Process for the catalytic hydrogenation of 2-isopropylphenol

Abstract

The present application relates to the technical field of catalytic hydrogenation, and particularly relates to a 2-isopropylbenzene alcohol catalytic hydrogenation preparation process, comprising the following steps: adding a cumene solution of cumene hydroperoxide and a composite catalyst into a high-pressure reaction kettle, and replacing air in the kettle with inert gas and hydrogen; filling hydrogen into the reaction kettle to a set pressure, and heating to a reaction temperature under stirring to perform a catalytic hydrogenation reaction, so as to obtain a reaction liquid containing 2-isopropylbenzene alcohol; and separating and purifying the reaction liquid to obtain 2-isopropylbenzene alcohol. The present application uses melamine formaldehyde resin as a carrier, and after alcohol reflux pretreatment, a composite catalyst is prepared by loading cerium manganese composite metal oxide through an in-situ coordination-hydrothermal method, so that the conversion rate of the cumene hydroperoxide catalytic hydrogenation reaction, the 2-isopropylbenzene alcohol selectivity and the yield are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of catalytic hydrogenation technology, and in particular to a process for the catalytic hydrogenation of 2-isopropylbenzeneol. Background Technology

[0002] 2-Isopropylbenzeneol (also known as 2-phenyl-2-propanol, α-phenylethanol, CAS No.: 617-94-7) is an aromatic alcohol organic intermediate. Its molecular structure contains a benzene ring and a hydroxyl functional group, exhibiting good chemical reactivity and participating in various organic synthesis reactions. Its applications are concentrated in the preparation of fragrances and cosmetic additives, where it can be used to synthesize fragrance components with special aromas, enhancing the sensory quality of products. It is also a key raw material for the synthesis of fine chemical products such as di(tert-butylperoxyisopropyl)benzene, and is widely used as a crosslinking agent and initiator in polymer materials. The preparation of 2-isopropylbenzeneol mainly uses aromatic ketones or phenolic compounds as raw materials, achieving conversion through reduction reactions. Catalytic hydrogenation is currently the mainstream technical route for the reduction preparation of alcohol products from these compounds. Catalytic hydrogenation reactions, with their advantages of mild reaction conditions, high selectivity, excellent atom economy, and no byproduct pollution, have been widely applied in pharmaceuticals, pesticides, fine chemicals, and other fields, becoming an important supporting technology for promoting the green upgrading of the chemical industry. In terms of catalytic systems, transition metal catalysts such as palladium, platinum, and nickel are commonly used catalytic materials in the catalytic hydrogenation of 2-isopropylbenzene alcohol. Some studies also use modified catalytic systems such as supported metal catalysts and alloy catalysts.

[0003] In existing technologies, commonly used precious metal catalysts such as palladium and platinum are prone to poisoning due to trace impurities in the raw materials during the reaction process. They are also prone to problems such as carbon deposition and sintering, which lead to catalyst deactivation, significantly shortening the catalyst life and increasing the total production cost. On the other hand, non-precious metal catalysts such as nickel-based catalysts have problems such as insufficient activity and poor selectivity, which can easily lead to excessive hydrogenation of the raw materials or side reactions, affecting the purity of the target product. Summary of the Invention

[0004] To address the problems mentioned in the background section, this invention provides a catalytic hydrogenation process for preparing 2-isopropylbenzene alcohol.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A catalytic hydrogenation process for preparing 2-isopropylbenzeneol includes the following steps:

[0007] S1. Add the cumene solution of hydrogen peroxide and the composite catalyst to a high-pressure reactor, and replace the air in the reactor with inert gas and hydrogen.

[0008] S2. Hydrogen gas is introduced into the reactor to the set pressure, and the temperature is raised to the reaction temperature under stirring to carry out the catalytic hydrogenation reaction, and a reaction solution containing 2-isopropylbenzene alcohol is obtained.

[0009] S3. Separate and purify the reaction solution to obtain 2-isopropylbenzene alcohol;

[0010] The composite catalyst is a cerium-manganese composite metal oxide supported on melamine-formaldehyde resin. It is prepared by a process that involves in-situ coordination of cerium and manganese metal ions with functional groups on the surface of melamine-formaldehyde resin, followed by hydrothermal crystallization growth.

[0011] Furthermore, the composite catalyst in step S1 is specifically prepared by the following steps:

[0012] A1. Melamine-formaldehyde resin powder is dispersed in alcohol and refluxed, then filtered, washed and dried to obtain a pretreated resin carrier. Cerium salt and manganese salt are dissolved in water to obtain a mixed solution of metal ions. The pretreated resin carrier is dispersed in water to form a suspension.

