Nickel-based catalyst for catalyzing 5-hydroxymethylfurfural to prepare 5-hydroxymethyl-2-furfurylamine as well as preparation method and application of nickel-based catalyst

Abstract

The invention discloses a preparation method of a nickel-based catalyst, which comprises the following steps: mixing an aqueous solution containing aluminum salt and nickel salt with a precipitator to obtain a Ni-Al oxide precursor; the Ni-Al oxide precursor is dried and roasted, and Ni-Al oxide is obtained; and finally, reducing to obtain the nickel-based catalyst. The invention also discloses the catalyst prepared by the method and a method for preparing 5-hydroxymethyl-2-furfuryl amine by catalyzing 5-hydroxymethylfurfural by using the catalyst. The preparation process is simple in procedure and mild in condition, and the preparation cost and time are greatly reduced. In the prepared catalyst, the Ni metal, the Ni-Al spinel and the Al2O3 phase exist stably, and the formed metal Ni has very strong capability of catalytically reducing aminated HMF in the mixed phase of the Ni-Al spinel and the Al2O3, and is not beneficial to the excessive hydrogenation reaction of an HMFA product.

Description

Technical Field

[0001] The invention relates to the technical field of biomass resource utilization, and in particular to a method for preparing 5-hydroxymethyl-2-furfurylamine by catalyzing 5-hydroxymethylfurfural with a high-efficiency nickel-based catalyst. Background Art

[0002] The global energy crisis and the intensification of environmental pollution have prompted human society to pay unprecedented attention to sustainable development and green chemistry. In this context, biomass resources have become an important direction for future resource utilization due to their renewability, wide sources and their potential role in achieving carbon neutrality. As an important biomass-based platform compound, 5-hydroxymethylfurfural (5-HMF, Formula I) provides huge reaction potential for the synthesis of a variety of high value-added chemicals due to its active functional groups in its molecular structure. In recent years, the application scope of 5-HMF has expanded from basic chemicals to fine chemicals, drug development and high-performance materials, becoming one of the important topics in the research of renewable chemicals.

[0003]

[0004] Among the many 5-HMF derivatives, 5-hydroxymethyl-2-furfurylamine (HMFA, Formula II) has shown broad application prospects in the fields of medicine, polymer curing agents and biofuel additives due to its unique molecular structure and properties. As a functional intermediate, HMFA is of great value in the preparation of diuretics, antihypertensive drugs and epoxy resins. Its preparation process is usually achieved through the reductive amination of 5-HMF. This conversion pathway represents a typical application of green chemistry in increasing the added value of bio-based chemicals. However, the existing technology still faces many challenges in the design of catalytic systems and process optimization, including insufficient selectivity, more side reactions and poor catalyst recyclability.

[0005] At present, precious metal catalysts have excellent catalytic activity for reductive amination. Ding Mingyue's team (Dong Chenglong et al, Molecular Catalysis, 2020, 482, 110755) used Ru / HZSM-5 catalyst, methanol as solvent, and prepared furfurylamine at a reaction temperature of 100°C, with a yield of 76%. Due to the low content of precious metals, high prices and large market fluctuations, its large-scale application is limited. Relatively speaking, the development of non-precious metal catalysts for furfural reductive amination to prepare furfurylamine is very attractive. The patent document with publication number CN118874470A discloses a method for preparing a Ni@C catalyst for reductive amination of furfurylamine, which improves the performance and efficiency of furfural reductive amination, but the catalytic reaction conditions are harsh, which limits large-scale application. Therefore, the development of efficient and stable non-precious metal catalysts has become the current research on furfural reductive amination.

[0006] Based on the above background, this study designed and developed a new nickel-based catalyst system to achieve efficient conversion of HMF to HMFA. This system not only outperforms existing technologies in catalytic efficiency and selectivity, but also has mild reaction conditions and high stability, providing new possibilities for industrial applications. Summary of the invention

[0007] In order to solve the problems existing in the prior art, the present invention provides a method for preparing HMFA by catalyzing HMF with an efficient Ni-based catalyst. The preparation method of the present invention is simple to operate, fast to prepare, and has mild reaction conditions. It is superior to the prior art in catalytic efficiency and selectivity, and also has mild reaction conditions and high stability, providing new possibilities for industrial applications.

