Modified resin catalysts, their preparation methods, and their application in the synthesis of methyl methacrylate.

Abstract

This invention relates to the field of fine chemical technology, and discloses a modified resin catalyst, its preparation method, and its application in the synthesis reaction of methyl methacrylate. The modified resin catalyst comprises a strong acid cation exchange resin and lanthanum sulfate; and based on the total weight of the modified resin catalyst, the content of the strong acid cation exchange resin is 75-97% by weight, and the content of the lanthanum sulfate is 3-25% by weight. This modified resin catalyst, when used in the methacrylate esterification reaction, can achieve higher methacrylic acid conversion and methyl methacrylate selectivity.

Description

Technical Field

[0001] This invention relates to the field of fine chemical technology, specifically to a modified resin 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 impregnating agents, 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 new methacrylate esterification catalysts and supporting processes is a development need facing the MMA production industry.

[0003] Esterification catalysts are a core technology in MMA production. Concentrated sulfuric acid is the traditional catalyst used for the esterification reaction of methacrylic acid and methanol. While this catalyst is highly active and inexpensive, the strong oxidizing and dehydrating properties of concentrated sulfuric acid, as well as its solubility in the reaction system, cause problems for equipment corrosion and subsequent treatment. Therefore, seeking catalysts that combine strong catalytic activity, high selectivity, and ease of separation from the reaction system remains of significant importance. Esterification catalysts for heterogeneous reactions are currently a relatively active research area. Currently, catalysts that can replace concentrated sulfuric acid include strong acid ion exchange resins, heteropoly acids, ionic liquids, and solid superacids, achieving good results. Among these, strong acid ion exchange resins have attracted widespread attention due to their insolubility in the reaction system, good stability, high selectivity, low cost, and ease of separation. Strong acid ion exchange resins are polymeric materials containing acidic functional active components, exhibiting strong catalytic capabilities for esterification, aldehyde-ketone condensation, and etherification. However, the acid strength of strong acid ion exchange resins is weaker than that of sulfuric acid, and when used alone as an esterification catalyst, the reaction rate is slower than that of concentrated sulfuric acid. Therefore, it is necessary to modify it to improve its catalytic activity.

[0004] With the increasing demand for MMA, the synthesis of methyl methacrylate (MMA) using green and environmentally friendly processes holds great promise. Currently, heterogeneous esterification catalysts are receiving increasing attention in the synthesis of MMA. 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, low methyl methacrylate yield, and poor catalyst stability in current methyl methacrylate production processes. This invention provides a modified resin catalyst, its preparation method, and its application in the synthesis of methyl methacrylate. This modified resin catalyst, 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 modified resin catalyst, wherein the modified resin catalyst comprises a strong acid cation exchange resin and lanthanum sulfate; and based on the total weight of the modified resin catalyst, the content of the strong acid cation exchange resin is 75-97% by weight, and the content of the lanthanum sulfate is 3-25% by weight.

[0007] A second aspect of the present invention provides a method for preparing a modified resin catalyst, wherein the preparation method includes:

[0008] (1) Lanthanum sulfate is mixed with an acidic aqueous solution to obtain a solution;

[0009] (2) The solution is reacted with a strong acid cation exchange resin to obtain a mixture;

[0010] (3) The mixture is filtered to obtain a solid product, and the solid product is then washed and dried in sequence to obtain a modified resin catalyst.

[0011] A third aspect of the present invention provides a modified resin catalyst prepared by the preparation method described above.

[0012] A fourth aspect of the present invention provides the application of the aforementioned modified resin 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 modified resin catalyst provided by the present invention uses strong acid cation exchange resin as raw material, and can be directly applied in industry without further molding.

[0015] (2) The modified resin catalyst provided by the present invention has readily available raw materials, a simple preparation process, easy-to-control conditions, good product repeatability, and is suitable for large-scale production.

[0016] (3) The catalyst provided by this invention provides a mild process for the synthesis of methyl methacrylate, with low requirements for the reaction equipment. It also results in high conversion of methacrylic acid and high selectivity for methyl methacrylate.

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

[0018] 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.

[0019] As previously stated, 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 lanthanum sulfate; and based on the total weight of the modified resin catalyst, the content of the strong acid cation exchange resin is 75-97% by weight, and the content of the lanthanum sulfate is 3-25% by weight.

