Preparation method of allyl alcohol

Abstract

The invention provides a preparation method of allyl alcohol, and belongs to the technical field of allyl alcohol. A preparation method of allyl alcohol comprises the following steps: (1) preparation of a catalyst: preparing a partially fluorinated aluminum oxide loaded lithium phosphate catalyst by a coprecipitation method, specifically, dropwise adding an aluminum trichloride aqueous solution into a mixed solution of phosphoric acid and hydrofluoric acid, and adding a mixture of lithium hydroxide and sodium hydroxide in batches; stirring and reacting for 1-9 hours, filtering, washing, forming and drying; burning for 5-10 hours at 230-350 DEG C in a nitrogen atmosphere to obtain a catalyst; and (2) epoxypropane isomerization reaction: filling the catalyst prepared in the step (1) into a reactor, taking nitrogen as carrier gas, preheating the nitrogen carrying epoxypropane through a heating belt, then feeding the nitrogen into the reactor, controlling the flow of the epoxypropane to be 3-30mL / min, the preheating temperature to be 150-280 DEG C and the reaction temperature to be 250-380 DEG C, and collecting the product allyl alcohol.

Description

Technical Field

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

[0002] Allyl alcohol, also known as propenol, is a colorless liquid that can be miscible with water, ethanol, ether, chloroform, and petroleum ether. Due to the presence of two functional groups, double bond and hydroxyl group, in the molecular structure of allyl alcohol, it can undergo various reactions such as oxidation, reduction, esterification, etherification, and addition. It can be used in the production of glycerol, acrolein, and 1,4-butanediol, and is an important intermediate for pharmaceuticals, pesticides, fragrances, and cosmetics.

[0003] The main synthesis methods of allyl alcohol include hydrolysis of allyl chloride, reduction of acrolein, hydrolysis of allyl acetate, and isomerization of propylene oxide, etc. Hydrolysis of allyl chloride method: This method was developed and successfully applied by Shell Oil Company and Dow Chemical Company in the United States in 1947 respectively, and it is the earliest method for industrial production of allyl alcohol. Allyl chloride is hydrolyzed in a 5-10% aqueous NaOH solution under the conditions of 150 °C, 1.3-1.4 MPa, and pH 2-10 to obtain allyl alcohol, with a yield of about 85%-95%, and by-products such as 5%-10% diallyl ether, propionaldehyde, and high-boiling substances are produced. This method has many by-products and is difficult to purify. Reduction of acrolein method: Under the action of a catalyst, propylene is first oxidized to acrolein, and then acrolein undergoes hydrogen exchange with ethanol or isopropanol to obtain allyl alcohol. For example, under the conditions of 400 °C, 0.1 MPa, and using MgO and ZnO as catalysts, acrolein reacts with isopropanol, and allyl alcohol and acetone are generated through hydrogen transfer. However, acrolein has problems such as strong toxicity, easy polymerization, and complex separation and purification, and the equipment investment is relatively large. Hydrolysis of allyl acetate method: It was developed and successfully applied by Showa Denko of Japan in 1985. Propylene is acetylated to form allyl acetate, and then allyl alcohol is obtained through hydrolysis or transesterification. The hydrolysis process of this method is an equilibrium reaction process, and there is a relatively complex azeotropic relationship among the various compounds in the reaction solution, making it difficult to recover acetic acid and purify, increasing the production cost. Isomerization of propylene oxide method: After propylene oxide is vaporized and preheated, it enters the reactor through a distributor, and under the conditions of 280 ± 5 °C and 12 MPa pressure, using lithium phosphate as a catalyst, allyl alcohol is obtained through liquid-phase or gas-phase isomerization reaction, with a selectivity of 94% and a conversion rate of propylene oxide of 58%-75%. This method has the advantages of simple process, high yield, no corrosion to equipment, and no generation of "three wastes" pollution, and is currently the main method for producing allyl alcohol, but the catalyst is prone to deactivation.

