Preparation process of high-content dihydroterpilenol

Abstract

The invention discloses a preparation process of high-content dihydroterpilenol, which comprises the following steps: adding alpha-terpilenol into a reaction kettle, adding a catalyst into the reaction kettle, and uniformly mixing with the alpha-terpilenol; closing the reaction kettle, introducing hydrogen, discharging air in the reaction kettle, and repeatedly washing the reaction kettle to ensure that the air in the kettle is completely replaced by the hydrogen; the temperature of the reaction kettle is set to be 80-100 DEG C, and the pressure is set to be 2-4 MPa; starting a stirring device of the reaction kettle, and uniformly stirring; after the reaction is finished, stopping hydrogen supply, stopping heating and stirring, releasing the pressure in the reaction kettle, and reducing the pressure to normal pressure; opening the reaction kettle, pouring out a reaction mixture, filtering and separating the catalyst and a liquid-phase product, washing the catalyst, collecting a washing solution, combining the reaction solution and the washing solution, purifying to obtain a crude product of dihydroterpilenol, and rectifying the crude product through rectification equipment to obtain the high-content dihydroterpilenol. According to the catalyst, the content of dihydroterpilenol can be remarkably increased, and the selectivity is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of dihydroterpineol synthesis, and in particular relates to a preparation process of high-content dihydroterpineol. Background Art

[0002] Dihydroterpineol, a chemical term that hides a series of delicate and complex chemical reaction processes, is a valuable compound carefully crafted through the hydrogenation reaction of α-terpineol. This transformation not only gives dihydroterpineol unique chemical properties, but also greatly broadens its application areas. Specifically, its molecular formula C 10 H 20 O succinctly and profoundly reveals the basis of its molecular structure, while the molecular weight of 156.27 g / mol accurately measures the "heavyweight" of this compound in the material world. In terms of physical properties, dihydroterpineol exhibits a moderate melting point (about 35°C), which means that it can be transformed from solid to liquid at a lower temperature, making it easy to handle and apply; and its boiling point (about 210°C) ensures that it can remain stable and not easily volatile in many industrial processes.

[0003] In industrial production, the value of dihydroterpineol has been fully demonstrated. As one of the important raw materials for making perfumes, its smell is softer and more elegant than terpineol, which makes it a powerful assistant in the hands of perfumers, especially in the pursuit of cost-effective low-cost household perfume formulas, dihydroterpineol is an indispensable role. In addition, it is also widely used in the preparation of industrial solvents such as conductive pastes and glass pastes, showing its diverse practical functions.

[0004] When it comes to the preparation process of dihydroterpineol, the hydrogenation reaction is undoubtedly the most critical step. In this process, metal catalysts play a vital role, among which nickel (Ni) and palladium (Pd) are favored due to their excellent catalytic performance. In particular, Raney nickel catalyst, with its high catalytic efficiency, occupies a pivotal position in the production of dihydroterpineol. However, just as everything has its two sides, Raney nickel catalyst is not perfect in practical applications.

[0005] First, the catalytic properties of Raney nickel are too extensive. Although this increases the flexibility of its application to a certain extent, it is also easy to cause a series of side reactions in the hydrogenation reaction, thereby reducing the selectivity and content of the main product, dihydroterpineol. This not only affects the purity of the product, but also increases the cost of subsequent separation and purification. Secondly, the Raney nickel catalyst is easily attacked by oxidation or sulfidation during the reaction, resulting in reduced catalyst activity or even complete deactivation, which will undoubtedly seriously affect the efficiency and economic benefits of the reaction. Furthermore, the mechanical strength of the Raney nickel catalyst is relatively weak, and it is easy to pulverize or fail during a long reaction process, which not only shortens the service life of the catalyst, but also may pollute the reaction system. Summary of the invention

[0006] The purpose of the present invention is to provide a preparation process of high-content dihydroterpineol, so that the catalyst of the present invention can significantly increase the content of dihydroterpineol and improve the selectivity.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A preparation process of high-content dihydroterpineol, comprising the steps of adding α-terpineol into a reactor, adding a silica-supported platinum catalyst into the reactor, and uniformly mixing the catalyst with the α-terpineol; closing the reactor, introducing hydrogen, exhausting the air in the reactor, repeatedly flushing the reactor, and ensuring that the air in the reactor is completely replaced by hydrogen; setting the temperature of the reactor to 80-100°C and the pressure to 2-4MPa; starting a stirring device of the reactor and uniformly stirring the reactor; and after the reaction is completed, closing the hydrogen supply, stopping heating and stirring, and releasing the pressure in the reactor to reduce the pressure to 100°C. Normal pressure; opening the reactor, pouring out the reaction mixture, filtering and separating the catalyst and the liquid product, washing the catalyst, collecting the washing liquid, combining the reaction liquid and the washing liquid for purification to obtain a crude dihydroterpineol product, and rectifying the crude dihydroterpineol product through a rectification device to obtain a high-content dihydroterpineol product; the silica-supported platinum catalyst comprises the following raw materials in parts by weight: 10-22 parts of silica, 1-7 parts of chloroplatinic acid, 0.25-3 parts of an auxiliary agent solution, 1-2 parts of sodium dodecyl sulfate, and 0.1-0.4 parts of a reducing agent.

[0009] Furthermore, the auxiliary agent solution comprises a dispersant solution: a chelating agent solution: a complexing agent solution in a mass ratio of 2-5:1-2:1-3:.

[0010] Furthermore, the dispersant solution is prepared by dissolving chitosan in 1% acetic acid solution to obtain a solution with a concentration of 1-2 wt%.

[0011] Further, the chelating agent solution is prepared by dissolving citric acid in deionized water to obtain a solution with a concentration of 0.5-1 wt%;

[0012] Furthermore, the complexing agent solution is prepared by dissolving trimethylphosphine in ethanol to obtain a solution with a concentration of 0.5-1 wt%.

[0013] Furthermore, the reducing agent is sodium borohydride.

[0014] Furthermore, the preparation process of the silica-supported platinum catalyst comprises the following steps:

[0015] S1. Carrier treatment: Dry the cleaned silica sample at 100-120°C for 2-3 hours, and then keep it at 300-400°C for 3-4 hours to activate the silica;

[0016] S2. Carrier impregnation: impregnate the activated silica in the additive solution and disperse it ultrasonically for 0.5-1h;

[0017] S3, carrier aging: aging the impregnated silica at room temperature, washing and drying after aging to obtain a silica carrier;

[0018] S4, platinum loading: dissolve chloroplatinic acid in water to obtain a precursor solution; add the silica carrier to the precursor solution, add sodium dodecyl sulfate and a reducing agent, and stir for 2-4 hours;

[0019] S5. Drying and reduction: washing, drying and reducing the loaded silica to obtain a silica-loaded platinum catalyst.

[0020] Furthermore, in S2, the ultrasonic power is 100-200W and the temperature is 25-40°C.

[0021] Furthermore, in S3, the aging time is 12-48 hours.

[0022] Furthermore, in S5, the reduction method is: maintaining in a hydrogen atmosphere at 300-400° C. for 2-4 hours.

[0023] The principles of the raw material components of the silica-supported platinum catalyst of the present invention are as follows:

[0024] Silica: Silica is an acidic oxide with relatively stable chemical properties. It does not react with halogens other than fluorine and hydrogen fluoride, hydrogen halides, sulfuric acid, nitric acid, and perchloric acid. It can avoid reacting with trace impurities in the reaction raw materials to cause catalyst poisoning, thereby ensuring the activity and selectivity of the catalyst. For example, there may be some trace halogen impurities in the reaction system. When using traditional Raney nickel catalysts, these impurities may react with the catalyst and deactivate the catalyst, but silica-supported platinum catalysts can effectively avoid this situation.

[0025] Silica has a porous structure, which gives it a high specific surface area. Its internal pores and surfaces can provide a large number of adsorption sites. When the reactant molecules approach the catalyst, they will be adsorbed on these sites, thereby increasing the concentration of the reactant molecules on the catalyst surface, which is conducive to the forward reaction, increasing the reaction rate, and improving the selectivity of the reaction. At the same time, the silicon-oxygen bond (Si-O) of silica has a high bond energy and high mechanical strength, which prevents the catalyst from being broken or pulverized and deactivated due to mechanical stirring, material flow and other factors during the reaction process, and can also prevent the catalyst from being poisoned and deactivated due to impurities reacting with it.

