Preparation method of g-C3N4-g-C3N5-NH composite photocatalyst and application of g-C3N4-g-C3N5-NH composite photocatalyst in production of 2-phenylbenzimidazole and hydrogen peroxide from o-phenylenediamine coupled biphenyl formaldehyde

Abstract

The invention belongs to the field of preparation of photocatalysts, and particularly relates to a preparation method and application of a composite graphite phase carbon nitride (g-C3N4-g-C3N5-NH) photocatalyst. According to the composite catalyst, 3-amino-1, 2, 4-triazole (3-AT) and melamine (C3H6N6) are taken as material cores, ammonium chloride (NH4Cl) is added, mixed calcination is performed, an electronic structure and interlayer spacing are regulated and controlled, and the photocatalytic performance of the g-C3N4-g-C3N5-NH composite photocatalyst is improved. The catalyst is used for photocatalytic coupling reaction of o-phenylenediamine (OPD) and benzaldehyde (BAD) to generate 2-phenylbenzimidazole (2-BZ) and hydrogen peroxide (H2O2), and has high catalytic activity.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of photocatalysts, and specifically relates to a gC 3 N 4 -gC 3 N 5 -NH composite photocatalyst and preparation method thereof and photocatalytically promoting coupling reaction of o-phenylenediamine (OPD) and benzaldehyde (BAD) to produce 2-phenylbenzimidazole (2-BZ) and hydrogen peroxide (H 2 O 2 ) in the application. Background Art

[0002] Benzimidazole is one of the important chemicals in the fields of biomedicine and chemical raw materials today. It has a wide range of biological activities against a variety of viruses, including human immunodeficiency virus, herpes, influenza, etc. Generally, benzimidazole is synthesized by coupling OPD with carboxylic acid or its derivatives under strong acidic conditions and high temperature, or it can be obtained by condensing OPD with aldehydes. The reported catalysts for the photocatalytic preparation of benzimidazole are Pd / TiO 2 , Pd / ZnO, etc. However, these methods require strong oxidants and toxic reagents, resulting in dangerous synthetic pathways, which are not easy to recycle, and the catalyst preparation process is relatively cumbersome. Therefore, under mild conditions, the light-driven coupling of OPD with aldehydes has become an alternative method for synthesizing bioactive benzimidazoles. However, how to effectively adsorb and activate the two conjugates on the photocatalyst to improve the activity remains a challenge. Graphite phase carbon nitride exhibits excellent catalytic performance in photocatalysts, and the preparation method is relatively simple. But most of the time, the lighting conditions are not ideal, and the utilization rate is not very high, and some darker solutions are not conducive to the irradiation and penetration of light, resulting in the catalyst not being able to receive the light conditions well. In this case, the catalyst solution is prone to failure. Further research and utilization on graphite phase carbon nitride is a good choice. Therefore, the development of a photocatalyst with a simple preparation method and high efficiency still needs to be explored. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a gC 3 N 4 -gC 3 N 5 -NH composite photocatalyst and its preparation method and application. The composite catalyst is composed of 3-amino-1,2,4-triazole (3-AT) and melamine (C 3 H 6 N 6 ) is the core of the material, and by adding ammonium chloride (NH 4Cl) mixed calcination regulates the electronic structure and interlayer spacing, and improves gC 3 N 4 -gC 3 N 5 The photocatalytic performance of the -NH composite photocatalyst. The catalyst is used for the photocatalytic coupling reaction of o-phenylenediamine (OPD) and benzaldehyde (BAD) to produce 2-phenylbenzimidazole (2-BZ) and hydrogen peroxide (H 2 O 2 ), with high catalytic activity.

