Core-shell type ZIF-67 (at) mZrO2 composite material as well as preparation method and application thereof

Abstract

The invention provides a core-shell type ZIF-67 (at) mZrO2 composite material as well as a preparation method and application thereof, and the preparation method comprises the following steps: dissolving 2-methylimidazole and N, N-dimethylethylenediamine in water in sequence; dissolving cobalt salt in water, and adding the solution into the solution obtained in the previous step; centrifuging and drying the obtained product to obtain a ZIF-67 inner core; the preparation method comprises the following steps: dispersing a ZIF-67 core and hexadecyl trimethyl ammonium bromide into ethanol; zirconium n-butoxide is added; transferring the mixed solution into a polytetrafluoroethylene lining; and after sealing, placing in a drying oven for micro-hydrolysis, cooling, washing, drying and calcining at high temperature. The preparation process of the catalyst is greatly simplified, the morphology, structure and size of the catalyst are modified, and the high-activity ZIF-67-coated mZrO2 achieves the catalytic hydrogenation conversion effect of lignite related model compounds and Xinjiang quasi-south lignite extraction residues.

Description

Technical Field

[0001] This invention relates to the field of core-shell composite catalyst technology, and more specifically, to a core-shell ZIF-67@mZrO2 composite material, its preparation method, and its application. Background Technology

[0002] Lignite is a low-rank coal resource rich in aromatic and heteroatom units, possessing a complex, high-density three-dimensional network structure. The unit segments are connected by various >CC< and >CX (X = O-, N<, and S-) bridging bonds, along with a small number of free nested groups. Therefore, based on these characteristics, highly active catalysts can be designed and used for the catalytic hydrogenation conversion of lignite to obtain high-value derivatives with different compositions and structural features.

[0003] In existing technologies, the catalysts used in lignite catalytic hydroconversion processes are mostly bimetallic oxides, including SiO2-Al2O3 complexes, Fe / Al complexes, and molecular sieves. These catalysts exhibit good process stability and sufficient acid-base active sites. However, since their high reactivity is related to their unique pore size distribution, to ensure a high yield of lignite-derived solubles, it is necessary to increase the specific surface area of ​​the catalyst to expose more active sites, which significantly increases the cost of the catalyst.

[0004] ZIF-67@mZrO2 possesses high porosity and a large specific surface area, thus exposing more active sites and further promoting the cracking of >CO- bridging bonds in lignite. To achieve both heteroatom removal and inhibition of aromatic ring hydrogenation, precise control of the conversion of active hydrogen species is required. However, in regulating the reaction, especially at relatively high temperatures, existing catalysts often suffer from carbon deposition, sintering, easy loss of active components, low porosity, small specific surface area, complex preparation processes, long production cycles, poor reproducibility, and harsh reaction conditions, leading to problems such as large dosage and high process costs. There is an urgent need to develop a lignite-related model compound and a catalyst for the catalytic hydrogenation conversion of lignite to completely solve the problems of carbon deposition, sintering, easy loss of active components, complex preparation processes, long production cycles, poor reproducibility, and harsh reaction conditions. Summary of the Invention

[0005] To address the aforementioned shortcomings, this invention provides a core-shell ZIF-67@mZrO2 composite material, its preparation method, and its applications. This invention significantly simplifies the catalyst preparation process, modifies the morphology, structure, and size of the catalyst, and overcomes the deficiencies of traditional catalysts. The highly active ZIF-67@mZrO2 achieves the catalytic hydrogenation conversion effect of lignite-related model compounds and lignite extraction residue from Jungfraujoch, Xinjiang.

[0006] In a first aspect, the present invention provides a method for preparing a core-shell ZIF-67@mZrO2 composite material, comprising the following steps:

[0007] a. Preparation of the ZIF-67 core:

[0008] a1. Dissolve 2-methylimidazole and N,N-dimethylethylenediamine in water sequentially and stir until homogeneous;

[0009] a2. Dissolve the cobalt salt in water, then add it to the solution obtained in step a1, and stir until well mixed;

[0010] a3. Centrifuge and dry the obtained product to obtain the ZIF-67 core;

[0011] b. Coating with mZrO2 shell:

[0012] b1. Disperse the ZIF-67 core obtained in step a3 and hexadecyltrimethylammonium bromide in ethanol and mix thoroughly.