[0026] Chloroplatinic acid: As a precursor of platinum, it forms a platinum catalyst with high catalytic activity after reduction. The platinum catalyst can effectively accelerate the hydrogenation reaction of α-pinene alcohol. In the mechanism of the hydrogenation reaction, it can interact with the double bonds in the α-pinene alcohol molecule, break the double bonds and combine with hydrogen atoms, thereby efficiently converting α-pinene alcohol into dihydropinene alcohol, improving the reaction efficiency and selectivity of the target product. During the catalytic reaction, platinum ions can be reduced to metallic platinum (Pt) under appropriate conditions. The atomic structure of metallic platinum gives it a special electron cloud distribution, and its d-orbital electrons can form adsorption and activation effects with reactant molecules. This adsorption and activation can reduce the activation energy required for the reactant molecules to react.

[0027] Chitosan: dispersant. The chitosan molecular chain contains a large number of active groups such as hydroxyl (-OH) and amino (-NH2). These groups can form hydrogen bonds with platinum ions, and through hydroxyl or electrostatic effects, the platinum ions are kept dispersed in the solution. At the same time, the steric hindrance effect of the chitosan molecular chain also plays an important role. The molecular chain will occupy a certain space in the solution, preventing the metal ion particles from agglomerating due to the van der Waals force and other forces. In terms of electronic structure, the amino group in chitosan has the ability to donate electrons. It forms electronic interactions with metal ions such as platinum and regulates the electron cloud density of the metal ions. According to the electronic effect theory of catalytic reactions, changes in the electron cloud density will affect the catalytic activity of metal ions, making them more conducive to the target reaction.

[0028] In the preparation of chitosan solution, since chitosan molecular chains contain a large number of hydroxyl groups (-OH) and amino groups (-NH2), in an acidic environment, the amino groups will be protonated, making the chitosan molecules positively charged. The acetic acid solution provides an acidic environment, and the ionized hydrogen ions combine with the amino groups in the chitosan molecules. This protonation increases the solubility of chitosan in the solution. At the same time, the hydrogen bonding between the chitosan molecular chains will be weakened due to protonation, and the molecular chains will be stretched, which is more conducive to dispersion in the solution.

[0029] Citric acid: Chelating agent. Citric acid contains multiple coordination groups such as carboxyl (-COOH) and hydroxyl (-OH). These groups can chelate with metal ions such as platinum ions. The lone pair of electrons of carboxyl and hydroxyl groups can form coordination bonds with metal ions to form stable chelates. This chelation can control the activity and distribution of metal ions. The formation of chelates changes the chemical environment of metal ions, redistributes their electron cloud density, and makes it easier to interact with reactants. As an organic acid, citric acid can affect the protonation degree of α-terpineol, which is beneficial to the formation and stability of reaction intermediates, thereby promoting the reaction.

[0030] In the preparation of citric acid solution, citric acid is an organic acid containing multiple carboxyl groups (-COOH) and hydroxyl groups (-OH). When it is dissolved in deionized water, the carboxyl groups and hydroxyl groups will ionize. The carboxyl groups will partially ionize hydrogen ions to form carboxylate ions (-COO - ), and the hydroxyl group can also form hydrogen bonds with water molecules. This ionization and hydrogen bonding effect allows citric acid to be evenly dispersed in water to form a stable solution.

[0031] Trimethylphosphine: Coordinating agent. There are lone pairs of electrons on the phosphorus atoms in the trimethylphosphine molecule, and these lone pairs of electrons can form coordination bonds with platinum atoms. This coordination effect can change the electron cloud density and spatial configuration of the platinum atom. The formation of coordination bonds will cause the electron cloud of the platinum atom to change, which in turn affects the way and intensity of its interaction with the reactant molecules. At the same time, the trimethylphosphine molecule has a certain spatial volume, and after coordinating with the platinum atom, it will produce a steric hindrance effect. When the reactant molecules are close to the catalyst surface, this steric hindrance will affect the adsorption position and reaction pathway of the reactant molecules, causing the reaction to proceed in a direction that is conducive to the production of dihydroterpineol.

[0032] In the preparation of trimethylphosphine solution, trimethylphosphine is an organic phosphorus compound with lone pairs of electrons on its phosphorus atom. Ethanol is an organic solvent with good solubility. The phosphorus atoms in the trimethylphosphine molecules can be dissolved with the ethanol molecules through weak interactions such as van der Waals forces and dipole-dipole interactions. In the ethanol solution, the trimethylphosphine molecules can move freely, providing conditions for the subsequent coordination reaction with the platinum atoms.

[0033] Sodium dodecyl sulfate: The molecular structure of sodium dodecyl sulfate contains hydrophilic and hydrophobic groups. In solution, the hydrophobic groups interact with the surface of the particles, while the hydrophilic groups extend into the solution. This structure causes the surface of the particles to be charged or form a hydration layer. The increase in the surface charge of the particles will lead to an increase in the repulsive force between the particles, thereby preventing the particles from agglomerating due to interactions such as van der Waals forces.

[0034] Sodium borohydride: Reducing agent. In the catalyst preparation process, it can reduce the platinum ions in chloroplatinic acid to metallic platinum (Pt). The reduction principle is based on the reducing property of hydrogen atoms in sodium borohydride, which can provide electrons to platinum ions, so that they can obtain electrons and be reduced, so that platinum is loaded on the silica carrier in a suitable metallic state, thereby ensuring that the platinum catalyst has catalytic activity for the subsequent dihydroterpineol synthesis reaction.

[0035] The principle of the preparation process of the silica-supported platinum catalyst of the present invention is:

[0036] S1. Carrier treatment: The cleaned silica contains water and some impurities. Dry at 100-120℃ for 2-3h, and use the temperature to evaporate the water. The dried silica is kept at 300-400℃ for 3-4h for activation. The high temperature changes some chemical bonds on the surface of the silica, producing more active sites. High temperature treatment can fine-tune the lattice structure of silica, exposing more unsaturated bonds, which can interact with the subsequent impregnated substances.

[0037] S2. Carrier impregnation: Silica is impregnated in the additive solution, and the various components in the additive solution will diffuse and adsorb on the surface of silica. Under the conditions of ultrasonic dispersion with a power of 100-200W and a temperature of 25-40℃ for 0.5-1h, the local high temperature, high pressure environment, strong shock waves and microjets generated by ultrasonic cavitation will accelerate the diffusion process of substances in the solution. Ultrasound enables the molecules in the solution to obtain more energy, speeding up their movement, thereby promoting the adsorption of the components in the additive solution to the surface of silica.

[0038] S3. Carrier aging: After impregnation, the silica is aged at room temperature. During this process, the components of the additive solution impregnated on the surface of the silica will gradually interact and stabilize, and the components will further react and adjust to reach a stable state. This allows the various components impregnated on the surface of the silica to fully react and stably combine, thereby improving the stability and uniformity of the catalyst.

[0039] S4. Platinum loading: Platinum ions are uniformly adsorbed on the surface of the silica carrier through stirring, and sodium dodecyl sulfate is used to prevent agglomeration. The platinum ions are then converted into metallic platinum through the reduction effect of sodium borohydride to achieve platinum loading on the silica carrier, forming a catalyst core with catalytic activity.

[0040] S5, Drying and Reduction: Washing and drying the loaded silica is to remove surface impurities and unreacted substances. Reduction is carried out in a hydrogen atmosphere at 300-400°C for 2-4 hours. The hydrogen atmosphere provides a reducing environment. At this temperature, the platinum catalyst can be kept in the best active state. Appropriate temperature and reducing gas atmosphere can adjust the crystal structure and electronic state of platinum, making it have higher catalytic activity, and finally obtain a silica-loaded platinum catalyst with good performance for the synthesis reaction of dihydroterpineol.

