A method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene

Abstract

The present invention provides a method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene, and belongs to the technical field of organic chemistry. The method comprises: (1) hydrocyanation of 1,3-butadiene; (2) secondary hydrocyanation reaction. Under the combined action of a suitable catalyst and a ligand, the present invention can greatly improve the reaction yield and selectivity of continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene, and the ligand is stable and not easy to hydrolyze, and the catalyst is chemically stable and easy to separate and regenerate, thereby reducing the reaction cost, and the preparation method of the catalyst and the ligand is simple, and the raw material source is wide, and the method has broad application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of organic chemistry, and in particular to a method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene. Background Art

[0002] At present, adiponitrile is an important organic synthesis intermediate in industry, mainly used in the production of nylon 66. Traditional adiponitrile production processes mainly include ammoxidation and acrylonitrile hydrolysis, but these methods generally have problems such as high energy consumption, many by-products, and serious environmental pollution. In recent years, with the enhancement of environmental awareness and technological progress, the development of efficient and low-pollution new adiponitrile production processes has become a research hotspot. Among them, the preparation of adiponitrile by 1,3-butadiene hydrocyanation has attracted widespread attention due to its mild reaction conditions, good selectivity, and environmental friendliness.

[0003] The existing methods for preparing adiponitrile by hydrocyanation of 1,3-butadiene mainly include batch reactors and fixed bed reactors. The batch reactor realizes the reaction by periodic feeding and unloading. Although the operation is simple, it is difficult to ensure the stability of product quality due to the large differences between batches. The fixed bed reactor realizes continuous reaction through a fixed layer of catalyst, which has a high conversion rate and yield, but there are problems such as large mass transfer resistance and easy deactivation of catalyst. Regardless of which method is used, it fails to effectively solve the problems of mass transfer and heat transfer, thereby limiting the further improvement of reaction rate and yield.

[0004] At present, there are many patents that disclose the preparation method of adiponitrile and the method of preparing the corresponding catalyst, in which a large number of organic phosphorus ligands, especially phosphites, are used to catalyze this type of hydrocyanation reaction. Monophosphites have good activity, but the positive / iso-selectivity (about 1:1) for terminal hydrocyanation compounds needs to be improved. When triphenylphosphine is introduced as a ligand into the nickel-catalyzed hydrocyanation reaction, monophosphites are added to catalyze the reaction, in which the unique electronic effect of monophosphites (weak σ-electron donor, strong π-electron acceptor) accelerates the combination of the coordinated nickel catalyst active intermediate with the olefin substrate, thereby accelerating the hydrocyanation reaction rate. At the same time, phosphites are easy to prepare and stable to sulfides and oxides, which is also an advantage compared with trivalent phosphine ligands. However, monophosphites are unstable in the reaction system and are prone to hydrolysis and alcoholysis, which affects their use as catalyst ligands. Summary of the invention

[0005] The purpose of the present invention is to provide a method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene, which greatly improves the reaction yield and selectivity of continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene, and the ligand is stable and not easy to hydrolyze, the catalyst is chemically stable and easy to separate and regenerate, and the reaction cost is reduced. The preparation method of the catalyst and the ligand is simple, the raw material source is wide, and the method has broad application prospects.

[0006] The technical solution of the present invention is achieved in this way:

[0007] The present invention provides a method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene, comprising the following steps:

[0008] (1) Hydrocyanation of 1,3-butadiene: Under the protection of inert gas, the catalyst and phosphine ligand are stirred and mixed, and then dehydrated 1,3-butadiene and hydrocyanic acid are added, and the reaction is heated and pressurized to obtain the product, and the catalyst is separated by a magnet;

[0009] (2) Secondary hydrocyanation reaction: adding a catalyst, a phosphine ligand and a Lewis acid to the product of step (1), heating and stirring under inert gas protection, adding hydrocyanic acid, keeping the temperature for reaction, collecting unreacted hydrocyanic acid, 3-pentenenitrile, product adiponitrile and other by-products by vacuum distillation, separating hydrocyanic acid and 3-pentenenitrile, and then re-entering step (2) to continue the reaction, purifying the product adiponitrile to obtain the final product, and carrying out continuous reaction in a single-pot cycle experimental mode; the structure of the phosphine ligand is shown in Formula I:

[0010]

[0011] Formula I.

[0012] As a further improvement of the present invention, the temperature of the heating and pressurizing reaction in step (1) is 90-100°C, the pressure is 13-17 bar, the time is 1-2h, and the mass ratio of the catalyst, phosphine ligand, 1,3-butadiene and hydrocyanic acid is 3-4:60-70:400-420:200-210.

