A method of forming ZIF-8

Abstract

The application belongs to the technical field of porous material preparation and application, and relates to a ZIF-8 forming method, which comprises the following steps: mixing ZIF-8 powder, water or nitric acid and a binder, adding a glue solvent to knead into a ball, tabletting, balling, drying and obtaining spherical ZIF-8 material; the binder comprises at least one of sesbania powder, methyl cellulose and acid clay. Compared with the prior art, the application optimizes the synthesis conditions, obtains a method for preparing ZIF-8 in large quantities and a forming method thereof, and the spherical ZIF-8 prepared by the application has good mechanical strength and no obvious damage to the skeleton structure, and achieves the effect of industrial production and application.

Description

Technical Field

[0001] This invention belongs to the field of porous material preparation and application technology, and relates to a ZIF-8 molding method. Background Technology

[0002] Zeolitic imidazolate frameworks (ZIFs) are MOFs with a zeolite framework structure, combining the characteristics of both zeolites and MOFs. They possess large specific surface area and pore volume, with tunable pore size, and exhibit high stability compared to other types of MOFs, making them promising for applications in various industrial and engineering fields. ZIF-8, a typical material in the ZIF series, has been the subject of extensive research into its properties, synthesis, and molding methods.

[0003] Patent CN103230777A from Beijing University of Chemical Technology discloses a preparation method and tableting method using N,N-dimethylformamide as a solvent, and investigates its adsorption performance on propane gas. However, the preparation method of this patented technology uses N,N-dimethylformamide as a solvent, which is highly toxic, and the post-processing of the product is cumbersome; the tableting method is not conducive to its large-scale industrial production and application.

[0004] Patent CN103611502A from Tianjin University of Technology discloses a method for preparing a non-woven fabric oil adsorption bag coated with ZIF-8 adsorbent. This patented technology uses a heat-sealing method to encapsulate the prepared ZIF-8 in a non-woven fabric "pocket," creating a novel marine oil adsorption device and realizing the "form-forming" application of ZIF-8. However, this patented technology has a narrow application scope and is difficult to apply to large-scale industrial adsorption and separation operations, and the "form-forming" cost is high.

[0005] Patent CN104817577A from Guangdong University of Technology discloses an efficient and simple method for preparing ZIF-8 crystals with different morphologies. This patented technology uses toluene as the reaction solvent and obtains ZIF-8 crystals with different morphologies by changing different zinc salts. However, most of the 2-methylimidazole in this patented technology does not react, resulting in reagent waste, low reaction yield, and high cost. Furthermore, the subsequent centrifugation speed for product separation is extremely high, making large-scale production conditions very demanding. Therefore, this technology is only suitable for laboratory scientific research and is difficult to mass-produce and apply industrially.

[0006] In summary, there is an urgent need to further explore and refine the synthesis reaction conditions of ZIF-8, comprehensively improving the yield and reducing the particle size of ZIF-8. Simultaneously, increasing the single-reactor reaction volume should not significantly alter the properties of the prepared material, or at least allow for scaled-up synthesis towards improved performance. Regarding ZIF-8 forming, relevant research papers and patents all borrow from molecular sieve forming and catalyst forming methods, employing the addition of binders and solvents to compress the material into tablets. This inevitably damages the material's framework, affecting its properties, and the tablet form is also inconvenient for industrial applications. Currently, there are no reports of successfully forming ZIF-8. This invention achieves a breakthrough in this area, and the structure and adsorption properties of the formed material remain essentially unchanged. Summary of the Invention

[0007] The purpose of this invention is to provide a method for forming ZIF-8 spherical particles with moderate mechanical strength. By optimizing the synthesis conditions, a method and its forming method for mass-producing ZIF-8 zeolite imidazole ester framework materials are obtained. Furthermore, the spherical zeolite imidazole ester framework materials prepared by this invention exhibit good mechanical strength and no significant damage to the framework structure, achieving the effect of industrial production and application.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] A ZIF-8 molding method includes: mixing ZIF-8 powder with water or nitric acid and a binder, adding a glue solvent and kneading into a dough, pressing into a sheet, forming into a ball, and drying to obtain spherical ZIF-8 material;

[0010] The binder includes at least one of guar gum powder, methylcellulose, and acid clay.

[0011] Furthermore, during the heating process, the heating temperature is 120-180℃, and the heating time is 2-5 hours.