[0004] In view of the above problems encountered in the related fields, the present invention aims to provide a method for isomerizing propylene oxide to prepare allyl alcohol with high conversion rate and selectivity under the action of a catalyst. This method has a simple process, is easy to scale up, and has low cost. Summary of the Invention

[0005] The object of the present invention is to address the above problems existing in the prior art and propose a method for preparing allyl alcohol, which has the characteristics of high selectivity and high conversion rate.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] A method for preparing allyl alcohol, comprising the following steps:

[0008] (1) Preparation of the catalyst: Prepare a lithium phosphate supported on partially fluorinated alumina catalyst by the co-precipitation method, specifically including:

[0009] Drop an aqueous solution of aluminum trichloride into a mixed solution of phosphoric acid and hydrofluoric acid, and add a mixture of lithium hydroxide and sodium hydroxide in batches;

[0010] After stirring and reacting for 1 - 9 hours, filter, wash, shape and dry;

[0011] Calcine in a nitrogen atmosphere at 230 - 350 °C for 5 - 10 hours to obtain the catalyst;

[0012] (2) Propylene oxide isomerization reaction: Load the catalyst prepared in step (1) into a reactor. Using nitrogen as the carrier gas, nitrogen carries propylene oxide and enters the reactor after being preheated by a heating belt. Control the flow rate of propylene oxide to be 3 - 30 mL / min, the preheating temperature to be 150 - 280 °C, and the reaction temperature to be 250 - 380 °C, and collect the product allyl alcohol.

[0013] In the above method for preparing allyl alcohol, the molar ratio of the raw materials of the catalyst is phosphoric acid: lithium hydroxide: sodium hydroxide: aluminum trichloride: hydrogen fluoride = 1:(2.7 - 2.995):(0.3 - 0.005):(0.85 - 3.4):(0.07 - 0.3).

[0014] In the above method for preparing allyl alcohol, in step (1), the phosphoric acid is an 85% phosphoric acid solution, and the hydrofluoric acid is a 40% aqueous solution; when preparing the mixed acid solution of phosphoric acid and hydrofluoric acid, the weight of water is 5 - 100 times the weight of the mixed acid.

[0015] In the above method for preparing allyl alcohol, the weight of water is 10 - 80 times the weight of the mixed acid.

[0016] In the above method for preparing allyl alcohol, in step (1), the stirring reaction time is 2 - 6 hours, and the calcination temperature is 250 - 330 °C.

[0017] In the above method for preparing allyl alcohol, the shape of the catalyst is columnar, with a diameter of 0.2 - 5 mm and a length of 0.4 - 10 mm.

[0018] In the above-mentioned method for preparing allyl alcohol, the inner diameter of the reactor is 10 mm, and the filling height of the catalyst is 3 - 13 cm.

[0019] In the above-mentioned method for preparing allyl alcohol, in step (2), the nitrogen flow rate is 8 - 20 mL / min, the propylene oxide flow rate is 5 - 20 mL / min, the preheating temperature is 180 - 230 °C, and the reaction temperature is 280 - 350 °C.

[0020] In the above-mentioned method for preparing allyl alcohol, a partially fluorinated alumina support is used to simultaneously generate a lithium phosphate active component by coprecipitation, and the degree of fluorination of the alumina is adjusted by the addition amount of hydrofluoric acid.

[0021] Compared with the prior art, the present application has the following advantages:

[0022] Using partially fluorinated alumina to replace silica, its amphoteric properties can adjust the acid-base site balance through the degree of fluorination, thereby optimizing the reaction path and reducing by-products such as propionaldehyde and acetone. The lithium phosphate is uniformly combined with the partially fluorinated alumina by coprecipitation to enhance the dispersion of the active component and avoid side reactions caused by local acid-base imbalance. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0024] Figure 1 It is a schematic diagram of different bond-breaking reaction paths and products of propylene oxide. Detailed Embodiments

[0025] The following will further specifically illustrate the technical solutions of the present invention through specific embodiments in combination with the drawings. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any form of modification and / or change made to the present invention will fall within the protection scope of the present invention.

