Modified resin catalysts, methods for their preparation, and their use in ketal reactions

Abstract

The application relates to the technical field of fine chemicals, and discloses a modified resin catalyst, a preparation method thereof and application of the modified resin catalyst in a ketal reaction. The modified resin catalyst comprises a strong acid type cation exchange resin and cerium sulfate loaded on the strong acid type cation exchange resin, and the content of the strong acid type cation exchange resin is 75-95% by weight and the content of the cerium sulfate is 5-25% by weight based on the total weight of the modified resin catalyst. The catalyst is used in a condensation reaction of acetone and ethylene glycol, a higher 2,2-dimethyl-1,3-dioxolane yield can be obtained, and the stability of the catalyst is better.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fine chemical technology, in particular, to a modified resin catalyst, a preparation method thereof and application thereof in ketal reaction. BACKGROUND

[0002] Ketals (aldehydes) are an important class of carbonyl compounds, which are products obtained by condensation of carbonyl compounds and dihydric alcohols under acidic conditions. They are commonly used in the synthesis of steroids and sugars, carbonyl protection of organic compounds, paints and as intermediates and target products in the pharmaceutical industry; due to the floral, fruity or special aroma of ketal compounds, and the long-lasting fragrance, the chemical properties are stable, so they are also commonly used in perfumes, such as wine, soft drinks, ice cream, cosmetics, etc. for flavoring and fragrance fixing; at the same time, ketal perfumes can also be used to prepare chicken flavor, meat flavor, butter flavor and other edible flavors. Therefore, ketal has great market development potential, which has attracted the attention of a large number of researchers.

[0003] There are many synthesis methods of ketals, among which the most commonly used is the condensation of ketone compounds and alcohol compounds under the action of catalysts.

[0004] Among them, 2,2-dimethyl-1,3-dioxolane is an important intermediate of a new process of petrochemical product ethylene glycol. The 1,3-dioxolane compound can be used as a solvent to replace the commonly used solvents such as dichloromethane, dichloroethane and butanone in industry, and can also be used as a solvent for polymers (Kirk-Othmer Encydopedia of Chemical Technology, John Wllley, Sons, Now Pork, Vol. 12: page 710).

[0005] In the prior art, when preparing 2,2-dimethyl-1,3-dioxolane, the catalysts used are mainly proton acid catalysts (including inorganic acids and organic acids) or Lewis acid catalysts. Acid catalysts have the disadvantages of easy corrosion of equipment, large amount of use, difficult separation of products, low selectivity of products, easy environmental pollution and the like when catalyzing the cyclization reaction. Therefore, it is still of positive significance to seek a ketal catalyst with strong catalytic activity, high selectivity and easy separation from the reaction system. The ketal catalyst for heterogeneous reaction is a relatively active research field at present.

[0006] Currently, reported catalysts that can replace concentrated sulfuric acid include strong-acid ion exchange resins, heteropolyacids, ionic liquids, and solid superacids, with promising results. Among these, strong-acid ion exchange resins have attracted widespread attention due to their advantages, including insolubility in the reaction system, good stability, high selectivity, low cost, and ease of separation. Strong-acid ion exchange resins are polymer materials containing acidic functional active ingredients and exhibit strong catalytic activity in esterification, aldehyde-ketone condensation, and etherification. However, the acid strength of strong-acid cation exchange resins is weaker than that of sulfuric acid, and when used alone as ketal catalysts, the reaction rate is slower than that of concentrated sulfuric acid.

[0007] Therefore, it is necessary to modify it to improve its catalytic activity. For researchers, developing high-performance ketal catalysts to improve reaction efficiency and inhibit the formation of by-products is an important future work direction. Summary of the Invention

[0008] The present invention aims to overcome the problems of low target product yield and poor catalyst stability in the current production process of 2,2-dimethyl-1,3-dioxolane, and to provide a modified resin catalyst, a preparation method thereof, and application thereof in a ketal reaction. The catalyst is used in the condensation reaction of acetone and ethylene glycol, can obtain a higher yield of 2,2-dimethyl-1,3-dioxolane, and has better catalyst stability.

[0009] To achieve the above object, the first aspect of the present invention provides a modified resin catalyst, wherein the modified resin catalyst comprises a strong acid cation exchange resin and cerium sulfate supported on the strong acid cation exchange resin, and based on the total weight of the modified resin catalyst, the content of the strong acid cation exchange resin is 75-95 weight%, and the content of the cerium sulfate is 5-25 weight%.

