethylaminoborane, and will not be described in detail here.

[0070] Example 10

[0071] This embodiment provides a casting solution, which is the same as that of Embodiment 1 except that dimethylaminoborane is replaced by diaminodihydroborane, and will not be described in detail here.

[0072] Embodiment 11

[0073] This embodiment provides a casting solution, which is the same as that of Embodiment 1 except that the vinyl content of the methyl vinyl siloxane is 15%, and will not be described in detail here.

[0074] Example 12

[0075] This embodiment provides a casting solution. The casting solution is the same as that of Embodiment 1 except that the vinyl content of the methyl vinyl siloxane is 0.5%, and details thereof will not be described again.

[0076] Embodiment 13

[0077] This embodiment provides a casting solution, which is the same as that of Embodiment 1 except that methylvinylsiloxane is replaced by dimethylsiloxane, and thus will not be described in detail herein.

[0078] Embodiment 14

[0079] This embodiment provides a casting solution, which is the same as that of Embodiment 1 except that polymethyl hydrogen siloxane is replaced by polyphenyl hydrogen siloxane (molecular weight is 6600), and will not be described in detail here.

[0080] Embodiment 15

[0081] This embodiment provides a casting liquid, which is the same as Example 1 except that the Karstedt catalyst is replaced by chloroplatinic acid, and in order to ensure the effect of the casting liquid, the solvent tetrahydrofuran is replaced by isopropanol (to facilitate the dissolution of chloroplatinic acid).

[0082] Comparative Example 1

[0083] This comparative example provides a casting liquid, which is different from Example 1 only in that the siloxane with nitrogen-containing borane side chains is not prepared, and 10.54 g of methyl vinyl siloxane with a weight-average molecular weight of 43,000 is directly added to 100 g of n-hexane. The rest is the same as Example 1 and will not be repeated here.

[0084] Comparative Example 2

[0085] This comparative example provides a casting solution, which is different from Example 1 only in that dimethylaminoborane is replaced by dimethylborane, and the rest is the same as Example 1, which will not be described again.

[0086] Comparative Example 3

[0087] This comparative example provides a casting solution, which is different from Example 1 only in that dimethylaminoborane is replaced by ethylamine, and the rest is the same as Example 1, which will not be repeated here.

[0088] Application Example 1

[0089] This application example provides a permeable membrane, which includes a polyimide base membrane (brand name PI-2610, thickness 20 μm), and a silicone rubber membrane layer located on the base membrane; the silicone rubber membrane layer is prepared by cross-linking the casting solution in Example 1. The specific preparation process includes: coating the casting solution on the polyimide base membrane, drying at 60°C for 12 hours, and the obtained permeable membrane with a total thickness of 40 μm is called MSR-1.

[0090] The NMR boron spectrum of the MSR-1 membrane was characterized by a Bruker Avance 400 spectrometer. 11 B NMR (128MHz), the nuclear magnetic resonance boron spectrum of the permeable membrane prepared in Example 1 is as follows Figure 1 As shown, from Figure 1 It can be seen that the NMR boron spectrum has a triplet peak at a chemical shift of -37.7, indicating that the permeable membrane MSR-1 in Example 1 has successfully modified the boron-containing substance, and the triplet peak indicates that borane is added to the double bond of the siloxane side chain to form a -BH2- structure. And relative to -BH3 (boron chemical shift is about 0) or R-BH2 (when R is an alkyl group, the boron chemical shift is in the low field and is generally positive), B - -N + The polarization effect causes the chemical shift of boron to shift to high field, indicating that the molecule has a BN structure.

[0091] Application Example 2

[0092] This application example provides a permeable membrane, which includes a polyimide base membrane (brand name PI-2610, thickness 20 μm), and a silicone rubber membrane layer located on the base membrane; the silicone rubber membrane layer is prepared by cross-linking the casting solution in Example 2. The specific preparation process includes: coating the casting solution on the polyimide base membrane, drying at 60°C for 12 hours, and the obtained permeable membrane with a total thickness of 35 μm is called MSR-2.

[0093] Application Example 3

[0094] This application example provides a permeable membrane, which includes a polysulfone base membrane (brand name K-3000, thickness 20 μm), and a silicone rubber membrane layer located on the base membrane; the silicone rubber membrane layer is prepared by cross-linking the casting solution in Example 3. The specific preparation process includes: coating the casting solution on the polysulfone base membrane, drying at 80°C for 6 hours, and the obtained permeable membrane with a total thickness of 32 μm is called MSR-3.

