Preparation method of copper-loaded cerium oxide catalyst and application thereof

Abstract

This invention discloses a method for preparing a copper-supported cerium oxide catalyst and its application, relating to the field of catalyst technology. The preparation method includes the following steps: S1, preparing cerium oxide via a hydrothermal method to obtain CeO2; S2, preparing the copper-supported cerium oxide catalyst: adding anhydrous copper chloride, PVP, and CeO2 to a mixed solution of N,N-dimethylformamide and water, stirring, and then sonicating. During sonication, hydrazine hydrate is added dropwise. After sonication, the mixture is filtered, and the filter cake is washed alternately with deionized water and ethanol to remove impurities and free copper ions from the composite material. Finally, it is vacuum dried to obtain the copper-supported cerium oxide catalyst Cu / CeO2. This invention prepares an interfacial oxygen-rich vacancy-type Cu / CeO2 catalyst for highly efficient catalytic dehydrazine grouping reactions of aromatic hydrazine derivatives, characterized by high catalytic efficiency, mild conditions, good stability, easy recovery, and reusability.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a method for preparing a copper-supported cerium oxide catalyst and its application. Background Technology

[0002] In the chemical industry, hydrazine compounds play a crucial role as intermediates in organic synthesis. For example, they can be used as raw materials to synthesize important organic compounds such as aminourea and bacitracin, and are also used as liquid rocket fuel, photographic developing agents, antioxidants, and reducing agents. However, when hydrazine compounds are present in wastewater, they pollute the environment and harm human health, causing significant side effects on the liver, kidneys, and blood systems. Furthermore, hydrazine, as a known toxic substance, also possesses potential carcinogenicity. Therefore, the removal of hydrazine groups from hydrazine-containing wastewater has become a hot research topic. In addition, the removal of hydrazine groups from hydrazine compounds is also an important method for synthesizing other heterocyclic compounds.

[0003] Chattopadhyaya and Reese reported a method for obtaining arachidonic acid by using excess mercuric oxide as a catalyst in the removal of the hydrazine group at the 8-position after hydrazinolysis of 8,2-epoxyadenosine. In 2006, Cesnek et al. reported a method for removing the hydrazine group at the 6-position of 2-chloro-6-hydrazide-9-isopropyl derivatives using excess silver oxide as a catalyst to generate 2-chloro-9-isopropylpurine derivatives. However, this method uses excessive heavy metals, which violates the principles of green chemistry, and the target product still contains residual heavy metals, and these problems cannot be solved. Espinosa et al. found a method to remove the hydrazine group using a strong base such as DBU. Although it does not use heavy metals as a catalyst, the reaction yield is low, and it is not a good method either. Liu Zhongquan et al. reacted sodium nitroprusside with phenylhydrazine derivatives to remove the hydrazine group. Although it did not use heavy metals and strong bases, it generated many byproducts. In 2014, Jiang et al. used excess transition metal CoPc to catalyze the selective radical arylation of aniline with arylhydrazine to synthesize 2-aminobenzyl, but the yield was low. In the same year, Xia et al. reported a method for dehydrazine removal in water using CuSO4 as a catalyst. However, CuSO4 as a catalyst cannot be recycled and will be discharged into wastewater after the reaction is completed, causing harm to the environment. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing copper-supported cerium oxide catalyst and its application, which avoids the use of heavy metal residues and toxic and harmful reagents in traditional methods, simplifies the operation process, reduces production costs, and exhibits high yield and good environmental friendliness.

[0005] The technical solution of this invention: A method for preparing a copper-supported cerium oxide catalyst includes the following steps: S1. Hydrothermal preparation of cerium oxide: Cerium nitrate aqueous solution and sodium hydroxide aqueous solution were prepared separately. The cerium nitrate aqueous solution was slowly added dropwise to the sodium hydroxide aqueous solution and stirred. After obtaining a light purple solution, it was transferred to a high-pressure reactor for reaction. After the reaction was completed, it was cooled to room temperature, filtered, and the filter cake was washed alternately with water and ethanol. The washed filter cake was dried to finally obtain CeO2. S2. Preparation of copper-supported cerium oxide catalyst: Anhydrous copper chloride, PVP (polyvinylpyrrolidone), and CeO2 obtained in step S1 were added to a mixed solution of N,N-dimethylformamide and water at room temperature. After stirring, the mixture was sonicated. Hydrazine hydrate was added dropwise during the sonication. After sonication, the mixture was filtered and the filter cake was washed alternately with deionized water and ethanol to remove impurities and free copper ions. Finally, the mixture was vacuum dried to obtain the copper-supported cerium oxide catalyst Cu / CeO2.

