Application of high-efficiency, easy-to-recover and low-dosage secondary amine ionic liquid in synthesis of methylacrolein
The catalyzed formaldehyde and propionaldehyde in the batch reactor by secondary amine ion liquid catalyst, which solved the problems of large amount of catalyst, difficulty in separation and recovery, and low catalytic efficiency, and achieved efficient synthesis of methacreal, with significantly improved conversion and yield. And the process conditions are mild.
Patent Information
- Application Number
- CN202411331959.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-24
- Publication Date
- 2024-12-31
AI Technical Summary
In the prior art, the large amount of catalyst is used, difficult to separate and recover, and low catalytic efficiency, resulting in many problems in the methacreal synthesis process.
Secondary amine ionic liquid is used as catalyst, and secondary amine and deionized water are added to the batch reactor, and then slowly add organic acid to prepare secondary amine ionic liquid, and use it to catalyze formaldehyde and propionaldehyde at room temperature. Condensation reaction to achieve efficient synthesis of methacreal.
The conversion rate of propionaldehyde is close to 100%, the yield of methacreal is above 98%, and the reaction conditions are mild, the catalyst is easy to recover, which improves the utilization rate of raw materials and catalytic activity.
Abstract
Description
Technical Field
[0001] The invention relates to the field of organic synthesis, and in particular to application of a high-efficiency, easily recyclable and low-dosage secondary amine ion liquid in the synthesis of methacrolein. Background Art
[0002] Methacrolein (MAL) is a colorless volatile liquid with a strong pungent odor at room temperature. As an organic synthesis intermediate, its downstream products mainly include methacrylic acid (MAA), methyl methacrylate (MMA), polymethyl methacrylate (PMMA), methacrylic alcohol (MAC), methyl allyl polyoxyethylene ether (TPEG), methacrylonitrile (MAN), polymethacrylimide (PMI) and 2-methylallyl diacetate (DMA). It is mainly used in the production of organic glass, a new generation of water reducers, foam plastics, fragrances and pharmaceutical products.
[0003] There are three main ways to synthesize MAL: isobutylene oxidation, isobutane oxidation and formaldehyde-propionaldehyde condensation. The isobutylene oxidation method has problems such as difficult selectivity control, complex reactor, and easy catalyst deactivation. The isobutane oxidation method has problems such as difficult raw material activation and low yield. The formaldehyde-propionaldehyde condensation method to produce MAL has the advantages of simple process route, green environmental protection, mild reaction conditions, wide source of raw materials and high MAL yield, and has good industrial application prospects.
[0004] The invention patent application with publication number CN114524721A adopts an intermittent reactor catalytic process and uses morpholine acetate to catalyze formaldehyde and propionaldehyde to synthesize MAL. The reaction process has the problems of being unable to operate continuously, requiring a large amount of catalyst and having a low catalyst utilization rate.
[0005] The invention patent application with publication number CN110882722A adopts an intermittent reactor catalytic process and uses an acid-base composite catalyst to catalyze formaldehyde and propionaldehyde to synthesize MAL. It has high catalytic activity and good stability, but the catalyst consumption is large and recovery is difficult.
[0006] The invention patent application with publication number CN104557490A adopts an intermittent reactor catalytic process and uses morpholine hydrochloride to catalyze formaldehyde and propionaldehyde to synthesize MAL. The reaction process has the problems of strong catalyst acidity, environmental pollution and difficulty in catalyst recovery.
[0007] The invention patent application with publication number CN109438201A designs an ionic liquid (IL-[HDEA]Ac) containing a secondary amine encapsulated in a Pickering emulsion for catalyzing the condensation of formaldehyde and propionaldehyde to prepare MAL. The process achieves product separation and catalyst recovery. The reaction apparatus is simple, but catalyst loss and deactivation are inevitable.
[0008] The invention patent application with publication number CN114733571A adopts a continuous fixed bed catalytic process and uses secondary amine grafted D301 resin (PH-D301) to catalyze formaldehyde and propionaldehyde to synthesize MAL, which achieves effective separation of catalyst and reactants, reduces catalyst dosage, and the catalyst can be recycled. However, there are problems such as low catalyst activity and low product yield.
[0009] Therefore, in order to solve the problems of large catalyst dosage, difficult separation and recovery, low catalytic efficiency, etc. existing in the above patents, it is still necessary to develop an easily recyclable catalyst that can efficiently catalyze the synthesis of MAL. Summary of the invention
[0010] The object of the present invention is to provide a method for efficiently preparing MAL using a secondary amine ionic liquid and applying the secondary amine ionic liquid to catalyze the synthesis of MAL from formaldehyde and propionaldehyde.
