Preparation method and application of catalyst for producing methyl methacrylate and co-producing methylacrolein

Abstract

The invention discloses a preparation method and application of a catalyst for producing methyl methacrylate and co-producing methylacrolein. The catalyst contains two catalytic promoters at the same time so as to provide catalytic active sites for producing methyl methacrylate and methylacrolein. When the mass ratio of the catalytic promoter to the active component is in a range of 0.2-0.45, relatively high methyl methacrylate selectivity can be realized; and when the mass ratio is in a range of 0.45-0.8, co-production of methyl methacrylate and methylacrolein can be realized. According to the catalyst, the product distribution of methyl methacrylate and methylacrolein can be more flexibly regulated and controlled, the economical efficiency of the whole process is optimized, the preparation process is simple, and the catalyst is suitable for large-scale industrial application.

Description

Technical Field

[0001] The present invention relates to a preparation method and application of a catalyst for producing methyl methacrylate and simultaneously co-producing methacrolein, and belongs to the technical field of chemical catalyst application. Background Art

[0002] Methyl methacrylate is an important chemical raw material, widely used in the production of synthetic polymers, coatings, adhesives and other polymer materials. As a functional monomer, methyl methacrylate not only has good chemical stability and weather resistance, but its derivatives also show excellent mechanical properties and thermal stability in polymer materials. Therefore, it has been widely used in the fields of plastics, fibers and inks. In the coal-based Alpha process, methyl propionate and formaldehyde are used to react with aldol to prepare methyl methacrylate. This process has attracted more and more attention due to its advantages such as environmental friendliness, high safety, mild reaction conditions, low corrosion of the equipment and low production cost.

[0003] As an organic synthesis intermediate, methacrolein can also be used to synthesize a variety of chemicals and materials, such as polymers, fragrances and drugs. The general production method of methacrolein includes the aldol condensation reaction of formaldehyde and propionaldehyde and the oxidation reaction of isobutylene. In industrial production, the effective use of methacrolein can add economic value to the reaction process and improve the economy and environmental friendliness of the overall reaction.

[0004] Regarding the reaction of methyl propionate and formaldehyde in the coal-based Alpha process, previous studies have mostly focused on improving the yield and selectivity of methyl methacrylate (such as CN111344059A, CN118106003A, etc.), while relatively less attention has been paid to and effective utilization of the product methacrolein. However, as an important organic intermediate, if a catalyst specifically for its production can be developed, it will not only improve the overall raw material conversion rate, but will also help improve the comprehensive utilization rate of resources and optimize the economic efficiency of the overall process, thereby making the entire production process more sustainable and competitive. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a catalyst for producing methyl methacrylate and methacrolein, wherein the catalyst can effectively catalyze the reaction of methyl propionate and formaldehyde to synthesize methyl methacrylate, and in the process, methacrolein is co-produced. By accurately regulating the ratio of the catalytic promoter and the active component, effective control of the distribution of methyl methacrylate and methacrolein products is achieved. The synthesis method of the catalyst of the present invention has the advantages of simple process, convenient operation and strong repeatability, can meet the needs of large-scale production, and shows broad industrial application prospects.

[0006] The present invention provides a method for preparing a catalyst for producing methyl methacrylate and methacrolein, which specifically comprises the following steps:

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

[0008] (2) After the salt solution obtained in step (1) is mixed evenly, a certain amount of silica carrier is added, and the mixture is stirred evenly, and then allowed to stand for 6-24 hours, and then dried in an oven at 80-140° C. for 6-12 hours until completely dry;

[0009] (3) placing the dried catalyst precursor obtained in step (2) in a muffle furnace, calcining at 500-800° C. for 4-6 h at a heating rate of 1-15° C. / min, and then naturally cooling 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 salt of the catalyst promoter and the active component can be selected from at least one of the nitrate, acetate, carbonate, chloride or hydroxide of the corresponding element; the mass percentage content of the catalyst promoter A and B is 1.0-6.0wt.% (calculated as oxide), and the mass percentage of the active component M is 5.0-15.0wt.% (calculated as oxide).

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

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

[0013] Compared with the existing technology for preparing catalysts, the beneficial effect of the present invention is that by modifying two or more types of catalytic promoters, the relative contents of different types of catalytic promoters and active components can be flexibly adjusted, thereby effectively regulating the number and strength of the acid-base active sites of the catalyst. This systematic regulation can significantly affect the product distribution of the aldol condensation reaction of methyl propionate and formaldehyde, and while ensuring a high selectivity for methyl methacrylate, a high selectivity for methacrolein can also be obtained. By adopting 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 DESCRIPTION

[0014] The present invention is further described in detail below in conjunction with specific implementation examples, but it should not be understood that the subject scope of the present invention is limited to the following implementation examples. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to common technical knowledge and customary means in the field, which should all be included in the scope of the present invention.