[0006] Preferably, the concentration of the cerium nitrate aqueous solution in step S1 is 1.5-2.0 mol / L; The concentration of the sodium hydroxide aqueous solution is 0.04-0.06 mol / L; The molar ratio of cerium nitrate to sodium hydroxide is 4:1.

[0007] Preferably, the light purple solution is reacted in a high-pressure reactor at a temperature of 100°C for a reaction time of 20-28 hours. The preferred reaction time is 24 hours.

[0008] Preferably, in step S1, the cerium nitrate aqueous solution is slowly added to the sodium hydroxide aqueous solution over a period of 5-6 minutes, and the stirring time is 0.5-4 hours. After filtration, the filter cake is washed alternately with water and ethanol. The mass ratio of water, ethanol and filter cake is 1-6:1-6:1, and the washing is repeated 3 times.

[0009] Preferably, the temperature for drying the filter cake in step S1 is 80°C, and the drying time is 10-16 hours. The preferred drying time is 12 hours.

[0010] Preferably, in step S2, the mass ratio of anhydrous copper chloride:PVP:CeO2 is 0.8-13.9:25:100, preferably 2.4:25:100; The volume ratio of N,N-dimethylformamide:water:hydrazine hydrate is 15:35:1; CeO2:hydrazine hydrate was 100 mg: 0.3 mL; The stirring time is 20-40 minutes; the preferred stirring time is 30 minutes. The ultrasonic treatment temperature is 60℃, the ultrasonic treatment time is 15-60 min, and the ultrasonic frequency is 30-200 kHz.

[0011] Preferably, in step S2, after filtration, the filter cake is washed alternately with water and ethanol, and the mass ratio of water, ethanol and filter cake is 1-6:1-6:1, and the washing is repeated 3 times.

[0012] Preferably, the drying temperature in step S2 is 60°C, the drying time is 10-15 hours, preferably 12 hours, and the vacuum degree is -100 Pa.

[0013] Secondly, the application of a copper-supported cerium oxide catalyst for the dehydrazine grouping reaction of phenylhydrazine derivatives.

[0014] Preferably, the phenylhydrazine derivative is an aromatic hydrazine and its derivatives, including 2,4-dinitrophenylhydrazine, 4-nitrophenylhydrazine, 3-toluidine, 2-chlorophenylhydrazine, 2-hydrazinepyridine, and 2-hydrazylbenzothiazole.

[0015] The room temperature of this invention is 18-38℃.

[0016] The beneficial effects of this invention are: This invention prepares an interfacial oxygen-enriched vacancy-type Cu / CeO2 catalyst, which can efficiently catalyze the dehydrazine reaction of aromatic hydrazine derivatives without the need for additional chemical oxidants. This catalyst is prepared via liquid-phase synthesis and features high catalytic efficiency, mild conditions, good stability, easy recovery, and reusability. This invention also prepares a Cu / CeO2 composite material and uses it to catalyze the dehydrazine reaction of phenylhydrazine derivatives. Studies show that at room temperature, Cu / CeO2 can effectively catalyze the dehydrazine reaction of 2,4-dinitrophenylhydrazine to 1,3-dinitrobenzene, without the need for additional chemical oxidants, utilizing only oxygen from the air. After 6 hours of reaction, the conversion rate reaches 92.27%. This catalyst is easily recoverable and exhibits good stability, maintaining excellent catalytic performance even after five consecutive uses. This catalytic system can proceed smoothly in both organic solvents and aqueous phases, avoiding the use of heavy metal residues and toxic reagents in traditional methods, simplifying the operation process, reducing production costs, and demonstrating high yield, good environmental friendliness, and a wide range of substrate applicability. In summary, this invention provides an effective route for green and efficient dehydrazine removal reactions. Attached Figure Description

