Adsorbent, preparation method thereof and application of adsorbent in separation of ethylbenzene from C8 mixed aromatic hydrocarbon

Abstract

The invention provides an adsorbent, a preparation method thereof and application of the adsorbent to separation of ethylbenzene from C8 mixed aromatic hydrocarbon, and relates to the technical field of adsorbents. The method comprises the following steps: mixing a silicon source, an aluminum source and water to obtain a first mixed solution; 2-aminoterephthalic acid, titanium isopropylate, N, N-dimethylformamide and methyl alcohol are mixed, and a second mixed solution is obtained; mixing the first mixed solution, the second mixed solution and an alkali metal salt solution to obtain a third mixed solution; performing hydrothermal reaction on the third mixed solution, and roasting an obtained hydrothermal product to obtain the adsorbent. The prepared adsorbent has a molecular sieve / MOF composite structure, alkali metal ions are anchored through organic ligands, and the acting force is stronger, so that the selectivity of the alkali metal ions is enhanced, meanwhile, the molecular sieve and MOF structures provide rich pore structures, and the ethylbenzene adsorption capacity of the material is greatly improved. The adsorbent provided by the invention can realize efficient separation of ethylbenzene from C8 mixed aromatic hydrocarbons, and ethylbenzene selectivity and adsorption capacity are high.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorbents, and in particular to an adsorbent and a preparation method thereof, and application thereof in separating ethylbenzene from C8 mixed aromatics. Background Art

[0002] C8 aromatic compounds are important raw materials for synthesizing various fibers, plastics and textiles, with an annual global output of more than 40 million tons. Among them, o-xylene, m-xylene, p-xylene and ethylbenzene account for 20%, 42%, 18% and 20% respectively. Ethylbenzene is an important raw material for synthesizing styrene, which is then used to manufacture engineering plastics and synthetic rubber, etc. The demand for styrene is increasing year by year. Since C8 aromatic isomers are produced in the form of a multi-component mixture through catalytic reforming of crude oil, subsequent separation is essential for its downstream applications.

[0003] The four aromatic components, o-xylene, m-xylene, p-xylene and ethylbenzene, have similar molecular structures and boiling points. Therefore, separating and purifying C8 aromatics by conventional distillation methods requires a large number of theoretical plates and consumes huge energy.

[0004] Adsorption separation technology has attracted wide attention in many fields such as petrochemical industry, separation and purification of natural products, and treatment of water bodies polluted by harmful substances due to its advantages such as simple operation and low energy consumption. Among the existing separation technologies, adsorption is the most popular and economical so far. Because this method has the advantages of low cost, high efficiency, simple equipment and convenient operation, it has broad application prospects in the field of C8 aromatics separation.

[0005] In the 1960s, the UOP Company of the United States proposed the Parex process for the separation of xylene isomers, mainly for the adsorption and separation of p-xylene from C8 aromatics. Adsorption separation technology based on porous materials is widely used in the separation of C8 aromatic mixtures. However, most of the materials developed are used to separate xylene isomers or to separate p-xylene, m-xylene or o-xylene from C8 aromatics separately by adsorption. There are few studies on materials for the separate adsorption and separation of ethylbenzene, and there is no process for directly separating ethylbenzene from C8 aromatic mixtures in industrial applications.

[0006] Patent CN110871053A discloses an adsorbent for separating ethylbenzene by adsorption. The adsorbent has a core-shell structure with a BEA molecular sieve as the core and an MFI molecular sieve as the shell. Alkali metal ion exchange is used to improve the adsorption performance of ethylbenzene. The highest purity of ethylbenzene separated by adsorption is 99.9wt%. Patent US4079094 discloses the Ebex process developed by UOP for the separation of industrial ethylbenzene. By using a special Sr 2+ , K +The exchanged molecular sieve is used as an adsorbent to separate ethylbenzene from C8 aromatics by adsorption, and the ethylbenzene product yield is >95%, and the ethylbenzene purity is >98wt%. Although the above technology can separate ethylbenzene from C8 aromatics by adsorption, the adsorption amount and adsorption selectivity of ethylbenzene still need to be improved. Summary of the invention

