A carbon-coated nickel-iron catalyst and its application in the hydrogenation of 5-hydroxymethylfurfural

Abstract

The present invention relates to the technical field of catalyst preparation methods and 5-hydroxymethylfurfural catalysis, and specifically relates to a preparation method of a carbon-coated nickel-iron catalyst and its application in the selective preparation of 2,5-bis(hydroxymethyl)furan by catalyzing 5-hydroxymethylfurfural at normal temperature and pressure. A series of nickel-iron catalysts supported on biomass-derived carbon (NixFey@C-T) were synthesized by a one-pot method. By adjusting the nickel-iron ratio in the catalyst, the calcination temperature of the catalyst, and optimizing the reaction conditions, the best balance was found between selectivity and reaction activity, realizing the selective hydrogenation of 5-hydroxymethylfurfural to synthesize 2,5-bis(hydroxymethyl)furan (yield: 95%) by a non-noble metal catalyst under aqueous phase conditions at normal temperature and pressure. At the same time, the catalyst has strong magnetism and can be recovered by means of an external magnet, which has great industrial application value.

Description

Technical Field

[0001] The present invention relates to the technical fields of catalyst preparation and 5-hydroxymethylfurfural catalysis, and particularly relates to a carbon-coated nickel-iron catalyst, a preparation method thereof, and an application in catalyzing the preparation of 2,5-furandimethanol from 5-hydroxymethylfurfural Background Art

[0002] Among the hydrogenation products of 5-hydroxymethylfurfural (HMF), 2,5-bis(hydroxymethyl)furan (BHMF) is a unique diol industrial intermediate with great application value in biomass conversion. It can be used in the preparation of artificial receptors for molecular recognition, man-made fibers, polyamides, polyethers, furan-based resins and other high-value fine chemicals [Tang, Xing, et al. Chemoselective hydrogenation of biomass derived 5-hydroxymethylfurfural to diols: Key intermediates for sustainable chemicals, materials and fuels [J]. Renewable and Sustainable Energy Reviews, 2017, 77: 287-296.]. The selective hydrogenation of HMF to BHMF has attracted much attention. However, HMF has three functional groups: aldehyde group, hydroxyl group and C=C double bond, and its chemical properties are active. During the hydrogenation process, its reaction pathways are diverse and the products are complex. For example, HMF directly decarboxylates to produce furfuryl alcohol, selectively hydrogenates to prepare the polymer monomer 2,5-bis(hydroxymethyl)furan (BHMF), over-hydrogenates to prepare BHMTHF, hydrolyzes to produce 1-hydroxyhexane-2,5-dione (HHD), and hydrogenates and dehydrates to produce 5-methylfurfural (MF), 2,5-dimethylfuran (DMF), etc. Therefore, highly selective catalytic preparation of BHMF from HMF has become the focus and difficulty of research. Noble metal catalysts have extremely excellent catalytic performance and can achieve the catalytic preparation of BHMF from HMF under relatively mild conditions. The team led by Fulignati [Fulignati, et al. Insight into the hydrogenation of pure and crude HMF to furan diols using Ru / C as catalyst [J]. Applied Catalysis A: General, 2019, 578: 122-133.] reported that the Ru / C catalyst reacted at 100 °C for 30 min under a H2 pressure of 3 MPa, and the BHMF yield was 79.5%.Chatterjee et al. [Chatterjee, et al. Selective hydrogenation of 5-hydroxymethylfurfural to 2,5-bis-(hydroxymethyl)furan using Pt / MCM-41 in an aqueous medium: a simple approach [J]. Green Chemistry, 2014, 16(11): 4734-4739.], under relatively mild conditions (35 °C, 0.8 MPa H2), the Pt catalyst supported on MCM-41 can achieve 100% HMF conversion and a BHMF yield of 98.9%. Han et al. [Han, Jusung, et al. Heterogeneous zirconia-supported ruthenium catalyst for highly selective hydrogenation of 5-hydroxymethyl-2-furaldehyde to 2,5-bis(hydroxymethyl)furans in various n-alcohol solvents [J]. RSC advances, 2016, 6(96): 93394-93397.] used ruthenium supported on zirconia (Ru(OH). xThe (Ru / ZrO2) catalyst can hydrogenate and reduce HMF to BHMF with high activity and selectivity, and 99% of BHMF can be obtained at 120 °C. However, due to the low reserves, high price of noble metals, and the significant impact of market fluctuations on the supply relationship, the development and practical industrial application of noble metal catalysts are greatly restricted. Developing efficient and inexpensive non-noble metal catalysts is the key to realizing the high-value utilization of biomass resources. Ni-based catalysts have extremely high activity in hydrogenation reactions and are considered potential substitutes for noble metal hydrogenation catalysts. However, Ni-based catalysts have poor selectivity in the HMF hydrogenation reaction and easily lead to over-hydrogenation of the furan ring. Usually, the catalyst needs to be modified to improve the selectivity of the product. Ahishakiye R et al. [Ahishakiye, Rosine, et al. Novel noble metal-free and recyclable Co-CoOx-FeNiCo / γ-Al2O3 catalyst for selective hydrogenation of 5-hydroxymethylfurfural to 2,5-dimethylfuran or 2,5-bis(hydroxymethyl)furan [J]. Chemical Engineering Journal, 2022, 450: 138187.] developed a novel Co-CoOx-FeNiCo / γ-Al2O3 catalyst for the selective hydrogenation of HMF. Due to the Fe-Ni interaction and the oxygen affinity of Fe species, the metal sites preferentially adsorb and activate the C=O bond of HMF through the η 1 (O)-adsorption mode. The reduced Co-CoOx-FeNiCo / γ-Al2O3 catalyst at 300 °C can catalyze the complete conversion of HMF to BHMF when reacting at 150 °C and 2 MPa H2 for 22 h, and the catalyst has high stability and still maintains the original catalytic activity after being recycled 6 times. However, the reaction conditions become relatively harsh and need to be carried out at a higher temperature, and the catalyst needs to be further designed and optimized. Fe, as the most abundant transition element in the earth's crust, is cheap and easily available, and may be the most attractive non-noble metal element for biomass conversion. Utilizing the oxygen affinity of Fe metal to change the adsorption configuration of reaction molecules on the catalyst surface is particularly important for designing an efficient, highly selective, and low-cost Ni-based catalyst for the preparation of BHMF. Summary of the Invention