[0004] The technical solution adopted by the present invention to solve the above-mentioned problems is:

[0005] A gC 3 N 4 -gC 3 N 5 The preparation method of -NH composite photocatalyst comprises the following specific steps:

[0006] (1) 3-AT, C 3 H 6 N 6 NH 4 Cl is used as the raw material, mixed and ground evenly, and then transferred into a muffle furnace for calcination. The solid product obtained by the reaction is ground to obtain the initial gC 3 N 4 -gC 3 N 5 -NH composite photocatalyst;

[0007] (2) The composite catalyst obtained in step (1) is washed, dried and then ground to obtain gC 3 N 4 -gC 3 N 5 -NH composite photocatalyst.

[0008] According to the above scheme, in step (1), 3-AT, C 3 H 6 N 6 NH 4 The mass ratio of the three Cl is (1-2):(1-2):2.

[0009] According to the above scheme, in step (1), the heating rate of the muffle furnace calcination is 2-10°C / min, the heating temperature ranges to 500-600°C, and the insulation time ranges to 2-5h.

[0010] According to the above scheme, in step (2), deionized water is used for washing, and the volume range is 50-100 mL.

[0011] The gC prepared by the above method3 N 4 -gC 3 N 5 -NH composite photocatalyst can couple BAD and OPD to produce 2-BZ and H 2 O 2 The specific application method is: in an air atmosphere, visible light irradiation is performed to realize the photocatalytic coupling conversion of OPD and BAD into 2-BZ and H 2 O 2 ; The wavelength of visible light is greater than or equal to 420nm, and the irradiation time ranges from 1 to 3h; in ethanol solvent, the OPD concentration is preferably (10-15) mmol / L, the concentration of the composite photocatalyst in ethanol solvent is preferably 1-5 mg / mL, and the BAD volume is preferably (5-10) μL.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. The present invention is in this gC 3 N 4 -gC 3 N 5 When preparing the composite photocatalyst, C 3 H 6 N 6 , 3-AT and NH 4 The three raw materials are ground and then directly calcined, so that the raw materials can be fully contacted and the reaction effect is better. The direct calcination of the raw materials optimizes the preparation process of the catalyst, making the preparation process simpler and more efficient. 3 N 4 -gC 3 N 5 -NH composite photocatalysts have abundant active sites and stronger oxidizing properties, which enhances the catalytic performance of the catalyst and improves gC 3 N 4 -gC 3 N 5 -NH composite photocatalyst photocatalytic activity.

[0014] 2. gC of the present invention 3 N 4 -gC 3 N 5 -NH composite photocatalyst uses OPD and BAD as reaction substrates under visible light (λ≥420nm) irradiation, and under the promotion of the catalyst, 2-BZ is generated by coupling. This photocatalytic reaction process makes full use of the photogenerated carriers and also converts organic matter into H 2 O 2 The composite photocatalyst gC 3N 4 -gC 3 N 5 -NH has better activity in photocatalytic conversion of organic matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 gC prepared in Comparative Example 1 3 N 4 , gC prepared in Comparative Example 2 3 N 5 , gC prepared in Comparative Example 3 3 N 4 -gC 3 N 5 , Example gC 3 N 4 -gC 3 N 5 -NH composite photocatalyst catalyzes the reaction of OPD and BAD to produce 2-BZ and H 2 O 2 Quantity comparison chart.

[0016] Figure 2 gC prepared in Comparative Example 1 3 N 4 , gC prepared in Comparative Example 2 3 N 5 , C prepared in Comparative Example 3 3 N 4 -C 3 N 5 , Example gC 3 N 4 -gC 3 N 5 Comparative X-ray diffraction (XRD) patterns of the -NH composite photocatalysts. DETAILED DESCRIPTION

[0017] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the present invention is not limited to the following embodiments.

[0018] Comparative Example 1

[0019] A gC 3 N 4 The preparation method of the photocatalyst comprises the following specific steps:

[0020] 2g C 3 H 6 N 6 After grinding into fine powder, transfer to a muffle furnace, heat to 550°C at a heating rate of 10°C / min, and keep warm for 3 hours. After the calcination, the ground product is fine powder to obtain gC3 N 4 .

