Orthogonal carbon nitride composite material, preparation method and application thereof, and preparation method of 2, 5-diformyl furan

Abstract

The invention belongs to the technical field of photocatalytic material preparation, and provides an orthogonal carbon nitride composite material, a preparation method and application thereof, and a preparation method of 2, 5-diformyl furan. The preparation method disclosed by the invention comprises the following steps: mixing a carbon nitride precursor with 2, 1, 3-benzothiazole-4, 7-dinitrile, and calcining at 300-400 DEG C to obtain the orthogonal carbon nitride composite material. According to the preparation method, a carbon nitride precursor and 2, 1, 3-benzothiazole-4, 7-dinitrile (BTDN) are used as raw materials, the calcination temperature is controlled to be 300-400 DEG C, and the orthorhombic carbon nitride composite material with the orthorhombic crystal structure is obtained. By adding small organic molecules BTDN, adjusting the molecular spacing of a heptazine ring in carbon nitride, regulating and controlling the electronic structure and energy band structure of carbon nitride, the light absorption range of carbon nitride is widened, the separation efficiency of photon-generated carriers is improved, and then the photocatalytic efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of photocatalytic materials, and particularly relates to an orthorhombic carbon nitride composite material, a preparation method and an application thereof, and a preparation method of 2,5-diformylfuran. Background Art

[0002] Non-metallic carbon materials, such as graphitic carbon nitride (g-C3N4), graphene, carbon nanotubes, etc., have long been hot materials in the research field of photocatalysis. As a non-metallic organic semiconductor photocatalytic material, carbon nitride has received extensive attention from chemists. However, the intrinsic carbon nitride has a narrow light absorption range and the photo-generated carriers are easily recombined, which affects its photocatalytic performance. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide an orthorhombic carbon nitride composite material, a preparation method and an application thereof, and a preparation method of 2,5-diformylfuran. The orthorhombic carbon nitride composite material of the present invention has a wide light absorption range, improves the separation efficiency of photo-generated carriers, and improves the photocatalytic efficiency.

[0004] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0005] The present invention provides a preparation method of an orthorhombic carbon nitride composite material, comprising the following steps:

[0006] Mix a carbon nitride precursor and 2,1,3-benzothiazole-4,7-dicarbonitrile, and perform calcination to obtain the orthorhombic carbon nitride composite material;

[0007] The temperature of the calcination is 300-400 °C;

[0008] The carbon nitride precursor is an organic amine.

[0009] Preferably, the organic amine includes urea or melamine.

[0010] Preferably, the mass ratio of the carbon nitride precursor to 2,1,3-benzothiazole-4,7-dicarbonitrile is 10-60:1.

[0011] Preferably, the heating rate to the temperature of the calcination is 1-10 °C / min.

[0012] Preferably, the calcination is carried out in an air atmosphere.

[0013] Preferably, the heat preservation time of the calcination is 0.5-1.5 h.

[0014] The present invention also provides an orthorhombic carbon nitride composite material prepared by the preparation method described in the above technical solution.

[0015] The present invention also provides an application of the orthorhombic carbon nitride composite material described in the above technical solution in the photocatalytic preparation of 2,5-diformylfuran from 5-hydroxymethylfurfural.

[0016] The present invention also provides a method for preparing 2,5-diformylfuran, comprising the following steps:

[0017] Mix 5-hydroxymethylfurfural (HMF), an additive, a catalyst, and an organic solvent to obtain a raw material solution;

[0018] The raw material solution is subjected to a photocatalytic reaction under illumination conditions to obtain the 2,5-diformylfuran (DFF);

[0019] The catalyst is the orthorhombic carbon nitride composite material described in the above technical solution.

[0020] Preferably, in the raw material solution, the concentration of 5-hydroxymethylfurfural is 0.05 - 0.2 mol / L, the concentration of the additive is 0.05 - 0.2 mol / L, and the concentration of the catalyst is 0.5 - 1 mg / mL; the additive is an inorganic acid or an organic acid;

[0021] The light source for the illumination is a xenon lamp, and the wavelength of the xenon lamp is 300 - 800 nm.

[0022] The present invention provides a method for preparing an orthorhombic carbon nitride composite material.

