Metal hybrid ionic liquid catalyst based on electron density regulation and control strategy and application thereof

Abstract

The invention discloses a metal hybrid ionic liquid catalyst based on an electron density regulation strategy and application thereof. The metal hybrid ionic liquid catalyst mainly comprises preparation of the metal hybrid ionic liquid catalyst and a catalyst used for aldol condensation reaction of formaldehyde and propionaldehyde to produce methylacrolein. The electron density of the ionic liquid can be regulated and controlled through the hybridization effect of metal ions, and then the catalytic activity and stability are improved. According to the catalyst, the generation frequency of methylacrolein on a unit active site can be improved by 2-52%, the consumption of the catalyst is reduced by 15-57%, and the catalyst has the characteristics of mild reaction conditions and easiness in preparation, and is suitable for large-scale industrial application.

Description

Technical Field

[0001] The present invention relates to a metal hybrid ionic liquid catalyst based on an electron density control strategy, and is applied to the aldol condensation reaction of formaldehyde and propionaldehyde to produce methacrolein. The hybridization of metal ions significantly controls the electron density of the ionic liquid, thereby effectively improving the catalytic activity and stability. The catalyst has the advantages of good catalytic activity, high catalyst stability, mild reaction conditions and simple catalyst preparation process, and belongs to the field of fine chemicals. Background Art

[0002] Methacrolein (MAL) is an important chemical with active chemical properties and conjugated double bonds. It has the characteristics of both olefins and aldehydes. Therefore, it is widely used in the synthesis of key materials in the fields of aerospace, decoration and construction. For example, polymethacrylamide required for rocket shells is usually synthesized from two raw materials, methacrylonitrile and methacrylic acid, which are prepared by cyanation and oxidation reactions of MAL, respectively. MAL can also be synthesized into methyl methacrylate by oxidation and esterification, or by one-step oxidative esterification, and is widely used in the manufacture of organic glass. In addition, methyl allyl alcohol, the reduction product of MAL, is also increasingly concerned in the production of a new generation of water reducers. Therefore, the production of methacrolein has an important impact on downstream chemicals and industrial chains. At present, the main methods for producing MAL include the aldol condensation of formaldehyde and propionaldehyde and the C4 oxidation of isobutylene / tert-butyl alcohol. In contrast, the aldol condensation of formaldehyde and propionaldehyde can effectively overcome the safety hazards and difficulties in selectivity control caused by the high-temperature gas-solid reaction in the C4 oxidation method, so this technology has received more and more attention. CN101316809 discloses a method for producing unsaturated aldehydes, wherein amines and protonic acids or salts thereof having 4 to 20 carbon atoms are used as catalysts to carry out a condensation reaction between two aldehydes. CN101074192A uses diethylamine hydrochloride as a catalyst for the aldol condensation reaction of formaldehyde and propionaldehyde to synthesize MAL. However, the high volatility of diethylamine may cause potential harm to the environment and pose a threat to the safety of operators. At the same time, hydrochloric acid with strong acidity is easy to corrode equipment. CN102659542A discloses a method for preparing MAL by catalyzing the condensation of formaldehyde and propionaldehyde with ionic liquids such as imidazoles and pyridines, US2518416 and US2639295 introduce methods using organic amines and inorganic acids as catalysts, and US6552232B2 discusses a method for synthesizing MAL using inorganic alkali liquid or alkaline ionic liquid as catalyst. However, the above methods generally need to be carried out at relatively high temperatures (100-200°C) and pressures (0.1-5.0MPa), and the reaction time is relatively long and the catalyst loss is large. Therefore, it is particularly important to develop an efficient and stable catalyst that can catalyze the reaction under mild conditions to increase the product generation rate and reduce catalyst loss. Summary of the invention

[0003] Based on the above-mentioned deficiencies of the prior art, the present invention proposes a new metal hybrid ionic liquid catalyst based on an electron density regulation strategy, which can significantly improve the catalytic activity and stability of the preparation of methacrolein by aldol condensation of formaldehyde and propionaldehyde under mild conditions.

[0004] A metal hybrid ionic liquid catalyst based on an electron density regulation strategy and its application, wherein the catalyst preparation method comprises the following steps:

[0005] a) Prepare an ionic liquid aqueous solution. Weigh a certain amount of deionized water and place it in a three-necked flask, add a certain amount of diethanolamine, place the three-necked flask in a low-temperature constant temperature reaction bath and stir it thoroughly. Add a certain amount of organic acid to a constant pressure dropping funnel, slowly drop it into the three-necked flask under vigorous stirring, and continue the reaction for 2 to 4 hours after the addition is completed.

