Preparation method and application of ZIF-8 for multi-component gas grading capture

Abstract

The invention provides a preparation method and application of ZIF-8 for multi-component gas graded capture, and belongs to the technical field of gas separation, specifically, the preparation method of the ZIF-8 provided by the invention comprises the following steps: S1, preparing a ZIF-8 precursor solution, the ZIF-8 precursor solution comprises Zn element, 2-methylimidazole, water and N, N-dimethylacetamide; and S2, enabling the ZIF-8 precursor solution to pass through a spray dryer, so as to obtain the ZIF-8 for multi-component gas grading capture. The ZIF-8 prepared by the method can be used for efficiently separating low-carbon hydrocarbon mixed gas.

Description

Technical Field

[0001] The present invention relates to the technical field of gas separation. Specifically, it relates to a preparation method and application of ZIF-8 for the hierarchical capture of multi-component gases. Background Art

[0002] The separation of light hydrocarbons is widely used in many chemical industries such as rubber manufacturing, petrochemical industry, and air treatment. At present, the separation process of light hydrocarbons mostly adopts energy-intensive fractional distillation and extractive distillation technologies, and these separation technologies have the disadvantage of high energy consumption. At the same time, for light hydrocarbons with similar boiling points, it is very difficult for traditional light hydrocarbon separation processes to separate them thoroughly.

[0003] Adsorption separation is considered a technology that can replace traditional energy-intensive separation methods. At present, adsorption separation has been widely used in the chemical industry. Adsorption separation separates molecular mixtures according to the differences in the adsorption-desorption behaviors of different components in the mixture. For the adsorption separation process, usually, the mixture is first contacted with the adsorption material under specific conditions, and then the conditions are changed to selectively remove one or more components to achieve the separation of the mixture. For a mixture of light olefins, the separation of the light olefin mixture is usually achieved by changing the pressure or temperature of the separation system.

[0004] ZIF-8 is a metal-organic framework material. For gases such as C3, C4, C5 and their isomers, the current ZIF-8 cannot effectively adsorb and separate them. Although ZIF-8 with a complete crystal structure can be synthesized by different preparation methods, due to the differences in reaction conditions, solvent systems, precursor types, additives and other factors, it will lead to differences in its microstructure such as morphology, grain size, pore structure and surface properties, and thus significantly affect its adsorption performance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: how to use ZIF-8 to achieve the separation of multi-component light hydrocarbon gases.

[0006] To solve the above technical problem, the first aspect of the present invention provides a preparation method of ZIF-8 for the hierarchical capture of multi-component gases, which specifically includes the following steps:

[0007] S1: Prepare a ZIF-8 precursor solution, and the ZIF-8 precursor solution includes Zn element, 2-methylimidazole, water and N,N-dimethylacetamide (DMAc);

[0008] S2: Pass the ZIF-8 precursor solution through a spray dryer to obtain ZIF-8 for the hierarchical capture of multi-component gases.

[0009] The preparation method of ZIF-8 for multi-component gas fractional capture provided by the present invention uses spray drying method to integrally prepare ZIF-8. The finally obtained ZIF-8 is in a granular structure. Compared with the traditional hydrothermal method for preparing ZIF-8, the preparation method provided by the present invention combines the crystallization and drying processes into one, which can greatly shorten the preparation time of ZIF-8. In addition, compared with the ZIF-8 prepared by the traditional method, the particle size and microporous structure of the ZIF-8 prepared by the spray drying method provided by the present invention have changed greatly, and this change can greatly change the gas adsorption performance of ZIF-8.

[0010] Preferably, in terms of molar parts, the ZIF-8 precursor solution includes 1 part of Zn element, 0.5 - 4 parts of 2-methylimidazole, 50 - 300 parts of water, and 20 - 200 parts of N,N-dimethylacetamide.

[0011] Preferably, in step S1, the form of the Zn element is zinc acetate dihydrate and / or zinc nitrate hexahydrate and / or zinc nitrate.

