Bimetal-based catalyst for synthesizing 2-methoxy-4-methylphenol through vanillin hydrogenation as well as preparation method and application of bimetal-based catalyst

Abstract

The invention belongs to the technical field of synthesis of 2-methoxy-4-methylphenol, and particularly discloses a bimetallic-based catalyst for synthesizing 2-methoxy-4-methylphenol through vanillin hydrogenation as well as a preparation method and application of the bimetallic-based catalyst. Molybdenum carbide (alpha-MoC) is adopted as a carrier, cobalt and iron are loaded by an impregnation method to obtain the bimetallic-based catalyst, and the bimetallic catalyst can be used for obtaining a 2-methoxy-4-methylphenol product with high added value at high yield by taking vanillin as a raw material under mild reaction conditions. The method is short in synthesis process, low in cost, economical, effective, high in universality, environment-friendly, free of corrosion to equipment and high in product quality. The bimetallic-based catalyst not only has excellent catalytic hydrodeoxygenation performance on vanillin, but also has relatively high selectivity on 2-methoxy-4-methylphenol, and in addition, the bimetallic-based catalyst also has excellent cycle stability, wide market prospect and remarkable economic potential.

Description

Technical Field

[0001] The invention relates to the synthesis of 2-methoxy-4-methylphenol, in particular to a bimetallic catalyst for synthesizing 2-methoxy-4-methylphenol by hydrogenation of vanillin, a preparation method and application thereof, and belongs to the technical field of synthesis of 2-methoxy-4-methylphenol. Background Art

[0002] Energy is the material basis for the survival and development of human society. With the development of society, the large-scale consumption of non-renewable energy has led to environmental pollution and energy crisis. Obtaining high-value-added chemicals from biomass is an effective way to solve the current energy and environmental crisis, with significant economic and ecological benefits. However, the high viscosity, low calorific value and strong corrosiveness of bio-oil derived from lignin limit its wide application in industry. Catalytic hydrodeoxygenation is an effective way to improve the quality of lignin-derived bio-oil. Vanillin has a variety of different CO / C=O bonds (Caryl−OH, Caryl−OCH3, Calkyl−OAr and C=O) and is a typical lignin-derived platform compound. A series of high-value-added chemicals can be prepared by hydrodeoxygenation of vanillin, such as 2-methoxy-4-methylphenol, benzene, phenol, etc. Among them, 2-methoxy-4-methylphenol is a high-value-added biofuel and an important fragrance precursor, which can be used to produce fragrances and drugs with antibacterial and insecticidal properties. The preparation of 2-methoxy-4-methylphenol by hydrodeoxygenation of vanillin is challenging because the reaction process involves aromatic ring hydrogenation, C=O bond hydrogenation, and selective hydrogenolysis of oxygen-containing functional groups.

[0003] In recent years, some researchers have developed precious metal catalysts (such as Au, Pt, Pd and Ru) for the hydrodeoxygenation of vanillin to prepare 2-methoxy-4-methylphenol. Precious metal catalysts show excellent catalytic activity, but their high cost and scarce resources greatly limit their large-scale application in industry. Therefore, the search for a cheap, highly active, highly selective and highly stable catalyst for the catalytic hydrodeoxygenation of vanillin to prepare 2-methoxy-4-methylphenol has attracted widespread attention. Although the single metal Co-based catalyst is low in cost, the hydrodeoxygenation activity is not ideal and the selectivity needs to be improved. In addition, the stability of the single metal Co-based catalyst has always been a problem to be solved.

[0004] Yuan Bing et al. (CN115160111A) from Qingdao University of Science and Technology disclosed a SLSre-Pd catalyst using sodium lignin sulfonate in a one-pot reduction in an aqueous phase for the hydrodeoxygenation of vanillin to produce 2-methoxy-4-methylphenol. Although the yield of 2-methoxy-4-methylphenol was >95.0%, the preparation cost of the catalyst was high and the catalyst cycle stability was not ideal. Wu Jun et al. (CN114656337A) from Shaanxi University of Science and Technology disclosed a catalyst (Co@NHCS) loaded with metal Co nanoparticles on hollow carbon spheres and used it in the hydrodeoxygenation of vanillin to produce 2-methoxy-4-methylphenol. Although the catalyst cost is cheaper than that of precious metal catalysts, the selectivity and yield of 2-methoxy-4-methylphenol are relatively low. Summary of the invention