[0006] b) Preparation of metal hybrid ionic liquid catalyst: Weigh a certain mass of ionic liquid aqueous solution and place it in a three-necked flask, and weigh a certain mass of metal salt into a powder feeding funnel, slowly add the metal salt to the ionic liquid aqueous solution under ultrasonic and mechanical stirring, and continue the reaction for 2 to 8 hours.

[0007] The organic acid is one or a combination of acetic acid, propionic acid, hydrochloric acid and sulfuric acid.

[0008] The cations in the metal salt include Li + 、Na + , K + , Cs + , Ba 2+ , Mn 2+ 、Zn 2+ and Y 3+ One or more of the combination; the anion in the metal salt includes Cl - 、NO3 - 、CH3COO - 、SO4 2- PO3 - 、SO3CF3 - and BF4 - One or a combination of the following.

[0009] The molar ratio of the metal salt to the ionic liquid is (0.1-1):1.

[0010] Compared with the existing technology for preparing catalysts, the beneficial effects of the present invention are: the addition of metal ions significantly regulates the electron density of the ionic liquid, improves the catalytic activity and stability, the reaction conditions are mild and the catalyst preparation process is simple. DETAILED DESCRIPTION

[0011] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only a 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 protection scope of the present invention.

[0012] Comparative Example 1

[0013] Weigh 25.5g of deionized water and place it in a three-necked flask, add 8.5g of diethanolamine, place the three-necked flask in a low-temperature constant temperature reaction bath and stir thoroughly. Add 6.0g of propionic acid to the constant pressure dropping funnel, slowly drip it into the three-necked flask under vigorous stirring, and continue to react for 2 to 4 hours after the addition is complete to obtain an ionic liquid catalyst. Accurately weigh 1.60g of the ionic liquid catalyst obtained above, add a mixed solution of 0.52g of formaldehyde aqueous solution and 0.38g of propionaldehyde to the catalyst, and perform a catalytic reaction at 15°C to obtain methacrolein.

[0014] Example 1

[0015] Weigh 10g of ionic liquid diethanolamine propionate aqueous solution and place it in a three-necked flask, weigh 0.66g of lithium acetate and place it in a powder feeding funnel, slowly add the metal salt to the ionic liquid aqueous solution under ultrasonic and mechanical stirring, and continue to react for 4 hours after the addition is completed to obtain a metal hybrid ionic liquid catalyst. Accurately weigh 1.64g of the metal hybrid ionic liquid catalyst obtained above, drop a mixed solution of 0.50g of formaldehyde aqueous solution and 0.37g of propionaldehyde into the catalyst, and perform a catalytic reaction at 15°C to obtain methacrolein.

[0016] Example 2

[0017] Weigh 10g of ionic liquid diethanolamine propionate aqueous solution and place it in a three-necked flask, weigh 0.82g of sodium acetate and place it in a powder feeding funnel, slowly add the metal salt to the ionic liquid aqueous solution under ultrasonic and mechanical stirring, and continue to react for 4 hours after the addition is completed to obtain a metal hybrid ionic liquid catalyst. Accurately weigh 1.65g of the above-obtained metal hybrid ionic liquid catalyst, drop a mixed solution of 0.50g of formaldehyde aqueous solution and 0.37g of propionaldehyde into the catalyst, and perform a catalytic reaction at 15°C to obtain methacrolein.

[0018] Example 3

[0019] Weigh 10g of ionic liquid diethanolamine propionate aqueous solution and place it in a three-necked flask, weigh 0.99g of potassium acetate and place it in a powder feeding funnel, slowly add the metal salt to the ionic liquid aqueous solution under ultrasonic and mechanical stirring, and continue to react for 4 hours after the addition is completed to obtain a metal hybrid ionic liquid catalyst. Accurately weigh 1.66g of the metal hybrid ionic liquid catalyst obtained above, drop a mixed solution of 0.49g of formaldehyde aqueous solution and 0.36g of propionaldehyde into the catalyst, and perform a catalytic reaction at 15°C to obtain methacrolein.

[0020] Example 4

[0021] Weigh 10g of ionic liquid diethanolamine propionate aqueous solution and place it in a three-necked flask, weigh 1.92g of cesium acetate and place it in a powder feeding funnel, slowly add the metal salt to the ionic liquid aqueous solution under ultrasonic and mechanical stirring, and continue to react for 4 hours after the addition is completed to obtain a metal hybrid ionic liquid catalyst. Accurately weigh 1.70g of the metal hybrid ionic liquid catalyst obtained above, drop a mixed solution of 0.46g of formaldehyde aqueous solution and 0.34g of propionaldehyde into the catalyst, and perform a catalytic reaction at 15°C to obtain methacrolein.

