Process for the preparation of 3-pentenenitrile by isomerization of 2-pentenenitrile

Abstract

This invention relates to a method for preparing 3-pentenonitrile by isomerization of 2-pentenonitrile. In this method, polyvinylpyridine porous microspheres are used as a catalyst. The polyvinylpyridine porous microspheres comprise polystyrene porous microspheres and a polyvinylpyridine polymer supported on the polystyrene porous microspheres. The catalyst used in this method possesses high catalytic activity, high selectivity, long service life, easy separation and recovery, and low cost, enabling efficient and highly selective isomerization of 2-pentenonitrile to 3-pentenonitrile. Therefore, when applied to the method of preparing adiponitrile by hydrocyanation of butadiene, the byproduct 2-pentenonitrile can be selectively isomerized to the target product 3-pentenonitrile, thus protecting the hydrocyanation catalyst and improving the yield of the target product.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, and in particular to a method for preparing 3-pentenonitrile by isomerization reaction of 2-pentenonitrile. Background Technology

[0002] Adiponitrile (ADN), with the molecular formula NC(CH2)4CN, is an important organic chemical intermediate. Industrially, it is mainly used for the hydrogenation of hexamethylenediamine, an intermediate for the production of nylon 66. It can also be used to prepare chemical products such as caprolactam and is widely used in the automotive, engineering plastics, electronics, precision instruments, and textile industries.

[0003] Currently, the butadiene hydrocyanation method has become the most competitive industrial production route for adiponitrile due to its short process route, high yield, and low pollution. This process mainly involves three steps: First, butadiene undergoes a primary hydrocyanation with hydrogen cyanide (HCN) to produce the main product 3-pentenonitrile (3PN) and the byproduct 2-methyl-3-butenonitrile (2M3BN); second, 2-methyl-3-butenonitrile isomerizes to 3-pentenonitrile; third, 3-pentenonitrile undergoes a secondary hydrocyanation with HCN to obtain the target product, adiponitrile.

[0004] However, during the hydrocyanation and isomerization reaction, the byproduct 2-pentenonitrile (2PN) will inevitably be generated. The accumulation of 2-pentenonitrile will not only poison the hydrocyanation catalyst, significantly reducing its activity and lifespan, but also the boiling points of 2-pentenonitrile and the target product 3-pentenonitrile are extremely close, making separation by distillation extremely difficult and energy-intensive.

[0005] Selectively isomerizing the byproduct 2-pentenonitrile to the target product 3-pentenonitrile and recycling the 3-pentenonitrile into the hydrocyanation reaction can both protect the hydrocyanation catalyst and improve the yield of the target product. This is currently an effective method to enhance the overall competitiveness of the butadiene hydrocyanation process. However, all the isomerization catalysts disclosed in the prior art have significant objective defects and are difficult to meet the needs of industrial applications.

[0006] For example, US3526654A uses silica, alumina, or sodium-calcium silicate catalysts for isomerization reactions, resulting in low conversion rates and long isomerization times; after 6 months, only 40% conversion was observed. Patent CN1777578A uses BET catalysts with a surface area of ​​50 m². 2Alumina catalysts of 1 g or higher are used for the isomerization of 2-pentenonitrile. However, in addition to the target isomerization reaction, oligomerization also occurs. As the pentenonitrile oligomerization proceeds, the sample becomes increasingly viscous, and the catalyst is encapsulated in heavy materials, resulting in a relatively short lifespan. Patent CN105102118A uses non-aluminum metal oxide catalysts such as Fe2O3, Cr2O3, CoO, NiO, CuO, ZnO, ZrO2 doped with CeO2, ZrO2 doped with La2O3, and ZrO2 doped with both CeO2 and La2O3 for isomerization. However, the activity of these catalysts is generally lower than that of noble metal or transition metal catalysts, requiring higher reaction conditions to achieve satisfactory conversion rates. Patent CN109651195A discloses a mixture of 2-pentenonitrile with transition metals such as nickel and rhodium, bidentate phosphorus ligands, and Lewis acids for isomerization. The transition metals and phosphorus ligands in this type of mixed catalytic system are very expensive. Patent CN104254520A uses 1,4-diazabicyclo[2.2.2]octane as a catalyst to intermittently or continuously isomerize 2-pentenonitrile to 3-pentenonitrile. However, during the isomerization process, due to the excessive basicity of 1,4-diazabicyclo[2.2.2]octane, excessive isomerization or polymerization of 2-pentenonitrile may occur, reducing the selectivity of the target product. Summary of the Invention

[0007] Therefore, it is necessary to provide a method for preparing 3-pentenonitrile by isomerization reaction of 2-pentenonitrile to address the above problems. The catalyst used in the method has the characteristics of high catalytic activity, high selectivity, long service life, easy separation and recovery, and low cost, and can efficiently and selectively isomerize 2-pentenonitrile to 3-pentenonitrile.