[0020] 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 catalysts and heterogeneous catalysts. 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 strong acid-type cation exchange resins as esterification catalysts to produce methyl methacrylate is currently the main process used in industrial applications. Resin catalysts have 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 an esterification catalyst, the reaction rate is slower than that of concentrated sulfuric acid. Furthermore, the active groups of strong acid-type cation exchange resins are mainly sulfonic acid groups; and in ion exchange resins, the bond between sulfonic acid groups and polymers is not very strong. During the esterification reaction, the sulfonic acid groups at the active center are easily detached and dissolved in the reaction system, resulting in poor catalyst stability. Therefore, it is necessary to modify the strong acid cation exchange resin to improve its esterification catalytic activity.

[0021] The inventors of this invention discovered during the development of esterification catalysts that modifying strong acid cation exchange resins with lanthanum sulfate yields high-performance esterification catalysts. On one hand, after modification with lanthanum sulfate, the rare earth metal ions interact with the functional sulfonic acid groups of the ion exchange resin to form new strong acid centers, significantly increasing the number of acidic centers on the catalyst and thus improving catalytic performance. On the other hand, lanthanum sulfate is not easily soluble in the esterification reaction system of methacrylic acid and methanol, avoiding the problem of active centers detaching and dissolving, thereby improving catalyst stability. For these reasons, the modified resin catalyst exhibits excellent catalytic activity, methyl methacrylate selectivity, and stability when used in the esterification reaction of methacrylic acid.

[0022] In industrial production, solid-phase esterification catalysts require molding before application. Modified resin catalysts, however, have the same morphology as strong acid cation exchange resins and do not require further molding, allowing them to be used directly as industrial catalysts.

[0023] According to the present invention, preferably, based on the total weight of the modified resin catalyst, the content of the strong acid cation exchange resin is 80-96% by weight, and the content of the lanthanum sulfate is 4-20% by weight; more preferably, the content of the strong acid cation exchange resin is 85-95% by weight, and the content of the lanthanum sulfate is 5-15% by weight. In the present invention, by using the aforementioned specific content of the strong acid cation exchange resin and the lanthanum sulfate, the prepared catalyst can exhibit better catalytic activity, ester selectivity, and catalyst stability when used in the methacrylic acid esterification reaction.

[0024] According to the present invention, the specific surface area of ​​the modified resin catalyst is 15-23 m². 2 / g, with a pore volume of 0.1-0.2 mL / g; preferably, the modified resin catalyst has a specific surface area of ​​19-21 m² / g. 2 / g, with a pore volume of 0.13-0.15mL / g.

[0025] According to the present invention, the strong acid cation exchange resin is an ion exchange resin with strong acid sulfonic acid groups (-SO3H) on a cross-linked polymer matrix. The structure of the strong acid cation exchange resin can be represented by R-SO3H (where R represents the polymer matrix). The relative density is between 0.5 and 1.0.

[0026] According to the present invention, the strong acid type cation exchange resin is obtained commercially, specifically ion exchange resins of model D008 and D006 purchased from Kerry Environmental Protection Technology Co., Ltd., and ion exchange resin of model DB757 purchased from Dandong Mingzhu Special Resin Co., Ltd.

[0027] A second aspect of the present invention provides a method for preparing a modified resin catalyst, wherein the preparation method includes:

[0028] (1) Lanthanum sulfate is mixed with an acidic aqueous solution to obtain a solution;

[0029] (2) The solution is reacted with a strong acid cation exchange resin to obtain a mixture;

[0030] (3) The mixture is filtered to obtain a solid product, and the solid product is then washed and dried in sequence to obtain a modified resin catalyst.

[0031] According to the present invention, lanthanum sulfate is mixed with an acidic aqueous solution to obtain a transparent and clear solution.

[0032] 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.

[0033] According to the present invention, in step (1), the mass concentration of the acidic aqueous solution is 0.2-30%, preferably 0.5-20%.

[0034] According to the present invention, in step (1), the weight ratio of the lanthanum sulfate to the acidic aqueous solution is 1:(10-300), preferably 1:(20-200).