[0013] A2. Under stirring and heating conditions, a mixed solution of metal ions is added dropwise to a suspension to carry out a coordination reaction. A precipitant is added to the system after the coordination reaction, and the mixture is transferred to a high-pressure reactor for hydrothermal reaction. The product after hydrothermal reaction is filtered, washed with deionized water 3-5 times until the washing liquid is neutral, and dried at 70-90℃ for 6-12 hours to obtain a composite catalyst.

[0014] Further, in step S1, the mass fraction of cumene hydroperoxide in the cumene hydroperoxide solution is 20-40%, and the amount of composite catalyst added is 1-5% of the mass of the cumene hydroperoxide; the cumene hydroperoxide solution is prepared using anhydrous cumene at a preparation temperature of 20-30℃, with a stirring speed of 150-300 r / min and a stirring time of 10-30 min during the preparation process; the particle size of the composite catalyst is 200-800 mesh.

[0015] Further, step S1, which involves replacing the air inside the reactor with inert gas and hydrogen, includes: first replacing the reactor with inert gas 2-4 times, pressurizing to 0.3-0.8 MPa each time and then venting; then replacing the reactor with hydrogen 2-4 times, pressurizing to 0.3-0.8 MPa each time and then venting; the preferred inert gas is nitrogen, and the stirring speed is maintained at 100-200 r / min during the replacement process, and the pressure is stabilized for 5-10 minutes after each pressurization before venting to ensure that the air inside the reactor is completely replaced; the inert gas is nitrogen or argon.

[0016] Furthermore, in step S2, the pressure is set to 0.5MPa-1.0MPa, the reaction temperature for catalytic hydrogenation is 40-50℃, and the reaction time is 60-180min.

[0017] Furthermore, the separation step in step S3 is filtration, with a filtration temperature of 25-40℃, used to separate the composite catalyst in the reaction solution. After filtration, the catalyst is purified by vacuum distillation, with a vacuum degree of 0.08-0.095MPa and a distillation temperature of 80-100℃.

[0018] Further, in step A1, the mass-to-volume ratio of melamine-formaldehyde resin powder to alcohol solvent is 1g:(30-60)mL; the reflux treatment temperature is 50-60℃, and the time is 1-3h; a condenser reflux device is used during the reflux treatment, and the stirring speed is 200-400r / min. After the reflux is completed, the temperature is naturally cooled to 25-30℃ before filtration.

[0019] Further, in step A1, the cerium salt is cerium nitrate, the manganese salt is manganese nitrate, and the molar ratio of cerium to manganese is (0.4-0.6):(0.6-0.4); in the mixed metal ion solution, the total concentration of cerium ions and manganese ions is 0.3-0.8 mol / L; the cerium nitrate is cerium nitrate hexahydrate (Ce(NO3)3·6H2O), the manganese nitrate is manganese nitrate tetrahydrate (Mn(NO3)2·4H2O), and when preparing the mixed metal ion solution, the stirring speed is 200-300 r / min, and the stirring time is 10-30 min.

[0020] Further, in step A1, the alcohol is ethanol or isopropanol, the washing is performed with anhydrous ethanol 2-3 times, the drying temperature is 60-80℃, and the drying time is 4-8h; the mass concentration of the suspension is 5-15g / L, the stirring speed during dispersion is 300-600r / min, and the dispersion time is 30-60min.

[0021] Furthermore, in step A2, the dropping rate of the mixed metal ion solution is 0.5-2.0 mL / min; the temperature of the coordination reaction is 50-60℃, and the reaction time is 1-4 h.

[0022] Furthermore, in step A2, the precipitant is urea; the hydrothermal reaction temperature is 140-180℃, and the reaction time is 8-16h; the amount of urea added is 1.5-3.0 times the total amount of cerium ions and manganese ions, and after adding urea, stir for 10-20min to make it completely dissolved.

[0023] The beneficial effects of this invention are:

[0024] 1. This invention uses melamine-formaldehyde resin as a catalyst support. This support undergoes a condensation reaction to form a three-dimensional network polymer with triazine rings as basic units, and its surface contains abundant polar functional groups such as amino, imino, and hydroxyl groups. Through alcohol reflux pretreatment, the resin can be moderately swollen, exposing more internal pores and surface functional groups, while simultaneously removing unreacted monomers and oligomers from the surface, reducing interference from impurities on the adsorption of metal ions. The three-dimensional interconnected porous structure of melamine-formaldehyde resin provides channels for the diffusion of reactants and products, reducing internal diffusion resistance and improving the utilization rate of active components. Compared with traditional activated carbon supports, it has a richer surface functional group, enabling stronger binding interactions with metal ions; compared with traditional alumina supports, its surface is neutral, making it less likely to initiate acid-catalyzed decomposition side reactions of cumene hydroperoxide.

