Catalyst for one-step synthesis of methyl methacrylate from methylal and methyl propionate and application of catalyst
By designing a bifunctional catalyst with acidic and basic active centers, the problems of low production efficiency and poor selectivity of methyl methacrylate in the existing technology have been solved, realizing an efficient and green one-step synthesis method for methyl methacrylate, and improving the selectivity and yield of MMA.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTHWEST RES & DESIGN INST OF CHEM IND
- Filing Date
- 2025-12-18
- Publication Date
- 2026-04-10
AI Technical Summary
Existing technologies for the production of methyl methacrylate (MMA) suffer from problems such as low raw material conversion rates, rapid decline in catalyst selectivity over time, and difficulties in product separation. In particular, the development of aldol condensation catalysts in the two-step ethylene process makes it difficult to improve MMA production efficiency and reaction selectivity.
A bifunctional catalyst containing both acidic and basic active centers was designed and prepared by co-precipitation or impregnation methods. It is used for the one-step synthesis of methyl methacrylate from methyl acetal and methyl propionate, realizing the aldol condensation reaction of formaldehyde and methyl propionate. The reaction efficiency is improved by in-situ hydrolysis, avoiding the reduction in selectivity and yield caused by the use of concentrated formaldehyde.
The synthesis of methyl methacrylate with high selectivity and high yield was achieved, with 100% atom utilization, reducing side reactions and improving production efficiency and product quality.
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of catalysts, and particularly relates to a catalyst for one-step synthesis of methyl methacrylate from methylal and methyl propionate and application thereof. BACKGROUND
[0002] Methyl methacrylate (MMA) is an important basic chemical raw material, and its downstream application demands, such as polymethyl methacrylate (PMMA), polyvinyl chloride auxiliary (ACR), methyl methacrylate-styrene-butadiene copolymer (MBS), etc.
[0003] With the increasingly wide downstream applications, the demand for methyl methacrylate (MMA) has also been growing continuously. At present, the production methods of methyl methacrylate mainly include ACH method, C4 method and ethylene two-step method. Among them, the ACH method uses extremely toxic hydrocyanic acid as raw material, produces a large amount of ammonium bisulfate in the production process, and has great safety and environmental protection pressure; the C4 method has a long synthesis route, low total MMA yield, high raw material cost and poor economy; the ethylene two-step method has the advantages of green and pollution-free raw materials, low production and maintenance cost, etc., and is the current research hotspot. The difficulty of the ethylene two-step method for producing MMA lies in the development of the second-step aldol condensation catalyst. The existing technology has low raw material conversion rate, and uses concentrated formaldehyde as the formaldehyde source, which inevitably faces problems such as rapid decline of catalyst selectivity with time, large fluctuation of product concentration and difficult product separation.
[0004] Therefore, it is urgent to develop a new catalyst which can improve the production efficiency of MMA and the reaction selectivity and stability. SUMMARY
[0005] The purpose of the present application is to provide a preparation method of a catalyst for one-step synthesis of methyl methacrylate from methylal and methyl propionate in view of the problems in the prior art. The present application builds a new system for one-step synthesis of MMA from methylal and methyl propionate by reasonably designing the components and structure of the catalyst. The system includes two processes of hydrolysis of methylal to generate formaldehyde and aldol condensation of formaldehyde and methyl propionate to generate MMA, and the water generated by the aldol condensation participates in the hydrolysis of methylal in situ, truly realizing a new green chemical synthesis path with an atomic utilization rate of 100 %. The effective balance of the hydrolysis of methylal and the aldol condensation reaction can improve the reaction efficiency of the aldol condensation, and at the same time, can avoid the problems of reduction of MMA selectivity and yield caused by the use of concentrated formaldehyde and the generation of water to the greatest extent.
[0006] The catalyst prepared by the method of the present application can be simultaneously applied to the hydrolysis of methylal and the aldol condensation to prepare MMA, and can effectively improve the product yield and selectivity.