[0012] Furthermore, the mixture of the ZIF-8 powder heating product and the binder comprises the following components and their weight percentages:

[0013]

[0014] Furthermore, the mass content of the nitric acid is 3-7 wt%.

[0015] Furthermore, the amount of nitric acid or water used is 1-3 wt% of the ZIF-8 powder heating product.

[0016] Furthermore, the adhesive solvent is water. Preferably, the amount used is 1-3 times the mass of the ZIF-8 powder.

[0017] Furthermore, the average particle size of the spherical ZIF-8 material is 3-8 mm.

[0018] Furthermore, the sheet is formed by rolling.

[0019] Furthermore, after compression, the resulting sheet thickness is 4-6 mm.

[0020] Furthermore, in the drying process, the drying temperature is 180-200℃ and the drying time is 6-8 hours.

[0021] Furthermore, the average particle size of the spherical ZIF-8 material is 4-6 mm.

[0022] Furthermore, the spherical ZIF-8 material is protected from excessive pressure during the tableting, pelletizing, and drying processes.

[0023] Furthermore, the preparation method of the ZIF-8 powder includes: mixing 2-methylimidazole, zinc nitrate, and sodium formate, and carrying out a crystallization reaction, followed by filtration, washing, and drying.

[0024] Further, the mass ratio of 2-methylimidazole, zinc nitrate, and sodium formate is (5-50):(10-50):(10-25), wherein the zinc nitrate is calculated as zinc nitrate hexahydrate.

[0025] Furthermore, the molar ratio of 2-methylimidazole to zinc nitrate is 0.5-5:1.

[0026] Furthermore, in the crystallization reaction, the reaction temperature is 50–150°C, and the reaction time is 6–24 h.

[0027] Furthermore, in the crystallization reaction, no programmed temperature rise is set; the temperature is directly set, which is a simple method.

[0028] Furthermore, in the crystallization reaction, the reaction solvent is methanol.

[0029] Furthermore, during the crystallization reaction, the system was stirred at a speed of 0-1500 rpm.

[0030] Furthermore, after the crystallization reaction, the mixture is cooled to room temperature, washed with methanol, and dried.

[0031] Compared with the prior art, the present invention has the following characteristics:

[0032] 1) The ZIF-8 crystals synthesized by the method of this invention have high crystallinity, large specific surface area, and smaller crystal particle size, with a yield of up to 84% (calculated results are the same for both reactants). It exhibits good reproducibility, with no significant changes in the crystal structure, specific surface area, pore size distribution, and other characteristics. It also boasts high reusability and significantly improved adsorption performance. Simple scale-up of the raw materials leads to varying degrees of improvement in product yield and specific surface area, demonstrating that the scale-up effect is beneficial to material synthesis.

[0033] 2) During the molding process, the addition of additives can improve the mechanical properties of the material, but on the other hand, it can also reduce the product's usability. Therefore, the selection and content control of additives are crucial to the application of the product. Powder material molding mainly includes compression molding, extrusion molding, and rotational molding. However, the first two methods cause significant damage to the original powder structure and greatly reduce adsorption characteristics. Rotational molding, on the other hand, applies moderate pressure and produces uniform particles. Therefore, this invention selected rotational molding to conduct molding studies on ZIF-8 synthesized by the optimized method. The molded samples prepared by this invention have suitable mechanical strength, the molding method causes virtually no damage to the material structure, and the specific surface area of ​​the molded material is not significantly reduced. Furthermore, this molding method is simple to operate, environmentally friendly (the solvent is water), and the spherical ZIF-8 can maintain almost the same properties as the original powder. Attached Figure Description

[0034] Figure 1 The images show electron micrographs of the ZIF-8 raw powder prepared in the examples (left: Example 7, without stirring; right: Example 13, stirring speed 800 r / min); wherein the molar ratio of zinc nitrate hexahydrate to 2-methylimidazole is 2:1.

[0035] Figure 2 The images show a comparison of the appearance of ZIF-8 prepared in Example 13 before and after molding.

