Preparation method and synthesis method of catalyst for preparing 1-hexyl methyl acetate through addition of n-heptene and acetic acid

Abstract

The invention relates to a preparation method of a catalyst for preparing 1-hexyl methyl acetate by addition of n-heptene and acetic acid, which comprises the following steps: impregnating a carrier sulfonic acid group strong acid resin into a heteropoly acid solution, stirring at 20-50 DEG C for 8-24 hours, and controlling the mass ratio of the sulfonic acid group strong acid resin to the heteropoly acid solution to be (10: 1)-(1: 3); and after stirring, filtering, and drying a solid obtained after filtering at 80-140 DEG C to obtain a finished product. The invention also provides a synthetic method for synthesizing 1-hexyl methyl acetate by using the catalyst. The supported solid acid catalyst can be recycled from reaction slurry through simple liquid-solid separation means such as filtration and centrifugation, and good product selectivity can be obtained.

Description

Technical Field

[0001] This invention belongs to the field of 1-methylhexyl acetate preparation, and particularly relates to a method for preparing a catalyst for the addition reaction of n-heptene with acetic acid to 1-methylhexyl acetate and its synthesis method. Background Technology

[0002] The industrial production of simple esters mostly employs traditional alcohol-esterification reactions, such as ethyl acetate and butyl acetate. The core disadvantage of this method stems from its reversible nature, which inherently limits its reaction efficiency. Because water is continuously generated during the reaction, it must be continuously removed to disrupt the chemical equilibrium. The use of water separators or dehydrating agents directly increases the complexity and energy consumption of the process. The reaction is typically carried out under strong acid (concentrated sulfuric acid in industrial applications) catalysis and reflux heating, which not only introduces equipment corrosion and safety risks, but also significantly increases production costs due to high energy consumption and long reaction times. More importantly, strong acid and high temperature conditions easily trigger a series of side reactions, such as alcohol dehydration and carboxylic acid decomposition, leading to poor product selectivity, reduced yield, and making substrates containing acid-sensitive or easily dehydrated functional groups unsuitable. The cumbersome purification process after the reaction, including neutralization, washing, and distillation, not only involves many steps and significant product loss, but also generates large amounts of difficult-to-treat acidic wastewater, creating severe environmental pressure. From an atom economy perspective, the reaction's use of water as a byproduct also implies low atom utilization.

[0003] Compared to traditional esterification reactions, the olefin addition method for ester production exhibits significant advantages in several dimensions. This process typically operates under milder conditions, using solid acids instead of liquid strong acids as catalysts. This not only substantially reduces energy consumption but also minimizes equipment corrosion and environmental pollution, producing very few byproducts, aligning with the development direction of green chemistry. Following the principle of atom economy, almost all reactant atoms are converted into the target product, fundamentally improving raw material utilization efficiency and avoiding the separation and purification burden caused by water byproducts in traditional methods. Furthermore, from an economic perspective, olefins and carboxylic acids are widely available as raw materials, and the simplified post-processing and lower equipment requirements make this technological route more cost-competitive. Therefore, the olefin addition method represents a more efficient, cleaner, and more controllable new route for ester synthesis.

[0004] However, current research on olefin addition reactions mainly focuses on short-chain olefins such as ethylene and propylene. For example, patents CN109456179A and CN102757341A report methods for synthesizing corresponding carboxylic acid esters by adding dilute ethylene and dilute propylene to acetic acid, respectively. Compared to short-chain olefins, the reaction of long-chain olefins such as heptene with acetic acid suffers from problems such as low reactivity, complex products, and low yields. Reports on their catalytic reaction systems and reaction processes are scarce. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a catalyst for the addition reaction of n-heptene with acetic acid to prepare 1-methylhexyl acetate.

[0006] The present invention also provides a method for synthesizing 1-methylhexyl acetate using a catalyst.

[0007] A method for preparing a catalyst for the addition reaction of n-heptene with acetic acid to prepare 1-methylhexyl acetate includes the following steps:

[0008] (1) Impregnate the carrier sulfonic acid strong acid resin into the heteropoly acid solution and stir at 20~50℃ for 8~24h. The mass ratio of the sulfonic acid strong acid resin impregnation to the heteropoly acid solution is 10:1~1:3.

[0009] (2) After stirring, filter the solid and dry it at 80~140℃ to obtain the finished product.

[0010] Furthermore, the sulfonic acid-based strong acid resin includes one of polystyrene-divinylbenzene sulfonic acid resin and acrylic sulfonic acid resin.

