Preparation Method and Application of a Fe2O3 / NiFe2O4 Composite Metal Oxide Catalyst

Abstract

The present invention discloses a preparation method and application of a Fe2O3 / NiFe2O4 composite metal oxide catalyst. The catalyst is prepared by a one-step hydrothermal method, with a simple preparation method and being inexpensive and easily available. The prepared catalyst is used in the reaction of synthesizing styrene carbonate from styrene oxide and CO2, having good reaction effects, and the catalyst has good recycling performance and stability. In addition, the reaction conditions of this catalytic system are mild, meeting the requirements of green chemistry and sustainable development.

Description

Technical Field

[0001] The present invention relates to a catalyst and a preparation method thereof, and particularly to a catalyst for synthesizing styrene carbonate from styrene oxide and CO2 and a preparation method thereof. Background Art

[0002] Styrene carbonate is widely used in textile, printing and dyeing, and as an intermediate in the synthesis of many organic compounds such as polycarbonate and thermosetting resin, as well as in many fields such as electrochemistry and metal extraction. Among them, the synthesis of styrene carbonate from styrene oxide and CO2 is the main route for producing styrene carbonate.

[0003] Because styrene carbonate has broad application prospects and CO2 can be efficiently utilized in this reaction, in recent years, the method for synthesizing styrene carbonate from styrene oxide and CO2 has received increasing attention. In this reaction, traditional homogeneous catalysts have disadvantages such as difficult separation of products, serious corrosion of equipment, and serious environmental pollution. Heterogeneous catalysts, on the other hand, have received increasing attention because of their advantages such as easy separation of products, low preparation cost, good stability, and environmental friendliness. Chinese Patent CN202210164524.9 discloses a method for synthesizing cyclic carbonates from CO2 based on a Zn-MOF catalyst. The catalyst is composed of Zn-MOF and 1,3-bis(3,5-dimethyl isophthalate)-1H benzimidazolium bromide with a molar ratio of 1:1, and can efficiently produce cyclic carbonates. However, the preparation method of such catalysts is complex, expensive, and the reaction effect is poor. Therefore, seeking a heterogeneous solid catalyst with low price and simple preparation to realize the synthesis of styrene carbonate from styrene oxide and CO2 under mild conditions has important practical significance, but still has great challenges. Summary of the Invention

[0004] Object of the Invention: Aiming at the above-mentioned prior art, a catalyst for synthesizing styrene carbonate from styrene oxide and CO2 and a preparation method thereof are proposed. The catalyst is used for synthesizing styrene carbonate from styrene oxide and CO2, the reaction conditions are mild, the yield of styrene carbonate is high, and the catalytic effect does not decrease significantly after being reused many times.

[0005] Technical Solution: A preparation method of a Fe2O3 / NiFe2O4 composite metal oxide catalyst, comprising: stirring and mixing FeCl3·6H2O, Ni(NO3)2·6H2O, urea, and deionized water, adding glacial acetic acid and continuing to stir, finally transferring the solution into a hydrothermal autoclave, carrying out hydrothermal treatment at 150-200°C for 20-30 h, after the liquid is cooled to room temperature, centrifuging several times with water and ethanol until the pH = 6-8, drying the washed precipitate in an oven and then calcining it in air at 300-700°C for 2-6 h to obtain the Fe2O3 / NiFe2O4 composite metal oxide.

[0006] Furthermore, the molar ratio of FeCl3·6H2O, Ni(NO3)2·6H2O, and urea is 1:0.20 - 0.33:6.25.

[0007] Application of the Fe2O3 / NiFe2O4 composite metal oxide catalyst obtained by the described preparation method in the synthesis of styrene carbonate from styrene oxide and CO2.

[0008] Furthermore, the Fe2O3 / NiFe2O4 composite metal oxide catalyst, styrene oxide, N,N-dimethylformamide, and tetrabutylammonium bromide are added into a high-pressure reaction kettle, and CO2 gas is introduced to prepare styrene carbonate.

[0009] Furthermore, the dosage of the Fe2O3 / NiFe2O4 composite metal oxide catalyst is 0.05 - 0.15 g / mL based on the volume of styrene oxide.

[0010] Furthermore, the molar ratio of styrene oxide and tetrabutylammonium bromide is 1:0.06 - 0.27.

[0011] Furthermore, the molar ratio of styrene oxide and N,N-dimethylformamide is 1:3.74 - 7.49.

