A process for the preparation of dihydromyrcenol
By using the modified HZSM-5 catalyst, the problem of high temperature and high pressure in the preparation of dihydroterpineol was solved, and a continuous hydrogenation reaction at low temperature and low pressure was realized, which improved product purity and yield and reduced production costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUJIAN SHAXIAN QINGZHOU DAILY USE CHEM CO LTD
- Filing Date
- 2026-05-12
- Publication Date
- 2026-07-10
AI Technical Summary
Existing methods for preparing dihydroterpineol involve harsh hydrogenation reaction conditions, requiring high temperature and pressure, poor catalyst selectivity, and are prone to side reactions, resulting in poor product stability.
Using a Pd-Mn-La/modified HZSM-5 catalyst, the pore size of the HZSM-5 molecular sieve is expanded by fluorine ion etching and amino functionalization sites are introduced. Combined with Mn-La double doping, a ternary active center is formed to carry out a continuous hydrogenation reaction, and the by-products are separated by distillation.
The preparation temperature and pressure were reduced, the stability and selectivity of the catalyst were improved, the production process was simplified, the purity and yield of dihydroterpineol were increased, and the production cost was reduced.
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Abstract
Description
Technical Field
[0001] This application relates to the field of terpene fragrance synthesis technology, and in particular to a method for preparing dihydroterpineol. Background Technology
[0002] Dihydroterpineol is an important monoterpene fragrance compound with a soft, elegant woody, floral, and camphor-like aroma. Its fragrance is long-lasting and stable, resistant to acids and alkalis, and does not easily deteriorate. It is widely used in the daily chemical fragrance, detergent, cosmetic, food flavoring, and pharmaceutical intermediate industries. It can also serve as a key intermediate in the synthesis of other high-end terpene derivatives, and has a large market demand. Industrially, dihydroterpineol is mainly prepared from turpentine oil, α-terpineol, and isoprene as starting materials through addition, hydrogenation, and isomerization reactions.
[0003] In existing technologies, the main method used is the liquid-phase catalytic hydrogenation of α-terpineol, using Raney nickel and palladium on carbon as hydrogenation catalysts. Under high temperature and high pressure hydrogen atmosphere, a batch reactor is used to saturately hydrogenate and reduce the intramolecular double bonds of α-terpineol. The product is then purified by distillation to obtain dihydroterpineol. Some other processes use a two-step synthesis route of inorganic acid catalytic hydration followed by hydrogenation reduction. Turpentine oil is used as a raw material, which is first hydrated to generate a mixture of terpineols, and then further catalytically hydrogenated to prepare dihydroterpineol.
[0004] However, the existing preparation methods have harsh hydrogenation reaction conditions, requiring high temperature and medium-high pressure hydrogen environment. Furthermore, the Raney nickel and palladium carbon catalysts have poor selectivity and are prone to side reactions, producing isomerization and over-hydrogenation byproducts. In addition, the short lifespan of the catalysts leads to poor product stability, which needs to be improved. Summary of the Invention
[0005] In view of this, the purpose of this application is to provide a method for preparing dihydroterpineol, so as to reduce the difficulty of preparation and achieve continuous industrial production. The specific method is as follows: A method for preparing dihydroterpineol, comprising the following steps: Step 1, Preparation: Prepare α-terpineol, solvent, catalyst, hydrogen, and co-catalyst for later use; Step 2, Pretreatment: Mix 90-100 parts of α-terpineol with 75-80 parts of solvent once and stir until homogeneous, then add 0.08-0.1 parts of co-catalyst and mix again until homogeneous to obtain the stock solution; Step 3, continuous hydrogenation: The raw liquid is pumped into a fixed-bed reactor filled with catalyst, while hydrogen is introduced and the temperature is controlled at 80-90℃ to carry out continuous feeding and discharging to obtain the reaction liquid; Step 4, distillation and purification: Distill the reaction solution to obtain dihydroterpineol; The catalyst is a Pd-Mn-La / modified HZSM-5 catalyst.
[0006] Preferably, in step 1, the solvent is anhydrous ethanol; the co-catalyst is nano zinc oxide with a particle size of 50-100 nm.
[0007] Preferably, in step 2, the first stirring is to control the stirring speed at 250-300 r / min and stir at room temperature for 20-25 min, and the second stirring is to continue stirring for 8-10 min.
[0008] Preferably, in step 3, the catalyst filling amount in the fixed-bed reactor is 18-20% of the reactor volume, and the catalyst bed height to diameter ratio is 4.5-5:1; the feed rate of the raw liquid is 1.5-1.6 mL / min; the molar ratio of hydrogen to α-terpineol is 1.2:1, the inlet pressure is 0.8-1.0 MPa, and the hydrogen flow rate is 40 mL / min.
