A catalyst for producing methyl methacrylate and a method for producing methyl methacrylate

Abstract

Disclosed are a catalyst for preparing methyl methacrylate represented by the following Chemical Formula 1, wherein a, b and c are weight ratios of active components Mg, Si and X, respectively, and d is a stoichiometric ratio of O atoms, wherein the mass fraction of Si is 20-500% and the mass fraction of X is 0.1-100% based on the mass of magnesium oxide (MgO), wherein X is selected from one or more of Mn, Fe, Ni, Co, Cu, Cr, Zn, Cs, Mo, W, Cd, P, Al, Na and K, a preparation method of the catalyst, and a preparation method of methyl methacrylate using the catalyst, which synthesizes methyl methacrylate in one step without separation using methanol and methyl acetate as raw materials. a Si b X c O d , Chemical Formula 1.

Description

Technical Field

[0001] This invention belongs to the field of fine chemicals, specifically relating to a catalyst for preparing methyl methacrylate, a method for preparing the catalyst, and a method for preparing methyl methacrylate using the catalyst, wherein the method for preparing methyl methacrylate uses methanol and methyl acetate as raw materials to synthesize methyl methacrylate in one step. Background Technology

[0002] Methyl methacrylate (MMA) is an important bulk chemical that can be used not only as an organic chemical raw material but also directly as a chemical product. As an organic chemical raw material, it is mainly used in the production of plexiglass (polymethyl methacrylate, PMMA), and also in the manufacture of polyvinyl chloride (PVC) additives such as ACR, and as a second monomer in the production of acrylonitrile. Furthermore, it has wide applications in adhesives, coatings, resins, textiles, and papermaking industries. As a chemical product, it can be directly applied in many fields, including leather, ion exchange resins, paper varnishes, textile printing and dyeing auxiliaries, leather treatment agents, lubricant additives, crude oil pour point depressants, impregnating agents for wood and softwood, impregnating agents for motor coils, plasticizers for insulating potting materials and plastic emulsions, floor polishing, unsaturated resin modification, and higher methacrylate esters. Therefore, the production prospects of MMA are broad and its significance is substantial.

[0003] Currently, the main industrial methods for producing methyl methacrylate (MMA) are the acetone cyanohydrin (ACH) process and the isobutylene / propylene oxidation process. Among these methods, the traditional acetone cyanohydrin process is the most important, accounting for approximately 80% of the world's total MMA production capacity. However, this process uses highly toxic hydrogen cyanide and requires the treatment of large quantities of ammonium bisulfate as a byproduct, and is therefore restricted in my country. The isobutylene process has developed rapidly in the last decade or so, with multiple isobutylene-based MMA production plants built in Japan, South Korea, and Singapore. Several new plants in my country also utilize this method. The isobutylene oxidation process has relatively abundant C4 feedstock and high atom utilization, but its drawbacks include a long process flow, complex equipment, high investment, low overall selectivity, and high production costs. Production methods using ethylene as a raw material include the BASF process (ethylene hydroformylation to produce propionaldehyde, which is then reacted with formaldehyde to produce MMA) and the Alpha process (ethylene-methanol-CO reaction to produce methyl propionate, which is then reacted with formaldehyde to produce MMA). The Alpha process is safer, uses no toxic or corrosive chemicals, and has lower equipment investment, maintenance costs, and production costs. Therefore, it is still necessary to explore a more suitable methyl methacrylate production process for my country's conditions.

[0004] The one-step process for producing methyl methacrylate from methanol and methyl acetate is inexpensive and readily available, and avoids the separation of intermediate products. The entire reaction process is simple, mild, and environmentally friendly. Therefore, the one-step gas-phase condensation reaction of methanol and methyl acetate to produce methyl methacrylate has significant competitive advantages and promising industrial application prospects. Summary of the Invention

[0005] According to a first aspect of the invention, an object of the invention is to provide a catalyst for the preparation of methyl methacrylate, the catalyst being represented by the following chemical formula 1:

[0006] Mg a Si b X c O d Chemical formula 1

[0007] In chemical formula 1, a, b, and c are the weight ratios of the active components Mg, Si, and X, respectively, and d is the stoichiometric ratio of O atoms. Based on the mass of magnesium oxide (MgO), the mass fraction of Si is 20-500%, and the mass fraction of X is 0.1-100%. X is selected from one or more of Mn, Fe, Ni, Co, Cu, Cr, Zn, Cs, Mo, W, Cd, P, Al, Na, and K.

