Supported catalyst for synthesizing methyl methacrylate, preparation method and application thereof

Abstract

The present invention provides a supported catalyst for synthesizing methyl methacrylate. The catalyst includes a carrier and an active component arranged on the carrier. The carrier is a Ce-M-N composite oxide treated with glow discharge plasma. The active component is Au, M is selected from one or more of Al, Ni, Cu, and Zr, and N is selected from one or more of K, Ca, Ba, and Mg. The Au loading is 0.5-3.0 wt%. The supported catalyst for synthesizing methyl methacrylate and a preparation method thereof are provided. The Ce-M-N oxide composite is used as a carrier and is composited with M to reduce its oxygen vacancy formation energy, making it easier to form oxygen vacancies. The electrons and negatively charged high-energy particles in the glow discharge plasma are utilized to generate oxygen vacancies in CeO2. The oxygen vacancies are easily activated by oxygen adsorption, thereby facilitating the oxidative esterification reaction of methanol and methacrolein, thereby improving the activity of the catalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a supported catalyst for synthesizing methyl methacrylate, a preparation method and an application thereof. Background Art

[0002] Methyl methacrylate (MMA) is an important organic chemical raw material and polymer monomer, mainly used in the production of organic glass, coatings, adhesives, pharmaceutical polymer materials, etc. It is a high-end material in the fields of aerospace, electronic information, optical fiber, etc.

[0003] Currently, mature industrial processes for producing MMA include ethylene carbonyl synthesis, methacrylamide hydrolysis and esterification (acetone cyanohydrin and methacrylonitrile methods), and isobutylene oxidation. The traditional acetone cyanohydrin method is the most widely used MMA production process worldwide, but it requires the use of highly toxic HCN and large amounts of concentrated sulfuric acid, posing serious environmental and safety issues. There are two main isobutylene oxidation routes. One involves oxidizing isobutylene to methacrolein (MAL), which is then oxidized to methacrylic acid (MAA), which then reacts with methanol to produce MMA. The other involves direct oxidative esterification of MAL to produce MMA, effectively avoiding the intermediate MAA and side reactions such as MAA polymerization, simplifying the process, and reducing energy consumption.

[0004] Asahi Kasei Corporation of Japan initially developed a process for the direct oxidative esterification of MAL to MMA, primarily using a Pd-Pb catalyst. However, the toxicity and contamination of Pb significantly limited its application. Subsequent catalyst development progressed from improved heteropolyacid-based catalysts to precious metal catalysts such as platinum, ruthenium, and gold. Au catalysts exhibited excellent catalytic performance in the one-step oxidative esterification of MAL, achieving high selectivity but exhibiting low conversion rates. Monometallic Au catalysts, while highly active, are susceptible to loss of active components, leading to decreased activity and limiting their industrial application. Therefore, improving the activity and stability of Au catalysts remains a key research priority and a challenge. Summary of the Invention

[0005] The purpose of the present invention is to overcome and supplement the deficiencies in the prior art, provide a supported catalyst for synthesizing methyl methacrylate, and a preparation method and application thereof, thereby solving the problems of low reaction conversion rate of supported catalysts for synthesizing methyl methacrylate and easy deactivation of single Au catalysts.

[0006] The supported catalyst for the synthesis of methyl methacrylate uses Ce-MN composite oxide as the carrier. The valence state conversion of Ce is accompanied by the formation of oxygen vacancies, which is not only beneficial to the adsorption and activation of oxygen, but also can effectively disperse and stabilize Au nanoparticles, thereby improving the catalytic activity and stability. The combination of M and CeO2 can change the crystal structure of CeO2, thereby reducing the oxygen vacancy formation energy and facilitating the formation of more oxygen vacancies. There are a large number of electrons and negatively charged high-energy particles in the glow discharge plasma, which can realize the generation of oxygen vacancies in CeO2. At the same time, it can strengthen the interaction between Ce oxide complexes, making the Au nanoparticles highly dispersed on its surface. Therefore, it catalyzes the oxidative esterification reaction of methanol and methacrolein, and improves the activity and stability of the catalyst while obtaining high selectivity.

