Process for the hydrogenation of phthalonitriles

Abstract

The application relates to the technical field of benzenedicarbonitrile and discloses a method for hydrogenating benzenedicarbonitrile, which comprises the following steps: (1) in the presence of a supported acid catalyst, carrying out a dehydration reaction on cyanobenzamide in benzenedicarbonitrile containing cyanobenzamide; wherein the supported acid catalyst comprises a first carrier and an acid component supported on the first carrier, and the acid component comprises at least one of phosphoric acid, boric acid and C2-C6 organic acid; (2) in the presence of a hydrogenation catalyst and optional ammonia, contacting the product obtained through the dehydration reaction in step (1) with hydrogen to carry out a hydrogenation reaction. By taking the supported acid catalyst containing a specific acid component as the catalyst for the dehydration reaction of cyanobenzamide, the application can effectively remove the impurity cyanobenzamide in the benzenedicarbonitrile and make the cyanobenzamide generate the benzenedicarbonitrile, and the method disclosed by the application can effectively prolong the service life of the hydrogenation catalyst.

Description

Technical Field

[0001] This invention relates to the field of phthalonitrile technology, and more specifically to a method for hydrogenating phthalonitrile. Background Technology

[0002] m-xylenediamine (m-XDA) is an important fine chemical intermediate with excellent performance and wide applications. It has three main uses: First, as an epoxy resin curing agent, it is a low-toxicity curing agent (LD50 1.0 g / kg), with low viscosity. Its characteristics include accelerating the curing speed at room temperature, good heat resistance, water resistance, and chemical resistance, as well as good wetting curing properties and surface gloss. It is widely used in coatings, adhesives, and electronic products. Second, it is used to synthesize xylene nylon resin, especially xylene nylon resin MXD6 prepared with nylon 6. It has high strength and elasticity over a very high temperature range, high deformation temperature, and low thermal expansion coefficient, comparable to alloys. It is suitable for precision molding and high-temperature baking coating. The resulting film has high transparency and oxygen barrier properties, making it suitable for food packaging. The resulting fibers have high strength. Third, it is used as a key intermediate raw material for polyurethane resins to synthesize isophthalic diisocyanate (XDI), which is further used to synthesize polyurethane resins. This resin is comparable to hexamethylene diisocyanate (HDI) and has better yellowing resistance. It can be used in light-colored coatings, producing coatings with high hardness and low toxicity. It can also be used in synthetic leather. In addition, it can also be used as a surfactant, paper processing agent, metal chelating agent, rubber crosslinking agent and stabilizer, fiber treatment agent, pesticide, photosensitive resin, lubricant and rust inhibitor, etc.

[0003] Currently, the commonly used method for preparing m-phenylenediamine is the ammoxidation-hydrogenation process. m-Xylene undergoes an ammoxidation reaction with ammonia and air under the action of V₂O₅ to produce isophthalonitrile (IPN), which is then hydrogenated to produce m-XDA. This process is not only mild but also produces high-quality products with high yields, making it the mainstream method.

[0004]

[0005] However, cyanobenzamide byproducts are inevitably generated during the production of isophthalonitrile. The presence of these byproducts not only affects the purity of the hydrogenation product of isophthalonitrile, but also affects the service life of the catalyst. Summary of the Invention

[0006] The purpose of this invention is to overcome the problem of high impurity (cyanobenzoamide) content in phthalonitrile, which affects the service life of the catalyst, in the prior art. This invention provides a method for hydrogenating phthalonitrile. This invention uses a specific supported acid catalyst to cause the cyanobenzoamide in the phthalonitrile containing cyanobenzoamide to undergo a dehydration reaction, and then hydrogenates the resulting phthalonitrile. The method of hydrogenating phthalonitrile using this invention can effectively extend the service life of the catalyst and enable the hydrogenation reaction to operate continuously and stably.

[0007] To achieve the above objectives, the first aspect of the present invention provides a method for hydrogenating phthalonitrile, the method comprising the following steps:

[0008] (1) In the presence of a supported acid catalyst, cyanobenzamide in phthalonitrile containing cyanobenzamide undergoes a dehydration reaction; wherein the supported acid catalyst comprises a first support and an acid component supported on the first support, the acid component comprising at least one of phosphoric acid, boric acid and C2-C6 organic acids;

[0009] (2) In the presence of a hydrogenation catalyst and optional ammonia, the product obtained from the dehydration reaction in step (1) is brought into contact with hydrogen to carry out a hydrogenation reaction.

