A process for the preparation of a catalyst for the simultaneous production of 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol from furfural hydrogenation

Abstract

The application discloses a preparation method of a catalyst for simultaneously producing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol through furfural hydrogenation. The catalyst preparation steps are as follows: (1) under normal temperature and pressure, a palladium salt, deionized water, a molecular sieve and a copper salt are stirred and mixed for 5-24 hours to obtain a mixed solution; (2) the obtained mixed solution is dried under an air atmosphere at 80-150 DEG C and normal pressure for 8-20 hours; (3) the dried catalyst is calcined in a muffle furnace under an air atmosphere at normal pressure and at 400-600 DEG C for 4-16 hours to obtain a Cu-Pd supported bimetallic catalyst. The furfural hydrogenation catalyst is simple to prepare, has relatively mild and simple use conditions, has long service life and high activity, and can simultaneously produce 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol through furfural hydrogenation.

Description

Technical Field

[0001] This invention relates to the field of bio-based chemical refining technology, and in particular to a method for preparing a catalyst for the simultaneous production of 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by hydrogenation of furfural. The method employs an equal-volume impregnation method to prepare a bimetallic supported furfural hydrogenation catalyst. Background Technology

[0002] 2-Methyltetrahydrofuran and tetrahydrofuran are products obtained by hydrogenating furfural, 2-methylfuran, and furfuryl alcohol derived from biomass. The carbon source is entirely from renewable biomass, aligning with the current national "dual-carbon" strategic goal of achieving carbon peaking and carbon neutrality. 2-Methyltetrahydrofuran is an important biofuel, a high-end environmentally friendly solvent, and a chemical intermediate: when used as a biofuel, it is miscible with gasoline in any proportion and exhibits excellent oxidation and vapor pressure properties; 2-Methyltetrahydrofuran can serve as a high-boiling-point alternative solvent to tetrahydrofuran and is an important solvent for low-temperature reactions; 2-Methyltetrahydrofuran forms a glassy solid at low temperatures without crystallizing, therefore it is frequently used as a solvent for spectroscopic studies at -196°C; 2-Methyltetrahydrofuran is also a raw material in the pharmaceutical industry and can be used in the synthesis of anti-hemorrhoid drugs such as primaquine phosphate. Tetrahydrofurfuryl alcohol, also known as tetrahydrofuran-2-methanol, is an important organic solvent and fine chemical raw material. It is a good fluxing solvent in electronic chemicals and soldering fluxes, a good solvent for resins, coatings, and oils, and a raw material for the production of dihydrofuran, tetrahydrofuran, lysine, and long-acting vitamin B. In addition, it can be used to produce polyamide plastics, and in printing and dyeing, it is used as a lubricant, dispersant, and decolorizing and deodorizing agent for pharmaceuticals.

[0003] 2-Methyltetrahydrofuran is currently mainly prepared via hydrogenation. Different catalysts are used depending on the source of the raw materials. The main preparation methods are as follows:

[0004] 1. One-step hydrogenation of furfural to prepare 2-methyltetrahydrofuran. Patent CN101589033A uses Pb or Pt supported on activated carbon as a catalyst in a fixed-bed reactor. Gaseous furfural reacts with hydrogen under the action of the catalyst. The reaction conditions are 150-300℃ and 0.1-1.5 MPaA to obtain 2-methyltetrahydrofuran. The furfural conversion rate is >99%, and the selectivity of 2-methyltetrahydrofuran is ~50%.

[0005] Patent CN105601592A employs a two-stage loading method in a fixed bed, consisting of a copper-supported catalyst and a palladium-supported catalyst. Gasified furfural and hydrogen first pass through the copper-supported catalyst to generate 2-methylfuran, and then through the palladium-supported catalyst to generate 2-methyltetrahydrofuran. The reaction conditions are 140–200 °C and 0.1–0.13 MPaG, achieving 100% furfural conversion and 97.1% selectivity for 2-methyltetrahydrofuran. This patent does not specify the catalyst deactivation time.

[0006] Patent CN113354602A utilizes a Cu-Ni / SiO2 catalyst to react gasified furfural with hydrogen in a fixed-bed reactor to produce 2-methyltetrahydrofuran. The reaction conditions are: 140–200℃, furfural conversion >99.5%, and 2-methyltetrahydrofuran selectivity >95.5%. The catalyst's single-pass lifetime is greater than 2000 hours.

[0007] Patent CN114644605A uses a Cu-Ni supported catalyst, and adds phenylhydrazine hydrochloride and sodium vanadate to improve catalytic activity, achieving 100% furfural conversion and ≥75% selectivity for 2-methyltetrahydrofuran.

[0008] 2. Preparation of 2-methyltetrahydrofuran by hydrogenation of 2-methylfuran. Patent CN101492433A uses a ruthenium-zinc / copper / iron activated carbon supported catalyst to hydrogenate 2-methylfuran in the liquid phase in a reactor under the following reaction conditions: 50–100℃ and 1.0–4.0 MPa.

