A bimetallic zif material, methods of making and using the same

Abstract

The application discloses a bimetallic Cu@ZIF-7 material and a preparation method thereof. 2+ Substituting part of Zn 2+ And a coordination is formed between the nitrogen atom and the copper atom, so that the Cu@ZIF-7 material has a good adsorption effect on methanol. The adsorbent has an obvious removal effect on trace methanol in an ethanol material liquid, and the adsorption capacity is up to 1.125 mg / g, which is 3.4 times of the adsorption capacity of a traditional molecular sieve.

Description

TECHNICAL FIELD

[0001] The application relates to a bimetallic ZIF material and a preparation method thereof, in particular to application of the bimetallic ZIF material in removal of trace methanol in an ethanol liquid. BACKGROUND

[0002] Application of metal organic framework compounds (MOF) in liquid phase adsorption / separation is one of important progresses in the field of adsorption separation, and zeolite imidazolate framework (ZIF) is composed of tetrahedral coordination transition metal ions connected by organic imidazole units, and has a similar structure to zeolite. The ZIF material has permanent porosity, and has the highest chemical stability and thermal stability among MOF materials.

[0003] Ethanol is widely used in fuel, medicine, food, paint and organic synthesis as a basic organic raw material. However, various organic by-products produced in the industrial ethanol production process pose a great threat to human health. The by-product methanol is very similar to ethanol in appearance and smell, and contact with methanol can cause irreversible damage to the nervous and blood systems, leading to impaired or even lost vision and even death. Therefore, purification and separation of ethanol is crucial in the process of ethanol production.

[0004] In the purification technology of ethanol, the adsorption method has the advantages of simple operation, economy and low energy consumption. The removal of methanol in industrial ethanol liquid is a big difficulty, especially the production of pharmaceutical industrial ethanol, which often requires higher removal of organic pollutants in ethanol. However, there are few related studies in this regard. Therefore, in the traditional adsorption technology purification route of industrial ethanol, the selectivity of the adsorbent is low, the removal rate of methanol is low, and the material cost required to reach the higher purification standard of the pharmacopoeia is high. A new purification method is needed to improve the selectivity of the adsorption process to improve the removal rate and reduce the production cost.

[0005] Xiancheng Ma et al. prepared nitrogen-rich porous carbon with high specific surface area by using nitrogen-rich ZIF-8 as a template and urea as a secondary nitrogen source. The content and type of nitrogen functional groups in the ZIF-8 / urea composite material can be adjusted by pyrolysis temperature, and the generated carbon has a highly polarized microporous structure, so it has a high affinity for methanol adsorption. ZIF has a higher diffusion selectivity for methanol than for ethanol, but the ZIF material containing only one type of imidazole linker has low selectivity for methanol, so the purity of the ethanol product is not high. Therefore, it is necessary to select a suitable ZIF material and improve the removal rate of methanol in ethanol. SUMMARY

[0006] The application aims to solve the problems of low selectivity of adsorbent to methanol, low product purity and high cost in the traditional adsorption method for purifying industrial ethanol, and provides a zeolite imidazolate framework material formed by Zn and Cu bimetal, namely Cu@ZIF-7. The Cu@ZIF-7 has high selectivity to methanol, thereby better realizing adsorption separation, and has the advantages of simple operation, low energy consumption and high methanol removal rate.

[0007] The technical scheme adopted to achieve the object of the application is:

[0008] A bimetallic ZIF material, which is a zeolite imidazolate framework material Cu@ZIF-7 formed by Zn and Cu bimetal.

[0009] The ZIF-7 material formed by Zn salt and benzimidazole is arranged in regular granular form, and has small particle size. Cu is introduced in the synthesis process of ZIF-7 2+ , so that the morphology of the Cu@ZIF-7 material changes. Compared with the granular micro-morphology of the conventional ZIF-7 nanoscale dodecahedron, the micro-morphology of the new Cu@ZIF-7 material is a micrometer-level sheet structure after the introduction of Cu 2+ . Due to the substitution of part of Zn 2+ by Cu 2+ , a new peak appears at about 935.08 eV, indicating that Cu 2+ is successfully introduced into the ZIF structure.

