An aluminum-based metal-organic framework material, a preparation method, an adsorption separation device and a method for separating a hydrocarbon mixture

Abstract

The present application relates to a kind of aluminum-based metal-organic framework material, preparation method, adsorption separation device and the method for separating hydrocarbon mixture.The chemical formula of the aluminum-based metal-organic framework material is C 54 H 33 Al3O 21 It is a kind of super-microporous metal-organic framework material, belongs to tetragonal system.This material shows significant advantages in the selective separation and purification of C6 isomers, and is the first metal-organic framework material that can separate single-branched and double-branched C6 at normal temperature and pressure with high efficiency so far.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of new materials and their applications, and more particularly relates to an aluminum-based metal-organic framework material, a preparation method, an adsorption separation device, and a method for separating a hydrocarbon mixture. BACKGROUND

[0002] Energy shortage and environmental pollution are world-wide problems faced by human society, and are also major challenges to be solved for China to achieve sustainable development. The chemical separation processes (such as distillation) in industry consume 10-15% of the world's total energy consumption every year. Developing energy-saving alternative technologies, such as adsorption separation, is expected to reduce the energy consumption required for chemical separation processes, while reducing carbon dioxide emissions and environmental pollution. These industrial separation processes are closely related to the national economy and social development, such as the separation of hydrocarbons in the oil refining process, which is listed as one of the seven chemical separation processes that can change the world. Among them, the separation of alkane (mainly C5 and C6 alkane) isomers is an important process for improving the octane number of gasoline in industry. Alkane isomers are one of the components of gasoline. In the petroleum refining process, catalytic isomerization produces a mixture of alkanes with different degrees of branching. Generally, alkane isomers with higher degrees of branching have higher octane numbers. Therefore, in order to achieve a higher octane number of gasoline components and improve the anti-knock performance of gasoline, it is necessary to separate molecules with lower degrees of branching from the mixture of alkane isomers and return them to the catalytic isomerization unit. At present, distillation technology is widely used in industry to separate alkane isomers, but due to the close boiling points of alkane isomers, the distillation separation process is complex and energy-consuming. Therefore, in order to reduce the energy consumption required for separation and reduce costs, it is urgent to develop more efficient, energy-saving and environmentally friendly separation technologies.

[0003] At present, the simulated moving bed technology with 5A molecular sieve as adsorbent has been used for the separation of alkane isomers in the oil refining process, but its application range is not wide, especially in domestic oil companies, which still mainly uses distillation separation. The reason is that first, the pore volume of 5A molecular sieve is not large enough, so its adsorption capacity is not high enough. Its saturated adsorption capacity for n-hexane at room temperature is about 16wt%, and the dynamic adsorption capacity at 150℃ is about 8wt%. Increasing the adsorption capacity of the adsorbent material can increase the processing capacity of the adsorption separation device, and thus improve the efficiency of the adsorption unit. More importantly, since 5A molecular sieve does not adsorb branched alkanes, it cannot separate single-branched alkanes and double-branched alkanes, thereby failing to further improve the octane number of isomerized oil and increase its practical value. Therefore, in order to improve the efficiency of the adsorption separation unit and make the adsorption separation technology widely used, it is urgent to develop new adsorbent materials that can efficiently separate alkane isomers.

[0004] Metal-Organic Frameworks (MOFs) as a new type of crystalline porous material, due to its high specific surface area / pore volume, surface function diversity, pore shape and size easy to control, etc. In the field of adsorption, separation, etc. Show great application potential. The high specific surface area / pore volume of MOFs, and the size and size of the channel are highly adjustable, which makes it become a potential alternative material to solve the bottleneck of adsorption separation performance of molecular sieve material. So far, there is no MOF material that can well solve the efficient separation problem of C6 single branched and double branched. For example, Fe2(BDP)3 and Zr-abtc can separate C6 single branched and double branched from thermodynamics due to different affinities, but the selectivity is low, and the flexibility of Ca-tcpb structure can separate C6 single branched and double branched by programmed temperature separation, but this process is complex and requires high temperature, which consumes a lot of energy. SUMMARY

[0005] The main technical problem solved by the present application is to provide an aluminum-based metal-organic framework material, which is a new type of crystalline porous material, to solve the problem of limited types and adsorption separation performance of separation and adsorption materials in the existing adsorption and separation fields.

[0006] Another technical problem solved by the present application is to provide a method for preparing an aluminum-based metal-organic framework material to obtain a new type of crystalline porous material, to solve the problem of limited types and adsorption separation performance of separation and adsorption materials in the existing adsorption and separation fields.

[0007] Still another technical problem solved by the present application is to provide an adsorption and separation device to solve the problem of inefficient separation of hydrocarbon mixtures in the prior art.

[0008] The technical problem solved by the present application is also to provide a method for separating a hydrocarbon mixture to solve the problem of inefficient separation of hydrocarbon mixtures in the prior art.

[0009] To solve the above technical problems, the technical scheme adopted by the present application is:

[0010] An aluminum-based metal-organic framework material has the chemical formula C 54 H 33 Al3 O 21 It is a super-microporous metal-organic framework material belonging to the orthorhombic system.

[0011] The structural formula of the aluminum-based metal-organic framework material is Figure 1 The crystal structure formula shown in the figure; the structural formula of the aluminum-based metal-organic framework material has ccca space group.

