Ketoamine reductive alkylation catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalysts, in particular to a preparation method of a ketoamine reductive alkylation catalyst. According to the invention, an intermediate Schiff base of a p-phenylenediamine reaction product generated by a catalytic reaction of a catalyst is used as a confinement agent precursor, and precise pre-embedding treatment is carried out on an invalid pore space in an activated carbon carrier by coupling an oxidative polymerization stabilization technology, so that a post-loaded active metal can be located in an effective catalytic pore space in the carrier; the utilization rate of precious metal components is increased, and the stability and selectivity of the catalyst are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a method for preparing a highly stable catalyst for ketone-amine reduction alkylation reaction and its application in the synthesis reaction of p-phenylenediamine antioxidants. Background Technology

[0002] p-Phenylenediamine antioxidants are an important class of rubber antioxidants, widely used in rubber products such as tires. Typical examples include the antioxidants IPPD (N-isopropyl-N'-phenyl-p-phenylenediamine) and 6PPD (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine). The reductive alkylation process using aromatic amines and ketones as raw materials is currently the main production method for p-phenylenediamine antioxidants. Among these methods, the use of noble metal catalysts to replace traditional copper-based catalysts is a common focus and research direction for both academia and industry.

[0003] Carbon-supported noble metal catalysts are the primary type used in production. The advantages of carbon-supported noble metal catalysts include high catalytic activity, anti-phenylenediamine antioxidants, relatively good selectivity, good chemical stability of the carbon support, and the ability to recover the noble metals after deactivation through simple incineration. Although some literature reports that carbon-supported noble metal catalysts prepared by loading platinum, palladium, and other noble metal active components onto novel nanocarbon supports such as graphene and carbon nanotubes also exhibit good catalytic activity in hydrogenation reactions, the actual production cost of novel nanocarbon materials such as graphene and carbon nanotubes limits their large-scale application. In contrast, activated carbon has a wide range of raw material sources, mature large-scale production technology, and relatively low preparation cost, making it the first choice for carbon supports of noble metal catalysts in industrial production.

[0004] However, in actual pilot-scale tests and production processes, it was found that carbon-supported noble metal catalysts for the ketone-amine reductive alkylation reaction, regardless of whether a batch reactor or a fixed-bed continuous reaction was used, generally suffered from problems such as a low number of catalyst reuses, rapid degradation of catalytic activity, and short lifespan. This significantly increased the catalyst consumption cost per ton of product and severely restricted the widespread application of carbon-supported noble metal catalysts in the synthesis of p-phenylenediamine antioxidants through ketone-amine reductive alkylation. The inventors, through long-term research on the ketone-amine reductive alkylation reaction, discovered that the main reason for the degradation of the activity of carbon-supported noble metal catalysts is that activated carbon supports contain abundant microporous structures. When the most commonly used impregnation method is used for catalyst preparation, a considerable portion of the active metal precursor inevitably adsorbs into the micropores of the carbon support. As some pores of the catalyst are occupied and blocked by organic molecules during the reaction, the active metal sites loaded in the micropores are blocked and cannot continue to contact the reactant molecules, thus losing their catalytic effect. Moreover, the catalytic selectivity of existing activated carbon-supported noble metal catalysts used in the ketone-amine reductive alkylation reaction needs to be improved. Therefore, for ketone-amine reductive alkylation, how to effectively improve the stability and selectivity of the catalyst while ensuring high catalyst activity is an urgent problem to be solved. Summary of the Invention

[0005] To address the aforementioned issues, this invention uses Schiff bases, intermediates of p-phenylenediamine-like reaction products generated by catalyst catalysis, as confinement agent precursors. Coupled with oxidative polymerization stabilization technology, it precisely pre-seales the ineffective pore spaces inside the activated carbon support, allowing the subsequently loaded active metal to reside within the effective catalytic pore spaces of the support. This improves the utilization rate of precious metal components and significantly enhances the stability and selectivity of the catalyst.

[0006] First, the present invention provides a ketamine reduction alkylation catalyst prepared according to the above preparation method. The catalyst includes an activated carbon support and an active metal supported on the activated carbon support. Before the catalyst is applied to the catalytic reaction to generate p-phenylenediamine products, the micropores inside the activated carbon support are filled with a polyaromatic amine confining agent formed by the polymerization of Schiff base, and the Schiff base is an intermediate generated in the catalytic reaction.

[0007] Secondly, the present invention also provides a method for preparing a ketone-amine reduction alkylation catalyst, which includes the following steps:

[0008] (1) The raw material ketone and aromatic amine are mixed and dissolved with the co-catalyst in a molar ratio of 5:1-10:1, and condensed at 60℃-100℃ to form a condensation solution containing Schiff base, wherein the Schiff base in step (1) is an intermediate of the reaction product of p-phenylenediamine catalyzed by the catalyst.

[0009] (2) Impregnate the activated carbon carrier in the ketone-amine condensation solution and stir for 0.5h-50h under a nitrogen atmosphere at 20℃-50℃;

[0010] (3) Take the activated carbon carrier out of the condensation solution of the ketone amine and place it in the ammonium persulfate stabilizing solution again, and stabilize it at 30℃-80℃ for 0.1h-10h. Then wash and dry the activated carbon carrier after treatment.

[0011] (4) The activated carbon carrier is further impregnated in an impregnation solution containing an active metal precursor and stirred at 20℃-50℃ for 0.2h-20h.

[0012] (5) For the steps The impregnated catalyst is then subjected to reduction treatment to obtain a ketamine reduction alkylation catalyst.

[0013] Preferably, in step (1), the p-phenylenediamine reaction product is one of N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-(1,4-dimethylpentyl)-N'-phenyl-p-phenylenediamine, N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine, N,N'-disec-butyl-p-phenylenediamine, and N,N'-biscyclohexyl-p-phenylenediamine; and / or, the aromatic amine is one of p-aminodiphenylamine and p-phenylenediamine; and / or, the ketone is one of acetone, methyl isobutyl ketone, methyl isopentyl ketone, butanone, and cyclohexanone.

[0014] Preferably, in step (1), the co-catalyst is p-toluenesulfonic acid; and / or, the mass ratio of the aromatic amine to the co-catalyst is 50:1-100:1.

