CN116217341B - A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol - Google Patents

Abstract

The invention discloses a photocatalysis preparation method of 1, 2-diphenyl-1, 2-glycol, and relates to the technical field of fine chemical engineering. The method comprises the following steps: acetonitrile and benzyl alcohol are mixed and subjected to ultrasonic treatment, and then a P-doped g-C ₃N₄ catalyst modified by NiS nano particles is added to obtain a reaction solution; stirring, reacting under the condition of inert gas atmosphere, visible light and 10-20 ℃, centrifuging and collecting the solution to prepare the 1, 2-diphenyl-1, 2-glycol. The preparation method has mild reaction conditions, does not need harsh instruments and other conditions, and is a clean, environment-friendly, stable, efficient, environment-friendly and economical preparation process of the 1, 2-diphenyl-1, 2-glycol. The invention solves the problems that the existing preparation method is complex and needs toxic metal complex catalyst and a large amount of hydrogen-supplying reagent.

Description

A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol

Technical Field

The invention relates to the technical field of fine chemicals, and in particular to a photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol.

Background technique

1,2-Diphenyl-1,2-ethylene glycol (hydrogenated benzoin) and its derivatives are multifunctional structural units in the synthesis of fine chemicals and pharmaceutical intermediates, and are widely used in chiral and synthetic chemistry. Traditional methods for preparing 1,2-diphenyl-1,2-ethylene glycol include asymmetric hydroxylation of olefins, asymmetric pinacol coupling reaction of benzaldehyde, and decomposition of racemic diols. These methods require toxic metal complex catalysts and a large amount of hydrogen donor reagents (various alcohols: methanol, ethanol, etc.), and these methods have complex process steps. The intermediate processing steps will be accompanied by the generation of a large amount of industrial pollutants, which will cause serious corrosion to the equipment and do not meet the requirements of green chemistry. At the same time, the yield of 1,2-diphenyl-1,2-ethylene glycol is low, and it is accompanied by the generation of a large amount of by-products.

Photocatalytic technology uses solar energy as its energy source and has the advantages of being green, environmentally friendly, cheap and readily available. The CC coupling of benzyl alcohol to produce 1,2-diphenyl-1,2-ethylene glycol by photocatalytic means can effectively solve the drawbacks of the above-mentioned traditional methods. In the light-driven preparation of hydrogenated benzoin, photogenerated holes will activate the OH bond or sp ³ hybridized CH bond of the reaction substrate benzyl alcohol. However, the activation of the OH bond will lead to the production of a large number of benzyloxy radicals (C ₆ H ₅ -CH ₂ O·), which will in turn produce benzaldehyde as a by-product. Therefore, highly selective control of the activation of the sp ³ hybridized CH bond of benzyl alcohol is crucial to increasing the yield of 1,2-diphenyl-1,2-ethylene glycol.

Summary of the invention

In order to solve the above technical problems, the purpose of the present invention is to provide a photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol to solve the problem that the existing preparation method is complicated and requires the use of toxic metal complex catalysts and a large amount of hydrogen supply reagents.

The technical solution of the present invention to solve the above technical problems is as follows: a photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol is provided, comprising the following steps:

(1) acetonitrile and benzyl alcohol are mixed, ultrasonicated, and then a P-doped gC ₃ N ₄ catalyst modified with NiS nanoparticles is added to obtain a reaction solution;

(2) The reaction solution obtained in step (1) is stirred for 25-35 minutes, reacted for 5-7 hours under an inert gas atmosphere, visible light and 10-20° C., and the solution is collected by centrifugation to obtain 1,2-diphenyl-1,2-ethylene glycol.

On the basis of the above technical solution, the present invention can also be improved as follows:

Furthermore, in step (1), the molar mass ratio of acetonitrile to benzyl alcohol is 8-12 mL: 0.2-1 mmol, and the molar mass ratio of benzyl alcohol to NiS nanoparticle-modified P-doped gC ₃ N ₄ catalyst is 0.2-1 mmol: 10-50 mg.

Furthermore, in step (1), before acetonitrile and benzyl alcohol are mixed, acetonitrile and water are first mixed to form a mixed solution, which is then mixed with benzyl alcohol; the volume fraction of water in the mixed solution is 8-12%.

