Method for preparing 2-methylfuran by taking biomass-derived furfural as raw material

Abstract

The invention discloses a method for preparing 2-methylfuran by taking biomass-derived furfural as a raw material, and belongs to the technical field of furfural hydrodeoxygenation catalysis. Comprising a carrier B and an active component A loaded on the carrier B, the active component A comprises Cu and a co-catalytic metal; the co-catalytic metal comprises at least one of Ni, Co, Fe, Mo, W, Re and Nb; the carrier B is an Al-doped molecular sieve, and the molecular sieve is one of MCM-41, SBA-15, HZSM-5 and ZSM-5. And by taking a mixed solution of furfural and an alcohol hydrogen donor as a raw material, carrying out gas-phase hydrodeoxygenation reaction under the catalytic action of the bifunctional catalyst to prepare the 2-methylfuran. The process has the characteristics of low reaction temperature, low energy consumption, high safety, good selectivity, excellent catalyst stability and the like, and is suitable for green preparation of sustainable aviation fuel and high-energy-density biofuel.

Description

A method for preparing 2-methylfuran from biomass-derived furfural. Technical Field

[0001] This invention belongs to the field of furfural hydrodeoxygenation catalysis technology, specifically relating to a method for preparing 2-methylfuran from biomass-derived furfural as a raw material. Background Technology

[0002] Biomass resources are among the most promising renewable carbon sources, with furfural, a hemicellulose-derived compound, serving as an important platform compound and widely used in the preparation of fuels, solvents, and high-value-added chemicals. In particular, 2-methylfuran, a bio-based fuel with high energy density, low freezing point, and good combustion performance, is considered an important component of sustainable aviation fuel (SAF) and advanced liquid fuels. Therefore, developing a catalytic system that can efficiently convert furfural to 2-methylfuran under mild conditions is of great significance for promoting biomass energy substitution.

[0003] Currently, research on the hydrodeoxygenation of furfural to 2-methylfuran mainly focuses on metal-supported catalyst systems. For example, patent application CN111085203A reports a Cu / SiO2 catalytic system that uses a sol-gel method to prepare high-surface-area Cu / SiO2, achieving 100% furfural conversion and 98% 2-methylfuran selectivity in a hydrogen atmosphere. This process exhibits excellent catalytic performance, but Cu active sites tend to migrate at high temperatures, and the reaction still requires relatively high temperatures (≥180°C) to achieve high selectivity. On the other hand, some studies have attempted to use electrocatalytic pathways to achieve the deoxygenation conversion of furfural. For example, patent application CN118792660A discloses a method for promoting the hydrodeoxygenation reaction of furfural using a Ni-Cu / CalZIF / CP electrode under electrochemical conditions, achieving good yields at higher current densities. However, such methods involve complex equipment, and the electrochemical system is highly sensitive to current disturbances, making it difficult to scale up for application in continuous gas-phase flow conditions.

[0004] Regarding the type of support and metal, existing technologies have explored various approaches. For example, patent application CN113457675A reports a system in which Cu, Co, and Ni metals are supported on SiO2, achieving a 2-methylfuran selectivity of over 90% under gas-phase conditions. However, the catalyst preparation involves low-temperature reduction, dialysis, and precise pH control, making the process complex and unsuitable for large-scale applications. Patent application CN103007942A uses a silicon-aluminum composite oxide as a support, leveraging the bifunctional properties of Cu's hydrogenation ability and the acid sites on the support to achieve high low-temperature activity. However, this system typically requires 180°C to reach optimal performance, indicating that the reaction temperature is still relatively high. Another example is patent application CN110180550A, which reports a Cu-SiO2 catalyst modified with rare earth elements (La, Ce, Y, etc.) that achieves good selectivity and stability, but the reaction temperature also needs to be 180°C or higher to reach the ideal conversion level.