[0009] Patent CN103214437A uses a nickel-based catalyst to perform gas-phase hydrogenation of 2-methylfuran in a fixed bed; Patent CN111841545A uses a nickel-aluminum-cobalt mixed catalyst to perform hydrogenation of 2-methylfuran in a tubular fixed bed reactor; Patent CN112871172A uses a Ni / Al2O3 catalyst to prepare 2-methyltetrahydrofuran by gas-phase hydrogenation.

[0010] Tetrahydrofurfuryl alcohol is also prepared via hydrogenation, using different catalysts depending on the raw materials. The main preparation methods are as follows:

[0011] 1. Preparation of tetrahydrofurfuryl alcohol from furfuryl alcohol by hydrogenation. Patent CN1280980A uses a supported nickel catalyst for liquid-phase hydrogenation to prepare tetrahydrofurfuryl alcohol, with reaction conditions of 100–200℃ and 2–8 MPa; Patent CN1847234A uses a nickel-aluminum-molybdenum catalyst for liquid-phase hydrogenation to prepare tetrahydrofurfuryl alcohol, with reaction conditions of 30–80℃ and 1.5–2 MPa; Patent CN104610199A uses a palladium supported catalyst for liquid-phase hydrogenation, with reaction conditions of 15–30℃ and 0.1–0.5 MPa; Patent CN106622219A uses a supported ruthenium catalyst for liquid-phase hydrogenation, with reaction conditions of 20–80℃ and 2.0–4.0 MPa, achieving a furfuryl alcohol conversion rate ≥98% and a tetrahydrofurfuryl alcohol selectivity ≥95%.

[0012] 2. Preparation of tetrahydrofurfuryl alcohol by hydrogenation of furfural. Patent CN102489315A uses a ruthenium-co-catalyst supported on titanium dioxide as a catalyst, in a liquid-phase batch reaction, under the following conditions: 50–110℃, 0.5–3 MPa; Patent CN104672185A uses a nickel-based catalyst and alkaline additives, in a liquid-phase batch reaction, under the following conditions: 80–180℃, 0.5–10 MPa, achieving a tetrahydrofurfuryl alcohol yield of up to 94%; CN109796427A uses a Pd-Ru bimetallic supported catalyst to prepare tetrahydrofurfuryl alcohol by liquid-phase hydrogenation of furfural, under the following conditions: 20–60℃, 0.3–1 MPa.

[0013] Based on currently available methods for preparing 2-methyltetrahydrofuran, the raw materials are all derived from biomass. Furfural is produced from the biomass, and then 2-methyltetrahydrofuran is prepared via either a one-step method (direct preparation of 2-methyltetrahydrofuran from furfural) or a two-step method (preparation of 2-methylfuran from furfural, followed by further hydrogenation of the 2-methylfuran to obtain 2-methyltetrahydrofuran). The one-step method uses noble metal-supported catalysts or Cu-noble metal-supported catalysts; the two-step method first hydrogenates furfural to prepare 2-methylfuran, and then further hydrogenates it using a nickel or ruthenium-based catalyst to obtain 2-methyltetrahydrofuran.

[0014] The preparation method of tetrahydrofuran is similar to that of 2-methyltetrahydrofuran. The main raw materials are furfural or furfuryl alcohol, of which furfuryl alcohol is obtained by hydrogenation of furfural.

[0015] Most existing methods utilize fixed-bed reactors or batch reactors, and none have been found to simultaneously yield 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol through a one-step hydrogenation reaction. Since furfural, furfuryl alcohol, 2-methylfuran, 2-methyltetrahydrofuran, and tetrahydrofurfuryl alcohol belong to the same industrial chain, obtaining two highly selective products using a single catalyst would better meet market demand, reduce plant construction investment, and offer better economic benefits.

[0016] This invention addresses the current situation where different catalysts are required for the hydrogenation of furfural using 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol. It proposes a bimetallic supported catalyst, which can directionally regulate the yields of 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by adjusting the loading amount of the noble metal Pd. The conversion rate of furfural is 100%, and the overall yield of 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol is >93.2%. Summary of the Invention

[0017] This invention provides a method for preparing a catalyst for the simultaneous hydrogenation of furfural to produce 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol. The catalyst prepared by this method is capable of directly producing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol from furfural. The reaction principle equation is as follows:

[0018]

[0019] This catalyst is suitable for batch hydrogenation in a batch reactor or continuous hydrogenation in a reactive distillation column. Liquid furfural and excess hydrogen react under Cu-Pd / HY, Cu-Pd / Hβ, or Cu-Pd / HZSM-5 supported catalysts to yield 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol. Reaction conditions: 150–300 °C, 0.1–5 MPa.

[0020] The present invention adopts the following technical solution:

[0021] A method for preparing a catalyst for the simultaneous hydrogenation of furfural to produce 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol, the method comprising the following steps:

[0022] (1) Palladium salt, deionized water, molecular sieve and copper salt were mixed under normal temperature and pressure to obtain a mixture;

[0023] (2) The mixture obtained in step (1) is dried in air at 80-150°C and normal pressure for 8-20 hours to obtain the catalyst precursor;

[0024] (3) The catalyst precursor obtained in step (2) is calcined in air atmosphere, at atmospheric pressure and at 400-600℃ for 4-16 hours to obtain Cu-Pd bimetallic supported catalyst.

