Method for efficiently preparing 2-heptanone in large scale by two-step method

Abstract

The invention discloses a method for large-scale preparation of 2-heptanone from 1-heptene by a two-step method, which specifically comprises the following steps of: firstly, directly hydrating 1-heptene serving as a raw material by using a specific catalyst to obtain 2-heptanol, and secondly, reacting 1-heptene with 2-heptanol under the conditions of a copper-based fixed bed catalyst and hydrogen-containing mixed gas to obtain 2-heptanol. And carrying out gas-phase dehydrogenation to obtain the 2-heptanone. By optimizing the process route, the preparation efficiency is improved, the yield of 95% in the whole process is achieved, the yield is remarkably higher than that of a traditional process route using acetone and butyraldehyde as raw materials, discharge of waste liquid containing acid and alkali is greatly reduced, large-scale industrial production is easy to achieve, and the green chemistry concept is met.

Description

Technical Field

[0001] The present invention relates to the field of heptanone synthesis, and specifically refers to a method for large-scale preparation of 2-heptanone from 1-heptene by a two-step process. Background Art

[0002] 2-Heptanone, also known as Methyl Amyl Ketone (MAK), is a colorless, fragrant, and stable liquid. 2-Heptanone is slightly soluble in water and soluble in organic solvents such as ethanol and ether. Due to its excellent solubility, low toxicity, and good stability, 2-Heptanone has been widely used in many fields. In the paint industry, MAK, as a solvent, can significantly improve the fluidity and adhesion of paints and is widely used in automotive paints, architectural paints, and industrial anti-corrosion paints. In the adhesives field, MAK, as a tackifier and diluent, effectively improves the bonding strength and workability of adhesives. In the solvent field, MAK, as a high-purity solvent, plays an irreplaceable role in the production of pharmaceuticals, pesticides, and fine chemicals.

[0003] As a key organic chemical raw material, there are various synthesis routes for 2-heptanone, and each method has its unique advantages and limitations. The natural raw material extraction method, although having advantages in environmental protection, is difficult to meet the requirements of large-scale industrial production due to the unstable and limited supply of raw materials. The Grignard reagent method is famous for its ability to synthesize various ketone compounds, but due to the complexity and potential danger of its operation, it needs to be carried out under strictly controlled reaction conditions, which limits its wide application in industry. The biological fermentation method, as an environmentally friendly and sustainable synthesis method that uses microbial fermentation to synthesize 2-heptanone, although renewable, has low productivity and high costs, resulting in low economic efficiency. The ethyl acetoacetate method is one of the main methods for industrial production of 2-heptanone at present. Its raw materials are relatively easy to obtain, but the production cost is high, and the entire production process requires multiple complex steps. The diethyl malonate method is favored for the easy availability of its raw materials and direct synthesis route, but the presence of side reactions requires fine control of the reaction conditions to ensure product quality. The aldol condensation method, using acetone and butyraldehyde with lower costs as raw materials, is suitable for industrial production, but this method produces more side reactions, making the product separation and purification process complex and difficult. The acetone-butyraldehyde condensation method has attracted attention for its short process flow and reduced by-product formation. This method not only reduces the production cost but also improves the production efficiency to a certain extent, but still requires fine control of the reaction conditions to ensure high purity and yield of the product.

[0004] Therefore, in view of the advantages and disadvantages of the above-mentioned various processes, considering factors such as the availability of raw materials, cost, environmental friendliness, and the purity and yield of products, the present invention optimizes the synthesis method of 2-heptanone, realizes the preparation of 2-heptanone by a two-step method, significantly shortens the production cycle, and achieves a total selectivity of up to 98.5% and an excellent yield of 97%. The discharge of acid-base-containing waste liquid is greatly reduced. The present invention not only provides a new option for the scale-up and large-scale production of the process, but also can bring more significant economic benefits, thus making a positive contribution to the environmental sustainability while improving the production efficiency, and is of great significance to promoting the sustainable development of the chemical industry. Summary of the Invention

[0005] The present invention provides a method for efficiently and large-scale preparing 2-heptanone by a two-step method. The process method of the present invention significantly shortens the preparation time of 2-heptanone, and at the same time realizes a selectivity of up to 98.5% and a high yield of 97%, effectively reducing the discharge of acid-base-containing waste liquid, and can realize the scale-up and large-scale production of the process, while generating greater economic benefits. To achieve the above objectives, the synthesis process adopted by the present invention includes the following steps:

[0006] Step 1: Using 1-heptene as a raw material, directly hydrating it in an inert gas atmosphere using a specific catalyst to obtain 2-heptanol, and rectifying the mixed product to separate high-purity 2-heptanol. Among them, the specific catalyst includes one or more of solid acid catalysts, liquid acid catalysts, zeolite catalysts, molecular sieve catalysts, transition metal salt or oxygen salt catalysts, ion exchange resins, etc.;