[0007] In order to achieve the above application purposes, the specific technical solutions of the present application are as follows: A catalyst for the one-step synthesis of methyl methacrylate from methyl acetal and methyl propionate is a bifunctional catalyst containing both acidic and basic active centers.
[0008] Furthermore, a catalyst (bifunctional catalyst) for the one-step synthesis of methyl methacrylate from methyl acetal and methyl propionate can be prepared by introducing acidic and basic centers in one step, or by preparing acidic and basic centers separately and then mixing them.
[0009] Furthermore, 1. Bifunctional catalysts formed by the one-step introduction of acidic and basic centers can be prepared by co-precipitation or impregnation methods.
[0010] The bifunctional catalyst prepared by coprecipitation includes the following steps: (1) Weigh a certain amount of alkali metal salts Li, Na, K, Cs or alkaline earth metal salts Be, Mg, Ca, Sr, and dissolve them in a certain amount of deionized water to introduce alkaline centers (as raw material 1). (2) Weigh a certain amount of soluble metal salts aluminum nitrate and zirconium nitrate, and dissolve them in a certain amount of deionized water to introduce acidic centers (as raw material 2). (3) Take a certain amount of deionized water as the base liquid, and take a certain amount of ammonia water, NaOH, Na2CO3 or one of them as precipitant. Add them to the base liquid in advance and dissolve them completely to obtain an alkaline base liquid. (4) The raw materials are added to the alkaline bottom liquid simultaneously in a co-current manner. After aging for a period of time, the raw materials are dried and calcined to obtain a bifunctional catalyst.
[0011] The bifunctional catalyst prepared by the impregnation method includes the following steps: (1) Weigh a certain amount of alkali metal salts Li, Na, K, Cs or alkaline earth metal salts Be, Mg, Ca, Sr and introduce them into the alkaline center. (2) Weigh a certain amount of soluble precursors aluminum nitrate, zirconium nitrate, boric acid, and phosphoric acid and introduce them into the acidic center; (3) Dissolve the basic center in step (1) and the acidic center in step (2) together in a certain amount of deionized water to obtain a mixed solution; (4) Weigh out one or more of alumina, silicon dioxide, zirconium oxide, titanium dioxide or molecular sieve as porous carrier; (5) The mixed solution is uniformly impregnated on a porous support, aged for a period of time, dried and calcined to obtain a bifunctional catalyst.
[0012] 2. The preparation method of the bifunctional catalyst, which is prepared by separately preparing acidic centers and basic centers and then mixing them, is as follows: (1) A certain amount of cation exchange resin, supported solid acid catalyst, oxide composed of one of V / P / Si / Ti / W / Mo or composite oxide composed of multiple ones as acidic center catalyst is weighed; (2) A certain amount of Cs / SiO2 as basic center catalyst is weighed; (3) The acidic center catalyst and the basic center catalyst are uniformly mixed in a mass ratio of 1:0.1-5 to obtain a bifunctional catalyst.
[0013] A catalyst for one-step synthesis of methyl methacrylate from methylal and methyl propionate is prepared by the above method.
[0014] Further, the catalyst is applied to one-step synthesis of methyl methacrylate from methylal and methyl propionate. Meanwhile, a certain proportion of water needs to be added to the reaction raw materials for hydrolysis of methylal to formaldehyde, so as to start the aldol condensation to generate MMA and provide a formaldehyde source for the reaction.
[0015] The bifunctional catalyst is loaded in a fixed bed reactor, and the raw materials methylal, methyl propionate and water are preheated and then sent into the fixed bed for reaction.
[0016] As a preferred mode of the present application, the bifunctional catalyst prepared by the coprecipitation method has an aging time of 1-6 h, is dried at 80-120°C for 8-12 h, and is calcined at 450-600°C for 4-8 h; more preferably, the aging time is 2-4 h.
[0017] As a preferred mode of the present application, the bifunctional catalyst prepared by the impregnation method has an aging time of 1-12 h, is dried at 80-120°C for 8-12 h, and is calcined at 450-600°C for 4-8 h; more preferably, the aging time is 8-12 h.