[0012] Preferably, in step S2, the temperature of the ZIF-8 precursor solution passing through the spray dryer is 130 - 220 °C.

[0013] Preferably, the nozzle diameter of the spray dryer is 0.7 - 2.0 mm.

[0014] Preferably, in step S2, the feeding speed of the spray dryer is 0.5 - 1.5 mL / s.

[0015] Preferably, the foregoing preparation method further includes the following steps:

[0016] S3: Use an organic solvent recovery device to recover the N,N-dimethylacetamide volatilized after the ZIF-8 precursor solution passes through the spray dryer.

[0017] More preferably, the organic solvent recovery device can be a condensation recovery device, and the organic solvent recovery device is installed at the gas outlet of the cyclone separator of the spray dryer.

[0018] The second aspect of the present invention provides an application of the foregoing preparation method of ZIF-8 for multi-component gas fractional capture, and uses the ZIF-8 for multi-component gas fractional capture prepared by the preparation method in the first aspect to perform fractional capture on the mixed gas.

[0019] More preferably, the ZIF-8 for multi-component gas fractional capture prepared by the preparation method provided by the present invention can be used as a gas chromatography column packing to further realize the separation and capture of multi-component gases.

[0020] Preferably, the mixed gas is a C2 mixed gas and / or a C3 mixed gas and / or a C4 mixed gas and / or a C5 mixed gas.

[0021] More preferably, the ZIF-8 for multi-component gas fractional capture prepared by the preparation method provided by the present invention can efficiently separate at least two gases among propylene / propane mixed gas, n-butane / isobutane mixed gas, 1,3-butadiene / 1-butene mixed gas, isoprene / isopentane mixed gas, benzene / cyclohexane mixed gas, n-butane, isobutane, 1,3-butadiene, 1-butene, and the C5 mixed gas.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. The present invention directly synthesizes ZIF-8 using a spray dryer. Compared with the prior art, the synthesis time of ZIF-8 in the present invention is only 0.1 - 1 s. At the same time, the present invention combines the crystallization and drying steps, which can greatly simplify the synthesis process of ZIF-8. In addition, in the preparation method provided by the present invention, the solvent can be recovered through an organic solvent recovery device and used for the preparation of the subsequent ZIF-8 precursor solution. The preparation method provided by the present invention can effectively reduce the preparation cost of ZIF-8;

[0024] 2. Compared with traditional ZIF-8, the particle size and microporous structure of the ZIF-8 prepared by the preparation method provided by the present invention have changed greatly. Further, its gas adsorption performance has also changed greatly, such that the ZIF-8 prepared by the present invention has a good separation effect on low-carbon hydrocarbon mixed gases. Description of the Drawings

[0025] Figure 1 Adsorption isotherm of 1,3-butadiene and isobutene by product M1 in Comparative Example 1;

[0026] Figure 2 XRD patterns of product M1 in Comparative Example 1 and product M2 in Example 1 of the present invention;

[0027] Figure 3 SEM images of product M1 in Comparative Example 1 and product M2 in Example 1 of the present invention;

[0028] Figure 4 Pore size distribution diagrams of product M1 in Comparative Example 1 and product M2 in Example 1 of the present invention;

[0029] Figure 5 Adsorption isotherm of 1,3-butadiene and isobutene by product M2 in Example 1;

[0030] Figure 6Test results of dynamic adsorption of the mixed gas of 1-butene and isobutene by product M1 in Comparative Example 1 of the present invention at 1 bar and 293K;

[0031] Figure 7 Test results of dynamic adsorption of the mixed gas of 1-butene and isobutene by product M2 in Example 1 of the present invention at 1 bar and 293K;

[0032] Figure 8 Test results of dynamic adsorption of the mixed gas containing four components of 1,3-butadiene, isobutene, n-butane, and n-butene by product M1 in Comparative Example 1 of the present invention at 1 bar and 293K;

[0033] Figure 9 Test results of dynamic adsorption of the mixed gas containing four components of 1,3-butadiene, isobutene, n-butane, and n-butene by product M2 in Example 1 of the present invention at 1 bar and 293K. Detailed implementation manners

[0034] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention is provided. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not used to limit the parameter range described in the present invention. Reasonable changes derived therefrom are still within the protection scope of the claims of the present invention.

