Bi / Bi2MoO6 photocatalytic material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of photocatalytic materials, and provides a Bi / Bi2MoO6 photocatalytic material as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing an ethylene glycol solution of Bi (NO3) 3.5 H2O, an ethylene glycol solution of Na2MoO4. 2H2O and ethanol, and then carrying out hydrothermal reaction to obtain the Bi / Bi2MoO6 photocatalytic material. The photocatalytic material prepared by the invention has efficient photocatalytic oxidation and coupling of diphenyl methylamine, when ethyl acetate is used as a reaction solvent, the conversion rate of a 10W LED lamp to benzene methylamine is up to 99.67% after 365-370nm ultraviolet light irradiation for 3h, and meanwhile, the selectivity to a target product N-benzylidenebutylamine is up to 96.74%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photocatalytic materials, and particularly relates to a Bi / Bi2MoO6 photocatalytic material and a preparation method and application thereof. BACKGROUND

[0002] Benzylamine, as an important organic compound and intermediate, plays a crucial role in the fields of chemical industry, scientific research, etc. It is a chemical substance harmful to human body, and has toxicity and corrosivity. It can enter the human body through inhalation, ingestion or skin absorption, etc., and cause strong irritation to the eyes, mucous membranes, respiratory tract and skin, etc.

[0003] In the initial study of amine oxidative coupling, metals (Cu, Fe, etc.) or noble metals (Pd, Au, Pt, etc.) have achieved good results in the thermal catalytic oxidative coupling of amines. Linda et al. found that CeO2 combined with CuO can be heated at 110℃ for 17 h in air atmosphere, and the yield of benzylamine oxidative coupling is as high as 82%. Although thermal catalysis and electrocatalysis are highly regarded, due to the problems of long reaction time, harsh conditions, etc., it is difficult to be used in practical applications. Samanta et al. synthesized BiVO4 / g-C3N4 heterojunction photocatalyst by hydrothermal method and pyrolysis method, and the catalyst has high photocatalytic activity and excellent oxidation performance for benzylamine, benzyl alcohol, etc. Chen et al. synthesized binuclear Ru polyoxometalate (POMs) in organic solvents, and the catalyst also showed good benzylamine coupling performance under visible light irradiation in O2 atmosphere. In addition, bismuth-based materials have good visible light absorption performance, such as Bi2O2CO3, Bi2WO6, BiOCl, which are also widely used in photocatalytic benzylamine coupling and have excellent photocatalytic performance.

[0004] Bi2MoO6 material belongs to n-type semiconductor, which is widely used for the degradation of pollutants and plays an important role in environmental engineering governance. Bai et al. prepared hollow mesoporous Bi2MoO6 by solvothermal method, which showed higher photocatalytic activity for TC under light. Yang et al. synthesized flower-like microspheres of Bi / Bi2MoO6 composite materials by glycol reduction method, which showed excellent photocatalytic performance under visible light and could completely degrade rhodamine B (rhb) after 30 min, which was attributed to the doping of Bi, which could effectively reduce the recombination rate of photo-generated electron-hole pairs. Ma et al. successfully prepared a new type of Ag / Ag2MoO4 / Bi2MoO6 ternary composite photocatalyst by three steps, which significantly broadened the absorption capacity and response range of the catalytic system to visible light due to the surface plasmon resonance (SPR) effect, so that it could completely degrade tetracycline in 20 min. In addition, it can also be used as a catalyst for organic synthesis, for example, Phasayavan et al. synthesized oxygen-deficient Bi2MoO6 nanoplates by solvothermal method using ethylene glycol-ethanol as the reaction medium, and found that the oxygen-deficient Bi2MoO6 nanocatalyst could significantly improve the photocatalytic performance of benzylamine oxidation coupling under visible light. Meng et al. prepared Mo2C-QDs / C / Bi2MoO6 composite material by a simple hydrothermal method, which showed excellent photocatalytic performance in the oxidation coupling of benzylamine, with a benzylamine conversion rate of up to 92%.

[0005] Although some progress has been made in the photocatalytic oxidation of benzylamine with Bi2MoO6 composite materials, there are still many problems and challenges. For example, how to further improve the activity and stability of the photocatalyst, how to optimize the reaction conditions to improve the treatment efficiency, how to reduce the production cost to realize industrial application, etc. Therefore, it is of great significance to provide a method for preparing Bi / Bi2MoO6 and its photocatalytic oxidation coupling of benzylamine to promote the application of photocatalytic oxidation technology in the field of environmental protection. SUMMARY

[0006] The purpose of the present application is to overcome the problems existing in the prior art and provide a Bi / Bi2MoO6 photocatalytic material and a preparation method and application thereof.

