Preparation method and application of ultra-small highly dispersed cerium oxide catalyst

Abstract

The present invention relates to a method for preparing an ultra-small highly dispersed cerium oxide catalyst, which comprises stirring and mixing a cerium source, an alkali source, a surface active agent and a solvent A to obtain a mixed solution; the mixed solution is subjected to solvent thermal treatment at 80-300°C for 5-36 hours, and the obtained solid is washed and dried, and then roasted at 200-900°C in an air atmosphere for 1-12 hours to obtain an ultra-small highly dispersed cerium oxide. At the same time, the present invention also discloses the use of the ultra-small highly dispersed cerium oxide catalyst in the preparation of cyclic carbonates from CO2 and polyols. The preparation method of the present invention is simple and easy to implement, low in cost and good in universality. The prepared ultra-small highly dispersed cerium oxide between 1 and 8 nm is used as a heterogeneous catalyst, has high activity and high stability, can realize the conversion process of a variety of organic polyols and CO2 to efficiently prepare cyclic carbonates, and is suitable for industrial production.

Description

Technical Field

[0001] The invention relates to the field of cyclic carbonate production, and in particular to a preparation method and application of an ultra-small highly dispersed cerium oxide catalyst. Background Art

[0002] Cyclic carbonates are versatile industrial raw materials and important organic intermediates for the production of fine chemicals such as medicines, pesticides and dyes. They can also be used in polar aprotic solvents, lithium-ion battery electrolyte additives, polymer precursors and fuel additives.

[0003] At present, the mature production processes of cyclic carbonates mainly include polyol and carbonate transesterification, CO2 and epoxide cycloaddition, and direct preparation of cyclic carbonates by CO2 and polyols. Among them, the polyol and carbonate transesterification method is limited by the preparation process of carbonates, and although the CO2 and epoxide cycloaddition method is the process closest to industrialization, epoxide is a toxic and carcinogenic substance, flammable and explosive, and not suitable for long-distance transportation, and has strong regionality. The direct dehydration cyclization reaction of CO2 and polyols to prepare cyclic carbonates is a competitive synthetic route. CO2 as a reaction raw material is cheap and easy to obtain, and biomass-based polyols as renewable resources are widely available. Therefore, the development of efficient catalysts for the direct dehydration cyclization reaction of CO2 and polyols to prepare cyclic carbonates has very important economic and practical significance.

[0004] For the direct preparation of cyclic carbonates from carbon dioxide and polyols, various homogeneous catalysts such as quaternary ammonium salts, quaternary phosphonium salts, and transition metal compounds have been developed (Catalysts 2022, 12, 124). Although these homogeneous catalysts have high catalytic activity, they face the problems of product separation and catalyst recycling. Based on this, heterogeneous catalysts such as metal organic framework (MOF) materials, polymers, supported ionic liquids, and oxide solid solutions have been developed one after another. However, these heterogeneous catalysts generally face the problems of low activity and poor stability. Among many oxides, cerium-based oxides have the advantages of small size effect and quantum effect of nanomaterials, strong redox ability, variable coordination number, and acid-base dual functional sites, which make them have potential application value in catalyzing the direct preparation of cyclic carbonates from CO2 and polyols (J. Chem. Technol. Biotechnol. 2014, 89, 19-33; Front. Energy Res. 2020, 8, 117). However, commercial cerium-based oxide catalysts have a low specific surface area, which results in insufficient active sites and low activity. Therefore, it is of great economic significance to develop efficient and stable heterogeneous catalysts to achieve the direct preparation of cyclic carbonates from CO2 and polyols.

[0005] Chinese patent CN1699282 proposed a method for preparing monodisperse spherical cerium oxide, and the particle size of the obtained cerium oxide spheres is relatively single (about 300nm), and the preparation process is complicated; Chinese patent CN1371867A proposed a method for preparing cerium oxide sol, which has complex procedures and harsh conditions, and the particle size distribution of the final particles is relatively wide (6~200nm); Chinese patent CN108017081B announced a method for preparing nano cerium oxide particles, and the particle size distribution is 10~100nm. In summary, how to effectively synthesize cerium oxide nanoparticles with controllable and uniform particle size and stable performance through a simple process is very urgent and necessary. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing an ultra-small highly dispersed cerium oxide catalyst with simple process, stable product performance and uniform and controllable particle size.

