A process for the preparation of furfurylamine from furfural

Abstract

The present application relates to a kind of biomass platform molecule furfural selective reduction amination method for preparing furfurylamine.Furfural, Ni@C catalyst and methanol ammonia solution are added to high-temperature and high-pressure airtight reactor, 0.1-2MPa H2 is filled, and the reaction is carried out at the temperature of 40-70 DEG C for 0.5-2h, and the highest furfurylamine yield is 95.1%.The preparation method of Ni@C catalyst of the present application is simple, low in price, Ni is highly dispersed, and has high specific surface area, realizes furfurylamine under mild conditions.The existing furfurylamine preparation furfurylamine uses noble metal as catalyst, and the problems of high price and low efficiency of non-noble metal catalyst are overcome, and the catalyst has good universality, can catalyze the reduction amination of a variety of aldehydes to prepare primary amine.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biomass resource utilization, and particularly relates to a method for preparing furfuryl amine by low-temperature reduction amination of furfuryl alcohol. BACKGROUND

[0002] Primary amines are important chemicals, widely used in the synthesis of dyes, pesticides, drugs, detergents and polymers [Afanasyev, Oleg I., et al. "Reductive amination in the synthesis of pharmaceuticals." Chemical reviews 119.23 (2019): 11857-11911.; Froidevaux, Vincent, et al. "Biobased amines: from synthesis to polymers; present and future." Chemical Reviews 116.22 (2016): 14181-14224.], the organic amines existing in nature are insufficient in both variety and yield to meet the industrial production demand, and need to be artificially synthesized in large quantities. Furfurylamine, as one of the primary amines, has a wide range of uses [Chandra, Debraj, et al. A high performance catalyst of shape-specific ruthenium nanoparticles for production of primary amines by reductive amination of carbonyl compounds." Chemical Science 9.27 (2018): 5949-5956.; Liang, Guanfeng, et al. Production of primary amines by reductive amination of biomass-derived aldehydes / ketones. Angewandte Chemie International Edition 56.11 (2017): 3050-3054.], mainly prepared by reductive amination of biomass platform molecule furfural [Yang, Yinze, et al. Catalytic reductive amination of furfural to furfurylamine on robust ultra-small Ni nanoparticles." Nano Research 16.3 (2023): 3719-3729.; Dong, Chenglong, et al.Ru / HZSM-5 as an efficient and recyclable catalyst for reductive amination of furfural to furfurylamine. Molecular Catalysis 482 (2020): 110755.; Lin, Chuncheng, et al. "An efficient approach to biomass-based tertiary amines by direct and consecutive reductive amination of furfural." Journal of Catalysis 410 (2022): 164-179. Patent: Application of supported catalyst in catalytic reductive amination of furfural to prepare furfurylamine, CN 116272966A. Patent: Method for preparing furfurylamine by selective amination of furfuryl alcohol on a deactivation-resistant nickel-based catalyst, CN 114805259B] At present, noble metal catalysts have excellent reductive amination catalytic activity, but due to the low content of noble metals, the price is high and is greatly affected by market fluctuations, etc. Limit its large-scale application. In contrast, the development of non-noble metal catalysts for the reductive amination of furfural to prepare furfurylamine is extremely attractive, but there are also problems such as harsh reaction conditions and long reaction time. Therefore, the development of efficient and stable non-noble metal catalysts has become a challenge for current reductive amination of furfural research. In the inventor's previous invention (publication number: CN117123226A), a high-load, high-dispersion, small-particle-size Ni-based catalyst was developed, which realized the selective hydrogenation of HMF under mild conditions. The progress of any industry is not achieved overnight, and it needs to be gradually accumulated and iterated to promote the development of the industry. The technical innovation of this work is based on the technology of the inventors before, by introducing a new reduction method, a catalyst for the reductive amination of furfural is obtained, which improves the performance and efficiency of the reductive amination of furfural, and significantly improves the value of practical application. SUMMARY

[0003] To solve the problems existing in the prior art, the present application provides a method for selectively reductive amination of furfural to prepare furfurylamine under mild conditions.

[0004] The technical solution of the present application is as follows:

[0005] A preparation method of a Ni-based catalyst Ni@C, characterized in that it comprises the following steps:

[0006] Put glucose, nickel nitrate hexahydrate, isopropyl alcohol in a pressure-resistant stainless steel reaction kettle, close the reaction kettle, stir at 50-70 DEG C for 0.5-2h, then heat to 160-200 DEG C and keep for 4-8h;

[0007] Cool to room temperature, filter, wash with anhydrous ethanol, and vacuum dry to obtain a catalyst precursor;

[0008] Subsequently, in a hydrogen gas-tube furnace, heat to 400 DEG C, keep for 1-5h, and naturally cool to room temperature to obtain a Ni@C catalyst.

