阅读说明：本技术 碳化钼助剂、其制备方法以及在芬顿反应降级有机污染物上的应用 (Molybdenum carbide auxiliary agent, preparation method thereof and application of molybdenum carbide auxiliary agent in degradation of organic pollutants through Fenton reaction ) 是由 张金水 侯乙东 余德熙 阳灿 邹俊华 于 2021-06-30 设计创作，主要内容包括：本发明属于多相催化和水体污染物治理领域,具体涉及到碳化钼催化材料及其制备方法和在芬顿法催化过氧化氢降解有机污染物中的应用。其以碳化钼为助催化剂,过氧化氢为氧化剂,在芬顿主催化剂存在的条件下降解有机污染物。本发明操作简单,反应条件温和,降解时间短,可重复性高,助剂易合成,设备要求简单,具有一定的工业化应用前景。本发明通过利用碳化钼的富电子特性,加速了芬顿反应中Fe(III)/Fe(II)的循环速率,并抑制了过氧化氢的无效分解,从而提高芬顿反应效率。本发明提供了一种开发廉价、稳定、高效的负载型催化剂的使用方法,具有潜在的应用前景。(The invention belongs to the field of heterogeneous catalysis and water pollutant treatment, and particularly relates to a molybdenum carbide catalytic material, a preparation method thereof and application thereof in degrading organic pollutants by catalyzing hydrogen peroxide through a Fenton method. Molybdenum carbide is used as a cocatalyst, hydrogen peroxide is used as an oxidant, and organic pollutants are degraded in the presence of a Fenton main catalyst. The method has the advantages of simple operation, mild reaction conditions, short degradation time, high repeatability, easy synthesis of the auxiliary agent, simple equipment requirement and certain industrial application prospect. The invention accelerates the circulation rate of Fe (III)/Fe (II) in the Fenton reaction by utilizing the electron-rich characteristic of the molybdenum carbide, and inhibits the ineffective decomposition of the hydrogen peroxide, thereby improving the efficiency of the Fenton reaction. The invention provides a using method for developing a cheap, stable and efficient supported catalyst, and has potential application prospect.)

1. The preparation method of the molybdenum carbide auxiliary agent is characterized by comprising the following steps: the method comprises the following steps:

(1) dissolving the carbon-containing precursor in water or ethanol to obtain a solution A;

(2) dissolving the molybdenum-containing precursor in water or ethanol to obtain a solution B;

(3) and under the heating condition, dropwise adding the solution B into the solution A, uniformly stirring, evaporating the solvent to dryness to obtain a white solid, and placing the white solid in a tubular furnace for annealing and calcining under the protection of inert atmosphere to obtain the product molybdenum carbide auxiliary agent.

2. The method of claim 1, wherein: in the step (1), the carbon-containing precursor is one or more of dicyandiamide, melamine, urea, glucose and Pluronic F127.

3. The method of claim 1, wherein: in the step (2), the molybdenum-containing precursor is one or more of sodium molybdate, ammonium molybdate and molybdenum pentachloride.

4. The method of claim 1, wherein: in the solution in the step (3), the mass ratio of the molybdenum-containing precursor to the carbon-containing precursor is 0.2-1: 1.

5. the method of claim 1, wherein: the stirring temperature in the step (3) is 25-80 DEG C^oAnd C, stirring for 1-4 h.

6. The method of claim 1, wherein: in the step (3), the annealing temperature is 700-900 ℃, and the time is 2-4 h.

7. The molybdenum carbide auxiliary agent prepared by the preparation method of any one of claims 1-6.

8. The use of the molybdenum carbide additive prepared by the method according to claim 7 for degrading organic pollutants by a Fenton method, wherein the molybdenum carbide additive comprises the following components in percentage by weight: the molybdenum carbide auxiliary agent performs a Fenton reaction in a Fenton reaction main catalyst-pollutant-hydrogen peroxide system.

9. Use according to claim 8, characterized in that: the Fenton reaction main catalyst comprises one of ferrous sulfate, nano zero-valent iron and nano carbon-coated iron, the concentration of pollutants is 10-50 ppm, the pollutants comprise one of rhodamine B, bisphenol A and golden orange II, and the concentration of hydrogen peroxide is 100-300 ppm.

