Method for catalyzing continuous hydrofining of p-xylylenediamine from p-phthalonitrile by using nickel-based catalyst regulated and controlled in local electronic environment

Abstract

The invention belongs to the technical field of industrial catalysis, and discloses a method for continuously hydrorefining p-xylylenediamine by catalyzing terephthalonitrile through a nickel-based catalyst regulated and controlled in a local electronic environment. A nickel-based catalyst regulated and controlled by a local electronic environment is adopted, and the process of producing the p-xylylenediamine by efficiently and continuously hydrogenating the terephthalonitrile under an alkali-free condition is realized. According to the method provided by the invention, under mild and alkali-free reaction conditions, the conversion rate of the terephthalonitrile reaches 100%, and the selectivity of the p-xylylenediamine can reach 98%. The catalyst has excellent hydrogenation performance, solves the problems of low yield of chemically synthesized p-xylylenediamine, harsh reaction conditions and the like, 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 preparing p-xylylenediamine by continuous hydrogenation of terephthalonitrile using a nickel-based catalyst regulated by a local electronic environment. Background Art

[0002] Polyamide is a typical product in human daily life and can be used in clothing, car seats, carpets and other fields. In addition, in the field of engineering plastics, it can be used to manufacture high-precision parts in the fields of aerospace, automobiles, electronics, machinery and other fields. p-Xylylenediamine is an important chemical precursor for the production of downstream high-value-added polyamide industry. The production capacity of p-Xylylenediamine directly affects the development of downstream industries. The synthesis of p-Xylylenediamine by hydrogenation of terephthalonitrile is a representative process. However, there are two unsaturated cyano groups in the molecular structure of terephthalonitrile, and the hydrogenation process is much more complicated than that of single cyano compounds. In the hydrogenation process, terephthalonitrile will first undergo partial hydrogenation to generate 4-cyanobenzylamine, and the intermediate product 4-cyanobenzylamine will be further hydrogenated to generate the target product p-Xylylenediamine. In addition, an imine intermediate can be generated in the hydrogenation of the cyano group, and the nucleophilic amino group will attack the carbon cation of the imine intermediate to undergo a condensation reaction. Therefore, improving the hydrogenation activity and inhibiting the formation of by-products are the key to achieving high selectivity of p-Xylylenediamine.

[0003] In industrial applications, Raney-type catalysts show excellent hydrogenation activity in the hydrogenation process of nitrile compounds. However, to improve the selectivity of primary amines, it is necessary to use indispensable 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 need to be used 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 nano-platinum catalyst. The catalyst prepared by the inventive method can catalyze the hydrogenation of terephthalonitrile under mild reaction conditions. Under the conditions of reaction temperature of 80°C, hydrogen pressure of 4Mpa and reaction time of 3h, the optimal conversion rate of terephthalonitrile is 92.13%, and the selectivity of p-phenylenediamine is 65.68%. Compared with homogeneous catalysts, the supported porous nano-platinum catalyst has the advantages of easy separation and reuse. However, the catalyst still has the problem of high price when using precious metal platinum as the active component; on the other hand, the catalyst has a low yield of p-phenylenediamine.

[0005] Chinese patent CN101768083A discloses a method for preparing xylenediamine, which uses a supported nickel-based catalyst to hydrogenate isophthalonitrile. Non-precious metal nickel is used as an active component to effectively overcome the disadvantage of high precious metal costs. However, the content of 3-cyanobenzylamine in the partially hydrogenated product after the catalyst is applied is high, and continuous hydrogenation to produce m-xylenediamine is not possible.

[0006] Chinese patent CN 117205923 A discloses a nitrogen-doped carbon-coated catalyst, a preparation method thereof, and a method for preparing meta-xylylenediamine from isophthalonitrile. The nitrogen-doped carbon-coated catalyst provided by the invention can significantly improve the selectivity and yield of meta-xylylenediamine under relatively mild reaction conditions. However, the introduction of alkaline inhibitors 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 that the alumina-supported nickel catalyst modified by alkaline earth metal oxide and rare earth metal oxide prepared by coprecipitation method can obtain a high conversion rate of adiponitrile and high selectivity of the target product hexamethylenediamine. The introduction of alkaline earth metal increases the surface basicity of the catalyst, which is beneficial to the formation of hexamethylenediamine. However, the additional introduction of alkaline earth metal to adjust the yield of the product for catalyst modification ignores that rare earth metal can also achieve similar effects as alkaline earth metal through the regulation of structure and local electronic environment.

