Method for preparing pentanol from 2-pentene

Abstract

The invention discloses a method for preparing pentanol from 2-pentene, and relates to the technical field of pentanol preparation, and the method comprises the following steps: S1, epoxidation reaction: 2-pentene, methanol and hydrogen peroxide react with a titanium silicalite molecular sieve catalyst on an isothermal fixed bed reactor to produce a reaction solution containing 2, 3-epoxypentane, and the obtained reaction solution is rectified through a rectifying tower to obtain 2, 3-epoxypentane; adding a 1, 3-epoxypentane methanol solution; and S2, hydrogenation reaction: adding hydrogen into the 2, 3-epoxypentane methanol solution, carrying out hydrogenation reaction under the action of a catalyst, and converting 2, 3-epoxypentane into 3-pentanol and 2-pentanol. According to the method, 2-pentene is taken as a raw material, the yield of 3-pentanol with high added value is greatly improved through an epoxidation-hydrogenation route, and meanwhile, the problems of corrosion of acid to equipment, serious pollution, high energy consumption and the like in an indirect method are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of pentanol preparation, and particularly relates to a method for preparing pentanol from 2-pentene. Background Art

[0002] Among the downstream products of 2-pentene, 3-pentanol is of great importance. The molecular formula of 3-pentanol is C5H12O, the molecular weight is 88.15, it is a colorless liquid, the density is 0.815 g / mL, the boiling point is 114 - 115 °C, the flash point is 35 °C, it is soluble in ethanol and ether, slightly soluble in water, has a special smell, can be used as a solvent, flotation agent, and raw material for organic synthesis, is an important chemical intermediate, and is often used as a raw material for manufacturing ester solvents, and these esters are widely used in coatings, paints, and resins. As an intermediate for drug synthesis, 3-pentanol can be used to produce some specific pharmaceutical compounds, such as antibacterial drugs and anti-inflammatory drugs. The molecular formula of 2-pentanol is C5H12O, the molecular weight is 88.148, it is a colorless liquid, the density is 0.812 g / cm3, the boiling point is 118 - 119 °C, the flash point is 34 °C, it is extremely soluble in water, soluble in ethanol and ether, showing the aroma of wine and ether, and is mainly used as a food flavor, solvent, and can also be used as an intermediate for organic synthesis, and is an indispensable raw material for preparing compounds such as esters, ethers, and ketones, as well as drugs such as antimalarials and local anesthetics.

[0003] Using pentene as a raw material, pentanol is prepared by methods such as sulfuric acid addition and hydrolysis, or direct hydration using cation exchange resins and acidic catalysts represented by zeolites. The advantages of the indirect method are low raw material requirements, mature and simple processes, low price and wide source of acids.

[0004] Fang Ling et al. used C5 fraction as a raw material, investigated the process conditions for preparing pentanol by sulfuric acid addition and hydrolysis method, and preliminarily refined the obtained product to obtain pentanol with a mass fraction of 97.7%; Patent CN 113754514A discloses a method for preparing pentanol from 2-methylfuran at room temperature in a reaction kettle using a supported platinum-based catalyst. The effects of various catalyst carriers, active metals, metal loadings, and reaction conditions (solvents, time, pressure, etc.) were investigated. Under the optimal conditions, the conversion rate of pentanol can reach 100%, and the selectivity of pentanol is 53%; Patent CN 114031480 A uses a platinum-based catalyst prepared by a continuous flow method for the hydrogenation of 2-methylfuran to prepare pentanol in an autoclave, and by adjusting the amount of different solvents and the reaction temperature, the conversion rate of 2-methylfuran hydrogenation to prepare pentanol can reach 100%, and the selectivity of pentanol is 70%. While improving the production efficiency of the catalyst, the efficacy is ensured; Patent CN 104368359 B discloses a catalyst for the hydrogenation of 3-pentanone to 3-pentanol, which includes a carbon-based carrier and multi-metal components, denoted as M1-M2-M3 / C. Among them, M1 is selected from one of Ru, Mn, and Ag, M2 is selected from one of Ir, Au, and Cu, and M3 is selected from one of La, Ce, and Y. Applying the catalyst to the liquid-phase hydrogenation process of 3-pentanone can achieve a 100% conversion rate of 3-pentanone in a relatively short time, while the selectivity of 3-pentanol is 100%.

[0005] Patent CN 104478661 B proposes a method for preparing a mixture of 2-pentanol and 3-pentanol from 2-pentene. The 2-pentene and acetic acid solution are subjected to an addition reaction through a fixed-bed catalyst bed composed of sulfonic acid group cation exchange resin to be first converted into amyl acetate, and then a transesterification reaction is carried out using sodium methoxide catalyst and methanol solution to prepare 2-pentanol and 3-pentanol.

