A method for continuously hydrogenating terephthalonitrile to 4-phenylenediamine using a nickel-based catalyst regulated by a local electronic environment

Abstract

The present invention belongs to the field of industrial catalysis technology and discloses a method for the continuous hydrogenation of terephthalonitrile to produce p-phenylenediamine using a nickel-based catalyst regulated by a localized electron environment. Using the nickel-based catalyst regulated by a localized electron environment, the method achieves efficient and continuous hydrogenation of terephthalonitrile to produce p-phenylenediamine under alkali-free conditions. According to the method of the present invention, under mild, alkali-free reaction conditions, the conversion rate of terephthalonitrile reaches 100%, and the selectivity for p-phenylenediamine reaches 98%. The catalyst exhibits excellent hydrogenation performance, addresses the problems of low yield and harsh reaction conditions in the chemical synthesis of p-phenylenediamine, and has good economic benefits and industrial application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial catalysis and relates to a method for continuously hydrogenating terephthalonitrile to purify p-phenylenediamine by a nickel-based catalyst regulated by a local electronic environment. Background Art

[0002] Polyamides are a staple of everyday life, found in clothing, car seats, carpets, and other applications. Furthermore, in the engineering plastics sector, they can be used to manufacture high-precision components in aerospace, automotive, electronics, and machinery. Para-xylylenediamine (p-xylylenediamine) is a key chemical precursor for the downstream, high-value-added polyamide industry. Its production capacity directly impacts the development of downstream industries. The hydrogenation of terephthalonitrile (PDN) is a representative process for synthesizing PDN. However, due to the presence of two unsaturated cyano groups in its molecular structure, the hydrogenation process is significantly more complex than that of single-cyano compounds. During the hydrogenation process, PDN undergoes partial hydrogenation to form 4-cyanobenzylamine. This intermediate, 4-cyanobenzylamine, is then further hydrogenated to form the target product, PDN. Furthermore, the hydrogenation of the cyano group can generate an imine intermediate, whose nucleophilic amino group attacks the carbonium ion of the imine intermediate, resulting in a condensation reaction. Therefore, improving hydrogenation activity and suppressing byproduct formation are key to achieving high selectivity for PDN.

[0003] In industrial applications, Raney-type catalysts exhibit excellent hydrogenation activity in the hydrogenation of nitrile compounds. However, to improve the selectivity of primary amines, it is necessary to use essential alkaline reagents or high-pressure ammonia. In addition, this type of catalyst also has problems such as easy spontaneous combustion, poor catalyst stability and difficulty in separation. Later, a series of homogeneous catalysts for nitrile hydrogenation were reported. Bagal et al. (Advanced Synthesis Catalysis, 2015, 357(5):883-900) used homogeneous catalysts such as Ru, Rh, and Ir in the nitrile hydrogenation reaction, which can achieve a primary amine selectivity of about 85%. However, the price of precious metals used in this type of catalyst is generally expensive, and complex ligands are required in the synthesis process. The catalyst recovery and reuse operations are complicated, which limits the large-scale industrial application of this type of catalyst.

[0004] Chinese patent CN 112973676 A discloses a method for preparing a supported porous nanoplatinum catalyst. This catalyst is capable of catalyzing the hydrogenation of terephthalonitrile under mild reaction conditions. Under the conditions of a reaction temperature of 80°C, a hydrogen pressure of 4 MPa, and a reaction time of 3 hours, the catalyst achieved an optimal conversion of terephthalonitrile of 92.13% and a selectivity for p-phenylenediamine of 65.68%. Compared to homogeneous catalysts, this supported porous nanoplatinum catalyst offers the advantages of easy separation and reuse. However, the use of precious metal platinum as the active component of the catalyst still presents the problem of high cost; furthermore, the catalyst yield of p-phenylenediamine is relatively low.

[0005] Chinese patent CN101768083A discloses a method for preparing xylylenediamine using a supported nickel-based catalyst to hydrogenate isophthalonitrile. The use of non-precious nickel as the active component effectively overcomes the high cost of precious metals. However, the catalyst produces a high content of 3-cyanobenzylamine in the partially hydrogenated product during the later stages of application, making continuous hydrogenation to produce m-xylylenediamine impossible.

[0006] Chinese patent CN 117205923 A discloses a nitrogen-doped carbon-coated catalyst, its preparation method, and a method for preparing m-xylylenediamine from m-phthalonitrile. The nitrogen-doped carbon-coated catalyst provided in this invention can significantly improve the selectivity and yield of m-xylylenediamine under relatively mild reaction conditions. However, the introduction of an alkaline inhibitor into the reaction system places high demands on the corrosion resistance of the equipment.