[0035] According to the present invention, in step (1), the mixing conditions of the lanthanum sulfate and the acidic aqueous solution include: a temperature of 40-100°C and a time of 0.5-12 h. Alternatively, the mixing conditions may include: a temperature of 40-100°C, preferably 60-90°C; and a time of 0.5-12 h, preferably 2-8 h. Preferably, to achieve a better mixing effect, rapid stirring or ultrasonic means can be used to improve the mixing efficiency during the mixing of the lanthanum sulfate and the acidic aqueous solution.

[0036] According to the present invention, the weight ratio of the lanthanum sulfate to the strong acid cation exchange resin is 1:(3-30), preferably 1:(5-20).

[0037] According to the present invention, in step (2), the conditions for the strong acid cation exchange resin to react with the solution include: a temperature of 60-110°C, preferably 70-100°C; and a time of 0.5-8 hours, preferably 1-6 hours. Preferably, to achieve a better reaction effect, rapid stirring can be performed during the reaction of the strong acid cation exchange resin with the solution to improve the reaction efficiency.

[0038] 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.

[0039] According to the present invention, in step (3), the method for washing the solid product is not particularly required. 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 washes can be 2-8. Preferably, in order to achieve a better washing effect, the mixture of deionized water and solid product can be stirred rapidly during the mixing process.

[0040] According to the present invention, in step (3), the drying conditions include: the temperature can be 60-180℃, preferably 80-150℃; the time can be 1-30h, preferably 3-20h.

[0041] A third aspect of the present invention provides a modified resin catalyst prepared by the preparation method described above.

[0042] A fourth aspect of the present invention provides the application of the aforementioned modified resin catalyst in the synthesis reaction of methyl methacrylate.

[0043] According to the present invention, the application includes reacting methacrylic acid and methanol simultaneously with a modified resin catalyst.

[0044] 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 can range from 0.01 to 50 h⁻¹. -1 Preferably 0.1-30h -1 .

[0045] The present invention will be described in detail below through embodiments.

[0046] In the following examples and comparative examples:

[0047] 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.

[0048] Elemental analysis of the samples was performed on an Eagle III energy-dispersive X-ray fluorescence spectrometer manufactured by EDAX Corporation in the United States.

[0049] The rotary evaporator was manufactured by IKA GmbH in Germany, and its model number is RV10 digital.

[0050] The drying oven was manufactured by Shanghai Yiheng Scientific Instruments Co., Ltd., model DHG-9030A.

[0051] Ion exchange resins of type D008 and D006 were purchased from Kerry Environmental Protection Technology Co., Ltd.; ion exchange resin of type DB757 was purchased from Dandong Mingzhu Special Resin Co., Ltd.; reagents used in the examples and comparative examples were all purchased from Sinopharm Chemical Reagent Co., Ltd., and the reagent purity was analytical grade.

[0052] Example 1

[0053] (1) Preparation of modified resin catalyst

[0054] In a round-bottom flask, 2.5 g of lanthanum sulfate and 300 g of a 5% sulfuric acid aqueous solution were mixed and heated in a water bath to 70°C with stirring for 4 hours to obtain a clear, transparent aqueous solution. 20 g of ion exchange resin (model D008) was added to the above clear, transparent aqueous solution, and the mixture was heated to 80°C and refluxed with stirring 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 A.

[0055] The structural parameters and composition of modified resin catalyst A are listed in Table 1.

[0056] (2) Evaluation of catalyst reaction performance

[0057] The performance of the catalyst in the methacrylilation reaction was evaluated in a fixed-bed reactor. 5.0 g of modified resin 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 3.0 h⁻¹. -1 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 programmed temperature ramping and correction factors. The conversion of methacrylic acid and the selectivity of methyl methacrylate are listed in Table 2.

[0058] Example 2

[0059] (1) Preparation of modified resin catalyst

[0060] In a round-bottom flask, 1.1 g of lanthanum sulfate and 200 g of a 2% sulfuric acid aqueous solution were mixed and heated in a water bath to 90°C with stirring for 2 hours to obtain a clear, transparent aqueous solution. 20 g of ion exchange resin (model D006) was added to the above clear, transparent aqueous solution, and the mixture was heated to 100°C and refluxed with stirring for 1 hour. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed three times with 500 ml of deionized water and dried in air at 150°C for 3 hours to obtain modified resin catalyst B.

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

[0062] (2) Evaluation of catalyst reaction performance

[0063] The esterification performance of catalyst B was tested according to step (2) in Example 1. The experimental results are listed in Table 2.

