Production method of high-content p-menthane

Abstract

The invention discloses a production method of high-content p-menthane, a crude p-menthane product is produced by using a catalyst and a dipentene hydrogenation method, the crude p-menthane product is rectified by a rectification device to obtain a high-content p-menthane product, the raw material is dipentene, the catalyst is a high-performance alumina-loaded nickel-chromium catalyst, and the catalyst is a high-performance alumina-loaded nickel-chromium catalyst. Comprising the following raw materials in parts by weight: 10.2 to 15.4 parts of aluminum oxide, 0.5 to 3 parts of polyethylene glycol, 5.7 to 8.5 parts of nickel nitrate, 4.1 to 6.2 parts of chromic nitrate, 0.3 to 0.45 part of hexadecyl trimethyl ammonium bromide, 1 to 1.5 parts of tetrabutyl titanate, 0.2 to 0.3 part of sodium tripolyphosphate, 5 to 6.5 parts of absolute ethyl alcohol and 1 to 3 parts of glacial acetic acid. By applying the catalyst provided by the invention, the content of p-menthane can be remarkably increased.

Description

Technical Field

[0001] The invention belongs to the technical field of p-menthane preparation, and in particular relates to a method for producing high-content p-menthane. Background Art

[0002] p-Menthane, also known as 1-methyl-4-isopropylcyclohexane, is a unique and important organic compound classified as a saturated alicyclic hydrocarbon. Its chemical formula is simple and clear, C10H20, which gives it a series of unique physical and chemical properties. As a colorless and transparent liquid, p-Menthane emits a special and unique smell, which is often used as a significant mark to identify its identity in the field of chemistry.

[0003] In terms of physical properties, p-menthane has a lower density than water, which means that when it comes into contact with water, it will naturally float on the surface of the water. At the same time, it is not soluble in water, but can be easily dissolved in many organic solvents, such as ethanol, ether and benzene, which makes it have a wide range of potential in solvent applications. In addition, the boiling point of p-menthane is about 170-175℃, while the melting point is relatively low. These physical properties facilitate its processing and application in industrial production.

[0004] In terms of chemical properties, as a member of saturated hydrocarbons, p-menthane has a relatively stable chemical structure and is not prone to chemical reactions. However, this does not mean that it has no value in the field of chemistry. On the contrary, it is precisely because of its stable chemical properties that p-menthane has become an ideal solvent and synthetic raw material.

[0005] In the industrial field, p-menthane has a wide range of uses. It can be used as a solvent to dissolve some organic compounds with high solubility requirements, especially in the synthesis of some fine chemicals. These fine chemicals often have strict requirements on the selection of solvents, and p-menthane meets these requirements with its unique solubility properties. In addition, p-menthane can also be used as a raw material to synthesize other organic compounds with specific functions. In the field of synthesis of fragrances and pharmaceutical intermediates, p-menthane plays an irreplaceable role. Because there are groups in its structure that can be further chemically modified, new functional groups can be introduced through clever chemical reactions, thereby synthesizing compounds with specific aromas, medicinal effects or other functions.

[0006] In the process of preparing p-menthane, the commonly used method in industry is the dipentene hydrogenation method. This method prepares p-menthane by reacting dipentene with a catalyst under hydrogenation conditions. However, the selection of catalyst is crucial to the efficiency of the reaction and the quality of the product.

[0007] Although traditional nickel-based catalysts have good hydrogenation activity and can efficiently convert dipentene into p-menthane, and under appropriate reaction conditions, the conversion rate can reach a high level, the selectivity is good, and the cost is relatively low, their activity and selectivity still need to be improved, and they are prone to poisoning, resulting in catalyst deactivation, which affects the yield and content of p-menthane.

[0008] Precious metal catalysts, such as Pt, Pd, and Ru, have unique electronic structures and can achieve hydrogenation of dipentene under relatively mild reaction conditions. The use of these catalysts greatly improves the reaction rate, has excellent selectivity, and is highly stable. However, the scarcity and high price of precious metal resources make the cost of the catalyst extremely high, thus limiting the possibility of its large-scale industrial application.

[0009] In order to cope with these difficulties, the strategy of using a supported catalyst can promote the full fusion of industrial dipentene and hydrogen under normal pressure, and react with the catalyst through gas-solid contact reaction, successfully completing the hydrogenation process of industrial dipentene at room temperature and pressure. This method has many advantages such as mild reaction conditions, strong system stability and relatively low cost. However, in the preparation process of supported catalysts, there is a significant problem: the active components of the catalyst are difficult to be efficiently loaded onto the carrier material, which directly leads to a limited number of reaction sites of the catalyst and poor activity performance. Therefore, when such supported catalysts are used to prepare p-menthane, the yield of p-menthane is often low and the content is not ideal. Summary of the invention

[0010] The object of the present invention is to provide a method for producing high-content p-menthane to solve the technical problems in the above-mentioned prior art.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions:

[0012] A method for producing high-content p-monane, which uses a catalyst to produce a crude p-monane product by a dipentene hydrogenation method, and the crude p-monane product is rectified by a distillation device to obtain a high-content p-monane product, wherein the raw material is dipentene, and is characterized in that the catalyst is a high-performance alumina-supported nickel-chromium catalyst, which comprises the following raw materials in parts by weight: 10.2-15.4 parts of alumina, 0.5-3 parts of polyethylene glycol, 5.7-8.5 parts of nickel nitrate, 4.1-6.2 parts of chromium nitrate, 0.3-0.45 parts of hexadecyltrimethylammonium bromide, 1-1.5 parts of tetrabutyl titanate, 0.2-0.3 parts of sodium tripolyphosphate, 5-6.5 parts of anhydrous ethanol, and 1-3 parts of glacial acetic acid.

[0013] Preferably, the catalyst is a high-performance alumina-supported nickel-chromium catalyst, which is made of the following raw materials in parts by weight: 13.5 parts of alumina, 0.5 parts of polyethylene glycol, 6.8 parts of nickel nitrate, 6.2 parts of chromium nitrate, 0.42 parts of hexadecyltrimethylammonium bromide, 1.5 parts of tetrabutyl titanate, 0.28 parts of sodium tripolyphosphate, 5.6 parts of anhydrous ethanol, and 3 parts of glacial acetic acid.

