A modified activated transition metal molecular sieve and its application

Abstract

The present invention discloses a modified and activated transition metal molecular sieve and its application. The molecular sieve of the present invention is composed of a transition metal-doped molecular sieve as a matrix, and the matrix is modified by introducing a heteroatom element P, or the matrix is modified by a substance containing an active functional group, so that the active functional group is grafted onto the matrix, and the active functional group is at least one of NH-, NH2-, or COOH-. The transition metal-doped molecular sieve matrix comprises a substance having the following chemical composition molar ratio mSiO2:XO, wherein X is a divalent transition metal, and the molar ratio of SiO2 to XO is m=10-30. The present invention functionalizes and regulates the molecular sieve framework pores through the active functional group species, achieving fine regulation of the framework pore polarity and the active site electron transfer capacity by the active modifying group. The present invention can preferentially adsorb a large amount of C2H6 in the C2H6-C2H4 separation, and can be applied to the high-purity polymerization-grade ethylene purification process to adsorb and remove small amounts of ethane gas in the mixed gas.

Description

Technical Field

[0001] The invention relates to a modified activated transition metal molecular sieve, which can efficiently adsorb trace ethane gas in high-purity polymerization-grade ethylene gas and belongs to the field of gas adsorption separation. Background Art

[0002] Ethylene is an important petrochemical product with an annual output of up to 100 million tons, occupying an important position among all petrochemical products. The industrial production of ethylene is usually produced by high-temperature cracking of ethane, but the final product is often a mixture of a small amount of ethane and a large amount of ethylene. In order to further improve the purity of ethylene gas, the industry often uses cryogenic separation to further separate and purify the product mixture after cracking. However, this process consumes a lot of energy, has high production costs, and is not economically profitable (Nat. Commun., 2015, 6, 8697). The currently available low-energy methods for purifying ethylene include absorption separation, membrane separation, and pressure swing adsorption technology. The absorption separation method requires the introduction of a certain amount of absorbent during the absorption process to control the mixed gas to only carry out one-way mass transfer between the gas phase and the liquid phase. Subsequently, an analytical operation is required to recover the absorbent. Patent CN103058810A reports a suspension slurry with a metal-organic framework for ethane and ethylene separation. The separation equipment involved in this method is numerous and costly, and the suspension slurry still needs to be analyzed in the later stage. Membrane separation utilizes the differences in molecular size and diffusion properties between ethane and ethylene. However, the molecular size difference between ethane and ethylene is small, and membrane materials are expensive and easily damaged. Furthermore, the higher the membrane's selectivity, the lower its gas permeability. Pressure swing adsorption technology can effectively separate low-concentration gases at room temperature, thus addressing the high energy consumption of traditional methods.

[0003] Porous materials have been widely studied as solid adsorbents commonly used in pressure swing adsorption technology. Currently, commonly used porous materials mainly include carbon materials, metal organic framework materials (MOFs) and zeolite molecular sieves. In the process of ethane and ethylene separation, the material needs to have high separation selectivity, but carbon materials are often widely adsorbed during the gas adsorption process and cannot achieve the product purity required in the industry. MOFs is a three-dimensional network structure formed by cross-linking metal nodes and organic ligands, which usually has a uniform pore size of 0.3nm-2nm (Nature, 2003, 423, 705). Although there are reports on the adsorption and separation of ethane-ethylene mixed gases by MOFs materials, ethylene is usually adsorbed in large quantities first, and the energy consumption of adsorption separation in high-concentration ethylene systems is high (J.Am.Chem.Soc.2021, 143, 8654-8660). Patent CN105709693A reports the application of a flexible MOFs material in ethane-ethylene adsorption separation, which preferentially adsorbs ethylene gas in large quantities. Although Li et al. will contain Fe(Ⅲ)-O22- MOF-47, with its ethylene-to-ethane site, has been used in ethane-ethylene separation, selectively adsorbing ethane. However, its reported ethane-to-ethylene adsorption capacity ratio is only 1.25, indicating poor adsorption separation performance (Science, 2018, 362, 443–446). Furthermore, patent CN105949028 reports a unique MOF preparation method that preferentially adsorbs oxygen molecules at the material's unsaturated sites, limiting the interaction between the unsaturated sites and ethylene molecules. This has led to its successful application in ethane separation, but the ethane separation selectivity decreases significantly with decreasing concentration. Furthermore, MOFs inherently have poor hydrothermal stability, limiting their industrial application. Zeolite molecular sieves are often used to separate different gas components in mixed gases. Their basic structure consists of regular tetrahedra centered on Si or Al atoms connected by oxygen bridges, forming a ring structure. Zeolite molecular sieves offer advantages such as structural stability, uniform and adjustable pore size, and good recyclability during gas separation. At present, the zeolite molecular sieves with the best ethane and ethylene separation performance are ITQ-55 molecular sieve, LTA type, FAU type and ETS type molecular sieve. However, due to the stronger polarity of ethylene gas, most of the current molecular sieve applications in ethane and ethylene separation research have prioritized the adsorption of ethylene components, and later thermal desorption is required to obtain high-purity ethylene gas (J.Am.Chem.Soc.2012,134,14635-14637). MFI molecular sieve is a small-pore molecular sieve with a main pore composed of ten-membered rings and a pore size of The pore size of MFI molecular sieve matches the size of ethane and ethylene gas molecules, and the pore size of MFI molecular sieve matches the size of ethane molecules. The pore wall adsorption is stronger, and it is very suitable for the separation of low-concentration ethane. However, there are still few reports on the application of MFI molecular sieves in the ethane and ethylene adsorption separation process.

