Ionic liquid induced bimetallic oxide as well as preparation method and application thereof

Abstract

The invention provides a bimetallic oxide and a preparation method and application thereof, and the preparation method comprises the following steps: dissolving a cerium salt precursor and a metal A precursor in water to obtain a mixed salt solution; dissolving an ionic liquid in a solvent to obtain an ionic liquid solution; and mixing the mixed salt solution and the ionic liquid solution, adding a complexing agent, and carrying out solvothermal reaction, solid-liquid separation and calcination to obtain the bimetallic oxide. According to the invention, the long-chain alkyl ionic liquid is used as a key structure-directing agent, so that the microstructure and active sites of the cerium-based bimetallic oxide are effectively regulated and controlled. In a catalytic reaction, by virtue of a unique component synergistic effect of the prepared bimetallic oxide, the activation capacity on CO2 is remarkably enhanced, conversion of low-carbon alcohol is efficiently promoted, the important role of the long-chain alkyl ionic liquid in construction of an efficient bimetallic catalytic material is highlighted, and the bimetallic oxide is simple in preparation process, excellent in performance and suitable for industrial production. And a novel way with high value is provided for industrial production of carbonic ester.

Description

Technical Field

[0001] This invention relates to the field of chemical catalysis technology, and in particular to an ionic liquid-induced bimetallic oxide, its preparation method, and its application. Background Technology

[0002] Carbon dioxide (CO2) is a major component of greenhouse gases, and its excessive emissions have triggered a series of environmental problems. At the same time, CO2 is also an abundant, non-toxic, and inexpensive renewable C1 resource. Realizing its high-value-added resource utilization and converting inorganic carbon into chemicals is of great strategic significance. However, current mainstream carbon capture and storage (CCS) technologies are insufficient for the effective conversion of CO2. Among these technologies, using CO2 as a starting material to replace traditional toxic carbonyl sources such as phosgene in the synthesis of carbonates is one of the important directions for realizing the resource utilization of CO2.

[0003] Carbonates are important chemical products, widely used in lithium-ion battery electrolytes, polycarbonate materials, and other fields, directly supporting the development of cutting-edge industries such as new energy and electronic information. The market predicts that by 2025, my country's total demand for carbonates will reach several million tons, making the development of efficient carbonate synthesis technologies urgent. Among numerous synthetic routes, the direct synthesis of carbonates from CO2 and lower alcohols (such as methanol, ethanol, and ethylene glycol) has become a research hotspot due to its high atom economy, inexpensive and readily available raw materials, and its origin in coal chemical industry.

[0004] However, this reaction faces core challenges due to thermodynamic equilibrium limitations and high kinetic energy barriers. To address these issues, researchers have developed various catalytic systems, including homogeneous systems such as alkali metal catalysts, which suffer from separation difficulties; heterogeneous systems, where metal oxides are among the most widely studied catalysts, and their catalytic performance is highly dependent on their morphology, pore structure, and the degree of exposure of active sites. However, metal oxides prepared by traditional methods often suffer from small specific surface area, insufficient active sites, and difficulty in structural control, resulting in limited catalytic efficiency, especially for CO2 activation at low temperatures; supported metal catalysts and metal-organic framework materials, while showing good potential, suffer from drawbacks such as high cost or poor hydrothermal stability; and ionic liquid catalysts, which have good adsorption and activation capabilities for CO2, are mostly used in homogeneous form, facing challenges in recycling and reuse.

[0005] In recent years, researchers have begun to explore strategies that combine the superior properties of ionic liquids with the easily separable properties of heterogeneous catalysts. Among these, utilizing ionic liquids as "structure inducers" or "soft templates" to regulate the synthesis of metal oxides has shown great potential. The unique anion and cation structures of ionic liquids can guide the self-assembly of precursors during material synthesis, effectively controlling the microstructure of the products, increasing specific surface area, and creating abundant defect sites. However, how to design specific ionic liquid structures and efficiently apply them to induce the synthesis of high-performance bimetallic oxide catalysts for the direct production of carbonates from CO2 and lower alcohols remains a challenge, lacking in-depth and effective research, particularly regarding the application of long-chain alkyl functionalized ionic liquids in this field. Existing catalytic systems still generally suffer from harsh reaction conditions (high temperature and high pressure) and difficulties in simultaneously achieving carbonate yield and selectivity.

