Supported cerium ammonium sulfate catalyst, its preparation method and application in methyl methacrylate synthesis reaction

Abstract

This invention relates to the field of fine chemicals, and discloses a supported cerium ammonium sulfate catalyst, its preparation method, and its application in the synthesis reaction of methyl methacrylate. The catalyst comprises a donut-shaped mesoporous material and cerium ammonium sulfate supported on the donut-shaped mesoporous material, wherein, based on the total weight of the catalyst, the content of the donut-shaped mesoporous material is 50-80% by weight, and the content of the cerium ammonium sulfate is 20-50% by weight. This catalyst, when used in the methacrylate esterification reaction, can achieve higher methacrylate conversion and methyl methacrylate selectivity.

Description

Technical Field

[0001] This invention relates to the field of fine chemicals, specifically to a supported cerium ammonium sulfate catalyst, its preparation method, and its application in the synthesis reaction of methyl methacrylate. Background Technology

[0002] As an important organic chemical product and raw material, the industrial production level and capacity of methyl methacrylate (MMA) have a significant impact on the development of my country's chemical industry. MMA is mainly used in industries such as PMMA (polymethyl methacrylate), coatings, textiles, adhesives, leather, papermaking, floor polishing, unsaturated resin modification, higher methacrylates, wood impregnators, printing and dyeing auxiliaries, and plasticizers. In recent years, the demand for MMA polymers, profiles, sheets, coatings, and emulsions has increased both domestically and internationally, and its application areas are constantly expanding, driving the rapid development of the MMA industry. Currently, domestic methyl methacrylate production technology is still in its initial stage. Developing methacrylate esterification catalysts and supporting processes with independent intellectual property rights is a development need facing my country's MMA production industry.

[0003] Esterification catalysts are a core technology in MMA production. For the esterification reaction of methacrylic acid and methanol, traditional production processes using inorganic acids such as sulfuric acid, phosphoric acid, and boric acid as catalysts are gradually being phased out. Using organic acids such as p-benzenesulfonic acid as catalysts also suffers from severe environmental pollution, low selectivity, and difficulty in product separation. Comparatively, esterification catalysts for heterogeneous reactions are currently a more active research area. Recent reports indicate that researchers are continuously exploring the use of acidic resins, organotin compounds, rare-earth solid superacids, and Lewis acids as catalysts in the synthesis of carboxylic acid esters, achieving significant experimental results. Currently, acidic cation exchange resins are widely used industrially for the production of methyl methacrylate. Cation exchange resins exhibit advantages such as good stability, high selectivity, low cost, and easy separation in esterification reactions. However, cation exchange resins themselves have poor heat resistance (generally decomposing at temperatures below 250℃), small specific surface area and pore volume, and are prone to swelling, resulting in poor reactivity and low ester yield as esterification catalysts. With the increasing demand for MMA, the synthesis of methyl methacrylate using green and environmentally friendly processes holds great promise.

[0004] Currently, supported esterification catalysts are receiving increasing attention in the synthesis of methyl methacrylate. For researchers, developing high-performance esterification catalysts to improve reaction efficiency and suppress byproduct formation is an important direction for future work. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of low methacrylic acid conversion and low methacrylic acid yield in the production of methyl methacrylate in the prior art, and to provide a supported cerium ammonium sulfate catalyst, its preparation method, and its application in the synthesis reaction of methyl methacrylate. This catalyst, when used in the esterification reaction of methacrylic acid, can achieve higher methacrylic acid conversion and methyl methacrylate selectivity.

[0006] To achieve the above objectives, a first aspect of the present invention provides a supported cerium ammonium sulfate catalyst, wherein the catalyst comprises a donut-shaped mesoporous material and cerium ammonium sulfate supported on the donut-shaped mesoporous material, and based on the total weight of the catalyst, the content of the donut-shaped mesoporous material is 50-80% by weight, and the content of the cerium ammonium sulfate is 20-50% by weight.

[0007] A second aspect of the present invention provides a method for preparing a supported cerium ammonium sulfate catalyst, wherein the preparation method includes:

[0008] (1) Mix cerium ammonium sulfate with the second acidic aqueous solution to obtain a yellow transparent aqueous solution;

[0009] (2) The yellow transparent aqueous solution is reacted with the donut-shaped mesoporous material to obtain a mixture;

[0010] (3) The mixture is filtered, washed and dried to obtain a supported cerium ammonium sulfate catalyst.

[0011] A third aspect of the present invention provides a supported cerium ammonium sulfate catalyst prepared by the preparation method described above.

[0012] The fourth aspect of this invention provides the application of the aforementioned supported cerium ammonium sulfate catalyst in the synthesis reaction of methyl methacrylate.

[0013] Compared with the prior art, the technical solution of the present invention has the following advantages through the above technical solution:

[0014] (1) The supported cerium ammonium sulfate catalyst provided by this invention has a stable structure and does not deform or swell during the reaction. When used to synthesize methyl methacrylate, it has a high conversion rate of methacrylic acid and a high selectivity for methyl methacrylate.

[0015] (2) The supported cerium ammonium sulfate catalyst provided by the present invention has readily available raw materials, a simple preparation method, easy-to-control conditions, and good product repeatability.