[0010] In a further preferred scheme, the number of Cu atoms in the Cu@ZIF-7 accounts for 1.14-3.31%.

[0011] The application further provides a preparation method of the Cu@ZIF-7, comprising the following steps:

[0012] 1) dissolving benzimidazole in an organic solvent to obtain solution A; dissolving a soluble zinc salt in N,N-dimethylformamide to obtain solution B; and dissolving a soluble copper salt in N,N-dimethylformamide to obtain solution C;

[0013] 2) pouring the solution A into a clean container, slowly pouring the solution B under stirring conditions, and then pouring the solution C to perform a coordination reaction;

[0014] 3) after the reaction is completed, filtering, drying and grinding to obtain the Cu@ZIF-7.

[0015] In the preparation method of the Cu@ZIF-7, a Zn and Cu bimetallic ZIF material, namely Cu@ZIF-7, is prepared based on benzimidazole.

[0016] In a further preferred aspect, the molar ratio of the benzimidazole, the soluble zinc salt, and the soluble copper salt is 1:1:0.2-2. By adjusting the molar amount of the soluble zinc salt and the soluble copper salt, the microstructure of the Cu@ZIF-7 material changes, and with the increase of the molar amount of Cu 2+ the molar amount of Cu, the microscale sheet structure of the Cu@ZIF-7 material is more obvious, and the adsorption selectivity for methanol is stronger, and therefore, in a still further preferred aspect, the molar ratio of the benzimidazole, the soluble zinc salt, and the soluble copper salt is 1:1:0.5-1.5, and in a still more preferred aspect, the molar ratio of the benzimidazole, the soluble zinc salt, and the soluble copper salt is 1:1:0.5.

[0017] In a further preferred aspect, the molar concentration of the benzimidazole in the solution A is 0.2-1.5 mol / L.

[0018] In a further preferred aspect, the molar concentration of the soluble zinc salt in the solution B is 0.2-1.5 mol / L.

[0019] In a further preferred aspect, the molar concentration of the soluble copper salt in the solution C is 0.05-3 mol / L.

[0020] In a further preferred aspect, the volume ratio of the solution A, the solution B, and the solution C can be the same or different.

[0021] In a still further preferred aspect, the volume ratio of the solution A, the solution B, and the solution C is 1:1:1.

[0022] In a further preferred aspect, the coordination reaction time in step 2) is 15-24 h.

[0023] In the above method for preparing Cu@ZIF-7, the organic solvent in step 1) can be methanol or ethanol or acetonitrile, and preferably methanol; the soluble zinc salt can be one of zinc acetate dihydrate, zinc nitrate, zinc sulfate, and zinc chloride, and preferably zinc acetate dihydrate; and the soluble copper salt can be one of copper chloride dihydrate, copper nitrate, and copper sulfate, and preferably copper chloride dihydrate.

[0024] In a further preferred aspect, when preparing the solution A, B, or C, a stirrer can be used to accelerate the dissolution of the solvent, and when mixing two substances in other steps, stirring can also be used, and the stirring time and stirring speed are determined according to the specific circumstances, which are not limited in the present application.

[0025] In a further preferred aspect, the container in the present application is a conventional container in the field, and the size and material are not limited, and a person skilled in the art can select according to the actual situation.

[0026] The Cu@ZIF-7 material described in the application can also be used to remove trace amounts of methanol in an ethanol feed liquid, and the adsorption amount of methanol in the ethanol feed liquid by the Cu@ZIF-7 is 1.059-1.125 mg / g. Through the static adsorption experiment test, the adsorption selectivity of the new adsorbent Cu@ZIF-7 to trace amounts of methanol is significantly improved, and the method has the advantages of simple operation, low energy consumption and high product purity.

[0027] The step of removing trace amounts of methanol in an ethanol feed liquid comprises: adding Cu@ZIF-7 into a clean container, then adding an industrial ethanol feed liquid into the container, sealing, and continuously shaking until adsorption equilibrium.