[0007] Furthermore, the molar ratio of 1-heptene to water is 1:(1-50), preferably 1:(5-10);

[0008] Furthermore, the total weight ratio of the specific catalyst to 1-heptene and water is (1-5):10, preferably (2-4):10;

[0009] Furthermore, the reaction temperature is 80-200 °C, preferably 100-150 °C;

[0010] Furthermore, the reaction pressure is 0.5-10.0 MPa, preferably 1-3 MPa;

[0011] Furthermore, the reaction time is 0.5-4 h, preferably 1-3 h;

[0012] Furthermore, the by-products include one or more of heptanal, heptyl ether, etc.;

[0013] Step 2: Under the conditions of a copper-based fixed-bed catalyst and a mixed gas containing hydrogen, 2-heptanone and unreacted 2-heptanol are obtained through gas-phase dehydrogenation. The mixed product is subjected to vacuum distillation to separate the high-purity 2-heptanone product. Among them, the copper-based catalyst needs to be reduced under normal pressure to improve the catalytic effect;

[0014] Further, the mixed gas containing hydrogen contains, in addition to hydrogen, one of nitrogen, helium, and argon, and the volume content of hydrogen is 5% to 30%;

[0015] Further, the liquid hourly space velocity of the fed 2-heptanol is 0.5 h -1 ~10.0 h -1 ;

[0016] Further, the reaction temperature is 150 to 400 °C, preferably 200 to 250 °C;

[0017] Further, the reaction pressure is 0.01 to 2.0 MPa, preferably 0.2 to 1.5 MPa;

[0018] Further, the gas-phase cooling temperature at the reactor outlet is 60 to 80 °C, preferably 65 to 75 °C;

[0019] Further, the unreacted 2-heptanol obtained after separation by vacuum distillation needs to be returned to the hydration reactor for continuous reaction.

[0020] The reaction equation is as follows:

[0021] Specific Embodiments

[0022] A method for efficiently and large-scale preparing 2-heptanone by a two-step method provided by the present invention is further described below through specific examples. The examples described in the present invention are only for the illustration of the present invention and do not limit the scope of the present invention.

[0023]

Example 1

[0024] Step 1: The raw materials 1-heptene and water are mixed at a molar ratio of 1:6 and input into the reaction kettle as a mixed feed. AlPO 4 As a catalyst, the total weight ratio to 1-heptene and water is 3:10. Stir continuously in an inert gas atmosphere to ensure the uniformity of the materials in the reaction kettle. Heat up to 120 °C, and the pressure in the reaction kettle reaches 1.0 MPa. React under these conditions for 1.5 h. After the hydration reaction is completed, cool the reaction system to room temperature to obtain the products 2-heptanol and by-products heptaldehyde and heptyl ether. The reaction products 2-heptanol and by-products are exported from the reactor and subjected to distillation separation to obtain high-purity 2-heptanol.

[0025] Step 2: First, heat the copper-based catalyst to 150°C for reduction treatment for 18 hours, and load the pretreated catalyst into a fixed-bed tubular reactor. Feed a nitrogen-hydrogen gas mixture with a hydrogen volume content of 10%, preheat and vaporize 2-heptanol, and then feed it into the fixed-bed tubular reactor at a liquid volume hourly space velocity of 0.5 h -1 Feed it into the fixed-bed tubular reactor, control the reaction temperature at 200°C and the reaction pressure at 1.0 MPa, and carry out a dehydrogenation reaction. 2-Heptanol is dehydrogenated under the action of the copper-based catalyst to produce the target product 2-heptanone. Cool the gas phase at the reactor outlet to 70°C, input the reaction product 2-heptanone and unreacted 2-heptanol into a distillation column, and separate them by vacuum distillation to obtain high-purity 2-heptanone, and return the separated unreacted 2-heptanol to the hydration reactor for continuous reaction.

[0026]

Example 2

[0027] Step 1: Mix raw materials 1-heptene and water at a molar ratio of 1:10 and input the mixture as a mixed feed into a reaction kettle. ZSM molecular sieve is used as a catalyst with a total weight ratio to 1-heptene and water of 2:10. Heat it to 130°C in an inert gas atmosphere until the pressure in the reaction kettle reaches 1.4 MPa, and react under these conditions for 2 h. After that, when the hydration reaction ends, cool the reaction system to room temperature to obtain the product 2-heptanol and by-products heptanal and heptyl ether. Export the reaction product 2-heptanol and by-products from the reactor, and carry out distillation separation to obtain high-purity 2-heptanol.

