A furan hydrogenation catalyst, a preparation method and a process for producing tetrahydrofuran using the catalyst

Abstract

The present application relates to the technical field of tetrahydrofuran preparation, in particular to a furan hydrogenation catalyst, a preparation method and a process for producing tetrahydrofuran by using the catalyst. The furan hydrogenation catalyst comprises a carrier and an active component loaded on the carrier, the active component is metal Ni and Cu, the carrier is Al2O3-SiO2 composite oxide, the content of Ni is 10%-20% by mass of the carrier, the content of Cu is 1%-5%, the content of Al2O3 is 70%-90%, and the content of SiO2 is 10%-30%. The Al2O3 carrier is modified by using a structural aid SiO2, a composite oxide carrier with moderate acidity is obtained, the influence of the oligomers formed by furan polymerization on the activity and stability of the catalyst can be avoided, Cu is used as an auxiliary active component, the furan conversion rate and the tetrahydrofuran selectivity in the furan hydrogenation reaction are improved, and the high tetrahydrofuran yield is ensured.

Description

Technical Field

[0001] This invention relates to the field of tetrahydrofuran preparation technology, specifically to a furan hydrogenation catalyst, a preparation method, and a process for producing tetrahydrofuran using the catalyst. Background Technology

[0002] Tetrahydrofuran (THF) is a high-performance organic solvent, characterized by low toxicity, low boiling point, good fluidity, and excellent solubility, earning it the nickname "universal solvent." THF generally has two main industrial uses: firstly, as a reactive solvent in the manufacture of polyvinyl chloride, pharmaceuticals, and magnetic tapes; and secondly, as a monomer for the production of polytetrahydrofuran (PTMEG). Currently, approximately 70% of THF globally is used to produce PTMEG, which is primarily used in the production of elastic spandex fibers. With the gradual implementation of climate change and carbon emission reduction regulations by countries worldwide, especially the European Union, there is an urgent need to partially replace fossil-based spandex fibers with biomass-based THF.

[0003] Currently, the furfural process is the mainstream technology route for producing bio-based tetrahydrofuran in industry. The furfural process first uses agricultural and forestry waste such as corn cobs / or sugarcane bagasse to produce furfural, and then uses the furfural gas-phase decarbonylation method to produce furan. It has a high decarbonylation conversion rate and furan selectivity, and the process is relatively mature. Finally, the furan is hydrogenated to produce tetrahydrofuran.

[0004] Chinese patent document CN112547071A discloses a catalyst for the hydrogenation of furan to prepare tetrahydrofuran. This catalyst uses TiO2-Al2O3 as a composite support and is prepared as a Ni catalyst via an impregnation method. The Ni content is 20% and the Ti content is 8%. The catalyst is then used in a 10 mL fixed-bed reactor at 210 °C, 3 MPa, and a space velocity of 1 h⁻¹. -1 A study was conducted on the continuous hydrogenation of furan to tetrahydrofuran under a hydrogen / furan molar ratio of 1000. The results showed that the furan conversion rate was approximately 98.3%, and the tetrahydrofuran selectivity was as high as 92.5%. However, the drawbacks of this technology are that the large hydrogen / furan molar ratio and high reaction temperature lead to difficulties in the condensation and recovery of low-boiling-point furan (32℃) and tetrahydrofuran (66℃), as well as problems such as large hydrogen circulation volume and high energy consumption. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defects of existing processes for the hydrogenation of furan to produce tetrahydrofuran, such as large hydrogen circulation volume and high reaction temperature, so as to provide a novel Ni-based catalyst to optimize the process conditions for the hydrogenation of furan to produce tetrahydrofuran.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a furan hydrogenation catalyst, comprising a support and an active component supported on the support; the active component is metallic Ni and Cu, and the support is an Al2O3-SiO2 composite oxide.

[0008] Based on the mass of the carrier, the Ni content is 10%-20%, the Cu content is 1%-5%, the Al2O3 content is 70%-90%, and the SiO2 content is 10%-30%.