[0025] Specifically, the objective of this invention is to provide a method for preparing a catalyst for the simultaneous hydrogenation of furfural to produce 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol, comprising the following steps:

[0026] (1) Palladium salt, deionized water, HY type molecular sieve or Hβ type molecular sieve or HZSM-5 type molecular sieve and copper salt are stirred and mixed for 5 to 24 hours under normal temperature and pressure to obtain a mixed solution.

[0027] (2) The mixture obtained in step (1) is dried in air at 80-150°C and normal pressure for 8-20 hours to obtain the catalyst precursor.

[0028] (3) The catalyst precursor obtained in step (2) is calcined in air atmosphere, at atmospheric pressure and at 400-600℃ for 4-16 hours to obtain Cu-Pd bimetallic supported catalyst.

[0029] Further, in step (1), the palladium salt is selected from one or more of palladium phosphate, palladium nitrate, and palladium acetate.

[0030] Preferably, the copper salt in step (1) is selected from one or more of copper phosphate, copper nitrate, copper acetate and copper sulfate.

[0031] Preferably, the molecular sieve used in step (1) is selected from one or more of HZSM-5 type molecular sieve, HY type molecular sieve, and Hβ type molecular sieve, and the silica-to-alumina ratio in the molecular sieve is 3 to 40. For example, the silica-to-alumina ratio in the molecular sieve is 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, or 40.

[0032] Furthermore, in the mixing process described in step (1), palladium acetate is used as the palladium salt, copper nitrate is used as the copper salt, and HY-type molecular sieve (silicon-to-aluminum ratio 5-6) is used for molecular sieving.

[0033] Further, in step (1), the weight ratio of palladium salt:copper salt:molecular sieve:deionized water is 0.05–1.5:1–3:3–9:4–70. For example, the weight ratios of palladium salt:copper salt:molecular sieve:deionized water are 0.05:1.9:4.25:50, 0.1:1.9:4.25:50, 0.2:1.9:4.25:50, 0.3:1.9:4.25:50, 0.4:1.9:4.25:50, 0.5:1.9:4.25:50, 0.53:1.9:4.25:50, 0.76:1.95:4.25:50, 1. 13:2.03:4.25:50, 0.2:1~3:3~9:4~70, 0.25:1~3:3~9:4~70, 0.3:1~3:3~9:4~70, 0.35:1~3:3~9:4~70, 0.4:1~3:3~9:4~70, 0.45:1~3:3~9:4~70, 0.5:1~3:3~9:4~70, 0.55:1~3:3~9:4~70 0.6:1~3:3~9:4~70, 0.65:1~3:3~9:4~70, 0.7:1~3:3~9:4~70, 0.75:1~3:3~9:4~70, 0.8:1~3:3~9:4~70, 0.85:1~3:3~9:4~70, 0.9:1~3:3~9:4~70, 0.95:1~3:3~9:4~70, 1:1~3:3~9:4~70 1.1:1~3:3~9:4~70, 1.15:1~3:3~9:4~70, 1.2:1~3:3~9:4~70, 1.25:1~3:3~9:4~70, 1.3:1~3:3~9:4~70, 1.35:1~3:3~9:4~70, 1.4:1~3:3~9:4~70, 1.45:1~3:3~9:4~70 or 1.5:1~3:3~9:4~7.

[0034] Preferably, in the mixing process described in step (1), the palladium salt is palladium acetate, the copper salt is copper nitrate, the molecular sieve is HY type molecular sieve, and the weight ratio of palladium acetate:copper nitrate:HY type molecular sieve is 0.4-1.2:1.4-2.4:4-6; preferably, the weight ratio of palladium acetate:copper nitrate:HY type molecular sieve is 0.4-0.8:1.4-2.4:4.25-6. For example, the weight ratio of palladium acetate:copper nitrate:HY type molecular sieve is 0.4:1.4~2.4:4~6, 0.45:1.4~2.4:4~6, 0.5:1.4~2.4:4~6, 0.55:1.4~2.4:4~6, 0.6:1.4~2.4:4~6, 0.65:1.4~2.4:4~6, 0.7:1.4~2.4:4~6, 0.75:1.4~2.4:4~6, 0.8:1.4~2.4:4~6, 0.53:1.9:4.25, 0.76:1.95:4.25, or 1.13:2.03:4.25.

[0035] Preferably, in the mixing process described in step (1), palladium salt, copper salt, HY molecular sieve and deionized water are stirred and mixed for 10 to 16 hours under normal temperature and pressure conditions.

[0036] Preferably, the drying process described in step (2) is carried out in an air atmosphere at 100-120°C (e.g., 100°C, 105°C, 110°C, 115°C or 120°C) and at normal pressure for 12-20 hours.

[0037] Preferably, the roasting process described in step (3) is carried out in a muffle furnace under air atmosphere, at atmospheric pressure, and at 450-550°C (e.g., 450°C, 460°C, 465°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, or 550°C) for 8-12 hours.

