Catalyst for methyl methacrylate synthesis, method for preparing the same, and use thereof
By preparing AuMaOn/Si10NbOx catalysts and optimizing Au particle size and dispersion, the problem of low conversion rate of existing catalysts was solved, achieving efficient synthesis of methyl methacrylate and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2023-11-27
- Publication Date
- 2026-07-28
AI Technical Summary
Existing catalysts for the oxidative esterification of methacrolein to synthesize methyl methacrylate have low conversion rates and low product yields. Au nanoparticles are also expensive. Therefore, reducing the amount of Au used and improving its dispersibility have become key issues.
Using AuMaOn/Si10NbOx catalysts, the Au particle size was optimized to 1–10 nm to improve dispersibility. Ni, Nb, Co, Fe, Bi and other elements were added as promoters to prepare catalysts with a specific surface area of 20–500 m²/g, a pore volume of 0.1–0.8 cm³/g, and a most probable pore size of 5–50 nm.
Under conditions of lower alcohol-aldehyde ratio, the catalyst conversion and selectivity are significantly improved, the catalyst cost is reduced, and efficient synthesis of methyl methacrylate is achieved.
Smart Images
Figure CN120037907B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of methods for synthesizing methyl methacrylate, and more specifically, to a catalyst for the synthesis of methyl methacrylate, its preparation method, and its application. Background Technology
[0002] Methyl methacrylate (MMA) is an important organic chemical raw material. Its main downstream product, acrylic glass, is an important thermoplastic that was developed relatively early. It has the characteristics of beautiful appearance, excellent light transmission, and chemical stability, and is widely used in industries such as automobiles, construction, sanitary ware, and public works.
[0003] In current industrialized MMA production processes, the traditional ACH process, which uses hydrogen cyanide as a raw material, is highly susceptible to changes in acrylonitrile conditions and generates a large amount of ammonium sulfate as a byproduct, resulting in high treatment costs and consequently higher MMA production costs, thus diminishing its advantages. BASF's technology does not offer significant economic benefits, and Alpha technology is currently in its early stages of industrialization; its technological maturity and overall economic viability require further evaluation.
[0004] Compared with other processes, the direct oxidation method using C4 as a raw material has advantages such as a wide range of raw material sources and good economic efficiency. The traditional three-step method first oxidizes isobutylene to methacrolein, then further oxidizes it to methacrylic acid, and finally esterifies it with methanol to obtain methyl methacrylate. In contrast, the two-step method, which oxidizes and esterifies methacrolein to methacrylic acid in one step, is a major innovation in the production of MMA via the C4 route. It has many advantages such as a shorter reaction route, high atom utilization, good selectivity, mild reaction conditions, and being environmentally friendly.
[0005] Currently, oxide-supported noble metal catalysts are widely used, especially Au-supported catalysts, which have the advantage of high selectivity; however, their catalyst costs are extremely high. For example, Suzuki et al. of Asahi Corporation in Japan supported 1.1 wt% Au nanoparticles on a composite oxide support such as SiO2-Al2O3-MgO, and the cost of their catalyst reached several million yuan per ton.
[0006] Au nanoparticles are highly beneficial for improving the selectivity of this reaction, but they are costly. How to reduce the amount of Au used is a key issue. How to reduce the size of Au particles, improve the dispersibility of Au particles, and find better auxiliaries and carriers to promote the activity of gold nanoparticles are all directions worth exploring. Summary of the Invention
[0007] The technical problem to be solved by the present invention is that the catalyst used in the prior art for the oxidative esterification of methacrolein to synthesize methyl methacrylate has low conversion rate and low product yield. The present invention provides a bifunctional catalyst with high conversion rate and high yield of methyl methacrylate.
[0008] One objective of this invention is to provide a catalyst for the synthesis of methyl methacrylate, comprising an active component and a support, wherein the active component and the support each have the general formula AuM a O n and Si 10 N b O x ,
[0009] Wherein, M is at least one of Ni, Nb, Co, Fe, and Bi, and N is a Group 2 element, preferably at least one of Be, Mg, Ca, Sr, and Ba;
[0010] a=0.001~10; b=0.001~2;
[0011] x and n are values determined by the total valence of the elements other than oxygen in the general formula.
[0012] In the catalyst, the Au content is 0.1 to 0.9 wt%, preferably 0.5 to 0.8 wt%, based on the total mass of the catalyst.
[0013] In the catalyst, the M content is 0.05 to 5 wt%, preferably 0.05 to 2.5 wt%, based on the total mass of the catalyst.
[0014] In the catalyst, the size of the Au particles is 1 to 10 nm, for example, it can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, etc.
