Method for preparing aniline and coproducing fatty amine through phenol amination

Abstract

The invention discloses a method for preparing aniline and coproducing fatty amine through phenol amination. The method can be used for efficiently preparing aniline and co-producing a series of high value-added fatty amines such as cyclohexylamine, dicyclohexylamine and the like. According to the method, the oxide-loaded noble metal catalyst is adopted, the surface of the catalyst is modified by using a phosphine ligand, and the generation proportion of various products is changed by regulating and controlling the conditions such as the catalyst structure, the reaction temperature, the pressure and the solvent, so that various amine products are simultaneously co-produced by using the same set of production equipment. According to the method, the production flexibility can be remarkably improved, and the structure of a phenol downstream product can be quickly adjusted according to the market demand change, so that the production efficiency and the economic benefit of the device are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of industrial synthesis technology, specifically relating to a method for preparing aniline and co-producing fatty amines by amination of phenol. Background Technology

[0002] Amine compounds are a crucial class of organic chemical raw materials, playing an irreplaceable role in numerous technological fields such as pharmaceuticals, dyes, and rubber additives. Aniline, in particular, serves as a key intermediate in the synthesis of fine chemicals and has extremely wide applications. Furthermore, aniline can also be used as a raw material for the preparation of isocyanates, demonstrating broad market prospects. In addition, other types of amine compounds, such as cyclohexylamine and dicyclohexylamine, also possess high economic added value.

[0003] Currently, the industrial process for preparing aniline typically employs a benzene nitration-hydrogenation reduction route. Specifically, benzene reacts with nitric acid under sulfuric acid catalysis to produce nitrobenzene, which is then hydrogenated to yield aniline. This process consumes large amounts of sulfuric or nitric acid as nitrating agents during nitration, and the subsequent neutralization step requires alkaline solutions such as sodium hydroxide, resulting in a highly concentrated brine solution. Furthermore, the nitration process must be carried out under high temperature and pressure conditions, placing stringent requirements on the pressure resistance of equipment and posing significant safety hazards and environmental pollution risks. In addition, other amine compounds such as cyclohexylamine and dicyclohexylamine are typically prepared from aniline through subsequent derivatization reactions.

[0004] Based on considerations of environmental friendliness and process safety, amination processes using cyclohexanol and phenol as alternative precursors have been proposed. Among these, the process of preparing aniline and related amine products using phenol and amination reagents as raw materials exhibits milder reaction conditions and, compared to traditional nitration processes, significant advantages in equipment requirements, safety precautions, and environmental protection, demonstrating higher process safety and environmental friendliness. The process for preparing aniline and co-producing aliphatic amines by hydrogen amination of phenol is as follows: Under hydrogen-induced conditions, phenol undergoes an amination reaction with liquid ammonia to generate aniline; the resulting aniline can further undergo a hydrogenation reaction with hydrogen gas to generate cyclohexylamine. In this process, cyclohexylamine can undergo a condensation reaction to generate dicyclohexylamine, with the intermediate product being N-cyclohexylaniline. This process can achieve the directed synthesis of various amine compounds such as aniline, cyclohexylamine, and dicyclohexylamine by controlling the reaction conditions.

[0005] CN1021816C discloses a method for producing aniline by amination of phenol. This method involves a reaction in a reactor equipped with a special alumina catalyst, which can be carried out in the gas or liquid phase and is a continuous operation. During the reaction, phenol and liquid ammonia are evaporated to form a gaseous mixture, which is then introduced into the reactor. The reaction temperature is approximately 300°C to approximately 600°C, the reaction pressure is 5-50 bar, and the molar ratio of ammonia to phenol is approximately 1:1 to approximately 40:1. This patent achieves high conversion and high selectivity at relatively low temperatures through an alumina catalyst with a special pore size distribution, and the catalyst activity can be maintained for a relatively long time. However, the process lacks economic viability, and no industrial-scale plants using this process are currently in operation.