[0009] Preferably, the preparation method of the Pd-Mn-La / modified HZSM-5 catalyst includes an HZSM-5 molecular sieve modification part and a doping modification part; the HZSM-5 molecular sieve modification part is to treat HZSM-5 molecular sieve with fluorine ion etching and amino functionalization to obtain a modified HZSM-5 catalyst; the doping modification part is to modify HZSM-5 catalyst with Pd main active and Mn-La dual doping treatment to obtain Pd-Mn-La / modified HZSM-5 catalyst.
[0010] Preferably, the HZSM-5 molecular sieve modification process includes: Step ① washing the HZSM-5 molecular sieve with deionized water until neutral, and then drying it at 105-110℃ for 12-13 hours to obtain clean HZSM-5 molecular sieve; Step ② immersing the clean HZSM-5 molecular sieve in an NH4F aqueous solution, stirring at 58-62℃ for 4-4.5 hours, filtering, washing with deionized water until fluoride-free, and then drying it at 105-110℃ for 7.5-8 hours to obtain etched HZSM-5; Step ③ immersing the etched HZSM-5 in a 3-aminopropyltriethoxysilane / ethanol solution, refluxing it at 68-72℃ for 5.5-6 hours, filtering, washing it multiple times with anhydrous ethanol, drying it at 118-122℃ for 9-10 hours, and calcining it at 530-550℃ for 4-4.2 hours to obtain the modified HZSM-5 support.
[0011] Preferably, the NH4F aqueous solution has a mass fraction of 8%, and the solid-liquid ratio after mixing with the NH4F aqueous solution is 1:15 g / mL; the 3-aminopropyltriethoxysilane / ethanol solution has a mass fraction of 5%, and the solid-liquid ratio after mixing with the 3-aminopropyltriethoxysilane / ethanol solution is 1:20 g / mL.
[0012] Preferably, the doping modification includes step ① mixing and stirring PdCl2, Mn(NO3)2·4H2O and La(NO3)3·6H2O with deionized water in a mass ratio of 1.5-2.5:2-3:2-3, and adjusting the pH to 2-2.5 to obtain a composite impregnation solution; step ② adding the modified HZSM-5 support to the composite impregnation solution and allowing it to stand at room temperature for 12-14 hours to obtain the impregnated support; step ③ drying the impregnated support at 108-112℃ for 12-14 hours, and then subjecting it to high-temperature calcination and hydrogen reduction treatment to obtain the Pd-Mn-La / modified HZSM-5 catalyst.
[0013] Preferably, the solid-liquid ratio of the modified HZSM-5 support to the composite impregnation solution is 1:10 g / mL; the high-temperature calcination treatment involves raising the temperature to 500℃ at a controlled heating rate of 5℃ / min, calcining for 5 hours, and then cooling to room temperature; the hydrogen gas treatment reduction treatment involves controlling the hydrogen gas flow rate at 50 mL / min, reducing at 280℃ for 3 hours, and then cooling to obtain the Pd-Mn-La / modified HZSM-5 catalyst.
[0014] Preferably, in step 4, the distillation includes a first-stage distillation for distilling anhydrous ethanol, a second-stage distillation for distilling α-terpineol, and a third-stage distillation for distilling dihydroterpineol; the first-stage distillation has a reboil temperature of 80°C, a top temperature of 78°C, and a vacuum of 0.08 MPa; the second-stage distillation has a reboil temperature of 120°C, a top temperature of 105°C, and a vacuum of 0.09 MPa; and the third-stage distillation has a reboil temperature of 140°C, a top temperature of 125°C, and a vacuum of 0.095 MPa.
[0015] As can be seen from the above scheme, this application provides a method for preparing dihydroterpineol, which has the following beneficial effects: 1. By enlarging the pore size of HZSM-5 molecular sieve through fluoride ion etching and providing stable loading sites through amino functionalization, the aggregation and loss of Pd particles are effectively suppressed. Furthermore, the Mn-La dual doping forms a ternary synergistic active center with Pd. Mn regulates the electron cloud density of Pd, and La further stabilizes the active sites, making the Pd-Mn-La / modified HZSM-5 catalyst have the characteristics of continuous use and regeneration, thereby significantly reducing losses and lowering the cost of industrial production. 2. By employing Pd-Mn-La / modified HZSM-5 catalyst in a fixed-bed reactor The process achieves continuous hydrogenation steps, thereby stabilizing the preparation temperature at 80-90℃ and the pressure at 0.8-1.0MPa to efficiently catalyze the hydrogenation reaction of α-terpineol. At the same time, the continuous feeding and discharging simplifies the overall preparation process, reduces equipment investment and production risks, and is suitable for large-scale continuous production. 3. The Pd-Mn-La / modified HZSM-5 catalyst effectively suppresses the excessive hydrogenation and isomerization side reactions of α-terpineol during the hydrogenation process. This enhances the adsorption effect of the modified HZSM-5 support, improving the contact efficiency between the raw material and the active site. The co-catalyst further enhances the catalytic selectivity. At the same time, the distillation process efficiently separates the solvent, unreacted raw material, and byproducts, thereby significantly improving the purity and yield of dihydroterpineol and effectively reducing distillation energy consumption and preparation costs. Detailed Implementation
[0016] The technical solutions described below in conjunction with the embodiments of this application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0017] It should be mentioned that the Si / Al ratio of the HZSM-5 molecular sieve in this embodiment is 25. Commercially available hydrochloric acid was used to adjust the pH, and intermittent stirring was performed during impregnation to improve loading uniformity. Anhydrous ethanol, also commercially available, was used as the solvent. The co-catalyst was nano-zinc oxide with a particle size of 50-100 nm, also commercially available.