10. Use according to claim 9, characterized in that: the Fenton reaction temperature is 25-60 ℃, and the reaction time is 5-30 min.

Technical Field

The invention belongs to the field of heterogeneous catalysis and water pollutant treatment, and particularly relates to a molybdenum carbide catalytic material, a preparation method thereof and application thereof in degrading organic pollutants by catalyzing hydrogen peroxide through a Fenton method.

Background

With the continuous development of the industrial level in China, the environmental problem is increasingly prominent, wherein the problem of organic pollutant emission of the water body is more serious. Fenton oxidation technology refers to catalytic decomposition of H by catalyst₂O₂The reaction generates a large amount of hydroxyl free radicals with strong oxidizing property and non-selectivity, thereby realizing the process of oxidizing and degrading organic pollutants in the water body. The efficiency of the fenton reaction is mainly limited by the following two aspects: 1. in the catalytic process, the reduction rate of high valence state metal in the catalyst is slower, and the rate of the whole Fenton process is inhibited. 2. The reduction step of the metal is accompanied by the generation of oxygen, a process which is regarded as ineffective decomposition of hydrogen peroxide, reducing the utilization of hydrogen peroxide. Therefore, how to promote the electronic circulation process of the catalyst, promote the oxidation rate of hydrogen peroxide and inhibit the generation of oxygen is the key to improve the efficiency of the fenton reaction.

Disclosure of Invention

The invention aims to provide a preparation method and application of molybdenum carbide, which utilize the electron-rich characteristic of the prepared molybdenum carbide to promote the electron circulation rate of a main catalyst in a Fenton reaction, inhibit the ineffective decomposition of hydrogen peroxide and improve the pollutant degradation efficiency. The invention has simple synthesis and easy operation, shows excellent cocatalyst effect in Fenton reaction and has potential application value.

In order to achieve the purpose, the invention adopts the following technical scheme:

the preparation method of the molybdenum carbide auxiliary agent comprises the following specific scheme:

(1) respectively preparing a molybdenum precursor solution (solution A) and a carbon precursor solution (solution B), dripping the solution A into the solution B under the condition of stirring, uniformly stirring, and evaporating the solvent to obtain a solid C.

(2) And calcining the solid C in a tube furnace under the protection of inert gas to obtain the molybdenum carbide.

Further, in the step (1), a solvent in the molybdenum precursor solution or the carbon precursor solution is water or ethanol.

Further, in the step (1), the molybdenum precursor includes one of ammonium molybdate, sodium molybdate and molybdenum chloride. The carbon precursor comprises one or more of dicyandiamide, melamine, urea, glucose and Pluronic F127. Wherein the mass ratio of the molybdenum-containing precursor to the carbon-containing precursor is 0.2-1: 1.

further, the stirring temperature in the step (1) is 25-80 DEG C^oAnd C, stirring for 1-4 h.

Further, in the step (2), the inert atmosphere comprises one of argon and nitrogen, and the annealing temperature is 700-900 DEG C^oC, the time is 2-4 h. .

The invention also discloses an application of the molybdenum carbide promoter: molybdenum carbide is used as a cocatalyst, and hydrogen peroxide is used as an oxidant to degrade common water organic pollutants in a multiphase Fenton oxidation system.

Further, the Fenton oxidation system catalyst is one of ferrous sulfate, nano zero-valent iron and carbon-coated iron nanospheres.

Further, the organic pollutant comprises one of rhodamine B, gold orange II and bisphenol A.

Further, the temperature of the Fenton system is 25-60 DEG C^oAnd C, degrading for 5-30 min.

Furthermore, the mass ratio of the hydrogen peroxide to the pollutants is 1-20.

Compared with the prior art, the invention has the following advantages:

(1) the invention discloses a preparation method of molybdenum carbide, and the molybdenum carbide is introduced into Fenton reaction. The electron-rich characteristic of molybdenum carbide is utilized to accelerate the electron circulation process of the catalyst in the Fenton reaction, inhibit the ineffective decomposition of hydrogen peroxide and improve the Fenton reaction efficiency. Experimental results show that the Fenton reaction system added with the molybdenum carbide auxiliary agent has higher pollutant degradation efficiency.