[0007] Chinese patents CN 108084035 A and CN 109647419 A disclose a coprecipitation-prepared alumina-supported nickel catalyst modified with alkaline earth metal oxides and rare earth metal oxides, achieving high adiponitrile conversion and high selectivity for the target product, hexamethylenediamine. The introduction of the alkaline earth metal increases the surface basicity of the catalyst, favoring the production of hexamethylenediamine. However, the addition of an alkaline earth metal to modify the catalyst to adjust product yield ignores the fact that rare earth metals can also achieve similar effects as alkaline earth metals through structural and local electronic environment regulation.

[0008] In summary, there is still considerable room for research in the development and design of catalysts for the continuous hydrogenation of phthalonitrile to p-xylylenediamine. Given the current state of research, it is crucial to develop a low-cost, liquid-phase hydrogenation catalyst for terephthalonitrile with excellent hydrogenation performance, enabling high conversion rates and selectivity to the target product under mild, alkaline-free reaction conditions. Summary of the Invention

[0009] The present invention provides a method for continuously hydrogenating terephthalonitrile to purify p-xylylenediamine. The method utilizes a nickel-based catalyst with a localized electronic environment to efficiently catalyze the hydrogenation of terephthalonitrile, thereby resolving the problems of low yield and harsh reaction conditions in the chemical synthesis of p-xylylenediamine.

[0010] The technical solution of the present invention:

[0011] A method for continuously hydrogenating terephthalonitrile to prepare p-xylylenediamine by a nickel-based catalyst regulated by a local electronic environment, comprising the following steps:

[0012] (1) Preparation of nickel-based catalysts regulated by local electronic environment

[0013] The carbon-based material, rare earth metal ion salt, and Ni ion salt were added to a DMF solvent and mixed, and the mixture was placed at 150°C for 24 hours to obtain a catalyst precursor powder; the catalyst precursor powder was pyrolyzed in an argon atmosphere at 800°C for 4 hours to derive a nickel-based catalyst with a localized electronic environment;

[0014] (2) Continuous hydrogenation of terephthalonitrile to produce p-phenylenediamine

[0015] A terephthalonitrile solution with a mass concentration of 1% to 50% is prepared; the terephthalonitrile solution and a nickel-based catalyst with a localized electronic environment are placed in a kettle reactor, and hydrogen is introduced simultaneously to catalytically hydrogenate terephthalonitrile to produce p-phenylenediamine at a reaction temperature of 70 to 120° C. and a reaction pressure of 1 to 8 MPa.

[0016] The carbon-based material is one or a combination of two or more of trimesic acid, terephthalic acid, and 2,5-dihydroxyphthalic acid.

[0017] The rare earth metal ion salt is a metal La ion salt and / or a metal Ce ion salt; the rare earth metal ion salt is all nitrate.

[0018] The molar ratio of the rare earth metal ion salt to the Ni ion salt is 1:(1-10); the molar ratio of the carbon-based material to the Ni ion salt is (1-10):1.

[0019] The mass ratio of terephthalonitrile to the nickel-based catalyst controlled by the local electronic environment is 5 to 50.

[0020] The solvent used to prepare the terephthalonitrile solution is one or a mixture of two or more of toluene, ethanol and tetrahydrofuran.

[0021] During the pyrolysis process, the decomposition of the oxygen-containing organic carbon matrix and the reduction of the metal nickel occur simultaneously. The monomer structure of the oxygen-containing organic carbon matrix contains a benzene ring. Under high temperature, the skeleton of the oxygen-containing organic carbon matrix collapses and the organic carbon matrix evolves into amorphous carbon. The collapse of the skeleton causes the shared electron pair on the benzene ring to undergo electron migration, achieving the gradual reduction of Ni in a non-reducing atmosphere. δ+ Reduced to nickel metal nanoparticles. The first ionization energy of La (538.1kJ / mol) and Ce (534.4kJ / mol) is lower than that of Ni (737.1kJ / mol). The stronger the ability of an atom to lose electrons, the stronger its reducibility. During the pyrolysis process, La and Ce will preferentially combine with the oxygen element in the oxygen-containing organic carbon matrix to form corresponding oxides. La and Ce lose electrons when combined with oxygen, and the electrons migrate from the metal and carbon interface to the surface of the nickel metal nanoparticles to form Ni sites with an electron-rich structure, which directly improves the hydrogenation ability of the catalyst. On the other hand, according to the Lewisite acid-base theory, La with electronic ability will induce the formation of alkaline sites on the catalyst surface, directly improving the yield of the product in the catalytic process. In general, the present invention originally designed a method for continuously hydrogenating terephthalonitrile to refine p-phenylenediamine using a nickel-based catalyst regulated by a local electronic environment.