The beneficial effect of adopting the above further technical scheme is that the addition of water can effectively regulate the activation path of the substrate benzyl alcohol in the reaction, which can not only accurately regulate the selectivity of the product 1,2-diphenyl-1,2-ethylene glycol, but also achieve the efficient preparation of another high value-added benzaldehyde product while preparing 1,2-diphenyl-1,2-ethylene glycol.

Furthermore, the volume fraction of water in the mixed solution is 10%.

In step (1), the molar mass ratio of the mixed solution to benzyl alcohol is 8-12 mL: 0.2-1 mmol, and the molar mass ratio of benzyl alcohol to the P-doped gC ₃ N ₄ catalyst modified by NiS nanoparticles is 0.2-1 mmol: 10-50 mg.

Furthermore, in step (1), the mass fraction of P element in the P-doped gC ₃ N ₄ catalyst modified by NiS nanoparticles is 1-5%, and the mass fraction of NiS is 1-3%.

Furthermore, in step (1), the mass fraction of P element in the P-doped gC ₃ N ₄ catalyst modified by NiS nanoparticles is 1.25%, and the mass fraction of NiS is 2%.

Further, in step (1), the NiS nanoparticle-modified P-doped gC ₃ N ₄ catalyst is prepared by the following method:

(1.1) Add dicyandiamide and NH ₄ H ₂ PO ₄ into water, stir, evaporate the water, and calcine to obtain P-doped carbon nitride;

(1.2) Dissolve Ni(CH ₃ COO) ₂ ·4H ₂ O in water, add the P-doped carbon nitride prepared in step (1.1), add thiourea and NaH ₂ PO ₂ ·H ₂ O under ultrasonic and stirring conditions, maintain for 25-35 min, perform hydrothermal reaction, wash, and dry to obtain NiS nanoparticle-modified P-doped gC ₃ N ₄ catalyst.

Furthermore, in step (1.1), the mass volume ratio of dicyandiamide, NH ₄ H ₂ PO ₄ and water is 7-9 g: 0.7-0.9 g: 30 mL.

Furthermore, in step (1.1), the mass volume ratio of dicyandiamide, NH ₄ H ₂ PO ₄ and water is 8 g:0.8 g:30 mL.

Furthermore, in step (1.1), the water is evaporated to dryness in a water bath at 75-85°C.

Furthermore, in step (1.1), calcination is carried out under a _N2 atmosphere.

Furthermore, in step (1.1), the calcination is carried out at 500-600°C for 3.5-4.5h.

Furthermore, in step (1.1), the calcination heating rate is 4.5-5.5°C/min.

Furthermore, in step (1.2), the molar volume ratio of Ni(CH ₃ COO) ₂ ·4H ₂ O, thiourea, NaH ₂ PO ₂ ·H ₂ O and water is 0.1-0.4 mmol: 0.4-1.6 mmol: 0.1-0.4 mmol: 45-55 mL.

Furthermore, in step (1.2), the molar volume ratio of Ni(CH ₃ COO) ₂ ·4H ₂ O, thiourea, NaH ₂ PO ₂ ·H ₂ O and water is 0.2 mmol:0.8 mmol:0.2 mmol:50 mL.

Furthermore, in step (1.2), the hydrothermal reaction is carried out at 150-200° C. for 3.5-4.5 h.

Further, in step (1.2), washing is performed with water and ethanol in sequence.

Furthermore, in step (1.2), drying is performed at 55-65° C. for 10-15 h.

Furthermore, in step (2), the inert gas is nitrogen or argon.

Furthermore, in step (2), the wavelength of visible light is ≥420 nm.

Furthermore, in step (2), the reaction is carried out under normal pressure.

The present invention also provides 1,2-diphenyl-1,2-ethylene glycol prepared by the method.

The present invention has the following beneficial effects:

1. The present invention uses photocatalytic means, selects NiS nanoparticles modified P doped gC ₃ N ₄ as a photocatalyst, uses benzyl alcohol as a raw material, and uses acetonitrile as a solvent under the condition of no additional hydrogen supply reagent, at room temperature, normal pressure, and visible light irradiation, to prepare 1,2-diphenyl-1,2-ethylene glycol through CC coupling reaction of benzyl alcohol, which has high reaction rate and product selectivity. The present invention relates to a preparation method with mild reaction conditions and no need for harsh instruments and other conditions, and is a clean, environmentally friendly, stable, efficient, green and economical 1,2-diphenyl-1,2-ethylene glycol preparation process.