[0038] The catalyst prepared by the method described in any of the preceding claims, wherein the weight percentage of Cu in the catalyst prepared by the method is 8 wt% to 15 wt% and the weight percentage of Pd is 0.5 wt% to 12 wt% based on the total weight of the Cu-Pd supported bimetallic catalyst; preferably, the weight percentage of Cu in the catalyst is 8 wt% to 15 wt% and the weight percentage of Pd is 0.5 wt% to 8 wt% based on the total weight of the Cu-Pd supported bimetallic catalyst.

[0039] For example, in the catalyst prepared by the method, the weight percentage of Cu, based on the total weight of the Cu-Pd supported bimetallic catalyst, is 8 wt%, 8.2 wt%, 8.4 wt%, 8.6 wt%, 8.8 wt%, 9 wt%, 9.2 wt%, 9.4 wt%, 9.6 wt%, 9.8 wt%, 10 wt%, 10.2 wt%, 10.4 wt%, 10.6 wt%, 10.8 wt%, 11 wt%, 11.2 wt%, 11.4 wt%, 11.6 wt%, 11.8 wt%, 12 wt%, 12.2 wt%, 12.4 wt%, 12.6 wt%, 12.8 wt%, 13 wt%, 13.2 wt%, 13.4 wt%, 13.6 wt%, 13.8 wt%, 14 wt%, 14.2 wt%, 14.6 wt%. 14.8 wt% or 15 wt%; Pd weight percentage is 0.5 wt%, 0.75 wt%, 1 wt%, 1.2 wt%, 1.4 wt%, 1.6 wt%, 1.8 wt%, 2 wt%, 2.2 wt%, 2.4 wt%, 2.6 wt%, 2.8 wt%, 3 wt%, 3.2 wt%, 3.4 wt%, 3.6 wt%, 3.8 wt%, 4 wt%, 4.2 wt%, 4.4 wt%, 4.6 wt%, 4.8 wt%, 5 wt%, 5.2 wt%, 5.4 wt%, 5.6 wt%, 5.8 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, 10.5 wt%, 11 wt%, 11.5 wt%, or 12 wt%.

[0040] The catalyst prepared by the method described in any of the preceding methods, the Cu-Pd supported bimetallic catalyst obtained in step (3), needs to be reduced with hydrogen before use. The reduction includes reducing the catalyst in a hydrogen atmosphere at a temperature of 450–550°C (e.g., 450°C, 475°C, 500°C, 525°C, or 550°C) for 2–5 hours (e.g., 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, and 5 hours), followed by cooling to room temperature. Preferably, the hydrogen atmosphere refers to a mixed atmosphere of hydrogen and nitrogen, for example, the volume percentage of hydrogen in the mixed atmosphere is 5%.

[0041] The application of the catalyst prepared by the method described in any of the preceding methods in the hydrogenation of furfural to produce 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol. This invention proposes a method for preparing a catalyst suitable for furfural hydrogenation. Compared to previously disclosed methods for preparing single 2-methyltetrahydrofuran or tetrahydrofurfuryl alcohol using furfural hydrogenation catalysts, the hydrogenation catalyst proposed in this invention uses a Cu-Pd bimetallic supported catalyst, has a long service life (showing no signs of deactivation after 50 repeated uses), and allows for adjustment of the Cu-Pd ratio according to market demand, simultaneously obtaining both 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol. The same production unit better adapts to market needs, reduces construction investment, and achieves better economic benefits. Attached Figure Description

[0042] Figure 1 This is a scanning electron microscope image of the catalyst obtained in Example 4;

[0043] Figure 2 These are the XRD patterns of the catalysts obtained in each embodiment. Detailed Implementation

[0044] The following embodiments are further illustrations of the present invention, but not limitations thereof. Unless otherwise specified, the equipment and chemicals used in the present invention are commercially available products conventional in this technical field.

[0045] Example 1

[0046] (1) 1.8g of copper nitrate trihydrate (purity 99wt%), 50g of deionized water and 4.25g of HY molecular sieve (Tianjin Nanhua Catalyst Co., Ltd., NKF-7-2QD5.0(HY) molecular sieve, silicon-aluminum ratio 5.4) were stirred and mixed for 8 hours under normal temperature and pressure to obtain a mixture.

[0047] (2) The mixture obtained in step (1) was dried at 110°C and normal pressure for 12 hours in an air atmosphere to obtain 4.85g of catalyst precursor.

[0048] (3) The catalyst precursor obtained in step (2) was calcined in a muffle furnace under air atmosphere, atmospheric pressure, and 500°C for 8 hours to obtain 4.72 g of Cu / HY catalyst. Based on the mass of the catalyst, the Cu content of the catalyst is 10.0 wt% (denoted as 10Cu / HY).

[0049] (4) The catalyst obtained in step (3) was loaded into a reduction tube furnace with an inner diameter of 20 mm, and the catalyst loading amount was 4.72 g. The reducing gas was a hydrogen / nitrogen mixture containing 5% vol of hydrogen, which was heated to 500 °C at a heating rate of 5 °C / min, and then held at that temperature for 3 hours. The hydrogen / nitrogen mixture flow rate was 0.002 Nm. 3 / h; after the reduction is complete, continue to pass a hydrogen / nitrogen mixture to cool down to room temperature, and obtain the reduced catalyst.