[0018] The following will describe in detail a method for preparing dihydroterpineol according to this application.
[0019] A method for preparing dihydroterpineol, comprising the following steps: Step 1, Preparation: Prepare α-terpineol, solvent, catalyst, hydrogen, and co-catalyst for later use; Step 2, Pretreatment: Mix 90-100 parts of α-terpineol with 75-80 parts of solvent and stir once until homogeneous. Then add 0.08-0.1 parts of co-catalyst and mix twice until homogeneous to obtain the stock solution. Control the stirring speed of the first stirring at 250-300 r / min and stir at room temperature for 20-25 min. Continue stirring for 8-10 min for the second stirring. Step 3, Continuous hydrogenation: Pump the raw solution into a fixed-bed reactor filled with catalyst. Control the catalyst filling amount in the fixed-bed reactor to be 18-20% of the reactor volume, and the catalyst bed height to diameter ratio to be 4.5-5:1. Control the feed rate of the raw solution to be 1.5-1.6 mL / min. Simultaneously, introduce hydrogen gas and control the temperature to be 80-90℃ for continuous feeding and discharging. Control the molar ratio of hydrogen gas to α-terpineol to be 1.2:1, the pressure to be introduced to be 0.8-1.0 MPa, and the hydrogen gas flow rate to be 40 mL / min to obtain the reaction solution. Step 4, Distillation Purification: The reaction solution is distilled to obtain dihydroterpineol. The distillation includes a first-stage distillation for distilling anhydrous ethanol, a second-stage distillation for distilling α-terpineol, and a third-stage distillation for distilling dihydroterpineol. The bottom temperature of the first-stage distillation column is 80℃, the top temperature is 78℃, and the vacuum degree is 0.08MPa. The bottom temperature of the second-stage distillation column is 120℃, the top temperature is 105℃, and the vacuum degree is 0.09MPa. The bottom temperature of the third-stage distillation column is 140℃, the top temperature is 125℃, and the vacuum degree is 0.095MPa.
[0020] The catalyst used was a Pd-Mn-La / modified HZSM-5 catalyst.
[0021] In the embodiments of this application, the preparation method of the Pd-Mn-La / modified HZSM-5 catalyst includes an HZSM-5 molecular sieve modification part and a doping modification part; the HZSM-5 molecular sieve modification part is to treat the HZSM-5 molecular sieve with fluorine ion etching and amino functionalization to obtain a modified HZSM-5 catalyst; the doping modification part is to modify the HZSM-5 catalyst with Pd as the main active agent and Mn-La as the dual doping agent to obtain the Pd-Mn-La / modified HZSM-5 catalyst.
[0022] The HZSM-5 molecular sieve modification process includes step ① washing the HZSM-5 molecular sieve with deionized water until neutral, and then drying it at 105-110℃ for 12-13 hours to obtain clean HZSM-5 molecular sieve; step ② adding the clean HZSM-5 molecular sieve to an NH4F aqueous solution, controlling the solid-liquid ratio at 1:15 g / mL, stirring at 58-62℃ for 4-4.5 hours, filtering, and then washing with deionized water until fluoride ions are removed, followed by drying at 105-110℃. The HZSM-5 was dried at ℃ for 7.5-8h to obtain etched HZSM-5; in step ③, the etched HZSM-5 was added to a 5% (w / w) 3-aminopropyltriethoxysilane / ethanol solution, and the solid-liquid ratio was controlled at 1:20 g / mL. The mixture was refluxed at 68-72℃ for 5.5-6h, filtered, washed multiple times with anhydrous ethanol, dried at 118-122℃ for 9-10h, and calcined at 530-550℃ for 4-4.2h to obtain the modified HZSM-5 support.
[0023] The doping modification process includes step ① mixing PdCl2, Mn(NO3)2·4H2O and La(NO3)3·6H2O with deionized water in a mass ratio of 1.5-2.5:2-3:2-3, and adjusting the pH to 2-2.5 to obtain a composite impregnation solution; step ② adding the modified HZSM-5 support to the composite impregnation solution, controlling the solid-liquid ratio to 1:10 g / mL, and allowing it to stand at room temperature for 12-14 h to obtain the impregnated support; step ③ drying the impregnated support at 108-112℃ for 12-14 h, followed by a high-temperature calcination treatment of raising the temperature to 500℃ at a controlled heating rate of 5℃ / min and calcining for 5 h, then cooling to room temperature; a reduction treatment of reducing the hydrogen flow rate at 50 mL / min and at 280℃ for 3 h, followed by cooling to obtain the Pd-Mn-La / modified HZSM-5 catalyst.
