A kind of MOFs material MOFs material Mn (bdc) (azo) and preparation method, application thereof
By preparing the MOF material Mn(bdc)(azo), the problem of difficult carbon dioxide removal from acetylene gas was solved, achieving efficient and energy-saving CO2/C2H2 separation. It has excellent selectivity and stability and is suitable for industrial acetylene gas purification.
Patent Information
- Application Number
- CN202211624225.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-12-16
- Publication Date
- 2025-12-12
- Estimated Expiration
- 2042-12-16
AI Technical Summary
In existing technologies, the removal of carbon dioxide from acetylene gas is difficult. Traditional methods are energy-intensive and have low selectivity. Existing adsorbents need to desorb acetylene before adsorbing carbon dioxide, resulting in high energy consumption and cumbersome operation.
A MOF material Mn(bdc)(azo) was prepared by hydrothermal reaction and vacuum heating activation. The material has a microporous structure and preferentially adsorbs carbon dioxide, thus achieving efficient separation of CO2/C2H2.
The material exhibits excellent CO2/C2H2 separation selectivity at room temperature and pressure, with an IAST selectivity of 23.7. Dynamic transmission experiments verified its purification effect on acetylene components in carbon dioxide/acetylene mixtures. It also has good structural stability and is suitable for industrial applications.
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Figure CN116199891B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of adsorption and separation materials, in particular to a MOFs material Mn(bdc)(azo) and a preparation method and application thereof. BACKGROUND
[0002] In industry, crude acetylene is generally prepared by hydrocarbon pyrolysis and calcium carbide method, but it usually contains a large amount of impurities, including a small amount of carbon dioxide. Removing a small amount of CO2 from crude acetylene is a very challenging task, mainly for two reasons: first, acetylene gas is a highly reactive gas with a low compression limit. At room temperature and in the absence of oxygen, the compression pressure is greater than 0.2 MPa, which will cause an explosion; second, carbon dioxide and acetylene have very similar physical properties, and both are linear structures with very similar three-dimensional spatial dimensions, making it difficult to efficiently remove carbon dioxide impurities from crude acetylene gas. The traditional methods for purifying acetylene gas in industry mainly include solvent extraction and low-temperature distillation, but both methods consume a large amount of energy, so it is urgent to develop a more energy-efficient CO2 / C2H2 separation method.
[0003] In addition, the prior art also uses the difference in adsorption capacity of adsorbents between mixed gas components to selectively adsorb specific gases, thereby achieving the purpose of separation and purification. However, the core of the adsorption separation technology is the adsorbent, and the preparation of an adsorbent with excellent separation performance and significant stability is the key to realizing low-energy gas component purification. The materials in the prior art have a common feature of preferentially adsorbing acetylene to separate carbon dioxide and acetylene, which means that to purify acetylene, the acetylene still needs to be desorbed, which not only consumes additional energy but also is complicated to operate, and the small amount of carbon dioxide fixed in the material will also be released during the desorption process, reducing the purity of the acetylene gas. Therefore, for the removal of a small amount of carbon dioxide in acetylene gas, it is of higher industrial application value to develop an adsorbent that preferentially adsorbs carbon dioxide. Moreover, the adsorption materials in the prior art also have the problem of low selectivity. Therefore, it is urgent to develop a new MOFs adsorbent with high carbon dioxide adsorption capacity and excellent CO2 / C2H2 separation selectivity to realize a more efficient and energy-saving CO2 / C2H2 separation process. SUMMARY
[0004] Therefore, in order to solve the problems of low selectivity and high energy consumption of the adsorption materials in the prior art, the present application provides a MOFs material Mn(bdc)(azo) and a preparation method thereof, and the specific technical solutions are as follows:
[0005] The MOFs material Mn(bdc)(azo) has a chemical molecular formula, wherein bdc is terephthalic acid, and azo is 4,4-azopyridine.
