A method for preparing a phenylacetone, the phenylacetone prepared thereby, and applications thereof

Abstract

The application provides a preparation method of acetophenone, acetophenone prepared by the method and application. The steps comprise: reacting ethylbenzene and an oxygen-containing gas under the action of a catalyst and a cocatalyst, and then performing rectification to obtain acetophenone; wherein the catalyst is a metal acid salt, and the cocatalyst is an alkyl siloxane. The method can effectively reduce the types of impurities, improve the selectivity of acetophenone, and through continuous rectification separation, the content of the obtained acetophenone is greater than or equal to 99.9%, the content of 1-phenyl ethanol is 0-100 ppm, and the content of phenyl acetaldehyde is 0-100 ppm. In the ethylbenzene oxidation reaction, through the research on the reaction mechanism, the acetophenone has the characteristics of high yield and few types of impurities, and high-purity acetophenone is obtained through rectification separation.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis, specifically relating to a method for preparing acetophenone, the acetophenone prepared therefrom, and its applications. Background Technology

[0002] Acetophenone is an important organic synthesis intermediate, mainly used in the synthesis of PVC stabilizers, fragrance intermediates, and also in pharmaceutical synthesis.

[0003] The traditional production process of acetophenone involves acylation of benzene and acetic anhydride using aluminum trichloride as a catalyst. However, this process is environmentally unfriendly, and the byproduct acetic acid causes severe corrosion to equipment. This method has been phased out. The current industrial production method is the ethylbenzene oxidation process, which uses ethylbenzene and oxygen as raw materials to produce acetophenone through an oxidation reaction. The current improvements to the ethylbenzene oxidation process for acetophenone mainly focus on improving the catalyst.

[0004] CN114917917A discloses Cu for the oxidation method in the preparation of acetophenone. x Co 1-x The V2O6 catalyst achieves a conversion rate of over 50% for ethylbenzene and a selectivity of over 90% for acetophenone. After 20 cycles, the catalytic efficiency is still over 98% compared to the first use. However, the catalyst preparation process is complex and the catalyst consumption is high, resulting in an increased cost per ton of acetophenone.

[0005] CN113979845A discloses a method for producing acetophenone by ethylbenzene oxidation. This method can improve the production efficiency of acetophenone by ethylbenzene oxidation, reduce the emissions of waste gas, wastewater, and solid waste during the process, improve catalyst utilization efficiency, and reduce energy consumption in acetophenone production. However, the catalyst can be recycled up to 4 times, the purity of the acetophenone obtained is >99%, the catalyst consumption is high, and the product purity is >99%, which does not meet the requirements for the use of high-purity acetophenone.

[0006] For certain food-grade synthetic fragrances, aldehyde and ketone resins, inks, and other products, high-purity acetophenone is required as a raw material for synthesis, and the content of the impurity 1-phenylethanol must be within 500 ppm. Therefore, it is essential to synthesize high-purity acetophenone efficiently and economically. Summary of the Invention

[0007] To address the aforementioned problems in the existing technology, the present invention aims to provide a high-purity acetophenone and its preparation method. The method utilizes metal salts as catalysts and alkylsiloxanes as co-catalysts to catalyze the oxidation of ethylbenzene to prepare acetophenone. This effectively reduces the types of impurities and improves the selectivity of acetophenone. Through further distillation and separation, the obtained acetophenone content is ≥99.9%, the 1-phenylethanol content is 0-100 ppm, and the phenylacetaldehyde content is 0-100 ppm. This method can be used in fields requiring high-purity acetophenone as a raw material for synthesis, such as certain food-grade synthetic fragrances, aldehyde-ketone resins, inks, and other products.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] This invention provides a method for preparing acetophenone, comprising the following steps:

[0010] In the presence of a catalyst and a co-catalyst, ethylbenzene reacts with an oxygen-containing gas, and then acetophenone is obtained by distillation.

[0011] The catalyst is a metal salt, and the co-catalyst is an alkylsiloxane.

[0012] In the method of this invention, the reaction between ethylbenzene and oxygen in an oxygen-containing gas follows a free radical reaction mechanism. Ethylbenzene and oxygen first generate ethylbenzene free radicals at a relatively high temperature, followed by the generation of ethylbenzene hydrogen peroxide free radicals. These hydrogen peroxide free radicals then react with ethylbenzene to generate ethylbenzene hydrogen peroxide and ethylbenzene free radicals. A metal acid salt catalyst and a co-catalyst silane synergistically catalyze the highly selective decomposition of ethylbenzene hydrogen peroxide into acetophenone. The reaction process is shown in the following equation:

[0013]

[0014] In this invention, the oxygen-containing gas is selected from one or more of air, oxygen, water vapor, etc., with air being preferred.