[0028] The pore size of the Cu@ZIF-7 material is 0.43 nm, the molecular diameter of methanol is 0.38 nm, and the molecular diameter of ethanol is 0.44 nm. From the perspective of molecular diameter, it can be seen that the Cu@ZIF-7 material can more easily adsorb methanol. Metal site substitution is a valuable strategy for adjusting the adsorption performance of ZIF materials. By replacing the metal nodes in the ZIF material, new adsorption sites can be introduced while ensuring the structural stability of the ZIF material. In the Cu@ZIF-7 agent material, Cu is doped, which exposes the Cu(111) crystal plane. Methanol molecules can be adsorbed on the metal surface through their oxygen atoms and form two hydrogen bonds with other methanol molecules around them through hydroxyl groups. Methanol has two hydrogen bond structures on the Cu(111), namely linear chains and cyclic hexamers (i.e. a ring of six methanol molecules), which makes the Cu-doped ZIF material have high adsorption capacity and good selectivity. Using the Cu@ZIF-7 material to remove trace amounts of methanol in an ethanol feed liquid has the advantages of simple operation, low energy consumption and high product purity.

[0029] In an industrial ethanol feed liquid, the content of methanol is generally 0.03-0.5%.

[0030] In a further preferred embodiment of the method for removing trace amounts of methanol in an ethanol feed liquid, the adsorption temperature is 20-50°C, and the adsorption time is 10-24 h.

[0031] Compared with the prior art, the application has the following advantages:

[0032] (1) The Cu@ZIF-7 prepared by the application successfully introduces Cu 2+ into the ZIF-7 material to obtain a micrometer-sized sheet-shaped material.

[0033] (2) The zeolite imidazolate framework material Cu@ZIF-7 formed by the Zn and Cu bimetal prepared by the application has better adsorption selectivity to methanol, which significantly improves the removal effect of trace amounts of methanol in an ethanol feed liquid, and the adsorption amount of methanol is as high as 1.125 mg / g, which is higher than that of the traditional 3.4 times the adsorption capacity of the molecular sieve (0.329 mg / g). BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 SEM (scanning electron microscope) images of the novel Cu@ZIF-7 adsorbents prepared for the present comparative example 2 (left), example 3 (middle) and example 5 (right).

[0035] Figure 2 XPS (X-ray photoelectron spectroscopy) images of the novel Cu@ZIF-7 adsorbents prepared for the present comparative example 2 (bottom), example 3 (middle) and example 5 (top).

[0036] Figure 3 Adsorption performance of the novel Cu@ZIF-7 prepared for the present comparative example 1 (4A), comparative example 2 (ZIF-7), example 2 (4:1), example 3 (2:1) and example 5 (1:1) on trace methanol in industrial ethanol feed liquid. DETAILED DESCRIPTION

[0037] The technical solutions of the present application will be described clearly and completely below in conjunction with specific embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0038] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. All the numerical identifiers, such as pH, temperature, length, flow rate, including ranges, are approximate values. It should be understood that although the term "about" is not always explicitly stated before all the numerical identifiers. It should also be understood that although the reagents described in the present application are only examples, their equivalents are known in the art.

[0039] The present application provides a zeolitic imidazolate framework material formed by Zn and Cu bimetal, i.e. Cu@ZIF-7, a preparation method of the Cu@ZIF-7, comprising the following steps:

[0040] 1) Dissolve benzimidazole in methanol, stir to mix uniformly to obtain solution A; dissolve zinc acetate dihydrate in N,N-dimethylformamide, stir to mix uniformly to obtain solution B; dissolve copper chloride dihydrate in N,N-dimethylformamide, stir to mix uniformly to obtain solution C;

[0041] 2) Pour the solution A into a clean container, slowly pour the solution B under stirring condition, then slowly pour the solution C, under stirring condition, coordinate reaction is carried out;

[0042] 3) After the reaction is completed, filtration, drying and grinding are carried out to obtain Cu@ZIF-7.

[0043] Optionally, the stirring speed and time can be determined according to specific conditions, and the stirring mode can also be determined according to specific scenes, as long as the purpose of reagent dissolution or mixing can be achieved.

[0044] Optionally, the molar ratio of the benzimidazole, the zinc acetate dihydrate and the copper chloride dihydrate is 1:1:0.2-2.

