Zeolite-supported basic amino acid catalysts and their use in the preparation of 5-methyl-3-en-2-hexanone

Abstract

The application belongs to the technical field of 5-methyl-3-en-2-hexanone preparation, and discloses a zeolite-supported basic amino acid catalyst and its application in the preparation of 5-methyl-3-en-2-hexanone. The zeolite-supported basic amino acid catalyst is made of a zeolite molecular sieve and a basic amino acid supported on the zeolite molecular sieve, and the loading amount of the basic amino acid is 10-50 wt% based on the total mass of the catalyst; the zeolite molecular sieve includes an alkali-treated ZSM-5, SBA-15 or Beta zeolite molecular sieve, and the basic amino acid includes one or both of arginine and lysine. The high-stability aldehyde-ketone condensation active site catalyst is formed by strong interaction between the basic amino acid and the surface hydroxyl groups of the molecular sieve, and is applied to the preparation of 5-methyl-3-en-2-hexanone through aldehyde-ketone condensation dehydration, so that the catalytic activity of the amino acid can be fully utilized, the selectivity of the product can be improved, the recovery rate of the catalyst can be improved, and the use amount of the amino acid can be reduced.

Description

Technical Field

[0001] This invention relates to the field of 5-methyl-3-en-2-hexanone preparation technology, and particularly to the application of zeolite-supported basic amino acid catalysts in the preparation of 5-methyl-3-en-2-hexanone. Background Technology

[0002] Methyl isopentyl ketone (MIAK) is a colorless, transparent liquid with strong dissolving power, low volatility, and stable chemical properties. It can be used in high-solids coatings and in the synthesis of organic compounds such as acrylic resins. Currently, the production of methyl isopentyl ketone generally employs a two-step method: first, under acid or base catalysis, aldehydes and ketones undergo condensation and dehydration to produce 5-methyl-3-en-2-hexanone; second, 5-methyl-3-en-2-hexanone is hydrogenated using an olefin-saturated catalyst to form MIAK. The synthesis of 5-methyl-3-en-2-hexanone is considered the key step in the preparation of MIAK.

[0003] Amino acids can be used alone as catalysts to synthesize 5-methyl-3-en-2-hexanone. However, during the reaction, 5-methyl-3-en-2-hexanone undergoes further self-condensation under the action of amino acids, generating macromolecular chemical byproducts such as polymers, leading to a decrease in the selectivity of 5-methyl-3-en-2-hexanone. Secondly, amino acids have poor solubility and low dispersibility in acetone and isobutyraldehyde, resulting in low exposure of amino acid active sites, making it difficult for amino acids to fully exert their catalytic effect. Summary of the Invention

[0004] In view of this, in order to solve the technical problem of low selectivity of aldehyde-ketone condensation products caused by the generation of macromolecular chemical byproducts in the synthesis of 5-methyl-3-en-2-hexanone during the synthesis process of the product itself, this application provides a zeolite-supported basic amino acid catalyst and its application in the preparation of 5-methyl-3-en-2-hexanone.

[0005] To solve the above-mentioned technical problems, this application adopts the following technical solution:

[0006] This application provides a zeolite-supported basic amino acid catalyst, which is made of zeolite molecular sieve and basic amino acids supported on the zeolite molecular sieve. The loading of basic amino acids is 10-50 wt% based on the total mass of the catalyst. The zeolite molecular sieve includes alkali-treated ZSM-5, SBA-15 or Beta zeolite molecular sieve, and the basic amino acid includes one or both of arginine and lysine.

[0007] The preparation method of the zeolite-supported alkaline amino acid catalyst provided in this application includes: immersing a zeolite molecular sieve in an aqueous solution of the alkaline amino acid, stirring and allowing it to stand for soaking, and then drying it, wherein the alkaline amino acid fills the pores of the zeolite molecular sieve to generate a zeolite-supported alkaline amino acid catalyst.

[0008] Furthermore, the stirring time is 1-2 hours, the standing soaking time is 18-24 hours, and the drying temperature is 60-80°C.

