A ferrocene-modified rare earth metal porphyrin photocatalyst, preparation method thereof and application thereof

Abstract

The present invention discloses a ferrocene-modified rare earth metal porphyrin photocatalyst, a preparation method thereof and an application thereof. First, using tetrahydroxy porphyrin and ferrocene formic acid as raw materials and benzene as a solvent, an esterification reaction is carried out to obtain a ferrocene ester-based porphyrin ligand; then, using a rare earth acetylacetonate complex and the ferrocene ester-based porphyrin ligand as raw materials and 1,2,4-trichlorobenzene as a solvent, a coordination reaction is carried out under a protective gas atmosphere to prepare a ferrocene-modified rare earth metal porphyrin photocatalyst; when the ferrocene-modified rare earth metal porphyrin photocatalyst is applied to catalyze the cycloaddition reaction of carbon dioxide and epoxides, it shows excellent catalytic effects and simultaneously obtains a cyclic carbonate with a high yield.

Description

Technical Field

[0001] The present invention belongs to the technical field of photocatalytic synthesis of cyclic carbonates, and particularly relates to a ferrocene-modified rare earth metal porphyrin photocatalyst, a preparation method thereof, and an application thereof. Background Art

[0002] As a greenhouse gas, the increase of carbon dioxide in the atmosphere has brought a series of environmental and ecological problems such as global warming, sea level rise, and severe climate. Therefore, how to reduce the content of carbon dioxide in the atmosphere has become an important issue faced by the world.

[0003] At present, capturing and chemically converting carbon dioxide into high-value chemical products to reduce the carbon dioxide level in the atmosphere is one of the important ways to solve the above problems. Among many carbon dioxide conversion reactions, the cyclic carbonate generated by the cycloaddition reaction of carbon dioxide and epoxide has attracted great interest due to its 100% atom utilization rate and wide application of the product (such as being widely used as a polar solvent, an electrolyte for high-density batteries, an intermediate for certain organic reactions, and the synthesis of phenolic resins).

[0004] Previous studies have shown that the rate-determining step of the CO2 cycloaddition reaction is the ring-opening of epoxide, and the f orbitals of rare earth metal complexes have a large number of unfilled empty orbitals, which are considered to be an excellent Lewis acid to provide adsorption sites for the ring-opening of epoxide, facilitating the nucleophilic attack of the cocatalyst tetrabutylammonium bromide. In addition, porphyrin-based metal complexes have unique structures and excellent properties, showing potential application prospects in the field of catalyzing the cycloaddition of CO2 and epoxide. Therefore, the theoretical research on them has been continuously advancing. For example, Wu Yang of Xi'an Shiyou University in this research group introduced the application of rare earth porphyrin metal complexes as catalysts in the cycloaddition reaction of CO2 and propylene oxide in his master's thesis "Research on Catalytic Functional Rare Earth Metal Complexes". Further, the electronic structure of rare earth metal catalytic sites was adjusted by the rare earth metal regulation strategy to enhance the CO2 conversion rate (Journal of the Chinese Chemical Society, 2020, 67(8): 1380-1386). However, due to the intrinsic chemical inertness of CO2, these catalysts usually need to be carried out under high pressure and high temperature, and the large amount of catalysts required leads to low cost-effectiveness.

[0005] In view of this, inspired by photocatalytic conversion technology, the present invention provides a ferrocene-modified rare earth metal porphyrin photocatalyst. Summary of the Invention

[0006] Aiming at the problems existing in the above-mentioned prior art, the present invention provides a ferrocene-modified rare earth metal porphyrin photocatalyst, a preparation method thereof, and an application thereof.

[0007] The first aspect of the present invention provides a ferrocene-modified rare earth metal porphyrin photocatalyst with a general structural formula of formula (1) as follows:

[0008]

[0009] In the formula, M is a rare earth metal element selected from Ce, Pr, Eu, Tb, Er, Tm, Yb.

[0010] Preferably, M is selected from the rare earth metal Yb.

[0011] The second aspect of the present invention provides a preparation method of the above-mentioned ferrocene-modified rare earth metal porphyrin photocatalyst, including the following steps:

[0012] S1. Using tetrahydroxy porphyrin and ferrocene formic acid as raw materials, benzene as a solvent, carrying out an esterification reaction, and then purifying to obtain a ferrocene ester-based porphyrin ligand;

[0013] S2. Using a rare earth acetylacetonate complex and a ferrocene ester-based porphyrin ligand as raw materials, 1,2,4-trichlorobenzene as a solvent, carrying out a coordination reaction under a protective gas atmosphere, and then purifying to obtain a ferrocene-modified rare earth metal porphyrin photocatalyst.