[0009] In an embodiment of the present invention, preferably, in the furan hydrogenation catalyst, the Ni content is 14%-20%, the Cu content is 1.5%-3%, the Al2O3 content is 77%-87%, and the SiO2 content is 13%-23%, calculated with the mass of the support as the denominator.

[0010] In a further preferred embodiment of the invention, the furan hydrogenation catalyst contains, with the mass of the support as the denominator, 17% Ni, 2.2% Cu, 80% Al2O3, and 20% SiO2.

[0011] In a further preferred embodiment of the invention, the furan hydrogenation catalyst contains, with the mass of the support as the denominator, 20% Ni, 3% Cu, 87% Al2O3, and 13% SiO2.

[0012] Secondly, the present invention also provides a process for preparing the furan hydrogenation catalyst, comprising the following steps:

[0013] (1) Pseudoboehmite and acidic silica sol are ground, mixed evenly, and water is added to form a suspension. Then dilute nitric acid aqueous solution is added and rheological phase reaction is carried out at 80℃-90℃ for 15-20 hours. After drying and calcination, Al2O3-SiO2 composite oxide is obtained.

[0014] (2) Prepare a mixed aqueous solution containing nickel salt and copper salt, adjust the pH value to 4-4.5, place the Al2O3-SiO2 composite oxide obtained in step (1) into the mixed aqueous solution, impregnate for a first time, dry, calcine, and reduce to obtain Ni-Cu / Al2O3-SiO2 catalyst.

[0015] In an embodiment of the present invention, optionally, the first time is 3 to 5 hours.

[0016] In this embodiment of the invention, in step (1), the calcination temperature is 650℃-700℃ and the calcination time is 5 hours-8 hours.

[0017] In this embodiment of the invention, in step (2), the calcination temperature is 420℃-450℃ and the calcination time is 5 hours-8 hours.

[0018] In this embodiment of the invention, the particle size of the Al2O3-SiO2 composite oxide in step (2) is 20-40 mesh.

[0019] In this embodiment of the invention, the reduction step in step (2) includes: placing the catalyst precursor in a hydrogen-nitrogen mixture, gradually raising the temperature to 280°C within 10 hours, then slowly raising the temperature to 300°C within 4 hours, and switching to pure hydrogen gas, and maintaining the temperature for 20 hours.

[0020] In an embodiment of the present invention, the nickel salt may optionally be at least one of nickel nitrate and nickel acetate.

[0021] In an embodiment of the present invention, the copper salt may optionally be at least one of copper nitrate and copper acetate.

[0022] Thirdly, the present invention provides a process for producing tetrahydrofuran, comprising the following steps: in the presence of a catalyst and hydrogen, furan undergoes a hydrogenation reaction to produce tetrahydrofuran;

[0023] The catalyst is the furan hydrogenation catalyst described in this invention.

[0024] In this embodiment of the invention, the reaction temperature is 100℃-150℃, the hydrogen pressure is 1.5MPa-5.5MPa, and the furan mass hourly space velocity is 0.2h. -1 -0.6h -1 The molar ratio of hydrogen to furan is 10-50.

[0025] In this embodiment of the invention, preferably, the reaction temperature is 115℃-130℃, the hydrogen pressure is 3MPa-3.5MPa, and the furan mass hourly space velocity is 0.35h. -1 -0.45h -1 .

[0026] In this embodiment of the invention, the reaction does not use a solvent.

[0027] In this embodiment of the invention, the reaction is carried out in a continuous fixed-bed reactor.

[0028] The technical solution of the present invention has the following advantages:

[0029] 1. The furan hydrogenation catalyst provided by this invention includes a support and active components supported on the support, wherein the active components are metallic Ni and Cu, and the support is an Al2O3-SiO2 composite oxide. Based on the mass of the support, the Ni content is 10%-20%, the Cu content is 1%-5%, the Al2O3 content is 70%-90%, and the SiO2 content is 10%-30%. This invention considers that the strongly acidic Al2O3 support easily leads to furan polymerization and the formation of oligomers. Therefore, the Al2O3 support is modified with the structural aid SiO2 to obtain a composite oxide support with moderate acidity, which can avoid the oligomers formed by furan polymerization from affecting the catalyst activity and stability. Using Cu as an auxiliary active component not only reduces the catalyst cost but, more importantly, improves the furan conversion rate and tetrahydrofuran selectivity in the furan hydrogenation reaction, ensuring a high tetrahydrofuran yield.

