Boron-doped MOF (Metal Organic Framework) derived carbon and multi-walled carbon nanotube composite material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of crystalline porous materials, in particular to a boron-doped MOF (Metal Organic Framework) derived carbon-coated multi-walled carbon nanotube composite material as well as a preparation method and application thereof. According to the preparation method of the boron-doped MOF-derived carbon-coated multi-walled carbon nanotube composite material, MET (Zn) is grown on the surface of a multi-walled carbon nanotube in situ, then a ZnO / C-coated multi-walled carbon nanotube is obtained through carbonization, and then the boron-doped MOF-derived carbon-coated multi-walled carbon nanotube composite material is obtained through boron doping treatment. The multi-walled carbon nanotubes anchor nano-particles during thermal decomposition of MET (Zn) and inhibit aggregation and coarsening of metal particles in the carbonization process, through boron doping treatment, part of B < 3 + > can replace metal ions in ZnO crystal lattices, high-valence metal ions are converted into low-valence metal ions, the adsorption capacity of the composite material is enhanced, and meanwhile, the adsorption capacity of the composite material is improved. Due to the introduction of boron, higher positive charge density is realized around carbon atoms, the charge transfer rate is increased, the adsorption time is shortened, the adsorption capacity per unit volume is improved, and high-efficiency adsorption of low-concentration toluene is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of crystalline porous materials, and in particular to a boron-doped MOF-derived carbon @ multi-walled carbon nanotube composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Volatile organic compounds (VOCs) are a class of pollutants widely present in industrial production and daily life. They not only pollute the environment but also pose a threat to human health. VOCs are important precursor substances causing environmental problems such as PM2.5 and photochemical smog. Therefore, VOCs emission reduction has become a hot issue in current air pollution control. At present, VOCs treatment technologies can be mainly divided into absorption method, adsorption method, combustion method, biodegradation method, plasma technology, etc. Among them, the adsorption method uses the physical and chemical interaction between the adsorption material and VOCs in the waste gas to achieve the enrichment and separation of VOCs, which is an efficient and economical method. After adsorption saturation, part of the organic matter can also be recovered by desorption condensation, realizing the resource utilization of waste, and it is the most widely used VOCs recovery and treatment technology in China.

[0003] The selection of the adsorption material is crucial for the adsorption effect of VOCs. Common adsorption materials include activated carbon, metal-organic frameworks (MOFs), hypercrosslinked polymer resins (HPR), and molecular sieves, etc. Among them, MOFs have advantages such as excellent adsorption performance and large adsorption capacity, and have been widely concerned by domestic and foreign scholars. Patent CN108751189A discloses a preparation method of an aluminum-based MOF porous carbon material with a high specific surface area. The carbon source is polymerized in the aluminum-based MOF material and then carbonized to prepare a composite material, which is applied to adsorb toluene, and the toluene adsorption capacity can reach 11.7 mmol·g -1 . Patent CN118371232A discloses a preparation method of a carbon nanotube charcoal composite material. The nitrogen-doped carbon nanotubes are mixed with a zinc nitrate solution and heated to obtain a carbon nanotube / MOF composite material, and then an electro-deposition method and tube furnace calcination are used to obtain a carbon nanotube charcoal composite adsorption material, which is applied to adsorb As(III), and the maximum adsorption capacity reaches 9.91 mg / g.

[0004] Existing published patents and literature have all reported that MOF materials can effectively adsorb VOCs, but it is difficult for existing MOF adsorption materials to effectively adsorb low-concentration pollutants in certain specific environments, such as chip manufacturing workshops, and the adsorption capacity is not very ideal. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material, its preparation method and application, so as to solve at least the problems of small adsorption capacity of existing MOF adsorption materials and difficulty in effectively adsorbing low-concentration pollutants in certain specific environments.

