Transition metal-based composite materials for photocatalytic organic reactions and methods of making the same

Abstract

The present application relates to the field of photocatalytic organic reaction, in particular to a transition metal-based composite material for photocatalytic organic reaction and a preparation method thereof, which is used to solve the problems of poor light absorption effect, low catalytic activity, influence on photocatalytic efficiency and photocatalytic stability of the existing composite material based on transition metal functional groups, and limits its wide application; the preparation method grafts the metal porphyrin molecules with high cross-linking degree on the surface of carbon nanotubes, effectively improves the number of active sites participating in the photocatalytic reaction, thereby significantly enhances the photocatalytic activity, and because the metal porphyrin and the carbon nanotube can each play a unique advantage and cooperate with each other, the synergistic effect of the two can more effectively absorb photon energy, accelerate the generation and separation of photo-generated carriers, thereby greatly improving the photocatalytic activity of the composite material, can significantly improve the efficiency and stability of the photocatalytic organic reaction, so that the whole composite material performs extremely well in the photocatalytic reaction.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photocatalytic organic reactions, in particular to a transition metal-based composite material for photocatalytic organic reactions and a preparation method thereof. BACKGROUND

[0002] As an efficient, green and controllable synthesis method, photocatalytic organic reactions have attracted much attention in recent years. With the continuous development of science and technology, photocatalytic organic reactions have important application prospects in the fields of organic synthesis, environmental protection, etc. Among them, composite materials based on transition metal functional groups have become a frontier research direction of efficient photocatalysts due to their good photocatalytic performance, low preparation cost and easily controllable active sites. Common such composite materials include transition metal oxides, metal organic frameworks, etc., but their photocatalytic efficiency is still limited by the performance of the system itself and the absorption characteristics limited to the visible light region, resulting in poor light absorption effect, low catalytic activity, affecting the photocatalytic efficiency and photocatalytic stability, and limiting their wide application.

[0003] Therefore, it is of important theoretical significance and practical application value to develop a transition metal-based composite material for photocatalytic organic reactions and a preparation method thereof. SUMMARY

[0004] In order to overcome the above technical problems, the purpose of the present application is to provide a transition metal-based composite material for photocatalytic organic reactions and a preparation method thereof, which solves the problem of poor light absorption effect, low catalytic activity, affecting the photocatalytic efficiency and photocatalytic stability, and limiting the wide application of the existing composite materials based on transition metal functional groups.

[0005] The purpose of the present application can be achieved by the following technical solutions:

[0006] The preparation method of the transition metal-based composite material for photocatalytic organic reactions comprises the following steps:

[0007] Step one: multi-walled carbon nanotubes, concentrated sulfuric acid and concentrated nitric acid are added to a three-necked flask equipped with a stirrer and a thermometer, ultrasonic dispersion is carried out under the condition that the ultrasonic frequency is 40-50 kHz for 1-1.5 h, then stirring reaction is carried out under the condition that the temperature is 25-30℃ and the stirring rate is 300-400 r / min for 1-1.5 h, then the reaction is continued under the condition that the temperature is increased to 80-85℃ and stirring is carried out for 5-6 h, after the reaction is completed, the reaction product is cooled to room temperature, then centrifugation is carried out, the precipitate is washed with distilled water for 3-5 times, then it is placed in a vacuum drying oven and dried under the condition that the temperature is 60-65℃ for 2-3 h, to obtain acidified carbon nanotubes;

[0008] Step 2: Add acidified carbon nanotubes and thionyl chloride to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir at 25-30℃ and 300-400 r / min for 20-30 min. Then raise the temperature to 80-85℃ and stir for 10-15 h. After the reaction is complete, cool the reaction product to room temperature, centrifuge, wash the precipitate 3-5 times with distilled water, and then place it in a vacuum drying oven and dry at 60-65℃ for 2-3 h to obtain acyl chloride carbon nanotubes.