[0030] 2. The furan hydrogenation catalyst provided by the present invention preferably has a Ni content of 14%-20%, a Cu content of 1.5%-3%, an Al2O3 content of 77%-87%, and a SiO2 content of 13%-23%; more preferably, it has a Ni content of 17%, a Cu content of 2.2%, an Al2O3 content of 80%, and a SiO2 content of 20%; or a Ni content of 20%, a Cu content of 3%, an Al2O3 content of 87%, and a SiO2 content of 13%, which further improves the furan conversion rate and tetrahydrofuran selectivity in the furan hydrogenation reaction, making the tetrahydrofuran yield as high as 97% or more.

[0031] 3. The preparation process of the furan hydrogenation catalyst provided by the present invention is simple and easy to operate, and can control the content of the active component of the catalyst and the acidity of the support to a suitable level, thereby maintaining the stability of the catalyst quality.

[0032] 4. The preparation process of the furan hydrogenation catalyst provided by the present invention can obtain the above-mentioned furan hydrogenation catalyst by reducing it with hydrogen at 300°C for 20 hours. The reduction temperature is low, which can reduce the temperature level of the heat exchange medium, thereby reducing the investment in reaction equipment and the difficulty of operation.

[0033] 5. The tetrahydrofuran preparation process provided by the present invention, in the presence of the above-mentioned furan hydrogenation catalyst and hydrogen, hydrogenates furan to produce tetrahydrofuran. The reaction conditions are mild, which is beneficial to reducing operating costs. Detailed Implementation

[0034] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0035] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0036] Because furan contains a large number of unsaturated double bonds, it is prone to polymerization during the reaction process. A decrease in hydrogen partial pressure or an increase in reaction temperature exacerbates this phenomenon. Polymerized furan can cover and block the catalyst pores and active surfaces, affecting the catalyst's activity and lifespan. This invention, through extensive experiments, has found that using the composite oxide support Al2O3-SiO2 and its supported nickel-copper bicomponent catalyst can effectively inhibit furan polymerization, ensuring the catalyst's activity and stability, and extending its lifespan.

[0037] Catalyst Preparation Example 1

[0038] First, the composite carrier Al2O3-SiO2 was measured by oxide. 102.8g of pseudoboehmite and 90g of acidic silica sol were mixed and ground evenly. Water was added to make a suspension. Then, 5mL of dilute nitric acid aqueous solution with a mass percentage of 10% was added while stirring. The sol reaction was carried out at 90℃ for 20 hours. Then, it was dried at 110℃ for 12 hours and calcined at 650℃ for 5 hours. The mixture was then crushed and sieved to obtain an aluminum-silicon composite oxide with a mesh size of 20-40.

[0039] 54.5g of nickel nitrate and 2.8g of copper nitrate were first acidified to pH 4.5 with ammonia water, and then 100g of aluminum-silicon composite oxide support was added and impregnated for 5 hours. After that, it was dried at 110℃ for 12 hours and calcined at 450℃ for 5 hours. The catalyst precursor was placed in a hydrogen-nitrogen mixture and the temperature was gradually increased to 280℃ over 10 hours, and then slowly increased to 300℃ over 4 hours. The temperature was then switched to pure hydrogen and kept constant for 20 hours to obtain the nickel-copper catalyst supported on aluminum-silicon oxide.

[0040] The content of active component Ni is 11%, co-active component Cu is 1%, Al2O3 is 73%, and SiO2 is 27%, with the mass of the composite oxide support as the denominator. The catalyst is labeled Cat1.

[0041] Catalyst Preparation Example 2

[0042] First, the composite carrier Al2O3-SiO2 was prepared by mixing and grinding 108g of pseudoboehmite and 76.7g of acidic silica sol evenly according to the oxide metric. After adding water to make a suspension, 5mL of dilute nitric acid aqueous solution with a mass percentage of 10% was added while stirring. The sol reaction was carried out at 80℃ for 20 hours, then dried at 110℃ for 12 hours, calcined at 700℃ for 5 hours, and crushed and sieved to obtain 20-40 mesh aluminum-silicon composite oxide.

