Preparation method of alkyl cyclohexanol, adopted catalyst and preparation method of catalyst

Abstract

The invention discloses a preparation method of alkyl cyclohexanol, an adopted catalyst and a preparation method of the catalyst.The preparation method belongs to the technical field of synthesis of alkyl cyclohexanol, the catalyst is a nitrogen-doped biomass-based mesoporous carbon-loaded bimetallic catalyst.A high-performance carbon carrier is prepared at low cost through pyrolysis and nitrogen doping processes, and the high-performance carbon carrier is prepared at high temperature; according to the present invention, the supported bimetallic is adopted as the active material, such that the catalyst has the high specific surface area and the high catalytic activity so as to regulate the oxidation state and the catalytic activity of the metal and enhance the reducibility of the metal particles, and the catalyst is used for the alkyl cyclohexanol preparation so as to promote the reaction to the product direction, and effectively improve the hydrogenation selectivity and the product conversion rate.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of alkylcyclohexanol synthesis, and particularly relates to a preparation method of alkylcyclohexanol, a catalyst used in the method and a preparation method of the catalyst. BACKGROUND

[0002] Alkylphenol environmental hormones exist widely in plastic and other daily necessities. Under certain conditions, alkylphenol environmental hormones can migrate into food, and along with various plastic product life garbage produced by people, the phenolic environmental hormones can migrate from plastic products to water bodies and soil. Alkylphenol environmental hormones are very stable in nature and are difficult to be degraded in the environment, and have biological accumulation and amplification effects. Therefore, various countries have successively introduced regulations to limit products containing alkylphenol environmental hormones. Alkylcyclohexanol is prepared by hydrogenation of alkylphenol, which can effectively reduce the harm to the environment and the influence on human health. Due to the excellent decontamination, wetting, dispersion and compatibilization and emulsification performance of alkylphenol, the demand for alkylphenol at home and abroad is still large. It is found that alkylcyclohexanol prepared by further reaction of alkylphenol can maximize the performance of alkylphenol polyoxyethylene ether. Alkylcyclohexanol prepared by hydrogenation of alkylphenol has similar structure and performance to alkylphenol, is an important intermediate for producing non-ionic surfactants, and has the advantages of no environmental toxicity, no biological accumulation and biodegradability.

[0003] At present, the method for preparing alkylcyclohexanol in the prior art is to use alkylphenol and hydrogen as raw materials, metal nickel and palladium as active components, and activated carbon as a carrier to prepare a hydrogenation catalyst, and to perform gas-liquid-solid three-phase catalytic reaction in a fixed bed reactor. However, the conversion rate of the reaction is low, and by-products are generated, which is not conducive to product collection. SUMMARY

[0004] The application provides a preparation method of alkylcyclohexanol, a catalyst used in the method and a preparation method of the catalyst, which can effectively improve the hydrogenation selectivity and product conversion rate in the preparation process of alkylcyclohexanol.

[0005] To achieve the above object, the following technical scheme is adopted in the application. A preparation method of alkylcyclohexanol, comprising the following steps: After mixing alkylphenol and a solvent, the mixture is placed in a reaction kettle, a catalyst is added, the air in the kettle is replaced with hydrogen for 3-5 times, the hydrogen pressure is adjusted to 2-8 MPa, the temperature is increased to 120-180 DEG C, and the mixture is stirred for 6-10 h. After the reaction is completed, the mixture is cooled, depressurized, and the catalyst is recovered by filtration. The solvent is removed from the filtrate by vacuum distillation to obtain alkylcyclohexanol.

[0006] The alkyl phenol includes at least one of propyl phenol, butyl phenol, pentyl phenol, heptyl phenol, octyl phenol, nonyl phenol; the solvent includes methanol, ethanol, tetrahydrofuran, deionized water.

[0007] The mass ratio of the alkyl phenol to the solvent is 1:5~10, and the catalyst is used in an amount of 1~10 wt% of the raw material.

[0008] The catalyst used in the above preparation method is a nitrogen-doped biomass-based mesoporous carbon supported bimetallic catalyst, which uses nitrogen-doped biomass-based mesoporous carbon as a carrier, loads nickel and molybdenum metal particles, and the mesoporous structure of the carrier has a high specific surface area and a pore structure, providing a carrier platform for uniform dispersion of nickel and molybdenum metal particles. The introduction of nitrogen atoms in nitrogen-doped changes the local electron density of carbon materials and serves as an anchoring point for metal particles.