[0024] Example 1 A method for preparing dihydroterpineol, comprising the following steps: Step 1, Preparation: Take α-terpineol, anhydrous ethanol, catalyst, hydrogen and nano zinc oxide for later use.
[0025] Step 2, Pretreatment: Mix 90 parts of α-terpineol with 75 parts of solvent once and stir until homogeneous. Then add 0.08 parts of co-catalyst and mix and stir again to obtain the stock solution. Control the stirring speed of the first stirring at 250 r / min and stir at room temperature for 20 min. The second stirring is to continue stirring for 8 min.
[0026] Step 3, Continuous Hydrogenation: The raw solution is pumped into a fixed-bed reactor filled with catalyst. The catalyst filling amount in the fixed-bed reactor is controlled to be 18% of the reactor volume, and the ratio of catalyst bed height to diameter is 4.5:1. The feed rate of the raw solution is controlled to be 1.5 mL / min. Hydrogen gas is introduced at the same time, and the temperature is controlled to be 80℃ for continuous feeding and discharging. The molar ratio of hydrogen gas to α-terpineol is controlled to be 1.2:1, the inlet pressure is 0.8 MPa, and the hydrogen gas flow rate is 40 mL / min to obtain the reaction solution.
[0027] Step 4, Distillation Purification: The reaction solution is distilled to obtain dihydroterpineol; the distillation includes a first-stage distillation for distilling anhydrous ethanol, a second-stage distillation for distilling α-terpineol, and a third-stage distillation for distilling dihydroterpineol; the bottom temperature of the first-stage distillation column is 80℃, the top temperature is 78℃, and the vacuum degree is 0.08MPa; the bottom temperature of the second-stage distillation column is 120℃, the top temperature is 105℃, and the vacuum degree is 0.09MPa; the bottom temperature of the third-stage distillation column is 140℃, the top temperature is 125℃, and the vacuum degree is 0.095MPa.
[0028] The catalyst is a Pd-Mn-La / modified HZSM-5 catalyst.
[0029] In this embodiment, the preparation method of the Pd-Mn-La / modified HZSM-5 catalyst includes an HZSM-5 molecular sieve modification part and a doping modification part; the HZSM-5 molecular sieve modification part is to treat the HZSM-5 molecular sieve with fluorine ion etching and amino functionalization to obtain the modified HZSM-5 catalyst; the doping modification part is to modify the HZSM-5 catalyst with Pd main active and Mn-La dual doping treatment to obtain the Pd-Mn-La / modified HZSM-5 catalyst.
[0030] The HZSM-5 molecular sieve modification process includes step ① washing the HZSM-5 molecular sieve with deionized water until neutral, and then drying it at 105℃ for 13 hours to obtain clean HZSM-5 molecular sieve; step ② adding the clean HZSM-5 molecular sieve to an NH4F aqueous solution, controlling the solid-liquid ratio at 1:15 g / mL, stirring at 58℃ for 4.5 hours, filtering, deionizing and washing until fluoride ions are removed, and then drying it at 105℃ for 8 hours to obtain etched HZSM-5 molecular sieve. SM-5; Step ③: Immerse the etched HZSM-5 in a 3-aminopropyltriethoxysilane / ethanol solution, control the solid-liquid ratio at 1:20 g / mL, reflux at 68℃ for 6 h, filter, wash multiple times with anhydrous ethanol, then dry at 118℃ for 10 h and calcine at 530℃ for 4.2 h to obtain the modified HZSM-5 support; the mass fraction of the NH4F aqueous solution is 8%, and the mass fraction of the 3-aminopropyltriethoxysilane / ethanol solution is 5%.
[0031] The doping modification process includes: Step ① mixing PdCl2, Mn(NO3)2•4H2O and La(NO3)3•6H2O with deionized water in a mass ratio of 1.5:2:2 and adjusting the pH to 2.0 to obtain a composite impregnation solution; Step ② adding the modified HZSM-5 support to the composite impregnation solution, controlling the solid-liquid ratio to 1:10 g / mL, and allowing it to stand at room temperature for 14 h to obtain the impregnated support; Step ③ drying the impregnated support at 108℃ for 14 h, followed by a high-temperature calcination treatment of raising the temperature to 500℃ at a controlled heating rate of 5℃ / min and calcining for 5 h, then cooling to room temperature; a reduction treatment of reducing the hydrogen flow rate at 50 mL / min and at 280℃ for 3 h, followed by cooling to obtain the Pd-Mn-La / modified HZSM-5 catalyst.
[0032] Example 2 A method for preparing dihydroterpineol, comprising the following steps: Step 1, Preparation: Take α-terpineol, anhydrous ethanol, catalyst, hydrogen and nano zinc oxide for later use.
