Process for preparing butanediamine by utilizing acrylonitrile and hydrocyanic acid through one-pot method
By integrating hydrocyanation and hydrogenation reactions in the same reactor, and utilizing composite catalysts and optimized conditions, the problems of lengthy, complex, and costly butanediamine preparation processes have been solved, achieving efficient and safe butanediamine production.
Patent Information
- Application Number
- CN202610241520.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-28
- Publication Date
- 2026-05-15
AI Technical Summary
The existing process for preparing butanediamine is lengthy, complex, and costly. In particular, the thermal instability of butanedionitrile increases equipment investment, energy consumption, and material loss during the intermediate separation and purification process.
A one-pot process using acrylonitrile and hydrogen cyanide is employed, where the hydrocyanation and hydrogenation reactions are carried out in the same reactor, omitting the intermediate separation step. Composite catalysts, such as core-shell structured nickel, palladium, or copper zero-valent metal complexes and supported metal catalysts, are used, and reaction conditions, such as temperature and pressure, are optimized to achieve continuous operation.
It simplifies the production process, improves atom economy and overall yield, reduces equipment investment and energy consumption, enhances production efficiency and safety, and shortens the production cycle.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of organic chemical synthesis technology, specifically to a process for preparing butanediamine using a one-pot method with acrylonitrile and hydrogen cyanide. Background Technology
[0002] 1,4-Butanediamine is a key monomer for the synthesis of high-performance nylon, polyamides, and specialty chemicals, and its market demand continues to grow with the expansion of the high-end materials industry. However, the large-scale production of 1,4-butanediamine and its core precursors in my country has long faced technological bottlenecks. Therefore, developing an efficient, simple, and safe process route is of great significance.
[0003] Currently, the acrylonitrile route used in industry and mainstream research to synthesize butanediamine typically employs a two-step method: first synthesizing butanedionitrile, followed by hydrogenation reduction. Specifically, acrylonitrile first undergoes a hydrocyanation reaction with hydrogen cyanide in the presence of a catalyst, such as a homogeneous base catalyst, to generate the intermediate butanedionitrile. Subsequently, the reaction mixture undergoes complex separation and purification processes, usually involving multi-stage distillation, to separate the butanedionitrile from the reaction solution with high purity. The purified butanedionitrile is then transferred to another hydrogenation reactor for reduction under a hydrogen atmosphere and in the presence of a dedicated hydrogenation catalyst, ultimately yielding the target product, butanediamine.
[0004] However, succinic anhydride, as a relatively chemically reactive intermediate, suffers from poor thermal stability. During subsequent distillation and purification, it is prone to polymerization and decomposition side reactions upon heating. This not only leads to yield losses of the target intermediate but also necessitates extremely precise and strict control of distillation operating conditions, increasing process complexity and operational difficulty. More importantly, the separation step of succinic anhydride makes the entire process lengthy and uneconomical: it requires additional specialized separation equipment, increasing fixed asset investment and energy consumption, ultimately translating material losses and energy consumption into high production costs.
[0005] Therefore, a more streamlined process for synthesizing butanediamine is needed. Summary of the Invention
[0006] (a) Technical problems to be solved
[0007] To address the problems of lengthy, complex, and costly processes in the preparation of butanediamine in existing technologies, this invention provides a process for preparing butanediamine using a one-pot method with acrylonitrile and hydrogen cyanide.
[0008] (II) Technical Solution
[0009] To achieve the above objectives, the main technical solutions adopted by the present invention include:
[0010] This invention provides a process for preparing butanediamine using a one-pot method with acrylonitrile and hydrogen cyanide, comprising the following steps:
[0011] Acrylonitrile, hydrogen cyanide, a hydrocyanation catalyst, and a hydrogenation catalyst are placed in the same reactor. First, under a nitrogen atmosphere, acrylonitrile and hydrogen cyanide undergo a hydrocyanation addition reaction in the presence of the hydrocyanation catalyst to generate butadiene nitrile intermediate. Then, without separation, hydrogen is added to the reaction system to increase the pressure, followed by a catalytic hydrogenation reaction in the presence of the hydrogenation catalyst. After separation, butadiene diamine is obtained.