[0010] Through the above technical solution, the present invention achieves the following beneficial effects:

[0011] (1) The present invention uses a supported acid catalyst containing a specific acid component as a catalyst for the dehydration reaction of cyanobenzamide, which can effectively remove the impurity cyanobenzamide in phthalonitrile and generate phthalonitrile from cyanobenzamide, thus effectively extending the service life of the hydrogenation catalyst.

[0012] (2) In a preferred embodiment, the hydrogenation catalyst containing electronic additives of the present invention can effectively suppress the formation of polymers such as secondary amines and tertiary amines while ensuring high conversion of phthalonitrile, thereby improving the selectivity of amine products. Preferably, it realizes the efficient hydrogenation of isophthalonitrile to isophthalic dimethylamine, and at the same time, it can effectively extend the life of the catalyst.

[0013] (3) In a preferred embodiment, the present invention introduces an electronic additive during the support formation process of the hydrogenation catalyst and controls the amount of electronic additive added, and then loads the active component on the support to prepare the hydrogenation catalyst. The hydrogenation catalyst prepared by the method of the present invention can effectively inhibit the formation of polymers such as secondary amines and tertiary amines while ensuring high conversion of nitrile compounds, thereby improving the selectivity of amine products. Preferably, it achieves efficient hydrogenation of isophthalonitrile to m-phenylenediamine. Detailed Implementation

[0014] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0015] In this invention, "ppm" means "mg / kg"; that is, "the content of cyanobenzamide in phthalonitrile raw material is 1ppm" means "the content of cyanobenzamide in 1 kg of phthalonitrile raw material is 1 mg".

[0016] The first aspect of this invention provides a method for hydrogenating phthalonitrile, the method comprising the following steps:

[0017] (1) In the presence of a supported acid catalyst, cyanobenzamide in phthalonitrile containing cyanobenzamide undergoes a dehydration reaction; wherein the supported acid catalyst comprises a first support and an acid component supported on the first support, the acid component comprising at least one of phosphoric acid, boric acid and C2-C6 organic acids;

[0018] (2) In the presence of a hydrogenation catalyst and optional ammonia, the product obtained from the dehydration reaction in step (1) is brought into contact with hydrogen to carry out a hydrogenation reaction.

[0019] The inventors of this invention have discovered that when the supported acid catalyst of this invention is used as the catalyst for the dehydration reaction, it can effectively remove the impurity cyanobenzamide from phthalonitrile and convert cyanobenzamide into phthalonitrile. This reduces the impact of the impurity cyanobenzamide on the catalyst of the subsequent phthalonitrile hydrogenation reaction, effectively avoids the loss of phthalonitrile during the impurity removal process, and can convert cyanobenzamide into phthalonitrile without the need for secondary separation and purification. At the same time, using the product obtained from the dehydration reaction of this invention for the hydrogenation reaction can extend the service life of the hydrogenation catalyst and enable the hydrogenation reaction to operate continuously and stably.

[0020] According to the present invention, in order to further improve the removal rate of the impurity cyanobenzamide, preferably, the content of the acid component is 0.5-30g per 100g of the first carrier, more preferably 5-20g. In the present invention, the content of the acid component per 100g of the first carrier can be 0.5g, 1g, 5g, 10g, 15g, 20g, 25g, 30g, or any combination of the above.

[0021] According to the present invention, preferably, the carrier includes at least one of alumina, silicon dioxide and activated carbon.

[0022] According to the present invention, preferably, the C2-C6 organic acid includes C2-C6 organic dicarboxylic acids and / or C2-C6 organic tricarboxylic acids; more preferably, the C2-C6 organic acid includes at least one of oxalic acid, acetic acid, tartaric acid and citric acid.

[0023] This invention also provides a method for preparing a supported acid catalyst. Preferably, the method includes: impregnating a support with a solution containing an acid component, followed by drying. The impregnation (aging) time can be 8-20 hours, preferably 10-14 hours. The drying conditions can include: a temperature of 80-200°C, preferably 80-120°C; and a time of 8-20 hours, preferably 10-14 hours. The solvent in the solution containing the acid component can be water. Preferably, the content of the acid component in the solution is 1-20% by weight. The amount of acid component used is such that, relative to every 100g of the first support, the content of the acid component in the obtained supported acid catalyst is 0.5-30g, more preferably 5-20g.

