Method for preparing ethylenediamine

Abstract

The invention relates to a method for preparing ethylenediamine. The method comprises the following steps: adding ethanolamine into a reaction kettle loaded with a catalyst, sequentially introducing ammonia gas and hydrogen into the reaction kettle, reacting at 170-210 DEG C for 10-18 hours, and carrying out catalytic ammoniation reaction to generate ethylenediamine, the catalyst is of a core-shell structure and comprises a silicon dioxide-aluminum oxide composite shell and a metal core, wherein the metal core is metal M1 and metal M2 which are Ni and Cu respectively; the total molar weight of Ni and Cu accounts for 67-91% of the whole catalyst, and the molar ratio of Ni to Cu is (2-4): 1. According to the invention, essential potential safety hazards existing in the original process are avoided, and green and sustainable production of ethidene diamine is realized.

Description

Technical Field

[0001] The present invention relates to a preparation technology of ethylenediamine, in particular to a method for preparing ethylenediamine from ethanolamine as an initial raw material and a catalyst thereof. Background Art

[0002] Ethylenediamine (EDA) is an important chemical raw material and fine chemical intermediate. It is widely used in pesticide, food, medicine, automobile, shipbuilding, civil engineering, water treatment, papermaking, rubber, textile and electronics industries. It can be used as a basic raw material for epoxy resin curing agent, dye intermediate, electroplating liquid surfactant, lubricant additive, paper wet strength agent, soil conditioner, etc.

[0003] The synthesis methods of ethylenediamine mainly include the dichloroethane method, the ethylene glycol method, the ethylene oxide method, the ethanolamine method, etc. In the early days, the main industrial synthesis method of ethylenediamine was the dichloroethane method, and dichloroethane was produced from petroleum-based chemicals, but this method has the disadvantages of poor product quality, high energy consumption, serious equipment corrosion, and large discharge of three wastes (US 5364971 A). For this reason, people have been exploring new methods and processes for preparing ethylenediamine, including using ethylene glycol as a raw material, preparing ethylenediamine by catalytic amination (yield up to 60%), generating a large amount of ethanolamine intermediates and by-products such as piperazine and long-chain amines, and the reaction conditions are very harsh (180°C, 30MPa, US 3270059 A). However, the ethylene oxide method has obvious disadvantages such as high cost, low product purity and low yield (4.5%, WO 2009083580 A1). In terms of reaction principle, the preparation of ethylenediamine by catalytic amination of ethanolamine (MEA) is the most concise and ideal route. The process basically does not discharge three wastes, and produces high value-added by-products such as piperazine. Most of the literature and patents reported on this type of method use precious metal catalysts (Ni-Re / γ-Al2O3 and Ni-Re-B / SiO2), and the yield of the target product ethylenediamine is low (US 5750790 A, 38.82% and US 6534441 B1, 31.32%).

[0004] In summary, the synthesis of ethylenediamine by ammoniating ethanolamine with a heterogeneous non-precious metal catalyst is a green and sustainable process. Therefore, it is of great significance to study a safe and high-yield ethylenediamine production method suitable for industrial production and its corresponding catalyst system. Summary of the invention

[0005] The purpose of the present invention is to solve the deficiencies of the prior art and provide a method for preparing ethylenediamine. The method uses a core-shell structure catalyst to synthesize ethylenediamine in high yield by catalytic amination of ethanolamine; the catalyst used has a core-shell structure, wherein the shell is a silicon dioxide-aluminum oxide composite material, and the limited internal space is conducive to the concentration of reactants, accelerates the collision between the reactants and NH3 / H2 molecules, thereby improving the reaction efficiency; inhibits the self-coupling reaction and peralkylation reaction of the product, and improves the selectivity of the target product. The bimetallic ratio of the metal core can regulate the electronic effect of the catalyst, thereby improving the dehydrogenation and hydrogenation activity of the catalyst. The present invention avoids the inherent safety hazards existing in the original process and realizes the green and sustainable production of ethylenediamine.

[0006] The technical solution of the present invention is:

[0007] A method for preparing ethylenediamine, the method comprising the steps of:

[0008] Ethanolamine is placed in a reactor loaded with a catalyst, and ammonia and hydrogen are introduced into the reactor in sequence, and the reaction is carried out at 170°C to 210°C for 10-18 hours to generate ethylenediamine by catalytic amination reaction;

[0009] Wherein, the mass ratio is ethanolamine: catalyst = 3-20:1; ammonia pressure: 0.3-0.7MPa; hydrogen pressure: 1-3MPa;

[0010] The catalyst is a core-shell structure, which comprises a silicon dioxide-aluminum oxide composite shell and a metal core; the metal core is metal M1 and metal M2, which are Ni and Cu respectively; the total molar amount of Ni and Cu accounts for 67-91% of the whole catalyst, and the molar ratio of metal Ni to Cu is 2-4:1.

[0011] The diameter of the metal core is 10-25 nm, and the thickness of the shell is 5-20 nm.