[0009] Step 3: Add 4-tetra(4-carboxyphenyl)porphyrin, N,N-dimethylformamide and chloroform to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube and reflux condenser. Purge with nitrogen and stir at 25-30℃ and 300-400 r / min for 1-1.5 h. Then add thionyl chloride and continue stirring under reflux for 5-6 h. After the reaction is complete, cool the reaction product to room temperature and then remove the solvent by rotary evaporation to obtain acylporphyrin chloride.

[0010] Step 4: Add acyl chloride carbon nanotubes, acyl chloride porphyrin, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and anhydrous methanol to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir the reaction at 25-30℃ and a stirring rate of 300-400 r / min for 2-2.5 h. Then add triethylenetetramine and continue stirring for 20-30 h. After the reaction is complete, centrifuge the reaction product and wash the precipitate 3-5 times with distilled water. Then place it in a vacuum drying oven and dry it at 30-35℃ for 3-4 h to obtain cross-linked porphyrin grafted carbon nanotubes.

[0011] Step 5: Crosslinked porphyrin-grafted carbon nanotubes, N,N-dimethylformamide, and chloroform are added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas is introduced for protection, and the reaction is stirred for 20-25 minutes at a temperature of 25-30℃ and a stirring rate of 300-400 r / min. Then, a transition metal salt is added, and the temperature is raised to 130-135℃, and the reaction is continued for 20-30 hours. After the reaction is completed, the reaction product is cooled to room temperature and then washed 3-5 times with anhydrous ethanol and distilled water in sequence. Then, it is placed in a vacuum drying oven and dried at a temperature of 80-85℃ for 8-10 hours to obtain a transition metal-based composite material for photocatalytic organic reactions.

[0012] As a further aspect of the present invention: the ratio of the amount of multi-walled carbon nanotubes, concentrated sulfuric acid and concentrated nitric acid used in step one is 2g:60-65mL:20-25mL.

[0013] As a further aspect of the present invention: the average diameter of the multi-walled carbon nanotubes in step one is 80 nm and the average length is 20 μm.

[0014] As a further aspect of the present invention, the concentrated sulfuric acid has a mass fraction of 96-98%.

[0015] As a further aspect of the present invention, the concentrated nitric acid has a mass fraction of 65-68%.

[0016] As a further aspect of the present invention: the ratio of the acidified carbon nanotubes to thionyl chloride in step two is 0.1g:20-25mL.

[0017] As a further aspect of the present invention: the ratio of the amounts of 4-tetra(4-carboxyphenyl)porphyrin, N,N-dimethylformamide, chloroform and thionyl chloride used in step three is 1g:7-9mL:50-55mL:1.5-3.5mL.

[0018] As a further embodiment of the present invention: the ratio of the amount of acyl chloride carbon nanotubes, acyl chloride porphyrin, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, anhydrous methanol and triethylenetetramine in step four is 0.1g:0.5-1.1g:0.3-0.5g:0.3-0.5g:80-100mL:0.5-0.9g.

[0019] As a further aspect of the present invention: the ratio of the cross-linked porphyrin-grafted carbon nanotubes, N,N-dimethylformamide, chloroform and transition metal salt in step five is 1g:7-9mL:50-55mL:9-13g.

[0020] As a further aspect of the present invention: the transition metal salt in step five is one of zinc acetate dihydrate, cobalt acetate tetrahydrate, and manganese acetate tetrahydrate.

[0021] As a further embodiment of the present invention: the transition metal-based composite material for photocatalytic organic reactions is prepared according to the preparation method of the transition metal-based composite material for photocatalytic organic reactions as described in the present invention.