[0022] Beneficial effects of the present invention: The present invention provides a method for the continuous hydrogenation of terephthalonitrile to produce p-phenylenediamine using a nickel-based catalyst regulated by a localized electron environment. The method optimizes the nickel-based catalyst by controllably inducing local electron migration of rare earth metal oxides, thereby achieving a process of efficient and continuous hydrogenation of terephthalonitrile to produce p-phenylenediamine. The rare earth metal oxide transfers electrons to the active nickel component, optimizing the electronic environment of the active nickel center and improving the ability to convert terephthalonitrile. Furthermore, according to Lewis acid-base theory, the rare earth metal oxide acts as an electron donor to derive Lewis basic sites, effectively improving the selectivity for p-phenylenediamine in the absence of alkali reagents. According to the method of the present invention, in some embodiments, under mild, alkali-free reaction conditions, the conversion rate of terephthalonitrile reaches 100%, and the selectivity for p-phenylenediamine can reach 98%. The catalyst has excellent hydrogenation performance and good economic benefits and industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the transmission electron microscope (TEM) image of the Ni-CeO2@C-1 catalyst in Example 5. DETAILED DESCRIPTION

[0024] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0025] Example 1:

[0026] 10 mmol of terephthalic acid, 1 mmol of metal La ion salt and 10 mmol of metal Ni ion salt were added to 80 mL of DMF and mixed, and placed at a temperature of 150°C for 24 hours to obtain a catalyst precursor; the catalyst precursor powder was pyrolyzed in an argon atmosphere at 800°C for 4 hours to derive Ni-La2O3@C-1.

[0027] Example 2-4:

[0028] The conditions were the same as those in Example 1, except that the amount of the metal La ion salt was changed to 3 mmol, 5 mmol, and 10 mmol, respectively, to obtain Ni-La2O3@C-2, Ni-La2O3@C-3, and Ni-La2O3@C-4.

[0029] Example 5:

[0030] 10 mmol of terephthalic acid, 1 mmol of metal Ce ion salt and 10 mmol of metal Ni ion salt were added to 80 mL of DMF and mixed, and placed at a temperature of 150°C for 24 hours to obtain a catalyst precursor; the catalyst precursor powder was pyrolyzed in an argon atmosphere at 800°C for 4 hours to derive Ni-CeO2@C-1.

[0031] Examples 6-8:

[0032] The conditions were the same as those in Example 5, except that the amount of the metal Ce ion salt was changed to 3 mmol, 5 mmol, and 10 mmol, respectively, to obtain Ni-CeO2@C-2, Ni-CeO2@C-3, and Ni-CeO2@C-4.

[0033] Example 9:

[0034] 10mmol of terephthalic acid, 3mmol of metal La ion salt, 3mmol of metal Ce ion salt and 10mmol of metal Ni ion salt were added to 80mL of DMF and mixed, and placed at a temperature of 150°C for 24 hours to obtain a catalyst precursor; the catalyst precursor powder was pyrolyzed in an argon atmosphere at 800°C for 4 hours to derive Ni-La2O3-CeO2@C-1.

[0035] Comparative Example 1:

[0036] 10 mmol of terephthalic acid and 10 mmol of metal Ni ion salt were added to 80 mL of DMF and mixed, and placed at a temperature of 150°C for 24 hours to obtain a catalyst precursor; the catalyst precursor powder was pyrolyzed in an argon atmosphere at 800°C for 4 hours to derive Ni@C.

[0037] Comparative Example 2:

[0038] 2.0g of activated carbon was dispersed in a mixed solution of Ni(NO3)2 and La(NO3)2 and stirred at 150°C for 8 hours. The mixture was filtered, washed, and dried to obtain a catalyst precursor. The catalyst precursor powder was pyrolyzed at 800°C in an argon atmosphere for 4 hours to produce Ni-La2O3 / C, with a Ni content of 20% and La of 5% by weight.

[0039] Comparative Example 3:

[0040] 2.0g of activated carbon was dispersed in a mixed solution of Ni(NO3)2 and Ce(NO3)2 and stirred at 150°C for 8 hours. The mixture was filtered, washed, and dried to obtain a catalyst precursor. The catalyst precursor powder was pyrolyzed at 800°C in an argon atmosphere for 4 hours to produce Ni-CeO2 / C, with a Ni content of 20% and Ce content of 5% by weight.

[0041] Comparative Example 4:

[0042] 2.0g of activated carbon was dispersed in a mixed solution of Ni(NO3)2, La(NO3)2, and Ce(NO3)2 and stirred at 150°C for 8 hours. The resulting catalyst precursor was filtered, washed, and dried. The catalyst precursor powder was pyrolyzed at 800°C in an argon atmosphere for 4 hours to produce Ni-CeO2 / C, with a Ni content of 20% by mass and La and Ce content of 5% each.