[0017] Figure 1 The XRD patterns of Cu / CeO2 composite materials with different Cu loadings according to the present invention are shown. Figure 2 The UV-Vis spectra of 2,4-dinitrophenylhydrazine DMF solutions of different concentrations in this invention are shown. Figure 3 This is a standard curve diagram of 2,4-dinitrophenylhydrazine according to the present invention; Figure 4This is a graph showing the effect of different Cu loadings on the reaction in this invention; Figure 5 The graph shows the effect of the amount of 1% Cu / CeO2 catalyst supported on the catalytic reaction in this invention. Detailed Implementation

[0018] Example 1 S1. Hydrothermal preparation of cerium oxide: Weigh 5.22 g (0.012 mol) of cerium nitrate hexahydrate and dissolve it in 7.5 mL of deionized water. Weigh 0.12 g (0.003 mol) of sodium hydroxide and dissolve it in 52.5 mL of deionized water. Stir each solution for 10 min. Slowly add the dissolved cerium nitrate solution dropwise to the sodium hydroxide solution over 5 min and stir for 30 min. After obtaining a light purple solution, transfer it to a high-pressure reactor and react at 100 °C for 24 h. After cooling to room temperature, filter the solution and wash the reactants three times with water and ethanol alternately, with a mass ratio of reactant:water:ethanol of 1:2:2 each time. Dry the resulting filter cake in a forced-air drying oven at 80 °C for 12 h to obtain a light yellow CeO2.

[0019] S2. Preparation of copper-supported cerium oxide catalyst:

[0020] 2.4 mg of anhydrous copper chloride, 25 mg of PVP, and 0.1 g of CeO2 were added to a mixed solution of 4.5 mL of N,N-dimethylformamide and 10.5 mL of water. After stirring for 30 min, 0.3 mL of hydrazine hydrate, a reducing agent, was added dropwise while sonicating at 60 °C for 30 min at a frequency of 100 kHz. After sonication, the mixture was filtered and washed three times alternately with deionized water and ethanol at a mass ratio of 1:2:2 each time to remove impurities and free copper ions from the composite material. Finally, the mixture was dried in a vacuum oven at -100 Pa at 60 °C for 12 h to obtain a black Cu / CeO2 catalyst. A Cu / CeO2 catalyst with a copper content of 1% was prepared, and the samples were labeled as 1% Cu / CeO2 (1% being the mass fraction of copper).

[0021] Example 2

[0022] Following the preparation method of Example 1, a Cu / CeO2 catalyst with a copper content of 0.4% was prepared by changing the amount of anhydrous copper chloride in step S2 to 0.8 mg. The samples were labeled as 0.4%Cu / CeO2 (0.4% being the mass fraction of copper).

[0023] Example 3

[0024] Following the preparation method of Example 1, Cu / CeO2 catalysts with a copper content of 2% were prepared by changing the amount of anhydrous copper chloride in step S2 to 3.9 mg. The samples were labeled as 2% Cu / CeO2 (2% being the mass fraction of copper).

[0025] Example 4

[0026] Following the preparation method of Example 1, Cu / CeO2 catalysts with a copper content of 3% were prepared by changing the amount of anhydrous copper chloride in step S2 to 5.85 mg. The samples were labeled as 3% Cu / CeO2 (3% being the mass fraction of copper).

[0027] Example 5

[0028] Following the preparation method of Example 1, Cu / CeO2 catalysts with a copper content of 4% were prepared by changing the amount of anhydrous copper chloride in step S2 to 7.8 mg. The samples were labeled as 4% Cu / CeO2 (4% being the mass fraction of copper).

[0029] Example 6

[0030] Following the preparation method of Example 1, Cu / CeO2 catalysts with a copper content of 5% were prepared by changing the amount of anhydrous copper chloride in step S2 to 13.5 mg. The samples were labeled as 5% Cu / CeO2 (5% being the mass fraction of copper).

[0031] Example 7 S1. Hydrothermal preparation of cerium oxide: Weigh 5.22 g (0.012 mol) of cerium nitrate hexahydrate and dissolve it in 6 mL of deionized water, and dissolve 0.12 g (0.003 mol) of sodium hydroxide in 75 mL of deionized water. Stir each solution for 10 min. Slowly add the dissolved cerium nitrate solution dropwise to the sodium hydroxide solution over 5 min and stir for 4 h. After obtaining a light purple solution, transfer it to a high-pressure reactor and react at 100 °C for 20 h. After cooling to room temperature, filter the solution and wash the reactants three times with water and ethanol alternately, with a mass ratio of reactant:water:ethanol of 1:1:1 each time. Dry the resulting filter cake in a forced-air drying oven at 80 °C for 10 h to obtain a light yellow CeO2.