[0012] The method for preparing the catalyst comprises the following steps:

[0013] (1) Continuous preparation of metal core:

[0014] The nitrate solution A and the Na2CO3 solution B are injected at a rate of 5.00-15.00 mL / min by a high-pressure booster pump, respectively, and mixed at a constant temperature of 50-70°C in a membrane disperser; the turbid liquid is collected, centrifuged, washed to neutrality, and dried at 80-100°C for 10-24h; finally, the cooled catalyst precursor is ground into powder, heated to 400-600°C and calcined for 2-4h at a heating rate of 5-10°C / min to obtain metal oxide nanoparticles, i.e., metal cores;

[0015] Among them, the concentration of nitrate solution is 0.10-0.30M, and the concentration of Na2CO3 solution is 0.20-0.60M;

[0016] The nitrate is copper nitrate and nickel nitrate; the molar ratio is Ni:Cu=2-4:1;

[0017] The metal oxides are specifically CuO, NiO and NiO-CuO; the particle size of the nanoparticles is 10-25nm;

[0018] (2) Covering the metal core with a shell;

[0019] Add metal oxide nanoparticles to H2O to obtain a metal oxide suspension; ultrasonically disperse for 30 to 60 minutes, continue to add tetrapropylammonium hydroxide (TPAOH) and ultrasonically disperse for 30 to 60 minutes, then drop tetraethyl orthosilicate (TEOS corresponds to SiO2) into it and hydrolyze at 40 to 60°C; finally, drop a mixed solution of Al(NO3)3, NaOH and H2O into the above mixture and stir at room temperature for 1 hour. Add the above mixed solution to a hydrothermal kettle, hydrothermally react at 160 to 180°C for 24 to 48 hours to obtain a catalyst precursor, then calcine at 400 to 600°C for 2 to 4 hours, and reduce to H2 at 400 to 600°C for 2 to 3 hours to obtain the final catalyst.

[0020] Wherein, the concentration of the metal oxide suspension is 0.2-1wt%;

[0021] The molar ratio is TEOS:Al(NO3)3·9H2O:TPAOH:NaOH:H2O in the mixed solution=2-20:1:20-150:200-1500:1500-10000;

[0022] The molar ratio is, metal oxide: (ethyl orthosilicate + Al(NO3)3·9H2O) = 0.1 to 1.0;

[0023] The essential features of the present invention are:

[0024] The present invention adopts a core-shell structure of a multiphase catalyst of Ni-Cu bimetallic wrapped with silicon dioxide-aluminum oxide, and the metal core is prepared continuously; due to the presence of the silicon dioxide-aluminum oxide shell, the service life of the catalyst can be increased. Through the precise design of the core-shell structure of the catalyst, the collision between the reactant and the NH3 / H2 molecule is accelerated, thereby improving the reaction efficiency; inhibiting the self-coupling reaction and peralkylation reaction of the product, improving the selectivity of the target product, and reducing the production of by-products such as piperazine and long-chain amines; further, regulating the bimetallic ratio of the metal core to regulate the electronic effect of the catalyst, thereby improving the dehydrogenation and hydrogenation activity of the catalyst.

[0025] Ultimately, the advantages of its core-shell structure and controllable shell structure are utilized to achieve efficient and highly selective catalytic amination of ethanolamine to ethylenediamine.

[0026] The beneficial effects of the present invention are:

[0027] The present invention provides a method for synthesizing ethylenediamine using ethanolamine as a raw material, which can solve the drawbacks of the existing production process, such as high difficulty, serious environmental pollution and low yield. The metal core of the core-shell structure catalyst is continuously prepared by using a membrane dispersion microreactor, and a silicon dioxide-aluminum oxide composite shell is used at the same time; the catalyst used in the invention is easy to prepare, and the shell carrier and metal core active components of the catalyst are both cheap and easy to obtain.

[0028] The catalytic amination reaction conditions of the present invention are relatively mild, the equipment requirements are not high, and the economic feasibility of the reaction is improved. Due to the unique core-shell structure of the catalyst, by-products such as piperazine and long-chain amines are less. During the catalytic process, the conversion rate of ethanolamine can reach 81%, the selectivity of ethylenediamine is 83%, and piperazine (PA) and triethylenediamine (TEDA) are obtained at yields of 11% and 5%, respectively (see Example 28 for details). BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The catalyst 3Ni-1Cu obtained in Example 8 间歇 @12.5SiO2-1Al2O3-0.2 (corresponding to 3NiO-1CuO obtained in Example 1 间歇 TEM images of nanoparticles;

[0030] Figure 2 This is the TEM image of the catalyst 3Ni-1Cu@12.5SiO2-1Al2O3-0.2 obtained in Example 8 (corresponding to the 3NiO-1CuO nanoparticles obtained in Example 3). DETAILED DESCRIPTION

[0031] The synthetic route of the present invention is shown in the following reaction formula:

[0032]

[0033] The technical features of the present invention are further described below by examples:

[0034] Example 1: 3NiO-1CuO 间歇 Preparation of nanoparticles

[0035] 4.36 g Ni(NO3)2·6H2O (0.0150 mol) and 1.21 g Cu(NO3)2·3H2O (0.0050 mol) were added to 100 mL of distilled water containing 3.00 g polyethylene glycol (PEG-20000). After stirring the solution for 30 min, 4.50 g urea was added and the mixture was heated to 90 °C for 24 h. The precipitate was collected by centrifugation, washed with ethanol and distilled water, dried at 100 °C for 10 h, and calcined at 400 °C in air for 4 h to obtain 3NiO-1CuO 间歇 Nanoparticles.

[0036] Example 2: Preparation of 2NiO-1CuO Nanoparticles

[0037] Solution A [3.87g Ni(NO3)2·6H2O (0.0133mol), 1.62g Cu(NO3)2·3H2O (0.0067mol) dissolved in 100mL distilled water] and solution B [4.24g Na2CO3 (0.0400mol) dissolved in 100mL distilled water] were injected at a rate of 5.00mL / min using a high-pressure booster pump, mixed through a membrane disperser (constant temperature 60°C), and the turbid liquid was collected, centrifuged, washed with deionized water and ethanol until neutral, and dried in an oven at 100°C for 10h. Finally, the cooled catalyst precursor was ground into powder, heated to 400°C in a muffle furnace and calcined for 4h at a heating rate of 5°C / min to obtain 2NiO-1CuO nanoparticles (i.e., metal cores).

