Preparation method and application of CTF-2-AA-Cu material

Abstract

The invention relates to a preparation method and application of a CTF-2-AA-Cu material. According to the method, 2, 4, 6-trihydroxybenzene-1, 3, 5-tricarboxaldehyde, 4, 4 ', 4' '-(1, 3, 5-triazine-2, 4, 6-triyl) and 2-aminoterephthalic acid are used as raw materials, a CTF-2-AA material with a hierarchical pore structure is constructed through an acetic acid catalytic condensation reaction, and then Cu (II) active sites are anchored. The method shows excellent CH4 selectivity in a photocatalytic CO2 reduction reaction, and the yield is improved in a breakthrough manner compared with that of a traditional system.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of photocatalytic materials, and particularly relates to preparation of a CTF-2-AA-Cu porous organic material and performance of the material in photocatalytic reduction of CO2. BACKGROUND

[0002] The large-scale use of fossil energy has led to a continuous increase in atmospheric CO2 concentration, triggering global climate anomalies. Developing clean energy conversion and carbon cycle technologies has become an important issue for the international community. Inspired by natural photosynthesis, artificial photosynthesis systems convert CO2 into high-value chemicals through photocatalyst materials, which are considered an effective way to achieve carbon neutrality. Photocatalytic CO2 reduction technology has developed over the decades. Early metal oxide semiconductors regulate the migration of photo-generated carriers through band engineering. However, such materials have significant defects, such as high charge recombination rate, weak visible light response, and photo-corrosion, which seriously restrict their practical application. To overcome the limitations of inorganic materials, covalent triazine frameworks (CTFs) with strong programmable molecular structure and adjustable electronic properties have become a research hotspot.

[0003] In the field of photocatalysis, breakthroughs have been continuously made in research based on covalent organic frameworks (COFs). Currently, strategies such as developing donor-acceptor (D-A) structures, constructing ordered-disordered heterojunction systems, and introducing metal active sites have effectively improved the efficiency of exciton separation. However, existing COF-based catalytic materials have deficiencies in the selectivity and generation rate of methane generated by high-efficiency catalytic reduction of CO2. The methane production rate of the covalent triazine organic polymer photocatalyst prepared in patent CN109261203B is <20 μmol·g -1 ·h -1 . The methane selectivity of the copper@covalent triazine organic polymer catalyst prepared in patent CN110721743B is as high as 98%, but the production rate is only 16.89 μmol·g -1 ·h -1 . The conjugated microporous polymer catalyst Tx-TzTz-CMP-2 developed in the literature (ACS Catal.2023, 13, 12142-12152) achieved a methane production rate of up to 300.62 μmol·g -1 ·h -1 , but the selectivity was only 71.2%. Although the catalyst PTA-PQ reported in the literature (J. Am. Chem. Soc.2021, 143, 16284-16292) achieved a methane production rate of 2150 μmol·g -1 ·h -1Methane yield and 90.2% methane selectivity, but the catalyst needs metal palladium, which greatly increases the preparation cost. In addition, the above-mentioned catalysts are all catalyzing CO2 reduction under oxygen-free conditions, which cannot meet the reduction of CO2 in the real oxygen environment, greatly limiting their large-scale application. SUMMARY

[0004] The present application aims to provide a preparation method and application of CTF-2-AA-Cu material to overcome the limitations of the current technology. The method adopts a multi-component synergistic strategy, using 2,4,6-trihydroxybenzene-1,3,5-triformaldehyde, 4,4',4''-(1,3,5-triazine-2,4,6-triazyl) and 2-amino terephthalic acid (2-AA) as precursors, constructing CTF-2-AA material with hierarchical pore structure through acetic acid catalyzed condensation reaction, and anchoring Cu(II) active sites in situ by one-pot method. Among them, the introduction of 2-amino terephthalic acid can regulate the π-π conjugation degree of COF material, while maintaining the high crystallinity and porous structure of the material, the local electronic distribution characteristics of COF are restructured, effectively balancing the process of exciton dissociation and carrier migration. The synchronously loaded Cu(II) species not only significantly accelerates the electron transport kinetics, but also forms high-activity catalytic centers through the construction of metal-organic interface, showing excellent CH4 selectivity in the photocatalytic CO2 reduction reaction, and the yield is breakthroughly improved compared with the traditional system.