[0041] Compared with the prior art, the present invention has the following technical advantages:

[0042] (1) The present invention uses a silica-supported catalyst to prepare dihydroterpineol, and the silica-supported platinum catalyst combines the advantages of silica and platinum. Platinum has extremely high catalytic activity and can effectively accelerate the hydrogenation reaction of α-terpineol, so that the reaction can achieve a higher conversion rate in a shorter time. At the same time, platinum has good selectivity for the target product dihydroterpineol, can accurately catalyze the conversion of α-terpineol into dihydroterpineol, reduce the occurrence of side reactions, thereby increasing the content of dihydroterpineol and reducing the generation of by-products. At the same time, silica as a carrier has good wear resistance and a higher melting point, high mechanical strength, and is not prone to pulverization or failure during the reaction process, providing a stable physical support for the platinum catalyst. In addition, the silica carrier can reduce the contact between the platinum catalyst and external substances, reduce the risk of catalyst deactivation, and enable the catalyst to maintain a higher activity for a longer period of time, thereby increasing the content of dihydroterpineol.

[0043] (2) In the auxiliary agent solution of the present invention, chitosan can make various substances dispersed evenly, prevent agglomeration, and can also adjust the electron cloud density of metal ions; citric acid controls the activity and distribution of metal ions through chelation and adjusts the acidic environment; trimethylphosphine adjusts the properties of the catalyst active center through coordination and can also produce a steric hindrance effect. The three components are used together and can interact with each other to synergistically improve the content and selectivity of dihydroterpineol.

[0044] (3) In the preparation process of the present invention, a surfactant, sodium dodecyl sulfate, is added. The hydrophobic group of sodium dodecyl sulfate interacts with the particle surface, and the hydrophilic group extends into the solution, so that the particle surface is charged or a hydration layer is formed, which increases the repulsive force between particles, thereby preventing the particles from agglomerating due to interactions such as van der Waals forces. This allows the active components of the catalyst to be better dispersed on the carrier surface, thereby improving the activity and stability of the catalyst. At the same time, sodium dodecyl sulfate can form micelles in the solution. The size and structure of the micelles will affect the growth of the catalyst particles, which helps to prepare catalyst particles with a smaller particle size and uniform distribution, and is beneficial to the effect of the catalyst.

[0045] (4) In the preparation process of the present invention, when silicon dioxide is impregnated, the local high temperature, high pressure environment, strong shock waves and microjets generated by ultrasonic cavitation during ultrasonic dispersion will have an impact and shearing effect on the silicon dioxide particles, making their particle size smaller, which is beneficial to increase the specific surface area and the number of active sites of the catalyst, thereby enhancing the catalytic performance of the catalyst. At the same time, ultrasonic dispersion can accelerate the transfer process of substances in the impregnation liquid, including the diffusion of active components to the surface of silicon dioxide particles and the detachment of reaction products, thereby increasing the rate of the impregnation reaction, shortening the preparation cycle, and improving production efficiency. In addition, under the action of the ultrasonic field, it helps to form a more stable chemical bond or interaction between the active component and the silicon dioxide, further improving the performance and stability of the catalyst.

[0046] (5) The present invention can effectively convert α-terpineol into dihydroterpineol in the synthesis process of dihydroterpineol. As shown in the experimental data, the content of dihydroterpineol in the embodiments is generally high, up to 97.9%, that is, most of the α-terpineol can be converted into the target product, which improves the utilization rate of the raw materials, thereby obtaining higher economic benefits in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a structural schematic diagram of the distillation equipment of the present invention;

[0049] Figure 2 It is a structural schematic diagram of the defoaming device in the present invention;

[0050] Figure 3 It is a structural schematic diagram of the connecting mechanism in the present invention;

[0051] Figure 4 It is a structural schematic diagram of the lifting mechanism in the present invention;

[0052] Figure 5 It is a structural schematic diagram of the rotating mechanism in the present invention;

[0053] Figure 6 It is a structural schematic diagram of the cleaning mechanism in the present invention;

[0054] Figure 7 This is a picture of a dihydroterpineol product prepared by using the silica-supported platinum catalyst of the present invention.

[0055] Figure 1-6In: 1. Tower kettle; 2. Measuring tank; 3- Defoaming device; 4. Filter; 5. Raw material storage tank; 6. Reflux distributor; 7. Condenser; 8. Cooler; 9. Vacuum pump; 10. Tail gas recovery tank; 11. Buffer tank; 12. Kettle residue tank; 13. Main heater; 14. First tower section; 15. Liquid distributor; 16. Second tower section; 17. Second liquid distributor; 18. Third tower section; 19. Auxiliary heater;

[0056] 310, connecting mechanism; 320, lifting mechanism; 330, rotating mechanism; 340, cleaning mechanism; 350, defoaming disc;

[0057] 311, inlet pipe; 312, support seat; 313, outlet pipe;

[0058] 321. telescopic rod; 322. bracket; 323. connecting rod;

[0059] 331. rotating rod; 332. gear; 333. gear seat;

[0060] 341. Support plate; 342. Rotating shaft; 343. Cleaning brush. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and preferred embodiments. However, it should be noted that many details listed in the specification are only for the purpose of enabling the reader to have a thorough understanding of one or more aspects of the present invention, and these aspects of the present invention can be implemented even without these specific details.

[0062] In an embodiment of the present invention, the silica-supported platinum catalyst is made of the following raw materials in parts by weight: 10-22 parts of silica, 1-7 parts of chloroplatinic acid, 0.25-3 parts of an auxiliary solution, 1-2 parts of sodium dodecyl sulfate, and 0.1-0.4 parts of sodium borohydride.

[0063] The auxiliary agent solution comprises a dispersant solution: a chelating agent solution: a complexing agent solution in a mass ratio of 2-5: 1-2: 1-3.

[0064] The dispersant solution is prepared by dissolving chitosan in 1% acetic acid solution to obtain a solution with a concentration of 1-2wt%; the chelating agent solution is prepared by dissolving citric acid in deionized water to obtain a solution with a concentration of 0.5-1wt%; and the complexing agent solution is prepared by dissolving trimethylphosphine in ethanol to obtain a solution with a concentration of 0.5-1wt%.

[0065] The preparation process of the silica-supported platinum catalyst comprises the following steps:

[0066] S1. Carrier treatment: Dry the cleaned silica sample at 100-120°C for 2-3 hours, and then keep it at 300-400°C for 3-4 hours to activate the silica;

[0067] S2. Carrier impregnation: impregnate the activated silica in the additive solution and disperse it ultrasonically at a power of 100-200W and a temperature of 25-40°C for 0.5-1h;

[0068] S3, carrier aging: aging the impregnated silica at room temperature for 12-48 hours, washing and drying after the aging to obtain a silica carrier;

[0069] S4, platinum loading: dissolve chloroplatinic acid in water to obtain a precursor solution; add the silica carrier to the precursor solution, add sodium dodecyl sulfate and sodium borohydride, and stir for 2-4 hours;

[0070] S5. Drying and reduction: washing, drying and reducing the loaded silica, and maintaining the reduction in a hydrogen atmosphere at 300-400° C. for 2-4 hours to obtain a silica-loaded platinum catalyst.

[0071] A preparation process of high-content dihydroterpineol comprises the following steps: adding α-terpineol into a high-pressure reactor, adding a silica-supported platinum catalyst into the reactor, and uniformly mixing the catalyst with the α-terpineol; closing the reactor, introducing hydrogen, exhausting the air in the reactor, repeatedly flushing the reactor, and ensuring that the air in the reactor is completely replaced by hydrogen; setting the temperature of the reactor to 80-100°C and the pressure to 2-4MPa; starting a stirring device of the reactor and uniformly stirring the reactor; after the reaction is completed, closing the hydrogen supply, stopping heating and stirring, and slowly releasing the pressure in the reactor to reduce the pressure to normal pressure; opening the reactor, pouring out the reaction mixture, filtering and separating the catalyst and the liquid phase product, washing the catalyst, collecting the washing liquid, combining the reaction liquid and the washing liquid, and purifying the mixture to obtain a dihydroterpineol crude product; and rectifying the dihydroterpineol crude product through a rectification device to obtain a high-content dihydroterpineol product.