[0007] Another technical problem to be solved by the present invention is to provide application of the ultra-small highly dispersed cerium oxide catalyst.

[0008] In order to solve the above problems, the present invention discloses a method for preparing an ultra-small and highly dispersed cerium oxide catalyst, which is characterized in that: the method refers to stirring and mixing a cerium source, an alkali source, a surface active agent and a solvent A to obtain a mixed solution; the mixed solution is subjected to solvent thermal treatment at 80-300°C for 5-36 hours, and the obtained solid is washed and dried, and then calcined at 200-900°C in an air atmosphere for 1-12 hours to obtain an ultra-small and highly dispersed cerium oxide.

[0009] The cerium source refers to one or two of ammonium cerium nitrate, cerium chloride, cerium nitrate hexahydrate, cerium acetate, cerium sulfate, and cerium carbonate. The molar ratio of the cerium source to the alkali source is 1:1-9.

[0010] The surfactant refers to one or two of anionic surfactants and ionic surfactants, and the concentration of the surfactants in the mixed solution is 0.1-30 mol / L; the anionic surfactant refers to one or two of sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, and sodium dodecyl sulfate; the nonionic surfactant refers to one or two of polyvinyl pyrrolidone and oleic acid.

[0011] The alkali source refers to one or two of an amino organic base and an inorganic base, and the concentration of the amino organic base in the mixed solution is 0.1-20 mol / L; the amino organic base is one or two of formamide, hexamethylenetetramine, urea, ammonia water, ethanolamine, and oleylamine; the inorganic base refers to one or two of sodium carbonate, sodium bicarbonate, sodium hydroxide, and potassium hydroxide.

[0012] The solvent A refers to any one of water, methanol, ethanol, propanol, n-hexanol, 1,4-dioxane, tetrahydrofuran, acetone, and xylene, or a combination of two or more thereof.

[0013] An ultra-small and highly dispersed cerium oxide catalyst prepared by the method as described above.

[0014] The ultra-small highly dispersed cerium oxide catalyst is monodispersed spherical with a particle size of 1-8 nm and a specific surface area of ​​50-240 m 2 / g.

[0015] The use of an ultra-small highly dispersed cerium oxide catalyst in the preparation of cyclic carbonates from CO2 and polyols as described above is characterized in that: in a CO2 atmosphere, a polyol compound solution and the ultra-small highly dispersed cerium oxide catalyst are input into a continuous reactor, or a polyol compound solution, the ultra-small highly dispersed cerium oxide catalyst and a solvent B are added to an intermittent reactor, and the reaction is carried out for 1 to 36 hours under the conditions of a pressure of 1 to 10 MPa and a temperature of 100 to 200°C. After the reaction is completed, the reaction is cooled in an ice water bath to below 10°C to release the unreacted carbon dioxide, thereby obtaining the corresponding cyclic carbonate compound.

[0016] The polyol compound solution refers to one of ethylene glycol, glycerol and 1,2-propylene glycol, and the ratio of the polyol to the ultra-small highly dispersed cerium oxide catalyst is 5-80 mmol: 1-20 mmol.

[0017] The solvent B refers to any one of alcohol solvents, ether solvents, hydrocarbon solvents, and nitrile solvents, or a combination of two or more thereof. The ratio of the solvent B to the ultra-small highly dispersed cerium oxide catalyst is 5-40 mL: 1-20 mmol.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. The present invention adopts a surfactant-assisted solvothermal method, uses cerium salt as the metal cerium source, obtains a uniformly dispersed precursor through solvothermal carbonization, and obtains an ultra-small and highly dispersed cerium-based oxide catalyst through washing, drying, high-temperature calcination, and removal of the surfactant.