[0012] In the process described above for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot method, preferably, the hydrocyanation catalyst is selected from zero-valent metal complexes of nickel, palladium, or copper, wherein the active metal is a zero-valent metal of nickel, palladium, or copper, and the organic ligand is a phosphite, diarylphosphine, or bidentate nitrogen.
[0013] In the process described above for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot method, preferably, the hydrogenation catalytic component is a supported metal catalyst, wherein the active metal is Raney nickel, palladium or platinum, and the support is alumina, silica or activated carbon.
[0014] In the process described above for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot method, preferably, the hydrocyanation catalyst component and the hydrogenation catalyst component are formed into a composite catalyst through chemical bonding or physical coating.
[0015] In the process described above for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot method, preferably, the composite catalyst has a core-shell structure, wherein the hydrogenation catalytic component is the core and the hydrogenation catalytic component is the shell.
[0016] In the process described above for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot reaction, preferably, the temperature of the hydrocyanation addition reaction is 30-100℃, and the reaction temperature of the catalytic hydrogenation reaction is 80-150℃.
[0017] In the process described above for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot reaction, preferably, the reaction pressure in the hydrocyanation addition reaction stage is ≤0.15 MPa, and the reaction pressure in the catalytic hydrogenation reaction stage is 0.1-0.5 MPa.
[0018] In the process described above for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot reaction, preferably, the molar ratio of acrylonitrile to hydrogen cyanide is 1:0.9-1:1.2, the total reaction time is 13-24 h, wherein the time for the hydrocyanation addition reaction is 5-8 h, and the time for the catalytic hydrogenation reaction is 8-16 h.
[0019] In the process described above for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot reaction, preferably, the entire reaction process is carried out in a solvent environment, wherein the solvent is a protic solvent.
[0020] In the process described above for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot method, preferably, the solvent is a C1-C4 alcohol.
[0021] (III) Beneficial Effects
[0022] The one-pot process provided by this invention integrates hydrocyanation and hydrogenation steps within a single reactor, avoiding the separation and processing of intermediate products, and bringing about several significant benefits:
[0023] First, the process of this invention fundamentally simplifies the production flow. Since the succinic acid intermediate generated by the hydrocyanation reaction does not require complex separation and purification, but is directly subjected to subsequent hydrogenation within the same reactor, the intermediate distillation unit and corresponding material transfer system required in traditional processes are eliminated. This significantly shortens the process flow, substantially reduces equipment investment and plant floor space, and the simplified operating steps also directly reduce energy consumption and labor costs.
[0024] Secondly, the process of this invention effectively avoids material losses caused by the separation and purification of butadienenitrile intermediates. The thermal instability of butadienenitrile means that it is prone to decomposition or polymerization during distillation, leading to a loss in the yield of the target product. This invention, by omitting this separation step, allows the intermediate to be converted into the final product in situ and promptly, thereby reducing the chance of side reactions and improving the overall atom economy and total yield from the raw material acrylonitrile to the product butadienenitrile.
[0025] Third, the continuous operation mode of this invention significantly shortens the production cycle. Traditional segmented processes involve a large amount of non-productive waiting time between reaction batches, such as cooling, separation, material transfer, and reheating. This invention seamlessly connects the two reaction stages within the same device, eliminating these intermediate steps and thus greatly improving production efficiency and the unit's capacity per unit time. Detailed Implementation
[0026] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to specific embodiments.
[0027] This invention provides a process for preparing butanediamine using a one-pot method with acrylonitrile and hydrogen cyanide, comprising the following steps:
[0028] Acrylonitrile, hydrogen cyanide, a hydrocyanation catalyst, and a hydrogenation catalyst are placed in the same reactor. First, under a nitrogen atmosphere, acrylonitrile and hydrogen cyanide undergo a hydrocyanation addition reaction in the presence of the hydrocyanation catalyst to generate a succinic acid intermediate. Then, without separation, hydrogen is added to the reaction system to increase the pressure, followed by a catalytic hydrogenation reaction in the presence of the hydrogenation catalyst. After separation, butanediamine is obtained (1,4-butanediamine is obtained in this invention).
