Metal organic framework adsorbent for carbon dioxide adsorption and preparation method thereof

Abstract

The invention belongs to the technical field of adsorbent preparation, and particularly relates to a metal organic framework adsorbent for carbon dioxide adsorption and a preparation method thereof. The preparation method comprises the following specific steps: carrying out alkali treatment on a metal organic framework adsorbent precursor synthesized by using formic acid and aluminum hydroxide as raw materials, and carrying out secondary synthesis on the metal organic framework adsorbent precursor, formic acid and organic amines to prepare the metal organic framework adsorbent for carbon dioxide adsorption. The method effectively solves the problems of poor carbon dioxide adsorption rate, difficult desorption and the like of the MOFs material, especially ALF in industrial application.

Description

Technical Field

[0001] The present invention belongs to the technical field of adsorbent preparation, and specifically relates to a metal organic framework adsorbent for carbon dioxide adsorption and a preparation method thereof. Technical Background

[0002] Carbon dioxide (CO2) is a greenhouse gas that poses a significant threat to the Earth's environment. The greenhouse effect caused by large-scale CO2 emissions has led to a series of environmental problems, including glacial melting, sea level rise, and ocean acidification. Therefore, the vigorous development of technologies for CO2 capture, storage, conversion, and utilization is of vital importance to human economic and social development.

[0003] The technologies currently being developed and applied in industry for separating and capturing carbon dioxide mainly include physical adsorption separation technology, chemical absorption separation technology, cryogenic separation technology, membrane separation technology, and adsorption separation technology. Among them, the comprehensive energy consumption and investment of physical adsorption separation technology are far lower than those of other separation technologies. In industrial applications, physical adsorption separation technology can be subdivided into pressure swing adsorption technology (PSA), temperature swing adsorption technology (TSA), and pressure-temperature swing coupled adsorption technology (PTSA). Pressure swing adsorption technology has many advantages, such as being green and environmentally friendly, simple process, low cost, and excellent separation and purification effects. Its core lies in the preparation and application of adsorbent materials.

[0004] Metal-organic frameworks (MOFs) are a class of crystalline porous materials with periodic network structures formed by self-assembly of multidentate organic ligands and metal ions or metal clusters. Compared to many traditional adsorbent materials, MOFs offer advantages such as high specific surface area, high adsorption capacity, high activity, and a uniform and modifiable pore structure. They exhibit excellent adsorption and separation capabilities for carbon dioxide in a carbon dioxide / nitrogen mixture and are easily regenerated and reused.

[0005] In their research (application number WO2022 / 260592A2), the Anthony K. Cheetham team investigated the adsorption capacity of metal-organic framework adsorbents prepared by coordinating various trivalent metal cations with formic acid for carbon dioxide. Among them, the metal-organic framework adsorbent (ALF) prepared using aluminum hydroxide and formic acid as raw materials had an equilibrium adsorption capacity of about 3.85 mmol / g (about 86.24 mL / g) for carbon dioxide under normal temperature and pressure conditions and almost no nitrogen adsorption. At the same time, the organic ligand used in this study was inexpensive formic acid, and the prepared metal-organic framework adsorbent had high resistance to gases such as NOx, SO2, water vapor, and concentrated solutions of strong acids such as hydrochloric acid, sulfuric acid, and nitric acid, and has extremely broad application prospects. However, although the saturated adsorption capacity of ALF material as a solid adsorbent is very excellent, its CO2 adsorption rate is far from meeting the process requirements of PSA, especially for large-scale treatment of flue gas, which requires the adsorbent to have the ability of low-pressure rapid adsorption. According to the ALF material prepared by the current research institute, its CO2 adsorption capacity within 3 minutes is only about 0.5mmol / g, which cannot meet the actual needs of large-scale PSA method for flue gas decarbonization. Summary of the Invention

[0006] The object of the present invention is to provide a metal organic framework adsorbent for carbon dioxide adsorption and a preparation method thereof in response to the problems existing in the prior art. In the preparation method, the present invention performs an alkali treatment on a metal organic framework adsorbent precursor synthesized with formic acid and aluminum hydroxide as raw materials, and then performs a secondary synthesis with formic acid and organic amines to obtain a metal organic framework adsorbent for carbon dioxide adsorption. The crystal grains of the metal organic framework adsorbent precursor synthesized with formic acid and aluminum hydroxide as raw materials are large, and alkali treatment can convert it into small crystal grains. Then, organic amines are used as templates and formic acid is used as raw materials to perform a secondary synthesis with it, and a metal organic framework adsorbent with smaller crystal grains can be obtained, thereby being able to more accurately control the secondary pore structure inside the crystal, forming a richer secondary pore structure, improving the problem of slow mass transfer rate in the adsorbent pores with a single carbon dioxide pore structure, and promoting the mass transfer process of adsorbents such as carbon dioxide in the adsorbent pores, thereby showing a more excellent ability to selectively adsorb and separate carbon dioxide in a carbon dioxide / nitrogen system, having a higher carbon dioxide equilibrium adsorption capacity, and being easier to desorb and regenerate. The present invention effectively solves the problems of poor carbon dioxide adsorption rate and desorption difficulty existing in the industrial application of MOFs materials, especially ALF.