[0005] The existing catalytic systems for the production of 2-methylfuran from furfural generally have the following shortcomings: (1) Most systems require a high reaction temperature of 180-250°C, resulting in high energy consumption and high equipment load; (2) Single metal active sites are difficult to meet the requirements of furfural hydrogenation and intermediate dehydration, resulting in an increase in side reactions; (3) Some catalysts have complex preparation processes, making it difficult to achieve long-term operation in industrial continuous flow reactors; (4) The catalysts are not stable enough and are prone to sintering and deactivation under high temperature operation.

[0006] Therefore, there is an urgent need to develop a furfural hydrodeoxygenation catalytic system that can achieve high conversion and high selectivity under low temperature conditions (≤180°C) and can operate stably in a continuous flow fixed bed reactor to meet the demand for efficient and low-energy-consumption processes in the field of green fuels. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing 2-methylfuran from biomass-derived furfural as a raw material, thereby solving the problems in the prior art.

[0008] The objective of this invention can be achieved through the following technical solution: a bifunctional catalyst, comprising: a support B and an active component A supported on the support B; the active component A comprises: Cu and a co-catalytic metal; the co-catalytic metal comprises at least one of Ni, Co, Fe, Mo, W, Re, and Nb; the support B is an Al-doped molecular sieve.

[0009] Furthermore, the molar ratio of Al to Si in the carrier B is 0.01 to 0.05:1.

[0010] Furthermore, the molecular sieve is one of MCM-41, SBA-15, HZSM-5, and ZSM-5.

[0011] Furthermore, in the bifunctional catalyst, the Cu loading is 1-5 wt%, and the co-catalytic metal loading is 0.5-5 wt%.

[0012] The preparation method of the above-mentioned bifunctional catalyst includes the following steps: dissolving molecular sieve powder in a solvent, adding aluminum chloride, stirring and evaporating the solvent, and calcining to obtain support B; dissolving Cu compound and co-catalyst metal compound in deionized water to form a metal mixed precursor solution; immersing support B in the metal mixed precursor solution, and obtaining the bifunctional catalyst after aging, drying and calcination.

[0013] Furthermore, the compound of Cu is copper nitrate; the compound of the co-catalyst metal is any one or more of niobium pentachloride, ammonium perrhenate, sodium tungstate, and ferric nitrate.

[0014] The above-mentioned bifunctional catalyst is used in the preparation of 2-methylfuran from biomass-derived furfural.

[0015] A method for preparing 2-methylfuran from biomass-derived furfural as a raw material includes: using a mixed solution of furfural and an alcohol hydrogen donor as a raw material, and carrying out a gas-phase hydrogenation and deoxygenation reaction under the catalysis of the above-mentioned bifunctional catalyst to obtain 2-methylfuran.

[0016] Furthermore, the reaction temperature of the gas-phase hydrogenation deoxygenation reaction is 140–180°C, and the pressure is atmospheric pressure to 3 MPa.

[0017] Furthermore, in the mixed solution of furfural and alcohol hydrogen donor, the concentration of furfural is 5 wt%, and the alcohol hydrogen donor is methanol, ethanol, or isopropanol.

[0018] The beneficial effects of the present invention are as follows: 1. The present invention adopts a bifunctional A / B catalyst system, wherein the active metal component A is responsible for the initial steps of hydrogenation of furfural carbonyl and CO bond breaking, and the support B provides Brønsted acid or Lewis acid centers to promote the dehydration conversion of intermediates, so that hydrogenation and dehydration can occur continuously at the same catalytic interface, thereby significantly improving the low-temperature reaction efficiency and 2-methylfuran selectivity.

[0019] 2. Under the action of A / B bifunctional catalysts, furfural undergoes hydrogenation, dehydration, and mild deoxygenation processes to finally generate 2-methylfuran. The reaction temperature can completely convert furfural at 140-170℃. Under continuous flow conditions, the selectivity of 2-methylfuran can reach 95-100%. It has good stability over long-term operation, and its performance does not show significant degradation within 500 hours of continuous operation.