[0006] The present invention solves the above technical problems by the following technical means:

[0007] In the first aspect, an embodiment of the present application discloses a preparation method of a boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material, including the following steps:

[0008] Prepare MET(Zn)@multi-walled carbon nanotubes. Add the activated multi-walled carbon nanotubes into a mixed solution of ethylene glycol and ammonia water, then add ZnCl2, dissolve it by ultrasonic treatment, then add 1H-1,2,3-triazole, ultrasonically treat for 15-30 s, and place it at room temperature for 24-48 h. The obtained product is washed and dried with ethanol to obtain MET(Zn)@multi-walled carbon nanotubes;

[0009] Prepare ZnO / C@multi-walled carbon nanotubes. Place MET(Zn)@multi-walled carbon nanotubes in a tube furnace, heat it to 500-600 °C at a heating rate of 5-10 °C / min, and calcine it in an inert atmosphere for 2-4 h to obtain ZnO / C@multi-walled carbon nanotubes;

[0010] Prepare the composite material. Dissolve boric acid in deionized water to obtain a boric acid solution, then disperse ZnO / C@multi-walled carbon nanotubes in the boric acid solution, stir, wash and dry. Subsequently, under a nitrogen atmosphere, heat it to 400-500 °C at a heating rate of 5-10 °C / min and calcine it for 2-4 h to obtain a boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material.

[0011] In some embodiments, the activation treatment of the multi-walled carbon nanotubes is as follows:

[0012] Weigh KOH and add it to deionized water and stir to dissolve to obtain a KOH solution;

[0013] Place the multi-walled carbon nanotubes in a vacuum at 80-100 °C for 8-12 h, then add them to the KOH solution, stir at room temperature for 4-6 h, wash and filter 3-5 times, dry, and under a nitrogen atmosphere, heat it to 400-600 °C at a heating rate of 5-10 °C / min and calcine it for 2-4 h to obtain activated multi-walled carbon nanotubes.

[0014] In some embodiments, the mass ratio of the multi-walled carbon nanotubes, KOH and deionized water is 1:(2-4):(40-60).

[0015] In some embodiments, in the step of preparing MET(Zn)@multi-walled carbon nanotubes, the mass ratio of ZnCl2, multi-walled carbon nanotubes, ethylene glycol, ammonia water, and 1H-1,2,3-triazole is 1:(3-5):(35-45):(0.5-1):(1.5-2).

[0016] In some embodiments, in the step of preparing MET(Zn)@multi-walled carbon nanotubes, the ethanol washing and drying is to wash with ethanol 3-6 times and dry at 60-80 °C for 12-24 h.

[0017] In some embodiments, in the step of preparing the composite material, the mass ratio of ZnO / C@multi-walled carbon nanotubes, boric acid, and deionized water is 1:(2-4):(30-50).

[0018] In some embodiments, in the step of preparing the composite material, the stirring, washing, and drying are specifically to stir at 60-80 °C for 4-6 h, centrifuge and wash with deionized water 3-5 times, and then dry at 80-100 °C for 8-12 h.

[0019] In a second aspect, the embodiments of the present application disclose a boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material, which is prepared by using the preparation method described in the first aspect above.

[0020] In a third aspect, the embodiments of the present application disclose the application of the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material described in the second aspect above in adsorbing toluene gas.

[0021] In some embodiments, the composite material is used to adsorb low-concentration toluene gas, and the concentration of the low-concentration toluene gas is ≤ 5 ppm.

[0022] In the preparation method of the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material of the present invention, MET(Zn) is first in-situ grown on the surface of multi-walled carbon nanotubes, and then carbonized to obtain ZnO / C@multi-walled carbon nanotubes, and then boron-doped treatment is carried out to obtain a boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material. Multi-walled carbon nanotubes can anchor nanoparticles during the thermal decomposition of MET(Zn), inhibiting the aggregation and coarsening of metal particles during carbonization. After boron-doped treatment, part of B 3+ can replace metal ions in the ZnO lattice, and the high-valence metal ions are transformed into low-valence states, strengthening the adsorption capacity of the composite material. At the same time, the introduction of boron will result in a higher positive charge density around carbon atoms, improving the charge transfer rate, shortening the adsorption time, increasing the adsorption capacity per unit volume, and also enabling efficient adsorption of low-concentration toluene.