[0015] The catalyst has a specific surface area of 20–500 m². 2 / g, preferably 30-100m 2 / g, for example, 20m 2 / g、30m 2 / g, 50m 2 / g、80m 2 / g, 100m 2 / g、200m 2 / g、300m 2 / g、400m 2 / g、500m 2 / g etc.
[0016] The catalyst has a pore volume of 0.1–0.8 cm³. 3 / g, preferably 0.35~0.8cm 3 / g, for example, 0.1cm 3 / g, 0.2cm 3 / g, 0.3cm 3 / g, 0.35cm 3 / g, 0.4cm 3 / g, 0.5cm 3 / g, 0.6cm 3 / g, 0.7cm 3 / g, 0.8cm 3 / g etc.
[0017] The most probable pore size range of the catalyst is 5 to 50 nm, preferably 20 to 50 nm, for example, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc.
[0018] The catalyst of the present invention has the general formula AuM a O n / Si 10 N b O x It can be used in the reaction of oxidative esterification of methacrolein to synthesize methyl methacrylate, where Au is a nanoparticle.
[0019] A second objective of this invention is to provide a method for preparing the catalyst for the synthesis of methyl methacrylate, comprising the following steps:
[0020] (1) Dissolve N salt in water to obtain solution A, then add solution A to silica sol and stir for a period of time, then spray dry to obtain the carrier precursor;
[0021] (2) The obtained carrier precursor is calcined to obtain the carrier;
[0022] (3) Mix gold trichloride or chloroauric acid solution and aqueous solution of M salt to obtain solution B, add it to the carrier, stir for a period of time, wait for the color of solution B to become transparent, filter, wash and dry to obtain catalyst precursor;
[0023] (4) The obtained catalyst precursor is calcined once and then calcined again in a water vapor atmosphere.
[0024] In step (1) of the preparation method:
[0025] The N salt is selected from at least one of the oxygen-containing salts and / or oxygen-containing salt hydrates of Be, Mg, Ca, Sr, and Ba.
[0026] The M salt is selected from at least one of the oxygen-containing salts and / or oxygen-containing salt hydrates of Ni, Nb, Co, Fe, and Bi.
[0027] In step (2) of the preparation method:
[0028] The roasting temperature is 450–700℃, and the roasting time is 2–100 hours.
[0029] Preferably, the roasting temperature is 500–650°C and the roasting time is 3–24 hours.
[0030] In step (4) of the preparation method:
[0031] In a single firing, the temperature is 200–600℃, and the firing time is 2–200 hours. Preferably, the firing temperature is 250–350℃, and the firing time is 3–24 hours.
[0032] During a single roasting process, the heating rate can be 0.5–5 °C / min, preferably 2–4 °C / min.
[0033] During the first firing, the atmosphere is either inert or air.
[0034] During the secondary roasting, the atmosphere is an inert atmosphere or air containing water vapor, wherein the water vapor volume content is 0.5% to 20%, preferably 5% to 15%, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc.
[0035] In the secondary roasting, the processing temperature is 100–800℃, and the processing time is 0.5–200 hours. Preferably, the processing temperature is 300–550℃, and the processing time is 1–72 hours.
[0036] A third objective of this invention is to provide the application of the catalyst for the synthesis of methyl methacrylate or the catalyst prepared by the preparation method in the synthesis of methyl methacrylate.
[0037] The application includes reacting methacrolein, methanol, and an O2-containing atmosphere in the presence of the catalyst.
[0038] According to one embodiment of the invention, the application includes reacting the catalyst with methacrolein, methanol and air in a batch reactor.
[0039] In the above-described reaction, preferably, the reaction temperature is 60–90°C, the partial pressure of O2 is 0.02–3 MPa, the molar ratio of methanol to methacrolein is 10–40, and the reaction time is 0.5–24 h.
[0040] More preferably, in the above-described reaction, the reaction temperature is 60–80°C, the partial pressure of O2 is 0.05–2.5 MPa, the molar ratio of methanol to methacrolein is 15–35, and the reaction time is 1–20 h.
[0041] Compared with the prior art, the present invention has the following advantages:
[0042] The catalyst prepared by the unique method of this invention significantly reduces the size of Au particles and improves their dispersibility. Furthermore, the addition of additives further enhances the catalyst's activity. When used in the synthesis of methyl methacrylate, this catalyst can improve conversion and selectivity even at a low alcohol-aldehyde ratio, achieving excellent technical results. Attached Figure Description
[0043] Figure 1 Electron micrograph of the catalyst prepared from the support without steam treatment, as shown in Comparative Example 2.
[0044] Figure 2 This is an electron microscope image of the catalyst prepared from the support treated with steam in Example 1.
[0045] from Figure 1 and Figure 2 As can be seen, after steam treatment, a large number of pores appear in the carrier, the Au particles are more evenly dispersed, and the particle size becomes smaller. Detailed Implementation
[0046] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.