[0011] In order to achieve the above object, the present invention provides the following technical solutions:
[0012] The invention provides a method for preparing a catalyst for preparing MAL, comprising the following steps: adding a secondary amine and deionized water into an intermittent reactor respectively, then slowly dropping an organic acid into the intermittent reactor, and obtaining a secondary amine ion liquid after the reaction is completed.
[0013] In a specific embodiment, the organic amine is one or two of dicyclohexylamine, N-methylcyclohexylamine, and N-ethylcyclohexylamine.
[0014] In a specific embodiment, the organic acid is one or two of benzoic acid, propionic acid, and n-butyric acid.
[0015] In a specific embodiment, the molar ratio of the secondary amine to the organic acid may be 1:0.8 to 1:1.2.
[0016] In a specific embodiment, the water content in the secondary amine ion liquid catalyst is 0-30%.
[0017] The invention provides a synthesis process of MAL, comprising the following steps: a certain amount of secondary amine ion liquid is put into a reactor, and a circulating water system is turned on. Subsequently, a certain amount of formaldehyde and propionaldehyde are fully mixed, and slowly dripped into the reactor, and the dripping speed is adjusted to ensure that the temperature of the reaction system is maintained at 20 to 40° C. After the dripping is completed, the temperature is kept constant. After the reaction is completed, the reactants are cooled and allowed to stand, and the upper layer obtained is an oil phase product, and the lower layer is an aqueous phase catalyst.
[0018] In a specific embodiment, the molar ratio of the reaction raw materials to the catalyst is: the molar ratio of the raw materials formaldehyde and propionaldehyde is 1.0:0.8 to 1:1.4, and the molar ratio of the catalyst to the raw materials is 0.3:1 to 0.5:1.
[0019] In a specific embodiment, the water content of the ionic liquid catalyst is 0-30%.
[0020] It can be seen from the above technical scheme that, compared with the prior art, the beneficial effects of the present invention are as follows: by using the ionic liquid catalyst of the present invention, with formaldehyde and propionaldehyde as raw materials, after condensation reaction, the propionaldehyde conversion rate can be close to 100%, and the MAL yield can reach more than 98%; at the same time, the reaction system is at normal temperature and pressure, and the conditions are mild. DETAILED DESCRIPTION
[0021] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0022] In the following examples, the reaction effect analysis method is as follows: sampling is performed in the reaction system after the reaction, and GC analysis is performed, propionaldehyde conversion rate = (moles of propionaldehyde added - moles of propionaldehyde remaining) / moles of propionaldehyde initially added * 100%; MAL selectivity = moles of MAL generated by the reaction / (moles of propionaldehyde added - moles of propionaldehyde remaining) * 100%.
[0023] Example 1
[0024] Add 8.52 g of N-methylcyclohexylamine and 9.61 g of N-ethylcyclohexylamine to an intermittent reactor, and then slowly drop 9.18 g of benzoic acid and 6.65 g of butyric acid (the molar ratio of N-methylcyclohexylamine, N-ethylcyclohexylamine, benzoic acid and butyric acid is 1:1:1:1) into the intermittent reactor. Before the dropwise addition, add 14.68 g of deionized water to the reaction system, and obtain a secondary amine ionic liquid after the reaction is completed.
[0025] A certain amount of the ionic liquid catalyst prepared above was put into an intermittent reactor, and the circulating water system was turned on to stabilize the temperature at 20° C. Subsequently, a certain amount of 24.51 g of formaldehyde and 17.97 g of propionaldehyde were fully mixed (the molar ratio of formaldehyde to propionaldehyde was 1:1, and the molar ratio of propionaldehyde to the secondary amine acid salt solution was 1:0.5), and slowly dripped into the reactor. After the dripping was completed, the reaction was continued for a certain period of time. After the reaction was completed, the analysis and testing were performed.
[0026] Using isobutyl alcohol as the internal standard, the conversion rate of propionaldehyde was 99.8% and the selectivity of methacrolein was 98.7% after analysis by gas chromatography internal standard method.
[0027] Example 2
[0028] Add 13.65 g of dicyclohexylamine and 8.53 g of N-methylcyclohexylamine to an intermittent reactor, and then slowly drop 9.32 g of benzoic acid and 5.63 g of propionic acid (the molar ratio of N-methylcyclohexylamine, dicyclohexylamine, benzoic acid and propionic acid is 1:1:1:1) into the intermittent reactor; add 15.98 g of deionized water to the reaction system before dropping, and obtain a secondary amine ionic liquid after the reaction is completed.