[0064] Example 3

[0065] (1) Preparation of modified resin catalyst

[0066] In a round-bottom flask, 3.6 g of lanthanum sulfate and 200 g of a 15% sulfuric acid aqueous solution were mixed and heated in a water bath to 60°C with stirring for 8 hours to obtain a clear, transparent aqueous solution. 20 g of DB757 ion exchange resin was added to the above clear, transparent aqueous solution, and the mixture was heated to 70°C and refluxed with stirring 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 400 ml of deionized water and dried in air at 80°C for 20 hours to obtain modified resin catalyst C.

[0067] The structural parameters and composition of the modified resin catalyst C are listed in Table 1.

[0068] (2) Evaluation of catalyst reaction performance

[0069] The esterification performance of catalyst C was tested according to step (2) in Example 1. The experimental results are listed in Table 2.

[0070] Example 4

[0071] Modified resin catalyst D was prepared using the same method as in Example 1, except that the preparation conditions of the catalyst in step (1) of Example 1 were changed. Specifically:

[0072] (1) Preparation of modified resin catalyst

[0073] In a round-bottom flask, 0.9 g of lanthanum sulfate and 150 g of a 4% sulfuric acid aqueous solution were mixed and heated in a water bath to 70°C with stirring for 4 hours to obtain a clear, transparent aqueous solution. 20 g of ion exchange resin (model D008) was added to the above clear, transparent aqueous solution, and the mixture was heated to 80°C and refluxed with stirring 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 D.

[0074] The structural parameters and composition of the modified resin catalyst D are listed in Table 1.

[0075] (2) Evaluation of catalyst reaction performance

[0076] The esterification performance of catalyst D was tested according to step (2) in Example 1. The experimental results are listed in Table 2.

[0077] Example 5

[0078] The modified resin catalyst E was prepared using the same method as in Example 3, except that the preparation conditions of the catalyst in step (1) of Example 3 were changed. Specifically:

[0079] (1) Preparation of modified resin catalyst

[0080] In a round-bottom flask, 5.0 g of lanthanum sulfate and 280 g of a 15% sulfuric acid aqueous solution were mixed and heated in a water bath to 60°C with stirring for 8 hours to obtain a clear, transparent aqueous solution. 20 g of DB757 ion exchange resin was added to the above clear, transparent aqueous solution, and the mixture was heated to 70°C and refluxed with stirring 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 400 ml of deionized water and dried in air at 80°C for 20 hours to obtain modified resin catalyst E.

[0081] The structural parameters and composition of the modified resin catalyst E are listed in Table 1.

[0082] (2) Evaluation of catalyst reaction performance

[0083] The esterification performance of catalyst E was tested according to step (2) in Example 1. The experimental results are listed in Table 2.

[0084] Example 6

[0085] The modified resin catalyst F was prepared using the same method as in Example 1, except that the preparation conditions of the catalyst in step (1) of Example 1 were changed. Specifically:

[0086] (1) Preparation of modified resin catalyst

[0087] In a round-bottom flask, 0.7 g of lanthanum sulfate and 120 g of a 4% sulfuric acid aqueous solution were mixed and heated in a water bath to 70°C with stirring for 4 hours to obtain a clear, transparent aqueous solution. 20 g of ion exchange resin (model D008) was added to the above clear, transparent aqueous solution, and the mixture was heated to 80°C and refluxed with stirring 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 the modified resin catalyst F.

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

[0089] (2) Evaluation of catalyst reaction performance

[0090] The esterification performance of catalyst F was tested according to step (2) in Example 1. The experimental results are listed in Table 2.

[0091] Example 7

[0092] The modified resin catalyst G was prepared using the same method as in Example 3, except that the preparation conditions of the catalyst in step (1) of Example 3 were changed. Specifically:

[0093] (1) Preparation of modified resin catalyst

[0094] In a round-bottom flask, 6.7 g of lanthanum sulfate and 380 g of a 15% sulfuric acid aqueous solution were mixed and heated in a water bath to 60°C with stirring for 8 hours to obtain a clear, transparent aqueous solution. 20 g of DB757 ion exchange resin was added to the above clear, transparent aqueous solution, and the mixture was heated to 70°C and refluxed with stirring 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 400 ml of deionized water and dried in air at 80°C for 20 hours to obtain the modified resin catalyst G.