[0014] Preferably, the tetrahydroxy porphyrin is prepared by using 4-hydroxybenzaldehyde and pyrrole as raw materials, propionic acid as a solvent, through an aldehyde-amine condensation reaction, or can also be obtained by conventional techniques in the art.

[0015] Preferably, the molar ratio of 4-hydroxybenzaldehyde to tetrahydroxy porphyrin is 50-55:100.

[0016] Preferably, in step S1, the molar ratio of ferrocene formic acid to tetrahydroxy porphyrin is 8-12:2, the temperature of the esterification reaction is room temperature, and the reaction time is 3-6 h.

[0017] Preferably, in step S2, the molar ratio of the rare earth acetylacetonate complex to the ferrocene ester-based porphyrin ligand is 0.6:0.1-0.3, the temperature of the coordination reaction is 210-240 °C, and the reaction time is 4-8 h.

[0018] Preferably, in step S1, the purification includes successively carrying out filtration, rotary evaporation, recrystallization, washing, and drying procedures on the reaction product.

[0019] Preferably, in step S2, the purification includes successively carrying out column chromatography elution, suction filtration, vacuum distillation, recrystallization, and drying procedures on the reaction product.

[0020] Preferably, the eluent used for column chromatography elution is a mixed solvent of CHCl3 and C2H5OH, wherein the volume ratio of CHCl3 to C2H5OH is 1-10:10-1, and more preferably 9:1.

[0021] The third aspect of the present invention provides the application of the above-mentioned ferrocene-modified rare earth metal porphyrin photocatalyst in the cycloaddition reaction of CO2 and epoxides to prepare cyclic carbonates.

[0022] Preferably, the ferrocene-modified rare earth metal porphyrin photocatalyst catalyzes the cycloaddition reaction of CO2 and epoxides to prepare cyclic carbonates, including the following steps: under nitrogen protection, 0.1-0.2 mmol of the ferrocene-modified rare earth metal porphyrin photocatalyst, 0.4-0.8 mmol of tetrabutylammonium bromide, and 10-20 mL of epoxide are sequentially added to a quartz glass reactor, carbon dioxide gas is charged, the pressure is adjusted to 0.08-0.1 MPa, and the reaction is carried out at room temperature for 2-10 h. The reaction is stopped to obtain cyclic carbonates.

[0023] Preferably, the epoxide is any one of propylene oxide, epichlorohydrin, styrene oxide, and 4-vinylbenzyl glycidyl ether.

[0024] The present invention has the following beneficial effects:

[0025] (1) By introducing a ferrocene unit with good optoelectronic properties into the porphyrin system, the present invention prepares a ferrocene-modified rare earth metal porphyrin photocatalyst. In the process of using it to catalyze the cycloaddition reaction of CO2 to prepare cyclic carbonates, CO2 can be converted into more active CO2* (CO2 radical) than neutral CO2 under mild conditions (room temperature and atmospheric pressure) by means of light driving. It has more catalytic active centers, accelerating the rate of CO2 insertion reaction. At the same time, using rare earth metal Ln with a smaller ionic radius and ferrocene with strong electron-donating ability can effectively improve the charge density distribution of the complex, form a more stable metal-epoxide activation coordination bond, and further accelerate the ring-opening rate of the rate-determining step of the CO2 cycloaddition reaction, namely the epoxide. Thus, carbon dioxide and epoxides can be rapidly converted into cyclic carbonates, effectively improving the conversion rate and yield of the reaction. Therefore, the ferrocene-modified rare earth metal porphyrin photocatalyst prepared by the present invention exhibits excellent catalytic activity and catalytic efficiency in the cycloaddition reaction of carbon dioxide and epoxides at room temperature and atmospheric pressure.

[0026] (2) The raw materials used in the preparation method of the present invention are simple and easy to obtain, with low cost, simple process, easy control of the operation process, and mild reaction conditions, which are suitable for application and promotion. Description of the Drawings

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the attached drawings required in the embodiments. Obviously, the attached drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other attached drawings can be obtained based on these attached drawings.