[0020] 2. The preparation method of the catalyst of the present invention is simple and easy, low in cost and has good universality. The obtained catalyst has high activity, and after the catalyst is reused for 7 times, the activity does not decrease significantly, and the catalyst has high stability.

[0021] 3. The ultra-small highly dispersed cerium oxide with a size between 1 and 8 nm prepared by the present invention can be used as a heterogeneous catalyst to realize the conversion process of various organic polyols and CO2 to efficiently prepare cyclic carbonates, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0023] Figure 1 This is a TEM image of the catalyst prepared in Example 1 of the present invention.

[0024] Figure 2 This is a TEM image of the catalyst prepared in Example 4 of the present invention.

[0025] Figure 3 The invention discloses a cycle performance of the ultra-small highly dispersed cerium oxide catalyst in the dehydration cyclization reaction of carbon dioxide and 1,2-propylene glycol to prepare propylene carbonate. DETAILED DESCRIPTION

[0026] A method for preparing an ultra-small and highly dispersed cerium oxide catalyst comprises the steps of: stirring and mixing a cerium source, an alkali source, a surface active agent and a solvent A to obtain a mixed solution; placing the mixed solution into a hydrothermal reactor for solvent thermal treatment at 80-300°C for 5-36 hours; washing the obtained solid, drying it at 80°C for 12 hours, and then roasting it at 200-900°C for 1-12 hours in an air atmosphere to remove the surface active agent, thereby obtaining an ultra-small and highly dispersed cerium oxide.

[0027] The cerium source refers to one or two of ammonium cerium nitrate, cerium chloride, hexahydrate cerium nitrate, cerium acetate, cerium sulfate, and cerium carbonate, and the molar ratio of the cerium source to the alkali source is 1:1-9.

[0028] The surfactant refers to one or both of anionic surfactants and ionic surfactants, and the concentration of the surfactants in the mixed solution is 0.1~30 mol / L; the anionic surfactant refers to one or both of sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, and sodium dodecyl sulfate; the nonionic surfactant refers to one or both of polyvinyl pyrrolidone and oleic acid.

[0029] The alkali source refers to one or two of an amino organic base and an inorganic base, and the concentration thereof in the mixed solution is 0.1-20 mol / L; the amino organic base refers to one or two of formamide, hexamethylenetetramine, urea, ammonia water, ethanolamine, and oleylamine; the inorganic base refers to one or two of sodium carbonate, sodium bicarbonate, sodium hydroxide, and potassium hydroxide.

[0030] Solvent A refers to any one of water, methanol, ethanol, propanol, n-hexanol, 1,4-dioxane, tetrahydrofuran, acetone, and xylene, or a combination of two or more thereof.

[0031] The obtained ultra-small highly dispersed cerium oxide can be used as a heterogeneous catalyst. It is monodispersed spherical with a particle size of 1-8 nm and a specific surface area of ​​50-240 m 2 / g.

[0032] The application of the ultra-small highly dispersed cerium oxide catalyst in the preparation of cyclic carbonate from CO2 and polyols: in a CO2 atmosphere, a polyol compound solution and an ultra-small highly dispersed cerium oxide catalyst are introduced into a continuous reactor, or a polyol compound solution, an ultra-small highly dispersed cerium oxide catalyst and a solvent B are added into a batch reactor, and the reaction is carried out for 1 to 36 hours under the conditions of a pressure of 1 to 10 MPa and a temperature of 100 to 200° C. After the reaction is completed, the reaction is cooled in an ice water bath to below 10° C. to release unreacted carbon dioxide, thereby obtaining a corresponding cyclic carbonate compound.

[0033] Wherein: the polyol compound solution refers to one of ethylene glycol, propylene glycol and 1,2-propylene glycol, and the ratio of the polyol to the ultra-small highly dispersed cerium oxide catalyst is 5-80 mmol: 1-20 mmol.

