A cobalt-based metal organic framework material, a preparation method thereof and application thereof in propylene ethylene separation
The prepared cobalt-based metal organic framework material solves the problem of high energy consumption in the separation of ethylene and propylene, and achieves efficient selective separation at room temperature and pressure. It is suitable for propylene and ethylene separation and has good economy and safety.
Patent Information
- Application Number
- CN202510045757.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-13
- Publication Date
- 2025-10-17
- Estimated Expiration
- 2045-01-13
AI Technical Summary
Existing technologies consume high energy in the separation of ethylene and propylene, making it difficult to achieve efficient and low-cost separation, especially when the molecular sizes and physicochemical properties of polymer-grade C3H6 and C2H4 are similar.
Cobalt-based metal-organic framework materials are used to prepare a Co2+ coordination mode with a three-dimensional framework structure and a trinuclear cobalt cluster structural unit through a solvent thermal reaction. Combined with 4,4'-(2,6-pyrazinediyl)dibenzoic acid organic ligand, an xmz topological type material is formed with high specific surface area and porosity, which is used for propylene and ethylene separation at room temperature and pressure.
It realizes the selective adsorption separation of propylene and ethylene under low energy consumption, improves economic benefits and energy efficiency, is suitable for propylene and ethylene separation, and has good safety and separation effect.
Smart Images
Figure CN119823410B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of gas adsorption separation, and particularly relates to a cobalt-based metal organic framework material, a preparation method thereof and application of the cobalt-based metal organic framework material in propylene ethylene separation. BACKGROUND
[0002] Ethylene (C2H4) and propylene (C3H6) are the most important basic raw materials in the petrochemical industry, and are the key raw materials for producing plastics, fibers, rubber, cosmetics and medicines. In traditional industrial production, olefins containing 2-4 carbon atoms are produced by steam cracking of naphtha extracted from crude oil, and the dependence on crude oil is great. The sharp fluctuations in the price of crude oil and the decline in the reserves have a huge impact on the production of C2H4 and C3H6. In recent years, the methanol-to-olefins (MTO) process is an important and advanced method for producing C2H4 from coal and natural gas, and the reaction products mainly include C3H6 (about 21wt%) and C2H4 (about 51wt%), therefore, purification of the MTO products to obtain high-purity C3H6 and C2H4 is crucial for downstream applications and chemical manufacturing.
[0003] Due to the close molecular size and physical and chemical properties of polymer-grade C3H6 and C2H4, the separation of the two has great challenges, and the commonly used separation method mainly relies on high-pressure low-temperature rectification, which has high energy consumption and does not meet the requirements of green chemistry. SUMMARY
[0004] The purpose of the present application is to provide a cobalt-based metal organic framework material, a preparation method thereof and application of the cobalt-based metal organic framework material in propylene ethylene separation, and the cobalt-based metal organic framework material provided by the present application can selectively adsorb propylene at low energy consumption.
[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme:
[0006] The present application provides a cobalt-based metal organic framework material, which comprises a coordination metal and an organic ligand, the coordination metal is Co 2+ , and the organic ligand is 4,4'-(2,6-pyrazinediyl) dibenzoic acid.
[0007] Preferably, the cobalt-based metal organic framework material is a (3,9)-linked three-dimensional framework structure: the coordination mode of each Co 2+ is hexacoordination, which is coordinated with 1 μ3-OH and 4 oxygen atoms of carboxyl groups of different organic ligands respectively, and the remaining 1 coordination site is occupied by 1 N atom in the pyrazine ring of the organic ligand.
[0008] Preferably, the cobalt-based metal organic framework material has a trinuclear cobalt cluster structure motif, and the trinuclear cobalt cluster structure motif forms a nine-connected saturated coordination mode, each trinuclear cobalt cluster structure motif is connected to 9 organic ligands, and each organic ligand is connected to 3 trinuclear cobalt cluster structure motifs.
[0009] Preferably, the cobalt-based metal organic framework material has an xmz topology.
[0010] Preferably, the cobalt-based metal organic framework material has a specific surface area of 600-900 m 2 / g, an actual pore volume of 0.30-0.50 cm 3 / g, and a porosity of 50-70%.