[0033] Step 2, Pretreatment: Mix 95 parts of α-terpineol with 77 parts of solvent once and stir until homogeneous. Then add 0.09 parts of co-catalyst and mix and stir again to obtain the stock solution. Control the stirring speed of the first stirring at 280 r / min and stir at room temperature for 22 min. The second stirring is to continue stirring for 9 min.
[0034] Step 3, Continuous Hydrogenation: The raw solution is pumped into a fixed-bed reactor filled with catalyst. The catalyst filling amount in the fixed-bed reactor is controlled to be 19% of the reactor volume, and the catalyst bed height to diameter ratio is 4.75:1. The feed rate of the raw solution is controlled to be 1.55 mL / min. Hydrogen gas is introduced at the same time, and the temperature is controlled to be 85℃ for continuous feeding and discharging. The molar ratio of hydrogen gas to α-terpineol is controlled to be 1.2:1, the inlet pressure is 0.9 MPa, and the hydrogen gas flow rate is 40 mL / min to obtain the reaction solution.
[0035] Step 4, Distillation Purification: The reaction solution is distilled to obtain dihydroterpineol; the distillation includes a first-stage distillation for distilling anhydrous ethanol, a second-stage distillation for distilling α-terpineol, and a third-stage distillation for distilling dihydroterpineol; the bottom temperature of the first-stage distillation column is 80℃, the top temperature is 78℃, and the vacuum degree is 0.08MPa; the bottom temperature of the second-stage distillation column is 120℃, the top temperature is 105℃, and the vacuum degree is 0.09MPa; the bottom temperature of the third-stage distillation column is 140℃, the top temperature is 125℃, and the vacuum degree is 0.095MPa.
[0036] The catalyst is a Pd-Mn-La / modified HZSM-5 catalyst.
[0037] In this embodiment, the preparation method of the Pd-Mn-La / modified HZSM-5 catalyst includes an HZSM-5 molecular sieve modification part and a doping modification part; the HZSM-5 molecular sieve modification part is to treat the HZSM-5 molecular sieve with fluorine ion etching and amino functionalization to obtain the modified HZSM-5 catalyst; the doping modification part is to modify the HZSM-5 catalyst with Pd main active and Mn-La dual doping treatment to obtain the Pd-Mn-La / modified HZSM-5 catalyst.
[0038] The HZSM-5 molecular sieve modification process includes step ① washing the HZSM-5 molecular sieve with deionized water until neutral, and then drying it at 108℃ for 12.5h to obtain clean HZSM-5 molecular sieve; step ② adding the clean HZSM-5 molecular sieve to an NH4F aqueous solution, controlling the solid-liquid ratio at 1:15 g / mL, stirring at 60℃ for 4.2h, filtering, deionizing and washing until fluoride ions are removed, and then drying it at 108℃ for 7.8h to obtain etched HZSM-5 molecular sieve. SM-5; Step ③: Immerse the etched HZSM-5 in a 3-aminopropyltriethoxysilane / ethanol solution, control the solid-liquid ratio at 1:20 g / mL, reflux at 70℃ for 5.8 h, filter, wash multiple times with anhydrous ethanol, then dry at 120℃ for 9.5 h and calcine at 540℃ for 4.1 h to obtain the modified HZSM-5 support; the mass fraction of the NH4F aqueous solution is 8%, and the mass fraction of the 3-aminopropyltriethoxysilane / ethanol solution is 5%.
[0039] The doping modification process includes: Step ① mixing PdCl2, Mn(NO3)2•4H2O and La(NO3)3•6H2O with deionized water in a mass ratio of 2:2.5:2.5 and adjusting the pH to 2.2 to obtain a composite impregnation solution; Step ② adding the modified HZSM-5 support to the composite impregnation solution, controlling the solid-liquid ratio to 1:10 g / mL, and allowing it to stand at room temperature for 13 h to obtain the impregnated support; Step ③ drying the impregnated support at 110℃ for 13 h, followed by a high-temperature calcination treatment of raising the temperature to 500℃ at a controlled heating rate of 5℃ / min and calcining for 5 h, then cooling to room temperature; a reduction treatment of reducing the hydrogen flow rate at 50 mL / min and at 280℃ for 3 h, followed by cooling to obtain the Pd-Mn-La / modified HZSM-5 catalyst.
[0040] Example 3 A method for preparing dihydroterpineol, comprising the following steps: Step 1, Preparation: Take α-terpineol, anhydrous ethanol, catalyst, hydrogen and nano zinc oxide for later use.
[0041] Step 2, Pretreatment: Mix 100 parts of α-terpineol with 80 parts of solvent and stir once until homogeneous. Then add 0.1 parts of co-catalyst and mix twice until homogeneous to obtain the stock solution. Control the stirring speed of the first stirring at 300 r / min and stir at room temperature for 25 min. The second stirring is to continue stirring for 10 min.
