WO2021196258A1 - Aluminum-based metal-organic skeleton material and preparation method therefor, adsorption separation device, and method for separating hydrocarbon mixture - Google Patents

Abstract

Disclosed are an aluminum-based metal-organic skeleton material and a preparation method therefor, an adsorption and separation device using the material as an adsorbent, and a method for separating a hydrocarbon mixture. The aluminum-based metal-organic skeleton material has a chemical formula of C54H 33Al3O21, and is an ultramicroporous metal-organic framework material, belonging to the tetragonal system. The material exhibits significant advantages in the selective separation and purification of C6 isomers, and is a metal-organic framework material which is capable of separating C6 single-branch and double-branch isomers at a higher efficiency at room temperature and atmospheric pressure.

Description

Aluminum-based metal-organic framework material, preparation method, adsorption separation device and method for separating hydrocarbon mixture Technical field

The invention belongs to a new material and its application field, and more specifically relates to an aluminum-based metal organic framework material, a preparation method, an adsorption separation device and a method for separating hydrocarbon mixtures.

Background technique

Energy shortage and environmental pollution are world-wide problems facing human society, and they are also major challenges that my country must solve to achieve sustainable development. Industrial chemical separation processes (such as distillation) consume 10-15% of the world's total energy consumption each year. The development of energy-saving alternative technologies, such as adsorption separation, is expected to reduce the energy consumption required in the chemical separation process, while reducing carbon dioxide emissions and environmental pollution. Most of these industrial separation processes are closely related to the national economy and social development. For example, the separation of hydrocarbons in the oil refining process is listed as one of the seven chemical separation processes that can change the world. Among them, the separation of isomers of alkanes (mainly C5 and C6 alkanes) is an important process for industrially increasing the octane number of gasoline. Alkane isomers are one of the components of gasoline. In the petroleum refining process, the catalytic isomerization reaction produces a mixture of alkanes with different degrees of branching. Generally, the more branched alkane isomers have a higher octane number. Therefore, in order to make gasoline components reach a higher octane number and improve the anti-knock performance of gasoline, it is necessary to separate molecules with a lower degree of branching from the mixture of alkane isomers and return them to the catalytic isomerization.化processing unit. At present, distillation technology is widely used in industry to separate alkane isomers, but because the boiling points of alkane isomers are relatively close, the distillation separation process is more complicated and energy consumption is high. Therefore, in order to reduce the energy consumption and cost of separation, it is urgent to develop more efficient, energy-saving and environmentally friendly separation technology.

At present, the simulated moving bed technology with 5A molecular sieve as the adsorbent has been used for the separation of alkane isomers in the refining process, but the application range is not wide, especially in domestic oil companies, which still focus on distillation separation. The reason is that, firstly, the pore volume of 5A molecular sieve is not large enough, making its adsorption capacity 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%, which improves the adsorption capacity. The adsorption capacity of the agent material can increase the processing capacity of the adsorption separation device, thereby increasing the efficiency of the adsorption unit; more importantly, because the 5A molecular sieve does not adsorb branched alkanes, it cannot separate single branched alkanes and double branched alkanes. Therefore, it is impossible to further increase the octane number of the isomerized oil and increase its practical value. Therefore, in order to improve the performance of the adsorption separation unit and enable the adsorption separation technology to be widely used, there is an urgent need to develop a new type of adsorbent material that can efficiently separate alkane isomers.

Metal-Organic Frameworks (MOFs) are a new type of crystalline porous material. Due to their high specific surface area/pore volume, surface functional diversity, easy adjustment of pore shape and size, etc., they are used in adsorption, separation, etc. The field shows great application potential. The high specific surface area/pore volume, and adjustable pore size and height of MOFs make them a potential alternative material to solve the bottleneck of the adsorption and separation performance of molecular sieve materials. Up to now, there is no MOFs material that can well solve the C6 single branch. The problem of efficient separation of chain and double-branched chain. For example, Fe ₂ (BDP) ₃ and Zr-abtc can be separated thermodynamically due to their different affinities for C6 single-branched and double-branched chains, but the selectivity is low. Using the flexibility of the Ca-tcpb structure, it can pass the program Separating C6 single-branched alkanes and double-branched alkanes at elevated temperature, but this process is complicated, requires higher temperatures, and consumes a lot of energy.

Summary of the invention

The main purpose of the present invention is to provide an aluminum-based metal organic framework material, which is a new type of crystalline porous material, to solve the problems of the types of separation adsorption materials and the limitation of adsorption and separation performance in the existing adsorption and separation fields .

Another object of the present invention is to provide a method for preparing aluminum-based metal organic framework materials to obtain a new type of crystalline porous material, which solves the limitation of the types of separation and adsorption materials and their adsorption and separation performance in the fields of adsorption and separation. And other issues.

