A CuO-CeO 2 / ZrO 2 Application of supported catalysts in transesterification to prepare organic carbonates

Abstract

This invention discloses a CuO-CeO 2 / ZrO 2 The application of supported catalysts in the transesterification process to prepare organic carbonates, wherein the organic carbonate is one of dimethyl carbonate, diethyl carbonate, diisopropyl carbonate, and di-n-pentyl carbonate. The specific application process involves using alcohols and ethylene carbonate as raw materials, in a CuO-CeO... 2 / ZrO 2 Organic carbonates are prepared by transesterification at 90-180℃ under the action of a supported catalyst; the alcohol is one of methanol, ethanol, isopropanol, and n-pentanol; the molar ratio of the alcohol to ethylene carbonate is (6-11):1. CuO-CeO 2 / ZrO 2 Supported catalysts exhibit excellent catalytic activity and stability, higher DMC selectivity, and higher DMC yield when used in transesterification to prepare organic carbonates.

Description

Application of a CuO-CeO2 / ZrO2 supported catalyst in transesterification to prepare organic carbonates Technical Field

[0001] This invention belongs to the field of thermal catalyst technology, specifically relating to the application of a CuO-CeO2 / ZrO2 supported catalyst in the transesterification preparation of organic carbonates. Background Technology

[0002] Organic carbonates, as an important class of chemicals, play a crucial role in the chemical and pharmaceutical industries. As a green, environmentally friendly, and non-toxic chemical intermediate, organic carbonates are widely used in organic chemicals, pharmaceuticals, cleaning agents, coatings, and paints. Furthermore, organic carbonates possess high octane numbers, good oil-water partition coefficients, and excellent electrical conductivity, making them widely used in fuel additives and battery electrolytes. Dimethyl carbonate, diethyl carbonate, diisopropyl carbonate, and di-n-pentyl carbonate are some of the more common organic carbonates.

[0003] Currently, the main methods for synthesizing organic carbonates from carbon dioxide include transesterification, urea alcoholysis, alcohol oxidative carbonylation, and direct synthesis from methanol and CO2. Transesterification has wide industrial applications, achieving 100% atom utilization, and is highly economical, perfectly meeting the requirements of green chemistry. This method first utilizes ethylene oxide (EO) and CO2 to synthesize ethylene carbonate (EC) intermediates. Then, EC undergoes transesterification with alcohols to generate organic carbonates, simultaneously producing ethylene glycol (EG). In the first step, CO2 can react with the high-energy compound EO to prepare EC; this process has been successfully implemented in industrial production and exhibits high reactivity and selectivity. Many researchers have also conducted extensive research on the second step reaction. The selection of the catalyst is crucial. Currently, sodium methoxide is the traditional catalyst used. While it has high catalytic activity, it has a fatal drawback: the deactivation of sodium methoxide generates solid waste, making subsequent separation processes very complex and unfavorable for industrial production.

[0004] Common heterogeneous catalysts for transesterification of organic carbonates include metal oxides, hydrotalcites, ion exchange resins, and supported catalysts. In the CeCu composite metal oxide catalyst prepared by Kumar P et al., a 71.9% dimethyl carbonate (DMC) yield was obtained under the following conditions: a raw material alcohol-ester molar ratio of 10:1, a reaction time of 4 h, and a reaction temperature of 160 °C. These reaction conditions were quite harsh. (Kumar P, Srivastava VC, Mishra I M. Dimethyl carbonate synthesis by transesterification of propylene carbonate with methanol: Comparative assessment of Ce-M (M=Co,Fe,Cu and Zn) catalysts[J]. Renewable Energy, 2016, 88:457-464.). Patent CN202210539015.X discloses a B-doped g-C3N4 catalyst for the synthesis of dimethyl carbonate (DMC). Under conditions of an alcohol-ester molar ratio of 8:1, a reaction time of 5 hours, a reaction temperature of 150°C, and a reaction pressure of 0.7 MPa, a DMC yield of 66.4% was obtained. However, the catalyst preparation process is relatively complex. Therefore, developing inexpensive, efficient, environmentally friendly, and recyclable heterogeneous catalysts is of great significance for the transesterification preparation of organic carbonates. Summary of the Invention

[0005] The purpose of this invention is to provide an application of CuO-CeO2 / ZrO2 supported catalyst in the transesterification preparation of organic carbonates. The application of CuO-CeO2 / ZrO2 supported catalyst in the transesterification preparation of organic carbonates can exhibit excellent catalytic activity and stability, higher DMC selectivity and DMC yield.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The application of a CuO-CeO2 / ZrO2 supported catalyst in the transesterification preparation of organic carbonates, wherein the organic carbonate is one of dimethyl carbonate, diethyl carbonate, diisopropyl carbonate, and di-n-pentyl carbonate.