[0021] The above gC 3 N 4 Photocatalysts are used for the photocatalytic conversion of OPD and BAD to produce 2-BZ and H 2 O 2 , the specific application process is as follows:

[0022] Take 4 mL of ethanol, 5.4 mg of OPD, 10 μL of BAD and 10 mg of gC 3 N 4 The mixture was placed in a hydrogen evolution tube and mixed evenly after ultrasonic treatment for 15 min. The reaction tube was sealed and irradiated with visible light (λ≥420 nm) for 1.5 h. After 1.5 h, 100 μL of the mixed solution in the tube was diluted with 4 mL of methanol, the solid particles were filtered through a filter head, and the 2-BZ generation amount was measured by liquid chromatography. At the same time, another 100 μL of the mixed solution in the tube was injected into a 900 μL H 2 O in a centrifuge tube, take out the supernatant after centrifugation, add potassium iodide (KI) aqueous solution, potassium hydrogen phthalate (C 8 H 5 KO 4 ) aqueous solution and ammonium molybdate ((NH 4 ) 2 MoO 4 ) in water solution, wait for 15 min for the reaction, and then add it to the UV-visible spectrophotometer to measure H 2 O 2 Amount generated.

[0023] In this step, the concentration of KI aqueous solution is 0.1 mol / L and the volume is 1 mL; C 8 H 5 KO 4 The concentration of the aqueous solution is 0.1 mol / L and the volume is 1 mL; (NH 4 ) 2 MoO 4 The concentration of the aqueous solution is 0.01 mol / L and the volume is 50 μL.

[0024] Comparative Example 2

[0025] A gC 3 N 5 The preparation method of the photocatalyst comprises the following specific steps:

[0026] After 3-AT was ground into fine powder, it was transferred to a muffle furnace and heated to 550°C at a heating rate of 10°C / min and kept warm for 3 hours. After the calcination, the ground product was fine powder, i.e. gC 3 N 5 .

[0027] The above gC 3 N 5 Photocatalysts are used for the photocatalytic conversion of OPD and BAD to produce 2-BZ and H 2 O 2 , the specific application process is as follows:

[0028] Take 4 mL of ethanol, 5.4 mg of OPD, 10 μL of BAD and 10 mg of gC 3 N 5 The mixture was placed in a hydrogen evolution tube and mixed evenly after ultrasonic treatment for 15 min. The reaction tube was sealed and irradiated with visible light (λ≥420 nm) for 1.5 h. After 1.5 h, 100 μL of the mixed solution in the tube was diluted with 4 mL of methanol, the solid particles were filtered through a filter head, and the 2-BZ generation amount was measured by liquid chromatography. At the same time, another 100 μL of the mixed solution in the tube was injected into a 900 μL H 2 O in a centrifuge tube, take out the supernatant after centrifugation, and then add KI aqueous solution, C 8 H 5 KO 4 The aqueous solution and (NH 4 ) 2 MoO 4 After 15 minutes of reaction, add the solution to the UV-visible spectrophotometer to measure H 2 O 2 Amount generated.

[0029] In this step, the concentration of KI aqueous solution is 0.1 mol / L and the volume is 1 mL; C 8 H 5 KO 4 The concentration of the aqueous solution is 0.1 mol / L and the volume is 1 mL; (NH 4 ) 2 MoO 4 The concentration of the aqueous solution is 0.01 mol / L and the volume is 50 μL.

[0030] Comparative Example 3

[0031] A gC 3 N 4 -gC 3 N 5 The preparation method of the photocatalyst comprises the following specific steps:

[0032] 1g C 3 H 6 N 6After mixing with 1 g of 3-AT and grinding into fine powder, the mixture was transferred to a muffle furnace and heated to 550 °C at a heating rate of 10 °C / min and kept at this temperature for 3 h. After the calcination, the ground product was fine powder, i.e. gC 3 N 4 -gC 3 N 5 .