[0008] Preferably, based on the mass calculation of magnesium oxide (MgO), the mass fraction of active component Si is 100-300%, and the mass fraction of active component X is 1-10%.

[0009] Preferably, X is selected from one or more of Mn, Fe, Ni, Cu, Cr, Zn, Cs, Na and K.

[0010] Preferably, the catalyst contains a support selected from molecular sieves such as HZSM-5, SBA-15, and MCM-41. Based on the mass of magnesium oxide (MgO), the mass fraction of the molecular sieve is 50-200%.

[0011] According to a second aspect of the present invention, another object of the present invention is to provide a method for preparing the catalyst for preparing methyl methacrylate, the method being carried out as follows:

[0012] A 0.2-2 mol / L solution is prepared by dissolving a salt or alkali containing Na and K in deionized water. The precursor salt of active component X is dissolved in the above solution, and then hexadecyltrimethylammonium bromide (CTAB) is added. After dissolution, MgO powder or Mg(NO3)2·6H2O precursor is added while stirring. After stirring for a certain period of time, tetraethoxysilane (TEOS) is added dropwise. The mixture is stirred at a certain temperature, then filtered and washed. After drying at 80-120℃ or hydrothermal crystallization in a crystallization kettle at 100-220℃, the mixture is calcined at 400-600℃ to obtain the final catalyst product.

[0013] The precursor salt of the active component X is selected from nitrates, chlorides, oxides, hydroxides, acetates, etc.

[0014] According to a third aspect of the invention, another object of the invention is to provide the use of the catalyst in the preparation of methyl methacrylate.

[0015] According to a fourth aspect of the invention, another object of the invention is to provide a method for producing methyl methacrylate from methanol and methyl acetate in a one-step process, said method employing the catalyst described in the invention for a catalytic reaction, said method being carried out as follows:

[0016] The catalyst was tableted under a pressure of 8-20 MPa, and 20-60 mesh 3-12 mL catalyst was screened and packed into a fixed-bed reactor. The reactant was a methanol solution of methyl acetate (5%-60% by mass). The reactant was passed through the fixed-bed reactor under a carrier gas. The reaction pressure was 0.1-2.0 MPa, the reaction temperature was 200-400℃, and the feed space velocity was 0.1-10 h⁻¹. -1 .

[0017] The carrier gas is selected from nitrogen, and the carrier gas flow rate is 0.1-100 mL / min.

[0018] Preferably, the catalyst is composed of 10-100 mesh particles with a filling volume between 1 mL and 15 mL, ensuring its presence in the temperature control zone of the fixed-bed reactor.

[0019] Preferably, the fixed-bed reactor can be a single-stage or two-stage reactor.

[0020] Beneficial effects

[0021] This invention uses inexpensive and readily available methanol and methyl acetate as raw materials to directly produce high-value-added methyl methacrylate in a one-step process without separation. The process is simple to operate, the byproducts are easily separated, the conditions are mild, and it is environmentally friendly. Detailed Implementation

[0022] The present invention will now be described in detail. Before proceeding with the description, it should be understood that the terminology used in this specification and the appended claims should not be construed as limited to its general or dictionary meaning, but rather should be interpreted according to the meaning and concept corresponding to the technical aspects of the invention, based on the principle that the inventors are allowed to appropriately define the terms for the best interpretation. Therefore, the description presented herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of the invention. It should be understood that other equivalents or modifications can be obtained from it without departing from the spirit and scope of the invention.