[0035] It should be noted that the endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0036] To solve the technical problem of poor separation effect of ZIF-8 for low-carbon hydrocarbons in the prior art, a preparation method of ZIF-8 for multi-component gas fractional capture provided by a specific embodiment of the present invention includes the following steps:

[0037] S1: Prepare a ZIF-8 precursor solution, where the ZIF-8 precursor solution includes Zn element, 2-methylimidazole, water, and N,N-dimethylacetamide;

[0038] S2: Pass the ZIF-8 precursor solution through a spray dryer to obtain ZIF-8 for multi-component gas fractional capture.

[0039] In the above embodiments, the ZIF-8 precursor solution includes 1 part of Zn element, 0.5 - 4 parts of 2-methylimidazole, 50 - 300 parts of water, and 20 - 200 parts of N,N-dimethylacetamide.

[0040] In step S1 of the above embodiments, the form of existence of the Zn element is zinc acetate dihydrate and / or zinc nitrate hexahydrate and / or zinc nitrate.

[0041] In step S2 of the above embodiments, the temperature of the ZIF-8 precursor solution passing through the spray dryer is 130 - 220 °C.

[0042] In the above embodiments, the nozzle diameter of the spray dryer is 0.7 - 2.0 mm.

[0043] In the above embodiments, the feeding rate of the spray dryer is 0.5 - 1.5 mL / s.

[0044] More specifically, the above embodiments further include the following steps:

[0045] S3: Use a condensation recovery device to recover the N,N-dimethylacetamide volatilized after the ZIF-8 precursor solution passes through the spray dryer.

[0046] The technical solution of the present invention will be further described below through specific embodiments.

[0047] Unless otherwise defined, all terms, symbols, and other scientific terms used herein are intended to have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. In some cases, terms with conventional understood meanings are defined herein for the purpose of clarification or convenient reference, and such definitions herein should not be construed as indicating a significant difference from the conventional understanding in the art. The technical methods described or cited herein are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise stated, the use of commercially available reagents and instruments is carried out according to the protocols and parameters given by the manufacturers.

[0048] Comparative Example 1

[0049] Prepare ZIF-8 powder by a conventional method

[0050] Add 0.879 g of zinc nitrate hexahydrate and 1.776 g of 2-methylimidazole to 60 mL of methanol respectively, stir until the solution is uniform, and then add the 2-methylimidazole solution to the metal salt solution and stir for 1 h. After the reaction is completed, collect the product by centrifugation and wash it three times with methanol. Finally, dry the powder at 60 °C for 12 h and then evacuate, and dry it at 80 °C for 12 h to obtain the ZIF-8 powder, and the product is denoted as M1.

[0051] At 293 K, the adsorption isotherms of M1 for 1,3-butadiene and isobutene are asFigure 1 As shown in the figure. At 1 bar and 293 K, M1 was used to adsorb 1,3-butadiene and isobutene. The adsorption amounts and adsorption capacity ratios of 1,3-butadiene and isobutene on M1 are shown in Table 1.

[0052] As can be seen from Table 1, the adsorption capacity ratio of M1 for 1,3-butadiene and isobutene is 1.1, indicating that M1 has no adsorption separation ability for the 1,3-butadiene / isobutene mixed gas.

[0053] Table 1

[0054]

[0055] At 1 bar and 293 K, M1 was used to adsorb n-butane and isobutane. The adsorption amounts and adsorption capacity ratios of n-butane and isobutane on M1 are shown in Table 2.

[0056] As can be seen from Table 2, the adsorption capacity ratio of M1 for n-butane and isobutane is 1.79, indicating that M1 has no adsorption separation ability for the n-butane / isobutane mixed gas.

