Method for producing bio-based dihydric alcohol

Abstract

The invention discloses a method for producing bio-based dihydric alcohol. According to the method, bio-based methyl 2-tetrahydrofuroate, tetrahydrofurfuryl propionate and methyl 2-(tetrahydrofuran-2-yl) acetate are used as precursors for dihydric alcohol synthesis, Cu-Ga-Mn / SiO2 or Cu-Ga-Mn / SiO2-Al2O3 is used as a hydrogenation catalyst, cyclic ether ester structures are synchronously activated in a fixed bed reactor, ester group hydrogenation and tetrahydrofuran ring opening are synergistically carried out, and the high-purity tetrahydrofuran is obtained. The reaction path is shortened. The hydrogenation catalyst is prepared by combining a sol-gel method and hydrothermal synthesis through roasting and reduction, active components are uniformly distributed, and the hydrogenation catalyst has excellent hydrogenation activity and structural stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of hydrogenation catalysis, and particularly relates to a method for producing bio-based diols. BACKGROUND

[0002] Diols, as a class of organic compounds containing two hydroxyl groups, are extremely valuable basic raw materials in the chemical industry. Due to their excellent reactivity and chemical stability, diols are widely used in polyurethanes, coatings, adhesives, pharmaceutical intermediates, and high-performance polyesters. With the continuous upgrading and expansion of global chemical industry, the application scenarios of diols are constantly expanding, and the market demand for diols is showing a steady growth trend. From traditional industries to high-end manufacturing fields, the performance advantages of diols make them one of the indispensable raw materials, and their industrial scale gradually increases with the expansion of downstream demand.

[0003] The current methods for preparing diols and the problems existing in the methods are as follows: 1. Summary of existing technologies Diols, as key monomers for high-performance polyesters and polyurethanes, have long relied on fossil raw material routes for industrial production. The main technical paths include adipate hydrogenation, cyclohexanone aldol condensation, and biological fermentation.

[0004] 2. Problems existing in the prior art Bio-based: Bottlenecks in production process and cost, the maturity of existing biological conversion technologies (such as biological fermentation method and enzyme catalysis method) is insufficient, the conversion rate of biomass raw materials and the purity of target products are low, and the purification process is complex, resulting in low production efficiency and high cost.

[0005] Petroleum-based: Dependence on raw materials and risk of resource depletion, adipic acid dimethyl ester and other precursors are completely derived from petroleum cracking products (patent CN102311342A), with the global energy structure shifting towards low carbon, the "unsustainability" of petroleum-based raw materials has become a core shortcoming; high carbon emissions and environmental pollution, the extraction, refining and synthesis of diols from petroleum will produce a large amount of carbon dioxide, sulfides and other pollutants. SUMMARY

[0006] The present application aims at the problems in the prior art and provides a method for producing bio-based diols. The reaction uses bio-based 2-tetrahydrofurfuryl methyl ester, tetrahydrofurfuryl propionate and methyl 2-(tetrahydrofuran-2-yl)acetate as raw materials to prepare bio-based diols under the hydrogenation of a copper-gallium-manganese catalyst. The method uses bio-based 2-tetrahydrofurfuryl methyl ester, tetrahydrofurfuryl propionate and methyl 2-(tetrahydrofuran-2-yl)acetate as precursors for diol synthesis, synchronously activates the cyclic ether ester structure, and makes the hydrogenation of the ester group and the ring-opening of the tetrahydrofuran ring cooperatively proceed, thereby shortening the reaction path. The method uses a Cu-Ga-Mn / SiO2-Al2O3 catalyst, which is prepared by a sol-gel method combined with hydrothermal synthesis, calcination and reduction, has a uniform distribution of active components, and has excellent hydrogenation activity and structural stability.

[0007] The chemical reaction equation is as follows: The present application provides a method for producing bio-based diols.