[0007] In order to achieve the above object of the invention, the specific technical solutions of the present invention are as follows:

[0008] A preparation method of a metal organic framework adsorbent for carbon dioxide adsorption, comprising the following steps: using formic acid and aluminum hydroxide as main synthetic raw materials, co-heating and stirring, condensing and refluxing under oil bath conditions at a certain temperature, filtering under reduced pressure and separating a white solid after a certain period of time, and washing with anhydrous ethanol until the clear liquid is neutral; fully drying (obtaining white solid I), co-heating and stirring with a sodium hydroxide aqueous solution under water bath conditions at a certain temperature for alkali treatment, filtering under reduced pressure and separating a white solid after a certain period of time, and washing with deionized water until the clear liquid is neutral; fully drying (obtaining white solid II), co-heating and stirring with formic acid and an organic amine under oil bath conditions at a certain temperature, condensing and refluxing after a certain period of time, filtering under reduced pressure and separating a white solid, and washing with anhydrous ethanol until the clear liquid is neutral; fully drying (obtaining white solid III), tableting and granulation, grinding and sieving (preferably 10-20 mesh) to obtain particles, and finally obtaining the metal organic framework adsorbent for carbon dioxide adsorption.

[0009] As a better embodiment of the present application, the temperature of the co-heating stirring treatment in the preparation step is 60-150°C (specifically 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, etc.).

[0010] As a better embodiment of the present application, the time of the coheating and stirring treatment in the preparation step is 8 to 72 hours (specifically 8 hours, 18 hours, 28 hours, 38 hours, 48 ​​hours, 58 hours, 68 hours, 72 hours, etc.).

[0011] As a preferred embodiment of the present application, the rate of the co-heating stirring treatment in the preparation step is 200 to 1000 r / min.

[0012] As a preferred embodiment of the present application, the temperature of the alkali treatment in the preparation step is 20-40°C (specifically 20°C, 25°C, 30°C, 35°C, 40°C, etc.).

[0013] As a better embodiment of the present application, the stirring time of the alkali treatment in the preparation step is 1 to 8 hours (specifically 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc.).

[0014] As a preferred embodiment of the present application, the stirring rate of the alkali treatment in the preparation step is 100 to 500 r / min.

[0015] As a preferred embodiment of the present application, the concentration of the sodium hydroxide aqueous solution in the preparation step is 0.01 to 1 mol / L.

[0016] As a preferred embodiment of the present application, the organic amine in the preparation step is one of triethylamine, ethylenediamine, tripropylamine, dibutylamine, aniline, and ethanolamine.

[0017] As a better embodiment of the present application, in the preparation step, the mass ratio of the white solid II after alkali treatment to formic acid is 1:80 to 1:120, and the mass ratio of the white solid II to the organic amine is 1:0.05 to 1:0.1.

[0018] The specific preparation process is as follows:

[0019] (1) Formic acid and aluminum hydroxide (mass ratio of 1:80 to 1:120) were added to a three-necked flask and mixed evenly. The mixture was then heated in an oil bath at 60 to 150°C with stirring and refluxed under condensation. After 8 to 72 hours, a white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180°C for 24 hours to obtain a white solid I.

[0020] Wherein, the rate of the co-heat stirring treatment is 200-1000 r / min;

[0021] (2) Alkali treatment: take the white solid I obtained in step (1) and 100-500 mL of sodium hydroxide aqueous solution (the mass ratio of white solid I to sodium hydroxide is 10:1-100:1) and add them to a beaker and mix them evenly. Then, stir and treat the solution with alkali in a water bath at 20-40°C. After 1-8 hours, separate the white solid by filtration under reduced pressure and wash with deionized water until the clear liquid is neutral. Then, transfer all the white solids to a blast drying oven and fully dry them at 180°C for 24 hours to obtain a white solid II.

[0022] Wherein, the stirring rate of the alkali treatment is 100-500 r / min; the concentration of the sodium hydroxide aqueous solution is 0.01-1 mol / L;

[0023] (3) The white solid II obtained in step (2) and formic acid (mass ratio of 1:80 to 1:120) were added to a three-necked flask and mixed evenly, 50 to 200 mL of organic amine was slowly added dropwise, and then heated and stirred under oil bath conditions of 60 to 150 ° C, condensed and refluxed, and after 8 to 72 hours, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral, and then all the above white solids were transferred to a blast drying oven, fully dried at 180 ° C for 24 hours, and then tableted and granulated, and ground and sieved into 10 to 20 mesh particles to finally obtain a metal organic framework adsorbent for carbon dioxide adsorption;

[0024] Wherein, the rate of the co-heat stirring treatment is 200-1000 r / min;

[0025] The organic amine is one of triethylamine, ethylenediamine, tripropylamine, dibutylamine, aniline and ethanolamine.