[0023] The boron-doped MOF-derived carbon@multi-walled carbon nanotube composite of the present invention has excellent toluene adsorption performance. The maximum toluene adsorption capacity can reach 238 mg / g. After 5 cycles of adsorption, its toluene adsorption performance is still excellent. The toluene adsorption capacity only decays from the initial 238 mg / g to 233 mg / g, and can maintain 97% of the initial toluene adsorption capacity, showing good renewable performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the toluene adsorption capacity diagram of the composites prepared in Examples 1-3 and Comparative Examples 1-2;

[0025] Figure 2 is the toluene cyclic adsorption capacity diagram of the composites prepared in Example 3 and Comparative Example 2;

[0026] Figure 3 is the structural schematic diagram of the chemical filter adsorption device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0028] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0029] In the preparation method of the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite of the present application, MET(Zn) is first in-situ grown on the surface of the multi-walled carbon nanotubes, and then carbonized to obtain ZnO / C@multi-walled carbon nanotubes, and then boron-doped treatment is carried out to obtain the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite. The multi-walled carbon nanotubes can anchor nanoparticles during the thermal decomposition of MET(Zn), inhibiting the aggregation and coarsening of metal particles during the carbonization process. After boron-doped treatment, part of B 3+Metal ions in the ZnO lattice can be replaced, and the high-valence metal ions are transformed into low-valence metal ions, strengthening the adsorption capacity of the composite material. At the same time, the introduction of boron will result in a higher positive charge density around the carbon atoms, improving the charge transfer rate, shortening the adsorption time, increasing the adsorption capacity per unit volume, and also enabling the efficient adsorption of low-concentration toluene.

[0030] Specifically, the preparation method of the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material of the present application is as follows:

[0031] (1) Activate multi-walled carbon nanotubes

[0032] Weigh KOH and add it to deionized water and stir to dissolve to obtain a KOH solution; after placing the multi-walled carbon nanotubes in a vacuum at 80-100 °C for 8-12 h, add them to the KOH solution, stir at room temperature for 4-6 h, wash and filter 3-5 times, dry, and under a nitrogen atmosphere, raise the temperature to 400-600 °C at a heating rate of 5-10 °C / min and calcine for 2-4 h to obtain the activated multi-walled carbon nanotubes. In this step, the mass ratio of multi-walled carbon nanotubes, KOH, and deionized water is 1:(2-4):(40-60).

[0033] (2) Prepare MET(Zn)@multi-walled carbon nanotubes

[0034] Add the activated multi-walled carbon nanotubes to a mixed solution of ethylene glycol and ammonia water, then add ZnCl2, dissolve it by ultrasonic treatment, then add 1H-1,2,3-triazole, perform ultrasonic treatment for 15-30 s, and leave it at room temperature for 24-48 h. The obtained product is washed 3-6 times with ethanol and dried at 60-80 °C for 12-24 h to obtain MET(Zn)@multi-walled carbon nanotubes. In this step, the mass ratio of ZnCl2, multi-walled carbon nanotubes, ethylene glycol, ammonia water, and 1H-1,2,3-triazole is 1:(3-5):(35-45):(0.5-1):(1.5-2), and the ammonia content of the ammonia water is 28%.

[0035] (3) Prepare ZnO / C@multi-walled carbon nanotubes

[0036] Place MET(Zn)@multi-walled carbon nanotubes in a tube furnace, raise the temperature to 500-600 °C at a heating rate of 5-10 °C / min, and calcine for 2-4 h under an inert atmosphere to obtain ZnO / C@multi-walled carbon nanotubes.