[0042] Step 3, Continuous Hydrogenation: The raw solution is pumped into a fixed-bed reactor filled with catalyst. The catalyst filling amount in the fixed-bed reactor is controlled to be 20% of the reactor volume, and the ratio of catalyst bed height to diameter is 5:1. The feed rate of the raw solution is controlled to be 1.6 mL / min. Hydrogen gas is introduced at the same time, and the temperature is controlled to be 90℃ for continuous feeding and discharging. The molar ratio of hydrogen gas to α-terpineol is controlled to be 1.2:1, the inlet pressure is 1.0 MPa, and the hydrogen gas flow rate is 40 mL / min to obtain the reaction solution.
[0043] Step 4, Distillation Purification: The reaction solution is distilled to obtain dihydroterpineol; the distillation includes a first-stage distillation for distilling anhydrous ethanol, a second-stage distillation for distilling α-terpineol, and a third-stage distillation for distilling dihydroterpineol; the bottom temperature of the first-stage distillation column is 80℃, the top temperature is 78℃, and the vacuum degree is 0.08MPa; the bottom temperature of the second-stage distillation column is 120℃, the top temperature is 105℃, and the vacuum degree is 0.09MPa; the bottom temperature of the third-stage distillation column is 140℃, the top temperature is 125℃, and the vacuum degree is 0.095MPa.
[0044] The catalyst is a Pd-Mn-La / modified HZSM-5 catalyst.
[0045] In this embodiment, the preparation method of the Pd-Mn-La / modified HZSM-5 catalyst includes an HZSM-5 molecular sieve modification part and a doping modification part; the HZSM-5 molecular sieve modification part is to treat the HZSM-5 molecular sieve with fluorine ion etching and amino functionalization to obtain the modified HZSM-5 catalyst; the doping modification part is to modify the HZSM-5 catalyst with Pd main active and Mn-La dual doping treatment to obtain the Pd-Mn-La / modified HZSM-5 catalyst.
[0046] The HZSM-5 molecular sieve modification process includes step ① washing the HZSM-5 molecular sieve with deionized water until neutral, and then drying it at 110℃ for 12 hours to obtain clean HZSM-5 molecular sieve; step ② adding the clean HZSM-5 molecular sieve to an NH4F aqueous solution, controlling the solid-liquid ratio at 1:15 g / mL, stirring at 62℃ for 4 hours, filtering, deionizing and washing until fluoride ions are removed, and then drying it at 110℃ for 7.5 hours to obtain etched HZSM-5 molecular sieve. SM-5; Step ③: The etched HZSM-5 was added to a 3-aminopropyltriethoxysilane / ethanol solution, and the solid-liquid ratio was controlled at 1:20 g / mL. The mixture was refluxed at 72℃ for 5.5 h. After filtration, it was washed multiple times with anhydrous ethanol, and then dried at 122℃ for 9 h and calcined at 550℃ for 4 h to obtain the modified HZSM-5 support. The mass fraction of the NH4F aqueous solution was 8%, and the mass fraction of the 3-aminopropyltriethoxysilane / ethanol solution was 5%.
[0047] The doping modification process includes: Step ① mixing PdCl2, Mn(NO3)2•4H2O and La(NO3)3•6H2O with deionized water in a mass ratio of 2.5:3:3 and adjusting the pH to 2.5 to obtain a composite impregnation solution; Step ② adding the modified HZSM-5 support to the composite impregnation solution, controlling the solid-liquid ratio to 1:10 g / mL, and allowing it to stand at room temperature for 12 h to obtain the impregnated support; Step ③ drying the impregnated support at 112℃ for 12 h, followed by a high-temperature calcination treatment of raising the temperature to 500℃ at a controlled heating rate of 5℃ / min and calcining for 5 h, then cooling to room temperature; a reduction treatment of reducing the hydrogen flow rate at 50 mL / min and at 280℃ for 3 h, followed by cooling to obtain the Pd-Mn-La / modified HZSM-5 catalyst.
[0048] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, an unmodified HZSM-5 catalyst doped with Pd-Mn-La was used instead of the Pd-Mn-La / modified HZSM-5 catalyst.
[0049] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the doping modification part in Comparative Example 2 did not add Mn(NO3)2·4H2O and La(NO3)3·6H2O.
[0050] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that Mn(NO3)2·4H2O was not added to the doping modification part in Comparative Example 3.
[0051] Performance testing: 1. Purity test: According to SN / T 1098-2010, gas chromatograph and capillary column were used. Based on the area normalization method, the peak area of dihydroterpineol, the residual peak area of unreacted α-terpineol, and the peak areas of various by-products were statistically analyzed to calculate the purity of the main product and the total impurity content. 2. Yield test: Based on the stoichiometric ratio of the complete hydrogenation of α-terpineol to dihydroterpineol, and based on the mass of the α-terpineol raw material, the theoretical product mass is calculated. Then, the mass of the qualified dihydroterpineol product after distillation and purification is weighed. Based on the product purity, the mass of the pure product is converted, and the synthesis yield is calculated. 3. Continuous stability test: Under continuous working conditions, calculate the time when the purity drops below 92% and the yield drops below 88%; The performance test results are shown in Table 1 below.