[0009] The preparation method of the above catalyst includes the following steps: (1) 20~40 parts by weight of nitrogen-doped biomass-based mesoporous carbon, 8~10 parts by weight of palladium nitrate, 8~10 parts by weight of platinum nitrate, and 40~80 parts by weight of deionized water are weighed respectively; (2) The palladium nitrate and platinum nitrate are added to the deionized water and stirred to dissolve, obtaining a metal salt solution; (3) The nitrogen-doped biomass-based mesoporous carbon is placed in a container, the metal salt solution is added dropwise and stirred until the nitrogen-doped biomass-based mesoporous carbon is completely wet, then the dropwise addition is stopped, and after standing for 10~12 h, it is placed in an oven, the temperature is set to 60~80°C, and the temperature is maintained for 10~12 h for drying, obtaining a catalyst precursor; (4) The catalyst precursor is placed in a tube furnace, heated to 400~500°C at a rate of 5~10°C / min under a hydrogen atmosphere and maintained for 2~4 h, and then cooled to room temperature, obtaining a nitrogen-doped biomass-based mesoporous carbon supported bimetallic catalyst.

[0010] The preparation method of the nitrogen-doped biomass-based mesoporous carbon includes the following steps: S1, biomass is mechanically ground into particles in a grinder to obtain biomass powder, the biomass powder is mixed with hydrochloric acid solution, soaked and treated at 70~90°C in a water bath for 2~4 h, washed with deionized water for 3~5 times after filtration, and then dried in an oven at a temperature of 60~80°C to constant weight, obtaining pretreated biomass powder; S2, the pretreated biomass powder is placed in a tube furnace, nitrogen is introduced for protection, heated to 400~800°C at a rate of 2~4°C / min and maintained for 2~4 h, then water vapor is introduced into the tube furnace, and heated to 700~900°C at a rate of 4~6°C / min, and maintained for 0.5~1.5 h for activation, and then cooled to room temperature, obtaining nitrogen-doped biomass-based mesoporous carbon.

[0011] In S1, the biomass powder comprises at least one of coconut shell powder, peanut shell powder and walnut shell powder, the particle size of the biomass powder is 100-200 mu m, the mass ratio of the biomass powder to the hydrochloric acid solution is 1:80-100, and the mass fraction of the hydrochloric acid solution is 10%.

[0012] In S2, the flow rate of nitrogen is 50-200 mL / min, and the flow rate of water vapor is 20-100 mL / min.

[0013] Beneficial effects: The application provides a preparation method of alkylcyclohexanol, and a catalyst and a preparation method of the catalyst, and has the following advantages compared with the prior art: The application adopts nitrogen-doped biomass-based mesoporous carbon as a carrier to load nickel and molybdenum metals to prepare a catalyst for alkyl phenol hydrogenation. The nitrogen-doped biomass-based mesoporous carbon has a high specific surface area and a developed pore structure, which provides an ideal carrier platform for uniform dispersion of nickel and molybdenum active metal particles. The ordered mesoporous structure is not only beneficial to efficient diffusion of reactants and products, but also can limit aggregation of metal particles by adjusting pore size, thereby improving stability of the catalyst. Meanwhile, introduction of nitrogen atoms can significantly change local electron density of the carbon material, induce electron transfer between the carrier and the active metal, thereby regulating oxidation state and catalytic activity of the metal, enhancing reducibility of the metal particles, and promoting selectivity of the hydrogenation reaction. In addition, nitrogen can act as an anchoring site to stabilize the metal nanoparticles and prevent sintering inactivation of the metal nanoparticles.