[0013] As a further improvement of the present invention, in step (2), the concentrations of the catalyst, phosphine ligand and Lewis acid in the product are 180-200 mg / L, 3-4 g / L and 300-500 mg / L respectively, the mass ratio of hydrocyanic acid to the product is 5-7:4-6, the heating temperature is 80-95° C., the insulation reaction time is 4-6 h, and the Lewis acid is ferric chloride.

[0014] As a further improvement of the present invention, the preparation method of the catalyst is as follows:

[0015] S1. Preparation of nano-magnetic ferroferric oxide: dissolving ferric chloride and ferrous chloride in water, adding an emulsifier to obtain an aqueous solution; dropping the aqueous solution into fish oil, emulsifying, adding ammonia water to adjust the pH value under the protection of inert gas, heating and stirring to react, centrifuging, washing, drying, and calcining to obtain nano-magnetic ferroferric oxide;

[0016] S2. Coated SiO2: Add nano-magnetic ferroferric oxide to ethanol, add alkyl orthosilicate, stir and disperse evenly, add ammonia and water dropwise, stir to react, separate the magnet, wash, dry, and calcine to obtain SiO2-coated nano-magnetic ferroferric oxide;

[0017] S3. Preparation of fullerene alcohol: fullerene was dissolved in m-xylene, alkali solution, tetrabutylammonium hydroxide solution and hydrogen peroxide were added dropwise, the reaction was stirred, the liquid was separated, the lower liquid was collected, ethanol was added for precipitation, the solid was collected, washed, and dried to obtain fullerene alcohol;

[0018] S4. Modification: adding fullerene alcohol, phytic acid, SiO2-coated nanomagnetic ferroferric oxide, and potassium dihydrogen phosphate to water, hydrothermally reacting, separating with a magnet, washing, and drying to obtain modified nanoparticles;

[0019] S5. Impregnation: dissolving nickel salt and rhodium salt in water, adding modified nanoparticles, impregnating, separating with a magnet, and drying to obtain an impregnated material;

[0020] S6. Reduction: Add the impregnated material into a sodium borohydride aqueous solution, stir the reaction, separate with a magnet, wash, and dry to obtain a catalyst.

[0021] As a further improvement of the present invention, the mass ratio of ferric chloride, ferrous chloride and emulsifier in step S1 is 3.24:1.26:0.2-0.3, the emulsifier is selected from at least one of Tween-20, Tween-40, Tween-60, Tween-80 and Tween-85, the pH value is adjusted to 10-12 by dripping ammonia water, the temperature of the heating and stirring reaction is 85-95°C, the time is 3-5h, the temperature of the calcination is 450-550°C, and the time is 3-5h; the mass ratio of nano-magnetic ferrosilicate, ethanol, alkyl orthosilicate, ammonia water and water in step S2 is 10:70-100:5-7:8-10:3-5, the alkyl orthosilicate is methyl orthosilicate or ethyl orthosilicate, the stirring reaction time is 10-12h, and the calcination time is 500-600°C, and the time is 1-3h.

[0022] As a further improvement of the present invention, in step S3, the mass ratio of fullerene, alkali solution, tetrabutylammonium hydroxide solution and hydrogen peroxide is 0.5-1:15-20:15-20:30-40, the alkali solution is 2-4 mol / L NaOH or KOH solution, the concentration of tetrabutylammonium hydroxide solution is 10-15wt%, the concentration of hydrogen peroxide is 25-35wt%, and the stirring reaction time is 2-4h; in step S4, the mass ratio of fullerol, phytic acid, SiO2-coated nanomagnetic ferrosoferric oxide and potassium dihydrogen phosphate is 2-3:0.5-1:10:0.1-0.2, the temperature of the hydrothermal reaction is 140-160°C, and the time is 9-12h.

[0023] As a further improvement of the present invention, the mass ratio of the nickel salt, the rhodium salt and the modified nanoparticles in step S5 is 3-5:1-2:7-10, the nickel salt is selected from at least one of nickel chloride, nickel sulfate and nickel nitrate, the rhodium salt is selected from at least one of rhodium chloride, rhodium nitrate and rhodium sulfate, and the impregnation time is 12-15h; the concentration of the sodium borohydride aqueous solution in step S6 is 0.5-1wt%, the mass ratio of the impregnated material and the sodium borohydride aqueous solution is 1-2:200, and the stirring reaction time is 30-50min.