[0011] Furthermore, the polystyrene-divinylbenzenesulfonic acid resin includes one of Amberlyst-36 resin, Amberlyst-45 resin, and D005-II resin.

[0012] Furthermore, the heteropolyacid in the heteropolyacid solution includes one or more of phosphotungstic acid (HPW), silicotungstic acid (HSiW), and phosphomolybdic acid (HPMo).

[0013] Furthermore, the concentration of the heteropolyacid solution is 10-40 wt%, and the active loading of the heteropolyacid is 10-60 wt%.

[0014] The method for synthesizing 1-methylhexyl acetate using a catalyst, wherein the reaction temperature is 60-180℃, the reaction time is 4-20h, the molar ratio of n-heptene to acetic acid is 1:2-1:20, the reaction pressure is 0.1-5MPa, and the catalyst contains 5-40 wt% of the mass of n-heptene.

[0015] The supported solid acid catalyst in this invention can be recovered and reused from the reaction slurry through simple liquid-solid separation methods such as filtration and centrifugation, and good product selectivity can be obtained. The reaction conditions of this invention are milder, and the lower reaction temperature is more conducive to reducing the selectivity of by-products and improving the selectivity of target products. At the same time, compared with the traditional pure heteropolyacid catalysts, the supported catalyst in this invention not only increases the specific surface area of ​​the catalyst, but also enhances its thermal and chemical stability. The sulfonic acid-based strong acid resin has a synergistic effect with the heteropolyacid, which significantly improves the service life of the addition esterification catalyst while improving its catalytic efficiency and maintaining high target product selectivity. Detailed Implementation

[0016] Example 1: A method for preparing a catalyst for the addition reaction of n-heptene with acetic acid to prepare 1-methylhexyl acetate, characterized by comprising the following steps:

[0017] (1) The carrier sulfonic acid strong acid resin was impregnated into the heteropoly acid solution and stirred at 20°C for 8 hours. The mass ratio of the sulfonic acid strong acid resin impregnation to the heteropoly acid solution was 10:1.

[0018] (2) After stirring, filter the solid and dry it at 80°C to obtain the finished product.

[0019] The sulfonic acid-based strong acid resin is polystyrene-divinylbenzene sulfonic acid resin. The polystyrene-divinylbenzene sulfonic acid resin is Amberlyst-36 resin. The heteropoly acid in the heteropoly acid solution is phosphotungstic acid (HPW). The concentration of the heteropoly acid solution is 10 wt%.

[0020] Example 2: A method for preparing a catalyst for the addition reaction of n-heptene with acetic acid to prepare 1-methylhexyl acetate, characterized by comprising the following steps:

[0021] (1) The carrier sulfonic acid strong acid resin is impregnated into the heteropoly acid solution and stirred at 30°C for 16 hours. The mass ratio of the sulfonic acid strong acid resin impregnation to the heteropoly acid solution is 5~2.

[0022] (2) After stirring, filter the solid and dry it at 110°C to obtain the finished product.

[0023] The sulfonic acid-based strong acid resin is an acrylic sulfonic acid resin. The polystyrene-divinylbenzene sulfonic acid resin is Amberlyst-45 resin. The heteropoly acid in the heteropoly acid solution is silicotungstic acid (HSiW). The concentration of the heteropoly acid solution is 20 wt%.

[0024] Example 3: A method for preparing a catalyst for the addition reaction of n-heptene with acetic acid to prepare 1-methylhexyl acetate, characterized by comprising the following steps:

[0025] (1) The carrier sulfonic acid strong acid resin was impregnated into the heteropoly acid solution and stirred at 50°C for 24 hours. The mass ratio of the sulfonic acid strong acid resin impregnation to the heteropoly acid solution was 1:3.

[0026] (2) After stirring, filter the solid and dry it at 140°C to obtain the finished product.

[0027] The sulfonic acid-based strong acid resin is polystyrene-divinylbenzene sulfonic acid resin. The polystyrene-divinylbenzene sulfonic acid resin is Amberlyst-45 resin. The heteropoly acid in the heteropoly acid solution is phosphomolybdic acid (HPMo). The concentration of the heteropoly acid solution is 40 wt%.

[0028] Example 4: Referring to Example 1, the sulfonic acid-based strong acid resin includes one of polystyrene-divinylbenzene sulfonic acid resin and acrylic sulfonic acid resin. The polystyrene-divinylbenzene sulfonic acid resin includes one of Amberlyst-36 resin, Amberlyst-45 resin, and D005-II resin. The heteropolyacid in the heteropolyacid solution includes one or more of phosphotungstic acid (HPW), silicotungstic acid (HSiW), and phosphomolybdic acid (HPMo).