[0028] Figure 1 It is a schematic structural diagram of a ferrocene-modified rare earth metal porphyrin photocatalyst;

[0029] Figure 2 It is an infrared spectrum diagram of the tetrahydroxy porphyrin ligand TPPH-OH prepared in Example 1;

[0030] Figure 3 It is an infrared spectrum diagram of the ferrocene ester-based porphyrin ligand TPPH-Fe prepared in Example 1.

[0031] Figure 4 It is an infrared spectrum diagram of the rare earth metal porphyrin complex TPPCOOFeCe prepared in Example 1. Specific Embodiments

[0032] In the following description, for the purpose of illustration rather than limitation, specific details such as specific system structures and technologies are presented to thoroughly understand the embodiments of the present invention. However, those skilled in the art should clearly understand that the present invention can also be implemented in other embodiments without these specific details.

[0033] The following describes in detail a ferrocene-modified rare earth metal porphyrin photocatalyst, a preparation method thereof, and an application thereof provided by the present invention in combination with embodiments.

[0034] Example 1

[0035] Refer to the following synthesis process route diagrams of formulas (1), (2), and (3) to prepare a ferrocene-modified rare earth metal porphyrin photocatalyst, as Figure 1 shown:

[0036]

[0037]

[0038] The specific steps are as follows:

[0039] 1. Prepare tetrahydroxy porphyrin TPPH-OH, and the specific steps are as follows:

[0040] (1) In a 250 ml three-necked flask equipped with a thermometer, a magnetic stirrer and a constant pressure dropping funnel, 50 mmol 4-hydroxybenzaldehyde and 100 ml propionic acid were added, and the mixture was stirred and heated to 142°C and reflux began. 100 mmol freshly distilled pyrrole (dissolved in 20 ml propionic acid) was added dropwise using a constant pressure dropping funnel. The addition was completed within 20 min, and the reaction solution quickly turned from light yellow to purple-black. The mixture was heated to 145°C and kept under reflux for 4 h. The heating was then stopped and the mixture was cooled to room temperature. A certain amount of anhydrous ethanol was added. The mixture was frozen and allowed to stand overnight in a refrigerator. The mixture was then filtered using a sand core funnel, washed with distilled water and ethanol, respectively, and dried to obtain a crude blue-purple crystal. The crude blue-purple crystal was dried in an oven at 110°C for 5 h to obtain a blue-purple crystal.

[0041] (2) Activate the neutral alumina for chromatography in an oven at 240°C for 3h, then cool it in a dryer for later use, use a wet method to pack the column, the filling height is 25cm, keep the liquid level on the column 1-2cm high, take the synthesized crude product and dissolve it with as little dichloromethane as possible, start adding the sample, wait for the solution to completely immerse the column, add dichloromethane in time for elution, collect the first purple band, and after rotary evaporation and drying, the pure target product tetrahydroxyporphyrin can be obtained. The obtained target product tetrahydroxyporphyrin TPPH-OH is characterized, and the infrared spectrum is shown in Figure 2 .

[0042] Depend on Figure 2 The results show that 3421cm -1 The peak at 796 cm is the peak of hydroxyl (-OH), -1 The peak at 3319 cm is the benzene ring (-C=C-) peak. –1 964cm –1 The peaks at 1472 cm-1 are the stretching and bending vibration peaks of the NH bond. -1 The peaks at 1089m are the vibration peaks of the benzene ring and pyrrole ring skeleton. -1 The peak appearing at is the characteristic peak of pyrrole CH swing vibration, which indicates that tetrahydroxyporphyrin TPPH-OH is successfully synthesized in this example.

[0043] 2. Preparation of ferrocenyl ester porphyrin ligand TPPH-Fe, the specific steps are:

[0044] 11mmol ferrocenecarboxylic acid, 2mmol tetrahydroxyporphyrin and 50mL benzene were added to a 100mL three-necked flask, and the esterification reaction was carried out at room temperature for 5h. Clear water droplets were formed on the wall of the condenser tube. A small amount of insoluble impurities were removed by hot filtration, and the solvent was removed by rotary evaporation to obtain a solid product. The solid product was then recrystallized from acetone / chloroform to obtain a pure target product, ferrocene ester porphyrin ligand. The obtained ferrocene ester porphyrin ligand TPPH-Fe was characterized by infrared spectroscopy. Figure 3 .