[0011] The application also provides a preparation method of the cobalt-based metal organic framework material described in the above scheme, comprising the following steps:
[0012] The cobalt salt, the organic ligand, the fluoroboric acid and the solvent are mixed to perform a solvothermal reaction, the organic ligand is 4,4'-(2,6-pyrazinediyldibenzoic acid), and the cobalt-based metal organic framework material is obtained.
[0013] Preferably, the molar ratio of the cobalt salt to the organic ligand is 1-3:1.
[0014] Preferably, the temperature of the solvothermal reaction is 100-160 DEG C, and the reaction time is 12-24 h; and the solvothermal reaction is performed in a closed condition.
[0015] The application also provides an application of the cobalt-based metal organic framework material described in the above scheme or the cobalt-based metal organic framework material obtained by the preparation method described in the above scheme in propylene-ethylene separation.
[0016] Preferably, the cobalt-based metal organic framework material is activated before use, and the activation comprises the following steps: degassing activation after solvent exchange of the cobalt-based metal organic framework material.
[0017] The application provides a cobalt-based metal organic framework material. The cobalt-based metal organic framework material provided by the application can preferentially adsorb propylene in a mixture of propylene and ethylene, and can be used for separation at normal temperature and pressure, has low energy consumption and good safety, and thus maximizes economic benefits and energy efficiency. The cobalt-based metal organic framework material provided by the application has a high specific surface area, can exhibit a high selective separation effect on propylene-ethylene mixed gas at normal temperature and pressure, and has a good application prospect.
[0018] The application further provides a preparation method of the cobalt-based metal organic framework material.
[0019] The application further provides application of the cobalt-based metal organic framework material in propylene and ethylene separation. BRIEF DESCRIPTION OF DRAWINGS
[0020] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.
[0021] Figure 1 It is an optical microscope photo of the cobalt-based metal organic framework material crystal of Example 1;
[0022] Figure 2 It is a microcrystal structure diagram of the cobalt-based metal organic framework material of Example 1;
[0023] Figure 3 It is a PXRD diagram of synthesis and structure simulation of the cobalt-based metal organic framework material of Example 1;
[0024] Figure 4 It is a PXRD diagram of the cobalt-based metal organic framework material of Example 1 after soaking in different solvents;
[0025] Figure 5 It is a 77K nitrogen adsorption isotherm of the cobalt-based metal organic framework material of Example 1;
[0026] Figure 6 It is an adsorption isotherm of propylene and ethylene at 298K of the cobalt-based metal organic framework material of Example 1;
[0027] Figure 7 It is an IAST separation coefficient curve of propylene / ethylene at different molar ratios at 298K of the cobalt-based metal organic framework material of Example 1. DETAILED DESCRIPTION
[0028] The application provides a cobalt-based metal organic framework material, which comprises a coordination metal and an organic ligand. 2+ The coordination metal is Co, and the organic ligand is 4,4'-(2,6-pyrazinediy) dibenzoic acid.
[0029] In the present application, the cobalt-based metal organic framework material preferably has a (3,9)-connected three-dimensional framework structure: each Co 2+ has a coordination mode of six coordination, respectively coordinating with 1 μ3-OH and 4 oxygen atoms of carboxyl groups of different organic ligands, and the remaining 1 coordination site is occupied by 1 N atom in the pyrazine ring of the organic ligand.
[0030] In the present application, the cobalt-based metal organic framework material preferably has a trinuclear cobalt cluster structure unit, which forms a nine-connected saturated coordination mode, each trinuclear cobalt cluster structure unit connects 9 organic ligands, and each organic ligand connects 3 trinuclear cobalt cluster structure units.
[0031] In the present application, the cobalt-based metal organic framework material preferably has a topology type of xmz topology.
[0032] In the present application, the specific surface area of the cobalt-based metal organic framework material is preferably 600-900 m 2 / g, and specifically can be 750 m 2 / g, the actual pore volume is preferably 0.30-0.50 cm 3 / g, and specifically can be 0.40 cm 3 / g, the porosity is preferably 50-70%, and specifically can be 60%.
[0033] The present application also provides a preparation method of the cobalt-based metal organic framework material described in the above scheme, comprising the following steps:
[0034] Mixing a cobalt salt, an organic ligand, fluoroboric acid and a solvent (denoted as first mixing) to perform a solvothermal reaction, the organic ligand comprising 4,4'-(2,6-pyrazinediyl) dibenzoic acid, to obtain a cobalt-based metal organic framework material.