[0022] The beneficial effects of this invention are:

[0023] The present invention relates to a transition metal-based composite material for photocatalytic organic reactions and its preparation method. The method involves treating multi-walled carbon nanotubes with a mixed acid of concentrated sulfuric acid and concentrated nitric acid to remove impurities and introduce active groups such as hydroxyl and carboxyl groups, resulting in acidified carbon nanotubes. The acidified carbon nanotubes are then treated with thionyl chloride to convert the carboxyl groups to acyl chloride groups, enhancing their reactivity and yielding acylchlorinated carbon nanotubes. Subsequently, thionyl chloride is used to treat 4-tetra(4-carboxyphenyl)porphyrin, converting the carboxyl groups to acyl chloride groups and enhancing its reactivity, yielding acylporphyrin. Finally, triethylenetetramine is used... Acyl chloride carbon nanotubes and acyl chloride porphyrins were treated to achieve full cross-linking, forming a highly cross-linked network structure, resulting in cross-linked porphyrin-grafted carbon nanotubes. Finally, the cross-linked porphyrin-grafted carbon nanotubes were reacted with a transition metal salt. The porphyrin rings on the cross-linked porphyrin-grafted carbon nanotubes and the transition metal ions in the transition metal salt formed a complex, forming a metalloporphyrin. This yielded a transition metal-based composite material for photocatalytic organic reactions. Porphyrins possess a large conjugated structure and strong absorption capacity for visible light. Incorporating transition metal ions can affect the light absorption characteristics of metalloporphyrins, thereby altering the electron distribution of the porphyrin rings and enhancing their light absorption capacity. Metalloporphyrins possess excellent light absorption capabilities, both in terms of absorption range and intensity. Under light irradiation, electrons in the metalloporphyrin molecule are excited from the ground state to the excited state, providing the energy basis for subsequent photocatalytic reactions. Carbon nanotubes are excellent conductive materials, and under light irradiation, electrons in carbon nanotubes are excited, forming photogenerated electrons and holes. These photogenerated electrons and holes are highly active and can participate in subsequent redox reactions. Therefore, fully cross-linking metalloporphyrins and carbon nanotubes to form a network structure allows for a close interaction between the two, making them appear as if they are connected by a network. A highly efficient bridge exists between metalloporphyrin and carbon nanotubes, each leveraging its unique advantages and working in tandem. When light shines on the transition metal matrix composite material, their synergistic effect during electron transfer enables more effective absorption of photon energy, accelerating the generation and separation of photogenerated carriers. This significantly enhances the photocatalytic activity of the composite material, substantially improving the efficiency and stability of photocatalytic organic reactions. Consequently, the entire composite material exhibits outstanding performance in photocatalytic reactions. Furthermore, the preparation method is simple, efficient, and highly reproducible, facilitating industrial production and making it highly valuable for practical industrial applications and scientific research. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1:

[0026] This embodiment describes a method for preparing a transition metal-based composite material for photocatalytic organic reactions, comprising the following steps:

[0027] Step 1: Add 2g of multi-walled carbon nanotubes with an average diameter of 80nm and an average length of 20μm, 60mL of 96% concentrated sulfuric acid, and 20mL of 65% concentrated nitric acid to a three-necked flask equipped with a stirrer and a thermometer. Disperse the mixture ultrasonically at a frequency of 40kHz for 1h. Then, stir the mixture at 25℃ and a stirring rate of 300r / min for 1h. After that, raise the temperature to 80℃ and continue stirring for 5h. After the reaction is complete, cool the reaction product to room temperature, centrifuge it, wash the precipitate three times with distilled water, and then place it in a vacuum drying oven and dry it at 60℃ for 2h to obtain acidified carbon nanotubes.

[0028] Step 2: Add 0.1g of acidified carbon nanotubes and 20mL of thionyl chloride to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Purge with nitrogen for protection and stir at 25℃ and 300r / min for 20min. Then raise the temperature to 80℃ and stir for 10h. After the reaction is complete, cool the reaction product to room temperature, centrifuge, wash the precipitate three times with distilled water, and then place it in a vacuum drying oven and dry at 60℃ for 2h to obtain acyl chloride carbon nanotubes.

[0029] Step 3: Add 1g of tetra(4-carboxyphenyl)porphyrin, 7mL of N,N-dimethylformamide and 50mL of chloroform to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube and reflux condenser. Purge with nitrogen and stir for 1h at 25℃ and 300r / min. Then add 1.5mL of thionyl chloride and continue stirring for 5h under reflux. After the reaction is completed, cool the product to room temperature and then remove the solvent by rotary evaporation to obtain acylporphyrin chloride.