[0014] Furthermore, the preparation method of the high-performance alumina-supported nickel-chromium catalyst comprises the following steps:

[0015] S1. Preparation of alumina carrier: preparing alumina carrier by mixing alumina powder and polyethylene glycol for later use;

[0016] S2. Preparation of nickel-chromium solution: nickel nitrate and chromium nitrate are dissolved in water to prepare a mixed solution with a concentration of 0.5-1.5 mol / L for later use;

[0017] S3, preparation of auxiliary agent solution: prepare cetyltrimethylammonium bromide, tetrabutyl titanate and sodium tripolyphosphate into solutions for standby use;

[0018] S4, coprecipitation-deposition: in a reaction vessel with a stirring device, add pretreated alumina and water to form a suspension, under stirring conditions, simultaneously drop the nickel-chromium mixed solution and the hexadecyltrimethylammonium bromide solution into the reaction vessel, keep the temperature at 40-60°C during the dropwise addition, and continue stirring for 1-2 hours after the dropwise addition is completed; drop the tetrabutyl titanate solution into the system, and control the pH value of the reaction system to 2-3, and continue stirring for 2-3 hours after the dropwise addition is completed; drop the sodium tripolyphosphate solution into the system, and continue stirring for 1-2 hours after the dropwise addition is completed, and control the pH value of the reaction system to 7-9 during the whole process;

[0019] S5, reaction and filtration: react in the reaction system, filter after the reaction, and wash the precipitate;

[0020] S6. Drying and calcining: Dry the washed precipitate at 100-120° C. for 12-24 hours, cool it to room temperature, and then heat it up and calcine it for 4-8 hours to obtain a high-performance alumina-supported nickel-chromium catalyst.

[0021] Furthermore, in S1, the specific preparation method of the alumina carrier is: mixing alumina powder with polyethylene glycol, and calcining at 500-700° C. for 3-5 hours to obtain the alumina carrier.

[0022] Furthermore, in S3, the method for preparing the hexadecyltrimethylammonium bromide solution is as follows: dissolving hexadecyltrimethylammonium bromide in deionized water to prepare a solution with a concentration of 0.1-0.3 mol / L; the method for preparing the tetrabutyl titanate solution is as follows: slowly adding anhydrous ethanol and glacial acetic acid to tetrabutyl titanate, stirring evenly, to obtain a tetrabutyl titanate solution; the method for preparing the sodium tripolyphosphate solution is as follows: dissolving sodium tripolyphosphate in deionized water to prepare a solution with a concentration of 0.2-0.5 mol / L.

[0023] Furthermore, in S3, the tetrabutyl titanate solution is prepared by slowly dropping anhydrous ethanol and glacial acetic acid into tetrabutyl titanate and stirring the mixture to obtain the tetrabutyl titanate solution.

[0024] Furthermore, in S3, the sodium tripolyphosphate solution is prepared by dissolving sodium tripolyphosphate in deionized water to prepare a solution with a concentration of 0.2-0.5 mol / L.

[0025] Furthermore, the reaction conditions in S5 are: reacting at 60-80° C. for 6-12 hours.

[0026] Furthermore, in S6, the temperature is raised to 400-600°C.

[0027] Furthermore, the heating rate is 2-5°C / min.

[0028] The raw material components of the high-performance alumina-supported nickel-chromium catalyst of the present invention have the following functions:

[0029] Alumina: As a carrier of the catalyst, it provides support for the active components. Its high specific surface area enables the active components to be highly dispersed on its surface, increasing the number of active sites. For example, the active components can be evenly distributed on the surface and pores of alumina in the form of atoms or small particles, thereby effectively participating in the catalytic reaction; alumina itself has good thermal stability and mechanical stability. Under high-temperature reaction conditions, it can maintain structural integrity and prevent sintering and collapse of the catalyst. This enables the catalyst to maintain its activity and performance during long-term use, ensuring the continuous and stable progress of the reaction. The functional groups on the surface of alumina can form chemical bonds with the active components. This chemical bonding can not only firmly fix the active components and reduce the loss of active components, but also adjust the electronic state of the active components, thereby affecting their catalytic performance.

[0030] Polyethylene glycol: By adding polyethylene glycol during the preparation of the alumina carrier, the polyethylene glycol decomposes or volatilizes during high temperature treatment, leaving additional pores in the alumina. These pores can increase the pore size and pore volume of the catalyst, provide more diffusion channels for reactant molecules, and make it easier for reactants to approach active sites. It provides a wider dispersion space for active components, which is conducive to a more uniform distribution of active components on the carrier and avoids the agglomeration of active components, thereby improving the utilization rate of active components and the activity of the catalyst.

[0031] Nickel nitrate and chromium nitrate: Precursors of the active ingredients nickel and chromium are converted into species with catalytic activity and become the active center of the catalyst. Chromium can change the dispersion state of nickel on the surface of alumina, and make the active components evenly distributed on the surface of the carrier by forming alloys or compounds. At the same time, chromium can adjust the electronic structure of the catalyst and affect the electron cloud density of the active components, thereby changing the adsorption capacity and reaction activity of the catalyst for the reactant molecules and increasing the content and selectivity of menthane.

[0032] Hexadecyltrimethylammonium bromide: Hexadecyltrimethylammonium bromide can form micelle structures in solution. In the process of catalyst preparation, these micelles can serve as soft templates to guide metal ions such as nickel and chromium and alumina precursors to be arranged and aggregated around them, which is conducive to the formation of a regular pore structure, increasing the specific surface area of ​​the catalyst and providing more active sites for the reaction; there is an interaction between the hydrophilic group of hexadecyltrimethylammonium bromide and the alumina precursor, which can effectively reduce the surface tension and prevent the agglomeration of active components and carriers. This makes the nickel-chromium active components more evenly dispersed on the alumina carrier, improves the utilization rate of the active components and the activity of the catalyst, and is conducive to the efficient preparation of menthane.

[0033] Tetrabutyl titanate: Enhances the stability of the carrier. Active titanium species are released during the hydrolysis and polycondensation process. These active titanium species can interact with the alumina carrier to form Ti-O-Al bonds, thereby enhancing the stability and mechanical strength of the carrier. This helps the catalyst maintain structural integrity during the reaction and resist structural damage that may occur under reaction conditions such as high temperature and high pressure. The presence of titanium may also change the surface properties of the carrier and adjust its acidity and alkalinity, making it more conducive to the loading of nickel-chromium active components and the adsorption and activation of reaction molecules. At the same time, the titanium hydroxy compounds produced by the hydrolysis of tetrabutyl titanate can chemically bond or coordinate with nickel and chromium ions, prevent the agglomeration of active components, promote their dispersion on the surface of the alumina carrier, and improve the activity and selectivity of the catalyst.

[0034] Sodium tripolyphosphate: It has strong chelating ability and can form stable chelates with nickel and chromium ions. In the process of catalyst preparation, this chelation can effectively control the precipitation rate and particle size of the active components, prevent them from agglomerating and growing quickly, and make the active components dispersed evenly on the alumina carrier with a smaller particle size, increase the specific surface area of ​​the active components and the exposure of the active sites, thereby improving the activity of the catalyst; the chelate formed with the active components can maintain good stability during the calcination and reaction of the catalyst, reduce the loss and sintering of the active components, and improve the service life and stability of the catalyst. At the same time, it can also interact with the hydroxyl groups on the surface of the alumina carrier, further enhancing the binding force between the active components and the carrier, so that the catalyst can maintain good structural integrity under reaction conditions.

[0035] Anhydrous ethanol: solvent.

[0036] Glacial acetic acid: In the hydrolysis reaction of tetrabutyl titanate, glacial acetic acid can be used as an inhibitor. It can adjust the hydrolysis rate of tetrabutyl titanate and prevent the formation of gel due to excessive hydrolysis, so that tetrabutyl titanate can be more evenly distributed in the system and interact better with other components. This control of hydrolysis helps to optimize the structure and performance of the catalyst.

