CN116948206B - Method for accurately regulating and controlling morphology of ZIF-8 material - Google Patents

Method for accurately regulating and controlling morphology of ZIF-8 material Download PDF

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CN116948206B
CN116948206B CN202311195048.8A CN202311195048A CN116948206B CN 116948206 B CN116948206 B CN 116948206B CN 202311195048 A CN202311195048 A CN 202311195048A CN 116948206 B CN116948206 B CN 116948206B
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zif
solution
particles
morphology
nitrate
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CN116948206A (en
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王琪
朱荣振
耿德敏
李秀萍
董雅鑫
李熠豪
冯齐云
魏玉玉
凌奇
魏强
袁翠然
刘建路
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Shandong Haihua Group Co Ltd
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Abstract

The invention provides a novel method for accurately regulating and controlling the morphology of a ZIF-8 material, and belongs to the technical field of material preparation. The size and uniformity of ZIF-8 particles are regulated by controlling the concentration and the addition sequence of polyvinylpyrrolidone solution and the stirring time, uniform ZIF-8 particles with the size of 1-3 mu m are used as precursors, and the ZIF-8 particles are subjected to post-synthesis modification by controlling the concentration and the reaction time of metal ion salt solutions with different elements, different valence states and different anions and the temperature, so that a flaky, spherical and rod-shaped ZIF-8 material is obtained, the structure of the ZIF-8 particles is basically reserved, and the method is a novel method for regulating the morphology of the ZIF-8 material. The preparation method disclosed by the invention is simple, the reaction condition is mild, no environmental pollution is caused, and compared with ZIF-8 particles, ZIF-8 materials with different morphologies obtained by the method have the characteristics of different specific surface areas, pore structures and acid-base active sites, and the preparation method has a wide industrial application prospect.

Description

Method for accurately regulating and controlling morphology of ZIF-8 material
Technical Field
The invention relates to a novel method for accurately regulating and controlling the morphology of a ZIF-8 material, and belongs to the technical field of material preparation.
Background
The Zeolitic Imidazolate Frameworks (ZIFs) are one of the metal organic framework Materials (MOFs) consisting of metal ions or oxides and organic ligands. ZIF-8 is the most representative ZIFs material, has the characteristics of special topological structure, excellent thermal stability and chemical stability, high specific surface area, abundant active sites, adjustable pore structure and the like, and has wide application prospect in the fields of heterogeneous catalysis, gas adsorption separation and the like. ZIF-8 materials with different morphologies may have more unique surface properties or structures, which affect the catalytic or adsorptive properties. Therefore, the precise regulation and control of the morphology of the ZIF-8 material attracts attention of researchers.
For the morphology adjustment of ZIF-8 materials, most of the preparation methods are limited to inhibiting the crystal plane growth of the ZIF-8 materials by adding a surfactant or an organic ligand so as to generate ZIF-8 materials with different shapes; little adjustment of the morphology of ZIF-8 materials is achieved by introducing other metal cations, and most research steps are stopped by doping and calcining ZIF-8. Yang Feng et al disclose on Morphological map of ZIF-8 crystals with five distinctive shapes: feature of filler in mixed-matrix membranes on C3H6/C3H8 separation (Chemistry of Materials, 2018, 30 (10): 3467-3473) that ZIF-8 of different shapes such as cake, rod, cluster and the like can be synthesized by controlling the concentration of cetyltrimethylammonium bromide (CTAB), but the problem is that the shape is only regulated, the pore canal of ZIF-8 and the acid-base active site have no effect, and the application is limited.
The Chinese patent document with publication number of CN113402719A discloses a novel ZIF-8 material, and a preparation method and application thereof. According to the method, the aqueous solution of various metal cations and the 2-methylimidazole aqueous solution are directly reacted by a one-step method to obtain ZIF-8 with different morphologies and different structures, and although the morphologies are changed and mesopores are generated, the structure of the ZIF-8 is destroyed, the pore diameter is not more than 10nm, and the catalytic application of the ZIF-8 is seriously affected.
The Chinese patent document with publication number of CN110394159A discloses a method for preparing an ion exchange ZIF-8 adsorbent by a one-step method and application thereof. According to the method, zinc nitrate, 2-methylimidazole, polyvinylpyrrolidone and lithium nitrate solution are mixed and then subjected to high-temperature conditions to prepare the ZIF-8-containing ion exchange adsorbent, the morphology of the ZIF-8 is not regulated, only the surface ion exchange of the ZIF-8 is realized, the carbon dioxide adsorption capacity is improved, and the influence of pore diameters and acid-base active sites is not further explored.
The Chinese patent document with publication number of CN112371189A discloses a preparation method and catalytic application of a hydroxide-coated ZIF series MOFs heterogeneous catalyst. The method adopts cobalt nitrate, nickel nitrate and ferrous sulfate to synthesize ZIF-8, ZIF-7 and ZIF-67 and modify to form hydroxide-coated MOFs, thereby improving CO conversion 2 To thereby improve the adsorption capacity with respect to CO 2 Catalytic efficiency. In the method, although an ion exchange mode of post-synthesis modification is adopted, hydroxide is formed on the surface of the ZIF-8, belongs to one of core-shell structures, the morphology of the ZIF-8 cannot be regulated and controlled to be flaky and other morphologies, and the influences of pore diameters and acid-base active sites are not explored.