[0010] A second aspect of the present invention provides a method for preparing a modified resin catalyst, wherein the preparation method comprises:

[0011] (1) mixing cerium sulfate with an acidic aqueous solution to obtain a yellow transparent aqueous solution;

[0012] (2) contacting the yellow transparent aqueous solution with a strong acidic cation exchange resin to react to obtain a mixture;

[0013] (3) filtering the mixture to obtain a solid product, and then washing and drying the solid product in sequence to obtain a modified resin catalyst.

[0014] The third aspect of the present invention provides a modified resin catalyst prepared by the aforementioned preparation method.

[0015] A fourth aspect of the present invention provides a method for preparing 2,2-dimethyl-1,3-dioxolane, wherein the preparation method comprises: contacting acetone and ethylene glycol in the presence of a modified resin catalyst and a water-carrying agent to carry out a condensation reaction, wherein the modified resin catalyst comprises the modified resin catalyst described above.

[0016] Through the above technical solution, compared with the prior art, the technical solution of the present invention has the following advantages:

[0017] 1. The modified resin catalyst provided by the present invention uses a strong acid cation exchange resin as raw material and can be directly used in industry without further shaping.

[0018] 2. The raw materials of the modified resin catalyst provided by the present invention are easily available, the preparation method is simple, the conditions are easy to control, the product has good reproducibility, and is suitable for large-scale production.

[0019] 3. The catalyst provided by the present invention is used to synthesize 2,2-dimethyl-1,3-dioxolane under mild process conditions and has low requirements for the reaction apparatus. The target product yield is high and the catalyst has good stability.

[0020] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0021] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0022] As described above, the first aspect of the present invention provides a modified resin catalyst, wherein the modified resin catalyst comprises a strong acid cation exchange resin and cerium sulfate supported on the strong acid cation exchange resin, and based on the total weight of the modified resin catalyst, the content of the strong acid cation exchange resin is 75-95% by weight, and the content of the cerium sulfate is 5-25% by weight.

[0023] The inventors of the present invention discovered that, in the prior art, catalysts used in ketone-alcohol condensation reactions are categorized into two types: homogeneous and heterogeneous. Homogeneous catalysts primarily include inorganic acid solutions and organic acids, while heterogeneous catalysts primarily include solid acid catalysts and supported catalysts. Homogeneous catalysts have the advantages of low cost and good catalytic activity, but they are gradually being phased out due to drawbacks such as difficulty separating the product from the catalyst, numerous side reactions, and equipment corrosion. While heterogeneous catalysts address the issues of difficult product separation and severe equipment corrosion, they are rarely used in industrial production due to drawbacks such as poor catalytic stability and low product yields. Compared to these catalysts, using strong-acid cation exchange resins as catalysts is a better choice for producing ketal products. Resin catalysts offer advantages such as high selectivity, low cost, and easy separation. However, the acid strength of strong-acid cation exchange resins is weaker than that of sulfuric acid, and when used alone as condensation catalysts, the reaction rate is slower than that of concentrated sulfuric acid. Furthermore, the active groups of strong-acid cation exchange resins are primarily sulfonic acid groups, and in ion exchange resins, the bond between the sulfonic acid groups and the polymer is not very strong. During the condensation reaction, the sulfonic acid group in the active center is easily detached and dissolved in the reaction system, resulting in poor catalyst stability.

[0024] Furthermore, during the development of ketal catalysts, the inventors discovered that by modifying a strong-acid cation exchange resin with cerium sulfate, a ketal catalyst with excellent performance can be obtained. On the one hand, after the strong-acid ion exchange resin is modified with cerium sulfate, the rare earth metal ions react with the sulfonic acid groups of the ion exchange resin's functional groups to form new strong acid centers, which can significantly increase the number of acid centers on the catalyst and thus promote improved catalytic performance. On the other hand, cerium sulfate is not easily soluble in organic reaction systems, avoiding the problem of active centers falling off and dissolving, and can improve the stability of the catalyst. For these reasons, the modified resin catalyst can exhibit good catalytic activity and stability when used in ketone-alcohol condensation reactions, and has a high yield of the target product.

[0025] In addition, in industrial production, heterogeneous catalysts must be formed before use. The appearance of the modified resin catalyst is the same as that of the strong acid cation exchange resin, and no further forming is required, so it can be used directly as an industrial catalyst.