[0030] Step 4: Add 0.1g of acyl chloride carbon nanotubes, 0.5g of acyl chloride porphyrin, 0.3g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 0.3g of N-hydroxysuccinimide, and 80mL of anhydrous methanol to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen and stir at 25℃ and 300r / min for 2h. Then add 0.5g of triethylenetetramine and continue stirring for 20h. After the reaction is complete, centrifuge the reaction product, wash the precipitate three times with distilled water, and then place it in a vacuum drying oven and dry at 30℃ for 3h to obtain cross-linked porphyrin grafted carbon nanotubes.

[0031] Step 5: Add 1g of cross-linked porphyrin-grafted carbon nanotubes, 7mL of N,N-dimethylformamide, and 50mL of chloroform to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir at 25℃ and 300r / min for 20min. Then add 9g of zinc acetate dihydrate and continue stirring at 130℃ for 20h. After the reaction is complete, cool the reaction product to room temperature and wash it three times with anhydrous ethanol and distilled water. Then place it in a vacuum drying oven and dry at 80℃ for 8h to obtain a transition metal-based composite material for photocatalytic organic reactions.

[0032] Example 2:

[0033] This embodiment describes a method for preparing a transition metal-based composite material for photocatalytic organic reactions, comprising the following steps:

[0034] Step 1: Add 2g of multi-walled carbon nanotubes with an average diameter of 80nm and an average length of 20μm, 62mL of 97% concentrated sulfuric acid, and 22mL of 67% concentrated nitric acid to a three-necked flask equipped with a stirrer and a thermometer. Sonicate the mixture at a frequency of 45kHz for 1.2h. Then, stir the mixture at 28℃ and a stirring rate of 350r / min for 1.2h. After that, raise the temperature to 82℃ and continue stirring for 5.5h. After the reaction is complete, cool the reaction product to room temperature, centrifuge it, wash the precipitate four times with distilled water, and then place it in a vacuum drying oven and dry it at 62℃ for 2.5h to obtain acidified carbon nanotubes.

[0035] Step 2: Add 0.1g of acidified carbon nanotubes and 22mL of thionyl chloride to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir at 28℃ and 350r / min for 25min. Then raise the temperature to 82℃ and stir for 12h. After the reaction is complete, cool the reaction product to room temperature, centrifuge, wash the precipitate four times with distilled water, and then place it in a vacuum drying oven and dry at 62℃ for 2.5h to obtain acyl chloride carbon nanotubes.

[0036] Step 3: Add 1g of tetra(4-carboxyphenyl)porphyrin, 8mL of N,N-dimethylformamide and 52mL of chloroform to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube and reflux condenser. Purge with nitrogen and stir at 28℃ and 350r / min for 1.2h. Then add 2.5mL of thionyl chloride and continue stirring under reflux for 5.5h. After the reaction is complete, cool the product to room temperature and then remove the solvent by rotary evaporation to obtain acylporphyrin chloride.

[0037] Step 4: Add 0.1g of acyl chloride carbon nanotubes, 0.8g of acyl chloride porphyrin, 0.4g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 0.4g of N-hydroxysuccinimide, and 90mL of anhydrous methanol to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen and stir at 28℃ and 350r / min for 2.2h. Then add 0.7g of triethylenetetramine and continue stirring for 25h. After the reaction is complete, centrifuge the reaction product, wash the precipitate four times with distilled water, and then place it in a vacuum drying oven and dry at 32℃ for 3.5h to obtain cross-linked porphyrin-grafted carbon nanotubes.

[0038] Step 5: Add 1g of cross-linked porphyrin-grafted carbon nanotubes, 8mL of N,N-dimethylformamide, and 52mL of chloroform to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir at 28℃ and 350r / min for 22min. Then add 11g of cobalt acetate tetrahydrate and continue stirring at 132℃ for 25h. After the reaction is complete, cool the reaction product to room temperature and wash it four times with anhydrous ethanol and distilled water. Then place it in a vacuum drying oven and dry at 82℃ for 9h to obtain a transition metal-based composite material for photocatalytic organic reactions.