[0024] As a further improvement of the present invention, the preparation method of the phosphine ligand is as follows:

[0025] T1. Preparation of dibornyl terephthalate: exo-2-endo-3-norbornanediol and terephthalic acid are added to toluene, a catalyst is added, the mixture is heated under reflux, and the mixture is separated and purified by column chromatography to obtain an intermediate having the following structure: ;

[0026] T2. Preparation of phosphine ligand: Under the protection of inert gas, add triethylamine and phosphorus trichloride to toluene, cool down, add phenol, keep warm and stir, then add intermediate, keep warm and continue to react, warm to room temperature and stir to react, filter, separate and purify by column chromatography to obtain phosphine ligand.

[0027] As a further improvement of the present invention, the molar ratio of exo-2-endo-3-norbornanediol to terephthalic acid in step T1 is 2-2.1:1, the amount of the catalyst added is 2-3wt% of the total mass of the system, the catalyst is concentrated sulfuric acid or p-toluenesulfonic acid, and the heating reflux reaction time is 8-10h.

[0028] As a further improvement of the present invention, the molar ratio of triethylamine, phosphorus trichloride, phenol and intermediate in step T2 is 6-8:1:1.9-2:1-1.1, the cooling temperature is -55 to -60°C, the time of heat preservation and stirring is 2-4h, the time of heat preservation and continued reaction is 1-2h, and the time of heating to room temperature and stirring the reaction is 0.5-1.5h.

[0029] The present invention has the following beneficial effects:

[0030] The invention prepares a nanoparticle with magnetic ferroferric oxide as a core and a layer of silicon dioxide coated on the surface, so that the catalyst has magnetism and is easy to separate and regenerate. At the same time, the nanoparticle has a large specific surface area, and is further loaded with polyhydroxyl fullerol on the surface. The fullerol has a unique electronic structure and can regulate the electronic structure of the metal catalyst through a π-conjugated system. The electron-withdrawing property of the fullerol induces charge redistribution at the interface, and significantly improves the catalytic performance. In addition, the spherical structure of the fullerol and the hydroxyl groups on the surface provide a good anchoring effect, and can evenly disperse the metal nanoparticles. After being fixed on the surface of the SiO2-coated nanomagnetic ferroferric oxide, the metal is conveniently deposited in situ, and the particle aggregation is prevented, so that a nano-scale metal catalyst is obtained. The hydroxyl groups form coordination bonds with the metal nanoparticles, and the loading amount of the metal catalyst is greatly improved. The composite catalysis of nickel and rhodium is adopted, and the catalytic activity is further improved. The composite of nickel and rhodium can effectively prevent the agglomeration of metal particles, thereby increasing the number of active sites. Rhodium, as a noble metal, can regulate the electronic state of nickel through electron transfer or charge redistribution, making it more conducive to the adsorption and activation of reactants. The catalyst provides abundant reaction active sites, thereby greatly improving the activity of the catalyst. At the same time, the catalyst prepared by the present invention has high chemical stability and thermal stability, and can maintain stable structure and performance under various reaction conditions.

[0031] The invention prepares a phosphine ligand, which mainly uses a diol structure obtained by reacting exo-2-endo-3-norbornanediol with a chiral structure with terephthalic acid, and reacts with phosphorus trichloride to obtain the phosphine ligand. A metal atom and a coordinated atom P center form a suitable angle, and electrons are transferred through conjugation effect, field effect, induction effect and the like. In addition, the space hindrance caused by the proximity of atoms or groups to each other and the tension in the molecule caused by the deviation from the normal bond angle form the most suitable complex, thereby greatly promoting the reaction and improving the reaction yield and selectivity.

[0032] The invention can greatly improve the reaction yield and selectivity of continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene under the joint action of suitable catalyst and ligand, and the ligand is stable and not easy to hydrolyze, and the catalyst is chemically stable and easy to separate and regenerate, thereby reducing the reaction cost, and the preparation method of the catalyst and the ligand is simple, the raw material source is wide, and the invention has broad application prospects. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Preparation Example 1 Preparation of Catalyst

[0035] The following steps are involved:

[0036] S1. Preparation of nano-magnetic ferroferric oxide: 3.24 g ferric chloride and 1.26 g ferrous chloride were dissolved in 200 mL water, and 0.2 g Tween-20 was added to obtain an aqueous solution; the aqueous solution was added dropwise into 500 mL fish oil, and emulsified at 8000 r / min for 15 min. Under nitrogen protection, ammonia water was added dropwise to adjust the pH value to 10, heated to 85°C, stirred for reaction for 3 h, centrifuged, washed, dried, and calcined at 450°C for 3 h to obtain nano-magnetic ferroferric oxide;