[0038] Example 3: Preparation of 3NiO-1CuO Nanoparticles

[0039] Solution A [4.36g Ni(NO3)2·6H2O (0.0150mol), 1.21g Cu(NO3)2·3H2O (0.0050mol) dissolved in 100mL distilled water] and solution B [4.24g Na2CO3 (0.0400mol) dissolved in 100mL distilled water] were injected at a rate of 5.00mL / min using a high-pressure booster pump, mixed through a membrane disperser (constant temperature 60°C), and the turbid liquid was collected, centrifuged, washed with deionized water and ethanol until neutral, and dried in an oven at 100°C for 10h. Finally, the cooled catalyst precursor was ground into powder, heated to 400°C in a muffle furnace and calcined for 4h at a heating rate of 5°C / min to obtain 3NiO-1CuO nanoparticles.

[0040] Example 4: Preparation of 4NiO-1CuO Nanoparticles

[0041] Solution A [5.82g Ni(NO3)2·6H2O (0.0200mol), 1.21g Cu(NO3)2·3H2O (0.0050mol) dissolved in 100mL distilled water] and solution B [5.30g Na2CO3 (0.0500mol) dissolved in 100mL distilled water] were injected at a rate of 5.00mL / min using a high-pressure booster pump, mixed through a membrane disperser (constant temperature 60°C), and the turbid liquid was collected, centrifuged, washed with deionized water and ethanol until neutral, and dried in an oven at 100°C for 10h. Finally, the cooled catalyst precursor was ground into powder, heated to 400°C in a muffle furnace and calcined for 4h at a heating rate of 5°C / min to obtain 4NiO-1CuO nanoparticles.

[0042] Example 5: Preparation of Ni-Cu@SiO2-0.2 catalyst

[0043] 0.25 g NiO-CuO nanoparticles (3.30 mmol, obtained from Examples 1-4) were added to 50 mL of distilled water and subjected to ultrasonic treatment for 30 min. Then, in an ultrasonic bath, 0.1394 g (i.e., 0.6691 mmol) of tetraethyl orthosilicate (TEOS) (corresponding to a molar ratio of the shell-forming agent to the metal core of 0.2- (the molar amount of the metal core is the sum of the molar amounts of Ni and Cu) and 10 mL of NH3·H2O (25 wt%, containing 0.13 mol of ammonia) were added in sequence under ultrasonic treatment (60 min), and then ultrasonic treatment was performed for 1 h, centrifuged, washed with deionized water and ethanol until neutral, dried at 80 ° C for 10 h, calcined at 400 ° C for 4 h, and reduced with H2 at 550 ° C for 2 h to obtain four core-shell catalysts 3Ni-1Cu 间歇 @SiO2-0.2, 2Ni-1Cu@SiO2-0.2, 3Ni-1Cu@SiO2-0.2 and 4Ni-1Cu@SiO2-0.2.

[0044] Example 6: Preparation of Ni-Cu@Al2O3-0.2 catalyst

[0045] 0.25 g NiO-CuO nanoparticles (3.30 mmol, obtained from Examples 1-4) were added to 50 mL of distilled water and subjected to ultrasonic treatment for 30 min. Then, in an ultrasonic bath, 0.2510 g (i.e., 0.6691 mmol) Al(NO3)3·9H2O (corresponding to a molar ratio of shell-forming reagent to metal core of 0.2) and 10 mL NH3·H2O (25 wt%, containing 0.13 mol of ammonia) were added in sequence under ultrasonic treatment (60 min), and then ultrasonic treatment was performed for 1 h, centrifuged, washed with deionized water and ethanol until neutral, dried at 80°C for 10 h, calcined at 400°C for 4 h, and reduced with H2 at 550°C for 2 h to obtain four core-shell catalysts 3Ni-1Cu 间歇 @Al2O3-0.2, 2Ni-1Cu@Al2O3-0.2, 3Ni-1Cu@Al2O3-0.2 and 4Ni-1Cu@Al2O3-0.2.

[0046] Example 7: Preparation of Ni-Cu@5SiO2-1Al2O3-0.2 catalyst

[0047] 0.25 g NiO-CuO nanoparticles (3.2761-3.3043 mmol, obtained from Example 1-4) were added to 40 mL H2O and ultrasonically dispersed for 60 min. 1.9320 g (i.e., 9.500 mmol) TPAOH was added and ultrasonically dispersed for 60 min. Then 0.1744 g (i.e., 0.8371 mmol) TEOS was added dropwise to the mixed solution, hydrolyzed at 60°C, and stirred at room temperature for 1 h. A mixed solution of 0.1105 g (i.e. 0.2946 mmol) Al(NO3)3·9H2O, 3.2640 g (i.e. 81.60 mmol) NaOH and 10 g (i.e. 555.56 mmol) H2O was added dropwise to the above mixture, and then added to a hydrothermal kettle, and hydrothermally reacted at 170°C for 36 h to obtain a catalyst precursor, which was centrifuged, washed with deionized water and ethanol until neutral, dried at 80°C for 10 h, calcined at 400°C for 4 h, and reduced with H2 at 500°C for 2 h to obtain four core-shell catalysts 3Ni-1Cu 间歇 @5SiO2-1Al2O3-0.2, 2Ni-1Cu@5SiO2-1Al2O3-0.2, 3Ni-1Cu@5SiO2-1Al2O3-0.2 and 4Ni-1Cu@5SiO2-1Al2O3-0.2.