[0025] 2. This invention utilizes an in-situ coordination method to load cerium-manganese metal ions. A mixed solution of cerium and manganese salts is slowly added dropwise to a pretreated resin suspension. The metal ions undergo a coordination reaction with the functional groups on the resin surface to form stable coordination bonds. Subsequently, a hydrothermal reaction allows the coordinated metal ions to grow in situ into cerium-manganese composite metal oxide nanoparticles. This preparation method fosters a strong interaction between the active component and the support, rather than simple physical adsorption, which helps reduce the loss of active components during the reaction. Simultaneously, the three-dimensional porous structure of the resin provides a spatial confinement effect for the nanoparticles, inhibiting their aggregation and sintering, thus extending the catalyst's lifespan.

[0026] 3. During hydrothermal crystallization, cerium ions and manganese ions form a composite oxide system. Due to the similar ionic radii of manganese and cerium ions, some manganese ions can replace cerium ions in the cerium dioxide lattice to form a doped solid solution. Manganese doping disrupts the lattice charge balance, inducing oxygen vacancies. When the manganese doping level exceeds the solid solution limit, excess manganese precipitates on the cerium dioxide surface as manganese oxide, forming a cerium dioxide-manganese oxide heterojunction. The difference in Fermi levels between the two oxides at the heterojunction interface creates a built-in electric field, accelerating electron transfer between the cerium-manganese redox pairs and increasing the redox reaction rate. Oxygen vacancies, as the main catalytic active centers, have strong electron-accepting capabilities, adsorbing and activating the peroxy bonds of hydrogen molecules and cumene hydroperoxide. They also serve as electron storage and transfer centers, promoting the cycling of the cerium-manganese redox pairs and contributing to improved hydrogenation activity of non-noble metal catalysts. Attached Figure Description

[0027] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] like Figure 1 As shown, a process flow diagram for the catalytic hydrogenation preparation of 2-isopropylbenzeneol is provided.

[0030] In the following examples, comparative examples, and preparation examples, the melamine-formaldehyde resin powder was industrial grade with a purity ≥98.0 wt%; ethanol (CAS No.: 64-17-5) and isopropanol (CAS No.: 67-63-0) were analytical grade with a purity ≥99.7%; cerium nitrate hexahydrate (CAS No.: 10294-41-4) and manganese nitrate tetrahydrate (CAS No.: 20694-39-7) were analytical grade with a purity ≥99.0%; urea (CAS No.: 57-13-6) was analytical grade with a purity ≥99.5%; cumene hydroperoxide (CAS No.: 80-15-9) was industrial grade with a purity ≥98.0 wt%; and anhydrous cumene (CAS No.: 98-82-8) was analytical grade with a purity ≥99.5%.

[0031] Preparation Example 1

[0032] The composite catalyst is prepared by the following steps:

[0033] A1. Take 10g of melamine-formaldehyde resin powder, add 450mL of ethanol to disperse, and reflux at 55℃ and 300r / min for 2h. After reflux, allow it to cool naturally to 28℃, filter, wash twice with anhydrous ethanol, and dry at 70℃ for 6h to obtain the pretreated resin carrier. Take 0.025mol cerium nitrate hexahydrate (about 10.73g) and 0.025mol manganese nitrate tetrahydrate (about 6.32g), dissolve in 100mL of deionized water, and stir at 250r / min for 20min to prepare a mixed solution of metal ions. Take 5g of the pretreated resin carrier, disperse in 500mL of deionized water, and stir at 450r / min for 45min to form a suspension with a mass concentration of 10g / L.

[0034] A2. Under the conditions of stirring speed of 400 r / min and 55℃, the above 100 mL metal ion mixed solution was added dropwise to the suspension at a rate of 1.2 mL / min using a constant pressure dropping funnel, and the coordination reaction was carried out for 2.5 h. 0.11 mol urea (about 6.61 g) was added to the system after the coordination reaction, and the mixture was stirred for 15 min to completely dissolve it. The mixture was then transferred to a 500 mL high-pressure reactor and subjected to a hydrothermal reaction at 160℃ for 12 h. After the hydrothermal reaction, the mixture was filtered, washed 4 times with deionized water until the washing liquid was neutral, and dried at 80℃ for 9 h to obtain the composite catalyst.

[0035] Preparation Example 2

[0036] The composite catalyst is prepared by the following steps:

[0037] A1. Take 10g of melamine-formaldehyde resin powder, add 300mL of isopropanol to disperse, and reflux at 50℃ and 200r / min for 1h. After reflux, allow it to cool naturally to 25℃, filter, wash twice with anhydrous ethanol, and dry at 60℃ for 4h to obtain the pretreated resin carrier. Take 0.012mol cerium nitrate hexahydrate (about 5.15g) and 0.018mol manganese nitrate tetrahydrate (about 5.69g), dissolve in 100mL of deionized water, and stir at 200r / min for 10min to prepare a mixed solution of metal ions. Take 2.5g of the pretreated resin carrier, disperse in 500mL of deionized water, and stir at 300r / min for 30min to form a suspension with a mass concentration of 5g / L.