[0037] The principle of the high-performance alumina-supported nickel-chromium catalyst preparation process of the present invention is:

[0038] S1. Preparation of alumina carrier: Polyethylene glycol will decompose at high temperature. When calcined with alumina powder, as the temperature rises, the polyethylene glycol molecular chain breaks, generating small volatile molecules such as carbon dioxide and water that leave the system. This process will leave gaps in the alumina, thereby changing the pore structure of alumina and obtaining an alumina carrier with a larger pore size and pore volume. The expanded alumina carrier can provide more space for the subsequent loading of active components, which is beneficial to the dispersion of active components. It also provides a better diffusion channel for the reactant molecules in the reaction process and enhances the mass transfer efficiency.

[0039] S2. Preparation of nickel-chromium solution: Nickel nitrate and chromium nitrate are strong electrolytes that can be ionized in deionized water to form nickel ions and chromium ions. By controlling the amount of solute and the volume of solvent, a mixed solution of the desired concentration can be accurately prepared. A solution containing nickel and chromium active component precursors is obtained, which facilitates the subsequent uniform introduction of nickel and chromium onto the alumina support. Accurate concentration control can ensure that the active component is loaded appropriately on the support, and that there is an appropriate ion concentration in the coprecipitation-deposition step, which is conducive to the effective deposition of the active component.

[0040] S3. Preparation of auxiliary solution

[0041] Hexadecyltrimethylammonium bromide can be uniformly dispersed in deionized water through intermolecular interactions to form a stable solution. A hexadecyltrimethylammonium bromide solution with a suitable concentration is obtained to play its role of template guidance and agglomeration prevention in the subsequent coprecipitation-deposition process, guide the directional arrangement of active components and carrier precursors, and improve the uniformity and activity of the catalyst.

[0042] Tetrabutyl titanate is miscible with anhydrous ethanol, and slow dripping of anhydrous ethanol can fully dissolve tetrabutyl titanate. Glacial acetic acid can interact with tetrabutyl titanate to adjust its hydrolysis rate. Since tetrabutyl titanate is easily hydrolyzed in water, the addition of glacial acetic acid can inhibit its excessive hydrolysis, allowing it to be more evenly distributed in the system. A stable tetrabutyl titanate solution is obtained, which is used to play its cross-linking role in the catalyst system later. The active species of titanium are released through hydrolysis and polycondensation reactions, forming chemical bonds with the alumina carrier, enhancing the stability of the carrier, while adjusting the surface properties of the carrier and promoting the dispersion of the active components.

[0043] Preparation of sodium tripolyphosphate solution Sodium tripolyphosphate is a water-soluble salt that can ionize corresponding ions in deionized water to form a stable solution. The sodium tripolyphosphate solution with a suitable concentration is obtained to exert its chelating effect in the subsequent steps, control the precipitation rate and particle size of the active components, enhance the binding force between the active components and the carrier, and improve the stability of the catalyst.

[0044] S4. Coprecipitation-deposition: When the nickel-chromium mixed solution and the cetyl trimethyl ammonium bromide solution are simultaneously added dropwise to a reaction vessel containing an alumina suspension, at the appropriate temperature, the metal ions may combine with the hydroxide ions in the solution to begin to form hydroxide precipitation. The micellar structure of cetyl trimethyl ammonium bromide can guide the precipitation process of the metal ions, causing them to deposit evenly on and around the alumina support surface.

[0045] When the tetrabutyl titanate solution is added dropwise, the pH value is controlled to be 2-3, which is conducive to the hydrolysis reaction of the tetrabutyl titanate, so that it releases active species of titanium, which can interact with the alumina support and the precipitated active components.

[0046] Finally, sodium tripolyphosphate solution is added dropwise. Under the condition of pH 7-9, sodium tripolyphosphate can form chelates with metal ions to further stabilize the precipitation structure of the active components and prevent them from agglomerating. By gradually adding the solution and controlling the reaction conditions, the active components (nickel and chromium) are uniformly deposited on the alumina carrier. At the same time, the role of the additive is utilized to achieve good dispersion of the active components, effective combination with the carrier, and stability of the precipitation structure of the active components, thus constructing a catalyst precursor with good performance.

[0047] S5, Reaction and Filtration: The reaction at 60-80℃ is to make the precipitation reaction more complete and to make the structure of the precipitate more stable and mature. In this process, the internal structure of the precipitate may be rearranged and optimized, and the binding force between particles is enhanced. The quality of the catalyst precursor is improved, the precipitate structure is improved through aging, and impurities are removed by filtration, providing pure raw materials for the subsequent drying and calcination steps, which helps to improve the performance of the catalyst.

[0048] S6, Drying and calcination: Drying at 100-120°C to remove moisture from the precipitate and form a solid particle structure of the catalyst precursor. As the temperature is increased to 400-600°C at a heating rate of 2-5°C / min for calcination, on the one hand, impurities can be further removed, and on the other hand, the active components can undergo phase changes, while strengthening the chemical bonding between the active components and the carrier, thereby improving the stability and activity of the catalyst. A catalyst with good stability and activity is obtained. The drying process ensures that the physical form of the catalyst is appropriate, and the calcination process optimizes the chemical structure of the catalyst. After these treatments, the catalyst can play an efficient catalytic role in reactions such as the preparation of menthane.

[0049] Compared with the prior art, the present invention exhibits significant technical advantages, which are not only reflected in the composition and preparation process of the catalyst, but also bring good improvements in practical applications, which are specifically manifested in the following aspects:

[0050] (1) In terms of the composition of the catalyst, the present invention cleverly uses alumina as the basic carrier, and this choice itself is based on careful consideration of the stability and durability of the catalyst. Alumina is an ideal supporting material due to its high specific surface area, good thermal stability and chemical inertness. More innovatively, the present invention loads nickel-chromium active ingredients on this basis, and the synergistic effect of these two metals greatly enhances the catalytic activity of the catalyst. In addition, the present invention also creatively introduces three substances, cetyltrimethylammonium bromide, tetrabutyl titanate and sodium tripolyphosphate, each of which plays an indispensable role in the catalyst system: cetyltrimethylammonium bromide helps the active ingredients to be evenly distributed on the surface of alumina; the addition of tetrabutyl titanate further improves the structural stability and catalytic efficiency of the catalyst; and sodium tripolyphosphate effectively prevents the agglomeration of the active ingredients through its unique complexing ability, ensuring the maximization of the catalytic activity. This series of careful design and scientific proportioning enables the prepared alumina-loaded nickel-chromium catalyst to show amazing performance in the reaction of dipentene hydrogenation to prepare p-menthane. Specifically, the conversion rates of the main components of dipentene, such as α-terpinene, p-cymene, limonene, γ-terpinene, and isoprene, have reached extremely high levels, namely 98.7%, 98.5%, 98.7%, 98.4%, and 98.6%, respectively, while the content of p-menthane is as high as 98.7%. This achievement not only greatly improves the yield of p-menthane, but also significantly optimizes the content of the product, providing great convenience for subsequent separation and purification work and reducing production costs.