[0039] Example 3:

[0040] This embodiment describes a method for preparing a transition metal-based composite material for photocatalytic organic reactions, comprising the following steps:

[0041] Step 1: Add 2g of multi-walled carbon nanotubes with an average diameter of 80nm and an average length of 20μm, 65mL of 98% concentrated sulfuric acid, and 25mL of 68% concentrated nitric acid to a three-necked flask equipped with a stirrer and a thermometer. Disperse the mixture ultrasonically at a frequency of 50kHz for 1.5h. Then, stir the mixture at 30℃ and a stirring rate of 400r / min for 1.5h. After that, raise the temperature to 85℃ and continue stirring for 6h. After the reaction is complete, cool the reaction product to room temperature, centrifuge it, wash the precipitate five times with distilled water, and then place it in a vacuum drying oven and dry it at 65℃ for 3h to obtain acidified carbon nanotubes.

[0042] Step 2: Add 0.1g of acidified carbon nanotubes and 25mL of thionyl chloride to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Purge with nitrogen for protection and stir at 30℃ and 400r / min for 30min. Then raise the temperature to 85℃ and stir for 15h. After the reaction is complete, cool the reaction product to room temperature, centrifuge, wash the precipitate 5 times with distilled water, and then place it in a vacuum drying oven and dry at 65℃ for 3h to obtain acyl chloride carbon nanotubes.

[0043] Step 3: Add 1g of 4-tetra(4-carboxyphenyl)porphyrin, 9mL of N,N-dimethylformamide and 55mL of chloroform to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube and reflux condenser. Purge with nitrogen and stir at 30℃ and 400r / min for 1.5h. Then add 3.5mL of thionyl chloride and heat to reflux and continue stirring for 6h. After the reaction is complete, cool the product to room temperature and then remove the solvent by rotary evaporation to obtain acylporphyrin chloride.

[0044] Step 4: Add 0.1g of acyl chloride carbon nanotubes, 1.1g of acyl chloride porphyrin, 0.5g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 0.5g of N-hydroxysuccinimide, and 100mL of anhydrous methanol to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen and stir at 30℃ and 400r / min for 2.5h. Then add 0.9g of triethylenetetramine and continue stirring for 30h. After the reaction is complete, centrifuge the reaction product, wash the precipitate 5 times with distilled water, and then place it in a vacuum drying oven and dry at 35℃ for 4h to obtain cross-linked porphyrin grafted carbon nanotubes.

[0045] Step 5: Add 1g of cross-linked porphyrin-grafted carbon nanotubes, 9mL of N,N-dimethylformamide, and 55mL of chloroform to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir at 30℃ and 400r / min for 25min. Then add 13g of manganese acetate tetrahydrate and continue stirring at 135℃ for 30h. After the reaction is complete, cool the reaction product to room temperature and wash it five times with anhydrous ethanol and distilled water. Then place it in a vacuum drying oven and dry at 85℃ for 10h to obtain a transition metal-based composite material for photocatalytic organic reactions.

[0046] Comparative Example 1:

[0047] This comparative example illustrates a method for preparing a transition metal-based composite material for photocatalytic organic reactions, comprising the following steps:

[0048] 1 g of 4-tetra(4-carboxyphenyl)porphyrin, 9 mL of N,N-dimethylformamide, and 55 mL of chloroform were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred at 30 °C and a stirring rate of 400 r / min for 25 min. Then, 13 g of manganese acetate tetrahydrate was added, and the mixture was heated to 135 °C and stirred for another 30 h. After the reaction was completed, the reaction product was cooled to room temperature, and the solvent was removed by rotary evaporation. The product was then washed five times with anhydrous ethanol and distilled water, and then placed in a vacuum drying oven and dried at 85 °C for 10 h to obtain a transition metal-based composite material for photocatalytic organic reactions.