[0023] In this document, the terms “comprising,” “including,” “having,” “containing,” or any similar terms are open-ended transitional phrases intended to encompass non-exclusive inclusions. For example, a composition or article containing a plural element is not limited to the elements listed herein, but may also include other elements not explicitly listed but typically inherent to the composition or article. Furthermore, unless explicitly stated otherwise, the term “or” is inclusive, not exclusive. For example, the condition “A or B” is satisfied in any of the following cases: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); A and B are both true (or exist). Moreover, in this document, the terms “comprising,” “including,” “having,” and “containing” should be interpreted as specifically disclosed and simultaneously encompassing closed or semi-closed transitional phrases such as “composed of” and “substantially composed of.”

[0024] In this document, all features or conditions defined in the form of numerical ranges or percentage ranges are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible secondary ranges and individual values ​​within those ranges, particularly integer values. For example, a range description of "1 to 8" should be considered as specifically disclosing all secondary ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., particularly secondary ranges defined by all integer values, and should be considered as specifically disclosing individual values ​​within those ranges such as 1, 2, 3, 4, 5, 6, 7, 8, etc. Unless otherwise specified, the foregoing interpretation applies to all content throughout this invention, regardless of its scope.

[0025] If a quantity or other numerical value or parameter is expressed as a range, a preferred range, or a series of upper and lower limits, it should be understood that this document has specifically disclosed all ranges consisting of any upper or preferred value of that range and the lower or preferred value of that range, regardless of whether such ranges are separately disclosed. Furthermore, when a range of numerical values ​​is mentioned herein, unless otherwise stated, the range shall include its endpoints and all integers and fractions within the range.

[0026] In this document, numerical values ​​are to be understood as having a precision with significant digits, provided that the purpose of the invention can be achieved. For example, the number 40.0 should be understood to cover a range from 39.50 to 40.49.

[0027] In the catalyst Mg used for the preparation of methyl methacrylate according to the present invention a Si b X c O d It contains at least three main active ingredients: Mg, Si, and X, wherein X is selected from one or more of Mn, Fe, Ni, Co, Cu, Cr, Cs, Zn, Mo, W, Cd, P, Al, Na, and K; preferably, X is selected from one or more of Mn, Fe, Ni, Cu, Cr, Zn, Cs, Na, and K.

[0028] In addition, the catalyst may also contain a support selected from molecular sieves such as HZSM-5, SBA-15, and MCM-41. Based on the mass of magnesium oxide (MgO), the mass fraction of the molecular sieve is 50-200%. When the content of the molecular sieve is within the above range, it is easier to form a Mg-Si-X-like solid solution structure, which promotes the reaction.

[0029] By rationally selecting and controlling the proportions of various active ingredients within the range described in this invention, the prepared catalyst exhibits excellent catalytic performance, such as high selectivity for the product methyl methacrylate.

[0030] The catalyst according to the present invention is prepared as follows:

[0031] A 0.2-2 mol / L solution is prepared by dissolving a salt or alkali containing Na and K in deionized water. The precursor salt of active component X is dissolved in the above solution, and then hexadecyltrimethylammonium bromide (CTAB) is added. After dissolution, Mg(NO3)2·6H2O or MgO powder is added while stirring. After stirring for a certain period of time, tetraethoxysilane (TEOS) is added dropwise. The mixture is stirred at a certain temperature, then filtered and washed. After drying at 80-120℃ or hydrothermal crystallization in a crystallization kettle at 100-220℃, the final catalyst product is calcined at 450-600℃.

[0032] The precursor salt of the active component X is selected from nitrates, chlorides, oxides, hydroxides, acetates, etc.

[0033] Catalysts prepared by adding surfactants such as CTAB tend to form pores, which greatly increases the specific surface area, thereby increasing the contact area between the catalyst and the reaction substrate and increasing the reaction rate.