[0008] A method for preparing 3-pentenonitrile by isomerization reaction of 2-pentenonitrile, wherein the method uses polyvinylpyridine porous microspheres as catalyst, the polyvinylpyridine porous microspheres comprising polystyrene porous microspheres and polyvinylpyridine polymer supported in the polystyrene porous microspheres.

[0009] In one embodiment, the pyridine monomer used in the polyvinylpyridine polymer has the following structural formula:

[0010] ;

[0011] In the structural formula, R1 and R2 are independently selected from hydrogen atoms, halogen atoms, and C1-C atoms, respectively. 10 Alkyl, C1-C 10 alkoxy groups, C1-C 10 The group is composed of alkyl, aryl, heteroaryl, cyano, or nitro groups, where m is an integer from 0 to 3, and Q is a direct bond or a divalent linker.

[0012] In one embodiment, Q is selected from... , or ;

[0013] Among them, R3, R4, R5, and R6 are independently selected from hydrogen atoms, halogen atoms, and C1-C atoms, respectively. 10 Alkyl, C1-C 10 alkoxy groups, C1-C 10 The alkyl, aryl, heteroaryl, cyano, or nitro groups are selected from direct bonds or divalent linkages, m0 is an integer from 0 to 3, and m1 is an integer from 0 to 2.

[0014] In one embodiment, Q0 is selected from... , , The aryl group can be substituted or unsubstituted, and n1 and n2 are independent integers from 1 to 50.

[0015] In one embodiment, the pyridine monomer is selected from at least one of NO-1 to NO-12;

[0016] , ,

[0017] , , , , , , , ,

[0018] , .

[0019] In one embodiment, the nitrogen content in the polyvinylpyridine porous microspheres is 1% to 10% by mass.

[0020] In one embodiment, the polyvinylpyridine porous microspheres contain polystyrene porous microspheres with a particle size of 50 nm-100 nm.

[0021] And / or, the BET specific surface area of ​​the polyvinylpyridine porous microspheres is 50 m². 2 / g-400m 2 / g, with an average pore size of 10nm-40nm.

[0022] In one embodiment, when the isomerization reaction is carried out in a fixed-bed reactor, the mass hourly space velocity (WHSV) of the 2-pentenonitrile is 0.2 h⁻¹. -1 -0.8h -1 ;

[0023] And / or, the isomerization reaction temperature is 100℃-180℃;

[0024] And / or, the pressure of the isomerization reaction is 0.1 MPa-0.5 MPa.

[0025] In one embodiment, the polystyrene porous microspheres have an average degree of polymerization of 4800-9600, and the polyvinylpyridine polymer has an average degree of polymerization of 100-500.

[0026] In one embodiment, after the isomerization reaction is completed, the process further includes recovering the polyvinylpyridine porous microspheres and recycling them for catalyzing the isomerization reaction of 2-pentenonitrile to prepare 3-pentenonitrile.

[0027] In this invention, porous polyvinylpyridine microspheres are used as a catalyst. The polyvinylpyridine polymer in the catalyst forms suitable active centers through the basicity of its pyridine ring, while the porous polystyrene microspheres provide an ideal three-dimensional microenvironment for these active centers through their stable three-dimensional network structure. This composite structure not only endows the catalyst with excellent catalytic activity and selectivity, efficiently promoting double bond migration reactions, but also significantly suppresses side reaction pathways such as oligomerization and deep isomerization easily initiated by strongly basic sites through its unique spatial confinement effect. Furthermore, thanks to its stable cross-linked structure, the catalyst maintains excellent performance stability during recycling; its regular microsphere morphology ensures efficient recovery through simple solid-liquid separation; and the composition system, entirely based on polymer materials, gives the catalyst both raw material cost advantages and ease of process operation. Therefore, these characteristics collectively enable the catalyst to achieve efficient and highly selective preparation of 3-pentenonitrile in the 2-pentenonitrile isomerization reaction, providing a better solution for developing an economically feasible industrial process.