[0008] To achieve the above object, the present application adopts the following technical scheme: A method for producing bio-based diols, the process is as follows: (1) The catalyst is placed in a fixed bed reactor, and quartz sand is filled above and below the catalyst layer; the catalyst is a Cu-Ga-Mn / SiO2 or Cu-Ga-Mn / SiO2-Al2O3 catalyst; (2) The fixed bed reactor is subjected to pressure retention and leakage test; (3) Hydrogen-nitrogen mixed gas is introduced, the temperature is raised to 200-250 DEG C, and the catalyst is reduced for 5-7 h, and the reduction endpoint is determined by monitoring the tail gas; (4) High-purity hydrogen is introduced into the fixed bed reactor, and the pressure is 5-8 MPa, (5) The ester raw material is prepared into a 50-70% mass concentration methanol solution, which is pumped into the fixed bed reactor; the structure of the ester raw material is as follows: n=0, 1 or 2, and R is methyl, ethyl or propyl; (6) After the gas-liquid at the outlet of the fixed bed reactor is condensed, the liquid phase product is stored in a storage tank; (7) The liquid phase product is discharged through the liquid phase discharge port at the bottom of the storage tank every 3-5 h, and GC-MS analysis is performed; (8) The target product is obtained after the liquid phase product is removed from methanol. The removed methanol can be reused.

[0009] Further, in step (1), in the Cu-Ga-Mn / SiO2 or Cu-Ga-Mn / SiO2-Al2O3 catalyst, Cu accounts for 3-7% of the mass of the carrier, Ga accounts for 1-5% of the mass of the carrier, and Mn accounts for 1-3% of the mass of the carrier; and in the Cu-Ga-Mn / SiO2-Al2O3 catalyst, the mass ratio of the carriers SiO2 and Al2O3 is (6-8):(2-4). Preferably, Cu accounts for 4% of the mass of the carrier, Ga accounts for 2.2% of the mass of the carrier, and Mn accounts for 1.3% of the mass of the carrier.

[0010] Further, the Cu-Ga-Mn / SiO2 or Cu-Ga-Mn / SiO2-Al2O3 catalyst is obtained by the following process: S1, weigh cetyltrimethylammonium bromide as a template agent and dissolve it in an ethanol aqueous solution, drop tetraethyl orthosilicate into the ethanol aqueous solution containing the template agent, and stir to hydrolyze and form a SiO2 sol; then dissolve aluminum isopropylate in ethanol and add it to the sol system or directly to the next step; S2, add copper salt, gallium salt and manganese salt, adjust the pH to 7-8 with a base, continuously stir at 45-55°C for 1-3 hours, form a uniform composite sol, then transfer the composite sol to a reaction kettle, and perform hydrothermal synthesis at 150-170°C for 10-15 hours to obtain a catalyst precursor, and finally, calcine the catalyst precursor at 500-600°C for 2-6 hours.

[0011] Further, in step (5), the hydrogen ester molar ratio of hydrogen gas to ester raw material is (20-50):1.

[0012] Further, in step (5), the space velocity during the reaction is 0.05-0.20 h -1 .

[0013] Further, in step (3), the volume ratio of hydrogen gas to nitrogen gas in the hydrogen-nitrogen mixed gas is 1:(4-6), and the flow rate of hydrogen gas is 30-50 mL / min.

[0014] Further, in step S2, the copper salt is copper nitrate or copper chloride, the gallium salt is gallium nitrate or gallium chloride, the manganese salt is manganese nitrate or manganese chloride, the base is one of ammonia water, sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution and potassium carbonate solution, and the concentration of the sodium hydroxide solution, the potassium hydroxide solution, the sodium carbonate solution and the potassium carbonate solution is 0.1 mol / L-1 mol / L.

[0015] Further, in step S1, the volume ratio of ethanol to water is (1-2):(1-2).

[0016] Preferably, the ester raw material in step (5) is at least one of 2-tetrahydrofurfuryl methyl ester, tetrahydrofurfuryl propionate and 2-(tetrahydrofuran-2-yl) methyl acetate.

[0017] Further, in step (3), when the tail gas moisture is ≤10 ppm, it is determined that the reduction endpoint is reached.

[0018] Compared with the prior art, the present application has the following characteristics: 1. Bio-based 2-tetrahydrofurfuryl methyl ester, tetrahydrofurfuryl propionate and 2-(tetrahydrofuran-2-yl) methyl acetate are used as precursors for the synthesis of diols, and the raw materials are derived from biomass platform compound routes.

[0019] 2. The Cu-Ga-Mn / SiO2-Al2O3 catalyst is prepared by combining sol-gel method and hydrothermal synthesis, and has uniform distribution of active components, high hydrogenation activity and targeted catalytic ability, excellent product selectivity and high stability.