[0023] The preparation method of the present invention uses a carbon nitride precursor (organic amine) and 2,1,3-benzothiazole-4,7-dicarbonitrile (BTDN) as raw materials, controls the calcination temperature to be 300 - 400 °C, and obtains an orthorhombic carbon nitride composite material with an orthorhombic crystal structure. By adding the organic small molecule BTDN, the molecular spacing of the heptazine ring in the carbon nitride is adjusted, the electronic structure and energy band structure of the carbon nitride are regulated, the light absorption range of the carbon nitride is broadened, the separation efficiency of photo-generated carriers is improved, and thus the photocatalytic efficiency is enhanced. Description of the Drawings

[0024] Figure 1 It is a schematic diagram of the principle for preparing an orthorhombic carbon nitride composite material using urea and melamine as organic amines;

[0025] Figure 2 It is a scanning electron microscope photograph of BTDN-u-Melon-40-380 obtained in Example 3;

[0026] Figure 3 It is a transmission electron microscope and element mapping diagram of BTDN-u-Melon-40-380 obtained in Example 3;

[0027] Figure 4X-ray photoelectron spectroscopy diagrams of BTDN-u-Melon-40-380 obtained in Example 3 (corresponding to BTDN-u-Melon in the figure) and u-Melon obtained in Comparative Example 1;

[0028] Figure 5 XRD pattern (left) and two-dimensional planar structure (right) of BTDN-u-Melon-40-380 obtained in Example 3 (corresponding to BTDN-u-Melon in the figure);

[0029] Figure 6 UV-visible diffuse reflection spectroscopy diagrams of u-Melon obtained in Comparative Example 1 and BTDN-u-Melon-40-380 obtained in Example 3 (corresponding to BTDN-u-Melon in the figure);

[0030] Figure 7 Photocurrent response diagrams of u-Melon obtained in Comparative Example 1 and BTDN-u-Melon-40-380 obtained in Example 3 (corresponding to BTDN-u-Melon in the figure);

[0031] Figure 8 Cyclic experiment test results of BTDN-u-Melon-40-380 obtained in Example 3;

[0032] Figure 9 1H nuclear magnetic spectrum diagram of the product 2,5-diformylfuran catalyzed by BTDN-u-Melon-40-380 obtained in Example 3. Detailed implementation manners

[0033] The present invention provides a preparation method of an orthorhombic carbon nitride composite material, comprising the following steps:

[0034] Mixing a carbon nitride precursor and 2,1,3-benzothiazole-4,7-dicarbonitrile, and performing calcination to obtain the orthorhombic carbon nitride composite material;

[0035] The temperature of the calcination is 300-400 °C;

[0036] The carbon nitride precursor is an organic amine.

[0037] Unless otherwise specified, the raw materials used in the present invention are preferably commercially available products.

[0038] In the present invention, the carbon nitride precursor preferably includes urea or melamine, and further preferably urea.

[0039] In the present invention, the mass ratio of the carbon nitride precursor to 2,1,3-benzothiazole-4,7-dicarbonitrile is preferably 10 to 60:1, specifically preferably 10:1, 20:1, 30:1, 40:1, 50:1 or 60:1.

[0040] In the present invention, the method of mixing the carbon nitride precursor and 2,1,3-benzothiazole-4,7-dicarbonitrile is preferably grinding and mixing.

[0041] In the present invention, the heating rate for heating to the calcination temperature is preferably 1 to 10 °C / min, specifically preferably 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 6 °C / min, 7 °C / min, 8 °C / min, 9 °C / min or 10 °C / min.

[0042] In the present invention, the calcination temperature is 300 to 400 °C, specifically preferably 300 °C, 310 °C, 320 °C, 330 °C, 340 °C, 350 °C, 360 °C, 370 °C, 380 °C, 390 °C or 400 °C.

[0043] In the present invention, the calcination is preferably carried out in an air atmosphere.

[0044] In the present invention, the heat preservation time of the calcination is preferably 0.5 to 1.5 h, specifically preferably 0.5 h, 1 h or 1.5 h.

[0045] In the present invention, the calcination is preferably carried out in a muffle furnace.