Another object of the present invention is to provide an adsorption separation device to solve the problem that the prior art cannot efficiently separate hydrocarbon mixtures.

The present invention also aims to provide a method for separating hydrocarbon mixtures to solve the problem that the prior art cannot efficiently separate hydrocarbon mixtures.

The present invention provides an aluminum-based metal-organic framework material with a chemical formula of C ₅₄ H ₃₃ Al ₃ O ₂₁ , which is an ultra-microporous metal-organic framework material and belongs to the tetragonal system.

The structural formula of the aluminum-based metal-organic framework material is the crystal structural formula shown in FIG. 1; the structural formula of the aluminum-based metal-organic framework material has the ccca space group.

The aluminum-based metal-organic framework material uses 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid bttotb as an organic ligand and aluminum salt as a source of metal ions. A metal-organic framework material prepared by solvothermal reaction.

In the structure of the aluminum-based metal-organic framework material, each Al ion center coordinates with 4 O atoms from carboxylate and 2 from hydroxyl anions to form a one-dimensional angle shared AlO ₆ octahedral array; the one-dimensional chain is further It is connected with the organic ligand bttob to form a three-dimensional network structure with two square one-dimensional pores; the aluminum-based metal-organic framework material has two different one-dimensional pores.

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

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°C; the specific surface area of the aluminum-based metal-organic framework material is 500-800m ² /g; The pore size of the aluminum-based metal-organic framework material is

The aluminum-based metal-organic framework material achieves complete separation of C6 alkane single-branched and double-branched chains by molecular sieving under normal temperature and pressure; the aluminum-based metal-organic framework material preferentially adsorbs C6 straight chains, and then adsorbs single-branched Chains, and finally the double-branched chains are less adsorbed or not adsorbed.

The present invention provides a method for preparing aluminum-based metal-organic framework material, which includes the following steps: mixing and dissolving aluminum salt, organic ligand bttotb, organic solvent, and acid in proportions, and the product obtained by solvothermal reaction is aluminum-based metal -Organic framework materials.

The method also includes:

After the solvothermal reaction is completed, wash with an organic solvent, and dry by suction filtration to obtain the product; or

After the solvothermal reaction is completed, in order to remove the reaction solvent molecules present in the pores of the product structure, it is removed by vacuum drying or solvent exchange and then 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 formic acid, acetic acid, hydrochloric acid , At least one of benzoic acid;

The solvothermal reaction temperature is 80-200°C, and the reaction time is 12-168 hours.

The present invention provides an adsorption separation device, including an adsorption column, the adsorbent filled in the adsorption column is the aluminum-based metal-organic framework material; the adsorbent can be regenerated.

The present invention provides a method for separating hydrocarbon mixtures, comprising the following steps: the mixed gas containing C6 alkane isomers is separated at 0-200°C and 0-5bar pressure through the adsorption as claimed in claim 9 In the device, C6 double-branched chains preferentially penetrate the adsorption column to directly obtain high-octane double-branched products, and then C6 single-branched products begin to overflow and obtain a high-octane single-branched and double-branched mixture Gas, so as to realize the effective separation of C6 branched and straight chain by adsorbent.

The above technical solutions have at least the following beneficial effects:

The present invention designs and synthesizes a new type of ultra-microporous metal-organic framework material with a chemical formula of C ₅₄ H ₃₃ Al ₃ O _21. The ultra-microporous metal-organic framework material belongs to the tetragonal crystal system and the ccca space group. This material shows significant advantages in the selective separation and purification of C6 isomers, and is the first to date to separate C6 single-branched and double-branched metals with high efficiency under normal temperature and pressure. Organic framework materials, so high-quality high-octane gasoline blending components can be obtained. In addition, the material has strong stability and is easy to mass produce, which can meet the requirements of industrial production. The material synthesized by the present invention solves the problems of low separation efficiency of C6 isomers, high energy consumption, high pollution, etc., provides a new method for preparing high-octane gasoline blending components, and has huge advantages in the petrochemical industry Application prospects.

Description of the drawings

Figure 1 is a diagram of the crystal structure of Al-bttotb of the present invention (there are two different one-dimensional channels A and B).

2 is a schematic diagram of the selective adsorption of C6 alkane isomers by the porous aluminum-based metal-organic framework material Al-bttotb of the present invention.

Figure 3 is the theoretical X-ray diffraction pattern of Al-bttotb, the Al-bttotb sample obtained in Example 1 of the present invention and the X-ray diffraction pattern of the sample after stability testing; the abscissa is 2 angles in the X-ray diffraction test, the unit Is degrees; the ordinate is the diffraction intensity.

