Gamma-butyrolactone prepared by continuous hydrogenation of maleic anhydride and preparation method of gamma-butyrolactone

Abstract

The invention relates to gamma-butyrolactone prepared by continuous hydrogenation of maleic anhydride and a preparation method of the gamma-butyrolactone. The method comprises the following steps: continuously feeding a prepared maleic anhydride solution and hydrogen into a fixed bed containing a nickel-copper catalyst for hydrogenation reaction, and feeding an obtained crude product into a separation tower for separation and purification to obtain gamma-butyrolactone. The purity of the obtained gamma-butyrolactone is greater than or equal to 99.99%, and the balance is impurities; the impurities comprise tetrahydrofuran and 1, 4-butanediol; the content of tetrahydrofuran is less than or equal to 0.003%; the content of the 1, 4-butanediol is less than or equal to 0.004%.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, in particular to gamma-butyrolactone prepared by continuous hydrogenation of maleic anhydride and a preparation method thereof. Background Art

[0002] γ-Butyrolactone, also known as 1,4-butyrolactone or 4-hydroxybutyric acid lactone, is a colorless oily liquid with a unique aromatic smell. It is miscible with water and soluble in organic solvents such as methanol, ethanol, acetone, ether and benzene. It is also a solvent with excellent performance. It is often used as an extractant and absorbent in the petroleum industry and as an electrolyte solution in the battery industry. As a chemical intermediate, it is mainly used to synthesize N-methylpyrrolidone, polyvinylpyrrolidone, etc. It can also be used to manufacture high value-added products such as NovoFluoro, Ciprofloxacin, and Interferon.

[0003] The methods for preparing γ-butyrolactone using maleic anhydride in the prior art mainly include maleic anhydride direct hydrogenation method and maleic anhydride esterification hydrogenation method. Among them, the maleic anhydride direct hydrogenation method is to enter the hydrogenation reactor with maleic anhydride and hydrogen under the action of a catalyst to convert it into γ-butyrolactone, while producing a small amount of tetrahydrofuran. The hydrogenation catalyst is mainly a precious metal catalyst and a nickel-based non-metallic catalyst. Among them, the precious metal catalyst has high catalyst activity and excellent selectivity, and plays an important role in the field of catalytic hydrogenation, but due to its high cost, it cannot be used on a large scale. Among non-precious metals, nickel metal has high catalytic activity and selectivity for hydrogen, as well as its relatively low price, and has been widely used in the field of industrial catalytic hydrogenation. The preparation methods of nickel-based catalysts include co-precipitation method, reduction method, sol-gel method, volume impregnation method, etc. The purity of the prepared γ-butyrolactone is closely related to the hydrogenation catalyst used.

[0004] Therefore, there is an urgent need to provide a low-cost nickel-copper catalyst with high strength and high selectivity for preparing high-purity γ-butyrolactone. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a γ-butyrolactone prepared by continuous hydrogenation of maleic anhydride (maleic anhydride) and a preparation method thereof. The present invention adopts a 5-30wt% maleic anhydride dilute solution, which continuously enters a fixed bed hydrogenation reactor to prepare a γ-butyrolactone liquid, which continuously enters a distillation separation tower for separation, and can prepare a γ-butyrolactone product with a purity of ≥99.99%. Maleic anhydride molecules have a C=C bond and two C=O bonds. Under certain catalytic conditions, selective deep hydrogenation of the C=C bonds will sequentially prepare γ-butyrolactone. To prepare high-purity γ-butyrolactone, it is necessary to control the hydrogenation stage where the hydrogenation reaction precisely stays to maintain controllable high-selectivity hydrogenation.

[0006] The present invention is achieved through the following technical solutions:

[0007] The first object of the present invention is to provide a γ-butyrolactone prepared by continuous hydrogenation of maleic anhydride, wherein the purity of the bio-based γ-butyrolactone is ≥99.99%, and the rest is impurities; the impurities include tetrahydrofuran and 1,4-butanediol; the content of the tetrahydrofuran is ≤0.003%; the content of the 1,4-butanediol is ≤0.004%.