[0016] (3) The catalyst provided by the present invention has mild process conditions and low requirements for reaction equipment when used to synthesize methyl methacrylate.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0018] Figure 1 This is the XRD pattern of the donut-shaped mesoporous material A prepared in Example 1;

[0019] Figure 2 This is a TEM transmission electron microscope image of the donut-shaped mesoporous material A prepared in Example 1;

[0020] Figure 3 This is a scanning electron microscope (SEM) image of the donut-shaped mesoporous material A prepared in Example 1. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] As previously stated, the first aspect of the present invention provides a supported cerium ammonium sulfate catalyst, wherein the catalyst comprises a donut-shaped mesoporous material and cerium ammonium sulfate supported on the donut-shaped mesoporous material, and based on the total weight of the catalyst, the content of the donut-shaped mesoporous material is 50-80% by weight, and the content of the cerium ammonium sulfate is 20-50% by weight.

[0023] The inventors of this invention have discovered that, in the prior art, esterification catalysts used to produce methyl methacrylate are divided into two categories: homogeneous and heterogeneous. Homogeneous catalysts mainly include inorganic acid solutions and organic acids, while heterogeneous catalysts mainly include solid acids and cation exchange resins. Homogeneous catalysts are advantageous due to their low cost and good catalytic activity; however, they are gradually being phased out due to drawbacks such as difficulty in separating the product from the catalyst, numerous side reactions, and easy corrosion of equipment. Solid esterification catalysts, while solving the problems of difficult product separation and severe equipment corrosion, are rarely used in industrial production due to their poor catalytic activity, high reaction temperature, and low product selectivity. Compared to the above catalysts, using acidic cation exchange resins as esterification catalysts to produce methyl methacrylate is currently the main process used in industry. Resin catalysts have advantages such as high selectivity, low cost, and easy separation; however, the yield of methyl methacrylate is relatively low during the esterification reaction of methyl methacrylate, and their high-temperature resistance is also poor. Resins are organic polymer materials that easily swell in organic solvents and are easily deformed or even decomposed in high-temperature environments, which is the main reason for the poor temperature resistance of resin catalysts. Developing novel solid catalyst systems to compensate for the performance deficiencies of resin catalysts is a good way to solve the problem.

[0024] Lewis acid catalysts are highly valued for their high activity, good selectivity, and mild reaction conditions. However, common Lewis acids are unstable in water and easily deactivated by reaction with water. Furthermore, some Lewis acids are readily soluble in organic solvents, and the dissolution of Lewis acid catalysts in the reaction system during esterification reactions can cause difficulties in product separation. Cerium ammonium sulfate is an inexpensive and readily available inorganic crystalline compound, belonging to the Lewis acid salt class. It is not easily hydrolyzed and is also poorly soluble in organic solvents. Because the sulfate anion in cerium ammonium sulfate readily forms a stable ion pair with the carbocation, it can lower the activation energy of the esterification reaction, making cerium ammonium sulfate a high-performance esterification catalyst. However, directly using cerium ammonium sulfate crystals as a catalyst in the synthesis of methyl methacrylate may lead to a decrease in catalytic efficiency due to uneven dispersion of the active component. If a suitable support can be selected to effectively disperse cerium ammonium sulfate, the above problems can be solved, and the catalyst efficiency can be improved. To obtain a high-performance supported cerium ammonium sulfate catalyst, it is essential to first select a novel material with excellent structural characteristics as the catalyst support. Donut-shaped mesoporous materials possess long-range ordered pore structure, large specific surface area, large pore size, and large pore volume, which facilitates the diffusion of macromolecular reactants and products during reactions, and may serve as a good support for supported cerium ammonium sulfate catalysts.

[0025] The inventors of this invention discovered during the development of esterification catalysts that if cerium ammonium sulfate is supported on a donut-shaped mesoporous material, the resulting supported catalyst will not dissolve, swell, or deform in organic solvents. This catalyst exhibits excellent catalytic activity and methyl methacrylate selectivity in the esterification reaction of methacrylic acid and methanol.

[0026] According to the present invention, preferably, the content of the donut-shaped mesoporous material is 55-75% by weight and the content of the cerium ammonium sulfate is 25-45% by weight, based on the total weight of the catalyst; more preferably, the content of the donut-shaped mesoporous material is 59.8-69.6% by weight and the content of the cerium ammonium sulfate is 30.4-40.2% by weight, based on the total weight of the catalyst. In the present invention, by using the aforementioned specific content of the donut-shaped mesoporous material and the cerium ammonium sulfate, the prepared catalyst can exhibit better catalytic activity and ester selectivity when used in the methacrylate esterification reaction.

[0027] According to the present invention, the catalyst has a specific surface area of ​​300-800 m². 2 / g, pore volume 0.6-1.6cm³ 3 / g, with an average pore size of 4-9 nm; preferably, the catalyst has a specific surface area of ​​400-700 m². 2 / g, pore volume 0.7-1.3cm³ 3 / g, with an average pore size of 5-8 nm; more preferably, the catalyst has a specific surface area of ​​475-614 m². 2 / g, pore volume 0.9-1.2cm³ 3 / g, with an average pore size of 5.9-7.4 nm. In this invention, a supported cerium ammonium sulfate catalyst with the aforementioned specific parameters is used, which enables the catalyst to exhibit better catalytic activity and ester selectivity when used in the methacrylic acid esterification reaction.

[0028] According to the present invention, the specific surface area of ​​the donut-shaped mesoporous material is 500-900 m². 2 / g, pore volume 1.2-1.8cm³ 3 / g, with an average pore size of 6-10nm; preferably, the specific surface area of ​​the donut-shaped mesoporous material is 600-800m². 2 / g, pore volume 1.3-1.6cm³ 3 / g, with an average pore size of 7-9nm; more preferably, the specific surface area of ​​the donut-shaped mesoporous material is 698-735m². 2 / g, pore volume 1.4-1.5cm³ 3 / g, with an average pore size of 8.1-8.4 nm. In this invention, the use of a donut-shaped mesoporous material with the aforementioned specific parameters enables the prepared catalyst to exhibit better catalytic activity and ester selectivity when used in the methacrylic acid esterification reaction.