[0014] The application uses biomass as a raw material to prepare mesoporous carbon, which has high thermal stability and chemical inertness. After nitrogen doping, strong metal-carrier interaction is formed on the surface of the mesoporous carbon, which can significantly improve the sintering resistance and carbon deposition resistance of the catalyst. The metal catalyst loaded on the nitrogen-doped mesoporous carbon can maintain good activity after multiple cycles. In addition, the biomass raw material is widely available and renewable. The high-performance carbon carrier can be prepared at low cost through pyrolysis and nitrogen doping processes, which reduces dependence on fossil resources and makes the carrier have higher specific surface area and catalytic activity, thereby promoting the reaction to proceed in the direction of the product, effectively improving the hydrogenation selectivity and product conversion rate. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 A scanning electron microscope characterization graph of the nitrogen-doped biomass-based mesoporous carbon prepared for the embodiment 1 of the application; Figure 2 A nitrogen adsorption-desorption characterization graph of the nitrogen-doped biomass-based mesoporous carbon prepared for the embodiment 1 of the application; Figure 3 A pore size distribution characterization graph of the nitrogen-doped biomass-based mesoporous carbon prepared for the embodiment 1 of the application; Figure 4The XRD characterization chart of the nitrogen-doped biomass-based mesoporous carbon prepared for the embodiment 1 of the present application; Figure 5 The XPS characterization chart of the nitrogen-doped biomass-based mesoporous carbon prepared for the embodiment 1 of the present application. DETAILED DESCRIPTION

[0016] The present application will be described in detail below with specific examples and drawings, but the embodiments of the present application are not limited thereto, and for the process parameters not specifically mentioned, the conventional techniques can be referred to. Embodiment 1

[0017] The catalyst carrier preparation method of the present embodiment comprises the following steps: S1, the coconut shell is mechanically ground into particles with a particle size of 100 μm in a grinder to obtain coconut shell powder, the coconut shell powder is mixed with a hydrochloric acid solution with a mass fraction of 10% at a mass ratio of 1:80, soaked and treated at 70°C in a water bath for 2 h, washed with deionized water for 3 times after filtration, and dried in an oven at a temperature of 60°C to constant weight to obtain pretreated biomass powder; S2, the pretreated coconut shell powder is placed in a tube furnace, nitrogen gas is passed in at a flow rate of 50 mL / min for protection, the temperature is raised to 400°C at a temperature raising rate of 2°C / min and kept for 2 h, water vapor is passed into the tube furnace at a flow rate of 20 mL / min, and the temperature is raised to 700°C at a temperature raising rate of 4°C / min, and kept for 0.5 h for activation at normal temperature, and cooled at normal temperature to obtain nitrogen-doped biomass-based mesoporous carbon. The nitrogen-doped biomass-based mesoporous carbon prepared in the present embodiment is characterized by scanning electron microscopy, nitrogen adsorption and desorption, XRD and XPS, and the specific results are shown in Figs. 1-4. Figures 1-5 Figure 1 The SEM characterization of the catalyst shows that the catalyst is in the form of spherical particles from the figure; Figure 2 Figure 3 The N2 adsorption characterization of the catalyst shows that the catalyst presents type VI isotherm and H3 type hysteresis loop, proving that the material has irregular pore structure, and the pore structure distribution chart shows that the material contains rich mesoporous structure; Figure 4 The XPS characterization chart shows that the material is amorphous carbon material. Embodiment 2

[0018] The catalyst carrier preparation method of the present embodiment comprises the following steps: S1, the peanut shell is mechanically ground into particles with a particle size of 150 μm in a grinder to obtain peanut shell powder, the peanut shell powder is mixed with a hydrochloric acid solution with a mass fraction of 10% at a mass ratio of 1:90, soaked and treated at 80°C in a water bath for 3 h, washed with deionized water for 4 times after filtration, and dried in an oven at a temperature of 70°C to constant weight to obtain pretreated peanut shell powder; ​​S2, the pretreated peanut shell powder was placed in a tube furnace, nitrogen was passed in at a flow rate of 100 mL / min for protection, the temperature was raised to 600°C at a rate of 3°C / min and kept for 3h, then water vapor was passed into the tube furnace at a flow rate of 60 mL / min, while the temperature was raised to 800°C at a rate of 5°C / min, and activated for 1h, and then cooled to room temperature, to obtain nitrogen-doped biomass-based mesoporous carbon. Example 3

[0019] The catalyst carrier preparation method of the present embodiment comprises the following steps: S1, the walnut shell was mechanically ground into particles with a particle size of 200μm in a grinder to obtain walnut shell powder, the walnut shell powder was mixed with a hydrochloric acid solution with a mass fraction of 10% at a mass ratio of 1:100, soaked and treated in a water bath at 90°C for 4h, washed with deionized water for 5 times after filtration, and then dried in an oven at a temperature of 80°C until the weight was constant to obtain pretreated walnut shell powder; S2, the pretreated walnut shell powder was placed in a tube furnace, nitrogen was passed in at a flow rate of 200 mL / min for protection, the temperature was raised to 800°C at a rate of 4°C / min and kept for 4h, then water vapor was passed into the tube furnace at a flow rate of 100 mL / min, while the temperature was raised to 900°C at a rate of 6°C / min, and activated for 1.5h, and then cooled to room temperature, to obtain nitrogen-doped biomass-based mesoporous carbon.