[0015] Preferably, in step (2), the activated carbon carrier used is one type of bio-based activated carbon; more preferably, the bio-based activated carbon is wood-based activated carbon, coal-based activated carbon, coconut shell activated carbon, fruit shell activated carbon, or resin-based activated carbon; and / or, the activated carbon carrier is in the form of powder, spheres, flakes, columnar particles, or irregular particles; and / or, the specific surface area of ​​the activated carbon carrier is 500 m². 2 / g-3000m 2 / g, the total pore volume of the carbon support is 0.5cm³. 3 / g-4cm 3 / g; and / or, the mass ratio of the activated carbon carrier to the condensation solution is 1:5-1:50.

[0016] Preferably, in step (3), the mass ratio of ammonium persulfate to activated carbon carrier is 1:100-1:1000; and / or, the mass ratio of activated carbon carrier to stabilizing liquid is 1:5-1:50; and / or, in the water washing process, the mass ratio of deionized water to activated carbon carrier is 1:5-1:50, and the water washing time is 0.5h-10h; and / or, the drying temperature is 120℃-150℃, and the drying time is 2h-24h.

[0017] Preferably, in step (4), the active metal precursor is di(acetylacetone)platinum, and the mass ratio of di(acetylacetone)platinum to the activated carbon carrier is 1:1000-1:20 based on platinum metal; and / or, the solvent used in the impregnation solution is a ketone; and / or, the mass ratio of the impregnation solution to the activated carbon carrier is 5:1-50:1.

[0018] Preferably, in step (5), the reducing gas used in the reduction treatment is hydrogen; and / or, the temperature of the reduction treatment is 120℃-180℃, and the reduction time is 1h-20h.

[0019] Finally, the ketamine reduction alkylation catalyst provided by this invention is applied in the ketamine reduction alkylation reaction to synthesize p-phenylenediamine antioxidants.

[0020] Preferably, the ketamine reductive alkylation reaction is one of the following: reductive alkylation reaction of p-aminodiphenylamine with acetone, reductive alkylation reaction of p-aminodiphenylamine with methyl isobutyl ketone, reductive alkylation reaction of p-aminodiphenylamine with methyl isopentyl ketone, reductive alkylation reaction of p-phenylenediamine with methyl isopentyl ketone, reductive alkylation reaction of p-phenylenediamine with butanone, and reductive alkylation reaction of p-phenylenediamine with cyclohexanone; and / or, the reactor for the reaction is a batch reactor or a fixed-bed continuous reactor.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] First, this invention uses Schiff base, an intermediate in the catalytic reaction that produces p-phenylenediamine-like products, as a confinement agent precursor. Coupled with oxidative polymerization stabilization technology, it precisely pre-seales the ineffective pore space inside the activated carbon support, allowing the subsequently loaded active metal to be located in the effective catalytic pore space within the support. This improves the utilization rate of the precious metal component, significantly enhances the stability and selectivity of the catalyst while ensuring its activity, and reduces the consumption cost of the precious metal catalyst.

[0023] Secondly, the oxidation stabilization process used in this invention can simultaneously establish acidic oxygen-containing functional group sites on the carbon support surface, matching the weak acid catalytic condensation reaction of ketone-amine reduction alkylation reaction, catalyzing the generation of Schiff base intermediate, and improving the overall activity of the catalyst.

[0024] Finally, the present invention unexpectedly and surprisingly discovered that the drying process using ammonium persulfate within a specific temperature range during the oxidative polymerization stabilization process can improve the selectivity of the catalyst without sacrificing or even enhancing its activity, and can effectively suppress the formation of high-boiling-point byproducts and ketone hydrogenation side reactions. Attached Figure Description

[0025] Figure 1 This is a TEM image of fresh CAT1 in Example 1;

[0026] Figure 2 TEM image of fresh CAT2 in Example 2;

[0027] Figure 3 This is a TEM image of fresh CAT3 in Example 3. Detailed Implementation

[0028] The following embodiments further illustrate the content of the present invention, but should not be construed as limiting the present invention. Any modifications and substitutions made to the methods, steps, or conditions of the present invention without departing from the essence of the invention are within the scope of the present invention.

[0029] A method for preparing a ketone-amine reduction alkylation catalyst, comprising the following steps:

[0030] (1) The dehydration condensation products of the raw aromatic amine and ketone corresponding to the p-phenylenediamine reaction products matched with the applied catalytic reaction are used as the confinement agent precursors. Specifically, the raw aromatic amine, raw ketone and co-catalyst are first mixed and dissolved and then added to a condensation vessel equipped with a vacuum dehydration device. After nitrogen purging, stirring is started and the temperature is raised to 60℃-100℃ under vacuum conditions for reaction. During the reaction, the liquid distilled under vacuum is condensed and separated into layers. The upper raw ketone is continuously returned to the condensation vessel. After a certain reaction time, a sample is taken for analysis. When the remaining amount of raw aromatic amine in the liquid is less than 10%, the ketone-amine condensation liquid is transferred to a rotary impregnation tank.

[0031] (2) Activated carbon is used as a carbon carrier. The carbon carrier is added to the ketamine condensation solution in the impregnation tank. The tank is first replaced with nitrogen. The material is stirred by slowly rotating the impregnation tank. After treatment at 20℃-50℃ for 0.5h-50h, the solution is completely drained from the drain port with a filter device at the bottom of the tank. The drained ketamine condensation solution is transferred to the storage tank for later use, and the activated carbon is left in the impregnation tank.

[0032] (3) Add a certain amount of ammonium persulfate stabilizing solution to the impregnation tank, slowly rotate the impregnation tank to stir the material, stabilize at 30℃-80℃ for 0.1h-10h, drain the liquid completely from the filter outlet at the bottom of the tank, leaving the activated carbon in the impregnation tank, add a certain amount of deionized water to the tank, rotate the impregnation tank to stir and wash the material, drain the liquid completely from the filter outlet at the bottom of the tank, and unload the activated carbon for drying.

[0033] (4) The activated carbon carrier obtained by drying in step (3) is transferred back into the impregnation tank. The tank is first replaced with nitrogen, and then a certain amount of impregnation liquid containing active metal precursor is added to the tank. The impregnation tank is rotated at 20℃-50℃ to stir the material for 0.2h-20h. The liquid is then completely drained from the filter outlet at the bottom of the tank. The drained liquid is recycled and transferred to the storage tank for later use.

[0034] (5) The catalyst obtained by impregnation in step (4) is subjected to reduction treatment using hydrogen reduction. The finished catalyst obtained after reduction is then vacuum-sealed and stored.

