A process for the production of 1,2-hexanediol from 1-hexene based on a fixed bed reactor

Abstract

The present application relates to a kind of method for producing 1,2-hexanediol from 1-hexene based on fixed bed reactor, belong to chemical production technical field.The method includes the following steps: fixed bed catalyst is loaded into fixed bed reactor;1-hexene, solvent and hydrogen peroxide are passed into fixed bed reactor, and contact with fixed bed catalyst and carry out epoxidation reaction;1,2-epoxyhexane is obtained by distillation separation;1,2-epoxyhexane is hydrolyzed in acidic solution, i.e. 1,2-hexanediol is prepared.Fixed bed catalyst uses TS-2 molecular sieve as active component, its preparation method is as follows: TS-2 molecular sieve is mixed with pore forming agent uniformly, and binder is added and kneaded uniformly, then extrusion molding, drying, calcination obtain the fixed bed catalyst.Compared with prior art, the present application creates TS-2 molecular sieve with larger pore as active component, more can adapt to the epoxidation of 1-hexene, more can meet the production demand of the present application production 1,2-hexanediol.

Description

Technical Field

[0001] This invention belongs to the field of chemical production technology, and in particular relates to a method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor. Background Technology

[0002] 1,2-Hexanediol (chemical formula C6H) 14 O2 is an important fine chemical raw material. It is miscible with water and can be mixed with a variety of organic compounds in any proportion. It has antibacterial and preservative activities and can be used in inks for color inkjet printers, high-end cosmetics, and synthetic raw materials in the pharmaceutical industry.

[0003] In the printing ink industry, 1,2-hexanediol, when added to inkjet printing inks, can enhance ink performance, significantly improving ozone resistance, gloss, and uniformity. By enhancing the physicochemical properties of inks, 1,2-hexanediol has become an important additive in inkjet printing, driving improvements in print quality and cost efficiency. The core applications of 1,2-hexanediol are concentrated in the cosmetics and personal care industries, primarily due to its mild and safe properties. In skincare, haircare, and body care products, 1,2-hexanediol is widely used as a preservative-free alternative. As a modifier for high-performance coatings (such as polyurethane and acrylic coatings), 1,2-hexanediol can improve coating flexibility, water resistance, and adhesion. In the pharmaceutical industry, 1,2-hexanediol is mainly used as a key chemical raw material for the synthesis of downstream drug active ingredients. In the field of biomaterials, 1,2-hexanediol is used to prepare biocompatible polymers for applications in drug delivery systems and tissue engineering. In addition, 1,2-hexanediol, as a highly effective and low-irritant preservative and moisturizer, is in high demand and its applications are expanding into emerging fields such as baby care and organic products.

[0004] Currently, the main industrial synthesis methods for 1,2-hexanediol include the halohydrin method, the organic acid peroxide method, and the hydrogen peroxide oxidation method. The halohydrin method is an early, traditional production process. Using hexene as a raw material, it first reacts with hydrogen halides (such as HBr) to generate halohexanol, then hydrolyzes and cyclizes it under alkaline conditions to form an epoxide intermediate. Finally, it undergoes acid-catalyzed hydrolysis to open the ring, generating 1,2-hexanediol. However, this process involves many side reactions, poor selectivity, severe corrosion of equipment by hydrogen halides, high hazard, and generates large amounts of difficult-to-treat waste, causing serious pollution. This process has been phased out. The peroxy-organic acidification method uses peroxy-organic acids as oxidants, or the organic acid reacts with hydrogen peroxide first, then reacts with hexene to form epoxide. Due to the presence of acid and water in the system, epoxide directly undergoes ring-opening to generate 1,2-hexanediol. Patents such as CN1465556A, CN107903146A, and CN1228294C all employ this method. Because this method uses a large amount of organic acid as a medium, it causes severe corrosion to the equipment, is difficult to recover, causes serious pollution, and has many side reactions in the organic acid system, resulting in poor product selectivity.

[0005] The hydrogen peroxide oxidation method utilizes the properties of a specific catalyst to directly react hexene with hydrogen peroxide to produce epoxide, which is then hydrolyzed to yield 1,2-hexanediol. This method offers advantages such as high reaction selectivity, mild solvent for easy recovery, and environmental friendliness. The specific catalyst used in this method is typically TS-1 molecular sieve, which has an MFI structure and belongs to the eight-membered ring orthorhombic crystal system. However, due to the small pore size of TS-1 molecular sieves, diffusion of high-carbon molecules is hindered. Therefore, TS-1 molecular sieves are commonly used in the epoxidation of low-carbon olefins, limiting their application. For example, CN117861722A discloses a titanium-silicon molecular sieve catalyst that modifies TS-1 molecular sieves to expand its pores for application in the catalytic oxidation of 1-hexene. However, the conversion rate of 1-hexene is only 35-60%, which still needs to be improved; in addition, the preparation process of this TS-1 molecular sieve catalyst is complex and difficult to control stably; and the catalyst does not change the basic characteristics of TS-1 molecular sieve, so it has little reference value for the industrial production of 1,2-hexanediol.