[0037] (4) Prepare the composite material

[0038] Dissolve boric acid in deionized water to obtain a boric acid solution. Then disperse ZnO / C@multi-walled carbon nanotubes in the boric acid solution, stir at 60 - 80 °C for 4 - 6 h, wash by centrifugation with deionized water 3 - 5 times, dry at 80 - 100 °C for 8 - 12 h, and then, under a nitrogen atmosphere, heat to 400 - 500 °C at a heating rate of 5 - 10 °C / min and calcine for 2 - 4 h to obtain boron-doped MOF-derived carbon@multi-walled carbon nanotube composite. In this step, the mass ratio of ZnO / C@multi-walled carbon nanotubes, boric acid, and deionized water is 1:(2 - 4):(30 - 50).

[0039] To better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0040] Example 1

[0041] The preparation method of the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite in this example is as follows:

[0042] (1) Activate multi-walled carbon nanotubes

[0043] Weigh 40 g of KOH and add it to 600 g of deionized water, stir to dissolve to obtain a KOH solution; after placing multi-walled carbon nanotubes in a vacuum at 100 °C for 12 h, weigh 10 g of the dried multi-walled carbon nanotubes and add them to the KOH solution, stir at room temperature for 6 h, wash and filter 5 times, dry at 80 °C for 12 h, and under a nitrogen atmosphere, heat to 600 °C at a heating rate of 10 °C / min and calcine for 4 h to obtain activated multi-walled carbon nanotubes.

[0044] (2) Prepare MET(Zn)@multi-walled carbon nanotubes

[0045] Weigh 5 g of activated multi-walled carbon nanotubes and add them to a mixed solution of 45 g of ethylene glycol and 1 g of ammonia water, then add 1 g of ZnCl2, dissolve by ultrasonic treatment, then add 2 g of 1H-1,2,3-triazole, perform ultrasonic treatment for 30 s, and leave at room temperature for 48 h. Wash the obtained product 6 times with ethanol and dry at 80 °C for 12 h to obtain MET(Zn)@multi-walled carbon nanotubes.

[0046] (3) Prepare ZnO / C@multi-walled carbon nanotubes

[0047] Place MET(Zn)@multi-walled carbon nanotubes in a tube furnace, heat to 600 °C at a heating rate of 10 °C / min, and calcine for 4 h under an inert atmosphere to obtain ZnO / C@multi-walled carbon nanotubes.

[0048] (4) Prepare the composite material

[0049] Weigh 8 g of boric acid and dissolve it in 100 g of deionized water to obtain a boric acid solution. Then weigh 2 g of ZnO / C@multi-walled carbon nanotubes and disperse them in the boric acid solution. Stir at 80 °C for 6 h, centrifuge and wash with deionized water 5 times, then dry at 100 °C for 12 h. Subsequently, under a nitrogen atmosphere, heat it to 500 °C at a heating rate of 10 °C / min and calcine for 4 h to obtain a boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material.

[0050] Example 2

[0051] The preparation method of the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material in this example is as follows:

[0052] (1) Activate multi-walled carbon nanotubes

[0053] Weigh 20 g of KOH and add it to 400 g of deionized water, stir and dissolve to obtain a KOH solution; place the multi-walled carbon nanotubes in a vacuum drying oven at 80 °C for 8 h. Then weigh 10 g of the dried multi-walled carbon nanotubes and add them to the KOH solution, stir at room temperature for 4 h, wash and filter 3 times, dry at 60 °C for 8 h, and under a nitrogen atmosphere, heat it to 400 °C at a heating rate of 5 °C / min and calcine for 2 h to obtain activated multi-walled carbon nanotubes.

[0054] (2) Prepare MET(Zn)@multi-walled carbon nanotubes

[0055] Weigh 3 g of activated multi-walled carbon nanotubes and add them to a mixed solution of 35 g of ethylene glycol and 0.5 g of ammonia water. Then add 1 g of ZnCl2, dissolve it by ultrasonic treatment, add 1.5 g of 1H-1,2,3-triazole, perform ultrasonic treatment for 15 s, and let it stand at room temperature for 24 h. Wash the obtained product 3 times with ethanol and dry at 60 °C for 24 h to obtain MET(Zn)@multi-walled carbon nanotubes.