[0035] Example 1

[0036] A 5000mL glass-jacketed reactor equipped with a vacuum dehydration device was used as the condensation vessel. 737g of p-aminodiphenylamine, 2003g of methyl isobutyl ketone, and 7.37g of p-toluenesulfonic acid were added to the condensation vessel. After nitrogen purging, stirring was started, and the temperature was raised to 80℃ under reduced pressure to begin the reaction. During the reaction, the liquid distilled under reduced pressure was condensed and separated into layers. The upper layer of methyl isobutyl ketone was continuously returned to the condensation vessel. After 4 hours of reaction, a sample was taken, and gas chromatography analysis showed that the residual p-aminodiphenylamine in the solution was 4.5%. More than 1000g of the condensate was transferred to a rotary impregnation tank. 100g of 2mm columnar activated carbon MZ-1 was added to the ketone-amine condensate in the impregnation tank. The impregnation tank was first purged with nitrogen. The material was stirred by slowly rotating the tank and treated at 30°C for 2 hours. The liquid was then completely drained through the drain port with a filter at the bottom of the tank under normal pressure, leaving the columnar activated carbon MZ-1 inside. Next, 1000g of a stabilizing solution containing 1g of ammonium persulfate was added to the impregnation tank. The material was stirred by slowly rotating the tank and stabilized at 70°C for 4 hours. The liquid was then completely drained through the drain port at the bottom of the tank under normal pressure, leaving the activated carbon inside. Then, 1000g of deionized water was added to the tank, and the material was stirred and washed by rotating the tank for 1 hour. The liquid was then completely drained through the drain port at the bottom of the tank under normal pressure, and the activated carbon was discharged and transferred to a forced-air drying oven for drying at 140°C for 5 hours. The dried MZ-1 was then transferred back to the impregnation tank and purged with nitrogen. 0.4 g of bis(acetylacetone)platinum was dissolved and mixed thoroughly with 1000 g of methyl isobutyl ketone, and then the mixture was added to an impregnation tank. The tank was rotated and stirred for 4 hours at 30°C. The liquid was then drained completely through the filter outlet at the bottom of the tank under normal pressure. The drained liquid was collected and transferred to a storage tank for later use. After impregnation, the catalyst was unloaded and transferred to a tube furnace for reduction at 160°C under a hydrogen atmosphere for 5 hours. After cooling, the catalyst was unloaded and quickly vacuum-sealed to obtain the finished catalyst Pt@MZ-1. This catalyst is designated CAT1.

[0037] Reaction Evaluation: CAT1 was applied to the continuous preparation of the antioxidant N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (hereinafter referred to as 6PPD) from p-aminodiphenylamine (hereinafter referred to as RT) and methyl isobutyl ketone (hereinafter referred to as RT). 50 g of CAT1 was packed into a fixed-bed reactor. After multiple purgings with nitrogen and hydrogen, the hydrogen pressure was controlled at 1 MPa, the reaction temperature at 80 °C, and the molar ratio of methyl isobutyl ketone to p-aminodiphenylamine in the feed solution was 4:1. The feed solution was continuously pumped into the reactor using a high-pressure feed pump at a flow rate of 1 mL / min, with a hydrogen flow rate of 2000 mL / min. Catalyst stability was evaluated by sampling every 8 hours and analyzing the samples using gas chromatography. The analytical results are shown in Table 1.

[0038] Table 1. Test results of the CAT1 catalyst prepared in Example 1

[0039] time RT margin Schiff base balance Keto-alcohol ratio 6PPD purity Impurity peaks 8h 0.15% 0.12% 96:4 99.03% 0.70% 16h 0.11% 0.07% 98:2 99.15% 0.67% 24h 0.12% 0.15% 98:2 99.21% 0.52% 32h 0.12% 0.14% 99:1 99.20% 0.54% 40h 0.10% 0.10% 99:1 99.32% 0.48% 48h 0.08% 0.11% 99:1 99.36% 0.45% 56h 0.09% 0.13% 99:1 99.35% 0.43% 64h 0.09% 0.11% 99:1 99.39% 0.41% 72h 0.09% 0.14% 99:1 99.38% 0.39% 80h 0.11% 0.12% 99:1 99.39% 0.38% 88h 0.10% 0.17% 99:1 99.37% 0.36% 96h 0.11% 0.12% 99:1 99.41% 0.36% 104h 0.09% 0.11% 99.2:0.8 99.46% 0.34% 112h 0.08% 0.13% 99.2:0.8 99.44% 0.35% 120h 0.09% 0.12% 99.4:0.6 99.43% 0.36% 128h 0.10% 0.09% 99.4:0.6 99.48% 0.33% 136h 0.08% 0.09% 99.2:0.8 99.48% 0.35% 144h 0.08% 0.11% 99.2:0.8 99.49% 0.32% 152h 0.09% 0.08% 99.2:0.8 99.48% 0.35% 160h 0.12% 0.08% 99.2:0.8 99.49% 0.31% 168h 0.08% 0.07% 99.2:0.8 99.46% 0.39% 176h 0.08% 0.10% 99.2:0.8 99.45% 0.37% 184h 0.07% 0.12% 99.3:0.7 99.50% 0.31% 192h 0.08% 0.09% 99.3:0.7 99.49% 0.34% 200h 0.10% 0.06% 99.3:0.7 99.45% 0.39% 208h 0.08% 0.06% 99.3:0.7 99.47% 0.39% 216h 0.09% 0.07% 99.2:0.8 99.52% 0.32% 224h 0.08% 0.10% 99.2:0.8 99.49% 0.33% 232h 0.09% 0.07% 99.3:0.7 99.46% 0.38% 240h 0.08% 0.10% 99.3:0.7 99.47% 0.35%

[0040] Analysis and characterization of carbon support and catalyst:

[0041] The specific surface area and pore structure of the original carbon support MZ-1, fresh CAT1, and CAT1 discharged after a 240-hour stability evaluation were analyzed using N2 low-temperature physical adsorption-desorption technology. The specific surface areas of the original carbon support MZ-1, fresh CAT1, and CAT1 discharged after a 240-hour stability evaluation were 1344 m² / s. 2 / g、895m 2 / g、872m 2 / g; the total pore volume of the three is 0.87cm³. 3 / g, 0.66cm 3 / g, 0.64cm 3 / g; the mesoporous-microporous pore volume ratios of the three are 45:55, 78:22, and 80:20, respectively.