[0009] Preferably,

[0010] The amount ratio range of glucose, nickel nitrate hexahydrate and isopropyl alcohol is (4-7)g:(3-5)g:(100-300)mL;

[0011] In the closed reaction kettle, stir at 60 DEG C for 1h, then heat to 180 DEG C and keep for 6h;

[0012] Vacuum dry at 80 DEG C for 12h to obtain a catalyst precursor;

[0013] In a tube furnace, heat to 400 DEG C at 5 DEG C / min, keep for 2h, and naturally cool to room temperature to obtain a Ni@C catalyst.

[0014] The application further provides a Ni-based catalyst Ni@C prepared by the preparation method.

[0015] Further provided is application of the Ni-based catalyst Ni@C in preparation of furfurylamine by selective reductive amination of furfuryl alcohol.

[0016] The application further provides a method for preparing furfurylamine by selective reductive amination of furfuryl alcohol, which comprises the following steps: adding furfuryl alcohol, the Ni-based catalyst Ni@C and an ammonia methanol solution into a high-temperature and high-pressure closed reactor, filling 0.1-3MPa H2, and reacting at a temperature of 30-70 DEG C for 0.5-3h, while stirring at a speed of 600-1200rpm;

[0017] Specifically, the optimal hydrogen pressure is 1.5-2.5MP; the reaction temperature is 40-60 DEG C; the reaction time is 1.5-2.5h; and the amount ratio range of the Ni-based catalyst Ni@C and the ammonia methanol solution is Ni@C 10-20mg:7M NH3 methanol solution 5-15ml.

[0018] The application also provides a method for reducing and aminating an aldehyde substance, which comprises the following steps: adding the aldehyde substance, the Ni@C catalyst and the methanol ammonia solution into a high-temperature and high-pressure sealed reactor, filling 1.5-2.5 MPa H2, and reacting at a temperature of 60-80 DEG C for 2-3 h, while stirring at a speed of 600-1200 rpm.

[0019] Specifically, the structural formula of the aldehyde substance is any one of the following:

[0020] Compared with the prior art, the application has the following advantages and effects: the application provides a method for preparing furfurylamine by reducing and aminating furfuryl alcohol, which has the advantages of mild reaction conditions and high selectivity. The Ni@C catalyst provided by the application has the advantages of large specific surface area, simple preparation and low price, and overcomes the problems of high price of the noble metal catalyst and low efficiency of the non-noble metal catalyst in the traditional preparation of furfurylamine. The catalyst has good universality and can catalyze the reduction and amination of various aldehydes to prepare primary amines. Experiments show that the effect is better than that of the prior art and the comparative examples. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The X-ray diffraction patterns of the Ni-based catalysts (Ni@C, Ni / AC and Ni / CNT) prepared in Example 1 and Comparative Examples 1 and 2 are shown in the following table.

[0022] Figure 2 The N2 adsorption and desorption curves of the Ni-based catalysts (Ni@C, Ni / AC and Ni / CNT) prepared in Example 1 and Comparative Examples 1 and 2 are shown in the following table.

[0023] Figure 3 The GC-MS spectrum of the furfurylamine prepared in Example 2 is shown in the following table. DETAILED DESCRIPTION

[0024] The technical solutions of the application will be described in detail below in combination with specific examples and the drawings of the specification, but the following examples do not limit the scope of the application.

[0025] Unless otherwise specified, the reagents and instruments used in the following examples are commercially available products. The specific implementation examples are as follows:

[0026] Example 1, Ni@C catalyst:

[0027] The preparation method is as follows: 5.4 g of glucose, 3.9 g of nickel nitrate hexahydrate, and 200 ml of isopropanol were placed in a 250 ml pressure-resistant stainless steel reactor. The reactor was sealed, and the mixture was stirred at 60 °C for 1 h. The temperature was then increased to 180 °C and maintained for 6 h. After cooling to room temperature, the mixture was filtered, washed with anhydrous ethanol, and dried under vacuum at 80 °C for 12 h to obtain the catalyst precursor. Subsequently, the precursor was heated to 400 °C at a rate of 5 °C / min in a tube furnace purged with hydrogen and held at that temperature for 2 h. After naturally cooling to room temperature, the Ni@C catalyst was obtained.