[0006] CN117326952A discloses a method for preparing aniline from cyclohexanol compounds and liquid ammonia as raw materials. This method involves reacting aniline at 160-250°C in the presence of a Pt-based catalyst. The Pt-based catalyst comprises a support and Pt, wherein the support is at least one of a metal oxide, SiO2, and activated carbon, and the Pt particle size is 1-20 nm. During the reaction, cyclohexanol, the catalyst, and the organic reaction medium are added to a batch reactor. The pressure after vaporization of the liquid ammonia is 0.1-1 MPa, and the reaction is carried out at a preferred temperature of 180-200°C for 1-24 hours. Alternatively, a continuous reaction can be carried out in a fixed-bed reactor, where an organic solution of cyclohexanol is mixed with ammonia and then introduced into a reaction tube containing the catalyst. However, this catalyst has poor recyclability and high operating costs.

[0007] CN1171853C discloses a method for preparing aniline or alkylaniline from phenol or alkylphenol and ammonia. The method involves reacting under hydrogen-containing conditions in a gas-solid phase fixed-bed reactor at a temperature of 200-300℃, a pressure of 0.1-2 MPa, a feed weight hourly space velocity of 0.1-0.5 h⁻¹, a weight ratio of ammonia to phenol or alkylphenol of 1-20:1, and a molar ratio of ammonia to hydrogen of 1-20:1. The catalyst used is alumina supported on 0.1-10% palladium metal or its compounds, tin or a combination of tin and cerium metal or its compounds in a weight ratio of 0.1-2 to palladium, and iron, lanthanum, cadmium, or other metals or their compounds in a weight ratio of 0-3 to palladium. After the reaction, the product is separated and purified to obtain aniline or alkylaniline. This process only yields aniline and cannot produce other amine products, including cyclohexylamine and dicyclohexylamine.

[0008] EP0167996A1 discloses a method for preparing aromatic amines. This method uses phenol with the corresponding structure as a raw material, reacting it with excess ammonia and excess hydrogen in the presence of recyclable alicyclic amines under the action of a hydrogenation-dehydrogenation catalyst. The catalyst used is a supported catalyst, with the support containing or composed of alumina, and may further contain basic substances and zinc, chromium, manganese, iron, cobalt, and nickel. The product does not contain the raw material phenol or complex impurities and is easily separated by distillation. The separated alicyclic amines can be recycled to dissolve solid phenol and reused in the reaction. The product of this process is mainly a combination of aromatic amines and corresponding alicyclic amines, and cannot generate polycyclic alicyclic amines such as dicyclohexylamine.

[0009] US4429155A discloses a method for preparing aromatic amines or alicyclic amines, which can directly use phenol as a raw material or react with ammonia and hydrogen through an alicyclic amine intermediate in the presence of a supported palladium catalyst to obtain the target product. The reaction conditions of this method can be flexibly controlled. The catalyst used is a supported palladium catalyst containing two promoters: elements from Groups IB, IIB, and VIIB of the periodic table, and iron, cobalt, and nickel, as well as a basic promoter. The addition of the basic promoter leads to poor catalyst stability. Furthermore, although this process can flexibly generate aromatic amines or alicyclic amines, it cannot achieve the co-production of aromatic amines and alicyclic amines, and it cannot generate polycyclic alicyclic amines such as dicyclohexylamine.

[0010] In summary, while the phenol amination process offers advantages in terms of safety and environmental friendliness, it still suffers from technical drawbacks such as limited product composition, high operating costs, insufficient catalyst stability, and inadequate economic performance. Furthermore, the product selectivity of the aforementioned processes needs improvement; currently available literature struggles to precisely control the compositional ratios of amine products such as aniline, cyclohexylamine, and dicyclohexylamine, failing to meet diverse production demands. Therefore, a novel method for producing amine products is needed to address the problems inherent in traditional processes. Summary of the Invention

[0011] To overcome the shortcomings of existing processes, this invention provides a method for the preparation of aniline and the co-production of aliphatic amines via the hydroamination of phenol. This method uses readily available and inexpensive phenol, liquid ammonia, and hydrogen as raw materials. Through the highly efficient catalytic action of a supported palladium-based catalyst modified with phosphine ligands, it achieves high-yield and high-purity synthesis of amine products. It also possesses advantages such as controllable product composition, simple process flow, and low production cost, making it particularly suitable for large-scale industrial production.

[0012] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows:

[0013] A method for preparing aniline and co-producing fatty amines includes the following steps: reacting phenol, liquid ammonia and hydrogen in the presence of a phosphine-ligand-modified supported palladium-based catalyst.