[0006] 3-Pentanol and 2-pentanol are important fine chemical product intermediates, mainly used for preparing products such as pesticides and pharmaceuticals. 3-Pentanol and 2-pentanol can be obtained by high-temperature decarboxylation of butyric acid and acetic acid to produce 3-pentanone and 2-pentanone, and then through hydrogenation reaction. However, due to the generation of a large amount of pollutants and the restriction of raw material sources, this preparation method is increasingly restricted. In addition, using 2-pentene obtained from the processing of C5 fraction by-products in petroleum cracking to produce ethylene as a raw material, 2-pentanol and 3-pentanol can also be produced through hydration reaction, including two processes of indirect hydration and direct hydration of 2-pentene. Although indirect hydration has the advantages of high conversion rate and good selectivity, due to the need to use acid in the preparation process, the corrosion resistance requirements of the equipment are extremely high, and the environmental pollution is still relatively serious. The direct hydration process does not have these problems and is an environmentally friendly technical route. However, the disadvantage of this method is that the reaction conversion rate is still relatively low, and the recycle amount of the raw material 2-pentene is extremely large. Using 2-pentene as a raw material, through the method of esterification reaction and transesterification reaction using acetic acid as an addition raw material to prepare a mixture of 2-pentanol and 3-pentanol can improve the reaction conversion rate and selectivity, but this route produces a large amount of by-product methyl acetate, and acetic acid has a certain corrosiveness to the equipment. Therefore, this application provides a method for preparing pentanol from 2-pentene to meet the demand. Summary of the Invention

[0007] The purpose of this application is to improve the yield of high-value-added 3-pentanol, and at the same time solve problems such as acid corrosion of equipment, serious pollution, and high energy consumption in the indirect method.

[0008] To achieve the above purpose, this application provides the following technical solution: A method for preparing pentanol from 2-pentene, including the following steps: S1. Epoxidation reaction: A reaction solution containing 2,3-epoxypentane is produced by reacting 2-pentene, methanol, and hydrogen peroxide on an isothermal fixed-bed reactor with a titanium silicalite catalyst. The reaction temperature is 35 - 45°C, and the obtained reaction solution is rectified through a rectification column to obtain a 2,3-epoxypentane methanol solution; The reaction temperature is 35 - 45°C. Within this temperature range, the titanium silicalite catalyst can maintain high activity, which is beneficial to the progress of the epoxidation reaction. At the same time, the relatively low temperature helps to reduce side reactions that may occur at high temperatures, such as the ring-opening reaction of epoxides, etc., thereby improving the purity and yield of the product; S2. Hydrogenation reaction: The 2,3-epoxypentane methanol solution undergoes a hydrogenation reaction by adding hydrogen and under the action of a catalyst, and 2,3-epoxypentane is converted into 3-pentanol and 2-pentanol, including the following steps: S21: After mixing the methanol solution containing 2,3-epoxypentane with hydrogen, it enters the preheating zone, and the mixture is preheated to 100 - 120°C through an electric heating jacket or hot oil circulation, and the residence time is controlled within 2 - 5 minutes; The boiling point of methanol is 64.7°C. The preheating temperature of 100 - 120°C can ensure that methanol remains in a liquid state, avoiding fluctuations in the reactant concentration caused by gasification; at the same time, this temperature range is lower than the autoignition point of methanol (464°C), so the safety is relatively high; the preheating time of 2 - 5 minutes can fully homogenize the temperature of the reaction solution, avoiding local low temperature or hot spots when entering the catalyst bed layer, and improving the reaction stability; After preheating, the viscosity of the reaction solution decreases, which is beneficial to the full mixing of hydrogen and epoxypentane, improving the mass transfer efficiency, and providing a uniform reaction environment for the subsequent hydrogenation reaction; S22: The preheated reaction solution enters a fixed-bed reactor filled with a hydrogenation catalyst. By precisely controlling the temperature distribution of the catalyst bed layer, the temperature at the inlet side of the front section of the bed layer is maintained at 140 - 150°C, the middle section at 150 - 155°C, and the end section at 155 - 160°C; the residence time is 15 - 20 minutes; Low inlet temperature (140 - 150°C): Prevent local overheating and deactivation of the catalyst due to intense heat release at the initial stage of the reaction, and at the same time inhibit side reactions (such as the ring-opening polymerization of epoxypentane); Mid-section temperature increase (150 - 155°C): As the reaction progresses, a moderate temperature increase can maintain the reaction rate and promote the conversion of epoxypentane to pentanol; High outlet temperature (155 - 160°C): Further promote the reaction equilibrium to shift towards the product direction and improve the conversion rate.