[0036] Figure 3 This is a comparison of the nitrogen adsorption isotherms of ZIF-8 prepared in Example 13 before and after molding. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0038] Example 1:

[0039] A method for scaled-up preparation and molding of ZIF-8 includes the following steps:

[0040] S1: Add 200mL of methanol solvent to a 250mL polytetrafluoroethylene liner, add the weighed 2-methylimidazole and zinc nitrate hexahydrate and 25g of sodium formate, and add a PTFE rotor of appropriate size. Stir on a magnetic stirrer until clear, wherein the zinc nitrate hexahydrate is 29.7g, the 2-methylimidazole is 16.4g, and the molar ratio is 0.5:1;

[0041] S2: Cover the polytetrafluoroethylene liner containing the rotor and the above-mentioned clarified solution, and place it in a heating and stirring controller with a rotation speed of 0 revolutions per minute and a set temperature of 150°C for 24 hours.

[0042] S3: Remove the reacted polytetrafluoroethylene liner and cool it to room temperature with water. Filter the milky white liquid obtained from the reaction in the liner and wash it with methanol more than 3 times. Then dry it at 80°C for more than 12 hours.

[0043] S4: Use a pulverizer to pulverize the dried block ZIF-8 into powder, dry it at 150℃ for 3 hours, and then add 10wt% guar gum powder as binder (the remaining 90wt% is ZIF-8 powder), 2wt% ZIF-8 powder and a 5wt% nitric acid solution, and grind and mix them thoroughly in a mortar.

[0044] S5: Gradually add small amounts of deionized water as a gum arabic until ZIF-8 is kneaded into a dough; wherein, the amount of deionized water used is equal to the amount of ZIF-8 powder used in step S4;

[0045] S6: Press the ZIF-8 dough into a rectangular sheet about 5 mm thick, then use a spherical forming machine to form spheres, and dry at 180°C for 6 hours to obtain spherical ZIF-8 material with a diameter of 5 mm.

[0046] Example 2:

[0047] A method for scaled-up preparation and molding of ZIF-8 includes the following steps:

[0048] S1: Add 200mL of methanol solvent to a 250mL polytetrafluoroethylene liner, add the weighed 2-methylimidazole and zinc nitrate hexahydrate and 25g of sodium formate, and add a PTFE rotor of appropriate size. Stir on a magnetic stirrer until clear. The mixture contains 24g of zinc nitrate hexahydrate and 6.6g of 2-methylimidazole, with a molar ratio of 2:1.

[0049] S2: Cover the polytetrafluoroethylene liner containing the rotor and the above-mentioned clarified solution, and place it in a heating and stirring controller with a speed of 800 revolutions per minute and a set temperature of 50°C for 12 hours.

[0050] S3: Remove the reacted polytetrafluoroethylene liner and cool it to room temperature with water. Filter the milky white liquid obtained from the reaction in the liner and wash it with methanol more than 3 times. Then dry it at 80°C for more than 12 hours.

[0051] S4: Crush the dried block ZIF-8 into powder using a pulverizer, dry at 150°C for 3 hours, then add 10wt% guar gum powder (the remaining 90wt% is ZIF-8 powder) and 1wt% ZIF-8 powder in a 5wt% nitric acid solution, and grind and mix thoroughly in a mortar.

[0052] S5: Gradually add small amounts of deionized water as a gum arabic until ZIF-8 is kneaded into a dough; wherein, the amount of deionized water used is equal to the amount of ZIF-8 powder used in step S4;

[0053] S6: Press the ZIF-8 dough into a rectangular sheet about 5 mm thick, then use a spherical forming machine to form spheres, and dry at 180°C for 6 hours to obtain spherical ZIF-8 material with a diameter of 5 mm.

[0054] Example 3:

[0055] A method for scaled-up preparation and molding of ZIF-8 includes the following steps:

[0056] S1: Add 200mL of methanol solvent to a 250mL polytetrafluoroethylene liner, add the weighed 2-methylimidazole and zinc nitrate hexahydrate and 15g of sodium formate, and add a PTFE rotor of appropriate size. Stir on a magnetic stirrer until clear, wherein the zinc nitrate hexahydrate is 29.7g, the 2-methylimidazole is 16.4g, and the molar ratio is 0.5:1;

[0057] S2: Cover the polytetrafluoroethylene liner containing the rotor and the above-mentioned clarified solution, and place it in a heating and stirring controller with a speed of 1500 revolutions per minute and a set temperature of 100°C for 12 hours.