[0037] S2. Coated SiO2: Add 10g of nano-magnetic ferroferric oxide to 70g of ethanol, add 5g of methyl orthosilicate, stir and disperse for 10min, drop 8g of ammonia water and 3g of water, stir and react for 10h, separate the magnet, wash, dry, and calcine at 500℃ for 1h to obtain SiO2-coated nano-magnetic ferroferric oxide;

[0038] S3. Preparation of fullerene: 0.5 g of fullerene was dissolved in 200 mL of m-xylene, 15 g of 2 mol / L NaOH solution, 15 g of 10 wt% tetrabutylammonium hydroxide solution and 30 g of 25 wt% hydrogen peroxide were added dropwise, the reaction was stirred for 2 h, the liquid was separated, the lower layer of liquid was collected, ethanol was added to the system ethanol content of 80 wt%, precipitation was performed for 1 h, the solid was collected, washed, and dried to obtain fullerene;

[0039] S4. Modification: 2 g of fullerol, 0.5 g of phytic acid, 10 g of SiO2-coated nanomagnetic ferroferric oxide, and 0.1 g of potassium dihydrogen phosphate were added to 100 mL of water, and hydrothermally reacted at 140 ° C for 9 h, separated by a magnet, washed, and dried to obtain modified nanoparticles;

[0040] S5 impregnation: 3g nickel chloride, 1g rhodium chloride was dissolved in 200mL water, 7g modified nanoparticles were added, impregnated for 12h, separated by a magnet, and dried to obtain an impregnated material;

[0041] S6. Reduction: Add 1 g of the impregnated material into 200 mL of a 0.5 wt% sodium borohydride aqueous solution, stir and react for 30 min, separate with a magnet, wash, and dry to obtain a catalyst.

[0042] Preparation Example 2 Preparation of Catalyst

[0043] The following steps are involved:

[0044] S1. Preparation of nano-magnetic ferroferric oxide: 3.24g ferric chloride and 1.26g ferrous chloride were dissolved in 200mL water, and 0.3g Tween-40 was added to obtain an aqueous solution; the aqueous solution was added dropwise into 500mL fish oil, emulsified at 8000r / min for 15min, and under nitrogen protection, ammonia water was added dropwise to adjust the pH value to 12, heated to 95℃, stirred for reaction for 5h, centrifuged, washed, dried, and calcined at 550℃ for 5h to obtain nano-magnetic ferroferric oxide;

[0045] S2. Coated SiO2: Add 10g of nano-magnetic ferroferric oxide to 100g of ethanol, add 7g of ethyl orthosilicate, stir and disperse for 10min, drop 10g of ammonia water and 5g of water, stir and react for 12h, separate the magnet, wash, dry, and calcine at 600℃ for 3h to obtain SiO2-coated nano-magnetic ferroferric oxide;

[0046] S3. Preparation of fullerene: 1 g of fullerene was dissolved in 200 mL of m-xylene, 20 g of 4 mol / L KOH solution, 20 g of 15 wt% tetrabutylammonium hydroxide solution and 40 g of 35 wt% hydrogen peroxide were added dropwise, the reaction was stirred for 4 h, the liquid was separated, the lower layer of liquid was collected, ethanol was added until the ethanol content of the system was 90 wt%, precipitation was performed for 1 h, the solid was collected, washed, and dried to obtain fullerene;

[0047] S4. Modification: 3 g of fullerol, 1 g of phytic acid, 10 g of SiO2-coated nanomagnetic ferroferric oxide, and 0.2 g of potassium dihydrogen phosphate were added to 100 mL of water, and hydrothermally reacted at 160 ° C for 12 h, separated by a magnet, washed, and dried to obtain modified nanoparticles;

[0048] S5. Impregnation: 5 g of nickel nitrate and 2 g of rhodium nitrate were dissolved in 200 mL of water, 10 g of modified nanoparticles were added, impregnated for 15 h, separated by a magnet, and dried to obtain an impregnated material;

[0049] S6. Reduction: 2 g of the impregnated material was added to 200 mL of a 1 wt % sodium borohydride aqueous solution, and the mixture was stirred for reaction for 50 min. The mixture was separated by a magnet, washed, and dried to obtain a catalyst.