[0003] To solve the problems existing in the above-mentioned prior art, the present invention provides a preparation method of a carbon-coated nickel-iron catalyst (NixFey@C-T) and its application in the preparation of 2,5-furan dimethanol from 5-hydroxymethylfurfural. By adjusting the nickel-iron ratio in the catalyst, the calcination temperature of the catalyst, and optimizing the reaction conditions, the present invention finds the best balance between selectivity and reactivity, and realizes the selective hydrogenation of HMF to synthesize BHMF under mild conditions by a non-precious metal nickel-iron catalyst under aqueous phase conditions. Moreover, the catalyst has strong magnetism, which is convenient for separation and recovery after the reaction.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A carbon-coated nickel-iron catalyst (NixFey@C-T) is prepared by the following method:

[0006] (1) First, weigh glucose, ferric nitrate nonahydrate, and nickel nitrate hexahydrate and dissolve them in an isopropanol solution. Then transfer the solution into a closed high-pressure reaction kettle, heat it to 150 - 200 °C under magnetic stirring, and keep it for 4 - 8 h. After cooling to room temperature, filter it under reduced pressure, wash the filter cake, and dry it in vacuum at 60 - 100 °C to obtain a solid named NixFey-GL (where x and y are the molar ratios of nickel and iron, and x:y = 1:0, 20:1, 5:1, 3:1, 2:1, 1:1, 0:1).