[0008] A method for preparing a nickel-based catalyst comprises: mixing an aqueous solution containing aluminum salt and nickel salt with a precipitant to obtain a Ni-Al oxide precursor; drying and calcining the Ni-Al oxide precursor to obtain Ni-Al oxide; and finally reducing the Ni-based catalyst.

[0009] The aluminum salt is selected from one or both of aluminum nitrate and aluminum sulfate; the precipitant is one or more of sodium carbonate, sodium hydroxide, ammonia water, ammonium carbonate, ammonium bicarbonate, or their corresponding aqueous solutions; the nickel salt is selected from one or more of nickel nitrate, nickel sulfate, and nickel chloride.

[0010] Furthermore, a method for preparing an efficient Ni-based catalyst for catalyzing HMF to prepare HMFA comprises the following steps:

[0011] An aqueous solution containing aluminum nitrate and nickel nitrate is added dropwise to a precipitant containing an aqueous sodium carbonate solution to obtain a precipitate, or a precipitant is added to an aqueous solution containing aluminum nitrate and nickel nitrate, and after stirring and aging, the precipitate is filtered and washed to obtain a filter cake. The filter cake is then dried and calcined to obtain Ni-Al oxide. Finally, the HMF is reduced in a tubular furnace to obtain an efficient Ni-based catalyst for preparing HMFA.

[0012] Preferably, the nitrate solution for preparing the precipitate is provided by aluminum nitrate and nickel nitrate in different contents, and preferably the Al / Ni molar ratio is (4:1) to (22:1). More preferably, it is (4:1) to (18:1). More specifically, the Al / Ni molar ratio is (6:1) to (18:1), and more preferably, it is (7:1) to (18:1); as a specific preference, the Al / Ni molar ratio is (7:1): to (9:1).

[0013] Preferably, the amount of the precipitant added is generally determined by detecting the pH value of the system liquid. The amount of the precipitant added is such that the pH value of the system liquid is greater than 9, generally 10-11.

[0014] Preferably, the precipitate is stirred and aged for 1 to 30 hours, more preferably for 1 to 20 hours, the filter cake is dried at 60 to 100°C, more preferably for 80 to 100°C, and the drying time is 2 to 12 hours. More preferably, the precipitate is stirred and aged for 20 hours, the filter cake is dried at 80°C, and the drying time is 12 hours.

[0015] Preferably, the calcination temperature of the NiAl oxide precursor is 400-800°C, more preferably 500-800°C, further preferably 600-800°C, and further preferably 700-800°C. The calcination time is 2-4 hours. More preferably, the calcination temperature of the NiAl oxide precursor is 750°C, and the calcination time is 3 hours.

[0016] Preferably, the reducing atmosphere of NiAl oxide is one of pure hydrogen and a mixture of 10% hydrogen and nitrogen. More preferably, pure hydrogen is used. More preferably, the amount of pure hydrogen introduced is 20 to 100 mL / min. More preferably, it is 50 mL / min.

[0017] Preferably, the reduction temperature of NiAl oxide is 400-750°C, and the reduction time is 2-4h. More preferably, the reduction temperature of NiAl oxide is 500-750°C, and the reduction time is 3h; further, the reduction temperature of NiAl oxide is 550-750°C; more preferably, the reduction temperature is 550-650°C; more preferably, 600°C, and the reduction time is 3h.

[0018] A Ni-based catalyst is prepared by the method described in any of the above technical solutions.

[0019] Preferably, the average size of the catalyst particles is 5 to 15 nm.

[0020] A method for preparing HMFA by catalyzing HMF with the highly efficient Ni-based catalyst as described above.

[0021] Specifically, HMF, a catalyst, anhydrous methanol and an aqueous ammonia solution are added to a reactor, and HMF is converted into HMFA by reductive amination under pressurized H2 and stirring conditions, and the reaction product is finally analyzed by a gas chromatograph.

