Method for synthesizing hollow spherical hydrotalcite-like catalysts and method for using the same in preparing alcohol ether carboxylate

Abstract

This invention belongs to the field of inorganic metal oxide catalysts, and particularly relates to a method for synthesizing hollow spherical hydrotalcite catalysts and their application in the preparation of alcohol ether carboxylic esters. The hollow spherical hydrotalcite catalyst is obtained by crystallization of hydrotalcite-based composite metal oxides, TPAOH, and mesoporous solid spherical precursors. The hollow spherical hydrotalcite catalyst has a particle size of 400–600 nm, a wall thickness of 50–100 nm, and a specific surface area of ​​140–360 m². 2 The MgO / Al2O3 molar ratio is 5–1, with a total pore volume of 0.11–0.39 mL / g, an average pore diameter of 0.2–0.60 nm, and a relative crystallinity of 90%–95%. Advantages: The catalytic reaction process is mild, requires a small amount of catalyst, produces a product with a narrow and easily controlled degree of polymerization, and the preparation process is simple and easy to operate.

Description

Technical Field

[0001] This invention belongs to the field of inorganic metal oxide catalysts, and particularly relates to a method for synthesizing hollow spherical hydrotalcite catalysts and their application in the preparation of alcohol ether carboxylic esters. Background Technology

[0002] Hydrotalcite compounds are an important class of novel inorganic functional materials. Due to their unique layered structure, tunable acid-base properties, good thermal stability, and ion exchange capacity, they have wide applications in catalysis, ion exchange, adsorption, and chemical engineering. In catalysis, hydrotalcite and its calcined products (composite metal oxides) are often used as acid-base dual-center catalysts, redox catalysts, or catalyst supports in various organic reactions, such as aldol condensation, transesterification, methane reforming, and the polymerization and addition reactions of epoxides. The general molecular formula of Mg-Al hydrotalcite is Mg6Al2(OH)CO3·4H2O. Researching novel hydrotalcite systems, through morphological control and pore size regulation, can help improve their catalytic activity in reactions. For example, hollow spherical morphology can effectively shorten molecular diffusion paths and improve the utilization rate of active sites. Pore size confinement control is beneficial for the formation of low molecular weight products of oligomeric alcohol ether esters and restricts the formation of high molecular weight products of polymeric alcohol ether esters.

[0003] In the synthesis of alcohol ether carboxylic esters, especially in the preparation of oligoethylene glycol ether carboxylic esters via the insertion ethoxylation reaction of carboxylic esters with epoxides such as ethylene oxide, the choice of catalyst is crucial. This reaction requires the catalyst to possess suitable acid-base dual centers to activate the ester groups and control product distribution. Therefore, the development of efficient, easily separable, and reusable heterogeneous catalysts is of great significance.

[0004] Composite metal oxides, especially hydrotalcite-derived oxides composed of elements such as magnesium and aluminum, are considered promising heterogeneous catalysts due to their simultaneous presence of Lewis acid and basic sites. Previous studies have shown that their catalytic performance can be significantly affected by controlling the chemical composition, calcination conditions, and microstructure of the hydrotalcite precursor. Patent application CN201310681835.3 discloses a method for preparing composite metal oxides and a method for synthesizing alcohol ether carboxylic esters, using composite metal oxides prepared by fatty acid modification to catalyze the synthesis of alcohol ether carboxylic esters. The composite metal oxides prepared by this method exhibit a significant mesopore distribution, which is beneficial for mass transfer of reactants. However, their pore structure is mostly composed of random stacking of macropores or mesopores, resulting in a wide pore size distribution. In the reaction of carboxylic esters such as butyl acetate with ethylene oxide, although such catalysts can catalyze the reaction, they still suffer from problems such as insufficient catalytic activity, need for improved selectivity of target products, and a wide product distribution. This may be due to the long diffusion path and lack of effective pore confinement, leading to inconsistent residence times of reactant molecules inside the catalyst and an increase in side reactions.