[0029] The one-pot process provided by this invention integrates hydrocyanation and hydrogenation steps within a single reactor, avoiding the separation and processing of intermediate products, and bringing about several significant benefits:
[0030] First, the process of this invention fundamentally simplifies the production flow. Since the succinic acid intermediate generated by the hydrocyanation reaction does not require complex separation and purification, but is directly subjected to subsequent hydrogenation within the same reactor, the intermediate distillation unit and corresponding material transfer system required in traditional processes are eliminated. This significantly shortens the process flow, substantially reduces equipment investment and plant floor space, and the simplified operating steps also directly reduce energy consumption and labor costs.
[0031] Secondly, the process of this invention effectively avoids material losses caused by the separation and purification of butadienenitrile intermediates. The thermal instability of butadienenitrile means that it is prone to decomposition or polymerization during distillation, leading to a loss in the yield of the target product. This invention, by omitting this separation step, allows the intermediate to be converted into the final product in situ and promptly, thereby reducing the chance of side reactions and improving the overall atom economy and total yield from the raw material acrylonitrile to the product butadienenitrile.
[0032] Third, the continuous operation mode of this invention significantly shortens the production cycle. Traditional segmented processes involve a large amount of non-productive waiting time between reaction batches, such as cooling, separation, material transfer, and reheating. This invention seamlessly connects the two reaction stages within the same device, eliminating these intermediate steps and thus greatly improving production efficiency and the unit's capacity per unit time.
[0033] This invention concentrates the entire reaction process within a closed reaction system, eliminating the need for highly toxic hydrogen cyanide feedstock and the reactive intermediate succinate to be exposed to the external environment or transferred between equipment. This significantly reduces the risk of leakage, volatilization, or contact with personnel of toxic and hazardous substances during operation, thereby substantially improving the safety of the entire production process.
[0034] In summary, this invention, through integrated innovation of the process route, successfully solves the problems of lengthy processes, complex operations, high costs, and safety challenges in existing technologies, providing a novel and highly valuable industrial solution for the efficient, economical, and safe production of butanediamine.
[0035] The reactor used in this invention is preferably a reaction vessel with a circulation system.
[0036] Preferably, the hydrocyanation catalyst component in this invention is selected from zero-valent metal complexes of nickel, palladium, or copper, wherein the active metal is a zero-valent metal of nickel, palladium, or copper, and the organic ligand is a phosphite, a diarylphosphine, or a bidentate nitrogen.
[0037] The nickel, palladium, or copper metal centers selected in this invention possess intrinsically high catalytic activity and selectivity for hydrocyanation reactions. In particular, nickel-based and palladium-based catalysts are more effective in such reactions. The organic ligands chosen are phosphites, diarylphosphine, or bidentate nitrogen ligands, primarily to adjust the electron cloud density and steric hindrance of the central metal, thereby precisely controlling its catalytic performance: on the one hand, enhancing the catalyst's stability in the reaction medium and preventing premature deactivation; on the other hand, improving its selectivity for the target hydrocyanation reaction pathway, suppressing side reactions such as acrylonitrile dimerization, and providing a purer source of butadienenitrile intermediates for subsequent steps.
[0038] Preferably, the hydrogenation catalytic component in this invention is a supported metal catalyst, wherein the active metal is Raney nickel, palladium, or platinum, and the support is alumina, silica, or activated carbon. Raney nickel, palladium, or platinum exhibit high efficiency and reliability in the hydrogenation of nitrile groups to amino groups. Raney nickel is inexpensive and highly active, while noble metal catalysts such as palladium and platinum exhibit excellent selectivity and milder reaction conditions under specific conditions. Choosing alumina, silica, or activated carbon as the support not only provides a high specific surface area to disperse the active metal and improve its utilization, but also enhances the mechanical strength and thermal stability of the catalyst, enabling it to withstand the thermal stress brought about by the temperature rise process from the first stage to the second stage in a one-pot process, thus maintaining sustained hydrogenation activity.
[0039] Preferably, the hydrocyanation catalytic component and the hydrogenation catalytic component of the present invention can be combined by physical mixing or chemical bonding, and more preferably by chemical bonding or physical coating to form a composite catalyst. More preferably, the composite catalyst has a core-shell structure, wherein the hydrogenation catalytic component is the core and the hydrocyanation catalytic component is the shell.