[0007] The addition ratio of the glucose, ferric nitrate nonahydrate, nickel nitrate hexahydrate, and isopropanol is (2 - 7) g:(0 - 6) g:(0 - 5) g:(50 - 300) mL

[0008] (2) Subject the catalyst precursor (NixFey-GL) obtained in step (1) to temperature-programmed reduction in a hydrogen atmosphere, and passivate it with oxygen after cooling to obtain a carbon-coated nickel-iron catalyst (NixFey@C-T, where T represents the reduction temperature: 250 °C, 350 °C, 450 °C).

[0009] The above catalyst is characterized in that: the addition ratio of the glucose, ferric nitrate nonahydrate, nickel nitrate hexahydrate, and isopropanol is (2 - 7) g:(0 - 6) g:(0 - 5) g:(50 - 300) mL;

[0010] Furthermore, the above catalyst is characterized in that: the addition ratio of the glucose, ferric nitrate nonahydrate, nickel nitrate hexahydrate, and isopropanol is (3 - 6) g:(0 - 6) g:(0 - 5) g:(100 - 200) mL.

[0011] Furthermore, in step (1), the reaction temperature in the reaction kettle is 180 °C and it is kept for 6 h.

[0012] Further, the filtration and washing process in step (1) is to wash three times with anhydrous ethanol and three times with ultrapure water.

[0013] Further, the vacuum drying temperature in step (1) is 80 °C.

[0014] Further, the reduction process in step (2) is as follows: heating to 200 - 500 °C at a rate of 5 °C / min in a hydrogen - passing tubular furnace, holding for 2 - 4 h, naturally cooling to room temperature, and then passivating with oxygen to obtain the carbon - coated nickel - iron catalyst.

[0015] Preferably: heating to 350 °C at a rate of 5 °C / min in a hydrogen - passing tubular furnace, holding for 2 h, naturally cooling to room temperature, and then passivating with oxygen to obtain the carbon - coated nickel - iron catalyst.

[0016] Further, the oxygen passivation process in step (2) is to passivate with a mixture of oxygen and nitrogen with an oxygen volume percentage of 1% for 2 h.

[0017] The present invention also provides an application of the above - mentioned carbon - coated nickel - iron catalyst (NixFey@C - T) in the selective hydrogenation of 5 - hydroxymethylfurfural to prepare 2,5 - dihydroxymethylfuran.

[0018] Add the catalyst, solvent, and 5 - hydroxymethylfurfural into a pressure - resistant reaction flask according to the dosage ratio of (10 - 50) mg:(10 - 20) mL:1 mmol. After evacuating to remove air, insert a balloon filled with hydrogen, and react at 25 - 50 °C with magnetic stirring for 0.5 - 5 h to obtain 2,5 - dihydroxymethylfuran.

[0019] Preferably: add the Ni3Fe1@C - 350 catalyst, water, and 5 - hydroxymethylfurfural into a pressure - resistant reaction flask according to the dosage ratio of 40 mg:10 mL:1 mmol. After evacuating to remove air, insert a balloon filled with hydrogen, and react at 30 °C with magnetic stirring for 4.5 h to obtain 2,5 - dihydroxymethylfuran.

[0020] Compared with the prior art, the present invention has the following advantages and effects:

[0021] 1. The present invention uses biomass - derived glucose as the carbon source, non - precious metal nickel as the active metal, and non - precious metal iron as the co - catalyst, and in - situ prepares the NiFe catalyst by a one - pot method. The catalyst preparation method is simple, and the NiFe metal ratio can be changed during the catalyst preparation process to change the catalyst structure, thereby regulating the selectivity of the reaction.

[0022] 2. The present invention uses the catalyst prepared above for the selective hydrogenation of 5 - hydroxymethylfurfural to prepare 2,5 - dihydroxymethylfuran. By selecting the best balance between catalyst activity and selectivity, the catalytic selective preparation of BHMF from HMF is realized under normal temperature and pressure conditions. Brief Description of the Drawings

[0023] Figure 1 This is a simplified flow chart of the preparation method of the catalyst of the present invention.

[0024] Figure 2 This is a thermogravimetric curve of the carbon-coated nickel-iron catalyst precursor (Ni3Fe1-GL) and glucose prepared in Example 1.