[0007] In view of this, the purpose of the present invention is to provide an adsorbent and a preparation method thereof and an application in separating ethylbenzene from C8 mixed aromatics. The adsorbent prepared by the present invention can efficiently separate ethylbenzene from C8 mixed aromatics, with high ethylbenzene selectivity and adsorption capacity.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides a method for preparing an adsorbent, comprising the following steps:

[0010] Mixing a silicon source, an aluminum source and water to obtain a first mixed solution; the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, and the molar ratio of the silicon source, the aluminum source and water is 1:(0.5-2):(80-200);

[0011] Mixing 2-aminoterephthalic acid, titanium isopropoxide, N,N-dimethylformamide and methanol to obtain a second mixed solution;

[0012] The first mixed solution, the second mixed solution and an alkali metal salt solution are mixed to obtain a third mixed solution; the pH value of the third mixed solution is 8 to 9;

[0013] subjecting the third mixed solution to a hydrothermal reaction to obtain a hydrothermal product;

[0014] The hydrothermal product is calcined to obtain the adsorbent.

[0015] Preferably, the silicon source includes one or more of sodium silicate, tetraethyl orthosilicate and silica sol, and the aluminum source includes one or more of sodium metaaluminate, aluminum sec-butoxide, aluminum isopropoxide and aluminum sulfate.

[0016] Preferably, the mass ratio of 2-aminoterephthalic acid, titanium isopropoxide, N,N-dimethylformamide and methanol is 1:(0.8-1.3):50:20.

[0017] Preferably, the alkali metal salt in the alkali metal salt solution includes one or more of cesium chloride, rubidium chloride and potassium chloride, and the concentration of the alkali metal salt solution is 1 mol / L.

[0018] Preferably, the mass ratio of the first mixed liquid to the second mixed liquid is 1:1; the mass ratio of the alkali metal salt solution to the mass of 2-aminoterephthalic acid in the second mixed liquid is (2-15):1.

[0019] Preferably, the pH value of the third mixed solution is adjusted by using an alkali metal hydroxide aqueous solution.

[0020] Preferably, the temperature of the hydrothermal reaction is 100-150° C., and the time is 12-48 hours; the temperature of the calcination is 180-200° C., and the time is 6-12 hours.

[0021] The present invention provides an adsorbent prepared by the preparation method described in the above technical scheme.

[0022] The present invention provides the use of the adsorbent described in the above technical solution to separate ethylbenzene from C8 mixed aromatics, wherein the C8 mixed aromatics include p-xylene, o-xylene, m-xylene and ethylbenzene.

[0023] Preferably, the application method comprises:

[0024] The organic solution of C8 mixed aromatics is mixed with the adsorbent for adsorption; the mass fractions of p-xylene, o-xylene, m-xylene and ethylbenzene in the organic solution of C8 mixed aromatics are independently 1.9-2.5%, and the liquid-to-solid mass ratio of the organic solution of C8 mixed aromatics to the adsorbent is (3-10):1.

[0025] The invention provides a method for preparing an adsorbent, comprising the following steps: mixing a silicon source, an aluminum source and water to obtain a first mixed liquid; mixing 2-aminoterephthalic acid, titanium isopropoxide, N,N-dimethylformamide and methanol to obtain a second mixed liquid; mixing the first mixed liquid, the second mixed liquid and an alkali metal salt solution to obtain a third mixed liquid; subjecting the third mixed liquid to a hydrothermal reaction to obtain a hydrothermal product; and roasting the hydrothermal product to obtain the adsorbent. In the present invention, the first mixed liquid is a raw material liquid for synthesizing X molecular sieve, and the second mixed liquid is a raw material liquid for synthesizing MIL-125 metal organic framework material (MOF). The molecular sieve / MOF composite structure is formed in a hydrothermal reaction. During the synthesis process, alkali metal ions are introduced through an alkali metal salt solution. The alkali metal ions have a strong selective effect on ethylbenzene. The organic ligand 2-aminoterephthalic acid anchors the alkali metal ions so that the alkali metal grows in situ in the material structure. Compared with the usual ion exchange, the force is stronger, which can enhance the ethylbenzene selectivity of the material, and the stability of the material is also enhanced; and the rich pore structure of the molecular sieve and the metal organic framework material can also greatly increase the ethylbenzene adsorption capacity of the material.