[0040] A compact nano-reaction environment can be formed through chemical bonding or physical encapsulation. The succinic acid intermediate generated by the hydrocyanation reaction can diffuse over a very short distance to the adjacent hydrogenation active site, achieving instantaneous conversion and minimizing the accumulation of unstable intermediates and the chance of side reactions in the reaction system, thus potentially improving the yield of butanediamine. Furthermore, the core-shell structured composite catalyst provides a physical model for programmed reaction control: the reactants acrylonitrile and hydrocyanic acid first undergo hydrocyanation in the outer shell to generate succinic acid, which then diffuses to the core for hydrogenation. This structure helps to spatially separate the two reactions, potentially optimizing the reaction sequence at the molecular level, reducing interference between the two catalytic cycles, and improving overall catalytic efficiency and selectivity.
[0041] Furthermore, to ensure efficient transport of intermediates, the outer shell of the composite catalyst must possess a suitable porous structure. If the outer shell is a completely dense coating, mass transfer between reactants and intermediates will be significantly restricted, making it difficult for hydrocyanation products to access the inner hydrogenation active sites, thus preventing the synergistic effect of the core-shell structure from being realized. By constructing a porous outer shell, not only can sufficient active interfaces be provided for the hydrocyanation reaction, but continuous diffusion channels can also be formed, allowing the generated succinic anionylene to diffuse smoothly into the inner core and ensuring that hydrogen and other hydrogenation reactants can permeate to the internal active sites.
[0042] Preferably, the molar ratio of acrylonitrile to hydrogen cyanide is 1:0.9-1:1.2, and the total reaction time is 13-24 h, of which the hydrocyanation addition reaction takes 5-8 h and the catalytic hydrogenation reaction takes 8-16 h. The temperature of the hydrocyanation addition reaction is 30-100℃, and the reaction temperature of the catalytic hydrogenation reaction is 80-150℃. The reaction pressure during the hydrocyanation addition reaction stage is ≤0.1 MPa, and the reaction pressure during the catalytic hydrogenation reaction stage is 0.1-0.5 MPa.
[0043] In this invention, a lower temperature is used in the hydrocyanation stage, while a higher temperature is used in the hydrogenation stage. The lower temperature promotes selectivity in the hydrocyanation reaction and inhibits the polymerization of acrylonitrile at high temperatures. Increasing the temperature after the formation of butadionitrile effectively activates the hydrogenation catalyst, accelerating the kinetically slow process of complete hydrogenation of the nitrile group. The initial lower hydrogen pressure helps to preferentially induce hydrocyanation, preventing the direct over-hydrogenation of acrylonitrile to produce byproducts such as propylamine. The later increase in hydrogen pressure provides sufficient reaction driving force for the deep hydrogenation of the butadionitrile intermediate, ensuring its complete conversion to butadiamine. This combined staged control of temperature and pressure is the core process guarantee for achieving efficient and orderly connection of the two-step reaction using only a single reactor.
[0044] Preferably, the entire reaction process of the present invention is carried out in a solvent environment, and the solvent is preferably a protic solvent, more preferably a C1-C4 alcohol, such as methanol.
[0045] The use of protic solvents, such as C1-C4 alcohols, is to accommodate the different requirements of the two reaction steps. Protic solvents, especially alcohols, often promote the reaction during the hydrogenation stage and help dissolve the amine products formed. The solvent system maintains a homogeneous and stable phase throughout the reaction process, avoiding problems such as catalyst precipitation, reduced activity, or phase separation caused by abrupt changes in solvent properties, thus ensuring a smooth transition and continuous progress of the reaction process from the first stage to the second stage.
[0046] Considering the yield performance, the one-pot process provided by this invention demonstrates outstanding performance. By avoiding the separation and purification steps of the unstable intermediate succinate, this invention fundamentally eliminates the inherent yield losses caused by thermally induced side reactions such as polymerization and decomposition in traditional processes. Therefore, even without considering other optimization factors, this invention has the potential to achieve a higher theoretical yield than the traditional two-step method. In practical applications, even if the final single-pass yield of butanediamine is similar to that of the optimized traditional process, the complete elimination of intermediate processing steps significantly improves overall atom economy and production efficiency, further reducing raw material consumption and overall costs per unit product. This indicates that this process achieves a better balance between pursuing higher yields and superior economics.