[0005] The technical scheme of the present application is:

[0006] A preparation method of CTF-2-AA-Cu material, comprising the following steps:

[0007] Step 1: disperse 2,4,6-trihydroxybenzene-1,3,5-triformaldehyde, 4,4',4''-(1,3,5-triazine-2,4,6-triazyl) triphenylamine and 2-amino terephthalic acid in a mixed solution, ultrasonic dispersion treatment for 10-20 min, add acetic acid aqueous solution in the obtained mixed solution, seal by freeze-circulation-degassing, heat the sealed tube at 110-130℃ for 2-5 days, separate the solid by filtration, wash repeatedly with DMF and THF, put the obtained solid into a vacuum drying oven and dry at 50-70℃ for 6-12 hours to obtain the product CTF-2-AA;

[0008] Among them, the molar ratio of the materials is 2,4,6-trihydroxybenzene-1,3,5-triformaldehyde: 4,4',4''-(1,3,5-triazine-2,4,6-triazyl) triphenylamine: 2-amino terephthalic acid = 4-20: 3-17: 3-9; 5-20 mmol of 2,4,6-trihydroxybenzene-1,3,5-triformaldehyde and 0.1-1.0 mL of acetic acid aqueous solution are added per 30 mL of mixed solution;

[0009] The concentration of the acetic acid aqueous solution is 3-6M;

[0010] The mixed solution is composed of mesitylene and 1,4-dioxane, and the volume ratio of mesitylene to 1,4-dioxane is 1:1.

[0011] Step 2: disperse CTF-2-AA and Cu(NO3)2·H2O into methanol, ultrasonic treatment for 10-20 min, to obtain a mixed solution; then heat and stir the mixed solution at 60-80℃ for 6-12 hours, collect the precipitate by filtration, wash with methanol and water respectively, and then place the obtained solid into a vacuum drying oven for drying at 50-70℃ for 10-15 hours, to obtain the product CTF-2-AA-Cu.

[0012] wherein 2-50 mg of CTF-2-AA and 1-40 mg of Cu(NO3)2·H2O are added per 20 mL of methanol;

[0013] The application of the CTF-2-AA-Cu material prepared by the method is for photocatalytic reduction of CO2 under aerobic conditions.

[0014] Specifically includes the following steps:

[0015] Disperse CTF-2-AA-Cu in a mixed solution, and then perform photocatalytic reaction under the irradiation of a 100-500W xenon lamp (λ≥420nm) in a sealed and mixed gas atmosphere;

[0016] wherein 1-10 mg of CTF-2-AA-Cu is added per 10 mL of mixed solution; the mixed solution is composed of deionized water, triethanolamine and acetonitrile, and the volume ratio of deionized water: triethanolamine: acetonitrile is 1:0.5-2:2-5;

[0017] The mixed gas is 80%-95% CO2 and 20%-5% O2 gas in volume percentage.

[0018] The beneficial effects of the present application are:

[0019] (1) The present application first coordinates metal in a three-component defect COF, and successfully synthesizes a CTF-2-AA-Cu porous organic material.

[0020] (2) The CTF-2-AA-Cu prepared by the present application is used as a photocatalyst, and the rate of reducing CO2 to CH4 under aerobic conditions is 350.3μmol·g -1 ·h -1 , and the methane selectivity is maintained at 95%.

[0021] (3) The application provides a potential solution for photocatalytic reduction of CO2 to prepare methane under aerobic conditions, and has good practical value. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 X-ray powder diffraction patterns of CTF, CTF-2-AA and CTF-2-AA-Cu materials;

[0023] Figure 2 Transmission electron microscopy (TEM) images of CTF-2-AA-Cu materials with a molar ratio of 5:4:3;

[0024] Figure 3 Infrared spectra of CTF, CTF-2-AA and CTF-2-AA-Cu materials;

[0025] Figure 4 Performance of photocatalytic reduction of CTF, CTF-2-AA and CTF-2-AA-Cu materials to CH4.