[0005] In view of the problems in the prior art of preparing 2-methoxy-4-methylphenol by catalytic hydrogenation and deoxygenation of vanillin, such as high preparation cost and unsatisfactory catalytic stability, the present invention provides a bimetallic catalyst for hydrogenating vanillin to synthesize 2-methoxy-4-methylphenol, and a preparation method and application thereof. By adopting a homemade molybdenum carbide (α-MoC)-loaded cobalt-iron bimetallic catalyst (Co-Fe / α-MoC), vanillin can be hydrogenated and catalyzed under mild conditions, and high-purity 2-methoxy-4-methylphenol can be prepared at a high reaction rate and selectivity. In addition, the catalyst has excellent cyclic stability, thereby significantly reducing production costs and having significant economic prospects.

[0006] In order to achieve the above technical objectives, the technical solutions adopted by the present invention are as follows: According to a first embodiment of the present invention, a bimetallic catalyst for hydrogenating vanillin to synthesize 2-methoxy-4-methylphenol is provided: the bimetallic catalyst comprises a carrier and a bimetallic active component supported on the carrier. The carrier is molybdenum carbide (α-MoC), and the bimetallic active component is cobalt and iron.

[0007] Preferably, in the bimetallic catalyst, the loading amount of cobalt is 7-10% of the mass of molybdenum carbide, preferably 7.5-9%. The loading amount of iron is 3-6% of the mass of molybdenum carbide, preferably 4-5%.

[0008] According to a second embodiment of the present invention, there is provided a method for preparing a bimetallic catalyst for catalytic hydrogenation of vanillin to synthesize 2-methoxy-4-methylphenol or a method for preparing the bimetallic catalyst as described in the first embodiment, wherein the bimetallic catalyst is prepared by the following method: 1) Dissolving a soluble cobalt salt and a soluble iron salt in water to obtain an active component precursor solution.

[0009] 2) Adding molybdenum carbide (α-MoC) into the active component precursor solution for impregnation treatment to obtain a catalyst precursor, 3) The catalyst precursor is first calcined in an inert atmosphere and a reducing atmosphere in sequence, and then cooled in an inert atmosphere to obtain the target bimetallic catalyst.

[0010] Preferably, the soluble cobalt salt includes one or more of cobalt chloride, cobalt nitrate, cobalt sulfate and cobalt acetate.

[0011] Preferably, the soluble iron salt includes one or more of ferric chloride, ferrous chloride, ferric nitrate, ferrous nitrate, ferric sulfate and ferrous sulfate.

[0012] It should be noted that the cobalt chloride, cobalt nitrate, cobalt sulfate, cobalt acetate, ferric chloride, ferrous chloride, ferric nitrate, ferrous nitrate, ferric sulfate, and ferrous sulfate should also include their hydrates. For example, cobalt chloride should include anhydrous cobalt dichloride and cobalt dichloride hexahydrate.

[0013] Preferably, the inert atmosphere is a nitrogen atmosphere and / or a helium atmosphere and / or an argon atmosphere. The catalyst precursor is calcined in an inert atmosphere at a temperature of 300 to 600° C., preferably 400 to 500° C. The calcination time is 0.5 to 5 hours, preferably 1 to 4 hours.

[0014] Preferably, the reducing atmosphere is a hydrogen atmosphere and / or a carbon monoxide atmosphere. The catalyst precursor is calcined in a reducing atmosphere at a temperature of 300-600° C., preferably 400-500° C. The calcination time is 0.5-5 h, preferably 1-4 h.

[0015] According to a third embodiment of the present invention, a method for synthesizing 2-methoxy-4-methylphenol is provided, which specifically comprises: first dissolving vanillin in a solvent, then adding the bimetallic catalyst as described in the first embodiment or adding the bimetallic catalyst prepared by the method described in the second embodiment, then performing a thermal reaction under a reducing atmosphere to obtain a crude product, and finally purifying the crude product to obtain 2-methoxy-4-methylphenol.

[0016] Preferably, the amount of the bimetallic catalyst added is 3-15% of the mass of vanillin, preferably 5-12%.