[0025] Figure 3 This is an energy spectrum diagram of a scanning electron microscope of the carbon-coated nickel-iron catalyst (Ni3Fe1@C-350) prepared in Example 1.

[0026] Figure 4 This is an X-ray diffraction pattern (XRD pattern) of the carbon-coated nickel-iron catalyst (Ni3Fe1@C-350) prepared in Example 1, as well as Ni@C-350, Fe@C-350, and C-350.

[0027] Figure 5 This is a scanning electron microscope image (SEM image) and a transmission electron microscope image (TEM image) of the carbon-coated nickel-iron catalyst (Ni3Fe1@C-350) prepared in Example 1.

[0028] Figure 6 This is a graph of the carbon-coated nickel-iron series catalysts prepared in Example 1, the HMF conversion rate, and the BHMF yield.

[0029] Figure 7 This is a physical image of the catalytic conversion of HMF by the carbon-coated nickel-iron catalyst (Ni3Fe1@C-350) prepared in Example 1 at normal temperature and pressure.

[0030] Figure 8 This is a physical image of the magnet-assisted recovery after the reaction of the carbon-coated nickel-iron series catalysts (Ni3Fe1@C-350) prepared in Example 1.

[0031] The technical solutions of the present invention will be described in detail below in conjunction with specific embodiments and the accompanying drawings of the specification. However, the following embodiments are not used to limit the scope of protection required by the present invention.

[0032] Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products. The specific implementation cases are as follows:

[0033] Example 1 A carbon-coated nickel-iron catalyst (NixFey@C-T) was prepared by the following method:

[0034] (1) As Figure 1As shown in the figure. First, weigh 5.4 g of glucose, 1.36 g of iron(III) nitrate nonahydrate, 2.94 g of nickel(II) nitrate hexahydrate, and 200 ml of isopropanol into a 250 ml pressure-resistant stainless steel autoclave. After sealing the autoclave, heat it up to 180 °C and hold for 6 h. After cooling to room temperature, filter, wash the filter cake, and dry it at 80 °C under vacuum for 12 h to obtain a solid named Ni3Fe1-GL. Except for the different molar ratios of Ni and Fe, under the condition that the total metal molar amount is 13.5 mmol, prepare a series of catalyst precursors NixFey-GL (where x and y are the molar ratios of nickel and iron, x:y = 1:0, 20:1, 5:1, 3:1, 2:1, 1:1, 0:1) according to the same method.

[0035] (2) Heat the catalyst precursor (NixFey-GL) obtained in step (1) to 350 °C at a rate of 5 °C / min in a hydrogen-purged tubular furnace, hold for 2 h, and then cool naturally to room temperature. Subsequently, passivate it with a mixture of oxygen and nitrogen with an oxygen volume percentage of 1% for 2 h to obtain a carbon-coated nickel-iron catalyst (NixFey@C-350). Except for the different calcination temperatures under a hydrogen atmosphere, prepare a series of NixFey@C-T catalysts (where T is the reduction temperature, 250 °C, 350 °C, 450 °C) according to the same method.

[0036] Figure 2 is the thermal decomposition diagram of Ni3Fe1-GL and glucose (GL). The prepared Ni3Fe1-GL and glucose have different thermal stabilities, indicating that during the preparation of Ni3Fe1-GL, the glucose structure is destroyed and new substances are formed. At the same time, under high-temperature conditions, glucose initially remains 14.3%, while NiFe-GL finally remains 40.4% at 1000 °C.

[0037] Explore the surface morphology of the carbon-coated nickel-iron catalyst (Ni3Fe1@C-350) prepared in Example 1 by SEM ( Figure 3 ), and the results show that the carbon-coated nickel-iron catalyst (Ni3Fe1@C-350) is composed of smaller irregular particles stacked together, and it can be found by EDS energy spectrum that the nickel and iron elements in the Ni3Fe1@C-350 catalyst are evenly distributed and there is no agglomeration phenomenon.