[0042] The oxygen, nitrogen, and sulfur contents in the original MZ-1 and the MZ-1 that underwent only confinement filling, stabilization, and drying treatments were analyzed using an organic elemental analyzer and a sulfur and carbon analyzer, respectively. The results showed that the oxygen, nitrogen, and sulfur contents in the original MZ-1 were 6.4%, 0.06%, and 0.02%, respectively, while the oxygen, nitrogen, and sulfur contents in the MZ-1 that underwent only confinement filling, stabilization, and drying treatments were 8.2%, 0.55%, and 0.09%, respectively.

[0043] The Pt content in fresh CAT1 and CAT1 discharged after a 240-hour stability evaluation was analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). The catalyst underwent pretreatment including drying, weighing, high-temperature calcination to remove the carbon support, aqua regia nitration, and dilution to a final volume. ICP-OES analysis showed that the Pt content in fresh CAT1 and CAT1 discharged after the 240-hour stability evaluation was 0.195% and 0.191%, respectively. Considering that the catalyst will adsorb a small amount of organic matter after use, causing a slight increase in weight, the small difference in Pt content before and after use indicates that the Pt loading on the catalyst is good, and no significant loss was observed after 240 hours of continuous use.

[0044] The loading and dispersion of Pt nanoparticles on fresh CAT1 were analyzed using TEM, based on TEM images of the catalyst ( Figure 1 As can be seen, the Pt nanoparticles exhibit a highly dispersed and well-loaded state on the catalyst support, with a nanoparticle size of about 1-2 nm and no agglomeration.

[0045] Example 2

[0046] Catalyst preparation: 1000g of the condensation solution identical to that in Example 1 was transferred into a rotary impregnation tank. 100g of GF-1 powdered coconut shell activated carbon was added to the impregnation tank. The impregnation tank was first purged with nitrogen. The material was stirred by slowly rotating the impregnation tank. After treatment at 30°C for 2 hours, the liquid was completely drained from the drain port with a filter at the bottom of the tank under nitrogen pressure, leaving the GF-1 powdered carbon in the impregnation tank. Add 1000g of a stabilizing solution containing 5g of ammonium persulfate to the impregnation tank. Slowly rotate the impregnation tank to stir the material. After stabilization treatment at 70℃ for 4 hours, drain the entire solution through the filter outlet at the bottom of the tank under nitrogen pressure, leaving the activated carbon in the impregnation tank. Add 1000g of deionized water to the tank, rotate the impregnation tank to stir and wash the material for 1 hour. Drain the entire solution through the filter outlet at the bottom of the tank under nitrogen pressure, removing the activated carbon and transferring it to a forced-air drying oven to dry at 140℃ for 5 hours. Transfer the dried GF-1 back to the impregnation tank and replace it with nitrogen. Dissolve 3g of bis(acetylacetone)platinum in 1000g of methyl isobutyl ketone, mix thoroughly, and add all of the solution to the impregnation tank. Stir the material by rotating the impregnation tank at 30℃ for 4 hours. Drain the entire solution through the filter outlet at the bottom of the tank under nitrogen pressure, recovering the drained solution and transferring it to a storage tank for later use. After impregnation, the catalyst was unloaded and transferred to a tube furnace, where it was reduced for 5 hours in a hydrogen atmosphere at 160°C. After cooling, it was unloaded and quickly vacuum-sealed to obtain the finished catalyst Pt@GF-1. This catalyst is labeled CAT2.

[0047] Reaction Evaluation: CAT2 was applied to the preparation of the antioxidant N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) using p-aminodiphenylamine (RT) and methyl isobutyl ketone as raw materials. A semi-continuous batch reactor was used for reaction evaluation. Specifically, 184g of p-aminodiphenylamine, 400.6g of methyl isobutyl ketone, and 1.84g of CAT2 were weighed and added to a 316 stainless steel high-pressure reactor. After multiple purgings with nitrogen and hydrogen, the hydrogen pressure was controlled at 1MPa, and the reaction temperature was 100℃. Mechanical stirring was started to carry out the reaction until the system no longer absorbed hydrogen, at which point the reaction was considered complete, and the reaction time was recorded. The reaction solution was filtered out through a built-in filter under the pressure of the reactor and analyzed by gas chromatography. The catalyst remained in the reactor for reuse. Based on the mass of the filtered reaction solution, the same mass of raw material solution was added using a high-pressure feed pump, maintaining the ketone-amine molar ratio, and the reaction was restarted with increased temperature and pressure. Without adding fresh catalyst, the catalyst was used continuously for 20 batches. The analysis results of the reaction solution are shown in the table below:

[0048] Table 2. Test results of the CAT2 catalyst prepared in Example 2

[0049] batch reaction time RT margin Schiff base balance Keto-alcohol ratio 6PPD purity Impurity peaks 1 3.0h 0.12% 0.08% 96:4 99.03% 0.77% 2 3.0h 0.11% 0.10% 98.5:1.5 99.21% 0.58% 3 3.2h 0.08% 0.07% 99:1 99.41% 0.44% 4 3.2h 0.08% 0.11% 99:1 99.36% 0.45% 5 3.2h 0.09% 0.08% 99:1 99.40% 0.43% 6 3.2h 0.08% 0.10% 99:1 99.36% 0.46% 7 3.2h 0.12% 0.07% 99:1 99.33% 0.48% 8 3.3h 0.10% 0.07% 99:1 99.38% 0.45% 9 3.4h 0.07% 0.10% 99.2:0.8 99.44% 0.39% 10 3.2h 0.11% 0.09% 99.2:0.8 99.36% 0.44% 11 3.2h 0.12% 0.11% 99.2:0.8 99.43% 0.34% 12 3.5h 0.09% 0.08% 99.2:0.8 99.41% 0.42% 13 3.5h 0.12% 0.13% 99.3:0.7 99.40% 0.35% 14 3.6h 0.11% 0.09% 99.2:0.8 99.42% 0.38% 15 3.6h 0.10% 0.11% 99.2:0.8 99.46% 0.33% 16 3.6h 0.13% 0.09% 99.2:0.8 99.34% 0.44% 17 3.5h 0.12% 0.12% 99.2:0.8 99.40% 0.36% 18 3.6h 0.11% 0.10% 99:1 99.40% 0.39% 19 3.8h 0.08% 0.07% 99.3:0.7 99.42% 0.43% 20 3.6h 0.09% 0.12% 99.2:0.8 99.42% 0.37%

[0050] Analysis and characterization of carbon support and catalyst:

[0051] The specific surface area and pore structure of the original powdered carbon support GF-1, fresh CAT2, and CAT2 removed after 20 batches of use were analyzed using N2 low-temperature physical adsorption-desorption technology. The specific surface areas of the original carbon support GF-1, fresh CAT2, and CAT2 removed after 20 batches of use were 918 m² / s. 2 / g、684m 2 / g、655 m 2 / g; the total pore volume of the three is 0.84 cm³. 3 / g, 0.64 cm 3 / g, 0.61 cm 3 / g; the mesoporous-microporous pore volume ratios of the three are 55:45, 82:18, and 85:15, respectively.

