Method for preparing pyrrolidone compound by reductive amination of levulinic acid

Abstract

The invention belongs to the technical field of catalytic synthesis, and particularly relates to a method for preparing pyrrolidone compounds by reductive amination of levulinic acid. The method for preparing the pyrrolidone compound by reductive amination of levulinic acid comprises the following steps: adding levulinic acid, an amine compound, an organic solvent and a Pt / CeO2 catalyst into a reactor, carrying out reductive amination reaction under the conditions of hydrogen and 20-30 DEG C, and collecting a reaction product to obtain the pyrrolidone compound. The key point of the invention is that ascorbic acid and a cerium source are introduced to carry out a solid phase-oxygen-containing atmosphere calcination process to prepare an oxygen vacancy-rich CeO2 carrier, then Pt is loaded on the CeO2 carrier by a simple wet chemical reduction method, and the prepared Pt / CeO2 catalyst, levulinic acid, an amine compound, an organic solvent and hydrogen construct a catalytic reaction system. The pyrrolidone compound can be synthesized by high-selectivity catalytic reduction and amination of levulinic acid under the conditions of normal temperature and normal pressure.

Description

Technical Field

[0001] This invention belongs to the field of catalytic synthesis technology, specifically relating to a method for preparing pyrrolidone compounds by reducing and amination of levulinic acid. Background Technology

[0002] The co-reactivity of the carbonyl and carboxyl groups in levulinic acid (LA) makes it an important precursor for the synthesis of high-value-added chemicals. Among them, N-substituted-5-methyl-2-pyrrolidone, due to its unique five-membered cyclic amide structure, has wide applications in solvents, surfactants, and pharmaceutical intermediates. For example, its derivatives can serve as environmentally friendly aprotic polar solvents to replace neurotoxic N-methylpyrrolidone and act as key intermediates in the synthesis of antitumor drugs (such as leupram).

[0003] Currently, the synthesis of N-substituted pyrrolidones mainly involves the reductive amination reaction of LA with amine compounds, a reaction that is highly dependent on efficient hydrogen sources and catalyst systems. While formic acid (FA) and organosilanes can provide active hydrogen, the former is highly corrosive and requires high-temperature conditions (>130°C), while the latter is expensive and prone to generating byproducts. In contrast, hydrogen (H2) has greater potential for industrial application as a clean hydrogen source. Existing catalytic systems are mainly divided into homogeneous and heterogeneous types. Homogeneous catalysts (such as Ir complexes (ChemSusChem, 2017, 10(21): 4150-4154)) have high activity, but there are difficulties in catalyst separation and recovery; heterogeneous non-precious metal catalysts (such as Cu and Ni (Applied Catalysis B, 2021, 292:14; ACS Catalysis, 2024, 15(1): 91-104)) exhibit excellent hydrogenation performance, but usually require high catalyst dosage and harsh reaction conditions (80-130℃, 6-14h). In contrast, heterogeneous noble metal catalysts (such as Pt, Ru, Pd (ACS Catalysis, 2014, 4(9): 3045-3050; J. Am. Chem. Soc., 2019, 141(9):4002-4009; J. Catal., 2020, 383: 206-214)) have attracted widespread attention due to their high activity, low energy consumption and reusability.

[0004] However, existing catalytic systems generally require high reaction temperatures (above 80℃ or even above 130℃) and / or long reaction times to achieve high (≥90%) pyrrolidone yields. Furthermore, in high-concentration levulinic acid systems, even increasing the reaction temperature or extending the reaction time cannot achieve high pyrrolidone yields. Therefore, developing a highly efficient catalyst capable of achieving efficient reductive amination of propionyl acetate at ambient temperature and pressure to obtain high pyrrolidone yields will greatly promote the large-scale industrialization of this reaction. Summary of the Invention

[0005] The purpose of this invention is to address the fact that existing reaction systems for the reductive amination of levulinic acid to prepare pyrrolidone still require relatively high reaction temperatures (above 80°C or even above 130°C) to achieve high pyrrolidone yields. This invention provides a method for the reductive amination of levulinic acid to prepare pyrrolidone compounds, which can achieve efficient reductive amination of propionyl acetate at ambient temperatures of 20-30°C and obtain high pyrrolidone compound yields (above 85%). Furthermore, under the same mild conditions, it can catalyze the preparation of pyrrolidone compounds from high concentrations of LA (≥10 wt%).

[0006] Specifically, this invention provides a method for preparing pyrrolidone compounds by reducing and amination of levulinic acid, comprising: adding levulinic acid, an amine compound, an organic solvent, and a Pt / CeO2 catalyst to a reactor, and carrying out a reducing and amination reaction under hydrogen atmosphere and at 20-30°C, collecting the reaction product to obtain the pyrrolidone compound; the Pt / CeO2 catalyst is prepared by the following method: S1. Mixing a cerium source with ascorbic acid and then heat-treating it under an oxygen-containing atmosphere, the resulting Ce oxide is denoted as the CeO2 support; S2. The CeO2 support is impregnated with platinum salt and then reduced to load Pt nanoparticles onto the CeO2 support. The reaction product is collected to obtain the Pt / CeO2 catalyst. The amine compound has the general chemical formula: R-NH2, wherein R is selected from any one of the following: C1-C8 alkyl, C3-C8 cycloalkyl, hydroxyl group substituted with C1-C8 alkylene, C1-C3 alkoxy group substituted with C1-C8 alkylene, unsubstituted C6-C20 aryl, and C6-C12 aralkyl group substituted with methyl or halogen atoms.

[0007] In a preferred embodiment, the Pt content in the Pt / CeO2 catalyst is 1~3 wt%.

[0008] In a preferred embodiment, in step S1, the molar ratio of Ce in the cerium source to ascorbic acid is 1:(0.1~0.3).

[0009] In a preferred embodiment, the cerium source is selected from at least one of cerium nitrate, cerium acetate, cerium oxalate, cerium chloride, and cerium sulfate.