2. The NiS nanoparticle-modified P-doped gC ₃ N ₄ photocatalyst used in the present invention does not contain toxic metal complexes, does not require additional precious metal co-catalysts, exhibits efficient photocatalytic activation of benzyl alcohol, can accurately control the selectivity of 1,2-diphenyl-1,2-ethylene glycol in the product (more than 70%), and exhibits efficient stability in cycle tests. The application of this method not only reduces the catalyst cost and saves resources, but also avoids harsh synthesis conditions, which is of great significance for the promotion and use of catalysts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a TEM characterization of the catalyst of Example 1;

FIG2 is an XRD characterization of the catalyst of Example 1;

FIG3 is an XPS characterization of the catalyst of Example 1;

FIG4 is a curve showing the change of product yield over time in Example 1;

FIG5 is a 5-cycle stability test of the catalyst in Example 1;

FIG6 is a graph showing the product production rate and selectivity of Examples 1, 8, 9 and Comparative Example 1;

Detailed ways

The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples are only used to explain the present invention and are not used to limit the scope of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

Embodiment 1:

A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol comprises the following steps:

(1) Preparation of Catalyst

(1.1) 8 g of dicyandiamide and 0.8 g of NH ₄ H ₂ PO ₄ were added to 30 mL of water and stirred for 1 h to form a homogeneous solution. The solution was then evaporated in a water bath at 80 °C and calcined at 550 °C for 4 h in a N ₂ atmosphere at a heating rate of 5 °C/min to obtain P-doped carbon nitride (PCN).

(1.2) Dissolve 0.2 mmol of Ni(CH ₃ COO) ₂ ·4H ₂ O in 50 mL of water, sonicate to dissolve it, add the P-doped carbon nitride obtained in step (1.1), sonicate for 30 min, add 0.8 mmol of thiourea and 0.2 mmol of NaH ₂ PO ₂ ·H ₂ O under stirring, keep for 30 min, transfer the stirred dispersion to a 50 mL hydrothermal autoclave, hydrothermally react at 180° C. for 4 h, wash with water and ethanol in turn, dry in an oven at 60° C. for 12 h, and obtain a NiS nanoparticle-modified P-doped g-C ₃ N ₄ catalyst (the mass fraction of the P element in the catalyst is 1.25%, and the mass fraction of NiS is 2%).

(2) 10 mL of acetonitrile and 0.2 mmol of benzyl alcohol were mixed and ultrasonicated to form a homogeneous solution, and then 20 mg of NiS nanoparticle-modified P-doped gC ₃ N ₄ catalyst (the mass fraction of the P element in the catalyst was 1.25%, and the mass fraction of NiS was 2%) was added to obtain a reaction solution;

(3) The reaction solution obtained in step (2) was placed in a reactor and stirred for 30 minutes. The reactor was sealed and inert gas _N2 was introduced for 30 minutes. The air in the reactor was exhausted. A 300W xenon lamp (with a wavelength ≥ 420nm filter) was used to irradiate visible light into the reactor through top illumination. The temperature of the reactor was controlled at 15°C by water circulation condensation. The reaction was carried out at normal pressure for 6 hours. The solution was collected by centrifugation to obtain 1,2-diphenyl-1,2-ethylene glycol.

Embodiment 2:

A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol comprises the following steps:

(1) Preparation of Catalyst

(1.1) 8 g of dicyandiamide and 0.8 g of _{NH 4} H ₂ PO ₄ were added to 30 mL of water and stirred for 1 h to form a homogeneous solution. The solution was then evaporated in a water bath at 80 °C and calcined at 550 °C for 4 h in a N ₂ atmosphere at a heating rate of 5 °C/min to obtain P-doped carbon nitride (PCN).

(1.2) Dissolve 0.1 mmol of Ni(CH ₃ COO) ₂ ·4H ₂ O in 50 mL of water, sonicate to dissolve it, add the P-doped carbon nitride obtained in step (1.1), sonicate for 30 min, add 0.4 mmol of thiourea and 0.1 mmol of NaH ₂ PO ₂ ·H ₂ O under stirring, keep for 25 min, transfer the stirred dispersion to a 50 mL hydrothermal autoclave, hydrothermally react at 180° C. for 4 h, wash with water and ethanol in turn, dry in an oven at 60° C. for 12 h, and obtain a NiS nanoparticle-modified P-doped g-C ₃ N ₄ catalyst (the mass fraction of the P element in the catalyst is 1.25%, and the mass fraction of NiS is 1%).

