A method for separating a mixture of benzene, cyclohexane and cyclohexene

Abstract

The invention discloses a method for separating a mixture of benzene, cyclohexane and cyclohexene. The method includes separating a mixture containing benzene, cyclohexane and / or cyclohexene by adsorption with an adsorbent, wherein the adsorbent comprises a metal organic framework material, wherein the metal organic framework material comprises a metal ion and an organic ligand, and the organic ligand comprises 2,5-dihydroxy-1,4-benzoquinone. The method of the present invention can effectively separate a benzene-cyclohexane-cyclohexene mixture, with high separation efficiency and low energy consumption, and the organic ligands and metal salts used for preparing the metal organic framework material used in the present invention are cheap and easy to obtain, have good stability, are easy to prepare on a large scale, have high selectivity for adsorption separation, and have good industrial application prospects.

Description

Technical Field

[0001] The invention belongs to the field of adsorption separation, and in particular relates to a method for separating a mixture of benzene, cyclohexane and cyclohexene. Technical Background

[0002] Benzene, cyclohexane and cyclohexene are important organic chemical raw materials. Cyclohexane is an important raw material for producing chemical products such as cyclohexanol, cyclohexanone, polycaprolactam and polyhexamethylene adipamide, and is an excellent solvent for cellulose ether, resin, wax, grease, asphalt and rubber. Cyclohexene, as an organic synthetic raw material, can be used to synthesize lysine, cyclohexanone, phenol, polycycloolefin resin, chlorocyclohexane, rubber additives, etc. It can also be used as a catalyst solvent and petroleum extractant, and high-octane gasoline stabilizer. In addition, environmental problems are becoming increasingly prominent, and the content of aromatic hydrocarbons such as benzene in oil products is directly related to the content of volatile organic compounds and toxic substances in the exhaust gas after combustion. The removal of aromatic hydrocarbons such as benzene in oil products is also receiving more and more attention.

[0003] At present, the chemical production of cyclohexene mainly adopts the partial selective hydrogenation of benzene. 80% to 85% of the world's cyclohexane is produced by benzene hydrogenation. In order to obtain pure cyclohexane, the reaction product cyclohexane and unreacted benzene must be separated. Subsequent production units include the preparation of cyclohexanol, adipic acid, caprolactam, etc. based on the cyclohexene hydration method. In the production process of cyclohexene, benzene and cyclohexane are usually present, and the boiling points of benzene, cyclohexane and cyclohexene are similar, which are 80.1℃, 80.3℃ and 83℃ respectively. The molecular dynamic size and density of the three are close. When the mass fraction of cyclohexane is 45%, an azeotrope is formed between benzene and cyclohexane with a boiling point of 77.5℃. This system is difficult to separate by ordinary distillation, especially the separation of cyclohexane and cyclohexene is difficult. In industry, the extractive distillation method with N, N-dimethylacetamide (DMAC) as solvent is usually adopted. The conventional separation process is four-tower, or the extractive distillation tower is transformed and designed as a bulkhead tower equipment, and the original device is improved to a multi-tower combination of four-tower or five-tower process, or the step of side line extraction is added. The improved device has problems such as complex process and large floor space. The extractive distillation method has high energy consumption, high equipment requirements, difficult operation, high operating equipment cost, complex pipeline design and low separation capacity. In azeotropic distillation, an entrainer needs to be added to form an azeotrope with one of the components to achieve the purpose of separating benzene and cyclohexane. The entrainer used is mostly acetone, and this technology is only of practical value when the benzene concentration is greater than 90%.

[0004] Therefore, it is urgent to develop a method for separating benzene-cyclohexane-cyclohexene mixtures with simple process, low cost, energy saving and environmental protection. The adsorption separation method has good application prospects in industry because of its significant advantages such as simple process flow, low energy consumption, low cost, energy saving and environmental protection. As an important carrier, the adsorbent should have a high adsorption capacity and high adsorption separation selectivity for the separation of benzene-cyclohexane-cyclohexene mixtures. Commonly used adsorbents in industry include activated carbon, clay, molecular sieves, silica gel, etc. Compared with the characteristics of continuous changes in the pores and functional group positions of metal organic framework materials during the structural transformation process, the former has a uniform internal pore structure and the pores are difficult to modify, so its adsorption effect in industrial production is not obvious. Summary of the invention

[0005] After extensive research, the inventors of the present application have found that a special metal organic framework material has a high adsorption selectivity for a benzene-cyclohexane-cyclohexene mixture, and thus can effectively separate pure components from the benzene-cyclohexane-cyclohexene mixture. Based on this discovery, the present application is proposed.