[0010] In a preferred embodiment, the heat treatment conditions include a temperature of 400~600℃ and a time of 3~5h.

[0011] In a preferred embodiment, the impregnation and reduction processes in step S2 are as follows: the CeO2 support is mixed with platinum salt and water and then impregnated. The resulting mixture is then mixed with a reducing agent to carry out a reduction reaction. The final reaction product is the Pt / CeO2 catalyst.

[0012] In a preferred embodiment, the amount of platinum salt used is such that the Pt content in the Pt / CeO2 catalyst is 1~3wt%.

[0013] In a preferred embodiment, the platinum salt is chloroplatinic acid and / or platinum chloride.

[0014] In a preferred embodiment, the conditions for the impregnation treatment include: a temperature of 15~30°C and a time of 1~3 hours.

[0015] In a preferred embodiment, step S2 further includes adding a dispersant; the dispersant is polyvinylpyrrolidone.

[0016] In a preferred embodiment, the reducing agent is sodium borohydride.

[0017] In a preferred embodiment, the molar ratio of the reducing agent to Pt in the platinum salt is (10~20):1.

[0018] In a preferred embodiment, the conditions for the reduction reaction include: a temperature of 15~30°C and a time of 3~5 hours.

[0019] In a preferred embodiment, the hydrogen pressure during the reductive amination reaction is 0.1~0.3 MPa.

[0020] In a preferred embodiment, the molar ratio of levulinic acid to Pt in the Pt / CeO2 catalyst is (250~1000):1.

[0021] In a preferred embodiment, the molar ratio of levulinic acid to the amine compound is 1:(1~3).

[0022] In a preferred embodiment, the amine compound is selected from at least one of n-propylamine, isopropylamine, n-butylamine, n-octylamine, n-propanolamine, isopropanolamine, 3-methoxy-1-propylamine, cyclohexylamine, aniline, benzylamine, 4-methylbenzylamine, 3-methylbenzylamine, 2-methylbenzylamine, 4-chlorobenzylamine, 3-chlorobenzylamine, and 2-chlorobenzylamine.

[0023] In a preferred embodiment, the organic solvent is selected from at least one of methanol, ethanol, isopropanol, and dimethyl sulfoxide.

[0024] Beneficial Effects: The key to this invention lies in preparing an oxygen-rich CeO2 support by introducing ascorbic acid (VC) and a cerium source through a solid-phase oxygen-containing atmosphere calcination process. Then, Pt is loaded onto the CeO2 support via a simple wet chemical reduction method. The resulting Pt / CeO2 catalyst, together with levulinic acid, amine compounds, organic solvents, and hydrogen, forms a catalytic reaction system. This system enables highly selective catalytic reduction of amination of levulinic acid to synthesize pyrrolidone compounds (N-substituted-5-methyl-2-pyrrolidone, abbreviated as BMP) under ambient temperature and pressure (20~30℃). Compared to the complex reaction conditions requiring high temperature and high pressure in existing processes, the reaction system of this invention is more environmentally friendly and milder, achieving a BMP yield of over 95% and a product formation rate of up to 476.0 mol BMP·mol Pt. -1 ·h -1 Furthermore, under the same mild reaction conditions, highly selective reductive amination of high concentrations of LA (up to 11.4 wt%) can be achieved, with BMP yields exceeding 90%. The method for preparing pyrrolidone compounds by the reductive amination of levulinic acid provided by this invention solves the problem that current catalysts have too low catalytic efficiency under mild reaction conditions and cannot be used for the efficient and selective reductive amination of high concentrations of LA to prepare pyrrolidone compounds. This method has significant implications for the large-scale production of pyrrolidone compounds. Attached Figure Description

[0025] Figure 1 These are high-resolution TEM images and particle size distribution results of the Pt(2.0) / CeO2-0.1VC-400 catalyst prepared in Example 1 and the Pt(2.0) / CeO2-400 catalyst prepared in Comparative Example 5.

[0026] Figure 2 The diagram (a) and reactor photograph (b) show the reaction route (a) for the reductive amination of levulinic acid to produce N-substituted-5-methyl-2-pyrrolidone in Example 1.

[0027] Figure 3The X-ray diffraction (XRD) patterns (a) and electron paramagnetic resonance (EPR) results (b) of Pt(2.0) / CeO2-0.1VC-400 catalyst (Example 1), Pt(2.0) / CeO2-400 catalyst (Comparative Example 5), CeO2-400 (Comparative Example 5), and CeO2-0.1VC-400 (Comparative Example 2) are shown.

[0028] Figure 4 The N2 adsorption-desorption isotherm results are shown for Pt(2.0) / CeO2-0.1VC-400 catalyst (Example 1), Pt(2.0) / CeO2-400 catalyst (Comparative Example 5), CeO2-400 (Comparative Example 5), and CeO2-0.1VC-400 (Comparative Example 2).

[0029] Figure 5 These are scanning electron microscope (SEM) images of Pt(2.0) / CeO2-0.1VC-400 catalyst (Example 1), Pt(2.0) / CeO2-400 catalyst (Comparative Example 5), CeO2-400 (Comparative Example 5), and CeO2-0.1VC-400 (Comparative Example 2) (scale bars in the images are 1 μm or 2 μm). Detailed Implementation

[0030] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Furthermore, unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present invention.

[0031] The method for preparing pyrrolidone compounds by reducing levulinic acid provided by this invention includes: adding levulinic acid, an amine compound, an organic solvent, and a Pt / CeO2 catalyst to a reactor, carrying out a reducing amination reaction under hydrogen atmosphere and at 20-30°C, and collecting the reaction product to obtain the pyrrolidone compound. The temperature of the reducing amination reaction can be 20°C, 22°C, 25°C, 28°C, 30°C, or any value between them.