[0032] S2. Preparation of copper-supported cerium oxide catalyst:

[0033] 2.4 mg of anhydrous copper chloride, 25 mg of PVP, and 0.1 g of CeO2 were added to a mixed solution of 4.5 mL of N,N-dimethylformamide and 10.5 mL of water. After stirring for 40 min, 0.3 mL of hydrazine hydrate, a reducing agent, was added dropwise while sonicating at 60 °C for 60 min at a frequency of 200 kHz. After sonication, the mixture was filtered and washed three times alternately with deionized water and ethanol at a mass ratio of 1:1:1 to remove impurities and free copper ions from the composite material. Finally, the mixture was dried in a vacuum oven at -100 Pa at 60 °C for 10 h to obtain a black Cu / CeO2 catalyst. A Cu / CeO2 catalyst with a copper content of 1% was prepared, and the samples were labeled as 1% Cu / CeO2 (1% being the mass fraction of copper).

[0034] Example 8 S1. Hydrothermal preparation of cerium oxide: Weigh 5.22 g (0.012 mol) of cerium nitrate hexahydrate and dissolve it in 4.8 mL of deionized water, and dissolve 0.12 g (0.003 mol) of sodium hydroxide in 60 mL of deionized water. Stir each solution for 10 min. Slowly add the dissolved cerium nitrate solution dropwise to the sodium hydroxide solution over 6 min and stir for 1 h. After obtaining a light purple solution, transfer it to a high-pressure reactor and react at 100 °C for 28 h. After cooling to room temperature, filter the solution and wash the reactants three times with alternating water and ethanol. The mass ratio of reactant:water:ethanol for each wash is 1:0.33:0.33. Dry the resulting filter cake in a forced-air drying oven at 80 °C for 16 h to obtain a light yellow CeO2.

[0035] S2. Preparation of copper-supported cerium oxide catalyst:

[0036] 2.4 mg of anhydrous copper chloride, 25 mg of PVP, and 0.1 g of CeO2 were added to a mixed solution of 4.5 mL of N,N-dimethylformamide and 10.5 mL of water. After stirring for 20 min, 0.3 mL of hydrazine hydrate, a reducing agent, was added dropwise while sonicating at 60 °C for 15 min at a frequency of 30 kHz. After sonication, the mixture was filtered and washed three times alternately with deionized water and ethanol, with a mass ratio of reactant:water:ethanol of 1:0.33:0.33 each time, to remove impurities and free copper ions from the composite material. Finally, the mixture was dried in a vacuum oven at -100 Pa at 60 °C for 15 h to obtain a black Cu / CeO2 catalyst. A Cu / CeO2 catalyst with a copper content of 1% was prepared, and the samples were labeled as 1% Cu / CeO2 (1% being the mass fraction of copper).

[0037] Comparative Example 1

[0038] Treatment of cerium oxide with hydrazine hydrate: Weigh 0.1g of cerium oxide prepared in step S1 of Example 1 above, add 25mg PVP, 4.5mL LDMF, and 10.5mL deionized water and stir for 30min. Then add 0.3mL hydrazine hydrate at 60℃. The solution turns grayish-purple. Then sonicate for 30min at a frequency of 100kHz. Filter and wash the reactants with water and ethanol alternately. Wash the reactants with deionized water and ethanol alternately 3 times. Each time, the mass ratio of reactants:water:ethanol is 1:2:2. Dry the resulting filter cake in a vacuum oven at -100pa at 60℃ for 12 hours. Finally, hydrazine hydrate pretreated CeO2 is obtained.

[0039] Comparative Example 2

[0040] Commercially available 99.99% pure copper oxide was ultrasonicated at 60°C with 0.3 mL of reducing agent hydrazine hydrate added dropwise. The mixture was ultrasonicated for 30 min at a frequency of 100 kHz. After ultrasonication, the mixture was filtered and washed three times alternately with deionized water and ethanol, with a mass ratio of reactant:water:ethanol of 1:2:2 each time, to remove impurities from the composite material. Finally, the mixture was dried in a vacuum oven at 60°C and -100 Pa for 12 h to obtain a black hydrazine hydrate pretreated Cu catalyst.