[0020] Examples 1-3 use a segmented holding method in the preparation of the carrier nitrogen-doped biomass-based mesoporous carbon, the purpose is: The essence of the first holding is the high-temperature carbonization process. Under the protection of inert gas nitrogen, volatile components (such as water, light tar, and part of the acidic functional groups) in the biomass will be precipitated first. As the temperature continues to rise, the biomass macromolecules (cellulose, hemicellulose, and lignin) will undergo thermal cracking, condensation, and aromatization reactions to generate a large amount of coke and some tar. In this process, the biomass is transformed from disordered organic polymers to an amorphous carbon skeleton mainly composed of sp² hybridized carbon, which is the basis for the formation of porous carbon materials. The escape of volatile substances leaves a large number of voids and channels in the carbon skeleton, but these channels are often blocked or covered by by-products such as tar and disordered carbon produced during pyrolysis. At this time, the specific surface area of the material has already developed to a certain extent, but it is far from the best state, and the accessibility of the pores is poor. The biomass itself contains nitrogen-containing substances such as proteins. During the high-temperature carbonization process, these nitrogen elements will be fixed into the newly formed carbon skeleton in the form of pyridine nitrogen, pyrrole nitrogen, and graphite nitrogen, realizing in-situ nitrogen doping, which lays a chemical foundation for subsequent metal anchoring. The essence of the second heat preservation is a water vapor activation process. At a higher temperature, the carbon material is reacted with the activation agent (water vapor) in a controlled manner, which is a key step of "sculpting" a developed pore structure. Water vapor reacts with carbon at high temperature as follows: C + H2O → CO + H2 (endothermic reaction). This reaction selectively vaporizes (ablates) carbon atoms. Water vapor molecules preferentially attack the disordered, high-reactivity carbon atoms in the carbon skeleton, as well as the amorphous carbon and tar that block the pore channels after the first carbonization. Through this selective etching, the originally blocked micropores are opened, and the pore walls between adjacent micropores can also be vaporized and opened, thereby forming larger mesopores (2-50 nm). This is the core step of obtaining mesoporous carbon. The etching process creates a large number of new pores and makes the original pores more open and unobstructed, resulting in a dramatic increase in the specific surface area and total pore volume of the material. The high specific surface area greatly increases the subsequent loadable sites of metal particles. Water vapor activation helps to form a three-dimensional interconnected and highly open pore network, which is beneficial for the rapid diffusion of reactants and products and reduces the mass transfer resistance, which is crucial in catalytic reactions. Moreover, the etching process generates more defects and unsaturated sites at the edges of the carbon material, and may introduce oxygen-containing functional groups (such as -OH, -COOH). These sites not only enhance hydrophilicity, but also synergize with nitrogen-doped sites to serve as active sites for anchoring metal particles.

[0021] The reaction between water vapor and carbon is an endothermic reaction, and high temperature is beneficial for the activation reaction to proceed in the forward direction, improving the etching efficiency. Moreover, the water vapor is added in two steps. If the water vapor is directly introduced and quickly raised to a high temperature, the reaction will be too violent to control, which may lead to excessive ablation of the carbon skeleton and collapse, resulting in a very low yield and a wide pore size distribution. The "two-step method" of carbonization followed by activation in the present application is a classic and controllable strategy for preparing high-performance porous carbon. Example 4