[0008] Further, the specific application process is as follows: using alcohols and ethylene carbonate as raw materials, an ester exchange reaction is carried out at 90-180℃ under the action of a CuO-CeO2 / ZrO2 supported catalyst to obtain organic carbonates; the alcohols are one of methanol, ethanol, isopropanol, and n-pentanol; the molar ratio between the alcohol and ethylene carbonate is (6-11):1, the amount of CuO-CeO2 / ZrO2 supported catalyst is 11.4% of the mass of ethylene carbonate, and the reaction time is 1-3h.

[0009] Preferably, the organic carbonate is prepared by transesterification at 90°C; the molar ratio between the alcohol and ethylene carbonate is 10:1, and the reaction time is 1 hour.

[0010] Furthermore, the preparation method of the CuO-CeO2 / ZrO2 supported catalyst includes the following steps:

[0011] (1) Cerium nitrate and zirconium nitrate were dissolved in deionized water to form a mixed solution. Then, a precipitant was added to carry out a hydrothermal reaction. After the reaction was completed, the solution was filtered, washed, dried, ground, and then heated to 400℃ and calcined to obtain CeO2 / ZrO2 support.

[0012] (2) The copper acetate aqueous solution was impregnated on the CeO2 / ZrO2 support prepared in step (1), dried, ground, and then heated to 600℃ to calcine to obtain CuO-CeO2 / ZrO2 supported catalyst, and the CuO loading was 4%wt.

[0013] Preferably, in step (1), the molar ratio between cerium nitrate and zirconium nitrate is 6:1; the concentrations of cerium nitrate and zirconium nitrate in the mixed solution are 0.2 mol / L and 0.034 mol / L, respectively; the hydrothermal reaction temperature is 50℃ and the hydrothermal reaction time is 3h.

[0014] Preferably, in step (1), the precipitant is a sodium carbonate aqueous solution with a mass concentration of 42.4%, and the volume ratio of the precipitant to the mixed solution is 1:2.

[0015] Preferably, in step (2), the concentration of the copper acetate aqueous solution is 0.5 mmol / ml, and 1 ml of copper acetate aqueous solution is added to each gram of CeO2 / ZrO2 carrier for impregnation.

[0016] Preferably, the drying temperature in steps (1) and (2) is 80°C and the drying time is 12h.

[0017] Preferably, the heating rate in steps (1) and (2) is 5°C / min.

[0018] Preferably, the calcination time in steps (1) and (2) is 5 hours.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) The raw material ethylene carbonate used in this invention is obtained by the addition of carbon dioxide and ethylene oxide. The CuO-CeO2 / ZrO2 catalyst provided by this invention exhibits excellent catalytic activity, higher DMC selectivity and DMC yield in the transesterification reaction to prepare organic carbonates.

[0021] (2) The CuO-CeO2 / ZrO2 catalyst provided by the present invention does not require activation during the reaction process and maintains high activity even after repeated reactions, thus exhibiting excellent stability.

[0022] (3) The CuO-CeO2 / ZrO2 catalyst preparation method provided by the present invention is simple, the preparation cost is low, and the industrial application prospects are good. The CuO-CeO2 / ZrO2 catalyst prepared has a larger pore size and more pores, which is more conducive to contact with raw materials and improves its catalytic performance. On the other hand, it also has abundant active sites, which promotes the adsorption and activation of methanol and is beneficial to improving the activity of the catalyst. Attached Figure Description

[0023] Figure 1 is a flowchart of the preparation method of CuO-CeO2 / ZrO2 supported catalyst;

[0024] Figure 2 shows scanning electron microscope images of the CeO2 / ZrO2 support (a) and the CuO-CeO2 / ZrO2 supported catalyst (b) prepared in the embodiments of the present invention;

[0025] Figure 3 shows the XRD patterns (a) of the CeO2 / ZrO2 support, CuO-CeO2 / ZrO2 supported catalyst, and CuO-CeO2 / ZrO2 catalyst after 4 cycles prepared in the embodiments of the present invention, and (b) is a partial magnified view of (a).

[0026] Figure 4 shows the N2 adsorption-desorption curves (a) and pore size distribution diagram (b) of the CeO2 / ZrO2 support and CuO-CeO2 / ZrO2 supported catalyst prepared in the embodiments of the present invention.