[0007] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions: The present application provides a preparation method of Bi / Bi2MoO6 photocatalytic material, comprising the following steps: The Bi(NO3)3·5H2O ethylene glycol solution, the Na2MoO4·2H2O ethylene glycol solution and the ethanol are mixed and then subjected to hydrothermal reaction to obtain the Bi / Bi2MoO6 photocatalytic material; The temperature of the hydrothermal reaction is 150-200 DEG C, and the time of the hydrothermal reaction is 10-15 hours.

[0008] Further, the concentration of the Bi(NO3)3.5H2O glycol solution is 0.1-1 mmol / mL. The concentration of the Na2MoO4.2H2O glycol solution is 0.05-0.2 mmol / mL.

[0009] Further, the volume ratio of the Bi(NO3)3.5H2O glycol solution, the Na2MoO4.2H2O glycol solution and the ethanol is 1-3:1-3:1-5.

[0010] Further, the hydrothermal reaction further comprises a post-treatment after the hydrothermal reaction. The post-treatment step is: after the hydrothermal reaction, cooling to room temperature, washing the reaction product precipitate with water and ethanol for 1-5 times, and then drying at 60-100 DEG C for 10-15 hours.

[0011] The application provides the Bi / Bi2MoO6 photocatalytic material prepared by the preparation method.

[0012] The application also provides the application of the Bi / Bi2MoO6 photocatalytic material in photocatalytic oxidation coupling benzylamine.

[0013] According to the technical solution, compared with the prior art, the application has the following beneficial effects: The Bi / Bi2MoO6 photocatalyst synthesized by the simple method has high photocatalytic oxidation coupling benzylamine, and when ethyl acetate is used as a reaction solvent, the conversion rate of benzylamine is up to 99.67% after 3 hours of irradiation of a 10 W LED lamp at 365-370 nm ultraviolet light, and the selectivity of the target product N-benzyl-ethylenediamine is up to 96.74%. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The figure is a reaction mechanism diagram of the Bi / Bi2MoO6 photocatalytic material prepared by the application in photocatalytic oxidation coupling benzylamine. Figure 2 The figure is an XRD spectrum of the products prepared in Examples 1-4 and Comparative Examples 1-2. Figure 3 The (a) figure is a transient photocurrent response diagram of Bi, Bi2MoO6 and BBM-4, and the (b) figure is an electrochemical impedance spectrum diagram of Bi, Bi2MoO6 and BBM-4. Figure 4 The figure is a mass spectrum diagram of the reaction system after 1 hour of irradiation of BBM-4 in photocatalytic oxidation coupling benzylamine. DETAILED DESCRIPTION

[0015] The application provides a preparation method of a Bi / Bi2MoO6 photocatalytic material. The Bi(NO3)3.5H2O ethylene glycol solution, the Na2MoO4.2H2O ethylene glycol solution and ethanol are mixed, and then a hydrothermal reaction is performed to obtain the Bi / Bi2MoO6 photocatalytic material. The temperature of the hydrothermal reaction is 150-200℃, preferably 160-190℃, and more preferably 170-180℃; and the time of the hydrothermal reaction is 10-15h, preferably 11-14h, and more preferably 12-13h.

[0016] In the application, the Na2MoO4.2H2O ethylene glycol solution is slowly added into the Bi(NO3)3.5H2O ethylene glycol solution, then ethanol is added into the mixed solution, and the hydrothermal reaction is performed after stirring for 2-3h.

[0017] In the application, the concentration of the Bi(NO3)3.5H2O ethylene glycol solution is 0.1-1mmol / mL, preferably 0.2-0.8mmol / mL, and more preferably 0.3-0.6mmol / mL. The concentration of the Na2MoO4.2H2O ethylene glycol solution is 0.05-0.2mmol / mL, preferably 0.8-1.5mmol / mL, and more preferably 1mmol / mL.

[0018] In the application, the volume ratio of the Bi(NO3)3.5H2O ethylene glycol solution, the Na2MoO4.2H2O ethylene glycol solution and ethanol is 1-3:1-3:1-5, and preferably 2:2:4.