[0012] The aluminum-based metal-organic framework material is a metal-organic framework material prepared by a solvothermal reaction with 4,4',4''-(phenyl-1,3,5-trioxo)-benzoic acid bttotb as an organic ligand and an aluminum salt as a metal ion source.

[0013] In the structure of the aluminum-based metal-organic framework material, each Al ion center is coordinated with 4 O atoms from carboxylate and 2 O atoms from hydroxyl anion to form a one-dimensional angular shared AlO6 octahedral array; the one-dimensional chain is further connected with the organic ligand bttob to form a three-dimensional network structure with two square one-dimensional channels; the aluminum-based metal-organic framework material has two different one-dimensional channels.

[0014] The aluminum-based metal-organic framework material is prepared by a solvothermal reaction with the organic ligand 4,4',4''-(phenyl-1,3,5-trioxo)-benzoic acid bttotb, an aluminum salt, a solvent and an acid in a molar ratio of aluminum salt: organic ligand: acid: solvent = 1:(0.5-5):(50-1000):(100-1000).

[0015] The aluminum-based metal-organic framework material is a white powder crystal; the thermal decomposition temperature of the aluminum-based metal-organic framework material is close to 500 DEG C; the specific surface area of the aluminum-based metal-organic framework material is 500-800 m 2 / g; and the pore size of the aluminum-based metal-organic framework material is The aluminum-based metal-organic framework material can completely separate C6 alkane single branched chain and double branched chain at normal temperature and pressure by molecular sieve separation; the aluminum-based metal-organic framework material preferentially adsorbs straight chain of C6, then adsorbs single branched chain, and finally adsorbs or does not adsorb double branched chain.

[0016] The application provides a method for preparing an aluminum-based metal-organic framework material, which comprises the following steps: mixing and dissolving an aluminum salt, an organic ligand bttotb, an organic solvent and an acid in a certain proportion, and performing a solvothermal reaction to obtain a product, which is the aluminum-based metal-organic framework material.

[0017] The method further comprises:

[0018] After the solvothermal reaction is completed, the product is obtained by washing with an organic solvent, and then performing suction filtration and drying; or

[0019] After the solvothermal reaction is completed, in order to remove the reaction solvent molecules existing in the channel of the product structure, vacuum drying or solvent exchange followed by vacuum drying is performed;

[0020] The aluminum salt is at least one of aluminum nitrate, aluminum chloride and aluminum sulfate.

[0021] The organic solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, and N,N-diethylformamide; and the acid is at least one of formic acid, acetic acid, hydrochloric acid, and benzoic acid.

[0022] The solvothermal reaction temperature is 80-200 DEG C, and the reaction time is 12-168 hours.

[0023] The application provides an adsorption separation device, which comprises an adsorption column, and an adsorbent filled in the adsorption column is the aluminum-based metal-organic framework material.

[0024] The application provides a method for separating a hydrocarbon mixture, which comprises the following steps: a mixed gas containing C6 alkane isomers is passed through the adsorption separation device at 0-200 DEG C and 0-5 bar pressure, double-branched C6 isomers preferentially penetrate the adsorption column to obtain double-branched products with high octane number, then single-branched C6 products begin to overflow to obtain single-branched products with high octane number, C6 straight-chain components are enriched, and the straight-chain components adsorbed in the adsorbent are eluted by a desorption method to obtain C6 straight-chain gas; thus, the adsorbent can effectively separate C6 branched chains and straight chains.

[0025] The technical scheme has at least the following beneficial effects:

[0026] The application designs and synthesizes a novel ultramicroporous metal-organic framework material, which has a chemical formula of C 54 H 33 Al3 O 21 The ultramicroporous metal-organic framework material belongs to an orthorhombic system and a ccca space group. The material has significant advantages in the selective separation and purification of C6 isomers, is the first metal-organic framework material that can separate single-branched and double-branched C6 at normal temperature and pressure with high efficiency, and can therefore obtain high-quality high-octane gasoline blending components. In addition, the material has strong stability and can be easily produced on a large scale, and can meet the production requirements of industrialization. The material synthesized in the application solves the problems of low separation efficiency, high energy consumption and high pollution of C6 isomers, provides a new method for preparing high-octane gasoline blending components, and has great application prospects in the petroleum and chemical industry. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a crystal structure diagram of the Al-bttotb in the application (there are two different one-dimensional channels A and B).

[0028] Figure 2 It is a schematic diagram of selective adsorption of C6 alkane isomers by the pore aluminum-based metal-organic framework material Al-bttotb in the application.

[0029] Figure 3 Figure 1 is an X-ray diffraction pattern of Al-bttotb, a sample of Al-bttotb obtained in Example 1 of the present application, and an X-ray diffraction pattern of the sample after stability test; the abscissa is the 2 theta angle in degrees, and the ordinate is the intensity of diffraction.

[0030] Figure 4 Figure 2 is a thermogravimetric curve of Al-bttotb obtained in Example 1 of the present application; the abscissa is temperature, and the ordinate is the change in mass in percentage.

[0031] Figure 5 Figure 3 is a nitrogen adsorption-desorption isotherm of Al-bttotb obtained in Example 1 of the present application at 77 K; the abscissa is the relative pressure of nitrogen under test conditions, and the ordinate is the adsorption amount in milliliter per gram.