[0020] 3. The core research system of this invention uses Al-doped MCM-41 as a support; the catalyst (5Cu-3Nb / Al-MCM-41) with MCM-41 as the support achieved 99.6% selectivity for 2-methylfuran (2-MF) at 160°C and atmospheric pressure, which fully verifies the effectiveness and superiority of Al-MCM-41 as a support in this invention.

[0021] 4. The bifunctional catalyst in this invention includes 5Cu-3Nb / Al-MCM-41. Comparison experiments with other Cu and Nb loading ratios show that when the Cu loading is too low (3wt%), the hydrogenation capacity is insufficient, and when it is too high (10wt%), it leads to particle aggregation and decreased selectivity. This proves that the loading range is the result of systematic optimization and is the key to achieving high activity and high selectivity. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 is a SEM image of the 5Cu-3Nb / Al-MCM-41 catalyst in Example 1 of the present invention; Figure 2 is a TEM image of the 5Cu-3Nb / Al-MCM-41 catalyst in Example 1 of the present invention; Figure 3 is a DRIFTS image of the 5Cu-3Nb / Al-MCM-41 catalyst in Example 1 of the present invention under different temperature conditions; Figure 4 is a graph showing the furfural conversion rate and 2-MF yield of the 5Cu-3Nb / Al-MCM-41 catalyst after cyclic reaction in Example 1 of the present invention, as well as a comparison of XRD and XPS before and after the reaction. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] A method for preparing 2-methylfuran from biomass-derived furfural as a raw material includes the following steps: using a mixed solution of furfural and an alcohol hydrogen donor as a raw material, a gas-phase hydrodeoxygenation reaction is carried out under the catalysis of a bifunctional catalyst to obtain 2-methylfuran (2-MF); specifically, the mixture is continuously fed into a fixed-bed reactor packed with a bifunctional catalyst, and a gas-phase hydrodeoxygenation reaction is carried out at 140–180 °C and atmospheric pressure up to 3 MPa to obtain 2-methylfuran; wherein: furfural is obtained from the cracking of biomass hemicellulose or pentose platform compounds and is soluble in alcohol hydrogen donor solvents such as methanol, ethanol, and isopropanol.

[0026] The gas-phase hydrodeoxygenation reaction was carried out in a fixed-bed continuous flow reactor, with the reaction temperature maintained at 140–180°C, hydrogen pressure ranging from atmospheric pressure to 3 MPa, and liquid feed space velocity at 0.2–1.0 h⁻¹. -1 The hydrogen flow rate is 5–20 mL / min.

[0027] In a mixed solution of furfural and alcohol hydrogen donors, the concentration of furfural is 5 wt%, and the alcohol hydrogen donors are methanol, ethanol or isopropanol.

[0028] The bifunctional catalyst comprises: a support B and an active component A mounted on the support B; the active component A comprises: Cu and a co-catalytic metal, wherein the Cu loading in the bifunctional catalyst is 1–5 wt%, and the co-catalytic metal loading is 0.5–5 wt%; the support B is an Al-doped molecular sieve, the Al to Si molar ratio in the support B is 0.01–0.05:1, and the specific surface area of ​​the support B is 600–1200 m². 2 / g, pore size 2-4nm; co-catalyst metal includes at least one of Ni, Co, Fe, Mo, W, Re, and Nb; molecular sieve is one of MCM-41, SBA-15, HZSM-5, and ZSM-5.

[0029] The preparation process of the bifunctional catalyst includes: S1, dissolving molecular sieve powder in a solvent, adding aluminum chloride to adjust the Al / Si molar ratio to 0.01-0.05:1, stirring and evaporating the solvent, and calcining to obtain Al-doped molecular sieve (support B); S2, dissolving Cu compounds (such as copper nitrate) and co-catalyst metal compounds (such as niobium pentachloride, ammonium perrhenate, sodium tungstate, and ferric nitrate) in deionized water to form a metal mixed precursor solution; S3, immersing support B in the metal mixed precursor solution, and obtaining the bifunctional catalyst after aging, drying, and calcination.