[0038] A2. Under the conditions of stirring speed of 300 r / min and 50℃, the above 100 mL metal ion mixed solution was added dropwise to the suspension at a rate of 0.5 mL / min using a constant pressure dropping funnel, and the coordination reaction was carried out for 1 h. 0.045 mol urea (about 2.70 g) was added to the system after the coordination reaction, and the mixture was stirred for 10 min to completely dissolve it. The mixture was then transferred to a 500 mL high-pressure reactor and subjected to a hydrothermal reaction at 140℃ for 8 h. After the hydrothermal reaction, the mixture was filtered, washed three times with deionized water until the washing solution was neutral, and dried at 70℃ for 6 h to obtain the composite catalyst.

[0039] Preparation Example 3

[0040] The composite catalyst is prepared by the following steps:

[0041] A1. Take 10g of melamine-formaldehyde resin powder, add 600mL of ethanol to disperse, and reflux at 60℃ and 400r / min for 3h. After reflux, allow it to cool naturally to 30℃, filter, wash three times with anhydrous ethanol, and dry at 80℃ for 8h to obtain the pretreated resin carrier. Dissolve 0.048mol of cerium nitrate hexahydrate (approximately 20.60g) and 0.032mol of manganese nitrate tetrahydrate (approximately 10.11g) in 100mL of deionized water, and stir at 300r / min for 30min to prepare a mixed solution of metal ions. Take 7.5g of the pretreated resin carrier, disperse it in 500mL of deionized water, and stir at 600r / min for 60min to form a suspension with a mass concentration of 15g / L.

[0042] A2. Under the conditions of stirring speed of 500 r / min and 60℃, the above 100 mL metal ion mixed solution was added dropwise to the suspension at a rate of 2.0 mL / min using a constant pressure dropping funnel, and the coordination reaction was carried out for 4 h. 0.24 mol urea (about 14.41 g) was added to the system after the coordination reaction, and the mixture was stirred for 20 min to completely dissolve it. The mixture was then transferred to a 500 mL high-pressure reactor and subjected to a hydrothermal reaction at 180℃ for 16 h. After the hydrothermal reaction, the mixture was filtered, washed 5 times with deionized water until the washing solution was neutral, and dried at 90℃ for 12 h to obtain the composite catalyst.

[0043] Example 1

[0044] A catalytic hydrogenation process for preparing 2-isopropylbenzeneol includes the following steps:

[0045] S1. Take 30g of cumene hydroperoxide and add 70mL of anhydrous cumene. Mix thoroughly at 25℃, stirring speed 220r / min, and stirring time 20min. Take 100g of the above solution and add 0.9g of the composite catalyst prepared in Preparation Example 1. Add both to a 500mL high-pressure reactor. First, purge with nitrogen three times, pressurizing to 0.5MPa each time and stabilizing for 8min before venting. Then purge with hydrogen three times, pressurizing to 0.5MPa each time and stabilizing for 8min before venting. Maintain a stirring speed of 150r / min during the purging process.

[0046] S2. Hydrogen gas is introduced into the reactor to 0.7 MPa, and the temperature is increased to 45°C at a rate of 3°C / min under stirring. Catalytic hydrogenation reaction is carried out for 120 min to obtain a reaction solution containing 2-isopropylbenzene alcohol.

[0047] S3. The reaction solution was filtered at 32°C to separate the composite catalyst. After filtration, it was purified by vacuum distillation (vacuum degree 0.09MPa, distillation temperature 90°C) to obtain 2-isopropylbenzene alcohol.

[0048] Example 2

[0049] A catalytic hydrogenation process for preparing 2-isopropylbenzeneol includes the following steps:

[0050] S1. Take 20g of cumene hydroperoxide and add 80mL of anhydrous cumene. Mix thoroughly at 20℃, stirring speed 150r / min, and stirring time 10min. Take 100g of the above solution and add 0.2g of the composite catalyst prepared in Preparation Example 2. Add both to a 500mL high-pressure reactor. First, purge with nitrogen twice, pressurizing to 0.3MPa each time and stabilizing for 5min before venting. Then purge with hydrogen twice, pressurizing to 0.3MPa each time and stabilizing for 5min before venting. Maintain stirring speed of 100r / min during the purging process.