[0048] Example 8: Preparation of Ni-Cu@12.5SiO2-1Al2O3-0.2 catalyst

[0049] 0.25 g NiO-CuO nanoparticles (3.2761-3.3043 mmol, obtained from Example 1-4) were added to 40 mL H2O and ultrasonically dispersed for 60 min. 1.9320 g (i.e. 9.500 mmol) TPAOH was added and ultrasonically dispersed for 60 min. Then 0.2098 g (i.e. 1.007 mmol) TEOS was added dropwise to the mixed solution, hydrolyzed at 60°C, and stirred at room temperature for 1 h. A mixed solution of 0.0533 g (i.e. 0.1421 mmol) Al(NO3)3·9H2O, 3.2640 g (i.e. 81.60 mmol) NaOH and 10 g (i.e. 555.56 mmol) H2O was added dropwise to the above mixture, and then added to a hydrothermal kettle, and hydrothermally reacted at 170°C for 36 h to obtain a catalyst precursor, which was centrifuged, washed with deionized water and ethanol until neutral, dried at 80°C for 10 h, calcined at 400°C for 4 h, and reduced with H2 at 500°C for 2 h to obtain four core-shell catalysts 3Ni-1Cu 间歇 @12.5SiO2-1Al2O3-0.2, 2Ni-1Cu@12.5SiO2-1Al2O3-0.2, 3Ni-1Cu@12.5SiO2-1Al2O3-0.2 and 4Ni-1Cu@12.5SiO2-1Al2O3-0.2.

[0050] The molar ratio of the metal core nanoparticles to the shell-forming agent is 0.1 to 0.5, and the shell-forming agent of the catalyst is tetraethyl orthosilicate.

[0051] Example 9: Preparation of Ni-Cu@25SiO2-1Al2O3-0.2 catalyst

[0052] 0.25 g NiO-CuO nanoparticles (3.2761-3.3043 mmol, obtained from Examples 1-4) were added to 40 mL H2O and ultrasonically dispersed for 60 min. 1.9320 g (i.e., 9.500 mmol) TPAOH was then added and ultrasonically dispersed for 60 min. 0.2252 g (i.e., 1.081 mmol) TEOS was then added dropwise to the mixed solution, hydrolyzed at 60°C, and stirred at room temperature for 1 h. A mixed solution of 0.0286 g (i.e. 0.0762 mmol) Al(NO3)3·9H2O, 3.2640 g (i.e. 81.60 mmol) NaOH and 10 g (i.e. 555.56 mmol) H2O was added dropwise to the above mixture, and then added to a hydrothermal kettle, and hydrothermally reacted at 170°C for 36 h to obtain a catalyst precursor, which was centrifuged, washed with deionized water and ethanol until neutral, dried at 80°C for 10 h, calcined at 400°C for 4 h, and reduced with H2 at 500°C for 2 h to obtain four core-shell catalysts 3Ni-1Cu 间歇@25SiO2-1Al2O3-0.2, 2Ni-1Cu@25SiO2-1Al2O3-0.2, 3Ni-1Cu@25SiO2-1Al2O3-0.2 and 4Ni-1Cu@25SiO2-1Al2O3-0.2.

[0053] Example 10: Preparation of Ni-Cu@12.5SiO2-1Al2O3-0.1 catalyst

[0054] 0.25 g NiO-CuO nanoparticles (3.2761-3.3043 mmol, obtained from Example 1-4) were added to 40 mL H2O and ultrasonically dispersed for 60 min. 1.9320 g (i.e., 9.500 mmol) TPAOH was added and ultrasonically dispersed for 60 min. Then 0.1049 g (i.e., 0.5035 mmol) TEOS was added dropwise to the mixed solution, hydrolyzed at 60°C, and stirred at room temperature for 1 h. A mixed solution of 0.0266 g (i.e. 0.0709 mmol) Al(NO3)3·9H2O, 3.2640 g (i.e. 81.60 mmol) NaOH and 10 g (i.e. 555.56 mmol) H2O was added dropwise to the above mixture, and then added to a hydrothermal kettle, and hydrothermally reacted at 170°C for 36 h to obtain a catalyst precursor, which was centrifuged, washed with deionized water and ethanol until neutral, dried at 80°C for 10 h, calcined at 400°C for 4 h, and reduced with H2 at 500°C for 2 h to obtain four core-shell catalysts 3Ni-1Cu 间歇 @12.5SiO2-1Al2O3-0.2, 2Ni-1Cu@12.5SiO2-1Al2O3-0.2, 3Ni-1Cu@12.5SiO2-1Al2O3-0.2 and 4Ni-1Cu@12.5SiO2-1Al2O3-0.2.

[0055] Example 11: Preparation of Ni-Cu@12.5SiO2-1Al2O3-0.3 catalyst

[0056] 0.25 g NiO-CuO nanoparticles (3.2761-3.3043 mmol, obtained from Example 1-4) was added to 40 mL H2O and ultrasonically dispersed for 60 min. 1.9320 g (i.e. 9.500 mmol) TPAOH was added and ultrasonically dispersed for 60 min. Then 0.3147 g (i.e. 1.5106 mmol) TEOS was added dropwise to the mixed solution, hydrolyzed at 60°C, and stirred at room temperature for 1 h. A mixed solution of 0.0799 g (i.e. 0.2130 mmol) Al(NO3)3·9H2O, 3.2640 g (i.e. 81.60 mmol) NaOH and 10 g (i.e. 555.56 mmol) H2O was added dropwise to the above mixture, and then added to a hydrothermal kettle, and hydrothermally reacted at 170°C for 36 h to obtain a catalyst precursor, which was centrifuged, washed with deionized water and ethanol until neutral, dried at 80°C for 10 h, calcined at 400°C for 4 h, and reduced with H2 at 500°C for 2 h to obtain four core-shell catalysts 3Ni-1Cu 间歇 @12.5SiO2-1Al2O3-0.3, 2Ni-1Cu@12.5SiO2-1Al2O3-0.3, 3Ni-1Cu@12.5SiO2-1Al2O3-0.3 and 4Ni-1Cu@12.5SiO2-1Al2O3-0.3.

