Preparation and application of 6PPD metal catalyst for the production of rubber antioxidants
The catalyst, constructed synergistically with a silicon-based framework and Cu-Zn intermetallic compounds, solves the problems of high energy consumption, insufficient selectivity, and environmental pollution in the synthesis of p-phenylenediamine antioxidants in existing technologies, achieving efficient, stable, and environmentally friendly synthesis results.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANXI ZHUOHUI CHEM CO LTD
- Filing Date
- 2026-01-15
- Publication Date
- 2026-08-04
AI Technical Summary
Existing catalysts for the synthesis of p-phenylenediamine antioxidants suffer from problems such as high energy consumption, insufficient selectivity, numerous byproducts, and environmental pollution, making it difficult to achieve efficient, stable, and environmentally friendly synthesis.
A metal catalyst synergistically constructed with a silicon-based framework and Cu-Zn intermetallic compounds was prepared via a sol-gel method and combined with copper halide calcination to form a catalyst with high stability and high specific surface area, which was used for the synthesis of p-aminodiphenylamine and methyl isobutyl ketone.
It significantly improved the hydrogenation activity and selectivity of the catalyst, increased the feed conversion rate to over 96%, reduced side reactions by over 50%, lowered production costs, and improved the purity and yield of the target product.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst preparation technology, and more specifically, to the preparation and application of a metal catalyst for the production of rubber antioxidant 6PPD. Background Technology
[0002] In the field of polymer materials such as rubber and plastics, aging is one of the main factors leading to a decline in material performance and a shortened service life. Among these factors, oxidation and ozone corrosion are key processes that trigger material aging. P-phenylenediamine antioxidants, due to the presence of both benzene rings and amino groups in their molecular structure, can efficiently capture free radicals and inhibit oxidation reactions, making them important additives for delaying aging and improving durability in rubber and other products. Common p-phenylenediamine antioxidants such as 6PPD, IPPD, and DBPD can effectively protect materials from aging problems caused by heat, oxygen, ozone, and dynamic fatigue, and are widely used in tires, seals, and various industrial rubber products.
[0003] However, in the industrial synthesis of p-phenylenediamine antioxidants, the choice of catalyst directly affects the reaction conversion rate, product selectivity, and the overall economic and environmental friendliness of the process. Traditional synthesis methods often rely on high temperature and high pressure conditions, resulting in problems such as high energy consumption, insufficient selectivity, numerous byproducts, and environmental pollution. Therefore, developing efficient, stable, and environmentally compatible novel catalytic systems has become an important research direction in this field.
[0004] In synthetic reactions, catalysts primarily play three roles: activating hydrogen molecules, promoting the condensation reaction of ketones and amines, and controlling the reaction pathway to improve the selectivity of the target product. Metal catalysts, by providing surface active sites, promote the adsorption and dissociation of hydrogen molecules, participating in key steps such as nitro reduction and Schiff base hydrogenation; simultaneously, their acidic sites can catalyze condensation reactions to generate Schiff base intermediates. Currently commonly used catalytic systems include copper-based catalysts (possessing high activity, selectivity, and stability), noble metal catalysts (such as palladium, platinum, and rhodium, which exhibit excellent low-temperature and low-pressure activity and resistance to poisoning), and multi-metal composite catalysts (further enhancing performance through synergistic effects). In recent years, with the development of nanotechnology, novel nanocatalysts have exhibited more surface active sites and better mass transfer performance by controlling the nanostructure of active components, optimizing support characteristics, and constructing core-shell structures, thereby significantly improving catalytic efficiency and selectivity.