[0013] b2. Add zirconium n-butoxide to the mixed solution obtained in step b1;

[0014] b3. Transfer the mixed solution obtained in step b2 into a polytetrafluoroethylene liner, and then fit it into a polytetrafluoroethylene liner pre-filled with deionized water to form a combination of large and small liners.

[0015] b4. After sealing, place in an oven for micro-hydrolysis, cool to room temperature and remove, then wash repeatedly with deionized water and ethanol, dry, and calcine at high temperature to obtain core-shell ZIF-67@mZrO2 composite material.

[0016] Preferably, in step a1, the mass ratio of 2-methylimidazole to N,N-dimethylethylenediamine is (1-10):(0.5-6).

[0017] Preferably, in step a2, the cobalt salt is Co(NO3)2·6H2O; the mass ratio of cobalt salt to 2-methylimidazole is (1-9):(1-10).

[0018] Preferably, in step a3, the centrifugation rate is 1000-5000 rpm and the centrifugation time is 1-30 min.

[0019] Preferably, in step b1, the mass ratio of hexadecyltrimethylammonium bromide to ZIF-67 core is (0.5-1):(0.1-2); the ratio of the volume of ethanol added to the mass of ZIF-67 core added is mL:g = (10-80):(0.1-2).

[0020] Preferably, in step b2, the ratio of the added volume of zirconium n-butoxide to the added mass of ZIF-67 core is mL:g = (0.5-2):(0.1-2); the density of zirconium n-butoxide is 0.7-0.9 g / mL.

[0021] Preferably, in step b3, the ratio of the added volume of deionized water to the added mass of ZIF-67 core is mL:g = (150-250):(0.1-2).

[0022] Preferably, in step b4, the drying temperature is 80-150℃ and the drying time is 6-24h; the calcination temperature is 100-1000℃ and the calcination time is 1-6h.

[0023] Secondly, the present invention provides a core-shell ZIF-67@mZrO2 composite material obtained by the preparation method described above.

[0024] Thirdly, the present invention provides the application of the core-shell ZIF-67@mZrO2 composite material as described above in the catalytic hydrogenation conversion reaction of lignite.

[0025] In summary, this invention provides a core-shell ZIF-67@mZrO2 composite material, its preparation method, and its application. The beneficial effects of this invention are:

[0026] This invention discloses a method for preparing a core-shell ZIF-67@mZrO2 composite material. This method greatly simplifies the catalyst preparation process, modifies the morphology, structure, and size of the catalyst, and overcomes the defects of traditional catalysts such as carbon deposition, sintering, easy loss of active components, low porosity, small specific surface area, complex preparation process, long production cycle, poor repeatability, and harsh reaction conditions. The highly active ZIF-67@mZrO2 achieves the catalytic hydrogenation conversion effect of lignite-related model compounds and lignite extraction residue from Jungfrau in Xinjiang.

[0027] Furthermore, the ZIF-67@mZrO2 prepared by this method has a high degree of mZrO2 coating on the outer shell, a thin coating layer, and no obvious agglomeration.

[0028] Furthermore, the preparation process is simple, safe, has a short production cycle, good repeatability, and the obtained ZIF-67@mZrO2 has good stability.

[0029] Furthermore, ZIF-67@mZrO2 has high porosity and a large specific surface area, which exposes more active sites and further promotes the cracking of CO- bridging bonds in lignite.

[0030] Furthermore, when this catalyst was used in the catalytic hydrogenation conversion of lignite-related model compounds and lignite extract residue from Junggar Basin in Xinjiang, it exhibited excellent catalytic activity, effectively cracking CO- bridging bonds and significantly improving the yield of aromatics derived from Junggar Basin lignite in Xinjiang. Attached Figure Description

[0031] Figure 1 The X-ray diffraction patterns are those of ZIF-67@mZrO2 and ZIF-67 obtained in Example 1 of this invention.

