Preparation method of catalyst for producing methyl methacrylate and methacrolein and its application

Abstract

This invention discloses a method for preparing a catalyst for the co-production of methyl methacrylate and methacrolein, and its application. The catalyst simultaneously contains two types of catalytic promoters to provide catalytically active sites for the production of methyl methacrylate and methacrolein. When the mass ratio of catalytic promoter to active component is in the range of 0.2-0.45, high selectivity for methyl methacrylate can be achieved; when the mass ratio is in the range of 0.45-0.8, co-production of methyl methacrylate and methacrolein can be achieved. The catalyst of this invention allows for more flexible control of the product distribution of methyl methacrylate and methacrolein, optimizes the overall process economy, has a simple preparation process, and is suitable for large-scale industrial applications.

Description

Technical Field

[0001] This invention relates to a method for preparing a catalyst for the production of methyl methacrylate and co-production of methacrolein, and its application. This invention belongs to the field of chemical catalyst application technology. Background Technology

[0002] Methyl methacrylate (MDMA) is an important chemical raw material widely used in the production of synthetic polymers, coatings, adhesives, and other polymeric materials. As a functional monomer, MDMA not only possesses excellent chemical stability and weather resistance, but its derivatives also exhibit superior mechanical properties and thermal stability in polymeric materials, thus finding wide application in plastics, fibers, and inks. In the coal-based Alpha process, MDMA is prepared by the aldol condensation reaction of methyl propionate and formaldehyde. This process has attracted increasing attention due to its environmental friendliness, high safety, mild reaction conditions, low equipment corrosivity, and low production cost.

[0003] Methacrolein, as an organic synthesis intermediate, can also be used to synthesize a variety of chemicals and materials, such as polymers, fragrances, and pharmaceuticals. Common production methods for methacrolein include the aldol condensation reaction of formaldehyde and propionaldehyde, and the oxidation reaction of isobutylene. In industrial production, the efficient utilization of methacrolein can increase the economic value of the reaction process and improve the overall economic and environmental friendliness of the reaction.

[0004] Previous studies on the reaction of methyl propionate and formaldehyde in coal-based Alpha processes have largely focused on improving the yield and selectivity of methyl methacrylate (e.g., CN111344059A, CN118106003A), while relatively little attention has been paid to the product methacrolein and its effective utilization. However, methacrolein is an important organic intermediate; developing catalysts specifically for its production could not only improve the overall conversion rate of raw materials but also help improve the comprehensive utilization rate of resources and optimize the overall economics of the process, thereby making the entire production process more sustainable and competitive. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a catalyst for the co-production of methyl methacrylate and methacrolein. This catalyst can effectively catalyze the reaction of methyl propionate and formaldehyde to synthesize methyl methacrylate, and in the process, co-produce methacrolein. By precisely controlling the ratio of the catalyst promoter and the active component, the distribution of methyl methacrylate and methacrolein products can be effectively controlled. The synthesis method of the catalyst described in this invention has the advantages of simple process, convenient operation, and high reproducibility, which can meet the needs of large-scale production and shows broad prospects for industrial application.

[0006] This invention provides a method for preparing a catalyst for the co-production of methyl methacrylate and methacrolein, specifically including the following steps:

[0007] (1) Weigh a certain mass of the metal salt of catalyst A, the metal salt of catalyst B and the metal salt of active component M, put them into a beaker, and add deionized water to prepare a salt solution containing the catalyst and the precursor of active component.

[0008] (2) After mixing the salt solution obtained in step (1) evenly, add a certain mass of silica carrier, stir thoroughly, let stand for 6-24 hours, and then dry in an oven at 80-140℃ for 6-12 hours until completely dry.

[0009] (3) The dried catalyst precursor obtained in step (2) is placed in a muffle furnace and calcined at 500-800℃ for 4-6 hours at a heating rate of 1-15℃ / min. After that, it is naturally cooled to room temperature to finally obtain the catalyst.

[0010] In step (1), the catalyst promoter A is one or more of Al or Ga, and the catalyst promoter B is one or more of Ti, Zr, or Hf. The active component M is one or more of Na, K, Rb, or Cs. Preferably, the metal salts of the catalyst promoter and the active component can be selected from at least one of the corresponding element's nitrate, acetate, carbonate, chloride, or hydroxide; the mass percentage content of the catalyst promoters A and B is 1.0-6.0 wt.% (calculated as oxides), and the mass percentage content of the active component M is 5.0-15.0 wt.% (calculated as oxides).

[0011] In step (2), the silica carrier is selected from porous silica spheres with a particle size of 20-40 mesh and a specific surface area of ​​300-500 m². 2 / g, pore size distribution of 2-15nm, pore volume of 0.6-0.8cm³ 3 / g.