[0005] Nevertheless, existing catalyst systems still face challenges in terms of cost control, long-term stability, and environmental adaptability. To further promote the green and efficient synthesis of p-phenylenediamine antioxidants, current research focuses on developing composite catalyst systems through nanostructure design, support functionalization, and other methods, aiming to achieve better catalytic performance and sustainable process goals while reducing production costs. Summary of the Invention
[0006] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, one aspect of the present invention is to provide a method for preparing a 6PPD metal catalyst for producing rubber antioxidants, the specific steps of which are as follows: S1. Dissolve copper nitrate compound and zinc nitrate compound in deionized water, add silicate esters, and mix in a water bath. S2. Slowly add pH adjuster to the system to adjust the pH, age, filter, and wash with water 3 times to obtain the catalyst precursor; S3. Add copper halide to the obtained catalyst precursor and stir evenly. Dry in an oven at 70℃~210℃, grind, and calcine in a muffle furnace to obtain the 6PPD metal catalyst for the production of rubber antioxidants.
[0007] Preferably, the copper nitrate compound in S1 is copper nitrate or copper nitrate hydrate.
[0008] Preferably, the zinc nitrate compound in S1 is zinc nitrate or zinc nitrate hydrate.
[0009] Preferably, the silicate in S1 is tetraethyl orthosilicate, methyl silicate, tetraethyl orthosilicate, or other organosilicon substances.
[0010] Preferably, the molar ratio of copper nitrate compound, zinc nitrate compound and silicate ester in S1 is 1:0.45-0.85:0.5-1.8; the mass ratio of copper nitrate compound, zinc nitrate compound and deionized water is 0.25-0.7; the water bath temperature is 10℃-80℃; and the water bath time is 20min-90min.
[0011] Preferably, the pH adjuster in S2 is ammonia, hydrazine hydrate, sodium hydroxide, potassium hydroxide, potassium carbonate, or sodium carbonate, with a pH of 5 to 8 and an aging time of 1.5 to 3 hours.
[0012] Preferably, the copper halide in S3 is copper chloride, copper bromide, etc., and is not limited to copper sulfides. The amount of copper halide added is 0.05 mol to 0.15 mol, and it is dried in an oven at 70℃ to 210℃ for 6h to 12h. The heating rate of the muffle furnace is 5℃ / min to 20℃ / min, the calcination temperature is 400℃ to 800℃, and the calcination time is 2h to 8h.
[0013] Another aspect of the present invention is to provide an application of a metal catalyst for the production of rubber antioxidant 6PPD, wherein the metal catalyst is used in a batch or tower fixed-bed reactor to catalyze the synthesis of rubber antioxidant 6PPD from p-aminodiphenylamine and methyl isobutyl ketone.
[0014] Preferably, the metal catalyst used to produce the rubber antioxidant 6PPD needs to be activated with hydrogen (dry method, commonly used for fixed-bed copper-based catalyst activation, using nitrogen as the carrier gas, with a certain amount of hydrogen added, gradually increasing the hydrogen concentration from low to high to reduce the oxidation state of copper to zero, thus meeting the catalyst reaction requirements; wet method, often using low-concentration alcohol as a reducing agent to reduce the oxidation state of copper to zero, thus meeting the catalyst reaction requirements) for 2-4 hours. Then, p-aminodiphenylamine, methyl isobutyl ketone, and the activated catalyst are added to the reactor and reacted for 2-4 hours at 150-200°C and 1.5-4.5 MPa. This process is repeated 3-8 times, and the tower-type fixed-bed reactor can be used continuously for more than 72 hours.
[0015] Preferably, the mass ratio of the metal catalyst to methyl isobutyl methanol is 1:2.5-6, and the mass ratio of p-aminodiphenylamine, methyl isobutyl ketone and activated catalyst is 1.5-4.5:1.2-3.5:1.
[0016] The beneficial effects of this invention are as follows: Significantly enhanced catalytic performance: Through the synergistic construction of a unique silicon-based framework and Cu-Zn intermetallic compounds, the metal catalyst of this invention exhibits excellent hydrogenation activity and selectivity, and the feed conversion rate can be stably increased to over 96%, while effectively reducing side reactions by more than 50%. Thus, while improving production efficiency, it significantly enhances the purity and yield of the target product.
[0017] Synergistic effect of zinc as a co-catalyst: The introduction of zinc as a co-catalyst not only promotes the conversion of silicon powder, but also extends the effective reaction time of the core silicon-copper catalytic system and improves the overall reaction efficiency. The addition of zinc also helps to passivate or eliminate impurities in the reaction system, further ensuring the high efficiency and stability of the catalytic process.