Disclosure of Invention
The invention aims to solve the technical problems of providing a novel method for accurately regulating and controlling the morphology of a ZIF-8 material, and aims to solve the problem that the method for regulating and controlling the morphology of the ZIF-8 material by adding an organic ligand or a surfactant is single, and the synthesized ZIF-8 material is added into a strong acid metal ion salt solution for post-synthesis modification.
The invention provides a novel method for accurately regulating and controlling the morphology of ZIF-8 material, which comprises the following steps:
(1) Respectively dissolving zinc salt, polyvinylpyrrolidone and 2-methylimidazole in a solvent to prepare zinc salt solution, polyvinylpyrrolidone solution and 2-methylimidazole solution, and then carrying out mixing, stirring and heating reaction to obtain ZIF-8-containing solution;
(2) Centrifuging the ZIF-8-containing solution to obtain a first solid, washing the first solid, and drying to obtain ZIF-8 particles;
(3) Adding ZIF-8 particles into methanol solution containing strong acid metal ion salt, uniformly mixing, heating for reaction, centrifuging the reaction solution after the reaction is completed to obtain a second solid, washing the second solid, and drying to obtain a flaky, spherical or rod-shaped ZIF-8 material;
in the step (1), the zinc salt is one of zinc nitrate, zinc acetate and zinc chloride; the solvent is one or a mixture of more than two of water, methanol and ethanol in any mass ratio; the mixing sequence is that zinc salt solution and polyvinylpyrrolidone solution are mixed uniformly and then added with 2-methylimidazole solution.
In the step (1), the proportion of the dosage of zinc salt, 2-methylimidazole and polyvinylpyrrolidone to the total volume of zinc salt solution, polyvinylpyrrolidone solution and 2-methylimidazole solution is as follows:
0.75mmol：3-6mmo：0.075-1.5mmol:20-40ml。
in the step (1), stirring is carried out for 10-50s after mixing; the heating reaction temperature is 20-40 ℃ and the reaction time is 20-30h.
In the step (2), the washing is ethanol or methanol washing; the drying temperature is 60-120 ℃, and the drying time is 1-24h.
In the step (3), the molar ratio of the strong acid metal ion salt, ZIF-8 and methanol is 1-10:1:1200-2500.
The strong acid metal ion salt is one of nitrate, chloride and sulfate.
The nitrate is one of copper nitrate, nickel nitrate, silver nitrate and chromium nitrate; the chloride salt is one of copper chloride, nickel chloride, ferrous chloride and ferric chloride; the sulfate is one of copper sulfate and ferrous sulfate.
In the step (3), the heating reaction temperature is 50-85 ℃; the reaction time is 0.5-5h; the washing is ethanol or methanol washing; the drying temperature is 60-120 ℃, and the drying time is 1-24h.
The invention has the beneficial effects that:
(1) The novel method for accurately regulating and controlling the morphology of the ZIF-8 material does not need to be subjected to high-temperature and high-pressure conditions, and the preparation method is simple, mild in reaction condition and free of environmental pollution.
(2) The method of the invention can adjust the size and uniformity of ZIF-8 particles by controlling the concentration, the adding sequence and the stirring time of polyvinylpyrrolidone, the size of the ZIF-8 particles is between 1 mu m and 3 mu m, and the ZIF-8 particles are synthesized and then modified with metal ion salt solutions containing different elements, different valence states and different anions, thus preparing ZIF-8 materials with different morphologies, wherein the ZIF-8 materials have sheet morphology and comprise Cu (NO 3 ) 2 /ZIF-8、CuCl 2 /ZIF-8、CuSO 4 /ZIF-8、FeSO 4 /ZIF-8、Cr(NO 3 ) 3 ZIF-8; the spherical morphology comprises NiCl 2 /ZIF-8、FeCl 3 /ZIF-8、Ni(NO 3 ) 2 ZIF-8; the rod-like morphology comprises AgNO 3 /ZIF-8、FeCl 2 /ZIF-8。
(3) The ZIF-8 material with different morphologies prepared by the method of the invention and ZIF-8 particles are prepared by XRD and N 2 -BET、NH 3 -TPD、CO 2 The comparison of the TPD characterization means shows that the ZIF-8 materials with different morphologies basically retain the structure of ZIF-8 particles, the ZIF-8 materials with different morphologies have different specific surface areas, pore structures and acid-base characteristics, and the specific surface areas and the alkaline site contents (CO 2 TPD) is reduced, the acid site content (NH) 3 TPD) and pore size range are both increasing. Therefore, the method has wide industrial application prospect in the fields of catalysis, adsorption, separation and the like.