[0026] In the above method, this method proposes a secondary modification synthesis method to solve the CO2 adsorption rate problem of ALF materials:

[0027] The metal organic framework adsorbent precursor synthesized using formic acid and aluminum hydroxide as raw materials has large grains. The ALF adsorbent material has low resistance to strong alkaline solutions such as sodium hydroxide. Therefore, the present invention modifies it by alkali treatment to convert it into small grains. Then, it is synthesized again using organic amines as templates and formic acid as raw materials. This can produce a metal organic framework adsorbent with smaller grains, thereby more accurately regulating the secondary pore structure inside its crystals, forming a richer secondary pore structure, improving the problem of slow mass transfer rate in the adsorbent pores with a single carbon dioxide pore structure, and promoting the mass transfer process of adsorbents such as carbon dioxide in the adsorbent pores. In addition, it exhibits a more excellent ability to selectively adsorb and separate carbon dioxide in a carbon dioxide / nitrogen system, has a higher carbon dioxide equilibrium adsorption capacity, and is easier to desorb and regenerate. The present invention effectively solves the problems of poor carbon dioxide adsorption rate and difficulty in desorption in industrial applications of MOFs materials, especially ALF.

[0028] Compared with the existing technology, the beneficial effects of the present invention are embodied in:

[0029] (1) The existing metal-organic framework adsorbent materials prepared according to this method have smaller grain sizes and richer secondary pore structures, which improve the problem of slow mass transfer rate within the adsorbent pores with a single carbon dioxide pore structure. It is beneficial to promote the mass transfer process of carbon dioxide and other adsorbates within the adsorbent pores, while maintaining a high carbon dioxide equilibrium adsorption capacity, and significantly improve the adsorption and desorption rates;

[0030] (2) The metal-organic framework adsorbent prepared according to this method can efficiently adsorb and separate and purify the carbon dioxide component in the carbon dioxide / nitrogen system, showing a more excellent performance in selective carbon dioxide adsorption;

[0031] (3) The raw materials used in the metal organic framework adsorbent prepared according to this method are simple, cheap and easy to obtain. It also has strong water resistance and acid resistance, and is easy to regenerate and reuse. It is a process technology that can be quickly transformed into engineering and has very broad application prospects in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The graph shows the adsorption rate of the sample synthesized after secondary modification by alkali treatment and the control sample without modification;

[0033] Among them, a is a blank comparative sample without modification and synthesis treatment; b is sample No. 1 of Example 1 that was subjected to alkali treatment modification and secondary synthesis;

[0034] Figure 2 The scanning electron microscopy comparison of the sample before and after alkali treatment modification and secondary synthesis;

[0035] Wherein, a is a blank comparative example sample which is not subjected to alkali treatment modification and secondary synthesis; b is sample No. 1 of Example which is subjected to alkali treatment modification and secondary synthesis. DETAILED DESCRIPTION

[0036] A preparation method for a metal-organic framework adsorbent for carbon dioxide adsorption. The adsorbent uses formic acid and aluminum hydroxide as main synthetic raw materials, is heated and stirred in an oil bath at a certain temperature, condensed and refluxed, and after a certain period of time, is filtered out to separate a white solid, which is then washed with anhydrous ethanol until the clear liquid is neutral; after being fully dried, the adsorbent is stirred with a sodium hydroxide aqueous solution in a water bath at a certain temperature, and after a certain period of time, is filtered out to separate a white solid, which is then washed with deionized water until the clear liquid is neutral; after being fully dried, the adsorbent is heated and stirred with formic acid and an organic amine in an oil bath at a certain temperature, condensed and refluxed, and after a certain period of time, is filtered out to separate a white solid, which is then washed with anhydrous ethanol until the clear liquid is neutral; after being fully dried, the adsorbent is pressed into tablets and granulated, and then ground and sieved into particles of 10 to 20 mesh, thereby finally obtaining a metal-organic framework adsorbent for carbon dioxide adsorption. The specific preparation process is as follows:

[0037] (1) Formic acid and aluminum hydroxide (mass ratio of 1:80 to 1:120) were added to a three-necked flask and mixed evenly, and then heated and stirred in an oil bath at 60 to 150°C, condensed and refluxed. After 8 to 72 hours, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. The white solid was then transferred to a blast drying oven and fully dried at 180°C for 24 hours; wherein the rate of the co-heating and stirring treatment was 200 to 1000 r / min;

[0038] (2) Take the dried white solid and 100-500 mL of sodium hydroxide aqueous solution (the mass ratio of white solid I to sodium hydroxide is 10:1-100:1) and add them to a beaker and mix them evenly. Then, stir and treat the solid with alkali in a water bath at 20-40°C. After 1-8 hours, separate the white solid by filtration under reduced pressure and wash it with deionized water until the clear liquid is neutral. Then, transfer all the white solids to a blast drying oven and fully dry them at 180°C for 24 hours. The concentration of the sodium hydroxide aqueous solution is 0.01-1 mol / L. The stirring rate of the alkali treatment is 100-500 r / min.

[0039] (3) The dried white solid and formic acid (mass ratio of 1:80 to 1:120) were added to a three-necked flask and mixed evenly, and 50 to 200 mL of organic amine was slowly added dropwise, and then co-heated and stirred under oil bath conditions of 60 to 150 ° C, condensed and refluxed. After 8 to 72 hours, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. Then all the white solids were transferred to a blast drying oven, fully dried at 180 ° C for 24 hours, and then tableted and granulated. The pellets were ground and sieved into 10 to 20 mesh particles to finally obtain a metal organic framework adsorbent for carbon dioxide adsorption; wherein the organic amine is one of triethylamine, ethylenediamine, ethanolamine, tripropylamine, dibutylamine, and aniline; and the rate of the co-heated and stirred treatment is 200 to 1000 r / min.