[0008] The second object of the present invention is to provide a method for preparing γ-butyrolactone prepared by continuous hydrogenation of maleic anhydride, comprising the following steps:

[0009] (1) preparing maleic anhydride solution;

[0010] (2) continuously introducing the maleic anhydride solution obtained in step (1) and hydrogen into a fixed bed containing a nickel-copper catalyst for hydrogenation reaction to obtain a crude product;

[0011] (3) The crude product obtained in step (2) is placed in a separation tower for separation and purification to obtain γ-butyrolactone.

[0012] In one embodiment of the present invention, in step (1), the mass percentage of maleic anhydride in the maleic anhydride solution is 5wt% to 30wt%.

[0013] In one embodiment of the present invention, in step (1), the solvent of the maleic anhydride solution is selected from one or more of tetrahydrofuran, γ-butyrolactone, diethyl ether, ethyl acetate, ethyl formate and methyl acetate; preferably tetrahydrofuran and / or γ-butyrolactone.

[0014] In one embodiment of the present invention, in step (2), the flow rate of the bio-based succinic acid solution is 0 to 5 mL / min;

[0015] And / or, the flow rate of the hydrogen is 0 to 100 mL / min.

[0016] In one embodiment of the present invention, in step (2), the pressure of the hydrogenation reaction is 1 MPa to 10 MPa; and / or, the temperature of the hydrogenation reaction is 25°C to 100°C; and / or, the system reaction space velocity of the hydrogenation reaction is 0.6 hr -1 ~6.0hr -1 .

[0017] In one embodiment of the present invention, in step (2), the nickel-copper catalyst is obtained by the following preparation method:

[0018] S1, stirring and mixing asphalt and molybdenum disulfide; heat-treating the obtained mixture under oxygen conditions to obtain a porous carbon / molybdenum disulfide material carrier;

[0019] S2, dissolving the nickel precursor compound, the copper precursor compound and the hydrophobic compound in water to obtain a mixed solution;

[0020] S3, impregnating the porous carbon / molybdenum disulfide material carrier obtained in step S1 into the mixed solution obtained in step S2 to obtain a catalyst intermediate;

[0021] S4, aging, drying and reducing the catalyst intermediate obtained in step S3 to obtain the nickel-copper catalyst.

[0022] In one embodiment of the present invention, in step S2, the nickel precursor compound is selected from one or more of nickel chloride, nickel nitrate, nickel sulfate, basic nickel carbonate, nickel acetylacetonate, nickel oxalate, nickel acetate, nickel citrate, nickel hypophosphite, nickel phosphate and nickel formate;

[0023] and / or, the copper precursor compound is selected from one or more of copper chloride, copper nitrate and copper sulfate;

[0024] And / or, the structural formula of the hydrophobic compound is Where n≥6.

[0025] In one embodiment of the present invention, in step S2, the mass ratio of the nickel precursor compound, the copper precursor compound and the hydrophobic compound is 80-99:0.1-20:0.01-1.

[0026] In one embodiment of the present invention, in step S4, the aging conditions are: aging at 50°C to 80°C for 12h to 16h;

[0027] And / or, the drying conditions are: 100° C. to 140° C., and the drying time is 10 h to 14 h.

[0028] In one embodiment of the present invention, in step S4, the reduction conditions are: reduction at 160°C to 200°C for 6h to 10h under hydrogen and normal pressure. ， This makes the nickel-copper catalyst have hydrogenation activity.

[0029] In one embodiment of the present invention, the cluster size of the nickel-copper catalyst is: 80nm-150nm in length, 30nm-100nm in width, and 10nm-30nm in thickness; and the particle strength of the nickel-copper catalyst is ≥400N / cm.

[0030] In one embodiment of the present invention, the nickel loading in the nickel-copper catalyst is 30 wt% to 60 wt%, the copper loading is 1 wt% to 5 wt%, and the content of the hydrophobic compound is 0.01 wt% to 0.2 wt%.

[0031] The porous carbon / molybdenum disulfide carrier of the present invention, due to the layered structural characteristics of molybdenum disulfide, when the carrier is subjected to high temperature treatment, the asphalt will extend along the layered voids, and then undergo dehydration, de-organic matter and other processes at a certain temperature to form a layered carbon structure, which is firmly combined with molybdenum disulfide and produces a large number of pore structures, which is conducive to the dispersion of active metal components. At the same time, this composite carrier structure naturally has a very high mechanical strength, and it is easy to achieve a particle strength of ≥400N / cm, while the particle strength of traditional alumina is difficult to achieve this. The mechanical strength of alumina particles of commercial catalyst carriers can generally reach 100N / cm.