(2) 8 mL of acetonitrile and 0.5 mmol of benzyl alcohol were mixed and ultrasonicated to form a homogeneous solution, and then 10 mg of NiS nanoparticle-modified P-doped gC ₃ N ₄ catalyst (the mass fraction of the P element in the catalyst was 1.25%, and the mass fraction of NiS was 1%) was added to obtain a reaction solution;

(3) The reaction solution obtained in step (2) was placed in a reactor and stirred for 25 minutes. The reactor was sealed and inert gas _N2 was introduced for 30 minutes. The air in the reactor was exhausted. A 300W xenon lamp (with a wavelength ≥ 420nm filter) was used to irradiate visible light into the reactor through top illumination. The temperature of the reactor was controlled at 10°C by water circulation condensation. The reaction was carried out at normal pressure for 7 hours. The solution was collected by centrifugation to obtain 1,2-diphenyl-1,2-ethylene glycol.

Embodiment 3:

A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol comprises the following steps:

(1) Preparation of Catalyst

(1.1) 8 g of dicyandiamide and 0.8 g of NH ₄ H ₂ PO ₄ were added to 30 mL of water and stirred for 1 h to form a homogeneous solution. The solution was then evaporated in a water bath at 80 °C and calcined at 550 °C for 4 h in a N ₂ atmosphere at a heating rate of 5 °C/min to obtain P-doped carbon nitride (PCN).

(1.2) Dissolve 0.4 mmol of Ni(CH ₃ COO) ₂ ·4H ₂ O in 50 mL of water, sonicate to dissolve it, add the P-doped carbon nitride obtained in step (1.1), sonicate for 30 min, add 1.6 mmol of thiourea and 0.4 mmol of NaH ₂ PO ₂ ·H ₂ O under stirring, keep for 35 min, transfer the stirred dispersion to a 50 mL hydrothermal autoclave, hydrothermally react at 180° C. for 4 h, wash with water and ethanol in turn, and dry in an oven at 60° C. for 12 h to obtain a NiS nanoparticle-modified P-doped g-C ₃ N ₄ catalyst (the mass fraction of the P element in the catalyst is 1.25%, and the mass fraction of NiS is 3%);

(2) acetonitrile and water were mixed to form 12 mL of a mixed solution (the volume fraction of water in the mixed solution was 10%), 1 mmol of benzyl alcohol was added, and ultrasonic treatment was performed to form a homogeneous solution, and then 50 mg of NiS nanoparticle-modified P-doped gC ₃ N ₄ catalyst was added to obtain a reaction solution; the mass fraction of P element in the NiS nanoparticle-modified P-doped gC ₃ N ₄ catalyst was 1.25%, and the mass fraction of NiS was 3%;

(3) The reaction solution obtained in step (2) was placed in a reactor and stirred for 35 minutes. The reactor was sealed and introduced with inert gas _N2 for 30 minutes. The air in the reactor was exhausted. A 300W xenon lamp (with a wavelength ≥ 420nm filter) was used to irradiate visible light into the reactor through top illumination. The temperature of the reactor was controlled at 20°C by water circulation condensation. The reaction was carried out at normal pressure for 5 hours. The solution was collected by centrifugation to obtain 1,2-diphenyl-1,2-ethylene glycol.

Embodiment 4-7:

A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol comprises the following steps:

In step (2), the masses of the P-doped gC ₃ N ₄ catalyst modified with NiS nanoparticles added are 10 mg, 30 mg, 40 mg and 50 mg, respectively. The rest is the same as in Example 1.

Embodiment 8-9:

A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol comprises the following steps:

In step (2), the mass fractions of NiS added to the P-doped gC ₃ N ₄ catalyst modified with NiS nanoparticles are 1% and 3% respectively. The rest is the same as in Example 1.

Embodiment 10:

A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol comprises the following steps:

In step (2), acetonitrile and water are mixed to form 10 mL of a mixed solution (the volume fraction of water in the mixed solution is 10%), and then 0.2 mmol of benzyl alcohol is added and ultrasonicated to form a homogeneous solution. The rest is the same as in Example 1.