[0026] The present invention provides an adsorbent prepared by the preparation method described in the above technical solution. The adsorbent provided by the present invention is applied to separate ethylbenzene from C8 mixed aromatics, which can achieve efficient separation of ethylbenzene from C8 mixed aromatics, with high ethylbenzene selectivity and adsorption capacity. DETAILED DESCRIPTION

[0027] The present invention provides a method for preparing an adsorbent, comprising the following steps:

[0028] Mixing a silicon source, an aluminum source and water to obtain a first mixed solution; the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, and the molar ratio of the silicon source, the aluminum source and water is 1:(0.5-2):(80-200);

[0029] Mixing 2-aminoterephthalic acid, titanium isopropoxide, N,N-dimethylformamide and methanol to obtain a second mixed solution;

[0030] The first mixed solution, the second mixed solution and an alkali metal salt solution are mixed to obtain a third mixed solution; the pH value of the third mixed solution is 8 to 9;

[0031] subjecting the third mixed solution to a hydrothermal reaction to obtain a hydrothermal product;

[0032] The hydrothermal product is calcined to obtain the adsorbent.

[0033] In the present invention, unless otherwise specified, the raw materials involved are commercially available products well known to those skilled in the art.

[0034] The present invention mixes a silicon source, an aluminum source and water to obtain a first mixed solution (also referred to as A solution in the embodiment of the present invention). In the present invention, the silicon source preferably includes one or more of sodium silicate, tetraethyl orthosilicate and silica sol, and more preferably sodium silicate; the aluminum source preferably includes one or more of sodium aluminate, aluminum sec-butoxide, aluminum isopropoxide and aluminum sulfate, and more preferably sodium aluminate; the water is preferably deionized water. In the present invention, the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, and the molar ratio of the silicon source, aluminum source and water is 1: (0.5-2): (80-200), preferably 1: (0.5-1): (80-150). The present invention preferably adds the silicon source and aluminum source into water and stirs evenly to obtain the first mixed solution. In the present invention, the first mixed solution is used as the raw material liquid for synthesizing X molecular sieve.

[0035] The present invention mixes 2-aminoterephthalic acid, titanium isopropoxide, N,N-dimethylformamide and methanol to obtain a second mixed solution (also referred to as B solution in the embodiment of the present invention). In the present invention, the mass ratio of the 2-aminoterephthalic acid, titanium isopropoxide, N,N-dimethylformamide and methanol is preferably 1: (0.8-1.3): 50: 20, more preferably 1: (0.9-1.2): 50: 20, and further preferably 1: (1-1.1): 50: 20. The present invention preferably mixes the N,N-dimethylformamide and methanol, then adds 2-aminoterephthalic acid and titanium isopropoxide to the obtained mixed solution, stirs evenly, and obtains the second mixed solution. In the present invention, the second mixed solution is a raw material solution for synthesizing MIL-125 metal organic framework material (MOF).