[0045] Optionally, the molar concentration of the benzimidazole in the solution A is 0.2-1.5 mol / L, the molar concentration of the zinc acetate dihydrate in the solution B is 0.2 mol / L-1.5 mol / L, and the molar concentration of the copper chloride dihydrate in the solution C is 0.05-3 mol / L.

[0046] The volume ratio of the solution A, the solution B and the solution C can be the same or different, and in a specific embodiment, the volume ratio is taken as an example, and the specific addition volume can be determined according to the required amount of material and the specific reaction scene.

[0047] Optionally, the reaction time of the step 2) is 15-24 h, the reaction temperature is room temperature, and the stirring mode and speed can be adjusted according to actual conditions.

[0048] Optionally, the operation processes such as filtration, drying and grinding can also be operated by selecting appropriate instrument equipment according to specific application scenes, the drying time can be adjusted according to specific conditions, the grinding degree is powdery, and the specific mode can be adjusted according to actual conditions.

[0049] Figure 1 The scanning electron microscope graph of the Cu@ZIF-7 material is shown in the figure, from which it can be seen that the ZIF-7 alone is a nano-level dodecahedral particle, after the introduction of Cu 2+ , the microstructure of the novel Cu@ZIF-7 material is a micrometer-level sheet structure. In addition, the introduced Cu 2+ has different molar amounts, and the sheet structure also has some differences.

[0050] Figure 2 The X-ray photoelectron spectroscopy analysis of the Cu@ZIF-7 material is shown in the figure, from which it can be seen that a new peak appears at about 935.08 eV, indicating that Cu 2+ is successfully introduced into the ZIF structure.

[0051] The Cu@ZIF-7 material described in the present application can also be used to remove trace amounts of methanol in an ethanol feed liquid, and the adsorption amount of the Cu@ZIF-7 for methanol in the ethanol feed liquid is 1.059-1.125 mg / g.

[0052] The method for removing trace amounts of methanol in an ethanol feed liquid by using the Cu@ZIF-7 material includes the following process: a certain amount of Cu@ZIF-7 is weighed and added to a clean container, industrial ethanol feed liquid is then added to the container, the container is sealed, and constant shaking is performed at a certain temperature until adsorption equilibrium is reached.

[0053] The amount of Cu@ZIF-7 added can be adjusted according to the amount of industrial ethanol, and optionally, 2 g of Cu@ZIF-7 can be added to 20 ml of industrial ethanol feed liquid, or the amount of adsorbent added can be appropriately increased or decreased according to the content of methanol in the ethanol feed liquid.

[0054] The container can be selected according to the size and material of the container according to the amount of industrial ethanol added.

[0055] Optionally, the adsorption temperature is 20-50℃, and the adsorption time is 10-24 h. The adsorption temperature and time can also be appropriately adjusted according to the specific application scenario.

[0056] The test method for the adsorption amount of the Cu@ZIF-7 is to test the concentration of methanol in the feed liquid before and after adsorption by gas chromatography, use the standard curve method to obtain the methanol concentration, and calculate the adsorption amount. (The calculation formula for the adsorption amount in the examples is: Q = ((C0-C1) x V) / m, where C0 and C1 are the concentrations of methanol in the feed liquid before and after adsorption, mg / L; V is the volume of the feed liquid, L; and m is the mass of the adsorbent added, g).

[0057] Figure 3 The adsorption performance diagram of the novel Cu@ZIF-7 prepared in Comparative Example 1 (4A), Comparative Example 2 (ZIF-7), Example 2 (4:1), Example 3 (2:1), and Example 5 (1:1) for trace amounts of methanol in industrial ethanol feed liquid can be seen from the figure, and it can be seen that when the molar ratio of Zn:Cu is 2:1, the prepared Cu@ZIF-7 material has better adsorption effect for methanol.