[0015] In this invention, the molar ratio of ethylbenzene to oxygen-containing gas is 2 to 20:1, for example 2:1, 4:1, 6:1, 8:1, 10:1, 12:1, 14:1, 16:1, 18:1, 20:1, and the oxygen-containing gas is measured by the molar amount of oxygen therein.

[0016] In this invention, the metal acid salt is selected from one or more of metal carbonates, silicates, etc.

[0017] The metal salt, wherein the metal element is selected from one or more of aluminum, gallium, iron, zinc, calcium, and titanium.

[0018] In this invention, the alkylsiloxane is selected from one or more of hexamethyldisiloxane, trimethylpropoxysilane, allyloxytrimethylsilane, and methylpropyldimethoxysilane.

[0019] In this invention, the amount of the co-catalyst added is 0.1 to 0.5% of the mass of the oxygen-containing gas feed, for example, 0.1, 0.2, 0.3, 0.4, or 0.5%.

[0020] In this invention, the reaction temperature is 60–100°C, for example 60, 65, 70, 75, 80, 85, 90, 95, 100°C, and the reaction pressure is 0.1–1.5 MPaG, for example 0.1, 0.3, 0.5, 0.7, 0.9, 1.1, 1.3, 1.5 MPaG;

[0021] Preferably, in the reaction, the air space velocity is 2-5 h⁻¹. -1 For example, 2, 2.5, 3, 3.5, 4, 4.5, 5h -1 Based on the quality of the catalyst;

[0022] Preferably, the reaction is carried out in a multi-stage jet continuous reactor.

[0023] In this invention, the distillation is multi-stage distillation, preferably two-stage distillation, and the distillation is carried out through a first distillation column and a second distillation column;

[0024] Preferably, the top temperature of the first distillation column is 90–110°C, for example, 90, 95, 100, 105, or 110°C; the reflux ratio is 10–20, for example, 10, 12, 14, 16, 18, or 20; the bottom temperature is 120–150°C, for example, 120, 130, 140, or 150°C; and the operating pressure is 20–50 kPa, for example, 20, 30, 40, or 50 kPa. PaA; the top temperature of the second distillation column is 85-105℃, for example 85, 90, 95, 100, 105℃, the reflux ratio is 10-20, for example 10, 12, 14, 16, 18, 20, the bottom temperature is 110-120℃, for example 110, 113, 115, 118, 120℃, and the operating pressure is 1-8KPaA, for example 1, 3, 5, 7, 8KPaA.

[0025] Another object of the present invention is to provide an acetophenone product.

[0026] An acetophenone product, prepared by the above-described preparation method, wherein the acetophenone content is ≥99.9%, the 1-phenylethanol content is 0-100 ppm (e.g., 0, 10, 20, 40, 60, 80 ppm), and the phenylacetaldehyde content is 0-100 ppm (e.g., 0, 10, 20, 40, 60, 80 ppm), based on the total mass of acetophenone. Another object of the present invention is to provide a use for the acetophenone product.

[0027] An application of an acetophenone product, wherein the product is prepared by the above-described preparation method, or is the above-described acetophenone product, and the product is used in the fields of fragrances and flavors, PVC stabilizers, and advanced inks.

[0028] Compared with the prior art, the positive effects of the present invention are as follows:

[0029] (1) Ethylbenzene and oxygen-containing gas can be synthesized with high selectivity under the action of the catalyst and co-catalyst selected in this invention.

[0030] (2) The obtained high-purity acetophenone content is ≥99.9%, the 1-phenylethanol content is 0~100ppm, and the phenylacetaldehyde content is 0~100ppm, which can meet the application requirements of fragrances, PVC stabilizers, high-grade inks and other fields. Detailed Implementation

[0031] The following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other well-known modifications within the scope of the claims of the present invention. The specific application of the present invention is not limited to the applications mentioned in the examples. Simple modifications made to the present invention by those skilled in the art based on the concept of the present invention are all within the scope of protection claimed by the present invention.