[0029] A certain amount of the ionic liquid catalyst prepared above was put into an intermittent reactor, and the circulating water system was turned on to stabilize the temperature at 20° C. Subsequently, a certain amount of 24.55 g of formaldehyde and 17.81 g of propionaldehyde were fully mixed (the molar ratio of formaldehyde to propionaldehyde was 1:1, and the molar ratio of propionaldehyde to the secondary amine acid salt solution was 1:0.5), and slowly dripped into the reactor. After the dripping was completed, the reaction was continued for a certain period of time. After the reaction was completed, the analysis and testing were performed.
[0030] Using isobutyl alcohol as the internal standard, the conversion rate of propionaldehyde was 99.9% and the selectivity of methacrolein was 98.5% after analysis by gas chromatography internal standard method.
[0031] Example 3
[0032] 17.18 g of N-methylcyclohexylamine was added to the intermittent reactor, and then 18.62 g of benzoic acid (the molar ratio of N-methylcyclohexylamine to benzoic acid was 1:1) was slowly added dropwise to the intermittent reactor. 15.41 g of deionized water was added to the reaction system before the addition. After the reaction was completed, a secondary amine ionic liquid was obtained.
[0033] A certain amount of the ionic liquid catalyst prepared above was put into an intermittent reactor, and the circulating water system was turned on to stabilize the temperature at 20° C. Subsequently, a certain amount of 24.28 g of formaldehyde and 17.91 g of propionaldehyde were fully mixed (the molar ratio of formaldehyde to propionaldehyde was 1:1, and the molar ratio of propionaldehyde to the secondary amine acid salt solution was 1:0.5), and slowly dripped into the reactor. After the dripping was completed, the reaction was continued for a certain period of time. After the reaction was completed, the analysis and testing were performed.
[0034] Using isobutyl alcohol as the internal standard, the conversion rate of propionaldehyde was 99.7% and the selectivity of methacrolein was 98.9% after analysis by gas chromatography internal standard method.
[0035] Example 4
[0036] 10.15 g of N-methylcyclohexylamine was added to an intermittent reactor, and then 9.12 g of benzoic acid (the molar ratio of N-methylcyclohexylamine to benzoic acid was 1:1) was slowly added dropwise to the intermittent reactor. 15.41 g of deionized water was added to the reaction system before the addition. After the reaction was completed, a secondary amine ionic liquid was obtained.
[0037] A certain amount of the ionic liquid catalyst prepared above was put into an intermittent reactor, and the circulating water system was turned on to stabilize the temperature at 20° C. Subsequently, a certain amount of 23.82 g of formaldehyde and 17.60 g of propionaldehyde were fully mixed (the molar ratio of formaldehyde to propionaldehyde was 1:1, and the molar ratio of propionaldehyde to the secondary amine acid salt solution was 1:0.3), and slowly dripped into the reactor. After the dripping was completed, the reaction was continued for a certain period of time. After the reaction was completed, the analysis and testing were performed.
[0038] Using isobutyl alcohol as the internal standard, the conversion rate of propionaldehyde was 99.2% and the selectivity of methacrolein was 99.1% after analysis by gas chromatography internal standard method.
[0039] Example 5
[0040] 16.86 g of N-methylcyclohexylamine was added to an intermittent reactor, and then 18.24 g of benzoic acid (the molar ratio of N-methylcyclohexylamine to benzoic acid was 1:1) was slowly added dropwise to the intermittent reactor. 8.84 g of deionized water was added to the reaction system before the addition. After the reaction was completed, a secondary amine ionic liquid was obtained.
[0041] A certain amount of the ionic liquid catalyst prepared above was put into an intermittent reactor, and the circulating water system was turned on to stabilize the temperature at 20° C. Subsequently, a certain amount of 23.37 g of formaldehyde and 17.83 g of propionaldehyde were fully mixed (the molar ratio of formaldehyde to propionaldehyde was 1:1, and the molar ratio of propionaldehyde to the secondary amine acid salt solution was 1:0.3), and slowly dripped into the reactor. After the dripping was completed, the reaction was continued for a certain period of time. After the reaction was completed, the analysis and testing were performed.
[0042] Using isobutyl alcohol as the internal standard, the conversion rate of propionaldehyde was 99.8% and the selectivity of methacrolein was 99.3% after analysis by gas chromatography internal standard method.
[0043] Example 6
[0044] 16.81 g of N-methylcyclohexylamine was added to an intermittent reactor, and then 18.11 g of benzoic acid (the molar ratio of N-methylcyclohexylamine to benzoic acid was 1:1) was slowly added dropwise to the intermittent reactor. 14.75 g of deionized water was added to the reaction system before the addition. After the reaction was completed, a secondary amine ionic liquid was obtained.