[0024] According to the present invention, preferably, the content of cyanobenzamide in the cyanobenzamide-containing phthalonitrile is 0.1-5% by weight (for example, it can be 0.1% by weight, 0.2% by weight, 0.3% by weight, 0.4% by weight, 0.5% by weight, 0.8% by weight, 1% by weight, 2% by weight, 3% by weight, 4% by weight, 5% by weight, and any two of the above ranges), more preferably 0.2-4% by weight.

[0025] According to the present invention, preferably, the cyanobenzamide is 3-cyanobenzamide.

[0026] According to the present invention, preferably, the phthalonitrile is isophthalonitrile.

[0027] According to the present invention, preferably, the dehydration reaction is carried out under an inert atmosphere; more preferably, the inert atmosphere is provided by nitrogen and / or an inert gas. The inert gas may be at least one of helium, neon, and argon.

[0028] According to the present invention, preferably, the dehydration reaction is carried out in the presence of a solvent, wherein the solvent is an organic solvent, and more preferably, the organic solvent includes at least one of toluene, dioxane, and N,N-dimethylformamide.

[0029] According to the present invention, preferably, the amount of solvent used relative to 100g of cyanobenzamide-containing phthalonitrile is 500-3000g, more preferably 1000-2000g. In the present invention, the amount of solvent used relative to 100g of cyanobenzamide-containing phthalonitrile can be 500g, 1000g, 1500g, 1900g, 2000g, 2100g, 2500g, 3000g, or any combination of the above.

[0030] According to the present invention, preferably, the conditions for the dehydration reaction include: a feed space velocity of 0.1-10 h⁻¹. -1 More preferably 1.5-6.5h -1 The reaction temperature is 200-400℃, more preferably 230-300℃; the reaction pressure is 1-10MPa, more preferably 3-6MPa.

[0031] According to the present invention, preferably, the method further includes: removing the solvent after the dehydration reaction is completed. The conditions for removing the solvent may include: a temperature of 100-300°C; and a pressure of -0.1 to -0.05 MPa.

[0032] In this invention, there is no particular limitation on the type of hydrogenation catalyst; it can be any hydrogenation catalyst commonly used in the art. For example, the hydrogenation catalyst can be a metal-supported hydrogenation catalyst. Typically, the hydrogenation catalyst comprises a second support and an active component supported on the second support. The active component includes at least one of Ni, Co, and Fe, and the second support includes at least one of alumina, silica, and activated carbon. The content of the active component relative to 100g of the second support can be 1-60g, more preferably 15-40g. The preparation method of the hydrogenation catalyst can be any catalyst preparation method commonly used in the art. For example, the active component can be directly loaded onto the support; alternatively, the support can be shaped first, and then the active component can be loaded onto the shaped support. For example, the method of shaping the support can be: mixing the support (at least one of alumina, silica, and activated carbon) with water, shaping it, and then subjecting it to a first drying and a first calcination to obtain the second support.

[0033] According to the present invention, in order to further improve the stability of the hydrogenation process, further extend the service life of the catalyst, and improve the selectivity of amine products, especially the selectivity of m-phenylenediamine, preferably, the second support further includes an electronic aid, which includes at least one of fullerene, graphene and carbon nanotubes; more preferably, the content of the electronic aid is 1-35% by weight based on the total weight of the second support, and more preferably 8-15% by weight.

[0034] In this invention, based on the total weight of the second carrier, the content of the electronic additive can be 1 wt%, 2 wt%, 4 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 9.5 wt%, 10 wt%, 12 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, or any two of the above ranges. In this invention, based on the total weight of the second carrier, the content of the electronic additive is calculated by the amount of material fed.

[0035] In this invention, the fullerene can be C 20 C 60 C 70 C 76 C 80 At least one of them, in this embodiment of the invention, is fullerene C 60 The invention is illustrated by example only, and is not limited thereto.

[0036] In this invention, the parameters of the graphene are not particularly limited; for example, the number of graphene layers can be 1-100, and the specific surface area can be 500-1000 m². 2 / g, with lateral dimensions ranging from 0.1 to 10 μm. In this embodiment of the invention, few-layer graphene (with fewer than 3 layers and a specific surface area greater than 500 m²) is used. 2 The invention is illustrated by taking an example (with a cross-sectional dimension of 0.5-5 μm) as an example, but is not limited thereto.

