A method for selectively preparing a furanamine or tetrahydrofuranamine from a furfural substance

Abstract

The application discloses a method for selectively preparing furan amine or tetrahydrofuran amine from furan aldehyde substances, which comprises the following steps: in an aqueous solution with the volume percentage concentration of ammonia water being greater than 70%, furan aldehyde substances are subjected to a reductive amination reaction in the presence of H2 and under the action of a catalyst to prepare furan amine; and in an aqueous solution with the volume percentage concentration of ammonia water being less than 20%, furan aldehyde substances are subjected to a reductive amination reaction in the presence of H2 and under the action of a catalyst to prepare tetrahydrofuran amine. The method can realize the selectivity of products by changing the addition amount of ammonia water in the aqueous solution, and is simple, easy to control, and suitable for industrial production and market promotion and application.

Description

Technical Field

[0001] The invention belongs to the technical field of biomass resource utilization, and particularly relates to a method for selectively preparing furfural from furfural and tetrahydrofurfurylamine. Background Art

[0002] Furfurylamine and tetrahydrofurfurylamine are important intermediates in the production of pharmaceuticals, pesticides, synthetic resins, and useful agricultural chemicals [Shen X, Dai J, Liu Y, et al. “Synthesis of high performance polybenzoxazine networks from bio-based furfurylamine: Furan vs benzene ring.” Polymer, 122(2017): 258-69.; S.F. Martin, J.M. Humphrey, A.Ali, M.C. Hillier. “Enantioselective total syntheses of ircinal a and related manzamine alkaloid.” Journal of the American Chemical Society, 121(1999): 866–867.]. Currently, there are two main pathways for the preparation of furfurylamine and tetrahydrofurfurylamine. One is the reductive amination of furfuryl alcohol in the presence of active metals such as Ru, Pd, Ni, and Cu via a "borrowing hydrogen" mechanism, but this involves complex steps and harsh reaction conditions [Wei Y, Wang H, Qin Y, et al. "Selective amination of furfurylalcohol to furfurylamine over nickel catalysts promoted by alumina encapsulation." Chemical Engineering Journal, 491(2024).; Patent: A method for selectively preparing furfurylamine or tetrahydrofurfurylamine, CN 107245066 A.]; the other is the reductive amination of furfural in the presence of metals such as Ru, Pd, Co, and Ni. However, this approach often requires high yields of furfurylamine in organic solvents [Gao Z, Cai L, Ma H, et al. "DualScale Hydrogen Transfer Bridge Construction for Biomass Tandem Reductive Amination." ACS Nano Catalysis, 13.19(2023):12835-47.; Xie C, Song J, Hua M, et al. "Ambient-Temperature Synthesis of Primary Amines via Reductive Amination ofCarbonyl Compounds." ACS Catalysis, 10.14(2020):7763-72.], since the hydrogenation of imine to furfurylamine is a reversible dehydration reaction, it increases the difficulty of synthesizing furfurylamine and tetrahydrofurfurylamine in aqueous systems. Research in aqueous systems is also focused on supported noble metal Ru and Rh-based catalysts [Chatterjee M, Ishizaka T, Kawanami H. “Reductive amination of furfural to furfurylamine using aqueous ammonia solution and molecular hydrogen: an environmentally friendly approach”. Green Chemistry, 18.2(2016):487-96.; Nishimura S, Mizuhori K, Ebitani K. “Reductive amination offurfural toward furfurylamine with aqueous ammonia under hydrogen over Ru-supported catalyst.” Research on Chemical Intermediates, 42.1, (2015):19-30.], for non-noble metal-based catalysts that require harsh reaction conditions to achieve high yields of furfurylamine and tetrahydrofurfurylamine in aqueous systems, there is still a need to solve the problem. Meanwhile, strategies for selectively regulating the products furfural and tetrahydrofurfurylamine remain limited to introducing a second metal or changing the support type [Qi H, Li Y, Zhou Z, et al. “Synthesis of piperidines and pyridine from furfural over a surface single-atom alloy Ru1CoNP catalyst”. Nature Communications, 14.1 (2023); Ishikawa H, Yamaguchi S, Mizugaki T, et al. “Highly Active and Sulfur-Tolerant Ruthenium Phosphide Catalyst for Efficient Reductive Amination of Carbonyl Compounds.” ACS Catalysis, 14.7 (2024): 4501-9.], which is highly unfavorable for large-scale industrial production. Switchably converting furfural to multiple target products in a single catalytic reaction system remains a significant challenge. SUMMARY