[0058] S3: Remove the reacted polytetrafluoroethylene liner and cool it to room temperature with water. Filter the milky white liquid obtained from the reaction in the liner and wash it with methanol more than 3 times. Then dry it at 80°C for more than 12 hours.

[0059] S4: Use a pulverizer to pulverize the dried block ZIF-8 into powder, dry it at 150℃ for 3 hours, and then add 10wt% guar gum powder (the remaining 90wt% is ZIF-8 powder) and 3wt% ZIF-8 powder in a 5wt% nitric acid solution. Grind and mix thoroughly in a mortar.

[0060] S5: Gradually add small amounts of deionized water as a gum arabic until ZIF-8 is kneaded into a dough; wherein, the amount of deionized water used is equal to the amount of ZIF-8 powder used in step S4;

[0061] S6: Press the ZIF-8 dough into a rectangular sheet about 5 mm thick, then use a spherical forming machine to form spheres, and dry at 180°C for 6 hours to obtain spherical ZIF-8 material with a diameter of 5 mm.

[0062] Example 4:

[0063] A method for scaled-up preparation and molding of ZIF-8 includes the following steps:

[0064] S1: Add 200mL of methanol solvent to a 250mL polytetrafluoroethylene liner, add the weighed 2-methylimidazole and zinc nitrate hexahydrate and 15g of sodium formate, and add a PTFE rotor of appropriate size. Stir on a magnetic stirrer until clear, wherein the zinc nitrate hexahydrate is 29.7g, the 2-methylimidazole is 16.4g, and the molar ratio is 0.5:1;

[0065] S2: Cover the polytetrafluoroethylene liner containing the rotor and the above-mentioned clarified solution, and place it in a heating and stirring controller with a speed of 1500 revolutions per minute and a set temperature of 100°C for 12 hours.

[0066] S3: Remove the reacted polytetrafluoroethylene liner and cool it to room temperature with water. Filter the milky white liquid obtained from the reaction in the liner and wash it with methanol more than 3 times. Then dry it at 80°C for more than 12 hours.

[0067] S4: Use a pulverizer to pulverize the dried block ZIF-8 into powder, dry it at 150℃ for 3 hours, and then add 10wt% methylcellulose binder, 10wt% guar gum powder (the remaining 80wt% is ZIF-8 powder), 2wt% ZIF-8 powder and deionized water, and grind and mix them thoroughly in a mortar.

[0068] S5: Gradually add small amounts of deionized water as a gum arabic until ZIF-8 is kneaded into a dough; wherein, the amount of deionized water used is equal to the amount of ZIF-8 powder used in step S4;

[0069] S6: Press the ZIF-8 dough into a rectangular sheet about 5 mm thick, then use a spherical forming machine to form spheres, and dry at 180°C for 6 hours to obtain spherical ZIF-8 material with a diameter of 5 mm.

[0070] Example 5:

[0071] A method for scaled-up preparation and molding of ZIF-8 includes the following steps:

[0072] S1: Add 200mL of methanol solvent to a 250mL polytetrafluoroethylene liner, add the weighed 2-methylimidazole and zinc nitrate hexahydrate and 15g of sodium formate, and add a PTFE rotor of appropriate size. Stir on a magnetic stirrer until clear, wherein the zinc nitrate hexahydrate is 29.7g, the 2-methylimidazole is 16.4g, and the molar ratio is 0.5:1;

[0073] S2: Cover the polytetrafluoroethylene liner containing the rotor and the above-mentioned clarified solution, and place it in a heating and stirring controller with a speed of 1500 revolutions per minute and a set temperature of 100°C for 12 hours.

[0074] S3: Remove the reacted polytetrafluoroethylene liner and cool it to room temperature with water. Filter the milky white liquid obtained from the reaction in the liner and wash it with methanol more than 3 times. Then dry it at 80°C for more than 12 hours.

[0075] S4: Use a pulverizer to pulverize the dried block ZIF-8 into powder, dry it at 150℃ for 3 hours, and then add 10wt% acidic clay, 10wt% guar gum powder (the remaining 80wt% is ZIF-8 powder), and 2wt% deionized water of ZIF-8 powder. Grind and mix them thoroughly in a mortar.