[0033] The above gC 3 N 4 -gC 3 N 5 Photocatalysts are used for the photocatalytic conversion of OPD and BAD to produce 2-BZ and H 2 O 2 , the specific application process is as follows:

[0034] Take 4 mL of ethanol, 5.4 mg of OPD, 10 μL of BAD and 10 mg of gC 3 N 4 -gC 3 N 5 The mixture was placed in a hydrogen evolution tube and mixed evenly after ultrasonic treatment for 15 min. The reaction tube was sealed and irradiated with visible light (λ≥420 nm) for 1.5 h. After 1.5 h, 100 μL of the mixed solution in the tube was diluted with 4 mL of methanol, the solid particles were filtered through a filter head, and the 2-BZ generation amount was measured by liquid chromatography. At the same time, another 100 μL of the mixed solution in the tube was injected into a 900 μL H 2 O in a centrifuge tube, take out the supernatant after centrifugation, and then add KI aqueous solution, C 8 H 5 KO 4 The aqueous solution and (NH 4 ) 2 MoO 4 After 15 minutes of reaction, add the solution to the UV-visible spectrophotometer to measure H 2 O 2 Amount generated.

[0035] In this step, the concentration of KI aqueous solution is 0.1 mol / L and the volume is 1 mL; C 8 H 5 KO 4 The concentration of the aqueous solution is 0.1 mol / L and the volume is 1 mL; (NH 4 ) 2 MoO 4 The concentration of the aqueous solution is 0.01 mol / L and the volume is 50 μL.

[0036] Example

[0037] A gC 3 N4 -gC 3 N 5 The preparation method of -NH composite photocatalyst comprises the following specific steps:

[0038] (1) 1g C 3 H 6 N 6 , 1 g 3-AT and 2 g NH 4 After the mixture is ground into fine powder, it is transferred to a muffle furnace and heated to 550°C at a heating rate of 10°C / min and kept at this temperature for 3h. After the calcination, the ground product is the initial gC 3 N 4 -gC 3 N 5 -NH composite photocatalyst;

[0039] (2) The obtained composite catalyst was treated with 70 mL of H 2 O for washing, and then transferred to a vacuum drying oven for drying at 60°C for 12 hours. After drying, it was ground to obtain gC 3 N 4 -gC 3 N 5 -NH composite photocatalyst.

[0040] The above gC 3 N 4 -gC 3 N 5 -NH photocatalyst for photocatalytic conversion of OPD and BAD to 2-BZ and H 2 O 2 , the specific application process is as follows:

[0041] Take 4 mL of ethanol, 5.4 mg of OPD, 10 μL of BAD and 10 mg of gC 3 N 4 -gC 3 N 5 -NH was placed in a hydrogen evolution tube and mixed evenly after ultrasonic treatment for 15 min. The reaction tube was sealed and irradiated with visible light (λ≥420 nm) for 1.5 h. After 1.5 h, 100 μL of the mixed solution in the tube was diluted with 4 mL of methanol, the solid particles were filtered through a filter head, and the generated 2-BZ was measured by liquid chromatography. At the same time, another 100 μL of the mixed solution in the tube was taken and injected into a liquid chromatograph containing 900 μL of H 2 O in a centrifuge tube, take out the supernatant after centrifugation, and then add KI aqueous solution, C 8 H 5 KO 4 The aqueous solution and (NH 4 ) 2 MoO4 After 15 minutes of reaction, add the solution to the UV-visible spectrophotometer to measure H 2 O 2 Amount generated.

[0042] In this step, the concentration of KI aqueous solution is 0.1 mol / L and the volume is 1 mL; C 8 H 5 KO 4 The concentration of the aqueous solution is 0.1 mol / L and the volume is 1 mL; (NH 4 ) 2 MoO 4 The concentration of the aqueous solution is 0.01 mol / L and the volume is 50 μL.