[0005] Therefore, developing a composite metal oxide (hydrotalcite-based) catalyst with a specific hollow spherical morphology and microporous structure is of significant theoretical and practical value for improving the catalytic efficiency, target product selectivity, and controlling product distribution in the insertion ethoxylation reaction of carboxylic esters. The hollow spherical hydrotalcite material synthesized in this invention has shorter channels and smaller pore size, belonging to the microporous category. This allows it to be applied to fields such as ethoxylation catalysis, with significantly enhanced activity, narrower product distribution, and higher selectivity for target products. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, the present invention aims to provide a method for synthesizing hollow spherical hydrotalcite catalysts and their application in the preparation of alcohol ether carboxylic esters. Through specific precursor preparation and secondary crystallization processes, precise control over the catalyst's microstructure and pore structure is achieved. The hollow spherical hydrotalcite catalyst synthesized by the above method is applied to the insertion ethoxylation reaction of carboxylic esters with epoxides to catalyze the synthesis of oligomeric polyethylene glycol butyl ether acetate. The hollow spherical structure and microporous characteristics of the catalyst effectively shorten the diffusion path of reactants and products. Simultaneously, the confinement effect of the micropores preferentially promotes the formation and diffusion of low-polymerization-degree target products while inhibiting the formation of high-polymers, thereby enhancing reaction activity and effectively controlling product distribution.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for synthesizing hollow spherical hydrotalcite catalysts, wherein the hollow spherical hydrotalcite catalyst is obtained by crystallization of hydrotalcite composite metal oxides, TPAOH, and mesoporous solid spherical precursors.

[0008] The hollow spherical hydrotalcite catalyst has a particle size of 400–600 nm, a wall thickness of 50–100 nm, and a specific surface area of ​​140–360 m². 2 / g, total pore volume 0.11~0.39mL / g, average pore diameter 0.2~0.60nm, MgO / Al2O3 molar ratio 5~1, relative crystallinity 90%~95%.

[0009] The hydrotalcite-based composite metal oxide is composed of one or more Group IIA metal oxides and one or more Group IIIA metal oxides, wherein the mass percentage of Group IIA metal oxides is 10% to 70%.

[0010] The Group IIA metal is magnesium and / or calcium; the Group IIIA metal is aluminum and / or gallium.

[0011] The method for preparing the mesoporous solid spherical precursor includes the following steps: 1) Dissolve the cationic surfactant in deionized water, and after the solution becomes clear, add acetone and ammonia. Stir at room temperature until the solution becomes clear and transparent. The molar ratio of the cationic surfactant, deionized water, ammonia, and acetone is (0.05-0.5):(100-500):(0.5-5):(5-300). The cationic surfactant is hexadecyltrimethylammonium bromide. The ammonia solution is a concentrated ammonia solution with a concentration of 25%–28% (volume fraction). The acetone solution is an acetone solution with a concentration of 6.0%–50% (mole fraction).

[0012] 2) Add tetraethyl orthosilicate dropwise to the mixed solution obtained in step 1), and then continue stirring the mixed solution at room temperature for 1.5 to 3 hours to form a mesoporous molecular sieve; The molar ratio of the tetraethyl orthosilicate to the acetone in step 1) is (0.5-2):(5-300). 3) The reaction solution obtained in step 2) is filtered under reduced pressure, washed with deionized water and dried, heated to 520-560℃ and calcined at this temperature for more than 6 hours to obtain a mesoporous solid spherical precursor.

[0013] A method for synthesizing hollow spherical hydrotalcite catalysts includes the following steps: 1) An aqueous solution of hydrotalcite-based composite metal oxide is mixed with a TPAOH solution, wherein the pH value of the TPAOH solution is 8-10; the molar ratio of hydrotalcite-based composite metal oxide to TPAOH is (0.5-12):(0.2-0.5). 2) Under reduced pressure filtration, the mixed solution obtained in step 1) is added dropwise to the mesoporous solid spherical precursor, with the molar ratio of SiO2 to TPAOH being (0.1~2):(0.1~0.5). Then, it is transferred to a crystallization kettle for crystallization under the following conditions: crystallization at 160~180℃ for 1~2 days. 3) The crystallized slurry is filtered, washed, dried, and calcined to obtain hollow spherical hydrotalcite.

[0014] Step 3) The washing is carried out under reduced pressure filtration until the pH of the washing liquid is 6.5 to 7.5; the drying is carried out at 60 to 80°C for 10 to 12 hours; the calcination is carried out at 400 to 600°C for 5 to 10 hours.

[0015] A method for preparing alcohol ether carboxylic acid esters using hollow spherical hydrotalcite catalysts involves synthesizing alcohol ether carboxylic acid esters via epoxide intercalation under the catalysis of a hollow spherical hydrotalcite catalyst. The method specifically includes the following steps: 1) The carboxylic acid ester and hollow spherical hydrotalcite catalyst are added to a high-pressure reactor at room temperature and heated to 80~90℃; 2) Continuously feed epoxides into the reactor and heat it to 100~180℃. The pressure of the high-pressure reactor shall not exceed 0.4MPa. Stir the reactor while feeding epoxides, and gradually increase the stirring speed as the mass of feed increases. The stirring speed shall gradually increase to 220~290r / min. 3) After the feeding is finished, start aging for 25-40 minutes. Stop heating, cool to 80-90℃, filter out the catalyst, and you will get the alcohol ether carboxylic acid ester.