[0038] Figure 4XRD patterns of Ni3Fe1@C-350 catalyst, Ni@C-350, Fe@C-350, and C-350. After calcination at 350 °C, the nickel metal in the Ni@C-350 catalyst was well-reduced, and the diffraction pattern matched well with the PDF card of nickel (JCPDS, PDF#70-0989). The characteristic peaks at 2θ = 44.5°, 51.3°, and 76.4° corresponded to the (111), (200), and (220) crystal planes of nickel, respectively. In contrast, iron in Fe@C-350 was relatively difficult to reduce, and iron species existed in the form of oxides at this temperature. There may be an overflow phenomenon on the surface of NixFey, which reduced the reduction temperature of iron. After reduction at 350 °C, it existed as Ni3Fe1 alloy, and the remaining carbon in the catalyst may exist as amorphous carbon and graphitized carbon.

[0039] The carbon-coated nickel-iron catalyst (Ni3Fe1@C-350) was observed by transmission electron microscopy (TEM). The obtained transmission electron micrograph is as Figure 5 shown. It can be clearly seen in the TEM image that nickel-iron nanoparticles are uniformly dispersed in the carbon material. It can be clearly seen that there is a carbon layer coating on the surface of the catalyst, and at the same time, EDS shows that nickel and iron elements are uniformly distributed in the carbon material.

[0040] Figure 6 Relationship diagram between the carbon-coated nickel-iron series catalysts prepared in Example 1 and the conversion rate of HMF and the yield of BHMF. The results show that as the Ni content increases, the hydrogenation activity of the catalyst increases, the conversion rate of HMF becomes higher. At the same time, the doping of Fe will change the reaction selectivity. An appropriate NiFe ratio can achieve a balance between activity and selectivity, realizing a high yield of BHMF.

[0041] Figure 7 Practical diagram of the catalytic conversion of HMF by the carbon-coated nickel-iron series catalyst (Ni3Fe1@C-350) prepared in Example 1 at room temperature and atmospheric pressure. The catalyst and the substrate were added to a pressure-resistant reaction flask. After evacuating to remove air, a balloon filled with hydrogen was inserted, and the reaction was carried out under magnetic stirring at 30 °C.

[0042] Figure 8 Practical diagram of the magnet-assisted recovery after the reaction of the carbon-coated nickel-iron series catalyst (Ni3Fe1@C-350) prepared in Example 1. The catalyst contains magnetic metals such as nickel and iron, resulting in strong magnetism, and the catalyst and the reaction solution can be separated by an external magnet.

[0043] Example 2-14

[0044] Application of the carbon-coated nickel-iron series catalyst prepared in Example 1 in the hydrogenation of 5-hydroxymethylfurfural to prepare 2,5-bis(hydroxymethyl)furan. The steps are as follows:

[0045] Add NixFey@C-T catalyst (40 mg), HMF (1 mmol), and solvent (methanol, 10 mL) into a high-pressure reactor. After sealing, fill and discharge with H2 multiple times to displace the air in the high-pressure reactor. After the filling and discharging of gas, pressurize H2 to 1 MPa. Subsequently, heat the reactor from room temperature to 50 °C, and stir the reaction at a rate of 1000 r / min under magnetic stirring for 1 h. After the reaction is completed, quickly cool the reactor to room temperature. Filter the reaction solution through a 0.45-μm organic filter head and analyze it by gas chromatography (GC), and identify the products using a gas chromatography-mass spectrometry (GC-MS) instrument.

[0046] Table 1 Hydrogenation of HMF to BHMF Catalyzed by Different Catalysts a

[0047]

[0048] a Reaction conditions: HMF 1 mmol, catalyst 40 mg, methanol 10 ml, H2 1 MPa, 50 °C, 1 h. b 150 °C, 2 h; 1 - 2,5-dihydroxymethylfuran (BHMF), 2 - 2,5-dihydroxymethyltetrahydrofuran (BHMTHF), 3 - 5-methylfurfuryl alcohol (MFA), 4 - 5-methylfurfural (MF).