[0009] The zeolite-supported alkaline amino acid catalyst described in this application has a specific surface area of ​​300–900 m². 2 / g, pore volume 0.1~1.5cm 3 / g.

[0010] Secondly, this application also provides a method for preparing 5-methyl-3-en-2-hexanone, wherein acetone and isobutyraldehyde undergo a dehydration condensation reaction under the action of the above-mentioned zeolite-supported alkaline amino acid catalyst to generate 5-methyl-3-en-2-hexanone.

[0011] Furthermore, the preparation method of 5-methyl-3-en-2-hexanone includes at least one of the following reaction conditions: reaction pressure of 0.5-5.0 MPa; reaction temperature of 60-150 °C; molar ratio of acetone to isobutyraldehyde of 0.5:1-4:1; and mass ratio of catalyst to isobutyraldehyde of 0.1:1-0.4:1.

[0012] Furthermore, the reaction pressure is 1.0 MPa to 3.0 MPa; the reaction temperature is 70 to 100 °C; the molar ratio of acetone to isobutyraldehyde is 1:1 to 2:1; and the mass ratio of the catalyst to isobutyraldehyde is 0.2:1.

[0013] Furthermore, the zeolite-loaded basic amino acids are recovered and reused after the dehydration condensation reaction by filtration.

[0014] Furthermore, the filtered reaction solution was fractionated to obtain water, acetone, isobutyraldehyde, and the product 5-methyl-3-en-2-hexanone.

[0015] The method for preparing 5-methyl-3-en-2-hexanone provided in this application has the following reaction formula:

[0016]

[0017] This application provides the use of a zeolite-supported basic amino acid catalyst in the preparation of 5-methyl-3-en-2-hexanone. The zeolite-supported basic amino acid catalyst is made from a zeolite molecular sieve and a basic amino acid supported on the zeolite molecular sieve. Compared with the prior art, the technical solution provided in this application has the following beneficial effects:

[0018] The catalyst provided in this application is a zeolite-supported basic amino acid. The basic amino-terminal -NH2 group of the amino acid forms a strong interaction with the abundant hydroxyl groups (-OH) on the molecular sieve surface, enhancing the interaction force between the amino acid and the molecular sieve surface, thus forming a basic amino acid-supported zeolite molecular sieve. The amino and carboxyl groups of the basic amino acid that do not interact with the molecular sieve can act as active sites for aldehyde-ketone condensation, catalyzing the dehydration condensation reaction of acetone and isobutyraldehyde to produce 5-methyl-3-en-2-hexanone. Furthermore, the aldehyde-ketone condensation product 5-methyl-3-en-2-hexanone, confined by the molecular sieve pores, can inhibit further self-condensation reaction of the product, improving the selectivity of 5-methyl-3-en-2-hexanone. This overcomes the defect of producing large molecular chemical byproducts when using amino acids alone.

[0019] Secondly, when using amino acids as catalysts for the condensation and dehydration of aldehydes and ketones, the poor solubility of amino acids in acetone and isobutyraldehyde leads to their aggregation, resulting in insufficient exposure of active sites and hindering the full effectiveness of the catalyst. In contrast, the zeolite-supported basic amino acid catalyst used in this application utilizes the molecular sieve's extensive specific surface area, allowing for high dispersion of basic amino acids on the zeolite surface and exposing more active sites. This enables the catalytic activity of the zeolite-supported basic amino acid catalyst to be fully realized. Furthermore, the catalyst prepared by loading amino acids onto the molecular sieve surface can reduce the amount of amino acids required.

[0020] Finally, using amino acids as a catalyst for the dehydration of aldehydes and ketones condensation presents challenges in recovering the amino acids from the aqueous phase after the reaction, as this process is energy-intensive and difficult. The zeolite-supported basic amino acid catalyst provided in this application allows for direct filtration and recovery of the molecular sieve-supported catalyst from the aqueous phase after the reaction, significantly improving catalyst separation efficiency and reducing energy consumption.