[0026] In the present invention, unless otherwise specified, all parts and percentages are in weight units, and the equipment and raw materials used can be purchased from the market or are commonly used in the art. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art. The components or equipment in the following embodiments, unless otherwise specified, are general standard parts or parts known to those skilled in the art, and their structures and principles can all be known to those skilled in the art through technical manuals or through conventional experimental methods.

[0027] Such as Figure 1As shown in:

[0028] Example 1:

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

[0030] (1) Preparation of the catalyst: Prepare a lithium phosphate supported on partially fluorinated alumina catalyst by co-precipitation method, specifically including:

[0031] In a 1L PFA three-necked flask, add 250g of water to a mixed solution of 23g of 85% phosphoric acid and 0.55g of 40% hydrofluoric acid;

[0032] Dropwise add 150g of an aqueous solution containing 10g of aluminum chloride to the mixed solution of phosphoric acid and hydrofluoric acid, and add a mixture of 14.4g of lithium hydroxide and 13g of sodium hydroxide in batches;

[0033] After stirring and reacting for 2 hours, filter, wash, shape and dry, and the drying temperature is 120°C;

[0034] Calcine in a nitrogen atmosphere at 280°C for 6 hours to obtain a columnar catalyst;

[0035] The shape of the catalyst is columnar, with a diameter of 1mm and a length of 2mm;

[0036] (2) Propylene oxide isomerization reaction: Load the catalyst prepared in step (1) into the reactor. The inner diameter of the reactor is 10mm, and the filling height of the catalyst is 13cm. Use nitrogen as the carrier gas. Nitrogen carries propylene oxide and enters the reactor after being preheated by a heating belt. The nitrogen flow rate is 5mL / min, control the propylene oxide flow rate to be 7mL / min, the preheating temperature is 230°C, the reaction temperature is 300°C, and collect the product allyl alcohol through a cold trap.

[0037] GC analysis shows that the reaction conversion rate is about 82%, the selectivity of allyl alcohol is 97.3%, the content of n-propanol is 0.5%, the content of acetone is 1.2%, and the content of propionaldehyde is 1.0%.

[0038] Example 2:

[0039] A preparation method of allyl alcohol, comprising the following steps:

[0040] (1) Preparation of the catalyst: Prepare a lithium phosphate supported on partially fluorinated alumina catalyst by co-precipitation method, specifically including:

[0041] In a 1L PFA three-necked flask, add 250g of water to a mixed solution of 22g of 85% phosphoric acid and 0.95g of 40% hydrofluoric acid;

[0042] Dropwise add 150g of an aqueous solution containing 14g of aluminum chloride to the mixed solution of phosphoric acid and hydrofluoric acid, and add a mixture of 14.4g of lithium hydroxide and 11g of sodium hydroxide in batches;

[0043] After stirring and reacting for 4 hours, filter, wash, form and dry, with the drying temperature at 120°C;

[0044] Calcine at 290°C for 6 hours under a nitrogen atmosphere to obtain a columnar catalyst;

[0045] The catalyst is in columnar shape, with a diameter of 0.8 mm and a length of 1.5 mm;

[0046] (2) Propylene oxide isomerization reaction: Load the catalyst prepared in step (1) into the reactor. The inner diameter of the reactor is 10 mm, the loading height of the catalyst is 15 cm. Using nitrogen as the carrier gas, nitrogen carries propylene oxide and enters the reactor after being preheated by a heating tape. The nitrogen flow rate is 7 mL / min, control the propylene oxide flow rate to be 8 mL / min, the preheating temperature is 250°C, the reaction temperature is 330°C, and collect the product allyl alcohol through a cold trap.

[0047] GC analysis shows that the reaction conversion rate is about 89%, the selectivity of allyl alcohol is 98.1%, the content of n-propanol is 0.14%, the content of acetone is 1.04%, and the content of propionaldehyde is 0.72%.

