Preparation method of transparent block MOF glass

Abstract

The invention discloses a preparation method of metal organic framework (MOF) glass, according to the method, a powdery MOF crystal material can be prepared into blocky MOF glass, the specific preparation method comprises a solvent removing process and a melting cooling process, and the solvent removing process is that a solvent in a porous structure is volatilized and released through vacuum or inert atmosphere protection heating; in the melting and cooling process, glass forming is conducted, heating and melting are conducted in the oxygen-free atmosphere, then cooling is conducted, and the blocky MOF glass is prepared. The preparation method of the novel MOF glass provided by the invention solves the problems that an MOF porous framework material is difficult to form and apply, and the application range of the MOF material is greatly expanded.

Description

Technical Field

[0001] The present invention relates to a method for preparing a novel MOFs glass material. The MOFs glass material can not only be used for gas storage and separation, catalysis, drug carrier, etc., but can also be expanded to the fields of light, electricity, magnetism, sensing, etc. Background Art

[0002] MOFs (Metal Organic Framework) is a metal-organic framework material, a nanoporous material with a periodic network formed by linking organic ligands and metal ions. It is a new type of porous material with the advantages of large specific surface area, high porosity, diverse topological structure, adjustable pore structure and function, etc. It also has the advantages of simple synthesis method, low density and low synthesis cost, which makes it have great application prospects in the fields of gas storage and separation, catalysis, adsorption and drug carrier. Compared with traditional porous materials, metal-organic framework materials have more types, more diverse structures, adjustable topological structures and designable functions, which has aroused widespread research interest. The huge obstacle affecting the application of MOF materials is poor stability and difficulty in molding. The material is basically in powder state. Even after pressure molding, its material strength is very low, which limits its large-scale application.

[0003] One type of MOFs material, ZIFs (Zeolitic Imidazolate Frameworks), is a relatively stable zeolite-like porous framework material with excellent adsorption properties, and is used for the adsorption and storage of CO2 and methane gases. Currently, research on MOFs materials is mostly focused on the synthesis of new MOFs and their functionalization. In recent years, researchers have discovered that MOFs materials have the potential to be prepared into glass, which has opened up a new field of MOFs material research and found a new method for MOFs material molding, namely vitrification. However, due to the narrow melting range of ZIF4 materials, bulk glass materials cannot be prepared. Summary of the invention

[0004] The invention discloses a method for preparing a transparent bulk MOF glass material. The method is also applicable to a variety of MOFs materials, solving the difficulty in preparing MOFs glass. The method is simple and efficient, has good repeatability, and is highly practical. It can be used for large-scale production of MOFs glass, and to a certain extent solves the problem of difficult molding and application of MOFs materials.

[0005] The MOF glass preparation method of the present invention comprises two steps:

[0006] 1) Desolventization process: The initial MOF crystal powder is heated under vacuum or inert gas protection to a certain temperature and kept warm for a period of time to remove all the solvent in the porous skeleton structure;

[0007] 2) Melt quenching process: that is, the glass-forming process, in which the solvent-free MOF crystal powder is heated to a temperature above the melting temperature and below the decomposition temperature under vacuum or inert gas protection, and then quenched to obtain a transparent bulk MOF glass material;

[0008] The initial MOF crystal powder used in step 1) is mainly ZIF-62, ZIF-4, TIF-4, ZIF-76, etc., which are mainly prepared by solvothermal method;

[0009] Step 1) uses a vacuum desolventization method: the initial MOF powder is placed in a vacuum drying oven at 200-250°C for 10-20 hours to completely remove the solvent;

[0010] At the same time, the vacuum desolvation method can also be used to place the initial MOF powder in a vacuum tube furnace and connect it to a vacuum device equipped with a cold hydrazine Dewar bottle to prevent the volatile substances from damaging the vacuum device. While evacuating the vacuum, the temperature is heated to 180-250°C, and the solvent can be completely volatilized, thereby obtaining a solvent-free MOF crystal material.