[0037] In this invention, the parameters of the carbon nanotubes are not particularly limited. For example, the carbon nanotubes can be single-walled carbon nanotubes, double-walled carbon nanotubes, etc. For example, the diameter of the carbon nanotubes is 1-5 nm and the length is 10-100 μm. In this embodiment of the invention, double-walled carbon nanotubes (diameter 2-4 nm, length 40-50 μm) are used as an example for illustrative purposes, but the invention is not limited thereto.

[0038] According to the present invention, preferably, the content of the active component is 0.5-65g per 100g of the second carrier, more preferably 10-50g, and even more preferably 10-45g. In the present invention, the content of the active component per 100g of carrier is calculated by the amount of material fed.

[0039] In this invention, the content of the active component relative to every 100g of the second carrier can be 0.5g, 1g, 10g, 12g, 15g, 19g, 20g, 25g, 30g, 35g, 40g, 45g, 50g, 55g, 60g, 65g, or any two of the above-mentioned groups.

[0040] According to the present invention, preferably, the active component does not include a detectable amount of VIB metal elements.

[0041] According to the present invention, in order to further improve the catalytic performance of the catalyst and improve the selectivity of amine products, especially the selectivity of m-phenylenediamine, preferably, the forming method of the second support includes: mixing at least one of alumina, silica, and activated carbon with optional electronic additives and water, forming the mixture, and then subjecting it to a first drying and a first calcination to obtain the second support.

[0042] According to the present invention, the first drying conditions can be conventional drying conditions in the art, as long as they can reduce the water content in the mixture after molding. Preferably, the first drying conditions include: a temperature of 100-200°C and a time of 8-16 hours.

[0043] According to the present invention, in order to further improve the synergistic effect between the carrier and the active component and improve the selectivity of amine products, especially the selectivity of m-phenylenediamine, the first calcination of the present invention is carried out at a lower temperature. Preferably, the conditions for the first calcination include: a temperature of 300-600°C, more preferably 400-500°C, and a time of 8-24h, more preferably 12-16h.

[0044] According to the present invention, the role of the water is to make it easier to shape at least one of alumina, silica, activated carbon and optional electronic additives into carriers of different shapes. Preferably, the weight ratio of the amount of at least one of alumina, silica, and activated carbon to the amount of water is 100:50-200, more preferably 100:80-140.

[0045] According to the present invention, the shape of the second carrier is not particularly limited and can be reasonably selected according to the conditions of the reactor or catalysis. Generally, the shape of the second carrier can be clover-shaped and / or cylindrical. The size of the second carrier is also not particularly limited. For example, when the second carrier is clover-shaped, the diameter of the clover strip can be 1-1.5 mm and the length can be 2-10 mm.

[0046] According to the present invention, preferably, the specific surface area of ​​the hydrogenation catalyst is 100-300 m². 3 / g.

[0047] According to the present invention, preferably, the pore volume of the hydrogenation catalyst is 0.3-1 mL / g.

[0048] According to the present invention, preferably, the pore size of the hydrogenation catalyst is 10-30 nm.

[0049] According to the present invention, the active component can be loaded onto the second support using conventional methods in the art, specifically at least one of impregnation, ion exchange, and coprecipitation. The embodiments of the present invention are illustrated by way of impregnation, but the present invention is not limited thereto. The method for loading the active component onto the second support may include: impregnating the second support with an aqueous solution of the active component precursor, followed by impregnation followed by drying and calcination.

[0050] In this invention, the active component precursor may include at least one of nickel salt, cobalt salt, and iron salt. For example, the active component precursor may include at least one of nickel nitrate, cobalt nitrate, and ferric nitrate. The embodiments of this invention use nickel nitrate as an example for illustrative purposes, but the invention is not limited thereto.

[0051] According to the present invention, the impregnation conditions can be those commonly used in the art, and the impregnation temperature can be room temperature. Preferably, the impregnation (aging) time is 12-24 hours. The impregnation method of the present invention can be conventional impregnation, equal-volume impregnation, or excessive impregnation.

[0052] According to the present invention, the second drying conditions can be conventional drying conditions in the art, as long as they can reduce the water content in the mixture after molding. Preferably, the second drying conditions include: a temperature of 100-200°C and a time of 8-16 hours.

