CN113083345A - Preparation method of nitrogen-doped carbon-based material catalyst containing defect active sites - Google Patents
Preparation method of nitrogen-doped carbon-based material catalyst containing defect active sites Download PDFInfo
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- CN113083345A CN113083345A CN202110339087.5A CN202110339087A CN113083345A CN 113083345 A CN113083345 A CN 113083345A CN 202110339087 A CN202110339087 A CN 202110339087A CN 113083345 A CN113083345 A CN 113083345A
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- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/24—Nitrogen compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/722—Oxidation by peroxides
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/34—Organic compounds containing oxygen
- C02F2101/345—Phenols
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2305/00—Use of specific compounds during water treatment
- C02F2305/02—Specific form of oxidant
- C02F2305/026—Fenton's reagent
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Abstract
The invention discloses a preparation method of a nitrogen-doped carbon-based material catalyst containing defect active sites, and relates to the field of nano-material heterogeneous catalysis. The method comprises the following steps: placing a carbon material in a round-bottom flask, and adding deionized water and concentrated nitric acid to obtain a mixed system. And placing the mixed system in an ultrasonic cleaner for ultrasonic treatment, fully mixing, condensing and refluxing, performing reduced pressure evaporation and drying on a rotary evaporator, performing high-temperature calcination and ammoniation in a tubular furnace, and finally obtaining the nitrogen-doped carbon-based material catalyst containing the defect active sites. The invention provides a preparation method of a nitrogen-doped carbon-based material catalyst containing a defect active site, and the catalyst is applied to a reaction system for activating and degrading a phenolic compound by persulfate. The method provided by the invention has the advantages of low cost and excellent catalyst performance, provides a new idea for the development of advanced oxidation technology, and provides a disposal method which is easy to realize, advanced in technology and clear in mechanism for refractory wastewater.
Description
The technical field is as follows:
the invention relates to the field of catalytic materials and environmental application, in particular to a preparation method of a nitrogen-doped carbon-based material catalyst containing defect active sites.
Background art:
phenolic substances as common chemical raw materials and intermediates widely exist in wastewater, and effective treatment of phenol-containing sewage is a difficult task which is inexorable in water environment work in China. Therefore, the development of a novel, efficient and economic process for degrading phenolic substances has great significance for human health and natural environment.
The traditional treatment method for the refractory wastewater at home and abroad mainly comprises a biological method, a physical and chemical method and an oxidation method. In the process of research, Advanced Oxidation Processes (AOPs) have been developed and have significant advantages. In recent years, based on sulfate radicals●SO4 -Due to the fact that the novel heterogeneous Fenton-like system has the function of reacting with hydroxyl free radicals●The OH system has similar oxidation capacity and has the advantages of wide pH application range, long half-life period, good selectivity and the like which are not possessed by the traditional Fenton system, thereby receiving wide attention.
Persulfate has various activation modes, including thermal activation, ultraviolet light activation, transition metal activation, alkali activation, carbon-based composite material activation, ultrasonic activation and the like. The problem of low cost performance generally exists in an activation mode of external energy, the catalytic efficiency is not obvious, but the energy consumption is huge. The metal-based catalyst has the defects of resource scarcity, high cost, biological toxicity of leached metal and the like. The carbon-based material is used as a non-Metal-carbon catalyst (MFCMs) capable of replacing transition Metal oxides to promote the activation of persulfate through the synergistic action of adsorption and catalysis, and oxygen-containing functional groups on the surface, the content of chemical substances and the microscopic morphology of the carbon-based material are not obviously changed after repeated regeneration, so that the long-term effective adsorption capacity of the carbon-based material can be ensured, and the carbon-based material has excellent stability and reusability. The invention takes carbon black and biochar as carbon-based materials, has wide sources and low cost, and is easy to modify.
In order to further improve the performance of the MFCMs, it is necessary to properly tailor them, focusing on improving their electron donating and transferring abilities, and there are generally four modification methods: (1) introducing defects; (2) doping of hetero atoms; (3) adjusting carbon configuration; (4) the pore structure and the surface functional group are regulated and controlled. The defect introduction can distort and hybridize the electronic state distribution, which can increase more active sites, while the heteroatom doping introduces different kinds and catalytic heteroatoms (N, S, B, P, etc.), which can effectively change the structure and properties of the carbon material by increasing the defect edge of the carbon material, improving the electron mobility and electron density. This patent uses both of the above modifications.
The invention discloses a preparation method of a nitrogen-doped carbon-based material catalyst containing a defect active site, which is invented by adopting carbon-based materials such as carbon black, active carbon or biochar as a loading template to prepare the nitrogen-doped carbon-based material catalyst containing the defect active site, and adopting a method of calcining and ammonia activation to successfully introduce defects and dope heteroatoms in simple steps and simultaneously apply the defects and the heteroatoms to catalyst modification.