[0007] The technical solution adopted in the present invention is:

[0008] A supported catalyst for synthesizing methyl methacrylate, wherein the catalyst comprises a carrier and an active component arranged on the carrier, the carrier is a Ce-MN composite oxide treated by glow discharge plasma, the active component is Au, the M is selected from one or more of Al, Ni, Cu, and Zr, the N is selected from one or more of K, Ca, Ba, and Mg, and the loading amount of the Au is 0.5-3.0 wt%.

[0009] Preferably, the supported catalyst for synthesizing methyl methacrylate has a specific surface area of ​​120-200 cm 2 / g, pore volume of 0.4-0.8cm 3 / g, a pore diameter of 8-15nm, and the Ce-MN composite oxide is alkaline.

[0010] Preferably, in the supported catalyst for synthesizing methyl methacrylate, the Ce-MN composite oxide comprises, by mass percentage, 5-50 wt% CeO2, 30-90 wt% MO and 5-50 wt% NO.

[0011] A method for preparing a supported catalyst for synthesizing methyl methacrylate, comprising the following steps:

[0012] Step S1. Ce, M, and N nitrates are dissolved in deionized water and stirred evenly. The mixture is heated to 60-90°C, ammonia is added, the pH is adjusted to 8-10, and stirring is continued for 1-6 hours. The mixture is then transferred to a hydrothermal reactor and kept at 140-200°C for 6-12 hours. The mixture is cooled to room temperature to obtain a mixture. The mixture is then filtered, washed, dried, and calcined to obtain a Ce-MN composite oxide, which is then crushed to 200 mesh for later use.

[0013] Step S2. placing the Ce-MN composite oxide in a glow discharge plasma reactor, introducing a discharge gas, maintaining the gas pressure at a first pressure, applying a high voltage to induce a glow discharge plasma, and maintaining the pressure for 5-120 min to obtain a Ce-MN composite oxide after glow discharge plasma treatment;

[0014] Step S3. Add the Ce-MN composite oxide prepared in step S2 to deionized water and stir thoroughly. Heat the mixture to 60-90°C to form a solution with a pH range of 7-8. Then, add HAuCl4 solution dropwise to the solution. After stirring for 1-4 hours, add NaOH solution and adjust the pH of the mixture to 8-10. Continue stirring for 1-6 hours, cool and filter, and calcine to obtain a supported catalyst.

[0015] Preferably, in the method for preparing a supported catalyst for synthesizing methyl methacrylate, the drying temperature in step S1 is 110° C.-150° C., and the drying time is 6-12 hours; the calcination temperature is 400-800° C., and the calcination time is 2-6 hours.

[0016] Preferably, in the method for preparing a supported catalyst for synthesizing methyl methacrylate, the discharge gas introduced in step S2 is selected from one of nitrogen, argon, air and oxygen.

[0017] Preferably, in the method for preparing a supported catalyst for synthesizing methyl methacrylate, the first gas pressure in step S2 is 40-150 Pa.

[0018] Preferably, in the method for preparing a supported catalyst for synthesizing methyl methacrylate, the calcination temperature in step S3 is 250-500° C. and the calcination time is 1-4 hours.

[0019] The invention discloses an application of a supported catalyst for synthesizing methyl methacrylate, wherein the supported catalyst is applied to a one-step oxidative esterification reaction for preparing methyl methacrylate using methanol and methacrolein as raw materials.

[0020] Preferably, the application of the supported catalyst for synthesizing methyl methacrylate comprises the following steps: adding methanol, methacrolein, and the supported catalyst into a reaction kettle, sealing the reaction kettle, heating the reaction kettle to 60-90° C., introducing air or oxygen, and reacting the reaction kettle at a certain stirring speed for 1-8 hours to obtain methyl methacrylate.

[0021] Advantages of the present invention:

[0022] (1) The supported catalyst for synthesizing methyl methacrylate and the preparation method thereof of the present invention use a Ce-MN oxide complex as a carrier and compound with M to reduce its oxygen vacancy formation energy, making it easier to form oxygen vacancies. The electrons and negatively charged high-energy particles in the glow discharge plasma are used to generate oxygen vacancies in CeO2. The oxygen vacancies are easily activated by oxygen adsorption, which is beneficial to the oxidative esterification reaction of methanol and methacrolein, thereby improving the activity of the catalyst.