[0043] 69.4 g of nickel nitrate and 4.2 g of copper nitrate were first acidified to pH 4.5 with ammonia water, and then 100 g of aluminum-silicon composite oxide support was added and impregnated for 5 hours. After that, it was dried at 110℃ for 12 hours and calcined at 450℃ for 8 hours. The catalyst precursor was placed in a hydrogen-nitrogen mixture and the temperature was gradually increased to 280℃ over 10 hours, and then slowly increased to 300℃ over 4 hours. The temperature was then switched to pure hydrogen and kept constant for 20 hours to obtain the nickel-copper catalyst supported on aluminum-silicon oxide.

[0044] The content of active component Ni is 14%, co-active component Cu is 1.5%, Al2O3 is 77%, and SiO2 is 23%, with the mass of the composite oxide support as the denominator. The catalyst is labeled Cat2.

[0045] Catalyst Preparation Example 3

[0046] First, the composite carrier Al2O3-SiO2 was prepared by mixing and grinding 112.7g of boehmite and 66.7g of acidic silica sol evenly according to the oxide metric. After adding water to make a suspension, 5mL of dilute nitric acid aqueous solution with a mass percentage of 10% was added while stirring. The sol reaction was carried out at 90℃ for 20 hours, then dried at 110℃ for 12 hours, calcined at 650℃ for 5 hours, and crushed and sieved to obtain 20-40 mesh aluminum-silicon composite oxide.

[0047] 84.2g of nickel nitrate and 8.4g of copper nitrate were first acidified to pH 4.5 with ammonia water, and then 100g of aluminum-silicon composite oxide support was added and impregnated for 5 hours. After that, it was dried at 110℃ for 12 hours and calcined at 450℃ for 5 hours. The catalyst precursor was placed in a hydrogen-nitrogen mixture and the temperature was gradually increased to 280℃ over 10 hours, and then slowly increased to 300℃ over 4 hours. The temperature was then switched to pure hydrogen and kept constant for 20 hours to obtain the nickel-copper catalyst supported on aluminum-silicon oxide.

[0048] The content of active component Ni is 17%, co-active component Cu is 2.2%, Al2O3 is 80%, and SiO2 is 20%, with the mass of the composite oxide support as the denominator. The catalyst is labeled Cat3.

[0049] Catalyst Preparation Example 4

[0050] First, the composite carrier Al2O3-SiO2 was prepared by mixing and grinding 122.5g of boehmite and 43.3g of acidic silica sol evenly according to the oxide metric. After adding water to make a suspension, 5mL of dilute nitric acid aqueous solution with a mass percentage of 10% was added while stirring. The sol reaction was carried out at 85℃ for 15 hours, then dried at 110℃ for 12 hours, calcined at 675℃ for 8 hours, and crushed and sieved to obtain 20-40 mesh aluminum-silicon composite oxide.

[0051] 99.1g of nickel nitrate and 11.4g of copper nitrate were first acidified to pH 4.5 with ammonia water, and then 100g of aluminum-silicon composite oxide support was added and impregnated for 5 hours. After that, it was dried at 110℃ for 12 hours and calcined at 420℃ for 6.5 hours. The catalyst precursor was placed in a hydrogen-nitrogen mixture and the temperature was gradually increased to 280℃ over 10 hours, and then slowly increased to 300℃ over 4 hours. The temperature was then switched to pure hydrogen and kept constant for 20 hours to obtain the nickel-copper catalyst supported on aluminum-silicon oxide.

[0052] The content of active component Ni is 20%, co-active component Cu is 3%, Al2O3 is 87%, and SiO2 is 13%, with the mass of the composite oxide support as the denominator. The catalyst is labeled Cat4.