[0006] Further, the crystal of the MOFs material Mn(bdc)(azo) belongs to monoclinic system, space group is P121 / n1, and the cell parameters are α = γ = 90°, β = 100.845°.
[0007] The application further provides a preparation method of the MOFs material Mn(bdc)(azo), and the preparation method comprises the following steps:
[0008] uniformly mixing N,N-dimethylformamide and alcohol to obtain a mixed solvent;
[0009] uniformly mixing terephthalic acid, 4,4-azopyridine and a manganese metal salt in the mixed solvent to obtain a mixture;
[0010] adding the mixture into a high-pressure reaction kettle to perform a hydrothermal reaction, forming a suspension after the reaction, then filtering the suspension and washing with N,N-dimethylformamide to obtain a crude target product, drying the crude target product, and then placing the crude target product in a vacuum heating activation device to remove the solvent, thereby obtaining the MOFs material Mn(bdc)(azo).
[0011] Further, the manganese metal salt is one or both of anhydrous manganese chloride and manganese sulfate.
[0012] Further, the molar ratio of the manganese metal ion in the manganese metal salt, terephthalic acid and 4,4-azopyridine is 1:0.5-3:1-10.
[0013] Further, the alcohol has a carbon number of 1-4.
[0014] Further, the temperature of the hydrothermal reaction is 90-180℃, and the time is 18-72h.
[0015] Further, the temperature of the heating activation is 100-220℃, and the time is 3-12h.
[0016] In addition, the application further provides an application of the MOFs material Mn(bdc)(azo), and the MOFs material can be applied in the separation of a carbon dioxide and acetylene mixed gas, and can first adsorb carbon dioxide.
[0017] The preparation method in the above scheme is simple, the preparation process is simple and feasible, the prepared material has a microporous structure, and thus the MOFs material Mn(bdc)(azo) provided by the application not only has a good carbon dioxide adsorption capacity of 2.20 mmol / g, but also has excellent CO2 / C2H2 separation selectivity, the IAST selectivity reaches 23.7 at normal temperature and pressure, the dynamic permeation experiment proves that the material can purify the acetylene component under the condition of a carbon dioxide / acetylene mixed gas, and has high industrial application value. In addition, the MOFs material Mn(bdc)(azo) provided by the application has a stable structure, and can maintain a stable structure for a long time in humid air. BRIEF DESCRIPTION OF DRAWINGS
[0018] Figure 1 A coordination schematic diagram of the Mn(bdc)(azo)-1 prepared in the embodiment 1 of the application;
[0019] Figure 2 A structure diagram of the MOFs material Mn(bdc)(azo) prepared in the embodiment 1 of the application on the crystal face b;
[0020] Figure 3 An XRD diagram of the MOFs material Mn(bdc)(azo) prepared in the embodiments 1 to 4 of the application;
[0021] Figure 4 An XRD diagram of the Mn(bdc)(azo)-1 prepared in the embodiment 1 of the application after being synthesized and activated;
[0022] Figure 5 An XRD diagram of the Mn(bdc)(azo)-1 prepared in the embodiment 1 of the application after being placed in humid air for 30 days;
[0023] Figure 6 An adsorption isotherm diagram of the Mn(bdc)(azo)-2 prepared in the embodiment 2 of the application at 25 DEG C for carbon dioxide and acetylene;
[0024] Figure 7 An adsorption isotherm diagram of the Mn(bdc)(azo)-2 prepared in the embodiment 2 of the application at 25 DEG C for carbon dioxide and acetylene; Figure 7 An IAST model calculation diagram of the separation selectivity of the Mn(bdc)(azo)-3 obtained in the embodiment 3 of the application for CO2 / C2H2;
[0025] Figure 8 A water vapor adsorption isotherm diagram of the Mn(bdc)(azo)-4 prepared in the embodiment 4 of the application at normal temperature;
[0026] Figure 9 A dynamic permeation experiment diagram of the Mn(bdc)(azo) obtained in the embodiment 1 in a He / CO2 / C2H2 (volume ratio of 8:1:1) mixed gas. DETAILED DESCRIPTION
[0027] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to embodiments thereof. It should be understood that the specific embodiments described herein are merely intended to explain the present application and not to limit the scope of protection of the present application.