[0016] The carboxylic acid ester is a fatty acid ester, and the epoxide alkane is ethylene oxide; the amount of the hollow spherical hydrotalcite catalyst is 1% to 3% of the reaction output by mass percentage.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention achieves precise control over the hollow spherical structure and microporous properties of the catalyst through specific precursor preparation and secondary crystallization processes. This results in hollow spherical hydrotalcite-based microporous molecular sieve catalysts with uniform particle size, moderate wall thickness (50–100 nm), high specific surface area, suitable total pore volume, and relatively small average pore size, providing abundant active sites and a unique diffusion environment for the reaction. The synthesis of this catalyst is simple, parameters are controllable, and reproducibility is good.

[0018] 2. The method for synthesizing alcohol ether carboxylic esters provided by this invention uses hollow spherical hydrotalcite catalysts. The catalytic reaction conditions are mild, the catalyst dosage is small, the resulting product has a narrow and easily controllable degree of polymerization, and the preparation process is simple and easy to operate. The catalyst is easily separated and recovered by filtration, which conforms to the concepts of green chemistry and atom economy. Attached Figure Description

[0019] Figure 1 This is the gas chromatogram of the oligomeric polyethylene glycol butyl ether acetate obtained in Example 1.

[0020] Figure 2 This is the gas chromatogram of the oligomeric polyethylene glycol butyl ether acetate obtained in Example 2.

[0021] Figure 3 The gas chromatogram of the oligomeric polyethylene glycol butyl ether acetate obtained in Comparative Example 1 is shown.

[0022] Figure 4 The gas chromatogram of the oligomeric polyethylene glycol butyl ether acetate obtained in Comparative Example 2 is shown.

[0023] Figure 5 This is a TEM image of the catalyst used in Example 1.

[0024] Figure 6 The image shows the XRD pattern of the catalyst used in Example 2. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0026] Example 1: 1. Preparation of hollow sphere hydrotalcite catalyst: Weigh 0.62g CTAB and dissolve it in 30g deionized water. After complete dissolution, add 2.6ml ammonia and 8.8g acetone to the solution. Stir at room temperature for about 20 minutes, then add 2.6ml TEOS. The final sol has a molar ratio of TEOS / CTAB / NH3 / H2O / acetone of 1:0.14:1.4:150:10. Continue stirring at room temperature for about 2 hours, then filter, wash with deionized water, and dry the resulting white precipitate in an oven at 60℃ for 1 day. The final powder is then calcined in a muffle furnace at 540℃ for 6 hours to remove the template agent, yielding a solid sphere precursor.

[0027] Weigh 0.192g of Mg(NO3)2·6H2O crystals and 0.113g of Al(NO3)3·9H2O crystals and dissolve them in 5ml of deionized water to prepare a mixed solution of Al(NO3)3 and Mg(NO3)2. Then, dissolve 2.8ml of TPAOH in 5ml of deionized water to prepare another solution. Weigh 4.5g of solid sphere precursor and, under reduced pressure filtration (specific process parameters), add the two prepared solutions together to the solid sphere precursor powder. Then transfer the solution to a crystallization vessel and crystallize at 170℃ for 48 hours. Cool the crystallized slurry to room temperature and wash it under reduced pressure filtration until the pH of the washing solution is close to neutral (pH 6.5–7.5). Dry it at 70℃ for 10 hours and then calcine it at 540℃ for 6 hours. The resulting catalyst is designated Cat-1.

[0028] 2. Preparation of oligomeric polyethylene glycol butyl ether acetate: 50.6 g of butyl acetate and 0.89 g of the hollow spherical hydrotalcite catalyst Cat-1 prepared above were added to a dry and clean high-pressure reactor at room temperature. After checking the airtightness and nitrogen purging, the reactor was heated to 80-90°C. Then, 38.6 g of ethylene oxide was continuously introduced into the reactor, and the temperature was raised to 170°C, while controlling the reactor pressure to not exceed 0.4 MPa. Stirring was carried out while introducing ethylene oxide, and the stirring speed was gradually increased from 160 r / min to 240 r / min as the mass of the feed increased. After the feeding was completed, the feed valve was closed, and aging began for 30 min. Heating was then stopped, and the reactor was cooled to 80-90°C. The pressure inside the reactor was released, the reactor was opened, and the catalyst was filtered out to obtain polyethylene glycol butyl ether acetate.