[0049] Comparative Example 2:

[0050] This comparative example illustrates a method for preparing a transition metal-based composite material for photocatalytic organic reactions, comprising the following steps:

[0051] Step 1: Add 1g of 4-tetra(4-carboxyphenyl)porphyrin, 9mL of N,N-dimethylformamide and 55mL of chloroform to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube and reflux condenser. Purge with nitrogen and stir at 30℃ and 400r / min for 1.5h. Then add 3.5mL of thionyl chloride and heat to reflux and continue stirring for 6h. After the reaction is complete, cool the product to room temperature and then remove the solvent by rotary evaporation to obtain acylporphyrin chloride.

[0052] Step 2: 1.1 g of acetyloporphyrin chloride, 0.5 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 0.5 g of N-hydroxysuccinimide, and 100 mL of anhydrous methanol were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred at 30 °C and a stirring rate of 400 r / min for 2.5 h. Then, 0.9 g of triethylenetetramine was added and the mixture was stirred for another 30 h. After the reaction was completed, the solvent was removed by rotary evaporation of the reaction product. The product was then washed five times with distilled water and placed in a vacuum drying oven at 35 °C for 4 h to obtain polyporphyrin.

[0053] Step 3: Add 1g of polyporphyrin, 9mL of N,N-dimethylformamide and 55mL of chloroform to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Purge with nitrogen for protection and stir at 30℃ and 400r / min for 25min. Then add 13g of manganese acetate tetrahydrate and heat to 135℃ and continue stirring for 30h. After the reaction is complete, cool the reaction product to room temperature and remove the solvent by rotary evaporation. Then wash with anhydrous ethanol and distilled water five times in sequence. Then place in a vacuum drying oven and dry at 85℃ for 10h to obtain a transition metal-based composite material for photocatalytic organic reactions.

[0054] Comparative Example 3:

[0055] This comparative example illustrates a method for preparing a transition metal-based composite material for photocatalytic organic reactions, comprising the following steps:

[0056] Step 1: Add 2g of multi-walled carbon nanotubes with an average diameter of 80nm and an average length of 20μm, 65mL of 98% concentrated sulfuric acid, and 25mL of 68% concentrated nitric acid to a three-necked flask equipped with a stirrer and a thermometer. Disperse the mixture ultrasonically at a frequency of 50kHz for 1.5h. Then, stir the mixture at 30℃ and a stirring rate of 400r / min for 1.5h. After that, raise the temperature to 85℃ and continue stirring for 6h. After the reaction is complete, cool the reaction product to room temperature, centrifuge it, wash the precipitate five times with distilled water, and then place it in a vacuum drying oven and dry it at 65℃ for 3h to obtain acidified carbon nanotubes.

[0057] Step 2: Add 0.1g of acidified carbon nanotubes and 25mL of thionyl chloride to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Purge with nitrogen for protection and stir at 30℃ and 400r / min for 30min. Then raise the temperature to 85℃ and stir for 15h. After the reaction is complete, cool the reaction product to room temperature, centrifuge, wash the precipitate 5 times with distilled water, and then place it in a vacuum drying oven and dry at 65℃ for 3h to obtain acyl chloride carbon nanotubes.

[0058] Step 3: Add 1g of 4-tetra(4-carboxyphenyl)porphyrin, 9mL of N,N-dimethylformamide and 55mL of chloroform to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube and reflux condenser. Purge with nitrogen and stir at 30℃ and 400r / min for 1.5h. Then add 3.5mL of thionyl chloride and heat to reflux and continue stirring for 6h. After the reaction is complete, cool the product to room temperature and then remove the solvent by rotary evaporation to obtain acylporphyrin chloride.