[0030] The technical solution of the present invention will be described below through the following embodiments. In these embodiments, the sources of the relevant raw materials are as follows: furfural (FAL, 99% purity), niobium pentachloride (NbCl5, 99% purity), aluminum trichloride (AlCl3, 99% purity), copper nitrate trihydrate (Cu(NO3)2·3H2O, 99% purity), γ-valerolactone (98%), ammonium perrhenate (NH4ReO4, 98%), cyclopentanone (98%), sodium tungstate (Na2O4W·2H2O, 98%), and ferric nitrate (Fe(NO3)3, 99%) were all purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. The all-silica MCM-41 and SBA-15 mesoporous molecular sieve supports were both provided by Nankai University Catalyst Co., Ltd.

[0031] In this embodiment, the furfural conversion rate and product yield were measured as follows: the liquid sample was diluted tenfold and identified by gas chromatography-mass spectrometry (GC-MS, Agilent 8860-5977C), and quantitative analysis was performed using a gas chromatograph (GC-FID, Shimadzu GC-2014C) equipped with an HP-5 capillary column (30 m × 0.32 mm × 0.25 μm). Gaseous products were analyzed using an Agilent 8890 gas chromatograph with a thermal conductivity detector (TCD) and three packed columns (3 ft HayeSep Q, 6 ft HayeSep Q, and 6 ft MolSieve 5A).

[0032] Example 1: Weigh an appropriate amount of MCM-41 powder and add it to anhydrous ethanol. Add aluminum chloride to adjust the Al / Si molar ratio to 0.02:1. Stir for 4 hours, then evaporate the solvent at 80°C and calcine at 550°C for 5 hours to obtain Al-MCM-41 support.

[0033] A 5% (w / w) copper nitrate and a 3% (w / w) niobium pentachloride were dissolved in deionized water to form a metal-mixed precursor solution. Al-MCM-41 was added to the above solution for equal-volume impregnation, aged for 12 hours, dried at 110°C, and calcined at 500°C for 4 hours in air to obtain the 5Cu-3Nb / Al-MCM-41 catalyst; in this catalyst, the Cu loading was 5 wt% and the Nb loading was 3 wt%.

[0034] The SEM and TEM images of the 5Cu-3Nb / Al-MCM-41 catalyst are shown in Figures 1 and 2, respectively, revealing its morphology, elemental distribution, and structural stability. First, the SEM images show that the 5Cu-3Nb / Al-MCM-41 catalyst (Figure 1) has fine, uniformly distributed nanoparticles without significant aggregation. This indicates that Al doping effectively inhibits the sintering of Cu and Nb species, playing a structural modulation role and enhancing the metal-support interaction. Second, the TEM image (Figure 2) confirms that the catalyst retains the ordered mesoporous channel structure of MCM-41, with clear and intact channels showing no signs of collapse. This directly relates to the catalyst's high activity and long-term stability in the furfural hydrodeoxygenation reaction (e.g., no deactivation in the 500-hour test). In summary, both SEM and TEM images demonstrate that the 5Cu-3Nb / Al-MCM-41 catalyst possesses excellent mesoporous structural integrity and metal dispersion, with Al doping being a key optimization factor, providing a structural basis for low-temperature, high-efficiency conversion.

[0035] Figure 3 shows the changes in surface adsorbed species and reaction intermediates of the 5Cu-3Nb / Al-MCM-41 catalyst at different temperatures. At low temperatures (≤160°C), a weak C=O stretching vibration band appears at 1680 cm⁻¹, corresponding to the adsorption of furfural carbonyl groups, but its low intensity indicates limited adsorption of furfural on the catalyst surface and weak reactivity. When the temperature rises above 160°C, the intensity of the C=O band at 1680 cm⁻¹ significantly increases, indicating a substantial increase in furfural adsorption. Simultaneously, an OH bending vibration band appears near 1360 cm⁻¹, and a CO stretching vibration band appears in the 1030-1085 cm⁻¹ region; these characteristics correspond to the formation of the intermediate furfuryl alcohol. The catalytic significance of these changes is that the DRIFTS results verify the tandem reaction mechanism of FAL to 2-methylfuran (2-MF), i.e., FAL is first reduced to furfuryl alcohol at Lewis acid sites, and then dehydrated at metal-acid co-existing sites to generate 2-methylfuran. The DRIFTS diagram mainly reveals the regulatory effect of temperature on the reaction pathway, confirming that the superiority of 5Cu-3Nb / Al-MCM-41 stems from its optimized interfacial electronic structure and acid site distribution.