[0072] See also Figure 1-6The distillation equipment comprises a tower kettle 1, a metering tank 2, a defoaming device 3, a filter 4, a raw material storage tank 5, a reflux distributor 6, a condensation cooling system, a vacuum system, a kettle residue tank 12, a main heater 13, a tower body, a liquid distributor, and an auxiliary heater 19. The tower body comprises several tower sections, such as a first tower section 14, a second tower section 16, and a third tower section 18. Several tower plates are arranged in the tower sections. The liquid distributor comprises several, such as a first liquid distributor 15 and a second liquid distributor 17. The liquid distributor is arranged between the tower sections. The lower part of the defoaming device 3 is connected to the upper part of the tower kettle 1, and the upper part of the defoaming device 3 is connected to the lower part of the first tower section 14. The upper part of the first tower section 14 is connected to the lower part of the first liquid distributor 15, and the upper part of the first liquid distributor 15 is connected to the second tower section 18. The lower part of the tower section 16 is connected, the upper part of the second tower section 16 is connected to the lower part of the second liquid distributor 17, the upper part of the second liquid distributor 15 is connected to the lower part of the third tower section 18, the upper part of the third tower section 18 is connected to the lower part of the reflux distributor 6, the raw material storage tank 5, the filter 4, and the metering tank 2 are connected in series through a pipeline and connected to the feed port of the tower kettle 1, the condensation cooling system is installed on the top of the reflux distributor 6, and the top of the tower body is connected to the vacuum system through a pipeline, the main heater 13 is installed in the tower kettle 1, the middle part of the auxiliary heater 19 is connected to the bottom of the tower kettle 1 through a pipeline, the top of the auxiliary heater 19 is connected to the middle part of the tower kettle 1 through a pipeline, the bottom of the auxiliary heater 19 is connected to the kettle residual tank 12 through a pipeline, and the kettle residual tank 12 is connected to the vacuum system through a pipeline.

[0073] The defoaming device 3 is used to eliminate bubbles generated by the raw materials in the tower bottom. The defoaming device 3 includes a connecting mechanism 310, a lifting mechanism 320, a rotating mechanism 330, a cleaning mechanism 340 and a defoaming plate 350. The connecting mechanism 310 is provided with a lifting mechanism 320, the bottom of the lifting structure 320 is connected to the rotating mechanism 330, the bottom of the rotating mechanism 330 is connected to the defoaming plate 350, and the defoaming plate 350 is provided with a rotating mechanism 340.

[0074] The connecting mechanism 310 is used to connect the tower kettle 1 and the tower body; the connecting mechanism 310 includes an inlet pipe 311 connected to the top of the tower kettle 1, the top of the inlet pipe 311 is connected to a support seat 312, the top of the support seat 312 is connected to an outlet pipe 313 for connecting to the tower body, the diameters of the inlet pipe 311 and the outlet pipe 313 are both smaller than the diameter of the support seat 312, the support seat 312 is a hollow cylindrical structure, the support seat 312 is used to connect the inlet pipe 311 and the outlet pipe 313, and the top of the outlet pipe 313 is connected to the bottom of the tower body.

[0075] The defoaming plate 350 is used to eliminate bubbles generated during the distillation of raw materials; the defoaming plate 350 moves and rotates in the support seat 312. The defoaming plate 350 is a disc-shaped structure. A plurality of through holes are provided on the defoaming plate 350. A mesh is provided on the top of the through holes. The sizes of the plurality of through holes on the defoaming plate 350 are different.

[0076] The lifting mechanism 320 is used to push the cleaning mechanism 340 to rise and fall; the lifting mechanism 320 includes a telescopic rod 321 arranged on the top of the support seat 312, the protruding end of the telescopic rod 321 is connected to the bracket 322 and is used to push the bracket 322 to rise and fall, the bottom of the bracket 322 is connected to the connecting rod 323, the telescopic rod 321 is provided with at least two groups of symmetrically distributed on the top of the support seat 312 outside the inlet pipe 311, the telescopic rod 321 can be selected from electric, hydraulic and pneumatic telescopic rods, the bracket 322 is a hollow circular ring structure, the bracket 322 is sleeved on the inlet pipe 311, and the bottom of the connecting rod 323 moves through the support seat 312 and is connected to the support plate 341.

[0077] According to the use requirements, the telescopic rod 321 is driven, and the telescopic rod 321 is extended and retracted to push the bracket 322 to rise and fall. The cleaning mechanism 340 is made to follow the rise and fall through the connecting rod 323 and the rotating rod 331. From the above connection relationship, it can be known that the defoaming plate 350 follows the rise and fall of the cleaning mechanism 340, and then the height of the defoaming plate 350 in the support seat 312 is adjusted, so that the height of the defoaming plate 350 can be adjusted according to the needs to meet various bubble bursting needs.

[0078] The rotating mechanism 330 is used to drive the defoaming plate 350 to rotate; the rotating mechanism 330 includes a rotating rod 331 rotatably clamped on the bracket 322, the bottom of the rotating rod 331 rotates through the support seat 312 and the support plate 341 and is connected to a gear 332, the gear 332 is engaged with the tooth seat 333 to drive the tooth seat 333 to rotate, and the top of the rotating rod 331 is connected to a motor for driving the rotating rod 331 to rotate, the motor is arranged on the bracket 322, the rotating rod 331 is rotatably clamped on the bracket 322 and the support plate 341, that is, the rotating rod 331 can rotate on the bracket 322 and the support plate 341, but cannot move up and down in the bracket 322 and the support plate 341, the rotating rod 331 moves and rotates through the support seat 312, and the tooth seat 333 is arranged on the top of the defoaming plate 350.

[0079] The cleaning mechanism 340 is used to clean the residual foam on the defoaming disk 350; the cleaning mechanism 340 includes a support plate 341 connected to the bottom of the connecting rod 323, and a rotating shaft 342 is provided at the center of the bottom of the support plate 341. The bottom end of the rotating shaft 342 is connected to the defoaming disk 350 and is used to support the rotation of the defoaming disk 350. The support plate 341 is a long plate-like structure, and the length of the support plate 341 is less than or equal to the diameter of the defoaming disk 350. The cleaning brush 343 is provided with at least two groups of support plate 341 bottoms symmetrically distributed on the outside of the rotating shaft 342, and the bottom of the cleaning brush 343 frictionally contacts the defoaming disk 350.

[0080] The motor is driven, and the motor drives the rotating rod 331 to rotate. The rotating rod 331 rotates, and the rotating rod 331 rotates to rotate the gear 332. The gear 332 engages with the gear seat 333 to drive the defoaming disk 350 to rotate. The defoaming disk 350 rotates under the support plate 341 through the rotating shaft 342. The defoaming disk 350 rotates to contact the cleaning brush 343 to clean the foam or other debris on the defoaming disk 350, so that the defoaming disk 350 is easy to clean, thereby ensuring a good circulation state of steam and defoaming efficiency, and improving the overall work efficiency.

[0081] The condensation cooling system includes a condenser 7 and a cooler 8. The condenser 7 is installed on the top of the tower body, and the cooler 8 is installed outside the tower body. The cooler 8 is connected to the condenser 7 and the reflux distributor 6 through a pipeline. The condenser 7 is installed on the top of the tower body 6 to cool the steam, and the required components are collected after condensation.

[0082] The vacuum system includes a vacuum pump 9, a tail gas recovery tank 10 and a buffer tank 11. The vacuum pump 9, the tail gas recovery tank 10 and the buffer tank 11 are connected in sequence through pipelines. The buffer tank 11 is connected to the top of the tower body through a pipeline. The kettle residue tank 12 is connected to the buffer tank 11 through a pipeline. The buffer tank 11 can keep the negative pressure in the tower body stable to avoid air pressure fluctuations caused by starting and stopping the vacuum pump 9. The tail gas recovery tank 10 can filter the tail gas to prevent the raw materials entrained in the air flow from entering the vacuum pump 9 and affecting the operation of the vacuum pump 9.

[0083] The main heater 13 comprises a heating plate, and the heating plate is embedded in the tower kettle 1 through a head.

[0084] The tower body is filled with fillers, which are in contact with steam to reduce the temperature of the steam, so that components with higher boiling points are condensed and refluxed, while components with lower boiling points remain in gaseous form and continue to rise.