[0028] Furthermore, when applied to the method of preparing adiponitrile by hydrocyanation of butadiene, it can selectively isomerize the byproduct 2-pentenonitrile into the target product 3-pentenonitrile, which can both protect the hydrocyanation catalyst and improve the yield of the target product. Detailed Implementation

[0029] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional scope of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0031] In this invention, numerical ranges are involved. Unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe features or characteristics, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0032] The present invention provides a method for preparing 3-pentenonitrile by isomerization reaction of 2-pentenonitrile, wherein the method uses polyvinylpyridine porous microspheres as catalyst, the polyvinylpyridine porous microspheres comprising polystyrene porous microspheres and polyvinylpyridine polymer supported in the polystyrene porous microspheres.

[0033] The average degree of polymerization (DP) of the polystyrene porous microspheres is preferably 4800-9600, and the average degree of polymerization (DP) of the polyvinylpyridine polymer is preferably 100-500.

[0034] The polyvinylpyridine porous microsphere catalyst used in this invention has, at the molecular level, a moderately basic active center formed by the pyridine ring in the polyvinylpyridine polymer, which provides the reaction driving force for double bond migration.

[0035] At the spatial structure level, the three-dimensional network framework constructed from polystyrene porous microspheres creates a unique three-dimensional microenvironment for the active centers through its precisely regulated pore size distribution and tortuous pore structure. On the one hand, the geometric constraints of the pores selectively distinguish the pathways of the main reaction and side reactions, allowing linear double bond migration reactions to proceed smoothly. On the other hand, the chemical environment on the pore surface regulates the adsorption strength and residence time of reactant molecules, effectively preventing excessive aggregation of reactant molecules at the active centers, thereby inhibiting the occurrence of side reactions such as oligomerization.

[0036] Therefore, based on the synergistic mechanism of the aforementioned electronic properties and spatial structure, the catalyst of this invention possesses a unique selective catalytic pathway. Specifically, moderate basicity provides the necessary driving force for double bond migration, ensuring efficient initiation of the main reaction; simultaneously, precise spatial confinement optimizes the reactant mass transfer process through molecular sieving effects, selectively hindering the molecular configuration and reaction space required for side reactions. This dual-effect synergistic mechanism works on both reaction kinetics and thermodynamic levels, significantly improving the selectivity of 3-pentenonitrile by precisely distinguishing between the main and side reaction pathways while maintaining high conversion rates, thus enabling the catalyst to possess both activity and selectivity.

[0037] Furthermore, in the polyvinylpyridine porous microsphere catalyst of this invention, the polyvinylpyridine segments are connected by covalent bonds and then form a stable three-dimensional network structure with the polystyrene porous microspheres. This effectively inhibits the swelling and deformation of the polymer chains, ensuring the long-term stability of the pore structure and specific surface area. Simultaneously, the rigid framework of the polystyrene porous microspheres effectively immobilizes the active sites, preventing their migration, aggregation, or loss during the reaction process, thereby maintaining the durability and consistency of catalytic performance. Its regular microsphere morphology ensures efficient recovery through simple solid-liquid separation. Moreover, the composition system, entirely based on polymer materials, gives this catalyst both raw material cost advantages and ease of process operation.

[0038] Optionally, the pyridine monomer used in the polyvinylpyridine polymer has the following structural formula:

[0039] ;

[0040] In the structural formula, R1 and R2 are independently selected from hydrogen atoms, halogen atoms, and C1-C atoms, respectively. 10 Alkyl, C1-C 10 alkoxy groups, C1-C 10 The group is composed of alkyl, aryl, heteroaryl, cyano, or nitro groups, where m is an integer from 0 to 3, and Q is a direct bond or a divalent linker.

[0041] Thus, by selecting the structure and precisely controlling the electronic effects of the R1 and R2 substituents and the spatial configuration of the Q linking group in the pyridine monomer, the electronic characteristics of the active center and the porous framework structure of the catalyst are synergistically optimized. This allows the catalyst to simultaneously balance reactivity and product selectivity, ensuring efficient catalysis of the migration of the 2-pentenonitrile double bond while suppressing side reaction pathways through steric hindrance. At the same time, the optimized crosslinked network structure endows the catalyst with a stable porous framework and excellent mechanical strength, which is beneficial for achieving efficient recovery and long cycle life.