[0004] At present, the adsorption and separation effect of molecular sieves is mainly achieved by introducing active metals to regulate the electrostatic adsorption force. The control methods of electrostatic action mainly include impregnation, ion exchange and isomorphous substitution. Among them, impregnation is mainly physical mixing, and active metal species are difficult to enter the molecular sieve framework. Patent CN114477205A reports a process for preparing titanium-containing MFI molecular sieves using an impregnation method. The obtained sample is rich in titanium species only on the surface of the molecular sieve. Patent CN108187607A reports a method of using equal volume impregnation to dope metal active salt active components into titanium silicon molecular sieves for ethane and ethylene adsorption separation process. The ethylene-ethane adsorption separation factor is 6.57. The adsorption capacity of the adsorption separation agent for ethylene is 2.602mmol / g, and the adsorption capacity of ethane is 0.396mmol / g, which still cannot achieve preferential separation of ethane. Introducing heteroatoms into molecular sieves through ion exchange easily leads to strong electrostatic fields. Patent CN104549141A selects lanthanide metal elements to modify molecular sieve materials through ion exchange, showing extremely strong polarity and induction in the molecular sieve framework. The same patent CN111747819B uses imidazole compounds to modify MFI molecular sieves through ion exchange and applies it to ethane and ethylene separation, with an equilibrium separation ratio of only 1.1. In the ethane-ethylene separation process, due to the weak polarity of ethane, the preferential adsorption separation of ethane requires the use of weakly polar molecular sieve materials. Therefore, the method of introducing metal elements by ion exchange and impregnation is not suitable for preferentially capturing low-concentration ethane gas in the mixed gas. We have previously reported a transition metal MFI molecular sieve modified by isomorphous substitution, which showed excellent ethane and ethylene separation selectivity. However, the adsorption behavior of ethane and ethylene in molecular sieves shows that compared with metal ion modification, non-polar heteroatom group modification can more easily obtain a relatively weak electrostatic field while introducing active sites, which is more advantageous for regulating the adsorption and separation force of low-concentration ethane.

[0005] Therefore, based on the above phenomenon, the present invention proposes a novel method for preparing heteroatom-modified transition metal atom MFI molecular sieves. Transition metal atoms are used to synthesize transition metal-doped MFI molecular sieves. The modified substance is evenly mixed with the molecular sieve powder, and then continued to stir at high temperature in a water bath. Through functional group grafting, ion exchange and other means, the active functional group substance is used to finely control the polarity of the molecular sieve pores and the electron transfer ability of the active site, thereby achieving preferential adsorption of low-concentration ethane in a large amount of ethylene. Summary of the Invention

[0006] In view of the above technical problems existing in the prior art, the purpose of the present invention is to provide a modified activated transition metal molecular sieve and its application. The present invention relates to an MFI molecular sieve adsorbent modified with active functional groups, which can efficiently capture low-content ethane gas.

[0007] To achieve the above objectives, the present invention uses tetrapropylammonium hydroxide as the alkaline template agent of the hydrothermal system. By optimizing the experimental method, a large number of active functional groups are promoted to stably enter the molecular sieve framework, and a low-polarity MFI molecular sieve with a high silicon content is successfully synthesized. It preferentially adsorbs ethane and is suitable for use as an adsorbent for the adsorption and separation of low-content ethane-high-content ethylene gas systems.

[0008] The technical solution adopted in the present invention is as follows:

[0009] A modified activated transition metal molecular sieve, which uses a transition metal-doped molecular sieve as a matrix, and is modified by introducing a heteroatom element P into the matrix, or by modifying the matrix with a substance containing active functional groups so that active functional groups are grafted onto the matrix, wherein the active functional groups of the substance containing active functional groups are at least one of NH-, NH2- or COOH-; the transition metal-doped molecular sieve matrix comprises a substance having the following chemical composition molar ratio: mSiO2:XO, wherein X is a divalent transition metal, and the molar ratio of SiO2 to XO is m=10-30.

[0010] Furthermore, the divalent transition metal X includes one or more of Ni, Mn, Cu, and Zn, preferably Mn; the molar ratio of SiO2 to XO is m=15-25, preferably 20.

[0011] Furthermore, the modified activated transition metal molecular sieve has an MFI molecular sieve configuration recognized by the International Zeolite Association (IZA), and as determined by X-ray diffraction, the molecular sieve has characteristic peaks within at least the following four interplanar spacings (d): the first interplanar spacing d = 11.0 ± 0.3, the second interplanar spacing d = 9.9 ± 0.2, the third interplanar spacing d = 4.3 ± 0.2, and the fourth interplanar spacing d = 3.8 ± 0.2.

[0012] Furthermore, the present invention uses the following process to activate the transition metal-doped molecular sieve matrix by introducing a heteroatom element P for modification:

[0013] S1: Add phosphorus source to organic solvent, heat and stir evenly;

[0014] S2: Add the transition metal-doped molecular sieve matrix to the solution obtained in step S1, heat and stir at 50-70°C for 2-4h, then evaporate the solvent, dry, and finally calcine at high temperature in an inert atmosphere containing 5-20% volume fraction of H2 to complete the activation; wherein, the ratio of the amount of P element in the phosphorus source to the mass of the transition metal-doped molecular sieve matrix is 0.2-0.8:1, preferably 0.4-0.5:1, the unit of the amount of substance is mmol, and the unit of mass is g.

[0015] Furthermore, the phosphorus source is triphenylphosphine, the organic solvent is ethanol, toluene or N,N-dimethylformamide; the high-temperature calcination temperature is 500-600° C., and the calcination time is 1-4 hours.

