A method for preparing allyl alcohol

Abstract

The present invention discloses a preparation method of allyl alcohol, belonging to the technical field of organic synthesis. The preparation method of the present invention passes an aqueous solution of allyl acetate into a fixed-bed reactor filled with an FeCl3-PBImim-PMO catalyst, and heats it to carry out an ester hydrolysis reaction to obtain a product containing acetic acid and allyl alcohol. The present invention uses an immobilized acidic ionic liquid as a catalyst, enabling the reaction to occur at relatively high temperatures and pressures, endowing the process with a very high reaction rate and conversion rate. The content of allyl acetate in the obtained product is ≤500 ppm, which is beneficial to the subsequent purification and separation of allyl alcohol. In addition, the preparation method of the present invention has simple steps, can adapt to working conditions with different raw material concentration ranges, and the immobilized acidic ionic liquid catalyst can be separated from the reaction system, making the reaction continuous and facilitating industrialization.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and particularly relates to a method for preparing allyl alcohol. Background Art

[0002] Allyl alcohol is an important organic synthesis raw material, mainly used for synthesizing 1,4-butanediol, epichlorohydrin, glycerol, allyl esters, allyl ethers, etc., and can be industrially applied to the production of products such as plasticizers, engineering plastics, polyethers, and surfactants.

[0003] Currently, in the prior art, allyl alcohol is usually prepared by hydrolysis of esters in the presence of an acid. The mechanism of acid hydrolysis of esters is as follows: under acid catalysis, the carbonyl oxygen atom is first protonated, the positive charge of the carbonyl carbon increases, water molecules attack the carbonyl carbon, and addition-elimination occurs to generate carboxylic acid and alcohol. For example, Showa Denko KK developed a technology for producing allyl alcohol by hydrolysis of allyl acetate in 1985, and the above method was disclosed in Chinese Patent CN1759091A. This hydrolysis reaction uses a cation exchange resin as a catalyst, but due to the use temperature limitation of the cation exchange resin, the reaction is carried out at 80°C, resulting in a slow reaction rate; at the same time, due to the azeotropic characteristics between the product and the raw material components, the subsequent separation of this method is relatively complex. Chinese Patent CN103119007A supplements a scheme using an alkali as a hydrolysis catalyst, but its effect is not as good as that of an acidic cation exchange resin.

[0004] Therefore, based on the existing preparation process, how to improve the reaction rate of the hydrolysis of allyl acetate to produce allyl alcohol, make the reaction more complete, and facilitate the subsequent separation of the product is one of the technical difficulties in realizing the efficient and continuous industrial production of allyl alcohol. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a method for preparing allyl alcohol. This preparation method has simple steps, reacts at a higher temperature and pressure, greatly improves the reaction rate and conversion rate, and the content of allyl acetate in the product is low, which is convenient for the subsequent separation of the product.

[0006] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing allyl alcohol, which includes the following steps: passing an aqueous solution of allyl acetate into a fixed-bed reactor filled with an FeCl3-PBImim-PMO catalyst, heating to 120-150°C for an ester hydrolysis reaction to obtain a product containing acetic acid and allyl alcohol, and the reaction formula is as follows:

[0008]

[0009] As a preferred embodiment of the present invention, the mass concentration of the allyl acetate aqueous solution is 20% to 80%.

[0010] More preferably, the mass concentration of the allyl acetate aqueous solution is 30% to 70%.

[0011] As a preferred embodiment of the present invention, the mass hourly space velocity of the allyl acetate aqueous solution fed is 3 to 10 (kg*h -1 ) / kg catalyst.