[0053] According to the present invention, in order to further promote the synergistic effect between the carrier and the active component, the second calcination is carried out at a lower temperature. Preferably, the conditions for the second calcination include: a temperature of 300-600°C, more preferably 380-480°C, and a time of 6-24h, more preferably 12-18h.

[0054] According to the present invention, preferably, the conditions for the hydrogenation reaction include: a temperature of 40-150°C, a pressure of 6-20 MPa, and a feed space velocity of 2-6 h⁻¹. -1 .

[0055] According to the present invention, preferably, the molar ratio of phthalonitrile to hydrogen is 1:4-10, and the molar ratio of phthalonitrile to ammonia is 1:130-400.

[0056] According to the present invention, preferably, the method further includes: reducing the catalyst before carrying out the hydrogenation reaction, wherein the reduction conditions include: a temperature of 200-500°C, a pressure of 0.1-1 MPa, and a time of 12-24 h.

[0057] The present invention will be described in detail below through embodiments. In the following embodiments,

[0058] The phosphoric acid raw material is a commercially available product with a purity of ≥99.9%.

[0059] The 3-cyanobenzamide content in the isophthalonitrile raw material was 3450 ppm (obtained by chromatographic analysis).

[0060] Fullerene (C 60 The raw material is a commercially available product from Tokyo Chemical Industry Co., Ltd. (TCI) under the brand name B1660.

[0061] The silica powder raw material is a commercially available product from Wacker Chemie AG, Germany, with the grade T40.

[0062] Preparation Example 1A

[0063] 1.5g of phosphoric acid was dissolved in 10g of deionized water. The resulting solution was used to impregnate 10g of silica support. After aging for 12h, the solution was placed in an oven and dried at 110℃ for 12h to complete the preparation of the supported acid catalyst, which is designated as catalyst 1A.

[0064] Preparation Example 2A

[0065] 0.8g of phosphoric acid was dissolved in 10g of deionized water. The resulting solution was used to impregnate 10g of silica support. After aging for 12h, the solution was placed in an oven and dried at 110℃ for 12h to complete the preparation of the supported acid catalyst, which is designated as catalyst 2A.

[0066] Preparation Example 3A

[0067] The preparation method was followed as in Example 1A, except that 0.2 g of phosphoric acid was used. The resulting supported acid catalyst is designated as catalyst 3A.

[0068] Preparation Example 4A

[0069] The preparation method of Example 1A was followed, except that phosphoric acid was replaced with boric acid. The resulting supported acid catalyst is designated as catalyst 4A.

[0070] Preparation Example 5A

[0071] The preparation method was carried out according to Example 1A, except that phosphoric acid was replaced with oxalic acid. The resulting supported acid catalyst is designated as catalyst 5A.

[0072] Comparative Preparation Example 1A

[0073] The preparation method of Example 1A was followed, except that the supported acid catalyst obtained by replacing phosphoric acid with perchloric acid was designated as catalyst D1A.

[0074] Preparation Example 1B

[0075] (1) 100g of silica powder and 11g of fullerene (C 60100g of deionized water was kneaded in a kneader and then extruded into clover strips (1.0-1.5mm in diameter) using an extruder. The strips were then placed in an oven and dried at 110℃ for 12 hours, and then calcined in a muffle furnace at 450℃ for 15 hours to complete the carrier preparation.

[0076] (2) Dissolve 9.8g of nickel nitrate hexahydrate in 10g of deionized water to obtain a solution. Use this solution to impregnate 10g of the carrier prepared in step (1), age it at room temperature for 12h, place it in an oven, dry it at 110℃ for 12h, and then calcine it in a muffle furnace at 420℃ for 12h to complete the preparation of the hydrogenation catalyst. The obtained catalyst is denoted as catalyst 1B.

[0077] Preparation Example 2B

[0078] (1) Mix 100g of silica powder and 8g of fullerene (C 60 120g of deionized water was kneaded in a kneader and then extruded into clover strips (1.0-1.5mm in diameter) using an extruder. The strips were then placed in an oven and dried at 110℃ for 12 hours, and then calcined in a muffle furnace at 450℃ for 15 hours to complete the carrier preparation.