[0045] It can be seen from Figure 3 the results that the peak at 3317 cm -1 is the C-H stretching vibration peak on the cyclopentadienyl ring, and the peak at 800 cm -1 is the (-C=C-) peak on the cyclopentadienyl ring. The peaks at 1595 cm -1 , 1433 cm -1 , and 1392 m -1 are the skeletal vibration peaks of the benzene ring and the pyrrole ring respectively. The peak appearing at 1716 cm -1 is the characteristic peak of (-COO-) on the benzene ring. This shows that the ferrocene ester-based porphyrin ligand TPPH-Fe was successfully synthesized in this example.

[0046] 3. Preparation of rare earth metal porphyrin complex TPPCOOFeCe. The specific steps are as follows:

[0047] Take 0.3 mmol of ferrocene ester-based porphyrin ligand TPPH-Fe and 0.6 mmol of cerium acetylacetonate hydrate Ce(acac)3·3H2O and place them in a 100 ml ground three-necked flask. Then add 40 ml of 1,2,4-trichlorobenzene as the solvent, introduce high-purity nitrogen, stir, heat up to 210 °C (at this time, the solvent 1,2,4-trichlorobenzene starts to reflux), carry out the coordination reaction for 5 h, stop heating, and cool to room temperature; filter by suction, distill under reduced pressure to obtain a grayish-black solid, and then recrystallize the obtained solid in absolute ethanol to obtain the rare earth metal porphyrin complex TPPCOOFeCe. Infrared characterization was performed on the obtained target compound TPPCOOFeCe, and the infrared spectrum is shown in Figure 4 .

[0048] It can be seen from Figure 4 the results that the disappearance of the N-H vibration peak at 3317 cm –1 on the pyrrole ring of the porphyrin is due to the cleavage of the hydrogen atom on nitrogen when the porphyrin chelates with rare earth ions. Therefore, the formation of the complex can be determined. The peaks at 1595 cm -1 , 1472 cm -1 , and 1434 cm -1 are the skeletal vibration peaks of the benzene ring and the pyrrole ring respectively. The peak appearing at 1715 cm -1 is the characteristic peak of (-COO-) on the benzene ring. This shows that the rare earth metal porphyrin complex TPPCOOFeCe was successfully synthesized in this example.

[0049] Example 2

[0050] The steps are basically the same as those in Experimental Example 1, except that: cerium acetylacetonate Ce(acac)3 is replaced by praseodymium acetylacetonate Pr(acac)3, and the rare earth metal porphyrin complex TPPCOOFePr was prepared using praseodymium acetylacetonate Pr(acac)3 in step 3.

[0051] Example 3

[0052] The steps are basically the same as those in Experimental Example 1, except that: cerium acetylacetonate Ce(acac)3 is replaced by europium acetylacetonate Eu(acac)3, and in step 3, europium acetylacetonate Eu(acac)3 is used to prepare the rare earth metal porphyrin complex TPPCOOFeEu.

[0053] Example 4

[0054] The steps are basically the same as those in Experimental Example 1, except that: cerium acetylacetonate Ce(acac)3 is replaced by terbium acetylacetonate Tb(acac)3, and in step 3, terbium acetylacetonate Tb(acac)3 is used to prepare the rare earth metal porphyrin complex TPPCOOFeTb.

[0055] Example 5

[0056] The steps are basically the same as those in Experimental Example 1, except that: cerium acetylacetonate Ce(acac)3 is replaced by erbium acetylacetonate Er(acac)3, and in step 3, erbium acetylacetonate Er(acac)3 is used to prepare the rare earth metal porphyrin complex TPPCOOFeEr.

[0057] Example 6

[0058] The steps are basically the same as those in Experimental Example 1, except that: cerium acetylacetonate Ce(acac)3 is replaced by thulium acetylacetonate Tm(acac)3, and in step 3, thulium acetylacetonate Tm(acac)3 is used to prepare the rare earth metal porphyrin complex TPPCOOFeTm.

[0059] Example 7

[0060] The steps are basically the same as those in Experimental Example 1, except that: cerium acetylacetonate Ce(acac)3 is replaced by ytterbium acetylacetonate Yb(acac)3, and in step 3, ytterbium acetylacetonate Yb(acac)3 is used to prepare the rare earth metal porphyrin complex TPPCOOFeYb.

[0061] Example 8

[0062] The steps are basically the same as those in Experimental Example 1, except that: 8 mmol of ferrocene formic acid is added and the esterification reaction is carried out at room temperature for 6 h.

[0063] Example 9

[0064] The steps are basically the same as those in Experimental Example 1, except that: 12 mmol of ferrocene formic acid is added and the esterification reaction is carried out at room temperature for 3 h.