[0047] To further clarify the present invention and its technological advancements, the following description is provided in conjunction with specific embodiments and technical effects.
[0048] Example 1
[0049] This embodiment provides a process for preparing butanediamine using a one-pot method with acrylonitrile and hydrogen cyanide, comprising the following steps:
[0050] Acrylonitrile, hydrogen cyanide, a hydrocyanation catalyst, a hydrogenation catalyst, and a solvent were placed in a sealed reactor. First, under a nitrogen atmosphere and in the presence of the hydrocyanation catalyst, acrylonitrile and hydrogen cyanide underwent a hydrocyanation addition reaction to generate butadienenitrile intermediate. Then, without separation, hydrogen gas was added to the reaction system to increase the pressure, followed by a catalytic hydrogenation reaction in the presence of the hydrogenation catalyst. After separation, butadiamine was obtained.
[0051] In this embodiment, the hydrocyanation catalytic component is a zero-valent metal complex of nickel, wherein the active metal is elemental nickel and the organic ligand is a phosphite. In this embodiment, the hydrogenation catalytic component is a supported metal catalyst, wherein the active metal is Raney nickel and the support is alumina.
[0052] In this embodiment, the hydrocyanation catalytic component and the hydrogenation catalytic component are chemically bonded to form a composite catalyst. The hydrogenation catalytic component is the core, and the hydrocyanation catalytic component is the shell.
[0053] In this embodiment, the molar ratio of acrylonitrile to hydrogen cyanide is 1:1. The temperature of the hydrocyanation addition reaction is 80°C, and the reaction temperature of the catalytic hydrogenation reaction is 120°C. The reaction pressure of the hydrocyanation addition reaction stage is 0.1 MPa, and the reaction pressure of the catalytic hydrogenation reaction stage is 0.4 MPa. The time of the hydrocyanation addition reaction is 6 h, the time of the catalytic hydrogenation reaction is 14 h, and the total reaction time of the two stages is 20 h.
[0054] The solvent in this embodiment is methanol.
[0055] Example 2
[0056] This embodiment provides a process for preparing butanediamine using a one-pot method with acrylonitrile and hydrogen cyanide, comprising the following steps:
[0057] Acrylonitrile, hydrogen cyanide, a hydrocyanation catalyst, a hydrogenation catalyst, and a solvent are placed in the same sealed reactor. First, under a nitrogen atmosphere and with the action of the hydrocyanation catalyst, acrylonitrile and hydrogen cyanide undergo a hydrocyanation addition reaction to generate butadiene nitrile intermediate. Then, without separation, hydrogen is added to the reaction system to increase the pressure, followed by a catalytic hydrogenation reaction under the action of the hydrogenation catalyst. After separation, butadiene diamine is obtained.
[0058] In this embodiment, the hydrocyanation catalytic component is a zero-valent metal complex of palladium, wherein the active metal is elemental palladium and the organic ligand is diarylphosphine. In this embodiment, the hydrogenation catalytic component is a supported metal catalyst, wherein the active metal is palladium and the support is silica.
[0059] In this embodiment, the hydrocyanation catalytic component and the hydrogenation catalytic component are formed into a composite catalyst through physical coating. The hydrogenation catalytic component is the core, and the hydrocyanation catalytic component is the outer shell.
[0060] In this embodiment, the molar ratio of acrylonitrile to hydrogen cyanide is 1:0.9. The hydrocyanation addition reaction is carried out at 30°C, and the catalytic hydrogenation reaction is carried out at 80°C. The reaction pressure during the hydrocyanation addition reaction is 0.08 MPa, and the reaction pressure during the catalytic hydrogenation reaction is 0.2 MPa. The hydrocyanation addition reaction takes 5 hours, the catalytic hydrogenation reaction takes 8 hours, and the total reaction time for both stages is 13 hours.
[0061] The solvent in this embodiment is ethanol.