Figure 4 is the thermogravimetric curve of Al-bttotb obtained in Example 1 of the present invention; wherein the abscissa is temperature, the ordinate is mass change, and the unit is percentage.

Figure 5 is the nitrogen adsorption-desorption isotherm of Al-bttotb obtained in Example 1 of the present invention at 77K; the abscissa is the relative pressure of nitrogen under the test conditions; the ordinate is the adsorption amount, in ml/g.

Fig. 6 is a pore size distribution diagram of Al-bttotb obtained in Example 1 of the present invention; the abscissa is the pore size, and the ordinate is the differential of the adsorption amount to the pore size.

Figure 7 is the adsorption isotherm of Al-bttotb obtained in Example 1 of the present invention for n-hexane (nHEX), 3-methylpentane (3MP), and 2,2-dimethylbutane (22DMB) at 30°C; The abscissa is the relative pressure of the adsorbed steam under the test conditions; the ordinate is the adsorption capacity.

Figure 8 is the adsorption kinetic curve of Al-bttotb obtained in Example 1 of the present invention on nHEX, 3MP, and 22DMB at 30°C; where the abscissa is the adsorption time and the ordinate is the adsorption amount.

Figure 9 is the multi-component penetration curve of Al-bttotb to the ternary mixture of nHEX, 3MP and 22DMB obtained in Example 1 of the present invention; where the abscissa is time, and the ordinate is the concentration of adsorbate component at the outlet of the adsorption column and its initial concentration ratio.

Figure 10 shows the multi-component penetration of Al-bttotb obtained in Example 1 of the invention to the pentad mixture of nHEX, 2-methylpentane (2MP), 3MP, 22DMB and 2,3-dimethylbutane (23DMB) Curve; where 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 its initial concentration.

Detailed ways

The present invention accurately designs and prepares a new type of ultra-microporous metal-organic framework material, namely aluminum-based metal-organic framework material, which is a single-branched and double-branched material with high stability and good separation of C6. The branched separation and adsorption material can be used in the petrochemical industry to prepare high-octane gasoline. The C6 alkane isomers and their related physical properties are shown in Table 1:

Table 1 C6 alkane isomers and their physical properties

The aluminum-based metal-organic framework material of the present invention is based on 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid (4,4',4"-(benzene- 1,3,5-triyltris(oxy))tribenzoicacid (abbreviated as bttotb) is used as organic ligand, aluminum salt is used as the source of metal ions, and N,N-dimethylformamide (abbreviated as DMF) or N,N- Diethylformamide (abbreviated as DEF) and other solutions are used as solvents and acid is used as regulator; among them, the molar ratio of aluminum salt: organic ligand: acid: solvent is: 1: (0.5-5): (50-1000) ): (100-1000), through solvothermal reaction (reaction temperature: 80-200°C), the prepared one has a brand-new structure. Aluminum-based metal-organic framework material (Al-bttotb) can be used to efficiently separate hydrocarbon mixtures.

The organic ligand bttotb, 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid, the structural formula is as follows (1)

The aluminum-based metal-organic framework material (Al-bttotb) of the present invention is an ultra-microporous metal-organic framework material with a chemical formula of C ₅₄ H ₃₃ Al ₃ O ₂₁ , belonging to the tetragonal crystal system, and ccca space group. Refer to the structure diagram of the aluminum-based metal-organic framework material Al-bttotb shown in FIG. 1. In the Al-bttotb material structure, each Al ion center coordinates with 4 O atoms from carboxylate (bttotb) and 2 O atoms from hydroxyl anion to form a one-dimensional angular common AlO ₆ 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 pores. The aluminum-based metal-organic framework material Al-bttotb has two different one-dimensional channels, A and B. The size of the one-dimensional pore structure is approximately

The preparation of the aluminum-based metal-organic framework material Al-bttotb of the present invention requires low raw material prices, simple preparation process, easy mass production, and can meet industrial production requirements.

The aluminum-based metal-organic framework material Al-bttotb of the present invention has strong stability, and has good stability in high temperature, water vapor environment and immersion in water.

The aluminum-based metal-organic framework material Al-bttotb of the present invention can achieve high selective separation of C6 single-branched and double-branched chains through molecular sieving, and is remarkable in the selective separation and purification of C6 isomers The advantage of C6 single-branched and double-branched C6 can be separated with higher efficiency under normal temperature and pressure. The aluminum-based metal-organic framework material Al-bttotb is used in the petrochemical industry to prepare high-octane gasoline, and high-quality high-octane gasoline blending components can be obtained.

The aluminum-based metal-organic framework material synthesized by the present invention solves the problems of low separation efficiency of C6 isomers, high energy consumption, high pollution, etc., and provides a new method for preparing high-octane gasoline blending components. It has huge application prospects in the petrochemical industry.