[0016] Furthermore, the present invention uses a substance containing an active functional group to modify a transition metal-doped molecular sieve matrix as follows: the substance containing an active functional group and the transition metal-doped molecular sieve matrix are dispersed together in a solvent, stirred at a temperature between room temperature and 80°C for 3-40 hours, and then solid-liquid separation is performed. The solid is washed with ethanol and dried to complete the activation; the amount of the active functional group NH, NH2- or COOH- in the substance containing an active functional group is in a ratio of 0.4-4:1 to the mass of the transition metal-doped molecular sieve matrix, the amount of the substance is mmol, and the mass unit is g.

[0017] Furthermore, the substance containing active functional groups is ethanolamine, diethanolamine, 3-(2-aminoethyl)-aminopropylmethyldimethoxysilane, formic acid, oxalic acid or lactic acid, preferably formic acid or oxalic acid, and the solvent is ethanol, toluene, N,N-dimethylformamide or deionized water.

[0018] Furthermore, the transition metal-doped molecular sieve matrix of the present invention is prepared according to the following steps:

[0019] 1) An alkaline template agent and deionized water are sequentially added to a reactor, heated and stirred to fully dissolve and mix, and then a transition metal X salt and a silicon source in the above molecular sieve composition are added according to the molar ratio of SiO2:XO oxide. After stirring and aging, an initial gel solution is obtained, which is transferred to a sealed reactor and subjected to a hydrothermal synthesis reaction to obtain a transition metal-doped molecular sieve precursor solid-liquid mixture; the alkaline template agent is tetrapropylammonium hydroxide;

[0020] 2) filtering, washing, and drying the molecular sieve precursor after the reaction in step 1), and then calcining it at high temperature in air to remove organic matter in the molecular sieve precursor, thereby obtaining the transition metal-doped molecular sieve.

[0021] Furthermore, in step 1), the mass ratio of deionized water to tetrapropylammonium hydroxide is 2-6:1, preferably 3-3.5:1; the mass of tetrapropylammonium hydroxide is 20-35% of the mass of the silicon source raw material, preferably 25-30%, and the silicon source is TEOS.

[0022] Furthermore, in step 1), the aging time is selected to be 12-24 hours, preferably 12-16 hours; the aging temperature is selected to be room temperature; the reaction temperature of the hydrothermal synthesis is 180-220°C, preferably 200°C; the reaction time of the hydrothermal synthesis is the molecular sieve crystallization stability time, selected to be 2.8-3.2 hours, preferably 3 hours.

[0023] Furthermore, the calcination temperature in the high-temperature calcination in step 2) is 400-700° C., preferably 500-600° C., and the calcination time is 2-12 h, preferably 3-8 h, and more preferably 4-7 h.

[0024] The modified activated transition metal molecular sieve is used for selective adsorption separation of ethane-ethylene mixed gas, and preferentially adsorbs a large amount of ethane gas in the mixed gas.

[0025] The transition metal molecular sieve modified with active functional groups (i.e., modified and activated transition metal molecular sieve) described in the present invention can be used to selectively absorb and separate ethane in the atmosphere of an ethane-ethylene system, thereby achieving the separation of ethane and ethylene. Compared with commercial silica-alumina molecular sieves and traditional one-step synthesized metal atom-doped molecular sieves, it can preferentially adsorb a large amount of ethane.

[0026] The active functional group-modified transition metal molecular sieve can be operated at 273-323K for adsorption and separation of gas, preferably 288-308K, and more preferably 298K.

[0027] The active functional group-modified transition metal molecular sieve of the present invention can be applied to the preferential selective adsorption separation of low-concentration ethane gas in a large amount of ethylene.

[0028] The present invention is a technological advancement compared to the prior art;

[0029] (1) The transition metal molecular sieve modified with active functional groups in the present invention changes the molecular sieve pore polarity and active site electron transfer capacity through precise regulation of the skeleton pore function, increases the recognition of ethane in the ethane-ethylene mixture by the adsorption site, realizes the preferential selective adsorption and separation of ethane, effectively improves the preferential large-scale adsorption of traditional molecular sieves in low-concentration ethane systems, and reduces energy consumption.

[0030] (2) The modification method of the active functional group-modified transition metal molecular sieve in the present invention is to introduce the modifying elements by grafting, ion exchange, etc. under high-temperature water bath stirring conditions. Compared with the metal-modified molecular sieve materials currently used for ethane and ethylene separation, this method can obtain a relatively weak electrostatic field, which is more conducive to the adsorption and separation of weak polarity and low concentration ethane gas in the ethane and ethylene mixture.

[0031] (3) By using the modification method of the active functional group-modified transition metal molecular sieve of the present invention, different modifying elements are substituted into the molecular sieve framework to obtain molecular sieves with different active adsorption sites. These molecular sieves can then be applied to various adsorption catalytic reactions based on the properties of the active functional group substances. Since most of the active sites are present in the framework, the molecular sieves after isomorphous substitution have high activity and excellent reproducibility. This preparation method provides some reference for the development of porous materials in the chemical industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the XRD test results of H-MFI-Zn / 20 in Example 1;

[0033] Figure 2 Schematic diagram of the XRD test results of H-MFI-Mn / 20 in Example 1;

[0034] Figure 3 Schematic diagram of the XRD test results of H-MFI-Ni / 20 in Example 1;

[0035] Figure 4 Schematic diagram of the XRD test results of H-MFI-Cu / 20 in Example 1;

[0036] Figure 5 Schematic diagram of ethane and ethylene breakthrough curves of Zn, Mn, Cu, and Ni molecular sieves in Example 1;