[0051] (2) The present invention has also made a groundbreaking contribution in optimizing the performance of the catalyst. By cleverly adding polyethylene glycol, the present invention successfully improved the pore structure of the alumina carrier, making the pores inside the catalyst more spacious and evenly distributed. This change not only increases the number of reaction sites, but also optimizes the contact efficiency between the reactants and the active ingredients, thereby greatly improving the activity of the catalyst. In addition, the introduction of polyethylene glycol also effectively alleviates the clogging problem of the catalyst during a long reaction process and extends the service life of the catalyst. Therefore, in practical applications, the catalyst of the present invention exhibits higher catalytic efficiency and longer service life, which is of great significance for improving production efficiency, reducing energy consumption and reducing waste emissions.

[0052] In summary, the catalyst of the present invention has not only achieved significant progress in terms of technology, but also demonstrated huge economic and environmental benefits in practical applications, providing strong support for technological upgrading and sustainable development of related industries.

[0053] Instruction Manual

[0054] Figure 1 This is a process flow chart for preparing the high-performance alumina-supported nickel-chromium catalyst of the present invention;

[0055] Figure 2 This is a diagram of the p-menthane product produced by using the high-performance alumina-supported nickel-chromium catalyst of the present invention;

[0056] Figure 3 It is a structural schematic diagram of the distillation equipment of the present invention;

[0057] Figure 4 It is a structural schematic diagram of the defoaming device in the present invention;

[0058] Figure 5 It is a structural schematic diagram of the connecting mechanism in the present invention;

[0059] Figure 6 It is a structural schematic diagram of the lifting mechanism in the present invention;

[0060] Figure 7 It is a structural schematic diagram of the rotating mechanism in the present invention;

[0061] Figure 8 It is a structural schematic diagram of the cleaning mechanism in the present invention.

[0062] Figure 3-8 In: 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;

[0063] 310, connecting mechanism; 320, lifting mechanism; 330, rotating mechanism; 340, cleaning mechanism; 350, defoaming disc;

[0064] 311, inlet pipe; 312, support seat; 313, outlet pipe;

[0065] 321. telescopic rod; 322. bracket; 323. connecting rod;

[0066] 331. rotating rod; 332. gear; 333. gear seat;

[0067] 341. Support plate; 342. Rotating shaft; 343. Cleaning brush. DETAILED DESCRIPTION

[0068] 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.

[0069] In an embodiment of the present invention, the high-performance alumina-supported nickel-chromium catalyst is made of the following raw materials in parts by weight: 10.2-15.4 parts of alumina, 0.5-3 parts of polyethylene glycol, 5.7-8.5 parts of nickel nitrate, 4.1-6.2 parts of chromium nitrate, 0.3-0.45 parts of hexadecyltrimethylammonium bromide, 1-1.5 parts of tetrabutyl titanate, 0.2-0.3 parts of sodium tripolyphosphate, 5-6.5 parts of anhydrous ethanol, and 1-3 parts of glacial acetic acid.

[0070] like Figure 1 The method for preparing the high-performance alumina-supported nickel-chromium catalyst comprises the following steps:

[0071] S1. Preparation of alumina carrier: mixing alumina powder with polyethylene glycol, calcining at 500-700° C. for 3-5 h to obtain an alumina carrier for standby use;

[0072] S2. Preparation of nickel-chromium solution: nickel nitrate and chromium nitrate are dissolved in an appropriate amount of deionized water to prepare a mixed solution with a concentration of 0.5-1.5 mol / L for later use;

[0073] S3, preparation of auxiliary agent solution: dissolve hexadecyltrimethylammonium bromide in deionized water to prepare a solution with a concentration of 0.1-0.3 mol / L for standby use; slowly add anhydrous ethanol and glacial acetic acid to tetrabutyl titanate, stir evenly, and obtain a tetrabutyl titanate solution for standby use; dissolve sodium tripolyphosphate in deionized water to prepare a solution with a concentration of 0.2-0.5 mol / L for standby use;

[0074] S4, coprecipitation-deposition: in a reaction vessel with a stirring device, add the pretreated alumina and an appropriate amount of deionized water to form a suspension, under stirring conditions, slowly drop the nickel-chromium mixed solution and the hexadecyltrimethylammonium bromide solution into the reaction vessel at the same time, keep the temperature at 40-60°C during the dropping process, and continue to stir for 1-2 hours after the dropping is completed; slowly drop the tetrabutyl titanate solution into the system, and control the pH value of the reaction system to 2-3, and continue to stir for 2-3 hours after the dropping is completed; slowly drop the sodium tripolyphosphate solution into the system, and continue to stir for 1-2 hours after the dropping is completed. During the whole process, the pH value of the reaction system is controlled to be 7-9;

[0075] S5, reaction and filtration: react the reaction system at 60-80°C for 6-12 hours, filter after the reaction, and wash the precipitate;

[0076] S6. Drying and calcining: Dry the washed precipitate at 100-120°C for 12-24 hours, cool it to room temperature, heat it to 400-600°C at a heating rate of 2-5°C / min, and calcine it for 4-8 hours to obtain a high-performance alumina-supported nickel-chromium catalyst.

[0077] A method for producing high-content p-monane, using a catalyst to produce a crude p-monane product by a dipentene hydrogenation method, and the crude p-monane product is distilled by a distillation device to obtain a high-content p-monane product, wherein the raw material is dipentene and the catalyst is a high-performance alumina-supported nickel-chromium catalyst.

[0078] The following is a more specific example.

[0079] Example 1

[0080] A high-performance alumina-supported nickel-chromium catalyst is prepared from the following raw materials in parts by weight: 13.5 parts of alumina, 0.5 parts of polyethylene glycol, 6.8 parts of nickel nitrate, 6.2 parts of chromium nitrate, 0.42 parts of hexadecyltrimethylammonium bromide, 1.5 parts of tetrabutyl titanate, 0.28 parts of sodium tripolyphosphate, 5.6 parts of anhydrous ethanol, and 3 parts of glacial acetic acid.