[0041] Comparative Example 3

[0042] The CeO2 pretreated with hydrazine hydrate prepared in Comparative Example 1 and the Cu catalyst pretreated with hydrazine hydrate prepared in Comparative Example 2 were mixed in a mass ratio of 1:74.

[0043] Application examples Copper-supported cerium oxide catalysts were used to catalyze the dehydrazine reaction of aromatic hydrazides and their derivatives.

[0044] The reaction was carried out in DMF solution using 2,4-dinitrophenylhydrazine as a substrate, and the reaction was monitored by UV-Vis spectroscopy.

[0045] The dehydrazine reaction conditions were as follows: 15 mg of catalyst was dispersed in 15 mL of 1.25 mM 2,4-dinitrophenylhydrazine DMF solution at room temperature (25 °C) with a sampling interval of 1.0 h. 300.0 μL of the reaction solution was then diluted in 3.0 mL of DMF solution. After each sampling, the change in the hydrazine peak at 360 nm was recorded using a UV-Vis spectrophotometer. Finally, the conversion rate was calculated using Beer-Lambert's law.

[0046] 2,4-dinitrophenylhydrazine (DMF) solutions of 0.1–0.6 g / L were prepared, and the absorbance changes at different concentrations were monitored using a UV-Vis spectrophotometer. The results are as follows: Figure 2 As shown, the changes in absorbance at 360 nm in the UV-Vis spectrum were recorded, and a standard curve of absorbance versus 2,4-dinitrophenylhydrazine concentration was plotted. Figure 3As shown, its standard curve equation is: y = 2.45036x + 0.00975, R0 2 =0.99938.

[0047] Figure 1 XRD patterns of Cu / CeO2 composites with different Cu loadings are shown. The composition and structure of the composites were determined by XRD. Figure 1 The diffraction peaks of CeO2 sample B treated with hydrazine hydrate and CeO2 sample A prepared by hydrothermal method are the same as those in the CeO2 standard card (PDF#34–0394), indicating that the hydrazine hydrate treatment did not change the crystal structure of CeO2. Simultaneously, the crystal structure of Cu was also determined by comparison with the PDF standard card (PDF#04-0836), confirming that the loaded copper is zero-valent copper. The relatively sharp peaks at 2θ=43.19°, 50.29°, 73.88°, and 89.61° in the XRD pattern of 5% Cu / CeO2 correspond to the (111), (200), (220), and (311) crystal planes of Cu, respectively, thus proving the successful introduction of Cu. No Cu diffraction peaks were observed in the XRD pattern of 1% Cu / CeO2 due to the low Cu content.

[0048] Application Example 1

[0049] The catalytic verification was performed using copper-supported cerium oxide catalysts to catalyze the dehydrazine reaction of 2,4-dinitrophenylhydrazine. The catalysts used were those from Examples 1-6 (excluding Example 4).

[0050] from Figure 4 It can be seen that adding catalysts with different copper loadings to catalyze the dehydrazine reaction of 2,4-dinitrophenylhydrazine, such as Figure 4 As shown, the conversion rate increases with increasing Cu loading. The conversion rate is highest when the Cu loading is 1%, but it gradually decreases beyond 1%, indicating that excessive metal loading is not conducive to the reaction. This may be because Cu nanoparticles may agglomerate when the metal loading is too high. Therefore, a copper loading of 1% is the optimal loading for the Cu / CeO2 composite material.

[0051] Application Example 2

[0052] The catalytic verification was performed using copper-supported cerium oxide catalyst under the conditions for catalyzing the dehydrazinolation reaction of 2,4-dinitrophenylhydrazine, examining the effect of the amount of catalyst prepared in Example 1 on the reaction. Figure 5 As shown in Table 1, the reaction cannot proceed without a catalyst (labeled 1), but the conversion rate gradually increases after adding a catalyst. The highest conversion rate, reaching 92.21%, is achieved when the catalyst dosage reaches 25 mg (labeled 5). Therefore, considering cost factors, 15 mg is selected as the optimal catalyst dosage.