[0052] The Pt content in fresh CAT2 and CAT2 discharged after 20 batches of use was analyzed by ICP-OES. The ICP-OES analysis results showed that the Pt content in fresh CAT2 and CAT2 discharged after 20 batches of use was 1.47% and 1.45%, respectively. This indicates that the Pt loading strength on the catalyst was good, and no significant loss was observed after 20 consecutive batches of use.

[0053] The loading and dispersion of Pt nanoparticles on fresh CAT2 were analyzed using TEM. This analysis was based on TEM images of the catalyst. Figure 2 As can be seen, the Pt nanoparticles are well dispersed, with a nanoparticle size of about 2 nm and no aggregation.

[0054] Example 3

[0055] Catalyst preparation: A 5000mL glass-jacketed reactor equipped with a vacuum dehydration device was used as the condensation vessel. 216.3g of p-phenylenediamine (PPD), 2283.6g of methyl isopentyl ketone (MIAK), and 2.16g of p-toluenesulfonic acid were added to the condensation vessel. After nitrogen purging, stirring was started, and the temperature was raised to 80℃ under reduced pressure to begin the reaction. During the reaction, the liquid distilled under reduced pressure was condensed and separated into layers. The upper layer of MIAK was continuously returned to the condensation vessel. After 4 hours of reaction, a sample was taken, and gas chromatography analysis showed that the residual p-phenylenediamine in the solution was 3.0%. More than 1000g of the condensation solution was transferred to a rotary impregnation tank. 50g of wood-based powdered activated carbon MF-1 was added to the ketone-amine condensation solution in the impregnation tank. The impregnation tank was first purged with nitrogen. The material was stirred by slowly rotating the tank and treated at 25°C for 2 hours. The liquid was then completely drained through the drain port with a filter at the bottom of the tank under nitrogen pressure, leaving the columnar activated carbon MF-1 inside. Next, 1000g of a stabilizing solution containing 1g of dissolved ammonium persulfate was added to the impregnation tank. The material was stirred by slowly rotating the tank and stabilized at 75°C for 5 hours. The liquid was then completely drained through the drain port at the bottom of the tank under nitrogen pressure, leaving the activated carbon inside. Then, 1000g of deionized water was added to the tank, and the material was stirred and washed by rotating the tank for 2 hours. The liquid was then completely drained through the drain port at the bottom of the tank under nitrogen pressure, and the activated carbon was discharged and transferred to a forced-air drying oven for drying at 130°C for 4 hours. The dried MF-1 was then transferred back to the impregnation tank and purged with nitrogen. 2g of bis(acetylacetone)platinum was dissolved and mixed thoroughly in 750g of MIAK, and then the entire mixture was added to an impregnation tank. The tank was rotated and stirred for 4 hours at 25°C. The liquid was then completely drained through the filter outlet at the bottom of the tank under nitrogen pressure. The drained liquid was collected and transferred to a storage tank for later use. After impregnation, the catalyst was unloaded and transferred to a tube furnace for reduction at 170°C under a hydrogen atmosphere for 5 hours. After cooling, the catalyst was unloaded and quickly vacuum-sealed to obtain the finished catalyst Pt@MF-1. This catalyst is designated CAT3.

[0056] Reaction Evaluation: CAT3 was applied to the preparation of the antioxidant N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (hereinafter referred to as 77PD) using PPD and MIAK as raw materials. The reaction evaluation employed a semi-continuous batch reactor. Specifically, 108.14 g of PPD, 685 g of MIAK, and 1.08 g of CAT3 were weighed and added to a high-pressure reactor made of 316 stainless steel. After multiple purgings with nitrogen and hydrogen, the hydrogen pressure was controlled at 1.5 MPa, and the reaction temperature was 110℃. Mechanical stirring was initiated until the reaction system no longer absorbed hydrogen, at which point the reaction was considered complete, and the reaction time was recorded. The reaction solution was filtered through a built-in filter under the pressure of the reactor and analyzed by gas chromatography. The catalyst remained in the reactor for reuse. Based on the mass of the filtered reaction solution, the same mass of raw material solution was added using a high-pressure feed pump, maintaining the ketone-amine molar ratio, and the reaction was restarted at higher temperatures and pressures. Without adding fresh catalyst, the catalyst was used continuously for 12 batches. The analysis results of the reaction solution are shown in the table below.

[0057] Table 3. Test results of the CAT3 catalyst prepared in Example 3

[0058] batch reaction time PPD margin Schiff base balance Keto-alcohol ratio 77PD purity Impurity peaks 1 2.5h 0.14% 0.10% 96:4 99.06% 0.64% 2 2.5h 0.16% 0.12% 97:3 99.21% 0.51% 3 2.5h 0.15% 0.13% 98:2 99.24% 0.48% 4 2.8h 0.11% 0.10% 98:2 99.36% 0.43% 5 2.6h 0.14% 0.12% 98:2 99.25% 0.49% 6 2.6h 0.13% 0.10% 98:2 99.36% 0.41% 7 2.8h 0.10% 0.09% 95.5:1.5 99.41% 0.40% 8 2.8h 0.12% 0.12% 95.5:1.5 99.38% 0.38% 9 3.0h 0.10% 0.08% 95.5:1.5 99.46% 0.36% 10 3.0h 0.12% 0.11% 99:1 99.38% 0.39% 11 3.0h 0.12% 0.10% 99:1 99.43% 0.35% 12 3.0h 0.12% 0.12% 99:1 99.40% 0.36%

[0059] Analysis and characterization of carbon support and catalyst:

[0060] The specific surface area and pore structure of the original powdered carbon support MF-1, fresh CAT3, and CAT3 after 12 batches of application were analyzed using N2 low-temperature physical adsorption-desorption technology. The specific surface areas of the original carbon support MF-1, fresh CAT3, and CAT3 after 12 batches of application were 1528 m² / s. 2 / g、1146m 2 / g、1079m 2 / g; the total pore volume of the three is 1.46 cm³. 3 / g, 1.12 cm 3 / g, 1.08cm 3 / g; the mesopore volume ratios of the three are 68:32, 84:16, and 87:13, respectively.