[0079] (2) Dissolve 5.9g of nickel nitrate hexahydrate in 10g of deionized water to obtain a solution. Use this solution to impregnate 10g of the carrier prepared in step (1), age it at room temperature for 12h, place it in an oven, dry it at 110℃ for 12h, and then calcine it in a muffle furnace at 420℃ for 12h to complete the preparation of the hydrogenation catalyst. The obtained catalyst is denoted as catalyst 2B.

[0080] Preparation Example 3B

[0081] (1) Put 100g of silica powder and 100g of deionized water into a kneader and knead them into shape. Then, use an extruder to extrude them into clover strips (1.0-1.5mm in diameter). Place them in an oven and dry them at 110℃ for 12h. Then, calcine them in a muffle furnace at 450℃ for 15h to complete the carrier preparation.

[0082] (2) Dissolve 19.7g of nickel nitrate hexahydrate in 10g of deionized water to obtain a solution. Use this solution to impregnate 10g of the carrier prepared in step (1), age it at room temperature for 12h, place it in an oven, dry it at 110℃ for 12h, and then calcine it in a muffle furnace at 420℃ for 12h to complete the preparation of the hydrogenation catalyst. The obtained catalyst is denoted as catalyst 3B.

[0083] Preparation Example 4B

[0084] (1) Put 100g of silica powder and 100g of deionized water into a kneader and knead them into shape. Then, use an extruder to extrude them into clover strips (1.0-1.5mm in diameter). Place them in an oven and dry them at 110℃ for 12h. Then, calcine them in a muffle furnace at 450℃ for 15h to complete the carrier preparation.

[0085] (2) Dissolve 9.8g of nickel nitrate hexahydrate in 10g of deionized water to obtain a solution. Use this solution to impregnate 10g of the carrier prepared in step (1), age it at room temperature for 12h, place it in an oven, dry it at 110℃ for 12h, and then calcine it in a muffle furnace at 420℃ for 12h to complete the preparation of the hydrogenation catalyst. The obtained catalyst is denoted as catalyst 4B.

[0086] Preparation Example 5B

[0087] The catalyst was prepared according to the method of Preparation Example 1B, except that fullerene (C 60 The amount of ) used is 1.0g. The resulting catalyst is designated as catalyst 5B.

[0088] Preparation Example 6B

[0089] The catalyst was prepared according to the method of Preparation Example 1B, except that fullerene was replaced with an equal weight of graphite. The resulting catalyst is designated as Catalyst 6B.

[0090] Example

[0091] (1) Purification of isophthalonitrile feedstock: A supported acid catalyst was loaded into a reaction tube with a diameter of 10 mm, and the temperature was raised to 250 °C under a nitrogen atmosphere (nitrogen flow rate of 50 mL / min), with the reactor pressure controlled at 5 MPa. 10 g of isophthalonitrile feedstock was dissolved in 200 g of toluene, and the solution was distilled at a constant temperature for 2.0 h. -1 The air velocity is introduced into the reaction tube to contact the supported acid catalyst for dehydration reaction to remove 3-cyanobenzamide from the isophthalonitrile feedstock. The material coming out of the reactor is depressurized to -0.1 MPa under heating at 150°C, and toluene is removed by flash evaporation to obtain purified isophthalonitrile. The 3-cyanobenzamide content in the purified isophthalonitrile is shown in Table 1.

[0092] (2) The conditions for hydrogenation of refined isophthalonitrile include: placing the hydrogenation catalyst in a stainless steel reactor with a diameter of 10 mm; reducing and activating the catalyst bed for 12 h at atmospheric pressure, 400 °C, and a hydrogen flow rate of 6.0 NL / h; cooling the reactor to 80 °C; increasing the reactor pressure to 12 MPaG with hydrogen; and introducing a liquid mixture of hydrogen, isophthalonitrile (IPN), and ammonia (NH3) from the top of the reactor at a feed space velocity of 5.7 h⁻¹. -1The molar ratio of nitrile to ammonia was 1:143, the molar ratio of nitrile to hydrogen was 1:9.5, the total pressure was 12 MPaG, and the reaction temperature was 100℃. After 24 h of reaction, the conversion rate of isophthalonitrile, the selectivity of m-phenylenediamine, and the selectivity of the high-boiling-point condensation product are shown in Table 1.

