Method for selectively preparing furan amine or tetrahydrofuran amine from furan aldehyde substance

Abstract

The invention discloses a method for selectively preparing furan amine or tetrahydrofuran amine from a furan aldehyde substance, which comprises the following steps: by taking the furan aldehyde substance as a raw material, carrying out reductive amination reaction on the furan aldehyde substance in an aqueous solution in which the volume percent concentration of ammonia water is greater than 70% in the presence of H2 under the action of a catalyst to obtain the furan amine, the method comprises the following steps: in an aqueous solution in which the volume percent concentration of ammonia water is less than 20%, carrying out reductive amination reaction on furan aldehyde substances in the presence of H2 under the action of a catalyst to obtain tetrahydrofuran amine; the selectivity of the product is realized by changing the adding amount of the ammonia water in the aqueous solution, and the method is simple, easy to regulate and control and suitable for industrial production and market popularization 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 for the production of drugs, pesticides, synthetic resins and useful agricultural chemicals [Shen X, Dai J, Liu Y, et al. "Synthesis of high performance polybenzoxazinenetworks from bio-based furfurylamine: Furan vs benzene ring." Polymer, 122 (2017): 258-69.; SF Martin, JM Humphrey, A. Ali, MCHillier. "Enantioselective total syntheses of ircinal a and related manzamine alkaloid." Journal of the American Chemical Society, 121 (1999): 866–867.]. At present, there are two main routes for the preparation of furfurylamine and tetrahydrofurfurylamine. One is the reductive amination of furfuryl alcohol under the action of active metals such as Ru, Pd, Ni, and Cu through the "borrowing hydrogen" mechanism, but the steps are complicated and the reaction conditions are harsh [Wei Y, Wang H, Qin Y, et al. "Selective amination of furfurylalcohol to furfurylamine over nickel catalysts promoted by aluminaencapsulation." 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 under the action of metals such as Ru, Pd, Co, and Ni. However, this route mostly achieves 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 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 water system. Research in water system is also focused on supported precious 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-precious metal-based catalysts that require harsh reaction conditions to achieve high yields of furfurylamine and tetrahydrofurfurylamine in water system, there is still a need to solve. At the same time, the selective regulation strategy for the products furfural and tetrahydrofurfurylamine is still stagnant in the introduction of a second metal or the change of the carrier 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 very unfavorable for industrial large-scale production. It is still a huge challenge to switchably convert furfural into multi-target products in a single catalytic reaction system. . Summary of the invention

[0003] The invention provides a method for selectively preparing furanamine or tetrahydrofuran amine from furan aldehyde substances. The method uses furan aldehyde substances as raw materials, and in an aqueous solution with an ammonia concentration of more than 70% by volume, the furan aldehyde substances are subjected to a reductive amination reaction in the presence of H2 and the action of a catalyst to obtain furanamine, and in an aqueous solution with an ammonia concentration of less than 20% by volume, the furan aldehyde substances are subjected to a reductive amination reaction in the presence of H2 and the action of a catalyst to obtain tetrahydrofuran amine.

[0004] The catalyst is Ni / NiO x The catalyst is prepared by placing nickel nitrate hexahydrate in a high-temperature resistant porcelain ark in a tubular furnace passing hydrogen at a temperature of 5°C / min to 400°C, keeping the temperature for 2 hours, and then cooling naturally; the mass ratio of furan aldehyde substance to catalyst is 5:2;

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

[0006] The furan aldehyde substance is

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

[0008] 1. The present invention uses furan aldehydes as raw materials, and under the action of Ni / NiOx catalyst, changes the selectivity of the product by changing the amount of ammonia water added in the aqueous solution. After reducing the amount of ammonia water, the target product is tetrahydrofuran amine. The process conditions of the two reactions are basically the same, but the selective control of the generation of different products can be achieved;

[0009] 2. The present invention uses furan aldehydes as raw materials, which are simple, easy to obtain and low in cost;

[0010] 3. The present invention adopts a heterogeneous catalyst Ni / NiOx, which can realize the recycling of the catalyst and has good universality. It can catalyze the reductive amination of various furan aldehyde substances to prepare furan amine or tetrahydrofuran amine. The method of the present invention is simple and easy to control, and is suitable for industrial production and market promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The X-ray diffraction patterns of the catalysts of Example 1 and Comparative Examples 1, 2, and 3;

[0012] Figure 2 The X-ray photoelectron spectra of the catalysts of Example 1 and Comparative Examples 1, 2, and 3 are shown;

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

[0014] The method of the present invention is further described in detail below through the accompanying drawings and examples, but the protection scope of the present invention is not limited to the above contents. Unless otherwise specified, the reagents in the examples are conventional reagents or reagents prepared according to conventional methods.

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

[0016] 1. Take nickel nitrate hexahydrate and place it in a high-temperature resistant porcelain ark, put it into a tubular furnace with hydrogen flowing at 5°C / min to 400°C, keep it warm for 2 hours, and cool it naturally to room temperature to obtain a Ni / NiOx catalyst.

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

[0018] Cobalt nitrate hexahydrate was placed in a high-temperature resistant porcelain ark, placed in a tubular furnace passing hydrogen and heated to 400°C at 5°C / min, kept warm for 2 hours, and naturally cooled to room temperature to obtain a Co / CoOx catalyst.