[0049] The different Ni / Fe ratios affect the reaction activity of the catalyst and the selectivity of the products. The specific results are shown in Table 1. As the Ni content increases, the hydrogenation activity of the catalyst becomes stronger, and the conversion rate of HMF becomes higher. With the doping of Fe, the reaction selectivity will change. An appropriate NiFe ratio can achieve the balance of activity and selectivity. At the same time, the calcination temperature of the catalyst affects the activity of the catalyst. The catalyst reduced at 350 °C has the best activity. When using the Ni3Fe1@C-350 catalyst poisoned with KSCN, the Ni3Fe1@C-350(HCl) catalyst pickled with HCl, as well as C-350 and Fe@C-350 as catalysts, there is basically no conversion of HMF, indicating that Ni plays a major role in the reaction, while Fe and C basically have no hydrogenation activity but can change the reaction selectivity.

[0050] Examples 15 - 25

[0051] Study the influence of different solvents on the catalytic activity. Add the Ni3Fe1@C-T catalyst (40 mg), HMF (1 mmol), and the solvent into a high-pressure reactor. After sealing, fill and discharge with H2 multiple times to displace the air in the high-pressure reactor. After the filling and discharging of gas are completed, pressurize H2 to 1 MPa. Subsequently, heat the reactor from room temperature to 50 °C and stir the reaction at a rate of 1000 r / min under magnetic stirring for 1 h. After the reaction is completed, quickly cool the reactor to room temperature. Filter the reaction solution with a 0.45-μm organic filter head and analyze it by gas chromatography (GC), and identify the products with a gas chromatography-mass spectrometry (GC-MS). The results show that polar proton solvents are beneficial to the conversion of HMF. The non-polar solvents have poor solubility with the substrate and low conversion rates. At the same time, there is a certain correlation between the Lewis acid of the solvent and the reaction. The stronger the Lewis acid of the solvent, the higher the conversion rate of HMF. Water has the strongest polarity and Lewis acidity and the best reaction effect. Specifically, it is shown in Table 2 as follows.

[0052] Table 2 Influence of different solvents on the hydrogenation of HMF to prepare BHMF a

[0053]

[0054] a Reaction conditions: HMF 1 mmol, Ni3Fe1@C-350 40 mg, solvent 10 ml, H2 1 MPa 50 °C 1 h; 1 - 2,5-dihydroxymethylfuran (BHMF), 2 - 2,5-dihydroxymethyltetrahydrofuran (BHMTHF), 3 - 5-methylfurfuryl alcohol (MFA), 4 - 5-methylfurfural (MF).

[0055] Examples 26 - 28

[0056] Study the influence of reaction temperature on the conversion of HMF and the selectivity of BHMF. According to the operation method and steps of Example 15, add the Ni3Fe1@C-T catalyst (40 mg), HMF (1 mmol), and water into a high-pressure reactor. After sealing, fill and discharge with H2 multiple times to displace the air in the high-pressure reactor. After the filling and discharging of gas are completed, pressurize H2 to 1 MPa. Subsequently, heat the reactor from room temperature to the set temperature and stir the reaction at a rate of 1000 r / min under magnetic stirring for 1 h. The results show that higher temperatures are more beneficial to the conversion of HMF. The conversion rate of HMF is greater than 99% at 50 °C, and 95% of BHMF can be obtained. Under low-temperature conditions, the selectivity of BHMF is higher, up to 98% at most. Specifically, it is shown in Table 3 as follows:

[0057] Table 3 Hydrogenation of HMF to prepare BHMF at different temperatures a

[0058]

[0059] a Reaction conditions: 1 mmol of HMF, 40 mg of Ni3Fe1@C-350, 10 ml of water, 1 MPa of H2, T = 1 h. 1 - 2,5-bis(hydroxymethyl)furan (BHMF), 2 - 2,5-bis(hydroxymethyl)tetrahydrofuran (BHMTHF), 3 - 5-methylfurfuryl alcohol (MFA), 4 - 5-methylfurfural (MF).