[0017] Preferably, the solvent is an organic solvent, preferably 1,4-dioxane (other organic solvents (such as isopropanol, glycerol, ethanol, etc.) can also be used in the present invention, but these organic solvents may undergo condensation reactions with reactants and products during the reaction). Preferably, the amount of the solvent used is 3 to 30 times the mass of vanillin.

[0018] Preferably, the temperature of the thermal reaction is 80-120° C., preferably 90-110° C. The time of the thermal reaction is 3-12 hours, preferably 5-10 hours.

[0019] Preferably, during the thermal reaction, the pressure of the reducing atmosphere is 0.5-5 MPa, preferably 1-3 MPa; preferably, the reducing atmosphere is a hydrogen atmosphere.

[0020] In the present invention, an innovative concept is proposed to use a bimetallic catalyst with Co-Fe supported on molybdenum carbide (α-MoC) as a carrier for the hydrodeoxygenation of vanillin to prepare 2-methoxy-4-methylphenol; the synergistic effect between the carrier and the Co-Fe bimetallic is used to improve the hydrodeoxygenation activity and catalyst stability of the catalyst, thereby achieving the use of relatively cheap and abundant vanillin as a raw material, and being able to prepare high-value-added 2-methoxy-4-methylphenol products with high conversion rate, high selectivity and high stability under mild conditions, which has the advantages of low cost, economic effectiveness, strong universality, environmental friendliness, and no corrosion to equipment.

[0021] In the present invention, molybdenum carbide (α-MoC) has excellent thermal stability and corrosion resistance, and can establish strong electronic interactions with metals such as Co and Fe. The strong carrier interaction of α-MoC promotes the interaction between the Co-Fe active component and the carrier surface, thereby preventing the loss of active components during the reaction, thereby improving the stability of the catalyst. Therefore, selectively using α-MoC as a catalyst carrier in the hydrodeoxygenation reaction in combination with Co and Fe as active components can achieve excellent catalytic stability.

[0022] In the present invention, in the bimetallic catalyst of cobalt-iron supported on molybdenum carbide (Co-Fe / α-MoC), in a preferred embodiment, the loading amount of cobalt is 7-10% (preferably 7.5-9%) of the mass of molybdenum carbide, and the loading amount of iron is 3-6% (preferably 4-5%) of the mass of molybdenum carbide. The introduction of the second metal in the bimetallic can well regulate the morphology and electronic structure of the main metal, thereby improving the catalytic performance of the bimetallic catalyst. Metal Fe is an oxophilic metal, and the introduction of an appropriate amount of Fe is conducive to promoting the dehydroxylation process in the hydrodeoxygenation reaction of vanillin. And the construction of a bimetallic Co-Fe bimetallic catalyst can greatly improve the cyclic stability of the catalyst. Therefore, the bimetallic catalyst of Co-Fe supported on α-MoC can exhibit excellent catalytic performance in the reaction of preparing 2-methoxy-4-methylphenol by hydrodeoxygenation of vanillin.

[0023] In the present invention, the carrier molybdenum carbide (α-MoC) of the present invention can be directly purchased from the market or prepared by itself: for example, a certain amount (e.g., 1.0 g) of molybdenum trioxide is placed in a high-temperature tube furnace, and in an NH3 atmosphere, the temperature is adjusted to rise from room temperature to about 650-800°C (preferably 680-750°C) at a heating rate of 5-15°C / min, and then maintained for a period of time (e.g., 0.5-5 h), and then naturally cooled to room temperature (preferably, the cooling process is maintained at an ammonia atmosphere); then the gas is switched to an atmosphere of about 20% CH4 / H2 (preferably, the introduction amount is 30-100 mL / min), the temperature is adjusted to rise from room temperature to about 650-800°C (preferably 680-750°C) at a heating rate of 3-10°C / min, and then maintained for a period of time (e.g., 1-12 h), and then naturally cooled to room temperature (preferably, the cooling process is maintained at about 20% CH4 / H2). The α-MoC can be obtained after the gas is switched to 5% O2 / Ar atmosphere (preferably with a flow rate of 10-50 mL / min) at room temperature and passivated for a period of time (e.g., 3-24 h).