[0035] In the present application, the cobalt salt is preferably a soluble cobalt salt; the soluble cobalt salt preferably comprises one or more of cobalt chloride, cobalt nitrate, cobalt acetate and cobalt sulfate; the cobalt nitrate is preferably cobalt nitrate hydrate; and the cobalt nitrate hydrate is preferably cobalt nitrate hexahydrate.
[0036] In the present application, the molar ratio of the cobalt salt to the organic ligand is preferably 1-3:1, and specifically can be 2:1.
[0037] In the present application, the solvent preferably comprises an amide solvent and a low-boiling point solvent; the amide solvent preferably comprises one or more of N,N-dimethylformamide, N-methylformamide, N,N-dimethylacetamide and N,N-diethylformamide, more preferably N,N-dimethylacetamide; the low-boiling point solvent preferably has a boiling point of 65-100℃, and specifically can be 65℃; the low-boiling point solvent preferably comprises one or more of 1,4-dioxane, acetonitrile, methanol and ethanol, more preferably methanol; and the volume ratio of the amide solvent to the low-boiling point solvent is preferably 3-8:1, and specifically can be 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1 or 8:1.
[0038] In the present application, the ratio of the amount of substance of the cobalt salt to the volume of the solvent is preferably (0.01-0.05) mmol:(2-3) mL, and specifically can be 0.04 mmol:2.3 mL.
[0039] In the present application, the volume ratio of the amide solvent to the fluoroboric acid is preferably 50-200:1, and specifically can be 50:1, 75:1, 100:1, 125:1, 150:1, 175:1 or 200:1.
[0040] In the present application, the first mixing is preferably as follows: the cobalt salt, the organic ligand and the amide solvent are mixed and then ultrasonicated to obtain a purple clear mixed solution, and the mixed solution is mixed with the fluoroboric acid and the low-boiling point solvent.
[0041] In the present application, the temperature of the solvothermal reaction is preferably 100-160℃, and specifically can be 120℃ or 140℃, and the incubation reaction time is preferably 12-24 h, and specifically can be 14 h or 20 h; and the solvothermal reaction is preferably carried out under a sealed condition.
[0042] In the present application, after the solvothermal reaction, the obtained reaction product is preferably cooled, and then sequentially washed and dried.
[0043] In the present application, the final temperature of the cooling is preferably room temperature; the washing reagent is preferably DMA; and the drying is preferably natural drying.
[0044] The present application also provides a use of the cobalt-based metal organic framework material prepared by the preparation method in the above scheme in propylene ethylene separation.
[0045] In the present application, the cobalt-based metal organic framework material is preferably activated before use, and the activation preferably comprises the following steps: the cobalt-based metal organic framework material is solvent-exchanged and then degassed and activated.
[0046] In the present application, the solvent used for the solvent exchange preferably comprises one or more of ethanol, methanol and dichloromethane; the temperature of the solvent exchange is preferably room temperature; the time of a single solvent exchange is preferably 1-3 h, more preferably 2 h, and the frequency is preferably 4-8 times per day, and the total exchange time is preferably 3-4 days. Through solvent exchange, the present application exchanges free guest molecules (DMA, DMF, H2O, etc.) in the framework pores, facilitating subsequent activation.
[0047] In the present application, the degassing activation is preferably performed under vacuum conditions; the temperature of the degassing activation is preferably 40-90℃, and can be specifically 50℃, 60℃, 65℃, 70℃ or 80℃, and the activation time is preferably 8-12 h, and can be specifically 10 h.
[0048] In order to further illustrate the present application, the schemes of the present application are described in detail below in conjunction with the accompanying drawings and examples, but they should not be understood as limiting the scope of protection of the present application.