[0014] As a preferred embodiment, a method for the co-production of fatty amines from aniline includes the following steps:

[0015] Phenol, solvent, and a phosphine-ligand-modified supported palladium-based catalyst were added to a reactor, and the reaction was carried out in the presence of ammonia and hydrogen. The mixture was then cooled and filtered.

[0016] The schematic diagram of the reaction formula for the preparation of aniline and the co-production of fatty amines in this invention is as follows:

[0017]

[0018] The solvents described in this invention include, but are not limited to, one or more of toluene, tetrahydrofuran, dioxane, ortho-xylene, and m-xylene, with m-xylene being preferred.

[0019] The mass ratio of solvent to phenol described in this invention is 2-5:1. If the amount of solvent is too small, the phenol will be difficult to dissolve completely, thus affecting the mass transfer of the reaction process; if the amount of solvent is too large, it will reduce the single-reactor production capacity and increase the energy consumption of post-processing.

[0020] The palladium to phenol mass ratio in the phosphine ligand-modified supported palladium catalyst of this invention is 1:1000-10000. Insufficient palladium in the catalyst will result in a slow reaction rate and more byproducts; excessive catalyst will not only increase the cost of catalyst use but also affect the filtration efficiency of the reaction solution.

[0021] The reaction temperature described in this invention is 90-250℃, preferably 110-170℃; the reaction pressure is 2-8 MPa, preferably 4-6 MPa. When the temperature and pressure increase, the hydrogenation process of the aromatic ring is accelerated, resulting in higher yields of cyclohexylamine and dicyclohexylamine products; when the temperature and pressure decrease, more aniline products can be obtained.

[0022] The mass ratio of liquid ammonia to phenol described in this invention is 1:10-5:1, preferably 1:10-5. If the amount of liquid ammonia used is too small, the amination reaction will be too slow and there will be more byproducts. If the amount of liquid ammonia used is too large, it will increase the pressure of the reaction process and the operating cost.

[0023] The phosphine ligand-modified supported palladium catalyst of the present invention comprises palladium, an auxiliary agent, a ligand, and a support.

[0024] The additives described in this invention are selected from one or more of gold, silver, copper, platinum, and ruthenium. When using weakly reducing metals such as gold and silver, more aniline products can be obtained; while when using strong reducing metals such as platinum and ruthenium, more cyclohexylamine and dicyclohexylamine products can be obtained.

[0025] The ligand described in this invention is a phosphine ligand. Using a phosphine ligand can promote the reducing power of metals and enhance the hydrogenation capacity of the catalyst.

[0026] Preferably, the ligand of the present invention is selected from one or more of triphenylphosphine, triethylphosphine, bis(2-diphenylphosphineethyl)phenylphosphine, and methyltriphenylphosphine bromide, with triphenylphosphine being the most preferred.

[0027] The carrier described in this invention is selected from one or more of alumina, titanium dioxide, diatomaceous earth, and ZSM-5, preferably alumina.

[0028] In the phosphine ligand-modified supported palladium catalyst of the present invention, the palladium content is 2-8 wt%, preferably 4-5 wt%, calculated by the total mass of the phosphine ligand-modified supported palladium catalyst; the content of the promoter is 0.1-0.5 wt%, preferably 0.2-0.3 wt%; and the phosphine ligand treatment concentration is 5-10 wt%, preferably 7%-9%.

[0029] The phosphine ligand-modified supported palladium-based catalyst described in this invention is prepared using a conventional excess impregnation method in the art, comprising the following steps:

[0030] Palladium salt and auxiliary salt are dissolved in deionized water at 70-90℃ to form a salt solution. Then, the carrier is added and stirred for 2-10 hours. After filtration, an ethanol solution containing phosphine ligand is added, followed by reduction with sodium borohydride. After filtration, the solution is dried in an oven at 100-120℃ for 10-24 hours. The solution is then calcined in an air or nitrogen atmosphere at a rate of 1-3℃ / min to 400-600℃ for 5-12 hours. After cooling, the solution is activated with hydrogen in a reactor.

[0031] In the catalyst preparation method of the present invention, the palladium salt and the auxiliary salt are one or more of the corresponding soluble halide salts, nitrates, and organic acid salts, preferably soluble nitrates.