[0032] Figure 6 Figure 4 is a pore size distribution of Al-bttotb obtained in Example 1 of the present application; the abscissa is the pore size, and the ordinate is the differential adsorption amount with respect to the pore size.

[0033] Figure 7 Figure 5 is an adsorption isotherm of Al-bttotb obtained in Example 1 of the present application at 30°C for n-hexane (nHEX), 3-methylpentane (3MP), and 2,2-dimethylbutane (22DMB); the abscissa is the relative pressure of the adsorbed vapor under test conditions, and the ordinate is the adsorption amount.

[0034] Figure 8 Figure 6 is an adsorption kinetics curve of Al-bttotb obtained in Example 1 of the present application at 30°C for nHEX, 3MP, and 22DMB; the abscissa is the adsorption time, and the ordinate is the adsorption amount.

[0035] Figure 9 Figure 7 is a multi-component breakthrough curve of Al-bttotb obtained in Example 1 of the present application for a ternary mixture of nHEX, 3MP, and 22DMB; the abscissa is time, and the ordinate is the ratio of the concentration of the adsorbate component at the outlet of the adsorption column to the initial concentration.

[0036] Figure 10 Figure 8 is a multi-component breakthrough curve of Al-bttotb obtained in Example 1 of the present application for a quinary mixture of nHEX, 2-methylpentane (2MP), 3MP, 22DMB, and 2,3-dimethylbutane (23DMB); the abscissa is time, and the ordinate is the ratio of the concentration of the adsorbate component at the outlet of the adsorption column to the initial concentration. DETAILED DESCRIPTION

[0037] The application designs and prepares a novel ultra-microporous metal-organic framework material, i.e., an aluminum-based metal-organic framework material, which is a separation adsorption material with high stability and good separation of C6 single branched chain and double branched chain, and can be applied to the preparation of high-octane gasoline in the petrochemical industry.

[0038] The aluminum-based metal-organic framework material of the application is prepared by using 4,4',4”-(benzene-1,3,5-triyltris(oxy))tribenzoic acid (abbreviated as bttotb) as an organic ligand, an aluminum salt as a metal ion source, N,N-dimethylformamide (abbreviated as DMF) or N,N-diethylformamide (abbreviated as DEF) as a solvent, and an acid as an adjusting agent; wherein the molar ratio of the aluminum salt: the organic ligand: the acid: the solvent is 1:(0.5-5):(50-1000):(100-1000), and a novel structure is prepared by a solvothermal reaction (reaction temperature: 80-200 DEG C).

[0039] The organic ligand bttotb is 4,4',4”-(benzene-1,3,5-trioxo)-benzoic acid, and the structural formula is shown in the following formula (1).

[0040]

[0041] The aluminum-based metal-organic framework material (Al-bttotb) of the application is an ultra-microporous metal-organic framework material, and the chemical formula is C 54 H 33 Al3 O 21 , which belongs to an orthorhombic system and a ccca space group. Figure 1 Referring to the structure diagram of the aluminum-based metal-organic framework material Al-bttotb shown in the drawing. Each Al ion center in the material structure of Al-bttotb is coordinated with 4 O atoms from carboxylate (bttotb) and 2 O atoms from hydroxyl anion to form a one-dimensional angular shared AlO6 octahedral array. The one-dimensional chain is further connected with the organic ligand bttob to form a three-dimensional network structure with two square one-dimensional channels.

[0042] The raw materials required for preparing the aluminum-based metal-organic framework material Al-bttotb of the application are low in price, the preparation process is simple, and the material can be easily produced in large scale, so that the production requirements of industrialization can be met.

[0043] The aluminum-based metal-organic framework material Al-bttotb has strong stability, and has good stability in a high-temperature, water vapor environment and immersion in water.

[0044] The aluminum-based metal-organic framework material Al-bttotb can realize high-selectivity separation of single branched chains and double branched chains of C6 through molecular sieving, has a significant advantage in selective separation and purification of C6 isomers, and can separate the single branched chains and double branched chains of C6 at a high efficiency under normal temperature and pressure.

[0045] The aluminum-based metal-organic framework material synthesized in the application solves the problems of low separation efficiency of C6 isomers, high energy consumption and high pollution, provides a new method for preparing high-octane gasoline blending components, and has a great application prospect in the petroleum and chemical industry.

[0046] The method for preparing the ultra-microporous aluminum-based metal-organic framework material mainly comprises the following steps: mixing aluminum salt, organic ligand bttotb, organic solvent and acid in a proportion, dissolving through ultrasonic or stirring, and then pouring into a reaction kettle or other closed container such as a glass bottle to perform a solvothermal reaction.

[0047] In some embodiments, after the solvothermal reaction is completed, the product can be washed with an organic solvent for multiple times, and then dried through suction filtration to obtain the required product.

[0048] Preferably, in order to remove the reaction solvent molecules existing in the pores of the product structure, vacuum drying or vacuum drying after solvent exchange can be performed to remove the reaction solvent molecules, so as to obtain the ultra-microporous metal-organic framework material Al-bttotb.

[0049] The aluminum salt is at least one of aluminum nitrate, aluminum chloride and aluminum sulfate.

[0050] The solvent is at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA) and N,N-diethylformamide (DEF).

[0051] The acid can be at least one of formic acid, acetic acid, hydrochloric acid and benzoic acid.