The method for preparing ultra-microporous aluminum-based metal-organic framework material mainly includes the following steps: mixing aluminum salt, organic ligand bttotb, organic solvent, acid in proportion, dissolving by ultrasonic or stirring, and putting it into a reactor or glass bottle, etc. Solvothermal reactions are carried out in other airtight containers. After cooling, it was filtered to obtain white powder crystals.

In some embodiments, after the solvothermal reaction is completed, an organic solvent can be used for washing multiple times, and the desired product can be obtained by suction filtration and drying.

Preferably, in order to remove the reaction solvent molecules present in the pores of the product structure, it can be removed by vacuum drying or solvent exchange followed by vacuum drying to obtain the ultra-microporous metal-organic framework material Al-bttotb.

Wherein, the aluminum salt is at least one of aluminum nitrate, aluminum chloride, and aluminum sulfate.

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

The acid may 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.

Adjust proper ultrasound or stirring to fully dissolve and mix the materials, and the conditions of ultrasound or stirring are not particularly limited.

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

The temperature of vacuum drying is 80-250°C, and the time is 6-24 hours.

The ultra-microporous aluminum-based metal-organic framework material prepared by the present invention is pure, free of impurities, and has regular morphology. And double-branched isomers are screened completely.

The present invention provides a molecular sieve made of the above-mentioned aluminum-based metal-organic framework material, which can be used as an adsorbent to efficiently separate hydrocarbon gas mixtures, in particular to separate direct, single-branched and double-branched homologous hydrocarbons containing C6 alkanes. Mixed gas of isomers. Refer to Figure 2: The prepared ultra-microporous aluminum-based metal-organic framework material Al-bttotb can selectively adsorb the linear and single-branched components of C6 alkane isomers with little or no adsorption of double-branched components Therefore, it is possible to separate straight-chain, single-branched and double-branched components of C6 alkane isomers.

Aluminum-based metal-organic framework materials are used as adsorbents for the separation of gasoline in the petroleum industry. The direct-connected, single-branched and double-branched isomers of C6 alkanes are adsorbed and separated to obtain higher octane High-quality gasoline blending components.

The present invention also provides a method for separating a hydrocarbon mixture, especially a method for separating the straight-linked, single-branched and double-branched isomers of C6 alkanes, wherein the aluminum-based metal-organic framework material is an adsorbent, Adsorption and separation of the C6 alkane's direct-linked, single-branched and double-branched isomers to obtain high-quality gasoline blending components with a higher octane number.

The method for separating hydrocarbon mixtures of the present invention is realized by an adsorption separation device, and mainly adopts any one of fluidized bed adsorption, moving bed adsorption and fixed bed adsorption. Preferably, it is a moving bed adsorption. The adsorption separation device includes an adsorption column, and the adsorbent filled in the adsorption column is the aluminum-based metal-organic frame material of the present invention. Preferably, the separation temperature of the adsorption column is 0-200°C, and the total pressure of the separated mixed gas is 0-5 bar. Preferably, the temperature of the adsorption separation is 20-150°C, and the total pressure of the mixed gas is 0.05-0.5 bar.

The method for separating hydrocarbon mixed gas of the present invention includes the following steps:

The straight chain (n-hexane), single-branched chain (2-methylpentane, 3-methylpentane) and double-branched chain (2,2-dimethylbutane, 2 ,3-dimethylbutane) at a certain temperature and pressure, at a certain flow rate through the fixed bed adsorption column filled with adsorbent (prepared ultra-microporous aluminum-based metal-organic framework material), because The interaction between n-hexane and the pores of the adsorbent is relatively strong. The single-branched chain and the pores of the adsorbent are relatively weak. The kinetic size of the double-branched chain is larger than the pore size. Therefore, the adsorbent preferentially adsorbs C6 linear chains, and then adsorbs single-branched chains. Adsorption or non-adsorption of the double-branched chain, that is, the double-branched chain preferentially penetrates the fixed bed, therefore, the double-branched product with high purity and high octane can be directly obtained. Subsequently, the single-branched products also began to overflow, and single-branched products with higher octane values can be obtained, and the effective separation of C6 branched and straight chains by the adsorbent can be realized.

The C6 linear component has a strong interaction with the adsorbent. Therefore, it will be enriched in the fixed bed. After it finally penetrates, it can be combined by heating, vacuum treatment, inert gas purging or a combination of multiple desorption methods. The linear components adsorbed in the adsorbent are eluted to obtain high-purity C6 linear gas.

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

The mixed gas to be separated is not limited to only containing C6 alkane isomers, but may also contain other gases such as oxygen, nitrogen, helium, carbon dioxide, water vapor, methane and the like.

The adsorbent of the present invention can be regenerated only after desorption treatment.