[0003] The application provides a method for selectively preparing furan amine or tetrahydrofuran amine from furan aldehyde, which comprises the following steps: in the presence of H2 and a catalyst, furan aldehyde is reduced and aminated in an aqueous solution with an ammonia concentration of more than 70% to prepare furan amine; and in the presence of H2 and a catalyst, furan aldehyde is reduced and aminated in an aqueous solution with an ammonia concentration of less than 20% to prepare tetrahydrofuran amine.

[0004] The catalyst is Ni / NiO x The catalyst is prepared by placing nickel nitrate hexahydrate in a high-temperature porcelain square canister, putting the canister into a hydrogen-treatment tube furnace, heating at a rate of 5 ℃ / min to 400 ℃, keeping the temperature for 2 h, and naturally cooling; the mass ratio of the furan aldehyde to the catalyst is 5:2;

[0005] The molar ratio of the furan aldehyde to ammonia is 1:14-57, the reaction is stirred at 100-120 ℃ for 1-2 h, and the hydrogen pressure is 1.5-2.5 MPa.

[0006] The furan aldehyde is

[0007] Compared with the prior art, the application has the following advantages:

[0008] 1. The application uses furan aldehyde as a raw material, and changes the selectivity of the product by changing the amount of ammonia added in the aqueous solution under the action of the Ni / NiOx catalyst; after reducing the amount of ammonia, the target product is tetrahydrofuran amine; the process conditions of the two reactions are basically the same, but the selectivity can be controlled to generate different products.

[0009] 2. The application uses furan aldehyde as a raw material, which is simple and low in cost.

[0010] 3. The application uses a heterogeneous catalyst Ni / NiOx, which can realize the recycling of the catalyst, has good universality, can catalyze the reduction and amination of various furan aldehydes to prepare furan amine or tetrahydrofuran amine, and has the advantages of simple method, easy control, and suitability for industrial production and market promotion and application. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 The X-ray diffraction patterns of the catalysts in Example 1 and Comparative Examples 1, 2 and 3 are shown in the following table:

[0012] Figure 2 The X-ray photoelectron spectrograms of the catalysts in Example 1 and Comparative Examples 1, 2 and 3 are shown in the following table:

[0013] Figure 3N2 adsorption-desorption curves of the catalysts of Example 1 and Comparative Examples 1, 2, 3. DETAILED DESCRIPTION

[0014] The method of the present application is further illustrated in detail below by means of the accompanying drawings and examples, but the scope of protection of the present application is not limited to the content described, and the reagents in the examples are all conventional reagents or reagents prepared according to conventional methods unless otherwise specified;

[0015] Example 1: Preparation of Ni / NiOx catalyst and other metal catalysts

[0016] 1. Take the nickel nitrate hexahydrate and place it in a high-temperature porcelain square canister, and place it in a hydrogen gas-treatment tube furnace at a rate of 5°C / min to 400°C, and keep it at this temperature for 2 hours, and then naturally cool it to room temperature to obtain the Ni / NiOx catalyst.

[0017] 2. Preparation of Co / CoOx catalyst (Comparative Example 1)

[0018] Take the cobalt nitrate hexahydrate and place it in a high-temperature porcelain square canister, and place it in a hydrogen gas-treatment tube furnace at a rate of 5°C / min to 400°C, and keep it at this temperature for 2 hours, and then naturally cool it to room temperature to obtain the Co / CoOx catalyst.

[0019] 3. Preparation of Cu / CuOx catalyst (Comparative Example 2)

[0020] Take the copper nitrate trihydrate and place it in a high-temperature porcelain square canister, and place it in a hydrogen gas-treatment tube furnace at a rate of 5°C / min to 400°C, and keep it at this temperature for 2 hours, and then naturally cool it to room temperature to obtain the Cu / CuOx catalyst.