[0053] Catalyst Preparation Example 5

[0054] First, the composite carrier Al2O3-SiO2 was prepared by mixing and grinding 112.6g of boehmite and 66.7g of acidic silica sol evenly according to the oxide metric. After adding water to make a suspension, 5mL of dilute nitric acid aqueous solution with a mass percentage of 10% was added while stirring. The sol reaction was carried out at 90℃ for 20 hours, then dried at 110℃ for 12 hours, calcined at 650℃ for 5 hours, and crushed and sieved to obtain 20-40 mesh aluminum-silicon composite oxide.

[0055] 95.1g of nickel nitrate was first acidified to pH=4.5 with ammonia water, and then 100g of aluminum-silicon composite oxide support was added and impregnated for 5 hours. After that, it was dried at 110℃ for 12 hours and calcined at 450℃ for 5 hours. The catalyst precursor was placed in a hydrogen-nitrogen mixture and the temperature was gradually increased to 280℃ over 10 hours, and then slowly increased to 300℃ over 4 hours. Then, it was switched to pure hydrogen gas and kept at a constant temperature for 20 hours to obtain the nickel-copper catalyst supported on aluminum-silicon oxide.

[0056] The content of the active component Ni is 19.2%, the content of Al2O3 is 80%, and the content of SiO2 is 20%, with the mass of the composite oxide support as the denominator. The catalyst is labeled Cat5.

[0057] Catalyst Preparation Example 6

[0058] First, the composite carrier Al2O3-SiO2 was prepared by mixing and grinding 112.6g of boehmite and 66.7g of acidic silica sol evenly according to the oxide metric. After adding water to make a suspension, 5mL of dilute nitric acid aqueous solution with a mass percentage of 10% was added while stirring. The sol reaction was carried out at 90℃ for 20 hours, then dried at 110℃ for 12 hours, calcined at 650℃ for 5 hours, and crushed and sieved to obtain 20-40 mesh aluminum-silicon composite oxide.

[0059] 73g of copper nitrate was first acidified to pH 4.5 with ammonia water, and then 100g of aluminum-silicon composite oxide support was added and impregnated for 5 hours. After that, it was dried at 110℃ for 12 hours and calcined at 450℃ for 5 hours. The catalyst precursor was placed in a hydrogen-nitrogen mixture and the temperature was gradually increased to 280℃ over 10 hours, and then slowly increased to 300℃ over 4 hours. The temperature was then switched to pure hydrogen and kept constant for 20 hours to obtain a nickel-copper catalyst supported on aluminum-silicon oxide.

[0060] The content of active component Cu is 19.2%, Al2O3 is 80%, and SiO2 is 20%, with the mass of the composite oxide support as the denominator. The catalyst is labeled Cat6.

[0061] Catalyst Preparation Example 7

[0062] First, 140.8g of boehmite was added to water to form a suspension. Then, 10mL of a 10% dilute nitric acid aqueous solution was added while stirring. The mixture was subjected to a sol-gel reaction at 90℃ for 20 hours. After drying at 110℃ for 12 hours, it was calcined at 650℃ for 5 hours and then crushed and sieved to obtain an alumina carrier with a mesh size of 20-40.

[0063] 84.2g of nickel nitrate and 8.4g of copper nitrate were first acidified to pH 4.5 with ammonia water, and 100g of alumina support was added. The mixture was impregnated for 5 hours, then dried at 110℃ for 12 hours and calcined at 450℃ for 5 hours. The catalyst precursor was placed in a hydrogen-nitrogen mixture and gradually heated to 280℃ over 10 hours, then slowly heated to 300℃ over 4 hours, and then switched to pure hydrogen gas and kept at a constant temperature for 20 hours to obtain a nickel-copper catalyst supported on aluminum-silicon oxide.

[0064] The content of the active component Ni is 17%, and the content of the co-active component Cu is 2.2%, with the mass of the alumina support as the denominator. The catalyst is labeled Cat7.

[0065] Catalyst Preparation Example 8

[0066] First, the composite carrier Al2O3-SiO2 was prepared by mixing and grinding 112.6g of boehmite and 66.7g of acidic silica sol evenly according to the oxide metric. After adding water to make a suspension, 5mL of dilute nitric acid aqueous solution with a mass percentage of 10% was added while stirring. The sol reaction was carried out at 90℃ for 20 hours, then dried at 110℃ for 12 hours, calcined at 650℃ for 5 hours, and crushed and sieved to obtain 20-40 mesh aluminum-silicon composite oxide.