[0043] like Figure 1 As shown, it is obvious that gC 3 N 4 -gC 3 N 5 , and gC 3 N 4 -gC 3 N 5 -NH composite photocatalysts have higher yields of 2-BZ and H 2 O 2 Activity. 3 N 4 and gC 3 N 5 Promote the coupling of OPD and BAD to generate 2-BZ and H 2 O 2 The amount and 2-BZ yield were basically the same; when gC 3 N 4 and gC 3 N 5 After the two catalysts were combined, the yield of 2-BZ was significantly improved, and H 2 O 2 The yield is blank gC 3 N 4 and gC 3 N 5 Twice; when gC 3 N 4 -gC 3 N 5 Catalyst addition NH 4 After Cl, the catalyst production of 2-BZ and H 2 O 2 performance, and the yield of 2-BZ increases nearly linearly. 3 N 4 -gC 3 N5 -NH is the composite catalyst with the best performance, which indicates that the catalyst 4 Cl greatly improved the photocatalytic activity and further increased gC 3 N 4 -gC 3 N 5 -NH photocatalytic coupling of OPD with BAD to generate 2-BZ and H 2 O 2 Product performance.

[0044] like Figure 2 As shown in the figure, no matter it is a blank catalyst or a composite catalyst, the four catalysts have the same crystal form, and the introduction of different groups does not change the crystal structure, which can prove that gC 3 N 4 -gC 3 N 5 -NH composite photocatalyst has good stability. And the enlarged view of the (002) peak clearly shows a peak shift to a lower angle, indicating that gC 3 N 4 -gC 3 N 5 The interlayer distance between -NH layers is larger.

[0045] The above is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and changes without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing a g-C3N4-g-C3N5-NH composite photocatalyst, characterized in that: The specific steps are as follows: (1) 3-amino-1,2,4-triazole (3-AT), melamine (C3H6N6) and ammonium chloride (NH4Cl) are used as raw materials, mixed and ground evenly, and then transferred into a muffle furnace for calcination, and the solid product obtained by the reaction is ground to obtain an initial g-C3N4-g-C3N5-NH composite photocatalyst; (2) The composite catalyst obtained in step (1) is washed, dried and then ground to obtain a g-C3N4-g-C3N5-NH composite photocatalyst.

2. The method for preparing a g-C3N4-g-C3N5-NH composite photocatalyst according to claim 1, characterized in that: In step (1), the mass ratio of 3-AT, C3H6N6 and NH4Cl is (1-2): (1-2):

2.

3. The method for preparing a g-C3N4-g-C3N5-NH composite photocatalyst according to claim 1, characterized in that: In step (1), the muffle furnace calcination heating rate ranges from 2 to 10 °C / min, the heating temperature ranges from 500 to 600 °C, and the holding time ranges from 2 to 5 h.

4. The method for preparing a g-C3N4-g-C3N5-NH composite photocatalyst according to claim 1, characterized in that: In step (2), deionized water is used for washing in a volume range of 50-100 mL, and a vacuum oven is used for drying.

5. A g-C3N4-g-C3N5-NH composite photocatalyst prepared by the method described in any one of claims 1 to 4.

6. Use of the g-C3N4-g-C3N5-NH composite photocatalyst as described in claim 5 in photocatalytically promoting the coupling reaction of o-phenylenediamine (OPD) and benzaldehyde (BAD) to produce 2-phenylbenzimidazole (2-BZ) and hydrogen peroxide (H2O2).

7. The use according to claim 6, characterized in that The specific application method is: add g-C3N4-g-C3N5-NH composite photocatalyst and OPD to a mixed solution of BAD and ethanol, ultrasonically disperse or stir evenly, and then irradiate with visible light under air atmosphere conditions to achieve photocatalytic coupling of OPD and BAD into 2-BA and H2O2; wherein, the wavelength of visible light is not less than 420 nm, and the irradiation time ranges from 1 to 3 h.

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