[0034] Solvent B refers to any one or a combination of two or more of alcohol solvents, ether solvents, hydrocarbon solvents, and nitrile solvents, preferably acetonitrile, 1,4-dioxane, benzonitrile, toluene, xylene, tetrahydrofuran, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), 2-cyanopyridine, furan-2-carbonitrile, etc. The ratio of solvent B to ultra-small highly dispersed cerium oxide catalyst is 5-40 mL: 1-20 mmol.

[0035] The obtained cyclic carbonate is one of ethylene carbonate, propylene carbonate and glycerol carbonate.

[0036] Reaction diagram:

[0037]

[0038] Example 1

[0039] 0.8 g of ammonium cerium nitrate, 3.5 g of oleylamine and 1.3 g of oleic acid were stirred in 100 mL of xylene solvent at 100 ° C until clear, and then the mixed solution was heated to 280 ° C and reacted for 3 h. After natural cooling, 100 mL of ethanol was added thereto and centrifuged. Then 100 mL of petroleum ether was added thereto, dissolved and centrifuged again. After repeating 5 times, the obtained sample was dried and calcined in air at 500 ° C for 5 h to obtain a solid powder of cerium oxide nanospheres with a size of 3.8 ± 0.6 nm. Its electron microscope photo is shown as follows Figure 1 shown.

[0040] Example 2

[0041] 0.6 g of cerium acetate and 3.8 g of oleylamine were dissolved in 50 mL of xylene solvent and magnetically stirred for 30 min. Then, the mixture was heated to 90 °C under magnetic stirring, and 1 mL of water was added while stirring. The magnetic stirring was continued for 6 h. The obtained sample was washed with chloroform and ethanol, respectively. After drying, the obtained sample was calcined at 800 °C for 3 h to obtain a light yellow cerium oxide nanosphere solid powder. The particle size was measured to be 5.8±0.4 nm.

[0042] Example 3

[0043] 0.8 g of cerium acetate and 5.1 g of oleylamine were dissolved in 50 mL of xylene solvent and magnetically stirred for 30 min. Then, the mixture was heated to 90 °C under magnetic stirring, and 1 mL of water was added while stirring. The magnetic stirring was continued for 6 h. The obtained sample was washed with chloroform and ethanol, respectively. After drying, the obtained sample was calcined at 700 °C for 6 h to obtain a light yellow cerium oxide nanosphere solid powder. The particle size was measured to be 6.4±0.4 nm.

[0044] Example 4

[0045] 0.8 g of cerium chloride and 1.6 g of sodium dodecylbenzene sulfonate were dissolved in 500 mL of water and magnetically stirred for 45 min. Then, 3.0 M hexamethylenetetramine solution was added at a flow rate of 35 uL / min under magnetic stirring until the pH of the reaction solution was 9. The magnetic stirring was continued for 30 min until the reaction solution was evenly mixed and then transferred to a hydrothermal reactor for reaction at 150 ° C for 24 h. After natural cooling, the sample was washed with water and ethanol. After drying, the obtained sample was calcined at 600 ° C for 12 h to obtain a cerium oxide nanosphere solid powder with a particle size of 8.2 ± 0.3 nm. Its electron microscope photograph is shown as follows: Figure 2 shown.

[0046] Example 5

[0047] 1.2 g of cerium chloride and 2.4 g of sodium dodecylbenzene sulfonate were dissolved in 500 mL of water and magnetically stirred for 45 min. Then, 3.0 M hexamethylenetetramine solution was added at a flow rate of 35 uL / min under magnetic stirring until the pH of the reaction solution was 9. The magnetic stirring was continued for 30 min until the reaction solution was evenly mixed and then transferred to a hydrothermal reactor. The reaction was carried out at 150 ° C for 24 h. After natural cooling, the sample was washed with water and ethanol. The obtained sample was dried and calcined at 400 ° C for 8 h to obtain a solid powder of cerium oxide nanospheres. The particle size was measured to be 7.2±0.3 nm.