[0020] 3. The ring ether ester structure of 2-tetrahydrofurfuryl methyl ester, tetrahydrofurfuryl propionate and 2-(tetrahydrofuran-2-yl) methyl acetate is used to make the hydrogenation of ester group and the ring-opening of tetrahydrofuran ring proceed cooperatively, thereby shortening the reaction path and reducing the generation of by-products. DETAILED DESCRIPTION

[0021] Example 1 The preparation process of the Cu-Ga-Mn / SiO2-Al2O3 hydrogenation catalyst is as follows: taking the preparation of 100 g of carrier as a benchmark, the Cu-Ga-Mn / SiO2-Al2O3 catalyst is prepared, 120 g of tetraethyl orthosilicate is selected as a silicon source, and 40 g of aluminum isopropoxide is selected as an aluminum source (the mass ratio of SiO2 to Al2O3 is about 7:3). Copper nitrate, gallium nitrate and manganese nitrate are taken as active component precursors, and the three are weighed according to the mass ratio of Cu:Ga:Mn of 4:2.2:1.3, and the total mass of the active components (the total mass of Cu, Ga and Mn) accounts for 7.5% of the mass of the carrier. 8 g of cetyltrimethylammonium bromide is weighed as a template agent and dissolved in 200 mL of an ethanol aqueous solution (the volume ratio of ethanol to water is 1:1). The tetraethyl orthosilicate is slowly dropped into the ethanol aqueous solution containing the template agent, and the stirring hydrolysis forms a SiO2 sol; then the aluminum isopropoxide is dissolved in a small amount of ethanol and added to the sol system. Subsequently, the mixed solution of copper nitrate, gallium nitrate and manganese nitrate prepared according to the proportion is added to the sol, and the pH is adjusted to 7-8 with ammonia water (mass fraction of 10%-25%), and the stirring is continuously carried out at 50°C for 2 hours to form a uniform composite sol. Then the composite sol is transferred to a reaction kettle, and hydrothermal synthesis is carried out at 160°C for 12 hours to obtain a catalyst precursor. Finally, the precursor is calcined in a muffle furnace at 550°C for 4 hours.

[0022] Example 2 A method for producing 1,6-hexanediol, the process is as follows: (1) The catalyst of Example 1 is broken into 1-2mm in size, and 40g is loaded into a 316L stainless steel fixed bed reactor, with a catalyst bed height of 13.5cm, and 1-2cm high quartz sand (20-40 mesh) is loaded on both the top and bottom; (2) The fixed bed reactor is subjected to pressure retention and leakage test; (3) A mixture of hydrogen and nitrogen gas (nitrogen 200mL / min, hydrogen 40mL / min) is introduced, and the temperature is raised to 220°C and kept constant for 6h to reduce, and the end point of reduction is determined by monitoring the tail gas moisture (≤10ppm); (4) High-purity hydrogen (purity ≥99.9%) is continuously introduced to make the pressure of the fixed bed reactor 6MPa, and the temperature of the reactor is adjusted to 160-190°C; (5) 2-(tetrahydrofuran-2-yl) methyl acetate is prepared into a 60% mass concentration methanol solution, which is pumped into the fixed bed reactor by a high-pressure metering pump, so that the molar ratio of hydrogen to ester is 30:1, and the space velocity (mass ratio of feedstock to catalyst in 1 hour) is 0.1h -1 .

[0023] (6) The gas-liquid at the outlet of the fixed bed reactor is subjected to three-stage condensation device, and the liquid phase product is stored in a storage tank; (7) The liquid phase product is discharged through the liquid phase outlet at the bottom of the storage tank every 4h, and GC-MS analysis is carried out.

[0024] (8) The target product is obtained after removing the methanol from the liquid phase product. The removed methanol can be reused.

[0025] Table 1 is the results of preparing 1,6-hexanediol by catalytic hydrogenation of methyl tetrahydrofuran acetate at different temperatures As can be seen from Table 1, under the same other reaction conditions, the preferred reaction temperature in the range of 160-190°C is 180°C, at which the conversion rate reaches more than 99% and the yield is 94%.

[0026] Example 3 Table 2 is the results of producing 1,6-hexanediol by catalytic hydrogenation of 2-(tetrahydrofuran-2-yl) methyl acetate at different pressures (temperature 180°C, molar ratio of hydrogen to ester 30:1, space velocity 0.1h -1 , 60% mass concentration 2-(tetrahydrofuran-2-yl) methyl acetate in methanol, process same as Example 2) As shown in Table 2, when other reaction conditions are the same, the conversion rate and yield first increase and then gradually stabilize with the increase of pressure in the range of 5-8 MPa, and the reaction is not affected by the increase of pressure after 7 MPa, and the preferred reaction pressure is 7 MPa.