[0058] Example 1

[0059] (1) 4.8901 g of benzimidazole was dissolved in 80 mL of methanol, and stirred to mix uniformly to obtain solution A; 9.2895 g of zinc acetate dihydrate was dissolved in 80 mL of DMF, and stirred to mix uniformly to obtain solution B; 1.5098 g of copper chloride dihydrate was dissolved in 80 mL of DMF, and stirred to mix uniformly to obtain solution C;

[0060] (2) Take a clean beaker, pour the above solution A into a clean beaker, slowly pour the above solution B under stirring conditions, then slowly pour solution C, place on a magnetic stirrer for continuous stirring reaction for 15h;

[0061] (3) After the reaction is completed, the filter cake is dried and ground, and the solid product is prepared to obtain a ZIF-Zn-Cu bimetallic ZIF material, namely Cu@ZIF-7;

[0062] (4) 2.0g of the above Cu@ZIF-7 is weighed into a clean 30mL sealed bottle, and industrial ethanol model liquid (20mL) containing 0.10% methanol is added;

[0063] (5) The sealed bottle is placed in a shaker at 35°C and adsorbed for 12h to equilibrium.

[0064] The adsorption capacity of the Cu@ZIF-7 material obtained in Example 1 for methanol reaches 1.059mg / g.

[0065] Example 2

[0066] (1) 8.6258g of benzimidazole is dissolved in 80mL of methanol, stirred to mix uniformly to obtain solution A; 16.0188g of zinc acetate dihydrate is dissolved in 80mL of DMF, stirred to mix uniformly to obtain solution B; 3.1124g of copper chloride dihydrate is dissolved in 80mL of DMF, stirred to mix uniformly to obtain solution C;

[0067] (2) Take a clean beaker, pour the above solution A into a clean beaker, slowly pour the above solution B under stirring conditions, then slowly pour solution C, place on a magnetic stirrer for continuous stirring reaction for 18h;

[0068] (3) After the reaction is completed, the filter cake is dried and ground, and the solid product is prepared to obtain a ZIF-Zn-Cu bimetallic ZIF material, namely Cu@ZIF-7;

[0069] (4) 2.0g of the above Cu@ZIF-7 is weighed into a clean 30mL sealed bottle, and industrial ethanol model liquid (20mL) containing 0.03% methanol is added;

[0070] (5) The sealed bottle is placed in a shaker at 30°C and adsorbed for 20h to equilibrium.

[0071] The adsorption capacity of the Cu@ZIF-7 material obtained in Example 2 for methanol reaches 1.078mg / g.

[0072] Example 3

[0073] (1) 5.9113 g of benzimidazole was dissolved in 80 mL of methanol, stirred to mix uniformly to obtain solution A; 10.9066 g of zinc acetate dihydrate was dissolved in 80 mL of DMF, stirred to mix uniformly to obtain solution B; 4.2435 g of copper chloride dihydrate was dissolved in 80 mL of DMF, stirred to mix uniformly to obtain solution C;

[0074] (2) A clean beaker was taken, the above solution A was poured into the clean beaker, the above solution B was slowly poured under stirring, and then the solution C was slowly poured, and the continuous stirring reaction was carried out for 20 h on a magnetic stirrer;

[0075] (3) After the reaction was completed, the filter cake was dried after filtration, and the solid product was ground to prepare a ZIF-Zn-Cu bimetallic ZIF material, namely Cu@ZIF-7.

[0076] (4) 2.0 g of the above Cu@ZIF-7 was weighed into a clean 30 mL sealed bottle, and an industrial ethanol model liquid (20 mL) with a methanol content of 0.03% was added.

[0077] (5) The sealed bottle was placed in a shaker at 25°C, and adsorbed for 24 h to equilibrium.

[0078] The adsorption amount of the Cu@ZIF-7 material obtained in Example 3 for methanol reached 1.125 mg / g.

[0079] Example 4

[0080] (1) 3.0673 g of benzimidazole was dissolved in 80 mL of methanol, stirred to mix uniformly to obtain solution A; 5.4965 g of zinc acetate dihydrate was dissolved in 80 mL of DMF, stirred to mix uniformly to obtain solution B; 3.3824 g of copper chloride dihydrate was dissolved in 80 mL of DMF, stirred to mix uniformly to obtain solution C.

[0081] (2) A clean beaker was taken, the above solution A was poured into the clean beaker, the above solution B was slowly poured under stirring, and then the solution C was slowly poured, and the continuous stirring reaction was carried out for 24 h on a magnetic stirrer.

