Preparation method and application process of carbon dioxide MOFs adsorption material based on biological template

Abstract

The invention relates to a preparation method and an application process of a carbon dioxide MOFs adsorption material based on a biological template, and relates to the technical field of gas adsorption separation. The preparation method of the MOFs material based on the biological template mainly comprises the following steps: drying, crushing and chemically pretreating a biomass material, reacting with a metal ion solution, adding an organic ligand solution, reacting in a high-pressure reaction kettle twice, filtering, washing, drying and activating to finally prepare a white MOFs solid material. The MOFs material based on the biological template disclosed by the invention has good water stability and structural stability, and shows relatively good adsorption / desorption performance and CO2 cycle performance in CO2 gas trapping in an underground coal mine; and the preparation method of the MOFs material based on the biological template is simple in process, easy to operate, low in equipment requirement, green and environment-friendly in synthesis process and low in cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas adsorption and separation, and in particular relates to a method for preparing a novel composite material for capturing CO2 in underground coal mines and its application, and specifically relates to a method for preparing a carbon dioxide MOFs adsorption material based on a biological template and its application process. Background Art

[0002] With the rapid development of materials science, metal organic frameworks (MOFs) materials have shown great application potential in gas storage, separation, catalysis, sensing and other fields due to their unique structure and properties. However, traditional MOFs material preparation methods often involve complex synthesis steps and expensive raw materials, which limits their large-scale application. Therefore, it is of great significance to develop simple, economical and environmentally friendly MOFs preparation methods.

[0003] In recent years, the preparation method of MOFs materials based on biological templates has gradually attracted attention. This method uses biomass materials as natural templates, combines metal ions with organic ligands in the pores or surfaces of biomass materials through simple chemical treatment, and then undergoes high temperature and high pressure reactions to obtain MOFs materials with specific structures and properties. This method not only simplifies the synthesis steps and reduces costs, but also can utilize the renewability of biomass materials to achieve green and sustainable production.

[0004] However, the existing bio-template-based MOFs material preparation methods still have some problems, such as the selectivity of biomass materials, the binding efficiency of metal ions and organic ligands, the purity and crystallinity of the products, etc. Therefore, it is necessary to further study and improve this method to improve the preparation efficiency and performance of MOFs materials.

[0005] The present invention aims to provide a method for preparing MOFs materials based on biological templates, and realizes efficient and environmentally friendly preparation of MOFs materials by optimizing the selection of biomass materials, pretreatment conditions, reaction conditions of metal ions and organic ligands, etc. At the same time, the present invention also relates to the capture and separation of carbon dioxide gas in coal mines using the prepared MOFs materials. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] The technical problem to be solved by the present invention is to provide a method for preparing MOFs materials based on biological templates in view of the shortcomings of the current technology, so as to solve the technical problems of the existing MOFs materials such as high preparation cost, poor adsorption performance, unfriendly environment and complex synthesis process. The MOFs material of the present invention has the characteristics of being green and environmentally friendly, low cost, simple synthesis process and good adsorption performance.

[0008] (II) Technical solution

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0010] The preparation method of carbon dioxide MOFs adsorption material based on biological template and its application process include the following steps:

[0011] a. Select biomass material as the biological template, dry the biological template at 65-75°C for 24-48h, crush it with a plant crusher, and weigh 6-10g of the biological template for chemical pretreatment;

[0012] b. Place the pretreated bio-template in a solution containing metal ions, shake it in a constant temperature water bath shaker at 60-70°C for 15-24h, place the mixed solution in a stainless steel autoclave lined with polytetrafluoroethylene (75ml), place the autoclave in a high temperature oven to fully react under certain conditions, take out the mixed solution and wait for the temperature to drop to room temperature to obtain a bio-based metal ion impregnation solution;

[0013] c. Adding an organic ligand solution to the bio-based metal ion impregnation solution, and then placing the mixture solution into a stainless steel autoclave lined with polytetrafluoroethylene (75 ml), placing the autoclave in a high-temperature oven to fully react under target conditions to obtain a reaction solution;

[0014] d. Filter and remove the biological template from the reaction solution obtained in step c to obtain a solid product, wash, dry and activate the product to obtain a white solid MOFs material.