[0040] All features disclosed in this specification, or all steps in the disclosed methods or processes, except mutually exclusive features and / or steps, can be combined in any manner.

[0041] Any feature disclosed in this specification (including claims and abstract), unless otherwise stated, may be replaced by other equivalent or similar features. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0042] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0043] In this application, unmarked % indicates mass percentage.

[0044] In the present invention, some conventional operating equipment, devices and components are omitted or only briefly described.

[0045] Example 1:

[0046] A method for preparing a metal organic framework adsorbent for carbon dioxide adsorption comprises the following steps:

[0047] (1) 3 L of formic acid and 36 g of aluminum hydroxide were added to a three-necked flask and mixed uniformly. The mixture was then heated and stirred in an oil bath at 100°C (stirring rate: 750 r / min), condensed and refluxed. After 48 h, a white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180°C for 24 h to obtain a white solid I.

[0048] (2) 50 g of the dried white solid (white solid I) and 250 mL of a 0.1 mol / L sodium hydroxide aqueous solution were added to a beaker and mixed evenly. The mixture was then stirred in a water bath at 30°C (stirring rate: 300 r / min). After 3 h, the white solid was separated by filtration under reduced pressure and washed with deionized water until the clear liquid was neutral. The white solid was then transferred to a blast drying oven and dried at 180°C for 24 h. The mass of the obtained white solid (white solid II) was 37.85 g.

[0049] (3) 12 g of the dried white solid (white solid II) and 1 L of formic acid were added to a three-necked flask and mixed evenly. 100 mL of triethylamine was slowly added dropwise, and then heated and stirred in an oil bath at 100 ° C (stirring rate was 750 r / min), condensed and refluxed. After 48 hours, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. Then, all the white solids were transferred to a blast drying oven and fully dried at 180 ° C for 24 hours to obtain white solid III. The white solid III was pressed into tablets and granulated, and ground and sieved into particles of 10 to 20 mesh. Finally, a metal organic framework adsorbent for carbon dioxide adsorption was obtained, which was recorded as sample No. 1 in Example 1.

[0050] Under normal temperature and pressure conditions, the equilibrium adsorption capacity of the sample for CO2 and N2 was measured using an isothermal adsorption-desorption instrument and the separation coefficient was calculated. The results are shown in Table 1.

[0051] Under normal temperature and pressure conditions, a manual static adsorption instrument was used to measure the adsorption capacity of the sample for CO2 and N2 within 3 minutes and the separation coefficient was calculated. The results are shown in Table 2.

[0052] Example 2

[0053] A method for preparing a metal organic framework adsorbent for carbon dioxide adsorption comprises the following steps:

[0054] (1) 3 L of formic acid and 36 g of aluminum hydroxide were added to a three-necked flask and mixed evenly. The mixture was then heated and stirred in an oil bath at 100 °C (stirring rate: 750 r / min) and refluxed under condensation. After 48 h, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180 °C for 24 h.

[0055] (2) 50 g of the dried white solid and 250 mL of a 0.1 mol / L sodium hydroxide aqueous solution were added to a beaker and mixed evenly. The mixture was then stirred in a water bath at 30°C (stirring rate: 300 r / min). After 3 h, the white solid was separated by filtration under reduced pressure and washed with deionized water until the clear liquid was neutral. The white solid was then transferred to a blast drying oven and dried at 180°C for 24 h. The mass of the obtained white solid was 38.31 g.

[0056] (3) 12 g of the dried white solid and 1 L of formic acid were added to a three-necked flask and mixed evenly. 100 mL of triethylamine was slowly added dropwise, and then heated and stirred in an oil bath at 80°C (stirring rate of 750 r / min), condensed and refluxed. After 48 h, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. Then, all the white solid was transferred to a blast drying oven, dried at 180°C for 24 h, and then pressed into tablets and granules, and ground and sieved into particles of 10 to 20 mesh. Finally, a metal organic framework adsorbent for carbon dioxide adsorption was obtained, which was recorded as sample No. 2 in Example 2.

[0057] Under normal temperature and pressure conditions, the equilibrium adsorption capacity of the sample for CO2 and N2 was measured using an isothermal adsorption-desorption instrument and the separation coefficient was calculated. The results are shown in Table 1.

[0058] Under normal temperature and pressure conditions, a manual static adsorption instrument was used to measure the adsorption capacity of the sample for CO2 and N2 within 3 minutes and the separation coefficient was calculated. The results are shown in Table 2.

[0059] Example 3

[0060] A metal organic framework adsorbent for carbon dioxide adsorption and a preparation method thereof, comprising the following steps:

[0061] (1) 3 L of formic acid and 36 g of aluminum hydroxide were added to a three-necked flask and mixed evenly. The mixture was then heated and stirred in an oil bath at 100 °C (stirring rate: 750 r / min) and refluxed under condensation. After 48 h, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180 °C for 24 h.

[0062] (2) 50 g of the dried white solid and 250 mL of a 0.1 mol / L sodium hydroxide aqueous solution were added to a beaker and mixed evenly. The mixture was then stirred in a water bath at 30°C (stirring rate: 300 r / min). After 6 h, the white solid was separated by filtration under reduced pressure and washed with deionized water until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180°C for 24 h. The mass of the obtained white solid was 32.17 g.