[0024] In the present invention, in the process of adding α-MoC to the active component precursor solution containing cobalt and iron for impregnation treatment to obtain the catalyst precursor, the α-MoC carrier can be first impregnated in a soluble cobalt salt solution and then in a soluble iron salt solution, or the α-MoC carrier can be directly impregnated in a mixed solution of a prepared soluble cobalt salt and a soluble iron salt. In the above two impregnation methods, the amount of the carrier and the metal active component is matched and adjusted in advance according to the specific composition of the desired target product.

[0025] Compared with the prior art, the beneficial technical effects of the present invention are as follows: 1: The molybdenum carbide (α-MoC) supported cobalt-iron bimetallic catalyst for hydrogenating vanillin to synthesize 2-methoxy-4-methylphenol can obtain high value-added 2-methoxy-4-methylphenol product in high yield with relatively easy-to-obtain vanillin as raw material under relatively mild reaction conditions, and the preparation and production process is short, the cost is low, the economy is effective, the universality is strong, the environment is friendly, the equipment is not corrosive, and the product quality is high.

[0026] 2: The self-made molybdenum carbide (α-MoC) loaded cobalt-iron bimetallic catalyst of the present invention has excellent catalytic hydrogenation and deoxygenation performance for vanillin and has high selectivity for 2-methoxy-4-methylphenol. At the same time, the catalyst also has excellent cycle stability, has broad market prospects and significant economic potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1This is the TEM image of Catalyst III prepared in Preparation Example 3. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is illustrated below by way of example, and the scope of protection requested by the present invention includes but is not limited to the following embodiments.