Drawings
FIG. 1 is a ZIF-8 particle Scanning Electron Microscope (SEM) image of step (2) of example 1;
FIG. 2 shows the sheet Cu (NO) of step (3) in example 1 3 ) 2 SEM image of ZIF-8 material;
FIG. 3 is a SEM image of ZIF-8 particles of step (2) of example 2;
FIG. 4 shows the spherical Ni (NO) of step (3) in example 2 3 ) 2 SEM image of ZIF-8 material;
FIG. 5 is a SEM image of ZIF-8 particles of step (2) of example 3;
FIG. 6 is a diagram ofThe sheet-like Cr (NO) of step (3) in example 3 3 ) 3 SEM image of ZIF-8 material;
FIG. 7 is a SEM image of ZIF-8 particles of step (2) of example 4;
FIG. 8 shows the rod-like AgNO of step (3) of example 4 3 SEM image of ZIF-8 material;
FIG. 9 is a sheet-like CuCl of step (3) in example 5 2 SEM image of ZIF-8 material;
FIG. 10 is a spherical NiCl of step (3) in example 6 2 SEM image of ZIF-8 material;
FIG. 11 shows the rod-like FeCl of step (3) in example 7 2 SEM image of ZIF-8 material;
FIG. 12 is a spherical FeCl of step (3) in example 8 3 SEM image of ZIF-8 material;
FIG. 13 is a sheet-like CuSO of step (3) of example 9 4 SEM image of ZIF-8 material;
FIG. 14 shows the sheet FeSO of step (3) of example 10 4 SEM image of ZIF-8 material;
FIG. 15 is an X-ray diffraction (XRD) pattern of examples 1-10 and comparative example 2;
FIG. 16 is an SEM image of comparative example 1 of ZIF-8 particles without polyvinylpyrrolidone added thereto and copper nitrate in methanol after reaction;
FIG. 17 is an SEM image of the Cu/ZIF-8 material of step (2) of comparative example 2;
FIG. 18 is an SEM image of ZIF-8 particles of comparative example 3;
FIG. 19 is an SEM image of ZIF-8 particles of comparative example 4.
Detailed Description
The technical scheme of the invention is clearly and completely described below by examples. Those skilled in the art will appreciate that the embodiments described below are some, but not all, embodiments of the present invention and are intended to be illustrative of the present invention only and should not be construed as limiting the scope of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
(1) 0.75mmol of zinc nitrate hexahydrate, 3mmol of 2-methylimidazole and 0.3mmol of polyvinylpyrrolidone are respectively dissolved in 10ml of methanol to prepare zinc nitrate solution, 2-methylimidazole solution and polyvinylpyrrolidone solution, the zinc nitrate solution and the polyvinylpyrrolidone solution are uniformly stirred and mixed, then the 2-methylimidazole solution is added, stirring is carried out for 40s, and the reaction is carried out for 24h at 28 ℃ to obtain ZIF-8-containing solution.
(2) And centrifuging the solution containing ZIF-8 to obtain a first solid, washing the first solid with methanol for three times, and drying at 80 ℃ for 12 hours to obtain ZIF-8 particles.
(3) Preparing 0.3mmol of copper nitrate trihydrate into a copper nitrate solution by using 0.17mol of methanol, adding 0.1mmol of ZIF-8 particles into the copper nitrate solution, uniformly mixing the copper nitrate solution by ultrasonic for 3min, and reacting the copper nitrate solution at 65 ℃ for 3h to obtain Cu (NO) 3 ) 2 Centrifuging the mother liquor to obtain a second solid, washing the second solid with methanol for three times, and drying at 80deg.C for 5 hr to obtain sheet Cu (NO) 3 ) 2 ZIF-8 material.
The ZIF-8 particles and Cu (NO) flakes of example 1 were respectively treated 3 ) 2 The ZIF-8 material is subjected to Scanning Electron Microscope (SEM) morphology, X-ray diffraction (XRD) structural characterization and performance test, including nitrogen total adsorption (N) 2 -BET）、NH 3 Programmed temperature desorption (NH) 3 -TPD）、CO 2 Programmed temperature desorption (CO) 2 -TPD). FIG. 1 is an SEM image of ZIF-8 particles and FIG. 2 is a sheet-like Cu (NO) 3 ) 2 SEM pictures of ZIF-8 materials, FIG. 15 XRD patterns of examples 1-10 and comparative example 2, table 1 shows N 2 -BET、NH 3 -TPD、CO 2 Test results of TPD.
As can be seen from the comparison of FIG. 1 and FIG. 2, ZIF-8 particles are synthesized by copper nitrate solution and then subjected to modification reaction, and the morphology is changed from dodecahedron to flake; as can be seen from fig. 15, sheet Cu (NO 3 ) 2 The ZIF-8 material basically maintains the structure of ZIF-8 particles, and the method has mild reaction and is a novel method for adjusting the morphology of the ZIF-8 material. As can be seen from Table 1, ZIF-8 particles were post-synthesized with a copper nitrate solution,the specific surface area and pore size range and the acid-base active site are changed.
Example 2
(1) 2ml of deionized water and 18ml of absolute ethyl alcohol are prepared into 20ml of 90% ethyl alcohol, and then 0.75mmol of absolute zinc chloride is dissolved in 10ml of 90% ethyl alcohol to prepare zinc chloride solution; 0.075mmol of polyvinylpyrrolidone is dissolved in 5ml of 90% ethanol to prepare a polyvinylpyrrolidone solution, 3mmol of 2-methylimidazole is dissolved in 5ml of methanol to prepare a 2-methylimidazole solution, then the zinc chloride solution and the polyvinylpyrrolidone solution are stirred and mixed uniformly, then the 2-methylimidazole solution is added, the mixture is stirred for 50 seconds, and the mixture is reacted for 30 hours at 20 ℃ to obtain a ZIF-8-containing solution.
(2) And (3) centrifuging the solution containing ZIF-8 to obtain a first solid, washing the first solid with ethanol for three times, and drying at 60 ℃ for 24 hours after washing to obtain ZIF-8 particles.