[0060] Examples 29 - 32

[0061] To study the effect of hydrogen content on the conversion of HMF and the selectivity of BHMF. According to the operation steps and methods of Examples 29 - 31, add Ni3Fe1@C-T catalyst (40 mg), HMF (1 mmol), and water (10 ml) into a high-pressure reactor. After sealing, repeatedly charge and discharge with H2 to displace the air in the high-pressure reactor. Change the hydrogen pressure in the reaction system (1 MPa, 2 MPa, 3 MPa). Heat the reactor to 30 °C and stir the reaction at a rate of 1000 r / min for 1 h under magnetic stirring.

[0062] According to the operation steps and methods of Example 32, add Ni3Fe1@C-T catalyst (40 mg), HMF (1 mmol), and water (10 ml) into a pressure-resistant reaction flask. After evacuating to remove air, insert a balloon filled with hydrogen to achieve atmospheric pressure conditions. At the same time, heat to 30 °C and react for 1 h under magnetic stirring (1000 r / min) to obtain 2,5-bis(hydroxymethyl)furan.

[0063] The results show that the H2 pressure affects the conversion of HMF and the selectivity of BHMF. At higher H2 pressures, more H2 can be dissolved in water, which is beneficial for the contact between H2 and the catalyst, thus more beneficial for the reaction to proceed. However, the catalyst has high activity. Under atmospheric pressure conditions, 30% of HMF can still react, and the selectivity of BHMF is 98%, as shown in Table 4 specifically:

[0064] Table 4 Preparation of BHMF by hydrogenation of HMF under different hydrogen pressures a

[0065]

[0066] a Reaction conditions: 1 mmol of HMF, 40 mg of Ni3Fe1@C-350, 10 ml of water, H2, 30 °C, 1 h. 1 - 2,5-bis(hydroxymethyl)furan (BHMF), 2 - 2,5-bis(hydroxymethyl)tetrahydrofuran (BHMTHF), 3 - 5-methylfurfuryl alcohol (MFA), 4 - 5-methylfurfural (MF).

[0067] Examples 33 - 38

[0068] The solvent, reaction temperature, and hydrogen pressure all affect the reaction rate. The higher the temperature and the greater the hydrogen pressure, the better the catalytic effect of the catalyst. However, the energy consumption during the reaction process and the requirements for equipment are also higher, which represents a significant expense in industrialization. Therefore, designing an efficient catalyst to carry out the reaction under mild conditions, especially at room temperature and atmospheric pressure, is particularly meaningful. The conditions in the aforementioned examples at 30 °C and under a hydrogen balloon were not optimal, but it could be compensated by extending the reaction time (Example 38). Considering comprehensively, the conditions of room temperature and atmospheric pressure were selected for the reaction.

[0069] According to the operation method and steps of Example 32, the catalyst and substrate were added to a pressure-resistant reaction flask. After evacuating to remove air, a hydrogen-filled balloon was inserted to achieve atmospheric pressure conditions, and the reaction was carried out under magnetic stirring (1000 r / min) at 30 °C to study the effect of reaction time on the conversion of HMF. The results showed that at room temperature and atmospheric pressure, 12% of HMF was converted in 0.5 h. As the reaction time extended, HMF continued to convert to BHMF, and most of it stably existed in the reaction system. After 4 h of reaction, the conversion rate of HMF was 99%, and the selectivity of BHMF was 96%. After 4.5 h of reaction, HMF was completely converted, and the selectivity of BHMF was 95%. Part of BHMF was converted to 2,5-bis(hydroxymethyl)tetrahydrofuran (BHMTHF). The specific results are shown in Table 5 as follows:

[0070] Table 5 Hydrogenation of HMF to Prepare BHMF at Different Times a

[0071]

[0072]

[0073] a Reaction conditions: HMF 1 mmol, Ni3Fe1@C-350 40 mg, water 10 ml, hydrogen balloon 30 °C. 1 - 2,5-bis(hydroxymethyl)furan (BHMF), 2 - 2,5-bis(hydroxymethyl)tetrahydrofuran (BHMTHF), 3 - 5-methylfurfuryl alcohol (MFA), 4 - 5-methylfurfural (MF).