[0015] The biomass material in step a is one of chitosan, lignin and nanocellulose, which has a rich pore structure and good biocompatibility.

[0016] The specific steps of the chemical pretreatment in step a above are as follows, and the main purpose is to remove impurities, add functional groups, etc., so as to improve its binding ability with metal ions.

[0017] (1) The weighed biomass template was placed in a 100 ml round-bottom flask, and freshly prepared 30% KOH solution was added at a solid-liquid ratio of 1:15 (m:v);

[0018] (2) placing the system in a water bath condensation device at 80° C. and rotating the reaction for 1.5 to 2.0 hours. After the reaction is completed, filtering the system, washing it repeatedly with anhydrous ethanol for 3 to 4 times, and drying it in a drying oven at 65 to 75° C. for 12 to 24 hours;

[0019] (3) Using 1 mol / L HNO3 solution to react for 40 to 60 min at the same material-liquid ratio and temperature conditions, the mixture was filtered, washed with deionized water until the pH value was neutral, and dried in a drying oven at 65 to 75°C to obtain a chemically pretreated biomass template.

[0020] The bio-template pretreated in step a is immersed in a solution containing metal ions, so that the metal ions are fully adsorbed on the pores and surface of the bio-template.

[0021] The metal ion solution in step b above contains Al 3+ , Fe 3+ Cr 3+ 、Zn 3+ , lanthanide or actinide metal ions, such as europium (Eu 3+ ), Ytterbium (Yb 3+ ), cerium (Ce 4+ ) in the reaction mixture; the certain conditions are pressure of 10-20 MPa, temperature of 100-150°C, and reaction time of 24-48 h.

[0022] In the above step c, the organic ligand solution is one or two of 2,5-dihydroxyterephthalic acid, 2-methylimidazole or 3,3′,4,4′-biphenyltetracarboxylic acid; the target conditions are pressure 10-20 MPa, temperature 200-300° C., and reaction time 48-72 h.

[0023] In the above step d, washing refers to washing with anhydrous ethanol for 3 to 4 times; drying refers to drying the product in a constant temperature drying oven at 65 to 80° C. for 12 to 24 hours.

[0024] The specific steps of activation treatment in the above step d are as follows:

[0025] (1) Grinding the prepared MOFs material into powder and screening out samples of the required particle size through a sieve;

[0026] (2) Soak in the solvent for 15 to 30 hours, then shake in water at 65 to 80°C for 48 to 72 hours, take out and wait for cooling to room temperature;

[0027] (3) The MOFs material is taken out from the solvent and dried under an inert atmosphere to obtain an activated MOFs material.

[0028] The solvent in the activation treatment step (2) of step d above is methanol; the inert atmosphere refers to nitrogen.

[0029] The bio-template-based MOFs material prepared by the above method is used for capturing and separating carbon dioxide gas in underground coal mines.

[0030] (III) Beneficial effects

[0031] The present invention provides a method for preparing MOFs materials based on biological templates, which has the following beneficial effects:

[0032] (1) The present invention uses biomass materials as natural templates and achieves efficient preparation of MOFs materials through simple chemical treatment. This method not only simplifies the synthesis steps and reduces costs, but also utilizes the renewability of biomass materials, which is in line with the green and sustainable production concept.

[0033] (2) The present invention improves the preparation efficiency and performance of MOFs materials by optimizing the selection of biomass materials, pretreatment conditions, reaction conditions of metal ions and organic ligands, etc. The prepared MOFs materials have rich pore structures, high specific surface areas, good chemical stability and biocompatibility, and provide a good material basis for the application of CO2 in coal mines.