[0029] Its gas chromatogram is shown below Figure 1 The product content analysis is shown in Table 1.

[0030] Table 1. Component content of the product from Example 1 Depend on Figure 5 As can be seen, the hydrotalcite catalyst has a hollow spherical structure with a particle size of approximately 500 nm, and the spherical walls are dense and uniform with a wall thickness of about 50 nm. The catalyst maintains its good hollow spherical morphology even after calcination at 540°C for 6 hours, indicating its excellent thermal stability. This hollow spherical structure can effectively shorten the molecular diffusion path and significantly improve the utilization rate of the active sites.

[0031] Example 2: 1. Catalyst preparation: Weigh 0.35g CTAB and dissolve it in 35g deionized water. After complete dissolution, add 6.1ml ammonia and 36.5g acetone to the solution. Stir at room temperature for about 20 minutes, then add 3.1ml TEOS. The final sol has a molar ratio of TEOS / CTAB / NH3 / H2O / acetone of 1:0.09:2.6:150:40. Continue stirring at room temperature for about 2 hours, then filter, wash with deionized water, and dry the resulting white precipitate in an oven at 60℃ for 1 day. The final powder is then calcined in a muffle furnace at 540℃ for 6 hours to remove the template agent, yielding a solid sphere precursor.

[0032] Weigh 0.192g of Mg(NO3)2·6H2O crystals and 0.06g of Al(NO3)3·9H2O crystals and dissolve them in 4ml of deionized water to prepare a mixed solution of Al(NO3)3 and Mg(NO3)2. Then, dissolve 3.6ml of TPAOH in 5ml of deionized water to prepare another solution. Weigh 2g of solid sphere precursor and, under reduced pressure filtration, add the two prepared solutions together to the solid sphere precursor powder. Then transfer the solution to a crystallization vessel and crystallize at 170℃ for 48 hours. Cool the crystallized slurry to room temperature and wash it under reduced pressure filtration until the pH of the washing solution is close to neutral (pH 6.5~7.5). Dry it at 60℃ for 10 hours and then calcine it at 600℃ for 8 hours. The resulting catalyst is designated Cat-2.

[0033] 2. Preparation of polyethylene glycol butyl ether acetate: 51.1 g of butyl acetate and 0.90 g of the catalyst Cat-2 prepared in step 1 were added to a dry and clean high-pressure reactor at room temperature. After checking the airtightness and purging with nitrogen, the reactor was heated to 80-90°C. Then, 38.7 g of ethylene oxide was continuously introduced into the reactor, and the temperature was raised to 150°C, while controlling the reactor pressure to not exceed 0.4 MPa. Stirring was carried out while introducing ethylene oxide, and the stirring speed was gradually increased from 160 r / min to 280 r / min as the mass of the feed increased. After the feeding was completed, the feed valve was closed, and aging began for 30 minutes. Heating was then stopped, and the reactor was cooled to 80-90°C. The pressure inside the reactor was released, the reactor was opened, and the catalyst was filtered out to obtain polyethylene glycol butyl ether acetate.

[0034] Its gas chromatogram is shown below Figure 2 The product content analysis is shown in Table 2.

[0035] Table 2. Component content of the product in Example 2 Depend on Figure 6It can be seen that the hollow spherical hydrotalcite catalyst, in addition to exhibiting the characteristic peaks of microporous materials, also possesses the main characteristic peaks of hydrotalcite. Among them, (015)Al2O3 can provide acid centers, (018)MgO can provide base centers, and (110)Mg(Al)O provides both acid and base centers. These characteristics lead to its high reactivity and high selectivity for the target product in the target reaction.

[0036] Comparative Example 1: 1. Catalyst preparation: Weigh 192g of Mg(NO3)2·6H2O crystals and 56g of Al(NO3)3·9H2O crystals and dissolve them in 1L of deionized water to prepare a mixed solution of Al(NO3)3 and Mg(NO3)2. Add 300ml of 0.90mol / L Na2CO3 solution to the above mixed solution. Then, add 2.25mol / L NaOH solution dropwise to the mixed solution to adjust the pH value to 10±0.5. Continue stirring the mixed solution at room temperature for 5-6 hours, then filter, wash until neutral, and dry in an oven at 80℃ for 12 hours.