The aluminum-based metal-organic framework material involved in the present invention uses raw materials with low price, mild conditions, simple synthesis process, pure product and large-scale preparation. The aluminum-based metal-organic frame material involved in the present invention has excellent stability, and the decomposition temperature is close to 500°C, whether it is exposed to a high temperature of 180°C for 7 days, exposed to air with a relative humidity of 90% for 7 days, or After being placed in 80°C water for 7 days, the structure can still be kept intact and the performance of adsorption and separation has not significantly decreased.

The present invention is currently the only metal-organic framework material that can completely separate C6 alkane single-branched and double-branched C6 alkanes by molecular sieving under normal temperature and pressure. The separation method provided by the present invention can obtain C6 with a purity of up to 99.5%. Double-branched components and C6 straight-chain components with a purity of up to 99.5% can obtain gasoline blending components with an octane number above 90.

Compared with the currently commonly used cryogenic distillation method, the separation method provided by the present invention has the advantages of low cost, energy saving, environmental protection, simple operation, etc., and is expected to bring quality and economic benefits to petrochemical enterprises in the preparation of high-octane gasoline blending components. promote.

The preparation of the aluminum-based metal-organic framework material and the application of the present invention to the separation of hydrocarbon mixed gas will be specifically illustrated below by non-limiting examples.

Example 1

Add 1mmol of aluminum nitrate nonahydrate and 0.4mmol of 4,4',4”-(phenyl-1,3,5-trioxo)-benzoic acid to 10mL formic acid and 20mL N,N-dimethylformamide After stirring the mixed solution for 30 minutes, it was transferred to a 100 mL reactor, and then placed in an oven at 150° C. for reaction for 72 hours. After cooling, it was filtered to obtain white powder crystals.

In order to remove the solvent in the crystal pores, the filtered material was soaked in methanol solution for 48 hours, the N,N-dimethylformamide solvent in the material pores was fully replaced by methanol, and then the solvent exchanged material After filtration, vacuum degassing at 120°C for 12 hours to obtain the solvent-removed aluminum-based metal-organic framework material, which can be used as a new type of adsorbent.

In order to test the specific surface area and pore size distribution of the synthesized adsorbent, the degassed adsorbent material (aluminum-based metal-organic framework material) was subjected to a nitrogen adsorption-desorption isotherm test at 77K. Please refer to Figure 5, the nitrogen adsorption-desorption isotherm of Al-bttotb obtained in this example at 77K. After testing, the specific surface area of the material is 500-800m2/g, and the adsorption capacity rises sharply in the low pressure zone and then tends to equilibrium , Indicating that the material is a microporous material.

Referring to Figure 6, the pore size distribution diagram of Al-bttotb obtained in this embodiment shows that the pore size of Al-bttotb obtained in the embodiment is about

Please refer to FIG. 3, the X-ray diffraction pattern simulated according to the Al-bttotb structure and the X-ray diffraction pattern of the Al-bttotb sample obtained in this embodiment and the stable test of the sample. In order to test the stability of the above synthesized adsorbents, the adsorbents prepared above were placed in an oven at 180°C, in water at a temperature of 80°C, and in air with a humidity of 90% at room temperature. They were all placed for 7 days. X-ray diffraction analysis tests were performed, and the test results showed that the three processed materials still maintained a complete crystal structure, indicating good stability.

The Al-bttotb obtained in this example and the sample after solvent exchange are subjected to thermogravimetric test. Please refer to Figure 4. It can be seen from the thermogravimetric curve shown in Figure 4 that the material can withstand a high temperature of 500°C and has excellent thermal stability. After solvent exchange, the first weight loss platform cuts off at 50°C, while the weight loss platform of Al-bttotb without solvent exchange cuts off at about 170°C, which means that the material after solvent exchange can lose solvent molecules at a lower temperature. .

Referring to Figure 7, in order to test the adsorption and separation performance of the above-mentioned synthetic adsorbent in this example, the Al-bttotb obtained in Example 1 was used as the adsorbent, and the adsorbent subjected to the desorption treatment was subjected to single-component nHEX, 3MP, and 22DMB. In the test of adsorption isotherm, the adsorption capacity of nHEX is 151mg/g, the adsorption capacity of 3MP is 94mg/g, and the adsorption capacity of 22DMB is almost no adsorption under the test environment with temperature of 30℃ and pressure of 1bar. The selectivity of nHEX/22DMB is 63, the selectivity of 3MP/22DMB is 44.

Referring to Figure 8, using Al-bttotb obtained in Example 1 as the adsorbent, the adsorption kinetic curve of nHEX, 3MP, and 22DMB was tested at 30°C. The adsorption speed of nHEX was very fast, and the adsorption capacity reached 21mg/g in 25s; 3MP The adsorption speed is also faster, the adsorption amount reaches 14mg/g in 100s, but 22DMB does not adsorb.