(3) Preparing 0.1mmol of nickel nitrate hexahydrate into nickel nitrate solution by using 0.12mol of methanol, adding 0.1mmol of ZIF-8 particles into the nickel nitrate solution, uniformly mixing the nickel nitrate solution by ultrasonic for 3min, and reacting the nickel nitrate solution at 85 ℃ for 0.5h to obtain Ni (NO) 3 ) 2 Centrifuging the mother liquor of the ZIF-8 material to obtain a second solid, washing the second solid with ethanol for three times, and drying at 60deg.C for 24 hr to obtain spherical Ni (NO) 3 ) 2 ZIF-8 material.
ZIF-8 particles and spherical Ni (NO) of example 2 were respectively treated 3 ) 2 The ZIF-8 material is subjected to SEM, XRD characterization and N 2 -BET、NH 3 -TPD、CO 2 TPD performance test. FIG. 3 is an SEM image of ZIF-8 particles and FIG. 4 is a spherical Ni (NO) 3 ) 2 SEM pictures of ZIF-8 materials, FIG. 15 XRD patterns of examples 1-10 and comparative example 2, table 1 shows N 2 -BET、NH 3 -TPD、CO 2 Test results of TPD.
As can be seen from the comparison of FIG. 3 and FIG. 4, the ZIF-8 particles are synthesized by nickel nitrate solution and then modified, and the morphology is changed from dodecahedron to sphere; as can be seen from fig. 15, spherical Ni (NO 3 ) 2 The ZIF-8 material basically maintains the structure of the ZIF-8 particles and contains the main structure of the ZIF-8 particles. As can be seen from Table 1, ZIF-8 particles were treated with nickel nitrate solutionThe specific surface area and pore size range and the acid-base active site are changed.
Example 3
(1) 0.75mmol of zinc acetate dihydrate is dissolved in 20ml of water to prepare a zinc acetate solution, 6mmol of 2-methylimidazole and 1.5mmol of polyvinylpyrrolidone are respectively dissolved in 10ml of water to prepare a 2-methylimidazole solution and a polyvinylpyrrolidone solution, the zinc acetate solution and the polyvinylpyrrolidone solution are uniformly stirred and mixed, then the 2-methylimidazole solution is added, the stirring is carried out for 10 seconds, and the reaction is carried out for 20 hours at 40 ℃ to obtain a ZIF-8-containing solution.
(2) And (3) centrifuging the solution containing ZIF-8 to obtain a first solid, washing the first solid with ethanol for three times, and drying the washed first solid at 120 ℃ for 1h to obtain ZIF-8 particles.
(3) 1mmol of chromium nitrate nonahydrate is dissolved in 0.25mol of methanol to prepare a chromium nitrate solution, then 0.1mmol of ZIF-8 particles are added into the solution, the mixture is evenly mixed for 3 minutes by ultrasound, and the mixture is reacted for 5 hours at 50 ℃ to obtain Cr (NO) 3 ) 3 Centrifuging the mother liquor to obtain a second solid, washing the second solid with methanol for three times, and drying at 120deg.C for 1 hr to obtain sheet Cr (NO) 3 ) 3 ZIF-8 material.
The ZIF-8 particles and the flaky Cr (NO) in example 3 were respectively treated 3 ) 3 The ZIF-8 material is subjected to SEM, XRD characterization and N 2 -BET、NH 3 -TPD、CO 2 TPD performance test. FIG. 5 is an SEM image of ZIF-8 particles and FIG. 6 is a sheet-like Cr (NO) 3 ) 3 SEM pictures of ZIF-8 materials, FIG. 15 XRD patterns of examples 1-10 and comparative example 2, table 1 shows N 2 -BET、NH 3 -TPD、CO 2 Test results of TPD.
As can be seen from the comparison of FIG. 5 and FIG. 6, the ZIF-8 particles are modified after being synthesized by chromium nitrate solution, and the morphology is changed from dodecahedron to flake; as can be seen from FIG. 15, the sheet-like Cr (NO 3 ) 3 The ZIF-8 material basically maintains the structure of the ZIF-8 particles and contains the main structure of the ZIF-8 particles. As can be seen from Table 1, the ZIF-8 particles were modified after synthesis with nickel nitrate solution to change the specific surface area and pore size range and acid-base active sites.
Example 4
(1) Preparing 40ml of methanol-ethanol solution from 20ml of methanol and 20ml of absolute ethanol, dissolving 0.75mmol of zinc acetate dihydrate, 5.25mmol of 2-methylimidazole and 1.4mmol of polyvinylpyrrolidone in 10ml of methanol-ethanol mixed solution to prepare zinc acetate solution, polyvinylpyrrolidone solution and 2-methylimidazole solution, stirring the zinc acetate solution and the polyvinylpyrrolidone solution uniformly, adding the 2-methylimidazole solution, stirring for 10 seconds, and reacting for 23 hours at 25 ℃ to obtain a solution containing ZIF-8.
(2) And (3) centrifuging the solution containing ZIF-8 to obtain a first solid, washing the first solid with ethanol for three times, and drying the washed solution at 100 ℃ for 22 hours to obtain ZIF-8 particles.
(3) Dissolving 0.3mmol of silver nitrate in 0.15mol of methanol to prepare silver nitrate solution, adding 0.1mmol of ZIF-8 particles into the solution, uniformly mixing the solution by ultrasonic for 3min, and reacting the solution for 1h at 60 ℃ to obtain AgNO 3 Centrifuging the mother liquor to obtain a second solid, washing the second solid with ethanol for three times, and drying at 100deg.C for 22 hr to obtain rod-like AgNO 3 ZIF-8 material.