[0028] Comparative Example 1, Ni / AC catalyst:

[0029] The preparation method is as follows: Activated carbon (AC) was refluxed at 60℃ with a mixture of nitric acid and sulfuric acid (volume ratio 1:3) for 1 h to obtain modified activated carbon. Then, it was kept in a vacuum oven at 100℃ for 12 h to remove adsorbed moisture. First, under magnetic stirring, 3.2 g of nickel nitrate was dissolved in an appropriate amount of ethanol, and 3.0 g of the modified activated carbon was immersed in the solution and stirred continuously for 6 h. The ethanol solvent was completely removed by rotary evaporation at 50℃. The mixture was dried under vacuum to obtain the catalyst precursor, which was then heated to 400℃ at 5℃ / min in a tube furnace purged with hydrogen, held at that temperature for 2 h, and naturally cooled to room temperature to obtain the Ni / AC catalyst.

[0030] Comparative Example 2, Ni / CNT catalyst:

[0031] The preparation method is as follows: Carbon nanotubes (CNTs) were refluxed at 60℃ with a mixture of nitric acid and sulfuric acid (volume ratio 1:3) for 1 h to obtain modified carbon nanotubes. Then, the modified carbon nanotubes were dried in a vacuum oven at 100℃ for 12 h to remove adsorbed moisture. First, 3.2 g of nickel nitrate was dissolved in an appropriate amount of ethanol under magnetic stirring. 3.0 g of the modified carbon nanotubes were then immersed in the solution and stirred continuously for 6 h. The ethanol solvent was completely removed by rotary evaporation at 50℃. The mixture was dried under vacuum to obtain the catalyst precursor, which was then heated to 400℃ at 5℃ / min in a tube furnace purged with hydrogen, held at that temperature for 2 h, and naturally cooled to room temperature to obtain the Ni / CNT catalyst.

[0032] The catalysts prepared in Examples 1-3 were characterized by X-ray diffraction. Figure 1 As shown, Ni@C, Ni / AC, and Ni / CNT all exhibit metallic Ni... 0 The relevant diffraction peaks. Figure 2 The N2 adsorption-desorption curves of the Ni-based catalysts (Ni@C, Ni / AC, Ni / CNT) prepared in Examples 1-3 are shown. The specific surface areas of Ni@C, Ni / AC, and Ni / CNT are 364.3 m², respectively. 2 / g,671.0m 2 / g,133.7m 2 / g.

[0033] Examples 2-4

[0034] The Ni-based catalysts (Ni@C, Ni / AC, Ni / CNT) prepared in Example 1 and Comparative Examples 1, 2 were used for the reduction amination of furfural to prepare furfurylamine, the steps of which were as follows:

[0035] The Ni-based catalysts (Ni@C, Ni / AC, Ni / CNT), furfural (1 mmol) and 7M NH3methanol solution 10 ml were added to a high-pressure reactor, the air was replaced with hydrogen for 5-6 times, then 2 MPa hydrogen was filled, the autoclave was heated to 60°C, and the reaction was stirred at a rate of 800 r / min for 2 h. After the reaction was completed, the reaction liquid was filtered with an organic filter head, and then detected by gas chromatography (Agilent 7890A). The specific data are shown in Table 1:

[0036] Table 1

[0037]

[0038] The activity of the Ni@C catalyst prepared in Example 1 and the catalysts of Comparative Examples 1 and 2 in the reduction amination of furfural was compared under the condition of a certain content of active metal Ni in the catalyst and a certain ratio of furfural. The Ni@C catalyst had the highest reaction activity, and under the same conditions, the conversion rate of furfural was greater than 99%, and the selectivity of furfurylamine could reach 95%. The reduction amination process of aldehyde is complex, and the reaction temperature and hydrogen pressure will affect the generation of primary amine. In order to further optimize the reaction conditions, the reaction temperature and hydrogen pressure were optimized, and the results are shown in Tables 2 and 3:

[0039] Table 2

[0040]

[0041] The Ni@C catalyst had very high reaction activity, and the data of Examples 5-8 showed that as the reaction temperature increased, the selectivity of furfurylamine gradually increased. At 40°C, the selectivity of furfurylamine was 73.8%, at 50°C, the selectivity of furfurylamine was 94.9%, and at 60°C and 70°C, the selectivity of furfurylamine was basically the same. 50°C was used for subsequent optimization.