[0012] As a preferred embodiment of the present invention, the structural formula of the FeCl3-PBImim-PMO catalyst is as shown in the following formula:

[0013]

[0014] As a preferred embodiment of the present invention, the reaction pressure in the fixed bed reactor is 0.3 to 0.7 Mpa.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] The present invention uses the immobilized acidic ionic liquid FeCl3-PBImim-PMO as the catalyst for the hydrolysis of allyl acetate. While retaining the industrial fixed bed process, it increases the upper limit of the reaction temperature, enabling the hydrolysis reaction to proceed at higher temperatures and pressures. This accelerates the reaction rate, allowing the reaction materials to flow through the fixed bed at a faster rate, and increases the chemical equilibrium constant of the hydrolysis reaction, promoting the hydrolysis reaction and making it more complete. The conversion rate is high, and the content of allyl acetate in the product is less than 500 ppm, which is beneficial for the subsequent purification and separation of allyl alcohol. At the same time, the preparation method of the present invention has simple steps, can adapt to different raw material concentration range working conditions, and the immobilized ionic liquid catalyst can be separated from the reaction system, making the reaction continuous and facilitating industrialization. Specific Embodiments

[0017] The present invention will be further described in detail below in conjunction with specific embodiments.

[0018] A method for preparing allyl alcohol, which comprises the following steps: feeding an allyl acetate aqueous solution with a mass concentration of 20% to 80% into a fixed bed reactor filled with FeCl3-PBImim-PMO catalyst at a mass hourly space velocity of 3 to 10 (kg*h -1 ) / kg catalyst, heating to 120 to 150 °C, and carrying out an ester hydrolysis reaction under a pressure of 0.3 to 0.7 Mpa to obtain a product containing acetic acid and allyl alcohol. The reaction formula is as follows:

[0019]

[0020] Among them, the structural formula of the FeCl3-PBImim-PMO catalyst is shown as follows:

[0021]

[0022] Example 1

[0023] A preparation method of allyl alcohol, which comprises the following steps:

[0024] Preheat an aqueous solution of allyl acetate with a mass concentration of 20% to about 120°C, and introduce it into a fixed-bed reactor (Φ*25*2.5, 5000mm) filled with 3 kg of immobilized acidic ionic liquid FeCl3-PBImim-PMO catalyst. The reaction temperature is 120°C, the reaction pressure is 0.3 Mpa, and the flow rate of the aqueous solution of allyl acetate is controlled to be 30 kg / h. After the material at the outlet of the fixed-bed reactor is stable, samples are taken and the content of allyl alcohol in the product is measured to be 11.6%, the content of allyl acetate is 78 ppm, and the conversion rate is 99.99%.

[0025] Example 2

[0026] [[ID=I8]]A preparation method of allyl alcohol, which comprises the following steps:

[0027] Preheat an aqueous solution of allyl acetate with a mass concentration of 30% to about 120°C, and introduce it into a fixed-bed reactor (Φ*25*2.5, 5000mm) filled with 3 kg of immobilized acidic ionic liquid FeCl3-PBImim-PMO catalyst. The reaction temperature is 120°C, the reaction pressure is 0.3 Mpa, and the flow rate of the aqueous solution of allyl acetate is controlled to be 30 kg / h. After the material at the outlet of the fixed-bed reactor is stable, samples are taken and the content of allyl alcohol in the product is measured to be 17.4%, the content of allyl acetate is 80 ppm, and the conversion rate is 99.99%.

[0028] Example 3

[0029] A preparation method of allyl alcohol, which comprises the following steps:

[0030] Preheat an aqueous solution of allyl acetate with a mass concentration of 50% to about 130°C, and introduce it into a fixed-bed reactor (Φ*25*2.5, 5000mm) filled with 3 kg of immobilized acidic ionic liquid FeCl3-PBImim-PMO catalyst. The reaction temperature is 130°C, the reaction pressure is 0.45 Mpa, and the flow rate of the aqueous solution of allyl acetate is controlled to be 15 kg / h. After the material at the outlet of the fixed-bed reactor is stable, samples are taken and the content of allyl alcohol in the product is measured to be 29.1%, the content of allyl acetate is 189 ppm, and the conversion rate is 99.98%.

[0031] Example 4

[0032] A method for preparing allyl alcohol, which comprises the following steps:

[0033] Preheat an aqueous solution of allyl acetate with a mass concentration of 70% to about 150 °C, and introduce it into a fixed-bed reactor (Φ25*2.5, 5000 mm) filled with 3 kg of immobilized acidic ionic liquid FeCl3-PBImim-PMO catalyst. The reaction temperature is 150 °C, the reaction pressure is 0.7 Mpa, and the flow rate of the aqueous solution of allyl acetate is controlled at 9 kg / h. After the material at the outlet of the fixed-bed reactor is stable, a sample is taken and the content of allyl alcohol in the product is measured to be 40.6%, the content of allyl acetate is 274 ppm, and the conversion rate is 99.97%.

