Bio-based tetrahydrofuran prepared by hydrogenation of bio-based succinic acid and preparation method of bio-based tetrahydrofuran

Abstract

The invention relates to bio-based tetrahydrofuran prepared by hydrogenation of bio-based succinic acid and a preparation method of the bio-based tetrahydrofuran. The method comprises the following steps: continuously feeding a bio-based succinic acid solution and hydrogen into a fixed bed containing a nickel-based catalyst, and carrying out hydrogenation reaction to obtain a crude product; the obtained crude product enters a separation tower for separation and purification, and bio-based tetrahydrofuran is obtained. The purity of the obtained bio-based tetrahydrofuran is greater than or equal to 99.99%, and the balance is impurities; the impurities are gamma-butyrolactone and 1, 4 butanediol; the content of the gamma-butyrolactone is less than or equal to 0.006%, and the content of the 1, 4-butanediol is less than or equal to 0.005%.

Description

Technical Field

[0001] The invention relates to the technical field of chemical raw material synthesis, in particular to bio-based tetrahydrofuran prepared by hydrogenating bio-based succinic acid and a preparation method thereof. Background Art

[0002] Tetrahydrofuran is a heterocyclic organic compound and an important organic and fine chemical raw material. It is widely used in the fields of medicine, chemical industry and daily chemical industry. It is the raw material for the synthesis of polytetrahydrofuran (PTMEG).

[0003] At present, there are three main types of tetrahydrofuran: 1. Furfural method; 2. 1,4-butanediol dehydration method; 3. Hydrogenation method. The furfural method is to separate furan from furfural decarbonylation reaction, and then separate and purify it to prepare tetrahydrofuran. The 1,4-butanediol dehydration method is to dehydrate 1,4-butanediol into a ring under acidic catalyst conditions, and then separate and prepare high-purity tetrahydrofuran. This scheme is the most common method for producing tetrahydrofuran in industry. In this scheme, since 1,4-butanediol contains methyl butanediol, the tetrahydrofuran will contain methyl tetrahydrofuran after dehydration. The hydrogenation method is to hydrogenate maleic anhydride, succinic acid and its derivatives to prepare a mixture of succinic anhydride, tetrahydrofuran, γ-butyrolactone and 1,4-butanediol, and then separate and distill to prepare tetrahydrofuran. The characteristic of this technology is that it can produce succinic anhydride, tetrahydrofuran, γ-butyrolactone and 1,4-butanediol at the same time according to different process conditions. The main disadvantages are that there are many hydrogenation by-products, the separation cost is high, and the maleic anhydride and succinic acid hydrogenation acidic reaction system is generally not acid-resistant, which will lead to active center poisoning and cannot be produced for a long period of time. By adjusting the catalytic active center, high-purity tetrahydrofuran without methyltetrahydrofuran can be prepared by directional and highly selective hydrogenation, which has great industrialization potential. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a bio-based tetrahydrofuran prepared by hydrogenation of bio-based succinic acid and a preparation method thereof. The bio-based tetrahydrofuran of the present invention is prepared by directly hydrogenating a 5wt% to 30wt% bio-based succinic acid solution; the purity of the obtained bio-based tetrahydrofuran is ≥99.99%. The catalyst used is composed of an ordered composite porous carbon / molybdenum disulfide material carrier, a nickel precursor compound active component, and a hydrophobic compound component.

[0005] The present invention is achieved through the following technical solutions:

[0006] The first object of the present invention is to provide a bio-based tetrahydrofuran prepared by hydrogenating bio-based succinic acid, wherein the purity of the bio-based tetrahydrofuran is ≥99.99%, and the rest is impurities; the impurities are γ-butyrolactone and 1,4-butanediol; the content of the γ-butyrolactone is ≤0.006%, and the content of the 1,4-butanediol is ≤0.005%.

[0007] The second object of the present invention is to provide a method for preparing bio-based tetrahydrofuran prepared by hydrogenating bio-based succinic acid, comprising the following steps:

[0008] (1) preparing a bio-based succinic acid solution;

[0009] (2) continuously introducing the bio-based succinic acid solution obtained in step (1) and hydrogen into a fixed bed containing a nickel-based catalyst for hydrogenation reaction to obtain a crude product;

[0010] (3) The crude product obtained in step (2) is placed in a separation tower for separation and purification to obtain bio-based tetrahydrofuran.

[0011] In one embodiment of the present invention, in step (1), the mass percentage of the bio-based succinic acid solution is 5wt% to 30wt%.

