NiCo catalyst and application thereof in preparation of 5-amino-1-pentanol by selective hydrogenolysis of furfurylamine

Abstract

This invention discloses a NiCo catalyst, which is prepared by dissolving nickel salt, cobalt salt, and aluminum salt in deionized water, adding a liquid containing sodium hydroxide and sodium carbonate under stirring to adjust the pH of the mixture to 9-11, placing the mixture in a sealed reactor, and hydrothermally reacting at 70-90°C for 24 hours. The solid is centrifuged, washed until neutral, dried, ground, calcined at 400-500°C for 3-5 hours, and then reduced at 400-500°C for 3-5 hours under a hydrogen atmosphere, followed by cooling. The catalyst prepared by this invention solves the problems of high cost of precious metal catalyst preparation, dependence on external acid, high equipment operation requirements, and complex post-reaction recovery of existing catalysts in the existing process of hydrogenolysis of furfurylamine to prepare 5-amino-1-pentanol. It is suitable for industrial production and market application.

Description

Technical Field

[0001] This invention belongs to the field of biomass resource utilization technology, specifically relating to a NiCo catalyst and its use in the hydrogenolysis of furfurylamine to prepare 5-amino-1-pentanol. Background Technology

[0002] 5-Amino-1-pentanol (5-AP) is an important organic synthesis intermediate and a key building block for constructing active pharmaceutical ingredients, specialty polymers, surfactant precursors, and chelating ligands. It is widely used in medicinal chemistry (such as the synthesis of specific antibiotics) and polymer / materials science [Yan X, Feng W, Ng JX, et al. “Recent advances in catalytic enantioselective synthesis of vicinal amino alcohols.” ChemicalSociety Reviews, 2025, 54(17): 7966-8018.]. Currently, industrial preparation relies on the fossil-based caprolactam route [Geng K, Li H, Zhang D, et al. “Producing hexamethylenediamine from caprolactam via 6-aminocapronitrile: a green production technology of themonomer of nylon-66.” Green Chemistry, 2024, 26(15): 8777-8784.;Li Baoqiang, Jiang Xiaoqing, Chen Shouqing. “Preparation of 5-amino-1-pentanol.” Fine Chemical Intermediates, 2014, 44(06): 40-41+48.]. This route is energy-intensive, environmentally harmful, and poses serious sustainability challenges.Existing biomass-derived 5-AP synthesis relies on two multi-step routes: a continuous route and a dihydropyran route [Zhang S, Zheng J, Li Z, et al. “Agreen catalytic reaction system for the synthesis 5-amino-1-pentanol with furfural and ionic liquid hydroxylamine salt as the initial raw material.”Molecular Catalysis, 2023, 538: 112995.;Li X, Tian J, Liu H, et al.“Effective synthesis of 5-amino-1-pentanol by reductive amination of biomass-derived 2-hydroxytetrahydropyran over supported Ni catalysts.” Chinese Journal of Catalysis, 2020, 41(4): 631-641.]. The inherent multi-step reaction characteristics of these two routes typically lead to challenges such as cumulative yield loss, high energy consumption for intermediate purification, and the generation of large amounts of waste, posing a serious challenge to their economic and environmental feasibility. Recent research indicates that direct one-pot FAM hydrolysis is a transformative alternative for the production of 5-AP.Currently, the catalytic systems used for this conversion are mainly based on noble metals, and can be roughly divided into two categories: high-temperature systems and low-temperature systems using inorganic acids [Hong CB, Li G, Liu H. “Selective hydrogenolysis of bio-renewable tetrahydrofurfurylamine to piperidine on ReOx-modified Rhcatalysts.” Green Chemistry, 2023, 25(9): 3515-3523.;Li G, Wang T, Hong CB, et al. “Effective synthesis of 5-Amino-1-pentanol via selective hydrogenolysis of biomass-derived furfurylamine on supported platinum catalysts at ambient temperature.” ACS Catalysis, 2024, 14(24): 18268-18277.]. The core design challenge in these two systems lies in the kinetic and thermodynamic equilibrium problem. In addition, the dependence on scarce noble metals brings cost constraints and the problem of their susceptibility to poisoning by the -NH2 group in FAM. This contradiction highlights the urgent need to design advanced catalysts for the FAM-5-AP conversion. It also underscores the significant importance of developing abundant and stable non-precious metal catalysts to achieve controllable hydrogen activation and selective CO bond breaking under mild, acid-free conditions. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a low-cost, high-yield, and stable NiCo catalyst, and its use in the selective hydrogenolysis of furfurylamine to prepare 5-amino-1-pentanol.