[0050] (5) Add 4.7 g of the catalyst obtained in step (4) to a 30 mL magnetically stirred reactor, then add 5 mL of n-heptane and 10 mL of furfural solvent in sequence. After the addition is complete, seal the reactor and purge it three times with 99.99% vol hydrogen gas. Then, purge the reactor with 99.99% vol hydrogen gas to 3 MPaG. After that, start stirring and heat to 220 °C at a rate of 10 °C / min and maintain the temperature for 2 h.

[0051] (6) After the reaction in the reactor in step (5) is completed, the reactor is placed in an ice-water bath for rapid cooling, and then the reaction products are analyzed by gas chromatography. Under the conditions of this example, the catalyst was reused 50 times, and no catalyst deactivation occurred.

[0052] Example 2

[0053] (1) 0.1g of palladium acetate (purity 99wt%), 1.82g of copper nitrate trihydrate (purity 99wt%), 50g of deionized water and 4.25g of HY molecular sieve (Tianjin Nanhua Catalyst Co., Ltd., NKF-7-2QD5.0(HY) molecular sieve, silicon-aluminum ratio 5.4) were stirred and mixed for 8 hours under normal temperature and pressure to obtain a mixed solution.

[0054] (2) The mixture obtained in step (1) was dried at 110°C and normal pressure for 12 hours in an air atmosphere to obtain 4.95g of catalyst precursor.

[0055] (3) The catalyst precursor obtained in step (2) was calcined in a muffle furnace under air atmosphere, atmospheric pressure, and 500°C for 8 hours to obtain 4.78 g of Cu-Pd / HY catalyst. Based on the mass of the catalyst, the catalyst has a Cu content of 10.0 wt% and a Pd content of 1.0 wt% (denoted as 10Cu1Pd / HY).

[0056] (4) The catalyst obtained in step (3) was loaded into a reduction tube furnace with an inner diameter of 20 mm, and the catalyst loading amount was 4.78 g. The reducing gas was a hydrogen / nitrogen mixture containing 5% vol of hydrogen, which was heated to 500 °C at a heating rate of 5 °C / min, and then held at that temperature for 3 hours. The hydrogen / nitrogen mixture flow rate was 0.002 Nm. 3 / h; after the reduction is complete, continue to pass a hydrogen / nitrogen mixture to cool down to room temperature, and obtain the reduced catalyst.

[0057] (5) Add 4.7 g of the catalyst obtained in step (4) to a 30 mL magnetically stirred reactor, then add 5 mL of n-heptane and 10 mL of furfural solvent in sequence. After the addition is complete, seal the reactor and purge it three times with 99.99% vol hydrogen gas. Then, purge the reactor with 99.99% vol hydrogen gas to 3 MPaG. After that, start stirring and heat to 220 °C at a rate of 10 °C / min and maintain the temperature for 2 h.

[0058] (6) After the reaction in the reactor in step (5) is completed, the reactor is placed in an ice-water bath for rapid cooling, and then the reaction products are analyzed by gas chromatography. Under the conditions of this example, the catalyst was reused 50 times, and no catalyst deactivation occurred.

[0059] Example 3

[0060] (1) 0.31 g of palladium acetate (purity 99wt%), 1.86 g of copper nitrate trihydrate (purity 99wt%), 50 g of deionized water and 4.25 g of HY molecular sieve (Tianjin Nanhua Catalyst Co., Ltd., NKF-7-2QD5.0(HY) molecular sieve, silicon-aluminum ratio 5.4) were stirred and mixed for 8 hours under normal temperature and pressure to obtain a mixed solution.

[0061] (2) The mixture obtained in step (1) was dried at 110°C and normal pressure for 12 hours in an air atmosphere to obtain 5.15 g of catalyst precursor.

[0062] (3) The catalyst precursor obtained in step (2) was calcined in a muffle furnace under air atmosphere, atmospheric pressure, and 500°C for 8 hours to obtain 4.89 g of Cu-Pd / HY catalyst. Based on the mass of the catalyst, the catalyst has a Cu content of 10.0 wt% and a Pd content of 3.0 wt% (denoted as 10Cu3Pd / HY).

[0063] (4) The catalyst obtained in step (3) was loaded into a reduction tube furnace with an inner diameter of 20 mm, and the catalyst loading amount was 4.89 g. The reducing gas was a hydrogen / nitrogen mixture containing 5% vol of hydrogen, which was heated to 500 °C at a heating rate of 5 °C / min, and then held at that temperature for 3 hours. The hydrogen / nitrogen mixture flow rate was 0.002 Nm. 3 / h; after the reduction is complete, continue to pass a hydrogen / nitrogen mixture to cool down to room temperature, and obtain the reduced catalyst.

[0064] (5) Add 4.7 g of the catalyst obtained in step (4) to a 30 mL magnetically stirred reactor, then add 5 mL of n-heptane and 10 mL of furfural solvent in sequence. After the addition is complete, seal the reactor and purge it three times with 99.99% vol hydrogen gas. Then, purge the reactor with 99.99% vol hydrogen gas to 3 MPaG. After that, start stirring and heat to 220 °C at a rate of 10 °C / min and maintain the temperature for 2 h.