[0037] Take 10g of the dried sample and add it to 400ml of deionized water containing 0.0025g / mL triethylamine. Boil and reflux for 2 hours, then filter and wash until neutral. Dry in an oven at 80℃ for 12 hours. Finally, calcine in a muffle furnace at 500℃ for 5 hours to obtain the final composite metal oxide catalyst.

[0038] 2. Preparation of polyethylene glycol butyl ether acetate: The preparation process of polyethylene glycol butyl ether acetate is as described in Example 1. Its gas chromatogram is shown below. Figure 3 The product content analysis is shown in Table 3.

[0039] Table 3. Component content of Comparative Example 1 Comparative Example 2: 1. Catalyst preparation: Weigh 192g of Mg(NO3)2·6H2O crystals and 56g of Al(NO3)3·9H2O crystals and dissolve them in 1L of deionized water to prepare a mixed solution of Al(NO3)3 and Mg(NO3)2. Add 300ml of 0.90mol / L Na2CO3 solution to the above mixed solution. Then, add 2.25mol / L NaOH solution dropwise to the mixed solution to adjust the pH value to 10±0.5. Continue stirring the mixed solution at room temperature for about 5-6 hours, then filter, wash until neutral, and dry in an oven at 80℃ for 12 hours. Finally, calcine in a muffle furnace at 500℃ for 5 hours to obtain the final composite metal oxide catalyst.

[0040] 2. Preparation of polyethylene glycol butyl ether acetate: The preparation process of polyethylene glycol butyl ether acetate is as described in Example 1. Its gas chromatogram is shown below. Figure 4 The product content analysis is shown in Table 4.

[0041] Table 4. Component content of Comparative Example 2 The results of comparing the catalyst activities of the above examples and comparative examples are shown in Table 5.

[0042] Table 5. Comparison of catalytic activity of catalysts in the examples and comparative examples. As shown in Table 5, the hollow spherical hydrotalcite catalyst provided by this invention exhibits high activity and a high percentage of the target product (1EO-4EO) in the synthesis reaction of oligoethylene glycol carboxylic acid esters.

[0043] Under the same ethyl acetate ethoxylation reaction conditions, the catalytic activity of the catalysts in Examples 1 and 2 (based on the mass of ethylene oxide converted per unit mass of catalyst per minute, gEO / gCat / min) reached 0.39~0.54, which is much higher than that of the composite metal oxide catalysts prepared by conventional methods (0.28 for Comparative Example 1 and 0.01 for Comparative Example 2).

[0044] The reaction time was significantly shortened; for example, the reaction time of Example 1 (138 minutes) was shorter than that of Comparative Example 1 (155 minutes) and Comparative Example 2 (270 minutes), indicating a faster reaction rate.

[0045] Using the catalyst of this invention, the conversion rate of butyl acetate was significantly improved. The conversion rates of Examples 1 and 2 reached 80.8% and 76.1%, respectively, while those of Comparative Examples 1 and 2 were only 54.9% and 4.2%, respectively.

[0046] The selectivity of the target products (primarily oligoethylene glycol butyl ether acetate with 1-4 ethylene oxide addition numbers (EO)) was significantly better than that of the comparative catalyst. The target product selectivity of Examples 1 and 2 (combined with gas chromatographic data and the trends shown in Table 5) was higher, and the product distribution was more concentrated in the ideal low degree of polymerization range.

[0047] Narrower product distribution, easier to control: results from gas chromatography analysis ( Figure 1 , 2 and Figure 3 , 4 (Comparison) It can be seen that in the products obtained using the catalyst of the present invention, the peak area ratio of oligomers (such as 1EO-4EO) is higher and the distribution is more concentrated, while the formation of high degree of polymerization products is effectively suppressed.

[0048] This is due to the confinement effect of the catalyst micropores, which helps to control the insertion chain length of ethylene oxide and achieve a narrow product distribution.

Claims

1. A method for synthesizing a hollow spherical hydrotalcite catalyst, characterized in that, Hollow spherical hydrotalcite catalysts were obtained by crystallization of hydrotalcite-based composite metal oxides, TPAOH, and mesoporous solid spherical precursors.