[0036] After obtaining the first mixed solution and the second mixed solution, the present invention mixes the first mixed solution and the second mixed solution with an alkali metal salt solution to obtain a third mixed solution. In the present invention, the alkali metal salt (i.e., Group IA metal salt) in the alkali metal salt solution preferably includes one or more of cesium chloride, rubidium chloride and potassium chloride, more preferably rubidium chloride; the concentration of the alkali metal salt solution is preferably 1 mol / L. In the present invention, the mass ratio of the first mixed solution to the second mixed solution is preferably 1:1; the ratio of the mass of the alkali metal salt solution to the mass of 2-aminoterephthalic acid in the second mixed solution is preferably (2-15):1, more preferably (10-15):1. In the present invention, the pH value of the third mixed solution is 8-9, and the pH value of the third mixed solution is preferably obtained by adjusting an alkali metal hydroxide aqueous solution, the alkali metal hydroxide aqueous solution is preferably an RbOH aqueous solution, and the concentration of the RbOH aqueous solution is preferably 0.01 mol / L.

[0037] The present invention preferably mixes the first mixed solution and the second mixed solution evenly, adds an alkali metal salt solution to the obtained mixed solution (referred to as solution C in the embodiment of the present invention), stirs evenly, and adjusts the pH value to 8-9 with an alkali metal hydroxide aqueous solution to obtain the third mixed solution.

[0038] After obtaining the third mixed solution, the present invention performs a hydrothermal reaction on the third mixed solution to obtain a hydrothermal product. In the present invention, the temperature of the hydrothermal reaction is preferably 100 to 150°C, more preferably 120 to 130°C, and the time is preferably 12 to 48 hours, more preferably 16 to 48 hours, and further preferably 24 to 30 hours. The present invention preferably transfers the third mixed solution to a polytetrafluoroethylene autoclave, places it in an oven, and performs the hydrothermal reaction. During the hydrothermal reaction, molecular sieves and MOF framework structures are generated.

[0039] After the hydrothermal reaction is completed, the present invention preferably cools the obtained hydrothermal reaction liquid and separates the solid and liquid, and sequentially washes the obtained solid with N,N-dimethylformamide, methanol and dries it to obtain the hydrothermal product. In the present invention, the number of N,N-dimethylformamide washings is preferably 3 times, the number of methanol washings is preferably 3 times, the drying is preferably vacuum drying, the vacuum drying temperature is preferably 80°C, and the time is preferably 12 hours.

[0040] After obtaining the hydrothermal product, the present invention roasts the hydrothermal product to obtain the adsorbent. In the present invention, the roasting temperature is preferably 180 to 200° C., and the time is preferably 6 to 12 hours. The present invention removes unreacted monomers by roasting.

[0041] The present invention provides an adsorbent prepared by the preparation method described in the above technical solution. In the present invention, the adsorbent is a molecular sieve / MOF composite structure, and the organic ligands in the MOF anchor the alkali metal that has a strong selectivity for ethylbenzene. In the adsorbent with a molecular sieve / MOF composite structure provided by the present invention, the alkali metal grows in situ in the material structure through the anchoring of the organic ligand. Compared with the alkali metal ion exchange molecular sieve, the action force is stronger, and the selectivity of the alkali metal ions is enhanced. At the same time, the silicon source and the aluminum source provide a rich pore structure in the organic skeleton, and the MOF structure also provides a rich pore structure, thereby greatly improving the ethylbenzene adsorption capacity of the material.

[0042] The present invention provides the use of the adsorbent described in the above technical solution to separate ethylbenzene from C8 mixed aromatics, wherein the C8 mixed aromatics include p-xylene, o-xylene, m-xylene and ethylbenzene.

[0043] In the present invention, the application method preferably comprises: mixing the organic solution of the C8 mixed aromatic hydrocarbons with the adsorbent for adsorption.

[0044] In the present invention, the mass fractions of p-xylene, o-xylene, m-xylene and ethylbenzene in the organic solution of C8 mixed aromatics are independently preferably 1.9-2.5%, specifically 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, the liquid-solid mass ratio of the organic solution of C8 mixed aromatics to the adsorbent is preferably (3-10):1, more preferably (5-6):1, and the solvent of the organic solution of C8 mixed aromatics is preferably n-nonane. In the present invention, the adsorption is carried out at room temperature (25°C).