[0023] (2) The supported catalyst for synthesizing methyl methacrylate and the preparation method thereof of the present invention use the oxide obtained by glow discharge plasma treatment of Ce-MN composite oxide as a carrier, thereby enhancing the interaction between the oxides and facilitating the dispersion of Au nanoparticles on the surface; oxygen vacancies can also effectively disperse and stabilize the metal, thus solving the problem of easy loss of single metal Au. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a TEM photograph of the catalyst prepared in Example 1 of the present invention.

[0025] Figure 2 This is a performance result diagram of the catalyst application experiment prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0027] Example 1

[0028] A supported catalyst for synthesizing methyl methacrylate comprises a carrier and an active component disposed on the carrier. The carrier is a Ce-MN composite oxide treated by glow discharge plasma, and the active component is Au. The Ce-Al-K composite oxide prepared in this embodiment comprises 30% CeO2, 50% Al2O3, and 20% K2O, and has a specific surface area of ​​153.4 m 2 / g, pore volume is 0.6cm 3 / g, and the pore size is 12.2nm.

[0029] A method for preparing a supported catalyst for synthesizing methyl methacrylate comprises the following steps:

[0030] Step S1. 11.4 g of Ce(NO3)3·6H2O, 27.6 g of Al(NO3)3·6H2O and 3.2 g of KNO3 were dissolved in 300 g of deionized water and stirred uniformly. The mixture was heated to 70°C, ammonia was added, the pH was adjusted to 8.5, and stirring was continued for 1 hour. The mixture was then transferred to a hydrothermal autoclave, maintained at 150°C for 12 hours, and cooled to room temperature to obtain a mixture. The mixture was filtered and washed, and the obtained precipitate was dried at 110°C for 12 hours. Finally, it was calcined at 450°C for 6 hours to obtain a Ce-Al-K composite oxide, which was then crushed and ground to 200 mesh for later use.

[0031] Step S2. The Ce-Al-K composite oxide obtained in step S1 is placed in a glow discharge plasma reactor, nitrogen is introduced, the gas pressure is maintained at 60 Pa, high voltage is applied to induce glow discharge plasma, and the pressure is maintained for 30 min;

[0032] Step S3. Take 9.9 g of the Ce-Al-K composite oxide in step S2, add 100 g of deionized water and stir thoroughly, heat to 80°C, and form a solution with a pH of 7.8. Then, 5.1 mL of 0.1 M HAuCl4 solution is added dropwise to the solution. After stirring for 1 hour, NaOH solution is added to adjust the pH to 9.5. Stirring is continued for 1 hour. After cooling and filtration, the mixture is calcined at 250°C for 4 hours to obtain a supported 1.0 wt.% Au / Ce-Al-K catalyst.

[0033] Example 2

[0034] A supported catalyst for synthesizing methyl methacrylate comprises a carrier and an active component disposed on the carrier. The carrier is a Ce-MN composite oxide treated by glow discharge plasma, and the active component is Au. The Ce-Zr-Ba composite oxide prepared in this embodiment comprises 15% CeO2, 70% ZrO2, and 15% BaO, and has a specific surface area of ​​179.6 m 2 / g, pore volume 0.6cm 3 / g, pore size 10.2nm.

[0035] A method for preparing a supported catalyst for synthesizing methyl methacrylate comprises the following steps:

[0036] Step S1. 5.7 g of Ce(NO3)3·6H2O, 36.6 g of Zr(NO3)4·5H2O and 3.8 g of Ba(NO3)2 were dissolved in 300 g of deionized water and stirred uniformly. The mixture was heated to 80°C, and aqueous ammonia was added to adjust the pH to 8.0. The mixture was stirred for 1 hour. The mixture was then transferred to a hydrothermal autoclave and maintained at 180°C for 7 hours. The mixture was cooled to room temperature to obtain a mixture. The mixture was filtered and washed. The obtained precipitate was dried at 110°C for 12 hours and then calcined at 600°C for 3 hours to obtain a Ce-Zr-Ba composite oxide, which was then crushed and ground to 200 mesh for later use.

[0037] Step S2. The Ce-Zr-Ba composite oxide obtained in step S1 is placed in a glow discharge plasma reactor, argon gas is introduced, the gas pressure is maintained at 120 Pa, high voltage electricity is applied to induce glow discharge plasma, and the pressure is maintained for 20 minutes;

[0038] Step S3. Take 9.8 g of the Ce-Zr-Ba composite oxide obtained in step S2, add 100 g of deionized water and stir thoroughly, raise the temperature to 70°C, and the pH of the formed solution is 7.6. 10.2 mL of 0.1 M HAuCl4 solution is added dropwise to the solution. After stirring for 1 hour, NaOH solution is added to adjust the pH to 9.0. Stirring is continued for 1 hour. After cooling and filtering, it is calcined at 450°C for 2 hours to obtain a supported 2.0 wt.% Au / Ce-Zr-Ba catalyst.