Disclosure of Invention
The invention aims to provide a preparation method of a nitrogen-doped carbon-based material catalyst containing a defect active site, and the catalyst is applied to a reaction system for activating and degrading a phenolic compound by persulfate. The carbon-based catalyst synthesized by the method has low cost and excellent performance, and can catalyze the persulfate advanced oxidation reaction to carry out so as to efficiently degrade pollutants. Provides a good material base and a modification method for the application of the Fenton-like catalytic reaction in the aspect of wastewater treatment.
1. The invention realizes the aim through the following technical scheme: a preparation method of a nitrogen-doped carbon-based material catalyst containing defect active sites comprises the following specific steps:
1) placing a certain carbon material in a round-bottom flask, and adding deionized water and concentrated nitric acid.
2) Placing the mixed system in the step 1) in an ultrasonic cleaner for ultrasonic treatment, and carrying out condensation reflux for 0.5-4 h at 50-100 ℃.
3) Rotary evaporating the mixed liquid in the step 2), and drying in an air drying oven at the temperature of 60-80 ℃.
4) Grinding the sample obtained in the step 3), uniformly dispersing the ground sample into a vessel, calcining the sample in a nitrogen atmosphere, heating the sample to 700-1000 ℃, and then ammoniating the sample in an ammonia atmosphere to obtain the nitrogen-doped carbon-based material catalyst NC containing the defect active site.
2. In the step 1), the concentration of the nitric acid is 2-8 mol L-1The carbon material may be carbon black, activated carbon or biochar, and the mixed liquid is 10-50 mL.
3. In the step 2), the temperature of the ultrasonic cleaning instrument is 10-30 ℃, and the cleaning time is 2-10 min.
4. In the step 3), the temperature of the rotary steaming water bath is 40-80 ℃, and the drying time is 2-3 h; the air blast drying time is 12-24 h.
5. In the step 4), the heating rate is 2-10 ℃/min, the ammoniation temperature is preferably 800-1000 ℃, and the ammoniation time is 15-90 min.
The preparation method of the nitrogen-doped carbon-based material catalyst containing the defect active sites successfully introduces defects and dopes heteroatoms in simple steps and simultaneously applies the defects and the heteroatoms to the modification of the carbon-based catalyst, so that the activation efficiency of persulfate is remarkably improved, a heterogeneous Fenton-like method based on persulfate is further explored, and the material synthesis method is enriched.
Drawings
FIG. 1 is a graph of the pore size distribution of a nitrogen doped carbon based material catalyst NC/BP2000 with defect active sites of example 1;
fig. 2 is a transmission electron microscope and element distribution diagram of a high-angle annular dark field scanning transmission electron microscope and a high-angle annular dark field scanning transmission electron microscope of a nitrogen-doped carbon-based material catalyst containing defect active sites in example 1, and the proportions are as follows: 200 nm.
FIG. 3 is an ESR plot of one of the defect-active-site containing nitrogen-doped carbon-based material catalysts NC/BP2000 of example 1;
FIG. 4 is a graph showing the properties of Phenol (Phenol) degradation in example 3;
fig. 5 is an abstract drawing, and is a TEM image of the nitrogen-doped carbon-based material catalyst NC/BP 2000.
Detailed Description
The following examples are further illustrative of the present invention and are not intended to be limiting, but are illustrative of a nitrogen doped carbon based material catalyst containing defective active sites, NC/BP 2000.
Example 1: preparation of nitrogen-doped carbon-based material catalyst NC/BP2000 containing defect active sites
1) 1g BP2000 was placed in a round bottom flask and 18mL deionized water and 12mL 6mol L were added-1Concentrated nitric acid of (2). Prepare 30mL system.
2) Placing the mixed system in the step 1) in an ultrasonic cleaner for ultrasonic treatment for 5min at the ultrasonic temperature of 25 ℃, and then carrying out condensation reflux for 2h at the temperature of 80 ℃.
3) And (3) carrying out rotary evaporation on the mixed solution in the step 2) in a water bath at 60 ℃ for 2h, and drying in an air drying oven at 80 ℃ for 18 h.
4) Grinding the sample in 3), uniformly dispersing the ground sample in a dish, and adding the ground sample in N2Calcining in atmosphere at a heating rate of 5 deg.C for min-1Increasing the temperature to 1000 ℃ and then adding NH3And (3) ammoniating in the atmosphere, wherein the ammoniating temperature is 1000 ℃, and the ammoniating time is 60min, so that the nitrogen-doped carbon-based material catalyst NC/BP2000 containing the defect active sites is obtained.
A nitrogen doped carbon based material catalyst containing defective active sites NC/BP2000 prepared in example 1.