(2) The invention has simple process, low cost and strong stability, and is beneficial to large-scale industrial production and application.

Drawings

FIG. 1 is an XRD pattern of carbon-coated molybdenum carbide a in example 1 of the present invention;

FIG. 2 is a Raman spectrum of carbon-coated molybdenum carbide a in example 1 of the present invention;

FIG. 3 is an SEM image of carbon-coated molybdenum carbide a prepared in example 1 of the present invention;

FIG. 4 is a graph showing the degradation of RhB by carbon-coated molybdenum carbide-ferrous sulfate in example 4 of the present invention;

FIG. 5 is a graph showing degradation RhB of carbon-coated molybdenum carbide-nano zero-valent iron in example 5 of the present invention;

fig. 6 is a graph showing degradation RhB of the carbon-coated molybdenum carbide-carbon-coated iron nanospheres in example 6 of the present invention.

Detailed Description

In order to make the present invention more comprehensible, the technical solutions of the present invention are further described below with reference to specific embodiments, but the present invention is not limited thereto.

Example 1

Molybdenum carbide a (carbon-coated molybdenum carbide, Mo)₂Preparation of C @ C):

0.5 g of molybdenum pentachloride was dissolved in 10 mL of ethanol at room temperature to form a solutionSolution A, 1 g of urea was dissolved in 10 mL of ethanol to form solution B. Adding solution A dropwise to solution B, and adding 0.5 g glucose at 25% ^oStirring for 2 h in water bath, stirring uniformly, and then heating to 80 DEG C ^oAnd C, evaporating the solvent. In a tubular furnace, nitrogen is used as protective gas and 5 is used^oThe temperature rises to 800 ℃ at a temperature rise rate of C/min^oAnd C, preserving the heat for 3 hours to obtain the molybdenum carbide a.

The molybdenum carbide a is characterized in that the molybdenum carbide is coated by in-situ grown carbon, and the stability of the molybdenum carbide can be still maintained under more extreme reaction conditions.

Example 2

Molybdenum carbide b (porous molybdenum carbide, porous-Mo)₂C) The preparation of (1):

at room temperature, 0.5 g of molybdenum pentachloride was dissolved in 5 mL of ethanol to form solution A, and 1 g of urea was dissolved in 5 mL of ethanol to form solution B. Solution a was added dropwise to solution B to form solution C. Dissolving 1.5 g of Pluronic F127 in 10 mL of ethanol to form a solution D, adding dropwise solution C to solution D at 25 ^oStirring in water bath for 2 h, and then heating to 80%^oAnd C, evaporating the solvent. In a tubular furnace, nitrogen is used as protective gas and 2 is used^oThe temperature rises to 300 ℃ at a temperature rise rate of C/min^oC, preserving the heat for 3 hours and then adding 5^oThe temperature rises to 800 ℃ at a temperature rise rate of C/min^oAnd C, preserving the heat for 3 hours to obtain molybdenum carbide b.

The molybdenum carbide a is characterized in that F127 is used as a soft template agent to induce the molybdenum carbide to form a porous structure, increase the specific surface area of the molybdenum carbide and improve the catalytic activity.

Example 3

Molybdenum carbide c (mesoporous molybdenum carbide mes-Mo)₂C) The preparation of (1):

80 ^ounder an oil bath C, 0.5 g of ammonium molybdate was dissolved in water to form a solution A, and 1 g of dicyandiamide was dissolved in water to form a solution B. Adding solution A dropwise to solution B at 25 ^oStirring in water bath for 2 h, and then heating to 80%^oAnd C, evaporating the solvent. In a tubular furnace with nitrogen as shielding gas 5^oThe temperature rises to 550 ℃ at the temperature rising rate of C/min^oC, preserving heat for 2 hours, and then heating to 750 DEG C ^oAnd C, preserving the heat for 2 hours to obtain molybdenum carbide C.