[0026] DETAILED DESCRIPTION

[0027] The application will be further described in detail below with reference to the examples. The following examples only illustrate the method of the application, so as to better understand the application, and thus should not be regarded as limiting the scope of the application.

[0028] Example 1: Preparation of CTF-2-AA-Cu (molar ratio 10:9:3)

[0029] Step 1: Disperse 2,4,6-trihydroxybenzene-1,3,5-trimethylaldehyde (10 mmol), 4,4',4''-(1,3,5-triazine-2,4,6-triazyl) triphenylamine (9 mmol) and 2-amino terephthalic acid (3 mmol) in a mixed solution of mesitylene and 1,4-dioxane (30 mL) with a volume ratio of 1:1, and ultrasonically disperse for 15 min. Add 0.2 mL of 6M aqueous acetic acid to the mixture, and after three cycles of freezing-circulation-degassing, seal. Place the sealed tube in a 120℃ oven and react for 3 days. After the reaction is completed, filter and collect the solid, and wash with DMF and THF for 3 times respectively, and vacuum dry at 60℃ for 12h to obtain a yellow solid product CTF-2-AA.

[0030] Step 2: Disperse 20mg of CTF-2-AA and 17.1mg of Cu(NO3)2·H2O in 20mL of methanol, and ultrasonically treat for 15min. Stir and heat the mixture at 80℃ for 6h, filter and collect the precipitate, and wash with 10mL of methanol and 10mL of deionized water for 3 times, and vacuum dry at 60℃ for 12h to obtain a solid product CTF-2-AA-Cu.

[0031] Example 2: Preparation of CTF-2-AA-Cu (molar ratio 20:17:9)

[0032] The amount of substance of the raw materials in Step 1 was adjusted to 2,4,6-trihydroxybenzene-1,3,5-tricarboxaldehyde (20 mmol), 4,4',4”-(1,3,5-triazine-2,4,6-triyl) triphenylamine (17 mmol) and 2-amino terephthalic acid (9 mmol), and the remaining steps were the same as Example 1.

[0033] Example 3-5: Preparation of CTF-2-AA-Cu with different molar ratios

[0034] Steps 1 and 2 of Example 1 were repeated with molar ratios of 5:4:3, 4:3:3 and 10:7:9 (2,4,6-trihydroxybenzene-1,3,5-tricarboxaldehyde:4,4',4”-(1,3,5-triazine-2,4,6-triyl) triphenylamine:2-amino terephthalic acid) respectively, to obtain CTF-2-AA-Cu materials with different structures.

[0035] Photocatalytic CO2 reduction performance test effect Example 1:

[0036] 5 mg of CTF-2-AA-Cu (product of Example 3) was dispersed in a mixture of 2 mL of deionized water, 2 mL of triethanolamine and 6 mL of acetonitrile. The system was sealed and mixed gas with a volume percentage of 88% CO2 and 12% O2 was introduced to exclude air, and then photocatalytic reaction was carried out under irradiation of a 300 W xenon lamp (λ≥420 nm). The reaction products were analyzed by gas chromatography (FL9790 PIUS), and the CH4 generation rate was calculated to be 350.3 μmol·g -1 ·h -1 .

[0037] Photocatalytic CO2 reduction performance test effect Example 2:

[0038] 5 mg of CTF-2-AA-Cu (product of Example 3) was dispersed in a mixture of 2 mL of deionized water, 2 mL of triethanolamine and 6 mL of acetonitrile. The system was sealed and mixed gas with a volume percentage of 95% CO2 and 5% O2 was introduced to exclude air, and then photocatalytic reaction was carried out under irradiation of a 100 W xenon lamp (λ≥420 nm). The reaction products were analyzed by gas chromatography (FL9790 PIUS), and the CH4 generation rate was calculated to be 2.90 μmol·g -1 ·h -1 .