[0085] Technical principle of the distillation equipment of the present invention:

[0086] During distillation, the equipment of the present invention forms a negative pressure in the tower body through the vacuum pump 9. When the valve between the metering tank 2 and the tower bottom 1 is opened, the crude dihydropinene alcohol product is sucked from the metering tank 2 into the tower bottom 1 under the action of the negative pressure. After the tower bottom 1 is heated by the main heater 13, the crude dihydropinene alcohol product is evaporated. The distillation of the crude dihydropinene alcohol product is carried out under a high-temperature vacuum state, and the gas velocity fluctuates greatly. Bubbles are easily formed on the surface of the crude dihydropinene alcohol product. After the bubbles accumulate to a certain extent, they begin to rise through the inlet pipe 311 into the support seat 312. When they contact the defoaming disk 350, the fine through holes on the defoaming disk 350 restrict the bubbles larger than the aperture thereof from passing therethrough and burst the bubbles, thereby achieving the purpose of defoaming, avoiding the crude dihydropinene alcohol product from impacting the tower top, affecting the product quality, and causing a loss of tons of crude dihydropinene alcohol. At the same time, the tiny holes on the defoaming plate 350 support the flow of steam to ensure the normal progress of distillation. The steam of the crude dihydropinene alcohol after defoaming enters the tower body from the outlet pipe 313, passes through the filler gaps in the tower body, and by controlling the temperature, the components of other components are condensed and refluxed, while the steam of the required components rises to the top of the tower body, is cooled, condensed and collected in the condenser, so as to achieve the purpose of distillation and obtain a high-content dihydropinene alcohol product. After the distillation is completed, the residual liquid is discharged into the residual tank 12 by utilizing the pressure difference between the kettle residue tank 12 and the tower bottom 1, and then the pressure difference between the raw material storage tank 4 and the tower bottom 1 is utilized to inject the crude dihydropinene alcohol into the tower bottom 1, and the distillation operation is continued, so as to realize the cyclic operation of the processes of feeding, distilling and discharging the crude dihydropinene alcohol, which can greatly save expenses and energy consumption.

[0087] The unique design of the distillation equipment of the present invention lies in its efficient and flexible distillation process. The tower bottom 1 is accurately heated by a precisely controlled main heater. This step not only ensures the uniform evaporation of the crude dihydroterpineol product, but also the entire distillation process is carried out in a specially designed high-temperature vacuum environment. Such an environment greatly promotes the fluctuation of the gas velocity, making it very easy to form fine and continuous bubbles on the surface of the crude dihydroterpineol product. These bubbles continue to accumulate on the liquid surface of the crude dihydroterpineol product until they reach a certain volume and density, and then begin to rise under the action of buoyancy, pass through the inlet pipe 311, and smoothly enter the internal space of the support seat 312.

[0088] Once the bubbles come into contact with the innovative defoaming disk 350, the densely distributed tiny through holes on its surface play a key role, which can effectively limit the passage of bubbles larger than its pore size, forcing the bubbles to be squeezed and burst at the moment of contact, thereby effectively reducing the interference of bubbles on the steam flow. At the same time, the tiny holes on the defoaming disk 350 not only ensure the bursting of bubbles, but also cleverly support the smooth flow of steam, ensuring the continuity and efficiency of the distillation process. The crude dihydropinene vapor that has undergone defoaming treatment smoothly enters the tower body through the outlet pipe 313, shuttles through the carefully designed filler gaps inside the tower body, and is temperature controlled, so that the unnecessary components are condensed and refluxed to the tower bottom, while the vapor of the target component continues to rise until it reaches the top of the tower body, and finally undergoes cooling and condensation in the condenser and is effectively collected, thereby completing the entire distillation process.

[0089] Another highlight of the present invention lies in its height adjustability and automatic cleaning function; according to different needs in actual operation, by driving the telescopic action of the telescopic rod 321, the bracket 322 can be flexibly pushed up and down, and this action drives the entire cleaning mechanism 340 and the defoaming plate 350 to rise and fall through the linkage effect of the connecting rod 323 and the rotating rod 331, thereby realizing the precise adjustment of the height of the defoaming plate 350 in the support seat 312. This enables the present invention to flexibly adjust the height of the defoaming plate according to specific working conditions to meet the needs of different bubble bursting, greatly enhancing the adaptability and practicality of the equipment.

[0090] Furthermore, when it is necessary to clean the defoaming disc 350, the motor is started, and the motor drives the rotating rod 331 to rotate, thereby driving the gear 332 connected thereto to rotate synchronously. The precise engagement of the gear 332 with the gear seat 333 ensures that the defoaming disc 350 rotates stably under the support plate 341 through the rotating shaft 342. This rotation action allows the surface of the defoaming disc 350 to evenly and comprehensively contact the cleaning brush 343, thereby effectively cleaning off the foam, impurities, etc. attached to the defoaming disc, ensuring that the steam channel is unobstructed, improving the defoaming efficiency, and thus significantly improving the overall work efficiency.

[0091] The following is a more specific example.

[0092] Example 1

[0093] A silicon dioxide-supported platinum catalyst is prepared from the following raw materials in parts by weight: 14 parts of silicon dioxide, 6 parts of chloroplatinic acid, 0.25 parts of an auxiliary agent solution, 2 parts of sodium dodecyl sulfate, and 0.4 parts of sodium borohydride.

[0094] The auxiliary agent solution comprises a dispersant solution: a chelating agent solution: a complexing agent in a mass ratio of 3:2:3.

[0095] The dispersant solution is prepared by dissolving chitosan in 1% acetic acid solution to obtain a solution with a concentration of 2wt%; the chelating agent solution is prepared by dissolving citric acid in deionized water to obtain a solution with a concentration of 0.5wt%; and the ligand solution is prepared by dissolving trimethylphosphine in ethanol to obtain a solution with a concentration of 0.5wt%.

[0096] The preparation process of the silica-supported platinum catalyst comprises the following steps:

[0097] S1. Carrier treatment: The cleaned silica sample was dried at 105°C for 3 hours, and then kept at 400°C for 3.8 hours to activate the silica;

[0098] S2. Carrier impregnation: The activated silica was immersed in the additive solution and ultrasonically dispersed at a power of 200 W and a temperature of 28°C for 0.8 h;

[0099] S3, carrier aging: aging the impregnated silica at room temperature for 24 hours, washing and drying after the aging to obtain a silica carrier;

[0100] S4, platinum loading: dissolve chloroplatinic acid in water to obtain a precursor solution; add the silica carrier to the precursor solution, add sodium dodecyl sulfate and sodium borohydride, and stir for 4 hours;

[0101] S5. Drying and reduction: washing, drying and reducing the loaded silica, and maintaining the reduction in a hydrogen atmosphere at 400° C. for 3 h to obtain a silica-loaded platinum catalyst.

[0102] A preparation process of high-content dihydroterpineol comprises the following steps: adding α-terpineol into a high-pressure reactor, adding a silica-supported platinum catalyst into the reactor, and uniformly mixing the catalyst with the α-terpineol; closing the reactor, introducing hydrogen, exhausting the air in the reactor, repeatedly flushing the reactor, and ensuring that the air in the reactor is completely replaced by hydrogen; setting the temperature of the reactor to 80°C and the pressure to 3MPa; starting a stirring device of the reactor and uniformly stirring the reactor; after the reaction is completed, closing the hydrogen supply, stopping heating and stirring, and slowly releasing the pressure in the reactor to reduce the pressure to normal pressure; opening the reactor, pouring out the reaction mixture, filtering and separating the catalyst and the liquid phase product, washing the catalyst, collecting the washing liquid, combining the reaction liquid and the washing liquid, and purifying the mixture to obtain a dihydroterpineol crude product; and rectifying the dihydroterpineol crude product through a rectification device to obtain a high-content dihydroterpineol product.

[0103] Example 2

[0104] A silicon dioxide-supported platinum catalyst is prepared from the following raw materials in parts by weight: 10 parts of silicon dioxide, 7 parts of chloroplatinic acid, 1 part of an auxiliary agent solution, 2 parts of sodium dodecyl sulfate, and 0.3 parts of sodium borohydride.

[0105] The auxiliary agent solution comprises a dispersant solution: a chelating agent solution: a complexing agent solution in a mass ratio of 5:2:1.

[0106] The dispersant solution is prepared by dissolving chitosan in 1% acetic acid solution to obtain a solution with a concentration of 2wt%; the chelating agent solution is prepared by dissolving citric acid in deionized water to obtain a solution with a concentration of 1wt%; and the ligand solution is prepared by dissolving trimethylphosphine in ethanol to obtain a solution with a concentration of 1wt%.