[0036] The prepared catalyst particles were controlled to be 40-60 mesh and loaded into a stainless steel fixed-bed reactor (1.0 g loading). Hydrogen gas was introduced at a rate of 20 mL / min, and the reactor was pretreated at 300 °C for 1 h before being cooled to the target reaction temperature.

[0037] Using a 5wt% furfural-methanol solution as raw material, the solution was metered at 0.5h... -1 The liquid hourly space velocity (LHSV) was continuously fed into the reactor at atmospheric pressure, with a hydrogen flow rate of 10 mL / min.

[0038] The reaction data for Cu-Nb / Al-MCM-41 are shown in Table 1 below: Table 1 Reaction data for Cu-Nb / Al-MCM-41 As shown in Table 1, within the temperature range of 120°C to 200°C, the furfural conversion rate approached or reached 100%, while the yield of 2-methylfuran exhibited a distinct volcanic distribution, peaking at 99.6% at 160°C. Furthermore, the yields of byproducts such as furfuryl alcohol, cyclopentanone, and γ-valerol were extremely low (totaling only 0.4%). This result highlights 160°C as the optimal reaction temperature, at which the catalyst achieved near-complete selective conversion, avoiding the increase in byproducts caused by excessive hydrogenation or ring-opening reactions at higher temperatures (such as above 170°C) (e.g., at 170°C, the 2-MF yield decreased to 74.79%, while other byproducts increased to 17.85%). In summary, this data strengthens the patent value of the catalyst and demonstrates its potential for low-temperature, high-efficiency, and sustainable application in biomass conversion.

[0039] In Example 2, a certain amount of Al-MCM-41 (prepared in Example 1) was weighed and dispersed in anhydrous ethanol. Copper nitrate and ammonium perrhenate were dissolved in deionized water and mixed at a ratio of 5 wt% Cu and 2 wt% Re to prepare a metal precursor solution. This mixed solution was impregnated into a support under stirring and aged at room temperature for 12 h. Subsequently, it was dried at 100 °C for 10 h and then calcined at 500 °C for 4 h to obtain the Cu-Re / Al-MCM-41 catalyst.

[0040] 1 g of catalyst was loaded into a fixed-bed reactor and reduced at 300 °C for 1 h with hydrogen gas at a flow rate of 10 mL / min. A 5 wt% furfural-isopropanol solution was prepared as the feedstock. The solution was then reduced at 0.5 h. -1 The liquid hourly gas (LIB) is pumped into the fixed-bed reactor at a reaction temperature of 140–160 °C, a hydrogen flow rate of 10 mL / min, and a pressure of atmospheric pressure.

[0041] The reaction data of Cu-Re / Al-MCM-41 are shown in Table 2 below: Table 2 Reaction data of Cu-Re / Al-MCM-41 As can be seen from Table 2, a conversion rate of nearly 100% and a selectivity of over 99% can be obtained at a low temperature of 140–160℃.

[0042] In Example 3, Al-MCM-41 (prepared in Example 1) was dispersed in anhydrous ethanol. Copper nitrate and sodium tungstate were weighed and dissolved in water, and a mixed solution was prepared according to a ratio of 5 wt% Cu and 2 wt% Re. The solution was added dropwise to the support using an equal-volume impregnation method, aged for 10 h, dried at 90 °C, and then calcined at 450 °C for 5 h to obtain the Cu–W / Al-MCM-41 catalyst.