[0057] Example 12: Preparation of Ni-Cu@12.5SiO2-1Al2O3-0.4 catalyst

[0058] 0.25 g NiO-CuO nanoparticles (3.2761-3.3043 mmol, obtained from Examples 1-4) were added to 40 mL H2O and ultrasonically dispersed for 60 min. 1.9320 g (i.e., 9.500 mmol) TPAOH was then added and ultrasonically dispersed for 60 min. 0.4196 g (i.e., 2.0141 mmol) TEOS was then added dropwise to the mixed solution, hydrolyzed at 60°C, and stirred at room temperature for 1 h. A mixed solution of 0.1065 g (i.e. 0.2839 mmol) Al(NO3)3·9H2O, 3.2640 g (i.e. 81.60 mmol) NaOH and 10 g (i.e. 555.56 mmol) H2O was added dropwise to the above mixture, and then added to a hydrothermal kettle, and hydrothermally reacted at 170°C for 36 h to obtain a catalyst precursor, which was centrifuged, washed with deionized water and ethanol until neutral, dried at 80°C for 10 h, calcined at 400°C for 4 h, and reduced with H2 at 500°C for 2 h to obtain four core-shell catalysts 3Ni-1Cu 间歇@12.5SiO2-1Al2O3-0.4, 2Ni-1Cu@12.5SiO2-1Al2O3-0.4, 3Ni-1Cu@12.5SiO2-1Al2O3-0.4 and 4Ni-1Cu@12.5SiO2-1Al2O3-0.4.

[0059] Example 13: Preparation of Ni-Cu@12.5SiO2-1Al2O3-0.5 catalyst

[0060] 0.25 g NiO-CuO nanoparticles (3.2761-3.3043 mmol, obtained from Example 1-4) were added to 40 mL H2O and ultrasonically dispersed for 60 min. 1.9320 g (i.e. 9.500 mmol) TPAOH was added and ultrasonically dispersed for 60 min. Then 0.5245 g (i.e. 2.5176 mmol) TEOS was added dropwise to the mixed solution, hydrolyzed at 60°C, and stirred at room temperature for 1 h. A mixed solution of 0.1332 g (i.e. 0.3550 mmol) Al(NO3)3·9H2O, 3.2640 g (i.e. 81.60 mmol) NaOH and 10 g (i.e. 555.56 mmol) H2O was added dropwise to the above mixture, and then added to a hydrothermal kettle, and hydrothermally reacted at 170°C for 36 h to obtain a catalyst precursor, which was centrifuged, washed with deionized water and ethanol until neutral, dried at 80°C for 10 h, calcined at 400°C for 4 h, and reduced with H2 at 500°C for 2 h to obtain four core-shell structure catalysts 3Ni-1Cu 间歇 @12.5SiO2-1Al2O3-0.5, 2Ni-1Cu@12.5SiO2-1Al2O3-0.5, 3Ni-1Cu@12.5SiO2-1Al2O3-0.5 and 4Ni-1Cu@12.5SiO2-1Al2O3-0.5.

[0061] The shell layer of the catalyst obtained above is SiO2 or Al2O3 or a SiO2-Al2O3 mixture;

[0062] The molar amount of the metal nanoparticles is based on the actual content measured by ICP characterization;

[0063] The metal M1 in the metal core is Ni, and the metal M2 is Cu; the molar ratio of the metal M1 to M2 is 2 to 4:1;

[0064] The thickness of the catalyst shell and the size of the pore size are determined by the ratio of the oxide shell (shell-forming reagent) to the metal, and the molar ratio of the metal to the shell-forming reagent is 1:0.1-1.0;

[0065] The catalyst is represented by xM1-yM2@mSiO2-nAl2O3-z, wherein M1 and M2 represent metals, x and y represent the molar ratio of M1 to M2 in the catalyst, m and n represent the molar ratio of SiO2 to Al2O3 in the catalyst, and z represents the molar ratio of mSiO2-nAl2O3 to xM1-yM2 in the catalyst.

[0066] Example 14: Catalytic amination reaction of ethanolamine

[0067] The reaction was carried out in a 15 mL stainless steel reactor, and the catalyst 4Ni-1Cu@SiO2-0.2 (0.20 g) and ethanolamine (2.00 g) obtained in Example 5 were added. Before the reaction, the reactor was purged with N2 five times to replace the residual air. Then, 0.5 MPa NH3 and 1.0 MPa H2 were filled, and the reaction was carried out at a constant temperature (180°C) with a stirring rate of 1500 rpm. After 12 hours of reaction, the liquid product was separated from the catalyst and N-methylpyrrolidone was added as an internal standard for gas chromatography analysis. The conversion rate of ethanolamine was 57%, the selectivity of ethylenediamine was 79%, the selectivity of piperazine was 12%, and the selectivity of triethylenediamine was 8%.