[0018] Structural stability and cost advantages: Using a high-temperature and corrosion-resistant silicon oxide network as the structural framework, the catalyst is endowed with excellent mechanical strength and thermal stability. The metal catalyst structure of this invention also provides a high specific surface area, which makes the active sites highly dispersed. Thus, while achieving higher catalytic activity, the unit consumption of catalyst is significantly reduced, and the industrial production cost is effectively controlled.
[0019] Preparation method and structural advantages: The sol-gel method allows the catalytically active copper and zinc components to be more uniformly and stably embedded in the silica network structure. The active sites are well dispersed and highly utilized. The resulting molecular channels are more dispersed and stable than those of traditional alumina supports. They are extremely tolerant to water molecules generated during the reaction and are basically unaffected by the moisture in the system. This minimizes the inhibition of catalytic activity by water molecule adsorption, optimizes the dehydration process, and thus prolongs the effective reaction time and improves selectivity.
[0020] Comprehensive industrial application value: The metal catalyst of this invention maintains high activity and high selectivity while also being low in cost, excellent in stability and environmentally friendly. The preparation process (combination of sol-gel method and supported method) is simple to operate, has good reproducibility, and is suitable for large-scale production. It provides a new catalytic solution with high industrial application value for the efficient and green synthesis of p-phenylenediamine antioxidants.
[0021] Additional aspects and advantages of the invention will become apparent from the description which follows, or may be learned by practice of the invention. Detailed Implementation
[0022] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.
[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.
[0024] The gas chromatography analysis conditions used in the embodiments of this invention are as follows: flame ionization detector, injection port temperature: 300℃; detector temperature: 300℃; H2 flow rate: 30 ml / min; nitrogen flow rate: 300 ml / min. The initial column oven temperature is 90℃, then increased to 280℃ at a rate of 9℃ / min and held for 15 min.
[0025] Example 1 230g of copper nitrate hexahydrate and 200g of zinc nitrate hexahydrate were dissolved in 1200g of deionized water. 200g of ethyl silicate was mixed in a 40℃ water bath for 1 hour. Ammonia was slowly added dropwise to the system to adjust the pH, which was monitored in real time. When the pH reached 7, the addition of ammonia was stopped, and the mixture was aged for 1.5 hours while maintaining the pH at 7. The mixture was then filtered and washed three times with water to obtain the catalyst precursor. 3.8g of copper halide was added to the obtained catalyst precursor and stirred until homogeneous. The mixture was then dried in an oven at 120℃, ground, and calcined in a muffle furnace at 600℃ at a rate of 5℃ / min for 4 hours to obtain the metal catalyst for the production of the rubber antioxidant 6PPD.
[0026] 185g of metal catalyst used in the production of rubber antioxidant 6PPD and 740g of methyl isobutyl methanol were activated at 150℃ and 2.0MPa for 3 hours. Main reaction: 185g of the metal catalyst methyl isobutyl ketone (640ml) and 280g of p-aminodiphenylamine (280g) were added to a reaction vessel and reacted at 130℃ and 2.5MPa for 8 hours. Samples were taken for analysis, and the metal catalyst used in the production of rubber antioxidant 6PPD was reused. The chromatographic analysis results of the reaction solution are shown in Table 1 below. Table 1. Chromatographic analysis results of the reaction solution in Example 1 Example 2 450g of copper nitrate hexahydrate and 450g of zinc nitrate hexahydrate were dissolved in 1200g of deionized water. 320g of ethyl silicate was mixed in a 45℃ water bath for 1.5h. Ammonia was slowly added dropwise to the system to adjust the pH, which was monitored in real time. When the pH reached 6.5, the addition of ammonia was stopped, and the mixture was aged for 2h. The pH was maintained at 6.5 while the system was continuously monitored. The mixture was filtered and washed three times with water to obtain the catalyst precursor. 6g of copper halide was added to the obtained catalyst precursor and stirred until homogeneous. The mixture was dried in an oven at 120℃, ground, and calcined in a muffle furnace at 700℃ at a rate of 10℃ / min for 3h to obtain the metal catalyst for the production of the rubber antioxidant 6PPD.