[0018] As a preferred mode of the present application, the bifunctional catalyst with one-step introduction of acidic center and basic center has the following preferred mode for introduction of the basic center: alkali metal Cs.
[0019] As a preferred mode of the present application, the bifunctional catalyst prepared by mixing the acidic center and the basic center separately has a mass ratio of the acidic center to the basic center of 1:0.1-5, and more preferably 1:1-2.
[0020] As a preferred mode of the present application, the molar ratio of methylal to water is 1:0.01-5, and preferably 1:0.5-1.
[0021] As a preferred mode of the present application, the reaction temperature is 200-400°C, and preferably 320-370°C.
[0022] As a preferred mode of the present application, the reaction pressure is 0.1-3 MPa, preferably 0.1-0.5 MPa.
[0023] Compared with the prior art, the present application has the following advantages: (1) The present application builds a new system for one-step synthesis of MMA from methylal and methyl propionate by rationally designing the components and structure of the catalyst.
[0024] (2) The system in the present application includes two processes of hydrolysis of methylal to generate formaldehyde and aldol condensation of formaldehyde and methyl propionate to generate MMA, and the water generated in the aldol condensation participates in the hydrolysis of methylal in situ, thus realizing a new green chemical synthesis path with an atomic utilization rate of 100%.
[0025] (3) The catalyst in the present application avoids the problem of low selectivity caused by using concentrated formaldehyde as a raw material.
[0026] (4) The catalyst in the present application avoids the problem of reduced MMA yield caused by the generation of water in the traditional aldol condensation reaction.
[0027] (5) The catalyst in the present application further reduces the occurrence of side reactions and improves the product quality by optimizing the reaction conditions such as temperature and pressure. DETAILED DESCRIPTION
[0028] The technical solutions of the present application will be described in detail below with reference to the embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.
[0029] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which the present application belongs.
[0030] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form also includes the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprise" and / or "include" are used in the present description, they indicate the presence of a feature, step, operation, device, component and / or combination thereof.
[0031] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation or be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation to the present application.
[0032] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the term "outlet" should be understood broadly, for example, it can be fixedly connected, or detachably connected, or integrally connected; of course, it can also be mechanically connected, or electrically connected; in addition, it can also be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above-mentioned terms in the present application can be understood according to the specific circumstances.
[0033] In the present application, some conventional operating devices, apparatuses and components are omitted or only described simply.
[0034] In the examples, the specific conditions not specified are carried out according to the conventional conditions or the conditions recommended by the manufacturer.
[0035] In the present application, those not marked are all volume percentage, i.e. v / v%.
[0036] Example 1 7.5 g of cesium acetate was weighed into 200 ml of deionized water as raw material 1; 3 g of aluminum nitrate was weighed into 200 ml of deionized water as raw material 2; 300 ml of deionized water was taken as the base solution, 4.5 g of Na2CO3 was added and completely dissolved in the base solution to obtain an alkaline base solution; raw materials (1 and 2) were simultaneously added to the alkaline base solution in a parallel flow co-precipitation manner, aged for 3 h, dried at 80℃ for 10 h, and calcined at 550℃ for 6 h, denoted as catalyst 1.
[0037] Catalyst test: the catalyst 1 was loaded in a solid bed reactor to carry out the one-step synthesis of methyl methacrylate from methylal and methyl propionate.
[0038] The molar ratio of raw materials methylal, water and methyl propionate was 1:0.5:2.88, the reaction temperature was 320℃, and the reaction pressure was 0.3 MPa. Among them, the MP conversion rate was the amount-of-substance ratio of the MP converted in the reaction process to the amount-of-substance of the MP in the feed; the MMA selectivity was the amount-of-substance ratio of MMA in the product to the amount-of-substance of the methyl propionate converted; the MMA yield was the product of the MP conversion rate and the MMA selectivity.
[0039] The evaluation results are: MMA selectivity is 80%, and MMA yield is 14.8%.