[0006] Therefore, a new method for producing 1,2-hexanediol based on novel molecular sieve catalysts and via a 1-hexene fixed bed still needs to be developed. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies where TS-1 molecular sieve catalysts are not suitable for the production of 1,2-hexanediol, and to provide a method for producing 1,2-hexanediol from 1-hexene based on a fixed-bed reactor.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] This invention provides a method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor. The method includes the following steps: loading a fixed-bed catalyst into a fixed-bed reactor; introducing 1-hexene, a solvent, and hydrogen peroxide into the fixed-bed reactor and contacting them with the fixed-bed catalyst to carry out an epoxidation reaction; obtaining 1,2-epoxyhexane by distillation; and hydrolyzing 1,2-epoxyhexane in an acidic solution to obtain 1,2-hexanediol.

[0010] The fixed-bed catalyst uses TS-2 molecular sieve as the active component and is prepared as follows: TS-2 molecular sieve is mixed evenly with a pore-forming agent, and a binder is added and kneaded evenly. Then, it is extruded, dried, and calcined to obtain the fixed-bed catalyst.

[0011] Furthermore, the packing density of the fixed-bed catalyst in the fixed-bed reactor is 0.4~0.8 g / mL.

[0012] Furthermore, the mass hourly space velocity (HHSV) of the 1-hexene is 0.1–2.0 h⁻¹. -1 .

[0013] Furthermore, the flow rate ratio of 1-hexene, solvent, and hydrogen peroxide is 1:(2~8):(1.3~1.4).

[0014] Furthermore, the solvent is any one or more of methanol, ethanol, tert-butanol, and acetonitrile.

[0015] Furthermore, the concentration of H2O2 in the hydrogen peroxide is 25~35wt%.

[0016] Furthermore, the epoxidation reaction is carried out at a temperature of 20~80 °C.

[0017] Furthermore, the pressure of the epoxidation reaction is 0~2.0 MPa.

[0018] Furthermore, the acidic solution is a dilute sulfuric acid solution.

[0019] Furthermore, the TS-2 molecular sieve has a MEL-type topology, consisting of a regular pore system composed of two sets of mutually perpendicular cylindrical ten-membered rings.

[0020] Furthermore, the TiO2 content in the TS-2 molecular sieve is 1.0~6.0 wt%.

[0021] Furthermore, the BET specific surface area of ​​the TS-2 molecular sieve is not less than 500 m². 2 / g.

[0022] Furthermore, the total pore volume of the TS-2 molecular sieve is not less than 0.45 cm³. 3 / g.

[0023] Furthermore, the TS-2 molecular sieve is prepared by the following method: a silicon source and a titanium source are mixed evenly, and a template agent is added under stirring conditions to ensure that the molar ratio of silicon source, titanium source and template agent is 1: (0.025~0.07): (0.1-0.2); after stirring and mixing, the mixture is transferred to a crystallization kettle and crystallized under heating conditions; after cooling, solid-liquid separation is performed, and the solid product is dried to obtain the TS-2 molecular sieve containing the template agent.

[0024] Furthermore, the silicon source is at least one of tetraethyl orthosilicate and silica sol.

[0025] Furthermore, the titanium source is at least one of tetrabutyl titanate and tetraethyl titanate.

[0026] Furthermore, the template agent is at least one of tetrabutylammonium hydroxide and tetrabutylammonium bromide.

[0027] Furthermore, the crystallization temperature is 150~200℃.

[0028] Furthermore, the crystallization time is 24~72h.

[0029] Furthermore, the mass content of the TS-2 molecular sieve in the fixed-bed catalyst is 30~95wt%.

[0030] Furthermore, the pore-forming agent is any one or more of guar gum powder, methylcellulose, and citric acid.

[0031] Furthermore, the mass ratio of the pore-forming agent to the TS-2 molecular sieve is (0.01~0.2):1.

[0032] Furthermore, the adhesive is either silica sol or tetraethyl orthosilicate.

[0033] Furthermore, the SiO2 content in the binder is 5-70% of the mass of the fixed-bed catalyst.

[0034] Furthermore, the calcination temperature is 500~600 ℃.

[0035] Furthermore, the roasting time is 2 to 6 hours.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) In the method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor, the present invention abandons the traditional TS-1 molecular sieve and innovatively uses TS-2 molecular sieve with larger pores as the active component. Its specific surface area and pore volume are significantly better than those of the TS-1 molecular sieve with MFI structure. The diffusion path is shorter and it is more adaptable to the epoxidation reaction of high carbon olefins (such as 1-hexene), and it can better meet the production requirements of the present invention for producing 1,2-hexanediol.

[0038] (2) The present invention uses a fixed-bed catalyst with TS-2 molecular sieve as active component. Compared with the traditional TS-1 molecular sieve fixed-bed catalyst, it has a higher 1-hexene conversion rate and 1,2-hexanediol selectivity, and also has a higher hydrogen peroxide utilization rate.