[0095] Application Example 4

[0096] This application example provides a permeable membrane, which includes a polyimide base membrane (brand name PI-2610, thickness 20 μm), and a silicone rubber membrane layer located on the base membrane; the silicone rubber membrane layer is prepared by cross-linking the casting solution in Example 4. The specific preparation process includes: coating the casting solution on the polyimide base membrane, drying at 60°C for 6 hours, and the obtained permeable membrane with a total thickness of 33 μm is called MSR-4.

[0097] Application Example 5

[0098] This application example provides a permeable membrane, which includes a polysulfone base membrane (brand name K-3000, thickness of 5 μm), and a silicone rubber membrane layer located on the base membrane; the silicone rubber membrane layer is prepared by cross-linking the casting solution in Example 5. The specific preparation process includes: coating the casting solution on the polysulfone base membrane, drying at 60°C for 6 hours, and the obtained permeable membrane with a total thickness of 16 μm is called MSR-5.

[0099] Application Example 6

[0100] This application example provides a permeable membrane, which includes a polysulfone base membrane (brand name K-3000, thickness of 5 μm), and a silicone rubber membrane layer located on the base membrane; the silicone rubber membrane layer is prepared by cross-linking the casting solution in Example 6. The specific preparation process includes: coating the casting solution on the polysulfone base membrane, drying at 60°C for 6 hours, and the obtained permeable membrane with a total thickness of 10 μm is called MSR-6.

[0101] Application Example 7

[0102] This application example provides a permeable membrane, which includes a polysulfone base membrane (brand name K-3000, thickness of 5 μm), and a silicone rubber membrane layer located on the base membrane; the silicone rubber membrane layer is prepared by cross-linking the casting solution in Example 7. The specific preparation process includes: coating the casting solution on the polysulfone base membrane, drying at 80°C for 12 hours, and the obtained permeable membrane with a total thickness of 17 μm is called MSR-7.

[0103] Application Example 8

[0104] This application example provides a permeable membrane, which includes a polyimide base membrane (brand name PI-2610, thickness 20 μm), and a silicone rubber membrane layer located on the base membrane; the silicone rubber membrane layer is prepared by cross-linking the casting solution in Example 7. The specific preparation process includes: coating the casting solution on the polyimide base membrane, drying at 80°C for 8 hours, and the obtained permeable membrane with a total thickness of 24 μm is called MSR-8.

[0105] Application Examples 9 to 15 and Comparative Application Examples 1 to 3

[0106] Application Examples 9 to 15 and Application Comparative Examples 1 to 3 provide a permeable membrane. Except for using the casting liquid in Examples 9 to 15 and Comparative Examples 1 to 3, the rest of the permeable membrane is the same as Application Example 1, which will not be repeated here.

[0107] Test method: The gas permeability of the membrane is measured by the pressure difference method. The gas permeability P is the volume of gas passing through the membrane within a certain period of time under unit membrane area and unit pressure difference, and the unit is barrer (10 -10 cm 3 s cm / cm 2 ·s·cmHg). The permeability of the simulated tail gas (4 vol% allyl chloride / nitrogen) was measured; the separation coefficient α is the ratio of the permeability of allyl chloride / nitrogen, and the larger the separation coefficient, the better the separation effect.

[0108] The test results of the above application examples and application comparison examples are shown in Table 1.

[0109] Table 1

[0110]

[0111]

[0112] From Table 1, we can see the following points:

[0113] (1) Comprehensive application examples 1 to 8 show that compared with conventional silicone rubber membranes, the modified permeable membranes of branched-chain modified borane-organic amines provided by the present invention have significantly improved permeability selectivity for allyl chloride / nitrogen, and improved the selective recovery efficiency of allyl chloride in allyl chloride tail gas, wherein α AC / N2 Above 30, and the permeability to allyl chloride P AC Above 1188barrer;

[0114] (2) It can be seen from the combination of Application Example 1 and Application Examples 9 to 10 that the dimethylaminoborane used in Application Example 1 is superior to the N-ethylaminoborane and diaminodihydroborane used in Application Examples 9 to 10. AC / N2 is 50, and in Application Examples 9 to 10, α AC / N2 38 and 4.2 respectively, which shows that the present invention can promote the polarization between boron and nitrogen, improve the adsorption capacity of olefins, and has high stability, and finally can further improve α AC / N2 ;