Referring to Figure 9, in order to 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 adsorbent subjected to the desorption treatment was subjected to nHEX, 3MP and 22DMB. Multi-component penetration experiment of mixed gas. In this experiment, a ternary mixture of equimolar nHEX, 3MP and 22DMB was passed through the adsorption column filled with adsorbent by helium gas. The test temperature was 30°C, the pressure was 1 bar, and the mixed gas flow rate was 1 mL/min. After testing, 22DMB penetrated at the beginning. At the 23rd minute, 3MP began to penetrate, while nHEX began to penetrate at 100 minutes. This material can effectively separate nHEX, 3MP and 22DMB and obtain purity. More than 99.5% of 22DMB component, and can obtain gasoline blending component with octane number higher than 90.

10, in order to further aggravate the separation effect of the above-mentioned adsorbent materials on C6 alkane isomers, the Al-bttotb obtained in Example 1 was used as the adsorbent, and the adsorbent subjected to the desorption treatment was subjected to nHEX, 2MP(2 -Methylpentane), 3MP, 22DMB, 23DMB (2,3-dimethylbutane) pentad mixed gas multi-component penetration experiment. In this experiment, a five-element mixture of equimolar nHEX, 2MP, 3MP, 22DMB, and 23DMB was passed through the adsorption column filled with adsorbent by helium gas. The test temperature was 30°C, the pressure was 1 bar, and the mixed gas flow rate was 1 mL/min. After testing, 22DMB (2,2-dimethylbutane) penetrated at the beginning, at the 4th minute, 23DMB (2,3-dimethylbutane) penetrated, at the 15th minute When 2MP (2-methylpentane) and 3MP (3-methylpentane) penetrate, and at 106 minutes, nHEX (n-hexane) starts to penetrate. This material can penetrate nHEX, 2MP, 3MP, Effective separation of 22DMB and 23DMB can obtain 22DMB components with a purity of more than 99.0%, and gasoline blending components with an octane number of more than 90 can be obtained.

Example 2

Add 1.6mmol of aluminum nitrate nonahydrate, 0.8mmol of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid to 3mL formic acid and 30mL N,N-dimethylformaldehyde After sonicating the mixed solution composed of amide for 30 minutes, it was transferred to a 50 mL glass bottle, the cap was tightened, and the glass bottle was placed in an oven at 120° C. for reaction for 50 hours. After cooling, it was filtered to obtain white powder crystals.

The aluminum-based metal-organic framework material Al-bttotb prepared by the above process is further vacuum degassed at 180° C. for 10 hours to obtain the solvent-removed aluminum-based metal-organic framework material Al-bttotb. The aluminum-based metal-organic framework material Al-bttotb prepared in this embodiment can be used as a new type of adsorbent and used as an adsorbent. In order to test the adsorption and separation performance of the adsorbent synthesized in this example, the desorption-treated adsorbent Al-bttotb of this example was used to test the single-component adsorption isotherms of nHEX, 3MP, and 22DMB. The adsorption capacity of nHEX under the test environment at 50°C and 0.5 bar pressure is 142 mg/g, the adsorption capacity of 3MP is 82 mg/g, and 22DMB has almost no adsorption. The selectivity of nHEX/22DMB is 60, and the selectivity of 3MP/22DMB is 42.

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 carry out the multi-component penetration experiment of nHEX, 3MP and 22DMB ternary mixed gas . In this experiment, the ternary mixture of equimolar nHEX, 3MP and 22DMB was passed through the adsorption column filled with adsorbent by helium gas. The test temperature was 50°C, the pressure was 1 bar, and the mixed gas flow rate was 0.5 mL/min. After testing, 22DMB penetrated at the beginning. At the 31st minute, 3MP began to penetrate, while nHEX only began to penetrate at 120 minutes. Effective separation of 22DMB can obtain 22DMB components with a purity of more than 99.5% and gasoline blending components with an octane number higher than 90.

Example 3

Add 4mmol of aluminum nitrate nonahydrate and 1.5mmol of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid to 35mL formic acid and 80mL N,N-dimethylformamide After stirring the mixed solution for 30 minutes, it was transferred to a 250 mL reactor, and then placed in an oven at 160° C. for reaction for 50 hours. After cooling, it was filtered to obtain white powder crystals.