Embodiment 11-14:

A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol comprises the following steps:

In step (2), the amounts of benzyl alcohol added were 0.4 mmol, 0.6 mmol, 0.8 mmol and 1 mmol, respectively, and the rest were the same as in Example 1.

Embodiment 15:

A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol comprises the following steps:

In step (3), the inert gas is argon, and the rest is the same as in Example 1.

Embodiment 16:

A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol comprises the following steps:

In step (2), 10 mg of NiS nanoparticle-modified P-doped gC ₃ N ₄ catalyst was added, the mass fraction of NiS was 2%, acetonitrile and water were mixed to form 10 mL of a mixed solution (the volume fraction of water in the mixed solution was 10%), and then 0.2 mmol of benzyl alcohol was added, and ultrasonication was performed to form a homogeneous solution. The rest was the same as in Example 1.

Embodiment 17:

A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol comprises the following steps:

In step (2), the mass fraction of NiS in the P-doped gC ₃ N ₄ catalyst modified with NiS nanoparticles is 3%, the amount of benzyl alcohol is 0.6 mmol, the inert gas is argon, and the rest is the same as in Example 1.

Embodiment 18:

A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol comprises the following steps:

In step (2), the mass of the P-doped gC ₃ N ₄ catalyst modified with NiS nanoparticles added is 50 mg, the mass fraction of NiS is 1%, and the rest is the same as in Example 1.

Comparative Example 1:

A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol comprises the following steps:

In step (2), the mass fraction of NiS in the P-doped gC ₃ N ₄ catalyst modified with NiS nanoparticles is 0%, and the rest is the same as in Example 1.

Comparative Examples 2-4:

A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol comprises the following steps:

In step (2), acetonitrile and water are mixed to form 10 mL of a mixed solution (the volume fraction of water in the mixed solution is 20%, 30% and 40% respectively), and then 0.2 mmol of benzyl alcohol is added and ultrasonicated to form a homogeneous solution. The rest is the same as in Example 1.

Comparative Example 5:

A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol comprises the following steps:

In step (2), the inert gas is argon, and the rest is the same as in Comparative Example 3.

Test example

1. The photocatalyst prepared in Example 1 was subjected to TEM, XRD and XPS tests. The results are shown in Figures 1-3.

As shown in Figure 1, the prepared NiS/PCN material exhibits a typical layered structure with pores in the layer. Small nanoparticles are evenly dispersed on the PCN surface. The size of these nanoparticles is 8nm and the lattice spacing is 0.27nm in HRTEM, which belongs to the (300) crystal plane of NiS. In Figure 2, XRD shows that the sample has diffraction peaks at 12.8° and 27.4°, which belong to the (100) and (002) crystal planes of graphite phase carbon nitride. The diffraction peaks at 18.46°, 32.25°, 35.77°, 40.54° and 48.93° belong to NiS (PDF#86-2280) particles. In the full XPS spectrum of Figure 3, C, N, O, P, Ni and S elements are detected, among which the O1s peak at 532eV is due to the oxygen-containing functional groups (such as H ₂ The above TEM, XRD and XPS together indicate that NiS is successfully dispersed on the P-doped carbon nitride surface of the layer in the form of nanoparticles.

2. The reaction time of step (3) of Example 1 was set to 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h and 10 h respectively, and the yield of the product was statistically analyzed. The results are shown in Figure 4.

As shown in Figure 4, with 2.0% NiS/PCN as the catalyst, as the reaction time progresses, the content of 1,2-diphenyl-1,2-ethylene glycol increases linearly within the first 6 hours. The calculated rate is as high as 677.5μmol·g ^-1 ·h ^-1 . After 6 hours of reaction, the content of 1,2-diphenyl-1,2-ethylene glycol no longer increases, indicating that the reactant benzyl alcohol has reacted completely and the product 1,2-diphenyl-1,2-ethylene glycol has not been decomposed.

3. The catalyst of Example 1 was recycled for 5 times. The results are shown in FIG5 .

As shown in Figure 5, the yield and selectivity are still good after 5 cycles of reaction.

4. The product components and contents of Examples 1, 4-18 and Comparative Examples 1-5 were determined by high performance liquid chromatography. The production rates and product selectivities are shown in Table 1.