[0039] (3) The present invention can effectively improve the conversion rate of raw materials and the selectivity of products, while having a longer lifespan, thereby meeting the requirements of fixed bed catalysts and providing a stronger guarantee for continuous industrial production. Attached Figure Description

[0040] Figure 1 The XRD pattern of the TS-2 molecular sieve prepared in Example 1 of this invention is shown. Detailed Implementation

[0041] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0042] This invention provides a method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor. The method includes the following steps: loading a fixed-bed catalyst into a fixed-bed reactor; introducing 1-hexene, a solvent, and hydrogen peroxide into the fixed-bed reactor and contacting them with the fixed-bed catalyst to carry out an epoxidation reaction; obtaining 1,2-epoxyhexane by distillation; and hydrolyzing 1,2-epoxyhexane in an acidic solution to obtain 1,2-hexanediol.

[0043] The fixed-bed catalyst uses TS-2 molecular sieve as the active component and is prepared as follows: TS-2 molecular sieve is mixed evenly with a pore-forming agent, and a binder is added and kneaded evenly. Then, it is extruded, dried, and calcined to obtain the fixed-bed catalyst.

[0044] In some specific embodiments, the packing density of the fixed-bed catalyst in the fixed-bed reactor is 0.4~0.8 g / mL.

[0045] In some specific embodiments, the mass hourly space velocity (HHSV) of the 1-hexene is 0.1 to 2.0 h⁻¹. -1 .

[0046] In some specific embodiments, the flow rate ratio of 1-hexene, solvent and hydrogen peroxide is 1:(2~8):(1.3~1.4), that is, the mass ratio of solvent to 1-hexene is 2~8.

[0047] In some specific embodiments, the solvent is any one or more of methanol, ethanol, tert-butanol, and acetonitrile.

[0048] In some specific embodiments, the concentration of H2O2 in the hydrogen peroxide is 25-35 wt%, preferably 30 wt%.

[0049] In some specific embodiments, the temperature of the epoxidation reaction is 20~80 ℃, preferably 40~80 ℃.

[0050] In some specific embodiments, the pressure of the epoxidation reaction is 0~2.0 MPa, preferably 0.1~2.0 MPa.

[0051] In some specific embodiments, the acidic solution is a dilute sulfuric acid solution.

[0052] In some specific embodiments, the TS-2 molecular sieve has a MEL-type topology, consisting of a regular pore system composed of two sets of mutually perpendicular cylindrical ten-membered rings.

[0053] In some specific embodiments, the TiO2 content in the TS-2 molecular sieve is 1.0~6.0wt%, preferably 3.0~5.0wt%.

[0054] In some specific embodiments, the BET specific surface area of ​​the TS-2 molecular sieve is not less than 500 m². 2 / g.

[0055] In some specific embodiments, the total pore volume of the TS-2 molecular sieve is not less than 0.45 cm³. 3 / g.

[0056] In some specific embodiments, the TS-2 molecular sieve is prepared by the following method: a silicon source and a titanium source are mixed evenly, and a template agent is added under stirring conditions to ensure that the molar ratio of silicon source, titanium source and template agent is 1: (0.025~0.07): (0.1-0.2); after stirring and mixing, the mixture is transferred to a crystallization kettle and crystallized under heating conditions; after cooling, solid-liquid separation is performed, and the solid product is dried to obtain the TS-2 molecular sieve containing the template agent.

[0057] In some more specific embodiments, the molar ratio of the silicon source, titanium source and template agent is preferably 1: (0.035~0.059): (0.14~0.18).

[0058] In some more specific embodiments, the silicon source is at least one of tetraethyl orthosilicate and silica sol, preferably tetraethyl orthosilicate.

[0059] In some more specific embodiments, the titanium source is at least one of tetrabutyl titanate and tetraethyl titanate, preferably tetraethyl titanate.

[0060] In some more specific embodiments, the template agent is at least one of tetrabutylammonium hydroxide and tetrabutylammonium bromide, preferably tetrabutylammonium hydroxide.

[0061] In some more specific embodiments, the crystallization temperature is 150~200°C.

[0062] In some more specific embodiments, the crystallization time is 24 to 72 hours.

[0063] In some specific embodiments, the TS-2 molecular sieve has a mass content of 30-95 wt% in the fixed-bed catalyst, preferably 50-85 wt%.

[0064] In some specific embodiments, the pore-forming agent is any one or more of guar gum powder, methylcellulose, and citric acid.

[0065] In some specific embodiments, the mass ratio of the pore-forming agent to the TS-2 molecular sieve is (0.01~0.2):1, preferably (0.02~0.1):1.

[0066] In some specific embodiments, the binder is either silica sol or tetraethyl orthosilicate.

[0067] In some specific embodiments, the SiO2 content in the binder is 5-70% of the mass of the fixed-bed catalyst, preferably 15-50%.

[0068] In some specific embodiments, the calcination temperature is 500~600 ℃.