[0012] In one embodiment of the present invention, in step (1), the solvent of the bio-based succinic acid solution is selected from one or more of tetrahydrofuran, γ-butyrolactone, ether, ethyl acetate, ethyl formate and methyl acetate; preferably tetrahydrofuran and γ-butyrolactone.

[0013] 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;

[0014] And / or, the flow rate of the hydrogen is 0 to 100 mL / min.

[0015] In one embodiment of the present invention, in step (2), the pressure of the hydrogenation reaction is 1 MPa to 10 MPa;

[0016] And / or, the temperature of the hydrogenation reaction is 25°C to 100°C;

[0017] And / or, the system reaction space velocity of the hydrogenation reaction is 0.6 hr -1 ~6.0hr -1 .

[0018] In one embodiment of the present invention, in step (2), the nickel loading in the nickel-based catalyst is 30 wt% to 60 wt%, and the content of the hydrophobic compound is 0.01 wt% to 0.2 wt%.

[0019] In one embodiment of the present invention, the nickel-based catalyst comprises a catalytically active center cluster composed of nickel and a hydrophobic compound; the size of the catalytically active center cluster is: 80nm to 150nm in length, 30nm to 100nm in width, and 10nm to 30nm in thickness;

[0020] The particle strength of the nickel-based catalyst is ≥400N / cm.

[0021] In one embodiment of the present invention, the nickel loading in the nickel-based catalyst is 30 wt% to 60 wt%, and the content of the hydrophobic compound is 0.01 wt% to 0.2 wt%.

[0022] In one embodiment of the present invention, in step (2), the nickel-based catalyst is obtained by the following preparation method:

[0023] S1. Under oxygen conditions, asphalt and molybdenum disulfide are stirred and mixed, and heat treated to obtain a porous carbon / molybdenum disulfide material carrier;

[0024] S2, dissolving the nickel precursor compound, the hydrophobic compound and the acid solution in water to obtain a mixed solution;

[0025] 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;

[0026] S4, subjecting the catalyst intermediate obtained in step S3 to aging, drying and reduction treatment to obtain the nickel-based catalyst.

[0027] In one embodiment of the present invention, in step S1, the mass average molecular weight of the asphalt is 600 to 2000, and the molecular weight distribution is 1.2 to 1.4;

[0028] And / or, the molybdenum disulfide is a nanosheet structure with 5 to 20 layers.

[0029] In one embodiment of the present invention, in step S1, the mass ratio of the asphalt to molybdenum disulfide is 1:5 to 5:1;

[0030] In one embodiment of the present invention, in step S1, the heat treatment conditions are: heat treatment at 200° C. to 400° C. for 3 h to 8 h.

[0031] In one embodiment of the present invention, in step S2, the acid solution is a 1 mol / L to 6 mol / L nitric acid solution.

[0032] 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;

[0033] And / or, the structural formula of the hydrophobic compound is Where n≥6;

[0034] And / or, the mass ratio of the nickel precursor compound to the hydrophobic compound is 1-90:0.1-1.

[0035] 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;

[0036] And / or, the drying conditions are: 100° C. to 140° C., and the drying time is 10 h to 14 h.

[0037] 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-based catalyst have hydrogenation activity.

[0038] In one embodiment of the present invention, in step S4, the pore volume of the porous carbon / molybdenum disulfide material carrier is 0.2 mL / g to 0.7 mL / g;

[0039] And / or, the particle size of the porous carbon / molybdenum disulfide material carrier is 3 mm to 5 mm;

[0040] And / or, the bulk density of the porous carbon / molybdenum disulfide material carrier is 750 kg / m 3 ~1100kg / m 3 .

[0041] In the nickel-based catalyst of the present invention, nickel exists in the form of atoms and is adsorbed on the carrier by physical adsorption with the hydrophobic compound. The catalytic active center clusters exist in the pores of the carrier, both on the surface and inside.

[0042] The technical solution of the present invention adopts a high-strength molybdenum disulfide / porous carbon carrier, which can avoid the non-precious metal nickel catalytic center from being lost into the product under pressurized hydrogenation conditions, thereby causing the catalyst activity to gradually decrease, thereby ensuring long-term production; in addition, the hydrophobic compound can make the hydrogenation product quickly desorb from the catalyst surface, and then by adjusting the reaction pressure and temperature, the degree of hydrogenation of the two C=O bonds of succinic acid can be controlled to obtain the target product.

[0043] 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.