[0048] Example 6

[0049] 1.0 g of cerium nitrate hexahydrate and 2.4 g of sodium hexadecylbenzenesulfonate were dissolved in 500 mL of water and magnetically stirred for 45 min. Then, 3.0 M hexamethylenetetramine solution was added at a flow rate of 35 uL / min under magnetic stirring until the pH of the reaction solution was 9. The magnetic stirring was continued for 30 min until the reaction solution was evenly mixed and then transferred to a hydrothermal reactor. The reaction was carried out at 150°C for 24 h. After natural cooling, the sample was washed with water and ethanol. The obtained sample was dried and calcined at 400°C for 8 h to obtain a solid powder of cerium oxide nanospheres. The particle size was measured to be 6.8±0.3 nm.

[0050] Example 7

[0051] 1.2 g of the catalyst prepared in Example 1, 5.0 g of 1,2-propylene glycol, 7.2 mL of 2-cyanopyridine and 20 ml of acetonitrile were weighed and added into a high-pressure reactor. After high-purity argon was introduced to replace the gas 6 times, CO2 was charged to 3.0 MPa, the temperature was raised to 140°C, and the reaction was carried out for 5 hours. After the reaction was completed, the reaction was quickly cooled to room temperature, and then the reaction liquid was centrifuged, the supernatant was taken and analyzed by gas chromatograph, and the reaction system was quantitatively calculated.

[0052] Example 8

[0053] Weigh 1.5 g of the catalyst prepared in Example 2, 4.6 g of ethylene glycol, 8.0 mL of 2-cyanopyridine, and 20 ml of DMF into a high-pressure reactor, introduce high-purity argon to replace the gas 6 times, then charge CO2 to 4.0 MPa, raise the temperature to 160°C, react for 12 h, and after the reaction is completed, quickly cool to room temperature, then centrifuge the reaction solution, take the supernatant, analyze it by gas chromatograph, and perform quantitative calculation on the reaction system.

[0054] Example 9

[0055] Weigh 2.0 g of the catalyst prepared in Example 3, 3.4 g of propylene glycol, and 30 mL of 2-cyanopyridine, add them into a high-pressure reactor, introduce high-purity argon gas to replace the gas 6 times, fill with CO2 to 5.0 MPa, raise the temperature to 120°C, react for 24 h, and after the reaction is completed, quickly cool to room temperature, then centrifuge the reaction solution, take the supernatant and analyze it by gas chromatograph, and perform quantitative calculation on the reaction system.

[0056] Example 10

[0057] Weigh 0.17 g of the catalyst prepared in Example 3, 1.5 g of 1,2-propylene glycol, and 20 ml of 2-cyanopyridine and add them into a high-pressure reactor. After high-purity argon is introduced to replace the gas 6 times, CO2 is charged to 2.0 MPa, the temperature is raised to 150°C, and the reaction is carried out for 15 hours. After the reaction is completed, it is quickly cooled to room temperature, and then the reaction liquid is centrifuged, the supernatant is taken and analyzed by gas chromatography, and the reaction system is quantitatively calculated.

[0058] Embodiment 11

[0059] Weigh 1.0 g of the catalyst prepared in Example 4, 4.5 g of 1,2-propylene glycol, 6.2 mL of furan-2-carbonitrile, and 20 ml of acetonitrile into a high-pressure reactor, introduce high-purity argon gas to replace the gas 6 times, then charge CO2 to 3.0 MPa, raise the temperature to 140°C, and react for 5 hours. After the reaction is completed, quickly cool to room temperature, then centrifuge the reaction solution, take the supernatant, analyze it by gas chromatograph, and perform quantitative calculation on the reaction system.

[0060] Example 12

[0061] Weigh 0.8 g of the catalyst prepared in Example 3, 2.74 g of ethylene glycol, 10 ml of 2-cyanopyridine, and 10 mL of DMF into a high-pressure reactor, introduce high-purity argon to replace the gas 6 times, then charge CO2 to 6.0 MPa, raise the temperature to 150°C, and react for 8 hours. After the reaction is completed, quickly cool to room temperature, then centrifuge the reaction solution, take the supernatant, analyze it by gas chromatograph, and perform quantitative calculation on the reaction system.