[0076] S5: Gradually add small amounts of deionized water as a gum arabic until ZIF-8 is kneaded into a dough; wherein, the amount of deionized water used is equal to the amount of ZIF-8 powder used in step S4;

[0077] S6: Press the ZIF-8 dough into a rectangular sheet about 5 mm thick, then use a spherical forming machine to form spheres, and dry at 180°C for 6 hours to obtain spherical ZIF-8 material with a diameter of 5 mm.

[0078] Example 6:

[0079] A method for scaled-up preparation and molding of ZIF-8 includes the following steps:

[0080] S1: Add 200mL of methanol solvent to a 250mL polytetrafluoroethylene liner, add the weighed 2-methylimidazole and zinc nitrate hexahydrate and 15g of sodium formate, and add a PTFE rotor of appropriate size. Stir on a magnetic stirrer until clear, wherein the zinc nitrate hexahydrate is 29.7g, the 2-methylimidazole is 16.4g, and the molar ratio is 0.5:1;

[0081] S2: Cover the polytetrafluoroethylene liner containing the rotor and the above-mentioned clarified solution, and place it in a heating and stirring controller with a speed of 1500 revolutions per minute and a set temperature of 100°C for 12 hours.

[0082] S3: Remove the reacted polytetrafluoroethylene liner and cool it to room temperature with water. Filter the milky white liquid obtained from the reaction in the liner and wash it with methanol more than 3 times. Then dry it at 80°C for more than 12 hours.

[0083] S4: Use a pulverizer to pulverize the dried block ZIF-8 into powder, dry it at 150℃ for 3 hours, and then add 1wt% acidic clay, 1wt% guar gum powder (the remaining 98wt% is ZIF-8 powder), and 1wt% deionized water of ZIF-8 powder. Grind and mix thoroughly in a mortar.

[0084] S5: Gradually add small amounts of deionized water as a gum arabic until ZIF-8 is kneaded into a dough; wherein, the amount of deionized water used is equal to the amount of ZIF-8 powder used in step S4;

[0085] S6: Press the ZIF-8 dough into a rectangular sheet about 5 mm thick, then use a spherical forming machine to form spheres, and dry at 180°C for 6 hours to obtain spherical ZIF-8 material with a diameter of 5 mm.

[0086] Example 7:

[0087] A method for scaled-up preparation and molding of ZIF-8 includes the following steps:

[0088] S1: Add 200mL of methanol solvent to a 250mL polytetrafluoroethylene liner, add the weighed 2-methylimidazole and zinc nitrate hexahydrate and 25g of sodium formate, and add a PTFE rotor of appropriate size. Stir on a magnetic stirrer until clear. The molar ratio of zinc nitrate hexahydrate to 24g and 2-methylimidazole to 6.6g is 1:1; or, the molar ratio of zinc nitrate hexahydrate to 24g and 2-methylimidazole to 6.6g is 2:1; or, the molar ratio of zinc nitrate hexahydrate to 48g and 2-methylimidazole to 6.6g is 4:1.

[0089] S2: Cover the polytetrafluoroethylene liner containing the rotor and the above-mentioned clarified solution, and place it in a heating and stirring controller with a rotation speed of 0 revolutions per minute and a set temperature of 150°C for 24 hours.

[0090] S3: Remove the reacted polytetrafluoroethylene liner and cool it to room temperature with water. Filter the milky white liquid obtained from the reaction in the liner and wash it with methanol more than 3 times. Then dry it at 80°C for more than 12 hours.

[0091] S4: Use a pulverizer to pulverize the dried block ZIF-8 into powder, dry it at 150℃ for 3 hours, and then grind and mix it thoroughly in a mortar.

[0092] S5: Gradually add small amounts of deionized water as a gum arabic until ZIF-8 is kneaded into a dough; wherein, the amount of deionized water used is equal to the amount of ZIF-8 powder used in step S4;

[0093] S6: Press the ZIF-8 dough into a rectangular sheet about 5mm thick, then pelletize it using a pelletizing machine and dry it at 180°C for 6 hours.

[0094] Example 8:

[0095] A method for scaled-up preparation and molding of ZIF-8 includes the following steps:

[0096] S1: Add 200mL of methanol solvent to a 250mL polytetrafluoroethylene liner, add the weighed 2-methylimidazole and zinc nitrate hexahydrate and 25g of sodium formate, and add a PTFE rotor of appropriate size. Stir on a magnetic stirrer until clear. The mixture contains 24g of zinc nitrate hexahydrate and 6.6g of 2-methylimidazole, with a molar ratio of 2:1.