[0057] Table 2

[0058]

[0059] Example 1

[0060] Preparation of ZIF-8 powder by spray drying method

[0061] Zinc acetate dihydrate and 2-methylimidazole ligand were respectively dissolved in an aqueous DMAc solution. After rapid mixing, a ZIF-8 precursor solution was obtained. The molar ratio of Zn, 2-methylimidazole, water, and DMAc in the precursor solution was 1:2:90:36.

[0062] The vacuum circulation pump carried by the spray dryer extracted the ZIF-8 precursor solution at a rate of 1 ml / s. After ZIF-8 was dispersed into droplets in the spray dryer, it was released into a tubular cavity at 220 °C. The solvent was rapidly volatilized in the tubular cavity and recovered through an organic solution recovery device. The dried ZIF-8 powder was collected into a collection tank through circulating air to obtain the ZIF-8 powder, and the product was denoted as M2.

[0063] At 293 K, the adsorption isotherms of M2 for 1,3-butadiene and isobutene are as Figure 5 shown. At 1 bar and 293 K, M2 was used to adsorb 1,3-butadiene and isobutene. The adsorption amounts and adsorption capacity ratios of 1,3-butadiene and isobutene on M2 are shown in Table 3.

[0064] As can be seen from Table 3, the adsorption capacity ratio of M2 for 1,3-butadiene and isobutene is 57.10, indicating that M2 has a strong adsorption capacity for 1,3-butadiene and can effectively separate the mixture of 1,3-butadiene and isobutene.

[0065] Table 3

[0066]

[0067] At 1 bar and 293 K, M2 was used to adsorb 1-butene and isobutene. The adsorption amounts and adsorption capacity ratios of 1-butene and isobutene on M2 are shown in Table 4.

[0068] As can be seen from Table 4, the adsorption capacity ratio of M2 for 1-butene and isobutene is 49.91, indicating that M2 has a stronger preferential adsorption capacity for 1-butene and can effectively separate the mixture of 1-butene and isobutene.

[0069] Table 4

[0070]

[0071] At 1 bar and 293 K, M2 was used to adsorb n-butane and isobutane. The adsorption amounts and adsorption capacity ratios of n-butane and isobutane on M2 are shown in Table 5.

[0072] As can be seen from Table 5, the adsorption capacity ratio of M2 for n-butane and isobutane is 41.13, indicating that M2 has a strong adsorption capacity for n-butane and can effectively separate the n-butane / isobutane mixture.

[0073] Table 5

[0074]

[0075] The XRD characterization of M1 and M2 is as Figure 2 shown. The XRD results show that both products are crystals. The SEM characterization of M1 and M2 is as Figure 3 shown. As can be seen from the SEM results, the particles of M1 are uniform with a particle size of about 50 nm, and the particles of M2 are uniform with a particle size of about 1.5 μm. The pore distribution diagrams of M1 and M2 are as Figure 4 shown. As Figure 4 can be seen, there are significant differences in the micro-pore structures of M1 and M2. From the above characterizations, it can be known that the morphology and micro-pore structure of the ZIF-8 particles prepared by the spray drying method are significantly different from those of the ZIF-8 prepared by the conventional method, which is also the main reason why the ZIF-8 prepared by the spray drying method can be used for multi-component gas separation.

[0076] Example 2

[0077] Separation of 1-butene and isobutene mixed gas

[0078] The dynamic adsorption test of M1 prepared in Comparative Example 1 on the mixed gas containing 1-butene and isobutene was carried out at 1 bar and 293 K, and the results are as Figure 6 shown.

[0079] As Figure 6 can be seen, M1 did not show obvious gas adsorption and separation ability for the mixed gas of 1-butene and isobutene.

[0080] The dynamic adsorption test of M2 prepared in Example 1 on the mixed gas containing 1-butene and isobutene was carried out at 1 bar and 293 K, and the results are as Figure 7 shown.