[0062] Example 3
[0063] This embodiment provides a process for preparing butanediamine using a one-pot method with acrylonitrile and hydrogen cyanide, comprising the following steps:
[0064] Acrylonitrile, hydrogen cyanide, a hydrocyanation catalyst, a hydrogenation catalyst, and a solvent are placed in the same sealed reactor. First, under a nitrogen atmosphere and with the action of the hydrocyanation catalyst, acrylonitrile and hydrogen cyanide undergo a hydrocyanation addition reaction to generate butadiene nitrile intermediate. Then, without separation, hydrogen is added to the reaction system to increase the pressure, followed by a catalytic hydrogenation reaction under the action of the hydrogenation catalyst. After separation, butadiene diamine is obtained.
[0065] In this embodiment, the hydrocyanation catalytic component is a zero-valent copper metal complex, wherein the active metal is elemental copper and the organic ligand is bidentate nitrogen. In this embodiment, the hydrogenation catalytic component is a supported metal catalyst, wherein the active metal is platinum and the support is activated carbon.
[0066] In this embodiment, the hydrocyanation catalytic component and the hydrogenation catalytic component are formed into a composite catalyst through physical coating. The hydrogenation catalytic component is the core, and the hydrocyanation catalytic component is the outer shell.
[0067] In this embodiment, the molar ratio of acrylonitrile to hydrogen cyanide is 1:1.2. The temperature of the hydrocyanation addition reaction is 100°C, and the reaction temperature of the catalytic hydrogenation reaction is 150°C. The reaction pressure of the hydrocyanation addition reaction stage is 0.09 MPa, and the reaction pressure of the catalytic hydrogenation reaction stage is 0.5 MPa. The time of the hydrocyanation addition reaction is 8 hours, and the time of the catalytic hydrogenation reaction is 16 hours, with a total reaction time of 24 hours.
[0068] The solvent in this embodiment is propanol.
[0069] Example 4
[0070] This embodiment provides a process for preparing butanediamine using a one-pot method with acrylonitrile and hydrogen cyanide, comprising the following steps:
[0071] Acrylonitrile, hydrogen cyanide, a hydrocyanation catalyst, a hydrogenation catalyst, and a solvent are placed in the same sealed reactor. First, under a nitrogen atmosphere and with the action of the hydrocyanation catalyst, acrylonitrile and hydrogen cyanide undergo a hydrocyanation addition reaction to generate butadiene nitrile intermediate. Then, without separation, hydrogen is added to the reaction system to increase the pressure, followed by a catalytic hydrogenation reaction under the action of the hydrogenation catalyst. After separation, butadiene diamine is obtained.
[0072] In this embodiment, the hydrocyanation catalytic component is a zero-valent metal complex of nickel and palladium, wherein the active metal is elemental nickel, and the organic ligand is a mixture of phosphite and bidentate nitrogen in a molar ratio of 2:1. In this embodiment, the hydrogenation catalytic component is a supported metal catalyst, wherein the active metal is Raney nickel, and the support is alumina.
[0073] In this embodiment, the hydrocyanation catalytic component and the hydrogenation catalytic component are formed into a composite catalyst through physical coating. The hydrogenation catalytic component is the core, and the hydrocyanation catalytic component is the outer shell.
[0074] In this embodiment, the molar ratio of acrylonitrile to hydrogen cyanide is 1:1.1. The hydrocyanation addition reaction is carried out at a temperature of 90°C, and the catalytic hydrogenation reaction is carried out at a temperature of 140°C. The reaction pressure during the hydrocyanation addition reaction is 0.1 MPa, and the reaction pressure during the catalytic hydrogenation reaction is 0.5 MPa. The hydrocyanation addition reaction takes 5 hours, the catalytic hydrogenation reaction takes 10 hours, and the total reaction time for both stages is 15 hours.
[0075] The solvent in this embodiment is butanol.
[0076] Example 5
[0077] This embodiment provides a process for preparing butanediamine using a one-pot method with acrylonitrile and hydrogen cyanide, comprising the following steps:
[0078] Acrylonitrile, hydrogen cyanide, a hydrocyanation catalyst, a hydrogenation catalyst, and a solvent are placed in the same sealed reactor. First, under a nitrogen atmosphere and with the action of the hydrocyanation catalyst, acrylonitrile and hydrogen cyanide undergo a hydrocyanation addition reaction to generate butadiene nitrile intermediate. Then, without separation, hydrogen is added to the reaction system to increase the pressure, followed by a catalytic hydrogenation reaction under the action of the hydrogenation catalyst. After separation, butadiene diamine is obtained.