[0012] Furthermore, the reaction temperature is 70 - 110 °C, the reaction time in the high-pressure reaction kettle is 2 - 6 h, and the reaction pressure is 0.2 - 0.8 MPa.

[0013] Beneficial effects: 1. A Fe2O3 / NiFe2O4 catalyst of the present invention comprises two metal oxides, Fe2O3 and NiFe2O4, wherein the molar ratio of Ni:Fe is 1:6 - 1:10, and it is prepared by one-step hydrothermal reaction of FeCl3·6H2O, Ni(NO3)2·6H2O, urea, and glacial acetic acid followed by drying and calcination. The Fe2O3 / NiFe2O4 catalyst of the present invention has low preparation cost and a simple preparation process.

[0014] 2. The Fe2O3 / NiFe2O4 catalyst of the present invention is used for the synthesis of styrene carbonate from styrene oxide and CO2, with mild reaction conditions, high yield of styrene carbonate, and no obvious decrease in catalytic effect after being reused multiple times, meeting the requirements of green chemistry and sustainable development, and having good industrial application prospects. Description of the Drawings

[0015] Figure 1 XRD patterns of the Fe2O3 / NiFe2O4 catalyst prepared in Example 1 of the invention, Fe2O3 in Comparative Example 1, and NiFe2O4 in Comparative Example 2;

[0016] Figure 2 SEM image of the Fe2O3 / NiFe2O4 catalyst prepared for Invention Example 1;

[0017] Figure 3 TEM image of the Fe2O3 / NiFe2O4 catalyst prepared for Invention Example 1;

[0018] Figure 4 HRTEM image of the Fe2O3 / NiFe2O4 catalyst prepared for Invention Example 1. Detailed implementation manners

[0019] The present invention will be further explained below with reference to the accompanying drawings.

[0020] Example 1

[0021] 4.8 mmol of FeCl3·6H2O, 1.2 mmol of Ni(NO3)2·6H2O, 30 mmol of urea, and 60 mL of deionized water were added to a 100 mL beaker and stirred for 0.5 h. Then 10 mL of glacial acetic acid was added and stirring continued for 0.5 h. The solution was placed in a hydrothermal autoclave and hydrothermally treated at 180 °C for 24 h. After the hydrothermal autoclave was naturally cooled to room temperature, it was centrifuged several times with water and ethanol until pH = 7. The obtained product was dried at 80 °C for 12 h and then calcined in air at 500 °C for 4 h to obtain the Fe2O3 / NiFe2O4 catalyst.

[0022] The prepared catalyst was used in the reaction of synthesizing styrene carbonate from styrene oxide and CO2. 0.2 g of the Fe2O3 / NiFe2O4 catalyst, 0.36 mmol of tetrabutylammonium bromide, 17.5 mmol of styrene oxide, and 10 mL of N,N-dimethylformamide were added to a high-pressure reaction kettle. The reaction was carried out at 90 °C and a CO2 pressure of 0.4 MPa for 4 h. The obtained product was analyzed by gas chromatography. The results showed that the conversion rate of styrene oxide reached 89.1% and the selectivity of styrene carbonate reached 100%. In addition, to test the recycling performance of the catalyst, the catalyst after the reaction was washed thoroughly with deionized water and ethanol and then dried at 80 °C for 12 h and used for the next test. The results showed that after the Fe2O3 / NiFe2O4 catalyst was recycled 5 times, there was no obvious decrease in catalytic activity and selectivity.

[0023] Comparative Example 1

[0024] The preparation method was the same as that of Example 1, the only difference being that the metal source did not involve Ni, and only 6 mmol of FeCl3·6H2O was added. The resulting catalyst was an Fe2O3 catalyst. The catalytic performance was tested under the same conditions as in Example 1, and the results showed that the conversion rate of styrene oxide was 51.3%, and the selectivity of phenyl vinyl carbonate was 100%.

[0025] Figure 1 It contains the XRD pattern of the prepared Fe2O3 catalyst.

[0026] Comparative Example 2

[0027] The preparation method was the same as that of Example 1, the only difference being that the amounts of FeCl3·6H2O and Ni(NO3)2·6H2O added were 3 mmol and 3 mmol respectively. The resulting catalyst was a NiFe2O4 catalyst. The catalytic performance was tested under the same conditions as in Example 1, and the results showed that the conversion rate of styrene oxide was 55.6%, and the selectivity of phenyl vinyl carbonate was 100%.