[0004] The NiCo catalyst of this invention is prepared by dissolving nickel salt, cobalt salt, and aluminum salt in deionized water, adding a liquid containing sodium hydroxide and sodium carbonate under stirring to adjust the pH of the mixture to 9-11, placing the mixture in a sealed reactor, and hydrothermally reacting it at 70-90°C for 24 hours. The solid is centrifuged, washed until neutral, dried, ground, calcined at 400-500°C for 3-5 hours, reduced in a hydrogen atmosphere at 400-500°C for 3-5 hours, and then cooled to obtain the catalyst.

[0005] The mass ratio of nickel salt:cobalt salt:aluminum salt is (1-1.5):1:(0.5-3), and the mass ratio of sodium hydroxide:sodium carbonate is 1:4-6.

[0006] Another objective of this invention is to apply the above-mentioned NiCo catalyst in the selective hydrogenolysis of furfurylamine to prepare 5-amino-1-pentanol. Specifically, furfurylamine, NiCo catalyst, and anhydrous ethanol are added to a high-temperature and high-pressure closed reactor, 0.5-2.5 MPa H2 is introduced, and the reactor is reacted at 100-140°C with stirring for 1-5 hours to obtain 5-amino-1-pentanol.

[0007] Compared with the prior art, the present invention has the following advantages: 1. This invention uses furfurylamine derived from inexpensive and renewable biomass resources to replace fossil raw materials in the production of 5-amino-1-pentanol, which has abundant raw material sources and low cost; 2. In this invention, the precursor is prepared by co-precipitation, followed by calcination to prepare the catalyst, Ni 0 and CoO containing oxygen vacancies x Synergistic effect, enabling H2 molecules to be in Ni 0 The hydrogen then undergoes efficient adsorption and dissociation, subsequently escaping into Ov-CoO. x It activates and breaks the CO bond to generate 5-amino-1-pentanol; 3. This invention uses a co-precipitation method to prepare heterogeneous Ni-Co catalysts, which have the characteristics of high efficiency, low cost and environmental friendliness. It can realize the recycling of catalysts and convert furfurylamine into high-value-added chemical 5-amino-1-pentanol under relatively mild conditions, which has the potential for large-scale industrial production applications. Detailed Implementation

[0008] The method of the present invention will be further described in detail below through examples, but the scope of protection of the present invention is not limited to the content described. Unless otherwise specified, the reagents in the examples are all conventional reagents or reagents prepared by conventional methods. Example 1: Preparation and application of Ni-Co catalysts 1. Dissolve 2.4g Ni(NO3)2·6H2O, 1.8g Co(NO3)3·6H2O and 1.5g Al(NO3)3⋅9H2O in 160mL of deionized water. Under stirring at 25℃ and 600rpm, add 150mL of a mixture containing 0.6g NaOH and 3.2g Na2CO3 dropwise to the metal salt mixture over 30min to maintain the pH of the solution at approximately 10±0.1. Place the resulting suspension in a sealed reactor and keep it in an 80℃ oven for 24 hours. After centrifugation and washing with deionized water until pH 7, collect the precipitate and dry it overnight in an 80℃ oven. The resulting catalyst precursor is calcined at 450℃ in air for 4h at a heating rate of 5℃ / min. Then, the calcined product is reduced at 450℃ in a N2 atmosphere containing 10% H2 for 4h and cooled to obtain NiCo catalyst 1. 2. Catalyst 2 was prepared simultaneously using the same method as above, except that only Co(NO3)3·6H2O and Al(NO3)3⋅9H2O were added to obtain Co catalyst 2; Catalyst 3 was prepared simultaneously using the same method as above, except that only Ni(NO3)3·6H2O and Al(NO3)3⋅9H2O were added to obtain Ni catalyst 3. Catalyst 4: Prepared using urea hydrolysis (UPM) method. 0.9 g Co(NO3)3·6H2O, 1.2 g Ni(NO3)3·6H2O, 0.7 g Al(NO3)3⋅9H2O, and 0.7 g urea were dissolved in 50 mL of deionized water and placed in a sealed high-pressure hydrothermal reactor. Heating was carried out at 120 °C for 4 h. After heating, the precipitate was washed with deionized water by centrifugation until neutral, and then dried in an oven at 80 °C for 24 h. The resulting solid was ground into powder and then calcined at 450 °C in air for 4 h, followed by calcination at 450 °C for 4 h in a N2 atmosphere containing 10% H2 to obtain Ni-CoO. x -Al2O3-UPM.