[0061] The Pt content in fresh CAT3 and CAT3 discharged after 12 batches of reuse was analyzed by ICP-OES. The ICP-OES analysis results showed that the Pt content in fresh CAT3 and CAT3 discharged after 12 batches of reuse was 1.94% and 1.92%, respectively. This indicates that Pt is firmly loaded on the catalyst and no significant loss was observed after 12 consecutive batches of reuse.

[0062] The loading and dispersion of Pt nanoparticles on fresh CAT3 were analyzed by TEM. The TEM images showed that the Pt nanoparticles were well dispersed, with a size of about 2 nm and no agglomeration.

[0063] Comparative Example 1

[0064] Catalyst preparation: 2mm wood-based columnar activated carbon MZ-1, the same as in Example 1, was used as the catalyst support. 100g of raw MZ-1 was directly added to the impregnation tank, which was then purged with nitrogen. 0.4g of bis(acetylacetone)platinum was dissolved in 1000g of methyl isobutyl ketone and mixed thoroughly before being added to the impregnation tank. The tank was rotated and stirred for 4 hours at 30°C. The liquid was then completely drained through the filter outlet at the bottom of the tank under normal pressure. The drained liquid was collected and transferred to a storage tank for later use. After impregnation, the catalyst was unloaded and transferred to a tube furnace for reduction at 160°C under a hydrogen atmosphere for 5 hours. After cooling, the catalyst was unloaded and quickly vacuum-sealed to obtain the finished catalyst, labeled CAT4.

[0065] Reaction Evaluation: Similar to Example 1, CAT4 was applied to the continuous preparation of antioxidant 6PPD using RT and methyl isobutyl ketone (MIBK) as raw materials. 50g of CAT4 was packed into a fixed-bed reactor, and the operating and reaction conditions were kept consistent with those in Example 1. Catalyst stability was evaluated, with samples taken every 8 hours and analyzed by gas chromatography. The analytical results are shown in Table 4 below:

[0066] Table 4. Test results of the CAT4 catalyst prepared in Comparative Example 1

[0067] time RT margin Schiff base balance Keto-alcohol ratio 6PPD purity Impurity peaks 8h 0.75% 0.95% 93:7 96.06% 2.24% 16h 1.77% 1.35% 94:6 95.02% 1.86% 24h 2.96% 2.04% 94:6 93.37% 1.63% 32h 3.52% 2.31% 95:5 92.63% 1.54% 40h 4.38% 2.63% 95:5 91.47% 1.52% 48h 5.08% 2.88% 95:5 90.56% 1.48%

[0068] Catalyst analysis and characterization:

[0069] The specific surface area and pore structure of fresh CAT4 and CAT4 discharged after stability evaluation experiments were analyzed using N2 low-temperature physical adsorption-desorption technology. The specific surface areas of fresh CAT4 and CAT4 discharged after stability evaluation experiments were 1302 m² / s. 2 / g、854m 2 / g; the total pore volume of both is 0.84cm³. 3 / g, 0.62cm 3 / g; the mesoporous-microporous pore volume ratios of the two are 48:52 and 82:18, respectively.

[0070] The Pt content in fresh CAT4 and CAT4 discharged after use was analyzed by ICP-OES. The ICP-OES analysis results showed that the Pt content in fresh CAT4 and CAT4 discharged after use was 0.194% and 0.181%, respectively. This indicates that a slight loss of Pt occurred after the catalyst was used.

[0071] Comparative Example 2

[0072] Catalyst preparation: The same GF-1 activated carbon powder from fruit shells as in Example 2 was used as the catalyst support. 50g of raw GF-1 was directly added to the impregnation tank, which was then purged with nitrogen. 2g of bis(acetylacetone)platinum was dissolved in 500g of MIBK and mixed thoroughly before being added to the impregnation tank. The tank was rotated and stirred for 4 hours at 30°C. The liquid was then completely drained through the filter outlet at the bottom of the tank under nitrogen pressure. The drained liquid was collected and transferred to a storage tank for later use. After impregnation, the catalyst was unloaded and transferred to a tubular furnace for reduction at 160°C under a hydrogen atmosphere for 5 hours. After cooling, the catalyst was unloaded and quickly vacuum-sealed to obtain the finished catalyst, labeled CAT5.

[0073] Reaction Evaluation: Similar to Example 2, a semi-continuous batch reactor was used to apply CAT5 to the reaction of preparing antioxidant 6PPD using RT and MIBK as raw materials. The feedstock and catalyst dosages, operating conditions, and reaction conditions remained consistent with Example 2, and continuous catalyst application evaluation tests were conducted. The analysis results of each batch of reaction solution are shown in Table 5 below:

[0074] Table 5. Test results of the CAT5 catalyst prepared in Comparative Example 2

[0075] batch reaction time RT margin Schiff base balance Keto-alcohol ratio 6PPD purity Impurity peaks 1 4.5h 0.88% 0.84% 93:7 95.59% 2.69% 2 5.2h 1.43% 1.25% 93:7 94.98% 2.34% 3 6.5h 2.76% 1.78% 94:6 93.59% 1.87% 4 7.6h 4.78% 2.52% 94:6 90.72% 1.98% 5 9.5h 7.80% 2.84% 95:5 87.15% 2.21%

[0076] Catalyst analysis and characterization:

[0077] The specific surface area and pore structure of fresh CAT5 and CAT5 discharged after application evaluation experiments were analyzed using N2 low-temperature physical adsorption-desorption technology. The specific surface areas of fresh CAT5 and CAT5 discharged after application evaluation experiments were 895 m² / s. 2 / g、527m 2 / g; the total pore volume of both is 0.82 cm³. 3 / g, 0.44 cm 3 / g; the mesoporous-microporous pore volume ratios of the two are 61:39 and 88:12, respectively.

[0078] The Pt content in fresh CAT5 and CAT5 after recycling was analyzed by ICP-OES. The ICP-OES results showed that the Pt content in fresh CAT5 and CAT5 after recycling was 1.95% and 1.82%, respectively. This indicates a slight loss of Pt after catalyst use.

[0079] Comparative Example 3

[0080] Catalyst preparation: The same granulated activated carbon GF-1 from fruit shells as in Example 2 was used as the catalyst support. The preparation method was consistent with Example 2, the only difference being that the activated carbon GF-1, after impregnation with the condensation solution, was not subjected to stabilization treatment with ammonium sulfate solution, but directly underwent subsequent washing, drying, impregnation-loading, and reduction steps. The resulting finished catalyst was labeled CAT6.