[0065] Example 10

[0066] The procedure is basically the same as that of Experimental Example 1, except that: 0.1 mmol of ferrocene-esterified porphyrin ligand TPPH-Fe was taken, heated to 220 °C, and the coordination reaction was carried out for 8 h.

[0067] Example 11

[0068] The procedure is basically the same as that of Experimental Example 1, except that: 0.2 mmol of ferrocene-esterified porphyrin ligand TPPH-Fe was taken, heated to 240 °C, and the coordination reaction was carried out for 4 h.

[0069] The performance of the rare earth metal porphyrin complexes TPPCOOFeLn (Ln = Ce, Pr, Eu, Tb, Er, Tm, Yb) prepared in Examples 1-7 for photocatalytic cycloaddition of carbon dioxide and propylene oxide to prepare cyclic carbonates was studied below.

[0070] Specific Test Example 1

[0071] Into a 50 mL quartz glass reactor, ferrocene-modified rare earth metal porphyrin complex TPPCOOFeCe (0.1500 mmol), tetrabutylammonium bromide (TBAB) (0.1934 g, 0.6000 mmol) and propylene oxide (15 mL, 0.2140 mol) were successively added. Meanwhile, a magnetic stir bar was added, sealed and the air in the autoclave was replaced with carbon dioxide for 2-3 times. Then, under continuous ventilation, the CO2 pressure was maintained at 0.1 MPa. At room temperature, the reaction was stirred under illumination with a 365 nm LED lamp for 6 h. Among them, in order to reduce the influence of a small amount of heat generated by the light reaction on the reaction, a fan cooling device was also provided to cool down to ensure that the reaction was always carried out at room temperature. After the catalytic reaction was completed, the CO2 gas was released, the catalyst and the cocatalyst were filtered and separated, and the liquid product was analyzed by gas chromatography. The yield of cyclic carbonate was calculated to be 83.9%.

[0072] Specific Test Example 2

[0073] The procedure is basically the same as that of Specific Test Example 1, except that: TPPCOOFeCe was replaced with TPPCOOFePr. After gas chromatography analysis, the yield of cyclic carbonate was calculated to be 85.2%.

[0074] Specific Test Example 3

[0075] The procedure is basically the same as that of Specific Test Example 1, except that: TPPCOOFeCe was replaced with TPPCOOFeEu. After gas chromatography analysis, the yield of cyclic carbonate was calculated to be 88.5%.

[0076] Specific Test Example 4

[0077] The procedure is basically the same as that in Specific Test Example 1, except that: TPPCOOFeCe is replaced by TPPCOOFeTb. Through gas chromatography analysis, the calculated yield of cyclic carbonate is 90.3%.

[0078] Specific Test Example 5

[0079] The procedure is basically the same as that in Specific Test Example 1, except that: TPPCOOFeCe is replaced by TPPCOOFeEr. Through gas chromatography analysis, the calculated yield of cyclic carbonate is 92.1%.

[0080] Specific Test Example 6

[0081] The procedure is basically the same as that in Specific Test Example 1, except that: TPPCOOFeCe is replaced by TPPCOOFeTm. Through gas chromatography analysis, the calculated yield of cyclic carbonate is 93.5%.

[0082] Specific Test Example 7

[0083] The procedure is basically the same as that in Specific Test Example 1, except that: TPPCOOFeCe is replaced by TPPCOOFeYb. Through gas chromatography analysis, the calculated yield of cyclic carbonate is 94.7%.

[0084] The following studies the performance of the rare earth metal porphyrin complex TPPCOOFeLnYb prepared in Research Example 7 for photocatalytic cycloaddition of carbon dioxide with other epoxides to prepare cyclic carbonates.

[0085] Specific Test Example 8

[0086] The procedure is basically the same as that in Specific Test Example 7, except that: propylene oxide is replaced by epichlorohydrin (15 ml, 0.2046 mol). Through gas chromatography analysis, the calculated yield of cyclic carbonate is 93.1%.

[0087] Specific Test Example 9

[0088] The procedure is basically the same as that in Specific Test Example 7, except that: propylene oxide is replaced by styrene oxide (15 ml, 0.1318 mol). Through gas chromatography analysis, the calculated yield of cyclic carbonate is 92.1%.

[0089] Specific Test Example 10

[0090] The procedure is basically the same as that in Specific Test Example 7, except that: propylene oxide is replaced by cyclohexene oxide. Through gas chromatography analysis, the calculated yield of cyclic carbonate is 92.5%.