[0052] The solvothermal reaction temperature is 80-200 DEG C, and the reaction time is 12-168 hours.

[0053] The ultrasonic or stirring condition is not particularly limited.

[0054] The solution used for organic solvent washing or solvent exchange can be at least one of methanol, dichloromethane, and ethanol.

[0055] The temperature for vacuum drying is 80-250 DEG C, and the time is 6-24 hours.

[0056] The ultra-microporous aluminum metal-organic framework material prepared by the method is pure, free of impurities, and has a regular morphology, and can be used as an adsorbent material for separating a hydrocarbon mixture and completely screening straight-chain, single-branched-chain, and double-branched-chain isomers of C6 alkanes.

[0057] The application provides a molecular sieve made of the above aluminum metal-organic framework material, which is used as an adsorbent and can efficiently separate a hydrocarbon mixed gas, in particular, a mixed gas containing straight-chain, single-branched-chain, and double-branched-chain isomers of C6 alkanes. Figure 2 The prepared ultra-microporous aluminum metal-organic framework material Al-bttotb can selectively adsorb straight-chain and single-branched-chain components of C6 alkane isomers and less or not adsorb double-branched-chain components, so that the straight-chain, single-branched-chain, and double-branched-chain components of C6 alkane isomers can be separated.

[0058] The aluminum metal-organic framework material is used as an adsorbent in the petroleum industry to separate gasoline, and straight-chain, single-branched-chain, and double-branched-chain isomers of C6 alkanes are adsorbed and separated to obtain high-quality gasoline blending components with high octane number.

[0059] The application also provides a method for separating a hydrocarbon mixture, in particular, a method for separating straight-chain, single-branched-chain, and double-branched-chain isomers of C6 alkanes, wherein the aluminum metal-organic framework material is used as an adsorbent to adsorb and separate straight-chain, single-branched-chain, and double-branched-chain isomers of C6 alkanes to obtain high-quality gasoline blending components with high octane number.

[0060] The method for separating a hydrocarbon mixture is realized by an adsorption separation device, and any one of fluidized bed adsorption, moving bed adsorption, and fixed bed adsorption is mainly used. Preferably, the moving bed adsorption is used. The adsorption separation device comprises an adsorption column, and the adsorbent filled in the adsorption column is the aluminum metal-organic framework material. Preferably, the separation temperature of the adsorption column is 0-200 DEG C, and the total pressure of the separated mixed gas is 0-5 bar. Preferably, the adsorption separation temperature is 20-150 DEG C, and the total pressure of the mixed gas is 0.05-0.5 bar.

[0061] The method for separating a hydrocarbon mixed gas comprises the following steps:

[0062] The mixed gas containing C6 alkane isomers of straight chain (normal hexane), single branched chain (2-methylpentane, 3-methylpentane) and double branched chain (2,2-dimethylbutane, 2,3-dimethylbutane) is passed through a fixed bed adsorption column filled with an adsorbent (the prepared ultra-microporous aluminum-based metal-organic framework material) at a certain temperature and pressure at a certain flow rate. Since normal hexane interacts more strongly with the adsorbent pores, the single branched chain interacts less strongly with the adsorbent pores, and the kinetic size of the double branched chain is larger than the pore size, therefore the adsorbent preferentially adsorbs the straight chain of C6, then adsorbs the single branched chain, and less or does not adsorb the double branched chain, that is, the double branched chain preferentially penetrates the fixed bed, so that the double branched chain product with high octane number and high purity can be directly obtained. Subsequently, the single branched chain product also begins to overflow, and the single branched chain product with high octane number can be obtained, realizing effective separation of the C6 branched chain and straight chain by the adsorbent.

[0063] The C6 straight chain component interacts strongly with the adsorbent, and therefore is enriched in the fixed bed. After the penetration, the straight chain component adsorbed in the adsorbent can be eluted out by heating, vacuum treatment, inert gas purging or a combination of various desorption methods, so as to obtain a high-purity C6 straight chain gas.

[0064] The separation temperature is 0-200℃, and the total pressure of the mixed gas is 0-5bar. Preferably, the adsorption separation temperature is 20-150℃, and the total pressure of the mixed gas is 0.05-0.5bar.

[0065] The mixed gas to be separated is not limited to containing only C6 alkane isomers, and can also contain other gases such as oxygen, nitrogen, helium, carbon dioxide, water vapor and methane.

[0066] The adsorbent of the present application can be regenerated only by desorption treatment.

[0067] The raw materials used in the aluminum-based metal-organic framework material of the present application are low in price, mild in conditions, simple in synthesis process, and the product is pure and can be prepared on a large scale. The aluminum-based metal-organic framework material has excellent stability, and the decomposition temperature is close to 500℃. Whether exposed to high temperature of 180℃ for 7 days, exposed to air with relative humidity of 90% for 7 days, or placed in water at 80℃ for 7 days, the structure remains intact and the performance of adsorption separation does not decrease significantly.

[0068] The present application is the only metal-organic framework material that can completely separate C6 alkane single branched chain and double branched chain by molecular sieving at normal temperature and pressure. The separation method provided by the present application can obtain C6 double branched chain component with a purity of up to 99.5%, C6 straight chain component with a purity of up to 99.5%, and gasoline blending component with an octane number of up to 95.