[0081] Reaction Evaluation: Similar to Example 2, a semi-continuous batch reactor was used to apply CAT6 to the reaction of preparing antioxidant 6PPD using RT and MIBK as raw materials. The feedstock and catalyst dosages, operating conditions, and reaction conditions remained consistent with Example 2, and continuous catalyst application evaluation tests were conducted. The analysis results of each batch of reaction solution are shown in the table below:

[0082] Table 6. Test results of the CAT6 catalyst prepared in Comparative Example 3

[0083] batch reaction time RT margin Schiff base balance Keto-alcohol ratio 6PPD purity Impurity peaks 1 4.2h 0.54% 0.38% 94:6 97.40% 1.68% 2 4.5h 0.88% 0.76% 95:5 96.54% 1.82% 3 4.8h 1.12% 0.86% 95:5 96.45% 1.57% 4 5.2h 1.59% 1.04% 95:5 95.85% 1.52% 5 5.6h 1.75% 1.21% 96:4 95.56% 1.48%

[0084] Catalyst analysis and characterization:

[0085] The specific surface area and pore structure of fresh CAT6 and CAT6 unloaded after application evaluation experiments were analyzed using N2 low-temperature physical adsorption-desorption technology. The specific surface areas of fresh CAT6 and CAT6 unloaded after application evaluation were 721 m² / s. 2 / g、635m 2 / g; the total pore volume of both is 0.67 cm³. 3 / g, 0.60 cm 3 / g; the mesoporous-microporous pore volume ratios of the two are 80:20 and 88:12, respectively.

[0086] The Pt content in fresh CAT6 and CAT6 after being unloaded using ICP-OES was analyzed. The ICP-OES analysis results showed that the Pt content in fresh CAT6 and CAT6 after being unloaded using ICP-OES was 1.41% and 1.34%, respectively.

[0087] Comparative Example 4

[0088] Catalyst preparation: GF-1 powdered activated carbon from fruit shells, the same as in Example 2, was used as the catalyst support. The preparation method was consistent with Example 2, the only difference being that potassium persulfate aqueous solution was used as the stabilizing liquid in the stabilization process. The resulting catalyst was labeled CAT7.

[0089] Reaction Evaluation: Similar to Example 2, a semi-continuous batch reactor was used to apply CAT7 to the reaction of preparing antioxidant 6PPD using RT and MIBK as raw materials. The feedstock and catalyst dosages, operating conditions, and reaction conditions remained consistent with Example 2, and continuous catalyst application evaluation tests were conducted. The analysis results of each batch of reaction solution are shown in Table 7 below:

[0090] Table 7. Test results of the CAT7 catalyst prepared in Comparative Example 4

[0091] batch reaction time RT margin Schiff base balance Keto-alcohol ratio 6PPD purity Impurity peaks 1 4.6h 0.71% 0.53% 94:6 96.51% 2.25% 2 4.8h 0.92% 0.90% 94:6 96.07% 2.11% 3 5.0h 1.32% 1.28% 94.5:5.5 95.55% 1.85% 4 5.5h 1.83% 1.37% 95:5 95.07% 1.73% 5 6.0h 2.21% 1.42% 96:4 94.65% 1.72%

[0092] Catalyst analysis and characterization:

[0093] The specific surface area and pore structure of fresh CAT6 and CAT6 unloaded after application evaluation experiments were analyzed using N2 low-temperature physical adsorption-desorption technology. The specific surface areas of fresh CAT6 and CAT6 unloaded after application evaluation were 705 m² / s. 2 / g、646m 2 / g; the total pore volume of both is 0.65 cm³. 3 / g, 0.61 cm 3 / g; the mesoporous-microporous pore volume ratios of the two are 82:18 and 87:13, respectively.

[0094] The Pt content in fresh CAT6 and CAT6 after being unloaded using ICP-OES was analyzed. The ICP-OES analysis results showed that the Pt content in fresh CAT6 and CAT6 after being unloaded using ICP-OES was 1.41% and 1.34%, respectively.

[0095] Comparative Example 5

[0096] Catalyst preparation: GF-1 powdered coconut shell activated carbon, the same as in Example 2, was used as the catalyst support. The preparation method was consistent with Example 2, the only difference being that the drying temperature of the activated carbon was adjusted to 200℃ after stabilization and washing treatments. The resulting catalyst was labeled CAT8.

[0097] Reaction Evaluation: Similar to Example 2, a semi-continuous batch reactor was used to apply CAT8 to the reaction of preparing antioxidant 6PPD using RT and MIBK as raw materials. The feedstock and catalyst dosages, operating conditions, and reaction conditions remained consistent with Example 2, and continuous catalyst application evaluation tests were conducted. The analysis results of each batch of reaction solution are shown in the table below.

[0098] Table 8. Test results of the CAT8 catalyst prepared in Comparative Example 5

[0099] batch reaction time RT margin Schiff base balance Keto-alcohol ratio 6PPD purity Impurity peaks 1 4.4h 1.21% 0.98% 96:4 96.51% 1.89% 2 5.2h 1.57% 1.18% 97:3 95.43% 1.82% 3 5.8h 1.86% 1.24% 97:3 95.01% 1.89% 4 6.5h 2.45% 1.72% 97:3 94.25% 1.58% 5 7.3h 3.23% 1.63% 97:3 93.50% 1.64%

[0100] Comparative Example 6

[0101] Catalyst preparation: GF-1 powdered activated carbon from fruit shells, the same as in Example 2, was used as the catalyst support. The preparation method was consistent with Example 2, the only difference being that the hydrogen reduction temperature of the catalyst was adjusted to 300℃. The resulting catalyst was labeled CAT9.

[0102] Reaction Evaluation: Similar to Example 2, a semi-continuous batch reactor was used to apply CAT9 to the reaction of preparing antioxidant 6PPD using RT and MIBK as raw materials. The feedstock and catalyst dosages, operating conditions, and reaction conditions remained consistent with Example 2, and continuous catalyst application evaluation tests were conducted. The analysis results of each batch of reaction solution are shown in Table 9 below:

[0103] Table 9. Test results of the CAT9 catalyst prepared in Comparative Example 6

[0104] batch reaction time RT margin Schiff base balance Keto-alcohol ratio 6PPD purity Impurity peaks 1 4.6h 1.52% 1.26% 96.5:3.5 94.77% 2.45% 2 5.4h 1.93% 1.05% 97:3 95.10% 1.92% 3 6.3h 2.63% 1.18% 97:3 94.47% 1.72% 4 7.0h 3.47% 1.28% 97:3 93.37% 1.88% 5 7.6h 4.02% 1.55% 96:4 92.62% 1.81%

[0105] Comparative Example 7:

[0106] Catalyst preparation: MF-1 powdered activated carbon from fruit shells, the same as in Example 3, was used as the catalyst support. The preparation method was consistent with Example 2, the only difference being that the loading of Pt catalyst was adjusted to 2% (i.e., the amount of bis(acetylacetone)platinum was adjusted to 4g). The resulting catalyst was labeled CAT10.