[0026] According to the present invention, the modified resin catalyst includes a strong-acid cation exchange resin and cerium sulfate. Preferably, based on the total weight of the modified resin catalyst, the strong-acid cation exchange resin comprises 80-92% by weight, and the cerium sulfate comprises 8-20% by weight. More preferably, the strong-acid cation exchange resin comprises 84-90% by weight, and the cerium sulfate comprises 10-16% by weight. In the present invention, the use of the aforementioned specific strong-acid cation exchange resin and cerium sulfate content enables the prepared catalyst to have a better yield of the target product and catalyst stability when used in a ketone-alcohol condensation reaction.

[0027] According to the present invention, the strong acid cation exchange resin is an ion exchange resin with a strong acid sulfonic acid group (-SO3H) on a cross-linked polymer matrix. The structure of the strong acid cation exchange resin can be represented by R-SO3H (wherein R represents the polymer matrix).

[0028] According to the present invention, the specific surface area of ​​the strong acid cation exchange resin is 20-40m 2 / g, and the pore volume is 0.2-0.3mL / g.

[0029] According to the present invention, the strong acid cation exchange resin is commercially available, including ion exchange resin model D009 purchased from Kairui Environmental Protection Technology Co., Ltd., and ion exchange resin models DA330 and DA345 purchased from Dandong Mingzhu Special Resin Co., Ltd.

[0030] According to the present invention, the specific surface area of ​​the modified resin catalyst is 16-25m 2 / g, and a pore volume of 0.14-0.20 mL / g; preferably, the specific surface area of ​​the modified resin catalyst is 20-22 m 2 / g, and the pore volume is 0.15-0.18mL / g.

[0031] A second aspect of the present invention provides a method for preparing a modified resin catalyst, wherein the preparation method comprises:

[0032] (1) mixing cerium sulfate with an acidic aqueous solution to obtain a yellow transparent aqueous solution;

[0033] (2) contacting the yellow transparent aqueous solution with a strong acidic cation exchange resin to react to obtain a mixture;

[0034] (3) filtering the mixture to obtain a solid product, and then washing and drying the solid product in sequence to obtain a modified resin catalyst.

[0035] According to the present invention, in step (1), the acidic aqueous solution is selected from one or more of sulfuric acid, nitric acid and hydrochloric acid, preferably sulfuric acid.

[0036] According to the present invention, in step (1), the mass concentration of the acidic aqueous solution is 0.2-30%, preferably 0.5-20%.

[0037] According to the present invention, in step (1), the weight ratio of the cerium sulfate to the acidic aqueous solution is 1:(10-300), preferably 1:(20-200).

[0038] According to the present invention, in step (1), the conditions for mixing the cerium sulfate and the acidic aqueous solution include: a temperature of 40-100° C. and a time of 0.5-12 hours; preferably, a temperature of 60-90° C. and a time of 2-8 hours. Preferably, to achieve a better mixing effect, rapid stirring or ultrasonic means can be used to improve the mixing efficiency during the mixing process of the cerium sulfate and the acidic aqueous solution.

[0039] According to the present invention, in step (2), the weight ratio of the cerium sulfate to the strong acid cation exchange resin is 1:(3-20), preferably 1:(5-10).

[0040] According to the present invention, in step (2), the conditions for the reaction of the strong acidic cation exchange resin with the yellow transparent aqueous solution include: a temperature of 60-110° C., preferably 70-100° C., and a reaction time of 0.5-8 hours, preferably 1-6 hours. Preferably, in order to achieve a better contact reaction effect, rapid stirring can be performed during the contact reaction between the strong acidic cation exchange resin and the yellow transparent aqueous solution to improve the reaction effect.

[0041] According to the present invention, in step (3), there are no special requirements for the filtration, and the filtration method can be any filtration method known in the art, including gravity filtration, pressure filtration, vacuum filtration, or centrifugal filtration. Preferably, the filtration process specifically includes: using a suction bottle, vacuuming the bottom side of the funnel, or filtering using a centrifugal filter.

[0042] According to the present invention, in step (3), there are no particular requirements for the method of washing the solid product. For example, the solid product can be washed with deionized water, the volume ratio of deionized water to solid product can be 5-20, and the number of washings can be 2-8. Preferably, in order to achieve a better washing effect, rapid stirring can be performed during the mixing of the deionized water and the solid product.

[0043] According to the present invention, in step (3), the drying conditions include: temperature of 60-180° C., preferably 80-150° C.; time of 1-30 h, preferably 3-20 h.

[0044] The third aspect of the present application provides a modified resin catalyst prepared by the preparation method described above.