ZIF-8 particles and rod-like AgNO in example 4, respectively 3 The ZIF-8 material is subjected to SEM, XRD characterization and N 2 -BET、NH 3 -TPD、CO 2 TPD performance test. FIG. 7 is an SEM image of ZIF-8 particles and FIG. 8 is a rod-like AgNO 3 SEM pictures of ZIF-8 materials, FIG. 15 XRD patterns of examples 1-10 and comparative example 2, table 1 shows N 2 -BET、NH 3 -TPD、CO 2 Test results of TPD.
As can be seen from the comparison of FIG. 7 and FIG. 8, ZIF-8 particles are synthesized by silver nitrate solution and then modified, and the morphology is changed from dodecahedron to rod-shaped; as can be seen from FIG. 15, the rod-like AgNO 3 The ZIF-8 material substantially retains the structure of the ZIF-8 particles. As can be seen from Table 1, the ZIF-8 particles were modified after synthesis with silver nitrate solution to change the specific surface area and pore size range and acid-base active sites.
Example 5
(1) 0.75mmol of zinc nitrate hexahydrate is dissolved in 5ml of ethanol to prepare zinc nitrate solution; dissolving 4mmol of 2-methylimidazole and 0.3mmol of polyvinylpyrrolidone in 10ml of ethanol to prepare a 2-methylimidazole solution and a polyvinylpyrrolidone solution; and (3) uniformly stirring and mixing the zinc nitrate solution and the polyvinylpyrrolidone solution, then adding the 2-methylimidazole solution, stirring for 30s, and reacting at 30 ℃ for 24 hours to obtain a solution containing ZIF-8.
(2) And centrifuging the solution containing ZIF-8 to obtain a first solid, washing the first solid with methanol for three times, and drying at 100 ℃ for 3 hours to obtain ZIF-8 particles.
(3) Dissolving 0.2mmol of copper chloride dihydrate in 0.22mol of methanol to prepare a copper chloride solution, adding 0.1mmol of ZIF-8 particles into the copper chloride solution, uniformly mixing the copper chloride solution by ultrasonic for 3min, and reacting the copper chloride solution at 70 ℃ for 4h to obtain CuCl 2 Centrifuging the mother liquor to obtain a second solid, washing the second solid with methanol for three times, and drying at 110deg.C for 3 hr to obtain sheet CuCl 2 ZIF-8 material.
For the flaky CuCl in example 5 2 The ZIF-8 material is subjected to SEM, XRD characterization and N 2 -BET、NH 3 -TPD、CO 2 TPD performance test. FIG. 9 is a sheet-like CuCl 2 SEM pictures of ZIF-8 materials, FIG. 15 XRD patterns of examples 1-10 and comparative example 2, table 1 shows N 2 -BET、NH 3 -TPD、CO 2 Test results of TPD.
As can be seen from fig. 9, the morphology of the ZIF-8 particles is changed from dodecahedron to flake by the post-synthesis modification reaction of the copper chloride solution; as can be seen from FIG. 15, the sheet-like CuCl 2 The ZIF-8 material retains the structure of the ZIF-8 particles. As can be seen from Table 1, post-synthesis modification of ZIF-8 particles with copper chloride solution changed the specific surface area and pore size range as well as the acid-base active sites.
Example 6
(1) 0.75mmol of zinc nitrate hexahydrate is dissolved in 10ml of water to prepare zinc nitrate solution; dissolving 3mmol of 2-methylimidazole and 0.09mmol of polyvinylpyrrolidone in 10ml of methanol to prepare a 2-methylimidazole solution and a polyvinylpyrrolidone solution; and (3) uniformly stirring and mixing the zinc nitrate solution and the polyvinylpyrrolidone solution, then adding the 2-methylimidazole solution, stirring for 30s, and reacting at 38 ℃ for 22h to obtain a solution containing ZIF-8.
(2) And (3) centrifuging the solution containing ZIF-8 to obtain a first solid, washing the first solid with ethanol for three times, and drying at 60 ℃ for 2 hours after washing to obtain ZIF-8 particles.
(3) Dissolving 0.8mmol of nickel chloride in 0.2mol of methanol to prepare nickel chloride solution, adding 0.1mmol of ZIF-8 particles into the solution, uniformly mixing the solution by ultrasonic for 3min, and reacting the solution at 80 ℃ for 0.8h to obtain NiCl 2 Centrifuging the mother liquor to obtain a second solid, washing the second solid with methanol for three times, and drying at 100deg.C for 2 hr to obtain spherical NiCl 2 ZIF-8 material.
For example 6, spherical NiCl 2 The ZIF-8 material is subjected to SEM, XRD characterization and N 2 -BET、NH 3 -TPD、CO 2 TPD performance test. FIG. 10 is a spherical NiCl 2 SEM pictures of ZIF-8 materials, FIG. 15 XRD patterns of examples 1-10 and comparative example 2, table 1 shows N 2 -BET、NH 3 -TPD、CO 2 Test results of TPD.
As can be seen from fig. 10, the ZIF-8 particles were modified after being synthesized with a nickel chloride solution, and the morphology changed from dodecahedron to sphere; as can be seen from FIG. 15, spherical NiCl 2 The ZIF-8 material substantially retains the structure of the ZIF-8 particles. As can be seen from Table 1, the ZIF-8 particles were modified after synthesis with nickel chloride solution to change the specific surface area and pore size range and acid-base active sites.