[0043] Comparative Example 5:

[0044] 10 mmol of terephthalic acid, 1 mmol of metal La ion salt and 10 mmol of metal Ni ion salt were added to 80 mL of DMF and mixed, and placed at a temperature of 150°C for 24 hours to obtain a catalyst precursor; the catalyst precursor powder was pyrolyzed in an oxygen atmosphere at 800°C for 4 hours to derive Ni-La2O3-1.

[0045] Comparative Example 6:

[0046] The conditions are the same as those of Comparative Example 5, except that Ni-La2O3-1 is reduced in a hydrogen atmosphere at 400°C for 4 hours to obtain Ni-La2O3-2.

[0047] The nickel-based catalyst with controlled local electronic environment, a terephthalonitrile solution and hydrogen are introduced into a tank reactor to generate p-phenylenediamine under mild reaction conditions; the reaction temperature is 70-120° C.; the reaction pressure is 1-8 MPa; the substrate to catalyst ratio is 5-50, and the reaction results are quantitatively analyzed by gas chromatography.

[0048] Table 1 Effect of different catalysts on catalytic activity in the examples

[0049]

[0050] As shown in the reaction results in Table 1, at a reaction temperature of 90°C, a hydrogen pressure of 4 MPa, and a reaction time of 4 h, the nickel-based catalysts with localized electron environment control in Examples 1-9 can achieve a 100% conversion rate of terephthalonitrile, with no partial hydrogenation product 4-cyanobenzylamine and a high yield of p-phenylenediamine, with the highest p-phenylenediamine yield reaching 98%. The results of Comparative Example 1 show that the performance of the nickel-based catalyst without the introduction of La or Ce is significantly inferior to that of the nickel-based catalyst with localized electron environment control. At the same time, in Comparative Examples 2-4, the conversion rate of terephthalonitrile obtained by the nickel-based catalysts obtained using an oxygen-free carbon matrix does not exceed 25%, and the nickel-based catalyst obtained by pyrolysis in an oxygen atmosphere in Comparative Example 5 does not convert terephthalonitrile. Comparative Example 6 further undergoes catalyst reduction treatment, and the nickel-based catalyst terephthalonitrile conversion rate is only 29.3%, and the p-phenylenediamine yield is 47.1%. In summary, the nickel-based catalyst with local electronic environment regulation in the present invention achieves continuous hydrogenation of terephthalonitrile and high selectivity for p-phenylenediamine under mild alkali-free conditions.

[0051] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments, and the substrate molecule may also be other aromatic nitrile compounds and straight-chain nitrile compounds. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for continuously hydrogenating terephthalonitrile to prepare p-xylylenediamine using a nickel-based catalyst regulated by a local electronic environment, characterized in that: Here are the steps: (1) Preparation of nickel-based catalysts regulated by local electronic environment The carbon-based material, rare earth metal ion salt, and Ni ion salt were added to a DMF solvent and mixed, and the mixture was placed at 150°C for 24 hours to obtain a catalyst precursor powder; the catalyst precursor powder was pyrolyzed in an argon atmosphere at 800°C for 4 hours to derive a nickel-based catalyst with a localized electronic environment; The carbon-based material is one or a combination of two or more of trimesic acid, terephthalic acid, and 2,5-dihydroxyphthalic acid; The rare earth metal ion salt is a metal La ion salt and / or a metal Ce ion salt; the rare earth metal ion salt is a nitrate; (2) Continuous hydrogenation of terephthalonitrile to produce p-phenylenediamine A terephthalonitrile solution with a mass concentration of 1% to 50% is prepared; the terephthalonitrile solution and a nickel-based catalyst with a localized electronic environment are placed in a kettle reactor, and hydrogen is introduced simultaneously to catalytically hydrogenate terephthalonitrile to produce p-phenylenediamine at a reaction temperature of 70 to 120° C. and a reaction pressure of 1 to 8 MPa.

2. The method according to claim 1, characterized in that The molar ratio of the rare earth metal ion salt to the Ni ion salt is 1:(1-10); the molar ratio of the carbon-based material to the Ni ion salt is (1-10):

1.

3. The method according to claim 1, characterized in that The mass ratio of terephthalonitrile to the nickel-based catalyst controlled by the local electronic environment is 5 to 50.

4. The method according to claim 1, wherein The solvent used to prepare the terephthalonitrile solution is one or a mixture of two or more of toluene, ethanol and tetrahydrofuran.

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