Example 2: preparation of nitrogen-doped carbon-based material catalyst NC/AC containing defect active sites
1) 1g of activated carbon was placed in a round bottom flask, 18mL of deionized water and 12mL of 6mol L were added-1Concentrated nitric acid of (2). Prepare 30mL system.
2) Placing the mixed system in the step 1) in an ultrasonic cleaner for ultrasonic treatment for 8min at the ultrasonic temperature of 25 ℃, and then carrying out condensation reflux for 2h at the temperature of 70 ℃.
3) And (3) carrying out rotary evaporation on the mixed solution in the step (2) in a water bath at 60 ℃ for 2h, and drying in an air drying oven at 80 ℃ for 24 h.
4) Grinding the sample in 3), uniformly dispersing the ground sample in a dish, and adding the ground sample in N2Calcining in atmosphere at a heating rate of 5 deg.C for min-1Heating to 900 ℃ and then adding NH3And (3) ammoniating in the atmosphere, wherein the ammoniating temperature is 900 ℃, and the ammoniating time is 75min, so that the nitrogen-doped carbon-based material catalyst NC/AC containing the defect active sites is obtained. Other different catalytic materials can be obtained by changing the carbon material, the reflux temperature, the ammoniation time and the ammoniation temperature.
A nitrogen doped carbon based material catalyst NC/AC containing defective active sites prepared in example 2.
Example 3: NC/BP2000 catalyst activated persulfate to degrade phenolic compounds
In order to examine the degradation effect of NC/BP2000 on phenolic compounds, representative Phenol (Phenol) is selected as a target organic matter. Preparing 10mmol L with deionized water-1Phenol stock solution of (5), 30mmol L-1Potassium hydrogen Persulfate (PMS) stock solution and 0.2mol L-1Boric acid/borax buffer (pH 7.2); quantitatively adding 10mL of Phenol stock solution, 10mL of PMS stock solution, 25mL of buffer solution and 55mL of deionized water according to 100mL of a system, wherein the Phenol and the PMS are respectively placed before the reaction is started, respectively adjusting the pH value of the reaction system to 7.2, and controlling the temperature of the reaction system; adding 0.01g of catalyst to be detected into Phenol part of the reaction system, quickly pouring PMS part into the Phenol part for mixing, starting timing, placing the reaction device (conical flask) into a constant-temperature shaking table, sampling at intervals, and adding 0.1mol L of catalyst into the sample-1The reaction is stopped by sodium thiosulfate solution, and after the solution is filtered to a liquid phase sampling bottle by an MCE disposable syringe filter with the aperture of 0.45um, the concentration of Phenol is detected by high performance liquid chromatography. The results are shown in FIG. 4.
Claims (5)
1. A preparation method of a nitrogen-doped carbon-based material catalyst containing defect active sites is characterized by comprising the following steps:
1) placing a certain carbon material in a round-bottom flask, and adding deionized water and concentrated nitric acid.
2) Placing the mixed system in the step 1) in an ultrasonic cleaner for ultrasonic treatment, and carrying out condensation reflux for 0.5-4 h at 50-100 ℃.
3) Rotary evaporating the mixed liquid in the step 2), and drying in an air drying oven at the temperature of 60-80 ℃.
4) Grinding the sample obtained in the step 3), uniformly dispersing the ground sample into a dish, calcining the sample in a nitrogen atmosphere, heating the sample to 700-1000 ℃, and then ammoniating the sample in an ammonia atmosphere to obtain the nitrogen-doped carbon-based material catalyst containing the defect active sites, wherein the name of the nitrogen-doped carbon-based material catalyst is NC.
2. The method of claim 1, wherein the nitrogen-doped carbon-based material catalyst comprises a plurality of defect sites, and the method comprises: in the step 1), the concentration of the nitric acid is 2-8 mol/L, the carbon material can be carbon black, biochar, graphene or activated carbon, and the mixed liquid is 10-50 mL.
3. The method of claim 1, wherein the nitrogen-doped carbon-based material catalyst comprises a plurality of defect sites, and the method comprises: in the step 2), the temperature of the ultrasonic cleaning instrument is 10-30 ℃, and the cleaning time is 2-10 min.
4. The method of claim 1, wherein the nitrogen-doped carbon-based material catalyst comprises a plurality of defect sites, and the method comprises: in the step 3), the temperature of the rotary steaming water bath is 40-80 ℃, and the drying time is 2-3 h; the air blast drying time is 12-24 h.
5. The method of claim 1, wherein the nitrogen-doped carbon-based material catalyst comprises a plurality of defect sites, and the method comprises: in the step 4), the heating rate is 2-10 ℃/min, the preferred ammoniation temperature is 800-1000 ℃, and the ammoniation time is 15-90 min.
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| CN113617350A (en) * | 2021-08-11 | 2021-11-09 | 北京林业大学 | Defective carbon material and preparation method and application thereof |
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