[0028] Figure 1 It contains the XRD pattern of the prepared NiFe2O4 catalyst.

[0029] Comparative Example 3

[0030] Ni(NO3)2·6H2O solid was calcined at 500 °C for 4 h to obtain a NiO catalyst. The catalytic performance was tested under the same conditions as in Example 1, and the results showed that the conversion rate of styrene oxide was 34.8%, and the selectivity of phenyl vinyl carbonate was 100%.

[0031] Comparative Example 4

[0032] According to XRF, the elemental ratio of Fe and Ni in the catalyst was 9:1. 0.268 g of Fe2O3 and 0.132 g of NiFe2O4 were weighed according to a molar ratio of 3.5:1, mixed and placed in an agate mortar, and ground until completely mixed evenly to obtain a physically mixed catalyst of Fe2O3 and NiFe2O4. The catalytic performance was tested under the same conditions as in Example 1, and the results showed that the conversion rate of styrene oxide was 57.0%, and the selectivity of phenyl vinyl carbonate was 100%.

[0033] Comparative Example 5

[0034] The catalytic performance was tested under the condition that no catalyst was added, but other reaction conditions were the same as those in Example 1. The results showed that the conversion rate of styrene oxide was 26.2%, and the selectivity of phenyl vinyl carbonate was 100%.

[0035] Example 2

[0036] The preparation method was the same as that of Example 1, and the only difference was that the amount of Ni(NO3)2·6H2O was 0.96 mmol, that is, the molar ratio of the addition amounts of FeCl3·6H2O, Ni(NO3)2·6H2O, and urea was 1:0.20:6.25. The obtained catalyst was tested for catalytic performance under the same conditions as in Example 1. The results showed that the conversion rate of styrene oxide was 85.4%, and the selectivity for styrene carbonate was 100%.

[0037] Example 3

[0038] The preparation method was the same as that of Example 1, and the only difference was that the amount of Ni(NO3)2·6H2O was 1.584 mmol, that is, the molar ratio of the addition amounts of FeCl3·6H2O, Ni(NO3)2·6H2O, and urea was 1:0.33:6.25. The obtained catalyst was tested for catalytic performance under the same conditions as in Example 1. The results showed that the conversion rate of styrene oxide was 87.0%, and the selectivity for styrene carbonate was 100%.

[0039] Example 4

[0040] The difference from Example 1 was that in the reaction for synthesizing styrene carbonate, 0.10 g of Fe2O3 / NiFe2O4 catalyst was added to the reaction kettle. Under the same other reaction conditions, the conversion rate of styrene oxide was 58.6%, and the selectivity for styrene carbonate was 100%.

[0041] Example 5

[0042] The difference from Example 1 was that in the reaction for synthesizing styrene carbonate, 0.15 g of Fe2O3 / NiFe2O4 catalyst was added to the reaction kettle. Under the same other reaction conditions, the conversion rate of styrene oxide was 70.3%, and the selectivity for styrene carbonate was 100%.

[0043] Example 6

[0044] The difference from Example 1 was that in the reaction for synthesizing styrene carbonate, 0.25 g of Fe2O3 / NiFe2O4 catalyst was added to the reaction kettle. Under the same other reaction conditions, the conversion rate of styrene oxide was 90.4%, and the selectivity for styrene carbonate was 100%.

[0045] Example 7

[0046] The difference from Example 1 was that in the reaction for synthesizing styrene carbonate, 0.30 g of Fe2O3 / NiFe2O4 catalyst was added to the reaction kettle. Under the same other reaction conditions, the conversion rate of styrene oxide was 90.1%, and the selectivity for styrene carbonate was 100%.

[0047] Example 8

[0048] The difference from Example 1 is that in the reaction for synthesizing styrene carbonate, the reaction temperature is 70 °C. Under the same other reaction conditions, the conversion rate of styrene oxide is 15.6%, and the selectivity of styrene carbonate is 100%.

[0049] Example 9

[0050] The difference from Example 1 is that in the reaction for synthesizing styrene carbonate, the reaction temperature is 80 °C. Under the same other reaction conditions, the conversion rate of styrene oxide is 49.1%, and the selectivity of styrene carbonate is 100%.