[0067] 84.2g of nickel nitrate and 8.4g of copper nitrate were first acidified to pH 4.5 with ammonia water, and 100g of alumina support was added. The mixture was impregnated for 5 hours, then dried at 110℃ for 12 hours and calcined at 450℃ for 5 hours. The catalyst precursor was placed in a hydrogen-nitrogen mixture and gradually heated to 280℃ over 10 hours, then slowly heated to 300℃ over 4 hours, and then switched to pure hydrogen gas and kept at a constant temperature for 20 hours to obtain a nickel-copper catalyst supported on aluminum-silicon oxide.

[0068] The content of active component Ni is 17%, co-active component Cu is 2.2%, Al2O3 is 80%, and SiO2 is 20%, with the mass of the composite oxide support as the denominator. The catalyst is labeled Cat8.

[0069] Example of tetrahydrofuran preparation

[0070] Reaction conditions: 50g of the catalyst prepared above was packed into a fixed-bed reactor, and hydrogen reduction was first carried out at 300℃ for 20 hours; the hydrogen pressure in the reactor was controlled at 3MPa, the reaction temperature at 110℃, and the furan space velocity at 0.3h. -1 The reaction is carried out with a hydrogen / furan molar ratio of 15.

[0071] The product distribution was quantitatively analyzed by gas chromatography. The furan conversion rate and tetrahydrofuran selectivity are shown in Table 1. Other major byproducts were butanol and dihydrofuran. Taking Cat3 as an example, the product distribution was: tetrahydrofuran 97.1%, dihydrofuran 0.3%, and n-butanol 2.6%.

[0072] Table 1. Effects of different catalysts on the hydrogenation of furan to tetrahydrofuran.

[0073]

[0074] As shown in Table 1, Cat3 exhibits the best tetrahydrofuran yield. Therefore, 50 g of Cat3 was refilled into the fixed-bed reactor, and the reactor was first reduced with hydrogen at 300 °C for 20 hours, followed by reaction at a space velocity of 0.3 h⁻¹. -1 Under the condition of a hydrogen / furan molar ratio of 15, the effects of reaction temperature and pressure on the conversion rate of furan and the selectivity of tetrahydrofuran were investigated, and the results are shown in Table 2.

[0075] Table 2. Effects of reaction temperature and pressure on furan conversion and tetrahydrofuran selectivity.

[0076]

[0077] Table 2 shows that the reaction temperature was 100–150℃, the pressure was 1.5–5.5 MPa, and the furan space velocity was 0.3 h⁻¹. -1 The highest yield of tetrahydrofuran was achieved under a hydrogen / furan molar ratio of 15.

[0078] Furthermore, under reaction conditions of 115°C and 3.5 MPa, the effects of reaction space velocity and hydrogen / furan molar ratio on furan conversion and tetrahydrofuran selectivity were investigated, as shown in Table 3.

[0079] Table 3. Effects of reaction space velocity and hydrogen / furan molar ratio on furan conversion and tetrahydrofuran selectivity

[0080]

[0081]

[0082] As can be seen from Table 3, when the furan space velocity is 0.2–0.6 h⁻¹ -1 The highest yield of tetrahydrofuran was achieved under the conditions of a hydrogen / furan molar ratio of 10–50, a reaction temperature of 115 °C, and a pressure of 3.5 MPa.

[0083] The data above show that, on the Ni-Cu / Al2O3-SiO2 system catalyst, the 17%Ni-2.2%Cu / 80%Al2O3-20%SiO2 catalyst can achieve highly selective hydrogenation of furan to prepare tetrahydrofuran with a yield of 97.1%.