[0032] The Pt / CeO2 catalyst was prepared by the following method: S1. A cerium source was mixed with ascorbic acid and then heat-treated in an oxygen-containing atmosphere to obtain Ce oxide, which was designated as the CeO2 support; S2. The CeO2 support was impregnated with platinum salt and then reduced to load Pt nanoparticles onto the CeO2 support. The reaction products were collected to obtain the Pt / CeO2 catalyst.

[0033] The amine compounds have the general chemical formula: R-NH2, wherein R is selected from any one of C1-C8 alkyl groups, C3-C8 cycloalkyl groups, hydroxyl groups substituted with C1-C8 alkylene groups, C1-C3 alkoxy groups substituted with C1-C8 alkylene groups, unsubstituted C6-C20 aryl groups, and C6-C12 aralkyl groups substituted with methyl or halogen atoms. The C1-C8 alkyl groups include straight-chain alkyl groups and branched-chain alkyl groups, and specific examples include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, isobutyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, 1,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, n-heptyl, and n-octyl. Specific examples of C3-C8 cycloalkyl groups include, but are not limited to, any one of cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, bicyclo[2.2.1]heptyl, and cyclooctyl. Specific examples of hydroxyl groups substituted with C1-C8 alkylene groups include, but are not limited to, any one of -CH2-OH, -CH2CH2-OH, -CH(OH)CH3, -(CH2)3-OH, -(CH2)4-OH, -(CH2)5-OH, -(CH2)6-OH, -(CH2)7-OH, and -(CH2)8-OH. Specific examples of C1-C3 alkoxy groups substituted with C1-C8 alkylene groups include, but are not limited to, any one of: -CH2-O-CH3, -CH2CH2-O-CH3, -(CH2)3-O-CH3, -(CH2)4-O-CH3, -(CH2)5-O-CH3, -(CH2)6-O-CH3, -(CH2)7-O-CH3, -(CH2)8-O-CH3, -CH2CH2CH2-O-CH2CH3, and -CH2CH2CH2-O-CH2CH2CH3. Specific examples of unsubstituted C6-C20 aryl groups include, but are not limited to, at least one of: phenyl, biphenyl, triphenyl, naphthyl, anthracene, phenanthryl, pyrene, and benzo[a]pyrene. Specific examples of methyl-substituted C6-C12 aralkyl groups include, but are not limited to (Ph represents benzene ring): any one of -CH2Ph-CH3, -CH2CH2Ph-CH3, -(CH2)3Ph-CH3, -(CH2)4Ph-CH3, and -CH2CH(CH3)CH2Ph-CH3. The substitution site of the methyl group on the benzene ring is not specifically limited and can be any site other than the methylene linkage site.Specific examples of C6-C12 aralkyl groups substituted with halogen atoms include, but are not limited to (Ph represents benzene ring): any one of -CH2Ph-Cl, -CH2Ph-Br, -CH2Ph-I, -CH2CH2Ph-Cl, -(CH2)3Ph-Cl, -(CH2)4Ph-Cl, and -CH2CH(CH3)CH2Ph-Cl. The substitution site of the halogen atom on the benzene ring is not specifically limited and can be any site other than the methylene linkage site. The halogen atom can be selected from any one of chlorine, iodine, and bromine atoms.

[0034] In this invention, the Pt content in the Pt / CeO2 catalyst is preferably 1~3 wt%, such as 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, or any value between them. This provides a comprehensive advantage in catalytic activity and stability because the appropriate Pt loading ensures a uniformly dispersed metal-support interface structure, fully exposing active sites and promoting H2 activation, while avoiding agglomeration caused by excessively high Pt content, thus achieving efficient and stable catalytic performance.

[0035] In this invention, in step S1, the molar ratio of Ce in the cerium source to ascorbic acid is preferably 1:(0.1~0.3), such as 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, or any ratio between them. This facilitates control of oxygen vacancy generation and maintains Ce... 3+ The structural advantage of its stable existence lies in the fact that ascorbic acid can act as a mild reducing agent within this ratio range, partially reducing Ce. 4+ For Ce 3+ The formation of a suitable amount of oxygen vacancies in the crystal lattice is beneficial for obtaining a CeO2 support with a complete structure and controllable defects. When the amount of ascorbic acid is higher or lower than the preferred ratio range, it may lead to problems such as destruction of the crystal structure or insufficient generation of oxygen vacancies, which will affect the dispersion of the subsequent Pt metal active components and the stability of the interface structure, and will not be conducive to further improvement of catalytic activity.

[0036] In this invention, the cerium source can be any compound that can provide a CeO2 support obtained by heat treatment of cerium element and ascorbic acid in an oxygen-containing atmosphere. Specific examples include, but are not limited to, at least one of cerium nitrate, cerium acetate, cerium oxalate, cerium chloride, and cerium sulfate.

[0037] In this invention, the heat treatment conditions preferably include: a temperature of 400~600℃, such as 400℃, 450℃, 500℃, 550℃, 600℃, or any value between them. This temperature range offers advantages in terms of good process stability and excellent overall performance because the CeO2 support crystal structure can fully develop within this temperature range, while avoiding excessive grain growth due to excessively high temperatures or incomplete precursor decomposition due to excessively low temperatures, thus obtaining a support material with stable structure and high surface activity; and a time of 3~5h, such as 3h, 3.5h, 4h, 4.5h, 5h, or any value between them. From an economic perspective, the oxygen-containing atmosphere is particularly preferably an air atmosphere.

[0038] In this invention, the impregnation and reduction processes in step S2 can be as follows: the CeO2 support is mixed with platinum salt and water and then impregnated. The resulting mixture is then mixed with a reducing agent to carry out a reduction reaction. The final reaction product is the Pt / CeO2 catalyst.

[0039] In this invention, the amount of platinum salt used is preferably such that the Pt content in the Pt / CeO2 catalyst is 1~3 wt%. The platinum salt is preferably chloroplatinic acid and / or platinum chloride.

[0040] In this invention, the conditions for the impregnation treatment preferably include: it can be carried out at room temperature, and the temperature can be any value among 15℃, 18℃, 20℃, 22℃, 25℃, 28℃, and 30℃; the time is 1~3h, such as 1h, 1.5h, 2h, 2.5h, 3h, or any value between them.