[0034] In addition, unless otherwise stated, the reagents and solvents disclosed below were purchased from Sinopharm Chemical Reagent Co., Ltd. Quantitative analysis of the products was performed using a Shimazu-GC-2010-Plus GC-MS (Shimazu-QP-2010-Ultra), and qualitative analysis was performed using GC-MS. Conversion and selectivity were calculated using the area normalization method.

[0035] The following embodiments are merely examples illustrating implementations of the present invention and do not constitute any limitation on the present invention. Those skilled in the art will understand that modifications made without departing from the spirit and concept of the present invention fall within the protection scope of the present invention. Unless otherwise specified, the reagents and instruments used in the following embodiments are commercially available products.

[0036] Example 1

[0037] Catalyst preparation 1: 1.0 g CTAB was dissolved in 100 mL of water and stirred at room temperature until clear. 8 g MgO was added and stirred for 3 hours. 7.5 g TEOS and 7 g zinc nitrate solution were added dropwise and stirred overnight. The mixture was filtered, washed, dried, and calcined at 550 degrees Celsius for 4 hours.

[0038] Catalyst Evaluation: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 0.3 MPa and 300°C. The reaction solution was a 10% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 31%, and the selectivity of methyl methacrylate was 52%.

[0039] Example 2

[0040] Catalyst preparation 2: Dissolve 5g of 50% manganese nitrate aqueous solution in 100mL of water, add 1g of CTAB, and after dissolution, add 8g of MgO while stirring. Stir at room temperature for 3h, add 7.5g of TEOS dropwise, stir overnight at 75°C, filter, wash, dry in an oven at 100°C, and calcine at 550°C for 4h.

[0041] Catalyst Evaluation: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 0.3 MPa and 300°C. The reaction solution was a 10% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 30%, and the selectivity of methyl methacrylate was 50%.

[0042] Example 3

[0043] Catalyst preparation 3: Dissolve 6g of ferric nitrate hexahydrate in 100mL of water, add 1g of CTAB, and after dissolution, add 8g of MgO while stirring. Stir at room temperature for 3h, add 7.5g of TEOS dropwise, stir overnight at 75°C, filter, wash, dry in an oven at 100°C, and calcine at 550°C for 4h.

[0044] Catalyst Evaluation: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 0.3 MPa and 300°C. The reaction solution was a 10% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 36%, and the selectivity of methyl methacrylate was 53%.

[0045] Example 4

[0046] Catalyst preparation 4: Dissolve 6g of nickel nitrate hexahydrate in 100mL of water, add 1g of CTAB, and after dissolution, add 8g of MgO while stirring. Stir at room temperature for 3h, add 7.5g of TEOS dropwise, stir overnight at 75°C, filter, wash, dry in an oven at 100°C, and calcine at 550°C for 4h.

[0047] Catalyst Evaluation: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 0.3 MPa and 300°C. The reaction solution was a 10% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 32%, and the selectivity of methyl methacrylate was 54%.

[0048] Example 5

[0049] Catalyst preparation 5: Dissolve 5.5g of copper nitrate in 100mL of water, add 1g of CTAB, and after dissolution, add 8g of MgO while stirring. Stir at room temperature for 3h, add 7.5g of TEOS dropwise, stir overnight at 75°C, filter, wash, dry in an oven at 100°C, and calcine at 550°C for 4h.

[0050] Catalyst Evaluation: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 0.3 MPa and 300°C. The reaction solution was a 10% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 65%, and the selectivity of methyl methacrylate was 43%.

[0051] Example 6

[0052] Catalyst preparation 6: Dissolve 5.5g copper nitrate, 6g ferric nitrate hexahydrate, and 6g nickel nitrate hexahydrate in 200mL of water, add 1g CTAB, and after dissolution, add 8g MgO while stirring. Stir at room temperature for 3h, add 7.5g TEOS dropwise, stir overnight at 75°C, filter, wash, dry in an oven at 100°C, and calcine at 550°C for 4h.

[0053] Catalyst Evaluation: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 0.3 MPa and 300°C. The reaction solution was a 10% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 58%, and the selectivity of methyl methacrylate was 46%.