[0045] The adsorbent of the present invention is applied to the separation of ethylbenzene from C8 mixed aromatics, so that ethylbenzene can be separated from C8 mixed aromatics with high selectivity and adsorption capacity.

[0046] In order to further illustrate the present invention, the adsorbent provided by the present invention, its preparation method and its application in separating ethylbenzene from C8 mixed aromatics are described in detail below with reference to examples, but they should not be construed as limiting the scope of protection of the present invention.

[0047] Example 1

[0048] Dissolve 1.0 g of sodium silicate (SiO2 content is 60 wt%) and 1.0 g of sodium aluminate in 15 g of deionized water, and stir to obtain solution A;

[0049] 0.56 g of 2-aminoterephthalic acid and 0.6 g of titanium isopropoxide were dissolved in a mixture of 28 g of N,N-dimethylformamide and 11.2 g of methanol and stirred to obtain a solution B;

[0050] Take 15g of solution A and 15g of solution B, mix them evenly to obtain solution C;

[0051] Add 3 g of 1 mol / L rubidium chloride solution to solution C, stir and mix evenly, adjust the pH value to 8 with 0.01 mol / L RbOH aqueous solution, then transfer the solution to a polytetrafluoroethylene high-pressure reactor and place it in an oven, and keep it at 120°C for 24 hours; after cooling, the solid product is washed with N,N-dimethylformamide 3 times and then with methanol 3 times; vacuum dry at 80°C for 12 hours, and then calcine at 200°C for 6 hours to obtain an adsorbent for separating ethylbenzene from C8 mixed aromatics.

[0052] Weigh 0.5g of the prepared adsorbent and place it in a 5mL sample bottle. Add a C8 aromatic hydrocarbon n-nonane solution into the bottle, where the mass fraction of ethylbenzene, p-xylene, m-xylene and o-xylene is 2%; the liquid-solid mass ratio is 5:1. Place the sample bottle in a 25℃ shaker for adsorption for 24h. Calculate the adsorption amount of ethylbenzene by the adsorbent and the selectivity of ethylbenzene / p-xylene.

[0053] The adsorption capacity Q of the adsorbent for adsorbate i i The calculation formula is as follows:

[0054]

[0055] Where, M0 is the mass of n-nonane adsorbed per gram of adsorbent, g; W i0 is the initial mass fraction of component i in the adsorption solution (i.e., n-nonane solution of C8 aromatics), %; W m0 is the initial mass fraction of n-nonane in the adsorption solution, %; W i is the mass fraction of component i in the adsorption equilibrium solution, %; W m is the mass fraction of n-nonane in the adsorption equilibrium solution, %.

[0056] Selective αi / j The calculation formula is as follows:

[0057]

[0058] In the formula, Q i Q is the adsorption capacity of the adsorbent for adsorbate i, mg / g; j W is the adsorption capacity of the adsorbent for adsorbate j, mg / g; i is the mass fraction of adsorbate i in the adsorption equilibrium solution, %; W j is the mass fraction of adsorbate j in the adsorption equilibrium solution, %.

[0059] Example 2

[0060] Dissolve 1.0 g of sodium silicate (SiO2 content is 60 wt%) and 1.0 g of sodium aluminate in 15 g of deionized water, and stir to obtain solution A;

[0061] 0.6 g of 2-aminoterephthalic acid and 0.6 g of titanium isopropoxide were dissolved in a mixture of 30 g of N,N-dimethylformamide and 12 g of methanol, and stirred to obtain a solution B;

[0062] Take 15g of solution A and 15g of solution B, mix them evenly to obtain solution C;

[0063] Add 3 g of 1 mol / L cesium chloride solution to the C solution, stir and mix evenly, adjust the pH value to 8 with 0.01 mol / L RbOH aqueous solution, then transfer the solution to a polytetrafluoroethylene high-pressure reactor and place it in an oven, and keep it at 120°C for 24 hours; after cooling, the solid product is washed with N,N-dimethylformamide for 3 times and then with methanol for 3 times; vacuum dry at 80°C for 12 hours, and then calcine at 200°C for 6 hours to obtain an adsorbent for separating ethylbenzene from C8 mixed aromatics.