[0062] Example 13

[0063] Weigh 2.0 g of the catalyst prepared in Example 5, 3.4 g of propylene glycol, and 30 mL of 2-cyanopyridine, add them into a high-pressure reactor, introduce high-purity argon gas to replace the gas 6 times, fill with CO2 to 4.0 MPa, raise the temperature to 170°C, react for 7 h, and after the reaction is completed, quickly cool to room temperature, then centrifuge the reaction solution, take the supernatant and analyze it by gas chromatograph, and perform quantitative calculation on the reaction system.

[0064] Embodiment 14

[0065] Weigh 0.17 g of the catalyst prepared in Example 6, 1.5 g of 1,2-propylene glycol, 5 ml of 2-cyanopyridine, and 15 mL of acetonitrile into a high-pressure reactor, introduce high-purity argon gas to replace the gas 6 times, then charge CO2 to 2.0 MPa, raise the temperature to 150°C, and react for 28 hours. After the reaction is completed, quickly cool to room temperature, then centrifuge the reaction solution, take the supernatant, analyze it by gas chromatograph, and perform quantitative calculation on the reaction system.

[0066] Embodiment 15

[0067] Weigh 1.2 g of the catalyst prepared in Example 5, 4.8 g of ethylene glycol, 15 mL of 2-cyanopyridine, and 15 mL of acetonitrile into a high-pressure reactor, introduce high-purity argon gas to replace the gas 6 times, then charge CO2 to 1.5 MPa, raise the temperature to 170°C, react for 24 hours, and after the reaction is completed, quickly cool to room temperature, then centrifuge the reaction solution, take the supernatant and analyze it by gas chromatograph, and perform quantitative calculation on the reaction system.

[0068] Example 16

[0069] Weigh 2.0 g of the catalyst prepared in Example 4, 3.4 g of propylene glycol, and 30 mL of 2-cyanopyridine, add them into a high-pressure reactor, introduce high-purity argon gas to replace the gas 6 times, fill with CO2 to 5.0 MPa, raise the temperature to 120°C, react for 24 h, and after the reaction is completed, quickly cool to room temperature, then centrifuge the reaction solution, take the supernatant and analyze it by gas chromatograph, and perform quantitative calculation on the reaction system.

[0070] Embodiment 17

[0071] Weigh 1.0 g of the catalyst prepared in Example 5, 4.5 g of 1,2-propylene glycol, and 30 mL of furan-2-carbonitrile, add them into a high-pressure reactor, introduce high-purity argon gas to replace the gas 6 times, fill with CO2 to 2.0 MPa, raise the temperature to 170°C, react for 12 h, and after the reaction is completed, quickly cool to room temperature, then centrifuge the reaction solution, take the supernatant and analyze it by gas chromatograph, and perform quantitative calculation on the reaction system.

[0072] Embodiment 18

[0073] 0.8 g of the catalyst prepared in Example 2, 4.2 g of 1,2-propylene glycol, 10 mL of 2-cyanopyridine and 15 mL of DMAC were weighed and added into a high-pressure reactor. After high-purity argon was introduced to replace the gas 6 times, CO2 was charged to 1.0 MPa, the temperature was raised to 170°C, and the reaction was carried out for 24 h. After the reaction was completed, the reaction solution was quickly cooled to room temperature, and then the reaction solution was centrifuged, the supernatant was taken and analyzed by gas chromatography, and the reaction system was quantitatively calculated.

[0074] The reaction results of Examples 7 to 18 are shown in Table 1.

[0075] Table 1 Comparison of reaction results under different reaction conditions

[0076]

[0077] As can be seen from Table 1, the present invention has good technical effects, and the conversion rate of the raw material polyol and the selectivity of the target product cyclic carbonate are both relatively ideal.