[0029] According to the present invention, the method for preparing the donut-shaped mesoporous material includes:

[0030] 1) Mix the template agent and N,N-dimethylformamide (DMF) with a first acidic aqueous solution, and after the template agent dissolves, contact it with tetraethyl orthosilicate to obtain a mixture;

[0031] 2) The mixture is subjected to crystallization, washing, filtration, drying and template removal to obtain a donut-shaped mesoporous material.

[0032] According to the present invention, the template agent can be any of the triblock copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene template agents conventionally used in the art, preferably P123.

[0033] According to the present invention, the first acidic aqueous solution is an inorganic acid aqueous solution, preferably a hydrochloric acid aqueous solution, wherein the hydrochloric acid aqueous solution is an aqueous solution of water and hydrogen chloride.

[0034] According to the present invention, the molar ratio of the template agent, N,N-dimethylformamide, tetraethyl orthosilicate, and hydrochloric acid (in molar amounts of HCl) is 1:(400-800):(20-100):(100-500), preferably 1:(500-700):(30-90):(200-400).

[0035] In this invention, the molar ratio of the template agent to hydrochloric acid (based on the molar ratio of water) is 1:(8000-20000), preferably 1:(10000-18000).

[0036] According to the present invention, the crystallization conditions include: a temperature of 25-60°C and a time of 10-40 hours; the crystallization process can be carried out under stirring conditions, wherein the stirring conditions include: a stirring rate of 200-900 rpm.

[0037] According to the present invention, the washing method is not specifically defined and can be any method well known to those skilled in the art. Preferably, the separated solid is mixed with deionized water, stirred and pulped for 2 hours, allowed to stand for 3 hours, and then separated. The above washing process is repeated 4-10 times.

[0038] According to the present invention, the preferred drying conditions are: drying temperature 70-150℃ and drying time 3-20 hours.

[0039] According to the present invention, the conditions for removing the template agent include: calcination treatment in air atmosphere, treatment temperature of 300-800℃, and treatment time of 4-50 hours; preferably, treatment temperature of 400-700℃ and treatment time of 10-30 hours.

[0040] A second aspect of the present invention provides a method for preparing a supported cerium ammonium sulfate catalyst, wherein the preparation method includes:

[0041] (1) Mix cerium ammonium sulfate with the second acidic aqueous solution to obtain a yellow transparent aqueous solution;

[0042] (2) The yellow transparent aqueous solution is reacted with the donut-shaped mesoporous material to obtain a mixture;

[0043] (3) The mixture is filtered, washed and dried to obtain a supported cerium ammonium sulfate catalyst.

[0044] According to the present invention, in step (1), the second acidic aqueous solution is sulfuric acid; the mass of the second acidic aqueous solution is 1-20%, preferably 2-15%.

[0045] According to the present invention, the weight ratio of the cerium ammonium sulfate to the second acidic aqueous solution is 1:(10-300), preferably 1:(20-100).

[0046] According to the present invention, the mixing conditions include: a temperature of 40-80°C, preferably 50-70°C; and a time of 1-16 hours, preferably 2-8 hours. Preferably, to achieve better mixing results, rapid stirring or ultrasonic means can be used to improve mixing efficiency during the mixing of cerium ammonium sulfate and the acidic aqueous solution.

[0047] According to the present invention, in step (2), the weight ratio of the cerium ammonium sulfate to the donut-shaped mesoporous material is 1:(1-15), preferably 1:(2-8).

[0048] According to the present invention, in step (2), the conditions for the contact reaction between the donut-shaped mesoporous material and the yellow transparent aqueous solution include: a temperature of 50-90°C, preferably 60-80°C; and a time of 0.5-12 h, preferably 2-8 h. Preferably, in order to achieve a better contact reaction effect, the mixture can be rapidly stirred during the contact reaction between the donut-shaped mesoporous material and the yellow transparent aqueous solution.

[0049] According to the present invention, there are no special requirements for the filtration in step (3), and it can be a filtration method known in the art, including gravity filtration, pressure filtration, vacuum filtration, or centrifugal filtration. Preferably, the filtration process specifically includes: using a vacuum flask to create a vacuum at the bottom of the funnel or using a centrifugal filter.

[0050] According to the present invention, in step (3), there are no special requirements for the method of washing the solid product. For example, deionized water can be used to wash the solid product, the volume ratio of deionized water to solid product can be 5-20, and the number of washing times can be 2-8.

[0051] According to the present invention, in step (3), the drying conditions include: the temperature can be 60-120℃, preferably 80-100℃; the time is 1-30h, preferably 3-20h.

[0052] A third aspect of the present invention provides a supported cerium ammonium sulfate catalyst prepared by the preparation method described above.

[0053] The fourth aspect of this invention provides the application of the aforementioned supported cerium ammonium sulfate catalyst in the synthesis reaction of methyl methacrylate.

[0054] According to the present invention, the method of applying the catalyst includes: simultaneously contacting methacrylic acid and methanol with a supported cerium ammonium sulfate catalyst.

[0055] In this invention, the contact conditions between the methacrylic acid and methanol and the catalyst include: a contact temperature of 40-150°C, preferably 60-120°C; a contact pressure of 0.01-5.0 MPa, preferably 0.1-3.0 MPa; and a mass hourly space velocity (HHSV) of methacrylic acid of 0.01-30 h⁻¹. -1 Preferably 0.1-10h -1 The mass hourly space velocity (MSV) of methanol is 0.01-50 h⁻¹. -1 Preferably 0.1-30h -1 .