[0097] S2: Cover the polytetrafluoroethylene liner containing the rotor and the above-mentioned clarified solution, and place it in a heating and stirring controller with a speed of 800 revolutions per minute and a set temperature of 150°C for 24 hours.

[0098] S3: Remove the reacted polytetrafluoroethylene liner and cool it to room temperature with water. Filter the milky white liquid obtained from the reaction in the liner and wash it with methanol more than 3 times. Then dry it at 80°C for more than 12 hours.

[0099] S4: Crush the dried block ZIF-8 into powder using a pulverizer, dry at 150°C for 3 hours, then add 2wt% of a 5wt% nitric acid solution (the remaining 98wt% is ZIF-8 powder), and grind and mix thoroughly in a mortar.

[0100] S5: Gradually add small amounts of deionized water as a gum arabic until ZIF-8 is kneaded into a dough; wherein, the amount of deionized water used is equal to the amount of ZIF-8 powder used in step S4;

[0101] S6: Press the ZIF-8 dough into a rectangular sheet about 5mm thick, then pelletize it using a pelletizing machine and dry it at 180°C for 6 hours.

[0102] Example 9:

[0103] A method for scaled-up preparation and molding of ZIF-8 includes the following steps:

[0104] S1: Add 200mL of methanol solvent to a 250mL polytetrafluoroethylene liner, add the weighed 2-methylimidazole and zinc nitrate hexahydrate and 25g of sodium formate, and add a PTFE rotor of appropriate size. Stir on a magnetic stirrer until clear. The mixture contains 24g of zinc nitrate hexahydrate and 6.6g of 2-methylimidazole, with a molar ratio of 2:1.

[0105] S2: Cover the polytetrafluoroethylene liner containing the rotor and the above-mentioned clarified solution, and place it in a heating and stirring controller with a speed of 800 revolutions per minute and a set temperature of 150°C for 24 hours.

[0106] S3: Remove the reacted polytetrafluoroethylene liner and cool it to room temperature with water. Filter the milky white liquid obtained from the reaction in the liner and wash it with methanol more than 3 times. Then dry it at 80°C for more than 12 hours.

[0107] S4: Use a pulverizer to pulverize the dried block ZIF-8 into powder, dry it at 150℃ for 3 hours, then add 2wt% deionized water (the remaining 98wt% is ZIF-8 powder), and grind and mix it thoroughly in a mortar.

[0108] S5: Gradually add small amounts of deionized water as a gum arabic until ZIF-8 is kneaded into a dough; wherein, the amount of deionized water used is equal to the amount of ZIF-8 powder used in step S4;

[0109] S6: Press the ZIF-8 dough into a rectangular sheet about 5mm thick, then pelletize it using a pelletizing machine and dry it at 180°C for 6 hours.

[0110] Example 10

[0111] A method for scaled-up preparation and molding of ZIF-8 includes the following steps:

[0112] S1: Add 200mL of methanol solvent to a 250mL polytetrafluoroethylene liner, add the weighed 2-methylimidazole and zinc nitrate hexahydrate and 25g of sodium formate, and add a PTFE rotor of appropriate size. Stir on a magnetic stirrer until clear. The mixture contains 24g of zinc nitrate hexahydrate and 6.6g of 2-methylimidazole, with a molar ratio of 2:1.

[0113] S2: Cover the polytetrafluoroethylene liner containing the rotor and the above-mentioned clarified solution, and place it in a heating and stirring controller with a speed of 800 revolutions per minute and a set temperature of 150°C for 24 hours.

[0114] S3: Remove the reacted polytetrafluoroethylene liner and cool it to room temperature with water. Filter the milky white liquid obtained from the reaction in the liner and wash it with methanol more than 3 times. Then dry it at 80°C for more than 12 hours.

[0115] S4: Use a pulverizer to pulverize the dried block ZIF-8 into powder, dry it at 150℃ for 3 hours, and then add 10wt% guar gum powder as binder (the remaining 90wt% is ZIF-8 powder), 2wt% ZIF-8 powder and a 5wt% nitric acid solution, and grind and mix them thoroughly in a mortar.