[0009] 3. Catalyst 1-4 prepared by the above method is used to catalyze the preparation of 5-amino-1-pentanol. 50 mg of catalyst, 0.1 g of furfurylamine, and 10 mL of anhydrous ethanol were added to a high-pressure reactor. After replacing the air with hydrogen 5-6 times, the reactor was purged with 1 MPa of hydrogen. The autoclave was heated to 120 °C and stirred at 600 r / min for 4 h. After the reaction was completed, the reaction solution was filtered through an organic filter and analyzed by gas chromatography (Agilent 7860A). The results are shown in Table 1. Table 1

[0010] As shown in the table, under the same conditions, catalyst 1 exhibits the highest activity in the hydrogenolysis of furfurylamine, achieving a furfurylamine conversion rate of 100% and a 5-amino-1-pentanol yield of 98.7%, thanks to the synergistic effect of Ni and CoOx species. Comparing catalysts 1 and 2, and 3, the preparation method also significantly impacts catalyst performance. Comparing catalysts 1 and 4, it can be observed that the catalyst prepared by urea hydrolysis exhibits significantly lower performance than the Ni-Co catalyst prepared by co-precipitation.

[0011] 4. Effect of different amounts of aluminum salt added on catalytic activity of catalysts The catalyst preparation in this embodiment is the same as in step 1, except that the amount of Al(NO3)2·9H2O added is 0.375g, 0.75g, 2.25g, and 3.0g, respectively, to obtain catalysts 5-8. The catalytic synthesis of 5-amino-1-pentanol is the same as in step 2, and the results are shown in Table 2. Table 2

[0012] The amount of Al2O3 support added has a significant impact on the distribution of active sites on the catalyst, resulting in differences in catalyst activity. The table shows that adding too much or too little aluminum salt increases the energy required for the reaction (time or temperature).

[0013] 4. Experiment on the effect of sodium hydroxide or sodium carbonate on product selectivity The catalyst preparation in this embodiment is the same as in step 1, except that only NaOH is added to obtain catalyst 9, and only Na2CO3 is added to obtain catalyst 10; the catalytic synthesis of 5-amino-1-pentanol is the same as in step 2, and the results are shown in Table 3: Table 3

[0014] The morphology or structure of the catalyst is affected by the addition of sodium hydroxide or sodium carbonate, thus influencing its catalytic performance. The results in the table show that the addition of sodium hydroxide or sodium carbonate has a significant impact on product selectivity. Adding only sodium hydroxide results in a reaction selectivity that stops at the intermediate product tetrahydrofurfurylamine or produces byproducts. While the catalyst prepared with only sodium carbonate produces the target product, the reaction proceeds slowly and polymerization occurs. This indicates that both sodium hydroxide and sodium carbonate must be added simultaneously to obtain good catalytic performance.

[0015] 4. Experiment on the effect of reaction temperature on product selectivity The performance of catalyst 1 at different reaction temperatures was evaluated: 50 mg of catalyst, 0.1 g of furfurylamine, and 10 mL of ethanol were added to a high-pressure reactor. After replacing the air with hydrogen 5-6 times, 1 MPa of H2 was introduced, and the autoclave was heated to 120-160 °C. The reaction was stirred at 600 r / min for 2 h. After the reaction was completed, the reaction solution was filtered through an organic filter and analyzed by gas chromatography (Agilent 7860A). The results are shown in Table 4. Table 4

[0016] The results in the table show that the yield of 5-amino-1-pentanol gradually increases with increasing reaction temperature. When the temperature is raised to 110-120℃, the product yield reaches more than 80%. Further increases in temperature lead to an increase in byproducts.