[0027] Example 4 Table 3 shows the results of preparing 1,6-hexanediol by catalytic hydrogenation of methyl 2-(tetrahydrofuran-2-yl)acetate at different hydrogen-ester molar ratios (temperature 180℃, pressure 6 MPa, space velocity 0.1 h -1 , 60% mass concentration of methyl 2-(tetrahydrofuran-2-yl)acetate in methanol, process same as Example 2) As shown in Table 3, when other reaction conditions are the same, the hydrogen-ester ratio has little effect on the reaction in the range of 20:1 to 50:1, and therefore the preferred hydrogen-ester ratio is 30:1.

[0028] Example 5 Table 4 shows the results of preparing 1,6-hexanediol by catalytic hydrogenation of methyl 2-(tetrahydrofuran-2-yl)acetate at different space velocities (temperature 180℃, pressure 6 MPa, hydrogen-ester molar ratio 30:1, 60% mass concentration of methyl 2-(tetrahydrofuran-2-yl)acetate in methanol, process same as Example 2) As shown in Table 4, when other reaction conditions are the same, the preferred space velocity is 0.1 h -1 in the range of 0.05-0.20 h -1 , at which time the reaction is completely converted and the reaction yield is 96%.

[0029] Example 6 A method for producing 1,5-pentanediol, the process being as follows: (1) The catalyst of Example 1 is crushed to a particle size of 1-2 mm, and 40 g is loaded into a 316L stainless steel fixed bed reactor, with 1-2 cm high quartz sand (20-40 mesh) loaded on the top and bottom of the catalyst bed, and the height of the catalyst bed being 13.5 cm; (2) The fixed bed reactor is subjected to pressure retention and leakage test; (3) Nitrogen-hydrogen mixed gas (nitrogen 200 mL / min, hydrogen 40 mL / min) is introduced, and the temperature is raised to 220℃ and kept constant for 6 h for reduction, and the end point of reduction is determined by monitoring the tail gas moisture (≤10 ppm); (4) High-purity hydrogen (purity ≥99.9%) is continuously introduced to make the pressure of the reactor 6 MPa, and the temperature of the reactor is adjusted to 160-190℃; (5) 2-tetrahydrofurfuryl methyl ester was prepared into a 60% mass concentration methanol solution, which was pumped into the fixed bed reactor by a high-pressure metering pump, so that the molar ratio of hydrogen ester was 30:1, and the space velocity was 0.1 h -1 ; (6) The gas-liquid at the reaction outlet of the fixed bed reactor was subjected to three-stage condensation device, and the liquid phase product was stored in a storage tank; (7) The liquid phase product was discharged through the bottom discharge port of the storage tank every 4 h, and was subjected to GC-MS analysis; (8) The target product was obtained after the liquid phase product was subjected to methanol removal. The removed methanol can be reused.

[0030] Table five is the results of preparing 1,5-pentanediol by catalytic hydrogenation of 2-tetrahydrofurfuryl methyl ester at different temperatures It can be seen from Table five that when other reaction conditions are the same, the preferred reaction temperature in the range of 160-190°C is 170°C, at which the conversion rate is above 99% and the yield is 94%.

[0031] Example 7 Table six is the results of preparing 1,5-pentanediol by catalytic hydrogenation of 2-tetrahydrofurfuryl methyl ester at different pressures (temperature 180°C, molar ratio of hydrogen ester 30:1, space velocity 0.1 h -1 , 60% mass concentration 2-tetrahydrofurfuryl methyl ester methanol solution, process same as Example 6) It can be seen from Table six that when other reaction conditions are the same, with the increase of pressure in the range of 5-8 MPa, the conversion rate and the yield first increase and then gradually stabilize, and the pressure has little effect on the reaction after 7 MPa, and the preferred reaction pressure is 7 MPa.

[0032] Example 8 Table seven is the results of preparing 1,5-pentanediol by catalytic hydrogenation of 2-tetrahydrofurfuryl methyl ester at different molar ratios of hydrogen ester (temperature 180°C, pressure 6 MPa, space velocity 0.1 h -1 , 60% mass concentration 2-tetrahydrofurfuryl methyl ester methanol solution, process same as Example 6) It can be seen from Table seven that when other reaction conditions are the same, the molar ratio of hydrogen ester has little effect on the reaction in the range of 20:1 to 50:1, and therefore the preferred molar ratio of hydrogen ester is 30:1.