[0068] Example 15: Catalytic amination of ethanolamine

[0069] The reaction was carried out in a 15 mL stainless steel reactor, and the catalyst 3Ni-1Cu@SiO2-0.2 (0.20 g) and ethanolamine (2.00 g) obtained in Example 5 were added. Before the reaction, the reactor was purged with N2 five times to replace the residual air. Then, 0.5 MPa NH3 and 1.0 MPa H2 were filled, and the reaction was carried out at a constant temperature (180°C) with a stirring rate of 1500 rpm. After 12 hours of reaction, the liquid product was separated from the catalyst and N-methylpyrrolidone was added as an internal standard for gas chromatography analysis. The conversion rate of ethanolamine was 54%, the selectivity of ethylenediamine was 86%, the selectivity of piperazine was 8%, and the selectivity of triethylenediamine was 5%.

[0070] Example 16: Catalytic amination reaction of ethanolamine

[0071] The reaction was carried out in a 15 mL stainless steel reactor, and the catalyst 2Ni-1Cu@SiO2-0.2 (0.20 g) and ethanolamine (2.00 g) obtained in Example 5 were added. Before the reaction, the reactor was purged with N2 five times to replace the residual air. Then, 0.5 MPa NH3 and 1.0 MPa H2 were filled, and the reaction was carried out at a constant temperature (180°C) with a stirring rate of 1500 rpm. After 12 hours of reaction, the liquid product was separated from the catalyst and N-methylpyrrolidone was added as an internal standard for gas chromatography analysis. The conversion rate of ethanolamine was 50%, the selectivity of ethylenediamine was 87%, the selectivity of piperazine was 8%, and the selectivity of triethylenediamine was 4%.

[0072] Example 17: Catalytic amination of ethanolamine

[0073] The reaction was carried out in a 15 mL stainless steel reactor, and the catalyst 3Ni-1Cu@Al2O3-0.2 (0.20 g) and ethanolamine (2.00 g) obtained in Example 6 were added. Before the reaction, the reactor was purged with N2 five times to replace the residual air. Then, 0.5 MPa NH3 and 1.0 MPa H2 were filled, and the reaction was carried out at a constant temperature (180°C) with a stirring rate of 1500 rpm. After 12 hours of reaction, the liquid product was separated from the catalyst and N-methylpyrrolidone was added as an internal standard for gas chromatography analysis. The conversion rate of ethanolamine was 69%, the selectivity of ethylenediamine was 73%, the selectivity of piperazine was 9%, and the selectivity of triethylenediamine was 4%.

[0074] Example 18: Catalytic amination reaction of ethanolamine

[0075] The reaction was carried out in a 15 mL stainless steel reactor, and the catalyst 3Ni-1Cu@5SiO2-1Al2O3-0.2 (0.20 g) and ethanolamine (2.00 g) obtained in Example 7 were added. Before the reaction, the reactor was purged with N2 five times to replace the residual air. Then, 0.5 MPa NH3 and 1.0 MPa H2 were charged, and the reaction was carried out at a constant temperature (180°C) with a stirring rate of 1500 rpm. After 12 hours of reaction, the liquid product was separated from the catalyst and N-methylpyrrolidone was added as an internal standard for gas chromatography analysis. The conversion rate of ethanolamine was 64%, the selectivity of ethylenediamine was 79%, the selectivity of piperazine was 11%, and the selectivity of triethylenediamine was 4%.

[0076] Example 19: Catalytic amination of ethanolamine

[0077] The reaction was carried out in a 15 mL stainless steel reactor, and the catalyst 3Ni-1Cu@12.5SiO2-1Al2O3-0.2 (0.20 g) and ethanolamine (2.00 g) obtained in Example 8 were added. Before the reaction, the reactor was purged with N2 five times to replace the residual air. Then, 0.5 MPa NH3 and 1.0 MPa H2 were charged, and the reaction was carried out at a constant temperature (180°C) with a stirring rate of 1500 rpm. After 12 h of reaction, the liquid product was separated from the catalyst and N-methylpyrrolidone was added as an internal standard for gas chromatography analysis. The conversion rate of ethanolamine was 61%, the selectivity of ethylenediamine was 84%, the selectivity of piperazine was 12%, and the selectivity of triethylenediamine was 3%.

[0078] Example 20: Catalytic amination of ethanolamine

[0079] The catalyst 3Ni-1Cu obtained in Example 8 was added in a 15 mL stainless steel reactor. 间歇 @12.5SiO2-1Al2O3-0.2 (0.20g) and ethanolamine (2.00g). Before the reaction, the reactor was purged with N2 five times to replace the residual air. Then, 0.5MPa NH3 and 1.0MPa H2 were filled, and the reaction was carried out at a constant temperature (180°C) with a stirring rate of 1500rpm. After 12h of reaction, the liquid product was separated from the catalyst and N-methylpyrrolidone was added as an internal standard for gas chromatography analysis. The conversion rate of ethanolamine was 47%, the selectivity of ethylenediamine was 62%, the selectivity of piperazine was 17%, and the selectivity of triethylenediamine was 10%.

[0080] Example 21: Catalytic amination of ethanolamine

[0081] The reaction was carried out in a 15 mL stainless steel reactor, and the catalyst 3Ni-1Cu@25SiO2-1Al2O3-0.2 (0.20 g) and ethanolamine (2.00 g) obtained in Example 9 were added. Before the reaction, the reactor was purged with N2 five times to replace the residual air. Then, 0.5 MPa NH3 and 1.0 MPa H2 were charged, and the reaction was carried out at a constant temperature (180°C) with a stirring rate of 1500 rpm. After 12 hours of reaction, the liquid product was separated from the catalyst and N-methylpyrrolidone was added as an internal standard for gas chromatography analysis. The conversion rate of ethanolamine was 57%, the selectivity of ethylenediamine was 85%, the selectivity of piperazine was 12%, and the selectivity of triethylenediamine was 3%.