[0009] Residence time: 15 - 20 minutes ensures that the reaction approaches the equilibrium state, and at the same time avoids excessive hydrogenation due to too long residence time (such as the formation of by-product 1-pentanol) Moderate temperature increase can accelerate the hydrogenation reaction of epoxy pentane, but too high temperature (>160 °C) may lead to an increase in the proportion of 2-pentanol or carbon deposition on the catalyst.

[0010] S23: The reaction product enters the cooling zone and is quickly cooled to below 80 - 100 °C by circulating cooling water or low-temperature hot oil, with a residence time of 3 - 5 minutes. After cooling, it directly enters the distillation column, and high-purity 3-pentanol is obtained through separation by the distillation column.

[0011] As a preferred implementation mode in this embodiment, in S1, the molar ratio of 2-pentene to H2O2 is 1.3 - 1.9. Within this molar ratio range, the amount of hydrogen peroxide is appropriate, which can not only ensure the full epoxidation of 2-pentene but also prevent unnecessary waste or side reactions caused by excessive hydrogen peroxide, thereby improving the efficiency of the entire reaction. In S2, the molar ratio of hydrogen to 2,3-epoxy pentane is 4 - 6:1. Within this molar ratio range, it can ensure the complete hydrogenation conversion of 2,3-epoxy pentane into 3-pentanol and 2-pentanol, and at the same time ensure that the amount of hydrogen is not excessive, avoiding unnecessary waste and subsequent treatment costs.

[0012] As a preferred implementation mode in this embodiment, in S1, the mass space velocity of H2O2 is 0.07 - 0.13 h-1. Within this space velocity range, the contact time between hydrogen peroxide and the catalyst is appropriate, which can not only ensure the full progress of the reaction but also prevent the deactivation of the catalyst or the degradation of the product due to too long contact time. In S2, the space velocity of 2,3-epoxy pentane is 1.2 - 1.6 h-1. Within this space velocity range, the contact time between 2,3-epoxy pentane and the catalyst is appropriate, which can not only ensure the full progress of the reaction but also prevent the deactivation of the catalyst or the degradation of the product due to too long contact time.

[0013] As a preferred implementation mode in this embodiment, in S1, the reaction pressure is 0.4 - 0.8 MPa. Within this pressure range, it is beneficial to the epoxidation reaction because the increase in pressure helps the hydrogen peroxide molecules better penetrate into the catalyst pores, contact with 2-pentene molecules and react. At the same time, the appropriate pressure will neither be too high for the equipment to bear nor too low to affect the reaction efficiency, thus ensuring the safety of the entire operation process. In S2, the reaction pressure is 4 - 6 MPa. Within this pressure range, it is beneficial to the hydrogenation reaction, which helps the hydrogen molecules better penetrate into the catalyst pores, contact with 2,3-epoxy pentane molecules and react.

[0014] As a preferred implementation mode in this embodiment, the theoretical plates of the distillation column are 30.

[0015] As a preferred implementation manner in this embodiment, the mixing device includes a tank body equipped with a first aeration pipe and a stirring system, and further includes a hydrogen circulation unit, which uses the rotational force of the drive shaft in the stirring system to transport the hydrogen overflowing from the solution into the solution for dissolution.