[0082] (3) After the reaction was completed, the filter cake was dried after filtration, and the solid product was ground to prepare a ZIF-Zn-Cu bimetallic ZIF material, namely Cu@ZIF-7.

[0083] (4) 2.0 g of the above Cu@ZIF-7 was weighed into a clean 30 mL sealed bottle, and an industrial ethanol model liquid (20 mL) with a methanol content of 0.03% was added.

[0084] (5) The sealed bottle is placed in a shaker at 25°C, and adsorption is carried out for 24 h to reach equilibrium.

[0085] The Cu@ZIF-7 material obtained in Example 4 has a methanol adsorption capacity of 1.096 mg / g.

[0086] Example 5

[0087] (1) 2.1576 g of benzimidazole is dissolved in 80 mL of methanol, and stirred to mix uniformly to obtain solution A; 4.0407 g of zinc acetate dihydrate is dissolved in 80 mL of DMF, and stirred to mix uniformly to obtain solution B; 3.2418 g of copper chloride dihydrate is dissolved in 80 mL of DMF, and stirred to mix uniformly to obtain solution C;

[0088] (2) A clean beaker is taken, and the above solution A is poured into the clean beaker, and the above solution B is slowly poured in under stirring, and then the solution C is slowly poured in, and continuous stirring is carried out on a magnetic stirrer for 20 h;

[0089] (3) After the reaction is completed, the filter cake is filtered and dried, and the solid product is ground to obtain a ZIF-Zn-Cu bimetallic ZIF material, namely Cu@ZIF-7;

[0090] (4) 2.0 g of the above Cu@ZIF-7 is weighed and added to a clean 30 mL sealed bottle, and 20 mL of an industrial ethanol model liquid with a methanol content of 0.50% is added thereto;

[0091] (5) The sealed bottle is placed in a shaker at 40°C, and adsorption is carried out for 18 h to reach equilibrium.

[0092] The Cu@ZIF-7 material obtained in Example 5 has a methanol adsorption capacity of 1.093 mg / g.

[0093] Example 6

[0094] (1) 10.1402 g of benzimidazole is dissolved in 80 mL of methanol, and stirred to mix uniformly to obtain solution A; 19.8103 g of zinc acetate dihydrate is dissolved in 80 mL of DMF, and stirred to mix uniformly to obtain solution B; 23.0271 g of copper chloride dihydrate is dissolved in 80 mL of DMF, and stirred to mix uniformly to obtain solution C;

[0095] (2) A clean beaker is taken, and the above solution A is poured into the clean beaker, and the above solution B is slowly poured in under stirring, and then the solution C is slowly poured in, and continuous stirring is carried out on a magnetic stirrer for 24 h;

[0096] (3) After the reaction is completed, the filtered cake is dried after filtration, and the solid product is ground to obtain a ZIF-Zn-Cu bimetallic ZIF material, namely Cu@ZIF-7;

[0097] (4) 2.0 g of the above Cu@ZIF-7 is weighed into a clean 30 mL sealed bottle, and an industrial ethanol model liquid with a methanol content of 0.20% (20 mL) is added thereto;

[0098] (5) The sealed bottle is placed in a shaker at 20°C, and adsorption is carried out for 24 h to equilibrium.

[0099] The adsorption amount of the Cu@ZIF-7 material obtained in Example 6 for methanol reaches 1.107 mg / g.

[0100] Example 7

[0101] (1) 7.4597 g of benzimidazole is dissolved in 80 mL of methanol, and stirred to mix uniformly to obtain solution A; 13.8853 g of zinc acetate dihydrate is dissolved in 80 mL of DMF, and stirred to mix uniformly to obtain solution B; 22.0587 g of copper chloride dihydrate is dissolved in 80 mL of DMF, and stirred to mix uniformly to obtain solution C;

[0102] (2) A clean beaker is taken, and the above solution A is poured into the clean beaker, and the above solution B is slowly poured under stirring, and then the solution C is slowly poured, and continuous stirring is carried out on a magnetic stirrer for 24 h;

[0103] (3) After the reaction is completed, the filtered cake is dried after filtration, and the solid product is ground to obtain a ZIF-Zn-Cu bimetallic ZIF material, namely Cu@ZIF-7;

[0104] (4) 2.0 g of the above Cu@ZIF-7 is weighed into a clean 30 mL sealed bottle, and an industrial ethanol model liquid with a methanol content of 0.35% (20 mL) is added thereto;

[0105] (5) The sealed bottle is placed in a shaker at 50°C, and adsorption is carried out for 10 h to equilibrium;

[0106] The adsorption amount of the Cu@ZIF-7 material obtained in Example 7 for methanol reaches 1.084 mg / g.