[0032] Figure 2 This is a transmission electron microscope (TEM) image of ZIF-67@mZrO2 prepared in Example 1 of the present invention.

[0033] Figure 3 This is a scanning electron microscope image of ZIF-67@mZrO2 prepared in Example 1 of the present invention.

[0034] Figure 4 The image shows the X-ray photoelectron spectrum of ZIF-67@mZrO2 obtained in Example 1 of this invention.

[0035] Figure 5 This is a yield diagram of the derivatives obtained from the catalytic hydrogenation conversion of ZIF-67@mZrO2 prepared in Example 1 of this invention using lignite from Zhunnan, Xinjiang.

[0036] Figure 6 This is a distribution diagram of the light component core group of ZIF-67@mZrO2 prepared in Example 1 of the present invention for catalytic hydrogenation conversion of lignite in Zhunnan, Xinjiang. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Table 1 shows the weight ratios of each raw material component in Examples 1-4.

[0039]

[0040] Example 1

[0041] A method for preparing a core-shell ZIF-67@mZrO2 composite material includes the following steps:

[0042] Phase 1:

[0043] (1) Disperse 5g of 2-methylimidazole in 400ml of water and add 1g of N,N-dimethylethylenediamine.

[0044] (2) Dissolve 3g Co(NO3)2·6H2O in 200ml of water, add it to the solution obtained in (1), stir, centrifuge the product at 2000r / min for 1min, and dry at 90℃ to obtain ZIF-67 core.

[0045] Phase Two:

[0046] (3) Disperse 0.5g of ZIF-67 kernel in 20ml of ethanol.

[0047] (4) Disperse 0.6g of cetyltrimethylammonium bromide in the mixture.

[0048] (5) Disperse 2 ml (density 0.8 g / ml) of zirconium butoxide in the above mixture.

[0049] (6) Transfer the above-obtained mixed solution into a 50 mL polytetrafluoroethylene liner, and then insert it into a 200 mL polytetrafluoroethylene liner pre-filled with a certain amount of deionized water to form a combination of large and small liners.

[0050] (7) After installation, the product was placed in an 80℃ oven for 24 hours. After cooling to room temperature, it was taken out and washed with deionized water and ethanol six times in total. After drying, it was calcined at 300℃ to obtain the core-shell ZIF-67@mZrO2 composite material.

[0051] Figure 1 The X-ray diffraction patterns of ZIF-67@mZrO2 and ZIF-67 prepared in Example 1 are shown in the figures. It can be seen from the figures that the XRD pattern of ZIF-67 is consistent with previous reports. Since Zr(OH)4 is not a crystalline structure, no XRD diffraction peaks of ZrO2 will appear. After high-temperature calcination, the ZIF-67 structure collapses, and Zr(OH)4 decomposes into ZrO2. Therefore, the diffraction peaks of ZIF-67 disappear after high-temperature calcination, and the metal Co ligand is partially reduced to elemental Co, with the remainder existing in the form of CoO. Specifically, the diffraction peaks at 2θ = 30.4°, 35.3°, and 60.4° are close to the diffraction peaks of the (111), (200), and (311) crystal planes of ZrO2, while the diffraction peaks at 2θ = 44.3° and 51.6° are close to those of Co. 0The diffraction peaks of the Co(111) and Co(200) crystal planes in (JCPDS no.15-0806) are close in position, indicating that the active component Co is dispersed in the form of crystals on the derived carbon.

[0052] like Figure 2 As shown in the transmission electron microscope (TEM) image, ZIF-67 exhibits a regular hexahedral structure. After being coated with Zr(OH)4, a clear boundary appears between ZIF-67 and Zr(OH)4. After pyrolysis, the outer layer of ZIF-67@mZrO2 is coated with ZrO2 particles and still maintains a regular morphology, proving that ZIF-67@mZrO2 has a core-shell structure.