[0006] Therefore, developing an innovative heterogeneous catalyst that is simple to prepare, low in cost, and can significantly improve CO2 activation efficiency and low-carbon alcohol conversion rate is crucial for promoting the industrialization of direct CO2 preparation of carbonates. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention provides a bimetallic oxide catalyst with simple preparation process, inexpensive and readily available raw materials, and significantly improved catalytic performance.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing ionic liquid-induced bimetallic oxides, the method comprising the following steps:

[0010] The cerium salt precursor and the metal A precursor were dissolved in water to obtain a mixed salt solution;

[0011] An ionic liquid is dissolved in a solvent to obtain an ionic liquid solution;

[0012] The mixed salt solution and the ionic liquid solution are mixed, and a complexing agent is added. The mixture is then subjected to a solvothermal reaction, solid-liquid separation, and calcination to obtain the bimetallic oxide.

[0013] The ionic liquid comprises any one or a combination of at least two of the structures shown in Formula I, Formula II, or Formula III, wherein R1, R2, R3, or R4 each independently comprises C8-C 16 Straight-chain and / or branched alkyl groups, for example, can be C8, C9, C6, C7, C8, C9 ... 10 C 11 C 12 C 13 C 14 C 15 Or C 16Straight-chain and / or branched alkyl groups, such as n-octyl, n-nonyl, n-decyl, n-dodecyl, n-hexadecyl, isooctyl, isonyl, isodecyl, or isotracene, etc., X - Including Br - Cl - I - or OH - Any one of them.

[0014]

[0015] The bimetallic oxide catalyst provided by this invention has a unique microstructure induced by a specific ionic liquid and abundant surface defects, which can expose more active sites.

[0016] The ionic liquids of this invention include 1-hexadecyl-3-methylimidazolium bromide, hexadecyltrimethylammonium bromide, hexadecyltributylphosphine bromide, 1-octyl-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium bromide, 1-hexadecyl-3-methylimidazolium chloride, 1-hexadecyl-3-methylimidazolium iodide, or 1-hexadecyl-3-methylammonium hydroxide, etc.

[0017] As a preferred technical solution of the present invention, the cerium salt precursor includes any one or a combination of at least two of cerium nitrate, cerium chloride, cerium acetylacetonate, or cerium ammonium nitrate. Typical but non-limiting combinations include combinations of cerium nitrate and cerium chloride, combinations of cerium nitrate and cerium acetylacetonate, combinations of cerium acetylacetonate and cerium chloride, combinations of cerium ammonium nitrate and cerium chloride, etc.

[0018] Preferably, the metal A precursor includes any one or a combination of at least two of ferric nitrate, cobalt nitrate, nickel nitrate, magnesium nitrate, manganese nitrate, praseodymium nitrate, yttrium nitrate, or zirconium nitrate. Typical but non-limiting combinations include combinations of ferric nitrate and cobalt nitrate, ferric nitrate and nickel nitrate, nickel nitrate and cobalt nitrate, ferric nitrate and manganese nitrate, etc.

[0019] As a preferred technical solution of the present invention, the molar concentration of the cerium salt precursor in the mixed salt solution is 0.03-0.5 M, for example, it can be 0.03 M, 0.06 M, 0.1 M, 0.2 M, 0.3 M, 0.4 M or 0.5 M, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, the molar concentration of the metal A precursor in the mixed salt solution is 0.02-0.26 M, for example, it can be 0.02 M, 0.06 M, 0.10 M, 0.14 M, 0.18 M, 0.22 M or 0.26 M, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] As a preferred technical solution of the present invention, the molar concentration of the ionic liquid in the ionic liquid solution is 0.2-0.5 M, for example, it can be 0.2 M, 0.3 M, 0.4 M or 0.5 M, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] Preferably, the solvent includes ethylene glycol.