[0082] Example 22: Catalytic amination reaction of ethanolamine

[0083] The reaction was carried out in a 15 mL stainless steel reactor, and the catalyst 3Ni-1Cu@12.5SiO2-1Al2O3-0.1 (0.20 g) and ethanolamine (2.00 g) obtained in Example 10 were added. Before the reaction, the reactor was purged with N2 five times to replace the residual air. Then, 0.5 MPa NH3 and 1.0 MPa H2 were charged, and the reaction was carried out at a constant temperature (180°C) with a stirring rate of 1500 rpm. After 12 hours of reaction, the liquid product was separated from the catalyst and N-methylpyrrolidone was added as an internal standard for gas chromatography analysis. The conversion rate of ethanolamine was 58%, the selectivity of ethylenediamine was 73%, the selectivity of piperazine was 11%, and the selectivity of triethylenediamine was 4%.

[0084] Example 23: Catalytic amination of ethanolamine

[0085] The reaction was carried out in a 15 mL stainless steel reactor, and the catalyst 3Ni-1Cu@12.5SiO2-1Al2O3-0.3 (0.20 g) and ethanolamine (2.00 g) obtained in Example 11 were added. Before the reaction, the reactor was purged with N2 five times to replace the residual air. Then, 0.5 MPa NH3 and 1.0 MPa H2 were charged, and the reaction was carried out at a constant temperature (180° C.) with a stirring rate of 1500 rpm. After 12 h of reaction, the liquid product was separated from the catalyst and N-methylpyrrolidone was added as an internal standard for gas chromatography analysis. The conversion rate of ethanolamine was 62%, the selectivity of ethylenediamine was 80%, the selectivity of piperazine was 13%, and the selectivity of triethylenediamine was 6%.

[0086] Example 24: Catalytic amination reaction of ethanolamine

[0087] The reaction was carried out in a 15 mL stainless steel reactor, and the catalyst 3Ni-1Cu@12.5SiO2-1Al2O3-0.4 (0.20 g) and ethanolamine (2.00 g) obtained in Example 12 were added. Before the reaction, the reactor was purged with N2 five times to replace the residual air. Then, 0.5 MPa NH3 and 1.0 MPa H2 were charged, and the reaction was carried out at a constant temperature (180° C.) with a stirring rate of 1500 rpm. After 12 h of reaction, the liquid product was separated from the catalyst and N-methylpyrrolidone was added as an internal standard for gas chromatography analysis. The conversion rate of ethanolamine was 64%, the selectivity of ethylenediamine was 73%, the selectivity of piperazine was 15%, and the selectivity of triethylenediamine was 11%.

[0088] Example 25: Catalytic amination reaction of ethanolamine

[0089] The reaction was carried out in a 15 mL stainless steel reactor, and the catalyst 3Ni-1Cu@12.5SiO2-1Al2O3-0.5 (0.20 g) and ethanolamine (2.00 g) obtained in Example 13 were added. Before the reaction, the reactor was purged with N2 five times to replace the residual air. Then, 0.5 MPa NH3 and 1.0 MPa H2 were charged, and the reaction was carried out at a constant temperature (180° C.) with a stirring rate of 1500 rpm. After 12 h of reaction, the liquid product was separated from the catalyst and N-methylpyrrolidone was added as an internal standard for gas chromatography analysis. The conversion rate of ethanolamine was 67%, the selectivity of ethylenediamine was 56%, the selectivity of piperazine was 20%, and the selectivity of triethylenediamine was 16%.

[0090] Example 26: Catalytic amination reaction of ethanolamine

[0091] The reaction was carried out in a 15 mL stainless steel reactor, and the catalyst 3Ni-1Cu@12.5SiO2-1Al2O3-0.2 (0.20 g) and ethanolamine (2.00 g) obtained in Example 8 were added. Before the reaction, the reactor was purged with N2 five times to replace the residual air. Then, 0.5 MPa NH3 and 1.0 MPa H2 were charged, and the reaction was carried out at a constant temperature (180°C) with a stirring rate of 1500 rpm. After 14 hours of reaction, the liquid product was separated from the catalyst and N-methylpyrrolidone was added as an internal standard for gas chromatography analysis. The conversion rate of ethanolamine was 64%, the selectivity of ethylenediamine was 83%, the selectivity of piperazine was 12%, and the selectivity of triethylenediamine was 4%.

[0092] Example 27: Catalytic amination of ethanolamine

[0093] The reaction was carried out in a 15 mL stainless steel reactor, and the catalyst 3Ni-1Cu@12.5SiO2-1Al2O3-0.2 (0.20 g) and ethanolamine (2.00 g) obtained in Example 8 were added. Before the reaction, the reactor was purged with N2 five times to replace the residual air. Then, 0.5 MPa NH3 and 1.0 MPa H2 were charged, and the reaction was carried out at a constant temperature (190° C.) with a stirring rate of 1500 rpm. After 14 h of reaction, the liquid product was separated from the catalyst and N-methylpyrrolidone was added as an internal standard for gas chromatography analysis. The conversion rate of ethanolamine was 70%, the selectivity of ethylenediamine was 81%, the selectivity of piperazine was 13%, and the selectivity of triethylenediamine was 5%.

[0094] Example 28: Catalytic amination reaction of ethanolamine

[0095] The reaction was carried out in a 15 mL stainless steel reactor, and the catalyst 3Ni-1Cu@12.5SiO2-1Al2O3-0.2 (0.40 g) and ethanolamine (2.00 g) obtained in Example 8 were added. Before the reaction, the reactor was purged with N2 five times to replace the residual air. Then, 0.5 MPa NH3 and 1.0 MPa H2 were charged, and the reaction was carried out at a constant temperature (190° C.) with a stirring rate of 1500 rpm. After 14 h of reaction, the liquid product was separated from the catalyst and N-methylpyrrolidone was added as an internal standard for gas chromatography analysis. The conversion rate of ethanolamine was 81%, the selectivity of ethylenediamine was 83%, the selectivity of piperazine was 11%, and the selectivity of triethylenediamine was 5%.