[0022] Preferably, the mass molar ratio of the catalyst to 5-hydroxymethylfurfural is 10-200 g / mol (i.e., to react 1 mol of 5-hydroxymethylfurfural, the mass of the catalyst required is 10-200 g). Taking 0.8 g of 5-hydroxymethylfurfural as an example, the amount of catalyst added is 0.2-1 g, and more preferably 0.4 g.

[0023] Further, the volume molar ratio of methanol to 5-hydroxymethylfurfural is 1 to 10 mL / mmol. Preferably, taking 0.8 g of 5-hydroxymethylfurfural as an example, the amount of anhydrous methanol added is 10 to 20 mL, and more preferably 20 mL.

[0024] Preferably, the molar ratio of NH3 to 5-hydroxymethylfurfural in the ammonia solution is 5 to 30:1. The ammonia solution is selected from one or more of 14% (w / w) NH4OH, 25% (w / w) NH4OH, and 30% (w / w) NH4OH. More preferably, it is 25% (w / w) NH4OH. As a further preference, taking 0.8g of 5-hydroxymethylfurfural as an example, the amount of ammonia solution added is 3 to 7mL. More preferably, it is 5mL.

[0025] Preferably, the pressure of H2 introduced into the reactor is 0.1-2.5 MPa, more preferably 0.5-2 MPa, and more preferably, the pressure of hydrogen is 0.5-2 MPa, further preferably 0.5-1.5 MPa, and more preferably 1 MPa.

[0026] Preferably, the HMF reductive amination reaction temperature is 50 to 120°C, more preferably 70 to 120°C, more preferably 80 to 120°C, more preferably 80 to 110°C, more preferably 85 to 95°C, and more preferably 90°C.

[0027] Preferably, the HMF reductive amination reaction time is 2 to 12 hours, more preferably 4 hours.

[0028] Preferably, the stirring speed of the HMF reduction amination reactor is 300 to 1000 rpm, more preferably 500 rpm.

[0029] A method for preparing an efficient Ni-based catalyst for catalyzing HMF to prepare HMFA comprises the following steps: in the presence of a precipitant, a nitric acid solution containing Ni and Al is converted into a precipitate, which is then aged, filtered, washed, dried and calcined in sequence to obtain a Ni-Al oxide; and the Ni-Al oxide is reduced to obtain an efficient Ni-based catalyst.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The preparation process of the present invention is simple in procedure and mild in conditions, which greatly reduces the preparation cost and time. In the prepared catalyst, Ni metal, Ni-Al spinel and Al2O3 phases are stably present, and the formed metal Ni has a strong ability to catalyze the reduction and amination of HMF in the mixed phase of Ni-Al spinel and Al2O3, which is not conducive to the over-hydrogenation reaction of the HMFA product. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is the X-ray diffraction (XRD) pattern of the catalysts prepared in Examples 1 to 8;

[0033] Figure 2 Transmission electron microscope (TEM) images of the catalysts prepared in Examples 1 to 4.

[0034] Figure 3 This is the TEM image of the Ni-based catalyst prepared in Example 5.

[0035] Figure 4 This is the TEM image of the Ni-based catalyst prepared in Example 6.

[0036] Figure 5 This is the TEM image of the Ni-based catalyst prepared in Example 7.

[0037] Figure 6 This is the TEM image of the Ni-based catalyst prepared in Example 8. DETAILED DESCRIPTION

[0038] In order to better understand the present invention, the present invention is described in detail below in conjunction with specific embodiments. In order to elaborate on the present invention, the following examples illustrate many process details, which are not intended to cause improper limitations on the present invention.

[0039] Example 1

[0040] Aluminum nitrate and nickel nitrate were added to deionized water at a molar ratio of 8:1 to prepare aluminum nitrate and nickel nitrate solutions with concentrations of 0.16 mol / L and 0.02 mol / L respectively. Then, 1 mol / L sodium carbonate solution was added dropwise to the mixed solution until pH = 10. The solution containing the precipitate was then stirred and aged for 20 hours. Next, a circulating water vacuum pump was used for suction filtration, and the filtered precipitate was washed 5 times with deionized water. The washed precipitate was dried at 80°C for 12 hours to obtain a dry Ni-Al oxide precursor.