[0051] S2. Hydrogen gas is introduced into the reactor to 0.5 MPa, and the temperature is increased to 40°C at a rate of 1°C / min under stirring. Catalytic hydrogenation reaction is carried out for 60 min to obtain a reaction solution containing 2-isopropylbenzene alcohol.

[0052] S3. Filter the reaction solution at 25°C to separate the composite catalyst. After filtration, purify the solution by vacuum distillation (0.08 MPa, 80°C) to obtain 2-isopropylbenzene alcohol.

[0053] Example 3

[0054] A catalytic hydrogenation process for preparing 2-isopropylbenzeneol includes the following steps:

[0055] S1. Take 40g of cumene hydroperoxide and add 60mL of anhydrous cumene. Mix thoroughly at 30℃, stirring speed 300r / min, and stirring time 30min. Take 100g of the above solution and add 2.0g of the composite catalyst prepared in Preparation Example 3. Add both to a 500mL high-pressure reactor. First, purge with argon gas 4 times, pressurizing to 0.8MPa each time and stabilizing for 10min before venting. Then purge with hydrogen gas 4 times, pressurizing to 0.8MPa each time and stabilizing for 10min before venting. Maintain a stirring speed of 200r / min during the purging process.

[0056] S2. Hydrogen gas is introduced into the reactor to 1.0 MPa, and the temperature is increased to 50°C at a rate of 5°C / min under stirring. Catalytic hydrogenation reaction is carried out for 180 min to obtain a reaction solution containing 2-isopropylbenzene alcohol.

[0057] S3. The reaction solution was filtered at 40°C to separate the composite catalyst. After filtration, it was purified by vacuum distillation (vacuum degree 0.095MPa, distillation temperature 100°C) to obtain 2-isopropylbenzene alcohol.

[0058] Example 4

[0059] A catalytic hydrogenation process for preparing 2-isopropylbenzeneol includes the following steps:

[0060] S1. Take 25g of cumene hydroperoxide and add 75mL of anhydrous cumene. Mix thoroughly at 22℃, stirring speed 180r / min, and stirring time 15min. Take 100g of the above solution and add 0.5g of the composite catalyst prepared in Preparation Example 1. Add both to a 500mL high-pressure reactor. First, purge with nitrogen twice, pressurizing to 0.4MPa each time and stabilizing for 6min before venting. Then purge with hydrogen three times, pressurizing to 0.4MPa each time and stabilizing for 6min before venting. Maintain a stirring speed of 120r / min during the purging process.

[0061] S2. Hydrogen gas is introduced into the reactor to 0.6 MPa, and the temperature is increased to 42°C at a rate of 2°C / min under stirring. Catalytic hydrogenation reaction is carried out for 90 min to obtain a reaction solution containing 2-isopropylbenzene alcohol.

[0062] S3. The reaction solution was filtered at 28°C to separate the composite catalyst. After filtration, it was purified by vacuum distillation (vacuum degree 0.085MPa, distillation temperature 85°C) to obtain 2-isopropylbenzene alcohol.

[0063] Example 5

[0064] A catalytic hydrogenation process for preparing 2-isopropylbenzeneol includes the following steps:

[0065] S1. Take 35g of cumene hydroperoxide and add 65mL of anhydrous cumene. Mix thoroughly at 28℃, stirring speed 250r / min, and stirring time 25min. Take 100g of the above solution and add 1.4g of the composite catalyst prepared in Preparation Example 2. Add both to a 500mL high-pressure reactor. First, purge with argon gas 3 times, pressurizing to 0.6MPa each time and stabilizing for 9min before venting. Then purge with hydrogen gas 3 times, pressurizing to 0.6MPa each time and stabilizing for 9min before venting. Maintain a stirring speed of 180r / min during the purging process.

[0066] S2. Hydrogen gas is introduced into the reactor to 0.8 MPa, and the temperature is increased to 48°C at a rate of 4°C / min under stirring. Catalytic hydrogenation reaction is carried out for 150 min to obtain a reaction solution containing 2-isopropylbenzene alcohol.

[0067] S3. The reaction solution was filtered at 35°C to separate the composite catalyst. After filtration, it was purified by vacuum distillation (vacuum degree 0.092MPa, distillation temperature 95°C) to obtain 2-isopropylbenzene alcohol.

[0068] Example 6

[0069] A catalytic hydrogenation process for preparing 2-isopropylbenzeneol includes the following steps:

[0070] S1. Take 32g of cumene hydroperoxide and add 68mL of anhydrous cumene. Mix thoroughly at 26℃, stirring speed 220r / min, and stirring time 22min. Take 100g of the above solution and add 1.0g of the composite catalyst prepared in Preparation Example 3. Add both to a 500mL high-pressure reactor. First, purge with nitrogen 4 times, pressurizing to 0.7MPa each time and stabilizing for 7min before venting. Then purge with hydrogen 4 times, pressurizing to 0.7MPa each time and stabilizing for 7min before venting. During the purging process, maintain a stirring speed of 160r / min.