[0023] As a preferred technical solution of the present invention, the complexing agent includes any one or a combination of at least two of citric acid, acetic acid, monoethanolamine, diethanolamine, polyvinylpyrrolidone or polyethylene glycol. Typical but non-limiting combinations include combinations of citric acid and acetic acid, combinations of citric acid and monoethanolamine, combinations of monoethanolamine and acetic acid, combinations of citric acid and polyethylene glycol, etc.

[0024] Preferably, the molar concentration of the complexing agent is 0.5-1 M, for example, it can be 0.5 M, 0.6 M, 0.7 M, 0.8 M, 0.9 M or 1.0 M, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] As a preferred technical solution of the present invention, the temperature of the solvothermal reaction is 100-180℃, for example, it can be 100℃, 120℃, 140℃, 160℃ or 180℃, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0026] Preferably, the solvothermal reaction time is 6-24 h, for example, it can be 6 h, 10 h, 14 h, 18 h, 22 h or 24 h, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0027] Preferably, the calcination temperature is 300-800℃, for example, it can be 300℃, 350℃, 400℃, 450℃, 500℃, 550℃ or 600℃, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0028] Preferably, the calcination time is 2-6 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] In a second aspect, the present invention provides a bimetallic oxide, which is prepared by the preparation method described in the first aspect.

[0030] As a preferred embodiment of the present invention, the bimetallic oxide is used to catalyze the reaction of carbon dioxide and lower alcohols to synthesize carbonates.

[0031] The reaction temperature for synthesizing carbonates by catalytic reaction of carbon dioxide and lower alcohols according to the present invention is 90-140℃, for example, 90℃, 100℃, 110℃, 120℃, 130℃ or 140℃, etc., and the reaction time is 0.5-4 h, for example, 0.5h, 1.0 h, 1.5 h, 2.0 h, 2.5 h, 3.0 h, 3.5 h or 4.0 h, etc., but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0032] The low-carbon alcohols described in this invention include any one or a combination of at least two of methanol, ethanol, or ethylene glycol.

[0033] As a preferred technical solution of the present invention, the feed molar ratio of the bimetallic oxide to the low-carbon alcohol is 1.5:(5-50), for example, it can be 1.5:5, 1.5:10, 1.5:15, 1.5:20, 1.5:25, 1.5:30, 1.5:35, 1.5:40, 1.5:45 or 1.5:50, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0034] Preferably, the reaction for synthesizing the carbonate includes a dehydrating agent.

[0035] Adding a dehydrating agent to the reaction system can remove the water produced in the reaction and shift the reaction equilibrium to the right.

[0036] The dehydrating agent of the present invention includes any one or a combination of at least two of 2-cyanopyridine, 3-cyanopyridine or 4-cyanopyridine.

[0037] Preferably, the feed molar ratio of the bimetallic oxide to the dehydrating agent is 1.5:(25-75), for example, it can be 1.5:25, 1.5:30, 1.5:35, 1.5:40, 1.5:45, 1.5:50, 1.5:55, 1.5:60, 1.5:65, 1.5:70 or 1.5:75, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] Compared with existing technical solutions, the present invention has at least the following beneficial effects:

[0039] (1) Excellent catalyst performance: This invention utilizes a specific long-chain alkyl ionic liquid as an inducer, and through its template effect and steric hindrance, effectively regulates the nucleation and growth process of bimetallic oxides. The resulting catalyst has a large specific surface area, rich pore structure, and fully exposed active sites, exhibiting excellent activation ability for both CO2 and low-carbon alcohols.