[0006] In a first aspect, the present invention provides a method for separating a mixture of benzene, cyclohexane and cyclohexene, comprising separating the mixture containing benzene, cyclohexane and / or cyclohexene by adsorption using an adsorbent, wherein the adsorbent comprises a metal organic framework material, wherein the metal organic framework material comprises metal ions and organic ligands, and the organic ligands comprise 2,5-dihydroxy-1,4-benzoquinone.

[0007] According to some embodiments of the present invention, the "mixture containing benzene, cyclohexane and / or cyclohexene" comprises a mixture of two or three components of benzene, cyclohexane and cyclohexene, and the content of each component can be 0.01-99.99%. In addition to benzene, cyclohexane and cyclohexene, the "mixture containing benzene, cyclohexane and / or cyclohexene" can also include other components such as ethylbenzene, styrene, xylene isomers, toluene, etc. According to some embodiments, in the mixture containing benzene, cyclohexane and / or cyclohexene, the volume occupied by benzene is 0.01%-99.99%.

[0008] According to some embodiments of the present invention, the mixture containing benzene, cyclohexane and / or cyclohexene is in gaseous or liquid state. Preferably, the volume ratio of benzene in the mixture of benzene, cyclohexane and cyclohexene is 0.01%-99.99%. According to some embodiments, the volume ratio of benzene in the mixture containing benzene, cyclohexane and / or cyclohexene is 0.01%, 1%, 5%, 15%, 25%, 35%, 50%, 60%, 70%, 80%, 90%, 99%, 99.99%.

[0009] According to some embodiments of the present invention, the metal ions in the metal organic framework material are selected from transition metal ions and alkaline earth metal ions.

[0010] According to some embodiments of the invention, the metal ions include one or more of zinc ions, manganese ions, iron ions, cobalt ions, magnesium ions, vanadium ions, zirconium ions, calcium ions, molybdenum ions, chromium ions, iron ions, nickel ions, copper ions, tin ions, niobium ions, titanium ions or scandium ions.

[0011] According to some preferred embodiments of the present invention, the metal ions include one or more of zinc ions, iron ions, cobalt ions, magnesium ions or manganese ions.

[0012] According to a further preferred embodiment of the present invention, the metal ions include manganese ions.

[0013] According to some preferred embodiments of the present invention, the pore size of the metal organic framework material is According to some preferred embodiments of the present invention, the pore size of the metal organic framework material is preferably More preferably

[0014] According to some preferred embodiments of the present invention, the specific surface area of ​​the metal organic framework material is 300-2000m 2 According to some preferred embodiments of the present invention, the specific surface area of ​​the metal organic framework material is 300-1000m 2 / g.

[0015] According to some embodiments of the present invention, the metal organic framework material is in the shape of a cube, needle or rod. The metal organic framework material used in the present invention can be prepared into spherical, columnar, granular and other adsorption separation materials through different processing techniques.

[0016] According to some embodiments of the present invention, the temperature of the adsorption separation is -5°C to 300°C, preferably 25°C to 250°C, and more preferably 30°C to 150°C. According to some embodiments, the temperature of the adsorption separation may be 25°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C or any value therebetween.

[0017] According to some embodiments of the present invention, the pressure of the adsorption separation is 0.01MPa-10MPa, preferably 0.1MPa-6MPa. According to some embodiments, the pressure of the adsorption separation can be 0.01MPa, 0.05MPa, 0.1MPa, 0.5MPa, 1MPa, 2MPa, 3MPa, 4MPa, 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, 10MPa or any value therebetween.

[0018] According to some embodiments of the present invention, the mixture containing benzene, cyclohexane and / or cyclohexene is subjected to adsorption separation in the form of a mixed vapor or liquid of benzene-cyclohexane-cyclohexene.

[0019] According to some embodiments of the present invention, the adsorptive separation is performed using a fixed bed, wherein the adsorbent is filled in the fixed bed adsorption column.

[0020] According to some embodiments of the present invention, the adsorption separation comprises the following steps: (1) passing a mixed vapor formed by a mixture containing benzene, cyclohexane and / or cyclohexene and a carrier gas through a fixed bed adsorption column, whereby the strongly adsorbed component in the mixture is adsorbed on the adsorbent and the weakly adsorbed component in the mixture penetrates the adsorption column, thereby causing the benzene, cyclohexane and cyclohexene components to flow out of the adsorption column at different times, respectively, to obtain the weakly adsorbed component; and (2) desorbing the strongly adsorbed component from the adsorbent to obtain the strongly adsorbed component.

[0021] According to some embodiments of the present invention, the mixed vapor is composed of a mixture containing benzene, cyclohexane and / or cyclohexene and a carrier gas. According to some embodiments, the carrier gas is nitrogen and / or helium.