[0107] The preparation process of the silica-supported platinum catalyst comprises the following steps:

[0108] S1. Carrier treatment: The cleaned silica sample was dried at 118°C for 2.8 hours, and then kept at 400°C for 3.5 hours to activate the silica;

[0109] S2. Carrier impregnation: The activated silica was immersed in the additive solution and ultrasonically dispersed at a power of 180 W and a temperature of 35°C for 0.5 h;

[0110] S3, carrier aging: aging the impregnated silica at room temperature for 48 hours, washing and drying after the aging to obtain a silica carrier;

[0111] S4, platinum loading: dissolve chloroplatinic acid in water to obtain a precursor solution; add the silica carrier to the precursor solution, add sodium dodecyl sulfate and sodium borohydride, and stir for 4 hours;

[0112] S5. Drying and reduction: washing, drying and reducing the loaded silica, and maintaining the reduction in a hydrogen atmosphere at 380° C. for 2 h to obtain a silica-loaded platinum catalyst.

[0113] A preparation process of high-content dihydroterpineol comprises the following steps: adding α-terpineol into a high-pressure reactor, adding a silica-supported platinum catalyst into the reactor, and uniformly mixing the catalyst with the α-terpineol; closing the reactor, introducing hydrogen, exhausting the air in the reactor, repeatedly flushing the reactor, and ensuring that the air in the reactor is completely replaced by hydrogen; setting the temperature of the reactor to 90°C and the pressure to 2MPa; starting a stirring device of the reactor and uniformly stirring the reactor; after the reaction is completed, closing the hydrogen supply, stopping heating and stirring, and slowly releasing the pressure in the reactor to reduce the pressure to normal pressure; opening the reactor, pouring out the reaction mixture, filtering and separating the catalyst and the liquid phase product, washing the catalyst, collecting the washing liquid, combining the reaction liquid and the washing liquid, and purifying the mixture to obtain a dihydroterpineol crude product; and rectifying the dihydroterpineol crude product through a rectification device to obtain a high-content dihydroterpineol product.

[0114] Example 3

[0115] A silicon dioxide-supported platinum catalyst is prepared from the following raw materials in parts by weight: 18 parts of silicon dioxide, 5 parts of chloroplatinic acid, 1.7 parts of an auxiliary agent solution, 1.4 parts of sodium dodecyl sulfate, and 0.3 parts of sodium borohydride.

[0116] The auxiliary agent solution comprises a dispersant solution: a chelating agent solution: a complexing agent solution in a mass ratio of 2:1:1.

[0117] The dispersant solution is prepared by dissolving chitosan in 1% acetic acid solution to obtain a solution with a concentration of 1wt%; the chelating agent solution is prepared by dissolving citric acid in deionized water to obtain a solution with a concentration of 1wt%; and the complexing agent solution is prepared by dissolving trimethylphosphine in ethanol to obtain a solution with a concentration of 0.5wt%.

[0118] The preparation process of the silica-supported platinum catalyst comprises the following steps:

[0119] S1. Carrier treatment: The cleaned silica sample was dried at 110°C for 2.5 hours, and then kept at 300°C for 4 hours to activate the silica;

[0120] S2. Carrier impregnation: The activated silica was immersed in the additive solution and ultrasonically dispersed at a power of 160 W and a temperature of 32° C. for 1 h;

[0121] S3, carrier aging: aging the impregnated silica at room temperature for 18 hours, washing and drying after the aging to obtain a silica carrier;

[0122] S4, platinum loading: dissolve chloroplatinic acid in water to obtain a precursor solution; add the silica carrier to the precursor solution, add sodium dodecyl sulfate and sodium borohydride, and stir for 3 hours;

[0123] S5. Drying and reduction: washing, drying and reducing the loaded silica, and maintaining the reduction in a hydrogen atmosphere at 400° C. for 3.5 hours to obtain a silica-loaded platinum catalyst.

[0124] A preparation process of high-content dihydroterpineol comprises the following steps: adding α-terpineol into a high-pressure reactor, adding a silica-supported platinum catalyst into the reactor, and uniformly mixing the catalyst with the α-terpineol; closing the reactor, introducing hydrogen, exhausting the air in the reactor, and repeatedly flushing the reactor to ensure that the air in the reactor is completely replaced by hydrogen; setting the temperature of the reactor to 100° C. and the pressure to 2 MPa; starting a stirring device of the reactor and uniformly stirring the reactor; after the reaction is completed, closing the hydrogen supply, stopping heating and stirring, and slowly releasing the pressure in the reactor to reduce the pressure to normal pressure; opening the reactor, pouring out the reaction mixture, filtering and separating the catalyst and the liquid phase product, washing the catalyst, collecting the washing liquid, combining the reaction liquid and the washing liquid, and purifying the crude dihydroterpineol product; and the crude dihydroterpineol product is rectified by a rectification device to obtain a high-content dihydroterpineol product. Figure 7 .

[0125] Example 4

[0126] A silicon dioxide-supported platinum catalyst is prepared from the following raw materials in parts by weight: 17 parts of silicon dioxide, 1 part of chloroplatinic acid, 2 parts of an auxiliary agent solution, 1 part of sodium dodecyl sulfate, and 0.2 part of sodium borohydride.

[0127] The auxiliary agent solution comprises a dispersant solution: a chelating agent solution: a complexing agent solution in a mass ratio of 4:1:3.

[0128] The dispersant solution is prepared by dissolving chitosan in 1% acetic acid solution to obtain a solution with a concentration of 2wt%; the chelating agent solution is prepared by dissolving citric acid in deionized water to obtain a solution with a concentration of 0.5wt%; and the ligand solution is prepared by dissolving trimethylphosphine in ethanol to obtain a solution with a concentration of 0.8wt%.

[0129] The preparation process of the silica-supported platinum catalyst comprises the following steps:

[0130] S1. Carrier treatment: The cleaned silica sample was dried at 120°C for 3 hours, and then kept at 400°C for 3 hours to activate the silica;

[0131] S2. Carrier impregnation: The activated silica was immersed in the additive solution and ultrasonically dispersed at a power of 100 W and a temperature of 25°C for 1 h;

[0132] S3, carrier aging: aging the impregnated silica at room temperature for 12 hours, washing and drying after the aging to obtain a silica carrier;

[0133] S4, platinum loading: dissolve chloroplatinic acid in water to obtain a precursor solution; add the silica carrier to the precursor solution, add sodium dodecyl sulfate and sodium borohydride, and stir for 2 hours;

[0134] S5. Drying and reduction: washing, drying and reducing the loaded silica, and maintaining the reduction in a hydrogen atmosphere at 300° C. for 2.6 h to obtain a silica-loaded platinum catalyst.

[0135] A preparation process of high-content dihydroterpineol comprises the following steps: adding α-terpineol into a high-pressure reactor, adding a silica-supported platinum catalyst into the reactor, and uniformly mixing the catalyst with the α-terpineol; closing the reactor, introducing hydrogen, exhausting the air in the reactor, repeatedly flushing the reactor, and ensuring that the air in the reactor is completely replaced by hydrogen; setting the temperature of the reactor to 85°C and the pressure to 4MPa; starting a stirring device of the reactor and uniformly stirring the reactor; after the reaction is completed, closing the hydrogen supply, stopping heating and stirring, and slowly releasing the pressure in the reactor to reduce the pressure to normal pressure; opening the reactor, pouring out the reaction mixture, filtering and separating the catalyst and the liquid phase product, washing the catalyst, collecting the washing liquid, combining the reaction liquid and the washing liquid, and purifying the mixture to obtain a dihydroterpineol crude product; and rectifying the dihydroterpineol crude product through a rectification device to obtain a high-content dihydroterpineol product.

[0136] Example 5

[0137] A silicon dioxide-supported platinum catalyst is prepared from the following raw materials in parts by weight: 20 parts of silicon dioxide, 4 parts of chloroplatinic acid, 3 parts of auxiliary agent solution, 1 part of sodium dodecyl sulfate, and 0.25 parts of sodium borohydride.