[0046] After the calcination is completed, the present invention preferably further includes: naturally cooling the obtained material to room temperature to obtain the orthorhombic carbon nitride composite material.

[0047] In the present invention, an organic amine is used as the carbon nitride precursor for calcination, and carbon nitride is formed by polymerization; the cyano group (-CN) in 2,1,3-benzothiazole-4,7-dicarbonitrile can combine with the amino group (-NH2) in the heptazine ring of carbon nitride. The introduction of 2,1,3-benzothiazole-4,7-dicarbonitrile can adjust the molecular spacing of carbon nitride, and then regulate the electronic structure and energy band structure of carbon nitride, broaden the light absorption range of carbon nitride, improve the separation efficiency of photogenerated carriers, and thus improve the photocatalytic efficiency.

[0048] Figure 1 is a schematic diagram of the principle for preparing the orthorhombic carbon nitride composite material using urea and melamine as organic amines. From Figure 1It can be seen that the cyano group (-CN) in 2,1,3-benzothiazole-4,7-dicarbonitrile can combine with the amino group (-NH2) in the heptazine ring of carbon nitride. The introduction of 2,1,3-benzothiazole-4,7-dicarbonitrile can adjust the molecular spacing of carbon nitride, thereby regulating the electronic structure and energy band structure of carbon nitride, broadening the light absorption range of carbon nitride, improving the separation efficiency of photogenerated carriers, and further enhancing the photocatalytic efficiency.

[0049] The present invention also provides an orthorhombic carbon nitride composite material prepared by the preparation method described in the above technical solution. In the present invention, the crystal structure of the orthorhombic carbon nitride composite material is an orthorhombic crystal; at the same time, the introduction of the organic small molecule BTDN can adjust the molecular spacing of the heptazine ring in carbon nitride, regulate the electronic structure and energy band structure of carbon nitride, broaden the light absorption range of carbon nitride, improve the separation efficiency of photogenerated carriers, and further enhance the photocatalytic efficiency.

[0050] The present invention also provides the application of the orthorhombic carbon nitride composite material described in the above technical solution in the photocatalytic preparation of 2,5-diformylfuran from 5-hydroxymethylfurfural.

[0051] The present invention also provides a preparation method of 2,5-diformylfuran, comprising the following steps:

[0052] Mix 5-hydroxymethylfurfural, an additive, a catalyst and an organic solvent to obtain a raw material solution;

[0053] The raw material solution is subjected to a photocatalytic reaction under light irradiation to obtain the 2,5-diformylfuran;

[0054] The catalyst is the orthorhombic carbon nitride composite material described in the above technical solution.

[0055] The present invention mixes 5-hydroxymethylfurfural, an additive, a catalyst and an organic solvent to obtain a raw material solution.

[0056] In the present invention, the additive is preferably an inorganic acid or an organic acid, and more preferably an organic acid. In the present invention, the inorganic acid is preferably hydrochloric acid, sulfuric acid or nitric acid; the organic acid is preferably formic acid, acetic acid or citric acid, and more preferably citric acid.

[0057] In the present invention, the organic solvent is preferably a polar organic solvent, and the polar organic solvent preferably includes one or more of methanol, ethanol, acetonitrile, dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF), and more preferably acetonitrile.

[0058] In the present invention, in the raw material liquid, the concentration of 5-hydroxymethylfurfural is preferably 0.05 - 0.2 mol / L, specifically preferably 0.05 mol / L, 0.1 mol / L, 0.15 mol / L or 0.2 mol / L; the concentration of the additive is preferably 0.05 - 0.2 mol / L, specifically preferably 0.05 mol / L, 0.1 mol / L, 0.15 mol / L or 0.2 mol / L; and the concentration of the catalyst is preferably 0.5 - 1 mg / mL, specifically preferably 0.5 mg / mL, 0.6 mg / mL, 0.7 mg / mL, 0.8 mg / mL, 0.9 mg / mL or 1 mg / mL.

[0059] In the present invention, the mixing of 5-hydroxymethylfurfural, the additive, the catalyst and the organic solvent preferably comprises the following steps: after mixing 5-hydroxymethylfurfural, the additive and the organic solvent, the catalyst is added.