[0022] According to some preferred embodiments of the present invention, the flow rate of the mixed steam through the fixed bed adsorption column is 1-200 mL / min / g adsorbent.

[0023] According to some embodiments of the present invention, the weight ratio of the adsorbent to the mixture containing benzene, cyclohexane and / or cyclohexene is (1-20):1, preferably (1-10):1.

[0024] According to some embodiments of the present invention, the adsorption separation is performed using a simulated moving bed, wherein the adsorbent is filled in the adsorption zone bed layer of the simulated moving bed.

[0025] According to some embodiments of the present invention, the adsorption separation comprises the following steps: (3) subjecting a mixture liquid containing benzene, cyclohexane and / or cyclohexene to adsorption separation through a liquid phase simulated moving bed under the action of a desorbent, so that benzene, cyclohexane and cyclohexene are respectively extracted in different bed layers.

[0026] According to some embodiments of the present invention, the number of adsorbent beds of the simulated moving bed is 4-32, and the desorbent is n-octane, 2-methylheptane, 3-methylheptane, 4-methylheptane, n-nonane or n-decane.

[0027] According to some embodiments of the present invention, the adsorptive separation is performed under the conditions of changing the total pressure of the mixed vapor or liquid of benzene-cyclohexane-cyclohexene or changing the adsorption temperature of the adsorbent, or changing both simultaneously.

[0028] According to some embodiments of the present invention, in the adsorption separation, the adsorbent is kept at 30° C. to less than 60° C. The inventors found that when the working temperature T of the adsorbent is less than 60° C., when the saturated vapor pressure P of cyclohexane is less than 51.91 kPa, the interaction between cyclohexane and the adsorbent is extremely weak, and cyclohexane is quickly desorbed from the adsorbent, thereby obtaining a pure cyclohexane product. Under this condition, the interaction between cyclohexene and benzene and the adsorbent is relatively strong, and they are desorbed from the adsorbent after being retained for a certain period of time.

[0029] According to some embodiments of the present invention, in the adsorption separation, the adsorbent is kept at 60°C to less than 90°C. The inventors have found that when the working temperature T of the adsorbent satisfies 90°C>T>60°C, under this condition, the interaction force between cyclohexene and the adsorbent is stronger than that between cyclohexane, and the retention time in the adsorbent is relatively long and flows out, thereby obtaining a pure component cyclohexane product, while the interaction force between benzene and the adsorbent is relatively the strongest, and after the adsorption reaches saturation, it is slowly desorbed from the adsorbent, thereby obtaining a pure component benzene.

[0030] According to some embodiments of the present invention, in the adsorption separation, the adsorbent is kept at 90°C-150°C, preferably heated to 90-120°C to separate benzene. The inventors found that when the working temperature T of the adsorbent is greater than 90°C, the interaction between cyclohexane and cyclohexene and the adsorbent is weak, the retention time in the adsorbent is short and the cyclohexene is rapidly precipitated, while benzene still has a strong interaction with the adsorbent, thereby obtaining a single product based on the difference in retention time.

[0031] According to some embodiments of the present invention, the adsorption separation device is an adsorption tower or an adsorption column.

[0032] The adsorption separation process of the present invention is simple. The mixed steam or mixed liquid under a certain pressure can be passed through an adsorption tower or adsorption column filled with the adsorbent. Furthermore, the adsorption tower can also be composed of one or more components, and the existing pressure swing adsorption or vacuum pressure swing adsorption or temperature swing adsorption can be used to achieve separation.

[0033] According to some embodiments of the present invention, the method further comprises regenerating the adsorbent after the adsorption separation is completed. Preferably, the regeneration comprises heating the adsorbent to 50-300°C under vacuum or inert atmosphere conditions for 20-120 hours. Too high a temperature or too long a time will cause the adsorbent structure to be destroyed; too low a temperature or too short a time will cause the adsorbate remaining in the adsorbent to be unable to be completely removed.

[0034] According to the present invention, the metal organic framework material is a three-dimensional or two-dimensional network framework structure formed by transition metal ions or alkaline earth metal ions and organic ligands (2,5-dihydroxy-1,4-benzoquinone) through coordination bonds or intermolecular forces.