[0053] Table 1 Effect of catalyst dosage on the reaction

[0054] Application Example 3 The catalytic verification was carried out using copper-supported cerium oxide catalyst for the dehydrazine reaction of 2,4-dinitrophenylhydrazine, and the effect of different catalysts on the catalytic reaction was investigated. The results are shown in Table 2.

[0055] To investigate the synergistic catalytic effect between Cu and CeO2, the pretreatment of Cu with hydrazine hydrate was examined. 0 CeO2 synthesized by hydrothermal method, CeO2 pretreated with hydrazine hydrate, and Cu pretreated with hydrazine hydrate 0+ The effect of mixing CeO2 pretreated with hydrazine hydrate on the dehydrazine reaction was investigated. Table 2 shows that the catalytic conversion rate of CeO2 synthesized by the hydrothermal method was only 12.7% at a reaction time of 6 h, while the catalytic conversion rate of CeO2 modified with hydrazine hydrate increased to 67.8%, indicating that hydrazine hydrate reduction treatment enhanced the catalytic performance of cerium oxide. The catalytic conversion rate of copper treated with only hydrazine hydrate reduction was 49.8%. However, when the copper-supported Cu / CeO2 catalyst catalyzed this reaction, the conversion rate of 2,4-dinitrophenylhydrazine reached 92.27%, indicating a synergistic catalytic relationship between copper and cerium oxide. Additionally, in Comparative Example 2, Cu pretreated with hydrazine hydrate... 0+ Compared to Example 1, the catalytic performance of the copper-supported cerium oxide catalyst, which was simply mixed with hydrazine hydrate pretreated CeO2, was significantly lower. This indicates that the copper-supported cerium oxide catalyst synthesized in this application is not a simple mixture, but rather exhibits a synergistic effect between copper and cerium oxide after loading. In summary, Cu / CeO2 demonstrates excellent catalytic activity in the dehydrazide grouping reaction of 2,4-dinitrophenylhydrazine.

[0056] Table 2 Effect of different catalysts on the reaction

[0057] Application Example 4 Using water as a solvent, copper-supported cerium oxide catalyst was used for the reaction of aromatic hydrazine and its derivatives, and the structure of the products was confirmed.

[0058] Because aromatic hydrazines and their derivatives have poor solubility in water at room temperature, the reaction must be carried out under heating conditions. The reaction was monitored by thin-layer chromatography (TLC). After the reaction was completed, the catalyst was filtered, extracted with dichloromethane, the organic phases were combined, the solvent was removed by rotary evaporation, and the product was purified by column chromatography, and the yield was calculated. The structure of the product was determined using... 1 HNMR confirmed.

[0059] Expansion of reaction substrates The dehydrazine reaction conditions were verified by catalysis using water or DMF as solvents at 85°C and with a catalyst dosage of 10-30 mg to catalyze phenylhydrazine derivatives with different substituents, and the suitability of the catalyst was investigated. Table 3 shows that under optimal conditions, phenylhydrazines with different substituents yielded the corresponding dehydrazine products in excellent yields, all maintaining yields above 85%.

[0060] Table 3 Dehydrazine reactions of different substrates under 1% Cu / CeO2 catalysis (Example 1) ab

[0061] a Reaction conditions: 1 mmol of substrate, water or DMF as solvent, water at 85°C, and 10-30 mg of catalyst. b Separation yield.

[0062] The specific experimental steps are as follows: Application Example 4-1-1 Using DMF as a solvent, the copper-cerium composite nanocatalyst prepared in Example 1 catalyzes the dehydrazineization of 2,4-dinitrophenylhydrazine. 198.6 mg (1 mmol) of 2,4-dinitrophenylhydrazine was dispersed in 30 mL of DMF solution at room temperature, and then 30 mg of Cu / CeO2 composite material was added. The mixture was stirred at 25 °C for 5 h. After the reaction was detected by thin-layer chromatography (TLC), the mixture was filtered, extracted with dichloromethane, and the organic phases were combined. The mixture was dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporation to obtain 154.2 mg of white solid, with a yield of 91.7%.

[0063] Main product: 1 H NMR (500 MHz, Chloroform- d )δ7.80(t, J =7.8 Hz, 1H), 7.48(q, J =7.0Hz, 1H), 7.32.