[0079] In this embodiment, the hydrocyanation catalytic component is a zero-valent metal complex of palladium, wherein the active metal is elemental palladium and the organic ligand is a mixture of diarylphosphine and bidentate nitrogen in a molar ratio of 1:1. In this embodiment, the hydrogenation catalytic component is a supported metal catalyst, wherein the active metal is palladium and the support is activated carbon.
[0080] In this embodiment, the hydrocyanation catalytic component and the hydrogenation catalytic component are formed into a composite catalyst through physical coating. The hydrogenation catalytic component is the core, and the hydrocyanation catalytic component is the outer shell.
[0081] In this embodiment, the molar ratio of acrylonitrile to hydrogen cyanide is 1:1.05. The hydrocyanation addition reaction is carried out at 70°C, and the catalytic hydrogenation reaction is carried out at 100°C. The reaction pressure during the hydrocyanation addition reaction is 0.1 MPa, and the reaction pressure during the catalytic hydrogenation reaction is 0.3 MPa. The hydrocyanation addition reaction takes 7 hours, the catalytic hydrogenation reaction takes 12 hours, and the total reaction time for both stages is 19 hours.
[0082] The solvent in this embodiment is ethanol.
[0083] Comparative Example 1
[0084] This comparative example provides a process for preparing butanediamine using acrylonitrile and hydrogen cyanide. First, the hydrocyanation of acrylonitrile is carried out under the same catalyst system and reaction conditions as in Example 1. After the reaction is complete, the reaction mixture is cooled, and the butanedionitrile intermediate is separated by precise vacuum distillation. Subsequently, the purified butanedionitrile is transferred to another hydrogenation reactor, and the same amount of hydrogenation catalyst and solvent as in Example 1 are added again. The hydrogenation reaction is carried out under the same temperature and pressure conditions. The type, amount, and reaction conditions of the hydrocyanation catalyst and hydrogenation catalyst used in Comparative Example 1 are consistent with those in Example 1.
[0085] Comparative Example 2
[0086] This comparative example directly adopts the existing industrially typical two-step process for synthesizing butanediamine using the acrylonitrile method. First, butanedionitrile is prepared by hydrocyanation of acrylonitrile and hydrogen cyanide in the presence of a homogeneous alkaline catalyst. Then, it is subjected to distillation to obtain high-purity butanedionitrile. Next, butanedionitrile is hydrogenated with hydrogen in the presence of a dedicated hydrogenation catalyst to obtain butanediamine.
[0087] The reaction mixtures obtained in Examples 1-5 and Comparative Examples 1-2 were sampled and analyzed, and the results are shown in Table 1.
[0088] Table 1. Statistical table of test results for product mixtures of Examples 1-5 and Comparative Examples 1-2
[0089] As shown in Table 1, the molar yields of butanediamine prepared by the one-pot method in Examples 1-5 were all between 92.8% and 94.8%. In contrast, Comparative Example 1, which strictly simulated the traditional two-step method and included the separation and purification of the intermediate succinate, achieved a yield of 91.5% after consuming a longer total time. This directly demonstrates that the one-pot process of this invention can effectively avoid material losses caused by intermediate separation, purification, and transfer processes, and verifies the significant effect of this invention in improving atom economy and overall product yield.
[0090] Examples 1-5 were all completed continuously in a single reactor, and the total reaction time is the actual chemical reaction time. However, Comparative Example 1, due to the addition of steps such as cooling of the reaction mixture, vacuum distillation separation of the intermediate succinate, material transfer, and reheating and pressurization of the hydrogenation reactor, had a total cycle time of 35 hours. This clearly demonstrates that the present invention significantly shortens the production cycle by omitting non-value-adding separation and transfer steps.