[0115] (3) From the perspective of Application Example 1 and Application Examples 11 to 12, it can be seen that the vinyl content of methyl vinyl siloxane in Application Example 1 is 5%, compared with 15% and 0.5% in Application Examples 11 to 12, respectively. AC / N2is 50, and in Application Examples 11 to 12, α AC / N2 11.4 and 13 respectively. Among them, the large number of modified sites in Application Example 11 leads to the enhancement of the intramolecular cross-chain boron-nitrogen interaction, thereby restraining some modified sites. In Application Example 12, when the alkenyl content is low, the number of modified sites is small and the modification effect is poor. This shows that the present invention can further improve α by preferably using methylvinylsiloxane with a suitable alkenyl content. AC / N2 ;

[0116] (4) It can be seen from the comprehensive application examples 1 and application examples 13 to 15 that the siloxane without alkenyl side chains used in application example 13 cannot be modified, and the separation effect is similar to that of the ordinary separation membrane; polyphenyl hydrogen siloxane is used in application example 14, and its cross-linking steric hindrance is greater than that of polymethyl hydrogen siloxane, and the cross-linking effect is relatively poor; compared with application example 1, application example 1 uses Karstedt catalyst, in which the alkenyl group has a reducing effect on platinum, and the effect is better than that of traditional chloroplatinic acid. This shows that the present invention optimizes the components in the casting solution, which can further improve the separation effect of allyl chloride and nitrogen;

[0117] (5) It can be seen from the application example 1 and the comparative examples 1 to 3 that the preparation of the siloxane having nitrogen-containing borane side chains is not performed in the application example 1, and the final α AC / N2 The separation effect is poor. In Application Example 2, ordinary borane is used for hydroboration. Borane does not undergo polarization, so its attraction to olefins is poor. AC / N2 It is only 11; in Application Example 3, ethylamine is used. Ethylamine cannot react with alkenyl in this synthesis route, so there is no modification effect. The final separation performance is equivalent to that of Application Example 1. This shows that the present invention can significantly improve the adsorption effect of silicone rubber membrane on allyl chloride and improve the separation effect of allyl chloride and nitrogen in the exhaust gas treatment process by modifying the alkenyl-containing siloxane with nitrogen-containing borane.

[0118] The present invention illustrates the detailed features of the present invention through the above embodiments, but the present invention is not limited to the above detailed features, that is, it does not mean that the present invention must rely on the above detailed features to be implemented. Those skilled in the art should understand that any improvement to the present invention, equivalent replacement of the technical features selected by the present invention, addition of auxiliary technical features, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A casting solution, characterized in that: The casting solution comprises siloxane, a cross-linking agent and a cross-linking catalyst; The siloxane is a siloxane having a nitrogen-containing borane branch chain.

2. The casting solution according to claim 1, characterized in that: The siloxane with nitrogen-containing borane side chains is obtained by modifying nitrogen-containing borane with olefin-containing siloxane.

3. The casting solution according to claim 2, characterized in that: The nitrogen-containing borane includes dimethylamino borane and / or 4-dimethylamino pyridine borane; Preferably, the mass ratio of the nitrogen-containing borane to the olefin-containing siloxane is (0.005-0.05):

1.

4. The casting solution according to claim 2 or 3, characterized in that: The olefin-containing siloxane includes any one or a combination of at least two of methylvinylsiloxane, acrylsiloxane or phenylvinylsiloxane; Preferably, the molecular weight of the olefin-containing siloxane is 20,000 to 50,000; Preferably, the vinyl content in the methylvinylsiloxane is 1-10%.

5. The casting solution according to any one of claims 1 to 3, characterized in that: The crosslinking agent is a hydroxyl-containing siloxane; Preferably, the hydroxyl-containing siloxane includes any one of polymethyl hydrogen siloxane, polyphenyl hydrogen siloxane or polymethyl phenyl hydrogen siloxane, or a combination of at least two thereof; Preferably, the mass ratio of siloxane, crosslinking agent and crosslinking catalyst in the casting solution is 1:(0.01-0.05):(0.005-0.01).

6. The casting solution according to any one of claims 1 to 3, characterized in that: The cross-linking catalyst comprises a Karstedt catalyst and / or chloroplatinic acid; Preferably, the content of the cross-linking catalyst in the casting solution is 500 to 4500 ppm.

7. The casting solution according to any one of claims 1 to 3, characterized in that: The solvent in the casting solution includes any one of n-hexane, cyclohexane or dichloromethane, or a combination of at least two of them.

8. A permeable membrane, characterized in that: The permeable membrane comprises a base membrane and a silicone rubber membrane layer located on the base membrane; the silicone rubber membrane layer is obtained by cross-linking the casting solution according to any one of claims 1 to 7.

9. The permeable membrane according to any one of claims 1 to 6, characterized in that The material of the base film includes polyimide and / or polysulfone.

10. Use of the permeable membrane according to claim 8 or 9 in the separation of halogenated olefins.

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