[0035] In the present invention, the geometric configuration of the pores of the metal organic framework material used is adapted to the geometric structure of the corresponding benzene-cyclohexane-cyclohexene mixture three-component molecule at different temperatures, and the material structure is a layered framework that forms a network-like material through hydrogen bonding between layers. The layered plane formed by the ligand molecules in this material after coordination with the metal contains a large amount of π electron clouds, and the corresponding π-π electron cloud accumulation is formed with the benzene ring and the six-membered ring plane in benzene, cyclohexane and cyclohexene to form a strong interaction. In view of the molecular geometric structure and planar structure of benzene, the molecule forms a strong interaction with the layered surface and the adapted pores of the material. The results of thermodynamics and kinetics show that these two factors lead to significant differences in the adsorption capacity of the three component molecules on the material surface. When the mixed vapor or mixed liquid passes through the adsorption tower, cyclohexane has the weakest effect and the smallest adsorption capacity, and is the first to leave the adsorbent or adsorption separation device. The effect and adsorption capacity of cyclohexene are second, and the time required to leave the adsorbent or adsorption separation device is longer than that of cyclohexane. However, because the molecular size matches the geometric pore size of the material and the adsorption capacity is the largest, it takes the longest time to leave the adsorbent or adsorption separation device, thereby achieving the separation of benzene, cyclohexane and cyclohexene.

[0036] According to some embodiments of the present invention, the metal organic framework material is prepared by a method comprising the following steps:

[0037] (a) mixing an inorganic salt, an organic ligand and deionized water to react; the inorganic salt is a chloride, nitrate, acetate, carbonate, sulfate or perchlorate of a metal ion; and the organic ligand includes 2,5-dihydroxy-1,4-benzoquinone;

[0038] (b) washing and drying the reaction product obtained in step (a).

[0039] In the preparation process of this metal organic framework material, 2,5-dihydroxy-1,4-benzoquinone is used as an organic ligand, which reacts with a series of metal inorganic salts in pure water at room temperature. No toxic, harmful, or volatile organic solvents are required in the process. The raw materials required for the preparation are low in price, the synthesis conditions are mild, the operation is simple, the post-processing is easy, and the material synthesis cost is low.

[0040] The metal organic framework material prepared by the above method has stable structural performance, regular particle shape, and has high separation selectivity and adsorption capacity for benzene-cyclohexane-cyclohexene mixed vapor or mixed liquid.

[0041] In the method of the present invention, the metal organic framework material has high adsorption capacity and separation selectivity for a two-component mixed system of benzene-cyclohexane, benzene-cyclohexene and cyclohexane-cyclohexene and a three-component mixed system of benzene-cyclohexane-cyclohexene, and has stable material structure and adsorption performance, good water resistance, and good prospects for industrial application.

[0042] Further preferably, the molar ratio of the organic ligand to the inorganic salt is 1:(0.5-10). Deionized water is used as a solvent, and the volume capacity is 10-2000mL. Further preferably, when the inorganic salt is a cobalt salt, a zinc salt, an iron salt, a manganese salt, a magnesium salt, a calcium salt, a tin salt or a scandium salt, the molar ratio of the organic ligand to the inorganic salt is 1:(0.5-10), and deionized water is used as a solvent, and the volume capacity is 10-2000mL; when the inorganic salt is a zinc salt, an iron salt, a cobalt salt, a magnesium salt or a manganese salt, the molar ratio of the organic ligand to the inorganic salt is 1:(1-10), and water is used as a solvent, and the volume capacity is 20-2000mL.

[0043] Further preferably, when the inorganic salt is cobalt salt, nickel salt, zinc salt, iron salt, manganese salt, tin salt or scandium salt, the ratio of the inorganic salt, organic ligand and deionized water is 1mmol:1mmol:2-40mL; when the metal salt is magnesium salt, manganese salt, zinc salt, iron salt or potassium salt, the ratio of the organic ligand, inorganic salt and deionized water is 1.5mmol:1.5-6mmol:10-2000mL. Changing the ratio of metal salt, organic ligand and deionized water will change the size, crystal form, regularity, etc. of the crystal, and will also affect the adsorption amount and separation selectivity of the material for benzene, cyclohexane and cyclohexene.

[0044] Further preferably, when the inorganic salt is cobalt chloride hexahydrate, hydrated scandium nitrate, tin chloride dihydrate, hydrated magnesium acetate and ferric chloride hexahydrate, the ratio of metal salt, organic ligand and deionized water is 150mmol:150mmol:1000mL; when the inorganic salt is anhydrous manganese chloride, the ratio of metal salt, organic ligand and deionized water is 4mmol:3mmol:30mL; when the inorganic salt is anhydrous magnesium sulfate, the ratio of metal salt, organic ligand and deionized water is 6mmol:1.5mmol:400mL; when the inorganic salt is manganese acetate tetrahydrate, the ratio of metal salt, organic ligand and deionized water is 10mmol:150mmol:1000mL. The ratio is 600mmol:600mmol:2000mL; when the inorganic salt is zinc acetate dihydrate, the ratio of metal salt, organic ligand and deionized water is 300mmol:300mmol:1000mL; when the inorganic salt is ferrous sulfate heptahydrate, the ratio of metal salt, organic ligand and deionized water is 200mmol:200mmol:1000mL; when the inorganic salt is ferrous sulfate heptahydrate and potassium carbonate, the ratio of ferrous sulfate heptahydrate, potassium carbonate, organic ligand and deionized water is 200mmol:200mmol:200mmol:1000mL.