[0116] S5: Gradually add small amounts of deionized water as a gum arabic until ZIF-8 is kneaded into a dough; wherein, the amount of deionized water used is equal to the amount of ZIF-8 powder used in step S4;

[0117] S6: Press the ZIF-8 dough into a rectangular sheet about 5 mm thick, then use a spherical forming machine to form spheres, and dry at 180°C for 6 hours to obtain spherical ZIF-8 material with a diameter of 5 mm.

[0118] Example 11

[0119] A method for scaled-up preparation and molding of ZIF-8 includes the following steps:

[0120] S1: Add 200mL of methanol solvent to a 250mL polytetrafluoroethylene liner, add the weighed 2-methylimidazole and zinc nitrate hexahydrate and 25g of sodium formate, and add a PTFE rotor of appropriate size. Stir on a magnetic stirrer until clear. The mixture contains 24g of zinc nitrate hexahydrate and 6.6g of 2-methylimidazole, with a molar ratio of 2:1.

[0121] S2: Cover the polytetrafluoroethylene liner containing the rotor and the above-mentioned clarified solution, and place it in a heating and stirring controller with a speed of 800 revolutions per minute and a set temperature of 150°C for 24 hours.

[0122] S3: Remove the reacted polytetrafluoroethylene liner and cool it to room temperature with water. Filter the milky white liquid obtained from the reaction in the liner and wash it with methanol more than 3 times. Then dry it at 80°C for more than 12 hours.

[0123] S4: Use a pulverizer to pulverize the dried block ZIF-8 into powder, dry it at 150℃ for 3 hours, and then add 10wt% guar gum powder (the remaining 90wt% is ZIF-8 powder) and 2wt% ZIF-8 powder in deionized water, and grind and mix them thoroughly in a mortar.

[0124] S5: Gradually add small amounts of deionized water as a gum arabic until ZIF-8 is kneaded into a dough; wherein, the amount of deionized water used is equal to the amount of ZIF-8 powder used in step S4;

[0125] S6: Press the ZIF-8 dough into a rectangular sheet about 5 mm thick, then use a spherical forming machine to form spheres, and dry at 180°C for 6 hours to obtain spherical ZIF-8 material with a diameter of 5 mm.

[0126] Example 12

[0127] A method for scaled-up preparation and molding of ZIF-8 includes the following steps:

[0128] S1: Add 200mL of methanol solvent to a 250mL polytetrafluoroethylene liner, add the weighed 2-methylimidazole and zinc nitrate hexahydrate and 25g of sodium formate, and add a PTFE rotor of appropriate size. Stir on a magnetic stirrer until clear. The mixture contains 24g of zinc nitrate hexahydrate and 6.6g of 2-methylimidazole, with a molar ratio of 2:1.

[0129] S2: Cover the polytetrafluoroethylene liner containing the rotor and the above-mentioned clarified solution, and place it in a heating and stirring controller with a speed of 800 revolutions per minute and a set temperature of 150°C for 24 hours.

[0130] S3: Remove the reacted polytetrafluoroethylene liner and cool it to room temperature with water. Filter the milky white liquid obtained from the reaction in the liner and wash it with methanol more than 3 times. Then dry it at 80°C for more than 12 hours.

[0131] S4: Use a pulverizer to pulverize the dried block ZIF-8 into powder, dry it at 150℃ for 3 hours, and then add 10wt% methylcellulose binder, 10wt% guar gum powder (the remaining 80wt% is ZIF-8 powder), 2wt% ZIF-8 powder and deionized water, and grind and mix them thoroughly in a mortar.

[0132] S5: Gradually add small amounts of deionized water as a gum arabic until ZIF-8 is kneaded into a dough; wherein, the amount of deionized water used is equal to the amount of ZIF-8 powder used in step S4;

[0133] S6: Press the ZIF-8 dough into a rectangular sheet about 5 mm thick, then use a spherical forming machine to form spheres, and dry at 180°C for 6 hours to obtain spherical ZIF-8 material with a diameter of 5 mm.

[0134] Example 13

[0135] A method for scaled-up preparation and molding of ZIF-8 includes the following steps:

[0136] S1: Add 200mL of methanol solvent to a 250mL polytetrafluoroethylene liner, add the weighed 2-methylimidazole and zinc nitrate hexahydrate and 25g of sodium formate, and add a PTFE rotor of appropriate size. Stir on a magnetic stirrer until clear. The mixture contains 24g of zinc nitrate hexahydrate and 6.6g of 2-methylimidazole, with a molar ratio of 2:1.