[0063] (3) 12 g of the dried white solid and 1 L of formic acid were added to a three-necked flask and mixed evenly. 100 mL of triethylamine was slowly added dropwise, and then heated and stirred in an oil bath at 100 ° C (stirring rate was 750 r / min), condensed and refluxed. After 48 hours, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. Then, all the white solids were transferred to a blast drying oven, dried at 180 ° C for 24 hours, and then pressed into tablets and granules. The pellets were ground and sieved into 10-20 mesh particles, and finally a metal organic framework adsorbent for carbon dioxide adsorption was obtained, which was recorded as sample No. 3 in Example 3.

[0064] Under normal temperature and pressure conditions, the equilibrium adsorption capacity of the sample for CO2 and N2 was measured using an isothermal adsorption-desorption instrument and the separation coefficient was calculated. The results are shown in Table 1.

[0065] Under normal temperature and pressure conditions, a manual static adsorption instrument was used to measure the adsorption capacity of the sample for CO2 and N2 within 3 minutes and the separation coefficient was calculated. The results are shown in Table 2.

[0066] Example 4

[0067] A metal organic framework adsorbent for carbon dioxide adsorption and a preparation method thereof, comprising the following steps:

[0068] (1) 3 L of formic acid and 36 g of aluminum hydroxide were added to a three-necked flask and mixed evenly. The mixture was then heated and stirred in an oil bath at 100 °C (stirring rate: 750 r / min) and refluxed under condensation. After 48 h, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180 °C for 24 h.

[0069] (2) 50 g of the dried white solid and 250 mL of a 0.5 mol / L sodium hydroxide aqueous solution were added to a beaker and mixed evenly. The mixture was then stirred in a water bath at 30°C (stirring rate: 300 r / min). After 3 h, the white solid was separated by filtration under reduced pressure and washed with deionized water until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180°C for 24 h. The mass of the obtained white solid was 30.39 g.

[0070] (3) 12 g of the dried white solid and 1 L of formic acid were added to a three-necked flask and mixed evenly. 100 mL of triethylamine was slowly added dropwise, and then heated and stirred in an oil bath at 100 ° C (stirring rate was 750 r / min), condensed and refluxed. After 48 hours, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. Then, all the white solids were transferred to a blast drying oven, dried at 180 ° C for 24 hours, and then pressed into tablets and granules. The particles were ground and sieved into 10-20 mesh particles, and finally a metal organic framework adsorbent for carbon dioxide adsorption was obtained, which was recorded as sample No. 4 in Example 4.

[0071] Under normal temperature and pressure conditions, the equilibrium adsorption capacity of the sample for CO2 and N2 was measured using an isothermal adsorption-desorption instrument and the separation coefficient was calculated. The results are shown in Table 1.

[0072] Under normal temperature and pressure conditions, a manual static adsorption instrument was used to measure the adsorption capacity of the sample for CO2 and N2 within 3 minutes and the separation coefficient was calculated. The results are shown in Table 2.

[0073] Example 5

[0074] A metal organic framework adsorbent for carbon dioxide adsorption and a preparation method thereof, comprising the following steps:

[0075] (1) 3 L of formic acid and 36 g of aluminum hydroxide were added to a three-necked flask and mixed evenly. The mixture was then heated and stirred in an oil bath at 100 °C (stirring rate: 750 r / min) and refluxed under condensation. After 48 h, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180 °C for 24 h.

[0076] (2) 50 g of the dried white solid and 250 mL of a 0.1 mol / L sodium hydroxide aqueous solution were added to a beaker and mixed evenly. The mixture was then stirred in a water bath at 30°C (stirring rate: 300 r / min). After 3 h, the white solid was separated by filtration under reduced pressure and washed with deionized water until the clear liquid was neutral. The white solid was then transferred to a blast drying oven and dried at 180°C for 24 h. The mass of the obtained white solid was 36.44 g.

[0077] (3) 12 g of the dried white solid and 1 L of formic acid were added to a three-necked flask and mixed evenly. 60 mL of triethylamine was slowly added dropwise, and then heated and stirred in an oil bath at 100 ° C (stirring rate was 750 r / min), condensed and refluxed. After 48 h, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. Then, all the white solids were transferred to a blast drying oven, dried at 180 ° C for 24 h, and then pressed into tablets and granules. The pellets were ground and sieved into 10-20 mesh particles, and finally a metal organic framework adsorbent for carbon dioxide adsorption was obtained, which was recorded as sample No. 5 in Example 5.

[0078] Under normal temperature and pressure conditions, the equilibrium adsorption capacity of the sample for CO2 and N2 was measured using an isothermal adsorption-desorption instrument and the separation coefficient was calculated. The results are shown in Table 1.

[0079] Under normal temperature and pressure conditions, a manual static adsorption instrument was used to measure the adsorption capacity of the sample for CO2 and N2 within 3 minutes and the separation coefficient was calculated. The results are shown in Table 2.