[0045] The fourth aspect of the present application provides a preparation method of 2,2-dimethyl-1,3-dioxolane, wherein the preparation method comprises: contacting acetone and ethylene glycol in the presence of a modified resin catalyst and a water-carrying agent to perform a condensation reaction, wherein the modified resin catalyst comprises the modified resin catalyst described above.

[0046] According to the present application, the water-carrying agent is selected from cyclohexane and / or benzene.

[0047] According to the present application, the weight ratio of the modified resin catalyst, the water-carrying agent, acetone and ethylene glycol is 1:(3-20):(5-30):(8-40).

[0048] According to the present application, the condensation reaction is performed under the following conditions: temperature is 60-100℃, preferably 70-90℃; time is 0.5-10h, preferably 1-6h.

[0049] The present application will be described in detail below through examples.

[0050] In the following examples and comparative examples:

[0051] The pore structure parameter analysis of the sample is performed on an ASAP2020-M+C adsorber purchased from Micromeritics Corporation of the United States. The sample is vacuum degassed at 40℃ for 4 hours before determination, the specific surface area of the sample is calculated by BET method, and the pore volume is calculated by BJH model.

[0052] The elemental analysis experiment of the sample is performed on an Eagle III energy dispersive X-ray fluorescence spectrometer produced by EDAX Corporation of the United States.

[0053] The rotary evaporator is produced by IKA Corporation of Germany, and the model is RV10 digital.

[0054] The drying oven is produced by Shanghai Yiheng Scientific Instrument Co., Ltd., and the model is DHG-9030A.

[0055] The ion exchange resin with the model D009 is purchased from Kerry Environmental Protection Technology Co., Ltd.; the ion exchange resins with the models DA330 and DA345 are purchased from Dandong Mingzhu Special Resin Co., Ltd.; the reagents used in the examples and comparative examples are purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd., and the purity of the reagents is analytical pure.

[0056] Example 1

[0057] This embodiment is intended to illustrate the modified resin catalyst of the present invention, its preparation method, and application.

[0058] (1) Preparation of modified resin catalyst

[0059] In a round-bottom flask, mix 3.0 g of anhydrous cerium sulfate and 250 g of 8% sulfuric acid aqueous solution, heat to 70°C in a water bath and stir for 4 h to obtain a yellow transparent aqueous solution;

[0060] 20g of D009 ion exchange resin was added to the yellow transparent aqueous solution (the weight ratio of cerium sulfate to strong acid cation exchange resin was 1:6.7). The temperature was raised to 80°C and stirred under reflux for 4 hours. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed four times with 500ml of deionized water and dried in air at 110°C for 6 hours to obtain modified resin catalyst A.

[0061] The structural parameters and composition of modified resin catalyst A are listed in Table 1.

[0062] (2) Catalyst reaction performance evaluation

[0063] To a 100ml three-necked flask, add 11.6g of acetone, 18.6g of ethylene glycol, 10g of cyclohexane with water, and 1g of modified resin catalyst A. Install a thermometer, water trap, and reflux condenser. Heat and reflux until almost no water is removed. After the reaction is complete, cool the reaction system to room temperature and drain the aqueous layer. Filter the reaction mixture to recover the catalyst. Wash the filtrate with saturated brine and then distilled water. Combine the organic layers, dry over anhydrous magnesium sulfate, and first recover cyclohexane (boiling point 80-81°C) by distillation. Then, collect the product, 2,2-dimethyl-1,3-dioxolane (boiling point 92-93°C), by distillation. Weigh and calculate the yield. The experimental results are listed in Table 2.

[0064] (3) Evaluation of the performance of the first recovered catalyst for reuse

[0065] The ketal reaction performance of the catalyst was evaluated according to the method in step (2), except that the "modified resin catalyst A" was replaced with the "first recovery catalyst A". The experimental results are listed in Table 2.

[0066] (4) Evaluation of the performance of the second recovered catalyst for reuse

[0067] The ketal reaction performance of the catalyst was evaluated according to the method in step (2), except that the "modified resin catalyst A" was replaced with the "secondary recovery catalyst A". The experimental results are listed in Table 2.

[0068] Example 2

[0069] This embodiment is intended to illustrate the modified resin catalyst of the present invention, its preparation method, and application.