[0029] Preparation Example 1 0.16 g of cobalt acetate and 0.19 g of ferric nitrate were dissolved in 15 mL of deionized water to obtain a mixed salt solution, and then 1.0 g of molybdenum carbide was added to the mixed salt solution for impregnation reaction for 2 h to obtain a catalyst precursor, and then the catalyst precursor was placed in a tubular furnace, firstly heat-treated at 400° C. for 3 h in a nitrogen atmosphere, and then heat-treated at 400° C. for 3 h in a hydrogen atmosphere, and finally cooled to room temperature in a nitrogen atmosphere to obtain Catalyst I (it was detected that the Co loading in Catalyst I was 5.30 wt% of the total mass of the carrier, and the Fe loading was 4.35 wt% of the total mass of the carrier) Preparation Example 2 0.22 g of cobalt acetate and 0.19 g of ferric nitrate were dissolved in 15 mL of deionized water to obtain a mixed salt solution, and then 1.0 g of molybdenum carbide was added to the mixed salt solution for impregnation reaction for 2 h to obtain a catalyst precursor, and then the catalyst precursor was placed in a tubular furnace, first heat-treated at 400° C. for 3 h in a nitrogen atmosphere, and then heat-treated at 400° C. for 3 h in a hydrogen atmosphere, and finally cooled to room temperature in a nitrogen atmosphere to obtain Catalyst II (it was detected that the Co loading in Catalyst II was 7.27 wt% of the total mass of the carrier, and the Fe loading was 4.34 wt% of the total mass of the carrier) Preparation Example 3 0.25 g of cobalt acetate and 0.19 g of ferric nitrate were dissolved in 15 mL of deionized water to obtain a mixed salt solution, and then 1.0 g of molybdenum carbide was added to the mixed salt solution for impregnation reaction for 2 h to obtain a catalyst precursor, and then the catalyst precursor was placed in a tubular furnace, first heat-treated at 400° C. for 3 h in a nitrogen atmosphere, and then heat-treated at 400° C. for 3 h in a hydrogen atmosphere, and finally cooled to room temperature in a nitrogen atmosphere to obtain Catalyst III (it was detected that the Co loading in Catalyst III was 8.28 wt% of the total mass of the carrier, and the Fe loading was 4.34 wt% of the total mass of the carrier) Preparation Example 4 0.30 g of cobalt acetate and 0.19 g of ferric nitrate were dissolved in 15 mL of deionized water to obtain a mixed salt solution, and then 1.0 g of molybdenum carbide was added to the mixed salt solution for impregnation reaction for 2 h to obtain a catalyst precursor, and then the catalyst precursor was placed in a tubular furnace, first heat-treated at 400° C. for 3 h in a nitrogen atmosphere, and then heat-treated at 400° C. for 3 h in a hydrogen atmosphere, and finally cooled to room temperature in a nitrogen atmosphere to obtain Catalyst IV (it was detected that the Co loading in Catalyst IV was 9.94 wt% of the total mass of the carrier, and the Fe loading was 4.33 wt% of the total mass of the carrier) Preparation Example 5 0.34 g of cobalt acetate and 0.19 g of ferric nitrate were dissolved in 15 mL of deionized water to obtain a mixed salt solution, and then 1.0 g of molybdenum carbide was added to the mixed salt solution for impregnation reaction for 2 h to obtain a catalyst precursor, and then the catalyst precursor was placed in a tubular furnace, firstly heat-treated at 400° C. for 3 h in a nitrogen atmosphere, and then heat-treated at 420° C. for 3 h in a hydrogen atmosphere, and finally cooled to room temperature in a nitrogen atmosphere to obtain catalyst V (it was detected that the Co loading in catalyst V was 11.28 wt% of the total mass of the carrier, and the Fe loading was 4.32 wt% of the total mass of the carrier) Preparation Example 6 0.25 g of cobalt acetate and 0.11 g of ferric nitrate were dissolved in 15 mL of deionized water to obtain a mixed salt solution, and then 1.0 g of molybdenum carbide was added to the mixed salt solution for impregnation reaction for 2 h to obtain a catalyst precursor, and then the catalyst precursor was placed in a tubular furnace, firstly heat-treated at 400° C. for 3 h in a nitrogen atmosphere, and then heat-treated at 400° C. for 3 h in a hydrogen atmosphere, and finally cooled to room temperature in a nitrogen atmosphere to obtain Catalyst VI (it was detected that the Co loading in Catalyst VI was 8.29 wt% of the total mass of the carrier, and the Fe loading was 2.51 wt% of the total mass of the carrier) Preparation Example 7 0.25 g of cobalt acetate and 0.16 g of ferric nitrate were dissolved in 15 mL of deionized water to obtain a mixed salt solution, and then 1.0 g of molybdenum carbide was added to the mixed salt solution for impregnation reaction for 2 h to obtain a catalyst precursor, and then the catalyst precursor was placed in a tubular furnace, first heat-treated at 400° C. for 3 h in a nitrogen atmosphere, and then heat-treated at 400° C. for 3 h in a hydrogen atmosphere, and finally cooled to room temperature in a nitrogen atmosphere to obtain Catalyst VII (it was detected that the Co loading in Catalyst VII was 8.29 wt% of the total mass of the carrier, and the Fe loading was 3.65 wt% of the total mass of the carrier) Preparation Example 8 0.25 g of cobalt acetate and 0.21 g of ferric nitrate were dissolved in 15 mL of deionized water to obtain a mixed salt solution, and then 1.0 g of molybdenum carbide was added to the mixed salt solution for impregnation reaction for 2 h to obtain a catalyst precursor, and then the catalyst precursor was placed in a tubular furnace, firstly heat-treated at 400° C. for 3 h in a nitrogen atmosphere, and then heat-treated at 400° C. for 3 h in a hydrogen atmosphere, and finally cooled to room temperature in a nitrogen atmosphere to obtain Catalyst VIII (it was detected that the Co loading in Catalyst VIII was 8.28 wt% of the total mass of the carrier, and the Fe loading was 4.80 wt% of the total mass of the carrier) Preparation Example 9 0.25 g of cobalt acetate and 0.25 g of ferric nitrate were dissolved in 15 mL of deionized water to obtain a mixed salt solution, and then 1.0 g of molybdenum carbide was added to the mixed salt solution for impregnation reaction for 2 h to obtain a catalyst precursor, and then the catalyst precursor was placed in a tubular furnace, firstly heat-treated at 400° C. for 3 h in a nitrogen atmosphere, and then heat-treated at 400° C. for 3 h in a hydrogen atmosphere, and finally cooled to room temperature in a nitrogen atmosphere to obtain Catalyst IX (it was detected that the Co loading in Catalyst IX was 8.27 wt% of the total mass of the carrier, and the Fe loading was 5.72 wt% of the total mass of the carrier) Preparation Example 10 0.25 g of cobalt acetate and 0.29 g of ferric nitrate were dissolved in 15 mL of deionized water to obtain a mixed salt solution, and then 1.0 g of molybdenum carbide was added to the mixed salt solution for impregnation reaction for 2 h to obtain a catalyst precursor, and then the catalyst precursor was placed in a tubular furnace, firstly heat-treated at 400° C. for 3 h in a nitrogen atmosphere, and then heat-treated at 400° C. for 3 h in a hydrogen atmosphere, and finally cooled to room temperature in a nitrogen atmosphere to obtain a catalyst X (it was detected that the Co loading in the catalyst X was 8.27 wt% of the total mass of the carrier, and the Fe loading was 6.63 wt% of the total mass of the carrier) Preparation Example 11 Preparation Example 13 was repeated except that 0.25 g of cobalt acetate was replaced with 0.26 g of cobalt nitrate.