[0069] The separation method has the advantages of low cost, energy saving, environmental protection, simple operation and the like compared with the low-temperature rectification method commonly used at present, and is expected to bring quality and economic benefit improvement of petrochemical enterprises in preparation of high-octane gasoline blending components.

[0070] The preparation of the aluminum-based metal-organic framework material and the application thereof in separating hydrocarbon mixed gas are specifically described below by non-limiting examples.

[0071] Example 1

[0072] 1 mmol of aluminum nitrate nonahydrate and 0.4 mmol of 4,4',4”-(phenyl-1,3,5-trioxo)-benzoic acid were added into a mixed solution composed of 10 mL of formic acid and 20 mL of N,N-dimethylformamide, stirred for 30 min, then transferred into a 100 mL reaction kettle, and then placed into an oven at 150 DEG C for reaction for 72 h, and then filtered to obtain white powder crystals after cooling.

[0073] In order to remove the solvent existing in the crystal channel, the material obtained by filtration was soaked in a methanol solution for 48 h, and the N,N-dimethylformamide solvent in the channel of the material was fully replaced by methanol, and then the material after solvent exchange was filtered and vacuum degassed at 120 DEG C for 12 h to obtain the aluminum-based metal-organic framework material from which the solvent was removed, which can be used as a new adsorbent.

[0074] In order to test the specific surface area and pore size distribution of the above-synthesized adsorbent, the above-degassed adsorbent material (aluminum-based metal-organic framework material) was subjected to nitrogen adsorption-desorption isotherm test at 77 K. Please refer to Figure 5 The nitrogen adsorption-desorption isotherm of the Al-bttotb obtained in the example at 77 K was tested, and the specific surface area of the material was 500-800 m2 / g, the adsorption amount sharply rose in the low pressure region and then tended to be balanced, indicating that the material was a microporous material.

[0075] Please refer to Figure 6 The pore size distribution graph of the Al-bttotb obtained in the example can be seen, and the pore size of the Al-bttotb obtained in the example is about

[0076] Please refer to Figure 3, X-ray diffraction patterns of Al-bttotb simulated according to the structure, and X-ray diffraction patterns of the Al-bttotb sample obtained in the example and the sample after stability test. In order to test the stability of the adsorbent synthesized above, the adsorbent obtained above was respectively placed in an oven at 180°C, water at a temperature of 80°C, and air at room temperature with a humidity of 90%, and after being placed for 7 days, X-ray diffraction analysis test was performed. The test results showed that the three kinds of treated materials still maintained complete crystal structure, indicating good stability.

[0077] Thermogravimetric test was performed on the Al-bttotb obtained in the example and the sample after solvent exchange. Please refer to Figure 4 , the thermogravimetric curve shown in Figure 4 , it can be seen that the material can withstand high temperature of 500°C and has excellent thermal stability. The first weight loss platform of the sample after solvent exchange is at 50°C, while the weight loss platform of the Al-bttotb without solvent exchange is at about 170°C, which shows that the material after solvent exchange can lose solvent molecules at a lower temperature.

[0078] Please refer to Figure 7 , in order to test the adsorption separation performance of the adsorbent synthesized above in the example, Al-bttotb obtained in example 1 was used as the adsorbent, and the adsorbent after desorption treatment was respectively tested for single-component adsorption isotherm of nHEX, 3MP and 22DMB. Under the test environment of temperature of 30°C and pressure of 1 bar, the adsorption amount of nHEX was 151 mg / g, the adsorption amount of 3MP was 94 mg / g, and 22DMB was almost not adsorbed. The selectivity of nHEX / 22DMB was 63, and the selectivity of 3MP / 22DMB was 44.

[0079] Please refer to Figure 8 , Al-bttotb obtained in example 1 was used as the adsorbent, and the adsorption kinetics curve of nHEX, 3MP and 22DMB at 30°C was tested. The adsorption speed of nHEX was very fast, and the adsorption amount reached 21 mg / g at 25 s; the adsorption speed of 3MP was also fast, and the adsorption amount reached 14 mg / g at 100 s, and 22DMB was not adsorbed.

[0080] Please refer to Figure 9To test the actual separation effect of the adsorbent on C6 alkane isomers, the Al-bttotb obtained in Example 1 was used as the adsorbent, and the desorbed adsorbent was subjected to a multi-component breakthrough experiment of a ternary mixed gas of nHEX, 3MP and 22DMB. In this experiment, an equimolar ternary mixture of nHEX, 3MP and 22DMB was passed through an adsorption column filled with the adsorbent using helium as the carrier gas, the test temperature was 30°C, the pressure was 1 bar, and the flow rate of the mixed gas was 1 mL / min. It was found that 22DMB was breakthrough at the beginning, 3MP was breakthrough at the 23rd minute, and nHEX was breakthrough at the 100th minute. The material can effectively separate nHEX, 3MP and 22DMB, and can obtain 22DMB component with a purity of more than 99.5%, and can obtain gasoline blending component with an octane number of more than 90.