[0064] Weigh 0.5g of adsorbent and place it in a 5mL sample bottle. Add a C8 aromatic n-nonane solution into the bottle, wherein the mass fraction of ethylbenzene, p-xylene, m-xylene and o-xylene is 2%; the liquid-solid mass ratio is 5:1. Place the sample bottle in a 25°C shaker for adsorption for 24 hours. Calculate the adsorption amount of ethylbenzene by the adsorbent and the selectivity of ethylbenzene / p-xylene, and the calculation method is the same as in Example 1.

[0065] Example 3

[0066] Dissolve 1.0 g of sodium silicate (SiO2 content is 60 wt%) and 1.2 g of sodium aluminate in 15 g of deionized water and stir to obtain solution A;

[0067] 0.5 g of 2-aminoterephthalic acid and 0.45 g of titanium isopropoxide were dissolved in a mixture of 25 g of N,N-dimethylformamide and 10 g of methanol and stirred to obtain a solution B;

[0068] Take 16g of solution A and 16g of solution B, mix them evenly to obtain solution C;

[0069] Add 3 g of 1 mol / L rubidium chloride solution to solution C, stir and mix evenly, adjust the pH to 8 with 0.01 mol / L RbOH aqueous solution, then transfer the solution to a polytetrafluoroethylene high-pressure reactor and place it in an oven, and keep it at 150°C for 48 hours; after cooling, the solid product is washed with N,N-dimethylformamide 3 times and then with methanol 3 times; vacuum dry at 80°C for 12 hours, and then calcine at 200°C for 6 hours to obtain an adsorbent for separating ethylbenzene from C8 mixed aromatics.

[0070] Weigh 0.5g of adsorbent and place it in a 5mL sample bottle. Add a C8 aromatic hydrocarbon n-nonane solution into the bottle, wherein the mass fraction of ethylbenzene is 2%, and the mass fractions of p-xylene, m-xylene and o-xylene are all 2.5%; the liquid-solid mass ratio is 5:1. Place the sample bottle in a 25°C shaker for adsorption for 24 hours. Calculate the adsorption amount of ethylbenzene by the adsorbent and the selectivity of ethylbenzene / p-xylene, and the calculation method is the same as in Example 1.

[0071] Example 4

[0072] Dissolve 1.0 g of sodium silicate (SiO2 content is 60 wt%) and 1.2 g of sodium aluminate in 15 g of deionized water and stir to obtain solution A;

[0073] 0.5 g of 2-aminoterephthalic acid and 0.6 g of titanium isopropoxide were dissolved in a mixture of 25 g of N,N-dimethylformamide and 10 g of methanol, and stirred to obtain a solution B;

[0074] Take 15g of solution A and 15g of solution B, mix them evenly to obtain solution C;

[0075] Add 3 g of 1 mol / L potassium chloride solution to the C solution, stir and mix evenly, adjust the pH to 8 with 0.01 mol / L RbOH aqueous solution, then transfer the solution to a polytetrafluoroethylene high-pressure reactor and place it in an oven, and keep it at 130°C for 30 hours; after cooling, the solid product is washed with N,N-dimethylformamide 3 times and then with methanol 3 times; vacuum dry at 80°C for 12 hours, and then calcine at 200°C for 6 hours to obtain an adsorbent for separating ethylbenzene from C8 mixed aromatics.

[0076] Weigh 0.5g of adsorbent and place it in a 5mL sample bottle. Add a C8 aromatic hydrocarbon n-nonane solution into the bottle, wherein the mass fraction of ethylbenzene is 2%, the mass fraction of p-xylene is 2.2%, the mass fraction of m-xylene is 1.9%, and the mass fraction of o-xylene is 2.1%; the liquid-solid mass ratio is 5:1. Place the sample bottle in a 25°C shaker for adsorption for 24 hours. Calculate the adsorption amount of ethylbenzene by the adsorbent and the selectivity of ethylbenzene / p-xylene, and the calculation method is the same as in Example 1.