[0059] Step 4: Add 0.1g of acyl chloride carbon nanotubes, 1.1g of acyl chloride porphyrin, 9mL of N,N-dimethylformamide, and 55mL of chloroform to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir at 30℃ and 400r / min for 25min. Then add 13g of manganese acetate tetrahydrate and continue stirring at 135℃ for 30h. After the reaction is complete, cool the reaction product to room temperature and remove the solvent by rotary evaporation. Then wash five times with anhydrous ethanol and distilled water. Finally, place in a vacuum drying oven and dry at 85℃ for 10h to obtain a transition metal-based composite material for photocatalytic organic reactions.

[0060] The transition metal-based composite material used for photocatalytic organic reactions was tested using the following method:

[0061] I. Catalytic oxidation of toluene

[0062] Accurately weigh 0.1g of the transition metal-based composite material for photocatalytic organic reactions from Examples 1-3 and Comparative Examples 1-3 and place it in a photochemical reactor. Then, measure 2g of toluene into the photochemical reactor. Secure the reactor, turn on the constant temperature circulating condensate system, and control the condensate temperature at 20°C. First, use CO at a flow rate of 10mL / min. 2，The photochemical reactor was purged with gas for 20 minutes to remove air. Then, the reactor outlet was closed, and the CO2 gas flow rate was increased to 5 mL / min. The reactor was then filled with CO2 gas for 10 minutes. The CO2 cylinder was then closed, and a 300W xenon lamp was turned on. After 11 hours of reaction, the xenon lamp and circulating condensate were turned off. The reaction solution was sonicated twice. All the product on the surface of the transition metal-based composite material used in the photocatalytic organic reaction was washed into an ethyl acetate solution. Vacuum filtration was then performed, and the filter cake was washed five times with ethyl acetate. The total amount of ethyl acetate added was 98 g. The concentration of toluene in the sample was determined using a GC9710 gas chromatograph, and the following formula was used:

[0063]

[0064] In the formula:

[0065] α 甲苯 Toluene conversion rate;

[0066] C 初始甲苯 This represents the initial toluene concentration;

[0067] C 反应后甲苯 This represents the concentration of toluene after the reaction.

[0068] II. Catalytic reaction of CO2 and methanol to synthesize dimethyl carbonate

[0069] Accurately weigh 0.1g of the transition metal-based composite material for photocatalytic organic reactions from Examples 1-3 and Comparative Examples 1-3 and place it in a photochemical reactor. Then, measure 2g of methanol into the photochemical reactor. Secure the reactor, turn on the constant-temperature circulating condensate system, and control the condensate temperature at 20°C. First, purge the photochemical reactor with CO2 gas at a flow rate of 10mL / min for 20min to remove air from the reactor. Then, close the gas outlet of the reactor and change the CO2 gas flow rate to 5mL / min to continue purging the photochemical reactor. The reactor was purged with CO2 gas for 10 minutes. The CO2 cylinder was then closed and a 300W xenon lamp was turned on. After 11 hours of reaction, the xenon lamp and circulating condensate were turned off. The reaction solution was sonicated twice. All the product on the surface of the transition metal-based composite material used for photocatalytic organic reaction was washed into an ethyl acetate solution, followed by vacuum filtration. The filter cake was washed five times with ethyl acetate, and the total amount of ethyl acetate added was 98g. The methanol concentration in the sample was tested using a GC9710 gas chromatograph, and the following formula was used:

[0070]

[0071] In the formula:

[0072] α甲醇 Methanol conversion rate;

[0073] C 初始甲醇 The initial methanol concentration;

[0074] C 反应后甲醇 This represents the methanol concentration after the reaction.

[0075] The test results are shown in the table below:

[0076] Sample Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 甲苯 , %]] ​ 88.14 90.39 95.53 78.45 86.92 90.06 甲醇 , %]] ​ 58.74 60.76 66.58 44.25 49.87 55.16

[0077] Referring to the data in the table above, and based on the comparison between Examples 1-3 and Comparative Examples 1-3, it can be seen that the transition metal-based composite material for photocatalytic organic reactions in this invention has excellent photocatalytic performance and effectively catalyzes the organic reactions.