[0011] The inert gas protection desolventizing method described in step 1) is to place the initial MOF powder in a vacuum tube furnace, introduce a 40-100 ml / min N2 or Ar gas flow, and heat it to 300-350°C to completely remove the solvent; heating to this temperature can completely remove the solvent without substantially destroying the crystal structure of MOF;

[0012] The vacuum melting method described in step 2) is to seal the solvent-free MOF powder material obtained by the above desolventizing method into a vacuum quartz tube, and then place it in a muffle furnace or a tube furnace and heat it to 450-600°C. After the powder is melted, it is kept warm for 0.5-2h. After the melt is uniform, it is taken out and quenched in water or cooled in air to obtain uniform transparent MOF glass;

[0013] The vacuum melting method described in step 2) is suitable for most MOFs materials that can form glass because it can achieve rapid cooling, which is conducive to the formation of glass;

[0014] Step 2) The inert gas protection melting method: place the solvent-free MOF powder in a vacuum tube furnace, introduce 40-100 ml / min of N2 or Ar gas flow, heat to 450-600°C, keep warm for 0.5-2h, stop heating after the melt is uniform, and cool with the furnace to obtain uniform transparent MOF glass;

[0015] The inert gas protection melting method described in step 2) can be combined with the previous desolventizing process, that is, the powder is placed in a tube furnace, a 40-100 ml / min N2 or Ar gas flow is introduced, and the solvent is removed by heating to 300-350°C, and then the temperature is continued to be heated to 450-600°C to melt, and then cooled to obtain a uniform transparent MOF glass;

[0016] The inert atmosphere protection melting method described in step 2) is suitable for preparing MOF materials with strong glass-forming ability such as ZIF-62 and TIF-4, because its cooling process cannot control rapid cooling. That is, these materials can be glassed under relatively slow cooling.

[0017] Compared with the prior art, the advantages of the present invention are:

[0018] This patent realizes the large-scale preparation of metal organic framework glass. By selecting fusible MOF crystal powder and using the melting-cooling preparation method under vacuum and inert atmosphere protection, transparent block MOF glass can be obtained, solving the problem that MOF materials are difficult to shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 yes Figure 1 Thermal analysis curves of melting and glass formation of a typical MOF glass (ZIF-62);

[0020] Figure 2 It is a prepared transparent bulk MOF glass. DETAILED DESCRIPTION

[0021] The following examples are intended to further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. Other specific implementation methods obtained according to the present invention are also within the scope of the claims described in this application.

[0022] Embodiment 1:

[0023] Take 1.7306g Zn(NO3)2·6H 2 O, 5.3468g imidazole, 1.0309g benzimidazole were dissolved in 50ml DMF, stirred for 1h, placed in a 100ml polytetrafluoroethylene-lined hydrothermal autoclave, reacted in a 100-130°C drying oven for 24-96h, and after cooling, the product powder was washed and dried to obtain ZIF-62 crystalline powder;

[0024] Take a certain amount of ZIF-62 crystal powder, place it in a glass container, put it in a vacuum drying oven at 200-230℃, evacuate, and keep warm for 10-16h to completely remove the solvent. After that, take out the powder;

[0025] The solvent-free ZIF-62 crystal powder was placed in a quartz tube and vacuumed to 1.0-5.0×10 -3 Pa vacuum degree, and then the quartz tube is sealed with hydrogen-oxygen flame to make the ZIF-62 powder in a vacuum oxygen-free state;

[0026] Place a vacuum quartz tube containing ZIF-62 powder in a muffle furnace or a tubular furnace, heat it to 500-580°C at a heating rate of 5-10°C / min, and keep it warm for 1-2 hours. After the insulation time is over, take out the quartz tube and immediately put it into water or ice water for cooling to obtain ZIF-62 glass.

[0027] Embodiment 2:

[0028] Similarly, 1.7306 g Zn(NO3)2·6H2O, 5.3468 g imidazole, and 1.0309 g benzimidazole were dissolved in 50 ml DMF, stirred for 1 h, placed in a 100 ml polytetrafluoroethylene-lined hydrothermal autoclave, reacted in a 100-130 ° C drying oven for 24-96 h, and after cooling, the product powder was washed and dried to obtain ZIF-62 crystalline powder;

[0029] Take a certain amount of ZIF-62 crystal powder, put it in a glass container, put it in a vacuum tube furnace, connect it to a vacuum device equipped with a cold hydrazine Dewar flask, heat it while evacuating, heat it to 250-320℃, and completely remove the solvent without heat preservation or short-term heat preservation, and take out the powder after cooling with the furnace;

[0030] The solvent-free ZIF-62 crystal powder was placed in a quartz tube and vacuumed to 1.0-5.0×10 -3 Pa vacuum degree, and then the quartz tube is sealed with hydrogen-oxygen flame to make the ZIF-62 powder in a vacuum oxygen-free state;

[0031] Place a vacuum quartz tube containing ZIF-62 powder in a muffle furnace or a tubular furnace, heat it to 500-580°C at a heating rate of 5-10°C / min, and keep it warm for 1-2 hours. After the insulation time is over, take out the quartz tube and immediately put it into water or ice water for cooling to obtain ZIF-62 glass.