[0016] As a preferred implementation manner in this embodiment, the hydrogen circulation unit includes an annular plate fixedly sealed in the inner cavity of the tank body, a piston cylinder fixed to the upper end of the annular plate, and a second one-way intake valve installed at the intake end of the first aeration pipe; A hollow cylinder with an open upper end is hermetically connected to the axis of the annular plate; The left end of the piston cylinder is connected to the intake end of the second aeration pipe through a connecting pipe, and a one-way outlet valve is installed on the connecting pipe; A piston is slidably arranged in the inner cavity of the piston cylinder, and the right end of the piston is movably connected to an eccentric column through a movable rod. The eccentric column is eccentrically arranged on a turntable. A mounting shaft is fixed at the axis of the turntable, and the mounting shaft is rotatably connected to the inner wall of the tank body through a mounting plate. The mounting shaft is arranged in a square structure. The lower end of the mounting shaft is slidably arranged in the inner cavity of the movable column. A gear is fixed at the lower end of the movable column. A magnetic isolation cover is rotatably arranged at the lower end of the gear, and a first adsorption magnet is installed in the magnetic isolation cover. A return spring is sleeved around the movable column. The upper end of the return spring is fixedly connected to the mounting plate, and the lower end of the return spring is rotatably connected to the outer wall of the movable column; The stirring system includes a servo motor with a drive shaft and a stirring shaft rotatably arranged in the inner cavity of the tank body; A first fixed magnet and a second fixed magnet are respectively installed in the magnetic isolation covers at the upper end of the stirring shaft and the lower end of the drive shaft. The lower end of the drive shaft is located in the inner cavity of the hollow cylinder. The stirring shaft is located below the hollow cylinder. A mounting ring plate is sleeved around the drive shaft, and the mounting ring plate is slidably connected to the hollow cylinder through sliders arranged at the bottom. A toothed ring is rotatably arranged on the mounting ring plate, and a limiting through hole is arranged on the toothed ring. A limiting strip adapted to the limiting through hole is arranged on the drive shaft. Two groups of first acting magnets are symmetrically arranged on the mounting ring plate, and both groups of first acting magnets are arranged in the magnetic isolation cover. A second adsorption magnet is installed in the magnetic isolation cover at the upper end of the mounting ring plate, and the opposite ends of the second adsorption magnet and the first adsorption magnet have opposite magnetic poles; A movable ring plate is hermetically and slidably arranged below the annular plate, and elastic rings for sealing are fixed on both the inner and outer walls of the movable ring plate. Two groups of second acting magnets are oppositely arranged on the movable ring plate, and both groups of second acting magnets are arranged in a magnetic shielding cover. The opposite ends of the first acting magnet and the second acting magnet have opposite magnetic poles. A telescopic pipe is installed on the movable ring plate. The upper end of the telescopic pipe communicates with the inner cavity of the piston cylinder, and the lower end of the telescopic pipe communicates with the cavity below the movable ring plate. A second one-way intake valve is installed on the telescopic pipe. A ventilation pipe is also installed on the tank body, and the lower end of the ventilation pipe penetrates through the annular plate.

[0017] In summary, the technical effects and advantages of the present invention are as follows: 1. The structure of the present invention is reasonable. The present invention uses 2-pentene as a raw material through an epoxidation-hydrogenation route, greatly improving the yield of high-value-added 3-pentanol, and at the same time solving many problems such as acid corrosion of equipment, serious pollution, and high energy consumption in the indirect method. 2. In the present invention, this mixing device uses the drive shaft as the rotation power and transports the hydrogen overflowing from the solution back to the solution until the solution completely dissolves hydrogen, making full use of hydrogen. At the same time, after the first aeration pipe finishes transporting, the second aeration pipe conducts cyclic aeration, saving electric energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 It is a table of the epoxidation reaction conditions and results of 2-pentene for Examples 1 to 9; Figure 2 It is a table of the hydrogenation reaction conditions and results of 2,3-epoxypentane for Examples 1 to 9; Figure 3 It is a schematic cross-sectional structure diagram of the mixing device; Figure 4 For Figure 3 The enlarged structure diagram at A in Figure 5 For Figure 3 The enlarged structure diagram at B in

[0020] In the figure: 1, tank body; 2, servo motor; 3, stirring shaft; 4, first aeration pipe; 5, annular plate; 6, piston cylinder; 7, movable rod; 8, connecting pipe; 9, one-way air outlet valve; 10, second one-way air inlet valve; 11, hollow cylinder; 12, eccentric column; 13, turntable; 14, mounting plate; 15, mounting shaft; 16, movable column; 17, return spring; 18, gear; 19, first adsorption magnet; 20, limiting strip; 21, first fixed magnet; 22, second fixed magnet; 23, driving shaft; 24, mounting ring plate; 25, slider; 26, second acting magnet; 27, first acting magnet; 28, second adsorption magnet; 29, magnetic ring; 30, limiting through hole; 31, ventilation pipe; 32, movable ring plate; 33, telescopic pipe; 34, second aeration pipe. Detailed implementation mode

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0022] A method for preparing pentanol from 2-pentene includes the following steps: S1. Epoxidation reaction: React 2-pentene, methanol, and hydrogen peroxide on an isothermal fixed-bed reactor with a titanium silicalite catalyst to produce a reaction solution containing 2,3-epoxypentane, and rectify the obtained reaction solution through a rectification column to obtain a 2,3-epoxypentane methanol solution; S2. Hydrogenation reaction: The 2,3-epoxypentane methanol solution undergoes a hydrogenation reaction by adding hydrogen and under the action of a catalyst, and 2,3-epoxypentane is converted into 3-pentanol and 2-pentanol; S21: After mixing the methanol solution containing 2,3-epoxypentane with hydrogen, enter the preheating zone, and preheat the mixture to 100 - 120 °C through an electric heating jacket or hot oil circulation, and control the residence time to be 2 - 5 minutes; S22: The preheated reaction solution enters a fixed-bed reactor filled with a hydrogenation catalyst. By precisely controlling the temperature distribution of the catalyst bed layer, the temperature at the inlet side of the front section of the bed layer is maintained at 140 - 150 °C, the middle section at 150 - 155 °C, and the last section at 155 - 160 °C; the residence time is 15 - 20 minutes; S23: The reaction product enters the cooling zone, and is quickly cooled to below 80 - 100 °C through circulating cooling water or low-temperature hot oil, with a residence time of 3 - 5 minutes. After cooling, it directly enters the rectification column, and high-purity 3-pentanol is separated through the rectification column.