[0053] like Figure 3 As shown in the scanning electron microscope image, the elemental distribution of ZIF-67@mZrO2 can be seen. Since ZIF-67@mZrO2 is mainly composed of graphite carbon, C element dominates. Co element is uniformly dispersed on graphite carbon, and Zr element is mainly concentrated in the outer layer of Co. This indirectly proves that ZIF-67@mZrO2 has a core-shell structure.

[0054] Figure 4 The X-ray photoelectron spectroscopy (XPS) spectrum of ZIF-67@mZrO2 is shown in the figure. It can be seen that C, N, O, Co, and Zr are present in ZIF-67@mZrO2. The Co XPS spectrum of Co / CN@mZrO2 consists of oxide Co, metallic Co, and satellite peaks. The peak positions of oxide Co and satellite peaks are 781.25 eV and 796.18 eV, and 788.86 eV and 802.73 eV, respectively, while the binding energies near 778.12 eV and 793.85 eV belong to metallic Co. These results indicate that the pyrolysis of organic ligands during the ZIF-67 pyrolysis process can partially reduce oxide Co to metallic Co. The binding energies of Zr 3d in ZIF-67@mZrO2 near 182.63 eV and 184.87 eV belong to Zr. 4+ The results show that Zr(OH)4 is pyrolyzed into ZrO2 during the pyrolysis process.

[0055] In ZIF-67@mZrO2, the binding energies of 400.63 eV and 402.82 eV correspond to a significant increase in pyrrole N and quaternary N. Doping carbon materials with different types of N exhibits excellent performance in terms of both catalysts and catalyst supports. Different types of N species play a positive role in stabilizing metals in the catalyst, thereby enhancing the catalyst's activity.

[0056] Example 2

[0057] A method for preparing core-shell ZIF-67@mZrO2 includes the following steps:

[0058] Phase 1:

[0059] (1) Disperse 1g of 2-methylimidazole in 100ml of water and add 0.5g of N,N-dimethylethylenediamine.

[0060] (2) Dissolve 1g Co(NO3)2·6H2O in 100ml of water, add it to the solution obtained in (1), stir, centrifuge the product at 3000r / min for 30min, and dry at 50℃ to obtain ZIF-67 core.

[0061] Phase Two:

[0062] (3) Disperse 0.1g of ZIF-67 kernel in 10ml of ethanol.

[0063] (4) Disperse 0.5g of cetyltrimethylammonium bromide in the mixture.

[0064] (5) Disperse 1 ml (density 0.8 g / ml) of zirconium n-butoxide in the above mixture.

[0065] (6) Transfer the above-obtained mixed solution into a 50 mL polytetrafluoroethylene liner, and then insert it into a 200 mL polytetrafluoroethylene liner pre-filled with a certain amount of deionized water to form a combination of large and small liners.

[0066] (7) After installation, the product was placed in a 100℃ oven for 24 hours. After cooling to room temperature, it was taken out and washed with deionized water and ethanol six times in total. After drying, it was calcined at 400℃ to obtain the core-shell ZIF-67@mZrO2 composite material.

[0067] Example 3

[0068] A method for preparing core-shell ZIF-67@mZrO2 includes the following steps:

[0069] Phase 1:

[0070] (1) Disperse 10g of 2-methylimidazole in 600ml of water and add 6g of N,N-dimethylethylenediamine.

[0071] (2) Dissolve 9g Co(NO3)2·6H2O in 600ml of water, add it to the solution obtained in (1), stir, centrifuge the product at 3000r / min for 15min, and dry at 70℃ to obtain ZIF-67 core.

[0072] Phase Two:

[0073] (3) Disperse 2g of ZIF-67 kernel in 80ml of ethanol.

[0074] (4) Disperse 1g of hexadecyltrimethylammonium bromide in the mixture.

[0075] (5) Disperse 2 ml (density 0.8 g / ml) of zirconium butoxide in the above mixture.

[0076] (6) Transfer the above-obtained mixed solution into a 50 mL polytetrafluoroethylene liner, and then insert it into a 200 mL polytetrafluoroethylene liner pre-filled with a certain amount of deionized water to form a combination of large and small liners.