[0050] Preparation Example 3 Preparation of Catalyst

[0051] The following steps are involved:

[0052] S1. Preparation of nano-magnetic ferroferric oxide: 3.24g ferric chloride and 1.26g ferrous chloride were dissolved in 200mL water, and 0.25g Tween-80 was added to obtain an aqueous solution; the aqueous solution was added dropwise into 500mL fish oil, and emulsified at 8000r / min for 15min. Under nitrogen protection, ammonia water was added dropwise to adjust the pH value to 11, heated to 90℃, stirred for reaction for 4h, centrifuged, washed, dried, and calcined at 500℃ for 4h to obtain nano-magnetic ferroferric oxide;

[0053] S2. Coated SiO2: 10g of nano-magnetic ferroferric oxide was added to 85g of ethanol, 6g of ethyl orthosilicate was added, and the mixture was stirred and dispersed for 10min. 9g of ammonia water and 4g of water were added dropwise, and the mixture was stirred and reacted for 11h. The magnet was separated, washed, dried, and calcined at 550℃ for 2h to obtain SiO2-coated nano-magnetic ferroferric oxide.

[0054] S3. Preparation of fullerene: 0.7 g of fullerene was dissolved in 200 mL of m-xylene, 17 g of 3 mol / L NaOH solution, 17 g of 12 wt% tetrabutylammonium hydroxide solution and 35 g of 30 wt% hydrogen peroxide were added dropwise, the reaction was stirred for 3 h, the liquid was separated, the lower layer of liquid was collected, ethanol was added to the system ethanol content of 85 wt%, precipitation was performed for 1 h, the solid was collected, washed, and dried to obtain fullerene alcohol;

[0055] S4. Modification: 2.5 g of fullerol, 0.7 g of phytic acid, 10 g of SiO2-coated nanomagnetic ferroferric oxide, and 0.15 g of potassium dihydrogen phosphate were added to 100 mL of water, and hydrothermally reacted at 150 ° C for 10 h, separated by a magnet, washed, and dried to obtain modified nanoparticles;

[0056] S5 impregnation: 4g nickel chloride, 1.5g rhodium chloride was dissolved in 200mL water, 8.5g modified nanoparticles were added, impregnated for 13h, separated by a magnet, and dried to obtain an impregnated material;

[0057] S6. Reduction: 1.5 g of the impregnated material was added to 200 mL of a 0.7 wt % sodium borohydride aqueous solution, and the mixture was stirred for reaction for 40 min. The mixture was separated by a magnet, washed, and dried to obtain a catalyst.

[0058] Comparative Preparation Example 1

[0059] Compared with Preparation Example 3, the difference is that step S2 is not performed.

[0060] The details are as follows:

[0061] S1. Preparation of nano-magnetic ferroferric oxide: 3.24g ferric chloride and 1.26g ferrous chloride were dissolved in 200mL water, and 0.25g Tween-80 was added to obtain an aqueous solution; the aqueous solution was added dropwise into 500mL fish oil, and emulsified at 8000r / min for 15min. Under nitrogen protection, ammonia water was added dropwise to adjust the pH value to 11, heated to 90℃, stirred for reaction for 4h, centrifuged, washed, dried, and calcined at 500℃ for 4h to obtain nano-magnetic ferroferric oxide;

[0062] S2. Preparation of fullerene: 0.7 g of fullerene was dissolved in 200 mL of m-xylene, 17 g of 3 mol / L NaOH solution, 17 g of 12 wt% tetrabutylammonium hydroxide solution and 35 g of 30 wt% hydrogen peroxide were added dropwise, the reaction was stirred for 3 h, the liquid was separated, the lower layer of liquid was collected, ethanol was added to the system ethanol content of 85 wt%, precipitation was performed for 1 h, the solid was collected, washed, and dried to obtain fullerene alcohol;

[0063] S3. Modification: 2.5 g of fullerol, 0.7 g of phytic acid, 10 g of nano-magnetic ferroferric oxide, and 0.15 g of potassium dihydrogen phosphate were added to 100 mL of water, and hydrothermally reacted at 150 ° C for 10 h, separated by a magnet, washed, and dried to obtain modified nanoparticles;

[0064] S4 impregnation: 4g nickel chloride, 1.5g rhodium chloride was dissolved in 200mL water, 8.5g modified nanoparticles were added, impregnated for 13h, separated by a magnet, and dried to obtain an impregnated material;

[0065] S5. Reduction: 1.5 g of the impregnated material was added to 200 mL of a 0.7 wt % sodium borohydride aqueous solution, and the mixture was stirred for reaction for 40 min. The mixture was separated by a magnet, washed, and dried to obtain a catalyst.

[0066] Comparative Preparation Example 2

[0067] Compared with Preparation Example 3, the difference is that steps S3 and S4 are not performed.