Example 7
(1) Dissolving 0.75mmol of zinc nitrate hexahydrate, 3mmol of 2-methylimidazole and 0.3mmol of polyvinylpyrrolidone in 10ml of methanol respectively to prepare a zinc nitrate solution, a 2-methylimidazole solution and a polyvinylpyrrolidone solution, stirring and mixing the zinc nitrate solution and the polyvinylpyrrolidone solution uniformly, adding the 2-methylimidazole solution, stirring for 20s, and reacting at 28 ℃ for 22h to obtain a ZIF-8-containing solution.
(2) And centrifuging the solution containing ZIF-8 to obtain a first solid, washing the first solid with methanol for three times, and drying the washed solution at 90 ℃ for 10 hours to obtain ZIF-8 particles.
(3) Dissolving 0.3mmol of ferrous chloride in 0.15mol of methanol to prepare ferrous chloride solution, adding 0.1mmol of ZIF-8 particles into the solution, uniformly mixing the solution by ultrasonic for 3min, and reacting the solution for 4h at 60 ℃ to obtain FeCl 2 Centrifuging the mother liquor to obtain a second solid, washing the second solid with methanol for three times, and drying at 100deg.C for 12 hr to obtain rod-like FeCl 2 ZIF-8 material.
For the rod-like FeCl of example 7 2 The ZIF-8 material is subjected to SEM, XRD characterization and N 2 -BET、NH 3 -TPD、CO 2 TPD performance test. FIG. 11 is a bar-shaped FeCl 2 SEM pictures of ZIF-8 materials, FIG. 15 XRD patterns of examples 1-10 and comparative example 2, table 1 shows N 2 -BET、NH 3 -TPD、CO 2 Test results of TPD.
As can be seen from fig. 11, the ZIF-8 particles were modified after being synthesized with ferrous chloride solution, and the morphology changed from dodecahedron to rod-like; as can be seen from FIG. 15, the rod-like FeCl 2 The ZIF-8 material substantially retains the structure of the ZIF-8 particles. As can be seen from Table 1, the ZIF-8 particles were modified after synthesis with ferrous chloride solution to change the specific surface area and pore size range and acid-base active sites.
Example 8
(1) ZIF-8 particles were prepared in the same manner as in example 7.
(2) Dissolving 0.3mmol of ferric trichloride hexahydrate in 0.13mol of methanol to prepare ferric trichloride solution, adding 0.1mmol of ZIF-8 particles into the solution, carrying out ultrasonic mixing for 3min, and reacting at 60 ℃ for 2h to obtain spherical FeCl 3 Centrifuging the mother liquor to obtain a second solid, washing the second solid with methanol for three times, and drying at 100deg.C for 2 hr to obtain spherical FeCl 3 ZIF-8 material.
For example 8, spherical FeCl 3 The ZIF-8 material is subjected to SEM, XRD characterization and N 2 -BET、NH 3 -TPD、CO 2 TPD performance test. FIG. 12 is a spherical FeCl 3 SEM pictures of ZIF-8 materials, FIG. 15 XRD patterns of examples 1-10 and comparative example 2, table 1 shows N 2 -BET、NH 3 -TPD、CO 2 Test results of TPD.
As can be seen from fig. 12, the ZIF-8 particles were modified by synthesis with ferric trichloride solution, and the morphology changed from dodecahedron to sphere; as can be seen from FIG. 15, spherical FeCl 3 The ZIF-8 material substantially retains the structure of the ZIF-8 particles. As can be seen from Table 1, the ZIF-8 particles were modified after synthesis with ferric trichloride solution to change the specific surface area and pore size range and the acid-base active sites.
Example 9
(1) ZIF-8 particles were prepared in the same manner as in example 1.
(2) Dissolving 0.3mmol of anhydrous copper sulfate in 0.13mol of methanol to prepare a copper sulfate solution, adding 0.1mmol of ZIF-8 particles into the solution, uniformly mixing the solution by ultrasonic for 3min, and reacting the solution for 4.5h at 65 ℃ to obtain CuSO 4 Centrifuging the mother liquor to obtain a second solid, washing the second solid with methanol for three times, and drying at 80deg.C for 5 hr to obtain sheet CuSO 4 ZIF-8 material.
For the sheet-like CuSO obtained in example 9 4 The ZIF-8 material is subjected to SEM, XRD characterization and N 2 -BET、NH 3 -TPD、CO 2 TPD performance test. FIG. 13 is a sheet-like CuSO 4 SEM pictures of ZIF-8 materials, FIG. 15 XRD patterns of examples 1-10 and comparative example 2, table 1 shows N 2 -BET、NH 3 -TPD、CO 2 Test results of TPD.
As can be seen from fig. 13, the ZIF-8 particles were modified after being synthesized with a copper sulfate solution, and the morphology was changed from dodecahedron to flake; as can be seen from FIG. 15, the sheet-like CuSO 4 The ZIF-8 material substantially retains the structure of the ZIF-8 particles. As can be seen from Table 1, the ZIF-8 particles were modified after synthesis with a copper sulfate solution to change the specific surface area and pore size range and the acid-base active sites.
Example 10
(1) ZIF-8 particles were prepared in the same manner as in example 1.