[0056] The present invention will be described in detail below through embodiments.

[0057] In the following examples and comparative examples:

[0058] Small-angle XRD tests of the samples were performed on a BRUKER AXS D8 ADVANCE high-power rotating target X-ray diffractometer, with a scanning range of 0.5-10°.

[0059] The pore structure parameters of the samples were analyzed using an ASAP2020-M+C adsorption analyzer manufactured by Micromeritics, USA. Before measurement, the samples were degassed under vacuum at 40°C for 4 hours. The specific surface area of ​​the samples was calculated using the BET method, and the pore volume was calculated using the BJH model.

[0060] Scanning electron microscope (SEM) images of the samples were obtained using an XL-30 field emission environmental scanning electron microscope manufactured by FEI Corporation, USA; high-resolution transmission electron microscope (TEM) images of the samples were obtained using a Tecnai F20 high-resolution transmission electron microscope manufactured by FEI Philips, Netherlands; elemental analysis of the samples was performed using an Eagle III energy-dispersive X-ray fluorescence spectrometer manufactured by EDAX Corporation, USA.

[0061] The drying oven was manufactured by Shanghai Yiheng Scientific Instruments Co., Ltd., model DHG-9030A.

[0062] The muffle furnace is manufactured by CARBOLITE, model CWF1100.

[0063] The polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer (P123) used in the examples and comparative examples was purchased from Sigma-Aldrich Chemistry; other reagents used in the examples and comparative examples were purchased from Sinopharm Chemical Reagent Co., Ltd., and the reagent purity was analytical grade.

[0064] Example 1

[0065] (1) Preparation of donut-shaped mesoporous materials

[0066] 58 g of P123 (0.01 mol), 438 g of N,N-dimethylformamide (DMF) and 2450 g of hydrochloric acid aqueous solution (containing 3 mol of HCl) were mixed and stirred at 40 °C until P123 was completely dissolved. 125 g of tetraethyl orthosilicate (0.6 mol) was added to the above solution and stirred at 40 °C for 24 hours to crystallize. After crystallization, the solid was obtained by filtration. The solid was washed with deionized water 8 times and then dried at 120 °C for 10 hours to obtain mesoporous material powder. The mesoporous material powder was calcined at 500 °C for 20 hours to remove the template agent, resulting in donut-shaped mesoporous material A.

[0067] The specific surface area of ​​donut-shaped mesoporous material A is 735 m². 2 / g, pore volume is 1.5mL / g, and average pore size is 8.4nm.

[0068] Figure 1 This is the XRD pattern of donut-shaped mesoporous material A; from Figure 1 It is evident that a diffraction peak appears in the small-angle region of the XRD pattern, indicating that the donut-shaped mesoporous material A has a regular mesoporous phase structure.

[0069] Figure 2 This is a TEM transmission electron microscope image of donut-shaped mesoporous material A; from Figure 2 It can be seen that the donut-shaped mesoporous material A has the highly ordered pore distribution characteristic of mesoporous materials.

[0070] Figure 3 This is a scanning electron microscope (SEM) image of donut-shaped mesoporous material A; from Figure 3 It can be seen that the microstructure of the bagel-shaped mesoporous material A is all bagel-shaped, with the outer diameter of the bagel between 0.5 and 1 μm.

[0071] (2) Preparation of supported cerium ammonium sulfate catalyst

[0072] In a round-bottom flask, 7.0 g of cerium ammonium sulfate dihydrate and 300 g of a 10% sulfuric acid aqueous solution were mixed and heated in a water bath to 60°C with stirring for 4 h to obtain a yellow transparent aqueous solution. 10 g of the donut-shaped mesoporous material A prepared in step (1) was added to the above yellow transparent aqueous solution, and the temperature was raised to 70°C and refluxed with stirring for 5 h. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed four times with 100 mL of deionized water and dried in air at 90°C for 10 h to obtain the supported cerium ammonium sulfate catalyst A.

[0073] The specific surface area of ​​supported cerium ammonium sulfate catalyst A is 567 m². 2 / g, pore volume is 1.1mL / g, and average pore size is 6.7nm.

[0074] Based on the total weight of the supported cerium ammonium sulfate catalyst A, the content of donut-shaped mesoporous material A is 64.2% by weight, and the content of cerium ammonium sulfate is 35.8% by weight.

[0075] (3) Evaluation of catalyst reaction performance

[0076] The esterification performance of the catalyst was evaluated in a fixed-bed reactor. 5.0 g of supported cerium ammonium sulfate catalyst A was packed into a stainless steel fixed-bed reactor with an inner diameter of 8 mm. The reaction temperature was 100 °C, the reaction pressure was 0.3 MPa, and the weight hourly space velocity (WHSV) of methacrylic acid was 1.0 h⁻¹. -1 The weight hourly space velocity (WHSV) of methanol is 2.7 h⁻¹. -1 The reaction time was 20 hours. After cooling, the product was analyzed using an Agilent 7890A gas chromatograph equipped with an FFAP capillary column and a flame ionization detector (FID). Quantitative analysis was performed using a programmed temperature rise and correction factors. The conversion rate of methacrylic acid was 97.4%, and the selectivity for methyl methacrylate was 99.8%.