[0045] According to some embodiments of the present invention, in step (a), the mixing is carried out under stirring, and the stirring conditions are: stirring at 200-1000 rpm for 5-72 hours, and the reaction solution is mixed uniformly for reaction. Uneven mixing or incomplete reaction will lead to irregular crystal form of the crystal obtained by the reaction, thereby affecting the adsorption and separation performance of the material benzene-cyclohexane-cyclohexene mixture.

[0046] Further preferably, in step (a), the reaction temperature is 10-50°C and the reaction time is 5-70 hours; further preferably, the reaction temperature is 25-40°C and the reaction time is 8-48 hours. The reaction temperature affects the formation of crystals, and too high or too low temperature will result in the failure to form crystals.

[0047] According to some embodiments of the present invention, the product after the reaction is completed is washed multiple times by centrifugation with deionized water to replace the ligands and inorganic salts remaining in the pores.

[0048] Further preferably, the thoroughly washed product is activated under vacuum or inert gas (such as nitrogen, helium, etc.) purge, and the activation temperature is 50-250° C. and the time is 12-24 hours.

[0049] Compared with the prior art, the present invention has the following advantages:

[0050] (1) The organic ligands and metal salts used in the preparation of the metal organic framework material used in the present invention are cheap and readily available, non-toxic and harmless, the synthesis conditions are mild, the purification steps are simple, and it is easy to operate and scale up.

[0051] (2) In the method of the present invention, the metal organic framework material used has a stable structure and has very high adsorption separation selectivity for benzene / cyclohexane, benzene / cyclohexene, cyclohexane / cyclohexene and benzene / cyclohexane / cyclohexene mixed vapor or mixed liquid.

[0052] (3) The metal organic framework material used in the present invention has stable performance, and after repeated adsorption-regeneration, the adsorption performance still maintains the original effect.

[0053] (4) In terms of the adsorption separation of benzene-cyclohexane-cyclohexene mixtures, the adsorbent prepared by the present invention is far superior to most existing solid adsorbents, especially in the purification of benzene-cyclohexane-cyclohexene mixtures to obtain a single component or single component concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is the adsorption isotherm curve of benzene, cyclohexane and cyclohexene at 30°C for the manganese metal organic framework material prepared in Example 1.

[0055] Figure 2 This is the adsorption isotherm curve of benzene, cyclohexane and cyclohexene at 60°C for the manganese metal organic framework material prepared in Example 1.

[0056] Figure 3 This is the adsorption isotherm curve of benzene, cyclohexane and cyclohexene at 90°C for the manganese metal organic framework material prepared in Example 1.

[0057] Figure 4 This is the breakthrough curve of cyclohexane / cyclohexene of the manganese metal organic framework material prepared in Example 1 at 30°C.

[0058] Figure 5 This is a breakthrough curve of the manganese metal organic framework material prepared in Example 1 in benzene / cyclohexane at 60°C.

[0059] Figure 6 Schematic diagram of the simulated moving bed used in Example 1.

[0060] Figure 7 This is the adsorption isotherm curve of benzene, cyclohexane and cyclohexene at 30°C for the iron metal organic framework material prepared in Example 2.

[0061] Figure 8 This is the adsorption isotherm curve of benzene, cyclohexane and cyclohexene at 60°C for the iron metal organic framework material prepared in Example 2.

[0062] Fig. 9 This is the adsorption isotherm curve of benzene, cyclohexane and cyclohexene at 90°C for the iron metal organic framework material prepared in Example 2.

[0063] Fig.10 This is the adsorption isotherm curve of benzene, cyclohexane and cyclohexene at 30°C for the zinc metal organic framework material prepared in Example 3.

[0064] Fig.11 This is the adsorption isotherm curve of benzene, cyclohexane and cyclohexene at 60°C for the zinc metal organic framework material prepared in Example 3.

[0065] Fig.12 This is the adsorption isotherm curve of benzene, cyclohexane and cyclohexene at 90°C for the zinc metal organic framework material prepared in Example 3. DETAILED DESCRIPTION

[0066] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention, rather than to limit the scope of protection of the present invention.