[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing specific embodiments only and is not intended to be limiting of the present application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.
[0029] The MOFs material Mn(bdc)(azo) in an embodiment of the present application has a chemical formula of Mn(bdc)(azo), wherein bdc is terephthalic acid and azo is 4,4-azopyridine.
[0030] In one embodiment, the crystal of the MOFs material belongs to a monoclinic system, has a space group of P121 / n1, and has a unit cell parameter of a=1.2 nm, b=0.7 nm, c=1.2 nm, α=γ=90°, and β=100.845°. α=γ=90°, β=100.845°.
[0031] The present application also provides a preparation method of the MOFs material Mn(bdc)(azo), which comprises the following steps:
[0032] The N,N-dimethylformamide and the alcohol are mixed uniformly to obtain a mixed solvent;
[0033] The terephthalic acid, the 4,4-azopyridine and the manganese metal salt are added into the mixed solvent and mixed uniformly to obtain a mixture;
[0034] The mixture is added into a high-pressure reaction kettle to perform a hydrothermal reaction. After the reaction is completed, a suspension is formed. Then, the suspension is filtered and washed with N,N-dimethylformamide to obtain a crude target product. After drying, the crude target product is placed in a vacuum heating device to remove the solvent, thereby obtaining the MOFs material Mn(bdc)(azo).
[0035] In one embodiment, the manganese metal salt is one or both of anhydrous manganese chloride and manganese sulfate.
[0036] In one embodiment, the molar ratio of the manganese metal ion in the manganese metal salt, the terephthalic acid and the 4,4-azopyridine is 1:0.5-3:1-10.
[0037] In one embodiment, the alcohol has a carbon number of 1-4.
[0038] In one embodiment, the hydrothermal reaction is performed at a temperature of 90-180℃ for 18-72h.
[0039] In one embodiment, the heating activation is performed at a temperature of 100-220℃ for 3-12h.
[0040] In addition, the application also provides a use of the MOFs material Mn(bdc)(azo), which can be used in the separation of carbon dioxide and acetylene mixed gas, and can first adsorb carbon dioxide.
[0041] In the above scheme, the preparation method is simple, the preparation process is simple and feasible, the prepared material has a microporous structure, and thus the MOFs material Mn(bdc)(azo) of the application not only has a good carbon dioxide adsorption capacity of 2.20mmol / g, but also has excellent CO2 / C2H2 separation selectivity, the IAST selectivity reaches 23.7 at normal temperature and normal pressure, the dynamic permeation experiment proves that the material can purify the acetylene component under the condition of carbon dioxide / acetylene mixed gas, has high industrial application value; in addition, the MOFs material Mn(bdc)(azo) of the application has stable structure, and can maintain stable structure for a long time in humid air.
[0042] The embodiments of the application will be described in detail below with reference to specific examples.
[0043] Example 1:
[0044] A preparation method of a MOFs material Mn(bdc)(azo) comprises the following steps:
[0045] 16mL of DMF and 4mL of methanol are mixed to obtain a mixed solvent;
[0046] 0.2mmol of manganese chloride, 0.01mmol of terephthalic acid and 0.2mmol of 4,4-azopyridine are sequentially added to the mixed solvent, and stirred uniformly to obtain a mixture;
[0047] The mixture is added to a high-pressure reaction kettle, sealed and placed in an oven, and then subjected to hydrothermal reaction at 90℃ for 18h, and the reacted mixture is filtered, washed and purified with DMF, and then heated and activated in vacuum at 30℃ for 3h to obtain a product, which is marked as Mn(bdc)(azo)-1.