[0032] The above technical solution of the present invention has the following advantages compared with the prior art:

[0033] The present invention provides γ-butyrolactone prepared by continuous hydrogenation of maleic anhydride and a preparation method thereof. The present invention provides γ-butyrolactone by continuously introducing a prepared maleic anhydride solution and hydrogen into a fixed bed containing a nickel-copper catalyst for hydrogenation reaction, and introducing the obtained crude product into a separation tower for separation and purification. The purity of the obtained bio-based γ-butyrolactone is ≥99.99%, and the rest is impurities; the impurities include tetrahydrofuran and 1,4-butanediol; the content of the tetrahydrofuran is ≤0.003%; the content of the 1,4-butanediol is ≤0.004%.

[0034] The catalyst used in the present invention has an ultra-high strength of ≥400N / cm, and the metal is not easy to be lost during the reaction, which plays a key role in the synthesis of high-purity succinic anhydride; it uses porous carbon / molybdenum disulfide as a carrier, and the catalyst carrier itself has a certain hydrogenation activity, which can promote the improvement of reaction activity, play a role in lowering the reaction temperature, improving the reaction selectivity, and then improving the purity of the product. The use of a hydrophobic compound as an additive can make the target product γ-butyrolactone desorb from the catalyst surface as soon as possible, which can accelerate the reaction speed on the one hand, and avoid further reaction of the product on the catalyst surface on the other hand, thereby achieving the goal of a high-purity product. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0036] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods, and the materials, reagents, etc. used are all available from commercial sources unless otherwise specified.

[0037] The detection method used in the present invention is as follows:

[0038] (1) The purity and impurity content of the product were tested by gas chromatography, with a gas chromatography column HP-5 (30m×320μm×0.25μm) and a FID detector. The column temperature conditions were initial temperature 60℃, first-order termination temperature 90℃, heating rate 15℃ / min, maintained for 2min, second-order termination temperature: 230℃, heating rate 10℃ / min, injection port temperature 260℃, split ratio 100:1, injection volume: 0.2μL, hydrogen flow rate: 30mL / min, nitrogen flow rate: 25mL / min. Using acetone as solvent, standard curves of maleic anhydride, succinic anhydride, tetrahydrofuran, γ-butyrolactone and 1,4-butanediol were established.

[0039] (2) Carry out catalyst strength test in accordance with HG / T 2782 standard.

[0040] Example 1

[0041] This embodiment provides a method for preparing γ-butyrolactone by continuous hydrogenation of maleic anhydride, which is as follows:

[0042] (1) Preparation of nickel-copper catalyst: 50.00 g of basic nickel carbonate, 159.5 mL (5 mol / L) of dilute nitric acid solution, 4.58 g of copper nitrate, 0.30 g of sodium dodecyl sulfate, and 500.00 g of deionized water were weighed and stirred at 45° C. until all solids were dissolved to obtain a nickel-copper solution; asphalt and molybdenum disulfide were stirred and mixed in a mass ratio of 1:1, and heat-treated at 300° C. for 4 h under oxygen conditions to obtain a porous carbon / molybdenum disulfide carrier with a pore volume of 0.5 mL / g and a particle size of 5 mm; the obtained porous carbon / molybdenum disulfide carrier was immersed in the nickel-copper solution, and the mixture was aged at 60° C. for 14 h under stirring, and then dried at 120° C. for 12 h, loaded into a tube, and reduced under hydrogen conditions at 200° C. for 6 h to obtain a nickel-copper catalyst.

[0043] (2) Catalytic hydrogenation reaction:

[0044] A tetrahydrofuran solution of maleic anhydride with a mass fraction of 5 wt% was prepared; the maleic anhydride tetrahydrofuran solution with a flow rate of 0.5 mL / min was mixed with hydrogen with a flow rate of 200 mL / min and then continuously entered a 50 mL catalyst-containing hydrogenation tubular reactor at a reaction temperature of 96° C. and a reaction pressure of 2.8 MPa(A), and continuously entered a distillation separation tower to separate and obtain the product γ-butyrolactone.