[0064] Application Example 4-1-2 Using water as a solvent, the copper-cerium composite nanocatalyst prepared in Example 1 catalyzes the dehydrazineization of 2,4-dinitrophenylhydrazine. 198.6 mg (1 mmol) of 2,4-dinitrophenylhydrazine was dissolved in 30 mL of distilled water, and then 30 mg of Cu / CeO2 composite material was added. The reaction was carried out at 85 °C, at which point the system changed from orange-red to dark green. The reaction was stirred for 5 h. After the reaction was completed by thin-layer chromatography (TLC), the catalyst was filtered, and the mixture was extracted with dichloromethane. The organic phases were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporation to obtain 148.1 mg of white solid, with a yield of 88.1%.

[0065] Main product: 1 H NMR (500 MHz, Chloroform- d )δ7.80(t, J =7.8 Hz, 1H), 7.48(q, J =7.0Hz, 1H), 7.32.

[0066] Application Example 4-2 Using water as a solvent, the copper-cerium composite nanocatalyst prepared in Example 1 catalyzes the dehydrazineization of 4-nitrophenylhydrazine. 153.1 mg (1 mmol) of 4-nitrophenylhydrazine was dissolved in 10 mL of distilled water at 85 °C. Then, 10 mg of Cu / CeO2 composite material was added, and the mixture was stirred for 5 h. After the reaction was completed, the catalyst was filtered off, and the mixture was extracted three times with dichloromethane. The organic phases were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporation to obtain 107.1 mg of a pale yellow oily liquid, with a yield of 87.0%.

[0067] Main product: 1 H NMR (500 MHz, Chloroform- d )δ7.29–7.24(m,2H),6.77–6.73(m,1H),6.62–6.56(m,2H).

[0068] Application Example 4-3 Using water as a solvent, the copper-cerium composite nanocatalyst prepared in Example 1 catalyzes the dehydrazineization of 3-toluhydrazide. 122.17 mg (1 mmol) of 3-toluidine was dissolved in 10 mL of distilled water at 85 °C, and then 10 mg of Cu / CeO2 composite material was added. The system was pale yellow. The reaction was stirred for 5 h. After the reaction was completed by thin-layer chromatography (TLC), the catalyst was filtered, and the mixture was extracted three times with dichloromethane. The organic phases were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by distillation under normal pressure to obtain 79.3 mg of colorless liquid, with a yield of 86.1%.

[0069] Main product: 1H NMR (500 MHz, Chloroform- d )δ7.33(dd, J =8.1,7.0 Hz,2H),7.27–7.24(m,2H),7.23(d, J =7.6 Hz, 1H), 2.43 (s, 3H).

[0070] Example 4-4 Using water as a solvent, the copper-cerium composite nanocatalyst prepared in Example 1 catalyzes the dehydrazineization of 2-chlorophenylhydrazine. 170.6 mg (1 mmol) of 2-chlorophenylhydrazine was dissolved in 10 mL of distilled water at 85 °C, and then 10 mg of Cu / CeO2 composite material was added. The mixture was stirred and reacted for 5 h. After the reaction was detected by thin-layer chromatography (TLC), the catalyst was filtered, and the mixture was extracted three times with dichloromethane. The organic phases were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporation to obtain 97.6 mg of colorless liquid, with a yield of 86.7%.

[0071] Main product: 1 H NMR (500 MHz, Chloroform- d )δ7.26(s,2H),7.22(s,2H),7.16(s,1H).

[0072] Application Example 4-5 Using water as a solvent, the copper-cerium composite nanocatalyst prepared in Example 1 catalyzes the dehydrazideation of 2-hydrazidepyridine. 109.1 mg (1 mmol) of 2-hydrazidepyridine was dissolved in 10 mL of distilled water at 85 °C, and then 10 mg of Cu / CeO2 composite material was added. The mixture was stirred and reacted for 5 h. After the reaction was detected by thin-layer chromatography (TLC), the catalyst was filtered, and the mixture was extracted three times with dichloromethane. The organic phases were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporation to obtain 71.9 mg of colorless liquid, with a yield of 91.0%.

[0073] Main product: 1 H NMR (500 MHz, Chloroform-d) δ8.26–8.15(m,2H),7.30–7.22(m,1H),6.91–6.82(m,2H).