[0037] Figure 6 Schematic diagram of the XRD test results of H-MFI-Mn / 20-P in Example 2;

[0038] Figure 7 is a schematic diagram of the ethane-ethylene breakthrough curve of H-MFI-Mn / 20-P in Example 2;

[0039] Figure 8 Schematic diagram of the XRD test results of H-MFI-Mn / 20-NH2 in Example 3;

[0040] Figure 9 is a schematic diagram of the ethane-ethylene breakthrough curve of H-MFI-Mn / 20-NH2 in Example 3;

[0041] Figure 10 Schematic diagram of the XRD test results of H-MFI-Mn / 20-NH in Example 4;

[0042] Figure 11 is a schematic diagram of the ethane-ethylene breakthrough curve of H-MFI-Mn / 20-NH in Example 4;

[0043] Figure 12Schematic diagram of the XRD test results of the H-MFI-Mn / 2-coupling agent in Example 5;

[0044] Figure 13 Schematic diagram of the ethane-ethylene breakthrough curve of the H-MFI-Mn / 20-coupling agent in Example 5;

[0045] Figure 14 is a schematic diagram of the XRD test results of H-MFI-Mn / 20-COOH in Example 6;

[0046] Figure 15 is a schematic diagram of the ethane-ethylene breakthrough curve of H-MFI-Mn / 20-COOH in Example 6;

[0047] Figure 16 is a schematic diagram of the XRD test results of H-MFI-Mn / 20-H2C2O4 in Example 7;

[0048] Figure 17 is a schematic diagram of the ethane-ethylene breakthrough curve of H-MFI-Mn / 20-H2C2O4 in Example 7;

[0049] Figure 18 is a schematic diagram of the XRD test results of H-MFI-Mn / 20-lactic acid in Example 8;

[0050] Figure 19 is a schematic diagram of the ethane ethylene breakthrough curve of H-MFI-Mn / 20-lactic acid in Example 8;

[0051] Figure 20 This is a schematic diagram of the ethane-ethylene breakthrough curve of UIO-66 in Comparative Example 1;

[0052] Figure 21 Schematic diagram of the ethane-ethylene breakthrough curve of MFI-Al / 50 in Comparative Example 2;

[0053] Figure 22 This is a schematic diagram of the XRD test results of H-MFI-Mn / 20-OH in Comparative Example 3. DETAILED DESCRIPTION

[0054] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0055] <Example 1>

[0056] To 6.8877g of TPAOH aqueous solution (TPAOH content = 25% by mass), 0.32g of deionized water was added, followed by 6g of TEOS (approximately 98% by mass) and 0.3494g of manganese acetate tetrahydrate. The solution was aged at room temperature for 12 hours to obtain an initial gel solution. The initial solution was placed in a sealed, polytetrafluoroethylene-lined stainless steel crystallization kettle and statically crystallized at 200°C for 3 hours. After the hydrothermal reaction, the kettle was cooled, the reaction solution was centrifuged, and washed to obtain a crystalline product. The obtained crystals were dried at 110°C for 5 h, ground, and calcined in air: heated to 580°C at a rate of 2°C / min, maintained at 580°C for 6 h to fully volatilize the moisture and organic matter therein, and then cooled to 80°C to obtain H-MFI-Mn / 20 (the naming rule for all homemade molecular sieves is: H-MFI-Mn / 20, where H is the balanced cation type, MFI is the molecular sieve configuration, Mn is the transition metal atom type, and 20 is the molar ratio of silicon to transition metal atoms, the same below).

[0057] According to the above preparation method, when 0.3494 g of manganese acetate tetrahydrate was replaced by 0.2318 g of nickel acetate tetrahydrate, 0.284 g of copper acetate monohydrate or 0.3129 g of zinc acetate dihydrate, while other conditions remained unchanged, molecular sieves H-MFI-Ni / 20, H-MFI-Cu / 20, and H-MFI-Zn / 20 were finally prepared, respectively.

[0058] The calcined molecular sieve samples were taken out and stored in a drying dish. The obtained products were analyzed by XRD for product phase analysis. The interplanar spacing of the characteristic peaks in H-MFI-Mn / 20, H-MFI-Zn / 20, H-MFI-Cu / 20, and H-MFI-Ni / 20 are shown in Table 1. The schematic diagram of the XRD test results is shown in Figure 1-4 , indicating that the synthesized zeolite has the MFI zeolite configuration identified by IZA.

[0059] The H-MFI-Mn / 20, H-MFI-Zn / 20, H-MFI-Cu / 20, and H-MFI-Ni / 20 samples were used to adsorb ethane or ethylene. Gas adsorption isotherms were measured on a Micromeritics 3Flex adsorption instrument. The adsorbed gases were ethane (99.99%) and ethylene (99.99%). To investigate the effect of pre-occupying atom-doped molecular sieves on ethane adsorption, the molecular sieves were dehydrated in a 3Flex to prevent the effect of physically adsorbed water on gas adsorption. Under low vacuum conditions (below 0.005 mmHg), the samples were heated at a rate of 5°C / min to 100°C, held for 1 hour, then heated at a rate of 5°C / min to 200°C, held for 1 hour, and then heated at a rate of 5°C / min to 350°C, held at 350°C for 6 hours. The sample tube was then placed in a 3Flex adsorption device for static adsorption curve testing (0-1 bar). A constant temperature water bath (accuracy 0.01°C) was used to control the temperature in the gas adsorption sample tube. The adsorption temperature was 298K. The static adsorption capacities of ethane and ethylene gases by H-MFI-Mn / 20, H-MFI-Zn / 20, H-MFI-Cu / 20, and H-MFI-Ni / 20 are shown in Table 10.