[0033] Example 9 Table 8 is the result of the catalytic hydrogenation of 2-tetrahydrofurfuryl propionate to produce 1,5-pentanediol at different space velocities (temperature 180°C, pressure 6 MPa, hydrogen to ester molar ratio 30:1, 60% mass concentration of 2-tetrahydrofurfuryl propionate in methanol, process same as Example 6) As can be seen from Table 8, when other reaction conditions are the same, the preferred space velocity is 0.1 h -1 in the range of 0.05 to 0.20 h -1 , at which time the reaction is completely converted and the reaction yield is 95%.

[0034] Example 10 A method for producing 1,5-pentanediol, the process is as follows: (1) The catalyst of Example 1 is crushed to a particle size of 1 to 2 mm, and 40 g is loaded into a 316L stainless steel fixed bed reactor, with a catalyst bed height of 13.5 cm, and 1 to 2 cm high quartz sand (20 to 40 mesh) is loaded on the top and bottom of the fixed bed reactor; (2) The fixed bed reactor is subjected to pressure retention and leakage test; (3) A mixture of hydrogen and nitrogen gas (nitrogen 200 mL / min, hydrogen 40 mL / min) is introduced, and the temperature is raised to 220°C and kept constant for 6 hours to reduce, and the end point of reduction is determined by monitoring the tail gas moisture (≤10 ppm); (4) High-purity hydrogen gas (purity ≥99.9%) is continuously introduced to make the pressure of the reactor 6 MPa, and the temperature of the fixed bed reactor is adjusted to 160 to 190°C; (5) Tetrahydrofurfuryl propionate is prepared into a 60% mass concentration methanol solution, which is pumped into the fixed bed reactor by a high-pressure metering pump, so that the hydrogen to ester molar ratio is 30:1, and the space velocity is 0.1 h -1 ; (6) The gas-liquid at the outlet of the fixed bed reactor is subjected to three-stage condensation device, and the liquid phase product is stored in a storage tank; (7) The liquid phase product is discharged through the bottom outlet of the storage tank every 4 hours, and subjected to GC-MS analysis; (8) The target product is obtained after the liquid phase product is subjected to methanol removal. The removed methanol can be reused.

[0035] Table 9 is the result of the catalytic hydrogenation of tetrahydrofurfuryl propionate to produce 1,5-pentanediol at different temperatures As can be seen from Table 9, when other reaction conditions are the same, the preferred reaction temperature is 180°C in the range of 160 to 190°C, at which time the conversion rate is more than 99% and the yield is 93%.

[0036] Example 11 Table 10: Results of catalytic hydrogenation of tetrahydrofurfuryl propionate to 1,5-pentanediol at different pressures (temperature 180°C, hydrogen ester molar ratio 30:1, space velocity 0.1 h -1 , 60% mass concentration of tetrahydrofurfuryl propionate in methanol, process same as Example 10) As can be seen from Table 10, under the same other reaction conditions, the conversion and yield increase with the increase of pressure in the range of 5-8 MPa, and the preferred reaction pressure is 8 MPa.

[0037] Example 12 Table 11: Results of catalytic hydrogenation of tetrahydrofurfuryl propionate to 1,5-pentanediol at different hydrogen ester molar ratios (temperature 180°C, pressure 6 MPa, space velocity 0.1 h -1 , 60% mass concentration of tetrahydrofurfuryl propionate in methanol, process same as Example 10) As can be seen from Table 11, under the same other reaction conditions, the hydrogen ester ratio has little effect on the reaction in the range of 20:1 to 50:1 of hydrogen ester molar ratio, and therefore the preferred hydrogen ester ratio is 30:1.

[0038] Example 13 Table 12: Results of catalytic hydrogenation of tetrahydrofurfuryl propionate to 1,5-pentanediol at different space velocities (temperature 180°C, pressure 6 MPa, hydrogen ester molar ratio 30:1, 60% mass concentration of tetrahydrofurfuryl propionate in methanol, process same as Example 10) As can be seen from Table 12, under the same other reaction conditions, the preferred space velocity in the range of 0.05-0.20 h -1 is 0.1 h -1 , at which the reaction is completely converted and the reaction yield is 95%.

[0039] Any changes or alternatives that can be easily conceived by those skilled in the art within the technical scope reported in the present application shall be included in the protection scope of the present application. Therefore, the protection scope of the present application shall not be limited to the above examples, but shall be subject to the protection scope defined in the claims.