[0081] As Figure 7 can be seen, M2 showed excellent gas adsorption and separation ability for the mixed gas of 1-butene and isobutene.

[0082] Example 3

[0083] Separation of mixed gas of 1,3-butadiene, isobutene, n-butane and n-butene

[0084] The dynamic adsorption test of M1 prepared in Comparative Example 1 on the mixed gas containing four components of 1,3-butadiene, isobutene, n-butane and n-butene was carried out, and the results are as Figure 8 shown.

[0085] As Figure 8 can be seen, M2 did not show obvious gas adsorption and separation ability for the mixed gas of 1,3-butadiene, isobutene, n-butane and n-butene.

[0086] The dynamic adsorption test of M2 prepared in Example 1 on the mixed gas containing four components of 1,3-butadiene, isobutene, n-butane and n-butene was carried out at 1 bar and 293 K, and the results are as Figure 9 shown.

[0087] As Figure 9 can be seen, M2 showed excellent gas adsorption and separation ability for the mixed gas of 1,3-butadiene, isobutene, n-butane and n-butene.

[0088] Example 4

[0089] Separation of C5 mixed gas

[0090] The adsorption capacity test of M1 prepared in Comparative Example 1 and M2 prepared in Example 1 on the mixed gas containing three components of isopentane, isoprene and 2-pentene was carried out at 1 bar and 293 K, and the results are shown in Table 6.

[0091] As can be seen from Table 6, the difference in the adsorption capacity of M1 for the three gases of isopentane, isoprene and 2-pentene is small, and it is not suitable for the separation of C5 mixed gas.

[0092] There are significant differences in the adsorption amounts of M2 for isopentane, isoprene, and 2-pentene, which can be used for the separation of C5 mixed gas.

[0093] Table 6

[0094]

[0095] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. A preparation method of ZIF-8 for multi-component gas fractional capture, characterized in that, It includes the following steps: S1: Prepare a ZIF-8 precursor solution, and the ZIF-8 precursor solution includes Zn element, 2-methylimidazole, water and N,N-dimethylacetamide; S2: Pass the ZIF-8 precursor solution through a spray dryer to obtain ZIF-8 for multi-component gas fractional capture.

2. The preparation method of ZIF-8 for multi-component gas fractional capture according to claim 1, characterized in that, In terms of molar parts, the ZIF-8 precursor solution includes 1 part of Zn element, 0.5 - 4 parts of 2-methylimidazole, 50 - 300 parts of water and 20 - 200 parts of N,N-dimethylacetamide.

3. The preparation method of ZIF-8 for multi-component gas fractional capture according to claim 1, characterized in that, In the step S1, the form of existence of Zn is zinc acetate dihydrate and / or zinc nitrate hexahydrate and / or zinc nitrate.

4. The preparation method of ZIF-8 for multi-component gas fractional capture according to claim 1, characterized in that, In the step S2, the temperature for the ZIF-8 precursor solution to pass through the spray dryer is 130 - 220 °C.

5. The preparation method of ZIF-8 for multi-component gas fractional capture according to claim 1, wherein, The nozzle diameter of the spray dryer is 0.7 - 2.0 mm.

6. The preparation method of ZIF-8 for multi-component gas fractional capture according to claim 1, characterized in that, In the step S2, the feeding speed of the spray dryer is 0.5 - 1.5 mL / s.

7. The preparation method of ZIF-8 for multi-component gas fractional capture according to claim 1, characterized in that, It further includes the following steps: S3: Use an organic solvent recovery device to recover the N,N-dimethylacetamide volatilized after the ZIF-8 precursor solution passes through the spray dryer.

8. Application of the ZIF-8 for multi-component gas fractional capture prepared by the preparation method according to any one of claims 1 - 7 in multi-component gas fractional capture.

9. The application according to claim 8, characterized in that, The mixed gas is a C2 mixed gas and / or a C3 mixed gas and / or a C4 mixed gas and / or a C5 mixed gas.

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