[0067] Example 1

[0068] 600 mmol of manganese acetate tetrahydrate, 600 mmol of 2,5-dihydroxy-1,4-benzoquinone and 2000 mL of deionized water were mixed and stirred at room temperature for 24-48 hours. After the reaction was completed, the solid obtained by the reaction was centrifuged and washed several times with deionized water until the supernatant was clear and transparent to obtain the purified metal organic framework material. The N 2 The adsorption-desorption isotherm of the manganese material was analyzed and the specific surface area was found to be 428.9 m 2 / g, the average pore size is The purified metal organic framework material was vacuum degassed at 150°C for 12 hours to obtain the desolventized adsorbent, which was then subjected to a vapor adsorption test.

[0069] In order to test the adsorption and separation performance of the synthesized manganese metal organic framework material, the single component adsorption isotherms of benzene, cyclohexane and cyclohexene were carried out using the metal organic framework material as an adsorbent. Take an appropriate amount of adsorbent and the adsorption temperature is 30°C, 60°C, and 90°C. After testing, at 30°C and a single component saturated vapor pressure of 1000Pa, the adsorption capacity of benzene is as high as 216mg / g, the adsorption capacity of cyclohexene is 163mg / g, and the adsorption capacity of cyclohexane is 13mg / g (see the adsorption isotherm curve Figure 1); at 60°C and a single component saturated vapor pressure of 1000 Pa, the adsorption capacity of benzene is as high as 198 mg / g, the adsorption capacity of cyclohexene is only 35 mg / g, and the adsorption capacity of cyclohexane is 5 mg / g (see the adsorption isotherm curve Figure 2 ); at 90°C and a single component saturated vapor pressure of 1000 Pa, the adsorption capacity of benzene is as high as 190 mg / g, the adsorption capacity of cyclohexene is only 7 mg / g, and the adsorption capacity of cyclohexane is 4 mg / g (see the adsorption isotherm curve Figure 3 ).

[0070] The specific process of using the above synthesized manganese metal organic framework material as an adsorbent to separate a mixed benzene-cyclohexane-cyclohexene mixture is as follows:

[0071] The above-synthesized adsorbent is first molded, and the amount of binder required for the molding process accounts for 3%-10% of the mass of the adsorbent. The molded adsorbent was used to carry out a penetration experiment of a benzene-cyclohexane-cyclohexene mixed vapor. In this embodiment, the adsorbed and separated is a mixed vapor of three or two of the benzene-cyclohexane-cyclohexene mixture. The ratio of the saturated vapor pressures of benzene, cyclohexane, and cyclohexene of each single component is 1:1:1 or 1:1. The total pressure of the mixed vapor is 0.1MPa. The specifications of the filled filling column are 10mm ID×50mm, and the mass of the filled and molded adsorbent is about 2.3g. After testing, when the temperature of the adsorbent is 30°C and the saturated vapor pressure ratio of cyclohexane / cyclohexene is 50:50, cyclohexane penetrates in 15 minutes, and cyclohexene begins to penetrate in 113 minutes (see the penetration curve). Figure 4 ); When the adsorbent temperature is 60°C and the benzene / cyclohexane saturated vapor pressure ratio is 50:50, cyclohexane breaks through in 3 minutes and benzene starts to break through in 107 minutes (see the attached breakthrough curve). Figure 5 ); When the adsorbent temperature is 90°C and the benzene / cyclohexene saturated vapor pressure ratio is 50:50, cyclohexene breaks through at 18 minutes, while benzene starts to break through at 137 minutes. Such a large difference in retention time indicates that the benzene-cyclohexane-cyclohexene mixture can be effectively separated at different temperatures.

[0072] After testing, for the mixed steam with saturated vapor pressure of benzene / cyclohexane / cyclohexene of 1:1:1, when the temperature of the adsorbent is 30°C, cyclohexane begins to penetrate at the initial 12 minutes, cyclohexene begins to penetrate at 66 minutes, and benzene remains in the packed column for about 135 minutes before it begins to penetrate and precipitate; when the temperature of the adsorbent is 60°C, cyclohexane begins to penetrate at the initial 4 minutes, cyclohexene begins to penetrate at 17 minutes, and benzene remains in the packed column for about 112 minutes before it begins to penetrate and precipitate; when the temperature of the adsorbent is 90°C, cyclohexane and cyclohexene begin to penetrate at the initial 3 minutes, while benzene remains in the packed column for about 129 minutes before it begins to penetrate and precipitate. Such a large difference in retention time once again verifies that the benzene-cyclohexane-cyclohexene mixture can be effectively separated at different temperatures. The adsorption performance of the metal organic framework material remains stable after 5 adsorption-regeneration cycles. The regeneration condition is to heat the adsorbent to 150°C under vacuum or inert atmosphere conditions and keep it for 72 hours.