[0045] Example 2

[0046] This embodiment provides a method for preparing γ-butyrolactone by continuous hydrogenation of maleic anhydride, which is similar to that of embodiment 1, except that:

[0047] The nickel-copper catalyst was prepared by replacing basic nickel carbonate with nickel nitrate.

[0048] The obtained nickel-copper catalyst is used for hydrogenation reaction of maleic anhydride to separate and obtain the product γ-butyrolactone.

[0049] Example 3

[0050] This embodiment provides a method for preparing γ-butyrolactone by continuous hydrogenation of maleic anhydride, which is similar to that of embodiment 1, except that:

[0051] The copper nitrate was replaced by copper chloride to prepare a nickel-copper catalyst.

[0052] The obtained nickel-copper catalyst is used for hydrogenation reaction of maleic anhydride to separate and obtain the product γ-butyrolactone.

[0053] Example 4

[0054] This embodiment provides a method for preparing γ-butyrolactone by continuous hydrogenation of maleic anhydride, which is similar to that of embodiment 1, except that:

[0055] In the catalytic hydrogenation reaction, a tetrahydrofuran solution of 10 wt% maleic anhydride is prepared and catalytic hydrogenation is performed to obtain the product γ-butyrolactone.

[0056] Example 5

[0057] This embodiment provides a method for preparing γ-butyrolactone by continuous hydrogenation of maleic anhydride, which is similar to that of embodiment 1, except that:

[0058] In the catalytic hydrogenation reaction, a 5 wt% γ-butyrolactone solution of maleic anhydride is prepared and catalytic hydrogenation is performed to obtain the product γ-butyrolactone.

[0059] Comparative Example 1

[0060] This comparative example provides a method for preparing γ-butyrolactone by continuous hydrogenation of maleic anhydride, which is as follows:

[0061] (1) Preparation of a nickel-based catalyst: 50.00 g of basic nickel carbonate, 159.5 mL (5 mol / L) of dilute nitric acid solution, 0.30 g of sodium dodecyl sulfate, and 500.00 g of deionized water were weighed and stirred at 45° C. until all solids were dissolved to obtain a nickel solution; asphalt and molybdenum disulfide were stirred and mixed in a mass ratio of 1:1, and heat-treated at 300° C. for 4 h under oxygen conditions to obtain a porous carbon / molybdenum disulfide carrier with a pore volume of 0.5 mL / g and a particle size of 5 mm; the obtained porous carbon / molybdenum disulfide carrier was impregnated in the nickel solution, and the mixture was aged at 60° C. for 14 h under stirring, and then dried at 120° C. for 12 h, loaded into a tube, and reduced at 200° C. for 6 h under hydrogen conditions to obtain a nickel-based catalyst.

[0062] (2) Catalytic hydrogenation reaction:

[0063] A tetrahydrofuran solution of maleic anhydride with a mass fraction of 5 wt% was prepared; the maleic anhydride tetrahydrofuran solution with a flow rate of 0.5 mL / min was mixed with hydrogen with a flow rate of 200 mL / min and then continuously entered a 50 mL catalyst-containing hydrogenation tubular reactor at a reaction temperature of 96° C. and a reaction pressure of 2.8 MPa(A), and continuously entered a distillation separation tower to separate and obtain the product γ-butyrolactone.

[0064] Comparative Example 2

[0065] This comparative example provides a method for preparing γ-butyrolactone by continuous hydrogenation of maleic anhydride, which is as follows:

[0066] (1) Preparation of a nickel-based catalyst: 50.00 g of basic nickel carbonate, 159.5 mL (5 mol / L) of dilute nitric acid solution, 4.58 g of copper nitrate, and 500.00 g of deionized water were weighed and stirred at 45° C. until all solids were dissolved to obtain a nickel-copper solution; asphalt and molybdenum disulfide were stirred and mixed in a mass ratio of 1:1, and heat treated at 300° C. for 4 h under oxygen conditions to obtain a porous carbon / molybdenum disulfide carrier with a pore volume of 0.5 mL / g and a particle size of 5 mm; the obtained porous carbon / molybdenum disulfide carrier was impregnated in the nickel-copper solution, and the mixture was aged at 60° C. for 14 h under stirring, and then dried at 120° C. for 12 h, loaded into a tube, and reduced at 200° C. for 6 h under hydrogen conditions to obtain a nickel-based catalyst.