[0032] In the catalyst preparation method of the present invention, the ligand is selected from one or more of triphenylphosphine, triethylphosphine, bis(2-diphenylphosphineethyl)phenylphosphine, and methyltriphenylphosphine bromide, preferably triphenylphosphine.

[0033] In the catalyst preparation method of the present invention, the activation temperature is 100-400℃, preferably 200-300℃; the activation pressure is 4-12MPa (gauge pressure), preferably 6-10MPa (gauge pressure); and the activation time is 1-10 hours, preferably 3-5 hours.

[0034] The product composition of the present invention includes aniline, cyclohexylamine, and dicyclohexylamine. It can produce a single product with a yield of greater than 95%, or it can produce multiple products. The mass ratio of aniline:cyclohexylamine:dicyclohexylamine is 0-0.2:0-0.7:0-0.5, preferably 0.1-0.2:0.4-0.6:0.2-0.4.

[0035] This invention achieves precise control over various amine products such as aniline, cyclohexylamine, and dicyclohexylamine by optimizing the catalyst system and reaction conditions, while significantly improving product yield and purity, and reducing production costs and environmental impact.

[0036] The beneficial effects of this invention are:

[0037] (1) The process route using phenol, liquid ammonia and hydrogen as raw materials is cheap and readily available. By controlling the catalyst structure, reaction temperature, pressure and liquid ammonia dosage, a variety of high-value-added amine compounds such as aniline, cyclohexylamine and dicyclohexylamine can be synthesized in a targeted manner. Compared with the traditional benzene nitration hydrogenation route, the use of strong acids and bases is eliminated, the process is simpler, and the yield and purity are significantly improved.

[0038] (2) The supported palladium-based catalyst modified with phosphine ligands uses alumina as a support and adds gold, platinum and other additives. Finally, the catalyst surface is modified with phosphine ligands. Through the synergistic effect of additives and palladium, the acidity and basicity of the catalyst and the metal dispersion are optimized. Phosphine ligands improve the surface structure of the catalyst, condition the electronic structure of the catalyst, suppress side reactions such as condensation, and improve catalytic activity and selectivity. After the support is modified, the acidity distribution is more reasonable, reducing the deamination reaction of aromatic amines, extending the catalyst life and reducing the cost of recycling. Detailed Implementation

[0039] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0040] The main raw materials and testing instruments used in the following examples are as follows: Phenol was purchased from Innokai with a purity greater than 99%; m-xylene, tetrahydrofuran, ethanol, alumina, and phosphine ligands were all purchased from Beijing Innokai Technology Co., Ltd.

[0041] The conditions for gas chromatography analysis in the following examples were as follows: Agilent DB-5 column, injection port temperature 280°C, FID detector temperature 300°C, column flow rate 1.5 ml / min, hydrogen flow rate 35 ml / min, air flow rate 350 ml / min, and temperature program mode: 60°C held for 1 min, then increased to 280°C at 20°C / min and held for 10 min.

[0042] Example 1

[0043] 1# Phenol amination to prepare aniline and co-produce fatty amines

[0044] Prepare a nitrate impregnation solution containing 3g palladium and 0.2g platinum in 200ml of deionized water. Heat and stir to 80℃ to form a homogeneous solution. Add 100g alumina support and impregnate at 80℃ for 10h. Filter the solution and add 10g of ethanol solution containing 10wt% triphenylphosphine. Stir at 80℃ for 2h. Add 10g sodium borohydride and stir the reaction for 5h. Filter the solution and dry in an oven at 110℃ for 12h. Finally, transfer the solution to a muffle furnace and calcine at 400℃ for 8h in air atmosphere at a rate of 1℃ / min. After natural cooling, the phosphine ligand-modified supported palladium-based catalyst precursor is obtained.

[0045] The catalyst precursor consists of 3 wt% palladium, 0.2 wt% platinum, 0.5 wt% phosphine ligand, and the remainder is a support, based on the proportion of the corresponding metal element to the total mass of the catalyst.