[0077] (7) After installation, the product was placed in an oven at 150°C for 24 hours. After cooling to room temperature, it was taken out and washed with deionized water and ethanol alternately eight times. After drying, it was calcined at 200°C to obtain the core-shell ZIF-67@mZrO2 composite material.

[0078] Example 4

[0079] A method for preparing core-shell ZIF-67@mZrO2 includes the following steps:

[0080] Phase 1:

[0081] (1) Disperse 7g of 2-methylimidazole in 500ml of water and add 3g of N,N-dimethylethylenediamine.

[0082] (2) Dissolve 8g Co(NO3)2·6H2O in 300ml of water, add it to the solution obtained in (1), stir, centrifuge the product at 2000r / min for 10min, and dry at 130℃ to obtain ZIF-67 core.

[0083] Phase Two:

[0084] (3) Disperse 1.5g of ZIF-67 kernel in 32ml of ethanol.

[0085] (4) Disperse 0.8g of cetyltrimethylammonium bromide in the mixture.

[0086] (5) Disperse 2 ml (density 0.8 g / ml) of zirconium butoxide in the above mixture.

[0087] (6) Transfer the resulting mixed solution into a 50 mL polytetrafluoroethylene liner, and then insert it into a 200 mL polytetrafluoroethylene liner pre-filled with a certain amount of deionized water to form a combination of large and small liners.

[0088] (7) After installation, the product was placed in a 100℃ oven for 10 hours. After cooling to room temperature, it was taken out and washed with deionized water and ethanol six times in total. After drying, it was calcined at 300℃ to obtain the core-shell ZIF-67@mZrO2 composite material.

[0089] The ZIF-67@mZrO2 prepared in Example 1 above was applied to lignite-related model compounds and the catalytic hydrogenation conversion process of lignite from Zhunnan, Xinjiang. This can be explained by comparing non-catalytic hydrogenation conversion with catalytic hydrogenation conversion.

[0090] The following examples illustrate the application of ZIF-67@mZrO2.

[0091] Application Example 1

[0092] In the non-catalytic hydrogenation conversion reaction of lignite in Zhunnan, Xinjiang, ZIF-67@mZrO2 was prepared in Example 1.

[0093] The specific application process is as follows:

[0094] (1) Place 20g of Xinjiang Jungnan lignite in a 1000mL high-pressure reactor and add 200mL of cyclohexane;

[0095] (2) Replace the air in the reactor with N2 and then introduce 1 MPa of H2. React at 300℃ for 4 hours. After the reaction is completed, cool to room temperature.

[0096] (3) The reaction mixture was completely extracted with cyclohexane to obtain cyclohexane-soluble matter, i.e. light components, and the light components were detected, analyzed and compared.

[0097] (4) Then, extraction was continued with an equal volume of acetone and carbon disulfide mixed solvent to obtain an equal volume of acetone and carbon disulfide mixed solvent soluble matter, i.e. heavy component.

[0098] Application Example 2

[0099] In the catalytic hydrogenation conversion reaction of lignite from Zhunnan, Xinjiang, ZIF-67@mZrO2 prepared in Example 1 was added.

[0100] The specific application process is as follows:

[0101] (1) Place 5g ZIF-67@mZrO2 and 20g Xinjiang Jungnan lignite in a 1000mL high-pressure reactor and add 200ml cyclohexane;

[0102] (2) Replace the air in the reactor with N2 and then introduce 1 MPa of H2. React at 300℃ for 4 hours. After the reaction is completed, cool to room temperature.

[0103] (3) The reaction mixture was completely extracted with cyclohexane to obtain cyclohexane-soluble material, i.e., light component;

[0104] (4) Then, extraction was continued with an equal volume of acetone and carbon disulfide mixed solvent to obtain an equal volume of acetone and carbon disulfide mixed solvent soluble matter, i.e. heavy component.

[0105] The obtained light components were analyzed and compared. A comparison of the results from the non-catalytic hydrogenation conversion reaction and the catalytic hydrogenation conversion reaction is shown below. Figure 5 and Figure 6 The obtained heavy components were analyzed and compared. A comparison of the results from non-catalytic hydrogenation conversion and catalytic hydrogenation conversion is shown in [the table below]. Figure 5 ;

[0106] from Figure 5 It can be seen that the yield of the derived solubles was significantly improved after the introduction of ZIF-67@mZrO2. Specifically, the yields of the light and heavy components increased by 10% and 30%, respectively.