[0049] Example 1
[0050] This example provides a cobalt-based metal organic framework material, the organic ligand of the cobalt-based metal organic framework material is 4,4'-(2,6-pyrazinediyldibenzoic acid, and the structural formula of the organic ligand is as follows:
[0051]
[0052] 33mg of cobalt nitrate hexahydrate and 18mg of organic ligand 4,4'-(2,6-pyrazinediyldibenzoic acid were weighed into a 20mL glass vial, followed by the addition of 3.50mL of N,N-dimethylacetamide, and the glass vial containing the above mixture was ultrasonically treated to obtain a clear purple solution, then 0.50mL of methanol and 60μL of fluoroboric acid were added, and the resulting mixed solution was ultrasonically mixed until uniform, sealed with a cover, and placed in a 120℃ oven for a solvothermal reaction under the pressure generated naturally by the glass vial for 22h, and after cooling to room temperature, a light orange transparent cubic block crystal was collected, the obtained crystal was washed with DMA, and then dried in air to obtain a cobalt-based metal organic framework material.
[0053] Example 2
[0054] Take 22 mg of cobalt nitrate hexahydrate and 12 mg of organic ligand 4,4'-(2,6-pyrazinediyldibenzoic acid) into a 20 mL glass vial, then add 2.00 mL of N,N-dimethylacetamide, and then ultrasonically treat the glass vial containing the mixture to obtain a clear purple solution, then add 90 μL of fluoroboric acid, and then ultrasonically mix the obtained mixed solution uniformly, seal with a cover, and then place in a 120°C oven for reaction for 24 h, and then collect the light orange transparent cubic block crystals after cooling to room temperature, and then wash the obtained crystals with DMA, and then dry in air to obtain the cobalt-based metal-organic framework material.
[0055] The cobalt-based metal-organic framework material prepared in the present example was subjected to electron microscope observation, and the results are shown in Figure 1 The crystal structure of the cobalt-based metal-organic framework material prepared in the present example is shown in Figure 2 According to Figure 1 and Figure 2 It can be seen that the cobalt-based metal-organic framework material provided by the present application has a distorted cubic cage structure, and has a three-nuclear cobalt cluster structure unit, and exhibits good stability and high propylene / ethylene separation performance.
[0056] Test Example 1
[0057] The powder of the cobalt-based metal-organic framework material prepared in Example 1 was subjected to XRD characterization, and the results are shown in Figure 3 According to Figure 3 It can be seen that the powder XRD pattern of the cobalt-based metal-organic framework material prepared in the present application is basically consistent with the diffraction peak position of the XRD pattern obtained by single crystal structure simulation, indicating that the compound prepared in the present application is a pure phase.
[0058] The cobalt-based metal-organic framework material prepared in Example 1 was subjected to chemical stability test, and was immersed in MeCN, MeOH, EtOH, CH3COCH3 or CH2C12 solvents, respectively, and the test results are shown in Figure 4 According to Figure 4 It can be seen that the diffraction peak positions of the XRD patterns of the cobalt-based metal-organic framework material after immersion for 3 days are basically consistent, proving that the crystal structure of the cobalt-based metal-organic framework material can still exist stably in low-boiling-point organic solvents.
[0059] Test Example 2
[0060] The cobalt-based metal organic framework material prepared in Example 1 was washed with N,N-dimethylacetamide for 3 times, and solvent exchange was performed by mixing with ethanol solvent to exchange the free guest molecules in the pores, and the solvent exchange was performed at a frequency of 3 hours each time, 4 times a day, and the exchange time was 3 days to obtain a pretreated cobalt-based metal organic framework material, and then vacuum treatment was performed on the crystal at 65℃ for 10 hours to remove the ethanol molecules free in the pores to obtain a fully activated cobalt-based metal organic framework material, and further performance test was performed.
[0061] The cobalt-based metal organic framework material prepared in Example 1 was subjected to specific surface area test, and 77K nitrogen isothermal adsorption test was performed, and the results are shown in Figure 5 Figure 5 It can be seen that the nitrogen adsorption curve is a typical type I curve, the maximum nitrogen adsorption amount is 260 cm 3 / g, and the BET specific surface area is 750 m 2 / g.
[0062] Test Example 3
[0063] The cobalt-based metal organic framework material prepared in Example 1 has permanent pores and stable structure, and the activated cobalt-based metal organic framework material in Test Example 2 was subjected to isothermal adsorption test of propylene and ethylene at 298K, and the results are shown in Figure 6 Figure 6 It can be seen that the cobalt-based metal organic framework material of the present application has an adsorption amount of propylene of 77.0 cm 3 / g and an adsorption amount of ethylene of 32.0 cm 3 / g at 298K and 1 bar.