[0069] In some specific embodiments, the roasting time is 2 to 6 hours.

[0070] In the preparation process of 1,2-hexanediol using the 1-hexene hydrogen peroxide oxidation method in this invention, the fixed-bed catalyst abandons the traditional TS-1 molecular sieve and innovatively adopts TS-2 molecular sieve with larger pores as the active component.

[0071] Specifically, TS-1 molecular sieve has an MFI-type topology, consisting of Z-shaped intersecting channels composed of eight-membered and ten-membered rings. Its diffusion path is relatively long and its acidity is strong, having little impact on the epoxidation reaction of low-carbon olefins. However, as the olefin molecule size gradually increases, its diffusion efficiency decreases significantly due to the influence of its pore size and acidity, leading to increased side reactions and coking. In contrast, the TS-2 molecular sieve selected in this invention has a MEL-type topology, consisting of a regular pore system composed of two sets of mutually perpendicular cylindrical ten-membered rings. Its specific surface area and pore volume are significantly larger than those of the MFI-type molecular sieve, resulting in a shorter diffusion path. It also possesses milder acidity, reducing the likelihood of secondary reactions and making it more suitable for the epoxidation reaction of high-carbon olefins. This effectively improves the conversion rate of raw materials and the selectivity of products, while also having a longer lifespan, thus meeting the requirements of fixed-bed catalysts and providing strong support for continuous industrial production.

[0072] Meanwhile, because low-carbon olefin molecules are smaller, they can more easily enter the catalyst channels and bind to active sites, and the resulting epoxides are also smaller and diffuse out of the channels more easily. High-carbon olefin molecules, on the other hand, are larger and enter the narrow molecular sieve channels more slowly. The resulting epoxides are also difficult to remove from the channels, leading to channel blockage and reduced catalyst efficiency. Furthermore, the slower entry and exit of high-carbon olefins and their epoxides results in longer residence times, increasing the likelihood of side reactions and more severe catalyst coking, thus affecting catalyst lifespan.

[0073] Each of the above embodiments can be implemented individually, or in any combination of two or more. The following detailed description of specific examples will further illustrate these embodiments.

[0074] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0075] The TS-1 molecular sieve used in Comparative Example 1 was sourced from Shanghai Yuying Materials Technology Co., Ltd., and its specific surface area was approximately 450 m² / g as determined by low-temperature nitrogen adsorption. 2 / g, total pore volume is approximately 0.42cm³. 3 / g.

[0076] The TS-2 molecular sieves used in Examples 1-6 can be commercially available TS-2 molecular sieves, or they can be prepared using the following methods:

[0077] Tetraethyl orthosilicate (TEOS) and tetraethyl titanate (TBOT) are mixed evenly in a certain proportion. Under vigorous stirring, 10wt% tetrabutylammonium hydroxide solution (TBAOH) is slowly added and stirred continuously for 2 hours. The slurry is then slowly heated to 80℃ to remove the alcohol generated by the hydrolysis of TEOS and TBOT in the solution.

[0078] The slurry was transferred to a stainless steel crystallization kettle, which was then sealed. Under stirring, the temperature was gradually increased to 170°C and maintained for 48 hours. After cooling, the mother liquor was filtered, washed, and dried to obtain TS-2 molecular sieve containing template agent.

[0079] Example 1

[0080] This embodiment provides a method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor. The specific method is as follows:

[0081] (1) Preparation of TS-2 molecular sieve:

[0082] 400g of tetraethyl orthosilicate (TEOS) and 18.1g of tetraethyl titanate (TBOT) were mixed evenly. Under vigorous stirring, 700g of 10wt% tetrabutylammonium hydroxide aqueous solution (TBAOH) was slowly added and stirred continuously for 2 hours. The slurry was slowly heated to 80℃ to remove alcohol from the solution. The stirred mixture was transferred to a stainless steel crystallization kettle, which was sealed. Under stirring, the temperature was gradually increased to 170℃ and maintained for 48 hours. After cooling, the reaction solution was filtered. The solid product was washed and dried to obtain TS-2 molecular sieve containing template agent. The mass content of TiO2 in the molecular sieve was 3.5%.

[0083] Figure 1 The XRD pattern of the prepared TS-2 molecular sieve is shown. Figure 1 It can be seen that the TS-2 molecular sieve samples prepared in this embodiment showed characteristic peaks of the MEL structure at 2θ of 8.0°, 8.9°, 23.2°, 24.5° and 45.3°, respectively, but no characteristic peak of the MFI structure was found at 25.5°, which proves that the molecular sieve material synthesized in this invention is a relatively pure TS-2 molecular sieve with a MEL structure.

[0084] Furthermore, this invention, through low-temperature nitrogen adsorption determination, yielded a BET specific surface area of ​​576 m² for the TS-2 molecular sieve sample prepared in this embodiment. 2 / g, total pore volume is 0.51 cm³ 3 / g.