[0096] Examples 14-16 use catalysts with SiO2 shells and different Ni:Cu ratios. When the molar ratio of metal Ni to Cu is 3:1, the conversion rate of ethanolamine is 54%, and the selectivity of ethylenediamine reaches a maximum value of 86%. The reason is that a high proportion of Cu is more conducive to the dehydrogenation of ethanolamine and promotes the conversion of ethanolamine, while a lower proportion of Cu promotes the dispersion of Ni, is more conducive to the formation of ethylenediamine, and improves the selectivity of ethylenediamine.

[0097] In the reduction amination reaction, the acidity and alkalinity of the catalyst have a great influence on the conversion rate of the substrate and the selectivity of the product. The acidity and alkalinity of the catalyst prepared in this study are mainly affected by the composition and thickness of the shell layer. Therefore, Examples 17-25 systematically investigate the effects of different shell layer compositions, shell layer thicknesses, etc. on the reaction. Catalyst 3Ni-1Cu@12.5SiO2-1Al2O3-0.2 has the best catalytic performance, with a conversion rate of ethanolamine of 61%, a selectivity of ethylenediamine of 84%, and a corresponding EDA yield of the highest, reaching 51%. The reason is that the catalyst has a suitable acid strength, an appropriate amount of acid sites and appropriate alkaline sites, which helps to promote the cleavage of the OH bond, the cleavage of the CH bond, the adsorption of MEA and intermediates in the condensation step of ketones and ammonia, and the desorption of EDA, thereby promoting the MEA-catalyzed amination reaction.

[0098] Example 20 is a catalyst prepared by metal nanoparticles prepared by an intermittent method, and its catalytic performance is significantly lower than the catalytic performance of metal nanoparticles prepared continuously by a membrane dispersion microreactor.

[0099] Examples 26-28 give some process condition optimization data. When the reaction conditions are: reaction temperature 190°C, reaction time 14h, MEA to catalyst mass ratio 5:1, ammonia pressure 0.5MPa, and hydrogen pressure 1MPa, the conversion rate of MEA reaches 81%, the selectivity of EDA is 83%, and the yield of EDA is 67%.

[0100] Matters not covered by the present invention are known technologies.

Claims

1. A method for preparing ethylenediamine, characterized in that: The method comprises the following steps: Ethanolamine is placed in a reactor loaded with a catalyst, and ammonia and hydrogen are introduced into the reactor in sequence, and the reaction is carried out at 170°C to 210°C for 10-18 hours to generate ethylenediamine by catalytic amination reaction; Wherein, the mass ratio is ethanolamine: catalyst = 3-20:1; ammonia pressure: 0.3-0.7MPa; hydrogen pressure: 1-3MPa; The catalyst is a core-shell structure, which comprises a silicon dioxide-aluminum oxide composite shell and a metal core; The metal cores are metal M1 and metal M2, which are Ni and Cu respectively; the total molar amount of Ni and Cu accounts for 67-91% of the whole catalyst, and the molar ratio of metal Ni to Cu is 2-4:

1.

2. The method for preparing ethylenediamine according to claim 1, characterized in that: The diameter of the metal core is 10-25 nm, and the thickness of the shell is 5-20 nm.

3. A method for preparing a core-shell catalyst, characterized in that: The steps include: (1) Continuous preparation of metal core: Nitrate solution A and Na2CO3 solution B were injected at a rate of 5.00-15.00 mL / min using a high-pressure booster pump, and mixed at a constant temperature of 50-70°C in a membrane disperser; The turbid liquid is collected, centrifuged, washed to neutrality, and dried at 80-100°C for 10-24h; finally, the cooled catalyst precursor is ground into powder, heated to 400-600°C and calcined for 2-4h at a heating rate of 5-10°C / min to obtain metal oxide nanoparticles; Among them, the concentration of nitrate solution is 0.10-0.30M, and the concentration of Na2CO3 solution is 0.20-0.60M; The nitrate is copper nitrate and nickel nitrate; the molar ratio is Ni:Cu=2-4:1; (2) Covering the metal core with a shell; Add metal oxide nanoparticles to H2O to obtain a metal oxide suspension; ultrasonically disperse for 30 to 60 minutes, continue to add tetrapropylammonium hydroxide and ultrasonically disperse for 30 to 60 minutes, then drop ethyl orthosilicate therein, and hydrolyze at 40 to 60°C; finally drop a mixed solution of Al(NO3)3·9H2O, NaOH and H2O into the above mixture, add it to a hydrothermal kettle after stirring, and hydrothermally react at 160 to 180°C for 24 to 48 hours to obtain a catalyst precursor, and then calcine at 400 to 600°C for 2 to 4 hours, and reduce it with H2 at 400 to 600°C for 2 to 3 hours to obtain a final catalyst; Wherein, the concentration of the metal oxide suspension is 0.2-1wt%; The molar ratio is TEOS:Al(NO3)3·9H2O:TPAOH:NaOH:H2O in the mixed solution=2-20:1:20-150:200-1500:1500-10000; The molar ratio is metal oxide: (ethyl orthosilicate + Al(NO3)3·9H2O) = 0.1 to 1.

0.

4. The method for preparing a core-shell catalyst as claimed in claim 3, characterized in that: The metal oxides are specifically CuO, NiO and NiO-CuO.

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