[0042] Table 3

[0043]

[0044] In the actual reaction process, furfural and ammonia can spontaneously form imines, and imines and aldehydes can polymerize to form new Schiff bases, resulting in an increase in the types of byproducts. The key to obtaining primary amines with high selectivity is the efficient hydrogenation of imines. Data from Examples 9-12 show that the selectivity of furfural amine gradually increases with increasing hydrogen pressure. At a hydrogen pressure of 0.2 MPa, the selectivity of furfural amine is only 74.4%, while as the hydrogen pressure increases to 2 MPa, the selectivity of furfural amine increases to 94.9%. Subsequent optimization was carried out using 2 MPa hydrogen pressure.

[0045] As shown in Table 4 Examples 13-16, the reaction time has a great influence on the selectivity of furfural. Aldehyde and ammonia can spontaneously condense, resulting in nearly 100% conversion of furfural in a very short time. As the time gradually increases, the selectivity of furfural gradually increases from 54.4% at 0.5h to 94.9% at 2h.

[0046] Table 4

[0047]

[0048]

[0049] In practical applications, the cyclic stability of a catalyst is also one of the criteria for judging the quality of a catalyst. As shown in Table 5 Examples 17-21, the catalyst was used 5 times and the catalyst activity did not decrease significantly, indicating that the catalyst has excellent stability.

[0050] Table 5

[0051]

[0052] The Ni@C catalyst of Example 1 of this invention not only has good selectivity in the application of furfural reduction amination to prepare furfurylamine, but also can catalyze the preparation of the corresponding primary amines from 5-methylfurfural, p-chlorobenzaldehyde, benzaldehyde, and 5-hydroxymethylfurfural. The results are shown in Table 6.

[0053] Table 6

[0054]

[0055] To further compare the differences between the present invention and the prior art, the prior art has been summarized, and the results are shown in the table below:

[0056]

[0057]

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[0078]

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[0079] The above-mentioned only the preferred embodiments of the present application, therefore, cannot be limited to the scope of the present application. According to the scope and content of the present application, the equivalent changes and modifications should be considered as part of the present application.

Claims

1. A method for preparing a Ni-based catalyst Ni@C, characterized in that, The steps are as follows: Glucose, nickel nitrate hexahydrate, and isopropanol are placed in a pressure-resistant stainless steel reactor. The reactor is sealed and stirred at 50-70℃ for 0.5-2 hours. The temperature is then raised to 160-200℃ and maintained for 4-8 hours. The ratio of glucose, nickel nitrate hexahydrate, and isopropanol is (4-7)g:(3-5)g:(100-300)mL. The catalyst precursor was obtained by cooling to room temperature, filtering, washing with anhydrous ethanol, and vacuum drying. The catalyst was then heated to 400°C at a rate of 5°C / min in a tube furnace purged with hydrogen, held at that temperature for 1-5 hours, and then naturally cooled to room temperature to obtain the Ni@C catalyst.

2. The preparation method according to claim 1, characterized in that, In a sealed reactor, the mixture was stirred at 60°C for 1 hour, then heated to 180°C and held for 6 hours. Vacuum drying involves drying at 80°C in a vacuum for 12 hours to obtain the catalyst precursor. The holding time in the tubular furnace is 2 hours.

3. The Ni-based catalyst Ni@C obtained by the preparation method as described in claim 1 or 2.

4. The application of the Ni-based catalyst Ni@C as described in claim 3 in the selective reductive amination of furfural to prepare furfurylamine.

5. A method for preparing furfural-based selective reducing amination, characterized in that: Furfural, the Ni-based catalyst Ni@C as described in claim 3, and methanol-ammonia solution are added to a high-temperature, high-pressure closed reactor, and 0.1-3 MPa H2 is introduced. The reactor is reacted at 30-70°C for 0.5-3 hours, while stirring at 600-1200 rpm.

6. The method as described in claim 5, characterized in that, The hydrogen pressure is 1.5-2.5 MPa; the reaction temperature is 40-60℃; and the reaction time is 1.5-2.5 h.

7. The method as described in claim 5, characterized in that, The ratio range of Ni-based catalyst Ni@C and methanol ammonia solution as described in claim 3 is: Ni@C 10-20 mg : 7M NH3 methanol solution 5-15 ml.

8. A method for the reductive amination of aldehydes, characterized in that, Aldehydes, the Ni@C catalyst as described in claim 3, and methanol-ammonia solution are added to a high-temperature, high-pressure closed reactor, which is then charged with 1.5-2.5 MPa H2 and reacted at 60-80°C for 2-3 hours, while stirring at 600-1200 rpm.

9. The method as described in claim 8, characterized in that, Aldehydes have any of the following structural formulas:

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