[0051] Example 10

[0052] The difference from Example 1 is that in the reaction for synthesizing styrene carbonate, the reaction temperature is 100 °C. Under the same other reaction conditions, the conversion rate of styrene oxide is 90.6%, and the selectivity of styrene carbonate is 100%.

[0053] Example 11

[0054] The difference from Example 1 is that in the reaction for synthesizing styrene carbonate, the reaction temperature is 110 °C. Under the same other reaction conditions, the conversion rate of styrene oxide is 90.2%, and the selectivity of styrene carbonate is 100%.

[0055] Example 12

[0056] The difference from Example 1 is that in the reaction for synthesizing styrene carbonate, the reaction time is 2 h. Under the same other reaction conditions, the conversion rate of styrene oxide is 31.2%, and the selectivity of styrene carbonate is 100%.

[0057] Example 13

[0058] The difference from Example 1 is that in the reaction for synthesizing styrene carbonate, the reaction time is 3 h. Under the same other reaction conditions, the conversion rate of styrene oxide is 59.6%, and the selectivity of styrene carbonate is 100%.

[0059] Example 14

[0060] The difference from Example 1 is that in the reaction for synthesizing styrene carbonate, the reaction time is 5 h. Under the same other reaction conditions, the conversion rate of styrene oxide is 87.3%, and the selectivity of styrene carbonate is 100%.

[0061] Example 15

[0062] Differing from Example 1, in the reaction for synthesizing styrene carbonate, the reaction time was 6 h. Under the same other reaction conditions, the conversion rate of styrene oxide was 87.9%, and the selectivity for styrene carbonate was 100%.

[0063] Example 16

[0064] Differing from Example 1, in the reaction for synthesizing styrene carbonate, the reaction pressure was 0.2 MPa. Under the same other reaction conditions, the conversion rate of styrene oxide was 63.5%, and the selectivity for styrene carbonate was 100%.

[0065] Example 17

[0066] Differing from Example 1, in the reaction for synthesizing styrene carbonate, the reaction pressure was 0.6 MPa. Under the same other reaction conditions, the conversion rate of styrene oxide was 87.9%, and the selectivity for styrene carbonate was 100%.

[0067] Example 18

[0068] Differing from Example 1, in the reaction for synthesizing styrene carbonate, the reaction pressure was 0.8 MPa. Under the same other reaction conditions, the conversion rate of styrene oxide was 85.4%, and the selectivity for styrene carbonate was 100%.

[0069] Example 19

[0070] Differing from Example 1, in the reaction for synthesizing styrene carbonate, the amount of N,N-dimethylformamide was 5 mL. Under the same other reaction conditions, the conversion rate of styrene oxide was 82.7%, and the selectivity for styrene carbonate was 100%.

[0071] Example 20

[0072] Differing from Example 1, in the reaction for synthesizing styrene carbonate, the molar ratio of styrene oxide to tetrabutylammonium bromide was 1:0.06. Under the same other reaction conditions, the conversion rate of styrene oxide was 30.4%, and the selectivity for styrene carbonate was 100%.

[0073] Example 21

[0074] Differing from Example 1, in the reaction for synthesizing styrene carbonate, the molar ratio of styrene oxide to tetrabutylammonium bromide was 1:0.13. Under the same other reaction conditions, the conversion rate of styrene oxide was 56.8%, and the selectivity for styrene carbonate was 100%.

[0075] Example 22

[0076] Differing from Example 1, in the reaction for synthesizing styrene carbonate, the molar ratio of styrene oxide to tetrabutylammonium bromide is 1:0.27. Under the same other reaction conditions, the conversion rate of styrene oxide is 88.9%, and the selectivity for styrene carbonate is 100%.