[0041] In this invention, step S2, the impregnation process preferably further includes adding a dispersant, that is, mixing the CeO2 support with platinum salt, water, and the dispersant before impregnation. The dispersant is preferably polyvinylpyrrolidone. The mixing order of the CeO2 support, platinum salt, water, and dispersant is not specifically limited; they can be added and mixed simultaneously, or partially mixed and dispersed first, and then the remaining portion added for further mixing. In a specific embodiment, the impregnation process is as follows: the CeO2 support is mixed uniformly with water and the dispersant, and then platinum salt is added for impregnation. This impregnation method is beneficial for further improving the uniformity of Pt loading on the CeO2 support.

[0042] In this invention, the reducing agent is preferably sodium borohydride. The molar ratio of the reducing agent to Pt in the platinum salt is preferably (10~20):1, such as 10:1, 12:1, 15:1, 18:1, 20:1, or any ratio between them.

[0043] In this invention, the preferred conditions for the reduction reaction include: it can be carried out at room temperature, and the temperature can be any value among 15℃, 18℃, 20℃, 22℃, 25℃, 28℃, and 30℃; the time is 3~5h, such as 3h, 3.5h, 4h, 4.5h, 5h, or any value between them.

[0044] In this invention, the hydrogen pressure during the reductive amination reaction is preferably 0.1~0.3 MPa, such as 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa or any value between them.

[0045] In this invention, the molar ratio of levulinic acid to Pt in the Pt / CeO2 catalyst is preferably (250~1000):1, such as 250:1, 300:1, 400:1, 500:1, 600:1, 700:1, 800:1, 900:1, 1000:1 or any ratio between them.

[0046] In this invention, the molar ratio of levulinic acid to amine compounds is preferably 1:(1~3), such as 1:1, 1:1.5, 1:2, 1:2.5, 1:3 or any ratio therebetween.

[0047] In this invention, the amine compound can be any compound having the general chemical formula R-NH2, and specific examples include, but are not limited to, at least one of the following: n-propylamine, isopropylamine, n-butylamine, n-octylamine, n-propanolamine, isopropanolamine, 3-methoxy-1-propylamine, cyclohexylamine, aniline, benzylamine, 4-methylbenzylamine, 3-methylbenzylamine, 2-methylbenzylamine, 4-chlorobenzylamine, 3-chlorobenzylamine, and 2-chlorobenzylamine.

[0048] In this invention, specific examples of the organic solvent include, but are not limited to, at least one of methanol, ethanol, isopropanol, and dimethyl sulfoxide.

[0049] The present invention will be described in detail below through specific embodiments. These embodiments are intended to explain the invention and should not be construed as limiting it. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0050] Example 1 (1) Preparation of Pt(2.0) / CeO2-0.1VC-400 catalyst: 4.3422g Ce(NO3)3·6H2O (10mmol) and 0.1761g ascorbic acid (VC, 1mmol) were placed in a mortar and ground by hand for 5min until they were mixed evenly. Then the solid mixture was placed in a muffle furnace and heated to 400℃ at a heating rate of 5℃ / min under air atmosphere and maintained for 4h to obtain CeO2 support, denoted as CeO2-0.1VC-400; 0.06 g of polyvinylpyrrolidone was dissolved in 30 mL of deionized water, and then 0.3 g of CeO2-0.1VC-400 support was added and stirred continuously for 20 min. Next, 10 mL of an aqueous solution containing 0.0170 g of H2PtCl6·6H2O was added dropwise to the mixture and stirred for 1 h. Then, 10 mL of NaBH4 aqueous solution (NaBH4 / Pt molar ratio of 10) was slowly added and stirred continuously for 3 h. The solid mixture was collected by filtration and washed three times each with hot water (95 °C) and anhydrous ethanol. Finally, the solid mixture was dried under vacuum at 60 °C for 12 h to obtain the Pt / CeO2 catalyst, denoted as Pt(2.0) / CeO2-0.1VC-400, with a Pt content of approximately 2 wt%.

[0051] (2) Add 0.1161 g levulinic acid (1 mmol), 0.1072 g benzylamine (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Pt(2.0) / CeO2-0.1VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 1 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0052] Example 2 (1) Preparation of Pt(2.0) / CeO2-0.2VC-400 catalyst: The catalyst was prepared according to step (1) in Example 1, except that the amount of ascorbic acid used was 0.3522 g (2 mmol), and the other conditions were the same as step (1) in Example 1. Thus, Pt / CeO2 catalyst was prepared, denoted as Pt(2.0) / CeO2-0.2VC-400, and the Pt content in the catalyst was about 2 wt%.

[0053] (2) Add 0.1161g levulinic acid, 0.1072g benzylamine and 2mL methanol to a two-necked flask (25mL), then add 0.0241g Pt(2.0) / CeO2-0.2VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25℃ and stir vigorously at 500rpm for 2h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0054] Example 3 (1) Preparation of Pt(2.0) / CeO2-0.3VC-400 catalyst: The catalyst was prepared according to step (1) in Example 1, except that the amount of ascorbic acid used was 0.5283 g (3 mmol), and the other conditions were the same as step (1) in Example 1. Thus, Pt / CeO2 catalyst was prepared, denoted as Pt(2.0) / CeO2-0.3VC-400, and the Pt content in the catalyst was about 2 wt%.

[0055] (2) Add 0.1161g levulinic acid, 0.1072g benzylamine and 2mL methanol to a two-necked flask (25mL), then add 0.0241g Pt(2.0) / CeO2-0.3VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25℃ and stir vigorously at 500rpm for 3h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0056] Example 4 (1) Preparation of Pt(2.0) / CeO2-0.1VC-500 catalyst: The catalyst was prepared according to step (1) in Example 1, except that 4.3422g Ce(NO3)3·6H2O (10mmol) and 0.1761g ascorbic acid (1mmol) were placed in a mortar and manually ground for 5min until they were mixed evenly. Then the solid mixture was placed in a muffle furnace and heated to 500℃ at a heating rate of 5℃ / min under air atmosphere and maintained for 4h to obtain CeO2 support, denoted as CeO2-0.1VC-500. The other conditions were the same as step (1) in Example 1. Thus, Pt / CeO2 catalyst was prepared, denoted as Pt(2.0) / CeO2-0.1VC-500, and the Pt content in the catalyst was about 2wt%.