[0060] After obtaining the raw material liquid, the raw material liquid in the present invention undergoes a photocatalytic reaction under the condition of light irradiation to obtain the 2,5-diformylfuran.

[0061] In the present invention, the light source for the light irradiation is preferably a xenon lamp, and the wavelength of the xenon lamp is preferably 300 - 800 nm.

[0062] In the present invention, the photocatalytic reaction is preferably carried out at room temperature.

[0063] After the photocatalytic reaction, the present invention preferably further comprises: subjecting the obtained reaction material liquid to column chromatography separation and purification to obtain the 2,5-diformylfuran. In the present invention, the eluent for the column chromatography separation and purification is preferably a mixed solvent of petroleum ether and ethyl acetate, and the volume ratio of petroleum ether to ethyl acetate in the mixed solvent is preferably 30:1.

[0064] In the present invention, the reaction formula for the preparation method of 2,5-diformylfuran is as follows:

[0065]

[0066] The following combines examples to detail the orthogonal carbon nitride composite material provided by the present invention, its preparation method and application, and the preparation method of 2,5-diformylfuran, but they should not be construed as limiting the protection scope of the present invention.

[0067] Example 1

[0068] Urea and 2,1,3-benzothiazole-4,7-dicarbonitrile (BTDN) were ground and mixed in a mass ratio of 10:1, 20:1, 30:1, 40:1, 50:1 or 60:1, then put into a crucible and placed in a muffle furnace. The temperature was raised to 380 °C at a rate of 5 °C / min for calcination for 1 h, and the calcination atmosphere was air; it was naturally cooled to room temperature to obtain an orthorhombic carbon nitride composite, denoted as BTDN-u-Melon-10-380, BTDN-u-Melon-20-380, BTDN-u-Melon-30-380, BTDN-u-Melon-40-380, BTDN-u-Melon-50-380 and BTDN-u-Melon-60-380.

[0069] 5-Hydroxymethylfurfural and citric acid were added to a quartz bottle containing acetonitrile, and then a series of orthorhombic carbon nitride composites were added as catalysts respectively to obtain a raw material solution; in the raw material solution, the concentration of 5-hydroxymethylfurfural was 0.1 mol / L, the concentration of citric acid was 0.1 mol / L, and the concentration of the catalyst was 0.6 mg / mL.

[0070] The photocatalytic reaction was carried out for 12 h under the irradiation of a xenon lamp (wavelength 300 - 800 nm). After the photocatalytic reaction was completed, column chromatography was used for separation and purification, and the eluent was a mixed solvent of petroleum ether and ethyl acetate, in which the volume ratio of petroleum ether to ethyl acetate was 30:1, to obtain the product 2,5-diformylfuran, and its yield was calculated.

[0071] The yields of 2,5-diformylfuran of different catalysts in Example 1 are shown in Table 1.

[0072] Table 1 Yields of 2,5-diformylfuran of different catalysts in Example 1

[0073]

[0074]

[0075] It can be seen from Table 1 that BTDN-u-Melon-40-380 has the best catalytic effect.

[0076] Example 2

[0077] Urea and 2,1,3-benzothiazole-4,7-dicarbonitrile (BTDN) were ground and mixed in a mass ratio of 40:1, then placed in a crucible and put into a muffle furnace. They were heated to 330 °C, 350 °C, 380 °C and 400 °C at a rate of 5 °C / min respectively for calcination for 1 h, and the calcination atmosphere was air. After natural cooling to room temperature, orthorhombic carbon nitride composites were obtained, denoted as BTDN-u-Melon-40-330, BTDN-u-Melon-40-350, BTDN-u-Melon-40-380, and BTDN-u-Melon-40-400.

[0078] 5-Hydroxymethylfurfural and citric acid were added to a quartz bottle containing acetonitrile, and then a series of orthorhombic carbon nitride composites were added as catalysts respectively to obtain a raw material solution. In the raw material solution, the concentration of 5-hydroxymethylfurfural was 0.1 mol / L, the concentration of citric acid was 0.1 mol / L, and the concentration of the catalyst was 0.6 mg / mL.