[0093] Table 1

[0094]

[0095] As can be seen from the results in Table 1, the methods of Examples 1-7 of this invention can improve the stability of the catalyst, enabling it to maintain a high conversion rate of isophthalonitrile even after long-term operation. Preferably, when the supported acid catalyst of Examples 1-2 of this invention is used, 3-cyanobenzamide in isophthalonitrile can be effectively removed.

[0096] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for hydrogenating phthalonitrile, characterized in that, The method includes the following steps: (1) In the presence of a supported acid catalyst, cyanobenzamide in phthalonitrile containing cyanobenzamide undergoes a dehydration reaction; wherein the supported acid catalyst comprises a first support and an acid component supported on the first support, the acid component comprising at least one of phosphoric acid, boric acid and C2-C6 organic acids; (2) In the presence of a hydrogenation catalyst and optional ammonia, the product obtained from the dehydration reaction in step (1) is brought into contact with hydrogen to carry out a hydrogenation reaction.

2. The method according to claim 1, wherein, The content of the acid component is 0.5-30g, preferably 5-20g, relative to every 100g of the first carrier; And / or, the first carrier includes at least one of alumina, silica and activated carbon.

3. The method according to claim 1, wherein, The C2-C6 organic acids include C2-C6 organic dicarboxylic acids and / or C2-C6 organic tricarboxylic acids; preferably, the C2-C6 organic acids include at least one of oxalic acid, tartaric acid and citric acid.

4. The method according to claim 1, wherein, The cyanobenzamide content in the cyanobenzamide-containing phthalonitrile is 0.1-5% by weight, preferably 0.2-4% by weight; And / or, the cyanobenzamide is 3-cyanobenzamide; And / or, the phthalonitrile is isophthalonitrile.

5. The method according to claim 1, wherein, The dehydration reaction is carried out under an inert atmosphere, preferably provided by nitrogen and / or an inert gas. And / or, the dehydration reaction is carried out in the presence of a solvent, which is an organic solvent, preferably including at least one of toluene, dioxane, and N,N-dimethylformamide; more preferably, the amount of solvent used is 500-3000g, preferably 1000-2000g, relative to 100g of cyanobenzamide-containing phthalonitrile.

6. The method according to claim 5, wherein, The conditions for the dehydration reaction include: a feed space velocity of 0.1-10 h⁻¹. -1 Preferably, it is 1.5-6.5h. -1 The reaction temperature is 200-400℃, preferably 230-300℃; the reaction pressure is 1-10MPa, preferably 3-6MPa. And / or, the method further includes: removing the solvent after the dehydration reaction is completed.

7. The method according to claim 1, wherein, The hydrogenation catalyst includes a second support and an active component supported on the second support, wherein the active component includes at least one of Ni, Co, and Fe, and the second support includes at least one of alumina, silica, and activated carbon.

8. The method according to claim 7, wherein, The content of the active component is 1-60g, preferably 15-40g, relative to every 100g of the second carrier.

9. The method according to claim 7 or 8, wherein, The second carrier also includes electronic additives, which include at least one of fullerene, graphene and carbon nanotubes. The content of the electronic additives is 1-35% by weight, preferably 8-15% by weight, based on the total weight of the second carrier.

10. The method according to claim 9, wherein, The content of the active component is 0.5-65g, preferably 10-45g, relative to every 100g of the second carrier; And / or, the active component does not include a detectable amount of VIB metal elements.

11. The method according to any one of claims 7-10, wherein, The second carrier is formed by mixing at least one of alumina, silica, and activated carbon with optional electronic additives and water, followed by forming, and then undergoing a first drying and a first calcination. Preferably, the conditions for the first drying include: a temperature of 100-200°C and a time of 8-16 hours; Preferably, the conditions for the first calcination include: a temperature of 300-600℃, more preferably 400-500℃, and a time of 8-24h, more preferably 12-16h; Preferably, the weight ratio of at least one of alumina, silica, and activated carbon to water is 100:50-200, more preferably 100:80-140; Preferably, the second carrier is clover-shaped and / or cylindrical.

12. The method according to any one of claims 7-11, wherein, The specific surface area of ​​the hydrogenation catalyst is 100-300 m². 3 / g, pore volume is 0.3-1mL / g, pore size is 10-30nm.

13. The method according to any one of claims 1-12, wherein, The conditions for the hydrogenation reaction include: a temperature of 40-150℃, a pressure of 6-20 MPa, and a feed space velocity of 2-6 h⁻¹. -1 .

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