[0022] The catalyst support used in the nitrogen-doped biomass-based mesoporous carbon-supported bimetallic catalyst of the present embodiment is the nitrogen-doped biomass-based mesoporous carbon prepared in Example 1. The nitrogen-doped biomass-based mesoporous carbon-supported bimetallic catalyst of the present embodiment is prepared by the following method, which comprises the following steps: (1) 20 parts of nitrogen-doped biomass-based mesoporous carbon, 8 parts of palladium nitrate, 8 parts of platinum nitrate, and 40 parts of deionized water are weighed according to the weight fraction; (2) The palladium nitrate and platinum nitrate are added to the deionized water and stirred to dissolve, obtaining a metal salt solution; (3) The nitrogen-doped biomass-based mesoporous carbon is placed in a container, and the metal salt solution is added dropwise and stirred until the nitrogen-doped biomass-based mesoporous carbon is completely wet. Stop adding dropwise, and after standing for 10 h, place it in an oven, set the temperature to 60°C, and heat and dry for 10 h, obtaining a catalyst precursor; (4) The catalyst precursor is loaded into a crucible, placed in a tube furnace, heated to 400°C at a heating rate of 5°C / min under a hydrogen atmosphere and held for 2 hours, and then cooled to room temperature to obtain a nitrogen-doped biomass-based mesoporous carbon supported bimetallic catalyst. Example 5

[0023] The catalyst support used in this embodiment of the nitrogen-doped biomass-based mesoporous carbon supported bimetallic catalyst is the nitrogen-doped biomass-based mesoporous carbon prepared in Example 2. The preparation method of this embodiment of the nitrogen-doped biomass-based mesoporous carbon supported bimetallic catalyst includes the following steps: (1) Weigh 30 parts nitrogen-doped biomass-based mesoporous carbon, 9 parts palladium nitrate, 9 parts platinum nitrate, and 60 parts deionized water by weight. (2) Add palladium nitrate and platinum nitrate to deionized water and stir to dissolve them to obtain a metal salt solution; (3) Place nitrogen-doped biomass-based mesoporous carbon in a container, add metal salt solution dropwise to the container and stir until the nitrogen-doped biomass-based mesoporous carbon is completely wetted, stop adding dropwise, let stand for 11 hours and then put it in an oven, set the temperature to 70℃, keep it warm and dry for 11 hours to obtain the catalyst precursor. (4) The catalyst precursor was loaded into a crucible and placed in a tube furnace. The temperature was increased to 450°C at a rate of 6°C / min under a hydrogen atmosphere and held for 3 hours. The catalyst was then cooled to room temperature to obtain a nitrogen-doped biomass-based mesoporous carbon-supported bimetallic catalyst. Example 6

[0024] The catalyst support used in this embodiment of the nitrogen-doped biomass-based mesoporous carbon-supported bimetallic catalyst is the nitrogen-doped biomass-based mesoporous carbon prepared in Example 3. The preparation method of this embodiment of the nitrogen-doped biomass-based mesoporous carbon-supported bimetallic catalyst includes the following steps: (1) Weigh 40 parts nitrogen-doped biomass-based mesoporous carbon, 10 parts palladium nitrate, 10 parts platinum nitrate, and 80 parts deionized water by weight. (2) Add palladium nitrate and platinum nitrate to deionized water and stir to dissolve them to obtain a metal salt solution; (3) Place nitrogen-doped biomass-based mesoporous carbon in a container, add metal salt solution to the container and stir until the nitrogen-doped biomass-based mesoporous carbon is completely wetted, stop adding, let stand for 12 hours and then put it in an oven, set the temperature to 80℃, keep it warm and dry for 12 hours to obtain the catalyst precursor. (4) The catalyst precursor was placed in a crucible and placed in a tube furnace. The temperature was increased to 500°C at a rate of 10°C / min under a hydrogen atmosphere and held for 4 hours. The catalyst was then cooled to room temperature to obtain a nitrogen-doped biomass-based mesoporous carbon-supported bimetallic catalyst. Example 7

[0025] The catalyst used for the alkylcyclohexanol in this embodiment is the nitrogen-doped biomass-based mesoporous carbon-supported bimetallic catalyst prepared in Example 4. The preparation method of the alkylcyclohexanol in this embodiment includes the following steps: Propylphenol and methanol were mixed at a mass ratio of 1:5 and placed in a reaction vessel. A nitrogen-doped biomass-based mesoporous carbon-supported bimetallic catalyst was added, with the catalyst amount being 1 wt% of the raw materials. After replacing the air in the vessel with hydrogen three times, the hydrogen pressure was adjusted to 2 MPa. The temperature was raised to 120°C and the reaction was stirred. After the reaction was completed, the mixture was cooled, the pressure was released, and the catalyst was recovered by filtration. The solvent was removed by vacuum distillation of the filtrate to obtain alkylcyclohexanol.