[0079] The photocatalytic reaction was carried out for 12 h under the irradiation of a xenon lamp (wavelength 300 - 800 nm). After the photocatalytic reaction was completed, column chromatography was used for separation and purification, and the eluent was a mixed solvent of petroleum ether and ethyl acetate. The volume ratio of petroleum ether to ethyl acetate in the mixed solvent was 30:1, and the product 2,5-diformylfuran was obtained and its yield was calculated.

[0080] The yields of 2,5-diformylfuran of different catalysts in Example 2 are shown in Table 2.

[0081] Table 2 Yields of 2,5-diformylfuran of different catalysts in Example 2

[0082] Serial number Yield of 2,5-diformylfuran BTDN-u-Melon-40-330 56％ BTDN-u-Melon-40-350 71％ BTDN-u-Melon-40-380 81％ BTDN-u-Melon-40-400 75％

[0083] It can be seen from Table 2 that the catalyst synthesized under the condition of 380 °C has the best effect.

[0084] Example 3

[0085] Urea and 2,1,3-benzothiazole-4,7-dicarbonitrile (BTDN) were ground and mixed in a mass ratio of 40:1, then placed in a crucible and put into a muffle furnace. They were heated to 380 °C at a rate of 5 °C / min for calcination for 1 h, and the calcination atmosphere was air. After natural cooling to room temperature, orthorhombic carbon nitride composites were obtained, denoted as BTDN-u-Melon-40-380.

[0086] 5-Hydroxymethylfurfural and citric acid were added to a quartz bottle containing acetonitrile, and then BTDN-u-Melon-40-380 was added as a catalyst respectively to obtain a raw material solution; in the raw material solution, the concentration of 5-hydroxymethylfurfural was 0.1 mol / L, the concentration of citric acid was 0.1 mol / L, and the concentration of the catalyst was 0.6 mg / mL.

[0087] The photocatalytic reaction was carried out for 12 h under the irradiation of a xenon lamp (wavelength 300 - 800 nm). After the photocatalytic reaction was completed, column chromatography was used for separation and purification, and the eluent was a mixed solvent of petroleum ether and ethyl acetate. Among them, the volume ratio of petroleum ether to ethyl acetate was 30:1, and the product 2,5-diformylfuran was obtained, and the obtained 2,5-diformylfuran was subjected to nuclear magnetic detection.

[0088] Example 4

[0089] BTDN-u-Melon-40-380 was prepared according to the preparation method of Example 3.

[0090] 5-Hydroxymethylfurfural and citric acid were added to quartz bottles containing acetonitrile, deionized water, ethanol, DMSO and DMF respectively, and then BTDN-u-Melon-40-380 was added as a catalyst respectively to obtain a raw material solution; in the raw material solution, the concentration of 5-hydroxymethylfurfural was 0.1 mol / L, the concentration of citric acid was 0.1 mol / L, and the concentration of the catalyst was 0.6 mg / mL.

[0091] The photocatalytic reaction was carried out for 12 h under the irradiation of a xenon lamp (wavelength 300 - 800 nm). After the photocatalytic reaction was completed, column chromatography was used for separation and purification, and the eluent was a mixed solvent of petroleum ether and ethyl acetate. Among them, the volume ratio of petroleum ether to ethyl acetate was 30:1, and the product 2,5-diformylfuran was obtained, and the yield of 2,5-diformylfuran was calculated.

[0092] Table 3 Yield of 2,5-diformylfuran in different organic solvents

[0093] Serial number Yield of 2,5-diformylfuran Acetonitrile 81％ Deionized water 32％ Ethanol 26％ DMSO 39％ DMF 43％

[0094] It can be seen from Table 3 that acetonitrile is the optimal organic solvent.

[0095] Example 5

[0096] BTDN-u-Melon-40-380 was prepared according to the preparation method of Example 3.

[0097] 5-Hydroxymethylfurfural, different additives (hydrochloric acid, sodium bicarbonate, formic acid, acetic acid and citric acid) were added into a quartz bottle containing acetonitrile, and then BTDN-u-Melon-40-380 was added as a catalyst respectively to obtain a raw material solution; in the raw material solution, the concentration of 5-hydroxymethylfurfural was 0.1 mol / L, the concentration of the additive was 0.1 mol / L, and the concentration of the catalyst was 0.6 mg / mL.