[0041] The dried Ni-Al oxide precursor was placed in a muffle furnace, heated at a rate of 5°C / min, heated to 750°C and kept at a constant temperature for 3h to obtain Ni-Al oxide. Subsequently, the Ni-Al oxide was placed in a tubular furnace at 600°C, and pure hydrogen was introduced at 50mL / min for a reduction reaction for 3h to prepare a Ni-based catalyst.

[0042] The HMF reduction amination reaction was carried out in a 50 mL reactor. 0.8 g HMF, 0.4 g catalyst, 20 mL anhydrous methanol and 5 mL ammonia water (25% (w / w), the same in other embodiments) were added to the reactor in sequence. Then, 0.5 MPa of hydrogen was introduced and all gas valves were closed. The reactor was stirred at 500 rpm, and the temperature was raised to 90 ° C and maintained for 4 hours to complete the HMF reduction amination reaction. After the reaction was completed, the heating was stopped and the pressure in the reactor was released, and the reaction product was taken out. After filtering out the catalyst, the reaction product was analyzed using a gas chromatograph to evaluate the catalytic effect.

[0043] Example 2

[0044] Aluminum nitrate and nickel nitrate were added to deionized water at a molar ratio of 8:1 to prepare aluminum nitrate and nickel nitrate solutions with concentrations of 0.16 mol / L and 0.02 mol / L respectively. Then, 1 mol / L sodium carbonate solution was added dropwise to the mixed solution until pH = 10. The solution containing the precipitate was then stirred and aged for 20 hours. Next, a circulating water vacuum pump was used for suction filtration, and the filtered precipitate was washed 5 times with deionized water. The washed precipitate was dried at 80°C for 12 hours to obtain a dry Ni-Al oxide precursor.

[0045] The dried Ni-Al oxide precursor was placed in a muffle furnace, heated at a rate of 5°C / min, heated to 750°C and kept at a constant temperature for 3h to obtain Ni-Al oxide. Subsequently, the Ni-Al oxide was placed in a tubular furnace at 600°C, and pure hydrogen was introduced at 50mL / min for a reduction reaction for 3h to prepare a Ni-based catalyst.

[0046] The HMF reduction amination reaction was carried out in a 50 mL reactor. 0.8 g HMF, 0.4 g catalyst, 20 mL anhydrous methanol and 5 mL ammonia water were added to the reactor in sequence. Then, 1 MPa of hydrogen was introduced and all gas valves were closed. Under stirring at 500 rpm, the temperature of the reactor was raised to 90 ° C and maintained for 4 hours to complete the HMF reduction amination reaction. After the reaction was completed, the heating was stopped and the pressure in the reactor was released, and the reaction product was taken out. After filtering out the catalyst, the reaction product was analyzed using a gas chromatograph to evaluate the catalytic effect.

[0047] Example 3

[0048] Aluminum nitrate and nickel nitrate were added to deionized water at a molar ratio of 8:1 to prepare aluminum nitrate and nickel nitrate solutions with concentrations of 0.16 mol / L and 0.02 mol / L respectively. Then, 1 mol / L sodium carbonate solution was added dropwise to the mixed solution until pH = 10. The solution containing the precipitate was then stirred and aged for 20 hours. Next, a circulating water vacuum pump was used for suction filtration, and the filtered precipitate was washed 5 times with deionized water. The washed precipitate was dried at 80°C for 12 hours to obtain a dry Ni-Al oxide precursor.

[0049] The dried Ni-Al oxide precursor was placed in a muffle furnace, heated at a rate of 5°C / min, heated to 750°C and kept at a constant temperature for 3h to obtain Ni-Al oxide. Subsequently, the Ni-Al oxide was placed in a tubular furnace at 600°C, and pure hydrogen was introduced at 50mL / min for a reduction reaction for 3h to prepare a Ni-based catalyst.