[0043] 1 g of catalyst was loaded, and reduction was carried out at 280 °C for 1 h with hydrogen gas at a flow rate of 10 mL / min. A 5 wt% furfural-isopropanol solution was then used at atmospheric pressure with an LHSV of 0.5 h. -1 The hydrogen flow rate was 15 mL / min, and the reaction temperature was 140–170 °C.

[0044] The reaction data for Cu-W / Al-MCM-41 are shown in Table 3 below: Table 3 Reaction data for Cu-W / Al-MCM-41 As can be seen from Table 3, a furfural conversion rate of nearly 100% can be obtained at a low temperature of 140–170℃, and the 2-MF yield shows a clear volcano-shaped distribution, reaching 88.73% at 160℃.

[0045] In Example 4, a mixed solution of copper nitrate and ferric nitrate in a mass ratio of 5:2 was prepared by impregnation and then impregnated with Al-MCM-41 (prepared in Example 1). After drying, the solution was calcined at 500°C for 4 hours to obtain a Cu–Fe / Al-MCM-41 catalyst. In this catalyst, the loading of Cu was 5 wt% and the loading of Fe was 3 wt%.

[0046] Reduction was carried out at 300℃ and 15 mL / min of hydrogen for 1 h. A 5 wt% furfural-isopropanol solution was used at atmospheric pressure with an LHSV of 0.5 h. -1 The hydrogen flow rate was 15 mL / min, and the reaction temperature was 140–170 °C.

[0047] The reaction data for Cu–Fe / Al-MCM-41 are shown in Table 4 below: Table 4 Reaction data for Cu–Fe / Al-MCM-41 As shown in Table 4, within the temperature range of 140°C to 170°C, the furfural conversion steadily increased from 88.62% to 99.1%, indicating that the catalytic activity increased with increasing temperature. However, the yield of the target product, 2-methylfuran, exhibited a typical "volcano-shaped" curve, peaking at 82.47% at 160°C and then decreasing to 79.34% at 170°C. This phenomenon suggests that 160°C remains the optimal reaction temperature; above this temperature, excessive hydrogenation or side reactions (such as ring-opening reactions) intensify.

[0048] In Example 5, SBA-15 mesoporous molecular sieve was weighed and pre-dried at 120°C for 6 hours to remove moisture before use. Copper nitrate and niobium pentachloride were dissolved in deionized water to prepare a mixed precursor solution with a Cu:Nb loading ratio of 5:3. SBA-15 was added to the above solution under an equal volume impregnation condition, mixed thoroughly, and aged for 12 hours. The impregnated solid was dried at 100°C for 10 hours, and then calcined at 500°C for 4 hours in air to obtain the Cu–Nb / SBA-15 catalyst. After calcination, the catalyst was pale blue, and the metal species were uniformly dispersed.

[0049] 1.0 g of catalyst was loaded into a fixed-bed reactor and reduced for 1 h at a hydrogen flow rate of 20 mL / min and a temperature of 300°C. The catalyst was then cooled to the reaction temperature for later use.

[0050] A 5 wt% furfural methanol solution was introduced into the reactor at an LHSV of 0.5 h⁻¹, with a hydrogen flow rate of 10 mL / min. The reaction temperature was controlled within the range of 140–180°C, and the operation was carried out at atmospheric pressure.

[0051] The reaction data for Cu-Nb / SBA-15 are shown in Table 5: Table 5 Reaction data for Cu-Nb / SBA-15 As shown in Table 5, the conversion rate of furfural steadily increased from 92.35% to 100% within the temperature range of 140°C to 170°C, demonstrating good reactivity. The yield of the target product, 2-methylfuran, continued to increase with increasing temperature, rising from 61.28% at 140°C to 91.32% at 170°C, without showing a decreasing trend within the test range. This indicates that 170°C may not have reached the upper limit of its optimal reaction temperature. Meanwhile, the yield of the byproduct furfuryl alcohol decreased from 5.37% to 1.75%, and the yield of cyclopentanone decreased significantly from 33.35% to 6.93%. This change clearly shows that increasing the temperature effectively promoted the further dehydration step of the intermediate furfuryl alcohol and significantly suppressed the side reaction pathway of furfural or the intermediate undergoing the Piancatelli rearrangement to generate cyclopentanone.