[0085] (2) Preparation of fixed-bed catalysts:

[0086] 76.0 g of TS-2 molecular sieve (containing template agent, TiO2 content of 3.5%) was thoroughly mixed with 2.0 g of methylcellulose, and then 107.1 g of tetraethyl orthosilicate and 40.0 g of water were added. After kneading until uniform, the mixture was extruded into strips using an extruder. The strips were then dried in a vacuum oven at 80 °C for 12 h, and finally calcined at 550 °C for 4 h to obtain strip-shaped fixed-bed catalyst 1. The solid content of SiO2 was 30 wt%.

[0087] (3) Production of 1,2-hexanediol:

[0088] 10.0 g of fixed-bed catalyst 1 was charged into a 20 mL fixed-bed reactor. The reactor temperature was raised to 60 °C, and the pressure was maintained at 0.3 MPa. 1-Hexene, tert-butanol, and 30% hydrogen peroxide were introduced into the reactor at flow rates of 10.0 g / h, 25.0 g / h, and 13.47 g / h, respectively. The reaction products were collected, and the solvent and excess 1-hexene were recovered by distillation to obtain 1,2-epoxyhexane.

[0089] 1,2-Epoxyhexane was hydrolyzed in a 1.0% dilute sulfuric acid solution at a temperature of 70°C for 1 hour to yield 1,2-hexanediol.

[0090] The conversion rate of 1-hexene was calculated to be 95.1%, the selectivity of 1,2-hexanediol was 96.6%, and the effective utilization rate of hydrogen peroxide was 91.2%.

[0091] Example 2

[0092] This embodiment provides a method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor. The specific method is as follows:

[0093] (1) Preparation of TS-2 molecular sieve:

[0094] 400g of tetraethyl orthosilicate (TEOS) and 25.8g of tetraethyl titanate (TBOT) were mixed evenly. Under vigorous stirring, 700g of 10wt% tetrabutylammonium hydroxide aqueous solution (TBAOH) was slowly added and stirred continuously for 2 hours. The slurry was slowly heated to 80℃ to remove alcohol from the solution. The stirred mixture was transferred to a stainless steel crystallization kettle, which was then sealed. Under stirring, the temperature was gradually increased to 170℃ and maintained for 48 hours. After cooling, the reaction solution was filtered. The solid product was washed and dried to obtain TS-2 molecular sieve containing template agent. The mass content of TiO2 in the molecular sieve was 5.0%.

[0095] (2) Preparation of fixed-bed catalysts:

[0096] 87.0 g of TS-2 molecular sieve (TiO2 content 5.0% by mass) was thoroughly mixed with 5.0 g of guar gum powder, and 66.7 g of 30% silica sol was added. After kneading until uniform, the mixture was extruded into strips. The strips were then dried in an oven at 120℃ for 12 h and finally calcined at 550℃ for 4 h to obtain strip-shaped fixed-bed catalyst 2. The solid content of SiO2 was 20 wt%.

[0097] (3) Production of 1,2-hexanediol:

[0098] 10.0 g of fixed-bed catalyst 2 was loaded into a 20 mL fixed-bed reactor. The reactor temperature was raised to 50 °C, and the pressure was maintained at 0.2 MPa. 1-Hexene, methanol, and 30% hydrogen peroxide were introduced into the reactor at flow rates of 6.0 g / h, 30.0 g / h, and 8.08 g / h, respectively. The reaction products were collected, and the solvent and excess 1-hexene were recovered by distillation to obtain 1,2-epoxyhexane.

[0099] 1,2-Epoxyhexane was hydrolyzed in a 1.0% dilute sulfuric acid solution at 25°C for 1 hour to yield 1,2-hexanediol.

[0100] Calculations showed that the conversion rate of 1-hexene was 97.5%, the selectivity of 1,2-hexanediol was 98.2%, and the effective utilization rate of hydrogen peroxide was 95.8%.

[0101] Example 3

[0102] This embodiment provides a method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor. The specific method is as follows:

[0103] (1) Preparation of TS-2 molecular sieve:

[0104] 400g of tetraethyl orthosilicate (TEOS) and 15.5g of tetraethyl titanate (TBOT) were mixed evenly. Under vigorous stirring, 700g of 10wt% tetrabutylammonium hydroxide aqueous solution (TBAOH) was slowly added and stirred continuously for 2 hours. The slurry was slowly heated to 80℃ to remove alcohol from the solution. The stirred mixture was transferred to a stainless steel crystallization kettle, which was then sealed. Under stirring, the temperature was gradually increased to 170℃ and maintained for 48 hours. After cooling, the reaction solution was filtered. The solid product was washed and dried to obtain TS-2 molecular sieve containing template agent. The mass content of TiO2 in the molecular sieve was 3.0%.