[0056] (3) Prepare ZnO / C@multi-walled carbon nanotubes

[0057] Place MET(Zn)@multi-walled carbon nanotubes in a tube furnace, heat it to 500 °C at a heating rate of 5 °C / min, and calcine for 2 h under an inert atmosphere to obtain ZnO / C@multi-walled carbon nanotubes.

[0058] (4) Prepare the composite material

[0059] Weigh 4 g of boric acid and dissolve it in 60 g of deionized water to obtain a boric acid solution. Then weigh 2 g of ZnO / C@multi-walled carbon nanotubes and disperse them in the boric acid solution. Stir at 60 °C for 4 h, centrifuge and wash with deionized water 3 times, then dry at 80 °C for 8 h. Subsequently, under a nitrogen atmosphere, heat it to 400 °C at a heating rate of 5 °C / min and calcine for 2 h to obtain a boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material.

[0060] Example 3

[0061] The preparation method of the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite in this example is as follows:

[0062] (1) Activate multi-walled carbon nanotubes

[0063] Weigh 30 g of KOH and add it to 500 g of deionized water, stir and dissolve to obtain a KOH solution; after placing the multi-walled carbon nanotubes in a vacuum drying oven at 90 °C for 10 h, weigh 10 g of the dried multi-walled carbon nanotubes and add them to the KOH solution, stir at room temperature for 5 h, wash and filter 4 times, dry at 75 °C for 12 h, and under a nitrogen atmosphere, heat up to 500 °C at a heating rate of 8 °C / min and calcine for 3 h to obtain the activated multi-walled carbon nanotubes.

[0064] (2) Prepare MET(Zn)@multi-walled carbon nanotubes

[0065] Weigh 4 g of the activated multi-walled carbon nanotubes and add them to a mixed solution of 40 g of ethylene glycol and 0.8 g of ammonia water, then add 1 g of ZnCl2, dissolve by ultrasonic treatment, then add 1.6 g of 1H-1,2,3-triazole, perform ultrasonic treatment for 20 s, and leave it at room temperature for 30 h. Wash the obtained product 4 times with ethanol and dry at 75 °C for 20 h to obtain MET(Zn)@multi-walled carbon nanotubes.

[0066] (3) Prepare ZnO / C@multi-walled carbon nanotubes

[0067] Place the MET(Zn)@multi-walled carbon nanotubes in a tube furnace, heat up to 500 °C at a heating rate of 8 °C / min, and calcine for 3 h under an inert atmosphere to obtain ZnO / C@multi-walled carbon nanotubes.

[0068] (4) Prepare the composite material

[0069] Weigh 6 g of boric acid and dissolve it in 66 g of deionized water to obtain a boric acid solution. Then weigh 2 g of ZnO / C@multi-walled carbon nanotubes and disperse them in the boric acid solution, stir at 70 °C for 5 h, centrifuge and wash 4 times with deionized water, then dry at 90 °C for 10 h. Subsequently, under a nitrogen atmosphere, heat up to 450 °C at a heating rate of 8 °C / min and calcine for 3 h to obtain the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite.

[0070] Example 4

[0071] The preparation method of the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite in this example is as follows:

[0072] (1) Activate multi-walled carbon nanotubes

[0073] Weigh 30 g of KOH and add it to 500 g of deionized water, stir to dissolve to obtain a KOH solution; place the multi-walled carbon nanotubes in a vacuum at 85 °C for 12 h, then weigh 10 g of the dried multi-walled carbon nanotubes and add them to the KOH solution, stir at room temperature for 6 h, wash and filter 5 times, dry at 80 °C for 12 h, and in a nitrogen atmosphere, heat to 500 °C at a heating rate of 10 °C / min and calcine for 3 h to obtain the activated multi-walled carbon nanotubes.

[0074] (2) Preparation of MET(Zn)@multi-walled carbon nanotubes

[0075] Weigh 5 g of the activated multi-walled carbon nanotubes and add them to a mixed solution of 45 g of ethylene glycol and 1 g of ammonia water, then add 1 g of ZnCl2, dissolve by ultrasonic treatment, then add 1.6 g of 1H-1,2,3-triazole, ultrasonically treat for 25 s, leave at room temperature for 40 h, wash the obtained product 5 times with ethanol, and dry at 75 °C for 20 h to obtain MET(Zn)@multi-walled carbon nanotubes.