[0138] The auxiliary agent solution comprises a dispersant solution: a chelating agent solution: a complexing agent solution in a mass ratio of 2:2:1.

[0139] The dispersant solution is prepared by dissolving chitosan in 1% acetic acid solution to obtain a solution with a concentration of 1wt%; the chelating agent solution is prepared by dissolving citric acid in deionized water to obtain a solution with a concentration of 0.8wt%; and the ligand solution is prepared by dissolving trimethylphosphine in ethanol to obtain a solution with a concentration of 0.5wt%.

[0140] The preparation process of the silica-supported platinum catalyst comprises the following steps:

[0141] S1. Carrier treatment: The cleaned silica sample was dried at 115°C for 2 hours, and then kept at 300°C for 3.2 hours to activate the silica;

[0142] S2. Carrier impregnation: The activated silica was immersed in the additive solution and ultrasonically dispersed at a power of 120 W and a temperature of 40° C. for 1 h;

[0143] S3, carrier aging: aging the impregnated silica at room temperature for 36 hours, washing and drying after the aging to obtain a silica carrier;

[0144] S4, platinum loading: dissolve chloroplatinic acid in water to obtain a precursor solution; add the silica carrier to the precursor solution, add sodium dodecyl sulfate and sodium borohydride, and stir for 2 hours;

[0145] S5. Drying and reduction: washing, drying and reducing the loaded silica, and maintaining the reduction in a hydrogen atmosphere at 350° C. for 3 h to obtain a silica-loaded platinum catalyst.

[0146] A preparation process of high-content dihydroterpineol comprises the following steps: adding α-terpineol into a high-pressure reactor, adding a silica-supported platinum catalyst into the reactor, and uniformly mixing the catalyst with the α-terpineol; closing the reactor, introducing hydrogen, exhausting the air in the reactor, repeatedly flushing the reactor, and ensuring that the air in the reactor is completely replaced by hydrogen; setting the temperature of the reactor to 95°C and the pressure to 3MPa; starting a stirring device of the reactor and uniformly stirring the reactor; after the reaction is completed, closing the hydrogen supply, stopping heating and stirring, and slowly releasing the pressure in the reactor to reduce the pressure to normal pressure; opening the reactor, pouring out the reaction mixture, filtering and separating the catalyst and the liquid phase product, washing the catalyst, collecting the washing liquid, combining the reaction liquid and the washing liquid, and purifying the mixture to obtain a dihydroterpineol crude product; and rectifying the dihydroterpineol crude product through a rectification device to obtain a high-content dihydroterpineol product.

[0147] Comparative Example 1

[0148] It is basically the same as Example 3, except that no auxiliary agent solution is added to the catalyst.

[0149] Comparative Example 2

[0150] The method is basically the same as Example 3, except that, in the catalyst, the additive solution does not contain citric acid and trimethylphosphine, but only contains chitosan.

[0151] Comparative Example 3

[0152] The method is basically the same as Example 3, except that chitosan and trimethylphosphine are not added to the catalyst additive solution, but only citric acid is used.

[0153] Comparative Example 4

[0154] The method is basically the same as Example 3, except that, in the catalyst, chitosan and citric acid are not added to the additive solution, but only trimethylphosphine is used.

[0155] Comparative Example 5

[0156] The method is basically the same as Example 3, except that sodium dodecyl sulfate is not added in the preparation process of the catalyst.

[0157] Comparative Example 6

[0158] It is basically the same as Example 3, except that in the preparation process of the catalyst, the silicon dioxide is not ultrasonically dispersed.

[0159] 1. Test of dihydroterpineol content

[0160] Dihydroterpineol was prepared according to the process of Examples 1-5 and Comparative Examples 1-6, and the content of dihydroterpineol was detected, as shown in Table 1.

[0161] Table 1 Dihydroterpineol content

[0162]

[0163]

[0164] It can be seen from Table 1 that:

[0165] (1) In Examples 1-5 of the present invention, the contents of dihydroterpineol are 97.5%, 96.4%, 97.9%, 96.8% and 97.2%, respectively, and the content of Example 3 reaches 97.9%, indicating that the silica-supported platinum catalyst of the present invention has the advantage of high content when preparing dihydroterpineol.

[0166] This is because: in the silica-supported platinum catalyst of the present invention, silica is an acidic oxide with relatively stable chemical properties. It does not react with halogens other than fluorine and hydrogen fluoride, hydrogen halides, sulfuric acid, nitric acid, and perchloric acid, and can avoid reacting with trace impurities in the reaction raw materials to cause catalyst poisoning, thereby ensuring the activity and selectivity of the catalyst; at the same time, silica has a very high specific surface area and strong adsorption, which can increase the catalytic efficiency of the catalyst, provide more active sites for the reaction, and is beneficial to the adsorption of reactant molecules and the progress of the reaction, thereby increasing the reaction rate; in addition, silica has good wear resistance and a high melting point, and high mechanical strength. As a catalyst carrier, it is not easy to pulverize or fail during the reaction.

[0167] Platinum catalysts have extremely high catalytic activity and can effectively accelerate the hydrogenation reaction of α-pinene alcohol, improve reaction efficiency, achieve a higher conversion rate in a shorter time, and enable the reaction to proceed efficiently. At the same time, platinum catalysts have good selectivity for the target product dihydropinene alcohol in the hydrogenation reaction and can accurately catalyze the conversion of α-pinene alcohol into dihydropinene alcohol, reduce the occurrence of side reactions, thereby increasing the content of dihydropinene alcohol and reducing the generation of by-products.

[0168] Platinum loading on silica can make the platinum catalyst more evenly dispersed and improve its stability. At the same time, the silica carrier plays a certain protective role on the platinum catalyst, reducing the contact of the platinum catalyst with external substances during the reaction process, reducing the risk of catalyst deactivation, and enabling it to maintain a high activity for a longer period of time.

[0169] Therefore, the present invention adopts a silicon dioxide-supported platinum catalyst, which can significantly increase the content of dihydroterpineol and reduce by-products.

[0170] (2) In Comparative Examples 1-4 in which the auxiliary agent solution of the present invention is not used or all the components of the auxiliary agent solution of the present invention are not fully used, the contents of dihydroterpineol are 82.3%, 89.4%, 87.5% and 85.8%, respectively, which are all lower than those of Examples 1-5 of the present invention. This indicates that in the auxiliary agent solution of the present invention, chitosan, citric acid and trimethylphosphine can interact with each other and synergistically enhance the synergy, thereby significantly increasing the content of dihydroterpineol.

[0171] This is because: in the additive solution of the present invention, the chitosan molecular chain contains a large number of active groups such as hydroxyl and amino groups. In the additive solution, these groups can form hydrogen bonds or electrostatic effects with metal ions, etc., wrap them and disperse them, and at the same time, the steric hindrance effect of its molecular chain can prevent the particles from approaching each other. When preparing the catalyst, chitosan can make metal ions such as platinum and substances such as citric acid and trimethylphosphine evenly dispersed during the impregnation process, prevent agglomeration, and ensure that each component is evenly distributed on the catalyst carrier, thereby improving the performance and stability of the catalyst, enabling the catalytic reaction to be carried out more efficiently, and then increasing the content of dihydroterpineol; at the same time, the amino group in chitosan has a certain electron-donating ability, which can form electronic interactions with metal ions such as platinum, regulate the electron cloud density of metal ions, and affect its catalytic activity. When coexisting with citric acid and trimethylphosphine, this electronic regulation may cooperate with the chelation of citric acid and the coordination of trimethylphosphine, further optimize the electronic structure of the catalyst, and make the catalyst have better selectivity and activity for the synthesis reaction of dihydroterpineol, thereby increasing the content.

[0172] Citric acid contains multiple coordination groups such as carboxyl and hydroxyl groups, which can chelate with metal ions such as platinum ions to form stable chelates. In the process of catalyst preparation, this chelation can control the activity and distribution of metal ions, making them more evenly dispersed on the surface of the carrier, preventing them from agglomerating or over-reducing, thereby improving the activity and stability of the catalyst. At the same time, the formation of chelates can also change the electron cloud density and chemical environment of metal ions, making them more likely to interact with reactants and improve the efficiency of catalytic reactions. When acting together with chitosan and trimethylphosphine, the chelation of citric acid can cooperate with the dispersing effect of chitosan to further improve the dispersion of each component in the catalyst; and its regulation of the electron cloud density of metal ions may also produce a synergistic effect with the coordination effect of trimethylphosphine, jointly optimizing the performance of the catalyst and increasing the content of dihydroterpineol; in addition, citric acid is an organic acid that can play a certain role in acid regulation in the reaction system. A suitable acidic environment is helpful for the activation of reactants and the progress of the reaction, and can ensure the protonation degree of α-terpineol and the stability of reaction intermediates, thereby promoting the formation of dihydroterpineol.