[0068] The details are as follows:

[0069] S1. Preparation of nano-magnetic ferroferric oxide: 3.24g ferric chloride and 1.26g ferrous chloride were dissolved in 200mL water, and 0.25g Tween-80 was added to obtain an aqueous solution; the aqueous solution was added dropwise into 500mL fish oil, and emulsified at 8000r / min for 15min. Under nitrogen protection, ammonia water was added dropwise to adjust the pH value to 11, heated to 90℃, stirred for reaction for 4h, centrifuged, washed, dried, and calcined at 500℃ for 4h to obtain nano-magnetic ferroferric oxide;

[0070] S2. Coated SiO2: 10g of nano-magnetic ferroferric oxide was added to 85g of ethanol, 6g of ethyl orthosilicate was added, and the mixture was stirred and dispersed for 10min. 9g of ammonia water and 4g of water were added dropwise, and the mixture was stirred and reacted for 11h. The magnet was separated, washed, dried, and calcined at 550℃ for 2h to obtain SiO2-coated nano-magnetic ferroferric oxide.

[0071] S3 impregnation: 4g nickel chloride, 1.5g rhodium chloride was dissolved in 200mL water, 8.5gSiO2 coated nanomagnetic ferroferric oxide was added, impregnated for 13h, separated by a magnet, and dried to obtain an impregnated material;

[0072] S4. Reduction: 1.5 g of the impregnated material was added to 200 mL of a 0.7 wt % sodium borohydride aqueous solution, and the mixture was stirred for reaction for 40 min. The mixture was separated by a magnet, washed, and dried to obtain a catalyst.

[0073] Comparative Preparation Example 3

[0074] Compared with Preparation Example 3, the difference is that rhodium chloride is not added in step S5.

[0075] The details are as follows:

[0076] S5. Impregnation: 5.5 g of nickel chloride was dissolved in 200 mL of water, and 8.5 g of modified nanoparticles were added. The mixture was impregnated for 13 h, separated by a magnet, and dried to obtain an impregnated product.

[0077] Preparation Example 4 Preparation of phosphine ligand

[0078] The synthetic route is as follows:

[0079]

[0080] Here’s how:

[0081] T1. Preparation of dibornyl terephthalate: 20 mmol of exo-2-endo-3-norbornanediol and 10 mmol of terephthalic acid were added to 50 mL of toluene, and p-toluenesulfonic acid was added. The amount of p-toluenesulfonic acid added was 2.5 wt% of the total mass of the system. The mixture was heated under reflux for 10 h, and purified by column chromatography (petroleum ether: ethyl acetate 5:1) to obtain an intermediate; ESI-MS calculated value: C 24 H 35 O6(M+H) + 419.24, found value: 419.2, yield: 67.9%.

[0082] NMR results: 1H NMR (300MHz, CDCl3) δ8.1 (s, 4H), 3.92 (dd, 2H), 3.75 (dd, 2H), 2.20 (m, 2H), 2.0 (br, 2H), 1.67 (m, 2H), 1.52-1.57 (m, 8H), 1.07 (d, 12H).

[0083] T2. Preparation of phosphine ligand: Under nitrogen protection, add 70mmol triethylamine and 10mmol phosphorus trichloride to 100mL toluene, cool to -60℃, add 20mmol phenol, stir for 3h, then add 10mmol intermediate, continue to react for 1.5h, heat to room temperature and stir for 1h, filter, separate by column chromatography (petroleum ether: dichloromethane 5:1), and purify to obtain phosphine ligand. ESI-MS calculated value: C 48 H 53 O 10 P2(M+H) + 851.30, found value: 851.3, yield: 52.4%.

[0084] NMR results: 1 H NMR (300MHz, CDCl3) δ8.15 (s, 4H), 7.12 (m, 8H), 6.76-6.85 (m, 12H), 3.93 (dd, 2H), 3.79 (dd, 2H), 2.20 (m, 2H), 1.72 (m, 2H), 1.59-1.63 (m, 8H), 1.10 (d, 12H).

[0085] Example 1

[0086] This embodiment provides a method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene, comprising the following steps:

[0087] (1) Hydrocyanation of 1,3-butadiene: Under nitrogen protection, 3 g of the catalyst prepared in Preparation Example 1 and 65 g of the phosphine ligand prepared in Preparation Example 4 were stirred and mixed for 30 min, and then 400 g of dehydrated 1,3-butadiene and 200 g of hydrocyanic acid were added. The mixture was heated to 100 °C and pressurized to 15 bar. The reaction was stirred for 1 h to obtain the product. The catalyst was separated by a magnet, washed, dried, and reused.