[0052] Table 1 Performance Test Results
[0053] As shown in Table 1 above, in the preparation of dihydroterpineol, this application uses a Pd-Mn-La / modified HZSM-5 catalyst as the core catalyst. Firstly, fluoride ion etching is used to expand the pore size of the HZSM-5 molecular sieve and increase its specific surface area. Then, amino functionalization is used to introduce stable coordination sites on the support surface, anchoring Pd, Mn, and La metal active particles. This effectively inhibits the aggregation, shedding, and loss of active components, significantly extending the service life of the Pd-Mn-La / modified HZSM-5 catalyst. Secondly, Pd serves as the main active component, providing highly efficient hydrogenation active centers to achieve saturated hydrogenation of carbon-carbon double bonds. Mn acts as an electronic regulation aid, optimizing the electron cloud density of Pd and weakening the strong adsorption of substrates by Pd, thereby suppressing side reactions such as over-hydrogenation and skeletal isomerization, significantly improving catalytic selectivity. La is used to fill support defects to stabilize metal active sites, thereby improving the catalyst's thermal and structural stability.
[0054] Based on Comparative Example 1 and Example 1, the Pd-Mn-La / HZSM-5 catalyst suffers from the small pore size, low specific surface area, and lack of amino coordination sites on the surface of the HZSM-5 molecular sieve. Therefore, the metal active components are only loaded by physical adsorption, resulting in weak binding force and easy aggregation, detachment, and loss of Pd particles, leading to a significant decrease in the number of active sites.
[0055] Based on Comparative Example 2 and Example 1, the catalyst lacking the synergistic effect of Mn and La dual promoters is difficult to achieve precise and controllable hydrogenation due to the high electronic activity of the Pd active site, which leads to problems such as excessive hydrogenation of the substrate, molecular skeleton isomerization and by-product generation, and the catalytic selectivity is significantly reduced.
[0056] Based on Comparative Example 3 and Example 1, without the electronic regulation function of Mn metal, this catalyst is difficult to precisely adjust the adsorption intensity of Pd active sites, thus it cannot avoid isomerization and excessive hydrogenation side reactions, resulting in weak catalytic selectivity.
[0057] In summary, this application provides a method for preparing dihydroterpineol. This method expands the pore size of HZSM-5 molecular sieves through fluoride ion etching and provides stable loading sites through amino functionalization, effectively inhibiting Pd particle aggregation and loss. Furthermore, Mn-La dual doping forms a ternary synergistic active center with Pd, with Mn regulating the electron cloud density of Pd and La further stabilizing the active sites. This results in a Pd-Mn-La / modified HZSM-5 catalyst that is continuously usable and regenerable, significantly reducing losses and lowering industrial production costs. Therefore, in this method for preparing dihydroterpineol, the use of a Pd-Mn-La / modified HZSM-5 catalyst enables continuous hydrogenation in a fixed-bed reactor, allowing for efficient catalysis of α-terpineol hydrogenation at a stable temperature of 80-90℃ and a pressure of 0.8-1.0 MPa. Simultaneously, continuous feeding and discharging simplify the overall preparation process, reducing equipment investment and production risks, making it suitable for large-scale continuous production. Meanwhile, the Pd-Mn-La / modified HZSM-5 catalyst effectively inhibits the excessive hydrogenation and isomerization side reactions of α-terpineol during hydrogenation, thereby enhancing the adsorption effect of the modified HZSM-5 support and improving the contact efficiency between the feedstock and the active site. The co-catalyst further enhances the catalytic selectivity. At the same time, the distillation-based process efficiently separates the solvent, unreacted feedstock, and byproducts, thereby significantly improving the purity and yield of dihydroterpineol and effectively reducing distillation energy consumption and preparation costs.
[0058] The terms “first,” “second,” “third,” “fourth,” etc., used in this application (if applicable) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, or apparatus that includes a series of steps or units is not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, or apparatus.
[0059] It should be noted that the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.
[0060] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. A method for preparing dihydroterpineol, characterized in that, Includes the following steps: Step 1, Preparation: Prepare α-terpineol, solvent, catalyst, hydrogen, and co-catalyst for later use; Step 2, Pretreatment: Mix 90-100 parts of α-terpineol with 75-80 parts of solvent once and stir until homogeneous, then add 0.08-0.1 parts of co-catalyst and mix again until homogeneous to obtain the stock solution; Step 3, continuous hydrogenation: The raw liquid is pumped into a fixed-bed reactor filled with catalyst, while hydrogen is introduced and the temperature is controlled at 80-90℃ to carry out continuous feeding and discharging to obtain the reaction liquid; Step 4, distillation and purification: Distill the reaction solution to obtain dihydroterpineol; The catalyst is a Pd-Mn-La / modified HZSM-5 catalyst.