[0057] (2) Add 0.1161g levulinic acid, 0.1072g benzylamine and 2mL methanol to a double-necked flask (25mL), then add 0.0241g Pt(2.0) / CeO2-0.1VC-500 catalyst, seal the double-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the double-necked flask in an oil bath at 25℃ and stir vigorously at 500rpm for 1h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0058] Example 5 (1) Preparation of Pt(2.0) / CeO2-0.1VC-600 catalyst: The catalyst was prepared according to step (1) in Example 1, except that 4.3422g Ce(NO3)3·6H2O (10mmol) and 0.1761g ascorbic acid (1mmol) were placed in a mortar and ground by hand for 5min until they were mixed evenly. Then the solid mixture was placed in a muffle furnace and heated to 600℃ at a heating rate of 5℃ / min under air atmosphere and maintained for 4h to obtain CeO2 support, denoted as CeO2-0.1VC-600. The other conditions were the same as step (1) in Example 1. Thus, Pt / CeO2 catalyst was prepared, denoted as Pt(2.0) / CeO2-0.1VC-600, and the Pt content in the catalyst was about 2wt%.

[0059] (2) Add 0.1161g levulinic acid, 0.1072g benzylamine and 2mL methanol to a two-necked flask (25mL), then add 0.0241g Pt(2.0) / CeO2-0.1VC-600 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25℃ and stir vigorously at 500rpm for 1h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0060] Example 6 (1) Preparation of Pt(1.0) / CeO2-0.1VC-400 catalyst: The catalyst was prepared according to step (1) in Example 1, except that 10 mL of aqueous solution containing 0.0085 g H2PtCl6·6H2O was added dropwise. All other conditions were the same as step (1) in Example 1. Thus, Pt / CeO2 catalyst was prepared, denoted as Pt(1.0) / CeO2-0.1VC-400, and the Pt content in the catalyst was about 1 wt%.

[0061] (2) Add 0.1161g levulinic acid, 0.1072g benzylamine and 2mL methanol to a two-necked flask (25mL), then add 0.0241g Pt(1.0) / CeO2-0.1VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25℃ and stir vigorously at 500rpm for 3h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0062] Example 7 (1) Preparation of Pt(3.0) / CeO2-0.1VC-400 catalyst: The catalyst was prepared according to step (1) in Example 1, except that 10 mL of aqueous solution containing 0.0255 g H2PtCl6·6H2O was added dropwise. All other conditions were the same as step (1) in Example 1. Thus, Pt / CeO2 catalyst was prepared, denoted as Pt(3.0) / CeO2-0.1VC-400, and the Pt content in the catalyst was about 3 wt%.

[0063] (2) Add 0.1161g levulinic acid, 0.1072g benzylamine and 2mL methanol to a two-necked flask (25mL), then add 0.0241g Pt(3.0) / CeO2-0.1VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25℃ and stir vigorously at 500rpm for 1h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0064] Example 8 (1) The Pt(2.0) / CeO2-0.1VC-400 catalyst was prepared according to the method in step (1) of Example 1.

[0065] (2) Add 0.1161 g levulinic acid, 0.0731 g n-butylamine (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Pt(2.0) / CeO2-0.1VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 3 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0066] Example 9 (1) The Pt(2.0) / CeO2-0.1VC-400 catalyst was prepared according to the method in step (1) of Example 1.

[0067] (2) Add 0.1161 g levulinic acid, 0.1012 g n-hexylamine (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Pt(2.0) / CeO2-0.1VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 3 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0068] Example 10 (1) The Pt(2.0) / CeO2-0.1VC-400 catalyst was prepared according to the method in step (1) of Example 1.

[0069] (2) Add 0.1161 g levulinic acid, 0.1292 g n-octylamine (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Pt(2.0) / CeO2-0.1VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 3 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0070] Example 11 (1) The Pt(2.0) / CeO2-0.1VC-400 catalyst was prepared according to the method in step (1) of Example 1.

[0071] (2) Add 0.1161 g levulinic acid, 0.0872 g 3-pentylamine (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Pt(2.0) / CeO2-0.1VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 3 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0072] Example 12 (1) The Pt(2.0) / CeO2-0.1VC-400 catalyst was prepared according to the method in step (1) of Example 1.

[0073] (2) Add 0.1161 g levulinic acid, 0.0751 g 3-amine-1-propanol (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Pt(2.0) / CeO2-0.1VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 3 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0074] Example 13 (1) The Pt(2.0) / CeO2-0.1VC-400 catalyst was prepared according to the method in step (1) of Example 1.

[0075] (2) Add 0.1161 g levulinic acid, 0.0891 g 3-methoxy-1-propane (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Pt(2.0) / CeO2-0.1VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 3 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0076] Example 14 (1) The Pt(2.0) / CeO2-0.1VC-400 catalyst was prepared according to the method in step (1) of Example 1.

[0077] (2) Add 0.1161 g levulinic acid, 0.0992 g cyclohexylamine (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Pt(2.0) / CeO2-0.1VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 5 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0078] Example 15 (1) The Pt(2.0) / CeO2-0.1VC-400 catalyst was prepared according to the method in step (1) of Example 1.

[0079] (2) Add 0.1161 g levulinic acid, 0.0931 g aniline (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Pt(2.0) / CeO2-0.1VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 5 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0080] Example 16 (1) The Pt(2.0) / CeO2-0.1VC-400 catalyst was prepared according to the method in step (1) of Example 1.