(2) Dissolving 0.5mmol of ferrous sulfate heptahydrate in 0.13mol of methanol to prepare ferrous sulfate solution, adding 0.1mmol of ZIF-8 particles into the solution, mixing the solution uniformly by ultrasonic for 3min, and reacting at 65 DEG C4.5h to obtain FeSO 4 Centrifuging the mother liquor to obtain a second solid, washing the second solid with methanol for three times, and drying at 80deg.C for 5 hr to obtain sheet FeSO 4 ZIF-8 material.
For the sheet FeSO obtained in example 10 4 The ZIF-8 material is subjected to SEM, XRD characterization and N 2 -BET、NH 3 -TPD、CO 2 TPD performance test. FIG. 14 is a sheet FeSO 4 SEM pictures of ZIF-8 materials, FIG. 15 XRD patterns of examples 1-10 and comparative example 2, table 1 shows N 2 -BET、NH 3 -TPD、CO 2 Test results of TPD.
As can be seen from fig. 14, the ZIF-8 particles were modified after being synthesized with a ferrous sulfate solution, and the morphology was changed from dodecahedron to flake; as can be seen from FIG. 15, the sheet FeSO 4 The ZIF-8 material substantially retains the structure of the ZIF-8 particles. Table 1 shows that the ZIF-8 particles were modified after synthesis with ferrous sulfate solution to change the specific surface area and pore size range and acid-base active sites.
BET specific surface area and NLDFT model aperture range are defined by N 2 -BET test; NH (NH) 3 Adsorption quantity is formed by NH 3 -TPD test; CO 2 The adsorption quantity is formed by CO 2 TPD test.
As can be seen from Table 1, the ZIF-8 particles of examples 1-4 were sized with polyvinylpyrrolidone, and the effect of the specific surface area and pore size structure was small (negligible), the larger the particles, the smaller the specific surface area; examples 1-10 post-synthesis modification of ZIF-8 particles by metal ion salt solutions containing different elements, different valence states and different anions, we found specific surface area and alkaline content (CO 2 TPD) is reduced, but the acid content (NH) 3 TPD) and pore size are increasing, the pore size being in the range of 0.4-35nm.
Comparative example 1
(1) ZIF-8 particles were prepared in the same manner as in example 1 except that polyvinylpyrrolidone was not added, and SEM characterization tests were performed on the ZIF-8 particles, see FIG. 16 (1).
(2) Cu (NO) was prepared in the same manner as in example 1 3 ) 2 ZIF-8 material and is specific to Cu (NO 3 ) 2 The ZIF-8 material was subjected to SEM characterization test, see FIG. 16 (2).
As can be seen from FIG. 16, the ZIF-8 size was reduced and a film was formed on the surface of the ZIF-8 after the exchange, and the morphology adjustment similar to that of example 1 was not completed.
Comparative example 2
(1) 0.375mmol of zinc nitrate hexahydrate and 0.375mmol of copper nitrate trihydrate are respectively dissolved in 5ml of methanol to prepare a zinc nitrate solution and a copper nitrate solution; dissolving 3mmol of 2-methylimidazole and 0.3mmol of polyvinylpyrrolidone in 10ml of methanol respectively to prepare a 2-methylimidazole solution and a polyvinylpyrrolidone solution, stirring and mixing a zinc nitrate solution, a copper nitrate solution and the polyvinylpyrrolidone solution uniformly, adding the 2-methylimidazole solution, stirring for 40s, and reacting at 28 ℃ for 24 hours to obtain a mother solution of the Cu/ZIF-8 material.
(2) And (3) centrifuging the mother liquor of the Cu/ZIF-8 material to obtain a solid, washing the solid with methanol for three times, and drying at 80 ℃ for 5 hours to obtain the Cu/ZIF-8 material.
SEM and XRD characterization tests were performed on Cu/ZIF-8 materials, as shown in FIGS. 17 and 15, respectively.
As can be seen from FIG. 15, the structure of the ZIF-8 particles was not changed, and still had the ZIF-8 structure; as can be seen from fig. 17, the one-step synthesis process affects the morphology, but the morphology is mainly dodecahedron and is uneven, and this is because the coordination time of Cu and Zn with 2-methylimidazole is longer than that of Zn with 2-methylimidazole in the reaction process when other metal ions are added, and the prolongation of the reaction time can slow down the morphology unevenness, and the morphology is also affected by the addition of polyvinylpyrrolidone.
Comparative example 3
ZIF-8 particles were prepared in the same manner as in example 1 except that the polyvinyl pyrrolidone solution was added in the order of mixing the zinc nitrate solution and the 2-methylimidazole solution, and SEM characterization test was performed on the ZIF-8 particles, see FIG. 18.
During the experiment, the zinc nitrate solution and the 2-methylimidazole solution became a white emulsion immediately after mixing. As can be seen from the comparison of FIG. 18 with FIG. 1, the ZIF-8 particles of FIG. 18 were about 250nm in size and not uniform, and the ZIF-8 particles of FIG. 1 were 2 μm in size, so that the order of addition of the polyvinylpyrrolidone solution had an important effect on the morphology size and uniformity of the ZIF-8 particles.
Comparative example 4
ZIF-8 particles were prepared in the same manner as in example 1 except that the stirring time was 24 hours, the entire experiment was conducted while stirring, and SEM characterization tests were conducted on ZIF-8 particles, as shown in FIG. 19.