[0050] The HMF reduction amination reaction was carried out in a 50 mL reactor. 0.8 g HMF, 0.4 g catalyst, 20 mL anhydrous methanol and 5 mL ammonia water were added to the reactor in sequence. Then, 2 MPa of hydrogen was introduced and all gas valves were closed. Under stirring at 500 rpm, the temperature of the reactor was raised to 90 ° C and maintained for 4 hours to complete the HMF reduction amination reaction. After the reaction was completed, the heating was stopped and the pressure in the reactor was released, and the reaction product was taken out. After filtering out the catalyst, the reaction product was analyzed using a gas chromatograph to evaluate the catalytic effect.

[0051] Example 4

[0052] Aluminum nitrate and nickel nitrate were added to deionized water at a molar ratio of 8:1 to prepare aluminum nitrate and nickel nitrate solutions with concentrations of 0.16 mol / L and 0.02 mol / L respectively. Then, 1 mol / L sodium carbonate solution was added dropwise to the mixed solution until pH = 10. The solution containing the precipitate was then stirred and aged for 20 hours. Next, a circulating water vacuum pump was used for suction filtration, and the filtered precipitate was washed 5 times with deionized water. The washed precipitate was dried at 80°C for 12 hours to obtain a dry Ni-Al oxide precursor.

[0053] The dried Ni-Al oxide precursor was placed in a muffle furnace, heated at a rate of 5°C / min, heated to 750°C and kept at a constant temperature for 3h to obtain Ni-Al oxide. Subsequently, the Ni-Al oxide was placed in a tubular furnace at 600°C, and pure hydrogen was introduced at 50mL / min for a reduction reaction for 3h to prepare a Ni-based catalyst.

[0054] The HMF reduction amination reaction was carried out in a 50 mL reactor. 0.8 g HMF, 0.4 g catalyst, 20 mL anhydrous methanol and 5 mL ammonia water were added to the reactor in sequence. Then, 1 MPa of hydrogen was introduced and all gas valves were closed. Under stirring at 500 rpm, the temperature of the reactor was raised to 120 ° C and maintained for 4 hours to complete the HMF reduction amination reaction. After the reaction was completed, the heating was stopped and the pressure in the reactor was released, and the reaction product was taken out. After filtering out the catalyst, the reaction product was analyzed using a gas chromatograph to evaluate the catalytic effect.

[0055] Example 5

[0056] Aluminum nitrate and nickel nitrate were added to deionized water at a molar ratio of 4:1 to prepare aluminum nitrate and nickel nitrate solutions with concentrations of 0.08 mol / L and 0.02 mol / L. Then, 1 mol / L sodium carbonate solution was added dropwise to the mixed solution until pH = 10. The solution containing the precipitate was then stirred and aged for 20 hours. Next, a circulating water vacuum pump was used for suction filtration, and the filtered precipitate was washed 5 times with deionized water. The washed precipitate was dried at 80°C for 12 hours to obtain a dry Ni-Al oxide precursor.

[0057] The dried Ni-Al oxide precursor was placed in a muffle furnace, heated at a rate of 5°C / min, heated to 750°C and kept at a constant temperature for 3h to obtain Ni-Al oxide. Subsequently, the Ni-Al oxide was placed in a tubular furnace at 600°C, and pure hydrogen was introduced at 50mL / min for a reduction reaction for 3h to prepare a Ni-based catalyst.

[0058] The HMF reduction amination reaction was carried out in a 50 mL reactor. 0.8 g HMF, 0.4 g catalyst, 20 mL anhydrous methanol and 5 mL ammonia water were added to the reactor in sequence. Then, 1 MPa of hydrogen was introduced and all gas valves were closed. Under stirring at 500 rpm, the temperature of the reactor was raised to 90 ° C and maintained for 4 hours to complete the HMF reduction amination reaction. After the reaction was completed, the heating was stopped and the pressure in the reactor was released, and the reaction product was taken out. After filtering out the catalyst, the reaction product was analyzed using a gas chromatograph to evaluate the catalytic effect.