[0077] The following conclusions can be drawn from the above experimental results: (1) From the comparative examples, it can be found that the catalytic performance of the catalyst prepared according to the molar ratio of FeCl3·6H2O, Ni(NO3)2·6H2O, and urea of 1:0.25:6.25 is higher than that of the catalysts prepared with the molar ratios of 1:0.20:6.25 and 1:0.33:6.25. In addition, the catalytic activity of the Fe2O3 / NiFe2O4 composite catalyst is higher than that of pure Fe2O3, NiFe2O4, NiO, and the catalyst prepared by physically mixing Fe2O3 and NiFe2O4 according to the Fe and Ni element ratio in the Fe2O3 / NiFe2O4 composite catalyst, and higher than that of the blank. This proves that the Fe2O3 / NiFe2O4 composite catalyst prepared according to the molar ratio of FeCl3·6H2O, Ni(NO3)2·6H2O, and urea of 1:0.25:6.25 is not a simple physical mixture and has good catalytic activity. (2) When the catalyst dosage increases from 0.10 g to 0.20 g, the conversion rate of styrene oxide increases significantly. This is because when the catalyst dosage increases, the active sites of the reaction increase. After that, when it continues to increase from 0.20 g to 0.30 g, the conversion rate of styrene oxide does not increase significantly. Generally speaking, 0.20 g of the catalyst should be selected. (3) Between 70 °C and 90 °C, the conversion rate of styrene oxide increases with the increase of the reaction temperature. However, after 90 °C, the conversion rate does not increase significantly. Generally considered, the reaction temperature of 90 °C is a better reaction parameter. (4) Between the reaction time of 2 h and 4 h, the conversion rate of styrene oxide increases with the increase of time. Between 4 h and 6 h, the conversion rate does not increase significantly. Therefore, 4 h is the optimal reaction time. (5) Between the CO2 pressure increasing from 0.0 MPa to 0.4 MPa, the conversion rate increases with the increase of pressure. However, after 0.4 MPa, with the increase of pressure, the conversion rate does not increase significantly. Therefore, 0.4 MPa is the optimal reaction pressure. (6) N,N-dimethylformamide acts as a solvent in the reaction. At different dosages of N,N-dimethylformamide, the conversion rate of styrene oxide is different. And when the dosage of N,N-dimethylformamide increases, the conversion rate of styrene oxide increases, indicating that N,N-dimethylformamide has a promoting effect on the reaction. (7) When the molar ratio of styrene oxide to tetrabutylammonium bromide increases from 1:0.06 to 1:0.20, the conversion rate of styrene oxide increases significantly. However, this does not mean that the higher the dosage of tetrabutylammonium bromide, the better. When the ratio of styrene oxide to tetrabutylammonium bromide increases from 1:0.20 to 1:0.27, the conversion rate of styrene oxide does not increase significantly. Generally considered, the ratio of 1:0.20 is the optimal reaction condition. In summary, the present invention proposes a scheme for a novel catalyst for improving the reaction efficiency of synthesizing styrene carbonate from styrene oxide and CO2. This catalyst has the advantages of simple preparation, mild use conditions, high catalytic efficiency, good stability and cycling performance.

[0078] 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 be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. Application of Fe2O3 / NiFe2O4 composite metal oxide catalyst in synthesis of styrene carbonate from styrene oxide and CO2; The preparation method of the Fe2O3 / NiFe2O4 composite metal oxide catalyst includes: Stir and mix FeCl3·6H2O, Ni(NO3)2·6H2O, urea and deionized water, then add glacial acetic acid and continue stirring. Finally, transfer the solution into a hydrothermal reactor and hydrothermally react at 150 - 200 °C for 20 - 30 h. After the liquid cools to room temperature, centrifuge several times with water and ethanol until the pH = 6 - 8. Dry the washed precipitate in an oven and calcine it in air at 300 - 700 °C for 2 - 6 h to obtain the Fe2O3 / NiFe2O4 composite metal oxide; wherein, the molar ratio of FeCl3·6H2O, Ni(NO3)2·6H2O and urea is 1:0.20 - 0.33:6.25; Add the Fe2O3 / NiFe2O4 composite metal oxide catalyst obtained by the above preparation method, styrene oxide, N,N-dimethylformamide and tetrabutylammonium bromide into a high-pressure reactor, and introduce CO2 gas to prepare styrene carbonate.

2. The application according to claim 1, wherein The dosage of the Fe2O3 / NiFe2O4 composite metal oxide catalyst is 0.05 - 0.15 g / mL based on the volume of styrene oxide.

3. The application according to claim 1, characterized in that, The molar ratio of styrene oxide to tetrabutylammonium bromide is 1:0.06 - 0.

27.

4. The application according to any one of claims 2-3, characterized in that The molar ratio of styrene oxide to N,N-dimethylformamide is 1:3.74 - 7.

49.

5. The application according to claim 4, characterized in that, The reaction temperature is 70 - 110 °C, the reaction time in the high-pressure reactor is 2 - 6 h, and the reaction pressure is 0.2 - 0.8 MPa.

Images