[0060] The ethane and ethylene gas adsorption penetration curve of the molecular sieve sample was measured on an Agilent 8860 series gas chromatograph. The adsorbed mixed gas composition is ethane: ethylene = 5:5 (volume ratio), the total flow rate of the mixed gas is 5.2 ml / min, and the mass of the molecular sieve adsorbent is 2.5 g. First, the peak of each pure gas component molecule in the detector is tested. After the error of the peak area of each component is within 1%, the valve is switched to pass the raw mixed gas into the reaction tube. The outlet of the reaction tube is connected to the automatic injection port of the gas chromatograph, and the gas chromatograph is started for testing. After obtaining the test results, the gas phase penetration curve of the ethane-ethylene adsorption system is obtained by comparing the peak area of each component of the mixer at the outlet of the reaction tube with that of each component of the pure gas. The results are as follows Figure 5 As shown in Table 12, the dynamic adsorption capacity and selectivity of H-MFI-Mn / 20, H-MFI-Zn / 20, H-MFI-Cu / 20, and H-MFI-Ni / 20 molecular sieve adsorbents for ethane and ethylene gases at a partial pressure of 0.5 bar are shown.

[0061] Table 1 Characteristic interplanar spacings of H-MFI-Mn / 20, H-MFI-Zn / 20, H-MFI-Cu / 20, and H-MFI-Ni / 20

[0062]

[0063]

[0064] Table 1 lists the interplanar spacings at which the seven characteristic peaks of the four molecular sieve samples are located. The seven characteristic peaks correspond to the characteristic peaks indicated by the seven arrows in their respective XRD patterns, and the same applies below.

[0065] <Example 2>

[0066] Based on the comparison of the breakthrough curve data of the four samples in Example 1, the H-MFI-Mn / 20 molecular sieve sample with the highest adsorption capacity and selectivity was selected for modification.

[0067] Molecular sieve H-MFI-Mn / 20 was prepared according to the method of Example 1. 0.3152 g of triphenylphosphine and 50 ml of N,N-dimethylformamide (DMF) were stirred in a 60°C water bath for 1 hour. After mixing evenly, 3 g of H-MFI-Mn / 20 molecular sieve solid powder was added and continued to be stirred in a 60°C water bath for 3 hours. After evaporating the solvent by rotary evaporation, the mixture was dried in an air atmosphere at 70°C. Finally, the mixture was heated to 600°C in a 10% H2 / Ar atmosphere at a heating rate of 20°C / min and calcined for 3 hours. The calcined sample was recorded as H-MFI-Zn / 20-P. H-MFI-Zn / 20-P was taken out and placed in a drying dish for storage. The obtained product was analyzed for product crystal phase by XRD. The interplanar spacing of the characteristic peaks in H-MFI-Zn / 20-P is shown in Table 2. The schematic diagram of the XRD test results is shown in FIG. Figure 6 , indicating that the synthesized zeolite has the MFI zeolite configuration identified by IZA.

[0068] The above H-MFI-Mn / 20-P was used for static adsorption and dynamic breakthrough experiments on ethane or ethylene gas. The adsorption test conditions were repeated in Example 1. The static adsorption capacity of H-MFI-Mn / 20-P for ethane and ethylene gas is shown in Table 10, and the dynamic adsorption capacity and selectivity are shown in Table 12. The ethane and ethylene breakthrough curve test results of H-MFI-Mn / 20-P in Example 2 are shown in Table 13. Figure 7 .

[0069] Table 2 Characteristic interplanar spacing of H-MFI-Mn / 20-P

[0070] Interplanar spacing (d) 1 11.112 2 9.993 3 6.683 4 4.353 5 4.076 6 3.845 7 3.744

[0071] <Example 3>

[0072] Molecular sieve H-MFI-Mn / 20 was prepared according to the method of Example 1. 0.468g of ethanolamine was mixed evenly with 20ml of toluene. At the same time, 3g of the molecular sieve sample was dried under vacuum conditions for 5h and mixed with 40ml of toluene and ultrasonically distributed for 30min. The turbid liquid was added to the ethanolamine solution and continued to stir at 500rpm for 24h at room temperature. The sample was washed three times with centrifugal ethanol and dried at 70°C in an air atmosphere. The dried sample was taken out and placed in a drying dish for storage. The obtained product was recorded as H-MFI-Mn / 20-NH2. XRD was used to analyze the crystal phase of H-MFI-Mn / 20-NH2. The interplanar spacing of the characteristic peaks in H-MFI-Mn / 20-NH2 is shown in Table 3. The schematic diagram of the XRD test results is shown in the figure. Figure 8 , indicating that the synthesized zeolite has the MFI zeolite configuration identified by IZA.

[0073] The above H-MFI-Mn / 20-NH2 was used for static adsorption and dynamic breakthrough experiments on ethane or ethylene gas. The adsorption test conditions were repeated in Example 1. The static adsorption capacity of H-MFI-Mn / 20-NH2 for ethane and ethylene gas is shown in Table 10, and the dynamic adsorption capacity and selectivity are shown in Table 12. The ethane and ethylene breakthrough curve test results of H-MFI-Mn / 20-NH2 in Example 3 are shown in Table 10. Figure 9 .