[0048] Example 2:
[0049] A preparation method of a MOFs material Mn(bdc)(azo) comprises the following steps:
[0050] 18 mL of DMF and 6 mL of ethanol are mixed to obtain a mixed solvent;
[0051] Manganese sulfate 0.2 mmol, terephthalic acid 0.2 mmol and 4,4-azopyridine 0.6 mmol are sequentially added to the mixed solvent, and the mixture is stirred to obtain a mixture;
[0052] The mixture is added to a high-pressure reaction kettle, and after being sealed, the high-pressure reaction kettle is placed in an oven and subjected to a hydrothermal reaction at 120 DEG C for 36 h. The mixture after reaction is filtered, washed and purified with DMF, and then activated at 120 DEG C under vacuum for 5 h to obtain a product, which is marked as Mn(bdc)(azo)-2.
[0053] Example 3:
[0054] A preparation method of a MOFs material Mn(bdc)(azo) comprises the following steps:
[0055] 22 mL of DMF and 5 mL of isopropanol are mixed to obtain a mixed solvent;
[0056] Manganese chloride 0.2 mmol, terephthalic acid 0.4 mmol and 4,4-azopyridine 1.4 mmol are sequentially added to the mixed solvent, and the mixture is stirred to obtain a mixture;
[0057] The mixture is added to a high-pressure reaction kettle, and after being sealed, the high-pressure reaction kettle is placed in an oven and subjected to a hydrothermal reaction at 150 DEG C for 60 h. The mixture after reaction is filtered, washed and purified with DMF, and then activated at 180 DEG C under vacuum for 8 h to obtain a product, which is marked as Mn(bdc)(azo)-3.
[0058] Example 4:
[0059] A preparation method of a MOFs material Mn(bdc)(azo) comprises the following steps:
[0060] 24 mL of DMF and 6 mL of n-butanol are mixed to obtain a mixed solvent;
[0061] Manganese sulfate 0.2 mmol, terephthalic acid 0.6 mmol and 4,4-azopyridine 2 mmol are sequentially added to the mixed solvent, and the mixture is stirred to obtain a mixture;
[0062] The mixture was added to a high-pressure reactor, sealed, and placed in an oven. It was then subjected to a thermal reaction at 180°C for 72 hours. The resulting mixture was filtered, washed and purified with DMF, and then activated under vacuum at 220°C for 12 hours to obtain the product, labeled as Mn(bdc)(azo)-4.
[0063] Diffraction data for Mn(bdc)(azo)-1 in the examples were collected at 293 K using a single-crystal diffractometer (Rigaku XtaLab Synergy) with Cu-Kα rays as incident light. Cell parameters were obtained using the least squares method, and structural analysis and refinement were performed using the SHELXTL program. The crystallographic data of Mn(bdc)(azo) are shown in Table 1. From the results, it can be concluded that the composition of Example 1 is Mn(bdc)(azo). Examples 2-4 are the same as Example 1 and will not be described again here.
[0064] Table 1:
[0065]
[0066] As shown in Table 1, the material prepared in this application has the composition Mn(bdc)(azo), belongs to the monoclinic crystal system, has the space group P121 / n1, and its cell parameters are... α=γ=90°, β=100.845°.
[0067] in addition, Figure 1 This is a coordination diagram of Mn(bdc)(azo)-1 prepared in Example 1 of this application. Figure 1 As can be seen from the above, in the MOFs material Mn(bdc)(azo) of this application, Mn is coordinated with two nitrogen atoms of two 4,4-azopyridines, two oxygen atoms on the carboxyl group of one terephthalic acid, and two oxygen atoms of two terephthalic acids.
[0068] Figure 2 The image shows the structure of the MOF material Mn(bdc)(azo) prepared in Example 1 of this invention on crystal plane b. As can be seen from the image on crystal plane b, Mn atoms coordinate with terephthalic acid to form one plane, and Mn atoms are connected with 4,4-azopyridine as pillars to form another plane.