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

[0020] Copper nitrate trihydrate was placed in a high temperature resistant porcelain ark, placed in a tubular furnace with hydrogen flowing at 5°C / min to 400°C, kept at this temperature for 2 hours, and naturally cooled to room temperature to obtain a Cu / CuOx catalyst;

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

[0022] Zinc nitrate hexahydrate was placed in a high-temperature resistant porcelain ark, placed in a tubular furnace passing hydrogen at 5°C / min to 400°C, kept at that temperature for 2 hours, and naturally cooled to room temperature to obtain a Zn / ZnOx catalyst;

[0023] The catalyst was characterized by X-ray diffraction. Figure 1 As shown in the figure, it can be seen that Ni / NiOx, Co / CoOx, Cu / CuOx, and Zn / ZnOx all show metal Ni 0 、Co 0 , Cu 0 and Co 2+ , Cu 2+ 、Zn 2+ The relevant diffraction peaks of Figure 2 The X-ray photoelectron spectrum of the above catalysts shows that the catalysts Ni / NiOx, Co / CoOx, Cu / CuOx, and Zn / ZnOx all show the properties of metal Ni.0 、Co 0 , Cu 0 and Co 2+ , Cu 2+ 、Zn 2+ Spectral peaks; Figure 3 The N2 adsorption and desorption curves of the above catalysts show that the specific surface areas of the catalysts Ni / NiOx, Co / CoOx, Cu / CuOx, and Zn / ZnOx are 42.2 m 2 / g, 48.7m 2 / g, 30.4m 2 / g, 60.4m 2 / g.

[0024] Example 2: Preparation of furfural amine by catalytic reductive amination of furfural using the catalyst prepared in Example 1

[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 were added to a high-pressure reactor. After replacing the air with hydrogen for 5-6 times, 2 MPa of hydrogen was charged. The autoclave was heated to 120° C. and stirred at a rate of 600 r / min for 1 h. After the reaction was completed, the reaction liquid was filtered with an organic filter head and 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] It can be seen from the table that under the same conditions, Ni / NiOx catalyst has the highest activity in catalyzing the reductive amination of furfural, with a furfural conversion rate of 100% and a selectivity of tetrahydrofurfurylamine of 93.8%. The amount of ammonia added has a great influence on the reductive amination process of aldehydes, so the amount of ammonia added in the aqueous solution was explored.

[0029] 2. Experiment on the effect of the amount of ammonia added to the aqueous solution on the product

[0030] The reaction system and reaction conditions of this embodiment are the same as above, the catalyst is Ni / NiOx, the difference is that the amount of ammonia added is changed, the total volume of H2O and ammonia is 10mL, 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, as the amount of ammonia in water increases, the yield of furfural reduction amination product tetrahydrofurfurylamine gradually decreases, while the yield of furfurylamine gradually increases; when the volume percentage concentration of ammonia in the aqueous solution system is greater than 80%, the product is furfurylamine.

[0034] 3. Experiment on the effect of organic solvent on the distribution of furfural reduction amination products. The results are shown in Table 3.

[0035] Table 3

[0036]

[0037] It can be seen from the table that when the solvent water is replaced by an organic solvent, no matter whether the amount of ammonia added is high or low, the product is mainly furfuralamine, and no tetrahydrofurfurylamine is generated.

[0038] 4. Experiments on the effects of reaction temperature and hydrogen pressure on product selectivity. The results are shown in Tables 4 and 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. At 110-120°C, the product is tetrahydrofurfurylamine;

[0043] Table 5

[0044]

[0045] The results in the table show that with the increase of hydrogen pressure, the selectivity of tetrahydrofurfurylamine gradually increases. Under 1MPa H2 pressure, the selectivity of furfurylamine is only 57.0%. As the H2 pressure increases to 2MPa, the selectivity of furfurylamine increases to 93.8%.

[0046] 5. Experiment on the effect of reaction time on product selectivity. The results are shown in Table 6.

[0047] Table 6

[0048]

[0049] The results in the table show that the reaction time has a great influence on the selectivity of furfuralamine. Aldehyde and ammonia can spontaneously condense, so that furfural is nearly 100% converted in a very short time. As time gradually increases, the selectivity of tetrahydrofurfurylamine gradually increases, from 79.1% at 0.5h to 93.8% at 1h.

[0050] 6. Catalyst circulation experiment

[0051] In practical applications, the cyclic stability of the catalyst is also one of the criteria for judging the quality of the catalyst. As shown in Table 7, the catalyst activity did not decrease significantly after being recycled for 5 times, and the catalyst had 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 water (28%), 8 mL of H2O, and other conditions are 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 furan amines or tetrahydrofuran amines from furan aldehydes, characterized in that: With furan aldehydes as raw materials, in an aqueous solution with an ammonia concentration of more than 70% 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 furan amines; 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.

2. The method for selectively preparing furan amine or tetrahydrofuran amine from furan aldehydes according to claim 1, characterized in that: Catalyst is Ni / NiO x catalyst.

3. The method for selectively preparing furan amine or tetrahydrofuran amine from furan aldehydes according to claim 1, characterized in that: The reaction temperature is 100-120°C, the reaction time is 1-2h, and the hydrogen pressure is 1.5-2.5MPa.

4. The method for selectively preparing furan amine or tetrahydrofuran amine from furan aldehydes according to claim 1, characterized in that: Furan aldehydes are

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