[0076] (3) Preparation of ZnO / C@multi-walled carbon nanotubes

[0077] Place the MET(Zn)@multi-walled carbon nanotubes in a tube furnace, heat to 500 °C at a heating rate of 10 °C / min, and calcine for 3 h in an inert atmosphere to obtain ZnO / C@multi-walled carbon nanotubes.

[0078] (4) Preparation of the composite material

[0079] Weigh 3 g of boric acid and dissolve it in 40 g of deionized water to obtain a boric acid solution, then weigh 1 g of ZnO / C@multi-walled carbon nanotubes and disperse them in the boric acid solution, stir at 70 °C for 5 h, centrifuge and wash 4 times with deionized water, then dry at 90 °C for 10 h, and then in a nitrogen atmosphere, heat to 500 °C at a heating rate of 10 °C / min and calcine for 3 h to obtain the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material.

[0080] Comparative Example 1

[0081] The composite material of this comparative example was not carbonized, and its preparation method is as follows:

[0082] (1) Activation of multi-walled carbon nanotubes

[0083] Weigh 40 g of KOH and add it to 600 g of deionized water, stir to dissolve to obtain a KOH solution; place the multi-walled carbon nanotubes in a vacuum at 100 °C for 12 h, then weigh 10 g of the dried multi-walled carbon nanotubes and add them to the KOH solution, stir at room temperature for 6 h, wash and filter 5 times, dry at 80 °C for 12 h, and in a nitrogen atmosphere, heat to 600 °C at a heating rate of 10 °C / min and calcine for 4 h to obtain the activated multi-walled carbon nanotubes.

[0084] (2) Preparation of MET(Zn)@Multi-walled Carbon Nanotubes

[0085] Weigh 5 g of activated multi-walled carbon nanotubes and add them to a mixed solution of 45 g of ethylene glycol and 1 g of ammonia water. Then add 1 g of ZnCl2 and dissolve it by ultrasonic treatment. Next, add 2 g of 1H-1,2,3-triazole and perform ultrasonic treatment for 30 s. Leave it at room temperature for 48 h. Wash the obtained product 6 times with ethanol and dry it at 80 °C for 12 h to obtain MET(Zn)@multi-walled carbon nanotubes.

[0086] (3) Preparation of Composite Material

[0087] Weigh 8 g of boric acid and dissolve it in 100 g of deionized water to obtain a boric acid solution. Then weigh 2 g of MET(Zn)@multi-walled carbon nanotubes and disperse them in the boric acid solution. Stir at 80 °C for 6 h. After centrifugally washing 5 times with deionized water, dry it at 100 °C for 12 h. Subsequently, under a nitrogen atmosphere, heat it to 500 °C at a heating rate of 10 °C / min and calcine for 4 h to obtain a boron-doped MOF@multi-walled carbon nanotube composite material.

[0088] Comparative Example 2

[0089] The composite material in this comparative example is not doped with boron, and its preparation method is as follows:

[0090] (1) Activation of Multi-walled Carbon Nanotubes

[0091] Weigh 40 g of KOH and dissolve it by stirring in 600 g of deionized water to obtain a KOH solution; after placing the multi-walled carbon nanotubes in a vacuum drying oven at 100 °C for 12 h, weigh 10 g of the dried multi-walled carbon nanotubes and add them to the KOH solution. Stir at room temperature for 6 h, wash and filter 5 times, dry at 80 °C for 12 h, and under a nitrogen atmosphere, heat it to 600 °C at a heating rate of 10 °C / min and calcine for 4 h to obtain activated multi-walled carbon nanotubes.