[0027] 200g of metal catalyst for the production of rubber antioxidant 6PPD and 800g of methyl isobutyl methanol were activated at 150℃ and 2.0MPa for 4 hours. Main reaction: 200g of metal catalyst for the production of rubber antioxidant 6PPD, 750ml of methyl isobutyl ketone, and 300g of p-aminodiphenylamine were added to a reaction vessel and reacted at 160℃ and 2.5MPa for 8 hours. Samples were taken for analysis, and the metal catalyst used for the production of rubber antioxidant 6PPD was reused. The chromatographic analysis results of the reaction solution are shown in Table 2 below. Table 2. Chromatographic analysis results of the reaction liquid in Example 2 Example 3 540g of copper nitrate hexahydrate and 600g of zinc nitrate hexahydrate were dissolved in 4000g of deionized water. 350g of ethyl silicate was mixed in a 50℃ water bath for 1 hour. Ammonia was slowly added dropwise to the system to adjust the pH and the pH was monitored in real time. When the pH reached 8, the addition of ammonia was stopped, and the system was aged for 1.5 hours. The pH was monitored and maintained at 8. The mixture was filtered and washed three times with water to obtain the catalyst precursor. 10g of copper halide was added to the obtained catalyst precursor and stirred evenly. The mixture was dried in an oven at 120℃, ground, and calcined in a muffle furnace at 600℃ at a rate of 10℃ / min for 4 hours to obtain the metal catalyst for the production of rubber antioxidant 6PPD.
[0028] 300g of metal catalyst for the production of rubber antioxidant 6PPD and 1000g of methyl isobutyl methanol were activated at 150℃ and 2.0MPa for 5h. Main reaction: 300g of metal catalyst for the production of rubber antioxidant 6PPD, 1000ml of methyl isobutyl ketone, and 460g of p-aminodiphenylamine were added to a reaction vessel and reacted at 130℃ and 3MPa for 8h. Samples were taken for analysis, and the metal catalyst used for the production of rubber antioxidant 6PPD was reused. The chromatographic analysis results of the reaction solution are shown in Table 3 below. Table 3. Chromatographic analysis results of the reaction solution in Example 3 Comparative Example 1 185g of copper catalyst for production and 740g of methyl isobutyl methanol were activated at 150℃ and 2.0MPa for 3 hours. Main reaction: 185g of methyl isobutyl ketone (a metal catalyst used in the production of rubber antioxidant 6PPD) and 640ml of p-aminodiphenylamine were added to the reactor, and the reaction was carried out at 130℃ and 2.5MPa for 8 hours.
[0029] The chromatographic analysis results of the reaction solution are shown in Table 4 below: Table 4. Chromatographic analysis results of the reaction liquid in Comparative Example 1 Comparative Example 2 100g of copper catalyst for production was acid-treated and then activated in 400ml of methyl isobutyl methanol at 150℃ and 2.0MPa for 3h. Main reaction: 185g of methyl isobutyl ketone (640ml) and 280g of p-aminodiphenylamine (280g) were added to the reactor and reacted at 130℃ and 2.5MPa for 8h.
[0030] The chromatographic analysis results of the reaction solution are shown in Table 5 below: Table 5. Chromatographic analysis results of the reaction liquid in Comparative Example 2 Based on the above experimental results, compared with the copper catalyst used in production, the self-made catalyst not only possesses a stable silicon-based framework, providing high stability and high specific surface area, but also significantly enhances the hydrogenation activity and selectivity of the catalyst by constructing a Cu-Zn intermetallic compound. In Examples 1 to 3, the self-made catalyst exhibited good catalytic activity, with a conversion rate of methyl isobutyl ketone of <22%, which is more than 50% lower than the side reactions in Comparative Examples 1 and 2, and it can still maintain a high conversion rate after multiple cycles. The sol-gel method used in the catalyst preparation process provides better dispersion of the catalyst active sites and higher catalytic utilization. Catalytically active copper and zinc can more effectively enter the SiO2 oxide network, releasing more active sites and improving the stability and activity of the catalyst.