[0070] (1) Preparation of modified resin catalyst

[0071] In a round-bottom flask, mix 2.3 g of anhydrous cerium sulfate and 300 g of a 4% sulfuric acid aqueous solution, heat to 90°C in a water bath and stir for 2 h to obtain a yellow transparent aqueous solution;

[0072] 20g of DA330 ion exchange resin was added to the yellow transparent aqueous solution (the weight ratio of cerium sulfate to strong acid cation exchange resin was 1:8.7). The temperature was raised to 100°C and stirred under reflux for one hour. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed three times with 500ml of deionized water and dried in air at 150°C for three hours to obtain modified resin catalyst B.

[0073] The structural parameters and composition of modified resin catalyst B are listed in Table 1.

[0074] The ketal reaction performance of catalyst B and recovered catalyst B was tested according to the method of steps (2) to (4) in Example 1. The experimental results are listed in Table 2.

[0075] Example 3

[0076] This embodiment is intended to illustrate the modified resin catalyst of the present invention, its preparation method, and application.

[0077] (1) Preparation of modified resin catalyst

[0078] In a round-bottom flask, mix 3.8 g of anhydrous cerium sulfate and 150 g of a 10% aqueous sulfuric acid solution, heat to 60°C in a water bath, and stir for 8 h to obtain a yellow transparent aqueous solution.

[0079] 20g of DA345 ion exchange resin was added to the above-mentioned yellow transparent aqueous solution (the weight ratio of cerium sulfate to strong acid cation exchange resin was 1:5.3). The temperature was raised to 70°C and stirred under reflux for 6 hours. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed eight times with 600ml of deionized water and dried in air at 80°C for 20 hours to obtain modified resin catalyst C.

[0080] The structural parameters and composition of modified resin catalyst C are listed in Table 1.

[0081] The ketal reaction performance of catalyst C and recovered catalyst C was tested according to the method of steps (2) to (4) in Example 1. The experimental results are listed in Table 2.

[0082] Example 4

[0083] This embodiment is intended to illustrate the modified resin catalyst of the present invention, its preparation method, and application.

[0084] Modified resin catalyst D was prepared in the same manner as in Example 1, except that the preparation conditions of the catalyst in step (1) of Example 1 were changed, specifically:

[0085] (1) Preparation of modified resin catalyst

[0086] In a round-bottom flask, mix 1.8 g of anhydrous cerium sulfate and 360 g of a 2% sulfuric acid aqueous solution, heat to 70°C in a water bath, and stir for 4 h to obtain a yellow transparent aqueous solution.

[0087] 20g of D009 ion exchange resin was added to the above-mentioned yellow transparent aqueous solution (the weight ratio of cerium sulfate to strong acid cation exchange resin was 1:11.1). The temperature was raised to 80°C and stirred under reflux for 4 hours. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed four times with 500ml of deionized water and dried in air at 110°C for 6 hours to obtain modified resin catalyst D.

[0088] The structural parameters and composition of modified resin catalyst D are listed in Table 1.

[0089] The ketal reaction performance of catalyst D and recovered catalyst D was tested according to the method of steps (2) to (4) in Example 1. The experimental results are listed in Table 2.

[0090] Example 5

[0091] Modified resin catalyst E was prepared in the same manner as in Example 3, except that the preparation conditions of the catalyst in step (1) of Example 3 were changed, specifically:

[0092] (1) Preparation of modified resin catalyst

[0093] In a round-bottom flask, mix 5.0 g of anhydrous cerium sulfate and 100 g of a 13% aqueous sulfuric acid solution, heat to 60°C in a water bath, and stir for 8 h to obtain a yellow transparent aqueous solution.

[0094] 20g of DA345 ion exchange resin was added to the above-mentioned yellow transparent aqueous solution (the weight ratio of cerium sulfate to strong acid cation exchange resin was 1:4.0). The temperature was raised to 70°C and stirred under reflux for 6 hours. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed eight times with 400ml of deionized water and dried in air at 80°C for 20 hours to obtain modified resin catalyst E.

[0095] The structural parameters and composition of modified resin catalyst E are listed in Table 1.

[0096] The ketal reaction performance of catalyst E and recovered catalyst E was tested according to the method of steps (2) to (4) in Example 1. The experimental results are listed in Table 2.

[0097] Example 6

[0098] This embodiment is intended to illustrate the modified resin catalyst of the present invention, its preparation method, and application.

[0099] Modified resin catalyst F was prepared in the same manner as in Example 1, except that the preparation conditions of the catalyst in step (1) of Example 1 were changed, specifically:

[0100] (1) Preparation of modified resin catalyst

[0101] In a round-bottom flask, mix 1.1 g of anhydrous cerium sulfate and 330 g of a 1% sulfuric acid aqueous solution, heat to 70°C in a water bath, and stir for 4 h to obtain a yellow transparent aqueous solution.