[0107] Comparative Example 1

[0108] (1) 2.0 g of the above Cu@ZIF-7 is weighed into a clean 30 mL sealed bottle, and an industrial ethanol model liquid with a methanol content of 0.03% (20 mL) is added thereto;

[0109] ​(2) The sealed bottle was placed in a shaker at 25°C, and adsorption was carried out for 24 h to reach equilibrium.

[0110] The ZIF-7 material obtained in Comparative Example 1 was analyzed. The adsorption amount of methanol on the molecular sieve adsorbent was 0.329 mg / g.

[0111] Comparative Example 2

[0112] (1) 3.5207 g of benzimidazole was dissolved in 80 mL of methanol, and stirred to mix uniformly to obtain solution A. 6.6959 g of zinc acetate dihydrate was dissolved in 80 mL of DMF, and stirred to mix uniformly to obtain solution B;

[0113] (2) A clean beaker was taken, and the above solution A was poured into the clean beaker, and the above solution B was slowly poured under stirring, and continuous stirring was carried out on a magnetic stirrer for 24 h;

[0114] (3) After the reaction was completed, the filtered cake was dried and ground to obtain the ZIF-Zn-Cu bimetallic ZIF material, i.e. Cu@ZIF-7;

[0115] (4) 2.0 g of the above Cu@ZIF-7 was taken into a clean 30 mL sealed bottle, and 20 mL of industrial ethanol model liquid containing 0.03% of methanol was added;

[0116] (5) The sealed bottle was placed in a shaker at 25°C, and adsorption was carried out for 24 h to reach equilibrium.

[0117] The adsorption amount of methanol on the ZIF-7 material obtained in Comparative Example 2 was 1.035 mg / g.

[0118] Table 1 Percentage of atomic number content of C, N, Cu and Zn in ZIF-7 and Cu@ZIF-7 materials

[0119] ZIF-7 / % Zn 2+ :Cu 2+ (2:1) / %]]> Zn 2+ :Cu 2+ (1:1) / %]]> C (1 s) 73.74 73.88 73.36 Cu (2p) - 1.14 3.31 N (1 s) 16.81 16.84 19.67 Zn (2p) 9.45 8.14 3.66

[0120] As can be seen from Table 1, when the molar ratio of Zn 2+ to Cu 2+ in the reaction raw material was 2:1, the atomic number of Cu(2p) in the prepared Cu@ZIF-7 material was 1.14%, and when the molar ratio of Zn 2+ to Cu 2+ in the reaction raw material was 1:1, the atomic number of Cu(2p) in the prepared Cu@ZIF-7 material was 3.31% (corresponding to Figure 2 ). Therefore, with the increase of the molar amount of Cu 2+ in the raw material, the content of Cu(2p) in the material also increased within a certain range.

[0121] Table 2

[0122]

[0123] As can be seen from Table 2, Zn 2+ With Cu 2+ The molar ratio of Cu to ZIF-7 has a certain influence on the adsorption of methanol by the prepared Cu@ZIF-7 adsorbent. 2+ With increasing Zn content, the adsorption capacity of Cu@ZIF-7 adsorbent for methanol increases, and when Zn... 2+ With Cu 2+ When the molar ratio of Cu to ZIF-7 is 1:0.5, the adsorption capacity of Cu@ZIF-7 adsorbent for methanol reaches its maximum. Further increasing the Cu content... 2+ The adsorption capacity of Cu@ZIF-7 adsorbent for methanol actually decreased due to the reduced Zn content. 2+ With Cu 2+ The preferred molar ratio is 1:0.5 to 1.5, with the optimal Zn... 2+ With Cu 2+ The molar ratio is 1:0.5.