[0042] Furthermore, Q is selected from , or Among them, R3, R4, R5, and R6 are independently selected from hydrogen atoms, halogen atoms, and C1-C atoms, respectively. 10 Alkyl, C1-C 10 alkoxy groups, C1-C 10 The alkyl, aryl, heteroaryl, cyano, or nitro groups are selected from direct bonds or divalent linkages, m0 is an integer from 0 to 3, and m1 is an integer from 0 to 2.

[0043] Furthermore, Q0 is selected from , , The aryl group can be substituted or unsubstituted, and n1 and n2 are independent integers from 1 to 50.

[0044] Furthermore, the pyridine monomer is selected from at least one of NO-1 to NO-12;

[0045] , ,

[0046] , , , , , , , ,

[0047] , .

[0048] Optionally, the nitrogen content in the polyvinylpyridine porous microspheres is 1% to 10% by mass. This allows for a more precise balance between the density of active sites and the integrity of the porous structure, ensuring sufficient pyridine active centers for efficient catalysis while avoiding increased side reactions or pore structure collapse due to excessive site density. Furthermore, this nitrogen content configuration allows the catalyst to maintain suitable surface polarity while preserving an open and interconnected three-dimensional pore network, providing an ideal channel for efficient mass transfer between reactants and products. Ultimately, this achieves optimal synergy between activity, selectivity, and stability, contributing to efficient isomerization performance and long cycle life.

[0049] To better improve catalytic activity, mass transfer efficiency, and ease of operation, the particle size of the polystyrene porous microspheres in the polyvinylpyridine porous microspheres is preferably 50 nm-100 nm, and / or the BET specific surface area of ​​the polyvinylpyridine porous microspheres is preferably 50 m² / m³. 2 / g-400m 2 / g, with an average pore size preferably between 10nm and 40nm. This ensures that the catalyst has sufficient exposed active sites and a suitable reaction interface, while also providing an efficient mass transfer channel for reactant molecules, and guaranteeing uniform dispersion of the catalyst in the reaction system and efficient separation in subsequent processing.

[0050] It is understood that the preparation method of the polyvinylpyridine porous microspheres of the present invention includes the following steps:

[0051] (1) Take polystyrene seed microspheres and ultrasonically disperse them in an aqueous solution of surfactant to obtain a first emulsion; take a certain volume of a first organic solvent and ultrasonically disperse it in an aqueous solution of surfactant to obtain a second emulsion. At room temperature, add the second emulsion to the first emulsion and shake and mix for a period of time to obtain a first mixture containing polystyrene seed microspheres.

[0052] (2) A certain amount of pyridine monomer and initiator are dissolved in a second organic solvent, then dispersed in an aqueous solution containing a surfactant, ultrasonically emulsified, added to the first mixture, and continued to be shaken and mixed to obtain the second mixture;

[0053] (3) The air in the second mixture is removed by replacing it with an inert atmosphere such as nitrogen or argon. Then the polymerization reaction is carried out. After the polymerization reaction is completed, the polymerization reaction liquid is separated into solid and liquid and washed with a third organic solvent. Then it is dried under vacuum to obtain polyvinylpyridine porous microspheres.

[0054] In steps (1) and (2), the concentration of the surfactant aqueous solution is 0.2wt%-1.5wt%, preferably 0.5wt%-1.0wt%, and the shaking mixing time is 6h-18h, preferably 10h-12h.

[0055] The surfactant is selected from at least one of cationic surfactants, anionic surfactants, and nonionic surfactants, and is further selected from at least one of hexadecyltrimethyl quaternary ammonium bromide, octadecyldimethylbenzyl quaternary ammonium chloride, ammonium dodecyl sulfate, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, potassium dodecyl phosphate, polyvinyl alcohol, and Tween-80.

[0056] In the first emulsion of step (1), the mass ratio of polystyrene seed microspheres to the volume ratio of surfactant aqueous solution is 1g:20mL-1g:100mL. In the second emulsion of step (1), the volume ratio of first organic solvent to surfactant aqueous solution is 1:10-1:30. The addition ratio of first emulsion to second emulsion in step (1) is 1:1-1:1.1.

[0057] The first organic solvent is selected from at least one of ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, methanol, ethanol, propanol, tert-butanol, ethylene glycol, propylene glycol, glycerol, and acetone.