[0069] Figure 3 The XRD patterns of Mn(bdc)(azo) MOFs materials prepared in Examples 1-4 of this application are shown below. The materials prepared in Examples 1-4 of this invention were tested using a Bruker D8-ADVANCE X-ray diffractometer (Germany), and the results are as follows. Figure 3 As shown. From Figure 3It can be seen that the XRD diffraction peaks of Mn(bdc)(azo) prepared under different reaction conditions are basically the same, indicating that Mn(bdc)(azo) materials can be obtained under the four conditions.
[0070] Figure 4 The XRD pattern of Mn(bdc)(azo)-1 prepared in Example 1 after synthesis and activation, and the XRD pattern of the material after heating and activation in Example 1, can be observed. The PXRD diffraction peaks of the material before and after activation change significantly, especially the diffraction peak of the material after activation at 13.2° is slightly shifted to the left and the intensity is stronger, and there is an additional diffraction peak at 11.9°. The change of the PXRD diffraction peaks of the material before and after activation indicates that the structure of Mn(bdc)(azo) has a certain flexibility. The XRD diffraction patterns of the materials obtained in Examples 2-4 before and after activation are the same as those of the material obtained in Example 1.
[0071] Figure 5 The XRD pattern of Mn(bdc)(azo)-1 prepared in Example 1 after being placed in humid air for 30 days, and the PXRD spectrum of the material prepared in Example 1 after being placed in humid air for 30 days, can be seen from the figure. The PXRD diffraction peaks of the material do not change significantly, indicating that the structure of the material has good water vapor stability at room temperature. The materials obtained in Examples 2-4 also exhibit significant water vapor stability.
[0072] Figure 6 The adsorption isotherm graph of Mn(bdc)(azo)-2 prepared in Example 2 at 25°C of carbon dioxide and acetylene, the carbon dioxide and acetylene adsorption isotherm test of the material obtained in Example 2 at 25°C was carried out by Micromeritics 3-Flex adsorption analyzer. From Figure 6 It can be seen that the adsorption amount of the material for carbon dioxide at room temperature and normal pressure is as high as 2.20 mmol / g, while the adsorption amount of acetylene under the same conditions is only 0.84 mmol / g, and the ratio of carbon dioxide and acetylene adsorption amount of the material at room temperature and pressure of 0.05 bar is 9.26. It is confirmed that the material can realize the preferential adsorption of carbon dioxide, and has stronger binding force for carbon dioxide. The difference in thermodynamic binding force can realize the effective separation of the two, and the materials obtained in Examples 1, 3 and 4 also exhibit the same difference in carbon dioxide and acetylene adsorption amount as the material obtained in Example 2.
[0073] Figure 7 The separation selectivity graph of Mn(bdc)(azo)-3 obtained in Example 3 for CO2 / C2H2 calculated by IAST model, the separation selectivity of the material obtained in Example 3 for CO2 / C2H2 at the same volume was calculated by IAST model, and the separation selectivity of the material obtained in Example 3 for CO2 / C2H2 at the same volume was calculated by IAST model.Figure 7 It can be seen that with the increase of pressure, the separation selectivity of the material first decreases and then increases, and finally reaches 23.7 at normal temperature and pressure, which proves that the material has a significant separation effect on the mixed gas of carbon dioxide and acetylene. The materials obtained in Examples 1, 2 and 4 also exhibit the same separation selectivity effect as the material obtained in Example 3.
[0074] Figure 8 The water vapor adsorption isotherm graph of Mn(bdc)(azo)-4 prepared in Example 4 at normal temperature shows the water vapor adsorption isotherm of the material obtained in Example 4 at normal temperature. It can be clearly seen that the water vapor adsorption amount of the material is very low at low humidity at normal temperature, and the water vapor adsorption amount is also less than 20 mg / g at a relative humidity of 50%, which indicates that the material still has significant hydrophobic properties at medium and low humidity. The materials obtained in Examples 1-3 also have the same excellent hydrophobic properties as the material obtained in Example 4.