[0039] Example 3

[0040] A supported catalyst for synthesizing methyl methacrylate comprises a carrier and an active component disposed on the carrier. The carrier is a Ce-MN composite oxide treated by glow discharge plasma, and the active component is Au. The Ce-Ni-Ca composite oxide prepared in this embodiment comprises 35% CeO2, 55% NiO, and 10% CaO, and has a specific surface area of ​​140.1 m 2 / g, pore volume 0.5cm 3 / g, pore diameter 12.9nm.

[0041] A method for preparing a supported catalyst for synthesizing methyl methacrylate comprises the following steps:

[0042] Step S1. 13.2 g of Ce(NO3)3·6H2O, 32.1 g of Ni(NO3)2·6H2O and 6.3 g of Ca(NO3)2·4H2O were dissolved in 300 g of deionized water and stirred uniformly, the mixture was heated to 85°C, ammonia water was added, the pH was adjusted to 8.5, and stirring was continued for 1 hour to obtain a mixed solution, the mixed solution was transferred to a hydrothermal autoclave, maintained at 160°C for 10 hours, and cooled to room temperature to obtain a mixture, the mixture was filtered and washed, the obtained precipitate was dried at 110°C for 12 hours, and then calcined at 500°C for 4 hours to obtain a Ce-Ni-Ca composite oxide, and the mixture was crushed and ground to 200 mesh for use;

[0043] Step S2. The Ce-Ni-Ca composite oxide obtained in step S1 is placed in a glow discharge plasma reactor, air is introduced, the gas pressure is maintained at 100 Pa, high voltage is applied to induce glow discharge plasma, and the pressure is maintained for 40 min;

[0044] Step S3. Take 9.85g of the Ce-Ni-Ca composite oxide obtained in step S2, add 100g of deionized water and stir thoroughly, raise the temperature to 85°C, and the pH of the formed solution is 7.2. Then, 7.6mL of 0.1M HAuCl4 solution is added dropwise to the melt. After stirring for 1h, NaOH solution is added to adjust the pH to 8.0, and stirring is continued for 1h. After cooling and filtering, it is calcined at 350°C for 2.5h to obtain a supported 1.5wt.% Au / Ce-Ni-Ca catalyst.

[0045] Example 4

[0046] A supported catalyst for synthesizing methyl methacrylate comprises a carrier and an active component disposed on the carrier. The carrier is a Ce-MN composite oxide treated by glow discharge plasma, and the active component is Au. The Ce-Cu-Mg composite oxide prepared in this embodiment comprises 20% CeO2, 75% CuO, and 15% MgO, and has a specific surface area of ​​165.0 m 2 / g, pore volume 0.6cm 3 / g, pore diameter 11.1nm.

[0047] A method for preparing a supported catalyst for synthesizing methyl methacrylate comprises the following steps:

[0048] Step S1. 7.6 g of Ce(NO3)3·6H2O, 34.2 g of Cu(NO3)2·3H2O and 14.3 g of Mg(NO3)2·6H2O were dissolved in 300 g of deionized water and stirred uniformly. The mixture was heated to 75°C, and aqueous ammonia was added to adjust the pH to 9.0. The mixture was stirred for 1 hour to obtain a mixed solution. The mixed solution was transferred to a hydrothermal autoclave, maintained at 150°C for 10 hours, and cooled to room temperature to obtain a mixture. The mixture was filtered and washed. The obtained precipitate was dried at 110°C for 12 hours and then calcined at 500°C for 4 hours to obtain a Ce-Cu-Mg composite oxide, which was then crushed and ground to 200 mesh for later use.