[0046] 4g of phosphine-ligand-modified supported palladium-based catalyst precursor was added to a 5.0L high-pressure reactor, along with 150ml of deionized water. The reactor was activated at 300℃ and 5MPa hydrogen pressure for 3 hours to obtain the phosphine-ligand-modified supported palladium-based catalyst. The deionized water was filtered through the reactor's built-in filter. 120g of phenol and 480g of tetrahydrofuran were added, and the mixture was purged three times each with 1MPa nitrogen and hydrogen. 30g of liquid ammonia was introduced, and the reactor was pressurized to 2MPa with hydrogen. Stirring was started at 700 rpm, and the temperature of the material in the reactor was raised and maintained at 150℃. The hydrogen pressure was maintained at 4MPa, and the reaction was stopped after 8 hours. The temperature was lowered to below 50℃, the pressure was released, and the mixture was purged three times with 1MPa nitrogen. The reaction solution in the reactor was filtered, and the catalyst remained in the reactor for further evaluation. The samples were analyzed by liquid chromatography. The conversion rate of phenol in the reaction solution was 99.7%. Gas chromatography analysis showed that the selectivity of aniline was 29.9%, the selectivity of cyclohexylamine was 69.7%, and the selectivity of dicyclohexylamine was 0.4%.

[0047] Comparative Example 1

[0048] The catalyst precursor preparation method of No. 1 was used, but without the addition of an ethanol solution containing 10% triphenylphosphine. The amination reaction was carried out, and samples were taken for liquid chromatography analysis. The conversion rate of phenol in the reaction solution was 62.2%. Gas chromatography analysis showed that the selectivity of aniline was 96.2% and the selectivity of cyclohexylamine was 3.8%.

[0049] Example 2

[0050] 2# Phenol amination to prepare aniline and co-produce fatty amines

[0051] Prepare a nitrate impregnation solution containing 2g palladium and 0.2g gold in 200ml of deionized water. Heat and stir to 80℃ to form a homogeneous solution. Add 100g of silica support and impregnate at 80℃ for 10 hours. Filter the solution and add 10g of ethanol solution containing 8wt% triethylphosphine. Stir at 80℃ for 4 hours. Add 10g of sodium borohydride and stir the reaction for 2 hours. Filter the solution and dry in an oven at 110℃ for 12 hours. Finally, transfer the solution to a tube furnace and calcine at 500℃ for 6 hours under a nitrogen atmosphere at a rate of 2℃ / min. After natural cooling, the supported palladium-based catalyst precursor modified with phosphine ligand #2 is obtained.

[0052] The catalyst precursor consists of 2 wt% palladium, 0.2 wt% gold, 0.5 wt% phosphine ligand, and the remainder is a support, based on the proportion of the corresponding metal element to the total mass of the catalyst.

[0053] Two g of phosphine-ligand-modified supported palladium-based catalyst precursor was added to a 5.0 L high-pressure reactor, along with 150 ml of deionized water. The reactor was activated at 200 °C and 7 MPa for 1 h to obtain the phosphine-ligand-modified supported palladium-based catalyst. The deionized water was filtered through the reactor's built-in filter. 320 g of phenol and 960 g of toluene were added, and the mixture was purged three times each with 1 MPa nitrogen and hydrogen. 64 g of liquid ammonia was introduced, and the reactor was pressurized to 2 MPa with hydrogen. Stirring was started at 700 rpm, and the temperature of the material in the reactor was raised and maintained at 170 °C. The hydrogen pressure was maintained at 6 MPa, and the reaction was stopped after 4 hours. The temperature was lowered to below 50 °C, the pressure was released, and the mixture was purged three times with 1 MPa nitrogen. The reaction solution in the reactor was filtered, and the catalyst remained in the reactor for further evaluation. Samples were taken for liquid chromatography analysis. The conversion rate of phenol in the reaction solution was 99.5%. Gas chromatography analysis showed that the selectivity of aniline was 11.4%, the selectivity of cyclohexylamine was 35.5%, and the selectivity of dicyclohexylamine was 53.1%.

[0054] Comparative Example 2

[0055] The catalyst precursor preparation method of No. 2 was used, but without the addition of gold nitrate solution. The same amination reaction scheme was used, and samples were taken for liquid chromatography analysis. The conversion rate of phenol in the reaction solution was 54.1%. Gas chromatography analysis showed that the selectivity of aniline was 99.9% and the selectivity of cyclohexylamine was 0.1%.