[0023] Using this method, the production route produces almost no by-products. The ratio of 3-pentanol to 2-pentanol is increased from 2:3 in the current process to 1.4:1, greatly improving the yield of 3-pentanol. This route has high yield, mild reaction, green and pollution-free, and has significant competitiveness.

[0024] Examples 1 to 9 1. Epoxidation reaction The epoxidation reaction was carried out in an isothermal bed reactor. 100 g of titanium silicalite catalyst was added to the reactor. A circulating hot water temperature control jacket was installed on the outside of the reactor. Platinum resistance thermometers were installed above, in the middle, and below the catalyst bed. The system pressure was regulated by a backpressure valve. The reaction feed rate was controlled by a feed pump, which was fed in from the bottom and out from the top. The resulting epoxidation reaction solution was analyzed by chromatography, and the HO conversion rate and product selectivity were calculated. The reaction conditions and results of each example are shown in Table 2. Figure 1 As shown; 2. Hydrogenation reaction The hydrogenation reaction of 2,3-epoxypentane was carried out in a fixed bed reactor. 100g of Raney nickel catalyst was added to the reactor. The catalyst was ETH-2000 purchased from Dalian General Chemical Co., Ltd. The reactor was equipped with a circulating oil bath temperature control jacket. Platinum resistance thermometers were installed on the top, middle and bottom of the catalyst bed. The system pressure was regulated by a back pressure valve. The reaction raw materials entered the reactor in a top-in and bottom-out manner. The obtained hydrogenation reaction liquid was analyzed by chromatography, and the conversion rate of 2,3-epoxypentane and the product selectivity were calculated. The reaction conditions and results of each embodiment are shown in the table below. Figure 2 As shown; from Figure 1 and Figure 2 As can be seen from the data in the examples, in the reaction of preparing pentanol by hydrogenation of 2,3-epoxypentane, a high conversion rate of 2,3-epoxypentane can be achieved and the 2,3-epoxypentane can be completely converted into pentanol. The ratio of 3-pentanol to 2-pentanol reaches 1.4:1 (the current ratio of 3-pentanol to 2-pentanol in traditional processes is 2:3). This route has high yield, mild reaction, is green and pollution-free, and has significant competitiveness.

[0025] A mixing device includes a tank body 1 equipped with a first aeration pipe 4 and a stirring system, and also includes a hydrogen circulation unit, which utilizes the rotational force of a drive shaft 23 in the stirring system to transport hydrogen overflowing from the solution into the solution for dissolution.