[0074] Application Example 4-6 Using water as a solvent, the copper-cerium composite nanocatalyst prepared in Example 1 catalyzes the dehydrazineization of 2-hydrazinobenzothiazole. 165.1 mg (1 mmol) of 2-hydrazinobenzothiazole was dissolved in 20 mL of distilled water at 85 °C. Then, 10 mg of Cu / CeO2 composite material was added. The system turned light purple. After stirring for 6 h, the reaction was detected by thin-layer chromatography (TLC). After the reaction was completed, the catalyst was filtered, and the mixture was extracted three times with dichloromethane. The organic phases were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporation to obtain 115.0 mg of oily liquid, with a yield of 85.1%.

[0075] Main product: 1 H NMR (500 MHz, Chloroform- d )δ8.98(s,1H),8.14(d, J =8.2 Hz, 1H), 7.94 (d, J =8.0 Hz,1H),7.55–7.48(m,1H),7.43(t, J =7.6 Hz, 1H).

[0076] 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 copper-supported cerium oxide catalyst for dehydrazino reaction of phenylhydrazine derivatives, characterized by, Includes the following steps: S1. Hydrothermal preparation of cerium oxide: Cerium nitrate aqueous solution and sodium hydroxide aqueous solution were prepared separately. The cerium nitrate aqueous solution was slowly added dropwise to the sodium hydroxide aqueous solution and stirred. After obtaining a light purple solution, it was transferred to a high-pressure reactor for reaction. After the reaction was completed, it was cooled to room temperature, filtered, and the filter cake was washed alternately with water and ethanol. The washed filter cake was dried to finally obtain CeO2. S2. Preparation of copper-supported cerium oxide catalyst: Anhydrous copper chloride, PVP, and CeO2 obtained in step S1 were added to a mixed solution of N,N-dimethylformamide and water at room temperature. After stirring, the mixture was sonicated. Hydrazine hydrate was added dropwise during the sonication. After sonication, the mixture was filtered and the filter cake was washed alternately with deionized water and ethanol to remove impurities and free copper ions. Finally, the mixture was vacuum dried to obtain the copper-supported cerium oxide catalyst Cu / CeO2.

2. The production method according to claim 1, characterized by, The concentration of the cerium nitrate aqueous solution in step S1 is 1.5-2.0 mol / L; The concentration of the sodium hydroxide aqueous solution is 0.04-0.06 mol / L; The molar ratio of cerium nitrate to sodium hydroxide is 4:

1.

3. The method of claim 1, wherein the compound is prepared by the method of claim 1. In step S1, the light purple solution is reacted in a high-pressure reactor at a temperature of 100°C for a time of 20-28 hours.

4. The preparation method according to claim 1, characterized in that, In step S1, the cerium nitrate aqueous solution is slowly added dropwise to the sodium hydroxide aqueous solution over a period of 5-6 minutes, and the stirring time is 0.5-4 hours. After filtration, the filter cake is washed alternately with water and ethanol. The mass ratio of water, ethanol and filter cake is 1-6:1-6:1, and the washing is repeated 3 times.

5. The preparation method according to claim 1, characterized in that, In step S1, the filter cake is dried at a temperature of 80°C for 10-16 hours.

6. The preparation method according to claim 1, characterized in that, In step S2, the mass ratio of anhydrous copper chloride:PVP:CeO2 is 0.8-13.9:25:100; The volume ratio of N,N-dimethylformamide:water:hydrazine hydrate is 15:35:1; CeO2:hydrazine hydrate was 100 mg: 0.3 mL; The stirring time is 20-40 minutes; The ultrasonic treatment temperature is 60℃, the ultrasonic treatment time is 15-60 min, and the ultrasonic frequency is 30-200 kHz.

7. The preparation method according to claim 1, characterized in that, In step S2, after filtration, the filter cake is washed alternately with water and ethanol. The mass ratio of water, ethanol and filter cake is 1-6:1-6:1, and the mixture is washed alternately 3 times.

8. Use of a copper-supported ceria catalyst prepared according to the preparation method of any one of claims 1 to 7, characterized in that, Used for the dehydrazine grouping reaction of phenylhydrazine derivatives.

9. Use according to claim 8, characterized in that, The phenylhydrazine derivatives include 2,4-dinitrophenylhydrazine, 4-nitrophenylhydrazine, 3-methylphenylhydrazine, or 2-chlorophenylhydrazine.

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