[0040] Example 2 7.5 g of magnesium nitrate was weighed and dissolved in 150 ml of deionized water as raw material 1; 3.9 g of zirconium nitrate was weighed and dissolved in 150 ml of deionized water as raw material 2, 200 ml of deionized water was taken as the base solution, 6 g of NaOH was added and completely dissolved in the base solution to obtain an alkaline base solution; raw materials (1 and 2) were added to the alkaline base solution in a parallel flow co-precipitation manner, aged for 2 h, dried at 80°C for 8 h, and calcined at 550°C for 6 h, recorded as catalyst 2.
[0041] The catalyst 2 test method is the same as example 1, and the test results show that the MMA selectivity is 12% and the MMA yield is 0.7%.
[0042] Example 3 4.29 g of cesium carbonate and 2 g of zirconium nitrate were weighed and dissolved in 88 ml of deionized water to obtain a mixed solution; 20 g of alumina was weighed as a porous carrier; the mixed solution was uniformly impregnated on the porous carrier, aged for 10 h, dried at 100°C for 8 h, and calcined at 500°C for 8 h, recorded as catalyst 3.
[0043] The catalyst test method is the same as example 1, and the test results show that the MMA selectivity is 83% and the MMA yield is 14.9%.
[0044] Example 4 3.55 g of cesium nitrate and 1.8 g of boric acid were weighed and dissolved in 123.2 ml of deionized water to obtain a mixed solution; 28 g of silicon oxide was weighed as a porous carrier; the mixed solution was uniformly impregnated on the porous carrier, aged for 12 h, dried at 110°C for 12 h, and calcined at 500°C for 8 h, recorded as catalyst 4.
[0045] The catalyst 4 test method is basically the same as example 1, except that the molar ratio of raw materials methylal, water and methyl propionate is 1:10:2.88.
[0046] The test results show that the MMA selectivity is 57% and the MMA yield is 2.61%.
[0047] Example 5 5 g of VPO catalyst (prepared according to the literature DOI: 10.1016 / j.jcat.2014.04.005) was weighed as an acidic center, and 5 g of Cs / SiO2 catalyst (prepared according to the literature DOI: 10.3969 / j.issn.1001-9219.2020.05.001) was weighed as a basic center, and they were mixed uniformly, recorded as catalyst 5.
[0048] The testing method of catalyst 5 is the same as that of example 1, and the test shows that the MMA selectivity is 93% and the MMA yield is 17.7%.
[0049] Example 6 5 g of cation exchange resin (Dowex 50 type catalyst) is weighed as an acidic center, 7 g of Cs / SiO2 catalyst (prepared according to the literature DOI: 10.3969 / j.issn.1001-9219.2020.05.001) is weighed as a basic center, and they are mixed uniformly, denoted as catalyst 6.
[0050] The testing method of catalyst 6 is the same as that of example 1, and the test shows that the MMA selectivity is 88% and the MMA yield is 15.6%.
[0051] Example 7 1 g of supported solid acid catalyst (commercially available) is weighed as an acidic center, and 10 g of Cs / SiO2 catalyst (prepared according to the literature DOI: 10.3969 / j.issn.1001-9219.2020.05.001) is weighed as a basic center, and they are mixed uniformly, denoted as catalyst 7.
[0052] The testing method of catalyst 7 is the same as that of example 1, and the test shows that the MMA selectivity is 72% and the MMA yield is 2.35%.
[0053] According to the catalyst activity test results of the above examples, it can be seen that the preparation method of the bifunctional catalyst, the feeding ratio of methylal and water, etc. have a significant influence on the activity of the catalyst.
[0054] Finally, it should be noted that: the above examples are only the preferred embodiments of the present application for explaining the technical solutions of the present application, but not limiting them, and of course, they are not limiting the patent scope of the present application; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application; that is to say, any modification or polishing without substantial significance in the main design idea and spirit of the present application, and the technical problems solved are still consistent with the present application, and should be included in the protection scope of the present application; in addition, the technical solutions of the present application are directly or indirectly applied to other related technical fields, which are also included in the patent protection scope of the present application.