[0058] In step (2), the molar ratio of pyridine monomer to initiator is 20:1-50:1, the mass ratio of pyridine monomer to polystyrene seed microspheres in step (1) is 50:1-100:1, the mass ratio of pyridine monomer to second organic solvent is 2:1-1:1, and the volume ratio of second solvent to surfactant aqueous solution is 1:10-1:30.

[0059] The initiator is selected from azo initiators, and further selected from at least one of azobisisobutyronitrile (AIBN), azobisisoheptanenitrile (ABVN), dimethyl azobisisobutyrate (AIBME), azobisisobutyramidine hydrochloride (AIBA), and azobisisobutyramidine imidazoline hydrochloride (AIBI); the second organic solvent is selected from at least one of aliphatic or alicyclic hydrocarbons, halogenated aliphatic or alicyclic hydrocarbons, substituted or unsubstituted aromatic hydrocarbons, aliphatic ethers, and cyclic ethers, and further selected from at least one of benzene, toluene, xylene, dichloromethane, cyclohexane, n-hexane, and tetrahydrofuran.

[0060] In step (3), the temperature of the polymerization reaction is 40℃-120℃, more preferably 60℃-80℃, and the time is 6h-36h, more preferably 20h-24h.

[0061] In step (3), the third organic solvent is selected from at least one of ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, methanol, ethanol, propanol, tert-butanol, ethylene glycol, propylene glycol, glycerol, and acetone.

[0062] To provide sufficient reaction interface and active sites, while avoiding the economic benefits and increased reaction system complexity caused by excessive catalyst use, it is preferable that the mass hourly space velocity (WHSV) of the 2-pentenonitrile is 0.2 h⁻¹ when carrying out the isomerization reaction in a fixed-bed reactor. -1 -0.8h -1 .

[0063] In order to ensure that the double bond migration reaction has sufficient kinetic driving force and obtain better conversion and selectivity, the temperature of the isomerization reaction is preferably 100℃-180℃.

[0064] In order to maintain the stability of the reaction system, ensure sufficient intermolecular collision frequency, and avoid the increased equipment requirements and energy consumption caused by excessive pressure, the pressure of the isomerization reaction is preferably 0.1MPa-0.5MPa.

[0065] Optionally, after the isomerization reaction is completed, the process further includes recovering the polyvinylpyridine porous microspheres and recycling them for catalyzing the isomerization reaction of 2-pentenonitrile to prepare 3-pentenonitrile.

[0066] The technical solution of the present invention will be further described below through specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Unless otherwise specified, specific conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used without specified manufacturers are all commercially available conventional products.

[0067] Preparation of polyvinylpyridine porous microspheres C1

[0068] (1) Take 1g of polystyrene porous microspheres (the microspheres used can be from Suzhou Zhiyi Microsphere Co., Ltd. - KBsphere60 PS, Wuxi Ruige Biotechnology Co., Ltd. - PS2600, Beijing Zhongke Keyou Technology Co., Ltd. - ZKKY-PS-60μm, etc., with a particle size of 60nm and a relative standard deviation of 3%) and ultrasonically disperse them in 30mL of 0.5wt% sodium dodecyl sulfate solution to obtain the first emulsion; take another 3mL of ethyl acetate and ultrasonically disperse it in 30mL of 0.5wt% sodium dodecyl sulfate solution to obtain the second emulsion. Quickly add the second emulsion to the first emulsion and shake to mix, and shake at room temperature for 10 hours to obtain the first mixture containing polystyrene porous microspheres.

[0069] (2) Dissolve 50g of pyridine monomer with the structural formula shown in NO-1 and 2.32g of AIBA initiator in 40mL of toluene, then disperse them in 0.5wt% polyvinyl alcohol solution, emulsify by sonication, and then quickly add them to the first mixture. Continue to shake for 12 hours under the same conditions to obtain the second mixture.

[0070] (3) The air in the second mixture was removed by nitrogen replacement, and then the mixture was placed at 70°C and shaken for 24 hours. After the polymerization was completed, the polymerization reaction solution was centrifuged, washed with ethanol, and then vacuum dried at room temperature to obtain 49.92g of polyvinylpyridine porous microspheres C1. The nitrogen content was determined by elemental analysis.

[0071] The preparation methods for C2 to C12 porous polyvinylpyridine microspheres are the same as those described above, except that the reaction control parameters are different. The specific reaction parameters are shown in Table 1, and the reaction results are shown in Table 2.