[0026] As a preferred implementation in this embodiment, Figures 3 - 5 As shown, the hydrogen circulation unit includes an annular plate 5 sealed and fixedly arranged in the inner cavity of the tank body 1, a piston cylinder 6 fixed to the upper end of the annular plate 5, and a second one-way air inlet valve 10 installed at the air inlet end of the first aeration pipe 4; At the axis center of the annular plate 5, there is a sealed connection with a hollow cylinder 11 with an open upper end; The left end of the piston cylinder 6 is connected to the intake end of the second aeration pipe 34 through a connecting pipe 8, and a one-way air outlet valve 9 is installed on the connecting pipe 8; A piston is slidably arranged in the inner cavity of the piston cylinder 6, and the right end of the piston is movably connected to an eccentric column 12 through a movable rod 7. The eccentric column 12 is eccentrically arranged on a turntable 13. A mounting shaft 15 is fixed at the axis center of the turntable 13, and the mounting shaft 15 is rotatably connected to the inner wall of the tank body 1 through a mounting plate 14. The mounting shaft 15 is arranged in a square structure. The lower end of the mounting shaft 15 is slidably arranged in the inner cavity of a movable column 16. A gear 18 is fixed at the lower end of the movable column 16. A magnetic shielding cover is rotatably arranged at the lower end of the gear 18, and a first adsorption magnet 19 is installed inside the magnetic shielding cover. A return spring 17 is sleeved around the periphery of the movable column 16. The upper end of the return spring 17 is fixedly connected to the mounting plate 14, and the lower end of the return spring 17 is rotatably connected to the outer wall of the movable column 16; The stirring system includes a servo motor 2 with a driving shaft 23 and a stirring shaft 3 rotatably arranged in the inner cavity of the tank body 1; A first fixed magnet 21 and a second fixed magnet 22 are respectively installed inside the magnetic shielding covers at the upper end of the stirring shaft 3 and the lower end of the driving shaft 23. The lower end of the driving shaft 23 is located in the inner cavity of the hollow cylinder 11. The stirring shaft 3 is located below the hollow cylinder 11. A mounting ring plate 24 is sleeved around the periphery of the driving shaft 23, and the mounting ring plate 24 is slidably connected to the hollow cylinder 11 through a slider 25 arranged at the bottom. A toothed ring 29 is rotatably arranged on the mounting ring plate 24, and a limiting through hole 30 is arranged on the toothed ring 29. A limiting strip 20 adapted to the limiting through hole 30 is arranged on the driving shaft 23. Two groups of first acting magnets 27 are symmetrically arranged on the mounting ring plate 24, and both groups of first acting magnets 27 are arranged inside the magnetic shielding cover. A second adsorption magnet 28 is installed inside the magnetic shielding cover at the upper end of the mounting ring plate 24, and the relative ends of the second adsorption magnet 28 and the first adsorption magnet 19 have opposite magnetic poles; An activity ring plate 32 is hermetically and slidably arranged below the annular plate 5, and elastic rings for sealing are fixed on both the inner and outer walls of the activity ring plate 32. Two groups of second acting magnets 26 are oppositely arranged on the activity ring plate 32, and both groups of second acting magnets 26 are arranged inside the magnetic shielding cover. The relative ends of the first acting magnet 26 and the second acting magnet 27 have opposite magnetic poles. A telescopic pipe 33 is installed on the activity ring plate 32. The upper end of the telescopic pipe 33 communicates with the inner cavity of the piston cylinder 6, and the lower end of the telescopic pipe 33 communicates with the cavity below the activity ring plate 12. A second one-way intake valve is installed on the telescopic pipe 33; A ventilation pipe 31 is also installed on the tank body 1, and the lower end of the ventilation pipe 31 penetrates through the annular plate 5.

[0027] Inject a specified amount of 2,3-epoxypentane methanol solution into the tank body 1, aerate the tank body 1 through the first aeration pipe 4 (inject a specified amount of hydrogen at a specified speed), and use the stirring shaft 3 to rotate and stir. Part of the hydrogen will dissolve into the solution, and part of the hydrogen will move into the solution and be blocked in the space below by the movable ring plate 32. As the amount of hydrogen in the lower space accumulates, the air pressure in the lower space increases, and the movable ring plate 32 will move upward. The upward movement of the movable ring plate 32 will, through the magnetic force of the second acting magnet 26 and the first acting magnet 27, cause the suspended mounting ring plate 24 to move upward. When approaching the end of aeration, through the magnetic force of the second adsorption magnet 28 and the first adsorption magnet 19, the first adsorption magnet 19 will move downward, and finally the gear 18 and the toothed ring 29 will be engaged. Drive the toothed ring 29 to move through the drive shaft 23, and use the rotating toothed ring 29 to drive the turntable 13 to rotate through the gear 18. Drive the piston in the piston cylinder 6 to perform a piston movement through the movable rod 7, and then pump the hydrogen below the movable ring plate 13 into the second aeration pipe 34 (which is arranged at the bottom of the inner cavity of the tank body 1), and transport the hydrogen to the solution again for dissolution until the movable ring plate 32 returns to its original position. When the movable ring plate 32 moves downward, it will drive the mounting ring plate 24 to move downward. At this time, since the first adsorption magnet 19 and the second adsorption magnet 28 are adsorbed and fixed together by magnetic action, as the mounting ring plate 24 moves downward, the second adsorption magnet 28 will drive the movable column 16 to move downward as the pull rope return spring 17 until the movable ring plate 32 returns to its original position. At this time, through the elastic force of the return spring 17, the first adsorption magnet 19 and the second adsorption magnet 28 are separated, and the movable column 16 drives the gear 18 to return to its original position; this structure uses the drive shaft 23 as the rotation power and transports the hydrogen overflowing from the solution back to the solution until the solution completely dissolves the hydrogen, making the hydrogen fully utilized. At the same time, after the first aeration pipe 4 finishes transporting, the second aeration pipe 34 will perform cyclic aeration. If the second aeration pipe 34 aerates together with the first aeration pipe 4 (since the hydrogen released by the first aeration pipe 4 has maximally increased the hydrogen dissolution rate of the solution per unit time, at this time, aerating the two aeration pipes together will not increase the hydrogen dissolution rate per unit time too much, making the servo motor 2 do useless work and generating more power consumption), it will cause the servo motor 2 to do too much useless work and ultimately increase the power consumption.