[0054] Example 7

[0055] Catalyst preparation 7: Dissolve 5.5g copper nitrate, 6g ferric nitrate hexahydrate, and 6g nickel nitrate hexahydrate in 200mL of water, add 1g CTAB, and after dissolution, add 8g MgO while stirring. Stir at room temperature for 3h, add 7.5g TEOS dropwise, stir overnight at 75°C, and hydrothermally freeze in a crystallization vessel at 180°C for 24h. Filter, wash, dry in an oven at 100°C, and calcine at 550°C for 4h.

[0056] Catalyst Evaluation: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 0.3 MPa and 300°C. The reaction solution was a 10% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 60%, and the selectivity of methyl methacrylate was 52%.

[0057] Example 8

[0058] Catalyst preparation 8: Dissolve 6g of chromium chloride in 100mL of water, add 1g of CTAB, and after dissolution, add 8g of MgO while stirring. Stir at room temperature for 3h, add 7.5g of TEOS dropwise, stir overnight at 75°C, filter, wash, dry in an oven at 100°C, and calcine at 550°C for 4h.

[0059] Catalyst Evaluation: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 0.3 MPa and 300°C. The reaction solution was a 10% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 36%, and the selectivity of methyl methacrylate was 60%.

[0060] Example 9

[0061] Catalyst preparation 9: Dissolve 6g of cesium nitrate in 100mL of water, add 1g of CTAB, and after dissolution, add 8g of MgO while stirring. Stir at room temperature for 3h, add 7.5g of TEOS dropwise, stir overnight at 75°C, filter, wash, dry in an oven at 100°C, and calcine at 550°C for 4h.

[0062] Catalyst Evaluation: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 0.3 MPa and 300°C. The reaction solution was a methanol solution of 35% methyl acetate, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 36%, and the selectivity of methyl methacrylate was 70%.

[0063] Example 10

[0064] Catalyst preparation 10: Dissolve potassium hydroxide in water (1.0 mol / L), add 1 g CTAB, and after dissolution, add 34 g Mg(NO3)2·6H2O and 8 g HZSM-5 while stirring. Add 7.5 g TEOS dropwise, stir overnight at 75 degrees Celsius, filter, wash, dry in an oven at 100 degrees Celsius, and calcine at 550 degrees Celsius for 4 hours.

[0065] Catalyst Evaluation 1: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 0.3 MPa and 300°C. The reaction solution was a 10% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 60%, and the selectivity of methyl methacrylate was 85%.

[0066] Catalyst Evaluation 2: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 0.3 MPa and 350°C. The reaction solution was a 10% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 72%, and the selectivity of methyl methacrylate was 70%.

[0067] Catalyst Evaluation 3: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of a 20-60 mesh catalyst sample was sieved into a fixed-bed reaction tube and reacted at 1.0 MPa and 350°C. The reaction solution was a 10% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 76%, and the selectivity of methyl methacrylate was 78%.

[0068] Catalyst Evaluation 4: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 1.0 MPa and 350°C. The reaction solution was a methanol solution of 35% methyl acetate, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 52%, and the selectivity of methyl methacrylate was 73%.

[0069] Example 11

[0070] Catalyst preparation 11: Sodium hydroxide was dissolved in water (1.0 mol / L), 1 g CTAB was added, and after dissolution, 34 g Mg(NO3)2·6H2O, 8 g HZSM-5, 3 g ZnO were added while stirring. 7.5 g TEOS was added dropwise, stirred overnight at 75 degrees Celsius, filtered, washed, dried in an oven at 100 degrees Celsius, and calcined at 550 degrees Celsius for 4 hours.

[0071] Catalyst Evaluation: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 1.0 MPa and 350°C. The reaction solution was a 35% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 48%, and the selectivity of methyl methacrylate was 68%.