Molybdenum carbidec is characterized in that during the annealing process, the material passes through MoO_x@C₃N₄And finally forming the mesoporous molybdenum carbide in the intermediate process.

Example 4

Activity test for degrading rhodamine B (RhB) by ferrous sulfate-molybdenum carbide Fenton method

Dispersing 10 mg of molybdenum carbide a in 50 mL of solution containing 20 ppm of rhodamine B, and adding 2 mg of FeSO₄·6H₂And O, stirring for 15 min to reach absorption and desorption equilibrium, and taking 1.5 mL of solution, filtering and marking as a sample No. 0. Add 100. mu.L of 3% H₂O₂The solution (60 ppm in the system) was sampled every two minutes until the tenth minute. The absorbance at 554 nm of each sample was measured with a UV-Vis spectrophotometer and the absorbance (C) of each sample was recorded_x) And absorbance of sample No. 0 (C)₀) The ratio is marked as C_x/C₀And recording a time-dependent relative concentration change graph of the rhodamine B.

Example 5

Activity test for degrading rhodamine B (RhB) by nano zero-valent iron-molybdenum carbide Fenton method

Dispersing 10 mg of molybdenum carbide a in 50 mL of solution containing 20 ppm of rhodamine B, adding 4 mg of nano zero-valent iron, stirring for 15 min to reach absorption and desorption balance, taking 1.5 mL of solution at the moment, filtering, and marking as a sample No. 0. Add 100. mu.L of 3% H₂O₂The solution (60 ppm in the system) was sampled every two minutes until the tenth minute. The absorbance at 554 nm of each sample was measured with a UV-Vis spectrophotometer and the absorbance (C) of each sample was recorded_x) And absorbance of sample No. 0 (C)₀) The ratio is marked as C_x/C₀And recording a time-dependent relative concentration change graph of the rhodamine B.

Example 6

Activity test for degrading rhodamine B (RhB) by carbon-coated iron nanosphere-molybdenum carbide Fenton method

Dispersing 10 mg of molybdenum carbide a in 50 mL of solution containing 20 ppm of rhodamine B, adding 4 mg of carbon-coated iron nanospheres, stirring for 15 min to reach adsorption and desorption balance, taking 1.5 mL of solution, filtering, and marking as No. 0And (5) sampling. Add 100. mu.L of 3% H₂O₂The solution (60 ppm in the system) was sampled every two minutes until the tenth minute. The absorbance at 554 nm of each sample was measured with a UV-Vis spectrophotometer and the absorbance (C) of each sample was recorded_x) And absorbance of sample No. 0 (C)₀) The ratio is marked as C_x/C₀And recording a time-dependent relative concentration change graph of the rhodamine B.

FIG. 1 is an XRD pattern of molybdenum carbide a, 2 thereinθ= 36.6^o And 42.6^oRespectively corresponding to the (111) and (200) crystal planes of the molybdenum carbide,

FIG. 2 is a Raman spectrum of molybdenum carbide a having peaks at 1300 cm-1 and 1580 cm-1 corresponding to amorphous and graphitic carbon, respectively, demonstrating the presence of elemental carbon in molybdenum carbide a.

Fig. 3 is an SEM image of molybdenum carbide, and it can be seen that the surface of molybdenum carbide a has a lamellar structure with a smooth surface.

FIG. 4 is a graph of the degradation RhB of carbon-coated molybdenum carbide-ferrous sulfate in example 4 of the present invention, which shows that molybdenum carbide itself has no Fenton activity, but it significantly improves the degradation efficiency of ferric sulfate to dye.

Fig. 5 is a graph of carbon-coated molybdenum carbide-nano zero-valent iron degradation RhB in example 5 of the present invention, which shows that molybdenum carbide itself has no fenton activity, but it significantly improves the degradation efficiency of nano zero-valent iron on dyes.

Fig. 6 is a graph of degradation RhB of the carbon-coated molybdenum carbide-carbon-coated iron nanospheres in example 6 of the present invention, which shows that molybdenum carbide itself has no fenton activity, but it significantly improves the degradation efficiency of the carbon-coated iron nanospheres on the dye.