[0027] Figure 5 shows the XPS spectra of the CeO2 / ZrO2 support and CuO-CeO2 / ZrO2 supported catalyst prepared in the embodiments of the present invention: Cu 2p (a), Zr 3d (b), Ce 3p (c) and O1s (d). Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Unless otherwise specified, all raw materials and reagents used in the following examples are commercially available products with a purity of analytical grade or higher.

[0030] As shown in Figure 1, the preparation process of the CuO-CeO2 / ZrO2 supported catalyst used in the following examples is as follows:

[0031] (1) Dissolve 0.02 mol cerium nitrate and 0.0034 mol zirconium nitrate in deionized water to form a mixed solution, then add 50 mL of an aqueous solution containing 0.0368 g sodium carbonate dropwise, and place it at 50 °C for hydrothermal reaction (stirring for 2 h, aging for 1 h). After the reaction is completed, filter, wash, dry (drying temperature is 80 °C, drying time is 12 h), grind, and then calcine at 400 °C for 5 h at a heating rate of 5 °C / min to obtain CeO2 / ZrO2 support;

[0032] (2) Take 4g of CeO2 / ZrO2 support, dissolve 2mmol of copper acetate in 4ml of deionized water and then impregnate it on the CeO2 / ZrO2 support, dry (drying temperature is 80℃, drying time is 12h), grind, and then calcine at 600℃ for 5h at a heating rate of 5℃ / min to obtain CuO-CeO2 / ZrO2 supported catalyst. As can be seen from Figures 2(a) and (b), the catalyst has a porous plate-like structure after high-temperature calcination, which is more conducive to contact with the raw materials and improves its catalytic performance. As can be seen from Figure 3(a), after CuO is supported, the peak width of the catalyst becomes narrower and the peak intensity increases. Figure 3(b) is a partial magnified view of Figure 3(a). Compared with CeO2 / ZrO2, the peak of CuO-CeO2 / ZrO2 has shifted. The cell parameters of CuO-CeO2 / ZrO2 are as follows: Smaller than the unit cell parameter of pure CeO2 Explanation of Ce 4+ (Radius 0.097 nm) is affected by Zr with a smaller radius. 4+ (radius 0.086 nm) or Cu 2 + (Radius 0.072 nm) substitution forms Ce-Zr solid solution or Cu-Ce-Zr solid solution. Furthermore, the cell parameters of CuO-CeO2 / ZrO2... Cell parameters smaller than CeO2 / ZrO2 Therefore, it can be deduced that Cu 2+A Cu-Ce-Zr solid solution was formed by entering the Ce-Zr lattice. The catalyst was tested using a N2 physical adsorption-desorption analyzer, and the resulting adsorption-desorption isotherms are shown in Figure 4(a). Based on the IUPAC classification, the prepared catalyst exhibits typical type IV adsorption isotherms. From the pore size distribution diagram in Figure 4(b), it can be seen that the average pore size of the catalyst increases after CuO loading, which is beneficial for contact with the raw materials and promotes the reaction. The physical structural characteristics of the catalyst are shown in Table 1. The XPS spectrum of Cu 2p in CuO-CeO2 / ZrO2 is shown in Figure 5(a), indicating a high binding energy Cu 2p. 3 / 2 The appearance of the peak (932.8 eV) and satellite peaks is due to Cu 2+ The presence of the species, as shown in Figure 5(b), indicates that the catalyst contains Zr3d. 5 / 2 and Zr 3d 3 / 2 The two peaks, due to zirconium replacing cerium's lattice positions, result in a higher binding energy for zirconium than for metallic Zr but lower than for ZrO2, as shown in Figure 5(c). The catalyst uses Ce... 4+ Species-based and a small amount of Ce 3+ Species, Ce 3+ Speciation may be due to Zr 4+ Or Cu 2+ Replace Ce 4+ Species-dependent, with 882.4, 888.4, and 897.9 eV attributed to Ce. 4+ 3D 5 / 2 900.85, 907.4, and 916.3 eV belong to Ce 4+ 3D 3 / 2 The peak represented by 884.5 eV belongs to Ce. 3+ As shown in Figure 5(d), the α peak represents the lattice oxygen of the metal oxide, the β peak represents the defect oxygen, and the γ peak represents the surface hydroxyl groups. Surface hydroxyl groups can usually promote catalytic activity.