[0056] Example 3

[0057] 3# Phenol amination to prepare aniline and co-produce fatty amines

[0058] Prepare a nitrate impregnation solution containing 5g palladium and 0.3g silver in 250ml of deionized water. Heat and stir to 80℃ to form a homogeneous solution. Add 100g of titanium dioxide support and impregnate at 80℃ for 8 hours. Filter the solution and add 10g of an ethanol solution containing 7wt% bis(2-diphenylphosphineethyl)phenylphosphine. Stir at 80℃ for 2 hours. Add 10g of sodium borohydride and stir the reaction for 8 hours. Filter the solution and dry it in an oven at 110℃ for 12 hours. Finally, transfer the solution to a tube furnace and calcine at 600℃ for 12 hours under a nitrogen atmosphere at a rate of 3℃ / min. After natural cooling, the supported palladium-based catalyst precursor modified with phosphine ligand #3 is obtained.

[0059] The catalyst precursor consists of 5 wt% palladium, 0.3 wt% silver, 0.5 wt% phosphine ligand, and the remainder is a support, based on the proportion of the corresponding metal element to the total mass of the catalyst.

[0060] 1 g of phosphine-ligand-modified supported palladium-based catalyst precursor was added to a 5.0 L high-pressure reactor, along with 150 ml of deionized water. The reactor was activated for 5 h at 400 °C and 10 MPa hydrogen pressure to obtain the phosphine-ligand-modified supported palladium-based catalyst. The deionized water was filtered through the reactor's built-in filter. 150 g of phenol and 300 g of o-xylene were added, and the mixture was purged three times each with 1 MPa nitrogen and hydrogen. 25 g of liquid ammonia was introduced, and the reactor was pressurized to 1 MPa with hydrogen. Stirring was started at 600 rpm, and the temperature of the material in the reactor was raised and maintained at 90 °C. The hydrogen pressure was maintained at 2 MPa, and the reaction was stopped after 7 hours. The temperature was lowered to below 50 °C, the pressure was released, and the mixture was purged three times with 1 MPa nitrogen. The reaction solution in the reactor was filtered, and the catalyst remained in the reactor for further evaluation. Samples were taken for liquid chromatography analysis. The conversion rate of phenol in the reaction solution was 99.2%. Gas chromatography analysis showed that the selectivity of aniline was 5.4%, the selectivity of cyclohexylamine was 67.3%, and the selectivity of dicyclohexylamine was 27.3%.

[0061] Comparative Example 3

[0062] The catalyst precursor preparation method of No. 3 was adopted, but the catalyst was not calcined. The same amination reaction scheme was used. The samples were analyzed by liquid chromatography. The conversion rate of phenol in the reaction solution was 7.4%. Gas chromatography analysis showed that the selectivity of aniline was 99.9% and the selectivity of cyclohexylamine was 0.1%.

[0063] Example 4

[0064] 4# Phenol amination to prepare aniline and co-produce fatty amines

[0065] Prepare a nitrate impregnation solution containing 10g palladium and 0.5g copper in 200ml of deionized water. Heat and stir to 80℃ to form a homogeneous solution. Add 100g diatomaceous earth support and impregnate at 80℃ for 6 hours. Filter the solution and add 10g of ethanol solution containing 9wt% triphenylphosphine. Stir at 80℃ for 4 hours. Add 10g sodium borohydride and stir the reaction for 12 hours. Filter the solution and dry it in an oven at 110℃ for 12 hours. Finally, transfer the solution to a muffle furnace and calcine at 600℃ for 5 hours under a nitrogen atmosphere at a rate of 3℃ / min. After natural cooling, the supported palladium-based catalyst precursor modified with phosphine ligand #4 is obtained.

[0066] The catalyst precursor consists of 10 wt% palladium, 0.5 wt% copper, 0.5 wt% phosphine ligand, and the remainder is a support, based on the proportion of the corresponding metal element to the total mass of the catalyst.