[0048] Example 3:

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

[0050] (1) Preparation of the catalyst: Prepare a lithium phosphate supported on partially fluorinated alumina catalyst by the co-precipitation method, specifically including:

[0051] In a 1 L PFA three-necked flask, add 250 g of water to a mixed solution of 22 g of 85% phosphoric acid and 2.5 g of 40% hydrofluoric acid;

[0052] Dropwise add 150 g of an aqueous solution containing 16 g of aluminum chloride to the mixed solution of phosphoric acid and hydrofluoric acid, and add a mixture of 15.6 g of lithium hydroxide and 2 g of sodium hydroxide in batches;

[0053] After stirring and reacting for 4 hours, filter, wash, form and dry, with the drying temperature at 120°C;

[0054] Calcine at 330°C for 6 hours under a nitrogen atmosphere to obtain a columnar catalyst;

[0055] The catalyst is in columnar shape, with a diameter of 1.2 mm and a length of 1.2 mm;

[0056] (2) Isomerization reaction of propylene oxide: The catalyst prepared in step (1) is loaded into a reactor with an inner diameter of 10 mm and a catalyst loading height of 15 cm. Nitrogen is used as the carrier gas. Propylene oxide carried by nitrogen enters the reactor after being preheated by a heating tape. The nitrogen flow rate is 6 mL / min, the flow rate of propylene oxide is controlled at 8 mL / min, the preheating temperature is 260 °C, and the reaction temperature is 320 °C. The product allyl alcohol is collected through a cold trap.

[0057] GC analysis shows that the reaction conversion rate is about 84.8%, the selectivity for allyl alcohol is 97.23%, the content of n-propanol is 0.22%, the content of acetone is 2.01%, and the content of propionaldehyde is 0.54%.

[0058] The reactor in this application is a gas-solid reaction tube.

[0059] Comparative example:

[0060] 76 g of sodium phosphate dodecahydrate is dissolved in 200 mL of hot water to prepare an aqueous sodium phosphate solution. Then, 26 g of lithium hydroxide monohydrate is dissolved in 200 mL of hot water to form a solution, which is added dropwise to the sodium phosphate solution and stirred for 2 h to form a white lithium phosphate precipitate. The precipitate is filtered, washed with hot water, and dried at 120 °C.

[0061] 30 g of silica carrier (10 - 20 mesh) and 30 g of lithium phosphate are mixed in hot water. The mixture is filtered, washed, and dried under reduced pressure at 120 °C for 6 h. Finally, it is calcined at 320 °C for 8 h. The catalyst is reserved after passing through a 10 - 20 mesh sieve.

[0062] Take the dried catalyst above and load it into a reaction tube with an inner diameter of 10 mm and a loading height of 15 cm. Then, the nitrogen flow rate is 7 mL / min, the flow rate of propylene oxide is 8 mL / min, and the preheating temperature is 260 °C. After preheating, it enters the reaction tube and reacts at 330 °C. The product allyl alcohol is collected after being cooled by a cold trap.

[0063] GC analysis shows that the reaction conversion rate is about 57%, the selectivity for allyl alcohol is 92%, the content of n-propanol is 1.2%, the content of acetone is 3.2%, and the content of propionaldehyde is 3.6%.

[0064] It can be seen from the above reaction results that:

[0065] The isomerization of propylene oxide yields different products under different conditions. For example, aldehydes are obtained under the action of acidic sites, ketones are obtained under the action of basic sites, and allyl alcohol is obtained under the action of both acidic and basic sites.

[0066] Therefore, the acidic and basic sites of the carrier have a great influence on the isomerization reaction. Compared with silica, the alumina used in the present invention is an amphoteric compound, and its acidic and basic sites can be adjusted by partial fluorination. In addition, the partially fluorinated alumina supported lithium phosphate catalyst of the present invention is prepared by a co-precipitation method, and the combination between the carrier and lithium phosphate is more sufficient and uniform, having good catalytic activity, and can isomerize propylene oxide to prepare allyl alcohol with a high conversion rate and selectivity.