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

[0096] (2) Evaluation of catalyst reaction performance

[0097] The esterification performance of catalyst G was tested according to step (2) in Example 1. The experimental results are listed in Table 2.

[0098] Comparative Example 1

[0099] Modified resin catalyst D1 was prepared using the same method as in Example 1, except that the modified resin catalyst was not prepared according to step (1) in Example 1, but instead, ion exchange resin of type D008 was used as catalyst D1. The structural parameters and composition of catalyst D1 are listed in Table 1.

[0100] The esterification performance of catalyst D1 was tested according to step (2) in Example 1. The experimental results are listed in Table 2.

[0101] Comparative Example 2

[0102] Modified resin catalyst D2 was prepared using the same method as in Example 2, except that the modified resin catalyst was not prepared according to step (1) in Example 2, but instead, ion exchange resin of type D006 was used as catalyst D2. The structural parameters and composition of catalyst D2 are listed in Table 1.

[0103] The esterification performance of catalyst D2 was tested according to step (2) in Example 1. The experimental results are listed in Table 2.

[0104] Comparative Example 3

[0105] Modified resin catalyst D3 was prepared using the same method as in Example 3, except that instead of preparing the modified resin catalyst according to step (1) in Example 3, DB757 ion exchange resin was used as catalyst D3. The structural parameters and composition of catalyst D3 are listed in Table 1.

[0106] The esterification performance of catalyst D3 was tested according to step (2) in Example 1. The experimental results are listed in Table 2.

[0107] Comparative Example 4

[0108] The modified resin catalyst D4 was prepared using the same method as in Example 1, except that the preparation conditions of the catalyst in step (1) of Example 1 were changed. Specifically:

[0109] (1) Preparation of modified resin catalyst

[0110] In a round-bottom flask, 0.2 g of lanthanum sulfate and 100 g of a 0.5% sulfuric acid aqueous solution were mixed and heated in a water bath to 70°C with stirring for 4 hours to obtain a clear, transparent aqueous solution. 20 g of ion exchange resin (model D008) was added to the above clear, transparent aqueous solution, and the mixture was heated to 80°C and refluxed with stirring 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 the modified resin catalyst D4.

[0111] The structural parameters and composition of the modified resin catalyst D4 are listed in Table 1.

[0112] (2) Evaluation of catalyst reaction performance

[0113] The esterification performance of catalyst D4 was tested according to step (2) in Example 1. The experimental results are listed in Table 2.

[0114] Comparative Example 5

[0115] The modified resin catalyst D5 was prepared using the same method as in Example 2, except that the preparation conditions of the catalyst in step (1) of Example 2 were changed. Specifically:

[0116] (1) Preparation of modified resin catalyst

[0117] In a round-bottom flask, 8.2 g of lanthanum sulfate and 200 g of a 10% sulfuric acid aqueous solution were mixed and heated in a water bath to 90°C with stirring for 2 hours to obtain a clear, transparent aqueous solution. 10 g of ion exchange resin (model D006) was added to the above clear, transparent aqueous solution, and the mixture was heated to 100°C and refluxed with stirring for 1 hour. The reaction system was cooled to room temperature and filtered to obtain a solid product. The solid product was washed three times with 500 ml of deionized water and dried in air at 150°C for 3 hours to obtain the modified resin catalyst D5.

[0118] The structural parameters and composition of the modified resin catalyst D5 are listed in Table 1.

[0119] (2) Evaluation of catalyst reaction performance

[0120] The esterification performance of catalyst D5 was tested according to step (2) in Example 1. The experimental results are listed in Table 2.

[0121] Comparative Example 6

[0122] Modified resin catalyst D6 was prepared using the same method as in Example 1, except that in step (1), sodium sulfate was supported instead of lanthanum sulfate. Specifically:

[0123] (1) Preparation of modified resin catalyst

[0124] In a round-bottom flask, 2.5 g of sodium sulfate and 300 g of a 5% sulfuric acid aqueous solution were mixed and heated in a water bath to 70°C with stirring for 4 hours to obtain a clear, transparent aqueous solution. 20 g of ion exchange resin (model D008) was added to the above clear, transparent aqueous solution, and the mixture was heated to 80°C and refluxed with stirring 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 the modified resin catalyst D6.