[0028] It should be noted that: First, a baffle is provided on the outer wall of the hollow cylinder 11 to support the bottom of the movable ring plate 32 in the initial state; Second, in the above process, the lower end of the limit strip 20 is located below the toothed ring 29, that is, the limit strip 20 always passes through the limit through hole 30. When the drive shaft 23 rotates, its toothed ring 29 also rotates together (relatively power-consuming); Third, a ventilation pipe 31 is provided to ensure that the air pressure in the space above the mounting ring plate 32 is the same as the external air pressure, so as to avoid hindering the upward movement of the mounting ring plate 32; Fourth, the telescopic rod 33 includes a first hollow tube and a second hollow tube. The lower end of the first hollow tube is hermetically and slidably arranged in the inner cavity of the second hollow tube through an elastic ring fixedly arranged on the outer wall; Fifth, when the drive shaft 23 rotates, the stirring shaft 3 is driven to rotate and stir through the magnetic force between the first fixed magnet 21 and the second fixed magnet 22 (a suction force is generated between the two magnets).

[0029] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing pentanol from 2-pentene, characterized in that: It includes the following steps: S1. Epoxidation reaction: React 2-pentene, methanol, and hydrogen peroxide on an isothermal fixed-bed reactor with a titanium silicalite catalyst to produce a reaction solution containing 2,3-epoxypentane. The reaction temperature is 35-45 °C, and the obtained reaction solution is rectified through a rectification column to obtain a 2,3-epoxypentane methanol solution; S2. Hydrogenation reaction: The 2,3-epoxypentane methanol solution undergoes a hydrogenation reaction by adding hydrogen and under the action of a catalyst, and 2,3-epoxypentane is converted into 3-pentanol and 2-pentanol; S21: Mix the methanol solution containing 2,3-epoxypentane with hydrogen through a mixing device, then enter the preheating zone, and preheat the mixture to 100-120 °C through an electric heating jacket or hot oil circulation. The residence time is controlled within 2-5 minutes; S22: The preheated reaction solution enters a fixed-bed reactor equipped with a hydrogenation catalyst. By precisely controlling the temperature distribution of the catalyst bed, the temperature at the inlet side of the front section of the bed is maintained at 140-150 °C, the middle section at 150-155 °C, and the last section at 155-160 °C; the residence time is 15-20 minutes; S23: The reaction product enters the cooling zone, and is quickly cooled to below 80-100 °C through circulating cooling water or low-temperature hot oil. The residence time is 3-5 minutes. After cooling, it directly enters the rectification column, and high-purity 3-pentanol is separated through the rectification column.

2. The method for preparing pentanol from 2-pentene according to claim 1, characterized in that: In S1, the molar ratio of 2-pentene to H2O2 is 1.3-1.

9. Within this molar ratio range, the amount of hydrogen peroxide is appropriate, which can not only ensure the full epoxidation of 2-pentene, but also prevent unnecessary waste or side reactions caused by excessive hydrogen peroxide, thereby improving the efficiency of the entire reaction; In S2, the molar ratio of hydrogen to 2,3-epoxypentane is 4-6:

1. Within this molar ratio range, it can ensure the complete hydrogenation conversion of 2,3-epoxypentane into 3-pentanol and 2-pentanol, and also ensure that the amount of hydrogen is not excessive, avoiding unnecessary waste and subsequent treatment costs.

3. A method for preparing pentanol from 2-pentene according to claim 1, characterized in that: In S1, the mass space velocity of H2O2 is 0.07 - 0.13 h -1 , within this space velocity range, the contact time between hydrogen peroxide and the catalyst is appropriate, which can not only ensure the full progress of the reaction, but also prevent the catalyst from deactivating or the product from degrading due to excessive contact time; In S2, the space velocity of 2,3-epoxypentane is 1.2~1.6 h -1 , within this space velocity range, the contact time between 2,3-epoxypentane and the catalyst is appropriate, which can not only ensure the full progress of the reaction, but also prevent the catalyst from deactivating or the product from degrading due to too long contact time.