[0072] Table 1

[0073]

[0074] Table 2

[0075]

[0076] Example 1

[0077] 10.0 g of polyvinylpyridine porous microspheres (C1 catalyst) were packed into the isothermal section of a Ф10 mm × 250 mm fixed-bed reactor. During fixed-bed operation, nitrogen protection was maintained throughout, and the system pressure was controlled at 0.3 MPa. When the reaction temperature reached 140 °C, 2-pentenonitrile feedstock was pumped into the reactor using a feed pump. The mass hourly space velocity (HSV) of the 2-pentenonitrile feedstock was 0.45 h⁻¹. -1 Samples were taken and analyzed every 1 hour. Analysis using well-known gas chromatography methods showed a selectivity of 89.4% for 3PN and 4PN, and a conversion rate of 15.8% for 2PN.

[0078] The preparation methods of Examples 2-12 are the same as those described above, except that the polyvinylpyridine porous microspheres used in the reaction are different. The specific reaction parameters and reaction results are shown in Table 3.

[0079] Table 3

[0080]

[0081] The composition and structure were determined by gas chromatography after the reaction, and the results are summarized in Table 4.

[0082] Table 4

[0083]

[0084] The calculations in the above embodiments are based on the following:

[0085] (1) 2PN conversion rate % = 2PN reaction reduction / 2PN initial amount × 100

[0086] (2) 3PN and 4PN selectivity % = (E - 3PN reaction product + Z - 3PN reaction product + 4PN reaction product) / (initial 2PN amount × 2PN conversion rate) × 100

[0087] In addition, E-2PN refers to trans-2-pentenonitrile, Z-2PN refers to cis-2-pentenonitrile, E-3PN refers to trans-3-pentenonitrile, Z-3PN refers to cis-3-pentenonitrile, and 4PN refers to 4-pentenonitrile.

[0088] The preparation methods of Examples 13-15 are the same as those of Example 1 above, except that the mass hourly space velocity of the raw material 2PN is different. The specific reaction parameters and reaction results are shown in Table 5.

[0089] Table 5

[0090]

[0091] The preparation methods of Examples 16-19 are the same as those of Example 1 above, except that the reaction temperature is different. The specific reaction parameters and reaction results are shown in Table 6.

[0092] Table 6

[0093]

[0094] Comparative Example 1: Pyridine monomer NO-1 was directly used as the isomerization catalyst. The specific preparation method is as follows:

[0095] 81.2 g of 2-pentenonitrile and 1.2 g of pyridine monomer NO-1 were added to an isomerization reactor. The reaction pressure was controlled at 0.3 MPa and the reaction temperature at 140 °C. During the reaction, nitrogen protection was maintained and mechanical stirring was applied. The reaction time was 8 hours, and 5.63 g of product was obtained after the reaction. Analysis using known gas chromatography methods showed a selectivity of 74.6% for 3PN and 4PN, and a conversion rate of 9.3% for 2PN.

[0096] Comparative Example 2 uses pyridine as an isomerization catalyst, and the specific preparation method is as follows:

[0097] 81.2 g of 2-pentenonitrile and 1.2 g of pyridine were added to an isomerization reactor, and the reaction pressure was controlled at 0.3 MPa and the reaction temperature at 140 °C. During the reaction, nitrogen protection was maintained and mechanical stirring was applied for 8 hours. After the reaction, 5.98 g of product was obtained. Analysis using known gas chromatography methods showed a selectivity of 70.2% for 3PN and 4PN, and a conversion rate of 10.5% for 2PN.

[0098] Comparative Example 3 uses polypyridine ionic liquid porous microspheres as a catalyst, with pyridine monomer NO-1. The specific preparation method is as follows:

[0099] 10.0 g of polypyridine ionic liquid porous microsphere catalyst was packed into the isothermal section of a Ф10 mm × 250 mm fixed-bed reactor. During fixed-bed operation, nitrogen protection was maintained throughout, and the system pressure was controlled at 0.3 MPa. When the reaction temperature reached 140 °C, 2-pentenonitrile feedstock was pumped into the reactor using a feed pump. The mass hourly space velocity (HSV) of the 2-pentenonitrile feedstock was 0.45 h⁻¹. -1 Samples were taken and analyzed every 1 hour. Analysis using well-known gas chromatography methods showed a selectivity of 71.2% for 3PN and 4PN, and a conversion rate of 5.8% for 2PN.