[0098] The photocatalytic reaction was carried out for 12 h under the irradiation of a xenon lamp (wavelength 300 - 800 nm). After the photocatalytic reaction was completed, column chromatography was used for separation and purification, and the eluent was a mixed solvent of petroleum ether and ethyl acetate, wherein the volume ratio of petroleum ether to ethyl acetate was 30:1, to obtain the product 2,5-diformylfuran, and the yield of 2,5-diformylfuran was calculated.

[0099] Table 4 Yields of 2,5-diformylfuran with different additives

[0100] Serial number Yield of 2,5-diformylfuran Hydrochloric acid 55％ Sodium bicarbonate 12％ Formic acid 46％ Acetic acid 66％ Citric acid 81％

[0101] It can be seen from Table 4 that citric acid is the optimal additive.

[0102] Example 6

[0103] BTDN-u-Melon-40-380 was prepared according to the preparation method of Example 3.

[0104] Different amounts of 5-hydroxymethylfurfural and citric acid were added into a quartz bottle containing acetonitrile, and then BTDN-u-Melon-40-380 was added as a catalyst respectively to obtain a raw material solution; in the raw material solution, the concentrations of 5-hydroxymethylfurfural were 0.05 mol / L, 0.1 mol / L, 0.15 mol / L or 0.2 mol / L respectively, the concentration of citric acid was 0.1 mol / L, and the concentration of the catalyst was 0.6 mg / mL.

[0105] The photocatalytic reaction was carried out for 12 h under the irradiation of a xenon lamp (wavelength 300 - 800 nm). After the photocatalytic reaction was completed, column chromatography was used for separation and purification, and the eluent was a mixed solvent of petroleum ether and ethyl acetate, wherein the volume ratio of petroleum ether to ethyl acetate was 30:1, to obtain the product 2,5-diformylfuran, and the yield of 2,5-diformylfuran was calculated.

[0106] Table 5 Yields of 2,5-diformylfuran with different 5-hydroxymethylfurfural concentrations

[0107] Serial number Yield of 2,5-diformylfuran 0.05 mol / L 72％ 0.1 mol / L 81％ 0.15 mol / L 76％ 0.2 mol / L 78％

[0108] It can be seen from Table 5 that the optimal concentration of 5-hydroxymethylfurfural in the raw material solution is 0.1 mol / L.

[0109] Example 7

[0110] Prepare BTDN-u-Melon-40-380 according to the preparation method of Example 3.

[0111] Add 5-hydroxymethylfurfural and citric acid into a quartz bottle containing acetonitrile, and then add different amounts of BTDN-u-Melon-40-380 as catalysts respectively to obtain a raw material solution; in the raw material solution, the concentration of 5-hydroxymethylfurfural is 0.1 mol / L, the concentration of citric acid is 0.1 mol / L, and the concentrations of the catalysts are 0.5 mg / mL, 0.6 mg / mL, 0.7 mg / mL, 0.9 mg / mL or 1 mg / mL respectively.

[0112] Carry out a photocatalytic reaction for 12 h under the irradiation of a xenon lamp (wavelength 300 - 800 nm). After the photocatalytic reaction is completed, separate and purify by column chromatography, and the eluent is a mixed solvent of petroleum ether and ethyl acetate, wherein the volume ratio of petroleum ether to ethyl acetate is 30:1, to obtain the product 2,5-diformylfuran, and calculate the yield of 2,5-diformylfuran.

[0113] Table 6 Yields of 2,5-diformylfuran at different catalyst concentrations

[0114] Serial number Yield of 2,5-diformylfuran 0.5 mg / mL 80％ 0.6 mg / mL 81％ 0.7 mg / mL 81％ 0.9 mg / mL 80％ 1 mg / mL 80％

[0115] It can be seen from Table 6 that the optimal catalyst concentration in the raw material solution is 0.6 mg / mL.

[0116] Comparative Example 1

[0117] The difference from Example 3 is that 2,1,3-benzothiazole-4,7-dicarbonitrile is not added to obtain a carbon nitride material, denoted as u-Melon.