The Al-bttotb material prepared by the above process is further vacuum degassed at 130° C. for 15 hours to obtain the solvent-removed metal-organic framework material Al-bttotb. The aluminum-based metal-organic framework material Al-bttotb prepared in this embodiment can be used as a new type of adsorbent and used as an adsorbent. In order to test the adsorption and separation performance of the above-mentioned synthetic adsorbent Al-bttotb, the desorption-treated adsorbent Al-bttotb was used to test the single-component adsorption isotherms of nHEX, 3MP, and 22DMB respectively. At a temperature of 25℃, The adsorption capacity of nHEX under the test environment with a pressure of 1 bar is 162 mg/g, the adsorption capacity of 3MP is 101 mg/g, and 22DMB has almost no adsorption. The selectivity of nHEX/22DMB is 58, and the selectivity of 3MP/22DMB is 38.

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 the multi-component penetration experiment of the ternary mixed gas of nHEX, 3MP and 22DMB . In this experiment, the ternary mixture of equimolar nHEX, 3MP and 22DMB was passed through the adsorption column filled with adsorbent by helium gas. The test temperature was 50°C, the pressure was 1 bar, and the mixed gas flow rate was 0.5 mL/min. After testing, 22DMB penetrated at the beginning. At the 31st minute, 3MP began to penetrate, while nHEX only began to penetrate at 120 minutes. Effective separation of 22DMB can obtain 22DMB components with a purity of more than 99.5% and gasoline blending components with an octane number higher than 90.

Example 4

Add 0.7mmol of aluminum nitrate nonahydrate and 0.4mmol of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid to 1.6mL formic acid and 14mL N,N-dimethyl In the mixed solution composed of formamide, after stirring for 60 minutes, it was transferred to a 25 mL reactor, and then the reactor was placed in an oven at 130°C for 60 hours, cooled and filtered to obtain white powder crystals.

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

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 penetration experiment of the binary mixed gas of nHEX and 22DMB. In this experiment, the binary mixture of equimolar nHEX and 22DMB was passed through the adsorption column filled with adsorbent by helium gas. The test temperature was 80°C, the pressure was 1 bar, and the mixed gas flow rate was 1.5 mL/min. After testing, 22DMB penetrated at the beginning, but nHEX began to penetrate after 120 minutes. The material Al-bttotb prepared in this example can effectively separate nHEX and 22DMB, and the purity can be as high as 99.5% or more. 22DMB component and can obtain gasoline blending component with octane number higher than 90.

Example 5

Add 0.25mmol of aluminum nitrate nonahydrate, 0.1mmol of 4,4',4”-(phenyl-1,3,5-trioxo)-benzoic acid to 2mL formic acid and 5mL N,N-dimethylformaldehyde In the mixed solution composed of amide, after ultrasonic dispersion for 45 minutes, it was transferred to a 20 mL reactor, and then placed in an oven at 140° C. for reaction for 80 hours. After cooling, it was filtered to obtain white powder crystals.

The material Al-bttotb prepared by the above process is methanol as the solvent, and the solvent is exchanged and degassed in vacuum at 120° C. for 8 hours to obtain the solvent-removed metal-organic framework material Al-bttotb. The aluminum-based metal-organic framework material Al-bttotb prepared in this embodiment can be used as a new type of adsorbent and used as an adsorbent. In order to test the adsorption and separation performance of the adsorbent Al-bttotb synthesized in this example, the adsorbent Al-bttotb subjected to the desorption treatment was used to test the single-component adsorption isotherms of 3MP and 22DMB, respectively, at a temperature of 0 The adsorption capacity of 3MP under the test environment at ℃ and 1bar pressure is 108mg/g, while 22DMB has almost no adsorption. The selectivity of 3MP/22DMB is 46.

In order to test the actual separation effect of the adsorbent Al-bttotb on C6 alkane isomers, a multi-component penetration experiment of 3MP and 22DMB ternary mixed gas was carried out using the desorbed adsorbent Al-bttotb of this example . In this experiment, the ternary mixture of equimolar nHEX, 3MP and 22DMB was passed through the adsorption column filled with adsorbent by helium gas. The test temperature was 0°C, the pressure was 1 bar, and the mixed gas flow rate was 0.35 mL/min. After testing, 22DMB penetrated at the beginning, and 3MP began to penetrate at the 35th minute. The material Al-bttotb prepared in this example can effectively separate 3MP and 22DMB, and can obtain a purity of more than 99.5%. 22DMB component, and can obtain gasoline blending components with octane number higher than 90.

The above is the specific implementation of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications are also considered. This is the protection scope of the present invention.