[0073] The above manganese metal adsorbent is used for adsorption separation on a small simulated moving bed with continuous countercurrent.

[0074] The small simulated moving bed device comprises 12 adsorption columns connected in series, each column is 150 mm long, the inner diameter of the column is 10 mm, and the total loading amount of the adsorbent is 140 mL. The ends of the 12 columns connected in series are connected by a circulation pump to form a closed loop, such as Figure 6 shown. Figure 6 In the process, the four inlet and outlet materials of adsorption raw material, desorbent, extract and raffinate divide the 12 adsorption columns into four sections, namely, the three adsorption columns between the adsorption raw material (column 8) and the raffinate (column 10) are the adsorption zone, the four adsorption columns between the extract (column 4) and the adsorption raw material (column 7) are the purification zone, the three adsorption columns between the desorbent (column 1) and the extract (column 3) are the desorption zone, and the two adsorption columns between the raffinate (column 11) and the desorbent (column 12) are the buffer zone. The temperature of the whole adsorption system is controlled at 90°C and the pressure is 0.5MPa.

[0075] During the operation, the desorbent and the adsorption raw material are continuously injected into the simulated moving bed device at a flow rate of 130mL / h and 100mL / h respectively, and the extract is extracted from the device at a flow rate of 80mL / h, and the raffinate is extracted from the device at a flow rate of 150mL / h. The desorbent is n-octane, 2-methylheptane, 3-methylheptane, 4-methylheptane, n-nonane or n-decane. The composition of the adsorption raw material is 10wt% benzene, 20wt% cyclohexane, and 70wt% cyclohexene. The circulation pump flow rate is set to 270mL / h. According to the principle of simulated countercurrent chromatography, the four material positions are moved forward by one adsorption column in the same direction as the liquid flow every 70 seconds. The benzene purity obtained under stable operating conditions is 99.75-99.9wt%, and the recovery rate is 98.0-99.0wt%.

[0076] Example 2

[0077] 200mmol of ferrous sulfate heptahydrate, 200mmol of 2,5-dihydroxy-1,4-benzoquinone, and 200mmol of potassium carbonate were mixed with 1000mL of deionized water and stirred for reaction at room temperature for 30min. After the reaction was completed, the solid product obtained by the reaction was centrifuged and washed several times with deionized water until the supernatant was clear and transparent to obtain the purified iron metal organic framework material. The N 2 The adsorption-desorption isotherm of the iron material was analyzed to obtain a specific surface area of ​​497 m 2 / g, the average pore size is The purified metal organic framework material was vacuum activated at 150°C for 12 hours to obtain the desolvated adsorbent, which was then subjected to a vapor adsorption test.

[0078] In order to test the adsorption and separation performance of the synthesized iron metal organic framework material, the single component adsorption isotherms of benzene, cyclohexane and cyclohexene were carried out using the metal organic framework material as an adsorbent. Take an appropriate amount of adsorbent and the adsorption temperature is 30°C, 60°C, and 90°C. After testing, at 30°C and a single component saturated vapor pressure of 1000Pa, the adsorption capacity of benzene is as high as 129mg / g, the adsorption capacity of cyclohexene is 42mg / g, and the adsorption capacity of cyclohexane is 3mg / g (see the adsorption isotherm curve Figure 7 ); at 60°C and a single component saturated vapor pressure of 1000 Pa, the adsorption capacity of benzene is as high as 62 mg / g, the adsorption capacity of cyclohexene is only 27 mg / g, and the adsorption capacity of cyclohexane is 2 mg / g (see the adsorption isotherm curve Figure 8 ); at 90°C and a single component saturated vapor pressure of 1000 Pa, the adsorption capacity of benzene is 25 mg / g, the adsorption capacity of cyclohexene is only 1.5 mg / g, and the adsorption capacity of cyclohexane is 0.1 mg / g (see the adsorption isotherm curve Fig. 9 ).

[0079] Example 3

[0080] 300 mmol zinc acetate dihydrate, 300 mmol 2,5-dihydroxy-1,4-benzoquinone, and 1000 mL deionized water were mixed and stirred at room temperature for 12-48 hours. After the reaction was completed, the solid product obtained by the reaction was centrifuged and washed several times with deionized water until the supernatant was clear and transparent to obtain the purified metal organic framework material. The N 2 The adsorption-desorption isotherm of the 2 / g, the average pore size is The purified metal organic framework material was vacuum activated at 150°C for 12 hours to obtain the desolvated adsorbent, which was then subjected to a vapor adsorption test.