[0081] (2) Add 0.1161 g levulinic acid, 0.1212 g 2-methylbenzylamine (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Pt(2.0) / CeO2-0.1VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 5 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0082] Example 17 (1) The Pt(2.0) / CeO2-0.1VC-400 catalyst was prepared according to the method in step (1) of Example 1.

[0083] (2) Add 0.1161 g levulinic acid, 0.1212 g 4-methylbenzylamine (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Pt(2.0) / CeO2-0.1VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 3 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0084] Example 18 (1) The Pt(2.0) / CeO2-0.1VC-400 catalyst was prepared according to the method in step (1) of Example 1.

[0085] (2) Add 0.1161 g levulinic acid, 0.1212 g 3-methylbenzylamine (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Pt(2.0) / CeO2-0.1VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 3 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0086] Example 19 (1) The Pt(2.0) / CeO2-0.1VC-400 catalyst was prepared according to the method in step (1) of Example 1.

[0087] (2) Add 0.1161 g levulinic acid, 0.1416 g 4-chlorobenzylamine (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Pt(2.0) / CeO2-0.1VC-400 catalyst, seal the two-necked flask, and fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 3 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0088] Examples 20-23 (1) The Pt(2.0) / CeO2-0.1VC-400 catalyst was prepared according to the method in step (1) of Example 1.

[0089] 2) Add 0.1161g of levulinic acid, 0.1072g of benzylamine, and 2.5mL (Example 20), 1.5mL (Example 21), 1.0mL (Example 22), and 0.5mL (Example 23) of methanol to a two-necked flask (25mL). Then add 0.0241g of Pt(2.0) / CeO2-0.1VC-400 catalyst. After sealing the two-necked flask, fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25°C and stir vigorously at 500rpm for 1h (Example 20), 3h (Example 21), 5h (Example 22), and 8h (Example 23) to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0090] Comparative Example 1 Add 0.1161 g levulinic acid (1 mmol), 0.1072 g benzylamine (1 mmol) and 2 mL methanol to a two-necked flask (25 mL). After sealing the two-necked flask, fill it with pure hydrogen gas (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 1 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0091] Comparative Example 2 (1) Place 4.3422g Ce(NO3)3·6H2O (10mmol) and 0.1761g ascorbic acid (1mmol) in a mortar and grind by hand for 5min until they are mixed evenly. Then place the solid mixture in a muffle furnace and heat it to 400℃ at a rate of 5℃ / min in air atmosphere and maintain it for 4h to obtain CeO2 support, which is denoted as CeO2-0.1VC-400.

[0092] (2) Add 0.1161 g levulinic acid (1 mmol), 0.1072 g benzylamine (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g CeO2-0.1VC-400. After sealing the two-necked flask, fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 1 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0093] Comparative Example 3 0.1161 g levulinic acid (1 mmol), 0.1072 g benzylamine (1 mmol), and 2 mL methanol were added to a two-necked flask (25 mL). Then, 0.0241 g of commercial Pt / C catalyst (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with a Pt content of 5 wt%) was added. After sealing the two-necked flask, pure hydrogen (99.999%) was introduced through a hydrogen balloon. The two-necked flask was then placed in an oil bath at 25 °C and stirred vigorously at 500 rpm for 1 h to stop the reaction. The reaction mixture was removed and tested. The test results are listed in Table 1.

[0094] Comparative Example 4 (1) Preparation of Pt(2.0) / commercial-CeO2 catalyst: 0.06 g of polyvinylpyrrolidone was dissolved in 30 mL of deionized water, and then 0.3 g of CeO2 was added and stirred continuously for 20 min; then 10 mL of aqueous solution containing 0.0170 g H2PtCl6·6H2O was added dropwise to the mixture and stirred for 1 h; then 10 mL of NaBH4 aqueous solution (NaBH4 / Pt molar ratio of 10) was slowly added and stirred continuously for 3 h; the solid mixture was collected by filtration and washed three times each with hot water (95 °C) and anhydrous ethanol; finally, the solid mixture was dried under vacuum at 60 °C for 12 h to obtain Pt(2.0) / commercial-CeO2 catalyst, in which the Pt content was about 2 wt%.

[0095] (2) Add 0.1161 g levulinic acid (1 mmol), 0.1072 g benzylamine (1 mmol) and 2 mL methanol to a double-necked flask (25 mL), and then add 0.0241 g Pt (2.0) / commercially available CeO2 catalyst (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with a Pt content of 5 wt%). After sealing the double-necked flask, fill it with pure hydrogen gas (99.999%) through a hydrogen balloon. Then place the double-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 1 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0096] Comparative Example 5 (1) Preparation of Pt(2.0) / CeO2-400 catalyst: 4.3422g Ce(NO3)3·6H2O (10mmol) was placed in a mortar and manually ground for 5min until it was mixed evenly. Then the solid mixture was placed in a muffle furnace and heated to 400℃ at a heating rate of 5℃ / min under air atmosphere and maintained for 4h to obtain CeO2 support, denoted as CeO2-400; 0.06 g of polyvinylpyrrolidone was dissolved in 30 mL of deionized water, followed by the addition of 0.3 g of CeO2-400 support and stirring for 20 min. Then, 10 mL of an aqueous solution containing 0.0170 g of H2PtCl6·6H2O was added dropwise to the mixture and stirring was continued for 1 h. Then, 10 mL of NaBH4 aqueous solution (NaBH4 / Pt molar ratio of 10) was slowly added and stirring was continued for 3 h. The solid mixture was collected by filtration and washed three times each with hot water (95 °C) and anhydrous ethanol. Finally, the solid mixture was dried under vacuum at 60 °C for 12 h to obtain the Pt / CeO2 catalyst, denoted as Pt(2.0) / CeO2-400, with a Pt content of approximately 2 wt%.