[0100] Comparative Example 4 uses polypyridine ionic liquid porous microspheres as a catalyst, with pyridine monomer NO-2. The specific preparation method is as follows:

[0101] 10.0 g of polypyridine ionic liquid porous microsphere catalyst was packed into the isothermal section of a Ф10 mm × 250 mm fixed-bed reactor. During fixed-bed operation, nitrogen protection was maintained throughout, and the system pressure was controlled at 0.3 MPa. When the reaction temperature reached 140 °C, 2-pentenonitrile feedstock was pumped into the reactor using a feed pump. The mass hourly space velocity (HSV) of the 2-pentenonitrile feedstock was 0.45 h⁻¹. -1 Samples were taken and analyzed every 1 hour. Analysis using well-known gas chromatography methods showed a selectivity of 80.3% for 3PN and 4PN, and a conversion rate of 9.1% for 2PN.

[0102] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0103] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing 3-pentenonitrile by isomerization reaction of 2-pentenonitrile, characterized in that, The method uses polyvinylpyridine porous microspheres as a catalyst, the polyvinylpyridine porous microspheres comprising polystyrene porous microspheres and polyvinylpyridine polymers supported in the polystyrene porous microspheres.

2. The method for preparing 3-pentenonitrile by isomerization reaction of 2-pentenonitrile according to claim 1, characterized in that, The pyridine monomer used in the polyvinylpyridine polymer has the following structural formula: ； In the structural formula, R1 and R2 are independently selected from hydrogen atoms, halogen atoms, and C1-C atoms, respectively. 10 Alkyl, C1-C 10 alkoxy groups, C1-C 10 The group is composed of alkyl, aryl, heteroaryl, cyano, or nitro groups, where m is an integer from 0 to 3, and Q is a direct bond or a divalent linker.

3. The method for preparing 3-pentenonitrile by isomerization reaction of 2-pentenonitrile according to claim 2, characterized in that, Q is selected from , or ; Among them, R3, R4, R5, and R6 are independently selected from hydrogen atoms, halogen atoms, and C1-C atoms, respectively. 10 Alkyl, C1-C 10 alkoxy groups, C1-C 10 The alkyl, aryl, heteroaryl, cyano, or nitro groups are selected from direct bonds or divalent linkages, m0 is an integer from 0 to 3, and m1 is an integer from 0 to 2.

4. The method for preparing 3-pentenonitrile by isomerization reaction of 2-pentenonitrile according to claim 3, characterized in that, Q0 is selected from , , The aryl group can be substituted or unsubstituted, and n1 and n2 are independent integers from 1 to 50.

5. The method for preparing 3-pentenonitrile by isomerization reaction according to claim 4, characterized in that, The pyridine monomer is selected from at least one of NO-1 to NO-12; 、 、 、 、 、 、 、 、 、 、 、 。 6. The method for preparing 3-pentenonitrile by isomerization reaction according to claim 1, characterized in that, The nitrogen content in the polyvinylpyridine porous microspheres is 1% to 10% by mass.

7. The method for preparing 3-pentenonitrile by isomerization reaction of 2-pentenonitrile according to claim 1, characterized in that, In the polyvinylpyridine porous microspheres, the particle size of the polystyrene porous microspheres is 50nm-100nm; And / or, the BET specific surface area of ​​the polyvinylpyridine porous microspheres is 50 m². 2 / g-400m 2 / g, with an average pore size of 10nm-40nm.

8. The method for preparing 3-pentenonitrile by isomerization reaction according to claim 1, characterized in that, When the isomerization reaction is carried out in a fixed-bed reactor, the mass hourly space velocity (WHSV) of the 2-pentenonitrile is 0.2 h⁻¹. -1 -0.8h -1 ; And / or, the isomerization reaction temperature is 100℃-180℃; And / or, the pressure of the isomerization reaction is 0.1 MPa-0.5 MPa.

9. The method for preparing 3-pentenonitrile by isomerization reaction of 2-pentenonitrile according to claim 1, characterized in that, The polystyrene porous microspheres have an average degree of polymerization of 4800-9600, and the polyvinylpyridine polymer has an average degree of polymerization of 100-500.

10. The method for preparing 3-pentenonitrile by isomerization reaction of 2-pentenonitrile according to any one of claims 1 to 9, characterized in that, After the isomerization reaction is completed, the process also includes recovering the polyvinylpyridine porous microspheres and recycling them for catalyzing the isomerization reaction of 2-pentenonitrile to prepare 3-pentenonitrile.

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