[0059] Example 6

[0060] Aluminum nitrate and nickel nitrate were added to deionized water at a molar ratio of 18:1 to prepare aluminum nitrate and nickel nitrate solutions with concentrations of 0.36 mol / L and 0.02 mol / L respectively. Then, 1 mol / L sodium carbonate solution was added dropwise to the mixed solution until pH = 10. The solution containing the precipitate was then stirred and aged for 20 hours. Next, a circulating water vacuum pump was used for suction filtration, and the filtered precipitate was washed 5 times with deionized water. The washed precipitate was dried at 80°C for 12 hours to obtain a dry Ni-Al oxide precursor.

[0061] The dried Ni-Al oxide precursor was placed in a muffle furnace, heated at a rate of 5°C / min, heated to 750°C and kept at a constant temperature for 3h to obtain Ni-Al oxide. Subsequently, the Ni-Al oxide was placed in a tubular furnace at 600°C, and pure hydrogen was introduced at 50mL / min for a reduction reaction for 3h to prepare a Ni-based catalyst.

[0062] The HMF reduction amination reaction was carried out in a 50 mL reactor. 0.8 g HMF, 0.4 g catalyst, 20 mL anhydrous methanol and 5 mL ammonia water were added to the reactor in sequence. Then, 1 MPa of hydrogen was introduced and all gas valves were closed. Under stirring at 500 rpm, the temperature of the reactor was raised to 90 ° C and maintained for 4 hours to complete the HMF reduction amination reaction. After the reaction was completed, the heating was stopped and the pressure in the reactor was released, and the reaction product was taken out. After filtering out the catalyst, the reaction product was analyzed using a gas chromatograph to evaluate the catalytic effect.

[0063] Example 7

[0064] Aluminum nitrate and nickel nitrate were added to deionized water at a molar ratio of 8:1 to prepare aluminum nitrate and nickel nitrate solutions with concentrations of 0.16 mol / L and 0.02 mol / L respectively. Then, 1 mol / L sodium carbonate solution was added dropwise to the mixed solution until pH = 10. The solution containing the precipitate was then stirred and aged for 20 hours. Next, a circulating water vacuum pump was used for suction filtration, and the filtered precipitate was washed 5 times with deionized water. The washed precipitate was dried at 80°C for 12 hours to obtain a dry Ni-Al oxide precursor.

[0065] The dried Ni-Al oxide precursor was placed in a muffle furnace, heated at a rate of 5°C / min, heated to 750°C and kept at a constant temperature for 3h to obtain Ni-Al oxide. Subsequently, the Ni-Al oxide was placed in a tubular furnace at 750°C, and pure hydrogen was introduced at 50mL / min for a reduction reaction for 3h to prepare a Ni-based catalyst.

[0066] The HMF reduction amination reaction was carried out in a 50 mL reactor. 0.8 g HMF, 0.4 g catalyst, 20 mL anhydrous methanol and 5 mL ammonia water were added to the reactor in sequence. Then, 1 MPa of hydrogen was introduced and all gas valves were closed. Under stirring at 500 rpm, the temperature of the reactor was raised to 90 ° C and maintained for 4 hours to complete the HMF reduction amination reaction. After the reaction was completed, the heating was stopped and the pressure in the reactor was released, and the reaction product was taken out. After filtering out the catalyst, the reaction product was analyzed using a gas chromatograph to evaluate the catalytic effect.

[0067] Example 8

[0068] Aluminum nitrate and nickel nitrate were added to deionized water at a molar ratio of 8:1 to prepare aluminum nitrate and nickel nitrate solutions with concentrations of 0.16 mol / L and 0.02 mol / L respectively. Then, 1 mol / L sodium carbonate solution was added dropwise to the mixed solution until pH = 10. The solution containing the precipitate was then stirred and aged for 20 hours. Next, a circulating water vacuum pump was used for suction filtration, and the filtered precipitate was washed 5 times with deionized water. The washed precipitate was dried at 80°C for 12 hours to obtain a dry Ni-Al oxide precursor.