[0032] The main raw material sources in the various embodiments and comparative examples of this invention are shown in Table 1 below. Unless otherwise specified, all other raw materials were purchased from commercially available finished products.

[0033] Table 1

[0034]

[0035]

[0036] The analytical instruments used in the embodiments of this invention are:

[0037] Gas chromatography was performed using an Anglient 7820A gas chromatograph (flame ionization detector, nitrogen as carrier gas) with a DB-5 capillary column (5% Phenyl Methyl Siloxan, 30m × 0.32mm × 0.25μm) and a flame ionization detector (FID). The injector and detector temperatures were both 280℃; column temperature was programmed: initial temperature 100℃, held for 0.5 min, increased to 260℃ at 15℃ / min, and held for 5 min. Column pressure was 8.5868 psi, and flow rate was 1.5 mL / min. Injection volume: 0.2 μL. Conversion and selectivity were calculated using the area normalization method.

[0038] The equipment information is as follows:

[0039] The reactor is a multi-stage jet fixed-bed reactor with a length of 120mm and an inner diameter of 25mm; the distillation column is 1200mm long and 25mm in diameter, and the packing is a 1.5mm*1.5mm triangular spiral.

[0040] Example 1

[0041] The steps for preparing acetophenone are as follows:

[0042] The reactor was packed with zinc silicate catalyst at a loading of approximately 23.5 g. The ethylbenzene feed rate was 106 g / h (1 mol / h), and the total air flow rate was 47 g / h (0.308 mol / h O2). The air was fed in multiple stages. The hexamethyldisiloxane addition rate was 0.047 g / h. The reaction temperature was 100℃, the pressure was 0.5 MPaG, and the air hourly space velocity (AHSV) was 2 h⁻¹. -1 (Based on zinc silicate), the resulting reaction solution is purified. Ethylbenzene and light alcohols are recovered in the first distillation column, with a top temperature of approximately 90°C, a reflux ratio of 10, a bottom temperature of 120°C, and an operating pressure of 25 kPaA. The bottom liquid enters the second distillation column for further purification, with a top temperature of approximately 85°C, a reflux ratio of 10, a bottom temperature of 110°C, and an operating pressure of 1.8 kPaA. The resulting acetophenone has a purity of 99.98%, a phenylacetaldehyde content of approximately 25 ppm, a 1-phenylethanol content of approximately 54 ppm, an ethylbenzene conversion rate of approximately 99.9%, and an acetophenone selectivity of 96.7%.

[0043] Example 2

[0044] The steps for preparing acetophenone are as follows:

[0045] The reactor was filled with calcium silicate catalyst, with a loading of approximately 31.3 g. The ethylbenzene feed rate was 212 g / h (2 mol / h), and the total air flow rate was 94 g / h (0.616 mol / h O2). Air was fed in multiple stages. The trimethylpropoxysilane addition rate was 0.188 g / h. The reaction temperature was 90℃, the pressure was 2 MPaG, and the air mass was 3 h⁻¹. -1 (Based on calcium silicate), the resulting reaction solution is purified. Ethylbenzene and light alcohols are recovered in the first distillation column, with a top temperature of approximately 95°C, a reflux ratio of 15, a bottom temperature of 125°C, and an operating pressure of 30 kPaA. The bottom liquid enters the second distillation column for further purification, with a top temperature of approximately 90°C, a reflux ratio of 15, a bottom temperature of 115°C, and an operating pressure of 2.3 kPaA. The resulting acetophenone has a purity of 99.978%, a phenylacetaldehyde content of approximately 32 ppm, a 1-phenylethanol content of approximately 47 ppm, an ethylbenzene conversion rate of approximately 99.9%, and an acetophenone selectivity of 97.2%.

[0046] Example 3

[0047] The steps for preparing acetophenone are as follows:

[0048] The reactor was filled with a catalyst consisting of a mixture of calcium silicate and zinc silicate in equal proportions, with a loading of approximately 9.4 g. The ethylbenzene feed rate was 424 g / h (4 mol / h), and the total air flow rate was 47 g / h (0.308 mol / h O2). Air was fed in multiple stages, with allyloxytrimethylsilane added at a rate of 0.235 g / h. The reaction temperature was 60℃, and the air mass was maintained for 5 hours. -1 (Based on calcium silicate and zinc silicate), under a pressure of 5 MPaG, the resulting reaction solution is purified. Ethylbenzene and light alcohols are recovered in the first distillation column, with a top temperature of approximately 100°C, a reflux ratio of 20, a bottom temperature of 130°C, and an operating pressure of 35 kPaA. The bottom liquid enters the second distillation column for further purification, with a top temperature of approximately 95°C, a reflux ratio of 20, a bottom temperature of 120°C, and an operating pressure of 3 kPaA. The resulting acetophenone has a purity of 99.986%, a phenylacetaldehyde content of approximately 56 ppm, a 1-phenylethanol content of approximately 77 ppm, an ethylbenzene conversion rate of approximately 99.9%, and an acetophenone selectivity of 96.9%.