[0040] (2) Mild reaction conditions: Under the catalyst and reaction conditions, the present invention can achieve efficient conversion of CO2 to carbonates at a lower temperature (90-140℃) and a shorter time (0.5-4 h), with high yield and selectivity of carbonates, reducing energy consumption and operating costs;

[0041] (3) Green and economical process: The preparation method is simple, the ionic liquid used is designable and has good stability, the raw material metal salt is cheap and readily available, and the whole process is easy to scale up, providing a valuable and environmentally friendly catalyst selection and technical path for the industrial production of carbonates. Attached Figure Description

[0042] Figure 1 This is a transmission electron microscope (TEM) image of Ce-Zr bimetal;

[0043] Figure 2 This is the X-ray diffraction (XRD) pattern of the Ce-M bimetallic catalyst. Detailed Implementation

[0044] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0045] In one specific embodiment, the present invention provides a method for preparing and applying ionic liquid-induced bimetallic oxides, the method and application comprising the following steps:

[0046] Weigh out a cerium salt precursor and a metal A precursor, dissolve them in deionized water, and stir until clear to obtain a mixed salt solution. The molar concentration of the cerium salt precursor in the mixed salt solution is 0.03-0.5 M, and the molar concentration of the metal A precursor is 0.02-0.26 M. Then, dissolve the ionic liquid in ethylene glycol to obtain an ionic liquid solution with a molar concentration of 0.2-0.5 M. Mix the mixed salt solution and the ionic liquid solution, add a complexing agent with a molar concentration of 0.5-1 M, and subject the mixture to a solvothermal reaction at 100-180℃ for 6-24 h, solid-liquid separation, and calcination at 300-800℃ for 2-6 h to obtain the bimetallic oxide.

[0047] It should be clarified that any use of the process provided in the embodiments of the present invention or any substitution or change of conventional data falls within the protection and disclosure scope of the present invention.

[0048] Example 1

[0049] This embodiment provides a method for preparing and applying ionic liquid-induced bimetallic oxides, the preparation method and application including the following steps:

[0050] Weigh out cerium nitrate hexahydrate (Ce source) and zirconium nitrate pentahydrate (Zr source), dissolve in 2 mL of deionized water, and stir until clear to obtain a mixed salt solution. The molar concentration of the cerium salt precursor in the mixed salt solution is 0.1 M, and the molar concentration of the metal A precursor is 0.05 M. Then, dissolve 1-hexadecyl-3-methylimidazolium bromide in 50 mL of ethylene glycol to obtain an ionic liquid solution with a molar concentration of 0.27 M. Mix the mixed salt solution and the ionic liquid solution, add a complexing agent with a molar concentration of 0.7 M, and perform a solvothermal reaction at 130 °C for 18 h, followed by solid-liquid separation and calcination at 500 °C for 2 h to obtain the bimetallic oxide.

[0051] Catalytic performance test: 0.0015 mol of the bimetallic oxide catalyst, 0.01 mol of methanol, and 0.05 mol of 2-cyanopyridine (ncatalyst:nmethanol:ndehydrating agent = 1.5:10:50) were added to a 50 mL high-pressure reactor. CO2 was introduced to a pressure of 3 MPa, and the reaction was carried out at 100 °C for 1 h.

[0052] Example 2

[0053] This embodiment provides a method for preparing and applying ionic liquid-induced bimetallic oxides. The preparation method and application include the following steps:

[0054] Weigh out cerium nitrate hexahydrate (Ce source) and zirconium nitrate pentahydrate (Zr source), dissolve in 2 mL of deionized water, and stir until clear to obtain a mixed salt solution. The molar concentration of the cerium salt precursor in the mixed salt solution is 0.03 M, and the molar concentration of the metal A precursor is 0.26 M. Then, dissolve 1-hexadecyl-3-methylimidazolium bromide in 50 mL of ethylene glycol to obtain an ionic liquid solution with a molar concentration of 0.2 M. Mix the mixed salt solution and the ionic liquid solution, add a complexing agent with a molar concentration of 1.0 M, and perform a solvothermal reaction at 100 °C for 24 h, followed by solid-liquid separation and calcination at 800 °C for 2 h to obtain the bimetallic oxide.

[0055] Catalytic performance test: 0.0015 mol of the bimetallic oxide catalyst, 0.005 mol of ethylene glycol, and 0.025 mol of 2-cyanopyridine (ncatalyst:nmethanol:ndehydrating agent = 1.5:5:25) were added to a 50 mL high-pressure reactor. CO2 was introduced to a pressure of 3 MPa, and the reaction was carried out at 90 °C for 1 h.