[0072] Example 12

[0073] Catalyst preparation 12: Dissolve potassium carbonate in water (1.0 mol / L), add 1 g CTAB, and after dissolution, add 34 g Mg(NO3)2·6H2O, 8 g HZSM-5, 5 g 50% manganese nitrate aqueous solution while stirring, add 7.5 g TEOS dropwise, stir overnight at 75 degrees Celsius, filter, wash, dry in an oven at 100 degrees Celsius, and calcine at 550 degrees Celsius for 4 hours.

[0074] Catalyst Evaluation: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 1.0 MPa and 350°C. The reaction solution was a 35% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 50%, and the selectivity of methyl methacrylate was 80%.

[0075] Example 13

[0076] Catalyst preparation 13: Dissolve potassium hydroxide in water (1.0 mol / L), add 1 g CTAB, and after dissolution, add 34 g Mg(NO3)2·6H2O, 8 g SBA-15, 6 g copper nitrate while stirring, add 7.5 g TEOS dropwise, stir overnight at 75 degrees Celsius, filter, wash, dry in an oven at 100 degrees Celsius, and calcine at 550 degrees Celsius for 4 hours.

[0077] Catalyst Evaluation: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 1.0 MPa and 350°C. The reaction solution was a 35% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 60%, and the selectivity of methyl methacrylate was 82%.

[0078] Example 14

[0079] Catalyst preparation 14: Dissolve potassium chloride in water (1.0 mol / L), add 1 g CTAB, and after dissolution, add 8 g MgO and 8 g HZSM-5 while stirring. Add 7.5 g TEOS dropwise, stir overnight at 75 degrees Celsius, filter, wash, dry in an oven at 100 degrees Celsius, and calcine at 550 degrees Celsius for 4 hours.

[0080] Catalyst Evaluation: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 1.0 MPa and 350°C. The reaction solution was a 35% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 32%, and the selectivity of methyl methacrylate was 70%.

[0081] Example 15: Using MCM-41 molecular sieve as a support

[0082] Catalyst preparation 15: Dissolve potassium hydroxide in water (1.0 mol / L), add 1 g CTAB, and after dissolution, add 34 g Mg(NO3)2·6H2O, 8 g MCM-41, 5 g 50% manganese nitrate aqueous solution while stirring, add 7.5 g TEOS dropwise, stir overnight at 75 degrees Celsius, filter, wash, dry in an oven at 100 degrees Celsius, and calcine at 550 degrees Celsius for 4 hours.

[0083] Catalyst Evaluation: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 0.3 MPa and 300°C. The reaction solution was a 10% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 62%, and the selectivity of methyl methacrylate was 83%.

[0084] Comparative Example 1: No Mg added

[0085] Catalyst preparation 16: Dissolve potassium hydroxide in water (1.0 mol / L), add 1 g CTAB, and after dissolution, add 8 g HZSM-5 and 7 g zinc nitrate solution while stirring. Add 7.5 g TEOS dropwise, stir overnight at 75 degrees Celsius, filter, wash, dry in an oven at 100 degrees Celsius, and calcine at 550 degrees Celsius for 4 hours.

[0086] Catalyst Evaluation: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of catalyst (20-60 mesh) was sieved into a fixed-bed reaction tube and reacted at 0.3 MPa and 300°C. The reaction solution was a 10% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 13%, and the selectivity of methyl methacrylate was 8%.

[0087] Comparative Example 2: Without TEOS

[0088] Catalyst preparation 17: Dissolve potassium hydroxide in water (1.0 mol / L), add 1 g CTAB, and after dissolution, add 34 g Mg(NO3)2·6H2O, 8 g HZSM-5, and 7 g zinc nitrate solution while stirring. Stir overnight at 75 degrees Celsius, filter, wash, dry in an oven at 100 degrees Celsius, and calcine at 550 degrees Celsius for 4 hours.

[0089] Catalyst Evaluation 3: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of a 20-60 mesh catalyst sample was sieved into a fixed-bed reaction tube and reacted at 0.3 MPa and 300°C. The reaction solution was a 10% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 28%, and the selectivity of methyl methacrylate was 41%.