[0033] Table 1 Physical structural characteristics of the catalyst

[0034] Sample specific surface area (m²) 2 / g) Pore volume (cm³) 2 Average pore size (nm) / g: CeO2 / ZrO2 28.695 0.091 1.267 CuO-CeO2 / ZrO2 14.026 0.149 4.252 surface

[0035] Example 1

[0036] The application of a CuO-CeO2 / ZrO2 supported catalyst in the transesterification preparation of dimethyl carbonate, the specific application process is as follows:

[0037] Performance tests for the synthesis of dimethyl carbonate from methanol and ethylene carbonate were conducted in a microreactor. After the reactor was thoroughly dried, 4.49 g of methanol (0.14 mol) and 1.76 g of ethylene carbonate (0.02 mol) were placed in a reactor equipped with a rotor, and 0.2 g of CuO-CeO2 / ZrO2 supported catalyst was added. The transesterification reaction was carried out at 90 °C for 1 h. After the reaction, the catalyst was separated by centrifugation after the reactor cooled, and the product mixture was quantitatively analyzed by gas chromatography with an FID detector. The content of each product was determined by internal standard method. The conversion rate of ethylene carbonate (EC), the selectivity of organic carbonates, and the yield were calculated according to the following formulas:

[0038]

[0039] The catalyst activity data in the transesterification to dimethyl carbonate are shown in Appendix Table 2.

[0040] Example 2

[0041] The application of a CuO-CeO2 / ZrO2 supported catalyst in the transesterification preparation of diethyl carbonate, the specific application process is as follows:

[0042] Performance testing of the catalyst for the synthesis of diethyl carbonate from ethanol and ethylene carbonate was conducted in a microreactor. The 4.49 g methanol in Example 1 was replaced with 6.45 g ethanol (0.14 mol), and the 90 °C in Example 1 was replaced with 110 °C. The remaining steps were the same as in Example 1. The catalyst activity data in the transesterification to diethyl carbonate are shown in Appendix Table 2.

[0043] Example 3

[0044] The application of a CuO-CeO2 / ZrO2 supported catalyst in the transesterification preparation of diisopropyl carbonate, the specific application process is as follows:

[0045] Performance testing of the catalyst for the synthesis of diisopropyl carbonate from isopropanol and ethylene carbonate was conducted in a microreactor. The 4.49 g methanol in Example 1 was replaced with 8.40 g isopropanol (0.14 mol), and the 90 °C in Example 1 was replaced with 150 °C. The remaining steps were the same as in Example 1. The catalyst activity data in the transesterification to diisopropyl carbonate are shown in Appendix Table 2.

[0046] Example 4

[0047] The application of a CuO-CeO2 / ZrO2 supported catalyst in the transesterification preparation of di-n-pentyl carbonate is as follows:

[0048] Performance testing of the catalyst for the synthesis of di-n-pentyl carbonate from n-pentanol and ethylene carbonate was conducted in a microreactor. The 4.49 g methanol in Example 1 was replaced with 12.34 g n-pentanol (0.14 mol), and the 90 °C in Example 1 was replaced with 160 °C. The remaining steps were the same as in Example 1. The catalyst activity data for the transesterification to di-n-pentyl carbonate are shown in Appendix Table 2.

[0049] Example 5

[0050] Replace 1h with 2h in Example 1, and follow the same steps as in Example 1. Catalyst activity data are shown in Appendix Table 2.

[0051] Example 6

[0052] Replace 1h with 3h in Example 1, and follow the same steps as in Example 1. Catalyst activity data are shown in Appendix Table 2.

[0053] Example 7

[0054] The 4.49g methanol in Example 1 was replaced with 3.84g methanol, and the remaining steps were the same as in Example 1. The catalyst activity data are shown in Appendix Table 2.

[0055] Example 8

[0056] The 4.49g methanol in Example 1 was replaced with 5.13g methanol, and the remaining steps were the same as in Example 1. The catalyst activity data are shown in Appendix Table 2.

[0057] Example 9

[0058] The 4.49g methanol in Example 1 was replaced with 5.77g methanol, and the remaining steps were the same as in Example 1. The catalyst activity data are shown in Appendix Table 2.

[0059] Example 10

[0060] The 4.49g methanol in Example 1 was replaced with 6.41g methanol, and the remaining steps were the same as in Example 1. The catalyst activity data are shown in Appendix Table 2.

[0061] Example 11

[0062] Replace 4.49g of methanol in Example 1 with 7.05g of methanol, and follow the same steps as in Example 1. Catalyst activity data are shown in Appendix Table 2.