[0105] (2) Preparation of fixed-bed catalysts:

[0106] 92.4 g of TS-2 molecular sieve (TiO2 content 3.0%) was thoroughly mixed with 1.5 g of citric acid, then 53.6 g of tetraethyl orthosilicate and 20.0 g of water were added. After kneading until uniform, the mixture was extruded into strips. The strips were then dried in a vacuum oven at 80 °C for 12 h, and finally calcined at 550 °C for 4 h to obtain strip-shaped fixed-bed catalyst 3. The solid content of SiO2 in this catalyst was 15 wt%.

[0107] (3) Production of 1,2-hexanediol:

[0108] 10.0 g of fixed-bed catalyst 3 was loaded into a 20 mL fixed-bed reactor. The reactor temperature was raised to 70 °C, and the pressure was maintained at 1.0 MPa. 1-Hexene, ethanol, and 30% hydrogen peroxide were introduced into the reactor at flow rates of 15.0 g / h, 45.0 g / h, and 20.21 g / h, respectively. The reaction products were collected, and the solvent and excess 1-hexene were recovered by distillation to obtain 1,2-epoxyhexane.

[0109] 1,2-Epoxyhexane was hydrolyzed in a 1.0% dilute sulfuric acid solution at 25°C for 1 hour to yield 1,2-hexanediol.

[0110] Calculations showed that the conversion rate of 1-hexene was 97.3%, the selectivity of 1,2-hexanediol was 95.4%, and the effective utilization rate of hydrogen peroxide was 92.8%.

[0111] Example 4

[0112] This embodiment provides a method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor. The specific method is as follows:

[0113] (1) Preparation of TS-2 molecular sieve:

[0114] 400g of tetraethyl orthosilicate (TEOS) and 20.6g of tetraethyl titanate (TBOT) were mixed evenly. Under vigorous stirring, 700g of 10wt% tetrabutylammonium hydroxide aqueous solution (TBAOH) was slowly added and stirred continuously for 2 hours. The slurry was slowly heated to 80℃ to remove alcohol from the solution. The stirred mixture was transferred to a stainless steel crystallization kettle, which was then sealed. Under stirring, the temperature was gradually increased to 170℃ and maintained for 48 hours. After cooling, the reaction solution was filtered. The solid product was washed and dried to obtain TS-2 molecular sieve containing template agent, with a TiO2 content of 4.0% by mass.

[0115] (2) Preparation of fixed-bed catalysts:

[0116] 81.5 g of TS-2 molecular sieve (TiO2 content 4.0%) was thoroughly mixed with 4.0 g of guar gum powder, and 83.3 g of silica sol with a concentration of 30 wt% was added. After kneading until uniform, the mixture was extruded into strips. The strips were then dried in an oven at 120℃ for 12 h and finally calcined at 550℃ for 4 h to obtain strip-shaped fixed-bed catalyst 4. The SiO2 content in this catalyst was 25%.

[0117] (3) Production of 1,2-hexanediol:

[0118] 10.0 g of fixed-bed catalyst 4 was loaded into a 20 mL fixed-bed reactor. The reactor temperature was raised to 40 °C, and the pressure was maintained at 0.1 MPa. 1-Hexene, methanol, and 30% hydrogen peroxide were introduced into the reactor at flow rates of 3.0 g / h, 10.0 g / h, and 4.04 g / h, respectively. The reaction products were collected, and the solvent and excess 1-hexene were recovered by distillation to obtain 1,2-epoxyhexane.

[0119] 1,2-Epoxyhexane was hydrolyzed in a 1.0% dilute sulfuric acid solution at 25°C for 1 hour to yield 1,2-hexanediol.

[0120] Calculations showed that the conversion rate of 1-hexene was 98.0%, the selectivity of 1,2-hexanediol was 98.6%, and the effective utilization rate of hydrogen peroxide was 96.6%.

[0121] Example 5

[0122] This embodiment provides a method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor. The specific method is as follows:

[0123] (1) Preparation of TS-2 molecular sieve:

[0124] 400g of tetraethyl orthosilicate (TEOS) and 23.2g of tetraethyl titanate (TBOT) were mixed evenly. Under vigorous stirring, 700g of 10wt% tetrabutylammonium hydroxide aqueous solution (TBAOH) was slowly added and stirred continuously for 2 hours. The slurry was slowly heated to 80℃ to remove alcohol from the solution. The stirred mixture was transferred to a stainless steel crystallization kettle, which was sealed. Under stirring, the temperature was gradually increased to 170℃ and maintained for 48 hours. After cooling, the reaction solution was filtered. The solid product was washed and dried to obtain TS-2 molecular sieve containing template agent. The mass content of TiO2 in the molecular sieve was 4.5%.

[0125] (2) Preparation of fixed-bed catalysts:

[0126] 54.3 g of TS-2 molecular sieve (TiO2 content 4.5% by mass) was thoroughly mixed with 5.0 g of guar gum powder, and 166.7 g of 30% silica sol was added. After kneading until uniform, the mixture was extruded into strips. The strips were then dried in an oven at 120℃ for 12 h and finally calcined at 550℃ for 4 h to obtain strip-shaped fixed-bed catalyst 5. The SiO2 content in this catalyst was 50%.