[0091] The acrylonitrile conversion rates in Examples 1-5 were all above 99%, and the residual amount of succinic anhydride in the final product was extremely low, indicating that the one-pot process of the present invention can drive the reaction to proceed completely, and the intermediate succinic anhydride is efficiently converted in situ. Furthermore, GC-MS analysis showed that the byproduct spectra of Examples 1-5 were simple, mainly consisting of trace amounts of propylamine, with no obvious polymerization byproduct peaks. In contrast, Comparative Examples 1 and 2 detected a small amount of dimer impurities in the separated succinic anhydride. This indicates that the continuous reaction mode of the one-pot process reduces the opportunity for the intermediate to be exposed to purification conditions, such as heating, which is beneficial for suppressing side reactions. Comparative Example 2 used a conventional two-step process, first performing a hydrocyanation reaction to generate succinic anhydride, which was then purified by distillation before undergoing a hydrogenation reaction. The results showed that the acrylonitrile conversion rate in the first hydrocyanation reaction reached 99%, and the succinic anhydride yield was approximately 95.0%. However, during the distillation separation process, due to the thermal instability of succinate, approximately 4-5% polymerization and decomposition losses occur, resulting in a final purified succinate yield of about 90% entering the hydrogenation reaction. The second-step hydrogenation reaction is more efficient, with a butanediamine yield reaching 99% (based on purified succinate). However, the overall molar yield from acrylonitrile to butanediamine is only 89.1%, significantly lower than in Examples 1-5. Furthermore, due to the addition of intermediate separation, purification, and material transfer steps, the total process cycle of Comparative Example 2 is extended to 40 hours, much longer than in the examples.
[0092] By combining yield, time, and process analysis, this invention achieves dual optimization of higher yield and shorter production cycle while ensuring high conversion rate and high selectivity. This is thanks to the one-pot method, which fundamentally avoids the main steps that result in yield loss and time consumption in traditional processes, thus solving the technical problems of lengthy, complex, and costly butanediamine preparation processes.
[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A process for preparing butanediamine in a one-pot reaction using acrylonitrile and hydrogen cyanide, characterized in that, Includes the following steps: Acrylonitrile, hydrogen cyanide, a hydrocyanation catalyst, and a hydrogenation catalyst are placed in the same reactor. First, under a nitrogen atmosphere, acrylonitrile and hydrogen cyanide undergo a hydrocyanation addition reaction in the presence of the hydrocyanation catalyst to generate butadiene nitrile intermediate. Then, without separation, hydrogen is added to the reaction system to increase the pressure, followed by a catalytic hydrogenation reaction in the presence of the hydrogenation catalyst. After separation, butadiene diamine is obtained.
2. The process for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot method according to claim 1, characterized in that, The hydrocyanation catalyst component is selected from zero-valent metal complexes of nickel, palladium, or copper, wherein the active metal is a zero-valent metal of nickel, palladium, or copper, and the organic ligand is a phosphite, a diarylphosphine, or a bidentate nitrogen.
3. The process for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot method according to claim 1, characterized in that, The hydrogenation catalytic component is a supported metal catalyst, wherein the active metal is Raney nickel, palladium or platinum, and the support is alumina, silica or activated carbon.
4. The process for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot method according to claim 1, characterized in that, The hydrocyanation catalyst component and the hydrogenation catalyst component are combined to form a composite catalyst through chemical bonding or physical coating.
5. The process for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot method according to claim 4, characterized in that, The composite catalyst has a core-shell structure, with the hydrogenation catalytic component as the core and the hydrocyanation catalytic component as the shell.
6. The process for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot process according to claim 1, characterized in that, The temperature range for hydrocyanation addition reaction is 30-100℃, and the reaction temperature for catalytic hydrogenation reaction is 80-150℃.
7. The process for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot process according to claim 1, characterized in that, The reaction pressure in the hydrocyanation addition reaction stage is ≤0.1MPa, and the reaction pressure in the catalytic hydrogenation reaction stage is 0.1-0.5MPa.
8. The process for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot method according to claim 1, characterized in that, The molar ratio of acrylonitrile to hydrogen cyanide is 1:0.9-1:1.2, and the total reaction time is 13-24 h, of which the time for the hydrocyanation addition reaction is 5-8 h and the time for the catalytic hydrogenation reaction is 8-16 h.
9. The process for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot process according to claim 1, characterized in that, The entire reaction process is carried out in a solvent environment, and the solvent is a protic solvent.
10. The process for preparing butanediamine using acrylonitrile and hydrogen cyanide in a one-pot method according to claim 9, characterized in that, The solvent is a C1-C4 alcohol.