[0092] (2) Preparation of MET(Zn)@Multi-walled Carbon Nanotubes

[0093] Weigh 5 g of activated multi-walled carbon nanotubes and add them to a mixed solution of 45 g of ethylene glycol and 1 g of ammonia water. Then add 1 g of ZnCl2 and dissolve it by ultrasonic treatment. Next, add 2 g of 1H-1,2,3-triazole and perform ultrasonic treatment for 30 s. Leave it at room temperature for 48 h. Wash the obtained product 6 times with ethanol and dry it at 80 °C for 12 h to obtain MET(Zn)@multi-walled carbon nanotubes.

[0094] (3) Preparation of ZnO / C@Multi-walled Carbon Nanotubes

[0095] Place the MET(Zn)@multi-walled carbon nanotubes in a tube furnace, heat it to 600 °C at a heating rate of 10 °C / min, and calcine for 4 h under an inert atmosphere to obtain ZnO / C@multi-walled carbon nanotubes.

[0096] (4) Preparation of composite material

[0097] Place ZnO / C@multi-walled carbon nanotubes in a tubular furnace. Under a nitrogen atmosphere, heat it to 500 °C at a heating rate of 10 °C / min and calcine for 4 h to obtain a MOF-derived carbon@multi-walled carbon nanotube composite material.

[0098] Use the composite materials prepared in Examples 1-4 and Comparative Examples 1-2 as samples for toluene gas adsorption tests. Specifically, use a chemical filter adsorption device (please refer to Figure 3 ) to conduct toluene gas adsorption tests on the materials. First, load the test filter on the filter mesh in the quartz tube, then turn on the fan and control the flow rate with a mass flow meter, and finally conduct the filter test. Test conditions: control the toluene test concentration (5 ppm), test flow rate (10 L / min), test resistance (<80 Pa). The test results are shown in Table 1 and Figure 1-2 .

[0099] Name Weight (g) Air volume (L / min) Resistance (Pa) Initial efficiency (%) Adsorption capacity (mg / g) Example 1 2 11 48 97.9 203 Example 2 2 11 52 96.5 215 Example 3 2 11 58 98.8 238 Example 4 2 11 50 98.4 229 Comparative example 1 2 11 46 83.7 77 Comparative example 2 2 11 50 77.5 85

[0100] Table 1

[0101] The data in Table 1 show that the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material of the present invention has excellent toluene adsorption performance, and the maximum toluene adsorption capacity can reach 238 mg / g. Compared with the uncarbonized and unboron-doped samples, the adsorption performance of the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material has been significantly improved. The carbonized material has a stronger electrostatic adsorption force and stronger adsorption of toluene. The introduction of boron changes the surrounding charge density and electronic state, shortens the adsorption time, improves the adsorption capacity per unit volume, and can achieve the adsorption of low-concentration toluene gas.

[0102] Figure 1 is the toluene adsorption capacity diagram of the composite materials prepared in Examples 1-3 and Comparative Examples 1-2. Figure 1 The data show that the composite material prepared in Example 3 has the fastest toluene adsorption rate and the largest adsorption capacity, reaching adsorption saturation at about 450 min.

[0103] Figure 2 is the toluene cyclic adsorption capacity diagram of the composite materials prepared in Example 3 and Comparative Example 2. Figure 2The data shows that after 5 cycles of adsorption, the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite still has excellent toluene adsorption performance. The toluene adsorption capacity only decays from the initial 238 mg / g to 233 mg / g, and can maintain 97% of the initial toluene adsorption capacity, showing good renewable performance. However, for the sample without boron doping, the performance decreases significantly after 5 cycles of adsorption. The toluene adsorption capacity decays from the initial 85 mg / g to 16 mg / g, only 18% of the initial toluene adsorption capacity, indicating that boron doping can improve the stability of the material.

[0104] In summary, the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite of the present invention has excellent toluene adsorption performance and can be used to adsorb toluene gas, especially low-concentration toluene gas with a concentration ≤ 5 ppm.

[0105] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention. The technologies, shapes, and structures not described in detail in the present invention are all well-known technologies.