[0044] Compared with the prior art, the present invention has the following advantages:

[0045] The present invention provides a bio-based tetrahydrofuran prepared by hydrogenating bio-based succinic acid and a preparation method thereof. The present invention continuously introduces a bio-based succinic acid solution and hydrogen into a fixed bed containing a nickel-based catalyst for hydrogenation reaction to obtain a crude product; the obtained crude product enters a separation tower for separation and purification to obtain bio-based tetrahydrofuran. The purity of the obtained bio-based tetrahydrofuran is ≥99.99%, and the rest is impurities; the impurities are γ-butyrolactone and 1,4-butanediol; the content of the γ-butyrolactone is ≤0.006%, and the content of the 1,4-butanediol is ≤0.005%. The catalyst used in the present invention has an ultra-high strength of ≥400N / cm, and the metal is not easily lost during the reaction, which plays a key role in the synthesis of high-purity tetrahydrofuran.

[0046] The catalyst used in the present invention 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 catalyst used in the present invention uses a hydrophobic compound as an additive, which can make the product tetrahydrofuran desorb from the catalyst surface as soon as possible, which can not only accelerate the reaction speed, but also avoid further reaction of the product on the catalyst surface, thereby achieving the ultimate goal of achieving the product purity of the polymerization grade. DETAILED DESCRIPTION

[0047] 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.

[0048] 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.

[0049] 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 an FID detector. The column temperature conditions were initial temperature 60℃, first-order termination temperature 90℃, heating rate 15℃ / min, and holding 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. Acetone was used as the solvent to establish the standard curves of bio-based 1,4-succinic acid, tetrahydrofuran, γ-butyrolactone and 1,4-butanediol.

[0050] The strength test of nickel-based catalyst was carried out in accordance with HG / T 2782 standard.

[0051] Example 1

[0052] This embodiment provides a method for preparing bio-based tetrahydrofuran by hydrogenating bio-based succinic acid, and the specific steps are as follows:

[0053] (1) Preparation of a nickel-based catalyst: 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 prepare a porous carbon / molybdenum disulfide carrier with a pore volume of 0.5 mL / g and a particle size of 5 mm; 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 solution of a nickel-containing precursor compound; the obtained porous carbon / molybdenum disulfide carrier was impregnated in the solution of the nickel-containing precursor compound, and the mixture was aged at 60°C for 14 h under stirring, then dried at 120°C for 12 h, and reduced under hydrogen at 200°C for 6 h to obtain a nickel-based catalyst.

[0054] (2) A tetrahydrofuran solution of bio-based succinic acid containing a nickel-based catalyst; a tetrahydrofuran solution of bio-based succinic acid at a flow rate of 0.5 mL / min and a hydrogen gas at a flow rate of 200 mL / min are mixed and continuously introduced into a 50 mL nickel-based catalyst hydrogenation tubular reactor, the reaction temperature is 145° C., the reaction pressure is 6.8 MPa (A), and continuously introduced into a distillation separation tower to separate and obtain the product tetrahydrofuran.

[0055] Example 2

[0056] This embodiment provides a method for preparing bio-based tetrahydrofuran by hydrogenating bio-based succinic acid, which is similar to Example 1, except that:

[0057] In step (1), basic nickel carbonate is replaced with nickel nitrate;

[0058] The obtained nickel-based catalyst is used for the hydrogenation reaction of bio-based succinic acid to separate and obtain bio-based tetrahydrofuran.

[0059] Example 3

[0060] This embodiment provides a method for preparing bio-based tetrahydrofuran by hydrogenating bio-based succinic acid, which is similar to Example 1, except that:

[0061] During the catalytic hydrogenation process, a tetrahydrofuran solution containing 10 wt% of bio-based succinic acid is prepared, and catalytic hydrogenation is performed to obtain the product tetrahydrofuran.

[0062] Example 4

[0063] This embodiment provides a method for preparing bio-based tetrahydrofuran by hydrogenating bio-based succinic acid, which is similar to Example 1, except that:

[0064] During the catalytic hydrogenation process, a γ-butyrolactone solution containing 5 wt% of bio-based succinic acid is prepared and catalytically hydrogenated to obtain tetrahydrofuran as a product.