[0031] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.
Claims
1. A method for preparing a metal catalyst for producing rubber antioxidant 6PPD, characterized in that: The specific steps of the preparation method are as follows: S1. Dissolve copper nitrate compound and zinc nitrate compound in deionized water, add silicate esters, and mix in a water bath. S2. Slowly add pH adjuster to the system to adjust the pH, age, filter, and wash with water 3 times to obtain the catalyst precursor; S3. Add copper halide to the obtained catalyst precursor and stir evenly. Dry in an oven at 70℃~210℃, grind, and calcine in a muffle furnace to obtain the 6PPD metal catalyst for the production of rubber antioxidant. The molar ratio of copper nitrate compound, zinc nitrate compound and silicate ester in S1 is 1:0.45-0.85:0.5-1.
8.
2. The preparation method of a metal catalyst for producing rubber antioxidant 6PPD according to claim 1, characterized in that: The copper nitrate compound in S1 is copper nitrate or copper nitrate hydrate.
3. The preparation method of a metal catalyst for producing rubber antioxidant 6PPD according to claim 1, characterized in that: The zinc nitrate compound in S1 is zinc nitrate or zinc nitrate hydrate.
4. The preparation method of a metal catalyst for producing rubber antioxidant 6PPD according to claim 1, characterized in that: The silicate in S1 is tetraethyl orthosilicate, methyl silicate, tetraethyl orthosilicate, or other organosilicon substances.
5. The method for preparing a metal catalyst for producing rubber antioxidant 6PPD according to claim 1, characterized in that: The water bath temperature is 10℃~80℃, and the water bath time is 20min~90min.
6. The method for preparing a metal catalyst for producing rubber antioxidant 6PPD according to claim 1, characterized in that: The pH adjuster in S2 is ammonia, hydrazine hydrate, sodium hydroxide, potassium hydroxide, potassium carbonate, or sodium carbonate, adjusting the pH to pH=5-8, and the aging time is 1.5h-3h.
7. The method for preparing a metal catalyst for producing rubber antioxidant 6PPD according to claim 1, characterized in that: The copper halide in S3 is copper chloride or copper bromide, and the amount of copper halide added is 0.05 mol to 0.15 mol. It is dried in an oven at 70℃ to 210℃ for 6h to 12h. The heating rate of the muffle furnace is 5℃ / min to 20℃ / min, the calcination temperature is 400℃ to 800℃, and the calcination time is 2h to 8h.
8. The application of the metal catalyst for producing rubber antioxidant 6PPD obtained by the preparation method according to claim 1, characterized in that: The metal catalyst is used in batch and tower-type fixed-bed reactors to catalyze the synthesis of rubber antioxidant 6PPD from p-aminodiphenylamine and methyl isobutyl ketone.
9. The application of the metal catalyst for producing rubber antioxidant 6PPD according to claim 8, characterized in that: The metal catalyst used to produce the rubber antioxidant 6PPD needs to be activated with hydrogen for 2-4 hours under the conditions of methyl isobutyl methanol at 100℃-185℃ and 1.2MPa-4.5MPa. Then, p-aminodiphenylamine, methyl isobutyl ketone and the activated catalyst are added to the reactor and reacted for 2-4 hours under the conditions of 150℃-200℃ and 1.5MPa-4.5MPa. This process is repeated 3-8 times, and the tower-type fixed-bed reactor can be used continuously for more than 72 days.
10. The application of the metal catalyst for producing rubber antioxidant 6PPD according to claim 9, characterized in that: The mass ratio of the metal catalyst to methyl isobutyl methanol is 1:2.5-6, and the mass ratio of p-aminodiphenylamine, methyl isobutyl ketone and the activated catalyst is 1.5-4.5:1.2-3.5:1.