[0107] from Figure 6 Further analysis reveals that the yield of alkanes in the light components did not change significantly, while the yield of derived aromatics increased substantially.

[0108] This proves that ZIF-67@mZrO2 can effectively promote the catalytic hydrogenation conversion of lignite from Jungfrau in Xinjiang and achieve the goal of obtaining high-yield derivative aromatics.

[0109] Application Example 3

[0110] The ZIF-67@mZrO2 prepared in Example 1 was applied to the catalytic hydrogenation conversion of lignite-related model compounds.

[0111] The specific application process is as follows:

[0112] (1) Place 1g benzylphenyl ether, 0.5g ZIF-67@mZrO2 and 200mL n-hexane into a 1000mL stainless steel high-pressure reactor;

[0113] (2) After purging the high-pressure reactor with N2 three times, pressurize it with 5MPa H2 at room temperature;

[0114] (3) Subsequently, the high-pressure reactor is heated to 120-200°C and maintained at the set temperature for a set time;

[0115] (4) After the reaction was completed, the high-pressure reactor was cooled to room temperature and the reaction mixture was removed. The filtered filtrate was analyzed by gas chromatography-mass spectrometry. The performance analysis results of ZIF-67@mZrO2 for the catalytic hydrogenation conversion of lignite-related model compounds are shown in Table 2 below.

[0116] Table 2. Performance analysis results of ZIF-67@mZrO2 for the catalytic hydrogenation conversion of lignite-related model compounds.

[0117]

[0118] As can be seen from Table 2, the main products of the ZIF-67@mZrO2 catalytic hydrogenation conversion of benzylphenyl ether are aromatics, especially toluene. The active hydrogen species formed by H2 activation on ZIF-67@mZrO2 play a crucial role in the acquisition of derived aromatics.

[0119] First, H2 can be effectively activated into diatomic active hydrogen (H…H) on ZIF-67@mZrO2. Due to the low bond dissociation energy of H…H, H…H tends to uniformly split into hydrogen radicals (H·) on ZIF-67@mZrO2. The cooperative transfer of H· and H…H further promotes the conversion of benzylphenyl ethers and their intermediates into derived aromatics. Therefore, the ZIF-67@mZrO2 synthesized using this invention has the characteristics of high catalytic activity, high aromatic selectivity, and easy recovery.

[0120] Application Example 4

[0121] The ZIF-67@mZrO2 prepared in Example 1 was applied to the catalytic hydrogenation conversion of lignite-related model compounds.

[0122] The specific application process is as follows:

[0123] (1) Place 1g benzylphenyl ether, 0.5g ZIF-67@mZrO2 and 200mL ethanol into a 1000mL stainless steel high-pressure reactor;

[0124] (2) After purging the high-pressure reactor with N2 three times, pressurize it with 1MPa N2 at room temperature;

[0125] (3) Subsequently, the high-pressure reactor is heated to 220-300°C and maintained at the set temperature for a set time;

[0126] (4) After the reaction was completed, the high-pressure reactor was cooled to room temperature and the reaction mixture was removed. The filtered filtrate was analyzed by gas chromatography-mass spectrometry. The performance analysis results of ZIF-67@mZrO2 for the catalytic hydrogenation conversion of lignite-related model compounds are shown in Table 3 below.

[0127] Table 3. Performance analysis results of ZIF-67@mZrO2 for the catalytic hydrogenation conversion of lignite-related model compounds.

[0128]

[0129] As can be seen from Table 3, the main products of the ZIF-67@mZrO2-catalyzed ethanol hydrolysis to benzylphenyl ether are aromatic hydrocarbons, especially toluene and phenol. The active hydrogen species formed by the activation of CH3CH2OH on ZIF-67@mZrO2 play a crucial role in the acquisition of derived aromatic hydrocarbons.