[0077] Comparative Example 1

[0078] 0.6 g of 2-aminoterephthalic acid and 0.6 g of titanium isopropoxide were dissolved in a mixed solution consisting of 30 g of N, N-dimethylformamide and 12 g of methanol and stirred evenly. 15 g of the solution was taken, 3 g of 1 mol / L cesium chloride solution was added, and after stirring and mixing evenly, the pH was adjusted to 8 with 0.01 mol / L RbOH aqueous solution. Then the solution was transferred to a polytetrafluoroethylene high-pressure reactor and placed in an oven, and kept warm at 120°C for 24 hours. After cooling, the solid product was washed 3 times with N, N-dimethylformamide and then washed 3 times with methanol; vacuum dried at 80°C for 12 hours, and then calcined at 200°C for 6 hours to obtain an adsorbent for separating ethylbenzene from C8 mixed aromatics.

[0079] Weigh 0.5g of adsorbent and place it in a 5mL sample bottle. Add a C8 aromatic n-nonane solution into the bottle, wherein the mass fraction of ethylbenzene, p-xylene, m-xylene and o-xylene is 2%; the liquid-solid mass ratio is 5:1. Place the sample bottle in a 25°C shaker for adsorption for 24 hours. Calculate the adsorption amount of ethylbenzene by the adsorbent and the selectivity of ethylbenzene / p-xylene, and the calculation method is the same as in Example 1.

[0080] Comparative Example 2

[0081] 1.0g sodium silicate (SiO2 content is 60wt%) and 1.0g sodium aluminate are dissolved in 15g deionized water and stirred evenly. 15g of the solution is taken, 3g of 1mol / L rubidium chloride solution is added, and after stirring and mixing evenly, the pH is adjusted to 8 with 0.01mol / L RbOH aqueous solution, and then the solution is transferred to a polytetrafluoroethylene high-pressure reactor and placed in an oven, and kept warm at 120°C for 24h; after cooling, the solid product is washed 3 times with N,N-dimethylformamide and then washed 3 times with methanol; vacuum dried at 80°C for 12 hours, and then calcined at 200°C for 6h to obtain an adsorbent for separating ethylbenzene from C8 mixed aromatics.

[0082] Weigh 0.5g of adsorbent and place it in a 5mL sample bottle. Add a C8 aromatic n-nonane solution into the bottle, wherein the mass fraction of ethylbenzene, p-xylene, m-xylene and o-xylene is 2%; the liquid-solid mass ratio is 5:1. Place the sample bottle in a 25°C shaker for adsorption for 24 hours. Calculate the adsorption amount of ethylbenzene by the adsorbent and the selectivity of ethylbenzene / p-xylene, and the calculation method is the same as in Example 1.

[0083] Comparative Example 3

[0084] The X-type molecular sieve was synthesized by hydrothermal method, and the molar ratio of the reactants was: n(Al2O3):n(SiO2):n(Na2O):n(K2O):n(H2O)=1:2.2:5.5:1.65:122. First, sodium hydroxide and potassium hydroxide were mixed with water and stirred at room temperature for 10 minutes. Sodium aluminate was dissolved in water and added to the previous mixture after 5 minutes. Subsequently, water glass was slowly added to the solution and stirred for 30 minutes. The prepared solution was transferred to an oven at 50°C for aging for 3 hours. Finally, it was placed in a reactor at 100°C for crystallization for 5 hours. The obtained solid product was filtered, washed, and dried at 100°C to obtain X zeolite molecular sieve. The X zeolite molecular sieve was continuously ion exchanged with 1 mol / L RbCl solution at a mass ratio of 1:5 at a constant temperature of 80°C for 6 hours. After the exchange, the sample was filtered, washed, and dried at 100°C to obtain an adsorbent.