[0107] Reaction Evaluation: The prepared CAT10 was applied to the reaction of preparing antioxidant 77PD using PPD and MIAK as raw materials. The reaction evaluation was conducted using a semi-continuous batch reactor. The specific feed ratio and operating method were the same as in Example 3. The analysis results of each batch of reaction solution are shown in Table 10 below:

[0108] Table 10 Test results of the CAT10 catalyst prepared in Comparative Example 7

[0109] batch reaction time PPD margin Schiff base balance Keto-alcohol ratio 77PD purity Impurity peaks 1 2.8h 0.65% 0.49% 96:4 97.58% 1.28% 2 3.5h 1.38% 0.88% 97:3 96.26% 1.48% 3 4.2h 2.35% 1.24% 97:3 95.13% 1.28% 4 5.0h 3.18% 1.44% 97:3 94.08% 1.30% 5 6.2h 3.89% 1.73% 97:3 93.02% 1.36%

[0110] The following embodiments further illustrate the content of the present invention, but should not be construed as limiting the present invention. Any modifications and substitutions made to the methods, steps, or conditions of the present invention without departing from the essence of the invention are within the scope of the present invention.

Claims

1. A ketone-amine reductive alkylation catalyst, characterized in that, The catalyst comprises an activated carbon support and an active metal supported on the activated carbon support. Before the catalyst is applied to the catalytic reaction that generates p-phenylenediamine-like reaction products, the micropores inside the activated carbon support are filled with a polyaromatic amine confinement agent formed by the polymerization of Schiff base, and the Schiff base is an intermediate generated in the catalytic reaction.

2. A method for preparing a ketone-amine reduction alkylation catalyst, characterized in that, Includes the following steps: (1) The raw material ketone and aromatic amine are mixed and dissolved with the co-catalyst in a molar ratio of 5:1-10:1, and condensed at 60℃-100℃ to form a condensation solution containing Schiff base, wherein the Schiff base in step (1) is an intermediate of the reaction product of p-phenylenediamine catalyzed by the catalyst. (2) Impregnate the activated carbon carrier in the ketone-amine condensation solution and stir for 0.5h-50h under a nitrogen atmosphere at 20℃-50℃; (3) Take the activated carbon carrier out of the condensation solution containing Schiff base and place it in ammonium persulfate stabilizing solution again, and stabilize it at 30℃-80℃ for 0.1h-10h. Then wash and dry the treated activated carbon carrier. (4) The activated carbon carrier is further impregnated in an impregnation solution containing an active metal precursor and stirred at 20℃-50℃ for 0.2h-20h. (5) The catalyst obtained by impregnation in step (4) is subjected to reduction treatment to obtain the ketone amine reduction alkylation catalyst.

3. The preparation method according to claim 1, characterized in that, In step (1), the p-phenylenediamine reaction product is one of N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-(1,4-dimethylpentyl)-N'-phenyl-p-phenylenediamine, N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine, N,N'-disec-butyl-p-phenylenediamine, and N,N'-biscyclohexyl-p-phenylenediamine; and / or, the aromatic amine is one of p-aminodiphenylamine and p-phenylenediamine; and / or, the raw material ketone is one of acetone, methyl isobutyl ketone, methyl isopentyl ketone, butanone, and cyclohexanone.

4. The preparation method according to claim 1, characterized in that, In step (1), the co-catalyst is p-toluenesulfonic acid; and / or, the mass ratio of the aromatic amine to the co-catalyst is 50:1-100:

1.

5. The preparation method according to claim 1, characterized in that, In step (2), the activated carbon carrier used is one type of bio-based activated carbon; and / or, the activated carbon carrier is in the form of powder, spheres, flakes, columnar particles, or irregular particles; and / or, the specific surface area of ​​the activated carbon carrier is 500 m². 2 / g-3000m 2 / g, the total pore volume of the carbon support is 0.5cm³. 3 / g-4cm 3 / g; and / or, the mass ratio of the activated carbon carrier to the condensation solution is 1:5-1:

50.

6. The preparation method according to claim 1, characterized in that, In step (3), the mass ratio of ammonium persulfate to activated carbon carrier is 1:100-1:1000; and / or, the mass ratio of activated carbon carrier to stabilizing liquid is 1:5-1:50; and / or, in the water washing process, the mass ratio of deionized water to activated carbon carrier is 1:5-1:50, and the water washing time is 0.5h-10h; and / or, the drying temperature is 120℃-150℃, and the drying time is 2h-24h.

7. The preparation method according to claim 1, characterized in that, In step (4), the active metal precursor is di(acetylacetone)platinum, and the mass ratio of di(acetylacetone)platinum to the activated carbon carrier, calculated as platinum metal, is 1:1000-1:20; and / or, the solvent used in the impregnation solution is a ketone; and / or, the mass ratio of the impregnation solution to the activated carbon carrier is 5:1-50:

1.

8. The preparation method according to claim 1, characterized in that, In step (5), the reducing gas used in the reduction treatment is hydrogen; and / or, the temperature of the reduction treatment is 120℃-180℃, and the reduction time is 1h-20h.

9. The application of the ketone-amine reductive alkylation catalyst according to claim 1 in the reaction of ketone-amine reductive alkylation to synthesize p-phenylenediamine antioxidants.

10. The application according to claim 9, characterized in that, The ketamine reductive alkylation reaction is one of the following: reductive alkylation of p-aminodiphenylamine with acetone, reductive alkylation of p-aminodiphenylamine with methyl isobutyl ketone, reductive alkylation of p-aminodiphenylamine with methyl isopentyl ketone, reductive alkylation of p-phenylenediamine with methyl isopentyl ketone, reductive alkylation of p-phenylenediamine with butanone, and reductive alkylation of p-phenylenediamine with cyclohexanone; and / or, the reactor for the reaction is a batch reactor or a fixed-bed continuous reactor.

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