2. The method for preparing dihydroterpineol according to claim 1, characterized in that: In step 1, the solvent is anhydrous ethanol; the co-catalyst is nano zinc oxide with a particle size of 50-100 nm.
3. The method for preparing dihydroterpineol according to claim 1, characterized in that: In step 2, the first stirring is to control the stirring speed at 250-300 r / min and stir at room temperature for 20-25 min, and the second stirring is to continue stirring for 8-10 min.
4. The method for preparing dihydroterpineol according to claim 1, characterized in that: In step 3, the catalyst filling amount in the fixed-bed reactor is 18-20% of the reactor volume, and the catalyst bed height to diameter ratio is 4.5-5:1; the feed rate of the raw liquid is 1.5-1.6 mL / min; the molar ratio of hydrogen to α-terpineol is 1.2:1, the inlet pressure is 0.8-1.0 MPa, and the hydrogen flow rate is 40 mL / min.
5. The method for preparing dihydroterpineol according to any one of claims 1-4, characterized in that: The preparation method of the Pd-Mn-La / modified HZSM-5 catalyst includes an HZSM-5 molecular sieve modification part and a doping modification part; The HZSM-5 molecular sieve modification part is to treat HZSM-5 molecular sieve with fluorine ion etching and amino functionalization to obtain modified HZSM-5 catalyst; the doping modification part is to treat HZSM-5 catalyst with Pd main activity and Mn-La dual doping to obtain Pd-Mn-La / modified HZSM-5 catalyst.
6. The method for preparing dihydroterpineol according to claim 5, characterized in that: The HZSM-5 molecular sieve modification process includes: Step ① washing the HZSM-5 molecular sieve with deionized water until neutral, and then drying it at 105-110℃ for 12-13 hours to obtain clean HZSM-5 molecular sieve; Step ② immersing the clean HZSM-5 molecular sieve in an NH4F aqueous solution, stirring at 58-62℃ for 4-4.5 hours, filtering, washing with deionized water until fluoride-free, and then drying it at 105-110℃ for 7.5-8 hours to obtain etched HZSM-5; Step ③ immersing the etched HZSM-5 in a 3-aminopropyltriethoxysilane / ethanol solution, refluxing it at 68-72℃ for 5.5-6 hours, filtering, washing it multiple times with anhydrous ethanol, drying it at 118-122℃ for 9-10 hours, and calcining it at 530-550℃ for 4-4.2 hours to obtain the modified HZSM-5 support.
7. The method for preparing dihydroterpineol according to claim 6, characterized in that: The NH4F aqueous solution has a mass fraction of 8%, and the solid-liquid ratio after mixing with the NH4F aqueous solution is 1:15 g / mL; the 3-aminopropyltriethoxysilane / ethanol solution has a mass fraction of 5%, and the solid-liquid ratio after mixing with the 3-aminopropyltriethoxysilane / ethanol solution is 1:20 g / mL.
8. The method for preparing dihydroterpineol according to claim 5, characterized in that: The doping modification process includes step ① mixing PdCl2, Mn(NO3)2·4H2O and La(NO3)3·6H2O with deionized water in a mass ratio of 1.5-2.5:2-3:2-3, and adjusting the pH to 2-2.5 to obtain a composite impregnation solution; step ② adding the modified HZSM-5 support to the composite impregnation solution and allowing it to stand at room temperature for 12-14 hours to obtain the impregnated support; and step ③ drying the impregnated support at 108-112℃ for 12-14 hours, followed by high-temperature calcination and hydrogen reduction treatment to obtain the Pd-Mn-La / modified HZSM-5 catalyst.
9. The method for preparing dihydroterpineol according to claim 8, characterized in that: The solid-liquid ratio of the modified HZSM-5 support to the composite impregnation solution is 1:10 g / mL; the high-temperature calcination treatment involves raising the temperature to 500℃ at a controlled heating rate of 5℃ / min, calcining for 5 hours, and then cooling to room temperature; the hydrogen gas treatment reduction treatment involves controlling the hydrogen gas flow rate at 50 mL / min, reducing at 280℃ for 3 hours, and then cooling to obtain the Pd-Mn-La / modified HZSM-5 catalyst.
10. The method for preparing dihydroterpineol according to claim 1, characterized in that: In step 4, the distillation includes a first-stage distillation for distilling anhydrous ethanol, a second-stage distillation for distilling α-terpineol, and a third-stage distillation for distilling dihydroterpineol; the first-stage distillation has a reboil temperature of 80°C, a top temperature of 78°C, and a vacuum of 0.08 MPa; the second-stage distillation has a reboil temperature of 120°C, a top temperature of 105°C, and a vacuum of 0.09 MPa; and the third-stage distillation has a reboil temperature of 140°C, a top temperature of 125°C, and a vacuum of 0.095 MPa.