[0034] Example 5

[0035] A method for preparing allyl alcohol, which comprises the following steps:

[0036] Preheat an aqueous solution of allyl acetate with a mass concentration of 80% to about 150 °C, and introduce it into a fixed-bed reactor (Φ25*2.5, 5000 mm) filled with 3 kg of immobilized acidic ionic liquid FeCl3-PBImim-PMO catalyst. The reaction temperature is 150 °C, the reaction pressure is 0.7 Mpa, and the flow rate of the aqueous solution of allyl acetate is controlled at 9 kg / h. After the material at the outlet of the fixed-bed reactor is stable, a sample is taken and the content of allyl alcohol in the product is measured to be 46.4%, the content of allyl acetate is 476 ppm, and the conversion rate is 99.95%.

[0037] From the comparison of Examples 1-5, it can be seen that using the immobilized acidic ionic liquid FeCl3-PBImim-PMO to catalyze the hydrolysis reaction of allyl acetate has good catalytic conversion efficiency in the raw material mass concentration range of 20% to 80%, and the content of allyl acetate in the product is below 500 ppm. From the product content data of each example, it can be seen that the content of allyl acetate in the product increases rapidly with the increase of the reaction solution concentration, which is caused by two reasons: 1. When the reaction solution concentration increases, the reactor reaches its maximum load; 2. As the reaction products increase, the reverse hydrolysis reaction trend increases. With the increase of the concentration of the aqueous solution of allyl acetate, in order to achieve an ideal catalytic effect, the reaction temperature and pressure need to be increased accordingly, and the material flow rate needs to be reduced to increase the reaction contact time. Considering the comprehensive energy consumption and efficiency, the concentration of the aqueous solution of allyl acetate in the method of the present invention is preferably 30% to 70% in industrial production.

[0038] Comparative Example 1

[0039] A method for preparing allyl alcohol, which comprises the following steps:

[0040] Preheat an aqueous solution of allyl acetate with a mass concentration of 30% to about 80°C and feed it into a fixed-bed reactor (Φ25*2.5, 5000 mm) filled with 3 kg of cationic acidic resin. The reaction temperature is 80°C and the reaction pressure is 0.2 Mpa to ensure a liquid-phase reaction inside the reactor. Control the flow rate of the aqueous solution of allyl acetate at 25 kg / h. After the material at the outlet of the fixed-bed reactor is stable, sample and measure that the content of allyl alcohol in the product is 17.0%, the content of allyl acetate is 0.74%, and the conversion rate is 97.53%.

[0041] Comparative Example 2

[0042] A method for preparing allyl alcohol, which comprises the following steps:

[0043] Preheat an aqueous solution of allyl acetate with a mass concentration of 70% to about 80°C and feed it into a fixed-bed reactor (Φ25*2.5, 5000 mm) filled with 3 kg of cationic acidic resin. The reaction temperature is 80°C and the reaction pressure is 0.2 Mpa to ensure a liquid-phase reaction inside the reactor. Control the flow rate of the aqueous solution of allyl acetate at 5 kg / h. After the material at the outlet of the fixed-bed reactor is stable, sample and measure that the content of allyl alcohol in the product is 39.6%, the content of allyl acetate is 1.64%, and the conversion rate is 97.66%.