[0017] 5. Experiment on the effect of reaction hydrogen pressure on product selectivity The performance of catalyst 1 under different hydrogen pressures was evaluated: 50 mg of catalyst, 0.1 g of furfurylamine, and 10 mL of ethanol were added to a high-pressure reactor. After replacing the air with hydrogen 5-6 times, hydrogen gas at 0.5-2.5 MPa was introduced, the autoclave was heated to 120℃, and the reaction was stirred at 600 r / min for 4 h. After the reaction was completed, the reaction solution was filtered through an organic filter and analyzed by gas chromatography (Agilent 7860A). The results are shown in Table 4. Table 5

[0018] The results in the table show that the yield of 5-amino-1-pentanol increases with increasing hydrogen pressure. At a pressure of 1 MPa H2, the yield of 5-amino-1-pentanol is 98.7%. Further increasing the hydrogen pressure will cause polymerization to form secondary amines as byproducts, indicating that both excessively low and excessively high hydrogen pressure are not conducive to the formation of the product.

[0019] 6. Experiment on the effect of reaction time on product selectivity Performance evaluation of catalyst 1 at different reaction times: 50 mg of catalyst, 0.1 g of furfurylamine, and 10 mL of ethanol were added to a high-pressure reactor. After replacing the air with hydrogen 5-6 times, 1 MPa H2 was introduced, the autoclave was heated to 120 °C, and the reaction was stirred at 600 r / min for 0.5-5 h. After the reaction was completed, the reaction solution was filtered through an organic filter and analyzed by gas chromatography (Agilent 7860A). The results are shown in Table 6. Table 6

[0020] The results in the table show that reaction time has a significant impact on the selectivity of furfurylamine. In a short time, furfurylamine is converted to tetrahydrofurfurylamine and then rapidly generates 5-amino-1-pentanol, indicating that tetrahydrofurfurylamine is an intermediate in this reaction. As the time gradually increases, the yield of 5-amino-1-pentanol gradually increases from 7.6% at 0.5 h to 97.8% at 4 h. Further extending the time results in a decrease in product yield and an increase in by-product yield, indicating that a polymerization reaction has occurred.

[0021] 7. Catalyst cycling experiment In practical applications, the cycle stability of a catalyst is also one of the criteria for evaluating its quality. The cycle stability of catalyst 1 was evaluated as follows: 50 mg of catalyst, 0.1 g of furfurylamine, and 10 mL of ethanol were added to a high-pressure reactor. After replacing the air with hydrogen 5-6 times, 1 MPa of H2 was introduced, the autoclave was heated to 120℃, and the reaction was stirred at 600 r / min for 4 h. After the reaction was completed, the reaction solution was centrifuged, the solid was washed three times with ethanol, and then dried overnight in a vacuum oven at 50℃. The obtained catalyst was then used for the next reaction. After filtering the reaction solution with an organic filter, the results were analyzed by gas chromatography (Agilent 7860A). The results are shown in Table 7. Table 7

[0022] The catalyst was recycled five times without a significant decrease in activity, demonstrating excellent stability.

[0023] The above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A NiCo catalyst, characterized in that: Nickel, cobalt, and aluminum salts were dissolved in deionized water, and a liquid containing sodium hydroxide and sodium carbonate was added with stirring to adjust the pH of the mixture to 9-11. The mixture was placed in a sealed reactor and hydrothermally reacted at 70-90℃ for 24 hours. The solid was centrifuged and washed until neutral, dried and ground, and then calcined at 400-500℃ for 3-5 hours. After reduction at 400-500℃ for 3-5 hours under a hydrogen atmosphere, the mixture was cooled to obtain the NiCo catalyst.

2. The NiCo catalyst according to claim 1, characterized in that: The mass ratio of nickel salt:cobalt salt:aluminum salt is (1-1.5):1:(0.5-3), and the mass ratio of sodium hydroxide:sodium carbonate is 1:4-6.

3. The application of the NiCo catalyst according to claim 1 or 2 in the selective hydrogenolysis of furfurylamine to prepare 5-amino-1-pentanol.

4. The application according to claim 3, characterized in that, 5-Amino-1-pentanol was prepared by adding furfurylamine, NiCo catalyst, and anhydrous ethanol into a high-temperature and high-pressure closed reactor, charging it with 0.5-2.5 MPa H2, and reacting it at 100-140℃ with stirring.

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