[0021] As can be seen from the above technical solutions, this application discloses for the first time a zeolite-supported basic amino acid catalyst and its application in the catalytic aldehyde-ketone condensation reaction. The basic amino acid and the hydroxyl groups on the surface of the molecular sieve form a catalyst with highly stable aldehyde-ketone condensation active sites through strong interaction. The catalyst is then used to prepare 5-methyl-3-en-2-hexanone by aldehyde-ketone condensation dehydration. This provides a simple and easy method to give full play to the catalytic activity of amino acids, reduce catalyst costs, improve product selectivity and catalyst recovery efficiency. Detailed Implementation

[0022] This invention discloses a zeolite-supported basic amino acid catalyst and its application in the catalytic condensation reaction of aldehydes and ketones. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments, and those skilled in the art can obviously make modifications or appropriate alterations and combinations to the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0023] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments.

[0024] Note: Unless otherwise specified, the conversion rate and selectivity of this application are calculated as follows:

[0025] Acetone molar conversion rate = (moles of acetone in the raw material - moles of acetone in the product) / moles of acetone in the raw material;

[0026] Isobutyraldehyde molar conversion rate = (moles of isobutyraldehyde in the raw material - moles of isobutyraldehyde in the product) / moles of isobutyraldehyde in the raw material;

[0027] Molar selectivity of 5-methyl-3-en-2-hexanone = (moles of 5-methyl-3-en-2-hexanone in the product) / (moles of isobutyraldehyde in the feedstock - moles of isobutyraldehyde in the product).

[0028] Example 1: Treatment and Physicochemical Properties of Zeolite Molecular Sieves

[0029] The physicochemical properties of the zeolite catalyst used in this application are shown in Table 1. The method for treating ZSM-5 with alkali using catalyst B in Table 1 can be any conventional method in the art. This application preferably uses the following method to treat ZSM-5 with alkali:

[0030] Zeolite ZSM-5 was mixed with 0.2 mol / L NaOH solution at a mass ratio of ZSM-5 to NaOH solution of 1:20. After stirring at 70℃ for 2 h, the zeolite was washed with deionized water until neutral and then dried at 100℃. The zeolite was then placed in 1 mol / L NH4Cl solution at a mass ratio of 1:20 and reacted at 80℃ for 4 h. This process was repeated twice. The sample was washed with deionized water 5 times and dried at 100℃. Finally, it was calcined in a muffle furnace at 550℃ for 5 h to obtain zeolite catalyst B, i.e., alkali-treated ZSM-5, as shown in Table 1.

[0031] Table 1 Properties of zeolite catalysts

[0032]

[0033] Example 2: Preparation of 5-methyl-3-en-2-hexanone catalyzed by a basic amino acid-supported zeolite catalyst

[0034] Different basic amino acid-supported zeolite catalysts were prepared by impregnating different masses of arginine with catalysts A, B, and C from Table 1 of Example 1. Conventional preparation methods are acceptable. In this example, the following preferred preparation method was used to prepare the basic amino acid-supported zeolite catalyst:

[0035] 1g of zeolite catalysts A, B, and C from Table 1 of Example 1 were soaked in 0.2g of arginine aqueous solution, stirred for 2h, and allowed to stand for 24h before drying at 60℃ to obtain basic amino acid-supported zeolite catalysts D, E, and F in Table 2; 1g of zeolite catalysts A, B, and C from Table 1 of Example 1 were soaked in 0.4g of arginine aqueous solution, stirred for 2h, and allowed to stand for 24h before drying at 60℃ to obtain basic amino acid-supported zeolite catalysts D1, E1, and F1 in Table 2.

[0036] Acetone and isobutyraldehyde underwent a dehydration condensation reaction under the action of basic amino acid-supported zeolite catalysts D, E, F, D1, E1 and F1. After the dehydration condensation reaction, the zeolite-supported basic amino acids were recovered by filtration and reused. The filtered reaction solution was fractionated to separate acetone, isobutyraldehyde, water and the product 5-methyl-3-en-2-hexanone. The reaction conditions and results are shown in Table 2.