[0081] Reference Figure 10 To further test the separation effect of the adsorbent material on C6 alkane isomers, the Al-bttotb obtained in Example 1 was used as the adsorbent, and the desorbed adsorbent was subjected to a multi-component breakthrough experiment of a quinary mixed gas of nHEX, 2MP (2-methylpentane), 3MP, 22DMB and 23DMB (2,3-dimethylbutane). In this experiment, an equimolar quinary mixture of nHEX, 2MP, 3MP, 22DMB and 23DMB was passed through an adsorption column filled with the adsorbent using helium as the carrier gas, the test temperature was 30°C, the pressure was 1 bar, and the flow rate of the mixed gas was 1 mL / min. It was found that 22DMB was breakthrough at the beginning, 23DMB was breakthrough at the 4th minute, 2MP and 3MP were breakthrough at the 15th minute, and nHEX was breakthrough at the 106th minute. The material can effectively separate nHEX, 2MP, 3MP, 22DMB and 23DMB, and can obtain 22DMB component with a purity of more than 99.0%, and can obtain gasoline blending component with an octane number of more than 90.

[0082] Example 2

[0083] 1.6 mmol of aluminum nitrate nonahydrate and 0.8 mmol of 4,4',4”-(phenyl-1,3,5-trioxo)-benzoic acid were added to a mixed solution of 3 mL of formic acid and 30 mL of N,N-dimethylformamide, and after ultrasonic treatment for 30 min, the mixture was transferred to a 50 mL glass bottle, the bottle cap was tightened, and then the glass bottle was placed in an oven at 120°C for 50 hours. After cooling, a white powder crystal was obtained by filtration.

[0084] The aluminum-based metal-organic framework material Al-bttotb prepared in the above process was further vacuum degassed at 180°C for 10 hours to obtain a solvent-removed aluminum-based metal-organic framework material Al-bttotb. The aluminum-based metal-organic framework material Al-bttotb prepared in this example can be used as a new type of adsorbent material as an adsorbent. In order to test the adsorption separation performance of the adsorbent synthesized in this example, the desorbed adsorbent Al-bttotb of this example was used to test the single-component adsorption isotherms of nHEX, 3MP and 22DMB, respectively. Under the test conditions of a temperature of 50°C and a pressure of 0.5 bar, the adsorption amount of nHEX was 142 mg / g, the adsorption amount of 3MP was 82 mg / g, and there was almost no adsorption of 22DMB. The selectivity of nHEX / 22DMB was 60, and the selectivity of 3MP / 22DMB was 42.

[0085] In order to test the actual separation effect of the adsorbent on C6 alkane isomers, the desorbed adsorbent Al-bttotb of this example was used to perform a multi-component breakthrough experiment of a ternary mixed gas of nHEX, 3MP and 22DMB. In this experiment, an equimolar ternary mixture of nHEX, 3MP and 22DMB was passed through an adsorption column filled with the adsorbent with helium as the carrier gas, and the test temperature was 50°C, the pressure was 1 bar, and the flow rate of the mixed gas was 0.5 mL / min. It was tested that 22DMB penetrated at the beginning, 3MP started to penetrate at the 31st minute, and nHEX started to penetrate at the 120th minute. The material Al-bttotb prepared in this example can effectively separate nHEX, 3MP and 22DMB, and can obtain a 22DMB component with a purity of more than 99.5% and a gasoline blending component with an octane number of more than 90.

[0086] Example 3

[0087] 4 mmol of aluminum nitrate nonahydrate and 1.5 mmol of 4,4',4”-(phenyl-1,3,5-trioxo)-benzoic acid were added to a mixed solution composed of 35 mL of formic acid and 80 mL of N,N-dimethylformamide, stirred for 30 min, then transferred to a 250 mL reaction kettle, and then placed in an oven at 160°C for reaction for 50 hours. After cooling, white powder crystals were obtained by filtration.

[0088] The Al-bttotb material prepared in the above process was further vacuum degassed at 130 °C for 15 hours to obtain the solvent-free metal-organic framework material Al-bttotb. The aluminum-based metal-organic framework material Al-bttotb prepared in this example can be used as a new type of adsorbent material as an adsorbent. In order to test the adsorption separation performance of the above synthesized adsorbent Al-bttotb, the above desorbed adsorbent Al-bttotb was used to test the single-component adsorption isotherms of nHEX, 3MP, and 22DMB, respectively. Under the test environment of a temperature of 25 °C and a pressure of 1 bar, the adsorption amount of nHEX was 162 mg / g, the adsorption amount of 3MP was 101 mg / g, and 22DMB was almost not adsorbed. The selectivity of nHEX / 22DMB was 58, and the selectivity of 3MP / 22DMB was 38.

[0089] In order to test the actual separation effect of the adsorbent Al-bttotb on C6 alkane isomers, the above desorbed adsorbent Al-bttotb was used to perform a multi-component breakthrough experiment of a ternary mixed gas of nHEX, 3MP, and 22DMB. In this experiment, an equimolar ternary mixture of nHEX, 3MP, and 22DMB was passed through an adsorption column filled with the adsorbent with helium as the carrier gas, the test temperature was 50 °C, the pressure was 1 bar, and the flow rate of the mixed gas was 0.5 mL / min. It was tested that 22DMB penetrated at the beginning, 3MP started to penetrate at the 31st minute, and nHEX started to penetrate at the 120th minute. The material Al-bttotb prepared in this example can effectively separate nHEX, 3MP, and 22DMB, and can obtain 22DMB components with a purity of more than 99.5% and gasoline blending components with an octane number of more than 90.