[0081] The method for preparing the high-performance alumina-supported nickel-chromium catalyst comprises the following steps:

[0082] S1. Preparation of alumina carrier: mixing alumina powder with polyethylene glycol, and calcining at 600° C. for 3 h to obtain an alumina carrier for standby use;

[0083] S2. Preparation of nickel-chromium solution: nickel nitrate and chromium nitrate are dissolved in an appropriate amount of deionized water to prepare a mixed solution with a concentration of 1 mol / L for later use;

[0084] S3, preparation of auxiliary agent solution: dissolve hexadecyltrimethylammonium bromide in deionized water to prepare a solution with a concentration of 0.3 mol / L for standby use; slowly add anhydrous ethanol and glacial acetic acid to tetrabutyl titanate, stir evenly, and obtain a tetrabutyl titanate solution for standby use; dissolve sodium tripolyphosphate in deionized water to prepare a solution with a concentration of 0.5 mol / L for standby use;

[0085] S4, coprecipitation-deposition: in a reaction vessel with a stirring device, add the pretreated alumina and an appropriate amount of deionized water to form a suspension, under stirring conditions, slowly drop the nickel-chromium mixed solution and the hexadecyltrimethylammonium bromide solution into the reaction vessel at the same time, keep the temperature at 50°C during the dropping process, and continue to stir for 1.3 hours after the dropping is completed; slowly drop the tetrabutyl titanate solution into the system, and control the pH value of the reaction system to 3, and continue to stir for 2.3 hours after the dropping is completed; slowly drop the sodium tripolyphosphate solution into the system, and continue to stir for 1 hour after the dropping is completed. During the whole process, the pH value of the reaction system is controlled to be 9;

[0086] S5, reaction and filtration: react the reaction system at 80° C. for 10 hours, filter after the reaction is completed, and wash the precipitate;

[0087] S6. Drying and calcination: The washed precipitate was dried at 110° C. for 15 hours, cooled to room temperature, heated to 600° C. at a heating rate of 5° C. / min, and calcined for 7 hours to obtain a high-performance alumina-supported nickel-chromium catalyst.

[0088] A method for producing high-content p-monane, wherein a catalyst is used to produce a crude p-monane product by a dipentene hydrogenation method, and the crude p-monane product is distilled by a distillation device to obtain a high-content p-monane product. Figure 2 , wherein the raw material is dipentene and the catalyst is a high-performance alumina-supported nickel-chromium catalyst.

[0089] See also Figure 3-8The 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] The main heater 13 comprises a heating plate, and the heating plate is embedded in the tower kettle 1 through a head.

[0101] 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.

[0102] Technical principle of the distillation equipment of the present invention:

[0103] 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 paramenane product is sucked into the tower bottom 1 from the metering tank 2 under the action of the negative pressure. After the tower bottom 1 is heated by the main heater 13, the crude paramenane product is evaporated. The distillation of the crude paramenane product is carried out in a high-temperature vacuum state. The gas velocity fluctuates greatly. Bubbles are easily formed on the surface of the crude paramenane 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 their aperture from passing through them and burst the bubbles, thereby achieving the purpose of defoaming and avoiding the crude paramenane product from impacting the tower top, affecting the product quality, and causing a loss of tons of crude paramenane product. 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 paramenane 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 paramenane product. After the distillation is completed, the residual liquid is discharged into the kettle residual tank 12 by utilizing the pressure difference between the kettle residual 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 paramenane 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 paramenane, which can greatly save expenses and energy consumption.

[0104] 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 menthane 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 menthane product. These bubbles continue to accumulate on the liquid surface of the crude menthane 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.

[0105] 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 aperture, 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 defoamed crude vapor of paramenane 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 bottom of the tower, 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.

[0106] 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.

[0107] 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.

[0108] Example 2

[0109] A high-performance alumina-supported nickel-chromium catalyst is prepared from the following raw materials in parts by weight: 10.2 parts of alumina, 2 parts of polyethylene glycol, 8.5 parts of nickel nitrate, 5.4 parts of chromium nitrate, 0.45 parts of hexadecyltrimethylammonium bromide, 1.2 parts of tetrabutyl titanate, 0.22 parts of sodium tripolyphosphate, 6.3 parts of anhydrous ethanol, and 1.5 parts of glacial acetic acid.

[0110] The method for preparing the high-performance alumina-supported nickel-chromium catalyst comprises the following steps:

[0111] S1. Preparation of alumina carrier: mixing alumina powder with polyethylene glycol, and calcining at 500° C. for 5 h to obtain an alumina carrier for standby use;

[0112] S2. Preparation of nickel-chromium solution: nickel nitrate and chromium nitrate are dissolved in an appropriate amount of deionized water to prepare a mixed solution with a concentration of 1.5 mol / L for later use;

[0113] S3, preparation of auxiliary agent solution: dissolve hexadecyltrimethylammonium bromide in deionized water to prepare a solution with a concentration of 0.1 mol / L for standby use; slowly add anhydrous ethanol and glacial acetic acid to tetrabutyl titanate, stir evenly, and obtain a tetrabutyl titanate solution for standby use; dissolve sodium tripolyphosphate in deionized water to prepare a solution with a concentration of 0.2 mol / L for standby use;

[0114] S4, coprecipitation-deposition: in a reaction vessel with a stirring device, add the pretreated alumina and an appropriate amount of deionized water to form a suspension, under stirring conditions, slowly drop the nickel-chromium mixed solution and the hexadecyltrimethylammonium bromide solution into the reaction vessel at the same time, keep the temperature at 55°C during the dropping process, and continue to stir for 1 hour after the dropping is completed; slowly drop the tetrabutyl titanate solution into the system, and control the pH value of the reaction system to 3, and continue to stir for 2.1 hours after the dropping is completed; slowly drop the sodium tripolyphosphate solution into the system, and continue to stir for 1.5 hours after the dropping is completed. During the whole process, the pH value of the reaction system is controlled to be 8;

[0115] S5, reaction and filtration: react the reaction system at 65° C. for 8 hours, filter after the reaction is completed, and wash the precipitate;

[0116] S6. Drying and calcination: The washed precipitate was dried at 120° C. for 18 hours, cooled to room temperature, heated to 450° C. at a heating rate of 4° C. / min, and calcined for 8 hours to obtain a high-performance alumina-supported nickel-chromium catalyst.

[0117] A method for producing high-content p-monane, wherein a catalyst is used to produce a crude p-monane product by a dipentene hydrogenation method, and the crude p-monane product is distilled by the same distillation equipment as in Example 1 to obtain a high-content p-monane product, wherein the raw material is dipentene and the catalyst is a high-performance alumina-supported nickel-chromium catalyst.

[0118] Example 3

[0119] A high-performance alumina-supported nickel-chromium catalyst is prepared from the following raw materials in parts by weight: 12.8 parts of alumina, 1 part of polyethylene glycol, 7.3 parts of nickel nitrate, 4.6 parts of chromium nitrate, 0.34 parts of hexadecyltrimethylammonium bromide, 1 part of tetrabutyl titanate, 0.25 parts of sodium tripolyphosphate, 6.5 parts of anhydrous ethanol, and 3 parts of glacial acetic acid.