[0071] S2. Hydrogen gas is introduced into the reactor to 0.9 MPa, and the temperature is increased to 46°C at a rate of 3°C / min under stirring. Catalytic hydrogenation reaction is carried out for 130 min to obtain a reaction solution containing 2-isopropylbenzene alcohol.

[0072] S3. The reaction solution was filtered at 30°C to separate the composite catalyst. After filtration, it was purified by vacuum distillation (vacuum degree 0.088MPa, distillation temperature 92°C) to obtain 2-isopropylbenzene alcohol.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 1 is that the composite catalyst prepared in Example 1 is replaced with melamine-formaldehyde resin, while the remaining steps and parameters are completely consistent with those in Example 1.

[0075] Comparative Example 2

[0076] The difference between this comparative example and Example 2 is that the composite catalyst prepared in Example 2 is replaced with cerium nitrate hexahydrate, while the remaining steps and parameters are completely consistent with those in Example 2.

[0077] Comparative Example 3

[0078] The difference between this comparative example and Example 3 is that the composite catalyst prepared in Example 3 is replaced with manganese nitrate tetrahydrate, while the remaining steps and parameters are completely consistent with those in Example 3.

[0079] Comparative Example 4

[0080] The difference between this comparative example and Example 4 is that anhydrous cumene is replaced with toluene, and no composite catalyst is added. The remaining steps and parameters are completely consistent with those of Example 4.

[0081] Take 10.00 mL of each of the reaction solutions prepared in Examples 1-6 and Comparative Examples 1-4, and place them in 100 mL volumetric flasks. Slowly add anhydrous ethanol to 1-2 cm below the mark of the volumetric flask, shake well 10 times, and let stand for 5 min to obtain the sample solution to be tested. At the same time, take 0.500 g of each of the 2-isopropylbenzeneol samples purified in Examples 1-6 and Comparative Examples 1-4, and place them in 100 mL volumetric flasks. Add 50 mL of anhydrous ethanol, shake to dissolve for 5 min, and then dilute to the mark with chromatographic grade anhydrous ethanol. Shake well 8 times and let stand for 3 min for later use.

[0082] Weigh 0.100 g of cumene hydrogen peroxide standard and 0.100 g of 2-isopropylbenzene alcohol standard, and place them in two 100 mL volumetric flasks respectively. Add 50 mL of anhydrous ethanol to each flask, shake to dissolve for 8 min, and then dilute to the mark with chromatographic grade anhydrous ethanol. Shake well and let stand for 4 min to obtain a 1.0 mg / mL cumene hydrogen peroxide standard stock solution and a 1.0 mg / mL 2-isopropylbenzene alcohol standard stock solution. Using a 5 mL pipette, transfer 0.1 mL, 0.2 mL, 0.5 mL, 1.0 mL, and 2.0 mL of each of the two mother solutions into ten 10 mL volumetric flasks. Dilute to the mark with anhydrous ethanol, shake well, and let stand for 3 min to obtain a series of cumene hydroperoxide standard solutions with concentrations of 0.01 mg / mL, 0.02 mg / mL, 0.05 mg / mL, 0.10 mg / mL, and 0.20 mg / mL, as well as a corresponding series of 2-isopropylbenzene alcohol standard solutions. Adjust the gas chromatograph and set the following conditions: column temperature: 150℃, detector temperature: 250℃, injection port temperature: 200℃, carrier gas: nitrogen, flow rate: 1.0 mL / min, injection volume: 1 μL. Inject the standard solutions sequentially, three times for each concentration, with a 2-min interval between each injection. Record the peak area for each detection to obtain the standard curve.

[0083] The gas chromatograph was used for detection under the conditions described above. Each sample was injected three times, with an injection volume of 1 μL and an injection interval of 3 min. The peak areas of cumene hydroperoxide and 2-isopropylbenzene alcohol were recorded for each detection. The conversion rate of cumene hydroperoxide, the selectivity of 2-isopropylbenzene alcohol, and the yield of 2-isopropylbenzene alcohol were calculated. The calculation method is as follows:

[0084] Conversion rate of cumene hydroperoxide (%) = (mass of cumene hydroperoxide before reaction - mass of cumene hydroperoxide remaining after reaction) / mass of cumene hydroperoxide before reaction × 100%.

[0085] 2-Isopropylbenzene alcohol selectivity (%) = mass of cumene hydrogen peroxide consumed in the formation of 2-isopropylbenzene alcohol / total mass of cumene hydrogen peroxide consumed in the reaction × 100%.