[0080] Blank comparison

[0081] A metal organic framework adsorbent for carbon dioxide adsorption and a preparation method thereof, comprising the following steps:

[0082] 3L of formic acid and 36g of aluminum hydroxide were added to a three-necked flask and mixed evenly. The mixture was then heated and stirred in an oil bath at 100°C (stirring rate of 750r / min), condensed and refluxed. After 48h, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. The above white solid was then transferred to a blast drying oven, fully dried at 180°C for 24h, and then pressed into tablets and granules. The tablets were ground and sieved into particles of 10-20 mesh, and finally a metal organic framework adsorbent for carbon dioxide adsorption was obtained, which was recorded as a blank comparative sample.

[0083] Under normal temperature and pressure conditions, the equilibrium adsorption capacity of the sample for CO2 and N2 was measured using an isothermal adsorption-desorption instrument and the separation coefficient was calculated. The results are shown in Table 1.

[0084] Under normal temperature and pressure conditions, a manual static adsorption instrument was used to measure the adsorption capacity of the sample for CO2 and N2 within 3 minutes and the separation coefficient was calculated. The results are shown in Table 2.

[0085] Comparative Example 1

[0086] A metal organic framework adsorbent for carbon dioxide adsorption and a preparation method thereof, comprising the following steps:

[0087] (1) 3 L of formic acid and 36 g of aluminum hydroxide were added to a three-necked flask and mixed evenly. The mixture was then heated and stirred in an oil bath at 100 °C (stirring rate: 750 r / min) and refluxed under condensation. After 48 h, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180 °C for 24 h.

[0088] (2) 50 g of the dried white solid and 250 mL of a 0.1 mol / L sodium hydroxide aqueous solution were added to a beaker and mixed evenly. The mixture was then stirred in a water bath at 30°C (stirring rate: 300 r / min). After 3 h, the white solid was separated by filtration under reduced pressure and washed with deionized water until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180°C for 24 h. The mass of the obtained white solid was 36.91 g.

[0089] (3) 12 g of the dried white solid and 1 L of formic acid were added to a three-necked flask and mixed evenly. 100 mL of triethylamine was slowly added dropwise, and then heated and stirred in an oil bath at 50° C. (stirring rate was 750 r / min), condensed and refluxed. After 48 h, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. Then, all the white solid was transferred to a blast drying oven, dried at 180° C. for 24 h, and then pressed into tablets and granules. The pellets were ground and sieved into 10-20 mesh particles, and finally a metal organic framework adsorbent for carbon dioxide adsorption was obtained, which was recorded as comparative example No. 1.

[0090] Under normal temperature and pressure conditions, the equilibrium adsorption capacity of the sample for CO2 and N2 was measured using an isothermal adsorption-desorption instrument and the separation coefficient was calculated. The results are shown in Table 1.

[0091] Under normal temperature and pressure conditions, a manual static adsorption instrument was used to measure the adsorption capacity of the sample for CO2 and N2 within 3 minutes and the separation coefficient was calculated. The results are shown in Table 2.

[0092] Comparative Example 2

[0093] A metal organic framework adsorbent for carbon dioxide adsorption and a preparation method thereof, comprising the following steps:

[0094] (1) 3 L of formic acid and 36 g of aluminum hydroxide were added to a three-necked flask and mixed evenly. The mixture was then heated and stirred in an oil bath at 100 °C (stirring rate: 750 r / min) and refluxed under condensation. After 48 h, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180 °C for 24 h.

[0095] (2) 50 g of the dried white solid and 250 mL of a 0.1 mol / L sodium hydroxide aqueous solution were added to a beaker and mixed evenly. The mixture was then stirred in a water bath at 70°C (stirring rate: 300 r / min). After 3 h, the white solid was separated by filtration under reduced pressure and washed with deionized water until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180°C for 24 h. The mass of the obtained white solid was 28.53 g.

[0096] (3) 12 g of the dried white solid and 1 L of formic acid were added to a three-necked flask and mixed evenly. 100 mL of triethylamine was slowly added dropwise, and then heated and stirred in an oil bath at 100 ° C (stirring rate was 750 r / min), condensed and refluxed. After 48 hours, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. Then, all the white solids were transferred to a blast drying oven, dried at 180 ° C for 24 hours, and then pressed into tablets and granules. The pellets were ground and sieved into 10-20 mesh particles, and finally a metal organic framework adsorbent for carbon dioxide adsorption was obtained, which was recorded as comparative example No. 2 sample.

[0097] Under normal temperature and pressure conditions, the equilibrium adsorption capacity of the sample for CO2 and N2 was measured using an isothermal adsorption-desorption instrument and the separation coefficient was calculated. The results are shown in Table 1.

[0098] Under normal temperature and pressure conditions, a manual static adsorption instrument was used to measure the adsorption capacity of the sample for CO2 and N2 within 3 minutes and the separation coefficient was calculated. The results are shown in Table 2.

[0099] Comparative Example 3

[0100] A metal organic framework adsorbent for carbon dioxide adsorption and a preparation method thereof, comprising the following steps:

[0101] (1) 3 L of formic acid and 36 g of aluminum hydroxide were added to a three-necked flask and mixed evenly. The mixture was then heated and stirred in an oil bath at 100 °C (stirring rate: 750 r / min) and refluxed under condensation. After 48 h, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180 °C for 24 h.