[0074] Table 3 Characteristic interplanar spacing of H-MFI-Mn / 20-NH2

[0075] Interplanar spacing (d) 1 11.136 2 10.007 3 5.988 4 4.369 5 4.002 6 3.843 7 3.756

[0076] <Example 4>

[0077] The preparation method of H-MFI-Mn / 20-NH in Example 4 repeats the modification process of H-MFI-Mn / 20-NH2 in Example 3, except that "0.468g of ethanolamine is replaced by 0.6715g of diethanolamine". The dried sample is recorded as H-MFI-Mn / 20-NH. After H-MFI-Mn / 20-NH is taken out and placed in a drying dish for storage, the obtained product is analyzed by XRD for product crystal phase. The interplanar spacing of the characteristic peaks in H-MFI-Mn / 20-NH is shown in Table 4. The schematic diagram of the XRD test results is shown in Figure 4. Figure 10 , indicating that the synthesized zeolite has the MFI zeolite configuration identified by IZA.

[0078] The above H-MFI-Mn / 20-NH was used for static adsorption and dynamic breakthrough experiments on ethane or ethylene gas. The adsorption test conditions were repeated in Example 1. The static adsorption capacity of H-MFI-Mn / 20-NH for ethane and ethylene gas is shown in Table 10, and the dynamic adsorption capacity and selectivity are shown in Table 12. The ethane and ethylene breakthrough curve test results of H-MFI-Mn / 20-NH in Example 4 are shown in Table 10. Figure 11 .

[0079] Table 4 Characteristic interplanar spacing of H-MFI-Mn / 20-NH

[0080]

[0081]

[0082] <Example 5>

[0083] Preparation and Modification Method of H-MFI-Mn / 20-Coupling Agent in Example 5: The modification process of H-MFI-Mn / 20-NH2 in Example 3 was repeated, except that 0.468 g of ethanolamine was replaced with 0.2578 g of 3-(2-aminoethyl)-aminopropylmethyldimethoxysilane. The dried sample was recorded as H-MFI-Mn / 20-coupling agent. The H-MFI-Mn / 20-coupling agent was removed and stored in a desiccating dish. The obtained product was analyzed by XRD for product phase. The interplanar spacing of the characteristic peaks in H-MFI-Mn / 20-NH is shown in Table 5. The schematic diagram of the XRD test results is shown in FIG. Figure 12 , indicating that the synthesized zeolite has the MFI zeolite configuration identified by IZA.

[0084] The above H-MFI-Mn / 20-coupling agent was used for static adsorption and dynamic breakthrough experiments on ethane or ethylene gas. The adsorption test conditions were repeated in Example 1. The static adsorption capacity of H-MFI-Mn / 20-coupling agent for ethane and ethylene gas is shown in Table 10, and the dynamic adsorption capacity and selectivity are shown in Table 12. The ethane and ethylene breakthrough curve test results of H-MFI-Mn / 20-NH in Example 4 are shown in Table 10. Figure 13 .

[0085] Table 5 Characteristic interplanar spacing of H-MFI-Mn / 20 coupling agent

[0086]

[0087]

[0088] Example 6

[0089] Molecular sieve H-MFI-Mn / 20 was prepared according to the method of Example 1. 0.48 ml of formic acid (mass percentage of about 88%) was mixed evenly with 20 ml of deionized water. At the same time, 3 g of H-MFI-Mn / 20 molecular sieve sample was dried at 350°C under vacuum conditions for 3 hours, mixed with 30 ml of deionized water and stirred in a water bath to form a turbid liquid. Then, the formic acid mixed solution was added, the temperature was raised to 80°C and stirred in a water bath for 4 hours, centrifuged and washed 3 times, and dried at 60°C in an air atmosphere. The dried sample was recorded as H-MFI-Mn / 20-COOH. After H-MFI-Mn / 20-COOH was taken out, it was placed in a drying dish for storage. The obtained product was analyzed for product crystal phase by XRD. The interplanar spacing of the characteristic peaks in H-MFI-Mn / 20-COOH is shown in Table 6, and the schematic diagram of XRD is shown in Figure 14 , indicating that the synthesized zeolite has the MFI zeolite configuration identified by IZA.

[0090] The above H-MFI-Mn / 20-COOH was used for static adsorption and dynamic breakthrough experiments on ethane or ethylene gas. The adsorption test conditions were repeated in Example 1. The static adsorption capacity of H-MFI-Mn / 20-COOH for ethane and ethylene gas is shown in Table 10, and the dynamic adsorption capacity and selectivity are shown in Table 12. The ethane and ethylene breakthrough curve results of H-MFI-Mn / 20-COOH in Example 6 are shown in Table 10. Figure 15 .

[0091] Table 6 Characteristic interplanar spacing of H-MFI-Mn / 20-COOH

[0092] Interplanar spacing (d) 1 11.116 2 9.998 3 6.680 4 4.355 5 4.078 6 3.843 7 3.741

[0093] <Example 7>

[0094] Preparation and Modification of H-MFI-Mn / 20-H2C2O4 in Example 7: The modification process of H-MFI-Mn / 20-COOH in Example 6 was repeated, with the only difference being that 0.48 ml of formic acid was replaced with 0.3194 g of oxalic acid dihydrate. The calcined sample was designated H-MFI-Mn / 20-H2C2O4. H-MFI-Mn / 20-H2C2O4 was taken out and placed in a drying dish for storage. The resulting product was analyzed by XRD for crystal phase. The interplanar spacing of the characteristic peaks in H-MFI-Mn / 20-H2C2O4 is shown in Table 7, and the schematic diagram of XRD is shown in FIG. Figure 16 , indicating that the synthesized zeolite has the MFI zeolite configuration identified by IZA.

[0095] The above H-MFI-Mn / 20-H2C2O4 was used for static adsorption and dynamic breakthrough experiments on ethane or ethylene gas. The adsorption test conditions were repeated in Example 1. The static adsorption capacity of H-MFI-Mn / 20-H2C2O4 for ethane and ethylene gas is shown in Table 10, and the dynamic adsorption capacity and selectivity are shown in Table 12. The ethane and ethylene breakthrough curve test results of H-MFI-Mn / 20-H2C2O4 in Example 7 are shown in Table 10. Figure 17 .