[0102] 20g of D009 ion exchange resin was added to the above-mentioned yellow transparent aqueous solution (the weight ratio of cerium sulfate to strong acid cation exchange resin was 1:18.2). The temperature was raised to 80°C and stirred under reflux for 4 hours. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed four times with 500ml of deionized water and dried in air at 110°C for 6 hours to obtain modified resin catalyst F.

[0103] The structural parameters and composition of modified resin catalyst F are listed in Table 1.

[0104] The ketal reaction performance of Catalyst F and recovered Catalyst F was tested according to the method of steps (2) to (4) in Example 1. The experimental results are listed in Table 2.

[0105] Example 7

[0106] This embodiment is intended to illustrate the modified resin catalyst of the present invention, its preparation method, and application.

[0107] Modified resin catalyst G was prepared in the same manner as in Example 3, except that the preparation conditions of the catalyst in step (1) of Example 3 were changed, specifically:

[0108] (1) Preparation of modified resin catalyst

[0109] In a round-bottom flask, mix 6.7 g of anhydrous cerium sulfate and 80 g of a 15% sulfuric acid aqueous solution, heat to 60°C in a water bath, and stir for 8 h to obtain a yellow transparent aqueous solution.

[0110] 20 g of ion exchange resin of type DA345 (the weight ratio of cerium sulfate to the strong acid type cation exchange resin is 1 :3.0) was added to the above yellow transparent aqueous solution, and the temperature was raised to 70 °C, and the reaction was stirred under reflux for 6 hours. The reaction system was cooled to room temperature, and the solid product was obtained by filtration. The solid product was washed with 400 ml of deionized water for 8 times, and dried in air at 80 °C for 20 hours to obtain the modified resin catalyst G.

[0111] The structural parameters and composition of the modified resin catalyst G are listed in Table 1.

[0112] The performance test of the ketal reaction of catalyst G and the recovered catalyst G was carried out according to the method of steps (2) to (4) in Example 1. The experimental results are listed in Table 2.

[0113] Comparative Example 1

[0114] Ion exchange resin of type D009 was used as catalyst D1. The structural parameters and composition of catalyst D1 are listed in Table 1.

[0115] The performance test of the ketal reaction of catalyst D1 and the recovered catalyst D1 was carried out according to the method of steps (2) to (4) in Example 1. The experimental results are listed in Table 2.

[0116] Comparative Example 2

[0117] Ion exchange resin of type DA330 was used as catalyst D2. The structural parameters and composition of catalyst D2 are listed in Table 1.

[0118] The performance test of the ketal reaction of catalyst D2 and the recovered catalyst D2 was carried out according to the method of steps (2) to (4) in Example 1. The experimental results are listed in Table 2.

[0119] Comparative Example 3

[0120] Ion exchange resin of type DA345 was used as catalyst D3. The structural parameters and composition of catalyst D3 are listed in Table 1.

[0121] The performance test of the ketal reaction of catalyst D3 and the recovered catalyst D3 was carried out according to the method of steps (2) to (4) in Example 1. The experimental results are listed in Table 2.

[0122] Comparative Example 4

[0123] The modified resin catalyst D4 was prepared according to the same method as in Example 1, except that the preparation conditions of the catalyst in step (1) in Example 1 were changed, specifically:

[0124] (1) Preparation of modified resin catalyst

[0125] In a round bottom flask, 0.4 g of anhydrous cerium sulfate and 200 g of an aqueous solution of sulfuric acid with a concentration of 2% were mixed, heated to 70°C in a water bath and stirred for 4 h to obtain a yellow transparent aqueous solution;

[0126] 20 g of ion exchange resin of type D009 was added to the above yellow transparent aqueous solution, the weight ratio of cerium sulfate to strong acid type cation exchange resin was 1:50, heated to 80°C, and stirred for 4 h under reflux; the reaction system was cooled to room temperature, and the solid product was obtained by filtration. The solid product was washed with 500 ml of deionized water for 4 times, and dried in air at 110°C for 6 h to obtain the modified resin catalyst D4.

[0127] The structural parameters and composition of the modified resin catalyst D4 are listed in Table 1.

[0128] The performance test of the ketal reaction of the catalyst D4 and the recovered catalyst D4 was carried out according to the method of steps (2) to (4) in Example 1. The experimental results are listed in Table 2.