2. The method for synthesizing a hollow spherical hydrotalcite catalyst according to claim 1, characterized in that, The hollow spherical hydrotalcite catalyst has a particle size of 400–600 nm, a wall thickness of 50–100 nm, and a specific surface area of ​​140–360 m². 2 / g, total pore volume 0.11~0.39mL / g, average pore diameter 0.2~0.60nm, MgO / Al2O3 molar ratio 5~1, relative crystallinity 90%~95%.

3. The method for synthesizing a hollow spherical hydrotalcite catalyst according to claim 1, characterized in that, The hydrotalcite-based composite metal oxide is composed of one or more Group IIA metal oxides and one or more Group IIIA metal oxides, wherein the mass percentage of Group IIA metal oxides is 10% to 70%.

4. The method for synthesizing a hollow spherical hydrotalcite catalyst according to claim 3, characterized in that, The Group IIA metal is magnesium and / or calcium; the Group IIIA metal is aluminum and / or gallium.

5. The method for synthesizing a hollow spherical hydrotalcite catalyst according to claim 1, characterized in that, The method for preparing the mesoporous solid spherical precursor includes the following steps: 1) Dissolve the cationic surfactant in deionized water, and after the solution becomes clear, add acetone and ammonia. Stir at room temperature until the solution becomes clear and transparent. The molar ratio of the cationic surfactant, deionized water, ammonia, and acetone is (0.05-0.5):(100-500):(0.5-5):(5-300). 2) Add tetraethyl orthosilicate dropwise to the mixed solution obtained in step 1), and then continue stirring the mixed solution at room temperature for 1.5 to 3 hours to form a mesoporous molecular sieve; The molar ratio of the tetraethyl orthosilicate to the acetone in step 1) is (0.5-2):(5-300). 3) The reaction solution obtained in step 2) is filtered under reduced pressure, washed with deionized water and dried, heated to 520-560℃ and calcined at this temperature for more than 6 hours to obtain a mesoporous solid spherical precursor.

6. The method for synthesizing a hollow spherical hydrotalcite catalyst according to claim 1, characterized in that, Includes the following steps: 1) An aqueous solution of hydrotalcite-based composite metal oxide is mixed with a TPAOH solution, wherein the pH value of the TPAOH solution is 8-10; the molar ratio of hydrotalcite-based composite metal oxide to TPAOH is (0.5-12):(0.2-0.5). 2) Under reduced pressure filtration, the mixed solution obtained in step 1) is added dropwise to the mesoporous solid spherical precursor, with the molar ratio of SiO2 to TPAOH being (0.1~2):(0.1~0.5). Then, it is transferred to a crystallization kettle for crystallization under the following conditions: crystallization at 160~180℃ for 1~2 days. 3) The crystallized slurry is filtered, washed, dried, and calcined to obtain hollow spherical hydrotalcite.

7. The method for synthesizing a hollow spherical hydrotalcite catalyst according to claim 6, characterized in that, Step 3) The washing is carried out under reduced pressure filtration until the pH of the washing liquid is 6.5 to 7.5; the drying is carried out at 60 to 80°C for 10 to 12 hours; the calcination is carried out at 400 to 600°C for 5 to 10 hours.

8. A method for using a hollow spherical hydrotalcite catalyst synthesized according to any one of claims 1-7 in the preparation of alcohol ether carboxylic acid esters, characterized in that, Alcohol ether carboxylic esters were synthesized from carboxylic esters via intercalation with epoxide-alkane catalysts under the catalysis of hollow spherical hydrotalcite catalysts.

9. The method for using a hollow spherical hydrotalcite catalyst according to claim 8 in the preparation of alcohol ether carboxylic esters, characterized in that, Includes the following steps: 1) The carboxylic acid ester and hollow spherical hydrotalcite catalyst are added to a high-pressure reactor at room temperature and heated to 80~90℃; 2) Continuously feed epoxides into the reactor and heat it to 100~180℃. The pressure of the high-pressure reactor shall not exceed 0.4MPa. Stir the reactor while feeding epoxides, and gradually increase the stirring speed as the mass of feed increases. The stirring speed shall gradually increase to 220~290r / min. 3) After the feeding is finished, start aging for 25-40 minutes. Stop heating, cool to 80-90℃, filter out the catalyst, and you will get the alcohol ether carboxylic acid ester.

10. A method for using a hollow spherical hydrotalcite catalyst according to claim 8 or 9 in the preparation of alcohol ether carboxylic esters, characterized in that, The carboxylic acid ester is a fatty acid ester, and the epoxide alkane is ethylene oxide; the amount of the hollow spherical hydrotalcite catalyst is 1% to 3% of the reaction output by mass percentage.

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