[0034] (3) The biological templates used in the present invention are widely available and low in cost, which is conducive to large-scale production and can realize waste utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is the overall experimental flow chart of the present invention. DETAILED DESCRIPTION

[0036] Embodiments of the present invention are described in detail below. The embodiments are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0037] Example 1: Preparation of Al-MOF material using chitosan as a biotemplate

[0038] The specific steps are as follows:

[0039] (1) Chitosan was selected as a biological template, and the chitosan was dried at 70°C for 24 hours. 10 g of chitosan was weighed and placed in a 100 ml round-bottom flask, and added to a freshly prepared 30% KOH solution at a solid-liquid ratio of 1:15 (m:v). The system was placed in an 80°C water bath condenser for a rotation reaction for 1.5 hours. After the reaction, it was filtered, washed repeatedly with anhydrous ethanol for 3 to 4 times, dried in a 65°C drying oven for 24 hours, and then reacted with 1 mol / L HNO3 solution at the same solid-liquid ratio and temperature conditions for 40 minutes, filtered, washed with deionized water until the pH was neutral, and dried in a 65°C drying oven to obtain chemically pretreated chitosan;

[0040] (2) Place the pretreated chitosan in a solution containing metal Al 3+The mixed solution was placed in a stainless steel autoclave lined with polytetrafluoroethylene (75 ml) and then placed in a high-temperature oven for 24 hours at a pressure of 15 MPa and a temperature of 100 ° C. The mixed solution was taken out and the temperature was cooled to room temperature to obtain chitosan metal Al 3+ impregnation solution;

[0041] (3) In the chitosan metal Al 3+ Adding 3,3′,4,4′-biphenyltetracarboxylic acid organic ligand solution to the impregnation solution, then placing the mixture solution into a stainless steel autoclave lined with polytetrafluoroethylene (75 ml), placing the autoclave in a high-temperature oven, reacting for 24 hours at a pressure of 20 MPa and a temperature of 100° C., to obtain a reaction solution;

[0042] (4) Filter and remove chitosan from the reaction solution prepared in step (3) to obtain a solid product, wash the product with anhydrous ethanol for 3 to 4 times, dry the washed product in a constant temperature drying oven at 65°C for 12 hours, grind the dried MOFs material into powder, screen out samples of the desired particle size through a sieve, soak them in methanol solvent for 20 hours, and then shake them in 65°C water for 48 hours, take them out and wait for them to cool to room temperature, remove the solid product from the solvent, and dry it in an inert N2 atmosphere to obtain the MOFs material.

[0043] Example 2: Preparation of Al-MOF material using lignin as a bio-template

[0044] The difference between this embodiment and embodiment 1 is that the biomass material selected is lignin.

[0045] Example 3: Preparation of Al-MOF material using nanocellulose as a bio-template

[0046] The difference between this embodiment and embodiment 1 is that the biomass material selected is nanocellulose.

[0047] Example 4: Adsorption effect test

[0048] The carbon dioxide adsorption amounts of Examples 1 to 3 at 40°C and 100 KPa were measured using a high-throughput specific surface and pore size analyzer (TriStar II Plus 3.0, Micromeritics Instruments, Inc., USA), and were 0.708 mmol / g, 0.810 mmol / g, and 1.32 mmol / g, respectively. Among the three biomass materials, the Al-MOF material synthesized using nanocellulose as a bio-template had the best adsorption effect. This may be because nanofibers have a more excellent pore structure and more micropores than chitosan and lignin, resulting in the synthesized Al-MOF material having richer micropores and a better adsorption amount.