[0088] (2) Secondary hydrocyanation reaction: The catalyst prepared in Preparation Example 1, the phosphine ligand prepared in Preparation Example 4 and ferric chloride were added to the product in step (1), wherein the concentrations of the catalyst, the phosphine ligand and the ferric chloride in the product were 190 mg / L, 3.5 g / L and 400 mg / L, respectively. The product was heated to 85° C. under nitrogen protection and stirred. 500 g of hydrocyanic acid was added to 600 g of the product. The reaction was kept warm for 5 h. Unreacted hydrocyanic acid, 3-pentenenitrile, product adiponitrile and other by-products were collected by reduced pressure distillation. After separation of hydrocyanic acid and 3-pentenenitrile, the product was re-entered into step (2) to continue the reaction. The product adiponitrile was purified to obtain the final product. The reaction was carried out continuously in a single-pot cycle experimental mode.

[0089] Example 2

[0090] Compared with Example 1, the difference is that the catalyst is prepared by Preparation Example 2.

[0091] Example 3

[0092] Compared with Example 1, the difference is that the catalyst is prepared by Preparation Example 3.

[0093] Comparative Example 1

[0094] Compared with Example 1, the difference is that the catalyst is prepared by Comparative Preparation Example 1.

[0095] Comparative Example 2

[0096] Compared with Example 1, the difference is that the catalyst is prepared by Comparative Preparation Example 2.

[0097] Comparative Example 3

[0098] Compared with Example 1, the difference is that the catalyst is prepared by Comparative Preparation Example 3.

[0099] Comparative Example 4

[0100] Compared with Example 1, the difference is that the phosphine ligand is replaced by monophosphite.

[0101] Test Example 1

[0102] The product adiponitrile obtained after 5 hours of reaction in Example 1-3 and Comparative Example 1-4 was purified and analyzed. The results are shown in Table 1.

[0103] Table 1

[0104]

[0105] Note: The conversion and selectivity of adiponitrile are calculated based on hydrocyanic acid.

[0106] As can be seen from the above table, the reaction conversion rate and selectivity in Examples 1 to 3 of the present invention are high. The catalyst in Comparative Example 2 was prepared by Comparative Preparation Example 1, and the surface of the magnetic ferroferric oxide was not coated with silicon dioxide. The catalyst collapsed after 100 hours of catalysis, and the catalytic activity was greatly reduced, and it could not be used any more.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene, characterized in that: The following steps are involved: (1) Hydrocyanation of 1,3-butadiene: Under the protection of inert gas, the catalyst and phosphine ligand are stirred and mixed, and then dehydrated 1,3-butadiene and hydrocyanic acid are added, and the reaction is heated and pressurized to obtain the product, and the catalyst is separated by a magnet; (2) Secondary hydrocyanation reaction: adding a catalyst, a phosphine ligand and a Lewis acid to the product of step (1), heating and stirring under inert gas protection, adding hydrocyanic acid, keeping the temperature for reaction, collecting unreacted hydrocyanic acid, 3-pentenenitrile, product adiponitrile and other by-products by vacuum distillation, separating hydrocyanic acid and 3-pentenenitrile, and then re-entering step (2) to continue the reaction, purifying the product adiponitrile to obtain the final product, and carrying out continuous reaction in a single-pot cycle experiment mode; The structure of the phosphine ligand is shown in Formula I: Formula I; The preparation method of the catalyst is as follows: S1. Preparation of nano-magnetic ferroferric oxide: dissolving ferric chloride and ferrous chloride in water, adding an emulsifier to obtain an aqueous solution; dropping the aqueous solution into fish oil, emulsifying, adding ammonia water to adjust the pH value under the protection of inert gas, heating and stirring to react, centrifuging, washing, drying, and calcining to obtain nano-magnetic ferroferric oxide; S2. Coated SiO2: Add nano-magnetic ferroferric oxide to ethanol, add alkyl orthosilicate, stir and disperse evenly, add ammonia and water dropwise, stir to react, separate the magnet, wash, dry, and calcine to obtain SiO2-coated nano-magnetic ferroferric oxide; S3. Preparation of fullerene alcohol: fullerene was dissolved in m-xylene, alkali solution, tetrabutylammonium hydroxide solution and hydrogen peroxide were added dropwise, the reaction was stirred, the liquid was separated, the lower liquid was collected, ethanol was added for precipitation, the solid was collected, washed, and dried to obtain fullerene alcohol; S4. Modification: adding fullerene alcohol, phytic acid, SiO2-coated nanomagnetic ferroferric oxide, and potassium dihydrogen phosphate to water, hydrothermally reacting, separating with a magnet, washing, and drying to obtain modified nanoparticles; S5. Impregnation: dissolving nickel salt and rhodium salt in water, adding modified nanoparticles, impregnating, separating with a magnet, and drying to obtain an impregnated material; S6. Reduction: Add the impregnated material into a sodium borohydride aqueous solution, stir the reaction, separate with a magnet, wash, and dry to obtain a catalyst.