[0120] The method for preparing the high-performance alumina-supported nickel-chromium catalyst comprises the following steps:

[0121] S1. Preparation of alumina carrier: Alumina powder was mixed with polyethylene glycol, and calcined at 550° C. for 4.5 h to obtain an alumina carrier for standby use;

[0122] S2. Preparation of nickel-chromium solution: nickel nitrate and chromium nitrate are dissolved in an appropriate amount of deionized water to prepare a mixed solution with a concentration of 0.5 mol / L for later use;

[0123] S3, preparation of auxiliary agent solution: dissolve hexadecyltrimethylammonium bromide in deionized water to prepare a solution with a concentration of 0.1 mol / L for standby use; slowly add anhydrous ethanol and glacial acetic acid to tetrabutyl titanate, stir evenly, and obtain a tetrabutyl titanate solution for standby use; dissolve sodium tripolyphosphate in deionized water to prepare a solution with a concentration of 0.5 mol / L for standby use;

[0124] S4, coprecipitation-deposition: in a reaction vessel with a stirring device, add the pretreated alumina and an appropriate amount of deionized water to form a suspension, under stirring conditions, slowly drop the nickel-chromium mixed solution and the hexadecyltrimethylammonium bromide solution into the reaction vessel at the same time, keep the temperature at 60°C during the dropping process, and continue to stir for 2 hours after the dropping is completed; slowly drop the tetrabutyl titanate solution into the system, and control the pH value of the reaction system to 2, and continue to stir for 3 hours after the dropping is completed; slowly drop the sodium tripolyphosphate solution into the system, and continue to stir for 1.2 hours after the dropping is completed. During the whole process, the pH value of the reaction system is controlled to be 8;

[0125] S5, reaction and filtration: react the reaction system at 60°C for 12 hours, filter after the reaction is completed, and wash the precipitate;

[0126] S6. Drying and calcination: The washed precipitate was dried at 110° C. for 12 hours, cooled to room temperature, heated to 400° C. at a heating rate of 4° C. / min, and calcined for 6 hours to obtain a high-performance alumina-supported nickel-chromium catalyst.

[0127] A method for producing high-content p-monane, wherein a catalyst is used to produce a crude p-monane product by a dipentene hydrogenation method, and the crude p-monane product is distilled by the same distillation equipment as in Example 1 to obtain a high-content p-monane product, wherein the raw material is dipentene and the catalyst is a high-performance alumina-supported nickel-chromium catalyst.

[0128] Example 4

[0129] A high-performance alumina-supported nickel-chromium catalyst is prepared from the following raw materials in parts by weight: 45.4 parts of alumina, 2.6 parts of polyethylene glycol, 5.7 parts of nickel nitrate, 4.1 parts of chromium nitrate, 0.3 parts of hexadecyltrimethylammonium bromide, 1.3 parts of tetrabutyl titanate, 0.3 parts of sodium tripolyphosphate, 5 parts of anhydrous ethanol, and 2.8 parts of glacial acetic acid.

[0130] The method for preparing the high-performance alumina-supported nickel-chromium catalyst comprises the following steps:

[0131] S1. Preparation of alumina carrier: Alumina powder was mixed with polyethylene glycol, and calcined at 700° C. for 3.5 h to obtain an alumina carrier for standby use;

[0132] S2. Preparation of nickel-chromium solution: nickel nitrate and chromium nitrate are dissolved in an appropriate amount of deionized water to prepare a mixed solution with a concentration of 0.5 mol / L for later use;

[0133] S3, preparation of auxiliary agent solution: dissolve hexadecyltrimethylammonium bromide in deionized water to prepare a solution with a concentration of 0.2 mol / L for standby use; slowly add anhydrous ethanol and glacial acetic acid to tetrabutyl titanate, stir evenly, and obtain a tetrabutyl titanate solution for standby use; dissolve sodium tripolyphosphate in deionized water to prepare a solution with a concentration of 0.3 mol / L for standby use;

[0134] S4, coprecipitation-deposition: in a reaction vessel with a stirring device, add the pretreated alumina and an appropriate amount of deionized water to form a suspension, under stirring conditions, slowly drop the nickel-chromium mixed solution and the hexadecyltrimethylammonium bromide solution into the reaction vessel at the same time, keep the temperature at 40°C during the dropping process, and continue to stir for 1.7 hours after the dropping is completed; slowly drop the tetrabutyl titanate solution into the system, and control the pH value of the reaction system to 3, and continue to stir for 2 hours after the dropping is completed; slowly drop the sodium tripolyphosphate solution into the system, and continue to stir for 2 hours after the dropping is completed. During the whole process, the pH value of the reaction system is controlled to be 9;

[0135] S5, reaction and filtration: react the reaction system at 75°C for 6 hours, filter after the reaction is completed, and wash the precipitate;

[0136] S6. Drying and calcination: The washed precipitate was dried at 100° C. for 24 hours, cooled to room temperature, heated to 500° C. at a heating rate of 2° C. / min, and calcined for 4 hours to obtain a high-performance alumina-supported nickel-chromium catalyst.

[0137] A method for producing high-content p-monane, wherein a catalyst is used to produce a crude p-monane product by a dipentene hydrogenation method, and the crude p-monane product is distilled by the same distillation equipment as in Example 1 to obtain a high-content p-monane product, wherein the raw material is dipentene and the catalyst is a high-performance alumina-supported nickel-chromium catalyst.

[0138] Example 5

[0139] A high-performance alumina-supported nickel-chromium catalyst is prepared from the following raw materials in parts by weight: 11.6 parts of alumina, 3 parts of polyethylene glycol, 8 parts of nickel nitrate, 5.8 parts of chromium nitrate, 0.37 parts of hexadecyltrimethylammonium bromide, 1.4 parts of tetrabutyl titanate, 0.2 parts of sodium tripolyphosphate, 5.2 parts of anhydrous ethanol, and 2.5 parts of glacial acetic acid.

[0140] The method for preparing the high-performance alumina-supported nickel-chromium catalyst comprises the following steps:

[0141] S1. Preparation of alumina carrier: mixing alumina powder with polyethylene glycol, and calcining at 650° C. for 3 h to obtain an alumina carrier for standby use;

[0142] S2. Preparation of nickel-chromium solution: nickel nitrate and chromium nitrate are dissolved in an appropriate amount of deionized water to prepare a mixed solution with a concentration of 1 mol / L for later use;

[0143] S3, preparation of auxiliary agent solution: dissolve hexadecyltrimethylammonium bromide in deionized water to prepare a solution with a concentration of 0.2 mol / L for standby use; slowly add anhydrous ethanol and glacial acetic acid to tetrabutyl titanate, stir evenly, and obtain a tetrabutyl titanate solution for standby use; dissolve sodium tripolyphosphate in deionized water to prepare a solution with a concentration of 0.5 mol / L for standby use;

[0144] S4, coprecipitation-deposition: in a reaction vessel with a stirring device, add the pretreated alumina and an appropriate amount of deionized water to form a suspension, under stirring conditions, slowly drop the nickel-chromium mixed solution and the hexadecyltrimethylammonium bromide solution into the reaction vessel at the same time, keep the temperature at 45°C during the dropping process, and continue to stir for 1.5 hours after the dropping is completed; slowly drop the tetrabutyl titanate solution into the system, and control the pH value of the reaction system to 2, and continue to stir for 2.8 hours after the dropping is completed; slowly drop the sodium tripolyphosphate solution into the system, and continue to stir for 1 hour after the dropping is completed. During the whole process, the pH value of the reaction system is controlled to be 7;

[0145] S5, reaction and filtration: react the reaction system at 70°C for 6 hours, filter after the reaction is completed, and wash the precipitate;

[0146] S6. Drying and calcination: The washed precipitate was dried at 120° C. for 20 hours, cooled to room temperature, heated to 550° C. at a heating rate of 3° C. / min, and calcined for 5 hours to obtain a high-performance alumina-supported nickel-chromium catalyst.