[0096] Table 7 Characteristic interplanar spacing of H-MFI-Mn / 20-H2C2O4

[0097] Interplanar spacing (d) 1 11.110 2 9.973 3 6.353 4 4.360 5 4.000 6 3.842 7 3.753

[0098] <Example 8>

[0099] Preparation and Modification of H-MFI-Mn / 20-Lactic Acid in Example 8: The modification process of H-MFI-Mn / 20-COOH in Example 6 was repeated, with the only difference being that 0.48 ml of formic acid was replaced with 0.6744 g of L-lactic acid. The dried sample was designated H-MFI-Mn / 20-lactic acid. The H-MFI-Mn / 20-lactic acid was removed and placed in a drying dish for storage. The resulting product was analyzed by XRD for crystal phase. The interplanar spacings of the characteristic peaks in H-MFI-Mn / 20-lactic acid are shown in Table 8, and the schematic diagram of the XRD is shown in FIG. Figure 18 , indicating that the synthesized zeolite has the MFI zeolite configuration identified by IZA.

[0100] The above H-MFI-Mn / 20-lactic acid was used for static adsorption and dynamic breakthrough experiments on ethane or ethylene gas. The adsorption test conditions were repeated in Example 1. The static adsorption capacity of H-MFI-Mn / 20-lactic acid for ethane and ethylene gas is shown in Table 10, and the dynamic adsorption capacity and selectivity are shown in Table 12. The ethane and ethylene breakthrough curve test results of H-MFI-Mn / 20-lactic acid in Example 8 are shown in Table 10. Figure 19 .

[0101] Table 8 Characteristic interplanar spacing of H-MFI-Mn / 20-lactic acid

[0102] Interplanar spacing (d) 1 11.112 2 9.993 3 6.682 4 4.351 5 4.033 6 3.852 7 3.712

[0103] Comparative Example 1

[0104] Dissolve 0.4g ZrCl4 in 45ml DMF by ultrasonication for 20min. Simultaneously, dissolve 0.28g terephthalic acid in 15ml DMF by ultrasonication for 20min. Mix the two solutions and ultrasonicate them for 2-3min. Crystallize at 120°C in air for 24h. Centrifuge and soak the sample three times in 40ml DMF and methanol for 12h each. Centrifuge and dry under vacuum at 150°C for 12h. The dried sample is designated as uio-66 sample and placed in a desiccating dish for storage.

[0105] The above UIO-66 sample was used for static adsorption and dynamic penetration experiments on ethane or ethylene gas. The adsorption test conditions were repeated in Example 1. The static adsorption capacity of ethane and ethylene gas by the UIO-66 sample is shown in Table 11, and the dynamic adsorption capacity and selectivity are shown in Table 12. The ethane and ethylene penetration curve test results of UIO-66 in Comparative Example 1 are shown in Table 11. Figure 20 .

[0106] Comparative Example 2

[0107] A certain amount of commercial H-type MFI molecular sieves with different silicon-to-aluminum ratios (commercial molecular sieves are named H-MFI / A, where A is the atomic molar ratio of silicon to aluminum in the molecular sieve; all commercial molecular sieves are silicon-aluminum molecular sieves) were calcined in air to ensure impurities were removed: heating to 580°C at a rate of 2°C / min, maintaining at 580°C for 6 hours, and then cooling to 100°C. The dried samples were removed and stored in a desiccating dish.

[0108] The commercial molecular sieve samples were used for static adsorption of ethane or ethylene gas and dynamic penetration test of H-MFI / 50 molecular sieve samples. The adsorption test conditions were repeated in Example 1. The static adsorption capacity of commercial molecular sieve samples for ethane and ethylene gas is shown in Table 11, and the dynamic adsorption capacity and selectivity of H-MFI / 50 are shown in Table 12. The ethane and ethylene breakthrough curve test results of MFI-Al / 50 in Comparative Example 2 are shown in Table 13. Figure 21 .

[0109] Comparative Example 3

[0110] Preparation and Modification of H-MFI-Mn / 20-OH in Comparative Example 3: The modification process of H-MFI-Mn / 20-COOH in Example 6 was repeated, with the only difference being that 0.48 ml of formic acid was replaced with 0.802 g of ethylene glycol. The dried sample was designated H-MFI-Mn / 20-OH. H-MFI-Mn / 20-OH was removed and placed in a drying dish for storage. The resulting product was analyzed by XRD for crystal phase. The interplanar spacings of the characteristic peaks in H-MFI-Mn / 20-OH are shown in Table 9, and the schematic diagram of the XRD is shown in FIG. Figure 22, indicating that the synthesized zeolite has the MFI zeolite configuration identified by IZA.

[0111] The above-mentioned H-MFI-Mn / 20-OH was used for static adsorption and dynamic breakthrough experiments on ethane or ethylene gas. The adsorption test conditions were repeated in Example 1. The static adsorption capacity of H-MFI-Mn / 20-OH for ethane and ethylene gas is shown in Table 11, and the dynamic adsorption capacity and selectivity are shown in Table 12.