[0137] S2: Cover the polytetrafluoroethylene liner containing the rotor and the above-mentioned clarified solution, and place it in a heating and stirring controller with a speed of 800 revolutions per minute and a set temperature of 150°C for 24 hours.

[0138] S3: Remove the reacted polytetrafluoroethylene liner and cool it to room temperature with water. Filter the milky white liquid obtained from the reaction in the liner and wash it with methanol more than 3 times. Then dry it at 80°C for more than 12 hours.

[0139] S4: Use a pulverizer to pulverize the dried block ZIF-8 into powder, dry it at 150℃ for 3 hours, and then add 1wt% acidic clay, 1wt% guar gum powder (the remaining 98wt% is ZIF-8 powder), and 1wt% deionized water of ZIF-8 powder. Grind and mix thoroughly in a mortar.

[0140] S5: Gradually add small amounts of deionized water as a gum arabic until ZIF-8 is kneaded into a dough; wherein, the amount of deionized water used is equal to the amount of ZIF-8 powder used in step S4;

[0141] S6: Press the ZIF-8 dough into a rectangular sheet about 5 mm thick, then use a spherical forming machine to form spheres, and dry at 180°C for 6 hours to obtain spherical ZIF-8 material with a diameter of 5 mm.

[0142] The properties of the ZIF-8 raw powder and molded products obtained from the above examples are shown in Appendix Table 1.

[0143] Table 1 Comparison of Adsorbent Preparation Effects

[0144]

[0145] Note: Raw materials in the table refer to 2-methylimidazole and zinc nitrate hexahydrate. "—" indicates that it was not implemented or that implementation was meaningless. Particle crushing strength was measured according to ASTM D 4179–01.

[0146] Table 2 compares the BET results of the ZIF-8 powder prepared in step S4 of Example 13 with the finally obtained spherical ZIF-8 material.

[0147]

[0148] Table 3 shows the static adsorption amount of the model compound n-alkane before and after molding in Example 13.

[0149]

[0150] Based on the results of the examples in Tables 1-3, the combination of guar gum powder, acidic clay, and water is the optimal molding aid combination. Using this scheme, the pore structure and hexane adsorption performance of the model compound in the molded ZIF-8 material do not change significantly, remaining close to the level of the original powder. Furthermore, from... Figure 1 SEM analysis showed that the crystal particles of the sample remained intact after molding, and the morphology of the 5mm diameter particles was uniform and regular.

[0151] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method of forming ZIF-8, characterized by, The application relates to a preparation method of a spherical ZIF-8 material. The ZIF-8 powder is mixed with one of water and nitric acid and a binder, a rubber solution is added to knead into a ball, tabletting is carried out, balling is carried out, drying is carried out, and the spherical ZIF-8 material is obtained; The amount of the nitric acid or water is 1-3 wt% of the ZIF-8 powder heated product; The binder is selected from the group consisting of sesbania powder, methyl cellulose and acid clay; The mixture of the ZIF-8 powder and the binder comprises the following components and weight percentage: acid clay 1-10%, Sesbania powder 1-10%, ZIF-8 powder heated product 80-98%.

2. The method of claim 1, wherein the ZIF-8 is formed by, In the heating, the heating temperature is 120-180 DEG C, and the heating time is 2-5 h.

3. The method of claim 1, wherein the ZIF-8 is formed by, The rubber solution is water.

4. The method of claim 1, wherein the ZIF-8 is formed by, The average particle size of the spherical ZIF-8 material is 3-8 mm.

5. The method of claim 1, wherein the ZIF-8 is formed by, The preparation method of the ZIF-8 powder comprises the following steps: 2-methyl imidazole, zinc nitrate and sodium formate are mixed and a crystallization reaction is carried out, and then filtering, washing and drying are carried out.

6. The method of claim 5, wherein the ZIF-8 is formed by, The mass ratio of the 2-methyl imidazole, the zinc nitrate and the sodium formate is (5-50):(10-50):(10-25), wherein the zinc nitrate is calculated according to zinc nitrate hexahydrate.

7. The method of claim 5, wherein the ZIF-8 is formed by, In the crystallization reaction, the reaction temperature is 50-150 DEG C, and the reaction time is 6-24 h.

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