[0047] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.
[0048] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.
[0049] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0050] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.
[0051] The catalyst evaluation method used in the following examples is as follows:
[0052] Methacrolein and methanol were added to a batch reactor containing the catalyst to be tested. After heating to the required temperature, a certain amount of air was introduced, and the mixture was analyzed by gas chromatography. During the analysis, the carbon balance was calculated, and data with a carbon balance of 95%–105% were selected as valid data. The reaction conditions were as follows:
[0053] Reactor: Stirred tank reactor, 200ml volume;
[0054] Catalyst loading: 2 grams;
[0055] Reaction temperature: 65℃;
[0056] Reaction time: 4 hours;
[0057] Raw material molar ratio: methanol / methacrylaldehyde = 30;
[0058] Feeding amount: 64g methanol, 4.7g methacrolein.
[0059] Air pressure: 3.5 MPa.
[0060] Example 1:
[0061] (1) Dissolve 40g of strontium nitrate (Sr(NO3)2) in water to obtain solution A, then add solution A to 280.8g of silica sol (SiO2 40wt%), continue stirring for a period of time, and spray dry to obtain the carrier precursor.
[0062] (2) The carrier precursor obtained in step (1) is calcined in air at 550°C for 4 hours to obtain the carrier.
[0063] (3) Mix 100ml of chloroauric acid solution (Au content 0.005g / ml) and 10ml of bismuth nitrate solution (Bi content 0.005g / ml) to obtain mixed salt solution B. Add it to 100g of carrier and stir for a period of time. When the color of solution B becomes transparent, filter and wash it, and dry it in a vacuum oven at 100℃ to obtain the catalyst precursor.
[0064] (4) The obtained catalyst precursor was calcined in air at 300°C for 4 hours, and then calcined again at 350°C for 2 hours in air with a water vapor content of 10% (V / V) to obtain a catalyst for the synthesis of methyl methacrylate.
[0065] The obtained catalyst has an average particle size of 3.1 nm and a specific surface area of 82 m². 2 / g, pore volume 0.67cm 3 / g, with a most probable pore size of 38nm.
[0066] Example 2:
[0067] 10 ml of nickel nitrate (Ni content 0.005 g / ml) was used instead of bismuth nitrate in Example 1, and everything else remained the same.
[0068] In the obtained catalyst, Au has a size of 3.5 nm and a specific surface area of 79 m². 2 / g, pore volume 0.64cm 3 / g, with a most probable pore size of 39nm.
[0069] Example 3:
[0070] 10 ml of niobium tartrate (Nb content of 0.005 g / ml) was used to replace bismuth nitrate in Example 1, and everything else remained the same.
[0071] In the obtained catalyst, Au has a size of 4.2 nm and a specific surface area of 67 m². 2 / g, pore volume 0.67cm 3 / g, with a most probable pore size of 41nm.
[0072] Example 4:
[0073] 10 ml of cobalt nitrate (Co content 0.005 g / ml) was used instead of bismuth nitrate in Example 1, and everything else remained the same.
[0074] The obtained catalyst has an Au size of 2.9 nm and a specific surface area of 84 m². 2 / g, pore volume is 0.71cm 3 / g, with a most probable pore size of 36nm.
[0075] Example 5:
[0076] 10 ml of ferric nitrate (Fe content 0.005 g / ml) was used instead of bismuth nitrate in Example 1, and everything else remained the same.
[0077] In the obtained catalyst, Au has a size of 2.8 nm and a specific surface area of 77 m². 2 / g, pore volume is 0.66cm 3 / g, with a most probable pore size of 37nm.
[0078] Example 6:
[0079] The second calcination was carried out at 350°C in air with a water vapor content of 19.5% (V / V), and the rest was the same as in Example 1.
[0080] In the obtained catalyst, Au has a size of 4.0 nm and a specific surface area of 52 m². 2 / g, pore volume is 0.91cm 3 / g, with a most probable pore size of 49nm.
[0081] Comparative Example 1:
[0082] (1) 280.8g of silica sol (40wt%) was spray-dried to obtain the carrier precursor.
[0083] (2) The carrier precursor obtained in step (1) is calcined in air at 550°C for 4 hours to obtain the carrier.
[0084] (3) 100 ml of chloroauric acid solution (Au content 0.005 g / ml) was added to 100 g of carrier and stirred for a period of time. When the color of solution B turned transparent, it was filtered, washed, and dried in a vacuum oven at 100 °C to obtain the catalyst precursor.
[0085] (4) The obtained precursor was calcined in air at 300°C for 4 hours to obtain a catalyst for the synthesis of methyl methacrylate.