[0081] In order to test the adsorption and separation performance of the synthesized zinc metal organic framework material, the single component adsorption isotherms of benzene, cyclohexane and cyclohexene were carried out using the metal organic framework material as an adsorbent. Take an appropriate amount of adsorbent and the adsorption temperature is 30°C, 60°C, and 90°C. After testing, at 30°C and a single component saturated vapor pressure of 1000Pa, the adsorption capacity of benzene is 43mg / g, the adsorption capacity of cyclohexene is 8mg / g, and the adsorption capacity of cyclohexane is 0.6mg / g (see the adsorption isotherm curve Fig.10 ); at 60°C and a single component saturated vapor pressure of 3000 Pa, the adsorption capacity of benzene is 20 mg / g, the adsorption capacity of cyclohexene is only 5 mg / g, and the adsorption capacity of cyclohexane is 1 mg / g (see the adsorption isotherm curve Fig.11 ); at 90°C and a single component saturated vapor pressure of 3000 Pa, the adsorption capacity of benzene is as high as 9 mg / g, the adsorption capacity of cyclohexene is only 1 mg / g, and the adsorption capacity of cyclohexane is 0.01 mg / g (see the adsorption isotherm curve Fig.12 ).

[0082] The above embodiments are only used to illustrate the technical solution of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solution to deviate from the scope of the technical solution of the present application.

Claims

1. A method for separating a mixture of benzene, cyclohexane and cyclohexene, comprising subjecting the mixture containing benzene, cyclohexane and / or cyclohexene to adsorption separation using an adsorbent, wherein the adsorbent comprises a metal organic framework material, wherein: The metal organic framework material comprises metal ions and organic ligands, wherein the organic ligands comprise 2,5-dihydroxy-1,4-benzoquinone. The metal ions include one or more of zinc ions, manganese ions, cobalt ions, magnesium ions, calcium ions, iron ions, nickel ions, copper ions or tin ions. The temperature of the adsorption separation is -5°C to 300°C.

2. The method according to claim 1, characterized in that The pore size of the metal organic framework material is above; and / or The specific surface area of ​​the metal organic framework material is 300-2000m 2 / g.

3. The method according to claim 1, characterized in that The pore size of the metal organic framework material is 4. The method according to claim 1, characterized in that: The pore size of the metal organic framework material is 5. The method according to any one of claims 1 to 4, characterized in that The mixture containing benzene, cyclohexane and / or cyclohexene is in gaseous or liquid state.

6. The method according to any one of claims 1 to 4, characterized in that The temperature of the adsorption separation is 25°C to 250°C; and / or The pressure of the adsorption separation is 0.01MPa-10MPa.

7. The method according to any one of claims 1 to 4, characterized in that The temperature of the adsorption separation is 30°C to 150°C; and / or The pressure of the adsorption separation is 0.1MPa-6MPa.

8. The method according to any one of claims 1 to 4, characterized in that The adsorption separation is performed using a fixed bed, wherein the adsorbent is filled in the fixed bed adsorption column.

9. The method according to claim 8, characterized in that The adsorption separation comprises the following steps: (1) passing a mixed vapor formed by a mixture containing benzene, cyclohexane and / or cyclohexene and a carrier gas through a fixed bed adsorption column, wherein a strongly adsorbed component in the mixture containing benzene, cyclohexane and / or cyclohexene is adsorbed on the adsorbent, and a weakly adsorbed component in the mixture containing benzene, cyclohexane and / or cyclohexene penetrates the adsorption column, so that benzene, cyclohexane and cyclohexene components flow out of the adsorption column at different times, respectively, to obtain a weakly adsorbed component; (2) Desorbing the strongly adsorbed component from the adsorbent to obtain the strongly adsorbed component.

10. The method according to any one of claims 1 to 4, characterized in that The adsorption separation is performed using a simulated moving bed, wherein the adsorbent is filled in the adsorption zone bed layer of the simulated moving bed.

11. The method according to claim 10, characterized in that The adsorption separation comprises the following steps: (3) subjecting a mixture liquid containing benzene, cyclohexane and / or cyclohexene to adsorption separation through a liquid phase simulated moving bed, so that benzene, cyclohexane and cyclohexene are extracted from different bed layers respectively.

12. The method according to claim 9, characterized in that The flow rate of the mixed steam through the fixed bed adsorption column is 1-200 mL / min / g adsorbent.

13. The method according to claim 11, characterized in that The number of adsorbent bed layers of the simulated moving bed is 4 to 32.

14. The method according to any one of claims 1 to 4, characterized in that: The method further comprises regenerating the adsorbent after the adsorption separation is completed.

15. The method according to claim 14, characterized in that: The regeneration comprises heating the adsorbent to 50-300° C. under vacuum or inert atmosphere conditions and maintaining the temperature for 20-120 hours.

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