[0008] In summary, there is still a lot of room for research on the development and design of catalysts for the continuous hydrogenation of phthalonitrile to p-xylylenediamine. In view of the current research status, it is of great significance to develop a terephthalonitrile liquid phase hydrogenation catalyst with excellent hydrogenation performance and low price to achieve a high reaction conversion rate and target product selectivity under mild alkali-free reaction conditions. Summary of the invention

[0009] The present invention provides a method for continuously hydrogenating terephthalonitrile to purify p-xylenediamine. The method develops a nickel-based catalyst regulated by a local electronic environment to efficiently catalyze the hydrogenation of terephthalonitrile, thereby solving the problems of low yield and harsh reaction conditions in the chemical synthesis of p-xylenediamine.

[0010] The technical solution of the present invention:

[0011] A method for preparing p-xylylenediamine by continuous hydrogenation of terephthalonitrile using 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 are added to a DMF solvent and mixed, and placed at a temperature of 150°C for 24 hours to obtain a catalyst precursor powder; the catalyst precursor powder is pyrolyzed in an argon atmosphere at 800°C for 4 hours to derive a nickel-based catalyst with local electronic environment regulation;

[0014] (2) Continuous Hydrogenation of Terephthalonitrile to Prepare P-Xylylenediamine

[0015] A terephthalonitrile solution with a mass concentration of 1% to 50% is prepared; the terephthalonitrile solution and a nickel-based catalyst controlled by a local electronic environment are placed in a kettle reactor, and hydrogen is introduced at the same time, and terephthalonitrile is catalytically hydrogenated to generate p-phenylenediamine under the conditions of 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 a 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 regulated by the local electronic environment is 5 to 50.

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

[0021] In the above 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 has a benzene ring. At high temperatures, the skeleton of the oxygen-containing organic carbon matrix collapses, and the organic carbon matrix evolves into amorphous carbon. The skeleton collapse causes the shared electron pairs 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 (538.1 kJ / mol) and Ce (534.4 kJ / mol) is lower than that of Ni (737.1 kJ / 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 will lose electrons when combined with oxygen, and the electrons will migrate from the metal-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 is an original design of a method for the continuous hydrogenation of terephthalonitrile to 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 preparing p-phenylenediamine by continuous hydrogenation of terephthalonitrile catalyzed by a nickel-based catalyst regulated by a local electronic environment, and can controllably induce the local electron migration of rare earth metal oxides to optimize the nickel-based catalyst, thereby realizing the process of efficiently and continuously hydrogenating terephthalonitrile to produce p-phenylenediamine. Rare earth metal oxides transfer electrons to the active nickel component, optimize the electronic environment of the active nickel center, and improve the ability to convert terephthalonitrile. In addition, according to the Lewis acid-base theory, rare earth metal oxides are used as electron donors to derive Lewis basic sites, which effectively improve the selectivity of p-phenylenediamine under the condition of an alkali-free reagent. 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 of p-phenylenediamine can reach 98%. The catalyst has excellent hydrogenation performance and has 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 of 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] Embodiment 1:

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

[0027] Embodiment 2-4:

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

[0029] Embodiment 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 150°C for 24 hours to obtain a catalyst precursor; the catalyst precursor powder was pyrolyzed at 800°C in an argon atmosphere for 4 hours to derive Ni-CeO2@C-1.

[0031] Embodiment 6-8:

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

[0033] Embodiment 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 150°C for 24 hours to obtain a catalyst precursor; the catalyst precursor powder was pyrolyzed at 800°C in an argon atmosphere 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 the mixture was placed at 150° C. for 24 hours to obtain a catalyst precursor; the catalyst precursor powder was pyrolyzed at 800° C. in an argon atmosphere for 4 hours to derive Ni@C.

[0037] Comparative Example 2:

[0038] 2.0g activated carbon was dispersed in a mixed solution of Ni(NO3)2 and La(NO3)2, stirred at a constant temperature of 150℃ for 8 hours, and the catalyst precursor was obtained after filtration, washing and drying. The catalyst precursor powder was pyrolyzed in an argon atmosphere at 800℃ for 4h to derive Ni-La2O3 / C, with a mass percentage of 20% for Ni and 5% for La.