[0091] Specific Test Example 11

[0092] The procedure was basically the same as that of Specific Test Example 7, except that propylene oxide was replaced with 4-vinylbenzyl glycidyl ether (15 ml, 0.0868 mol). Through gas chromatography analysis, the yield of cyclic carbonate was calculated to be 91.8%.

[0093] From the above results, it can be seen that the present invention successfully prepared a ferrocene-modified rare earth metal porphyrin photocatalyst. This ferrocene-modified rare earth metal porphyrin photocatalyst has more catalytic active centers. By using rare earth metal Ln with a smaller ionic radius and ferrocene with a strong electron-donating ability, the charge density distribution of the complex can be effectively improved, forming a more stable metal-epoxide activation coordination bond, accelerating the ring-opening of the epoxide, and further enabling the rapid conversion of carbon dioxide and epoxide into cyclic carbonate at room temperature and atmospheric pressure, effectively improving the conversion rate and yield of the reaction. In addition, this rare earth metal porphyrin photocatalyst TPPCOOFeLn has wide applicability and is not affected by the substituents of the epoxide, and the yield of its cyclic carbonate all reaches more than 80%.

[0094] The present invention is not limited to the above specific embodiments. Those of ordinary skill in the art, starting from the above concepts and without creative labor, can make various transformations, which all fall within the protection scope of the present invention.

Claims

1. Use of a ferrocene-modified rare earth metal porphyrin photocatalyst in the photocatalytic cycloaddition reaction of CO2 and epoxides to prepare cyclic carbonates, characterized in that, The ferrocene-modified rare earth metal porphyrin photocatalyst has a general structural formula of formula (1) as follows: （1） In the formula, M is a rare earth metal element selected from Ce, Pr, Eu, Tb, Er, Tm or Yb.

2. The application according to claim 1, wherein The preparation method of the ferrocene-modified rare earth metal porphyrin photocatalyst includes the following steps: S1. Using tetrahydroxy porphyrin shown by the former of the following structural formula and ferrocene formic acid as raw materials, and benzene as a solvent, an esterification reaction is carried out, and then purification is carried out to obtain a ferrocene ester-based porphyrin ligand shown by the latter of the following structural formula; S2. Using a rare earth acetylacetonate complex and a ferrocene ester-based porphyrin ligand as raw materials, 1,2,4-trichlorobenzene as a solvent, a coordination reaction is carried out under the atmosphere of a protective gas, and then purification is carried out to obtain a ferrocene-modified rare earth metal porphyrin photocatalyst.

3. The application according to claim 2, characterized in that, The tetrahydroxy porphyrin is prepared by using 4-hydroxybenzaldehyde and pyrrole as raw materials and propionic acid as a solvent through an aldehyde-amine condensation reaction.

4. The application according to claim 2, wherein In step S1, the molar ratio of the ferrocene formic acid to the tetrahydroxy porphyrin is 8-12:2, the temperature of the esterification reaction is room temperature, and the reaction time is 3-6 h.

5. The application according to claim 2, characterized in that, In step S2, the molar ratio of the rare earth acetylacetonate complex to the ferrocene ester-based porphyrin ligand is 0.6:0.1-0.3, the temperature of the coordination reaction is 210-240 °C, and the reaction time is 4-8 h.

6. The application according to claim 2, wherein In step S2, the purification includes sequentially performing column chromatography elution, suction filtration, vacuum distillation, recrystallization, and drying processes on the reaction product.

7. The application according to claim 6, characterized in that, The eluent used for the column chromatography elution is a mixed solvent of CHCl3 and C2H5OH, wherein the volume ratio of CHCl3 to C2H5OH is 1-10:10-1.

8. The application according to claim 1, wherein The ferrocene-modified rare earth metal porphyrin photocatalyst photocatalytically reacts CO2 and epoxides to carry out a cycloaddition reaction to prepare cyclic carbonates, including the following steps: Under nitrogen protection, 0.1-0.2 mmol of the ferrocene-modified rare earth metal porphyrin photocatalyst, 0.4-0.8 mmol of tetrabutylammonium bromide, and 10-20 mL of epoxide are sequentially added to a quartz glass reactor, carbon dioxide gas is filled, the pressure is adjusted to 0.08-0.1 MPa, and the reaction is carried out at room temperature for 2-10 h to obtain cyclic carbonates.

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