[0019] In the application, the post-treatment is further included after the hydrothermal reaction. The post-treatment step is as follows: after the hydrothermal reaction, the reaction product is precipitated, washed with water and ethanol for 1-5 times, preferably 2-4 times, and more preferably 3 times; and then dried at 60-100℃ for 10-15h; the drying temperature is preferably 70-90℃, and more preferably 80℃; and the drying time is preferably 11-14h, and more preferably 12-13h.

[0020] The application further provides the Bi / Bi2MoO6 photocatalytic material prepared by the above preparation method.

[0021] The application further provides application of the Bi / Bi2MoO6 photocatalytic material in photocatalytic oxidation of coupled benzylamine.

[0022] The technical solutions provided by the application will be described in detail below with reference to the examples, but they should not be understood as limiting the scope of protection of the application.

[0023] Example 1 3mmol of Bi(NO3)3·5H2O and 1mmol of Na2MoO4·2H2O were accurately measured respectively and placed in two beakers containing 10mL of ethylene glycol, and stirred until completely dissolved to obtain an ethylene glycol solution of Bi(NO3)3·5H2O and an ethylene glycol solution of Na2MoO4·2H2O.

[0024] The ethylene glycol solution of Na2MoO4·2H2O was slowly added dropwise into the ethylene glycol solution of Bi(NO3)3·5H2O under stirring, and after the addition was completed, the stirring was continued for 10min to obtain a mixed solution.

[0025] 20mL of ethanol was added to the mixed solution, and the stirring was continued for 2.5h to fully mix and uniformly distribute the solution. The mixed solution was loaded into a hydrothermal reaction kettle, and reacted at 180℃ for 12h.

[0026] After the reaction was completed, the reaction kettle was cooled to room temperature, and the gray precipitate inside was taken out, washed repeatedly with water and ethanol for 3 times, and then dried at 80℃ for 12h to obtain the Bi / Bi2MoO6 photocatalytic material, which was named as BBM-2.

[0027] Evaluation of photocatalytic performance: The photocatalyst BBM-2 prepared in the example was placed in 5mL of ethyl acetate solvent. 0.1mmol of benzylamine was accurately transferred into the system and ultrasonically treated for 10min to completely dissolve it. The photoreaction tube was placed in a photo-thermal parallel reactor for dark reaction for 1h to ensure that the material reached adsorption-desorption equilibrium, and then was subjected to photo-reaction under ultraviolet light irradiation for 3h, and the experimental temperature was controlled at 25℃ by circulating condensed water. The solution after reaction was detected by gas chromatography-mass spectrometry (GC-MS) for the photocatalytic oxidation coupled benzylamine product and imine yield, and the highest conversion rate was 95.26% by calculation, and the selectivity of the target product N-benzyl enamine butylamine was as high as 96.65%.

[0028] Example 2 The same as example 1, except that the addition amount of Bi(NO3)3·5H2O was 4mmol, and the Bi / Bi2MoO6 photocatalytic material was obtained, which was named as BBM-3.

[0029] Evaluation of photocatalytic performance: The same as example 1, except that the photocatalyst BBM-3 of example 2 is added in 5 mL of ethyl acetate solvent. The solution after reaction is detected by gas chromatography-mass spectrometry (GC-MS) for the photocatalytic oxidation coupling benzylamine product and imine yield, and the highest conversion rate is calculated to be 96.15%, and the selectivity of the target product N-benzyl enamine butylamine is as high as 96.69%.

[0030] Example 3 The same as example 1, except that the amount of Bi(NO3)3·5H2O added is 5 mmoL, and the Bi / Bi2MoO6 photocatalytic material is obtained, named BBM-4.

[0031] Evaluation of photocatalytic performance: The same as example 1, except that the photocatalyst BBM-4 of example 3 is added in 5 mL of ethyl acetate solvent. The solution after reaction is detected by gas chromatography-mass spectrometry (GC-MS) for the photocatalytic oxidation coupling benzylamine product and imine yield, and the highest conversion rate is calculated to be 99.67%, and the selectivity of the target product N-benzyl enamine butylamine is as high as 96.74%.

[0032] Example 4 The same as example 1, except that the amount of Bi(NO3)3·5H2O added is 6 mmoL, and the Bi / Bi2MoO6 photocatalytic material is obtained, named BBM-5.

[0033] Evaluation of photocatalytic performance: The same as example 1, except that the photocatalyst BBM-5 of example 4 is added in 5 mL of ethyl acetate solvent. The solution after reaction is detected by gas chromatography-mass spectrometry (GC-MS) for the photocatalytic oxidation coupling benzylamine product and imine yield, and the highest conversion rate is calculated to be 98.72%, and the selectivity of the target product N-benzyl enamine butylamine is as high as 95.60%.