[0037] Table 2. Catalytic reaction conditions and results of alkaline amino acid-supported zeolite catalyst-based reaction.

[0038]

[0039]

[0040] Comparative Example 1: Preparation of 5-methyl-3-en-2-hexanone from amino acid-catalyzed aldehyde-ketone condensation

[0041] In this comparative example, the amino acids in Table 3 were used to catalyze the condensation of aldehydes and ketones to prepare 5-methyl-3-en-2-hexanone. Acetone and isobutyraldehyde underwent a dehydration condensation reaction. After the dehydration condensation reaction, the reaction solution was fractionated to obtain the product 5-methyl-3-en-2-hexanone. The reaction conditions, product selectivity, and reactant conversion rate are shown in Table 3.

[0042] Table 3. Amino acid catalysts, catalytic reaction conditions, and results.

[0043]

[0044] This application uses the basic amino acid-supported zeolite catalyst provided in Example 2 to catalyze the dehydration condensation reaction of acetone and isobutyraldehyde to prepare 5-methyl-3-en-2-hexanone. Using the zeolite-supported amino acid catalyst results in higher selectivity for 5-methyl-3-en-2-hexanone. By mass, the basic amino acid content in the zeolite-supported amino acid catalyst is 10–50 wt%. Under the same catalyst / isobutyraldehyde ratio, this application's use of the zeolite-supported amino acid catalyst significantly improves the catalytic effect and reduces the amount of amino acid used in the reaction.

[0045] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of zeolite-supported alkaline amino acid catalysts in the preparation of 5-methyl-3-en-2-hexanone, characterized in that, The catalyst is made of zeolite molecular sieve and basic amino acids supported on the zeolite molecular sieve, with the loading of basic amino acids being 10-50 wt% based on the total mass of the catalyst; the zeolite molecular sieve includes alkali-treated ZSM-5, SBA-15 or Beta zeolite molecular sieve, and the basic amino acid includes one or both of arginine or lysine. Under the action of the zeolite-supported alkaline amino acid catalyst, acetone and isobutyraldehyde undergo a dehydration condensation reaction to generate 5-methyl-3-en-2-hexanone.

2. The application as described in claim 1, characterized in that, The preparation method of the zeolite-supported alkaline amino acid catalyst includes: immersing a zeolite molecular sieve in an aqueous solution of the alkaline amino acid, stirring and allowing it to stand for soaking, and then drying it, wherein the alkaline amino acid fills the pores of the zeolite molecular sieve to generate a zeolite-supported alkaline amino acid catalyst.

3. The application as described in claim 2, characterized in that, The stirring time is 1-2 hours, the standing soaking time is 18-24 hours, and the drying temperature is 60-80℃.

4. The application as described in claim 1, characterized in that, The specific surface area of ​​zeolite-supported alkaline amino acid catalysts is 300–900 m². 2 / g, pore volume 0.1~1.5cm 3 / g.

5. The application as described in claim 1, characterized in that, The dehydration condensation reaction includes at least one of the following reaction conditions: a reaction pressure of 0.5–5.0 MPa; a reaction temperature of 60–150 °C; a molar ratio of acetone to isobutyraldehyde of 0.5:1–4:1; and a mass ratio of the catalyst to isobutyraldehyde of 0.1:1–0.4:

1.

6. The application as described in claim 5, characterized in that, The reaction pressure is 1.0 MPa to 3.0 MPa; the reaction temperature is 70 to 100℃; the molar ratio of acetone to isobutyraldehyde is 1:1 to 2:1; and the mass ratio of the catalyst to isobutyraldehyde is 0.2:

1.

7. The application as described in claim 1, characterized in that, After dehydration condensation reaction, zeolite-loaded basic amino acids are recovered by filtration and reused.

8. The application as described in claim 7, characterized in that, The filtered reaction solution was fractionated to obtain water, acetone, isobutyraldehyde and the product 5-methyl-3-en-2-hexanone.

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