[0028] Step 2: First, heat the copper-based catalyst to 150°C for reduction treatment for 18 hours, and load the pretreated catalyst into a fixed-bed tubular reactor. Feed a nitrogen-hydrogen gas mixture with a hydrogen volume content of 10%, preheat and vaporize 2-heptanol, and then feed it into the fixed-bed tubular reactor at a liquid volume hourly space velocity of 3.0 h -1 Feed it into the fixed-bed tubular reactor, control the reaction temperature at 220°C and the reaction pressure at 1.3 MPa, and carry out a dehydrogenation reaction. 2-Heptanol is dehydrogenated under the action of the copper-based catalyst to produce the target product 2-heptanone. Cool the gas phase at the reactor outlet to 70°C, input the reaction product 2-heptanone and unreacted 2-heptanol into a distillation column, and separate them by vacuum distillation to obtain high-purity 2-heptanone, and return the separated unreacted 2-heptanol to the hydration reactor for continuous reaction.

[0029]

Example 3

[0030] Step 1: Mix raw material 1-heptene and water at a molar ratio of 1:5 and input the mixture as a mixed feed into a reaction kettle. The solid superacid is used as a catalyst with a total weight ratio to 1-heptene and water of 1:10. Heat it to 100 °C under an inert gas atmosphere. The pressure in the reaction kettle reaches 0.8 MPa. React under these conditions for 3 h. After that, when the hydration reaction ends, cool the reaction system to room temperature to obtain the product 2-heptanol and by-products heptanal and heptyl ether. Export the reaction products 2-heptanol and by-products from the reactor and carry out rectification separation to obtain high-purity 2-heptanol.

[0031] Step 2: First, heat the copper-based catalyst to 150 °C for reduction treatment for 18 hours, and load the pretreated catalyst into a fixed-bed tubular reactor. Introduce a nitrogen-hydrogen gas mixture with a hydrogen volume content of 10%. Preheat and vaporize 2-heptanol and feed it into the fixed-bed tubular reactor at a liquid volume hourly space velocity of 0.5 h -1 ~10.0 h -1 Control the reaction temperature at 220 °C and the reaction pressure at 1.0 MPa in the fixed-bed tubular reactor to carry out dehydrogenation reaction. 2-Heptanol dehydrogenates to generate the target product 2-heptanone under the action of the copper-based catalyst. Cool the gas phase at the reactor outlet to 70 °C, input the reaction product 2-heptanone and unreacted 2-heptanol into a rectification column, and carry out vacuum rectification separation to obtain high-purity 2-heptanone, and return the separated unreacted 2-heptanol to the hydration reactor for continuous reaction.

[0032]

Example 4

[0033] Step 1: Mix raw material 1-heptene and water at a molar ratio of 1:4 and input the mixture as a mixed feed into a reaction kettle. ZSM molecular sieve is used as a catalyst with a total weight ratio to 1-heptene and water of 5:10. Heat it to 130 °C under an inert gas atmosphere. The pressure in the reaction kettle reaches 1.4 MPa. React under these conditions for 5 h. After that, when the hydration reaction ends, cool the reaction system to room temperature to obtain the product 2-heptanol and by-products heptanal and heptyl ether. Export the reaction products 2-heptanol and by-products from the reactor and carry out rectification separation to obtain high-purity 2-heptanol.

[0034] Step 2: First, heat the copper-based catalyst to 150 °C for reduction treatment for 18 hours, and load the pretreated catalyst into a fixed-bed tubular reactor. Introduce a nitrogen-hydrogen gas mixture with a hydrogen volume content of 10%. Preheat and vaporize 2-heptanol and feed it into the fixed-bed tubular reactor at a liquid volume hourly space velocity of 0.5 h -1 ~10.0 h -1In the feed fixed-bed tubular reactor, the reaction temperature is controlled at 220 °C and the reaction pressure is 1.0 MPa for dehydrogenation reaction. 2-Heptanol is dehydrogenated to form the target product 2-heptanone under the action of a copper-based catalyst. The gas phase at the reactor outlet is cooled to 70 °C, and the reaction product 2-heptanone and unreacted 2-heptanol are fed into a distillation column. After separation by vacuum distillation, high-purity 2-heptanone is obtained, and the separated unreacted 2-heptanol is returned to the hydration reactor for continuous reaction.

Claims

1. A method for efficiently and scalably preparing 2-heptanone from 1-heptene in two steps, characterized in that: It includes the following two steps: In the first step, 1-heptene is used as a raw material and directly hydrated to obtain 2-heptanol using a specific catalyst under an inert gas atmosphere; The second step is a preparation process for obtaining 2-heptanone by gas phase dehydrogenation under the conditions of a copper-based fixed bed catalyst and a mixed gas containing hydrogen.