[0078] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0079] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing transition metal-based composite materials for photocatalytic organic reactions, characterized in that, Includes the following steps: Step 1: Multi-walled carbon nanotubes, concentrated sulfuric acid and concentrated nitric acid are ultrasonically dispersed, and then stirred to react. After the reaction is completed, the reaction product is cooled, centrifuged, the precipitate is washed with distilled water and then dried to obtain acidified carbon nanotubes. Step 2: Acidified carbon nanotubes and thionyl chloride are stirred and reacted. After the reaction is completed, the reaction product is cooled, then centrifuged, the precipitate is washed with distilled water and then dried to obtain acyl chloride carbon nanotubes. Step 3: The reaction mixture of 4-tetra(4-carboxyphenyl)porphyrin, N,N-dimethylformamide and chloroform is stirred and reacted. Then, thionyl chloride is added and the reaction is stirred and reacted again. After the reaction is completed, the reaction product is cooled and then evaporated by rotary evaporation to obtain acylporphyrin chloride. Step 4: The acyl chloride carbon nanotubes, acyl chloride porphyrin, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide and anhydrous methanol were stirred and reacted. Then, triethylenetetramine was added and the reaction was continued with stirring. After the reaction was completed, the reaction product was centrifuged, the precipitate was washed with distilled water and then dried to obtain cross-linked porphyrin grafted carbon nanotubes. Step 5: Cross-linked porphyrin-grafted carbon nanotubes, N,N-dimethylformamide, and chloroform are stirred and reacted. Then, a transition metal salt is added and the reaction is stirred and continued. After the reaction is completed, the reaction product is cooled and then washed with anhydrous ethanol and distilled water in sequence, and then dried to obtain a transition metal-based composite material for photocatalytic organic reactions.

2. The method for preparing the transition metal-based composite material for photocatalytic organic reactions according to claim 1, characterized in that, In step one, the ratio of the amount of multi-walled carbon nanotubes, concentrated sulfuric acid, and concentrated nitric acid used is 2g:60-65mL:20-25mL.

3. The method for preparing the transition metal-based composite material for photocatalytic organic reactions according to claim 1, characterized in that, The multi-walled carbon nanotubes in step one have an average diameter of 80 nm and an average length of 20 μm. The concentrated sulfuric acid has a mass fraction of 96-98%, and the concentrated nitric acid has a mass fraction of 65-68%.

4. The method for preparing the transition metal-based composite material for photocatalytic organic reactions according to claim 1, characterized in that, In step two, the ratio of acidified carbon nanotubes to thionyl chloride is 0.1g:20-25mL.

5. The method for preparing the transition metal-based composite material for photocatalytic organic reactions according to claim 1, characterized in that, In step three, the ratio of the amounts of 4-carboxyphenyl porphyrin, N,N-dimethylformamide, chloroform, and thionyl chloride is 1g:7-9mL:50-55mL:1.5-3.5mL.

6. The method for preparing the transition metal-based composite material for photocatalytic organic reactions according to claim 1, characterized in that, In step four, the ratio of the amounts of acyl chloride carbon nanotubes, acyl chloride porphyrin, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, anhydrous methanol, and triethylenetetramine is 0.1g:0.5-1.1g:0.3-0.5g:0.3-0.5g:80-100mL:0.5-0.9g.

7. The method for preparing the transition metal-based composite material for photocatalytic organic reactions according to claim 1, characterized in that, In step five, the ratio of cross-linked porphyrin-grafted carbon nanotubes, N,N-dimethylformamide, chloroform, and transition metal salt is 1g:7-9mL:50-55mL:9-13g.

8. The method for preparing the transition metal-based composite material for photocatalytic organic reactions according to claim 1, characterized in that, The transition metal salt mentioned in step five is one of zinc acetate dihydrate, cobalt acetate tetrahydrate, and manganese acetate tetrahydrate.

9. A transition metal-based composite material for photocatalytic organic reactions, characterized in that, The transition metal-based composite material for photocatalytic organic reactions is prepared according to the method described in any one of claims 1-8.

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