[0118] Observe the morphology of the carbon nitride material obtained in Comparative Example 1 through a transmission electron microscope photo, and the result is: a blocky irregular shape.

[0119] Test the yield of 2,5-diformylfuran of the carbon nitride material obtained in Comparative Example 1 under the above conditions, and the result is: the yield of 2,5-diformylfuran is 12%.

[0120] Comparative Example 2

[0121] The difference from Example 3 is that 2,1,3-benzothiazole-4,7-dicarbonitrile is replaced by benzothiadiazole.

[0122] Observe the morphology of the orthorhombic carbon nitride composite material obtained in Comparative Example 2 through a transmission electron microscope photo, and the result is: a layered morphology.

[0123] Under the above conditions, the yield of 2,5-diformylfuran of the orthorhombic carbon nitride composite material obtained in Comparative Example 2 was tested, and the result was that the yield of 2,5-diformylfuran was 56%.

[0124] Figure 2 Figure 4 is the scanning electron microscope photograph of BTDN-u-Melon-40-380 obtained in Example 3. From Figure 2 it can be seen that the morphology of the obtained BTDN-u-Melon-40-380 is a multi-layer morphology.

[0125] Figure 3 Figure 5 is the transmission electron microscope and elemental mapping images of BTDN-u-Melon-40-380 obtained in Example 3. From Figure 3 it can be seen that the morphology of BTDN-u-Melon-40-380 is a massive morphology, and at the same time, the three elements of C, N, and S on the surface of the material are evenly distributed.

[0126] In order to explore the surface chemical properties and elemental chemical states of the orthorhombic carbon nitride composite material, X-ray photoelectron spectroscopy (XPS) was used to characterize u-Melon and BTDN-u-Melon-40-380 obtained in Example 3, and the results are as Figure 4 shown. Figure 4 Figure 6 is the X-ray photoelectron spectroscopy diagram of BTDN-u-Melon-40-380 (corresponding to BTDN-u-Melon in the figure) obtained in Example 3 and u-Melon obtained in Comparative Example 1. Figure 4 It shows that no obvious characteristic peak was detected in u-Melon within the S2p binding energy range, while a doublet structure appeared at 165.09 eV and 166.15 eV in BTDN-u-Melon-40-382; among them, the characteristic peak at 165.09 eV can be attributed to the S2p 3 / 2 orbital; the characteristic peak at 166.15 eV comes from the spin-orbit splitting peak of the S2p1 / 2 orbital, and this result further proves the successful introduction of BTDN.

[0127] In order to explore the precise structure of the orthorhombic carbon nitride composite material, the XRD pattern of the orthorhombic carbon nitride composite material was calculated by DFT theory, and the results are as Figure 5 shown, Figure 5 Figure 7 is the XRD pattern (left) and two-dimensional plane structure (right) of BTDN-u-Melon-40-380 obtained in Example 3 (corresponding to BTDN-u-Melon in the figure). In the left picture, the black is the actual XRD pattern of BTDN-u-Melon-40-380, and the blue is the theoretically calculated XRD pattern of BTDN-u-Melon-40-380. From Figure 5It can be seen that the theoretical XRD pattern (blue) of BTDN-u-Melon-40-380 coincides well with the actual XRD pattern (black), determining the precise structure of BTDN-u-Melon-40-380.

[0128] The optical absorption properties of the u-Melon obtained in Comparative Example 1 and BTDN-u-Melon-40-380 obtained in Example 3 were characterized by ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), and the results are as Figure 6 shown. Figure 6 Figure shows the ultraviolet-visible diffuse reflectance spectra of the u-Melon obtained in Comparative Example 1 and BTDN-u-Melon-40-380 (corresponding to BTDN-u-Melon in the figure) obtained in Example 3. It can be seen from Figure 6 this that the intrinsic absorption edge of u-Melon is located at 410 nm, and the absorption edge of BTDN-u-Melon-40-380 redshifts to 800 nm, expanding the visible light absorption range. The redshift of the absorption edge can be attributed to the molecular orbital hybridization and band structure change caused by the introduction of BTDN.