[0097] (2) Add 0.1161 g levulinic acid (1 mmol), 0.1072 g benzylamine (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Pt(2.0) / CeO2-400 catalyst. After sealing the two-necked flask, fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 1 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0098] Comparative Example 6 (1) Preparation of Pd(2.0) / CeO2-0.1VC-400 catalyst: The catalyst was prepared according to step (1) in Example 1, except that 10 mL of aqueous solution containing 0.0108 g PdCl2 was added dropwise. All other conditions were the same as step (1) in Example 1. Thus, Pd / CeO2 catalyst was prepared and denoted as Pd(2.0) / CeO2-0.1VC-400. The Pd content in the catalyst was about 2 wt%.

[0099] (2) Add 0.1161 g levulinic acid (1 mmol), 0.1072 g benzylamine (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Pd(2.0) / CeO2-400 catalyst. After sealing the two-necked flask, fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 1 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0100] Comparative Example 7 (1) Preparation of Au(2.0) / CeO2-0.1VC-400 catalyst: The catalyst was prepared according to step (1) in Example 1, except that 10 mL of aqueous solution containing 0.0112 g HAuCl4 was added dropwise. All other conditions were the same as step (1) in Example 1. Thus, Au / CeO2 catalyst was prepared, denoted as Au(2.0) / CeO2-0.1VC-400, and the Au content in the catalyst was about 2 wt%.

[0101] (2) Add 0.1161 g levulinic acid (1 mmol), 0.1072 g benzylamine (1 mmol) and 2 mL methanol to a two-necked flask (25 mL), then add 0.0241 g Au(2.0) / CeO2-400 catalyst. After sealing the two-necked flask, fill it with pure hydrogen (99.999%) through a hydrogen balloon. Then place the two-necked flask in an oil bath at 25 °C and stir vigorously at 500 rpm for 1 h to stop the reaction. Take out the reaction mixture and test it. The test results are listed in Table 1.

[0102] Test Example 1 Depend on Figure 1 The high-resolution TEM images and particle size distribution shown indicate that the average particle size of Pt nanoparticles on the Pt(2.0) / CeO2-400 catalyst is 3.67 nm, while the average particle size of Pt nanoparticles distributed on the Pt(2.0) / CeO2-0.1VC-400 catalyst is only 1.89 nm.

[0103] Depend on Figure 3 The XRD characterization results in (a) show that all samples exhibit typical face-centered cubic fluorite CeO2 characteristic diffraction peaks (JCPDS No. 34-0394). Further refinement using Rietveld (…) Figure 3 (a) Right side) It was found that the lattice constant of CeO2-0.1VC-400 was slightly larger than that of CeO2-400. This may be due to the reduction gas generated during the ascorbic acid (VC) assisted calcination process inducing partial CeO2 oxidation. 4+ Restored to Ce 3+ And accompanied by the formation of oxygen vacancies (Ov) (Ce 4+ →Ce 3+ +Ov). On the other hand, no interaction with Pt or PtO was observed in the catalyst after Pt loading. x The presence of new diffraction peaks or noticeable peak shifts is likely due to the low Pt loading and its high dispersion on the support surface. Figure 3 (b) The EPR results show that all catalyst samples exhibit symmetrical Lorentz curves at a g-factor of 2.004. The EPR signal of CeO2-0.1VC-400 is stronger than that of CeO2-400, which proves that VC can effectively promote the generation of oxygen vacancies. Notably, the EPR signal intensity of the Pt(2.0) / CeO2-0.1VC-400 catalyst is much higher than that of CeO2-0.1VC-400 and Pt(2.0) / CeO2-400, indicating that it has more oxygen vacancies.

[0104] Depend on Figure 4 The N2 adsorption-desorption isotherm characterization results show that the catalyst samples all exhibit typical type IV adsorption curves, accompanied by H3 type hysteresis loops, indicating that the catalyst has a mesoporous structure formed by the accumulation of plate-like particles, which is consistent with the layered morphology observed by SEM. Figure 5 The specific surface area of ​​the CeO2-400 carrier is calculated to be 62.8 m². 2 ·g -1 After VC-assisted calcination, the specific surface area of ​​CeO2-0.1VC-400 significantly increased to 90.6 m². 2 ·g -1Meanwhile, the total pore volume decreased from 0.198 cm³. 3 ·g -1 Increased to 0.218cm 3 ·g -1 This phenomenon may be attributed to the decomposition of VC during calcination, which releases a large amount of gas. This gas makes the support more porous and forms numerous pores within it. After loading Pt, the specific surface area and total pore volume of the Pt(2.0) / CeO2-0.1VC-400 catalyst decreased to 52.8 m². 2 ·g -1 and 0.192cm 3 ·g -1 This may be because Pt nanoparticles are deposited in the pores of CeO2-0.1VC-400.

[0105] The morphology and structural characteristics of the Pt(2.0) / CeO2-0.1VC-400 catalyst were further revealed using electron microscopy (SEM). Figure 5 The results show that the CeO2-400 support exhibits a regular lamellar structure with smooth particle surfaces; in contrast, the CeO2-0.1VC-400 support prepared by VC-assisted calcination exhibits an irregular, disordered lamellar structure with rougher and looser particle surfaces. This is consistent with the increase in specific surface area (62.8→90.6 m²) observed in the N2 adsorption-desorption test. 2 ·g -1 The results are consistent.

[0106] Test Example 2 The reaction mixtures obtained in the above examples and comparative examples were analyzed for components and content using gas chromatography, and the LA conversion rate (%) and the yields (%) of BMP and intermediate products were calculated according to formulas (1), (2), and (3), respectively. The results are shown in Table 1.

[0107] Formula (1):

[0108] Formula (2):

[0109] Formula (3): The intermediate product is M4 or M5.

[0110] Table 1

[0111]

[0112]

[0113]

[0114] The catalytic system of the present invention was compared with that of the prior art, and the results are shown in Table 2. As can be seen from Table 2, the catalytic system of the present invention can efficiently catalyze the reduction amination of levulinic acid to synthesize N-substituted-5-methyl-2-pyrrolidone under ambient temperature and pressure conditions, with a formation rate as high as 476.0 mol BMP·mol metal. -1 ·h -1 This value exceeds that of most catalytic systems currently reported.