Table 1 Product generation rate and selectivity

As shown in Table 1, the production rate and product selectivity of photocatalytic preparation of 1,2-diphenyl-1,2-ethylene glycol are not only related to the content of NiS in the NiS/PCN catalyst, but also closely related to the quality of the catalyst, the type of solvent, and the content of the added reactant benzyl alcohol. Among them, with the increase in the amount of catalyst NiS/PCN used, the production rate of 1,2-diphenyl-1,2-ethylene glycol increased significantly. After 50 mg of catalyst was added, the highest production rate was as high as 1331.9 μmol·g ^-1 ·h ^-1 ; when water was added to acetonitrile, water would directly affect the activation path of the reaction substrate benzyl alcohol, resulting in a slight decrease in the production rate of 1,2-diphenyl-1,2-ethylene glycol, a decrease in selectivity, and an increase in the content of another benzaldehyde in the product; when the content of the reactant benzyl alcohol was increased, the production rate of 2-diphenyl-1,2-ethylene glycol product was improved.

5. The product generation rates and product selectivities of Examples 1, 8, 9 and Comparative Example 1 are plotted in a bar graph, and the results are shown in FIG6 .

As shown in Figure 6, the introduction of NiS in the NiS/PCN catalyst has a significant effect on the efficiency of the photocatalytic production of 1,2-diphenyl-1,2-ethylene glycol. With the increase of NiS content, the production rate of 1,2-diphenyl-1,2-ethylene glycol first increases and then decreases. When the NiS mass fraction is 2.0%, the production rate of 1,2-diphenyl-1,2-ethylene glycol is as high as 677.5μmol·g ^-1 ·h ^-1 ; the conversion rate of the reactant benzyl alcohol also shows the same change trend. Under the action of 2.0% NiS/PCN catalyst, the conversion rate of benzyl alcohol is >99%.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (6)

1. A photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol, characterized in that it comprises the following steps: (1) acetonitrile and benzyl alcohol are mixed, ultrasonicated, and then a P-doped g-C ₃ N ₄ catalyst modified with NiS nanoparticles is added to obtain a reaction solution; (2) stirring the reaction solution obtained in step (1) for 25-35 minutes, reacting for 5-7 hours under an inert gas atmosphere, visible light and 10-20°C, and collecting the solution by centrifugation to obtain 1,2-diphenyl-1,2-ethylene glycol; In step (1), the mass fraction of P element in the P-doped gC ₃ N ₄ catalyst modified with NiS nanoparticles is 1-5%, and the mass fraction of NiS is 1-3%; In step (1), the NiS nanoparticle-modified P-doped gC ₃ N ₄ catalyst is prepared by the following method: (1.1) Add dicyandiamide and NH ₄ H ₂ PO ₄ to water, stir, evaporate the water, and calcine to obtain P-doped carbon nitride; (1.2) Dissolve Ni(CH ₃ COO) ₂ ·4H ₂ O in water, add the P-doped carbon nitride prepared in step (1.1), add thiourea and NaH ₂ PO ₂ ·H ₂ O under ultrasonic and stirring conditions, maintain for 25-35 min, carry out hydrothermal reaction, wash, and dry to obtain NiS nanoparticle-modified P-doped g-C ₃ N ₄ catalyst. 2. The photocatalytic preparation method of 1,2-diphenyl-1,2-ethanediol according to claim 1, characterized in that, in step (1), the volume molar ratio of acetonitrile to benzyl alcohol is 8-12 mL:0.2-1 mmol, and the molar mass ratio of benzyl alcohol to NiS nanoparticle-modified P-doped gC ₃ N ₄ catalyst is 0.2-1 mmol:10-50 mg. 3. The photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol according to claim 1, characterized in that, in step (1), before acetonitrile and benzyl alcohol are mixed, acetonitrile and water are first mixed to form a mixed solution, which is then mixed with benzyl alcohol; the volume fraction of water in the mixed solution is 8-12%. 4. The photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol according to claim 1, characterized in that in step (2), the inert gas is nitrogen or argon. 5. The photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol according to claim 1, characterized in that in step (2), the wavelength of visible light is ≥ 420 nm. 6. The photocatalytic preparation method of 1,2-diphenyl-1,2-ethylene glycol according to claim 1, characterized in that in step (2), the reaction is carried out under normal pressure.