[0067] 3g of phosphine-ligand-modified supported palladium-based catalyst precursor was added to a 5.0L high-pressure reactor, along with 150ml of deionized water. Activation was performed at 100℃ and 8MPa hydrogen pressure for 7h to obtain the phosphine-ligand-modified supported palladium-based catalyst. The deionized water was filtered through the reactor's built-in filter. 480g of phenol and 2400g of m-xylene were added, and the mixture was purged three times each with 1MPa nitrogen and hydrogen. 48g of liquid ammonia was introduced, and the reactor was pressurized to 6MPa with hydrogen. Stirring was started at 900 rpm, and the temperature of the material in the reactor was raised and maintained at 250℃. The hydrogen pressure was maintained at 8MPa, and the reaction was stopped after 10 hours. The temperature was lowered to below 50℃, the pressure was released, and the mixture was purged three times with 1MPa nitrogen. The reaction solution in the reactor was filtered, and the catalyst remained in the reactor for further evaluation. The samples were analyzed by liquid chromatography. The conversion rate of phenol in the reaction solution was 98.7%. Gas chromatography analysis showed that the selectivity of aniline was 1.8%, the selectivity of cyclohexylamine was 71.5%, and the selectivity of dicyclohexylamine was 26.7%.

[0068] Example 5

[0069] 5# Phenol amination to prepare aniline and co-produce fatty amines

[0070] Prepare a nitrate impregnation solution containing 0.5g palladium and 0.05g ruthenium in 150ml of deionized water. Heat and stir to 80℃ to form a homogeneous solution. Add 100g ZSM-5 support and impregnate at 80℃ for 2 hours. Filter the solution and add 10g of ethanol solution containing 10wt% triethylphosphine. Stir at 80℃ for 24 hours. Add 10g sodium borohydride and stir for 12 hours. Filter the solution and dry in an oven at 110℃ for 12 hours. Finally, transfer the solution to a muffle furnace and calcine at 550℃ for 8 hours in air atmosphere at a rate of 2℃ / min. After natural cooling, the supported palladium-based catalyst precursor modified with phosphine ligand #5 is obtained.

[0071] The catalyst precursor consists of 0.5 wt% palladium, 0.05 wt% ruthenium, 0.5 wt% phosphine ligand, and the remainder is a support, based on the proportion of the corresponding metal element to the total mass of the catalyst.

[0072] 5g of phosphine-ligand-modified supported palladium-based catalyst precursor was added to a 5.0L high-pressure reactor, along with 150ml of deionized water. The reactor was activated at 200℃ and 4MPa hydrogen pressure for 10h to obtain the phosphine-ligand-modified supported palladium-based catalyst. The deionized water was filtered through the reactor's built-in filter. 1000g of phenol and 4000g of dioxane were added, and the mixture was purged three times each with 1MPa nitrogen and hydrogen. 125g of liquid ammonia was introduced, and the reactor was pressurized to 5MPa with hydrogen. Stirring was started at 800 rpm, and the temperature of the material in the reactor was raised and maintained at 150℃. The hydrogen pressure was maintained at 7MPa. After 6 hours of reaction, the reaction was stopped, cooled to below 50℃, depressurized, and purged three times with 1MPa nitrogen. The reaction solution in the reactor was filtered, and the catalyst remained in the reactor for further evaluation. Samples were taken for liquid chromatography analysis. The conversion rate of phenol in the reaction solution was 99.7%. Gas chromatography analysis showed that the selectivity of aniline was 0.2%, the selectivity of cyclohexylamine was 47.2%, and the selectivity of dicyclohexylamine was 52.6%.

[0073] Example 6

[0074] 6# Phenol amination to prepare aniline and co-produce fatty amines

[0075] Prepare a nitrate impregnation solution containing 8g palladium and 0.1g platinum in 300ml of deionized water. Heat and stir to 80℃ to form a homogeneous solution. Then add 50g alumina and 50g silica support and impregnate at 80℃ for 5 hours. After filtration, add 10g of ethanol solution containing 6wt% methyltriphenylphosphine bromide and stir at 80℃ for 4 hours. Add 10g sodium borohydride and stir for 2 hours. After filtration, dry in an oven at 110℃ for 12 hours. Finally, transfer to a muffle furnace and calcine at 400℃ for 7 hours in air atmosphere at a rate of 3℃ / min. After natural cooling, the supported palladium-based catalyst precursor modified with 6# phosphine ligand is obtained.