[0075] Figure 9 The dynamic permeation experiment graph of Mn(bdc)(azo)-1 prepared in Example 1 in He / CO2 / C2H2 (volume ratio of 8:1:1) mixed gas, 700 mg of the material obtained in Example 1 was loaded into a fixed bed adsorption column with an inlet diameter of 50 mm, and 1 ml / min of He / CO2 / C2H2 (volume ratio of 8:1:1) mixed gas was passed through the adsorption column at normal temperature and pressure to test the dynamic permeation experiment. The tail gas passing through the fixed bed adsorption column was detected by GC 9560 gas chromatograph. Figure 9 It can be seen that acetylene gas can be detected in the tail gas after 4 min of the start of the test, and carbon dioxide can be retained in the fixed bed adsorption column for 18 min, and is detected until 18 min, which proves that the material can separate and purify the acetylene component in the mixed gas of carbon dioxide and acetylene. The materials obtained in Examples 2-4 also exhibit the same dynamic permeation curve as the material obtained in Example 4.
[0076] The technical features of the above-described embodiments can be combined in any manner. In order to make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not contradict, they should be considered as within the scope of the present disclosure.
[0077] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be construed as limiting the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present patent should be subject to the appended claims.
Claims
1. A MOF material Mn(bdc)(azo), characterized in that, In the chemical formula of the MOF material Mn(bdc)(azo), bdc represents terephthalic acid and azo represents 4,4-azopyridine. The MOF material belongs to the monoclinic crystal system, with space group P121 / n1 and cell parameters of [missing information]. α=γ=90°, β=100.845°; The preparation method of MOF material Mn(bdc)(azo) includes the following steps: N,N-dimethylformamide and alcohols are mixed evenly to obtain a mixed solvent; Terephthalic acid, 4,4-azopyridine, and manganese metal salt were added to the mixed solvent and mixed evenly to obtain a mixture. The mixture was added to a high-pressure reactor for hydrothermal reaction. After the reaction was completed, a suspension was formed. The suspension was then filtered and washed with N,N-dimethylformamide to obtain a crude target product. After drying, it was placed in a vacuum heating environment to activate and remove the solvent, thus obtaining the MOF material Mn(bdc)(azo). The molar ratio of manganese metal ions, terephthalic acid, and 4,4-azopyridine in the manganese metal salt is 1:0.5-3:1-10. The hydrothermal reaction is carried out at a temperature of 90℃ to 180℃ for a duration of 18h to 72h. The heating activation temperature is 100℃~220℃, and the time is 3h~12h.
2. A method for preparing MOF material Mn(bdc)(azo), characterized in that, The preparation method is used to prepare the MOFs material as described in claim 1, and the preparation method includes the following steps: N,N-dimethylformamide and alcohols are mixed evenly to obtain a mixed solvent; Terephthalic acid, 4,4-azopyridine, and manganese metal salt were added to the mixed solvent and mixed evenly to obtain a mixture. The mixture was added to a high-pressure reactor for hydrothermal reaction. After the reaction was completed, a suspension was formed. The suspension was then filtered and washed with N,N-dimethylformamide to obtain a crude target product. After drying, it was placed in a vacuum heating environment to activate and remove the solvent, thus obtaining the MOF material Mn(bdc)(azo).
3. The preparation method according to claim 2, characterized in that, The manganese metal salt is one or both of anhydrous manganese chloride and manganese sulfate.
4. The preparation method according to claim 2, characterized in that, The molar ratio of manganese metal ions, terephthalic acid, and 4,4-azopyridine in the manganese metal salt is 1:0.5 to 3:1 to 10.
5. The preparation method according to claim 2, characterized in that, The alcohols mentioned have 1 to 4 carbon atoms.
6. An application of the MOF material Mn(bdc)(azo), characterized in that, The MOF material is the MOF material Mn(bdc)(azo) as described in claim 1.
7. The application according to claim 6, characterized in that, The MOFs material can be used in the separation of a mixture of carbon dioxide and acetylene, and can first adsorb carbon dioxide.