[0086] 2-Isopropylbenzene alcohol yield (%) = actual mass of 2-isopropylbenzene alcohol obtained / theoretical mass of 2-isopropylbenzene alcohol completely converted from cumene hydroperoxide × 100%.

[0087] The results are shown in Table 1:

[0088] Table 1. Experimental results of different embodiments and comparative examples:

[0089]

[0090] As shown in Table 1, Examples 1-6 exhibited better performance in terms of cumene hydroperoxide conversion, 2-isopropylbenzene alcohol selectivity, and 2-isopropylbenzene alcohol yield, while Comparative Examples 1-4 showed relatively poor performance. Examples 1-6 all used the composite catalyst prepared in the preparation example. This composite catalyst used melamine-formaldehyde resin as a support and loaded cerium-manganese metal ions via in-situ coordination. The melamine-formaldehyde resin underwent a condensation reaction to form a three-dimensional network polymer with triazine rings as basic units, and its surface contained abundant polar functional groups such as amino, imino, and hydroxyl groups. Through alcohol reflux pretreatment, the resin swelled moderately, exposing more internal pores and surface functional groups, while removing unreacted monomers and oligomers from the surface, reducing the interference of impurities on the adsorption of metal ions. Its three-dimensional interconnected porous structure provides channels for the diffusion of reactants and products, reducing internal diffusion resistance and improving the utilization rate of active components. Compared with traditional activated carbon carriers, it has a richer surface functional group, which can form a stronger binding effect with metal ions; compared with traditional alumina carriers, its surface is neutral and is less likely to trigger the acid-catalyzed decomposition side reaction of cumene hydroperoxide.

[0091] In-situ coordination loading of cerium-manganese metal ions was employed, where the metal ions coordinated with functional groups on the resin surface to form stable coordination bonds. Subsequently, a hydrothermal reaction allowed the coordinated metal ions to grow in situ into cerium-manganese composite metal oxide nanoparticles. This preparation method fosters a strong interaction between the active component and the support, rather than simple physical adsorption, which helps reduce the loss of active components during the reaction. Simultaneously, the three-dimensional porous structure of the resin provides a spatial confinement effect for the nanoparticles, inhibiting agglomeration and sintering, thus extending the catalyst's lifespan.

[0092] During hydrothermal crystallization, cerium ions and manganese ions form a composite oxide system. Some manganese ions can replace cerium ions and enter the cerium dioxide lattice to form a doped solid solution. Manganese ion doping disrupts the lattice charge balance and induces oxygen vacancies. When the manganese doping amount exceeds the solid solution limit, excess manganese precipitates on the cerium dioxide surface as manganese oxide, forming a cerium dioxide-manganese oxide heterojunction. The difference in Fermi levels between the two oxides at the heterojunction interface creates a built-in electric field, which accelerates electron transfer between the cerium-manganese redox pairs and increases the redox reaction rate. Oxygen vacancies, as the main catalytic active centers, have strong electron accepting capacity. They can adsorb and activate the peroxy bonds of hydrogen molecules and cumene hydroperoxide, and also serve as electron storage and transfer centers, promoting the cycling of the cerium-manganese redox pairs and contributing to improved hydrogenation activity of non-noble metal catalysts.

[0093] In Comparative Example 1, the composite catalyst was replaced with melamine-formaldehyde resin. Although the resin support has certain porous structure and other characteristics, it lacks the active component of cerium-manganese composite metal oxide. Without the catalytic effect of the active component, the hydrogenation reaction of cumene hydroperoxide cannot be effectively promoted, resulting in low conversion rate of cumene hydroperoxide, low selectivity of 2-isopropylbenzene alcohol, and low yield.

[0094] In Comparative Example 2, the composite catalyst was replaced with cerium nitrate hexahydrate. The single cerium salt did not form a composite oxide system with manganese, thus failing to generate manganese ion-induced oxygen vacancies and structures such as cerium dioxide-manganese oxide heterojunctions. These special structures play a crucial role in enhancing redox reaction rates and catalytic activity; their absence resulted in poor catalytic performance, with all indicators significantly lower than in the examples.

[0095] In Comparative Example 3, when the composite catalyst was replaced with manganese nitrate tetrahydrate, the single manganese salt still failed to form the cerium-manganese composite oxide with its unique structure and properties. Without the synergistic effect of cerium and its corresponding structural advantages, the reaction could not be effectively promoted, resulting in low conversion, selectivity, and yield.

[0096] Comparative Example 4 replaced anhydrous cumene with toluene and did not add a composite catalyst. The reactivity and selectivity of toluene with cumene hydroperoxide were different from those of anhydrous cumene. In addition, without the presence of a catalyst, the reaction could not provide active centers or lower the activation energy, making the reaction difficult to proceed. The conversion rate of cumene hydroperoxide was extremely low, and the selectivity and yield of 2-isocumene alcohol were also very low.