[0067] (2) Catalytic hydrogenation reaction:

[0068] A tetrahydrofuran solution of maleic anhydride with a mass fraction of 5 wt% was prepared; the maleic anhydride tetrahydrofuran solution with a flow rate of 0.5 mL / min was mixed with hydrogen with a flow rate of 200 mL / min and then continuously entered a 50 mL catalyst-containing hydrogenation tubular reactor at a reaction temperature of 96° C. and a reaction pressure of 2.8 MPa(A), and continuously entered a distillation separation tower to separate and obtain the product γ-butyrolactone.

[0069] Comparative Example 3

[0070] This comparative example provides a method for preparing γ-butyrolactone by continuous hydrogenation of maleic anhydride, which is as follows:

[0071] (1) Preparation of a nickel-based catalyst: 50.00 g of basic nickel carbonate, 159.5 mL (5 mol / L) of dilute nitric acid solution, and 500.00 g of deionized water were weighed and stirred at 45° C. until all solids were dissolved to obtain a nickel solution; asphalt and molybdenum disulfide were stirred and mixed in a mass ratio of 1:1, and heat treated at 300° C. for 4 h under oxygen conditions to obtain a porous carbon / molybdenum disulfide carrier with a pore volume of 0.5 mL / g and a particle size of 5 mm; the obtained porous carbon / molybdenum disulfide carrier was impregnated in the nickel solution, and the mixture was aged at 60° C. for 14 h under stirring, and then dried at 120° C. for 12 h, loaded into a tube, and reduced under hydrogen conditions at 200° C. for 6 h to obtain a nickel-based catalyst.

[0072] (2) Catalytic hydrogenation reaction:

[0073] A tetrahydrofuran solution of maleic anhydride with a mass fraction of 5 wt% was prepared; the maleic anhydride tetrahydrofuran solution with a flow rate of 0.5 mL / min was mixed with hydrogen with a flow rate of 200 mL / min and then continuously entered a 50 mL catalyst-containing hydrogenation tubular reactor at a reaction temperature of 96° C. and a reaction pressure of 2.8 MPa(A), and continuously entered a distillation separation tower to separate and obtain the product γ-butyrolactone.

[0074] Comparative Example 4

[0075] This comparative example provides a preparation method and application of a nickel-based catalyst, which are as follows:

[0076] (1) Preparation of nickel-based catalyst: Weigh 50.00g of basic nickel carbonate, 159.5mL (5mol / L) of dilute nitric acid solution, 4.58g of copper nitrate, 0.30g of sodium dodecyl sulfate, and 500.00g of deionized water and stir at 45°C until all solids are dissolved to obtain a nickel-copper solution; heat treat the asphalt at 300°C for 4h under oxygen conditions to obtain porous carbon with a pore volume of 0.5mL / g and a particle size of 5mm. The obtained porous carbon / molybdenum disulfide carrier is impregnated in the nickel-copper solution, and the mixture is aged at 60°C for 14h under stirring, and then dried at 120°C for 12h, loaded into a tube, and reduced at 200°C for 6h under hydrogen conditions to obtain a nickel-based catalyst.

[0077] (2) Catalytic hydrogenation reaction:

[0078] A tetrahydrofuran solution of maleic anhydride with a mass fraction of 5 wt% was prepared; the maleic anhydride tetrahydrofuran solution with a flow rate of 0.5 mL / min was mixed with hydrogen with a flow rate of 200 mL / min and then continuously entered a 50 mL catalyst-containing hydrogenation tubular reactor at a reaction temperature of 96° C. and a reaction pressure of 2.8 MPa(A), and continuously entered a distillation separation tower to separate and obtain the product γ-butyrolactone.