[0112] Table 9 Characteristic interplanar spacing of H-MFI-Mn / 20-OH

[0113]

[0114]

[0115] Table 10298K static adsorption of ethane and ethylene by different molecular sieves in the examples

[0116]

[0117] Table 11 Static adsorption of ethane and ethylene gases by metal organic framework materials and different commercial molecular sieves and one-step method in comparative examples at 298K

[0118] Commercial molecular sieve name Ethane adsorption capacity (mmol / g) Ethylene adsorption capacity (mmol / g) Uio-66 1.542 0.97 H-MFI / 100 0.542 0.354 H-MFI / 50 0.754 0.433 H-MFI / 30 0.414 0.673 H-MFI / 11.9 0.402 0.695 H-MFI-Mn / 20-OH 0.840 0.422

[0119] Table 12 Dynamic adsorption capacity and adsorption selectivity of samples for ethane and ethylene at 298K

[0120]

[0121] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be considered as being limited to the specific forms described in the embodiments.

Claims

1. A modified activated transition metal molecular sieve, characterized in that The invention adopts a molecular sieve doped with a transition metal as a matrix, and the matrix is modified by a substance containing an active functional group so that the active functional group is grafted onto the matrix, wherein the active functional group of the substance containing the active functional group is at least one of NH-, NH2- or COOH-; The transition metal-doped molecular sieve matrix comprises a substance having the following chemical composition molar ratio: mSiO2:XO, wherein X is a divalent transition metal, and the molar ratio of SiO2 to XO is m=10-30; The divalent transition metal X includes one or more of Ni, Mn, Cu, and Zn elements, and the molar ratio of SiO2 to XO is m=15-25; The modified activated transition metal molecular sieve has an MFI molecular sieve configuration recognized by the International Molecular Sieve Association (IZA), and as determined by X-ray diffraction, the molecular sieve has characteristic peaks within at least the following four interplanar spacings (d): a first interplanar spacing d=11.0±0.3, a second interplanar spacing d=9.9±0.2, a third interplanar spacing d=4.3±0.2, and a fourth interplanar spacing d=3.8±0.2; The process of modifying the transition metal-doped molecular sieve matrix by using a substance containing an active functional group is as follows: the substance containing an active functional group and the transition metal-doped molecular sieve matrix are dispersed in a solvent, stirred at a temperature between room temperature and 80° C. for 3-40 hours, and then solid-liquid separation is performed. The solid is washed with ethanol and dried, and activation is completed. The ratio of the amount of the active functional group NH, NH2- or COOH- in the substance containing active functional groups to the mass of the molecular sieve matrix doped with transition metals is 0.4-4:1, the unit of the amount of the substance is mmol, and the unit of mass is g.

2. A modified activated transition metal molecular sieve according to claim 1, characterized in that The divalent transition metal X is Mn, and the molar ratio of SiO2 to XO is m=20.

3. The modified activated transition metal molecular sieve according to claim 1, characterized in that The substance containing active functional groups is ethanolamine, diethanolamine, 3-(2-aminoethyl)-aminopropylmethyldimethoxysilane, formic acid, oxalic acid or lactic acid, and the solvent is ethanol, toluene, N,N-dimethylformamide or deionized water.

4. A modified activated transition metal molecular sieve according to claim 3, characterized in that The substance containing active functional groups is formic acid or oxalic acid.

5. A modified activated transition metal molecular sieve according to claim 1, characterized in that The transition metal-doped molecular sieve matrix is prepared according to the following steps: 1) An alkaline template agent and deionized water are sequentially added to a reactor, heated and stirred to fully dissolve and mix, and then a transition metal X salt and a silicon source in the above molecular sieve composition are added according to the molar ratio of SiO2:XO oxide. After stirring and aging, an initial gel solution is obtained. The initial gel solution is transferred to a sealed reactor and subjected to a hydrothermal synthesis reaction to obtain a transition metal-doped molecular sieve precursor solid-liquid mixture; the alkaline template agent is tetrapropylammonium hydroxide; 2) filtering, washing, and drying the molecular sieve precursor after the reaction in step 1), and then calcining it in air at a high temperature to remove organic matter in the molecular sieve precursor, thereby obtaining the transition metal-doped molecular sieve.

6. A modified activated transition metal molecular sieve according to claim 5, characterized in that In step 1), the mass ratio of deionized water to tetrapropylammonium hydroxide is 2-6:1; the mass of tetrapropylammonium hydroxide is 20-35% of the mass of the silicon source raw material, and the silicon source is TEOS; In step 1), the aging time is selected to be 12-24 hours; the aging temperature is selected to be room temperature; the reaction temperature of the hydrothermal synthesis is 180-220° C.; the reaction time of the hydrothermal synthesis is the molecular sieve crystal stability time, which is selected to be 2.8-3.2 hours.

7. A modified activated transition metal molecular sieve according to claim 6, characterized in that In step 1), the mass ratio of deionized water to tetrapropylammonium hydroxide is 3-3.5:1; the mass of tetrapropylammonium hydroxide is 25-30% of the mass of the silicon source raw material; In step 1), the aging time is selected to be 12-16 hours; the reaction temperature of the hydrothermal synthesis is 200° C.; and the reaction time of the hydrothermal synthesis is 3 hours.

8. The modified activated transition metal molecular sieve according to claim 5, characterized in that The calcination temperature of high-temperature calcination is 400-700°C, and the calcination time is selected to be 2-12h.

9. A modified activated transition metal molecular sieve according to claim 8, characterized in that The calcination temperature of high temperature calcination is 500-600°C, and the calcination time is selected to be 3-8h.

10. A modified activated transition metal molecular sieve according to claim 9, characterized in that The calcination time is selected to be 4-7h.

11. The use of a modified activated transition metal molecular sieve according to claim 1, characterized in that The molecular sieve is used for selective adsorption separation of ethane-ethylene mixed gas, and preferentially adsorbs a large amount of ethane gas in the mixed gas.

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