2. The method for efficiently and scalably preparing 2-heptanone from 1-heptene in two steps according to claim 1, characterized in that: The specific catalyst includes: one or more of a solid acid catalyst, a liquid acid catalyst, a zeolite catalyst, a molecular sieve catalyst, a transition metal salt or oxygen salt catalyst, an ion exchange resin, and the like.

3. The specific catalyst according to claim 2, characterized in that The solid acid catalyst includes one or more of a solid-supported liquid acid, a phosphate, a solid superacid, etc.; And / or, the liquid acid catalyst includes one or more of sulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, oxalic acid, ionic liquid, etc.; And / or, the zeolite catalyst includes one or more of ZSM-5 zeolite, X zeolite, Y zeolite, β zeolite, mordenite, faujasite, etc.; And / or, the molecular sieve catalyst includes one or more of ZSM series molecular sieves, MCM-22, MCM-36, MCM-49 molecular sieves, β molecular sieves, SAPO-11 molecular sieves, etc.; And / or, the transition metal salt or oxygen salt catalyst includes one or more of transition metal (palladium) salts, cobalt salts, nickel salts, etc.

4. The method for efficiently and scalably preparing 2-heptanone from 1-heptene in two steps according to claim 1, characterized in that: The hydration reaction The following steps are involved: S1: Mixing raw materials 1-heptene and water as mixed feed and inputting them into a reactor, and in an inert gas atmosphere, through the action of a specific catalyst and at a specific reaction temperature and pressure, 1-heptene and water undergo a hydration reaction to generate 2-heptanol and by-products; S2: The reaction product 2-heptanol and by-products are discharged from the reactor and separated by distillation to obtain high-purity 2-heptanol.

5. The method for preparing 2-heptanone in a two-step method using 1-heptene in high efficiency and large scale according to claim 4, characterized in that: The molar ratio of 1-heptene to water in S1 is 1:(1-50), preferably 1:(5-10); And / or, the total weight ratio of the specific catalyst described in S1 to 1-heptene and water is (1-5):10, preferably (2-4):10; And / or, the reaction temperature in S1 is 80-200°C, preferably 100-150°C; and / or, the reaction pressure in S1 is 0.5 to 10.0 MPa, preferably 1 to 3 MPa; And / or, the reaction time in S1 is 0.5 to 4 hours, preferably 1 to 3 hours; And / or, the by-products in S1 include one or more of heptanal, heptyl ether, etc.

6. The method for preparing 2-heptanone in a two-step efficient and large-scale manner from 1-heptene according to claim 4, characterized in that: The single-pass conversion rate of heptene is about 8-20%, the selectivity of 2-heptanol is greater than 99%, and the purity of separated 2-heptanol is greater than 99.5%.

7. The method for preparing 2-heptanone from 1-heptene in two steps efficiently and on a large scale according to claim 1, characterized in that: The gas phase dehydrogenation reaction comprises the following steps: SS1: Perform atmospheric pressure reduction treatment on copper-based catalysts to improve the catalytic effect; SS2: The pretreated catalyst is loaded into a fixed bed tubular reactor, the feed 2-heptanol is preheated and vaporized and heated to the reaction temperature to contact with the catalyst, and the 2-heptanol is dehydrogenated to generate the reaction product 2-heptanone and unreacted 2-heptanol; SS3: The gas phase at the reactor outlet is cooled to a certain temperature, and the reaction product 2-heptanone and unreacted 2-heptanol are input into a distillation tower, and separated by vacuum distillation to obtain high-purity 2-heptanone.

8. The method for preparing 2-heptanone in a large scale using 1-heptene in two steps according to claim 7, characterized in that: SS1 The reduction treatment temperature of the copper-based catalyst is 120-300°C, the reduction time is 6-24 hours, and the mixed gas containing hydrogen contains, in addition to hydrogen, one of nitrogen, helium and argon, and the volume content of hydrogen is 5%-30%; And / or, the liquid volume space velocity of the feed 2-heptanol in SS2 is 0.5h -1 ~10.0h -1 ; And / or, the reaction temperature of SS2 is 150-400°C, preferably 200-250°C; and / or, the reaction pressure of SS2 is 0.01 to 2.0 MPa, preferably 0.2 to 1.5 MPa; and / or, the gas phase cooling temperature at the outlet of the reactor of SS3 is 60 to 80° C., preferably 65 to 75° C.; And / or, the unreacted 2-heptanol obtained after separation by vacuum distillation in SS2 needs to be returned to the hydration reactor to continue the reaction.

9. The method for preparing 2-heptanone in a large scale using 1-heptene in two steps according to claim 7, characterized in that: Within the catalyst life test period of 1000 hours, the single-pass conversion rate of the raw material heptanol-2 was >85%, and the selectivity of 2-heptanone was >99.5%.

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