[0039] Comparative Example 3:

[0040] 2.0g activated carbon was dispersed in a mixed solution of Ni(NO3)2 and Ce(NO3)2, stirred at a constant temperature of 150℃ for 8 hours, and the catalyst precursor was obtained after filtration, washing and drying. The catalyst precursor powder was pyrolyzed in an argon atmosphere at 800℃ for 4h to derive Ni-CeO2 / C, with a mass percentage of 20% Ni and 5% Ce in the catalyst.

[0041] Comparative Example 4:

[0042] 2.0g activated carbon was dispersed in a mixed solution of Ni(NO3)2, La(NO3)2 and Ce(NO3)2, stirred at a constant temperature of 150℃ for 8 hours, and the catalyst precursor was obtained after filtration, washing and drying. The catalyst precursor powder was pyrolyzed in an argon atmosphere at 800℃ for 4h to derive Ni-CeO2 / C, with a mass percentage of 20% for the catalyst Ni, and 5% for La and Ce.

[0043] Comparative Example 5:

[0044] 10mmol of terephthalic acid, 1mmol of metal La ion salt and 10mmol of metal Ni ion salt were added to 80mL of DMF and mixed, and placed at 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 controlled by the local electronic environment, a terephthalonitrile solution and hydrogen are introduced into a kettle reactor to generate p-phenylenediamine under mild reaction conditions; the reaction temperature is 70 to 120° C.; the reaction pressure is 1 to 8 MPa; the substrate to catalyst ratio is 5 to 50, and gas chromatography is used to quantitatively analyze the reaction results.

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

[0049]

[0050] It can be seen from the reaction results in Table 1 that at a reaction temperature of 90°C, a hydrogen pressure of 4MPa and a reaction time of 4h, the nickel-based catalysts with local electronic environment regulation in Examples 1-9 can achieve a conversion rate of 100% for terephthalonitrile, no partial hydrogenation product 4-cyanobenzylamine and a high yield of terephthalonitrile dimethylamine, and the highest yield of terephthalonitrile dimethylamine can reach 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 worse than that of the nickel-based catalyst with local electronic environment regulation. At the same time, in Comparative Examples 2-4, the conversion rate of terephthalonitrile obtained by the nickel-based catalyst 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 reduces the catalyst, and the conversion rate of terephthalonitrile of the nickel-based catalyst is only 29.3%, and the yield of terephthalonitrile dimethylamine is 47.1%. In summary, the nickel-based catalyst with local electronic environment regulation in the present invention realizes continuous hydrogenation of terephthalonitrile and high selectivity of p-xylylenediamine under mild alkali-free conditions.

[0051] Above, the embodiments of the present invention have been described. However, the present invention is not limited to the above-mentioned embodiments, and the substrate molecule may also be other aromatic nitrile compounds and straight-chain nitrile compounds. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should all be included in the protection scope of the present invention.

Claims

1. A method for continuously hydrogenating terephthalonitrile to phthalylenediamine 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 are added to a DMF solvent and mixed, and placed at a temperature of 150°C for 24 hours to obtain a catalyst precursor powder; the catalyst precursor powder is pyrolyzed in an argon atmosphere at 800°C for 4 hours to derive a nickel-based catalyst with local electronic environment regulation; (2) Continuous Hydrogenation of Terephthalonitrile to Prepare P-Xylylenediamine A terephthalonitrile solution with a mass concentration of 1% to 50% is prepared; the terephthalonitrile solution and a nickel-based catalyst controlled by a local electronic environment are placed in a kettle reactor, and hydrogen is introduced at the same time, and terephthalonitrile is catalytically hydrogenated to generate p-phenylenediamine under the conditions of 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 carbon-based material is one or a combination of two or more of trimesic acid, terephthalic acid, and 2,5-dihydroxyphthalic acid.

3. The method according to claim 1, characterized in that 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.

4. 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.

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

6. The method according to claim 1, characterized in that The solvent used for preparing the terephthalonitrile solution is one or a mixture of two or more of toluene, ethanol and tetrahydrofuran.

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