2. The method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene according to claim 1, characterized in that: The temperature of the heating and pressurizing reaction in step (1) is 90-100°C, the pressure is 13-17 bar, the time is 1-2 hours, and the mass ratio of the catalyst, phosphine ligand, 1,3-butadiene and hydrocyanic acid is 3-4:60-70:400-420:200-210.

3. The method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene according to claim 1, characterized in that: In step (2), the concentrations of the catalyst, phosphine ligand and Lewis acid in the product are 180-200 mg / L, 3-4 g / L and 300-500 mg / L respectively, the mass ratio of hydrocyanic acid to the product is 5-7:4-6, the heating temperature is 80-95° C., the insulation reaction time is 4-6 h, and the Lewis acid is ferric chloride.

4. The method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene according to claim 1, characterized in that: The mass ratio of ferric chloride, ferrous chloride and emulsifier in step S1 is 3.24:1.26:0.2-0.3, the emulsifier is selected from at least one of Tween-20, Tween-40, Tween-60, Tween-80 and Tween-85, the pH value is adjusted to 10-12 by dripping ammonia water, the temperature of the heating and stirring reaction is 85-95° C., the time is 3-5 hours, the temperature of the calcination is 450-550° C., and the time is 3-5 hours; the mass ratio of nano-magnetic ferrosilicate, ethanol, alkyl orthosilicate, ammonia water and water in step S2 is 10:70-100:5-7:8-10:3-5, the alkyl orthosilicate is methyl orthosilicate or ethyl orthosilicate, the stirring reaction time is 10-12 hours, the calcination time is 500-600° C., and the time is 1-3 hours.

5. The method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene according to claim 1, characterized in that: In step S3, the mass ratio of fullerene, alkali solution, tetrabutylammonium hydroxide solution and hydrogen peroxide is 0.5-1:15-20:15-20:30-40, the alkali solution is 2-4 mol / L NaOH or KOH solution, the concentration of tetrabutylammonium hydroxide solution is 10-15wt%, the concentration of hydrogen peroxide is 25-35wt%, and the stirring reaction time is 2-4h; in step S4, the mass ratio of fullerol, phytic acid, SiO2-coated nanomagnetic ferrosoferric oxide and potassium dihydrogen phosphate is 2-3:0.5-1:10:0.1-0.2, the temperature of the hydrothermal reaction is 140-160°C, and the time is 9-12h.

6. The method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene according to claim 1, characterized in that: The mass ratio of the nickel salt, rhodium salt and modified nanoparticles in step S5 is 3-5:1-2:7-10, the nickel salt is selected from at least one of nickel chloride, nickel sulfate and nickel nitrate, the rhodium salt is selected from at least one of rhodium chloride, rhodium nitrate and rhodium sulfate, and the impregnation time is 12-15h; the concentration of the sodium borohydride aqueous solution in step S6 is 0.5-1wt%, the impregnated material and the sodium borohydride aqueous solution are in a mass ratio of 1-2:200, and the stirring reaction time is 30-50min.

7. The method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene according to claim 1, characterized in that: The preparation method of the phosphine ligand is as follows: T1. Preparation of dibornyl terephthalate: exo-2-endo-3-norbornanediol and terephthalic acid are added to toluene, a catalyst is added, the mixture is heated under reflux, and the mixture is separated and purified by column chromatography to obtain an intermediate having the following structure: ； T2. Preparation of phosphine ligand: Under the protection of inert gas, add triethylamine and phosphorus trichloride to toluene, cool down, add phenol, keep warm and stir, then add intermediate, keep warm and continue to react, warm to room temperature and stir to react, filter, separate and purify by column chromatography to obtain phosphine ligand.

8. The method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene according to claim 7, characterized in that: In step T1, the molar ratio of exo-2-endo-3-norbornanediol to terephthalic acid is 2-2.1:1, the amount of the catalyst added is 2-3wt% of the total mass of the system, the catalyst is concentrated sulfuric acid or p-toluenesulfonic acid, and the heating reflux reaction time is 8-10h.

9. The method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene according to claim 7, characterized in that: The molar ratio of triethylamine, phosphorus trichloride, phenol and intermediate in step T2 is 6-8:1:1.9-2:1-1.1, the temperature is cooled to -55 to -60°C, the time of heat preservation and stirring is 2-4h, the time of heat preservation and continued reaction is 1-2h, and the time of heating to room temperature and stirring the reaction is 0.5-1.5h.

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