[0115] Table 2

[0116] Generation rate a This refers to the amount of the target product (in moles) obtained per hour per mole of precious metal under the listed reaction conditions, expressed in mol BMP·mol metal. -1 ·h -1 .

[0117] The catalyst systems described above are derived from the following references: [1] Green Chem. 16 (2014) 1093-1096, https: / / doi.org / 10.1039 / C3GC42125B. [2] J. Flow Chem. 8 (2018) 35-43, https: / / doi.org / 10.1007 / s41981-018-0005-6. [3] ACS Sustainable Chem. Eng. 9 (2021) 4377-4382, https: / / doi.org / 10.1021 / acssuschemeng.1c00211. [4] ACS Catal. 7 (2017) 4927-4935, https: / / doi.org / 10.1021 / acscatal.7b01786. [5] ACS Catal. 13 (2023) 12601-12616, https: / / doi.org / 10.1021 / acscatal.3c03854. [6] ACS Catal. 15 (2025) 91-104, https: / / doi.org / 10.1021 / acscatal.4c06035. [7] Angew. Chem. Int. Ed. 50 (2011) 7815-7819, https: / / doi.org / 10.1002 / anie.201100102. [8] Green Chem. 22 (2020) 7760-7764, https: / / doi.org / 10.1039 / D0GC01725F. [9] Green Chem. 22 (2020) 3820-3826, https: / / doi.org / 10.1039 / D0GC01177K.

[10] J. Catal. 383 (2020) 206-214, https: / / doi.org / 10.1016 / j.jcat.2020.01.020.

[11] J. Am. Chem. Soc. 141 (2019) 4002-4009, https: / / doi.org / 10.1021 / jacs.8b13024.

[12] ACS Catal. 4 (2014) 3045-3050, https: / / doi.org / 10.1021 / cs500757k. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A method for producing a pyrrolidinone compound by reductive amination of levulinic acid, characterized by, The method comprises: adding acetylpiclin, an amine compound, an organic solvent and a Pt / CeO2 catalyst into a reactor, and performing a reductive amination reaction under the conditions of hydrogen and 20-30 DEG C to collect a reaction product to obtain a pyrrolidone compound. The Pt / CeO2 catalyst is prepared by the following method: S1. mixing a cerium source with ascorbic acid and performing heat treatment under an oxygen-containing atmosphere to obtain a Ce oxide, which is denoted as a CeO2 carrier; S2. performing impregnation treatment and reduction treatment on the CeO2 carrier and a platinum salt to load Pt nanoparticles on the CeO2 carrier, and collecting a reaction product to obtain the Pt / CeO2 catalyst. The amine compound has a general chemical structure of R-NH2, wherein R is any one of C1-C8 alkyl, C3-C8 cycloalkyl, C1-C8 alkylene-substituted hydroxyl, C1-C8 alkylene-substituted C1-C3 alkoxy, unsubstituted C6-C20 aryl, and C6-C12 aralkyl substituted with methyl or halogen atoms.

2. The method of preparing pyrrolidinone compounds by reductive amination of levulinic acid according to claim 1, characterized in that, The Pt content in the Pt / CeO2 catalyst is 1-3 wt%.

3. The method of claim 1, wherein the method is characterized by, In step S1, the molar ratio of Ce in the cerium source to ascorbic acid is 1:(0.1-0.3). Preferably, the cerium source is at least one of cerium nitrate, cerium acetate, cerium oxalate, cerium chloride and cerium sulfate. Preferably, the heat treatment is performed under the conditions of a temperature of 400-600 DEG C and a time of 3-5 h.

4. The method of claim 1, wherein the method is characterized by, In step S2, the impregnation treatment and reduction treatment are performed as follows: mixing the CeO2 carrier with a platinum salt and water to perform impregnation treatment, mixing the obtained mixture with a reducing agent to perform a reduction reaction, and collecting a final reaction product to obtain the Pt / CeO2 catalyst.

5. The method of preparing a pyrrolidinone compound by reductive amination of levulinic acid according to claim 1 or 4, characterized in that, The amount of the platinum salt is determined according to the Pt content of 1-3 wt% in the Pt / CeO2 catalyst. Preferably, the platinum salt is chloroplatinic acid and / or platinum chloride. Preferably, the impregnation treatment is performed under the conditions of a temperature of 15-30 DEG C and a time of 1-3 h.

6. The method of preparing pyrrolidinone compounds by reductive amination of levulinic acid according to claim 4, characterized in that, In step S2, the impregnation treatment further comprises adding a dispersant, and the dispersant is polyvinylpyrrolidone.

7. The method of claim 4, wherein the method is characterized by, The reducing agent is sodium borohydride. Preferably, the molar ratio of the reducing agent to Pt in the platinum salt is (10-20):

1. Preferably, the reduction reaction is performed under the conditions of a temperature of 15-30 DEG C and a time of 3-5 h.

8. The method of claim 1, wherein the method is characterized by: The pressure of hydrogen during the reductive amination reaction is 0.1-0.3 MPa. Preferably, the molar ratio of acetylpiclin to Pt in the Pt / CeO2 catalyst is (250-1000):

1. Preferably, the molar ratio of acetylpiclin to the amine compound is 1:(1-3).

9. The method of claim 1, wherein the method is characterized by, The amine compound is at least one of n-propylamine, isopropylamine, n-butylamine, n-octylamine, n-propyl alcohol amine, isopropyl alcohol amine, 3-methoxy-1-propylamine, cyclohexylamine, aniline, benzylamine, 4-methylbenzylamine, 3-methylbenzylamine, 2-methylbenzylamine, 4-chlorobenzylamine, 3-chlorobenzylamine and 2-chlorobenzylamine.

10. The method of claim 1, wherein the method is characterized by: The organic solvent is at least one of methanol, ethanol, isopropyl alcohol and dimethyl sulfoxide.

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