4. The method for preparing pentanol from 2-pentene according to claim 1, characterized in that: In S1, the reaction pressure is 0.4-0.8 MPa. Within this pressure range, it is beneficial to the epoxidation reaction because the increase in pressure helps hydrogen peroxide molecules better penetrate into the catalyst pores, contact with 2-pentene molecules and react. At the same time, an appropriate pressure will neither be too high for the equipment to bear nor too low to affect the reaction efficiency, thus ensuring the safety of the entire operation process; In S2, the reaction pressure is 4-6 MPa. Within this pressure range, it is beneficial to the hydrogenation reaction, which helps hydrogen molecules better penetrate into the catalyst pores, contact with 2,3-epoxypentane molecules and react.

5. The method for preparing pentanol from 2-pentene according to claim 1, wherein: The theoretical plates of the rectification column are 30.

6. A method for preparing pentanol from 2-pentene according to claim 1, wherein the mixing device comprises a tank body (1) equipped with a first air supply pipe (4) and a stirring system, and is characterized in that: It also includes a hydrogen circulation unit, which uses the rotational force of the drive shaft (23) in the stirring system to transport the hydrogen overflowing from the solution back into the solution for dissolution.

7. A method for preparing pentanol from 2-pentene according to claim 6, characterized in that: The hydrogen circulation unit includes an annular plate (5) fixedly sealed inside the inner cavity of the tank body (1), a piston cylinder (6) fixed to the upper end of the annular plate (5), and a second one-way intake valve (10) installed at the intake end of the first air supply pipe (4); At the axis center of the annular plate (5), there is a hollow cylinder (11) with an open upper end, which is hermetically connected; The left end of the piston cylinder (6) is connected to the air inlet end of the second aeration pipe (34) through a connecting pipe (8), and a one-way air outlet valve (9) is installed on the connecting pipe (8); A piston is slidably arranged in the inner cavity of the piston cylinder (6), and the right end of the piston is movably connected to an eccentric column (12) through a movable rod (7). The eccentric column (12) is eccentrically arranged on a turntable (13). A mounting shaft (15) is fixed at the axis center of the turntable (13), and the mounting shaft (15) is rotationally connected to the inner wall of the tank body (1) through a mounting plate (14). The mounting shaft (15) is arranged in a square structure. The lower end of the mounting shaft (15) is slidably arranged in the inner cavity of the movable column (16). A gear (18) is fixed at the lower end of the movable column (16). A magnetic shielding cover is rotatably arranged at the lower end of the gear (18), and a first adsorption magnet (19) is installed in the magnetic shielding cover. A return spring (17) is sleeved around the movable column (16). The upper end of the return spring (17) is fixedly connected to the mounting plate (14), and the lower end of the return spring (17) is rotationally connected to the outer wall of the movable column (16); The stirring system includes a servo motor (2) with a driving shaft (23) and a stirring shaft (3) rotatably arranged in the inner cavity of the tank body (1); A first fixed magnet (21) and a second fixed magnet (22) are respectively installed in the magnetic shielding covers at the upper end of the stirring shaft (3) and the lower end of the driving shaft (23). The lower end of the driving shaft (23) is located in the inner cavity of the hollow cylinder (11). The stirring shaft (3) is located below the hollow cylinder (11). A mounting ring plate (24) is sleeved around the driving shaft (23), and the mounting ring plate (24) is slidably connected to the hollow cylinder (11) through a slider (25) arranged at the bottom. A toothed ring (29) is rotatably arranged on the mounting ring plate (24), and a limiting through hole (30) is arranged on the toothed ring (29). A limiting strip (20) adapted to the limiting through hole (30) is arranged on the driving shaft (23). Two groups of first acting magnets (27) are symmetrically arranged on the mounting ring plate (24), and both groups of the first acting magnets (27) are arranged in the magnetic shielding cover. A second adsorption magnet (28) is installed in the magnetic shielding cover at the upper end of the mounting ring plate (24), and the relative end of the second adsorption magnet (28) and the first adsorption magnet (19) has opposite magnetic poles; A movable ring plate (32) is hermetically and slidably arranged below the annular plate (5), and elastic rings for sealing are fixed on both the inner and outer walls of the movable ring plate (32). Two groups of second acting magnets (26) are oppositely arranged on the movable ring plate (32), and both groups of the second acting magnets (26) are arranged inside a magnetic shielding cover. The opposite ends of the first acting magnet (26) and the second acting magnet (27) have opposite polarities. A telescopic tube (33) is installed on the movable ring plate (32). The upper end of the telescopic tube (33) communicates with the inner cavity of the piston cylinder (6), and the lower end of the telescopic tube (33) communicates with the cavity below the movable ring plate (12). A second one-way intake valve is installed on the telescopic tube (33). A ventilation pipe (31) is further installed on the tank body (1), and the lower end of the ventilation pipe (31) penetrates through the annular plate (5).

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