[0078] Embodiment 19

[0079] The catalyst in Example 1 was recycled (the reaction conditions were the same as those in Example 11). The conversion rate and selectivity of the product of the recycled catalyst were as follows: Figure 3 As shown, it can be seen that the catalyst prepared by the present invention still maintains a very high catalytic effect after being used seven times.

Claims

1. Application of an ultra-small highly dispersed cerium oxide catalyst in the preparation of cyclic carbonates from CO2 and polyols, characterized in that: In a CO2 atmosphere, a polyol compound solution and an ultra-small highly dispersed cerium oxide catalyst are introduced into a continuous reactor, or a polyol compound solution, an ultra-small highly dispersed cerium oxide catalyst and a solvent B are added into a batch reactor, and the reaction is carried out for 1 to 36 hours under the conditions of a pressure of 1 to 10 MPa and a temperature of 100 to 200°C. After the reaction is completed, the reaction is cooled in an ice water bath to below 10°C to release unreacted carbon dioxide, thereby obtaining a corresponding cyclic carbonate compound. The ultra-small highly dispersed cerium oxide catalyst is in a monodispersed spherical shape, with a particle size of 1 to 8 nm and a specific surface area of ​​50 to 240 m 2 / g; the preparation method of the ultra-small highly dispersed cerium oxide catalyst is to stir and mix a cerium source, an alkali source, a surfactant and a solvent A to obtain a mixed solution; the mixed solution is subjected to solvent thermal treatment at 80-300°C for 5-36h, and the obtained solid is washed and dried, and then roasted at 200-900°C in an air atmosphere for 1-12h to obtain an ultra-small highly dispersed cerium oxide; the cerium source is one or two of ammonium cerium nitrate, cerium chloride, hexahydrate cerium nitrate, cerium acetate, cerium sulfate, and cerium carbonate, and the molar ratio of the cerium source to the alkali source is 1:1-9; the concentration of the alkali source in the mixed solution is 0.1-20 mol / L; the surfactant is one or two of anionic surfactants and nonionic surfactants; the anionic surfactant is one or two of sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, and sodium dodecyl sulfate; the nonionic surfactant is one or two of polyvinyl pyrrolidone and oleic acid.

2. The use of an ultra-small highly dispersed cerium oxide catalyst as claimed in claim 1 in the preparation of cyclic carbonates from CO2 and polyols, characterized in that: The concentration of the surfactant in the mixed solution is 0.1-30 mol / L.

3. The use of an ultra-small highly dispersed cerium oxide catalyst as claimed in claim 1 in the preparation of cyclic carbonates from CO2 and polyols, characterized in that: The alkali source refers to one or two of an amino organic base and an inorganic base; the amino organic base is one or two of formamide, hexamethylenetetramine, urea, ammonia water, ethanolamine, and oleylamine; the inorganic base refers to one or two of sodium carbonate, sodium bicarbonate, sodium hydroxide, and potassium hydroxide.

4. The use of an ultra-small highly dispersed cerium oxide catalyst as claimed in claim 1 in the preparation of cyclic carbonates from CO2 and polyols, characterized in that: The solvent A refers to any one of water, methanol, ethanol, propanol, n-hexanol, 1,4-dioxane, tetrahydrofuran, acetone, and xylene, or a combination of two or more thereof.

5. The use of an ultra-small highly dispersed cerium oxide catalyst as claimed in claim 1 in the preparation of cyclic carbonates from CO2 and polyols, characterized in that: The polyol compound solution refers to one of ethylene glycol, glycerol and 1,2-propylene glycol, and the ratio of the polyol to the ultra-small highly dispersed cerium oxide catalyst is 5-80 mmol: 1-20 mmol.

6. The use of an ultra-small highly dispersed cerium oxide catalyst as claimed in claim 1 in the preparation of cyclic carbonates from CO2 and polyols, characterized in that: The solvent B refers to any one of alcohol solvents, ether solvents, hydrocarbon solvents, and nitrile solvents, or a combination of two or more thereof. The ratio of the solvent B to the ultra-small highly dispersed cerium oxide catalyst is 5-40 mL: 1-20 mmol.

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