Claims
1. A catalyst for the one-step synthesis of methyl methacrylate from methyl acetal and methyl propionate, characterized in that: The catalyst is a bifunctional catalyst containing both acidic and basic active centers.
2. The catalyst for the one-step synthesis of methyl methacrylate from methyl acetal and methyl propionate according to claim 1, characterized in that, This bifunctional catalyst is prepared by introducing acidic and basic centers in one step, or by preparing acidic and basic centers separately and then mixing them.
3. The catalyst for the one-step synthesis of methyl methacrylate from methyl acetal and methyl propionate according to claim 2, characterized in that, Bifunctional catalysts, which are formed by the one-step introduction of acidic and basic centers, are prepared by co-precipitation or impregnation methods.
4. The catalyst for the one-step synthesis of methyl methacrylate from methyl acetal and methyl propionate according to claim 3, characterized in that, The bifunctional catalyst prepared by coprecipitation includes the following steps: (1) Weigh a certain amount of alkali metal salts Li, Na, K, Cs or alkaline earth metal salts Be, Mg, Ca, Sr, and dissolve them in a certain amount of deionized water for later use, and introduce them into the alkaline center. (2) Weigh a certain amount of soluble metal salts aluminum nitrate and zirconium nitrate, and dissolve them in a certain amount of deionized water for later use, and introduce them into the acidic center; (3) Take a certain amount of deionized water as the base liquid, and take a certain amount of ammonia water, NaOH, Na2CO3 or one of them as precipitant. Add them to the base liquid in advance and dissolve them completely to obtain an alkaline base liquid. (4) The spare materials in steps (1) and (2) are added to the alkaline bottom liquid in step (3) in a parallel flow manner. After aging for a period of time, the mixture is dried and calcined to obtain a bifunctional catalyst.
5. The catalyst for the one-step synthesis of methyl methacrylate from methyl acetal and methyl propionate according to claim 3, characterized in that, The bifunctional catalyst prepared by the impregnation method includes the following steps: (1) Weigh a certain amount of alkali metal salts Li, Na, K, Cs or alkaline earth metal salts Be, Mg, Ca, Sr and introduce them into the alkaline center. (2) Weigh a certain amount of soluble precursors aluminum nitrate, zirconium nitrate, boric acid, and phosphoric acid and introduce them into the acidic center; (3) Dissolve the basic center in step (1) and the acidic center in step (2) together in a certain amount of deionized water to obtain a mixed solution; (4) Weigh out one or more of alumina, silicon dioxide, zirconium oxide, titanium dioxide or molecular sieve as porous carrier; (5) The mixed solution is uniformly impregnated on a porous support, aged for a period of time, dried and calcined to obtain a bifunctional catalyst.
6. The catalyst for the one-step synthesis of methyl methacrylate from methyl acetal and methyl propionate according to claim 2, characterized in that, The catalyst prepared by separately preparing acidic and basic centers and then mixing them includes the following steps: (1) Weigh a certain amount of cation exchange resin, supported solid acid catalyst, and an oxide or composite oxide composed of one or more of V / P / Si / Ti / W / Mo as an acidic center catalyst. (2) Weigh a certain amount of Cs / SiO2 as the alkaline center catalyst; (3) A bifunctional catalyst is prepared by uniformly mixing acidic central catalyst and basic central catalyst at a mass ratio of 1:0.1~5.
7. The use of a catalyst as described in any one of claims 1-6 in the one-step synthesis of methyl methacrylate from methyl acetal and methyl propionate.
8. The application according to claim 7, characterized in that: Water is added to the reaction raw materials to hydrolyze methyl acetal to formaldehyde, thereby initiating aldol condensation to generate MMA and providing a formaldehyde source for the reaction.
9. The application according to claim 7, characterized in that... The specific steps include: loading the bifunctional catalyst into a fixed-bed reactor, and feeding the preheated raw materials methyl acetal, methyl propionate and water into the fixed bed for reaction.
10. The application according to claim 7, characterized in that: The molar ratio of methyl acetal to water is 1:0.01~5; the reaction temperature is 200~400℃; and the reaction pressure is 0.1~3 MPa.