[0069] The dried Ni-Al oxide precursor was placed in a muffle furnace, heated at a rate of 5°C / min, heated to 750°C and kept at a constant temperature for 3h to obtain Ni-Al oxide. Subsequently, the Ni-Al oxide was placed in a tubular furnace at 500°C, and pure hydrogen was introduced at 50mL / min for a reduction reaction for 3h to prepare a Ni-based catalyst.

[0070] The HMF reduction amination reaction was carried out in a 50 mL reactor. 0.8 g HMF, 0.4 g catalyst, 20 mL anhydrous methanol and 5 mL ammonia water were added to the reactor in sequence. Then, 1 MPa of hydrogen was introduced and all gas valves were closed. Under stirring at 500 rpm, the temperature of the reactor was raised to 90 ° C and maintained for 4 hours to complete the HMF reduction amination reaction. After the reaction was completed, the heating was stopped and the pressure in the reactor was released, and the reaction product was taken out. After filtering out the catalyst, the reaction product was analyzed using a gas chromatograph to evaluate the catalytic effect.

[0071] Product Characterization:

[0072] The XRD patterns of the Ni-based catalysts prepared in Examples 1 to 8 are as follows: Figure 1 As shown by Figure 1 It can be seen that all the Ni-based catalysts prepared in Examples 1 to 8 show characteristic peaks of γ-Al2O3 and NiAl2O4.

[0073] The TEM images of the Ni-based catalysts prepared in Examples 1 to 4 are as follows: Figure 2As shown by Figure 2 It can be seen that the average size of the spherical Ni particles of the catalysts prepared in Examples 1 to 4 is 7.4 nm.

[0074] The TEM image of the Ni-based catalyst prepared in Example 5 is as follows: Figure 3 As shown, the average size of the spherical Ni particles of the catalyst prepared in Example 5 is 9.3 nm.

[0075] The TEM image of the Ni-based catalyst prepared in Example 6 is as follows: Figure 4 As shown, the average size of the spherical Ni particles of the catalyst prepared in Example 6 is 6.3 nm.

[0076] The TEM image of the Ni-based catalyst prepared in Example 7 is as follows: Figure 5 As shown, the average size of the spherical Ni particles of the catalyst prepared in Example 7 is 12.3 nm.

[0077] The TEM image of the Ni-based catalyst prepared in Example 8 is as follows: Figure 6 As shown, the average size of the spherical Ni particles of the catalyst prepared in Example 8 is 6.6 nm.

[0078] Performance Test:

[0079] The Ni-based catalyst was used to test the reductive amination of HMF using the test methods of Examples 1 to 8, and the obtained products were analyzed by gas chromatography. The results of the reductive amination reaction for 4 hours are shown in Table 1. Table 1 shows the evaluation performance results of the catalysts prepared in Examples 1 to 8 for catalyzing the reductive amination of HMF to produce HMFA.

[0080] Table 1 Product analysis results of HMF reductive amination for 4 h

[0081]

[0082] According to the data in Table 1, the Ni-based catalysts prepared in Examples 1 to 8 exhibited extremely high conversion rates in the HMF conversion process. The selectivity of HMFA can be further regulated by adjusting the reaction temperature, the Al / Ni ratio of the catalyst, and the reduction temperature. Figures 2 to 6 The comparative analysis further showed that the size of the metallic Ni particles on the Ni-based catalyst is the key factor determining the HMFA selectivity in the HMF reductive amination reaction.

[0083] Combined with the evaluation results of Examples 1 to 3, the optimal reaction pressure for the reductive amination of HMF is 1 MPa. Further increase in pressure will lead to preferential hydrogenation rather than reductive amination, so that HMF is hydrogenated to furan dimethanol (DHMF), Schiff base is hydrogenated to secondary amines, and the product HMFA furan ring is hydrogenated to 5-methyl-2-tetrahydrofurfurylamine (HMTHFA), resulting in a decrease in the selectivity of HMFA.

[0084]

[0085] Based on the evaluation results of Examples 2 and 4, the optimal temperature for the HMF reductive amination reaction is 90° C. A further increase in the reaction temperature will lead to a decrease in the selectivity of HMFA, thereby promoting the conversion of HMFA to an over-hydrogenated product.