[0052] Example 6 used the Cu-Nb / Al-MCM-41 catalyst prepared in Example 1 as the subject of investigation. The catalyst was pressed into tablets, sieved to obtain 40-60 mesh particles, and then packed into a stainless steel fixed-bed microreactor with a loading of 1.0 g, secured at both ends with quartz wool. After loading, the catalyst underwent reduction pretreatment under a hydrogen atmosphere: hydrogen gas was introduced (30 mL / min), the temperature was raised to 300 °C, held for 2 h, and then cooled to the reaction temperature of 160 °C.

[0053] The reaction proceeds were a 5 wt% furfural-isopropanol solution, with isopropanol acting as both the solvent and hydrogen donor. The reaction was carried out using a high-pressure constant-flow metering pump at 0.5 h⁻¹.-1 The feed was continuously introduced at a liquid hourly space velocity (LHSV) and the reaction pressure was atmospheric pressure. If hydrogen was introduced, an additional 10 mL / min of hydrogen was introduced during the reaction. The reaction temperature was fixed at 160 °C, and the reaction was continuously run for 500 h under the above conditions. After condensation, liquid phase samples were collected online or offline, and the furfural conversion rate and selectivity of each product were analyzed periodically by gas chromatography-FID (GC-FID), with samples taken every 50 h.

[0054] The test results are shown in Table 6: Table 6 Stability test results of Cu-Nb / Al-MCM-41 after 500h continuous operation at 160℃ As shown in Table 6, during the 500-hour continuous operation, the furfural conversion rate remained at 100%, and the 2-methylfuran selectivity remained at approximately 99.0%, with only minor fluctuations and a small amount of byproducts (Figure 4a). No obvious deactivation trend was observed. Combined with XRD analysis (Figure 4b), the XRD patterns of the catalyst after 200 and 500 hours of continuous reaction showed no significant difference, fully demonstrating its excellent post-reaction structural stability: Firstly, the crystal structure of the catalyst did not change significantly after the reaction. Except for the characteristic diffraction peaks of quartz sand (20.8° and 26.7°), no other significant impurity peaks appeared in the diffraction pattern. This indicates that the catalyst did not undergo unexpected chemical changes during the long-term reaction, maintaining the stable purity of the main phase. Secondly, after 500 hours of reaction, the catalyst still clearly showed the characteristic diffraction peaks attributed to CuO (JCPDS 00-048-1548). The peaks at 35.5°, 38.6°, and 48.7° correspond to the (1 1 –1), (1 11), and (2 0 –2) crystal planes of CuO, respectively. These peaks did not show significant broadening or weakening, indicating that the CuO grains did not undergo significant agglomeration or growth. This further confirms the excellent structural stability of the catalyst during long-term reactions, while also possessing superior anti-sintering ability, ensuring that its structure remains intact even after prolonged reaction time.

[0055] The Cu–Nb–Al catalyst demonstrated excellent structural stability and anti-sintering ability while maintaining activity and selectivity. After 500 hours of reaction, the peak shape and position in the Si 2p region remained basically stable (c-f) in Figure 4), and the chemical state of the silicon material did not change significantly—indicating that the support structure has good stability during the reaction. Meanwhile, the relative intensities of the fitted peaks in the C1s spectrum showed only minor overall changes, indicating that no significant carbon deposition occurred even after 200 hours of continuous operation. XPS analysis showed that the catalyst maintained stable Cu content throughout long-term operation. + / Cu 2+The redox balance and strong acid-metal synergistic effect demonstrate the potential for continuous industrial-scale production of indene-based biofuels. Furthermore, the catalyst, when removed after shutdown, showed no obvious sintering or agglomeration, indicating good long-term continuous operation stability and suitability for the industrial-scale continuous production of bio-based 2-methylfuran.