[0026] In this embodiment, the conversion rate of propionic acid was 98.2%, and the selectivity was 98.6%. Example 8

[0027] The catalyst used for the alkylcyclohexanol in this embodiment is the nitrogen-doped biomass-based mesoporous carbon-supported bimetallic catalyst prepared in Example 4. The preparation method of the alkylcyclohexanol in this embodiment includes the following steps: Pentylphenol and ethanol were mixed at a mass ratio of 1:8 and placed in a reaction vessel. A nitrogen-doped biomass-based mesoporous carbon-supported bimetallic catalyst was added, with the catalyst amount being 5 wt% of the raw materials. After replacing the air in the vessel with hydrogen four times, the hydrogen pressure was adjusted to 5 MPa. The temperature was raised to 160°C and stirred for reaction. After the reaction was completed, the mixture was cooled, the pressure was released, the catalyst was recovered by filtration, and the solvent was removed by vacuum distillation of the filtrate to obtain alkylcyclohexanol.

[0028] In this embodiment, the conversion rate of pentylphenol was 98.7%, and the selectivity was 99.3%. Example 9

[0029] The catalyst used for the alkylcyclohexanol in this embodiment is the nitrogen-doped biomass-based mesoporous carbon-supported bimetallic catalyst prepared in Example 4. The preparation method of the alkylcyclohexanol in this embodiment includes the following steps: Heptylphenol and tetrahydrofuran were mixed at a mass ratio of 1:10 and placed in a reactor. A nitrogen-doped biomass-based mesoporous carbon-supported bimetallic catalyst was added, with the catalyst amount being 10 wt% of the raw materials. After replacing the air in the reactor with hydrogen five times, the hydrogen pressure was adjusted to 8 MPa. The temperature was raised to 180°C and stirred for reaction. After the reaction was completed, the mixture was cooled, the pressure was released, and the catalyst was recovered by filtration. The solvent was removed by vacuum distillation of the filtrate to obtain alkylcyclohexanol.

[0030] In this embodiment, the conversion rate of heptaphenol was 97.6%, and the selectivity was 97.9%.

[0031] Comparative Example 1 The preparation method of the alkylcyclohexanol in this comparative example is roughly the same as that in Example 7. The difference is that the catalyst used in this comparative example is a commercially available nickel-based hydrogenation catalyst. The conversion rate of propionic acid in this comparative example is 88.2%, and the selectivity is 89.7%.

[0032] Comparative Example 2 The preparation method of alkylcyclohexanol in this comparative example is roughly the same as that in Example 7. The difference is that the catalyst used in this comparative example is a platinum-carbon hydrogenation catalyst. The conversion rate of propionic acid in this comparative example is 91.2%, and the selectivity is 92.5%.

[0033] As can be seen from the comparison of Examples 7-9 and Comparative Examples 1-2, the nitrogen-doped biomass-based mesoporous carbon-supported bimetallic catalyst provided by the present invention exhibits a conversion rate of over 97% for the hydrogenation of different types of alkylphenols. Compared with commercially available nickel-based hydrogenation catalysts and platinum-carbon hydrogenation catalysts, it demonstrates better conversion rate and selectivity. This is because the catalyst of the present invention uses biomass as a raw material to prepare mesoporous carbon, which itself has high thermal stability and chemical inertness. Combined with nitrogen doping, the strong metal-support interaction formed on its surface can significantly improve the catalyst's resistance to sintering and carbon deposition. The nitrogen-doped mesoporous carbon-supported metal catalyst can still maintain good activity after multiple cycles of use. Furthermore, biomass raw materials are widely available and renewable. High-performance carbon supports can be prepared at low cost through pyrolysis and nitrogen doping processes, reducing dependence on fossil resources and simultaneously enabling the support to possess higher performance. By utilizing nitrogen-doped biomass-based mesoporous carbon as a support to load nickel-molybdenum metal, a catalyst for the hydrogenation of alkylphenols was prepared. The nitrogen-doped biomass-based mesoporous carbon possesses a high specific surface area and well-developed pore structure, providing an ideal support platform for the uniform dispersion of nickel-molybdenum active metal particles. Its ordered mesoporous structure not only facilitates the efficient diffusion of reactants and products but also limits the aggregation of metal particles by regulating pore size, thereby improving catalyst stability. Simultaneously, the introduction of nitrogen atoms significantly alters the local electron density of the carbon material, initiating electron transfer between the support and the active metal. Furthermore, nitrogen acts as an anchoring point, stabilizing metal nanoparticles and preventing sintering deactivation, thus regulating the oxidation state and catalytic activity of the metal, enhancing the reducibility of the metal particles, promoting the selectivity of the hydrogenation reaction, and directing the reaction towards the product, effectively improving hydrogenation selectivity and product conversion rate.