[0065] (6) After the reaction in the reactor in step (5) is completed, the reactor is placed in an ice-water bath for rapid cooling, and then the reaction products are analyzed by gas chromatography. Under the conditions of this example, the catalyst was reused 50 times, and no catalyst deactivation occurred.

[0066] Example 4

[0067] (1) 0.53 g of palladium acetate (purity 99wt%), 1.90 g of copper nitrate trihydrate (purity 99wt%), 50 g of deionized water and 4.25 g of HY molecular sieve (Tianjin Nanhua Catalyst Co., Ltd., NKF-7-2QD5.0(HY) molecular sieve, silicon-aluminum ratio 5.4) were stirred and mixed for 8 hours under normal temperature and pressure to obtain a mixed solution.

[0068] (2) The mixture obtained in step (1) was dried at 110°C and normal pressure for 12 hours in an air atmosphere to obtain 5.20 g of catalyst precursor.

[0069] (3) The catalyst precursor obtained in step (2) was calcined in a muffle furnace under air atmosphere, atmospheric pressure, and 500°C for 8 hours to obtain 5.0 g of Cu-Pd / HY catalyst. Based on the mass of the catalyst, the catalyst has a Cu content of 10.0 wt% and a Pd content of 5.0 wt% (denoted as 10Cu5Pd / HY).

[0070] Figure 1 HR-TEM and SEM images of the 10Cu5Pd / HY catalyst. Figure 1 As shown in Figure c, the average metal particle size of the 10Cu5Pd / HY catalyst (9.7 nm) is smaller than that of the single-metal catalyst 10Cu / HY (13.1 nm). Clearly, the introduction of palladium prevents the agglomeration of copper particles, promoting more uniform dispersion of both metal particles and resulting in smaller particle sizes. Figures (ab, di) show the energy dispersive spectroscopy (EDS) spectra of the 10Cu5Pd / HY catalyst (corresponding to SEM). It is evident that Cu and Pd are uniformly dispersed. High dispersion helps suppress the sintering of metal particles, giving the catalyst excellent stability. Furthermore, well-dispersed metal particles expose more active sites to furfural molecules, which is beneficial for hydrogenation and achieving high conversion rates.

[0071] (4) The catalyst obtained in step (3) was loaded into a reduction tube furnace with an inner diameter of 20 mm, and the catalyst loading amount was 5.0 g. The reducing gas was a hydrogen / nitrogen mixture containing 5% vol of hydrogen, which was heated to 500 °C at a heating rate of 5 °C / min, and then held at that temperature for 3 hours. The hydrogen / nitrogen mixture flow rate was 0.002 Nm. 3 / h; after the reduction is complete, continue to pass a hydrogen / nitrogen mixture to cool down to room temperature, and obtain the reduced catalyst.

[0072] (5) Add 4.7 g of the catalyst obtained in step (4) to a 30 mL magnetically stirred reactor, then add 5 mL of n-heptane and 10 mL of furfural solvent in sequence. After the addition is complete, seal the reactor and purge it three times with 99.99% vol hydrogen gas. Then, purge the reactor with 99.99% vol hydrogen gas to 3 MPaG. After that, start stirring and heat to 220 °C at a rate of 10 °C / min and maintain the temperature for 2 h.

[0073] (6) After the reaction in the reactor in step (5) is completed, the reactor is placed in an ice-water bath for rapid cooling, and then the reaction products are analyzed by gas chromatography. Under the conditions of this example, the catalyst was reused 50 times, and no catalyst deactivation occurred.

[0074] Example 5

[0075] (1) 0.76 g of palladium acetate (purity 99wt%), 1.95 g of copper nitrate trihydrate (purity 99wt%), 50 g of deionized water and 4.25 g of HY molecular sieve (Tianjin Nanhua Catalyst Co., Ltd., NKF-7-2QD5.0(HY) molecular sieve, silicon-aluminum ratio 5.4) were stirred and mixed for 8 hours under normal temperature and pressure to obtain a mixed solution.

[0076] (2) The mixture obtained in step (1) was dried at 110°C and normal pressure for 12 hours in an air atmosphere to obtain 5.35g of catalyst precursor.

[0077] (3) The catalyst precursor obtained in step (2) was calcined in a muffle furnace under air atmosphere, atmospheric pressure, and 500°C for 8 hours to obtain 5.13 g of Cu-Pd / HY catalyst. Based on the mass of the catalyst, the catalyst has a Cu content of 10.0 wt% and a Pd content of 7.0 wt% (denoted as 10Cu7Pd / HY).

[0078] (4) The catalyst obtained in step (3) was loaded into a reduction tube furnace with an inner diameter of 20 mm, and the catalyst loading amount was 5.13 g. The reducing gas was a hydrogen / nitrogen mixture containing 5% vol of hydrogen, which was heated to 500 °C at a heating rate of 5 °C / min, and then held at that temperature for 3 hours. The hydrogen / nitrogen mixture flow rate was 0.002 Nm. 3 / h; after the reduction is complete, continue to pass a hydrogen / nitrogen mixture to cool down to room temperature, and obtain the reduced catalyst.