[0127] (3) Production of 1,2-hexanediol:

[0128] 10.0 g of fixed-bed catalyst 5 was loaded into a 20 mL fixed-bed reactor. The reactor temperature was raised to 80 °C, and the pressure was maintained at 2.0 MPa. 1-Hexene, acetonitrile, and 30% hydrogen peroxide were introduced into the reactor at flow rates of 20.0 g / h, 160.0 g / h, and 26.94 g / h, respectively. The reaction products were collected, and the solvent and excess 1-hexene were recovered by distillation to obtain 1,2-epoxyhexane.

[0129] 1,2-Epoxyhexane was hydrolyzed in a 1.0% dilute sulfuric acid solution at 25°C for 1 hour to yield 1,2-hexanediol.

[0130] Calculations showed that the conversion rate of 1-hexene was 96.6%, the selectivity of 1,2-hexanediol was 93.1%, and the effective utilization rate of hydrogen peroxide was 89.9%.

[0131] Example 6

[0132] This embodiment provides a method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor. The specific method is as follows:

[0133] (1) Preparation of TS-2 molecular sieve:

[0134] 400g of tetraethyl orthosilicate (TEOS) and 25.8g of tetraethyl titanate (TBOT) were mixed evenly. Under vigorous stirring, 700g of 10wt% tetrabutylammonium hydroxide aqueous solution (TBAOH) was slowly added and stirred continuously for 2 hours. The slurry was slowly heated to 80℃ to remove alcohol from the solution. The stirred mixture was transferred to a stainless steel crystallization kettle, which was then sealed. Under stirring, the temperature was gradually increased to 170℃ and maintained for 48 hours. After cooling, the reaction solution was filtered. The solid product was washed and dried to obtain TS-2 molecular sieve containing template agent, with a TiO2 content of 5.0% by mass in the molecular sieve.

[0135] (2) Preparation of fixed-bed catalysts:

[0136] 87.0 g of TS-2 molecular sieve (TiO2 content 5.0%) was thoroughly mixed with 2.0 g of methylcellulose, then 71.4 g of tetraethyl orthosilicate and 28.0 g of water were added. After kneading until homogeneous, the mixture was extruded into strips. The strips were then dried in a vacuum oven at 80 °C for 12 h, and finally calcined at 550 °C for 4 h to obtain strip-shaped fixed-bed catalyst 6. The SiO2 content in this catalyst was 20%.

[0137] (3) Production of 1,2-hexanediol:

[0138] 10.0 g of fixed-bed catalyst 6 was loaded into a 20 mL fixed-bed reactor. The reactor temperature was raised to 50 °C, and the pressure was maintained at 0.2 MPa. 1-Hexene, methanol, and 30% hydrogen peroxide were introduced into the reactor at flow rates of 8.0 g / h, 32.0 g / h, and 10.78 g / h, respectively. The reaction products were collected, and the solvent and excess 1-hexene were recovered by distillation to obtain 1,2-epoxyhexane.

[0139] 1,2-Epoxyhexane was hydrolyzed in a 1.0% dilute sulfuric acid solution at 25°C for 1 hour to yield 1,2-hexanediol.

[0140] Calculations showed that the conversion rate of 1-hexene was 97.9%, the selectivity of 1,2-hexanediol was 98.8%, and the effective utilization rate of hydrogen peroxide was 96.7%.

[0141] Comparative Example 1

[0142] This comparative example provides a method for producing 1,2-hexanediol based on TS-1 molecular sieve catalyst and fixed bed, the specific method being as follows:

[0143] 75.0 g of TS-1 molecular sieve with a TiO2 content of 4.5% was thoroughly mixed with 4.0 g of guar gum powder, and 83.3 g of silica sol with a concentration of 30% was added. After kneading evenly, the mixture was extruded into strips and dried in an oven at 120℃ for 12 h. Finally, it was calcined at 550℃ for 4 h to obtain the comparative fixed-bed catalyst 1. The SiO2 content in this catalyst was 25%.

[0144] 10.0 g of the comparative fixed-bed catalyst 1 was charged into a 20 mL fixed-bed reactor. The reactor temperature was raised to 70 °C, and the pressure was maintained at 1.0 MPa. 1-Hexene, methanol, and 30% hydrogen peroxide were introduced into the reactor at flow rates of 10.0 g / h, 50.0 g / h, and 13.47 g / h, respectively. The reaction products were collected, and the solvent and excess 1-hexene were recovered by distillation to obtain 1,2-epoxyhexane.

[0145] 1,2-Epoxyhexane was hydrolyzed in a 1.0% dilute sulfuric acid solution at 25°C for 1 hour to yield 1,2-hexanediol.

[0146] Calculations showed that the conversion rate of 1-hexene was only 83.7%, the selectivity of 1,2-hexanediol was only 84.8%, and the effective utilization rate of hydrogen peroxide was only 71.0%.

[0147] The relevant performance data of Examples 1-6 and Comparative Example 1 are summarized in Table 1.