[0063] Table 2 Catalytic activity data for each example

[0064]

[0065]

[0066] The activity of the supported catalyst CuO-CeO2 / ZrO2 in the transesterification synthesis of corresponding organic carbonates from methanol, ethanol, isopropanol, n-butanol, n-pentanol, and ethylene carbonate in a batch microreactor was studied, and its performance is shown in Table 2. In Example 6, the yield of organic carbonate decreased slightly after 4 cycles, mainly due to partial catalyst loss after each use, resulting in a decrease in the yield of organic carbonate. However, after 4 cycles, the EC conversion of the catalyst only decreased by about 2%, and the selectivity of organic carbonate remained at 100%, indicating that the catalyst has excellent stability. Comparison of Examples 1 and Examples 7-11 shows that when the ratio of methanol to ethylene carbonate is optimized to 10:1, the catalyst exhibits the best reactivity, achieving the highest yield of organic carbonate at 79.95%.

[0067] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. The application of a CuO-CeO2 / ZrO2 supported catalyst in the transesterification preparation of organic carbonates, wherein the organic carbonate is one of dimethyl carbonate, diethyl carbonate, diisopropyl carbonate, and di-n-pentyl carbonate; the specific application process is as follows: using alcohols and ethylene carbonate as raw materials, under the action of the CuO-CeO2 / ZrO2 supported catalyst, at 90-180 °C... o Organic carbonates are prepared by transesterification at C; the preparation method of the CuO-CeO2 / ZrO2 supported catalyst includes the following steps: (1) Cerium nitrate and zirconium nitrate are dissolved in deionized water to form a mixed solution with a molar ratio of 6:

1. Then, a precipitant is added to carry out a hydrothermal reaction at a temperature of 50°C. o C, the hydrothermal reaction time is 3 hours; after the reaction is completed, the mixture is filtered, washed, dried, ground, and then heated to 400°C. o C calcination yields CeO2 / ZrO2 support; the precipitant is a sodium carbonate aqueous solution with a mass concentration of 42.4%; (2) copper acetate aqueous solution is impregnated on the CeO2 / ZrO2 support prepared in step (1), dried, ground, and then heated to 600°C. o The CuO-CeO2 / ZrO2 supported catalyst was obtained by calcination of C, with a CuO loading of 4%wt.

2. The application of the CuO-CeO2 / ZrO2 supported catalyst according to claim 1 in the transesterification preparation of organic carbonates, characterized in that, The alcohol is one of methanol, ethanol, isopropanol, and n-pentanol; the molar ratio between the alcohol and ethylene carbonate is (6-11):1, the amount of CuO-CeO2 / ZrO2 supported catalyst is 11.4% of the mass of ethylene carbonate, and the reaction time is 1-3 h.

3. The application of the CuO-CeO2 / ZrO2 supported catalyst according to claim 2 in the transesterification preparation of organic carbonates, characterized in that, At 90 o Organic carbonates were prepared by transesterification at C; the molar ratio of the alcohol to ethylene carbonate was 10:1, and the reaction time was 1 h.

4. The application of the CuO-CeO2 / ZrO2 supported catalyst according to claim 1 in the transesterification preparation of organic carbonates, characterized in that, In step (1), the concentrations of cerium nitrate and zirconium nitrate in the mixed solution are 0.2 mol / L and 0.034 mol / L, respectively.

5. The application of the CuO-CeO2 / ZrO2 supported catalyst according to claim 1 in the transesterification preparation of organic carbonates, characterized in that, In step (1), the volume ratio of the precipitant to the mixed solution is 1:

2.

6. The application of the CuO-CeO2 / ZrO2 supported catalyst according to claim 1 in the transesterification preparation of organic carbonates, characterized in that, In step (2), the concentration of the copper acetate aqueous solution is 0.5 mmol / ml, and 1 ml of copper acetate aqueous solution is added to each gram of CeO2 / ZrO2 carrier for impregnation.

7. The application of the CuO-CeO2 / ZrO2 supported catalyst according to claim 1 in the transesterification preparation of organic carbonates, characterized in that, The drying temperature in steps (1) and (2) is 80°C. o C, drying time is 12h.

8. The application of the CuO-CeO2 / ZrO2 supported catalyst according to claim 1 in the transesterification preparation of organic carbonates, characterized in that, The heating rate in steps (1) and (2) is 5. o C / min.

9. The application of the CuO-CeO2 / ZrO2 supported catalyst according to claim 1 in the transesterification preparation of organic carbonates, characterized in that, The calcination time in steps (1) and (2) is 5 hours.

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