As can be seen from a comparison of FIG. 19 with FIG. 1, the ZIF-8 particles of FIG. 19 have a particle size of about 5 μm (non-uniform) and the ZIF-8 particles of FIG. 1 have a particle size of 2 μm (uniform), and thus stirring for a long period of time may destroy the morphology and uniformity of the ZIF-8 particles, requiring proper stirring.
As can be seen from examples 1-10 and comparative example 1, polyvinylpyrrolidone is the key for adjusting morphology, and the polyvinylpyrrolidone solution adjusts the size of the ZIF-8 material and helps to stabilize the structure of the ZIF-8 material during post-synthesis modification; it is known from examples 1-10 and comparative example 2 that under the same conditions, the preparation process of the one-step method can influence the morphology of ZIF-8, but the morphology is not regulated, the morphology is still mainly twelve-sided, and the morphology is uneven; from examples 1-10 and comparative example 3, it is clear that the order of addition of the polyvinylpyrrolidone solution has a significant effect on the morphology size and uniformity of the ZIF-8 particles; as can be seen from examples 1-10 and comparative example 4, the stirring time has an effect on the size and uniformity of the ZIF-8 particles.
The above-described embodiments are provided to illustrate the gist of the present invention, but are not intended to limit the scope of the present invention. It will be understood by those skilled in the art that various modifications and equivalent substitutions may be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention.

Claims (6)

1. The method for precisely regulating and controlling the morphology of the ZIF-8 material is characterized by comprising the following steps of:
(1) Respectively dissolving zinc salt, polyvinylpyrrolidone and 2-methylimidazole in a solvent to prepare zinc salt solution, polyvinylpyrrolidone solution and 2-methylimidazole solution, and then carrying out mixing, stirring and heating reaction to obtain ZIF-8-containing solution;
(2) Centrifuging the ZIF-8-containing solution to obtain a first solid, washing the first solid, and drying to obtain ZIF-8 particles;
(3) Adding ZIF-8 particles into methanol solution containing strong acid metal ion salt, uniformly mixing, heating for reaction, centrifuging the reaction solution after the reaction is completed to obtain a second solid, washing the second solid, and drying to obtain a flaky, spherical or rod-shaped ZIF-8 material;
in the step (1), the zinc salt is one of zinc nitrate, zinc acetate and zinc chloride; the solvent is one or a mixture of more than two of water, methanol and ethanol in any mass ratio; the mixing sequence is that zinc salt solution and polyvinylpyrrolidone solution are mixed uniformly and then added with 2-methylimidazole solution;
in the step (1), stirring is carried out for 10-50s after mixing; heating to react at 20-40 deg.c for 20-30 hr;
in the step (3), the molar ratio of the strong acid metal ion salt, ZIF-8 and methanol is 1-10:1:1200-2500; the heating reaction temperature is 50-85 ℃; the reaction time is 0.5-5h.
2. The method for precisely regulating and controlling the morphology of the ZIF-8 material according to claim 1, which is characterized in that: in the step (1), the proportion of the dosage of zinc salt, 2-methylimidazole and polyvinylpyrrolidone to the total volume of zinc salt solution, polyvinylpyrrolidone solution and 2-methylimidazole solution is as follows: 0.75mmol:3-6mmol:0.075-1.5 mmol/20-40 ml.
3. The method for precisely regulating and controlling the morphology of the ZIF-8 material according to claim 1, which is characterized in that: in the step (2), the washing is ethanol or methanol washing; the drying temperature is 60-120 ℃, and the drying time is 1-24h.
4. The method for precisely regulating and controlling the morphology of the ZIF-8 material according to claim 1, which is characterized in that: the strong acid metal ion salt is one of nitrate, chloride and sulfate.
5. The method for precisely controlling the morphology of the ZIF-8 material according to claim 4, wherein the nitrate is one of copper nitrate, nickel nitrate, silver nitrate and chromium nitrate; the chloride salt is one of copper chloride, nickel chloride, ferrous chloride and ferric chloride; the sulfate is one of copper sulfate and ferrous sulfate.
6. The method for precisely controlling the morphology of the ZIF-8 material according to claim 1, wherein in the step (3), the washing is ethanol or methanol washing; the drying temperature is 60-120 ℃, and the drying time is 1-24h.
CN202311195048.8A 2023-09-16 2023-09-16 Method for accurately regulating and controlling morphology of ZIF-8 material Active CN116948206B (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020006328A (en) * 2018-07-10 2020-01-16 住友ベークライト株式会社 Composite particle, method for producing composite particle, adsorbent, and liquid purification method
CN114498068A (en) * 2022-02-18 2022-05-13 江西虔悦新材料有限公司 MOFs derived carbon-coated ferrite wave-absorbing material and preparation method and application thereof
CN115636950A (en) * 2022-12-26 2023-01-24 山东海化集团有限公司 Preparation method and application of ZIF-8 hierarchical pore material

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020006328A (en) * 2018-07-10 2020-01-16 住友ベークライト株式会社 Composite particle, method for producing composite particle, adsorbent, and liquid purification method
CN114498068A (en) * 2022-02-18 2022-05-13 江西虔悦新材料有限公司 MOFs derived carbon-coated ferrite wave-absorbing material and preparation method and application thereof
CN115636950A (en) * 2022-12-26 2023-01-24 山东海化集团有限公司 Preparation method and application of ZIF-8 hierarchical pore material

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