Claims (15)

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 Al ₃ O ₂₁ , which is a kind of ultra-microporous metal-organic framework material and belongs to tetragonal crystal Tie.
2. The aluminum-based metal-organic framework material according to claim 1, wherein the structural formula of the aluminum-based metal-organic framework material is the crystal structural formula shown in FIG. 1; the structural formula of the aluminum-based metal-organic framework material has ccca space group.
3. The aluminum-based metal-organic framework material of claim 1, wherein the aluminum-based metal-organic framework material is 4,4',4"-(phenyl-1,3,5-trioxo )-Benzoic acid bttotb is used as an organic ligand, and aluminum salt is used as a source of metal ions to prepare a metal-organic framework material through solvothermal reaction.
4. The aluminum-based metal-organic framework material according to claim 3, wherein each Al ion center in the structure of the aluminum-based metal-organic framework material is associated with 4 O from carboxylate and 2 from hydroxyl anion. Atoms coordinate to form a one-dimensional corner shared AlO ₆ 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 pores; there are two different aluminum-based metal-organic framework materials One-dimensional channel.
5. The aluminum-based metal-organic framework material of claim 3, wherein the aluminum-based metal-organic framework material is composed of an organic ligand 4,4',4"-(phenyl-1,3,5- Trioxo)-benzoic acid bttotb, aluminum salt, solvent, acid, according to the molar ratio of aluminum salt: organic ligand: acid: solvent: 1: (0.5-5): (50-1000): (100-1000 ), prepared by solvothermal reaction.
6. The aluminum-based metal-organic framework material according to any one of claims 1 to 5, wherein the aluminum-based metal-organic framework material is a white powder crystal; the heat of the aluminum-based metal-organic framework material The decomposition temperature is close to 500°C; the specific surface area of the aluminum-based metal-organic framework material is 500-800m ² /g; the pore size of the aluminum-based metal-organic framework material is

   

   The aluminum-based metal-organic framework material achieves complete separation of C6 alkane single-branched and double-branched chains by molecular sieving under normal temperature and pressure; the aluminum-based metal-organic framework material preferentially adsorbs C6 straight chains, and then adsorbs single-branched Chain, the final adsorption or non-adsorption of double-branched chains.
7. The method for preparing the aluminum-based metal-organic framework material according to any one of claims 1 to 6, comprising the following steps: mixing and dissolving aluminum salt, organic ligand bttotb, organic solvent, and acid in proportions, and performing solvothermal reaction. The product is aluminum-based metal-organic framework materials.
8. The method according to claim 7, wherein the method further comprises:

   After the solvothermal reaction is completed, wash with an organic solvent, and dry by suction filtration to obtain the product; or

   After the solvothermal reaction is completed, in order to remove the reaction solvent molecules existing in the pores of the product structure, it is removed by vacuum drying or solvent exchange and then vacuum drying.
9. The method of claim 7, wherein:

   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 may be formic acid, acetic acid, hydrochloric acid , At least one of benzoic acid;

   The solvothermal reaction temperature is 80-200°C, and the reaction time is 12-168 hours.
10. An adsorption separation device, characterized in that 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 to 6; the adsorbent has Renewability.
11. 9. The adsorption separation device of claim 10, wherein the adsorption separation device is suitable for the separation of mixed gas containing C6 alkane isomers;

    Among them, the adsorbent preferentially adsorbs C6 linear chains, and then adsorbs single-branched chains, with little or no adsorption of double-branched chains; accordingly, double-branched chains preferentially penetrate the adsorption column so as to preferentially obtain double-branched products with high octane number. , Then the single-branched product overflows to obtain a single-branched product with a higher octane number; after breakthrough, the linear components adsorbed in the adsorbent are eluted to obtain high-purity C6 linear gas.
12. The adsorption separation device of claim 10, wherein the working temperature of the adsorption column is 0-200°C, the total pressure of the mixed gas is 0-5 bar and greater than 0, and the flow rate of the mixed gas is 0.1-100 mL/min; The adsorption separation device is one of fluidized bed adsorption, moving bed adsorption or fixed bed adsorption; the adsorption separation device.
13. A method for separating hydrocarbon mixtures, comprising the following steps: passing a mixed gas containing C6 alkane isomers through the adsorption separation device according to any one of claims 10 to 12 to realize the adsorption of C6 branched and straight chains by the adsorbent Effective separation of chains.
14. The method according to claim 13, characterized in that it comprises the following steps: passing C6 alkane isomers at a predetermined flow rate through an adsorption column filled with an aluminum-based metal-organic framework material adsorbent, wherein the adsorption The agent preferentially adsorbs C6 linear chains, and then adsorbs single-branched chains, with little or no adsorption of double-branched chains; accordingly, double-branched chains preferentially penetrate the adsorption column to obtain double-branched products with high octane number. The single-branched product overflows and accordingly a single-branched product with a higher octane value is obtained; after breakthrough, the linear components adsorbed in the adsorbent are eluted through desorption to obtain high-purity C6 linear gas.
15. The method of claim 13, wherein the temperature of the adsorption separation is 20-150°C, and the total pressure of the mixed gas is 0.05-0.5 bar.

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