[0130] CH3CH2OH can be effectively activated on ZIF-67@mZrO2 into hydrogen radicals (H·) and ethoxy radicals (CH3CH2O·). The co-transfer of H· and CH3CH2O· further promotes the conversion of benzylphenyl ethers and their intermediates into derived aromatic hydrocarbons.

[0131] This invention employs a one-pot hydrothermal synthesis method to prepare the catalyst while simultaneously modifying its morphology, structure, and size. It also overcomes the shortcomings of traditional bimetallic oxide catalysts, such as easy carbon deposition, sintering, S / N sensitivity, easy loss of active components, and difficulty in recovery. The highly active ZIF-67@mZrO2 achieves the catalytic hydrogenation conversion effects of lignite-related model compounds and Xinjiang Jungfrau lignite.

[0132] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A preparation method of a core-shell ZIF-67@mZrO2 composite material, characterized in that, It includes the following steps: a. Preparation of the ZIF-67 core: a1. Dissolve 2-methylimidazole and N,N-dimethylethylenediamine in water sequentially and stir until homogeneous; a2. Dissolve the cobalt salt in water, then add it to the solution obtained in step a1, and stir until well mixed; a3. Centrifuge and dry the obtained product to obtain the ZIF-67 core; b. Coating with mZrO2 shell: b1. Disperse the ZIF-67 core obtained in step a3 and hexadecyltrimethylammonium bromide in ethanol and mix thoroughly. b2. Add zirconium n-butoxide to the mixed solution obtained in step b1; b3. Transfer the mixed solution obtained in step b2 into a polytetrafluoroethylene (PTFE) liner, and then fit it into a PTFE liner pre-filled with deionized water to form a combination of large and small liners. b4. After sealing, place in an oven for micro-hydrolysis, cool to room temperature and remove, then wash repeatedly with deionized water and ethanol, dry, and calcine at high temperature to obtain core-shell ZIF-67@mZrO2 composite material. 2.The method for preparing the core-shell ZIF-67@mZrO 2 composite material according to claim 1, characterized in that, In step a1, the mass ratio of 2-methylimidazole to N,N-dimethylethylenediamine is (1-10):(0.5-6).

3. The method for preparing the core-shell ZIF-67@mZrO2 composite material according to claim 1, characterized in that, In step a2, the cobalt salt is Co(NO3)2·6H2O; the mass ratio of cobalt salt to 2-methylimidazole is (1-9):(1-10).

4. The method for preparing the core-shell ZIF-67@mZrO2 composite material according to claim 1, characterized in that, In step a3, the centrifugation rate is 1000-5000 rpm and the centrifugation time is 1-30 min.

5. The method for preparing the core-shell ZIF-67@mZrO2 composite material according to claim 1, characterized in that, In step b1, the mass ratio of hexadecyltrimethylammonium bromide to ZIF-67 core is (0.5-1):(0.1-2); the ratio of the volume of ethanol added to the mass of ZIF-67 core added is mL:g = (10-80):(0.1-2).

6. The method for preparing the core-shell ZIF-67@mZrO2 composite material according to claim 1, characterized in that, In step b2, the ratio of the added volume of zirconium n-butoxide to the added mass of ZIF-67 core is mL:g = (1-2):(0.1-2); the density of zirconium n-butoxide is 0.7-0.9 g / mL.

7. The method for preparing the core-shell ZIF-67@mZrO2 composite material according to claim 1, characterized in that, In step b3, the ratio of the volume of deionized water added to the mass of ZIF-67 core added is mL:g = (150-250):(0.1-2).

8. The method for preparing the core-shell ZIF-67@mZrO2 composite material according to claim 1, characterized in that, In step b4, the drying temperature is 80-150℃ and the drying time is 6-24h; the calcination temperature is 100-1000℃ and the calcination time is 1-6h.

9. A core-shell ZIF-67@mZrO2 composite material obtained by the preparation method according to any one of claims 1 to 8.

10. The application of the core-shell ZIF-67@mZrO2 composite material as described in claim 9 in the catalytic hydrogenation conversion reaction of lignite.

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