[0076] The catalyst composition is as follows: palladium 15 wt%, platinum 0.1 wt%, phosphine ligand 0.5 wt%, and the remainder is the support, based on the corresponding metal element as a percentage of the total mass of the catalyst.

[0077] 4g of phosphine-ligand-modified supported palladium-based catalyst precursor was added to a 5.0L high-pressure reactor, along with 150ml of deionized water. The reactor was activated at 300℃ and 5MPa hydrogen pressure for 4 hours to obtain the phosphine-ligand-modified supported palladium-based catalyst. The deionized water was filtered through the reactor's built-in filter. 320g of phenol and 640g of toluene were added, and the mixture was purged three times each with 1MPa nitrogen and hydrogen. 40g of liquid ammonia was introduced, and the reactor was pressurized to 3MPa with hydrogen. Stirring was started at 800 rpm, and the temperature of the material in the reactor was raised and maintained at 160℃. The hydrogen pressure was maintained at 5MPa, and the reaction was stopped after 6 hours. The temperature was lowered to below 50℃, the pressure was released, and the mixture was purged three times with 1MPa nitrogen. The reaction solution in the reactor was filtered, and the catalyst remained in the reactor for further evaluation. The samples were analyzed by liquid chromatography, and the conversion rate of phenol in the reaction solution was 99.7%. Gas chromatography analysis showed that the selectivity of aniline was 0.1%, the selectivity of cyclohexylamine was 4.1%, and the selectivity of dicyclohexylamine was 95.8%.

[0078] Finally, it should be noted that the above embodiments are only used to describe preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that various modifications and improvements made to the technical solutions of the present invention by means of modifications or equivalent substitutions should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing aniline and co-producing fatty amines by amination of phenol, comprising the following steps: Phenol, liquid ammonia, and hydrogen react in the presence of a phosphine-ligand-modified supported palladium catalyst.

2. The method according to claim 1, characterized in that, The mass ratio of palladium to phenol in the phosphine ligand-modified supported palladium catalyst is 1:1000-10000.

3. The method according to claim 1 or 2, characterized in that the temperature of the reaction is 90-250°C, preferably 110-170°C; and the pressure of the reaction is 2-8 MPa, preferably 4-6 MPa.

4. The method according to any one of claims 1-3, characterized in that, The mass ratio of liquid ammonia to phenol is 1:10-5:1, preferably 1:10-5.

5. The method according to any one of claims 1-4, characterized in that, The phosphine ligand-modified supported palladium catalyst comprises palladium, an auxiliary agent, a ligand, and a support.

6. The method according to any one of claims 1-5, characterized in that, The additives are selected from one or more of gold, silver, copper, platinum, and ruthenium.

7. The method according to any one of claims 1-6, characterized in that, The ligand is a phosphine ligand, preferably one or more of triphenylphosphine, triethylphosphine, bis(2-diphenylphosphineethyl)phenylphosphine, and methyltriphenylphosphine bromide.

8. The method according to any one of claims 1-7, characterized in that, In the phosphine ligand-modified supported palladium catalyst, the palladium content is 2-8 wt%, preferably 4-5 wt%, calculated by the total mass of the phosphine ligand-modified supported palladium catalyst; the content of the promoter is 0.1-0.5 wt%, preferably 0.2-0.3 wt%; and the phosphine ligand treatment concentration is 5-10 wt%, preferably 7%-9%.

9. The method according to any one of claims 1-8, characterized in that, The method for preparing the phosphine ligand-modified supported palladium-based catalyst includes the following steps: Palladium salt and auxiliary salt are dissolved in deionized water at 70-90℃ to form a salt solution. Then, the carrier is added and stirred for 2-10 hours. After filtration, an ethanol solution containing phosphine ligand is added, followed by reduction with sodium borohydride. After filtration, the solution is dried in an oven at 100-120℃ for 10-24 hours. The solution is then calcined in an air or nitrogen atmosphere at a rate of 1-3℃ / min to 400-600℃ for 5-12 hours. After cooling, the solution is activated with hydrogen in a reactor.

10. The method according to any one of claims 1-9, characterized in that, The activation temperature is 100-400℃, preferably 200-300℃; the activation pressure is 4-12MPa gauge pressure, preferably 6-10MPa gauge pressure; and the activation time is 1-10 hours, preferably 3-5 hours.

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