[0067] From the results of Examples 1-3, the prior art and the comparative examples:

[0068]

[0069] By replacing the traditional silica carrier with partially fluorinated alumina and using its amphoteric properties to regulate the acidic and basic sites, the ratio of acidic and basic sites on the carrier surface is accurately adjusted by the degree of fluorination, thereby effectively controlling the generation of by-products. The selectivity of the comparative example (silica carrier) is 92%, while the selectivity of Example 2 reaches 98.1%, and the total amount of by-products is reduced from 8% to 1.9%.

[0070] There is a trade-off relationship between the conversion rate (58-75%) and selectivity (94%) of the traditional process, while the present patent achieves both high values through the synergistic effect of the carrier and the active component: the conversion rate in Example 2 is 89% and the selectivity is 98.1%, breaking through the industry bottleneck.

[0071] Specific examples are used in this article to elaborate on the principle and implementation mode of the present invention. The description of the above examples is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing allyl alcohol, characterized in that: The following steps are involved: (1) Preparation of catalyst: A partially fluorinated alumina-supported lithium phosphate catalyst is prepared by a coprecipitation method, specifically comprising: Adding aluminum chloride aqueous solution dropwise to the mixed solution of phosphoric acid and hydrofluoric acid, and adding a mixture of lithium hydroxide and sodium hydroxide in batches; After stirring for 1-9 hours, filter, wash, shape and dry; Burning at 230-350° C. for 5-10 hours under a nitrogen atmosphere to obtain a catalyst; (2) Isomerization reaction of propylene oxide: The catalyst prepared in step (1) is loaded into a reactor, and nitrogen is used as a carrier gas. The nitrogen carries the propylene oxide through a heating belt for preheating before entering the reactor. The propylene oxide flow rate is controlled to be 3-30 mL / min, the preheating temperature is 150-280° C., the reaction temperature is 250-380° C., and the product allyl alcohol is collected.

2. The method for preparing allyl alcohol according to claim 1, characterized in that The molar ratio of the raw materials of the catalyst is phosphoric acid: lithium hydroxide: sodium hydroxide: aluminum chloride: hydrogen fluoride = 1: (2.7-2.995): (0.3-0.005): (0.85-3.4): (0.07-0.3).

3. The method for preparing allyl alcohol according to claim 1, characterized in that In step (1), phosphoric acid is an 85% phosphoric acid solution, and hydrofluoric acid is a 40% aqueous solution; when preparing a mixed acid solution of phosphoric acid and hydrofluoric acid, the weight of water is 5-100 times the weight of the mixed acid.

4. The method for preparing allyl alcohol according to claim 3, characterized in that: The weight of water is 10-80 times the weight of the mixed acid.

5. The method for preparing allyl alcohol according to claim 1, characterized in that: In step (1), the stirring reaction time is 2-6 hours, and the calcination temperature is 250-330°C.

6. The method for preparing allyl alcohol according to claim 1, characterized in that: The catalyst is in the shape of a column with a diameter of 0.2-5 mm and a length of 0.4-10 mm.

7. The method for preparing allyl alcohol according to claim 1, characterized in that: The inner diameter of the reactor is 10 mm, and the catalyst filling height is 3-13 cm.

8. The method for preparing allyl alcohol according to claim 1, characterized in that: In the step (2), the nitrogen flow rate is 8-20 mL / min, the propylene oxide flow rate is 5-20 mL / min, the preheating temperature is 180-230°C, and the reaction temperature is 280-350°C.

9. The method for preparing allyl alcohol according to claim 1, characterized in that: The partially fluorinated alumina carrier is used to simultaneously generate lithium phosphate active components through a co-precipitation method, and the fluorination degree of the alumina is adjusted by the amount of hydrofluoric acid added.

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