[0129] The photoelectrochemical properties of the u-Melon obtained in Comparative Example 1 and BTDN-u-Melon-40-380 obtained in Example 3 were studied using a photocurrent response test technique. The specific operation was as follows: The sample u-Melon or BTDN-u-Melon was ultrasonically dispersed in an ethanol solution, and 200 μL was taken and dropped onto the conductive side of the ITO (conductive glass), and then tested on a controllable intensity modulated photoelectrochemical spectrometer (model: Zahner-Zennium-PP211) to obtain photocurrent data. The results are as Figure 7 shown. Figure 7 Figure shows the photocurrent response diagrams of the u-Melon obtained in Comparative Example 1 and BTDN-u-Melon-40-380 (corresponding to BTDN-u-Melon in the figure) obtained in the example. As Figure 7 shown, under the same light illumination conditions, the photocurrent intensity of BTDN-u-Melon-40-380 is higher than that of u-Melon, indicating that BTDN-u-Melon-40-380 has a more excellent photogenerated electron-hole separation efficiency.

[0130] To evaluate the recycling performance of the orthorhombic carbon nitride composite as a catalyst, the catalyst was recovered from the photocatalytic reaction system by centrifugal separation, then washed twice with deionized water and twice with ethanol. The filtered catalyst was transferred to a beaker and dried at a constant temperature in an oven at 60 °C for use in the next photocatalytic reaction. Five consecutive cycle experiments were carried out on the catalyst, and the results are as Figure 8 shown. Figure 8The test results of the BTDN-u-Melon-40-380 cyclic experiment obtained in Example 3 Figure 8 Among them, Group A, Group B, and Group C refer to three parallel experiments. From Figure 8 It can be seen that: after 5 cycles of use, the yield of BTDN-u-Melon-40-380 still remains at 74%, indicating that BTDN-u-Melon-40-380 has good stability and reusability.

[0131] Figure 9 The 1H NMR spectrum of the product 2,5-diformylfuran catalyzed by BTDN-u-Melon-40-380 obtained in Example 3. From Figure 9 It can be seen that: the product is 2,5-diformylfuran.

[0132] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing an orthogonal carbon nitride composite material, characterized in that: The following steps are involved: Mixing a carbon nitride precursor and 2,1,3-benzothiazole-4,7-dicarbonitrile, and calcining the mixture to obtain the orthogonal carbon nitride composite material; The calcination temperature is 300-400°C; The carbon nitride precursor is an organic amine.

2. The preparation method according to claim 1, characterized in that: The organic amine includes urea or melamine.

3. The preparation method according to claim 1 or 2, characterized in that: The mass ratio of the carbon nitride precursor to 2,1,3-benzothiazole-4,7-dicarbonitrile is 10 to 60:

1.

4. The preparation method according to claim 1, characterized in that: The heating rate to the calcination temperature is 1 to 10°C / min.

5. The preparation method according to claim 1, characterized in that: The calcination is performed under air atmosphere.

6. The preparation method according to claim 1, characterized in that: The calcination holding time is 0.5 to 1.5 hours.

7. An orthogonal carbon nitride composite material obtained by the preparation method according to any one of claims 1 to 6.

8. Use of the orthogonal carbon nitride composite material according to claim 7 in the photocatalytic preparation of 2,5-diformylfuran from 5-hydroxymethylfurfural.

9. A method for preparing 2,5-diformylfuran, characterized in that: The following steps are involved: Mixing 5-hydroxymethylfurfural, an additive, a catalyst and an organic solvent to obtain a raw material liquid; The raw material liquid undergoes a photocatalytic reaction under light irradiation to obtain the 2,5-diformylfuran; The catalyst is the orthogonal carbon nitride composite material as described in claim 7.

10. The preparation method according to claim 9, characterized in that: In the raw material liquid, the concentration of 5-hydroxymethylfurfural is 0.05-0.2 mol / L, the concentration of the additive is 0.05-0.2 mol / L, and the concentration of the catalyst is 0.5-1 mg / mL; the additive is an organic acid or an inorganic acid; The light source of the illumination is a xenon lamp, and the wavelength of the xenon lamp is 300-800nm.

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