[0030] Preparation Example 12 Preparation Example 13 was repeated except that 0.19 g of ferric nitrate was replaced with 0.13 g of ferric chloride.

[0031] Comparative Example 1 0.25 g of cobalt acetate was dissolved in 15 mL of deionized water to obtain a mixed salt solution, and then 1.0 g of molybdenum carbide was added to the mixed salt solution for impregnation reaction for 2 h to obtain a catalyst precursor, and then the catalyst precursor was placed in a tubular furnace, firstly heat-treated at 400° C. for 3 h in a nitrogen atmosphere, and then heat-treated at 400° C. for 3 h in a hydrogen atmosphere, and finally cooled to room temperature in a nitrogen atmosphere to obtain catalyst-1 (the Co loading in catalyst-1 was detected to be 8.29 wt% of the total mass of the carrier) Comparative Example 2 0.19 g of ferric nitrate was dissolved in 15 mL of deionized water to obtain a mixed salt solution, and then 1.0 g of molybdenum carbide was added to the mixed salt solution for impregnation reaction for 2 h to obtain a catalyst precursor, and then the catalyst precursor was placed in a tubular furnace, first heat-treated at 400° C. for 3 h in a nitrogen atmosphere, and then heat-treated at 400° C. for 3 h in a hydrogen atmosphere, and finally cooled to room temperature in a nitrogen atmosphere to obtain Catalyst-2 (the Fe loading in Catalyst-2 was detected to be 4.34 wt% of the total mass of the carrier) Comparative Example 3 0.25 g of cobalt acetate and 0.19 g of ferric nitrate were dissolved in 15 mL of deionized water to obtain a mixed salt solution, and then 1.0 g of activated carbon was added to the mixed salt solution for impregnation reaction for 2 hours to obtain a catalyst precursor. Subsequently, the catalyst precursor was placed in a tubular furnace, firstly heat-treated at 400°C in a nitrogen atmosphere for 3 hours, and then heat-treated at 400°C in a hydrogen atmosphere for 3 hours, and finally cooled to room temperature in a nitrogen atmosphere to obtain Catalyst-3 (it was detected that the Co loading in Catalyst-3 was 8.29 wt% of the total mass of the carrier, and the Fe loading was 4.35 wt% of the total mass of the carrier).

[0032] Application Example 1 1.0 g of vanillin was added to the inner lining of a high-pressure reactor containing 10 g of 1,4-dioxane, and then 0.1 g of catalyst I was added, and then a magnet was placed in the reactor; after the reactor was sealed, the air in the reactor was replaced with hydrogen for 4 times, and then the reactor was evacuated to a vacuum with a vacuum pump, and finally the reactor was placed in the jacket of an electric heating reactor and heated to 100°C, and hydrogen was introduced to increase the pressure to a reaction pressure of 1.0 MPa, and the reaction start time was recorded. After 6 hours, the reaction was completed, and the main valves of the electric heating reactor and the hydrogen cylinder were closed, and the reactor was placed in a cold water bath and cooled to room temperature; the cooled reaction liquid was taken out, and the product was qualitatively and quantitatively analyzed by gas chromatography, and it was detected that the conversion rate of vanillin was 100%, and the selectivity of 2-methoxy-4-methylphenol was 98.6%.

[0033] The catalysts prepared in Examples 2 to 10 and Comparative Examples 1 to 3 were respectively subjected to the above-mentioned process of catalytic hydrogenation of vanillin to synthesize 2-methoxy-4-methylphenol, and the catalytic performance of each catalytic material was tested.