[0032] Embodiment 3:

[0033] A certain amount of ZIF-62 crystal material prepared by the same solvothermal reaction as in the above embodiment is placed in a glass container, placed in a vacuum tube furnace, evacuated, and then introduced into a 40-80 ml / min Ar gas flow, and heated to 320-370° C. at the same time, the solvent in the pores of the ZIF-62 material can be removed to obtain solvent-free ZIF-62 powder;

[0034] The solvent-free ZIF-62 crystal powder was placed in a quartz tube and vacuumed to 1.0-5.0×10 -3 Pa vacuum degree, and then the quartz tube is sealed with hydrogen-oxygen flame to make the ZIF-62 powder in a vacuum oxygen-free state;

[0035] Place a vacuum quartz tube containing ZIF-62 powder in a muffle furnace or a tubular furnace, heat it to 500-580°C at a heating rate of 5-10°C / min, and keep it warm for 1-2 hours. After the insulation time is over, take out the quartz tube and immediately put it into water or ice water for cooling to obtain ZIF-62 glass.

[0036] Embodiment 4:

[0037] A certain amount of ZIF-62 crystalline material is prepared by the same solvent thermal reaction as in the above embodiment, and is placed in a glass container. The container is placed in a vacuum tube furnace and evacuated. Then, an Ar gas flow of 40-80 ml / min is introduced and the material is heated to 320-370°C. The solvent in the pores of the ZIF-62 material can be removed to obtain a solvent-free ZIF-62 powder. The Ar gas flow is then maintained and the material is heated to 500-580°C for 1-2 hours. After the insulation time is over, the material is cooled with the furnace to obtain ZIF-62 glass.

[0038] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a transparent bulk MOF glass, characterized in that: The preparation method comprises the following steps: 1) Solvent removal process: The initial fusible MOF crystal powder is heated under vacuum or inert gas protection to a set temperature and kept warm to remove all the solvent in the porous structure; 2) Melt quenching process: The solvent-free MOF crystal powder is heated to a temperature above the melting temperature and below the decomposition temperature under vacuum or inert gas protection, and then quenched to obtain a transparent bulk MOF glass material.

2. The preparation method according to claim 1, characterized in that: The initial MOF crystal powder used includes one or a combination of ZIF-62, ZIF-4, TIF-4, and ZIF-76.

3. The preparation method according to claim 1, characterized in that: The preparation method step 1) adopts a vacuum desolvation method: the solvent can be completely removed by treating the solvent in a vacuum drying oven at a temperature above the boiling point of the solvent for 10-20 hours; or the solvent is completely evaporated while being heated in a vacuum device equipped with a cold hydrazine Dewar flask to obtain a solvent-free MOF crystal material.

4. The preparation method according to claim 1, characterized in that: The preparation method step 1) adopts the inert gas protection desolventization method: the initial MOF powder is placed in a vacuum tube furnace, a 40-100 ml / min N2 or Ar gas flow is introduced, and the solvent is completely removed by heating to the solvent complete volatilization temperature.

5. The preparation method according to claim 1, characterized in that: The preparation method step 2) adopts a vacuum melting method: the obtained solvent-free MOF material is sealed in a vacuum quartz tube, heated to a temperature between the melting temperature and the decomposition temperature, kept warm until the melt is uniform, taken out and quenched in water to obtain uniform transparent MOF glass.

6. The preparation method according to claim 1, characterized in that: The preparation method step 2) adopts an inert gas protection melting method: placing solvent-free MOF powder in a vacuum tube furnace, introducing a 40-100 ml / min N2 or Ar gas flow, heating to the melting temperature and before the decomposition temperature, keeping warm for a period of time until the melt is uniform, stopping heating, and cooling with the furnace to obtain uniform transparent MOF glass.

7. The preparation method according to claim 1, characterized in that: The solvent is first removed by heating under the protection of an inert gas flow, and then the mixture is heated until it melts, and then cooled to obtain a uniform and transparent MOF glass.

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