[0090] Example 4

[0091] 0.7 mmol of aluminum nitrate nonahydrate and 0.4 mmol of 4,4',4”-(phenyl-1,3,5-trioxo)-benzoic acid were added to a mixed solution composed of 1.6 mL of formic acid and 14 mL of N,N-dimethylformamide, stirred for 60 min, transferred to a 25 mL reaction kettle, and then the reaction kettle was placed in an oven at 130 °C for reaction for 60 hours. After cooling, white powder crystals were obtained by filtration.

[0092] The material Al-bttotb prepared in the above process was further vacuum degassed at 160 °C for 9 hours to obtain the solvent-free metal-organic framework material Al-bttotb. The aluminum-based metal-organic framework material Al-bttotb prepared in this example can be used as a new type of adsorbent material as an adsorbent. In order to test the adsorption separation performance of the adsorbent Al-bttotb synthesized in this example, the above-mentioned desorbed adsorbent Al-bttotb was used to test the single-component adsorption isotherm of nHEX, 22DMB, respectively. Under the test environment of temperature 80 °C and pressure 1 bar, the adsorption capacity of nHEX is 122 mg / g, while 22DMB has almost no adsorption. The selectivity of nHEX / 22DMB is 57.

[0093] In order to test the actual separation effect of the adsorbent Al-bttotb on C6 alkane isomers, the above-mentioned desorbed adsorbent Al-bttotb was used to carry out a multi-component breakthrough experiment of nHEX and 22DMB binary mixed gas. In this experiment, an equimolar binary mixture of nHEX and 22DMB was passed through the adsorption column filled with the adsorbent with helium as the carrier gas, the test temperature was 80 °C, the pressure was 1 bar, and the mixed gas flow rate was 1.5 mL / min. It was tested that 22DMB penetrated at the beginning, while nHEX started to penetrate at 120 minutes. The material Al-bttotb prepared in this example can effectively separate nHEX and 22DMB, and can obtain 22DMB component with a purity of more than 99.5% and gasoline blending component with an octane number of more than 90.

[0094] Example 5

[0095] 0.25 mmol of aluminum nitrate nonahydrate and 0.1 mmol of 4,4',4”-(phenyl-1,3,5- trioxo)-benzoic acid were added to a mixed solution composed of 2 mL of formic acid and 5 mL of N,N-dimethylformamide, and ultrasonically dispersed for 45 min, then transferred to a 20 mL reaction kettle, and then placed in an oven at 140 °C for reaction for 80 hours. After cooling, a white powder crystal was obtained by filtration.

[0096] The material Al-bttotb prepared in the above process was degassed at 120°C for 8 hours under vacuum after solvent exchange with methanol as solvent to obtain the solvent-free metal-organic framework material Al-bttotb. The aluminum metal-organic framework material Al-bttotb prepared in this example can be used as a new type of adsorbent material as an adsorbent. In order to test the adsorption separation performance of the adsorbent Al-bttotb synthesized in this example, the above desorbed adsorbent Al-bttotb was used to test the single-component adsorption isotherms of 3MP and 22DMB, respectively. The adsorption capacity of 3MP was 108 mg / g at a temperature of 0°C and a pressure of 1 bar, while the adsorption of 22DMB was almost zero. The selectivity of 3MP / 22DMB was 46.

[0097] In order to test the actual separation effect of the adsorbent Al-bttotb on C6 alkane isomers, the desorbed adsorbent Al-bttotb of this example was used to perform a multi-component breakthrough experiment of ternary mixed gas of 3MP and 22DMB. In this experiment, the ternary mixture of equimolar nHEX, 3MP and 22DMB was passed through the adsorption column filled with the adsorbent with helium as the carrier gas, the test temperature was 0°C, the pressure was 1 bar, and the flow rate of the mixed gas was 0.35 mL / min. The test results showed that 22DMB penetrated at the beginning, and 3MP started to penetrate at the 35th minute. The material Al-bttotb prepared in this example can effectively separate 3MP and 22DMB, and can obtain 22DMB component with a purity of more than 99.5%, and can obtain gasoline blending component with an octane number of more than 90.

[0098] The above is a specific embodiment of the present application. It should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements are also considered within the scope of protection of the present application.

Claims

1. An aluminum-based metal-organic framework material characterized in that, The chemical formula of the aluminum-based metal-organic framework material is C 54 H 33 Al3 O 21 It is an ultra-microporous metal-organic framework material, belonging to the orthorhombic system; the aluminum-based metal-organic framework material is a metal-organic framework material prepared by a solvothermal reaction with 4,4',4''-(phenyl-1,3,5-trioxo)-benzoic acid bttotb as an organic ligand and an aluminum salt as a metal ion source; The structure formula of the aluminum-based metal-organic framework material is a crystal structure formula shown in Figure 1; the structure formula of the aluminum-based metal-organic framework material has a ccca space group; In the structure of the aluminum-based metal-organic framework material, each Al ion center is coordinated with 4 O atoms from carboxylate and 2 O atoms from hydroxyl anion to form a one-dimensional angular shared AlO6 octahedral array; the one-dimensional chain is further connected with an organic ligand bttob to form a three-dimensional network structure with two square-shaped one-dimensional channels; the aluminum-based metal-organic framework material has two different one-dimensional channels, and the pore size of the channels is 5.6 angstroms; The aluminum-based metal-organic framework material is a white powder crystal; the thermal decomposition temperature of the aluminum-based metal-organic framework material is close to 500 DEG C; the specific surface area of the aluminum-based metal-organic framework material is 500-800 m 2 / g; at normal temperature and pressure, the aluminum-based metal-organic framework material can realize complete separation of C6 alkane single branched chain and double branched chain through molecular sieve separation, and preferentially adsorbs straight chain of C6 alkane, then adsorbs single branched chain of C6 alkane, and finally adsorbs or does not adsorb double branched chain of C6 alkane; after separation, the purity of C6 alkane double branched chain product is greater than or equal to 99.5%, the purity of C6 alkane straight chain product is less than or equal to 99.5%, and the aluminum-based metal-organic framework material can be used for preparing gasoline blending component with octane number greater than or equal to 95. After the aluminum-based metal-organic framework material is placed in a high-temperature environment at 180 DEG C for 7 days, placed in a 90% relative humidity environment for 7 days, or soaked in water at 80 DEG C for 7 days, the crystal structure remains complete, and the adsorption separation performance does not decrease significantly.