[0084] In summary, this invention utilizes a nickel-copper catalyst supported on an aluminum-silicon composite oxide, which can achieve a reaction at a hydrogen pressure of 1.5–5.5 MPa, a reaction temperature of 100–150 °C, and a furan space velocity of 0.2–0.6 h⁻¹. -1 The directed catalytic conversion of furan to tetrahydrofuran was achieved under conditions of a hydrogen / furan molar ratio of 10–50. This method can be used in continuous fixed-bed reactors and other similar reactors to achieve highly efficient catalytic hydrogenation of furan. The catalyst is stable, the tetrahydrofuran yield is high, and the processing is simple, making it valuable for industrial production.

[0085] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A process for producing tetrahydrofuran, characterized in that, The process includes the following steps: in the presence of a furan hydrogenation catalyst and hydrogen, furan undergoes a hydrogenation reaction to produce tetrahydrofuran; wherein the reaction temperature is 100℃-150℃, the hydrogen pressure is 1.5MPa-5.5MPa, and the molar ratio of hydrogen to furan is 10-50. The furan hydrogenation catalyst comprises a support and an active component supported on the support. The active component is metallic Ni and Cu, and the support is an Al2O3-SiO2 composite oxide. Based on the mass of the support, the Ni content is 10%-20%, the Cu content is 1%-5%, the Al2O3 content is 70%-90%, and the SiO2 content is 10%-30%. The carrier is prepared by grinding boehmite and acidic silica sol, mixing them evenly, adding water to form a suspension, then adding dilute nitric acid aqueous solution, and carrying out a rheological phase reaction at 80℃-90℃ for 15-20 hours, drying, and calcining to obtain Al2O3-SiO2 composite oxide.

2. The production process of tetrahydrofuran according to claim 1, characterized in that, The mass hourly space velocity (HSV) of furan is 0.2 h⁻¹. -1 -0.6h -1 .

3. The production process of tetrahydrofuran according to claim 1, characterized in that, The reaction temperature was 115℃-130℃, the hydrogen pressure was 3MPa-3.5MPa, and the furan mass hourly space velocity was 0.35h⁻¹. -1 -0.45h -1 .

4. The production process of tetrahydrofuran according to claim 1, characterized in that, The reaction does not use a solvent; and / or the reaction is carried out in a continuous fixed-bed reactor.

5. The production process of tetrahydrofuran according to claim 1, characterized in that, The roasting temperature is 650℃-700℃, and the roasting time is 5-8 hours.

6. The production process of tetrahydrofuran according to any one of claims 1-5, characterized in that, The furan hydrogenation catalyst contains 14%-20% Ni, 1.5%-3% Cu, 77%-87% Al2O3, and 13%-23% SiO2.

7. The production process of tetrahydrofuran according to claim 6, characterized in that, The furan hydrogenation catalyst contains 17% Ni, 2.2% Cu, 80% Al₂O₃, and 20% SiO₂; or The composition is as follows: Ni content is 20%, Cu content is 3%, Al2O3 content is 87%, and SiO2 content is 13%.

8. A production process for tetrahydrofuran according to any one of claims 1-5, characterized in that, The preparation method of the furan hydrogenation catalyst includes the following steps: A mixed aqueous solution containing nickel salt and copper salt was prepared, and the pH value was adjusted to 4-4.

5. The Al2O3-SiO2 composite oxide was placed in the mixed aqueous solution, impregnated for a first time, dried, calcined, and reduced to obtain the Ni-Cu / Al2O3-SiO2 catalyst.

9. The production process of tetrahydrofuran according to claim 8, characterized in that, The first time period is 3-5 hours; and / or, The firing temperature after impregnation is 420℃-450℃, and the firing time is 5-8 hours; and / or, The particle size of the Al2O3-SiO2 composite oxide is 20-40 mesh; and / or, The reduction steps include: placing the catalyst precursor in a hydrogen-nitrogen mixture, gradually increasing the temperature to 280°C over 10 hours, then slowly increasing the temperature to 300°C over 4 hours, switching to pure hydrogen, and maintaining the temperature for 20 hours.

10. The production process of tetrahydrofuran according to claim 8, characterized in that, The nickel salt is at least one of nickel nitrate and nickel acetate; and / or The copper salt is at least one of copper nitrate and copper acetate.

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