[0147] A method for producing high-content p-monane, wherein a catalyst is used to produce a crude p-monane product by a dipentene hydrogenation method, and the crude p-monane product is distilled by the same distillation equipment as in Example 1 to obtain a high-content p-monane product, wherein the raw material is dipentene and the catalyst is a high-performance alumina-supported nickel-chromium catalyst.

[0148] Comparative Example 1

[0149] The method is basically the same as Example 1, except that hexadecyltrimethylammonium bromide, tetrabutyl titanate and sodium tripolyphosphate are not added to the catalyst.

[0150] Comparative Example 2

[0151] The method is basically the same as Example 1, except that tetrabutyl titanate and sodium tripolyphosphate are not added to the catalyst, but only hexadecyltrimethylammonium bromide is added.

[0152] Comparative Example 3

[0153] It is basically the same as Example 1, except that, in the catalyst, hexadecyltrimethylammonium bromide and sodium tripolyphosphate are not added, but only tetrabutyl titanate is added.

[0154] Comparative Example 4

[0155] The method is basically the same as Example 1, except that, in the catalyst, hexadecyltrimethylammonium bromide and tetrabutyl titanate are not added, but only sodium tripolyphosphate is added.

[0156] Comparative Example 5

[0157] It is basically the same as Example 1, except that polyethylene glycol is not added to the catalyst.

[0158] 1. Dipentene conversion and p-menthane content experiment

[0159] The catalyst obtained by the methods of Examples 1-5 and Comparative Examples 1-5 is used for preparing crude p-menthane by dipentene hydrogenation method. The crude p-menthane is distilled by distillation equipment to obtain a high-content p-menthane product, and the conversion rate of dipentene and the p-menthane content are detected by chromatography.

[0160] Table 1 Dipentene conversion and p-menthane content

[0161]

[0162] It can be seen from Table 1 that:

[0163] (1) In Examples 1-5 of the present invention, the conversion rates of α-terpinene, p-cymene, limonene, γ-terpinene and terpinene in dipentene are greater than those in Comparative Examples 1-4, and the content of p-menthane is also greater than that in Comparative Examples 1-5. In Example 1, the conversion rates of α-terpinene, p-cymene, limonene, γ-terpinene and terpinene are 98.7%, 98.5%, 98.7%, 98.4% and 98.6%, respectively, and the content of p-menthane is 98.7%.

[0164] It is shown that in the alumina-supported nickel-chromium catalyst of the present invention, hexadecyltrimethylammonium bromide, tetrabutyl titanate and sodium tripolyphosphate can work together to synergistically improve the catalytic effect of the catalyst, significantly improve the conversion rate of dipentene, and thus greatly increase the content of p-menane.

[0165] This is because: alumina is used as a carrier, and nickel and chromium are used as active ingredients. The addition of chromium can change the dispersion state of nickel on the surface of alumina. Chromium can form alloys or compounds with nickel and be evenly distributed in the pores and surface of alumina. The high specific surface area of ​​alumina helps to disperse these active ingredients, and the alumina carrier and the active components can be connected to each other through chemical bonds such as Al-O-Ni, Al-O-Cr, etc. to form a stable structure. In the preparation of p-menthane, chromium may enhance the stability of the catalyst. Under reaction conditions such as high temperature and high pressure, chromium can prevent the sintering and agglomeration of nickel particles and maintain the high activity state of the active components. At the same time, chromium will participate in the catalytic process of the reaction. Chromium can change the electron cloud density on the catalyst surface, making it easier for dipentene molecules to adsorb on the catalyst surface, and is conducive to the hydrogenation reaction, thereby increasing the content of p-menthane.

[0166] Hexadecyltrimethylammonium bromide has a template-directing effect and can form micelle structures in solution. In the process of catalyst preparation, its micelles can serve as soft templates to guide metal ions such as nickel and chromium and alumina precursors to be arranged and aggregated around them, which is conducive to the formation of a regular pore structure, increasing the specific surface area of ​​the catalyst and providing more active sites for the reaction. At the same time, there is an interaction between the hydrophilic group of hexadecyltrimethylammonium bromide and the alumina precursor, which can effectively reduce the surface tension, prevent the agglomeration of active components and carriers, and make the nickel-chromium active components more evenly dispersed on the alumina carrier, thereby improving the utilization rate of active components and the activity of the catalyst. Tetrabutyl titanate releases active titanium species during hydrolysis and polycondensation. These active titanium species can interact with the alumina carrier to form Ti-O-Al bonds, thereby enhancing the stability and mechanical strength of the carrier. At the same time, the presence of titanium species may also change the surface properties of the carrier, adjust its acidity and alkalinity, and make it more conducive to the loading of nickel-chromium active components and the adsorption and activation of reaction molecules; at the same time, the titanium hydroxy compound produced by the hydrolysis of tetrabutyl titanate can chemically bond or coordinate with nickel and chromium ions, prevent the agglomeration of active components, promote their dispersion on the surface of alumina carrier, and improve the activity and selectivity of the catalyst. In addition, the introduction of titanium may also increase the interaction between active components and carriers, and improve the anti-sintering ability of catalysts during the reaction process. Sodium tripolyphosphate has a strong chelating ability and can form a stable chelate with nickel and chromium ions. During the preparation of the catalyst, this chelation can effectively control the precipitation rate and particle size of the active component, prevent its rapid agglomeration and growth, and make the active component evenly dispersed on the alumina carrier with a smaller particle size, increase the specific surface area of ​​the active component and the exposure degree of the active site, thereby improving the activity of the catalyst; at the same time, the chelate formed by sodium tripolyphosphate and the active component can maintain good stability during the calcination and reaction of the catalyst, reduce the loss and sintering of the active component, and improve the service life and stability of the catalyst. At the same time, sodium tripolyphosphate can also interact with the hydroxyl groups on the surface of the alumina carrier, further enhancing the binding force between the active components and the carrier, so that the catalyst can maintain good structural integrity under reaction conditions.

[0167] Hexadecyltrimethylammonium bromide makes the active components and carrier precursors dispersed evenly through the role of micelle template and reducing surface tension; tetrabutyl titanate further promotes the dispersion of active components on the carrier through chemical bonding or coordination; sodium tripolyphosphate controls the particle size and precipitation process of active components through chelation. The three work together to achieve highly uniform dispersion of nickel-chromium active components on the alumina carrier, greatly improving the activity and selectivity of the catalyst; the micelle template formed by hexadecyltrimethylammonium bromide provides a regular pore structure for the catalyst; the titanium species produced by the hydrolysis of tetrabutyl titanate enhances the stability of the carrier and adjusts the surface properties; the interaction between sodium tripolyphosphate and the active components and the carrier further stabilizes the structure of the catalyst. The three work synergistically to construct a catalyst system with suitable pore structure, high stability and good distribution of active components, which is conducive to the diffusion and adsorption of reaction molecules and improves the catalytic performance and anti-deactivation ability of the catalyst.