[0034] Comparative example 1 Accurately weigh 0.1 mmoL of Na2MoO4·2H2O, and place it in a beaker containing 60 mL of deionized water. Ultrasonic cleaner is used for ultrasonic treatment for 30 min to ensure complete dissolution of Na2MoO4·2H2O, and a colorless transparent solution is obtained.

[0035] Weigh 0.2 mmoL of Bi(NO3)3·5H2O, and slowly add it to the above colorless transparent solution while stirring. Continue stirring for 3 h, during which time amorphous white precipitate will gradually form.

[0036] The ammonia water was added dropwise while monitoring the pH of the solution using a pH meter until the pH reached 6, at which point the solution was light yellow. The above solution was transferred to a hydrothermal reactor and heated at a temperature of 160°C for 12h. After the reaction was completed, a yellow precipitate was observed.

[0037] The yellow precipitate was washed with water and ethanol alternately 5 times to remove impurity ions, and then dried at 60°C for 12h to obtain Bi2MoO6 powder.

[0038] Comparative Example 2 The procedure of Comparative Example 1 was followed, but the amount of Bi(NO3)3·5H2O added was 1 / 5 of the amount of Na2MoO4·2H2O. The reaction was carried out under the same conditions. After the reaction was completed, in addition to the Bi2MoO6 precipitate, spherical Bi was separated by centrifugation.

[0039] Figure 2 The XRD patterns of the products prepared in Examples 1-4 and Comparative Examples 1-2 were obtained. The characteristic diffraction peaks of Bi and Bi2MoO6 were observed. In the XRD pattern of the composite material, the intensity of the characteristic diffraction peaks of Bi gradually increased and then decreased as the proportion of Bi added increased. No other diffraction peaks were observed in the pattern, indicating the successful preparation of the BBM composite material and the high purity of the prepared sample.

[0040] Figure 3 The (a) figure in (a) is the transient photocurrent response diagram of Bi, Bi2MoO6 and BBM-4, and the (b) figure is the electrochemical impedance spectrum diagram of Bi, Bi2MoO6 and BBM-4. It can be seen from the figures that the photocurrent response of the material BBM-4 after the combination of Bi and Bi2MoO6 is significantly improved, and the separation efficiency of the photo-generated electron-hole pairs is increased compared to the pure material. BBM-4 has the smallest Nyquist radius, indicating that the transfer resistance of the photo-generated electrons is the smallest, thereby improving the transfer efficiency of the photo-generated carriers. The above results show that BBM-4 has a high photo-generated electron-hole separation rate and a high photo-generated carrier transfer rate, making it have a high activity for photocatalytic conversion of benzylamine; Figure 4 The mass spectrum of the reaction system after BBM-4 was photocatalyzed for 1h for the oxidation coupling of benzylamine. It can be seen from the figure that benzylamine and N-benzyl enamine have obvious signal peaks.

[0041] The above only describes the preferred embodiments of the present application. It should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A preparation method of a Bi / Bi2MoO6 photocatalytic material, characterized in that, The method comprises the following steps: Bi(NO3)3.5H2O ethylene glycol solution, Na2MoO4.2H2O ethylene glycol solution and ethanol are mixed to carry out hydrothermal reaction to obtain the Bi / Bi2MoO6 photocatalytic material; The temperature of the hydrothermal reaction is 150-200℃, and the time of the hydrothermal reaction is 10-15h.

2. The production method according to claim 1, characterized by, The concentration of the Bi(NO3)3.5H2O ethylene glycol solution is 0.1-1mmol / mL; The concentration of the Na2MoO4.2H2O ethylene glycol solution is 0.05-0.2mmol / mL.

3. The production method according to claim 2, characterized by, The volume ratio of the Bi(NO3)3.5H2O ethylene glycol solution, Na2MoO4.2H2O ethylene glycol solution and ethanol is 1-3:1-3:1-5.

4. The production method according to any one of claims 1 to 3, characterized by, The method further comprises a post-treatment after the hydrothermal reaction; The post-treatment is carried out as follows: after the hydrothermal reaction, the reaction product is cooled to room temperature, and then washed with water and ethanol for 1-5 times, and then dried at 60-100℃ for 10-15h.

5. The Bi / Bi2MoO6 photocatalytic material prepared by the method of any one of claims 1-4.

6. The application of the Bi / Bi2MoO6 photocatalytic material of claim 5 in photocatalytic oxidation of coupled benzylamine.

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