Claims

1. Preparation method of boron-doped MOF-derived carbon @ multi-walled carbon nanotube composite material, characterized in that, It includes the following steps: Prepare MET(Zn)@multi-walled carbon nanotubes. Add the activated multi-walled carbon nanotubes into a mixed solution of ethylene glycol and ammonia water, then add ZnCl2, ultrasonically dissolve it, then add 1H-1,2,3-triazole, ultrasonically treat for 15 - 30 s, place it at room temperature for 24 - 48 h, and wash and dry the obtained product with ethanol to obtain MET(Zn)@multi-walled carbon nanotubes; Prepare ZnO / C@multi-walled carbon nanotubes. Place MET(Zn)@multi-walled carbon nanotubes in a tube furnace, heat it to 500 - 600 °C at a heating rate of 5 - 10 °C / min, and calcine it for 2 - 4 h under an inert atmosphere to obtain ZnO / C@multi-walled carbon nanotubes; Prepare the composite material. Dissolve boric acid in deionized water to obtain a boric acid solution, then disperse ZnO / C@multi-walled carbon nanotubes in the boric acid solution, stir, wash and dry it, and then under a nitrogen atmosphere, heat it to 400 - 500 °C at a heating rate of 5 - 10 °C / min and calcine it for 2 - 4 h to obtain a boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material.

2. The preparation method of the boron-doped MOF-derived carbon @ multi-walled carbon nanotube composite material according to claim 1, characterized in that, The activation treatment of the multi-walled carbon nanotubes is as follows: Weigh KOH and add it to deionized water and stir to dissolve to obtain a KOH solution; Place the multi-walled carbon nanotubes in a vacuum at 80 - 100 °C for 8 - 12 h, then add them to the KOH solution, stir at room temperature for 4 - 6 h, wash and filter 3 - 5 times, dry, and under a nitrogen atmosphere, heat it to 400 - 600 °C at a heating rate of 5 - 10 °C / min and calcine it for 2 - 4 h to obtain the activated multi-walled carbon nanotubes.

3. The preparation method of the boron-doped MOF-derived carbon @ multi-walled carbon nanotube composite material according to claim 2, wherein The mass ratio of the multi-walled carbon nanotubes to KOH is 1:(2 - 4).

4. The preparation method of the boron-doped MOF-derived carbon @ multi-walled carbon nanotube composite according to claim 1, characterized in that, In the step of preparing MET(Zn)@multi-walled carbon nanotubes, the mass ratio of ZnCl2, multi-walled carbon nanotubes, ethylene glycol, ammonia water and 1H-1,2,3-triazole is 1:(3 - 5):(35 - 45):(0.5 - 1):(1.5 - 2).

5. The preparation method of the boron-doped MOF-derived carbon @ multi-walled carbon nanotube composite according to claim 1, characterized in that, In the step of preparing MET(Zn)@multi-walled carbon nanotubes, the ethanol washing and drying is to wash with ethanol 3 - 6 times and dry at 60 - 80 °C for 12 - 24 h.

6. The preparation method of the boron-doped MOF-derived carbon @ multi-walled carbon nanotube composite according to claim 1, characterized in that, In the step of preparing the composite material, the mass ratio of ZnO / C@multi-walled carbon nanotubes to boric acid is 1:(2 - 4).

7. The preparation method of the boron-doped MOF-derived carbon @ multi-walled carbon nanotube composite material according to claim 1, characterized in that, In the step of preparing the composite material, the stirring, washing and drying specifically means stirring at 60 - 80 °C for 4 - 6 h, centrifugally washing with deionized water 3 - 5 times, and then drying at 80 - 100 °C for 8 - 12 h.

8. Boron-doped MOF-derived carbon @ multi-walled carbon nanotube composite material, characterized in that, The composite material is prepared by the preparation method described in any one of claims 1 - 7.

9. Use of the boron-doped MOF-derived carbon@multi-walled carbon nanotube composite material according to claim 8 in adsorbing toluene gas.

10. The application according to claim 9, wherein The composite material is used to adsorb low-concentration toluene gas, and the concentration of the low-concentration toluene gas ≤ 5 ppm.

Images