[0065] Comparative Example 1

[0066] This comparative example provides a method for preparing bio-based tetrahydrofuran prepared by hydrogenating bio-based succinic acid, and the specific steps are as follows:

[0067] (1) Preparation of nickel-based catalyst: 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 prepare a porous carbon / molybdenum disulfide carrier with a pore volume of 0.5 mL / g and a particle size of 5 mm; 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 solution of a nickel-containing precursor compound; the obtained porous carbon / molybdenum disulfide carrier was impregnated in the solution of the nickel-containing precursor compound, and the mixture was aged at 60°C for 14 h under stirring, then dried at 120°C for 12 h, and reduced under hydrogen at 200°C for 6 h to obtain a nickel-based catalyst.

[0068] (2) preparing a tetrahydrofuran solution of bio-based succinic acid with a mass percentage of 5 wt%; mixing the tetrahydrofuran solution of bio-based succinic acid with a flow rate of 0.5 mL / min and hydrogen with a flow rate of 200 mL / min, and then continuously entering a 50 mL nickel-based catalyst hydrogenation tubular reactor, the reaction temperature is 145° C., the reaction pressure is 6.8 MPa (A), and continuously entering a distillation separation tower to separate and obtain the product tetrahydrofuran.

[0069] Comparative Example 2

[0070] This comparative example provides a method for preparing bio-based tetrahydrofuran prepared by hydrogenating bio-based succinic acid, and the specific steps are as follows:

[0071] (1) Preparation of nickel-based catalyst: Asphalt was heat treated at 300°C for 4 h under oxygen conditions to prepare porous carbon with a pore volume of 0.5 mL / g and a particle size of 5 mm; 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 solution of nickel-containing precursor compounds; the obtained porous carbon was impregnated in the solution of nickel-containing precursor compounds, and the mixture was aged at 60°C for 14 h under stirring, and then dried at 120°C for 12 h, and reduced under hydrogen conditions at 200°C for 6 h to obtain a nickel-based catalyst.

[0072] (2) preparing a tetrahydrofuran solution of bio-based succinic acid with a mass percentage of 5 wt%; mixing the tetrahydrofuran solution of bio-based succinic acid with a flow rate of 0.5 mL / min and hydrogen with a flow rate of 200 mL / min, and then continuously entering a 50 mL nickel-based catalyst hydrogenation tubular reactor, the reaction temperature is 145° C., the reaction pressure is 6.8 MPa (A), and continuously entering a distillation separation tower to separate and obtain the product tetrahydrofuran.

[0073] Test Case

[0074] 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:

[0075] Table 1

[0076] catalyst Strength (N / cm) Example 1 453.8 Example 2 455.2 Example 3 453.8 Example 4 453.8 Comparative Example 1 451.5 Comparative Example 2 200.2

[0077] 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.

[0078] The product purity and impurity content were tested by gas chromatography. The conversion rate of the hydrogenation process after 1000h of continuous experiment is shown in Table 2 below:

[0079] Table 2

[0080]

[0081] 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 tetrahydrofuran can be prepared under certain pressure and temperature conditions.

[0082] 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 bio-based tetrahydrofuran prepared by hydrogenating bio-based succinic acid, characterized in that: The purity of the bio-based tetrahydrofuran is ≥99.99%, and the rest are impurities; the impurities are γ-butyrolactone and 1,4-butanediol; the content of the γ-butyrolactone is ≤0.006%, and the content of the 1,4-butanediol is ≤0.005%.

2. The method for preparing bio-based tetrahydrofuran by hydrogenating bio-based succinic acid according to claim 1, characterized in that: The following steps are involved: (1) preparing a bio-based succinic acid solution; (2) continuously introducing the bio-based succinic acid solution obtained in step (1) and hydrogen into a fixed bed containing a nickel-based 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 bio-based tetrahydrofuran.

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

4. The preparation method according to claim 2, characterized in that: In step (1), the solvent of the bio-based succinic acid 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 loading in the nickel-based catalyst is 30 wt% to 60 wt%, and the content of the hydrophobic compound is 0.01 wt% to 0.2 wt%.

8. The preparation method according to claim 2, characterized in that: In step (2), the nickel-based catalyst is obtained by the following preparation method: S1. Under oxygen conditions, asphalt and molybdenum disulfide are stirred and mixed, and heat treated to obtain a porous carbon / molybdenum disulfide material carrier; S2, dissolving the nickel precursor compound, the hydrophobic compound and the acid solution 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, subjecting the catalyst intermediate obtained in step S3 to aging, drying and reduction treatment to obtain the nickel-based catalyst.

9. The preparation method according to claim 8, 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 structural formula of the hydrophobic compound is Where n≥6; And / or, the mass ratio of the nickel precursor compound to the hydrophobic compound is 1-90:0.1-1.

10. The preparation method according to claim 8, 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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