[0077] Example 2

[0078] (1) Preparation of donut-shaped mesoporous materials

[0079] 58 g of P123 (0.01 mol), 365 g of N,N-dimethylformamide (5 mol), and 1873 g of hydrochloric acid aqueous solution (containing 2 mol of HCl) were mixed and stirred at 25 °C until P123 was completely dissolved. 104 g of tetraethyl orthosilicate (0.5 mol) was added to the above solution, and the mixture was stirred at 25 °C for 40 hours to crystallize. After crystallization, the solid was obtained by filtration. The solid was washed with deionized water 8 times and then dried at 150 °C for 3 hours to obtain mesoporous material powder. The mesoporous material powder was calcined at 400 °C for 30 hours to remove the template agent, resulting in donut-shaped mesoporous material B.

[0080] The specific surface area of ​​donut-shaped mesoporous material B is 720 m². 2 / g, pore volume is 1.4mL / g, and average pore size is 8.1nm.

[0081] XRD pattern of donut-shaped mesoporous material B and Figure 1 Similarly, the TEM transmission electron microscopy image of donut-shaped mesoporous material B is similar to... Figure 2 Similarly, the SEM image of donut-shaped mesoporous material B is similar to... Figure 3 resemblance.

[0082] (2) Preparation of supported cerium ammonium sulfate catalyst

[0083] In a round-bottom flask, 5.5 g of cerium ammonium sulfate dihydrate and 150 g of a 12% sulfuric acid aqueous solution were mixed and heated in a water bath to 70°C and stirred for 2 h to obtain a yellow transparent aqueous solution. 10 g of the donut-shaped mesoporous material B prepared in step (1) was added to the above yellow transparent aqueous solution, and the temperature was raised to 80°C and refluxed with stirring for 3 h. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed 6 times with 100 mL of deionized water and dried in air at 100°C for 3 h to obtain the supported cerium ammonium sulfate catalyst B.

[0084] The specific surface area of ​​supported cerium ammonium sulfate catalyst B is 614 m². 2 / g, pore volume is 1.2mL / g, and average pore size is 7.4nm.

[0085] Based on the total weight of the supported cerium ammonium sulfate catalyst B, the content of donut-shaped mesoporous material B is 69.6% by weight, and the content of cerium ammonium sulfate is 30.4% by weight.

[0086] (3) Evaluation of catalyst reaction performance

[0087] The esterification reaction performance of catalyst B was tested according to step (3) in Example 1; the conversion rate of methacrylic acid was 97.1%, and the selectivity of methyl methacrylate was 99.7%.

[0088] Example 3

[0089] (1) Preparation of donut-shaped mesoporous materials

[0090] 58 g of P123 (0.01 mol), 511 g of N,N-dimethylformamide (7 mol), and 3386 g of hydrochloric acid aqueous solution (containing 4 mol of HCl) were mixed and stirred at 60 °C until P123 was completely dissolved. 146 g of tetraethyl orthosilicate (0.7 mol) was added to the above solution, and the mixture was stirred at 60 °C for 10 hours to crystallize. After crystallization, the solid was obtained by filtration. The solid was washed with deionized water 8 times and then dried at 70 °C for 20 hours to obtain mesoporous material powder. The mesoporous material powder was calcined at 600 °C for 25 hours to remove the template agent, yielding donut-shaped mesoporous material C.

[0091] The specific surface area of ​​donut-shaped mesoporous material C is 698 m². 2 / g, pore volume is 1.4mL / g, and average pore size is 8.2nm.

[0092] XRD pattern of donut-shaped mesoporous material C and Figure 1 Similarly, the TEM transmission electron microscopy image of the donut-shaped mesoporous material C is similar to... Figure 2 Similarly, the SEM image of the donut-shaped mesoporous material C is similar to... Figure 3 resemblance.

[0093] (2) Preparation of supported cerium ammonium sulfate catalyst

[0094] In a round-bottom flask, 8.7 g of cerium ammonium sulfate dihydrate and 400 g of 8% sulfuric acid aqueous solution were mixed and heated in a water bath to 50 °C with stirring for 8 h to obtain a yellow transparent aqueous solution. 10 g of the donut-shaped mesoporous material C prepared in step (1) was added to the above yellow transparent aqueous solution, and the temperature was raised to 60 °C and refluxed with stirring for 8 h. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed three times with 200 mL of deionized water and dried in air at 80 °C for 20 h to obtain the supported cerium ammonium sulfate catalyst C.

[0095] The specific surface area of ​​the supported cerium ammonium sulfate catalyst C is 475 m². 2 / g, pore volume is 0.9mL / g, and average pore size is 5.9nm.

[0096] Based on the total weight of the supported cerium ammonium sulfate catalyst C, the content of the donut-shaped mesoporous material C was 59.8% by weight, and the content of cerium ammonium sulfate was 40.2% by weight.

[0097] (3) Evaluation of catalyst reaction performance

[0098] The esterification reaction performance of catalyst C was tested according to step (3) in Example 1; the conversion rate of methacrylic acid was 97.0%, and the selectivity of methyl methacrylate was 99.6%.

[0099] Example 4

[0100] The supported cerium ammonium sulfate catalyst D was prepared using the same method as in Example 1, except that the preparation conditions of the catalyst in step (2) of Example 1 were changed. Specifically:

[0101] In a round-bottom flask, 4.2 g of cerium ammonium sulfate dihydrate and 230 g of a 10% sulfuric acid aqueous solution were mixed and heated in a water bath to 60°C with stirring for 4 h to obtain a yellow transparent aqueous solution. 10 g of donut-shaped mesoporous material A was added to the above yellow transparent aqueous solution, and the mixture was heated to 70°C and refluxed with stirring for 5 h. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed four times with 100 mL of deionized water and dried in air at 90°C for 10 h to obtain the supported cerium ammonium sulfate catalyst D.

[0102] The specific surface area of ​​the supported cerium ammonium sulfate catalyst D is 631 m². 2 / g, pore volume is 1.2mL / g, and average pore size is 7.5nm.