[0086] The obtained catalyst has an Au size of 9.3 nm and a specific surface area of 118 m². 2 / g, pore volume 0.32cm 3 / g, with a most probable pore size of 19nm.
[0087] Comparative Example 2:
[0088] (1) Dissolve 40g of strontium nitrate (Sr(NO3)2) in water to obtain solution A, then add solution A to 280.8g of silica sol (SiO2 40wt%), continue stirring for a period of time, and spray dry to obtain the carrier precursor.
[0089] (2) The carrier precursor obtained in step (1) is calcined in air at 550°C for 4 hours to obtain the carrier.
[0090] (3) Mix 100ml of chloroauric acid solution (Au content 0.005g / ml) and 10ml of bismuth nitrate solution (Bi content 0.005g / ml) to obtain mixed salt solution B. Add it to 100g of carrier and stir for a period of time. When the color of solution B becomes transparent, filter and wash it, and dry it in a vacuum oven at 100℃ to obtain the catalyst precursor.
[0091] (4) The obtained catalyst precursor was calcined in air at 300°C for 4 hours to obtain a catalyst for the synthesis of methyl methacrylate.
[0092] The obtained catalyst has an Au size of 7.1 nm and a specific surface area of 125 m². 2 / g, pore volume is 0.31cm 3 / g, with a most probable pore size of 18nm.
[0093] The obtained catalyst was evaluated and tested, and the results are shown in Table 1 below.
[0094] Table 1
[0095]
[0096] In Table 1, n is a value determined by the total valence of the elements other than oxygen in the general formula.
[0097] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.
[0098] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.
[0099] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.
[0100] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.
Claims
1. A catalyst for the synthesis of methyl methacrylate, comprising an active component and a support, wherein the active component and the support each have the general formula AuM a O n and Si 10 N b O x ,in, M is at least one of Ni, Nb, Co, Fe, and Bi; N is at least one of Be, Mg, Ca, Sr, and Ba; a = 0.001~10; b = 0.001~2; x and n are values determined by the total valence of the elements other than oxygen in the general formula. In the catalyst, the Au size is 0.5~5 nm, and the specific surface area of the catalyst is 30~100 m². 2 / g, the catalyst has a pore volume of 0.35~0.8cm. 3 / g, the most probable pore size of the catalyst is 20~50nm; the catalyst is obtained by calcining the catalyst precursor once and then calcining it again in a water vapor atmosphere.
2. The catalyst for the synthesis of methyl methacrylate according to claim 1, characterized in that... Based on the total mass of the catalyst: Au content is 0.1~0.9wt%; and / or, The M content is 0.05~5wt%.
3. The catalyst for the synthesis of methyl methacrylate according to claim 2, characterized in that: Au content is 20.5~0.8wt%; and / or, The M content is 20.05~2.5wt%.
4. A method for preparing the catalyst according to any one of claims 1 to 3, comprising the following steps: (1) Dissolve N salt in water to obtain solution A, then add solution A to silica sol and stir, and spray dry to obtain the carrier precursor; (2) The obtained carrier precursor is calcined to obtain the carrier; (3) Mix gold trichloride or chloroauric acid solution and aqueous solution of M salt to obtain solution B, add it to the carrier, filter, wash and dry to obtain catalyst precursor; (4) The obtained catalyst precursor is calcined once and then calcined again in a water vapor atmosphere.
5. The preparation method according to claim 4, characterized in that: The N salt is selected from at least one of the oxygen-containing salts and / or oxygen-containing salt hydrates of Be, Mg, Ca, Sr, and Ba; and / or, The M salt is selected from at least one of the oxygen-containing salts and / or oxygen-containing salt hydrates of Ni, Nb, Co, Fe, and Bi.
6. The preparation method according to claim 4, characterized in that... In step (2): The roasting temperature is 450~700℃, and the roasting time is 2~100 hours.
7. The preparation method according to claim 4, characterized in that... In step (4): In a single firing, the temperature is 200~600℃ and the time is 2~200 hours; and / or, In the secondary roasting, the volume content of water vapor is 0.5-20%, the temperature is 100-800℃, and the time is 0.5-200 hours.
8. The use of the catalyst for the synthesis of methyl methacrylate according to any one of claims 1 to 3 and / or the catalyst prepared by the preparation method according to any one of claims 4 to 7 in the synthesis of methyl methacrylate.
9. The application according to claim 8, characterized in that... This includes reacting methacrolein, methanol, and an O2-containing atmosphere in the presence of the catalyst.
10. The application according to claim 9, characterized in that: The reaction temperature is 60~90℃, the partial pressure of O2 is 0.02~3MPa, the molar ratio of methanol to methacrolein is 10~40, and the reaction time is 0.5~24h.