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

[0016] (1) Weigh 1.78 g Ga(NO 3 ) 3 9H 2 O, 1.22g Zr(NO 3 ) 4 ·5H 2 O and 1.38 g CsNO 3 Dissolve in 10 mL of deionized water, stir for 20 min, and oscillate and ultrasonicate for 20 min to prepare a clear and transparent salt solution;

[0017] (2) taking 10 g of a 20-40 mesh porous silica carrier, quickly adding it to the salt solution prepared in step (1), stirring and mixing evenly, then standing for 24 hours, and then drying in an oven at 100° C. for 6 hours until completely dry;

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

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

[0020] (1) Weigh 2.21 g Al(NO 3 ) 3 9H 2 O, 1.22 g Zr(NO 3 ) 4 ·5H 2 O and 1.38 g CsNO 3 Dissolve in 10 mL of deionized water, stir for 20 min, and oscillate and ultrasonicate for 20 min to prepare a clear and transparent salt solution;

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

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

[0023] (1) Weigh 1.78 g Ga(NO 3 ) 3 9H 2 O, 0.38 g HfCl 4 and 1.38 g CsNO 3 Dissolve in 10 mL of deionized water, stir for 20 min, and oscillate and ultrasonicate for 20 min to prepare a clear and transparent salt solution;

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

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

[0026] (1) Weigh 2.21 g Al(NO 3 ) 3 9H 2 O, 0.38 g HfCl 4 and 1.38 g CsNO 3 Dissolve in 10 mL of deionized water, stir for 20 min, and oscillate and ultrasonicate for 20 min to prepare a clear and transparent salt solution;

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

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

[0029] (1) Weigh 0.89 g Ga(NO 3 ) 3 9H 2 O, 0.61g Zr(NO 3 ) 4 ·5H 2 O and 1.38 g CsNO 3 Dissolve in 10 mL of deionized water, stir for 20 min, and oscillate and ultrasonicate for 20 min to prepare a clear and transparent salt solution;

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

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

[0032] (1) Weigh 1.10 g Al(NO 3 ) 3 9H 2 O, 0.61g Zr(NO 3 ) 4 ·5H 2 O and 1.38 g CsNO 3 Dissolve in 10 mL of deionized water, stir for 20 min, and oscillate and ultrasonicate for 20 min to prepare a clear and transparent salt solution;

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

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

[0035] (1) Weigh 0.89 g Ga(NO 3 ) 3 9H 2 O, 0.19 g HfCl4 and 1.38 g CsNO 3 Dissolve in 10 mL of deionized water, stir for 20 min, and oscillate and ultrasonicate for 20 min to prepare a clear and transparent salt solution;

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

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

[0038] (1) Weigh 1.10 g Al / Ga(NO 3 ) 3 9H 2 O, 0.19 g HfCl 4 and 1.38 g CsNO 3 Dissolve in 10 mL of deionized water, stir for 20 min, and oscillate and ultrasonicate for 20 min to prepare a clear and transparent salt solution;

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

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

[0041] (1) Weigh 2.21 g Al(NO 3 ) 3 9H 2 O and 1.38 g CsNO 3 Dissolve in 10 mL of deionized water, stir for 20 min, and oscillate and ultrasonicate for 20 min to prepare a clear and transparent salt solution;

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

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

[0044] (1) Weigh 1.22 g Zr(NO 3 ) 4 ·5H 2 O and 1.38 g CsNO 3 Dissolve in 10 mL of deionized water, stir for 20 min, and oscillate and ultrasonicate for 20 min to prepare a clear and transparent salt solution;

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

[0046] Application Example: Catalyst aldol condensation activity test experiment was carried out in a fixed bed reactor, the catalyst loading amount was 6 ml, methyl propionate / formaldehyde was 2:1, methanol / methyl propionate was 2:1: the feed liquid space velocity was 0.8 h -1 , the reaction temperature is 370°C. The results are shown in Table 1:

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

[0048] Compared with Comparative Examples 1-2, Example 2 has both Al and Zr catalyst elements, and is therefore more conducive to the simultaneous production of methyl methacrylate and methacrolein, while the latter has only one catalyst element, which is only conducive to the production of methyl methacrylate and almost no methacrolein.

[0049] Table 1

[0050]

Claims

1. A catalyst for producing methyl methacrylate and methacrolein, characterized in that: The catalyst comprises two types of catalyst promoters to provide catalytic active sites for producing methyl methacrylate and methacrolein.

2. A method for preparing a catalyst for producing methyl methacrylate and methacrolein, characterized in that The method comprises the following steps: weighing a catalyst promoter A, a catalyst promoter B and a metal salt of an active component M, adding deionized water to prepare a solution, adding a porous silica carrier, stirring thoroughly and evenly, and then standing to dry; calcining the dried catalyst precursor to obtain a catalyst sample.

3. The method for preparing a catalyst according to claim 2, characterized in that: The catalyst promoter A is one or more of Al or Ga; 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; the metal salt is at least one of the nitrate, acetate, carbonate, chloride or hydroxide of the corresponding element; the mass percentage content of the catalyst promoters A and B is 1.0-6.0wt.% (calculated as oxide), and the mass percentage of the active component M is 5.0-15.0wt.% (calculated as oxide).

4. Use of the catalyst according to claims 1 and 2, characterized in that When the mass ratio of the catalytic aids A and B to the active component M is in the range of 0.2-0.45, a higher selectivity for methyl methacrylate can be achieved; when the mass ratio of the catalytic aids A and B to the active component M is in the range of 0.45-0.8, co-production of methyl methacrylate and methacrolein can be achieved.

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