[0125] Based on the total weight of the modified resin catalyst D6, the content of ion exchange resin is 89% by weight and the content of sodium sulfate is 11% by weight.

[0126] (2) Evaluation of catalyst reaction performance

[0127] The esterification performance of catalyst D6 was tested according to step (2) in Example 1. The experimental results are listed in Table 2.

[0128] Table 1

[0129]

[0130] Table 2

[0131]

[0132]

[0133] The results above show that the modified resin catalyst provided by the present invention can directly convert methacrylic acid and methanol into methyl methacrylate, achieving a high conversion rate of methacrylic acid and selectivity for methyl methacrylate, while maintaining good catalyst stability.

[0134] In Comparative Examples 1, 2, and 3, unmodified ion exchange resins were used as esterification catalysts. The conversion rate of methacrylic acid was low, the selectivity of methyl methacrylate was low, and the catalyst stability was poor.

[0135] In Comparative Example 4, the content of ion exchange resin in the modified resin catalyst was too high. Due to the low content of lanthanum sulfate, a modified component on the catalyst, the conversion rate of methacrylic acid was low, the selectivity of methyl methacrylate was low, and the catalyst stability was poor.

[0136] In Comparative Example 5, the content of ion exchange resin in the modified resin catalyst was too low. Due to the excessive content of lanthanum sulfate, a modified component on the catalyst, it was not evenly dispersed on the support, resulting in low conversion rate of methacrylic acid, low selectivity of methyl methacrylate, and poor catalyst stability.

[0137] In Comparative Example 6, sodium sulfate was used instead of lanthanum sulfate as the modifying component in the modified resin catalyst. Due to the poor modifying ability of sodium sulfate, the conversion rate of methacrylic acid was low, the selectivity of methyl methacrylate was low, and the catalyst stability was poor.

[0138] 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 modified resin catalyst in the synthesis reaction of methyl methacrylate, wherein the application includes: The reaction involves simultaneously contacting methacrylic acid and methanol with a modified resin catalyst, characterized in that the modified resin catalyst comprises a strong acid cation exchange resin and lanthanum sulfate; and based on the total weight of the modified resin catalyst, the content of the strong acid cation exchange resin is 75-97% by weight, and the content of the lanthanum sulfate is 3-25% by weight. The preparation method of the modified resin catalyst includes: (1) Lanthanum sulfate is mixed with an acidic aqueous solution to obtain a solution; (2) The solution is reacted with a strong acid cation exchange resin to obtain a mixture; wherein the weight ratio of the lanthanum sulfate to the strong acid cation exchange resin is 1:(3-30). (3) The mixture is filtered to obtain a solid product, and the solid product is then washed and dried in sequence to obtain a modified resin catalyst.

2. The application 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 80-96% by weight, and the content of the lanthanum sulfate is 4-20% by weight.

3. The application according to claim 2, wherein, The content of the strong acid cation exchange resin is 85-95% by weight, and the content of the lanthanum sulfate is 5-15% by weight.

4. The application according to claim 1 or 3, wherein, The modified resin catalyst has a specific surface area of ​​15-23 m². 2 / g, with a pore volume of 0.1-0.2mL / g.

5. The application according to claim 4, wherein, The modified resin catalyst has a specific surface area of ​​19-21 m². 2 / g, with a pore volume of 0.13-0.15mL / g.

6. The application according to claim 1, 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 lanthanum sulfate to the acidic aqueous solution is 1:(10-300).

7. The application according to claim 1, wherein, The weight ratio of lanthanum sulfate to the strong acid cation exchange resin is 1:(5-20).

8. The application according to claim 1, wherein, The conditions for contacting the solution with the strong acid cation exchange resin include: a temperature of 60-110℃ and a time of 0.5-8h. And / or, the drying conditions include: a temperature of 60-180°C and a time of 1-30 hours.

9. The application according to claim 1, wherein, The conditions for simultaneously contacting methacrylic acid and methanol with the modified resin catalyst include: a temperature of 40-150℃, a contact pressure of 0.01-5.0 MPa, and a mass hourly space velocity (HHSV) of methacrylic acid of 0.01-30 h⁻¹. -1 The mass hourly space velocity (MSV) of methanol is 0.01-50 h⁻¹. -1 .

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