[0056] In summary, this invention provides a method for the efficient preparation of 2-methylfuran from biomass-derived furfural under low-temperature conditions. By constructing a bifunctional catalyst system with hydrogenation activity and acid-co-synergistic characteristics, furfural can undergo hydrodeoxygenation conversion under mild conditions of 140–180°C, successfully achieving continuous flow stable operation in a fixed-bed reactor. The combination of metal component A and support B used in this invention has broad applicability; A can be a composite material of Cu and various co-catalyst metals, and B can be an aluminum-doped mesoporous molecular sieve structure. This allows the catalytic system to possess both hydrogenation capability and moderate acidity and interfacial synergistic properties, thereby ensuring the effective conversion of key intermediates during the reaction process.

[0057] Through comparative examples with different catalyst formulations and reaction conditions, the method of the present invention demonstrates excellent performance in terms of furfural conversion rate, target product selectivity, and catalyst stability. High conversion rate and high selectivity can be achieved even at low temperatures, and the method remains stable even after hundreds of hours of continuous operation. The method of the present invention features a mild process, tunable catalyst structure, and suitability for continuous production, meeting the needs of sustainable aviation fuel and high-energy-density biofuel production, and has promising prospects for industrial application.

[0058] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0059] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A bifunctional catalyst, characterized in that, include: Carrier B and active component A loaded on carrier B; The active component A includes Cu and a co-catalytic metal; the co-catalytic metal includes at least one of Ni, Co, Fe, Mo, W, Re, and Nb; the support B is an Al-doped molecular sieve.

2. The bifunctional catalyst according to claim 1, characterized in that, The molar ratio of Al to Si in the carrier B is 0.01 to 0.05:

1.

3. The bifunctional catalyst according to claim 1, characterized in that, The molecular sieve is one of MCM-41, SBA-15, HZSM-5, and ZSM-5.

4. A bifunctional catalyst according to claim 1, characterized in that, In the bifunctional catalyst, the Cu loading is 1-5 wt%, and the co-catalytic metal loading is 0.5-5 wt%.

5. The method for preparing the bifunctional catalyst according to any one of claims 1-4, characterized in that, Includes the following steps: Molecular sieve powder was dissolved in a solvent, aluminum chloride was added, the solvent was evaporated after stirring, and the mixture was calcined to obtain support B. Cu compounds and co-catalyst metal compounds were dissolved in deionized water to form a metal mixed precursor solution. Support B was immersed in the metal mixed precursor solution, and after aging, drying, and calcination, a bifunctional catalyst was obtained.

6. The method for preparing the bifunctional catalyst according to claim 5, characterized in that, The compound of Cu is copper nitrate; the compound of the co-catalyst metal is any one or more of niobium pentachloride, ammonium perrhenate, sodium tungstate, and ferric nitrate.

7. The use of the bifunctional catalyst according to any one of claims 1-4 in the preparation of 2-methylfuran from biomass-derived furfural.

8. A method for preparing 2-methylfuran from biomass-derived furfural, characterized in that, include: Using a mixed solution of furfural and an alcohol hydrogen donor as raw material, 2-methylfuran is prepared by gas-phase hydrogenation and deoxygenation under the catalysis of the bifunctional catalyst described in any one of claims 1-4.

9. The method for preparing 2-methylfuran from biomass-derived furfural according to claim 8, characterized in that, The gas-phase hydrogenation deoxygenation reaction is carried out at a temperature of 140–180°C and a pressure of atmospheric pressure to 3 MPa.

10. A method for preparing 2-methylfuran from biomass-derived furfural as a raw material according to claim 8, characterized in that, In the mixed solution of furfural and alcohol hydrogen donor, the concentration of furfural is 5 wt%, and the alcohol hydrogen donor is methanol, ethanol or isopropanol.

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