[0085] Weigh 0.5g of adsorbent and place it in a 5mL sample bottle. Add a C8 aromatic n-nonane solution into the bottle, wherein the mass fraction of ethylbenzene, p-xylene, m-xylene and o-xylene is 2%; the liquid-solid mass ratio is 5:1. Place the sample bottle in a 25°C shaker for adsorption for 24 hours. Calculate the adsorption amount of ethylbenzene by the adsorbent and the selectivity of ethylbenzene / p-xylene, and the calculation method is the same as in Example 1.

[0086] The pore structure data of the adsorbents prepared in various embodiments and comparative examples are shown in Table 1, and the experimentally measured ethylbenzene adsorption amount and selectivity are shown in Table 2.

[0087] Table 1 Pore structure data results of adsorbent

[0088]

[0089] Table 2 Experimental measurement of ethylbenzene adsorption and selectivity

[0090]

[0091]

[0092] The results in Tables 1 and 2 show that the adsorbent prepared by the embodiment of the present invention has excellent pore structure characteristics thanks to the anchoring of alkali metals and the rich pore structure. The adsorbent prepared by the present invention has significantly higher ethylbenzene adsorption and ethylbenzene selectivity than the related art.

[0093] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing an adsorbent, characterized in that: The following steps are involved: Mixing a silicon source, an aluminum source and water to obtain a first mixed solution; the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, and the molar ratio of the silicon source, the aluminum source and water is 1:(0.5-2):(80-200); Mixing 2-aminoterephthalic acid, titanium isopropoxide, N,N-dimethylformamide and methanol to obtain a second mixed solution; The first mixed solution, the second mixed solution and an alkali metal salt solution are mixed to obtain a third mixed solution; the pH value of the third mixed solution is 8 to 9; subjecting the third mixed solution to a hydrothermal reaction to obtain a hydrothermal product; The hydrothermal product is calcined to obtain the adsorbent.

2. The preparation method according to claim 1, characterized in that: The silicon source includes one or more of sodium silicate, tetraethyl orthosilicate and silica sol, and the aluminum source includes one or more of sodium metaaluminate, aluminum sec-butoxide, aluminum isopropoxide and aluminum sulfate.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the 2-aminoterephthalic acid, titanium isopropoxide, N,N-dimethylformamide and methanol is 1:(0.8-1.3):50:

20.

4. The preparation method according to claim 1, characterized in that: The alkali metal salt in the alkali metal salt solution includes one or more of cesium chloride, rubidium chloride and potassium chloride, and the concentration of the alkali metal salt solution is 1 mol / L.

5. The preparation method according to claim 1 or 4, characterized in that: The mass ratio of the first mixed liquid to the second mixed liquid is 1:1; the mass ratio of the alkali metal salt solution to the mass of 2-aminoterephthalic acid in the second mixed liquid is (2-15):

1.

6. The preparation method according to claim 1, characterized in that: The pH value of the third mixed solution is adjusted by using an alkali metal hydroxide aqueous solution.

7. The preparation method according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 100-150° C., and the time is 12-48 hours; the temperature of the calcination is 180-200° C., and the time is 6-12 hours.

8. The adsorbent prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the adsorbent according to claim 8 to separate ethylbenzene from C8 mixed aromatics, wherein the C8 mixed aromatics include p-xylene, o-xylene, m-xylene and ethylbenzene.

10. The use according to claim 9, characterized in that: The method of application includes: The organic solution of C8 mixed aromatics is mixed with the adsorbent for adsorption; the mass fractions of p-xylene, o-xylene, m-xylene and ethylbenzene in the organic solution of C8 mixed aromatics are independently 1.9-2.5%, and the liquid-to-solid mass ratio of the organic solution of C8 mixed aromatics to the adsorbent is (3-10):1.

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