Claims

1. A method of producing a bio-based diol, characterized by, The process is as follows: (1) The catalyst is placed in a fixed bed reactor, and quartz sand is filled on the upper and lower layers of the catalyst layer; the catalyst is Cu-Ga-Mn / SiO2 or Cu-Ga-Mn / SiO2-Al2O3 catalyst; (2) The fixed bed reactor is subjected to pressure retention and leakage test; (3) The hydrogen-nitrogen mixed gas is introduced, and the temperature is raised to 200-250°C for 5-7h to reduce the catalyst, and the reduction endpoint is determined by monitoring the tail gas moisture; (4) High-purity hydrogen gas is introduced into the fixed bed reactor, and the pressure is 5-8MPa, (5) The ester raw material is prepared into a 50-70% mass concentration methanol solution and pumped into a fixed bed reactor. The structural formula of the ester raw material is as follows: , n = 0, 1 or 2, and R is methyl, ethyl or propyl. (6) After the gas and liquid at the outlet of the fixed bed reactor are condensed, the liquid phase product is stored in a storage tank; (7) The liquid phase product is discharged through the liquid phase outlet at the bottom of the storage tank every 3-5h, and GC-MS analysis is performed; (8) The target product is obtained after removing methanol from the liquid phase product.

2. The method of producing a bio-based diol according to claim 1, characterized in that, In step (1), in the Cu-Ga-Mn / SiO2 or Cu-Ga-Mn / SiO2-Al2O3 catalyst, Cu accounts for 3-7% of the mass of the carrier, Ga accounts for 1-5% of the mass of the carrier, and Mn accounts for 1-3% of the mass of the carrier; the mass ratio of SiO2 and Al2O3 in the Cu-Ga-Mn / SiO2-Al2O3 catalyst is (6-8):(2-4).

3. The method of producing a bio-based diol according to claim 1 or 2, characterized in that, The Cu-Ga-Mn / SiO2 or Cu-Ga-Mn / SiO2-Al2O3 catalyst is obtained by the following process: S1, hexadecyl trimethyl ammonium bromide is weighed as a template agent and dissolved in an ethanol aqueous solution, tetraethyl orthosilicate is added to the ethanol aqueous solution containing the template agent, and the mixture is stirred to form a SiO2 sol; then aluminum isopropylate is dissolved in ethanol and added to the sol system or directly to the next step; S2, copper salt, gallium salt and manganese salt are added, the pH is adjusted to 7-8 with a base, and the mixture is continuously stirred at 45-55°C for 1-3 hours to form a uniform composite sol, then the composite sol is transferred to a reaction kettle, and hydrothermal synthesis is carried out at 150-170°C for 10-15 hours to obtain a catalyst precursor, finally, the catalyst precursor is calcined at 500-600°C for 2-6 hours to obtain the catalyst.

4. The method of producing a bio-based diol according to claim 1, wherein, In step (5), the hydrogen ester molar ratio of hydrogen gas to ester raw material is (20-50):

1.

5. The method of producing a bio-based diol according to claim 1, wherein, In step (5), the space velocity at the time of reaction is 0.05 to 0.20 h -1 .

6. The method of producing a bio-based diol according to claim 1, wherein, In step (3), the volume ratio of hydrogen gas to nitrogen gas in the hydrogen-nitrogen mixed gas is 1:(4-6), and the flow rate of hydrogen gas is 30-50 mL / min.

7. The method of producing a bio-based diol according to claim 3, wherein, In step S2, the copper salt is copper nitrate or copper chloride, the gallium salt is gallium nitrate or gallium chloride, the manganese salt is manganese nitrate or manganese chloride, and the base is one of ammonia water, sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution and potassium carbonate solution, and the concentration of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution and potassium carbonate solution is 0.1 mol / L-1 mol / L.

8. The method of producing a bio-based diol according to claim 3, wherein, In step S1, the volume ratio of ethanol to water is (1-2):(1-2).

9. The method of producing a bio-based diol according to claim 1, wherein, In step (5), the ester raw material is at least one of 2-tetrahydrofurfuryl methyl ester, propionic acid tetrahydrofurfuryl ester and 2-(tetrahydrofuran-2-yl) methyl acetate.

10. The method of producing a bio-based diol according to claim 1, wherein, In step (3), when the tail gas moisture is ≤10ppm, the reduction endpoint is determined.

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