[0049] Comparative Example 1

[0050] Acetophenone was prepared according to the method in Example 1, except that the co-catalyst hexamethyldisiloxane was not added, while other operations and conditions remained unchanged. The resulting acetophenone had a purity of 99.43%, a phenylacetaldehyde content of about 0.27%, a 1-phenylethanol content of about 0.15%, an ethylbenzene conversion rate of about 94.8%, and a selectivity of 88.7%.

[0051] Comparative Example 2

[0052] Acetophenone was prepared according to the method in Example 1, except that the zinc silicate catalyst was replaced with an equal amount of cobalt oxide, while other operations and conditions remained unchanged. The resulting acetophenone had a purity of 99.39%, a phenylacetaldehyde content of about 0.31%, a 1-phenylethanol content of about 0.18%, an ethylbenzene conversion rate of about 93.8%, and a selectivity of 85.5%.

[0053] Comparative Example 3

[0054] Acetophenone was prepared according to the method in Example 1, except that the zinc silicate catalyst was replaced with an equal amount of zinc oxide, while other operations and conditions remained unchanged. The resulting acetophenone had a purity of 99.28%, a phenylacetaldehyde content of approximately 0.22%, a 1-phenylethanol content of approximately 0.25%, an ethylbenzene conversion rate of approximately 88.75%, and a selectivity of 87.6%.

[0055] Comparative Example 4

[0056] Acetophenone was prepared according to the method in Example 1, except that the cocatalyst hexamethyldisiloxane was replaced with silicon tetrachloride, while other operations and conditions remained unchanged. The resulting acetophenone had a purity of 99.21%, a phenylacetaldehyde content of about 0.27%, a 1-phenylethanol content of about 0.4%, an ethylbenzene conversion rate of about 85.34%, and a selectivity of 82.89%.

Claims

1. A method for preparing acetophenone, characterized in that the steps include... include: In the presence of a catalyst and a co-catalyst, ethylbenzene reacts with an oxygen-containing gas, and then acetophenone is obtained by distillation. The catalyst is a metal salt, wherein the metal element is selected from one or more of zinc and calcium, and the co-catalyst is an alkylsiloxane; the metal salt is selected from one or more of metal carbonates and silicates; the alkylsiloxane is selected from one or more of hexamethyldisiloxane, trimethylpropoxysilane, allyloxytrimethylsilane, and methylpropyldimethoxysilane. The reaction is carried out at a temperature of 60~100℃ and a pressure of 0.1~1.5MPaG.

2. The preparation method according to claim 1, characterized in that, The oxygen-containing gas is selected from one or more of air, oxygen, and water vapor.

3. The preparation method according to claim 1, characterized in that, The molar ratio of ethylbenzene to oxygen-containing gas is 2~20:1, and the oxygen-containing gas is measured by the molar amount of oxygen in it.

4. The preparation method according to claim 1, characterized in that, The amount of the co-catalyst added is 0.1~0.5% of the mass of the oxygen-containing gas feed.

5. The preparation method according to claim 1, characterized in that, In the reaction, the air space velocity is 2~5 h⁻¹, based on the mass of the catalyst.

6. The preparation method according to claim 1, characterized in that, The reaction is carried out using a multi-stage jet continuous reactor.

7. The preparation method according to claim 1, characterized in that, The distillation is a multi-stage distillation.

8. The preparation method according to claim 7, characterized in that, The distillation is a two-stage distillation, which is carried out through a first distillation column and a second distillation column.

9. The preparation method according to claim 8, characterized in that, The first distillation column has a top temperature of 90~110℃, a reflux ratio of 10~20, a bottom temperature of 120~150℃, and an operating pressure of 20~50KPaA; the second distillation column has a top temperature of 85~105℃, a reflux ratio of 10~20, a bottom temperature of 110~120℃, and an operating pressure of 1~8KPaA.

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