[0056] Example 3

[0057] This embodiment provides a method for preparing and applying ionic liquid-induced bimetallic oxides. The preparation method and application include the following steps:

[0058] Weigh out cerium nitrate hexahydrate (Ce source) and zirconium nitrate pentahydrate (Zr source), dissolve in 2 mL of deionized water, and stir until clear to obtain a mixed salt solution. The molar concentration of the cerium salt precursor in the mixed salt solution is 0.5 M, and the molar concentration of the metal A precursor is 0.02 M. Then, dissolve 1-hexadecyl-3-methylimidazolium bromide in 50 mL of ethylene glycol to obtain an ionic liquid solution with a molar concentration of 0.5 M. Mix the mixed salt solution and the ionic liquid solution, add a complexing agent with a molar concentration of 0.5 M, and perform a solvothermal reaction at 180 °C for 6 h, solid-liquid separation, and calcination at 300 °C for 6 h to obtain the bimetallic oxide.

[0059] Catalytic performance test: 0.0015 mol of the bimetallic oxide catalyst, 0.05 mol of ethanol, and 0.075 mol of 2-cyanopyridine (ncatalyst:nmethanol:ndehydrating agent = 1.5:50:75) were added to a 50 mL high-pressure reactor. CO2 was introduced to a pressure of 3 MPa, and the reaction was carried out at 140 °C for 1 h.

[0060] Example 4

[0061] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that "zirconium nitrate pentahydrate" is replaced with an equimolar amount of "cobalt nitrate hexahydrate". All other aspects are the same as those of Example 1.

[0062] Example 5

[0063] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Embodiment 1 is that "zirconium nitrate pentahydrate" is replaced with an equimolar amount of "ferric nitrate nonahydrate". All other aspects are the same as in Embodiment 1.

[0064] Example 6

[0065] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that "zirconium nitrate pentahydrate" is replaced with an equimolar amount of "nickel nitrate hexahydrate". All other aspects are the same as in Example 1.

[0066] Example 7

[0067] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that "zirconium nitrate pentahydrate" is replaced with an equimolar amount of "magnesium nitrate hexahydrate". All other aspects are the same as in Example 1.

[0068] Example 8

[0069] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that "zirconium nitrate pentahydrate" is replaced with an equimolar amount of "manganese nitrate pentahydrate". All other aspects are the same as in Example 1.

[0070] Example 9

[0071] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that "zirconium nitrate pentahydrate" is replaced with an equimolar amount of "praseodymium nitrate hexahydrate". All other aspects are the same as in Example 1.

[0072] Example 10

[0073] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that "zirconium nitrate pentahydrate" is replaced with an equimolar amount of "yttrium nitrate hexahydrate". All other aspects are the same as in Example 1.

[0074] Example 11

[0075] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that "1-hexadecyl-3-methylimidazolium bromide" is replaced with an equimolar amount of "hexadecyltrimethylammonium bromide". All other aspects are the same as in Example 1.

[0076] Example 12

[0077] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that "1-hexadecyl-3-methylimidazolium bromide" is replaced with an equimolar amount of "hexadecyltributylphosphine bromide". All other aspects are the same as in Example 1.

[0078] Example 13

[0079] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that "1-hexadecyl-3-methylimidazolium bromide" is replaced with an equimolar amount of "1-octyl-3-methylimidazolium chloride". All other aspects are the same as in Example 1.

[0080] Example 14

[0081] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that "1-hexadecyl-3-methylimidazolium bromide" is replaced with an equimolar amount of "1-dodecyl-3-methylimidazolium bromide". All other aspects are the same as in Example 1.

[0082] Example 15

[0083] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that "1-hexadecyl-3-methylimidazolium bromide" is replaced with an equimolar amount of "1-hexadecyl-3-methylimidazolium chloride". All other aspects are the same as in Example 1.

[0084] Example 16

[0085] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that "1-hexadecyl-3-methylimidazolium bromide" is replaced with an equimolar amount of "1-hexadecyl-3-methylimidazolium iodide". All other aspects are the same as in Example 1.