[0039] Photocatalytic CO2 reduction performance test effect Example 3:

[0040] 5mg CTF-2-AA-Cu (product of Example 3) was dispersed in 2 mL deionized water, 2 mL triethanolamine and 6 mL acetonitrile mixed solution. The system was sealed and mixed gas of volume percentage of 80% CO2 and 20% O2 was introduced to exclude air, and then photocatalytic reaction was carried out under 500W xenon lamp (λ≥420nm) irradiation. The reaction product was analyzed by gas chromatography (FL9790 PIUS), and the CH4 generation rate was calculated as 185.0 μmol·g -1 ·h -1 .

[0041] Photocatalytic CO2 reduction performance test effect Examples 4-8:

[0042] 5mg CTF-2-AA-Cu (product of Example 1, 2, 4, 5) was dispersed in 2 mL deionized water, 2 mL triethanolamine and 6 mL acetonitrile mixed solution, respectively. The system was sealed and mixed gas of volume percentage of 88% CO2 and 12% O2 was introduced to exclude air, and then photocatalytic reaction was carried out under 300W xenon lamp (λ≥420nm) irradiation. The reaction product was analyzed by gas chromatography (FL9790 PIUS), and the CH4 generation rate was calculated as 116.8 μmol·g -1 ·h -1 , 170.2 μmol·g -1 ·h -1 , 235.5 μmol·g -1 ·h -1 , 165.2 μmol·g -1 ·h -1 .

[0043] The details of the present application are known technology.

Claims

1. A method for preparing a CTF-2-AA-Cu material, characterized by: The following steps are involved: Step 1: 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde, 4,4',4"-(1,3,5-triazine-2,4,6-triyl)triphenylamine and 2-aminoterephthalic acid are dispersed in a mixed solution, and ultrasonic dispersion is performed for 10 to 20 minutes. An acetic acid aqueous solution is added to the obtained mixed solution, and the mixture is sealed by freezing-circulating-degasting. The sealed tube is heated at 110 to 130° C. for 2 to 5 days, and the solid is separated by filtration, washed with DMF and THF, and the obtained solid is dried at 50 to 70° C. for 6 to 12 hours to obtain the product CTF-2-AA; The material molar ratio is 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde:4,4',4"-(1,3,5-triazine-2,4,6-triyl)triphenylamine:2-aminoterephthalic acid = 4-20:3-17:3-9; 5-20 mmol of 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde and 0.1-1.0 mL of acetic acid aqueous solution are added to every 30 mL of the mixed solution; The composition of the mixed solution is mesitylene and 1,4-dioxane; Step 2: CTF-2-AA and Cu(NO3)2·H2O are dispersed in methanol and ultrasonically treated for 10 to 20 minutes to obtain a mixed solution; the mixed solution is then heated and stirred at 60 to 80°C for 6 to 12 hours, the precipitate is collected by filtration, washed with methanol and water, respectively, and the resulting solid is dried at 50 to 70°C for 10 to 15 hours to obtain the product CTF-2-AA-Cu; Wherein, 2 to 50 mg of CTF-2-AA and 1 to 40 mg of Cu(NO3)2·H2O were added to every 20 mL of methanol.

2. The method for preparing the CTF-2-AA-Cu material according to claim 1, wherein: The concentration of the acetic acid aqueous solution is 3 to 6M.

3. The method for preparing the CTF-2-AA-Cu material according to claim 1, wherein: In the mixed solution in step 1, the volume ratio of mesitylene to 1,4-dioxane is 1:

1.

4. Application of the CTF-2-AA-Cu material prepared by the method of claim 1, characterized in that: Used for photocatalytic CO2 reduction under aerobic conditions.

5. The use according to claim 4, characterized in that The steps include: CTF-2-AA-Cu was dispersed in the mixed solution and then photocatalytically reacted under irradiation of a 100-500W xenon lamp (λ≥420nm) in a sealed, mixed gas atmosphere; Wherein, 1 to 10 mg of CTF-2-AA-Cu is added to every 10 mL of the mixed solution; the composition of the mixed solution is deionized water, triethanolamine and acetonitrile, and the volume ratio of deionized water: triethanolamine: acetonitrile is 1:0.5 to 2:2 to 5; The mixed gas is 80% to 95% CO2 and 20% to 5% O2 gas in volume percentage.

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