[0049] It should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0050] The present invention is not limited to the above-mentioned embodiments. Those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and purpose of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing a carbon dioxide MOFs adsorption material based on a biological template and its application process, characterized in that: The preparation method mainly comprises the following steps: a. Select biomass material as the biological template, dry the biological template at 65-75°C for 24-48h, crush it with a plant crusher, and weigh 6-10g of the biological template for chemical pretreatment; b. Place the pretreated bio-template in a solution containing metal ions, shake it in a constant temperature water bath shaker at 60-70°C for 15-24h, place the mixed solution in a stainless steel autoclave lined with polytetrafluoroethylene (75ml), place the autoclave in a high temperature oven to fully react under certain conditions, take out the mixed solution and wait for the temperature to drop to room temperature to obtain a bio-based metal ion impregnation solution; c. Adding an organic ligand solution to the bio-based metal ion impregnation solution, and then placing the mixture solution into a stainless steel autoclave lined with polytetrafluoroethylene (75 ml), placing the autoclave in a high-temperature oven to fully react under target conditions to obtain a reaction solution; d. Filter and remove the biological template from the reaction solution obtained in step c to obtain a solid product, wash, dry and activate the product to obtain a white solid MOFs material.

2. The method for preparing MOFs materials based on biological templates according to claim 1, characterized in that: The biomass material described in step a is one of chitosan, lignin and nanocellulose.

3. The method for preparing MOFs materials based on biological templates according to claim 1, characterized in that: The specific steps of the chemical pretreatment described in step a are as follows: (1) The weighed biomass template was placed in a 100 ml round-bottom flask, and freshly prepared 30% KOH solution was added at a solid-liquid ratio of 1:15 (m:v); (2) placing the system in a water bath condensation device at 80° C. and rotating the reaction for 1.5 to 2.0 hours. After the reaction is completed, filtering the system, washing it repeatedly with anhydrous ethanol for 3 to 4 times, and drying it in a drying oven at 65 to 75° C. for 12 to 24 hours; (3) Using 1 mol / L HNO3 solution to react for 40 to 60 min at the same material-liquid ratio and temperature conditions, the mixture was filtered, washed with deionized water until the pH value was neutral, and dried in a drying oven at 65 to 75°C to obtain a chemically pretreated biomass template.

4. The method for preparing MOFs materials based on biological templates according to claim 1, characterized in that: The metal ion solution in step b is Al 3+ , Fe 3+ Cr 3+ 、Zn 3+ , lanthanide or actinide metal ions, such as europium (Eu 3+ ), Ytterbium (Yb 3+ ), cerium (Ce 4+ ) in a metal salt solution; the certain conditions are a pressure of 10 to 20 MPa, a temperature of 100 to 150° C., and a reaction time of 24 to 48 hours.

5. The method for preparing MOFs materials based on biological templates according to claim 1, characterized in that: The organic ligand solution in step c is any one or two of 2,5-dihydroxyterephthalic acid, 2-methylimidazole or 3,3′,4,4′-biphenyltetracarboxylic acid; the target conditions are pressure 10-20 MPa, temperature 200-300° C., and reaction time 48-72 h.

6. The method for preparing MOFs materials based on biological templates according to claim 1, characterized in that: The washing in step d refers to washing with anhydrous ethanol for 3 to 4 times; the drying refers to drying the product in a constant temperature drying oven at 65 to 80° C. for 12 to 24 hours.

7. The method for preparing MOFs materials based on biological templates according to claim 1, characterized in that: The specific steps of the activation treatment in step d are as follows: (1) Grinding the prepared MOFs material into powder and screening out samples of the required particle size through a sieve; (2) Soak in the solvent for 15 to 30 hours, then shake in water at 65 to 80°C for 48 to 72 hours, take out and wait for cooling to room temperature; (3) The MOFs material is taken out from the solvent and dried under an inert atmosphere to obtain an activated MOFs material.

8. The method for preparing MOFs materials based on biological templates according to claim 7, characterized in that: The solvent is methanol; the inert atmosphere is nitrogen.

9. The use of the bio-templated MOFs material according to claim 1, characterized in that: The bio-template-based MOFs material is used for capturing and separating carbon dioxide gas in underground coal mines.

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