[0124] Compared with Comparative Example 1, the Cu@ZIF-7 adsorbent of the present invention has an adsorption capacity of 1.125 mg / g for methanol under the same conditions. The molecular sieve's adsorption capacity for methanol is only 0.329 mg / g. Therefore, under the same adsorption conditions, the adsorption capacity of the Cu@ZIF-7 adsorbent for methanol is... 3.4 times that of molecular sieves.

[0125] Compared with Comparative Example 2, Example 3 shows that the introduction of Cu into ZIF-7 significantly increases the adsorption capacity of the ZIF material for methanol. This is because Cu... 2+ The introduction of [a specific substance] exposes the Cu(111) crystal plane. Methanol molecules can adsorb onto the metal surface through their oxygen atoms and form two hydrogen bonds with other surrounding methanol molecules through hydroxyl groups. The adsorption of methanol on Cu(111) exhibits two hydrogen bond structures: linear chains and cyclic hexamers (i.e., a ring of six methanol molecules). This makes Cu-doped [a specific substance] more suitable for [a specific process]. 2+ The adsorbent has high adsorption capacity and good selectivity.

[0126] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. Use of a bimetallic ZIF material for the removal of trace amounts of methanol from an ethanol feed, characterized in that, The bimetallic ZIF material is a zeolite imidazolate framework material Cu@ZIF-7 formed by Zn and Cu bimetals, the number of Cu atoms in the Cu@ZIF-7 accounts for 1.14-3.31%, and the Cu@ZIF-7 has a micron-level sheet structure.

2. Use of the bimetallic ZIF material of claim 1 for the removal of trace amounts of methanol from an ethanol feed, characterized in that, The preparation method of the Cu@ZIF-7 comprises the following steps: 1) dissolving benzimidazole in an organic solvent to obtain solution A; dissolving a soluble zinc salt in N,N-dimethylformamide to obtain solution B; and dissolving a soluble copper salt in N,N-dimethylformamide to obtain solution C; 2) pouring the solution A into a clean container, slowly pouring the solution B under stirring, and then pouring the solution C to perform a coordination reaction; 3) after the reaction is completed, filtering, drying and grinding to obtain the Cu@ZIF-7.

3. Use of the bimetallic ZIF material of claim 2 for the removal of trace amounts of methanol from an ethanol feed, wherein, The molar ratio of the benzimidazole, the soluble zinc salt and the soluble copper salt is 1:1:0.2-2.

4. Use of the bimetallic ZIF material of claim 2 for the removal of trace amounts of methanol from an ethanol feed, wherein, The molar ratio of the benzimidazole, the soluble zinc salt and the soluble copper salt is 1:1:0.5-1.

5.

5. Use of the bimetallic ZIF material of claim 2 for the removal of trace amounts of methanol from an ethanol feed, characterized in that, The molar ratio of the benzimidazole, the soluble zinc salt and the soluble copper salt is 1:1:0.

5.

6. Use of the bimetallic ZIF material of claim 2 for the removal of trace amounts of methanol from an ethanol feed, characterized in that, The molar concentration of the benzimidazole in the solution A is 0.2-1.5 mol / L; the molar concentration of the soluble zinc salt in the solution B is 0.2 mol / L-1.5 mol / L; and the molar concentration of the soluble copper salt in the solution C is 0.05-3 mol / L.

7. Use of the bimetallic ZIF material of claim 2 for the removal of trace amounts of methanol in ethanol feedstocks, characterized in that, The volume ratio of the solvents of the solution A, the solution B and the solution C is 1:1:

1.

8. Use of the bimetallic ZIF material of claim 2 for the removal of trace amounts of methanol from an ethanol feed, characterized in that, The coordination reaction time of the step 2) is 15-24 h.

9. Use of the bimetallic ZIF material of claim 1 for the removal of trace amounts of methanol in ethanol feedstocks, characterized in that, The adsorption amount of the Cu@ZIF-7 to methanol in an ethanol feed liquid is 1.059-1.125 mg / g.

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