[0044] It can be seen from the comparison between Example 2 and Comparative Example 1, and between Example 4 and Comparative Example 2 that even if the flow rate of the aqueous solution of allyl acetate is reduced and the residence time of the reactants in the cationic acidic resin is increased, the catalytic effect of the cationic acidic resin on allyl acetate is still worse than that of the immobilized acidic ionic liquid FeCl3-PBImim-PMO catalyst. Using the immobilized acidic ionic liquid catalyst of the present invention has a higher conversion rate, and this characteristic is reflected in both high-concentration and low-concentration aqueous solutions of allyl acetate. The main reason for this difference is that the hydrolysis reaction of allyl acetate is an endothermic reaction, and increasing the temperature can promote the hydrolysis of allyl acetate and accelerate the reaction rate. The upper limit of the operating temperature of the cationic acidic resin is 100-105°C, and the optimum operating temperature is about 80°C, while the acidic ionic liquid can be used at a relatively higher temperature and has more excellent acid-catalytic properties. Therefore, the content of the raw materials in the reaction solution after being catalyzed by the immobilized acidic ionic liquid is lower and the hydrolysis conversion rate is higher.

[0045] Comparative Example 3

[0046] A method for preparing allyl alcohol, which comprises the following steps:

[0047] The aqueous solution of allyl acetate with a mass concentration of 30% is preheated to about 80 °C and enters a fixed-bed reactor (Φ25*2.5, 5000 mm) filled with 3 kg of immobilized acidic ionic liquid FeCl3-PBImim-PMO catalyst. The reaction temperature is 80 °C and the reaction pressure is 0.2 Mpa to ensure a liquid-phase reaction inside the reactor. The flow rate of the aqueous solution of allyl acetate is controlled at 25 kg / h. After the material at the outlet of the fixed-bed reactor is stable, the content of allyl alcohol in the product is measured to be 16.88%, the content of allyl acetate is 0.89%, and the conversion rate is 97.03%.

[0048] Comparative Example 4

[0049] A method for preparing allyl alcohol, which comprises the following steps:

[0050] The aqueous solution of allyl acetate with a mass concentration of 70% is preheated to about 80 °C and enters a fixed-bed reactor (Φ25*2.5, 5000 mm) filled with 3 kg of immobilized acidic ionic liquid FeCl3-PBImim-PMO catalyst. The reaction temperature is 80 °C and the reaction pressure is 0.2 Mpa to ensure a liquid-phase reaction inside the reactor. The flow rate of the aqueous solution of allyl acetate is controlled at 5 kg / h. After the material at the outlet of the fixed-bed reactor is stable, the content of allyl alcohol in the product is measured to be 39.58%, the content of allyl acetate is 1.75%, and the conversion rate is 97.50%.

[0051] By comparing Comparative Example 1 and 3, and Comparative Example 2 and 4, it can be found that when other process parameters are the same and only the catalysts are different, the catalytic hydrolysis effects of the immobilized acidic ionic liquid FeCl3-PBImim-PMO catalyst and the cationic acidic resin catalyst on allyl acetate are similar, and even slightly lower than that of the cationic acidic resin catalyst. It can be seen that the present invention effectively improves the reaction conversion rate by using the immobilized acidic ionic liquid FeCl3-PBImim-PMO as the catalyst and controlling the reaction temperature, and the content of allyl acetate in the product is lower than 500 ppm, which is beneficial to the subsequent purification and separation of allyl alcohol.

[0052] The above embodiments are only the preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantive changes and substitutions made by those skilled in the art based on the present invention belong to the scope of protection required by the present invention.

Claims

1. A method for preparing allyl alcohol, characterized in that: It includes the following steps: Pass an aqueous solution of allyl acetate into a fixed-bed reactor filled with a FeCl3-PBImim-PMO catalyst, heat it to 120-150 °C for an ester hydrolysis reaction to obtain a product containing allyl alcohol; wherein, the structural formula of the FeCl3-PBImim-PMO catalyst is shown as follows:

2. The preparation method of allyl alcohol according to claim 1, characterized in that: The mass concentration of the aqueous solution of allyl acetate is 20% - 80%.

3. The method for preparing allyl alcohol according to claim 1, wherein: The mass concentration of the aqueous solution of allyl acetate is 30% - 70%.

4. The method for preparing allyl alcohol according to any one of claims 1 to 3, characterized in that: The mass hourly space velocity of the aqueous allyl acetate solution fed is 3 to 10 (kg*h -1 ) / kg catalyst.

5. The preparation method of allyl alcohol according to claim 1, characterized in that: The reaction pressure in the fixed-bed reactor is 0.3 - 0.7 Mpa.

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