[0102] (2) 50 g of the dried white solid and 250 mL of a 2.0 mol / L sodium hydroxide aqueous solution were added to a beaker and mixed evenly. The mixture was then stirred in a water bath at 30°C (stirring rate: 300 r / min). After 3 h, the white solid was separated by filtration under reduced pressure and washed with deionized water until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180°C for 24 h. The mass of the obtained white solid was 22.06 g.

[0103] (3) 12 g of the dried white solid and 1 L of formic acid were added to a three-necked flask and mixed evenly. 100 mL of triethylamine was slowly added dropwise, and then heated and stirred in an oil bath at 100 ° C (stirring rate was 750 r / min), condensed and refluxed. After 48 hours, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. Then, all the white solids were transferred to a blast drying oven, dried at 180 ° C for 24 hours, and then pressed into tablets and granules. The pellets were ground and sieved into 10-20 mesh particles, and finally a metal organic framework adsorbent for carbon dioxide adsorption was obtained, which was recorded as comparative example No. 3.

[0104] Under normal temperature and pressure conditions, the equilibrium adsorption capacity of the sample for CO2 and N2 was measured using an isothermal adsorption-desorption instrument and the separation coefficient was calculated. The results are shown in Table 1.

[0105] Under normal temperature and pressure conditions, a manual static adsorption instrument was used to measure the adsorption capacity of the sample for CO2 and N2 within 3 minutes and the separation coefficient was calculated. The results are shown in Table 2.

[0106] Comparative Example 4

[0107] A metal organic framework adsorbent for carbon dioxide adsorption and a preparation method thereof, comprising the following steps:

[0108] (1) 3 L of formic acid and 36 g of aluminum hydroxide were added to a three-necked flask and mixed evenly. The mixture was then heated and stirred in an oil bath at 100 °C (stirring rate: 750 r / min) and refluxed under condensation. After 48 h, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180 °C for 24 h.

[0109] (2) 50 g of the dried white solid and 250 mL of a 0.1 mol / L sodium hydroxide aqueous solution were added to a beaker and mixed evenly. The mixture was then stirred in a water bath at 30°C (stirring rate: 300 r / min). After 12 h, the white solid was separated by filtration under reduced pressure and washed with deionized water until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180°C for 24 h. The mass of the obtained white solid was 25.74 g.

[0110] (3) 12 g of the dried white solid and 1 L of formic acid were added to a three-necked flask and mixed evenly. 100 mL of triethylamine was slowly added dropwise, and then heated and stirred in an oil bath at 100 ° C (stirring rate was 750 r / min), condensed and refluxed. After 48 hours, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. Then, all the white solids were transferred to a blast drying oven, dried at 180 ° C for 24 hours, and then pressed into tablets and granules. The particles were ground and sieved into 10-20 mesh particles, and finally a metal organic framework adsorbent for carbon dioxide adsorption was obtained, which was recorded as comparative example No. 4.

[0111] Under normal temperature and pressure conditions, the equilibrium adsorption capacity of the sample for CO2 and N2 was measured using an isothermal adsorption-desorption instrument and the separation coefficient was calculated. The results are shown in Table 1.

[0112] Under normal temperature and pressure conditions, a manual static adsorption instrument was used to measure the adsorption capacity of the sample for CO2 and N2 within 3 minutes and the separation coefficient was calculated. The results are shown in Table 2.

[0113] Comparative Example 5

[0114] A metal organic framework adsorbent for carbon dioxide adsorption and a preparation method thereof, comprising the following steps:

[0115] (1) 3 L of formic acid and 36 g of aluminum hydroxide were added to a three-necked flask and mixed evenly. The mixture was then heated and stirred in an oil bath at 100 °C (stirring rate: 750 r / min) and refluxed under condensation. After 48 h, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180 °C for 24 h.

[0116] (2) 50 g of the dried white solid and 250 mL of a 0.1 mol / L sodium hydroxide aqueous solution were added to a beaker and mixed evenly. The mixture was then stirred in a 30°C water bath (stirring rate: 300 r / min). After 3 h, the white solid was separated by filtration under reduced pressure and washed with deionized water until the clear liquid was neutral. The white solid was then transferred to a forced air drying oven and dried at 180°C for 24 h. The mass of the obtained white solid was 37.16 g.

[0117] (3) 12 g of the dried white solid and 1 L of formic acid were added to a three-necked flask and mixed evenly. 300 mL of triethylamine was slowly added dropwise, and then heated and stirred in an oil bath at 100 ° C (stirring rate was 750 r / min), condensed and refluxed. After 48 hours, the white solid was separated by filtration under reduced pressure and washed with anhydrous ethanol until the clear liquid was neutral. Then, all the white solids were transferred to a blast drying oven, dried at 180 ° C for 24 hours, and then pressed into tablets and granules. The pellets were ground and sieved into 10-20 mesh particles, and finally a metal organic framework adsorbent for carbon dioxide adsorption was obtained, which was recorded as comparative example No. 5.

[0118] Under normal temperature and pressure conditions, the equilibrium adsorption capacity of the sample for CO2 and N2 was measured using an isothermal adsorption-desorption instrument and the separation coefficient was calculated. The results are shown in Table 1.