[0049] Step S2. The Ce-Cu-Mg composite oxide obtained in step S1 is placed in a glow discharge plasma reactor, oxygen is introduced, the gas pressure is maintained at 80 Pa, high voltage is applied to induce glow discharge plasma, and the pressure is maintained for 20 minutes;

[0050] Step S3. Take 10 g of the Ce-Cu-Mg composite oxide obtained in step S2, add 100 g of deionized water and stir thoroughly, raise the temperature to 75°C, and the pH of the formed solution is 7.5. Then, 5.1 mL of 0.1 M HAuCl4 solution is added dropwise to the solution. After stirring for 1 hour, NaOH solution is added to adjust the pH to 8.0, and stirring is continued for 1 hour. After cooling and filtering, the solution is calcined at 300°C for 3 hours to obtain a supported 1.0 wt.% Au / Ce-Cu-Mg catalyst.

[0051] Example 5

[0052] The Au / Ce-MN catalyst is used as a supported catalyst for the synthesis of methyl methacrylate. The Au / Ce-MN catalyst is used to catalyze the synthesis of methyl methacrylate from methanol and methacrolein. The specific application includes the following steps:

[0053] 18.3 g of methanol and 2 g of methacrolein (MAL) were added to the reactor, and the Au / Ce-MN catalysts prepared in Example 1, Example 2, Example 3, Example 4, and Comparative Example 1 were added at a ratio of m(MAL:Au) = 1:0.4%. After sealing, the reactor was heated to 80° C., 0.8 MPa of oxygen was introduced, and the reaction was carried out at a certain stirring speed for 2-6 hours. Samples were taken for gas chromatography analysis. The results are shown in Table 1.

[0054] Comparative Example 1

[0055] Step S1. 11.4 g of Ce(NO3)3·6H2O, 27.6 g of Al(NO3)3·6H2O and 3.2 g of KNO3 were dissolved in 300 g of deionized water and stirred uniformly. The mixture was heated to 70°C, ammonia was added, the pH was adjusted to 8.5, and stirring was continued for 1 hour to obtain a mixed solution. The mixed solution was transferred to a hydrothermal autoclave, maintained at 150°C for 12 hours, and cooled to room temperature to obtain a mixture. The mixture was filtered and washed. The obtained precipitate was dried at 110°C for 12 hours and then calcined at 450°C for 6 hours to obtain a Ce-Al-K composite oxide, which was then crushed and ground to 200 mesh for later use.

[0056] Step S2. The Ce-Al-K composite oxide obtained in step S1 is placed in a glow discharge plasma reactor, nitrogen is introduced, the gas pressure is maintained at 60 Pa, high voltage is applied to induce glow discharge plasma, and the pressure is maintained for 30 min;

[0057] Step S3. Take 9.8 g of the Ce-Al-K composite oxide obtained in step S2, add 100 g of deionized water and stir thoroughly, raise the temperature to 80°C, and the pH of the formed solution is 7.8. Then, 5.1 mL of 0.1 M HAuCl4 solution and 8.5 mL of 0.2 M Ni(NO3)2·6H2O solution are added dropwise to the solution. After stirring for 1 hour, NaOH solution is added to adjust the pH to 9.5, and stirring is continued for 1 hour. After cooling and filtering, the mixture is calcined at 250°C for 4 hours to obtain a supported 1.0 wt.% Au-1.0 wt.% Ni / Ce-Al-K catalyst.

[0058] The results of the synthesis of methyl methacrylate from methanol and methacrolein catalyzed by the catalysts prepared in Examples 1-4 and Comparative Example 1 are shown in Table 1.

[0059] Table 1

[0060]

[0061] As can be seen from Table 1, after 4 hours of reaction, the Au / Ce-MN prepared in Examples 1-4 has almost completely converted methacrolein and obtained a higher selectivity. Compared with the AuNi / Ce-Al-K prepared in Comparative Example 1, the Au / Ce-Al-K prepared in Example 1 has a higher conversion rate and selectivity.

[0062] Apply the experiment

[0063] The performance evaluation of Au / Ce-Al-K catalyst for synthesizing methyl methacrylate from methanol and methacrolein includes the following steps:

[0064] After each reaction, the catalyst was centrifuged and recovered, and 2% of the initial amount of fresh catalyst was added. The experiment was repeated according to the steps of Example 5, and the reaction was carried out for 4 hours to verify the recycling performance of the catalyst. The results are shown in FIG. Figure 2 shown.