[0021] 4. Preparation of Zn / ZnOx catalyst (Comparative Example 3)

[0022] Take the zinc nitrate hexahydrate and place it in a high-temperature porcelain square canister, and place it in a hydrogen gas-treatment tube furnace at a rate of 5°C / min to 400°C, and keep it at this temperature for 2 hours, and then naturally cool it to room temperature to obtain the Zn / ZnOx catalyst.

[0023] The above catalysts were characterized by X-ray diffraction, and the results are shown in Figure 1 From the figure, it can be seen that the Ni / NiOx, Co / CoOx, Cu / CuOx, and Zn / ZnOx catalysts all exhibit relevant diffraction peaks of metallic Ni 0 , Co 0 , Cu 0 , and Co 2+ , Cu 2+ , and Zn 2+ . Figure 2 The X-ray photoelectron spectrograms of the above catalysts are shown in the figure, and it can be seen from the figure that the catalysts Ni / NiOx, Co / CoOx, Cu / CuOx, and Zn / ZnOx all exhibit relevant diffraction peaks of metallic Ni0 Co 0 Cu 0 and Co 2+ Cu 2+ Zn 2+ the spectrum peaks of Zn; Figure 3 The N2 adsorption-desorption curve of the above catalyst is shown in the figure, from which it can be seen that the specific surface areas of the catalysts Ni / NiOx, Co / CoOx, Cu / CuOx and Zn / ZnOx are respectively: 42.2 m 2 / g, 48.7 m 2 / g, 30.4 m 2 / g and 60.4 m 2 / g.

[0024] Example 2: The catalyst prepared in Example 1 is used to catalyze the reductive amination of furfural to prepare furfuryl amine

[0025] 1. 40 mg of the catalyst prepared in Example 1, 0.1 g of furfural, 2 mL of ammonia water (28%) and 8 mL of H2O are added to a high-pressure reactor, the air is replaced with hydrogen for 5-6 times, 2 MPa of hydrogen is filled, the autoclave is heated to 120°C, and the reaction is stirred at a rate of 600 r / min for 1 h. After the reaction is completed, the reaction solution is filtered with an organic filter head, and then detected by gas chromatography (Agilent 7860A). The results are shown in Table 1:

[0026] Table 1

[0027] catalyst Furfural conversion rate (%) Furfurylamine selectivity (%) Tetrahydrofurfurylamine selectivity (%) Ni / NiOx 100.0 -- 93.8 Co / CoOx 100.0 11.7 40.8 Cu / CuOx 100.0 14.1 25.3 Zn / ZnOx 100.0 12.2 25.5

[0028] As can be seen from the table, under the same conditions, the activity of the Ni / NiOx catalyst in the reductive amination of furfural is the highest, the conversion rate of furfural is 100%, and the selectivity of tetrahydrofurfuryl amine can reach 93.8%. The addition amount of ammonia water has a great influence on the reductive amination process of aldehyde, so the addition amount of ammonia in the aqueous solution is explored.

[0029] 2. Effect of the addition amount of ammonia in the aqueous solution on the product

[0030] The reaction system and reaction conditions of this example are the same as above, the catalyst is Ni / NiOx, and the difference is that the addition amount of ammonia water is changed, the total volume of H2O and ammonia water is 10 mL, and the results are shown in Table 2.

[0031] Table 2

[0032] Volume of ammonia water (mL) Furfural conversion rate (%) Furfurylamine selectivity (%) Tetrahydrofurfurylamine selectivity (%) 2 100.0 -- 93.8 4 100.0 51.4 33.6 6 100.0 68.2 18.5 8 100.0 81.7 -- 9 100.0 90.5 --

[0033] Under the same conditions, with the increase of the amount of ammonia water in water, the yield of tetrahydrofurfuryl amine, the product of the reductive amination of furfural, gradually decreases, and the yield of furfuryl amine gradually increases; in the aqueous solution system with a volume percentage concentration of ammonia water greater than 80%, the product is furfuryl amine.