[0103] Based on the total weight of the supported cerium ammonium sulfate catalyst D, the content of donut-shaped mesoporous material A is 75% by weight, and the content of cerium ammonium sulfate is 25% by weight.

[0104] The catalytic performance of catalyst D was tested according to the esterification reaction performance evaluation method in step (3) of Example 1; the conversion rate of methacrylic acid was 95.6%, and the selectivity of methyl methacrylate was 98.9%.

[0105] Example 5

[0106] The supported cerium ammonium sulfate catalyst was prepared using the same method as in Example 3, except that the catalyst preparation conditions in step (2) of Example 3 were changed. Specifically:

[0107] In a round-bottom flask, 11.0 g of cerium ammonium sulfate dihydrate and 270 g of a 15% sulfuric acid aqueous solution were mixed and heated in a water bath to 50 °C with stirring for 8 h to obtain a yellow transparent aqueous solution. 10 g of donut-shaped mesoporous material C was added to the above yellow transparent aqueous solution, and the mixture was heated to 60 °C and refluxed with stirring for 8 h. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed three times with 200 mL of deionized water and dried in air at 80 °C for 20 h to obtain the supported cerium ammonium sulfate catalyst E.

[0108] The specific surface area of ​​the supported cerium ammonium sulfate catalyst E is 427 m².2 / g, pore volume is 0.7mL / g, and average pore size is 5.0nm.

[0109] Based on the total weight of the supported cerium ammonium sulfate catalyst E, the content of the donut-shaped mesoporous material C is 55% by weight, and the content of cerium ammonium sulfate is 45% by weight.

[0110] The catalytic performance of catalyst E was tested according to the esterification reaction performance evaluation method in step (3) of Example 1; the conversion rate of methacrylic acid was 95.9%, and the selectivity of methyl methacrylate was 99.1%.

[0111] Example 6

[0112] The supported cerium ammonium sulfate catalyst F was prepared using the same method as in Example 1, except that the preparation conditions of the catalyst in step (2) of Example 1 were changed. Specifically:

[0113] In a round-bottom flask, 3.2 g of cerium ammonium sulfate dihydrate and 180 g of a 10% sulfuric acid aqueous solution were mixed and heated in a water bath to 60 °C with stirring for 4 h to obtain a yellow transparent aqueous solution. 10 g of donut-shaped mesoporous material A was added to the above yellow transparent aqueous solution, and the mixture was heated to 70 °C and refluxed with stirring for 5 h. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed four times with 100 mL of deionized water and dried in air at 90 °C for 10 h to obtain the supported cerium ammonium sulfate catalyst F.

[0114] The specific surface area of ​​the supported cerium ammonium sulfate catalyst F is 689 m². 2 / g, pore volume is 1.3mL / g, and average pore size is 7.8nm.

[0115] Based on the total weight of the supported cerium ammonium sulfate catalyst F, the content of donut-shaped mesoporous material A is 80% by weight, and the content of cerium ammonium sulfate is 20% by weight.

[0116] The catalytic performance of catalyst F was tested according to the esterification reaction performance evaluation method in step (3) of Example 1; the conversion rate of methacrylic acid was 94.3%, and the selectivity of methyl methacrylate was 98.4%.

[0117] Example 7

[0118] The supported cerium ammonium sulfate catalyst G was prepared using the same method as in Example 3, except that the preparation conditions of the catalyst in step (2) of Example 3 were changed. Specifically:

[0119] In a round-bottom flask, 13.3 g of cerium ammonium sulfate dihydrate and 330 g of a 15% sulfuric acid aqueous solution were mixed and heated in a water bath to 50 °C with stirring for 8 h to obtain a yellow transparent aqueous solution. 10 g of donut-shaped mesoporous material C was added to the above yellow transparent aqueous solution, and the mixture was heated to 60 °C and refluxed with stirring for 8 h. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed three times with 200 mL of deionized water and dried in air at 80 °C for 20 h to obtain the supported cerium ammonium sulfate catalyst G.

[0120] The specific surface area of ​​the supported cerium ammonium sulfate catalyst G is 384 m². 2 / g, pore volume is 0.6mL / g, and average pore size is 4.6nm.

[0121] Based on the total weight of the supported cerium ammonium sulfate catalyst G, the content of the donut-shaped mesoporous material C is 50% by weight, and the content of cerium ammonium sulfate is 50% by weight.

[0122] The catalytic performance of catalyst G was tested according to the esterification reaction performance evaluation method in step (3) of Example 1; the conversion rate of methacrylic acid was 94.1%, and the selectivity of methyl methacrylate was 98.3%.

[0123] Comparative Example 1

[0124] The supported cerium ammonium sulfate catalyst D1 was prepared using the same method as in Example 1, except that the preparation conditions of the catalyst in step (2) of Example 1 were changed. Specifically:

[0125] In a round-bottom flask, 1.1 g of cerium ammonium sulfate dihydrate and 350 g of a 3% sulfuric acid aqueous solution were mixed and heated in a water bath to 60°C with stirring for 4 h to obtain a yellow transparent aqueous solution. 10 g of donut-shaped mesoporous material A was added to the above yellow transparent aqueous solution, and the mixture was heated to 70°C and refluxed with stirring for 5 h. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed four times with 100 mL of deionized water and dried in air at 90°C for 10 h to obtain the supported cerium ammonium sulfate catalyst D1.

[0126] The specific surface area of ​​the supported cerium ammonium sulfate catalyst D1 is 704 m². 2 / g, pore volume is 1.4mL / g, and average pore size is 8.0nm.