[0065] Figure 2 The Au / Ce-Al-K prepared in Example 1 maintained high activity and conversion after 20 cycles, indicating that the single Au catalyst prepared in the present invention has high stability. The ICP results of the fresh Au / Ce-Al-K catalyst and the catalyst after 20 cycles are shown in Table 2. Based on the calculated data, the Au loading of the fresh catalyst was 1.02 wt.%, which is consistent with the theoretical loading, while the Au loading after 20 cycles was 0.96 wt.%, confirming that there was no significant loss of Au.

[0066] Table 2

[0067] Detection elements Fresh catalyst Catalyst after 20 applications Au 10.2mg / g 9.6mg / g

[0068] The electrode preparation method of the present invention is simple and easy to implement, and can quickly and flexibly produce membrane electrodes with beautiful appearance and various shapes by simply changing the shape of the tooling used in the hot pressing process.

[0069] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An application of a supported catalyst for synthesizing methyl methacrylate, characterized in that: The supported catalyst is used in a one-step oxidative esterification reaction to produce methyl methacrylate using methanol and methacrolein as raw materials. The supported catalyst for synthesizing methyl methacrylate comprises a carrier and an active component arranged on the carrier, wherein the carrier is a Ce-MN composite oxide treated with glow discharge plasma, the active component is Au, M is selected from one or more of Al, Ni, Cu, and Zr, and N is selected from one or more of K, Ca, Ba, and Mg, and the loading amount of Au is 0.5-3.0 wt%.

2. The use of a supported catalyst for synthesizing methyl methacrylate according to claim 1, wherein: The specific surface area of ​​Ce-MN composite oxide is 120-200 cm 2 / g, pore volume of 0.4-0.8 cm 3 / g, a pore diameter of 8-15nm, and the Ce-MN composite oxide is alkaline.

3. The use of a supported catalyst for synthesizing methyl methacrylate according to claim 1, wherein: Calculated by mass percentage, the Ce-MN composite oxide includes 5-50 wt% CeO2, 30-90 wt% MO and 5-50 wt% NO.

4. The use of a supported catalyst for synthesizing methyl methacrylate according to claim 1, wherein: The preparation method of the supported catalyst comprises the following steps: Step S1. Ce, M, and N nitrates are dissolved in deionized water and stirred uniformly. The mixture is heated to 60-90°C, ammonia is added, the pH is adjusted to 8-10, and stirring is continued for 1-6 hours. The mixture is then transferred to a hydrothermal reactor and kept at 140-200°C for 6-12 hours. The mixture is cooled to room temperature to obtain a mixture. The mixture is then filtered, washed, dried, and calcined to obtain a Ce-MN composite oxide, which is then pulverized to 200 mesh for later use. Step S2. placing the Ce-MN composite oxide in a glow discharge plasma reactor, introducing a discharge gas, maintaining the gas pressure at a first pressure, applying a high voltage to induce a glow discharge plasma, and maintaining the pressure for 5-120 min to obtain a Ce-MN composite oxide after glow discharge plasma treatment; Step S3. Add the Ce-MN composite oxide prepared in step S2 to deionized water and stir thoroughly. Heat the mixture to 60-90°C to form a solution with a pH range of 7-8. Then, add HAuCl4 solution dropwise to the solution. After stirring for 1-4 hours, add NaOH solution and adjust the pH of the mixture to 8-10. Continue stirring for 1-6 hours, cool and filter, and calcine to obtain a supported catalyst.

5. The use of a supported catalyst for synthesizing methyl methacrylate according to claim 4, wherein: The drying temperature of step S1 is 110-150° C., and the drying time is 6-12 hours; the roasting temperature is 400-800° C., and the roasting time is 2-6 hours.

6. The use of a supported catalyst for synthesizing methyl methacrylate according to claim 4, characterized in that: The discharge gas introduced in step S2 is selected from one of nitrogen, argon, air and oxygen.

7. The use of a supported catalyst for synthesizing methyl methacrylate according to claim 4, wherein: The first gas pressure in step S2 is 40-150 Pa.

8. The use of a supported catalyst for synthesizing methyl methacrylate according to claim 4, wherein: The calcination temperature in step S3 is 250-500° C., and the calcination time is 1-4 h.

9. The use of a supported catalyst for synthesizing methyl methacrylate according to claim 1, wherein: The specific application process is: add methanol, methacrolein and a supported catalyst into a reactor, seal it, heat it to 60-90°C, introduce air or oxygen, and react for 1-8 hours at a certain stirring speed to obtain methyl methacrylate.

Images