[0034] Table 1 is a comparison table of the catalytic results of various embodiments and comparative examples:

[0035] Catalyst cycle stability test: The catalysts prepared in Preparation Examples 1 to 10 and Comparative Examples 1 to 3 were respectively repeatedly used in the process of catalytic hydrogenation of vanillin to synthesize 2-methoxy-4-methylphenol in Example 1, and each catalyst was recycled 100 times: Table 2 is a comparison table of catalytic results after each catalytic material was recycled 100 times:

[0036] It can be seen from Table 1 and Table 2 above that the catalyst prepared by the present invention has excellent catalytic performance and selectivity for the catalytic hydrogenation of vanillin to synthesize 2-methoxy-4-methylphenol, and also has excellent cycle stability.

Claims

1. A bimetallic catalyst for hydrogenating vanillin to synthesize 2-methoxy-4-methylphenol, characterized in that: The bimetallic catalyst comprises a carrier and a bimetallic active component loaded on the carrier; the carrier is molybdenum carbide, and the bimetallic active component is cobalt and iron.

2. The bimetallic catalyst according to claim 1, characterized in that: In the bimetallic catalyst, the loading amount of cobalt is 7-10% of the mass of molybdenum carbide, preferably 7.5-9%; the loading amount of iron is 3-6% of the mass of molybdenum carbide, preferably 4-5%.

3. A method for preparing a bimetallic catalyst for catalytic hydrogenation of vanillin to synthesize 2-methoxy-4-methylphenol or a method for preparing a bimetallic catalyst as claimed in claim 1 or 2, characterized in that: The bimetallic catalyst is prepared by the following method: 1) dissolving a soluble cobalt salt and a soluble iron salt in water to obtain an active component precursor solution; 2) adding molybdenum carbide into an active component precursor solution for impregnation treatment to obtain a catalyst precursor; 3) The catalyst precursor is first calcined in an inert atmosphere and a reducing atmosphere in sequence, and then cooled in an inert atmosphere to obtain the target bimetallic catalyst.

4. The method according to claim 3, characterized in that: The soluble cobalt salt includes one or more of cobalt chloride, cobalt nitrate, cobalt sulfate and cobalt acetate; and / or The soluble iron salt includes one or more of ferric chloride, ferrous chloride, ferric nitrate, ferrous nitrate, ferric sulfate, and ferrous sulfate.

5. The method according to claim 3 or 4, characterized in that: The inert atmosphere is a nitrogen atmosphere and / or a helium atmosphere and / or an argon atmosphere; the catalyst precursor is calcined in the inert atmosphere at a temperature of 300-600° C., preferably 400-500° C.; the calcination time is 0.5-5 h, preferably 1-4 h; and / or The reducing atmosphere is a hydrogen atmosphere and / or a carbon monoxide atmosphere; the catalyst precursor is calcined in the reducing atmosphere at a temperature of 300-600° C., preferably 400-500° C.; and the calcination time is 0.5-5 h, preferably 1-4 h.

6. A method for synthesizing 2-methoxy-4-methylphenol, characterized in that: The method specifically comprises: first dissolving vanillin in a solvent, then adding the bimetallic catalyst as described in claims 1-2 or adding the bimetallic catalyst prepared by the method as described in any one of claims 3-5, then performing a thermal reaction under a reducing atmosphere to obtain a crude product, and finally purifying the crude product to obtain 2-methoxy-4-methylphenol.

7. The method according to claim 6, characterized in that: The addition amount of the bimetallic catalyst is 3-15% of the vanillin mass, preferably 5-12%.

8. The method according to claim 6 or 7, characterized in that: The solvent is an organic solvent, preferably the organic solvent is 1,4-dioxane; preferably, the amount of the solvent used is 3 to 30 times the mass of vanillin.

9. The method according to any one of claims 6 to 8, characterized in that: The temperature of the thermal reaction is 80-120° C., preferably 90-110° C.; the time of the thermal reaction is 3-12 hours, preferably 5-10 hours.

10. The method according to any one of claims 6 to 9, characterized in that: During the thermal reaction, the pressure of the reducing atmosphere is 0.5-5 MPa, preferably 1-3 MPa; preferably, the reducing atmosphere is a hydrogen atmosphere.

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