[0012] The catalyst described above for the co-production of methyl methacrylate and methacrolein is applied in the reaction of methyl propionate and formaldehyde to produce methyl methacrylate, while simultaneously producing methacrolein. The application conditions are as follows: catalytic evaluation is conducted in a fixed-bed reactor; the catalyst loading is 6 ml; the methyl propionate / formaldehyde ratio is 2:1; the methanol / methyl propionate ratio is 2:1; and the feed liquid hourly space velocity is 0.8 h⁻¹. -1 The reaction temperature is 370℃.

[0013] Compared with existing catalyst preparation techniques, the advantages of this invention are: by modifying two or more types of catalyst promoters, the relative contents of different types of catalyst promoters and active components can be flexibly adjusted, thereby effectively controlling the number and intensity of acid-base active sites in the catalyst. This systematic control can significantly affect the product distribution of the aldol condensation reaction of methyl propionate and formaldehyde, ensuring high selectivity for both methyl methacrylate and methacrolein. Using this method, the raw materials methyl propionate and formaldehyde can be fully converted and utilized, thereby reducing production costs, improving the comprehensive utilization rate of resources, and making the entire production process more economical and competitive. Detailed Implementation

[0014] The following detailed description of the invention, in conjunction with specific embodiments, should not be construed as limiting the scope of the invention to the following embodiments. Various substitutions and modifications made based on ordinary technical knowledge and common practice in the art without departing from the above-described technical concept of the invention should be included within the scope of the invention.

[0015] Example 1: In this example, the content of the catalyst promoter Ga is 4.0 wt.%, the content of the catalyst promoter Zr is 3.5 wt.%, the content of the active component Cs is 10.0 wt.%, and the mass ratio of catalyst promoter to active component is 0.75. The specific preparation method is as follows:

[0016] (1) Weigh 1.78g Ga(NO3)3·9H2O, 1.22g Zr(NO3)4·5H2O and 1.38g CsNO3 and dissolve them in 10mL of deionized water. Stir for 20min and sonicate for 20min to prepare a clear and transparent salt solution.

[0017] (2) Take 10g of 20-40 mesh porous silica carrier and quickly add it to the salt solution prepared in step (1). Stir and mix evenly, then let it stand for 24 hours, and then dry it in an oven at 100℃ for 6 hours until completely dry.

[0018] (3) The dried catalyst precursor obtained in step (2) is placed in a muffle furnace and calcined at 500°C for 6 hours at a heating rate of 10°C / min. Finally, it is cooled to room temperature to obtain the catalyst.

[0019] Example 2: In this example, the content of catalyst promoter Al is 3.0 wt.%, the content of catalyst promoter Zr is 3.5 wt.%, the content of active component Cs is 10.0 wt.%, and the mass ratio of catalyst promoter to active component is 0.65. The specific preparation method is as follows:

[0020] (1) Weigh 2.21g Al(NO3)3·9H2O, 1.22g Zr(NO3)4·5H2O and 1.38g CsNO3 and dissolve them in 10mL of deionized water. Stir for 20min and sonicate for 20min to prepare a clear and transparent salt solution.

[0021] Steps (2) and (3) are the same as those described in Example 1.

[0022] Example 3: In this example, the content of the catalyst promoter Ga is 4.0 wt.%, the content of the catalyst promoter Hf is 2.5 wt.%, the content of the active component Cs is 10.0 wt.%, and the mass ratio of catalyst promoter to active component is 0.65. The specific preparation method is as follows:

[0023] (1) Weigh 1.78g Ga(NO3)3·9H2O, 0.38g HfCl4 and 1.38g CsNO3 and dissolve them in 10mL of deionized water. Stir for 20min and sonicate for 20min to prepare a clear and transparent salt solution.

[0024] Steps (2) and (3) are the same as those described in Example 1.

[0025] Example 4: In this example, the content of catalyst promoter Al is 3.0 wt.%, the content of catalyst promoter Hf is 2.5 wt.%, the content of active component Cs is 10.0 wt.%, and the mass ratio of catalyst promoter to active component is 0.55. The specific preparation method is as follows:

[0026] (1) Weigh 2.21g Al(NO3)3·9H2O, 0.38g HfCl4 and 1.38g CsNO3 and dissolve them in 10mL of deionized water. Stir for 20min and sonicate for 20min to prepare a clear and transparent salt solution.

[0027] Steps (2) and (3) are the same as those described in Example 1.

[0028] Example 5: In this example, the content of the catalyst promoter Ga is 2.0 wt.%, the content of the catalyst promoter Zr is 1.75 wt.%, the content of the active component Cs is 10.0 wt.%, and the mass ratio of catalyst promoter to active component is 0.375. The specific preparation method is as follows:

[0029] (1) Weigh 0.89g Ga(NO3)3·9H2O, 0.61g Zr(NO3)4·5H2O and 1.38g CsNO3 and dissolve them in 10mL of deionized water. Stir for 20min and sonicate for 20min to prepare a clear and transparent salt solution.

[0030] Steps (2) and (3) are the same as those described in Example 1.