[0064] The IAST model was used to calculate the selectivity of the propylene and ethylene binary component gas, and the results are shown in Figure 7 Figure 7 It can be seen that the cobalt-based metal organic framework material prepared in Example 1 has a selectivity of 8.3, 9.0 and 9.7 for C3H6 / C2H4 binary component gas with a molar ratio of 0.5 / 0.5, 0.2 / 0.5 and 0.1 / 0.9 respectively at 298K and 1 bar, and has good selectivity.
[0065] From the above examples, it can be seen that the cobalt-based metal organic framework material provided by the present application has the ability of selectively adsorbing propylene in a mixture of propylene and ethylene, and the polymer grade ethylene is obtained by separation, and high-purity propylene is obtained by desorption, and has good application prospect.
[0066] Although the above embodiments have been described in detail, it should be understood that these are only some embodiments of the present application, but not all embodiments, and other embodiments can be obtained without creativity on the basis of the above embodiments, and these embodiments all belong to the protection scope of the present application.
Claims
1. A cobalt-based metal-organic framework material, characterized in that It includes a coordination metal and an organic ligand, wherein the coordination metal is Co 2+ The organic ligand is 4,4'-(2,6-pyrazinediyl)dibenzoic acid; the cobalt-based metal organic framework material is a (3,9)-connected three-dimensional framework structure: each Co 2+ The coordination mode is six-coordinated, coordinated with one μ3-OH and the oxygen atoms of the carboxylic acid groups of four different organic ligands, and the remaining coordination site is occupied by one nitrogen atom in the pyrazine ring of the organic ligand. The cobalt-based metal-organic framework material has a trinuclear cobalt cluster structural unit, the trinuclear cobalt cluster structural unit forms a nine-connected saturated coordination mode, each trinuclear cobalt cluster structural unit is connected to 9 organic ligands, and each organic ligand is connected to 3 trinuclear cobalt cluster structural units; The topology type of the cobalt-based metal-organic framework material is xmz topology; The preparation method of the cobalt-based metal organic framework material comprises the following steps: A cobalt salt, an organic ligand, fluoroboric acid and a solvent are mixed to undergo a solvothermal reaction, wherein the organic ligand is 4,4'-(2,6-pyrazinediyl)dibenzoic acid to obtain a cobalt-based metal organic framework material; the solvent is an amide solvent and a low-boiling point solvent; the amide solvent is one or more of N,N-dimethylformamide, N-methylformamide, N,N-dimethylacetamide and N,N-diethylformamide; and the low-boiling point solvent is one or more of 1,4-dioxane, acetonitrile, methanol and ethanol.
2. The cobalt-based metal-organic framework material according to claim 1, characterized in that The specific surface area of the cobalt-based metal organic framework material is 600-900 m 2 / g, the actual pore volume is 0.30~0.50cm 3 / g, porosity is 50~70%.
3. The method for preparing the cobalt-based metal organic framework material according to any one of claims 1 to 2, characterized in that: The following steps are involved: A cobalt salt, an organic ligand, fluoroboric acid and a solvent are mixed to undergo a solvothermal reaction, wherein the organic ligand is 4,4'-(2,6-pyrazinediyl)dibenzoic acid, to obtain a cobalt-based metal organic framework material; The solvent is an amide solvent and a low-boiling-point solvent; the amide solvent is one or more of N,N-dimethylformamide, N-methylformamide, N,N-dimethylacetamide and N,N-diethylformamide; the low-boiling-point solvent is one or more of 1,4-dioxane, acetonitrile, methanol and ethanol.
4. The preparation method according to claim 3, characterized in that The molar ratio of the cobalt salt to the organic ligand is 1-3:
1.
5. The preparation method according to claim 3, characterized in that The temperature of the solvent thermal reaction is 100-160° C., and the reaction time is 12-24 hours; the solvent thermal reaction is carried out in a closed condition.
6. Use of the cobalt-based metal organic framework material according to any one of claims 1 to 2 or the cobalt-based metal organic framework material obtained by the preparation method according to any one of claims 3 to 5 in propylene and ethylene separation.
7. The use according to claim 6, characterized in that The cobalt-based metal organic framework material is activated before use, and the activation comprises the following steps: degassing and activating the cobalt-based metal organic framework material after solvent exchange.