[0086] Example 17

[0087] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that "1-hexadecyl-3-methylimidazolium bromide" is replaced with an equimolar amount of "1-hexadecyl-3-methylammonium hydroxide". All other aspects are the same as in Example 1.

[0088] Example 18

[0089] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that in Example 1 is that the catalytic reaction temperature is adjusted from 100℃ to 90℃, while the rest are the same as in Example 1.

[0090] Example 19

[0091] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that in Example 1 is that the catalytic reaction temperature is adjusted from 100℃ to 140℃, while the rest are the same as in Example 1.

[0092] Example 20

[0093] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that the amount of methanol used in the catalytic reaction is changed to 0.005 mol (n catalyst:n methanol = 1.5:5), and all other aspects are the same as in Example 1.

[0094] Example 21

[0095] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that the amount of methanol used in the catalytic reaction is changed to 0.05 mol (n catalyst:n methanol = 1.5:50), while other conditions remain unchanged. All other conditions are the same as in Example 1.

[0096] Example 22

[0097] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that the amount of the dehydrating agent 2-cyanopyridine in the catalytic reaction is changed to 0.025 mol (n catalyst:n dehydrating agent = 1.5:25), and the rest is the same as that of Example 1.

[0098] Example 23

[0099] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that the amount of the dehydrating agent 2-cyanopyridine in the catalytic reaction is changed to 0.075 mol (n catalyst:n dehydrating agent = 1.5:75), and the rest is the same as that of Example 1.

[0100] Example 24

[0101] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that in Example 1 is that the reaction time in the catalytic reaction is changed from 1 h to 0.5 h, while the rest is the same as in Example 1.

[0102] Example 25

[0103] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that in Example 1 is that the reaction time in the catalytic reaction is changed from 1 h to 4 h, while the rest is the same as in Example 1.

[0104] Example 26

[0105] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that the raw material in the catalytic reaction is changed from methanol to ethanol. All other aspects are the same as those in Example 1.

[0106] Example 27

[0107] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that the raw material in the catalytic reaction is changed from methanol to ethylene glycol. All other aspects are the same as in Example 1.

[0108] Example 28

[0109] This embodiment provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and that of Example 1 is that 2-cyanopyridine dehydrating agent is not added in the catalytic reaction, while the rest are the same as in Example 1.

[0110] Comparative Example 1

[0111] This comparative example provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and Example 1 is that no ionic liquid is added; all other aspects are the same as in Example 1.

[0112] Comparative Example 2

[0113] This comparative example provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and Example 1 is that the ionic liquid is replaced with a short-chain alkyl 1-ethyl-3-methylimidazolium bromide, while the rest are the same as in Example 1.

[0114] Comparative Example 3

[0115] This comparative example provides a method for preparing and applying an ionic liquid-induced bimetallic oxide. The only difference between the preparation method and application and Example 1 is that zirconium nitrate is not added, and only cerium nitrate is used. All other aspects are the same as in Example 1.

[0116] The test results of Examples 1-28 and Comparative Examples 1-3 are shown in Table 1:

[0117] Table 1

[0118]

[0119] As can be seen from Table 1, the present invention provides C8-C 16 Ce-A bimetallic oxide catalysts synthesized by long-chain alkyl ionic liquids can significantly improve the yield of CO2 and low-carbon alcohols to carbonates under specific optimized process and application conditions, effectively solving problems such as low catalyst efficiency and harsh reaction conditions.

[0120] A comprehensive comparison of Examples 1 and 18-19 reveals that the temperature range set in this application is key to improving the yield. The yield reaches 79.4% at 100°C, while it drops significantly to 63.4% and 57.7% at 90°C and 140°C, respectively. This indicates that the selected temperature range optimally balances the reaction rate and equilibrium; too low a temperature results in a slow reaction, while too high a temperature easily triggers side reactions.

[0121] A comparative analysis of Examples 1 and 28 shows that a dehydrating agent is indispensable for disrupting reaction equilibrium and increasing yield. Under the same conditions, the yield reached 79.4% with the dehydrating agent, while the yield was only 1.2% without it. The dehydrating agent powerfully shifts the reaction equilibrium to the right by continuously removing the water generated in the reaction.