[0168] In addition, the titanium species introduced by tetrabutyl titanate may change the electronic structure of the catalyst and affect the electron cloud density of the active component; the chelation effect of sodium tripolyphosphate may also have a certain effect on the electronic state of the active component. The presence of CTAB may affect the charge transfer and electron transfer process between the active component and the carrier. The electronic effects among the three work together to optimize the electronic state of the active component, making it easier to adsorb and activate the reaction molecules, thereby improving the catalytic activity and reaction selectivity of the catalyst.

[0169] In summary, the present invention can synergistically and significantly increase the content of p-menthane by using a high-performance alumina-supported nickel-chromium catalyst and adding hexadecyltrimethylammonium bromide, tetrabutyl titanate and sodium tripolyphosphate during catalyst preparation.

[0170] (2) In Examples 1-5 of the present invention, polyethylene glycol was added. Compared with Comparative Example 5 in which polyethylene glycol was not added, the conversion rates of α-terpinene, p-cymene, limonene, γ-terpinene, and terpinene, as well as the content of p-menthane were all improved.

[0171] This is due to:

[0172] The present invention adds polyethylene glycol to the alumina carrier for calcination. During the calcination process, the polyethylene glycol will decompose at high temperature, and its molecular chain will stretch between or inside the alumina particles. As the temperature rises, it will gradually decompose to generate small molecular volatiles such as carbon dioxide and water and leave the system. This process will leave gaps in the alumina, thereby changing the pore structure of the alumina and increasing the pore size and pore volume. The enlarged pore structure provides a wider dispersion space for the nickel-chromium active component, so that the active component can be more evenly distributed in the pores of the alumina carrier, so that the active sites are more dispersed. For example, in the coprecipitation-deposition process, the active component is more likely to enter the alumina pores after the pores are expanded, and in the subsequent drying and calcination process, a good dispersion state can be maintained. At the same time, the alumina carrier after the polyethylene glycol pores are expanded, and its pore wall structure may be more stable due to the reasonable distribution of pores. This stable carrier structure can better withstand the temperature changes, pressure changes and changes in the active components during the reaction process, reduce the fragmentation and pulverization of the carrier, and in addition, the pore expansion process may affect the distribution of functional groups such as hydroxyl groups on the surface of the alumina. The increase in pores changes the degree of exposure of functional groups on the surface of alumina, which can in turn regulate the interaction between the active components and the carrier, enhance the chemical bonding between the active components and the carrier, make the catalyst structure more stable, and thus improve the catalytic effect of the catalyst.

[0173] 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 method for producing high-content p-monane, wherein a crude p-monane product is produced by a dipentene hydrogenation method using a catalyst, and the crude p-monane product is distilled by a distillation device to obtain a high-content p-monane product, wherein the raw material is dipentene, and the method is characterized in that: The catalyst is a high-performance alumina-supported nickel-chromium catalyst, which is made of the following raw materials in parts by weight: 10.2-15.4 parts of alumina, 0.5-3 parts of polyethylene glycol, 5.7-8.5 parts of nickel nitrate, 4.1-6.2 parts of chromium nitrate, 0.3-0.45 parts of hexadecyltrimethylammonium bromide, 1-1.5 parts of tetrabutyl titanate, 0.2-0.3 parts of sodium tripolyphosphate, 5-6.5 parts of anhydrous ethanol, and 1-3 parts of glacial acetic acid.

2. The method for producing high-content p-menthane according to claim 1, characterized in that: The catalyst is a high-performance alumina-supported nickel-chromium catalyst, which is made of the following raw materials in parts by weight: 13.5 parts of alumina, 0.5 parts of polyethylene glycol, 6.8 parts of nickel nitrate, 6.2 parts of chromium nitrate, 0.42 parts of hexadecyltrimethylammonium bromide, 1.5 parts of tetrabutyl titanate, 0.28 parts of sodium tripolyphosphate, 5.6 parts of anhydrous ethanol, and 3 parts of glacial acetic acid.

3. The method for producing high-content p-menthane according to claim 1 or 2, characterized in that: The method for preparing the high-performance alumina-supported nickel-chromium catalyst comprises the following steps: S1. Preparation of alumina carrier: preparing alumina carrier by mixing alumina powder and polyethylene glycol for later use; S2. Preparation of nickel-chromium solution: nickel nitrate and chromium nitrate are dissolved in water to prepare a mixed solution with a concentration of 0.5-1.5 mol / L for later use; S3, preparation of auxiliary agent solution: prepare cetyltrimethylammonium bromide, tetrabutyl titanate and sodium tripolyphosphate into solutions for standby use; S4, coprecipitation-deposition: in a reaction vessel with a stirring device, add pretreated alumina and water to form a suspension, under stirring conditions, simultaneously drop the nickel-chromium mixed solution and the hexadecyltrimethylammonium bromide solution into the reaction vessel, keep the temperature at 40-60°C during the dropwise addition, and continue stirring for 1-2 hours after the dropwise addition is completed; drop the tetrabutyl titanate solution into the system, and control the pH value of the reaction system to 2-3, and continue stirring for 2-3 hours after the dropwise addition is completed; drop the sodium tripolyphosphate solution into the system, and continue stirring for 1-2 hours after the dropwise addition is completed, and control the pH value of the reaction system to 7-9 during the whole process; S5, reaction and filtration: react in the reaction system, filter after the reaction, and wash the precipitate; S6. Drying and calcining: Dry the washed precipitate at 100-120° C. for 12-24 hours, cool it to room temperature, and then heat it up and calcine it for 4-8 hours to obtain a high-performance alumina-supported nickel-chromium catalyst.

4. The method for producing high-content p-menthane according to claim 3, characterized in that: In S1, the specific preparation method of the alumina carrier is: mixing alumina powder with polyethylene glycol, and calcining at 500-700° C. for 3-5 hours to obtain the alumina carrier.

5. The method for producing high-content p-menthane according to claim 3, characterized in that: In S3, the preparation method of the cetyltrimethylammonium bromide solution is: dissolving cetyltrimethylammonium bromide in deionized water to prepare a solution with a concentration of 0.1-0.3 mol / L.

6. The method for producing high-content p-menthane according to claim 3, characterized in that: In S3, the tetrabutyl titanate solution is prepared by slowly dropping anhydrous ethanol and glacial acetic acid into tetrabutyl titanate and stirring the mixture to obtain the tetrabutyl titanate solution.

7. The method for producing high-content p-menthane according to claim 3, characterized in that: In S3, the sodium tripolyphosphate solution is prepared by dissolving sodium tripolyphosphate in deionized water to prepare a solution with a concentration of 0.2-0.5 mol / L.

8. The method for producing high-content p-menthane according to claim 3, characterized in that: The reaction conditions in S5 are: reacting at 60-80° C. for 6-12 hours.

9. The method for producing high-content p-menthane according to claim 3, characterized in that: In S6, the temperature is raised to 400-600°C.

10. The method for producing high-content p-menthane according to claim 9, characterized in that: The heating rate is 2-5°C / min.

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