[0129] Comparative Example 5

[0130] The modified resin catalyst D5 was prepared according to the same method as in Example 2, except that the preparation conditions of the catalyst in step (1) of Example 2 were changed, specifically:

[0131] (1) Preparation of modified resin catalyst

[0132] In a round bottom flask, 7.5 g of anhydrous cerium sulfate and 250 g of an aqueous solution of sulfuric acid with a concentration of 15% were mixed, heated to 90°C in a water bath and stirred for 2 h to obtain a yellow transparent aqueous solution;

[0133] 10 g of ion exchange resin of type DA330 was added to the above yellow transparent aqueous solution, the weight ratio of cerium sulfate to strong acid type cation exchange resin was 1:1.3, heated to 100°C, and stirred for 1 h under reflux; the reaction system was cooled to room temperature, and the solid product was obtained by filtration. The solid product was washed with 500 ml of deionized water for 3 times, and dried in air at 150°C for 3 h to obtain the modified resin catalyst D5.

[0134] The structural parameters and composition of the modified resin catalyst D5 are listed in Table 1.

[0135] The performance test of the ketal reaction of the catalyst D5 and the recovered catalyst D5 was carried out according to the method of steps (2) to (4) in Example 1. The experimental results are listed in Table 2.

[0136] Comparative Example 6

[0137] Modified resin catalyst D6 was prepared in the same manner as in Example 1, except that in step (1), sodium sulfate was loaded instead of cerium sulfate. Specifically:

[0138] (1) Preparation of modified resin catalyst

[0139] In a round-bottom flask, mix 3.0 g of sodium sulfate and 250 g of 8% sulfuric acid aqueous solution, heat to 70°C in a water bath and stir for 4 h to obtain a colorless, transparent aqueous solution.

[0140] Add 20g of ion exchange resin model D009 to the above-mentioned transparent aqueous solution, heat to 80°C, and reflux with stirring for 4 hours. Cool the reaction system to room temperature and filter to obtain a solid product. Wash the solid product four times with 500ml of deionized water and dry it in air at 110°C for 6 hours to obtain modified resin catalyst D6.

[0141] Based on the total weight of the modified resin catalyst D6, the content of the ion exchange resin was 87 wt % and the content of the sodium sulfate was 13 wt %.

[0142] The ketal reaction performance of catalyst D6 and recovered catalyst D6 was tested according to the method of steps (2) to (4) in Example 1. The experimental results are listed in Table 2.

[0143] Comparative Example 7

[0144] Modified resin catalyst D7 was prepared in the same manner as in Example 1, except that in step (1), instead of using a strong acidic cation exchange resin, a high-density polyethylene resin with a grade of 7000F was used. Specifically:

[0145] (1) Preparation of modified resin catalyst

[0146] In a round-bottom flask, mix 3.0 g of anhydrous cerium sulfate and 250 g of 8% sulfuric acid aqueous solution, heat to 70°C in a water bath and stir for 4 h to obtain a yellow transparent aqueous solution;

[0147] 20 g of 7000F high-density polyethylene resin was added to the yellow transparent aqueous solution. The temperature was raised to 80°C and the mixture was stirred under reflux for 4 hours. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed four times with 500 ml of deionized water and dried in air at 110°C for 6 hours to obtain modified resin catalyst D7.

[0148] Based on the total weight of the modified resin catalyst D7, the content of the ion exchange resin was 87 wt %, and the content of the cerium sulfate was 13 wt %.

[0149] The ketal reaction performance of catalyst D7 and recovered catalyst D7 was tested according to the method of steps (2) to (4) in Example 1. The experimental results are listed in Table 2.

[0150] Table 1

[0151]

[0152] Table 2

[0153]

[0154]

[0155] From the above results, it can be seen that the modified resin catalyst provided by the present invention can catalyze the condensation reaction of acetone and ethylene glycol to produce 2,2-dimethyl-1,3-dioxolane, obtain a high yield of 2,2-dimethyl-1,3-dioxolane, and maintain good catalyst stability.

[0156] In Comparative Examples 1, 2, and 3, unmodified ion exchange resins were used as ketal catalysts. The yield of 2,2-dimethyl-1,3-dioxolane was low, and the catalyst stability was poor.

[0157] In Comparative Example 4, the content of the ion exchange resin in the modified resin catalyst was too high, and the content of the cerium sulfate modifying component on the catalyst was too low, resulting in a low yield of 2,2-dimethyl-1,3-dioxolane and poor catalyst stability.