[0122] A comprehensive comparison of Example 1 and Comparative Examples 1-2 reveals that long-chain alkyl ionic liquids are key to forming highly active structures. Example 1, using a long-chain alkyl ionic liquid, achieved a yield of 79.4%, significantly higher than the yields without using a long-chain alkyl liquid (35.6%) or with using a short-chain ionic liquid (44.7%). This indicates that long-chain alkyl groups are crucial for constructing a microenvironment that efficiently activates the reactants.

[0123] A comparative analysis of Example 1 and Comparative Example 3 shows that the synergistic effect of bimetallic catalysts is significantly better than that of monometallic catalysts. Example 1, using a bimetallic catalyst, achieved a yield of 79.4%, while Comparative Example 3, using a monometallic catalyst, only achieved a yield of 47.5%. This demonstrates that bimetallic components, through synergistic action, can more effectively activate reactants and improve overall catalytic efficiency.

[0124] The present invention has been illustrated with the above embodiments to illustrate its detailed structural features. However, the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing ionic liquid-induced bimetallic oxides, characterized in that, The preparation method includes the following steps: The cerium salt precursor and the metal A precursor were dissolved in water to obtain a mixed salt solution; An ionic liquid is dissolved in a solvent to obtain an ionic liquid solution; The mixed salt solution and the ionic liquid solution are mixed, and a complexing agent is added. The mixture is then subjected to a solvothermal reaction, solid-liquid separation, and calcination to obtain the bimetallic oxide. The ionic liquid comprises any one or a combination of at least two of the structures shown in Formula I, Formula II, or Formula III, wherein R1, R2, R3, or R4 each independently comprises C8-C 16 Straight-chain and / or branched alkyl groups, X - Including Br - Cl - I - or OH - Any one of them.

2. The preparation method according to claim 1, characterized in that, The cerium salt precursor includes any one or a combination of at least two of cerium nitrate, cerium chloride, cerium acetylacetone, or cerium ammonium nitrate.

3. The preparation method according to claim 1 or 2, characterized in that, The metal A precursor includes any one or a combination of at least two of the following: ferric nitrate, cobalt nitrate, nickel nitrate, magnesium nitrate, manganese nitrate, praseodymium nitrate, yttrium nitrate, or zirconium nitrate.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The molar concentration of the cerium salt precursor in the mixed salt solution is 0.03-0.5 M; Preferably, the molar concentration of the metal A precursor in the mixed salt solution is 0.02-0.26 M.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The molar concentration of the ionic liquid in the ionic liquid solution is 0.2-0.5 M; Preferably, the solvent includes ethylene glycol.

6. The preparation method according to any one of claims 1 to 5, characterized in that, The complexing agent includes any one or a combination of at least two of citric acid, acetic acid, monoethanolamine, diethanolamine, polyvinylpyrrolidone, or polyethylene glycol; Preferably, the molar concentration of the complexing agent is 0.5-1 M.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The temperature of the solvothermal reaction is 100-180℃; Preferably, the solvothermal reaction takes 6-24 hours; Preferably, the calcination temperature is 300-800℃; Preferably, the calcination time is 2-6 hours.

8. A bimetallic oxide catalyst, characterized in that, The bimetallic oxide catalyst is obtained by the preparation method according to any one of claims 1 to 7.

9. The bimetallic oxide catalyst according to claim 8, characterized in that, The bimetallic oxide is used to catalyze the reaction of carbon dioxide and lower alcohols to synthesize carbonates. Preferably, the reaction temperature for synthesizing the carbonate is 90-140°C; Preferably, the reaction time for synthesizing the carbonate is 0.5-4 h.

10. The bimetallic oxide catalyst according to claim 9, characterized in that, The feed molar ratio of the bimetallic oxide to the low-carbon alcohol is 1.5:(5-50); Preferably, the reaction for synthesizing the carbonate includes a dehydrating agent; Preferably, the feed molar ratio of the bimetallic oxide to the dehydrating agent is 1.5:(25-75).

Images