[0119] Under normal temperature and pressure conditions, a manual static adsorption instrument was used to measure the adsorption capacity of the sample for CO2 and N2 within 3 minutes and the separation coefficient was calculated. The results are shown in Table 2.

[0120] Table 1 Results of determination of equilibrium adsorption capacity of CO2 and N2 by metal organic framework adsorbents in Examples and Comparative Examples

[0121]

[0122]

[0123] Table 2 Adsorption capacity of metal organic framework adsorbents for CO2 and N2 within 3 min in the examples and comparative examples

[0124]

[0125] From the test and calculation results in Table 1 and Table 2, it can be found that when preparing the metal organic framework adsorbent, the metal organic framework adsorbent precursor is modified by alkali treatment to convert it into small crystals, and then a secondary synthesis is carried out with it using organic amines as templates and formic acid as raw materials. For example, the samples in Examples 1 to 5 all have a very high equilibrium adsorption capacity for carbon dioxide, and the adsorption capacity of carbon dioxide for the samples in Examples 1 to 5 is also higher at 3 minutes. At the same time, the samples in Examples 1 to 5 also have a higher CO2 / N2 separation coefficient, that is, a more superior ability to selectively adsorb and separate carbon dioxide; from Figure 1 It can also be seen from the adsorption rate curve in that the modified sample has a higher adsorption capacity and faster adsorption rate for carbon dioxide; Figure 2 From the comparison of the scanning electron microscope images in , it can be seen that the modified sample has a smaller grain size and richer secondary pore structure.

[0126] The above results show that the method of the present invention modifies the metal-organic framework adsorbent precursor synthesized with formic acid and aluminum hydroxide as raw materials by alkali treatment, converting it into small crystals, and then performing secondary synthesis with it using organic amines as templates and formic acid as raw materials, thereby obtaining a metal-organic framework adsorbent with smaller crystals, thereby being able to more accurately regulate the secondary pore structure inside the crystal, forming a richer secondary pore structure, improving the problem of slow mass transfer rate in the adsorbent pores with a single carbon dioxide pore structure, and promoting the mass transfer process of adsorbates such as carbon dioxide in the adsorbent pores, thereby showing a more excellent ability to selectively adsorb and separate carbon dioxide in the carbon dioxide / nitrogen system, having a higher carbon dioxide equilibrium adsorption capacity, and being easier to desorb and regenerate.

[0127] The above-described embodiments merely represent specific implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of protection of the present application. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the technical concept of the present application, and all such variations and improvements fall within the scope of protection of the present application.

[0128] This background section is provided to generally present the context of the invention, and the work of the presently named inventors, the work to the extent described in this background section, and aspects of the description in this section that did not constitute prior art at the time of filing are neither explicitly nor implicitly admitted to be prior art to the present invention.

Claims

1. A method for preparing a metal organic framework adsorbent for carbon dioxide adsorption, characterized in that: The adsorbent is synthesized using formic acid and aluminum hydroxide as main raw materials, which are heated and stirred in an oil bath, condensed and refluxed; then filtered under reduced pressure to separate a white solid, washed with anhydrous ethanol until the clear liquid is neutral, and fully dried to obtain a white solid I; then the white solid I is heated and stirred with a sodium hydroxide aqueous solution in a water bath for alkali treatment, filtered under reduced pressure to separate a white solid, washed with deionized water until the clear liquid is neutral, and fully dried to obtain a white solid II; The white solid II is then co-heated with formic acid and organic amines under oil bath conditions, stirred, condensed and refluxed, and the white solid is separated by vacuum filtration and washed with anhydrous ethanol until the clear liquid is neutral. After sufficient drying, the white solid III is obtained; the white solid III is tableted and granulated, and the particles are ground and sieved to obtain a metal organic framework adsorbent for carbon dioxide adsorption.

2. The method for preparing a metal organic framework adsorbent according to claim 1, wherein: The co-heating stirring temperature is 60-150° C.; the co-heating stirring time is 8-72 hours; and the co-heating stirring rate is 200-1000 r / min.

3. The method for preparing a metal organic framework adsorbent according to claim 1, wherein: The temperature of the alkali treatment is 20-40°C.

4. The method for preparing a metal organic framework adsorbent according to claim 1, wherein: The stirring time of the alkali treatment is 1 to 8 hours; the stirring speed of the alkali treatment is 100 to 500 r / min.

5. The method for preparing a metal organic framework adsorbent according to claim 1, wherein: The concentration of the sodium hydroxide aqueous solution is 0.01 to 1 mol / L.

6. The method for preparing a metal organic framework adsorbent according to claim 1, wherein: The organic amine in the preparation step is any one of triethylamine, ethylenediamine, tripropylamine, dibutylamine, aniline and ethanolamine.

7. The method for preparing a metal organic framework adsorbent according to claim 1, wherein: The mass ratio of the white solid II after alkali treatment to formic acid is 1:80-1:120, and the mass ratio of the white solid II to the organic amine is 1:0.05-1:0.

1.

8. The method for preparing a metal organic framework adsorbent according to claim 1, wherein: Grind and sieve out 10-20 mesh particles.

9. A metal organic framework adsorbent prepared by the method according to any one of claims 1 to 8.

10. Use of the metal organic framework adsorbent according to claim 9 in a carbon dioxide adsorption process.

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