[0029] Example 5: A method for synthesizing 1-methylhexyl acetate using the catalyst of Example 1, wherein the reaction temperature is 60°C, the reaction time is 4 h, the molar ratio of n-heptene to acetic acid is 1:2, the reaction pressure is 0.1 MPa, and the catalyst contains 5 wt% n-heptene.

[0030] Example 6: Synthesis of 1-methylhexyl acetate using the catalyst of Example 2, wherein the reaction temperature was 120°C, the reaction time was 12 h, the molar ratio of n-heptene to acetic acid was 1:10, the reaction pressure was 3 MPa, and the catalyst contained 20 wt% n-heptene.

[0031] Example 7: A method for synthesizing 1-methylhexyl acetate using the catalyst of Example 3, wherein the reaction temperature is 180°C, the reaction time is 20 h, the molar ratio of n-heptene to acetic acid is 1:20, the reaction pressure is 5 MPa, and the catalyst contains 40 wt% n-heptene.

[0032] Comparative Example 1: Referring to Example 5, the catalyst used in Example 5 was replaced with phosphotungstic acid of the same mass as that used in Example 1, while the rest of the operation remained unchanged.

[0033] Comparative Example 2: Referring to Example 5, the catalyst in Example 5 was replaced with the same mass of sulfonic acid-based strong acid resin as the support sulfonic acid-based strong acid resin in Example 1, while the rest of the operation remained unchanged.

[0034] Comparative Example 3: Referring to Example 5, the catalyst of Example 5 was replaced with a solid superacid of the same mass. / The rest of the operations remain unchanged.

[0035] Comparative Example 4: Referring to Example 5, the sulfonic acid-based strong acid resin in Example 1 was replaced with activated carbon to obtain the replaced catalyst. Example 5 was carried out using the replaced catalyst, and the other operations remained unchanged.

[0036] Comparative Example 5: Referring to Example 5, the sulfonic acid-based strong acid resin support in Example 1 was replaced with Hβ molecular sieve to obtain the replaced catalyst. Example 5 was carried out using the replaced catalyst, and the other operations remained unchanged.

[0037] Comparative Example 6: Referring to Example 5, the sulfonic acid-based strong acid resin support in Example 1 was replaced with HZSM-5 molecular sieve to obtain the replaced catalyst. Example 5 was carried out using the replaced catalyst, and the other operations remained unchanged.

[0038]

[0039] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of 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 a catalyst for the addition reaction of n-heptene with acetic acid to prepare 1-methylhexyl acetate, characterized in that, Includes the following steps: (1) Impregnate the carrier sulfonic acid strong acid resin into the heteropoly acid solution and stir at 20~50℃ for 8~24h. The mass ratio of the sulfonic acid strong acid resin impregnation to the heteropoly acid solution is 10:1~1:

3. (2) After stirring, filter the solid and dry it at 80~140℃ to obtain the finished product.

2. The method for preparing the catalyst for the addition reaction of n-heptene with acetic acid to prepare 1-methylhexyl acetate according to claim 1, characterized in that, The sulfonic acid-based strong acid resin includes one of polystyrene-divinylbenzene sulfonic acid resin and acrylic sulfonic acid resin.

3. The method for preparing the catalyst for the addition reaction of n-heptene with acetic acid to prepare 1-methylhexyl acetate according to claim 1, characterized in that, The polystyrene-divinylbenzenesulfonic acid resin includes one of Amberlyst-36 resin, Amberlyst-45 resin, and D005-II resin.

4. The method for preparing the catalyst for the addition reaction of n-heptene with acetic acid to prepare 1-methylhexyl acetate according to claim 1, characterized in that, The heteropolyacid solution contains one or more of phosphotungstic acid (HPW), silicotungstic acid (HSiW), and phosphomolybdic acid (HPMo).

5. The method for preparing the catalyst for the addition reaction of n-heptene with acetic acid to prepare 1-methylhexyl acetate according to claim 1, characterized in that, The concentration of the heteropolyacid solution is 10~40 wt%.

6. A method for synthesizing 1-methylhexyl acetate using the catalyst according to any one of claims 1 to 5, characterized in that, The reaction temperature is 60~180℃, the reaction time is 4~20h, the molar ratio of n-heptene to acetic acid is 1:2~1:20, the reaction pressure is 0.1~5MPa, and the catalyst is 5~40 wt% of the mass of n-heptene.

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