[0127] Based on the total weight of the supported cerium ammonium sulfate catalyst D1, the content of donut-shaped mesoporous material A is 92% by weight, and the content of cerium ammonium sulfate is 8% by weight.

[0128] The catalytic performance of catalyst D1 was tested according to the esterification reaction performance evaluation method in step (3) of Example 1; the conversion rate of methacrylic acid was 83.5%, and the selectivity of methyl methacrylate was 95.7%.

[0129] Comparative Example 2

[0130] The supported cerium ammonium sulfate catalyst D2 was prepared using the same method as in Example 3, except that the preparation conditions of the catalyst in step (2) of Example 3 were changed. Specifically:

[0131] In a round-bottom flask, 21.7 g of cerium ammonium sulfate dihydrate and 180 g of 18% sulfuric acid aqueous solution were mixed and heated in a water bath to 50 °C with stirring for 8 h to obtain a yellow transparent aqueous solution. 10 g of donut-shaped mesoporous material C was added to the above yellow transparent aqueous solution, and the mixture was heated to 60 °C and refluxed with stirring for 8 h. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed three times with 200 mL of deionized water and dried in air at 80 °C for 20 h to obtain the supported cerium ammonium sulfate catalyst D2.

[0132] The specific surface area of ​​the supported cerium ammonium sulfate catalyst D2 is 294 m². 2 / g, pore volume is 0.4mL / g, and average pore size is 3.7nm.

[0133] Based on the total weight of the supported cerium ammonium sulfate catalyst D2, the content of donut-shaped mesoporous material C is 38% by weight, and the content of cerium ammonium sulfate is 62% by weight.

[0134] The catalytic performance of catalyst D2 was tested according to the esterification reaction performance evaluation method in step (3) of Example 1; the conversion rate of methacrylic acid was 83.7%, and the selectivity of methyl methacrylate was 95.0%.

[0135] Comparative Example 3

[0136] In Example 1, step (1) is cancelled, and the donut-shaped mesoporous material A in step (2) of Example 1 is replaced with commercially available silica (purchased from Qingdao Hailang Silica Gel Desiccant Factory, specific surface area 329 m²). 2 / g, pore volume 0.6cm³ 3 / g), to obtain catalyst D3.

[0137] Based on the total weight of catalyst D3, the content of commercially available silica is 64.2% by weight and the content of cerium ammonium sulfate is 35.8% by weight.

[0138] The catalytic performance of catalyst D3 was tested according to the esterification reaction performance evaluation method in step (3) of Example 1. The conversion rate of methacrylic acid was 87.8%, and the selectivity of methyl methacrylate was 94.7%.

[0139] Comparative Example 4

[0140] Catalyst D4 was prepared using the same method as in Example 1, except that steps (1) and (2) in Example 1 were omitted, and a commercially available resin material was used for the synthesis reaction of methyl methacrylate; wherein the resin catalyst was purchased from Kerry Environmental Technology Co., Ltd., model D009 (specific surface area 31 m²). 2 / g, pore volume is 0.24cm³ 3 / g, most probable pore size 210nm).

[0141] The catalytic performance of catalyst D4 was tested according to the esterification reaction performance evaluation method in step (3) of Example 1; the conversion rate of methacrylic acid was 90.2%, and the selectivity of methyl methacrylate was 96.9%.

[0142] Comparative Example 5

[0143] Catalyst D5 was prepared in the same manner as in Example 1, except that in step (2), sodium sulfate was loaded instead of cerium ammonium sulfate.

[0144] Based on the total weight of catalyst D5, the content of donut-shaped mesoporous material A is 64.2% by weight, and the content of sodium sulfate is 35.8% by weight.

[0145] The catalytic performance of catalyst D5 was tested according to the esterification reaction performance evaluation method in step (3) of Example 1; the conversion rate of methacrylic acid was 62.8%, and the selectivity of methyl methacrylate was 82.0%.

[0146] Comparative Example 6

[0147] Catalyst D6 was prepared using the same method as in Example 1, except that the prepared support, "donut-shaped mesoporous material," was replaced with "ZSM-5 zeolite molecular sieve (purchased from Tianjin Nanhua Catalyst Co., Ltd., with a specific surface area of ​​341 m²)." 2 / g, pore volume 0.35cm³ 3 The catalyst D6 has a surface area of ​​218 m² / g and an average pore size of 0.55 nm. 2 / g, pore volume is 0.27cm³ 3 / g, with an average pore size of 0.48nm.

[0148] Based on the total weight of catalyst D6, the content of ZSM-5 zeolite molecular sieve is 64.2% by weight, and the content of cerium ammonium sulfate is 35.8% by weight.

[0149] The catalytic performance of catalyst D6 was tested according to the esterification reaction performance evaluation method in step (3) of Example 1; the conversion rate of methacrylic acid was 83.1%, and the selectivity of methyl methacrylate was 94.2%.

[0150] The results above show that the supported cerium ammonium sulfate catalyst provided by the present invention can directly convert methacrylic acid and methanol into methyl methacrylate, resulting in a high conversion rate of methacrylic acid and a high selectivity for methyl methacrylate.

[0151] In Comparative Example 1, the content of donut-shaped mesoporous material in the supported cerium ammonium sulfate catalyst was too high. Due to the low content of cerium ammonium sulfate, an active component on the catalyst, there were insufficient active sites during the reaction, resulting in low conversion of methacrylic acid and low selectivity of methyl methacrylate.