[0022] Example 5

[0023] Weigh 10g of ionic liquid diethanolamine propionate aqueous solution and place it in a three-necked flask, weigh 2.55g of barium acetate and place it in a powder feeding funnel, slowly add the metal salt to the ionic liquid aqueous solution under ultrasonic and mechanical stirring, and continue to react for 4 hours after the addition is completed to obtain a metal hybrid ionic liquid catalyst. Accurately weigh 1.73g of the above-obtained metal hybrid ionic liquid catalyst, drop a mixed solution of 0.45g of formaldehyde aqueous solution and 0.33g of propionaldehyde into the catalyst, and perform a catalytic reaction at 15°C to obtain methacrolein.

[0024] Example 6

[0025] Weigh 10g of ionic liquid diethanolamine propionate aqueous solution and place it in a three-necked flask, weigh 2.48g of manganese acetate and place it in a powder feeding funnel, slowly add the metal salt to the ionic liquid aqueous solution under ultrasonic and mechanical stirring, and continue to react for 4 hours after the addition is completed to obtain a metal hybrid ionic liquid catalyst. Accurately weigh 1.73g of the metal hybrid ionic liquid catalyst obtained above, drop a mixed solution of 0.45g of formaldehyde aqueous solution and 0.33g of propionaldehyde into the catalyst, and perform a catalytic reaction at 15°C to obtain methacrolein.

[0026] Example 7

[0027] Weigh 10g of ionic liquid diethanolamine propionate aqueous solution and place it in a three-necked flask, weigh 1.84g of zinc acetate and place it in a powder feeding funnel, slowly add the metal salt to the ionic liquid aqueous solution under ultrasonic and mechanical stirring, and continue to react for 4 hours after the addition is completed to obtain a metal hybrid ionic liquid catalyst. Accurately weigh 1.7g of the metal hybrid ionic liquid catalyst obtained above, drop a mixed solution of 0.47g of formaldehyde aqueous solution and 0.34g of propionaldehyde into the catalyst, and perform a catalytic reaction at 15°C to obtain methacrolein.

[0028] Example 8

[0029] Weigh 10g of ionic liquid diethanolamine propionate aqueous solution and place it in a three-necked flask, weigh 2.66g of yttrium acetate and place it in a powder feeding funnel, slowly add the metal salt to the ionic liquid aqueous solution under ultrasonic and mechanical stirring, and continue to react for 4 hours after the addition is completed to obtain a metal hybrid ionic liquid catalyst. Accurately weigh 1.67g of the metal hybrid ionic liquid catalyst obtained above, drop a mixed solution of 0.43g of formaldehyde aqueous solution and 0.32g of propionaldehyde into the catalyst, and perform a catalytic reaction at 15°C to obtain methacrolein.

[0030] Table 1. Catalyst activity and stability evaluation results

[0031]

[0032] *Measured based on the initial generation rate of methacrolein per unit active site.

[0033] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A metal hybrid ionic liquid catalyst based on an electron density regulation strategy and its application, characterized by: A metal hybrid ionic liquid catalyst is generated in situ by a metal salt and an ionic liquid aqueous solution, and the catalyst is used for the reaction of preparing methacrolein by aldol condensation of formaldehyde and propionaldehyde.

2. The metal hybrid ionic liquid catalyst according to claim 1, characterized in that: The cations in the metal salt include Li + 、Na + , K + , Cs + , Ba 2+ , Mn 2+ 、Zn 2+ and Y 3+ One or more of the combination; the anion in the metal salt includes Cl - 、NO3 - 、CH3COO - 、SO4 2- PO3 - 、SO3CF3 - and BF4 - One or a combination of the following.

3. The metal hybrid ionic liquid catalyst according to claim 1, characterized in that: The molar ratio of the metal salt to the ionic liquid is (0.1-1):

1.

4. The metal hybrid ionic liquid catalyst according to claim 1, characterized in that: The ionic liquid is one or a combination of diethanolamine acetate, diethanolamine propionate, diethanolamine hydrochloride, and diethanolamine sulfate.

5. The metal hybrid ionic liquid catalyst according to claim 1, characterized in that: The preparation steps of the metal hybrid ionic liquid catalyst are: continuously adding the metal salt into the ionic liquid aqueous solution under ultrasonic and mechanical stirring, and continuing the reaction for 2 to 8 hours.

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