[0031] Example 6: In this example, the content of catalyst promoter Al is 1.5 wt.%, the content of catalyst promoter Zr is 1.75 wt.%, the content of active component Cs is 10.0 wt.%, and the mass ratio of catalyst promoter to active component is 0.325. The specific preparation method is as follows:

[0032] (1) Weigh 1.10g Al(NO3)3·9H2O, 0.61g Zr(NO3)4·5H2O and 1.38g CsNO3 and dissolve them in 10mL of deionized water. Stir for 20min and sonicate for 20min to prepare a clear and transparent salt solution.

[0033] Steps (2) and (3) are the same as those described in Example 1.

[0034] Example 7: In this example, the content of the catalyst promoter Ga is 2.0 wt.%, the content of the catalyst promoter Hf is 1.25 wt.%, the content of the active component Cs is 10.0 wt.%, and the mass ratio of catalyst promoter to active component is 0.325. The specific preparation method is as follows:

[0035] (1) Weigh 0.89g Ga(NO3)3·9H2O, 0.19g HfCl4 and 1.38g CsNO3 and dissolve them in 10mL of deionized water. Stir for 20min and sonicate for 20min to prepare a clear and transparent salt solution.

[0036] Steps (2) and (3) are the same as those described in Example 1.

[0037] Example 8: In this example, the content of catalyst promoter Al is 1.5 wt.%, the content of catalyst promoter Hf is 1.25 wt.%, the content of active component Cs is 10.0 wt.%, and the mass ratio of catalyst promoter to active component is 0.275. The specific preparation method is as follows:

[0038] (1) Weigh 1.10g Al / Ga(NO3)3·9H2O, 0.19g HfCl4 and 1.38g CsNO3 and dissolve them in 10mL of deionized water. Stir for 20min and sonicate for 20min to prepare a clear and transparent salt solution.

[0039] Steps (2) and (3) are the same as those described in Example 1.

[0040] Comparative Example 1: In this example, the content of catalyst Al is 3.0 wt.%, and the content of active component Cs is 10.0 wt.%. The specific preparation method is as follows:

[0041] (1) Weigh 2.21g Al(NO3)3·9H2O and 1.38g CsNO3 and dissolve them in 10mL of deionized water. Stir for 20min and sonicate for 20min to prepare a clear and transparent salt solution.

[0042] Steps (2) and (3) are the same as those described in Example 1.

[0043] Comparative Example 2: In this example, the content of the catalyst Zr is 3.5 wt.%, and the content of the active component Cs is 10.0 wt.%. The specific preparation method is as follows:

[0044] (1) Weigh 1.22g Zr(NO3)4·5H2O and 1.38g CsNO3 and dissolve them in 10mL of deionized water. Stir for 20min and sonicate for 20min to prepare a clear and transparent salt solution.

[0045] Steps (2) and (3) are the same as those described in Example 1.

[0046] Application Example: The catalyst's aldol condensation activity test was conducted in a fixed-bed reactor. The catalyst loading was 6 ml, the methyl propionate / formaldehyde ratio was 2:1, the methanol / methyl propionate ratio was 2:1, and the feed liquid hourly space velocity was 0.8 h⁻¹. -1 The reaction temperature was 370℃. The results are shown in Table 1:

[0047] Compared with Examples 5-8, Examples 1-4 have a relatively high ratio of catalyst to active component, which is more conducive to the simultaneous formation of methyl methacrylate and methacrolein, while Examples 5-8 have a relatively low ratio of catalyst to active component, which is more conducive to the formation of methyl methacrylate.

[0048] Compared with Comparative Examples 1-2, Example 2 has both Al and Zr as catalysts, which is more conducive to the simultaneous formation of methyl methacrylate and methacrolein. In contrast, the latter has only one catalyst, which is only conducive to the formation of methyl methacrylate and almost no formation of methacrolein.

[0049] Table 1

[0050]

Claims

1. A method for producing methyl methacrylate and co-producing methacrolein using a catalyst, characterized in that, The catalyst comprises a support, two types of catalyst promoters A and B, and an active component M. Catalyst promoter A is one or more of Al or Ga; catalyst promoter B is one or more of Ti, Zr, or Hf; and active component M is one or more of Na, K, Rb, or Cs. When the mass ratio of catalyst promoters A and B to active component M is in the range of 0.45-0.80, the co-production of methyl methacrylate and methacrolein can be achieved.

2. The method for producing methyl methacrylate and co-producing methacrolein using a catalyst according to claim 1, characterized in that, The catalyst is prepared as follows: Weigh the metal salts of catalyst promoter A, catalyst promoter B and active component M, add deionized water to prepare a solution, add porous silica support, stir thoroughly and evenly, and then let stand and dry; calcine the dried catalyst precursor to obtain the catalyst sample.

3. The method for producing methyl methacrylate and co-producing methacrolein using a catalyst according to claim 2, characterized in that, The metal salt is at least one of the corresponding element's nitrate, acetate, carbonate, chloride, or hydroxide; calculated as oxides, the mass percentage content of the catalyst promoters A and B is 1.0-6.0 wt.%, and the mass percentage content of the active component M is 5.0-15.0 wt.%.

Images