[0148] Table 1. Relevant performance data of Examples 1-6 and Comparative Example 1

[0149]

[0150] As shown in Table 1, the TS-2 molecular sieve with larger pores used in this invention is the catalytically active component. Its specific surface area and pore volume are significantly superior to those of the MFI-structured TS-1 molecular sieve. The conversion rate of 1-hexene, the selectivity of 1,2-hexanediol, and the effective utilization rate of hydrogen peroxide are all significantly improved compared to the TS-1 molecular sieve. Furthermore, the 1-hexene conversion rate of this invention can reach over 95%, which is far higher than the 35-60% 1-hexene conversion rate in the prior art (CN117861722A).

[0151] In summary, this invention provides a method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor based on a TS-2 fixed-bed catalyst. This invention employs a fixed-bed process for the hydrogen peroxide oxidation of 1-hexene to produce 1,2-hexanediol. The fixed-bed catalyst abandons the traditional TS-1 molecular sieve, instead selecting a TS-2 molecular sieve with larger pores as the catalytically active component. Its specific surface area and pore volume are significantly superior to the MFI structure of the TS-1 molecular sieve, resulting in a shorter diffusion path and better adaptability to the epoxidation reaction of high-carbon olefins (1-hexene). This effectively improves the conversion rate of raw materials and the selectivity of products, while also possessing a longer lifespan, thus meeting the requirements of fixed-bed catalysts and providing strong support for continuous industrial production.

[0152] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor, characterized in that, The method includes the following steps: A fixed-bed catalyst is loaded into a fixed-bed reactor; 1-hexene, solvent, and hydrogen peroxide are introduced into the fixed-bed reactor and contacted with the fixed-bed catalyst to carry out an epoxidation reaction; 1,2-epoxyhexane is obtained by distillation; 1,2-epoxyhexane is hydrolyzed in an acidic solution to obtain 1,2-hexanediol. The fixed-bed catalyst uses TS-2 molecular sieve as the active component and is prepared as follows: TS-2 molecular sieve is mixed evenly with a pore-forming agent, and a binder is added and kneaded evenly. Then, the mixture is extruded, dried, and calcined to obtain the fixed-bed catalyst. The pore-forming agent is any one or more of guar gum powder, methylcellulose, and citric acid, and the mass ratio of the pore-forming agent to the TS-2 molecular sieve is (0.01~0.2):1; The TS-2 molecular sieve was prepared by the following method: Mix the silicon source and titanium source evenly, and add the template agent under stirring conditions to ensure that the molar ratio of silicon source, titanium source and template agent is 1: (0.025~0.07): (0.1-0.2); After stirring and mixing, the mixture is transferred to a crystallization vessel and crystallized under heating conditions; After cooling, solid-liquid separation is performed, and the solid product is dried to obtain TS-2 molecular sieve containing template agent.

2. The method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor according to claim 1, characterized in that, The fixed-bed catalyst is packed at a density of 0.4~0.8 g / mL in the fixed-bed reactor; The mass hourly space velocity (HHSV) of the 1-hexene is 0.1–2.0 h⁻¹. -1 .

3. The method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor according to claim 1, characterized in that, The flow rate ratio of 1-hexene, solvent, and hydrogen peroxide is 1: (2~8): (1.3~1.4); The solvent is any one or more of methanol, ethanol, tert-butanol, and acetonitrile; The concentration of H2O2 in the hydrogen peroxide is 25~35wt%.

4. The method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor according to claim 1, characterized in that, The epoxidation reaction is carried out at a temperature of 20~80℃; The pressure of the epoxidation reaction is 0~2.0 MPa.

5. The method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor according to claim 1, characterized in that, The TS-2 molecular sieve has a MEL-type topology, consisting of a regular pore system composed of two sets of mutually perpendicular cylindrical ten-membered rings. The TiO2 content in the TS-2 molecular sieve is 1.0~6.0 wt%; The BET specific surface area of ​​the TS-2 molecular sieve is not less than 500 m. 2 / g, total pore volume not less than 0.45 cm³ 3 / g.

6. The method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor according to claim 1, characterized in that, The silicon source is at least one of tetraethyl orthosilicate and silica sol; The titanium source is at least one of tetrabutyl titanate and tetraethyl titanate; The template agent is at least one of tetrabutylammonium hydroxide and tetrabutylammonium bromide; The crystallization temperature is 150~200℃, and the crystallization time is 24~72h.

7. The method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor according to claim 1, characterized in that, The mass content of the TS-2 molecular sieve in the fixed-bed catalyst is 30~95wt%.

8. The method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor according to claim 1, characterized in that, The binder is either silica sol or tetraethyl orthosilicate, and the SiO2 content in the binder is 5-70% of the mass of the fixed-bed catalyst.

9. A method for producing 1,2-hexanediol from 1-hexene using a fixed-bed reactor according to claim 1, characterized in that, The roasting temperature is 500~600 ℃, and the roasting time is 2~6 h.

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