[0086] Catalysts with different NiAl2O4 and Al2O3 contents were obtained by adjusting the Al / Ni ratio of the catalyst. Catalysts with different Al / Ni ratios were reduced to obtain catalysts with different active metal Ni contents. Combined with the evaluation results of Examples 2, 5 and 6, the optimal Al / Ni ratio of the catalyst for HMF reductive amination was 8:1. Further increase in the Al / Ni ratio resulted in a reduction in Ni metal sites, and a higher HFMA conversion per unit Ni metal could not be achieved.

[0087] On the Ni-based catalyst reduced at 600°C, spherical metal Ni active sites with an average particle size of 7.4 nm were generated, and these sites showed good HMF conversion performance. Combined with the evaluation results of Examples 2, 7 and 8, when the reduction temperature was increased to 750°C, the size of the metal Ni particles increased, resulting in a decrease in its catalytic performance, which was not conducive to the selective reduction of HMF to HMFA. When the reduction temperature was reduced to 500°C, although the size of the Ni metal active sites was small, the number was small, which also made the catalyst insufficiently active and could not effectively promote the conversion of HMF to HMFA.

[0088] The performance test results of the above embodiments show that the method for preparing the high-efficiency nickel-based catalyst provided by the present invention exhibits higher HMF conversion rate and HMFA selectivity in the reaction of catalyzing the reduction amination of HMF to prepare HMFA.

[0089] The above description is only a preferred embodiment of the present invention. Within the scope of the principle of the present invention, those skilled in the art may make several improvements and modifications, which should also be considered as the protection scope of the present invention.

Claims

1. A method for preparing a nickel-based catalyst, characterized in that: include: mixing an aqueous solution containing aluminum salt and nickel salt with a precipitant to obtain a Ni-Al oxide precursor; The Ni-Al oxide precursor is dried and calcined to obtain the Ni-Al oxide; and finally the nickel-based catalyst is obtained through reduction.

2. The method for preparing a nickel-based catalyst according to claim 1, characterized in that: The aluminum salt is selected from one or both of aluminum nitrate and aluminum sulfate; the precipitant is one or more of sodium carbonate, sodium hydroxide, ammonia water, ammonium carbonate, ammonium bicarbonate, or their corresponding aqueous solutions; the nickel salt is selected from one or more of nickel nitrate, nickel sulfate, and nickel chloride.

3. The method for preparing a nickel-based catalyst according to claim 1, characterized in that: The Al / Ni molar ratio is (4:1) to (22:1).

4. The method for preparing a nickel-based catalyst according to claim 1, characterized in that: The calcination temperature is 400-800°C.

5. The method for preparing a nickel-based catalyst according to claim 1, characterized in that: The reduction is carried out using hydrogen at a temperature of 400-750°C.

6. A nickel-based catalyst, characterized in that The compound is prepared by the preparation method according to any one of claims 1 to 5.

7. The nickel-based catalyst according to claim 6, characterized in that The average size of the catalyst particles is 5 to 15 nm.

8. A method for preparing 5-hydroxymethyl-2-furfurylamine from 5-hydroxymethylfurfural, characterized in that: include: In the presence of a catalyst, anhydrous methanol, and an ammonia solution, in a hydrogen atmosphere and under stirring conditions, 5-hydroxymethylfurfural is reductively aminized and converted into 5-hydroxymethyl-2-furfurylamine; the catalyst is the catalyst according to any one of claims 6 or 7.

9. The method for preparing 5-hydroxymethyl-2-furfurylamine from 5-hydroxymethylfurfural according to claim 8, characterized in that: The hydrogen pressure is 0.1-2.5 MPa; the reductive amination reaction temperature is 50-120°C.

10. The method for preparing 5-hydroxymethyl-2-furfurylamine from 5-hydroxymethylfurfural according to claim 8, characterized in that: The amount of the catalyst added is 10 to 200 g / mol relative to the molar amount of 5-hydroxymethylfurfural.

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