[0034] 3. The effect of organic solvent on the distribution of the product of the reductive amination of furfural, as shown in Table 3.

[0035] Table 3

[0036]

[0037] As can be seen from the table, when the solvent water is replaced by an organic solvent, the product is mainly furfurylamine, regardless of the amount of ammonia added, and no tetrahydrofurfurylamine is generated.

[0038] 4. The effect of reaction temperature and hydrogen pressure on the selectivity of the product, as shown in Table 4 and Table 5.

[0039] Table 4

[0040]

[0041]

[0042] The results in the table show that as the reaction temperature increases, the selectivity of tetrahydrofurfurylamine gradually increases, and at 110-120°C, the product is tetrahydrofurfurylamine.

[0043] Table 5

[0044]

[0045] The results in the table show that as the hydrogen pressure increases, the selectivity of tetrahydrofurfurylamine gradually increases, and at 1 MPa H2pressure, the selectivity of furfurylamine is only 57.0%, and as the H2pressure increases to 2 MPa, the selectivity of furfurylamine increases to 93.8%.

[0046] 5. The effect of reaction time on the selectivity of the product, as shown in Table 6.

[0047] Table 6

[0048]

[0049] The results in the table show that the reaction time has a great effect on the selectivity of furfurylamine. The aldehyde and ammonia can spontaneously condense, making the conversion of furfural almost 100% in a very short time. As the time gradually increases, the selectivity of tetrahydrofurfurylamine gradually increases, from 79.1% at 0.5h to 93.8% at 1h.

[0050] 6. Catalyst recycling experiment

[0051] In practical applications, the recycling stability of the catalyst is also one of the criteria for judging the quality of the catalyst. As shown in Table 7, the catalyst is used for 5 times, and the activity of the catalyst does not decrease significantly, and the catalyst has excellent stability.

[0052] Table 7

[0053]

[0054]

[0055] Example 3: Reaction using 5-hydroxymethylfurfural and 5-methylfurfural as raw materials

[0056] Using Ni / NiOx as catalyst (40 mg), 5-hydroxymethylfurfural, 5-methylfurfural, p-chlorobenzaldehyde or benzaldehyde as raw materials (0.1 g), ammonia (28%) 7 mL, H2O 3 mL, H2 2 MPa, the rest of the operation is the same as above, the results are shown in Table 8;

[0057] Table 8

[0058]

[0059] Table 9 (In the reaction system, 2 mL of ammonia (28%) and 8 mL of H2O were used, and the other conditions were the same as above)

[0060]

[0061] It can be seen from the table that when 5-hydroxymethylfurfural or 5-methylfurfural is used as raw material, the selectivity of the product can be changed by changing the amount of ammonia added in the aqueous solution, while when p-chlorobenzaldehyde or benzaldehyde is used as raw material, the selectivity of the product cannot be changed by changing the amount of ammonia.

Claims

1. A method for selectively preparing furanamine or tetrahydrofuran amine from furan aldehydes, characterized in that: Using furan aldehydes as raw materials, in an aqueous solution with an ammonia concentration of greater than 80% by volume, the furan aldehydes are subjected to a reductive amination reaction in the presence of H2 and the action of a catalyst to obtain furanamines; in an aqueous solution with an ammonia concentration of less than 20% by volume, the furan aldehydes are subjected to a reductive amination reaction in the presence of H2 and the action of a catalyst to obtain tetrahydrofuran amines; The furan aldehyde substance is 、 、 ; The catalyst is Ni / NiO x The catalyst is prepared by placing nickel nitrate hexahydrate in a high-temperature resistant porcelain ark in a tube furnace filled with hydrogen and heating the mixture at 5°C / min to 400°C, holding the mixture for 2 hours, and then naturally cooling the mixture. The mass ratio of the furan aldehyde to the catalyst is 5:

2. The reaction temperature of the above reaction is 100-120°C, the reaction time is 1-2h, and the hydrogen pressure is 1.5-2.5MPa; The furanamine is furfurylamine, 、 ; The tetrahydrofuran amine is tetrahydrofurfurylamine, 、 .

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