[0158] In Comparative Example 5, the content of ion exchange resin in the modified resin catalyst is too low. Since the content of cerium sulfate as the modifying component on the catalyst is too high, it is unevenly dispersed on the carrier, resulting in a low yield of 2,2-dimethyl-1,3-dioxolane and poor catalyst stability.

[0159] In Comparative Example 6, sodium sulfate was used as the modifying component in the modified resin catalyst instead of cerium sulfate. Due to the poor modifying ability of sodium sulfate, the yield of 2,2-dimethyl-1,3-dioxolane was low and the catalyst stability was poor.

[0160] In Comparative Example 7, instead of using a strong-acid cation exchange resin as the modified resin catalyst, a high-density polyethylene resin (brand 7000F) was used. Because polyethylene resin lacks acidic centers, it cannot catalyze the ketal reaction, resulting in only a very small amount of 2,2-dimethyl-1,3-dioxolane being produced.

[0161] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including that each technical feature is combined in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A method for preparing 2,2-dimethyl-1,3-dioxolane, characterized in that: The preparation method comprises: contacting acetone and ethylene glycol in the presence of a modified resin catalyst and a water-carrying agent to carry out a condensation reaction, wherein the modified resin catalyst comprises a strong-acid cation exchange resin and cerium sulfate supported on the strong-acid cation exchange resin, and the strong-acid cation exchange resin is selected from one or more of an ion exchange resin with a model number of D009, an ion exchange resin with a model number of DA330, and an ion exchange resin with a model number of DA345; and based on the total weight of the modified resin catalyst, the content of the strong-acid cation exchange resin is 75-95% by weight, and the content of the cerium sulfate is 5-25% by weight.

2. The preparation method according to claim 1, wherein Based on the total weight of the modified resin catalyst, the content of the strong acid cation exchange resin is 80-92 weight %, and the content of the cerium sulfate is 8-20 weight %.

3. The preparation method according to claim 2, wherein The content of the strong acid cation exchange resin is 84-90% by weight, and the content of the cerium sulfate is 10-16% by weight.

4. The preparation method according to claim 1, wherein The strong acid cation exchange resin is an ion exchange resin with a strong acid sulfonic acid group -SO3H on a cross-linked polymer matrix; And / or, the specific surface area of ​​the strong acid cation exchange resin is 20-40m 2 / g, and the pore volume is 0.2-0.3mL / g.

5. The preparation method according to claim 1, wherein The specific surface area of ​​the modified resin catalyst is 16-25m 2 / g, and the pore volume is 0.14-0.20mL / g.

6. The preparation method according to claim 1, wherein The specific surface area of ​​the modified resin catalyst is 20-22m 2 / g, and the pore volume is 0.15-0.18mL / g.

7. The preparation method according to any one of claims 1 to 6, wherein The preparation method of the modified resin catalyst comprises: (1) Mixing cerium sulfate with an acidic aqueous solution to obtain a yellow transparent aqueous solution; (2) contacting the yellow transparent aqueous solution with a strong acidic cation exchange resin to react and obtain a mixture; (3) Filtering the mixture to obtain a solid product, and then washing and drying the solid product in sequence to obtain a modified resin catalyst.

8. The preparation method according to claim 7, wherein In step (1), the acidic aqueous solution is selected from one or more of sulfuric acid, nitric acid and hydrochloric acid; And / or, the mass concentration of the acidic aqueous solution is 0.2-30%; and / or, the weight ratio of the cerium sulfate to the acidic aqueous solution is 1:(10-300); And / or, the mixing conditions include: temperature of 40-100° C. and time of 0.5-12 h.

9. The preparation method according to claim 8, wherein The acidic aqueous solution is sulfuric acid.

10. The preparation method according to claim 7, wherein In step (2), the weight ratio of the cerium sulfate to the strong acid cation exchange resin is 1:(3-20); And / or, the reaction conditions include: temperature of 60-110° C., and time of 0.5-8 h.

11. The preparation method according to claim 10, wherein The weight ratio of the cerium sulfate to the strong acid cation exchange resin is 1:(5-10).

12. The preparation method according to claim 1, wherein The water-carrying agent is selected from cyclohexane and / or benzene; and / or, the weight ratio of the modified resin catalyst, the water-carrying agent, acetone and ethylene glycol is 1:(3-20):(5-30):(8-40); And / or, the condensation reaction conditions include: temperature of 60-100° C., and time of 0.5-10 h.

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