[0079] (5) Add 4.7 g of the catalyst obtained in step (4) to a 30 mL magnetically stirred reactor, then add 5 mL of n-heptane and 10 mL of furfural solvent in sequence. After the addition is complete, seal the reactor and purge it three times with 99.99% vol hydrogen gas. Then, purge the reactor with 99.99% vol hydrogen gas to 3 MPaG. After that, start stirring and heat to 220 °C at a rate of 10 °C / min and maintain the temperature for 2 h.

[0080] (6) After the reaction in the reactor in step (5) is completed, the reactor is placed in an ice-water bath for rapid cooling, and then the reaction products are analyzed by gas chromatography. Under the conditions of this example, the catalyst was reused 50 times, and no catalyst deactivation occurred.

[0081] Example 6

[0082] (1) 1.13g of palladium acetate (purity 99wt%), 2.03g of copper nitrate trihydrate (purity 99wt%), 50g of deionized water and 4.25g of HY molecular sieve (Tianjin Nanhua Catalyst Co., Ltd., NKF-7-2QD5.0(HY) molecular sieve, silicon-aluminum ratio 5.4) were stirred and mixed for 8 hours under normal temperature and pressure to obtain a mixed solution.

[0083] (2) The mixture obtained in step (1) was dried at 110°C and normal pressure for 12 hours in an air atmosphere to obtain 5.56g of catalyst precursor.

[0084] (3) The catalyst precursor obtained in step (2) was calcined in a muffle furnace under air atmosphere, atmospheric pressure, and 500°C for 8 hours to obtain 5.32 g of Cu-Pd / HY catalyst. Based on the mass of the catalyst, the catalyst has a Cu content of 10.0 wt% and a Pd content of 9.0 wt% (denoted as 10Cu9Pd / HY).

[0085] (4) The catalyst obtained in step (3) was loaded into a reduction tube furnace with an inner diameter of 20 mm, and the catalyst loading amount was 5.32 g. The reducing gas was a hydrogen / nitrogen mixture containing 5% vol of hydrogen, which was heated to 500 °C at a heating rate of 5 °C / min, and then held at that temperature for 3 hours. The hydrogen / nitrogen mixture flow rate was 0.002 Nm. 3 / h; after the reduction is complete, continue to pass a hydrogen / nitrogen mixture to cool down to room temperature, and obtain the reduced catalyst.

[0086] (5) Add 4.7 g of the catalyst obtained in step (4) to a 30 mL magnetically stirred reactor, then add 5 mL of n-heptane and 10 mL of furfural solvent in sequence. After the addition is complete, seal the reactor and purge it three times with 99.99% vol hydrogen gas. Then, purge the reactor with 99.99% vol hydrogen gas to 3 MPaG. After that, start stirring and heat to 220 °C at a rate of 10 °C / min and maintain the temperature for 2 h.

[0087] (6) After the reaction in the reactor in step (5) is completed, the reactor is placed in an ice-water bath for rapid cooling, and then the reaction products are analyzed by gas chromatography. Under the conditions of this example, the catalyst was reused 50 times, and no catalyst deactivation occurred.

[0088] The process parameters for specific embodiments are summarized in the following table:

[0089] Table 1

[0090]

[0091] Furfural hydrogenation was carried out in a stainless steel reactor using n-heptane as solvent and molecular hydrogen as the hydrogen source. Six catalysts with different Cu / Pd ratios (10Cu / HY, 10Cu1Pd / HY, 10Cu3Pd / HY, 10Cu5Pd / HY, 10Cu7Pd / HY, and 10Cu9Pd / HY) were used to investigate their catalytic effects. When using 10Cu / HY, the yield of 2-MTHF was 2.8%, while the yield of THFA was 0 (Table 1, first row), indicating that single-metal copper has poor catalytic activity for specific functional groups, requiring the introduction of a stronger active metal (e.g., palladium) to enhance the catalytic effect. When using 10Cu1Pd / HY, the conversion of furfural reached 93.4%, but the yield of 2-MTHF was 0 (Table 1, second row). This suggests that the Cu-Pd bimetallic catalyst has excellent furfural conversion ability, but the insufficient active metal during hydrogenation may have led to the 0% yield of 2-MTHF. In contrast, when using 10Cu3Pd / HY, the yield of 2-MTHF is 55.2% with 100% furfural conversion (Table 1, row 3). This is likely due to the increased Pd content, which provides more active sites for furan ring hydrogenation, promoting the conversion of the intermediate 2-MF to 2-MTHF. Compared to the reactions using 10Cu1Pd / HY and 10Cu3Pd / HY, under the same reaction parameters, the yield of 2-MTHF is higher with 10Cu5Pd / HY, reaching 83.1% (Table 1, row 4). However, compared to the three catalysts mentioned above, the yield of 2-MTHF is significantly lower with 10Cu7Pd / HY, while the yield of THFA is greater. This is likely due to the stronger hydrogenation ability of Pd, which converts the intermediate FA to THFA (Table 1, row 5). When using the 10Cu9Pd / HY catalyst with a higher Pd content, the yield of 2-MTHF further decreased to 25.8%, while the yield of THFA increased to 53.5%, indicating that the strong hydrogenation ability of Pd played an important role (Table 1, row 6). Clearly, when the Pd content is less than 5%, increasing the Pd content leads to an increase in the yield of 2-MTHF, suggesting that with increasing Pd, the furan ring hydrogenation reaction of the intermediate 2-MF promotes the formation of 2-MTHF. On the other hand, when the Pd content is greater than 5%, increasing Pd leads to a decrease in the yield of 2-MTHF and an increase in the yield of THFA, indicating that excessively high Pd content leads to over-hydrogenation of the furan ring. When the Pd content is too high, the furan ring in the furfural molecule is over-hydrogenated to THFA, and under these reaction conditions, THFA is not easily converted to 2-MTHF. Therefore, the selectivity of the products can be changed by adjusting the Cu / Pd ratio. Within a certain range of Cu / Pd ratios, the selectivity of 2-MTHF increases with increasing Pd.The results showed that with 10Cu5Pd / HY as catalyst, the furfural conversion rate reached 100% and the 2-MTHF yield was 83.1%, which is the highest yield reported to date for the one-pot direct conversion of furfural to 2-MTHF using n-heptane as solvent and H2 as hydrogen source.