[0045] A certain amount of the ionic liquid catalyst prepared above was put into an intermittent reactor, and the circulating water system was turned on to stabilize the temperature at 20° C. Subsequently, a certain amount of 23.82 g of formaldehyde and 17.61 g of propionaldehyde were fully mixed (the molar ratio of formaldehyde to propionaldehyde was 1:1, and the molar ratio of propionaldehyde to the secondary amine acid salt solution was 1:0.3), and slowly dripped into the reactor. After the dripping was completed, the reaction was continued for a certain period of time. After the reaction was completed, the analysis and testing were performed.
[0046] Using isobutyl alcohol as the internal standard, the conversion rate of propionaldehyde was 99.9% and the selectivity of methacrolein was 98.8% after analysis by gas chromatography internal standard method.
[0047] Example 7
[0048] 16.97 g of N-methylcyclohexylamine was added to the intermittent reactor, and then 18.11 g of benzoic acid (the molar ratio of N-methylcyclohexylamine to benzoic acid was 1:1) was slowly added dropwise to the intermittent reactor. 15.08 g of deionized water was added to the reaction system before the addition. After the reaction was completed, a secondary amine ionic liquid was obtained.
[0049] A certain amount of the ionic liquid catalyst prepared above was put into an intermittent reactor, and the circulating water system was turned on to stabilize the temperature at 20° C. Subsequently, a certain amount of 23.78 g of formaldehyde and 21.45 g of propionaldehyde were fully mixed (the molar ratio of formaldehyde to propionaldehyde was 1:1, and the molar ratio of propionaldehyde to the secondary amine acid salt solution was 1:0.3), and slowly dripped into the reactor. After the dripping was completed, the reaction was continued for a certain period of time. After the reaction was completed, the analysis and testing were performed.
[0050] Using isobutyl alcohol as the internal standard, the conversion rate of propionaldehyde was 99.9% and the selectivity of methacrolein was 98.9% after analysis by gas chromatography internal standard method.
[0051] Based on Examples 1-7, in the synthesis reaction of methacrolein, the conversion rate and selectivity of the reaction are high, and the utilization rate of raw materials is improved, indicating that the catalytic activity of the catalyst prepared by the present invention is good. It can be seen that the catalyst prepared by the present invention can catalyze the synthesis of methacrolein with high activity.
[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A synthesis process for methacrolein, characterized in that: A secondary amine is reacted with an organic acid to obtain a secondary amine ionic liquid catalyst; formaldehyde and propionaldehyde react under the catalysis of the secondary amine ionic liquid to generate methacrolein. After the reaction is completed, the solution is cooled and allowed to stand to separate into layers, wherein the upper layer is an oil phase product and the lower layer is an aqueous phase catalyst. The catalyst can be recycled after being recovered.
2. The synthesis process of methacrolein according to claim 1, specifically comprising the following steps: (1) adding a secondary amine ionic liquid aqueous solution into an intermittent reaction kettle and maintaining the temperature at 20 to 40° C.; (2) adding the mixed raw material of formaldehyde and propionaldehyde into an intermittent reactor, turning on the condensation reflux, controlling the temperature of the reaction system to 20-40° C. under stirring conditions, and reacting for 5-25 minutes; (3) After the reaction is completed, the solution is cooled and allowed to stand to separate into layers. The upper layer is the oil phase product and the lower layer is the water phase catalyst. After separation, they can be recycled.
3. The synthesis process of methacrolein according to claim 2, characterized in that: The preparation method of the secondary amine ionic liquid is as follows: a secondary amine and deionized water are added into an intermittent reaction kettle respectively, and then an organic acid is slowly added dropwise, and the secondary amine ionic liquid is obtained after the reaction is completed.
4. The synthesis process of methacrolein according to claim 3, characterized in that: The organic amine is one or two of dicyclohexylamine, N-methylcyclohexylamine and N-ethylcyclohexylamine; the organic acid is one or two of benzoic acid, propionic acid and n-butyric acid; the molar ratio of N-methylcyclohexylamine to the organic acid is 1:0.8 to 1:1.2; the mass fraction of water is 0 to 30%; and during the process of dripping the organic acid, the temperature is controlled to be -10 to 0°C.
5. The synthesis process of methacrolein according to claim 2, characterized in that The molar ratio of the raw materials formaldehyde and propionaldehyde is 1.0:0.8-1:1.4, and the molar ratio of the catalyst and the raw materials is 0.3:1-0.5:1.