[0079] Test Case

[0080] The strength of the catalysts prepared in the examples and comparative examples was tested according to the HG / T 2782 standard. The test results are shown in Table 1 below:

[0081] Table 1

[0082] catalyst Strength (N / cm) Example 1 453.3 Example 2 451.8 Example 3 457.2 Example 4 453.3 Example 5 453.3 Comparative Example 1 453.8 Comparative Example 2 454.6 Comparative Example 3 451.5 Comparative Example 4 205.1

[0083] It can be seen from Table 1 that the strength of the supported catalyst prepared in the example exceeds 450 N / cm. By combining high-strength molybdenum disulfide with porous carbon, the strength of the supported catalyst can be greatly improved.

[0084] The product purity and impurity content were tested by gas chromatography. The maleic anhydride conversion rate after 1000h of continuous hydrogenation process experiment is shown in Table 2 below:

[0085] Table 2

[0086]

[0087] It can be seen from Table 2 that the catalyst of the present invention still has high catalytic activity and selectivity after long-term continuous hydrogenation for 1000 hours, which is manifested in that high-purity γ-butyrolactone can be prepared under certain pressure and temperature conditions.

[0088] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A γ-butyrolactone prepared by continuous hydrogenation of maleic anhydride, characterized in that: The purity of the gamma-butyrolactone is ≥99.99%, and the rest are impurities; the impurities include tetrahydrofuran and 1,4-butanediol; the content of the tetrahydrofuran is ≤0.003%; and the content of the 1,4-butanediol is ≤0.004%.

2. The method for preparing γ-butyrolactone prepared by continuous hydrogenation of maleic anhydride according to claim 1, characterized in that: The following steps are involved: (1) preparing maleic anhydride solution; (2) continuously introducing the maleic anhydride solution obtained in step (1) and hydrogen into a fixed bed containing a nickel-copper catalyst for hydrogenation reaction to obtain a crude product; (3) The crude product obtained in step (2) is placed in a separation tower for separation and purification to obtain γ-butyrolactone.

3. The preparation method according to claim 2, characterized in that: In step (1), the mass percentage of maleic anhydride in the maleic anhydride solution is 5wt% to 30wt%.

4. The preparation method according to claim 2, characterized in that: In step (1), the solvent of the maleic anhydride solution is selected from one or more of tetrahydrofuran, γ-butyrolactone, ether, ethyl acetate, ethyl formate and methyl acetate.

5. The preparation method according to claim 2, characterized in that: In step (2), the flow rate of the bio-based succinic acid solution is 0 to 5 mL / min; And / or, the flow rate of the hydrogen is 0 to 100 mL / min.

6. The preparation method according to claim 2, characterized in that: In step (2), the pressure of the hydrogenation reaction is 1 MPa to 10 MPa; and / or, the temperature of the hydrogenation reaction is 25°C to 100°C; and / or, the system reaction space velocity of the hydrogenation reaction is 0.6 hr -1 ~6.0hr -1 .

7. The preparation method according to claim 2, characterized in that: In step (2), the nickel-copper catalyst is obtained by the following preparation method: S1, stirring and mixing asphalt and molybdenum disulfide; heat-treating the obtained mixture under oxygen conditions to obtain a porous carbon / molybdenum disulfide material carrier; S2, dissolving the nickel precursor compound, the copper precursor compound and the hydrophobic compound in water to obtain a mixed solution; S3, impregnating the porous carbon / molybdenum disulfide material carrier obtained in step S1 into the mixed solution obtained in step S2 to obtain a catalyst intermediate; S4, aging, drying and reducing the catalyst intermediate obtained in step S3 to obtain the nickel-copper catalyst.

8. The preparation method according to claim 7, characterized in that: In step S2, the nickel precursor compound is selected from one or more of nickel chloride, nickel nitrate, nickel sulfate, basic nickel carbonate, nickel acetylacetonate, nickel oxalate, nickel acetate, nickel citrate, nickel hypophosphite, nickel phosphate and nickel formate; and / or, the copper precursor compound is selected from one or more of copper chloride, copper nitrate and copper sulfate; And / or, the structural formula of the hydrophobic compound is Where n≥6.

9. The preparation method according to claim 7, characterized in that: In step S2, the mass ratio of the nickel precursor compound, the copper precursor compound and the hydrophobic compound is 80-99:0.1-20:0.01-1.

10. The preparation method according to claim 7, characterized in that: In step S4, the reduction conditions are: reduction at 160° C. to 200° C. for 6 h to 10 h.

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