[0152] In Comparative Example 2, the content of donut-shaped mesoporous material in the supported ceric ammonium sulfate catalyst was too low, while the content of ceric ammonium sulfate was too high. Due to the uneven dispersion of the active component ceric ammonium sulfate on the support and the low utilization efficiency of active sites during the reaction, the conversion rate of methacrylic acid was low, and the selectivity of methyl methacrylate was low.

[0153] In Comparative Example 3, the donut-shaped mesoporous material specifically defined in this invention was not used; instead, commercially available silica was used. Due to the irregular pore structure of commercially available silica and the uneven dispersion of the active components on the carrier surface, the conversion rate of methacrylic acid was low, and the selectivity of methyl methacrylate was low.

[0154] In Comparative Example 4, the supported cerium ammonium sulfate catalyst provided by this invention was not used; instead, a commercially available resin material was used for the synthesis reaction of methyl methacrylate. The methacrylic acid conversion and methyl methacrylate selectivity of the resin catalyst were both lower than those of the supported cerium ammonium sulfate catalyst provided by this invention.

[0155] In Comparative Example 5, sodium sulfate was used instead of cerium ammonium sulfate as the active component in the supported cerium ammonium sulfate catalyst. Due to the poor esterification catalytic performance of sodium sulfate, the conversion rate of methacrylic acid was low, and the selectivity of methyl methacrylate was also low.

[0156] In Comparative Example 6, the donut-shaped mesoporous material specifically defined in this invention was not used. Instead, ZSM-5 zeolite molecular sieve was used. Due to the narrow pores of ZSM-5 zeolite molecular sieve (average pore size of only 0.55 nm), the active components were not evenly dispersed on the carrier surface, and the pores were easily blocked, resulting in low conversion of methacrylic acid and low selectivity of methyl methacrylate.

[0157] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. The application of a supported cerium ammonium sulfate catalyst in the synthesis reaction of methyl methacrylate, the application comprising: The method involves simultaneously contacting methacrylic acid and methanol with a supported ceric ammonium sulfate catalyst, characterized in that the supported ceric ammonium sulfate catalyst comprises a donut-shaped mesoporous material and ceric ammonium sulfate supported on the donut-shaped mesoporous material, wherein the specific surface area of ​​the donut-shaped mesoporous material is 698-735 m². 2 / g, pore volume 1.4-1.5cm³ 3 The catalyst has an average pore size of 8.1-8.4 nm, and based on the total weight of the supported cerium ammonium sulfate catalyst, the content of the donut-shaped mesoporous material is 50-80% by weight, and the content of the cerium ammonium sulfate is 20-50% by weight; the specific surface area of ​​the supported cerium ammonium sulfate catalyst is 475-614 m² / g. 2 / g, pore volume 0.9-1.2cm³ 3 / g, with an average pore size of 5.9-7.4nm.

2. The application according to claim 1, wherein, Based on the total weight of the supported cerium ammonium sulfate catalyst, the content of the donut-shaped mesoporous material is 55-75% by weight, and the content of the cerium ammonium sulfate is 25-45% by weight.

3. The application according to claim 2, wherein, Based on the total weight of the supported cerium ammonium sulfate catalyst, the content of the donut-shaped mesoporous material is 59.8-69.6% by weight, and the content of the cerium ammonium sulfate is 30.4-40.2% by weight.

4. The application according to any one of claims 1-3, wherein, The method for preparing the donut-shaped mesoporous material includes: 1) Mix the template agent and N,N-dimethylformamide with a first acidic aqueous solution, and after the template agent dissolves, contact it with tetraethyl orthosilicate to obtain a mixture; 2) The mixture is subjected to crystallization, washing, filtration, drying and template removal to obtain a donut-shaped mesoporous material.

5. The application according to claim 4, wherein, The template agent is a polyoxyethylene-polyoxypropylene-polyoxyethylene template agent; And / or, the first acidic aqueous solution is an inorganic acid aqueous solution; And / or, the crystallization conditions include: a temperature of 25-60°C and a time of 10-40 hours; And / or, the conditions for removing the template agent include: calcination treatment in air atmosphere at a temperature of 300-800°C for 4-50 hours.

6. The application according to claim 5, wherein, The first acidic aqueous solution is a hydrochloric acid aqueous solution.

7. The application according to claim 6, wherein, The molar ratio of the template agent, N,N-dimethylformamide, tetraethyl orthosilicate, and hydrochloric acid (based on the number of moles of HCl) is 1:(400-800):(20-100):(100-500).

8. The application according to claim 7, wherein, The molar ratio of the template agent, N,N-dimethylformamide, tetraethyl orthosilicate, and hydrochloric acid (based on the number of moles of HCl) is 1:(500-700):(30-90):(200-400).

9. The application according to any one of claims 1-3, wherein, The preparation method of the supported cerium ammonium sulfate catalyst includes: (1) Mix cerium ammonium sulfate with the second acidic aqueous solution to obtain a yellow transparent aqueous solution; (2) The yellow transparent aqueous solution is reacted with the donut-shaped mesoporous material to obtain a mixture; (3) The mixture is filtered, washed and dried to obtain a supported cerium ammonium sulfate catalyst.

10. The application according to claim 9, wherein, In step (1), the second acidic aqueous solution is sulfuric acid; And / or, the mass of the second acidic aqueous solution is 1-20%; And / or, the weight ratio of the cerium ammonium sulfate to the second acidic aqueous solution is 1:(10-300); And / or, the mixing conditions include: a temperature of 40-80°C and a time of 1-16 hours.

11. The application according to claim 9, wherein, In step (2), the weight ratio of the cerium ammonium sulfate to the donut-shaped mesoporous material is 1:(1-15); And / or, the reaction conditions include: a temperature of 50-90°C and a time of 0.5-12 h.

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