[0097] In summary, this invention utilizes melamine-formaldehyde resin as a carrier, and after alcohol reflux pretreatment, prepares a composite catalyst by supporting cerium-manganese composite metal oxides in situ using a coordination-hydrothermal method. By leveraging the porous structure and abundant functional groups of the carrier, as well as the unique structures such as oxygen vacancies and heterojunctions formed by the cerium-manganese composite system, the conversion rate, selectivity, and yield of the catalytic hydrogenation reaction of cumene peroxide are significantly improved.

[0098] In the description of this specification, the reference to terms such as "embodiment," "various embodiments," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or preparation example is included in at least one embodiment of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments.

[0099] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A process for the catalytic hydrogenation of 2-isopropylbenzeneol, characterized in that, Includes the following steps: S1. Add the cumene solution of hydrogen peroxide and the composite catalyst to a high-pressure reactor, and replace the air in the reactor with inert gas and hydrogen. S2. Hydrogen gas is introduced into the reactor to the set pressure, and the temperature is raised to the reaction temperature under stirring to carry out the catalytic hydrogenation reaction, and a reaction solution containing 2-isopropylbenzene alcohol is obtained. S3. Separate and purify the reaction solution to obtain 2-isopropylbenzene alcohol; Among them, the composite catalyst is a composite catalyst in which cerium and manganese composite metal oxides are supported on melamine-formaldehyde resin. It is prepared by a process that involves in-situ coordination of cerium and manganese metal ions with functional groups on the surface of melamine-formaldehyde resin, followed by hydrothermal crystallization growth. Specifically, the composite catalyst in step S1 is prepared by the following steps: A1. Melamine-formaldehyde resin powder is dispersed in alcohol and refluxed, then filtered, washed and dried to obtain a pretreated resin carrier. Cerium salt and manganese salt are dissolved in water to obtain a mixed solution of metal ions. The pretreated resin carrier is dispersed in water to form a suspension. A2. Under stirring and heating conditions, a mixed solution of metal ions is added dropwise to a suspension to carry out a coordination reaction. A precipitant is added to the system after the coordination reaction, and the mixture is transferred to a high-pressure reactor for a hydrothermal reaction. The product after the hydrothermal reaction is filtered, washed, and dried to obtain a composite catalyst.

2. The catalytic hydrogenation process for preparing 2-isopropylbenzeneol according to claim 1, characterized in that, In step S1, the mass fraction of cumene hydroperoxide in the cumene hydroperoxide solution is 20-40%, and the amount of composite catalyst added is 1-5% of the mass of the cumene hydroperoxide.

3. The catalytic hydrogenation process for preparing 2-isopropylbenzeneol according to claim 1, characterized in that, The process of replacing the air inside the reactor with inert gas and hydrogen in step S1 includes: first replacing it with inert gas 2-4 times, pressurizing it to 0.3-0.8 MPa each time and then venting it; then replacing it with hydrogen 2-4 times, pressurizing it to 0.3-0.8 MPa each time and then venting it.

4. The catalytic hydrogenation process for preparing 2-isopropylbenzeneol according to claim 1, characterized in that, In step S2, the pressure is set to 0.5MPa-1.0MPa, the reaction temperature for catalytic hydrogenation is 40-50℃, and the reaction time is 60-180min.

5. The catalytic hydrogenation process for preparing 2-isopropylbenzeneol according to claim 1, characterized in that, In step A1, the mass-to-volume ratio of melamine-formaldehyde resin powder to alcohol solvent is 1 g:(30-60) mL; the reflux treatment temperature is 50-60℃ and the time is 1-3 h.

6. The catalytic hydrogenation process for preparing 2-isopropylbenzeneol according to claim 2, characterized in that, In step A1, the cerium salt is cerium nitrate, the manganese salt is manganese nitrate, and the molar ratio of cerium to manganese is (0.4-0.6):(0.6-0.4); in the mixed solution of metal ions, the total concentration of cerium ions and manganese ions is 0.3-0.8 mol / L.

7. The catalytic hydrogenation process for preparing 2-isopropylbenzeneol according to claim 1, characterized in that, In step A2, the dropping rate of the mixed metal ion solution is 0.5-2.0 mL / min; the temperature of the coordination reaction is 50-60℃, and the reaction time is 1-4 h.

8. The catalytic hydrogenation process for preparing 2-isopropylbenzeneol according to claim 1, characterized in that, In step A2, the precipitant is urea; the hydrothermal reaction temperature is 140-180℃, and the reaction time is 8-16h.

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