2. The aluminum-based metal-organic framework material of claim 1, wherein, The aluminum-based metal-organic framework material is prepared by solvothermal reaction of an organic ligand 4,4',4''-(phenyl-1,3,5-trioxo)-benzoic acid bttotb, an aluminum salt, a solvent, and an acid, in a molar ratio of aluminum salt: organic ligand: acid: solvent = 1: (0.5-5): (50-1000): (100-1000).

3. The aluminum-based metal-organic framework material of claim 1 or 2, wherein The preparation method of the aluminum-based metal-organic framework material comprises the following steps: 1) aluminum salt, organic ligand bttotb, acid, and organic solvent are mixed in a molar ratio of aluminum salt: organic ligand bttotb: acid: organic solvent = 1: (0.5-5): (50-1000): (100-1000), dissolved by ultrasonic or stirring to obtain a mixed solution; the aluminum salt is at least one of aluminum nitrate, aluminum chloride, and aluminum sulfate; the organic solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, and N,N-diethylformamide; the acid is at least one of formic acid, acetic acid, hydrochloric acid, and benzoic acid; 2) the mixed solution obtained in step 1) is transferred to a sealed container, and solvothermal reaction is carried out at 80-200 DEG C for 12-168 hours, and then filtered after cooling to obtain white powder crystals; 3) the white powder crystals obtained in step 2) are post-treated: washed with an organic solvent, then dried by suction filtration, or vacuum dried at 80-250 DEG C for 6-24 hours, or first solvent exchanged with at least one of methanol and dichloromethane, and then vacuum dried at 80-250 DEG C for 6-24 hours to remove the reaction solvent molecules in the crystal channels, to obtain the aluminum-based metal-organic framework material.

4. A method of preparing an aluminiferous metal-organic framework material as claimed in any one of claims 1 to 3, comprising the steps of: The product obtained by mixing and dissolving aluminum salt, organic ligand bttotb, organic solvent, and acid in a certain proportion and carrying out solvothermal reaction is an aluminum-based metal-organic framework material.

5. The method of claim 4, wherein The method further comprises: after the solvothermal reaction is completed, the product is obtained by washing with an organic solvent and then dried by suction filtration; or After the end of the solvothermal reaction, in order to remove the reaction solvent molecules existing in the pores of the product structure, the solvent is removed by vacuum drying or solvent exchange followed by vacuum drying; The aluminum salt is at least one of aluminum nitrate, aluminum chloride, and aluminum sulfate; The organic solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, and N,N-diethylformamide; The acid can be at least one of formic acid, acetic acid, hydrochloric acid, and benzoic acid; The solvothermal reaction temperature is 80-200°C, and the reaction time is 12-168 hours.

6. An adsorptive separation device, characterized by The adsorption separation device comprises an adsorption column, and the adsorbent filled in the adsorption column is the aluminum-based metal-organic framework material according to any one of claims 1-3; the adsorption separation device can adopt a fluidized bed adsorption, a moving bed adsorption, or a fixed bed adsorption mode, and the adsorbent can be regenerated.

7. A method for separating a hydrocarbon mixture, comprising the following steps: 1) Preheat a mixed gas containing C6 alkane isomers including C6 alkane straight chain, C6 alkane single branched chain, and C6 alkane double branched chain to 0-200°C, and adjust the total pressure of the mixed gas to 0-5 bar; 2) Pass the mixed gas pretreated in step 1) into the adsorption separation device according to claim 6 at a set flow rate, and collect the outlet gas of the adsorption column to obtain a C6 alkane double branched chain product with a purity of ≥99.5%, because the C6 alkane double branched chain in the mixed gas has a kinetic size larger than the pore size of the adsorbent; 3) As the time of passing in increases, the C6 alkane single branched chain product in the mixed gas begins to overflow the adsorption column, and the outlet gas of the adsorption column at this time is collected to obtain a C6 alkane single branched chain product; 4) The C6 alkane straight chain is enriched in the adsorption column because of strong interaction with the adsorbent pores, and after the C6 alkane straight chain penetrates the adsorption column, the straight chain component adsorbed in the adsorbent is eluted by heating or vacuum treatment or inert gas purging or a combination of multiple desorption methods to obtain a high-purity C6 straight chain gas; The mixed gas can contain at least one of oxygen, nitrogen, helium, carbon dioxide, water vapor, and methane.

Images