[0092] The XRD patterns of the catalysts prepared in the above embodiments are as follows: Figure 2 As shown, the peaks of HY remain largely unchanged in the spectra of other catalysts. For 10Cu / HY, peaks were observed at 43.4°, 50.6°, and 74.2°, which are attributed to Cu, respectively. 0 The (111), (200), and (220) planes were observed. No obvious Pd peaks were found in catalysts with different Cu / Pd mass ratios, likely due to the uniform dispersion of Pd within the catalyst. An interesting trend was also observed: the diffraction peak intensity of Cu decreased significantly with increasing Pd content. After the addition of Pd, only the 43.4° peak was retained in the Cu spectrum, while the 50.6° and 74.2° peaks almost disappeared. This phenomenon may be due to the high dispersion of Cu atoms and the introduction of Pd atoms into the Cu lattice to form a Cu-Pd alloy, leading to changes in the original Cu-Cu lattice. Furthermore, the appearance of new peaks also confirms the formation of the Cu-Pd alloy. In summary, the introduction of Pd significantly benefits the dispersion of Cu particles and leads to the formation of the Cu-Pd alloy. Therefore, due to the synergistic effect between Cu and Pd, the growth and agglomeration of Cu crystals can be reduced, which is beneficial for improving the catalytic effect. This clearly demonstrates the advantages of bimetallic catalysts over monometallic catalysts.

[0093] The parts of this invention not described in detail are well-known to those skilled in the art. The embodiments described above are merely preferred embodiments of the invention, and do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Various modifications and improvements to the technical solutions of this invention made by those skilled in the art without departing from the spirit of the invention should fall within the protection scope defined by the claims of this invention.

Claims

1. Use of a catalyst for the simultaneous production of 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol from furfuryl alcohol hydrogenation, characterized in that, The catalyst is prepared by a method comprising the following steps: (1) a palladium salt, deionized water, molecular sieve and copper salt are mixed under normal temperature and pressure to obtain a mixture; in step (1), the molecular sieve is a HY type molecular sieve, and the silica-alumina ratio of the molecular sieve is 3-40; (2) the mixture obtained in step (1) is dried under an air atmosphere at 80-150°C and normal pressure for 8-20 hours to obtain a catalyst precursor; (3) the catalyst precursor obtained in step (2) is calcined under an air atmosphere, normal pressure and at 400-600°C for 4-16 hours to obtain a Cu-Pd bimetallic supported catalyst; the catalyst prepared by the method has a Cu content of 8wt%-15wt% and a Pd content of 0.5wt%-12wt% based on the total weight of the Cu-Pd bimetallic supported catalyst.

2. Use according to claim 1, characterized in that, In step (1), the palladium salt is selected from one or more of palladium phosphate, palladium nitrate and palladium acetate.

3. Use according to claim 1, characterized in that, In step (1), the copper salt is selected from one or more of copper phosphate, copper nitrate, copper acetate and copper sulfate.

4. Use according to claim 1, characterized in that, In step (1), the weight ratio of the palladium salt, the copper salt, the molecular sieve and the deionized water is 0.05-1.5:1-3:3-9:4-70.

5. The use according to claim 1, characterized in that, In step (1), the palladium salt is palladium acetate, the copper salt is copper nitrate, and the weight ratio of palladium acetate, copper nitrate and HY type molecular sieve is 0.4-1.2:1.4-2.4:4-6.

6. Use according to claim 1, characterized in that, In step (1), the palladium salt, the copper salt, the HY type molecular sieve and the deionized water are mixed under normal temperature and pressure for 10-16 hours.

7. Use according to claim 1, characterized in that, The method further comprises that the Cu-Pd bimetallic supported catalyst obtained in step (3) needs to be reduced with hydrogen before use.

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