Claims

1. Application of a carbon-coated nickel-iron catalyst in catalytic hydrogenation of 5-hydroxymethylfurfural to prepare 2,5-bis(hydroxymethyl)furan under normal temperature and pressure conditions, characterized in that, The catalyst is prepared by the following method: (1) Weigh glucose, ferric nitrate nonahydrate, and nickel nitrate hexahydrate and dissolve them in an isopropanol solution. Then transfer the solution into a hermetically sealed high-pressure reaction kettle. Heat it to 150 - 200 °C under magnetic stirring and maintain for 4 - 8 h. After cooling to room temperature, perform vacuum filtration, wash the filter cake, and dry it in a vacuum at 60 - 100 °C to obtain the catalyst precursor NixFey-GL, where x and y are the molar ratios of nickel and iron, and x:y = 1:0, 20:1, 5:1, 3:1, 2:1, 1:1, 0:1; The addition ratio of the glucose, ferric nitrate nonahydrate, nickel nitrate hexahydrate, and isopropanol is 2 - 7 g:0 - 6 g:0 - 5 g:50 - 300 mL; (2) Subject the catalyst precursor NixFey-GL obtained in step (1) to temperature-programmed reduction in a hydrogen atmosphere. After cooling to room temperature, passivate it with oxygen to obtain the carbon-coated nickel-iron catalyst NixFey@C-T, where T represents the reduction temperature: 250 °C, 350 °C, 450 °C; The reduction process is as follows: In a hydrogen-purged tubular furnace, heat it to 200 - 500 °C at a rate of 4 - 6 °C / min, hold for 2 - 4 h, and then naturally cool to room temperature. Then passivate it with oxygen to obtain the carbon-coated nickel-iron catalyst; The oxygen passivation process is to passivate it with a mixture of oxygen and nitrogen with an oxygen volume percentage of 1% for 2 h; The application of the catalyst includes the following steps: Add the carbon-coated nickel-iron catalyst, solvent, and 5-hydroxymethylfurfural into a pressure-resistant reaction flask according to the dosage ratio of 10 - 50 mg:10 - 15 mL:1 mmol. After evacuating to remove air, insert a balloon filled with hydrogen, and react under normal temperature and pressure conditions with magnetic stirring to obtain 2,5-bis(hydroxymethyl)furan.

2. The application according to claim 1, wherein: The addition ratio of the glucose, ferric nitrate nonahydrate, nickel nitrate hexahydrate, and isopropanol is 3 - 6 g:0 - 6 g:0 - 5 g:100 - 200 mL.

3. The application according to claim 1, characterized in that: The reduction process in step (2) is as follows: In a hydrogen-purged tubular furnace, heat it to 350 °C at a rate of 5 °C / min, hold for 2 h, and then naturally cool to room temperature. Then passivate it with oxygen to obtain the carbon-coated nickel-iron catalyst.

4. The application according to claim 1, characterized in that, The magnetic stirring speed is 1000 r / min, the reaction temperature is 30 °C, and the reaction time is 0.5 - 5 h.

5. The application according to claim 1, characterized in that, The application includes the following steps: Add the carbon-coated nickel-iron catalyst NixFey@C-T, solvent, and 5-hydroxymethylfurfural into a pressure-resistant reaction flask according to the dosage ratio of 40 mg:10 mL:1 mmol. After evacuating to remove air, insert a balloon filled with hydrogen to achieve normal pressure conditions. React at 1000 r / min and 30 °C for 4.5 h to obtain 2,5-bis(hydroxymethyl)furan.

6. The application according to claim 1, characterized in that, The solvent is one of water, methanol, ethanol, isopropanol, acetone, acetonitrile, THF, 1,4-dioxane, ethyl acetate, dichloroethane, and n-hexane.

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