[0034] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A catalyst for the preparation of alkylcyclohexanols, characterized in that The catalyst is supported by nitrogen-doped biomass-based mesoporous carbon, and nickel-molybdenum metal particles are loaded on the mesoporous structure of the carrier, which has a high specific surface area and pore structure, and provides a carrier platform for uniform dispersion of the nickel-molybdenum metal particles; the introduction of nitrogen atoms in the nitrogen-doped carbon material changes the local electron density of the carbon material and serves as an anchoring point for the metal particles.

2. A process for the preparation of a catalyst for the preparation of alkylcyclohexanols, characterized in that The method comprises the following steps: (1) adding palladium nitrate and platinum nitrate into deionized water to stir and dissolve, to obtain a metal salt solution; (2) placing the nitrogen-doped biomass-based mesoporous carbon in a container, adding the metal salt solution dropwise into the container and stirring until the nitrogen-doped biomass-based mesoporous carbon is completely wet, then stopping the dropwise addition, and after standing for 10-12 h, drying to obtain a catalyst precursor; (3) heating the catalyst precursor to 400-500°C at a rate of 5-10°C / min under a hydrogen atmosphere and maintaining the temperature for 2-4 h, and then cooling at room temperature to obtain a nitrogen-doped biomass-based mesoporous carbon-supported bimetallic catalyst.

3. The process for preparing the catalyst used in the preparation of alkylcyclohexanol according to claim 2, characterized by, According to weight parts, the nitrogen-doped biomass-based mesoporous carbon is 20-40 parts, the palladium nitrate is 8-10 parts, the platinum nitrate is 8-10 parts, and the deionized water is 40-80 parts.

4. The process for preparing the catalyst used in the preparation of alkylcyclohexanols according to claim 2 or 3, characterized in that, The preparation method of the nitrogen-doped biomass-based mesoporous carbon comprises the following steps: S1, grinding the biomass to obtain a biomass powder, mixing the biomass powder with a hydrochloric acid solution, soaking and treating the mixture at 70-90°C in a water bath for 2-4 h, washing with deionized water after filtration, and drying to constant weight to obtain a pretreated biomass powder; S2, heating the pretreated biomass powder to 400-800°C at a rate of 2-4°C / min under nitrogen protection and maintaining the temperature for 2-4 h, then passing in water vapor, heating to 700-900°C at a rate of 4-6°C / min, maintaining the temperature for 0.5-1.5 h, and cooling at room temperature to obtain the nitrogen-doped biomass-based mesoporous carbon.

5. The process for preparing the catalyst used in the preparation of alkylcyclohexanol according to claim 4, characterized by, The mass ratio of the biomass powder to the hydrochloric acid solution is 1:80-10.

6. The process for preparing the catalyst used in the preparation of alkylcyclohexanol according to claim 4 or 5, characterized in that, The particle size of the biomass powder is 100-200μm.

7. The process for preparing the catalyst used in the preparation of alkylcyclohexanol according to claim 4 or 5, characterized by, The mass fraction of the hydrochloric acid solution is 10%.

8. The process for preparing the catalyst used in the preparation of alkylcyclohexanol according to claim 4, characterized by, In S2, the flow rate of nitrogen is 50-200 mL / min, and the flow rate of water vapor is 20-100 mL / min.

9. A process for the preparation of an alkylcyclohexanol, characterized in that, The alkyl phenol is mixed with a solvent, and then placed in a reaction kettle; the catalyst of claim 1 is added; the air in the kettle is replaced with hydrogen for 3-5 times; the hydrogen pressure is adjusted to 2-8 MPa; the temperature is raised to 120-180°C; stirring is performed for 6-10 h; after the reaction is completed, the catalyst is recovered by cooling and depressurizing; the solvent is removed from the filtrate by vacuum distillation to obtain an alkylcyclohexanol. The mass ratio of the alkyl phenol to the solvent is 1:5-10, and the catalyst usage is 1-10 wt% of the raw material.

10. The process for preparing alkylcyclohexanol according to claim 9, characterized by, ​

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