[0090] Comparative Example 3: Without X-metal precursor

[0091] Catalyst preparation 18: Dissolve potassium hydroxide in water (1.0 mol / L), add 1 g CTAB, and after dissolution, add 34 g Mg(NO3)2·6H2O and 8 g HZSM-5 while stirring. Add 7.5 g TEOS dropwise, stir overnight at 75 degrees Celsius, filter, wash, dry in an oven at 100 degrees Celsius, and calcine at 550 degrees Celsius for 4 hours.

[0092] Catalyst Evaluation 4: The catalytic performance of the catalyst was evaluated in a fixed-bed reactor. Approximately 10 mL of a 20-60 mesh catalyst sample was sieved into a fixed-bed reaction tube and reacted at 0.3 MPa and 300°C. The reaction solution was a 10% methyl acetate methanol solution, and the mass hourly space velocity (WHSV) was 1.2 h⁻¹. -1 Samples were taken every 3 hours for chromatographic analysis. The conversion rate of methyl acetate was 35%, and the selectivity of methyl methacrylate was 76%.

[0093] As can be seen from the comparison of the above examples, without the addition of Mg, TEOS (Si source) or X metal, the conversion rate of methyl acetate and the selectivity of methyl methacrylate both decreased significantly, indicating that these active substances have an important influence on the catalyst preparation of methyl methacrylate.

[0094] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for producing methyl methacrylate in one step from methanol and methyl acetate, wherein the method employs a catalyst for the preparation of methyl methacrylate for catalytic reaction, and the method is carried out as follows: The catalyst for the preparation of methyl methacrylate was tableted at 8-20 MPa, and 20-60 mesh 3-12 mL catalyst was screened and packed into a fixed-bed reactor. The reactant was a methanol solution of methyl acetate (5%-60% by mass). The reactant was passed through the fixed-bed reactor under a carrier gas. The reaction pressure was 0.1-2.0 MPa, and the reaction temperature was 200-400 °C. o C, The mass hourly space velocity (HSV) of the reaction solution feed is 0.1-10 h⁻¹. -1 ; The catalyst used to prepare methyl methacrylate is represented by the following chemical formula 1: Mg a Si b X c O d Chemical formula 1 In chemical formula 1, a, b, and c represent the weight ratios of the active components Mg, Si, and X, respectively, and d represents the stoichiometric ratio of O atoms. Based on the mass of magnesium oxide (MgO), the mass fraction of Si is 20-500%, and the mass fraction of X is 0.1-100%. X is selected from one or more of Mn, Fe, Ni, Co, Cu, Cr, Zn, Cs, Mo, W, Cd, P, Al, Na, and K.

2. The method for producing methyl methacrylate in one step from methanol and methyl acetate according to claim 1, characterized in that, In the catalyst used to prepare methyl methacrylate, based on the mass of magnesium oxide (MgO), the mass fraction of active component Si is 100-300%, and the mass fraction of active component X is 1-10%.

3. The method for producing methyl methacrylate in one step from methanol and methyl acetate according to claim 1, characterized in that, In the catalyst used to prepare methyl methacrylate, X is selected from one or more of Mn, Fe, Ni, Cu, Cr, Zn, Cs, Na, and K.

4. The method for producing methyl methacrylate in one step from methanol and methyl acetate according to claim 1, characterized in that, The catalyst contains a support selected from molecular sieves such as HZSM-5, SBA-15, and MCM-41; based on the mass of magnesium oxide (MgO), the mass fraction of the molecular sieve is 50-200%.

5. The method for producing methyl methacrylate in one step from methanol and methyl acetate according to claim 1, characterized in that, The carrier gas is selected from nitrogen, and the carrier gas flow rate is 0.1-100 mL / min; the fixed bed reactor is a one-stage or two-stage reactor.

6. The method for producing methyl methacrylate from methanol and methyl acetate in one step according to claim 1, characterized in that, The catalyst consists of 10-100 mesh particles with a filling volume between 1 mL and 15 mL, ensuring it is within the temperature control zone of the fixed-bed reactor.