[0173] As a coordination agent, the lone pair of electrons on the phosphorus atom of trimethylphosphine can form a coordination bond with the platinum atom. This coordination can change the electron cloud density and spatial configuration of the platinum atom, thereby affecting the catalytic efficiency and selectivity of the platinum catalyst for the synthesis of dihydroterpineol. When coexisting with chitosan and citric acid, the coordination of trimethylphosphine can cooperate with the electronic effect of chitosan and the chelation of citric acid to more accurately adjust the properties of the active center of the catalyst, so that the catalyst can more effectively activate the reactant molecules, reduce the activation energy of the reaction, and increase the reaction rate and selectivity, thereby significantly increasing the content of dihydroterpineol; at the same time, the trimethylphosphine molecule has a certain spatial volume, and after coordinating with the platinum atom, it will produce a steric hindrance effect. This steric hindrance can affect the adsorption and reaction process of the reactant molecules on the catalyst surface, so that the reaction proceeds in a direction that is conducive to the formation of dihydroterpineol, thereby improving the selectivity of the product. At the same time, the presence of chitosan and citric acid may also have a certain impact on this steric hindrance effect. The three interact and coordinate with each other to further optimize the selectivity and content of the reaction.

[0174] Therefore, in the auxiliary agent solution of the present invention, chitosan, citric acid and trimethylphosphine act together to synergistically enhance the effect and significantly increase the content of dihydroterpineol.

[0175] (3) In the comparative example 5 in which the sodium dodecyl sulfate of the present invention was not added during the preparation of the catalyst, the content of dihydroterpineol was 92.7%, which was also lower than that of the embodiments 1-5 of the present invention. This indicates that the addition of sodium dodecyl sulfate during the preparation of the catalyst of the present invention can improve the catalyst performance, thereby increasing the content of dihydroterpineol.

[0176] This is because: the molecular structure of sodium dodecyl sulfate usually contains hydrophilic and hydrophobic groups. The hydrophobic groups can interact with the surface of the particles, while the hydrophilic groups extend into the solution, so that the surface of the particles is charged or forms a hydration layer, thereby increasing the repulsive force between the particles and preventing the particles from agglomerating due to interactions such as van der Waals forces. For example, when preparing a catalyst, adding an appropriate amount of sodium dodecyl sulfate can better disperse the active components of the catalyst on the surface of the carrier, thereby improving the activity and stability of the catalyst. At the same time, sodium dodecyl sulfate can form micelles in the solution, and the size and structure of the micelles will affect the growth of the catalyst particles. When the catalyst precursor chloroplatinic acid precipitates or crystallizes in the solution, the sodium dodecyl sulfate molecules will be adsorbed on the surface of the particles, limiting the growth direction and rate of the particles, thereby helping to prepare catalyst particles with smaller particle size and uniform distribution, which is beneficial to the effect of the catalyst.

[0177] (4) In the preparation process of the catalyst, in Comparative Example 6 in which ultrasonic dispersion was not performed, the content of dihydroterpineol was 93.5%, which was not as good as that of Examples 1-5 of the present invention. This shows that the present invention can improve the performance of the catalyst by ultrasonically dispersing the silicon dioxide during the impregnation process, thereby preparing the content of dihydroterpineol.

[0178] This is because: during the ultrasonic dispersion process, the local high temperature, high pressure environment, strong shock waves and microjets generated by ultrasonic cavitation will have an impact and shear effect on the silica particles, making their particle size smaller, which is beneficial to increase the specific surface area of ​​the catalyst and the number of active sites of the catalyst, thereby enhancing the catalytic performance of the catalyst; at the same time, ultrasonic dispersion can accelerate the transfer process of substances in the impregnation liquid, including the diffusion of active components to the surface of silica particles and the detachment of reaction products, thereby increasing the rate of the impregnation reaction, shortening the preparation cycle, and improving production efficiency; in addition, under the action of the ultrasonic field, it helps to form a more stable chemical bond or interaction between the active components and silica, further improving the performance and stability of the catalyst.

[0179] The above content cannot be used to determine that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the concept of the present invention, which should be regarded as belonging to the scope of patent protection of the present invention determined by the submitted claims.

Claims

1. A preparation process for high-content dihydroterpineol, characterized in that: Add α-terpineol to the reactor, add silica-supported platinum catalyst to the reactor, and mix them evenly with α-terpineol; close the reactor, introduce hydrogen, exhaust the air in the reactor, and repeatedly flush the reactor to ensure that the air in the reactor is completely replaced by hydrogen; set the temperature of the reactor to 80-100°C and the pressure to 2-4MPa; start the stirring device of the reactor and stir evenly; after the reaction is completed, turn off the hydrogen supply, stop heating and stirring, and release the pressure in the reactor to normal pressure; The reaction kettle is opened, the reaction mixture is poured out, the catalyst and the liquid phase product are separated by filtering, the catalyst is washed, the washing liquid is collected, the reaction liquid and the washing liquid are combined and purified to obtain a crude dihydroterpineol product, and the crude dihydroterpineol product is rectified by a rectification device to obtain a high-content dihydroterpineol product; the silica-supported platinum catalyst comprises the following raw materials in parts by weight: 10-22 parts of silica, 1-7 parts of chloroplatinic acid, 0.25-3 parts of an auxiliary agent solution, 1-2 parts of sodium dodecyl sulfate, and 0.1-0.4 parts of a reducing agent.

2. The preparation process of high-content dihydroterpineol according to claim 1, characterized in that: The auxiliary agent solution comprises a dispersant solution: a chelating agent solution: a complexing agent solution in a mass ratio of 2-5:1-2:1-3.

3. The preparation process of high-content dihydroterpineol according to claim 2, characterized in that: The dispersant solution is prepared by dissolving chitosan in 1% acetic acid solution to obtain a solution with a concentration of 1-2 wt%.

4. The preparation process of high-content dihydroterpineol according to claim 2, characterized in that: The chelating agent solution is prepared by dissolving citric acid in deionized water to obtain a solution with a concentration of 0.5-1 wt%.

5. The preparation process of high-content dihydroterpineol according to claim 2, characterized in that: The complexing agent solution is prepared by dissolving trimethylphosphine in ethanol to obtain a solution with a concentration of 0.5-1 wt%.

6. The preparation process of high-content dihydroterpineol according to claim 1, characterized in that: The reducing agent is sodium borohydride.

7. The process for preparing high-content dihydroterpineol according to any one of claims 1 to 6, characterized in that: The preparation process of the silica-supported platinum catalyst comprises the following steps: S1. Carrier treatment: Dry the cleaned silica sample at 100-120°C for 2-3 hours, and then keep it at 300-400°C for 3-4 hours to activate the silica; S2. Carrier impregnation: impregnate the activated silica in the additive solution and disperse it ultrasonically for 0.5-1h; S3, carrier aging: aging the impregnated silica at room temperature, washing and drying after aging to obtain a silica carrier; S4, platinum loading: dissolve chloroplatinic acid in water to obtain a precursor solution; add the silica carrier to the precursor solution, add sodium dodecyl sulfate and a reducing agent, and stir for 2-4 hours; S5. Drying and reduction: washing, drying and reducing the loaded silica to obtain a silica-loaded platinum catalyst.

8. The process for preparing high-content dihydroterpineol according to claim 7, characterized in that: In S2, the ultrasonic power is 100-200W and the temperature is 25-40°C.

9. The process for preparing high-content dihydroterpineol according to claim 7, characterized in that: In S3, the aging time is 12-48 hours.

10. The process for preparing high-content dihydroterpineol according to claim 7, characterized in that: In the S5, the reduction method is: maintaining in a hydrogen atmosphere at 300-400° C. for 2-4 hours.

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