Alumina supported molecular sieve membrane catalyst and method of making and microchannel reactor amination reaction process

Abstract

The application provides an alumina-supported molecular sieve membrane catalyst, a preparation method and an ammination reaction method in a microchannel reactor. Liquid ammonia and an olefin are subjected to ammination reaction in the microchannel reactor loaded with the molecular sieve membrane catalyst, the mass transfer and heat transfer performance can be enhanced, the reaction temperature is kept constant, the temperature overshoot phenomenon is avoided, and the reaction efficiency can be significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of petrochemicals, specifically relating to an alumina-supported molecular sieve membrane catalyst, its preparation method, and an amination reaction method using a microchannel reactor. Background Technology

[0002] Amine products can be considered as compounds obtained by replacing hydrogen in ammonia molecules with different types or numbers of alkyl, aromatic, or other hydrocarbon groups. These include aliphatic amines, aromatic amines, quaternary ammonium salts, ether amines, and amides. Among them, aliphatic amines have a wide range of applications, such as in the textile industry, dyes, flotation, metallurgy, wastewater treatment, and daily necessities.

[0003] Currently, the commonly used synthetic methods for fatty amine compounds include fatty acid amination and hydrogenation, fatty alcohol amination, and direct olefin amination. Among them, direct olefin amination has advantages such as high atom utilization and less waste, but it generally has a high reaction energy barrier and correspondingly harsh synthesis conditions.

[0004] The development of acidic catalysts in the early 1980s made the practical application of this type of synthesis possible. In 1994, the direct amination of isobutylene with ammonia to synthesize tert-butylamine was industrialized. The amination processes of several other olefins besides isobutylene, such as ethylene, propylene, and styrene, have also been studied in the laboratory. However, due to low conversion rates and easy catalyst deactivation, they cannot be used for long-term operation and have not been industrialized.

[0005] In the 1970s, international research began on the preparation of corresponding amine products by olefin amination, but due to the poor selectivity of the amination reaction and the short catalyst life, it failed to be industrialized.

[0006] US4375002 discloses a method for the direct amination of isobutylene using amorphous aluminum silicate or aluminum silicate molecular sieve as a catalyst. However, due to the excessively strong acid centers in aluminum silicate materials and aluminum silicate molecular sieves, they easily promote the polymerization of olefins at high temperatures, leading to carbon accumulation on the catalyst surface and rapid deactivation of the catalyst.

[0007] US4929759 discloses a method for isobutylene amination using boron-substituted BETA molecular sieves as catalysts, which can achieve a certain conversion rate and selectivity greater than 98%. However, the reaction conditions are harsh, with a reaction pressure of 30 MPa and a reaction temperature of over 300°C. After 28 days of operation, the catalyst carbon deposition reached 11%.

[0008] CN104418754A discloses the preparation of tert-butylamine using a tubular fixed bed reactor, but this process has a low space velocity, low production efficiency, is not conducive to reaction diffusion, and it is difficult to replace the catalyst in the tubular reactor, resulting in large investment and making it difficult to apply in production.

[0009] Existing technologies indicate that olefin feedstocks in olefin amination reactions tend to polymerize within the catalyst channels for extended periods, forming high-molecular-weight carbides. These polymers are prone to carbonization, causing catalyst channel blockage and reducing catalyst lifespan, necessitating frequent catalyst replacement. Furthermore, current technologies often employ adiabatic bed reactors for olefin amination processes. Due to the low conversion rate of these reactions, this process route results in extremely large reactor sizes, with significant amounts of hydrocarbons and liquid ammonia remaining within the reactor, posing substantial safety risks. Additionally, the heat generated during industrial operation of adiabatic bed reactors cannot be removed, and the heat released during the reaction often exacerbates the temperature rise, intensifying olefin polymerization, producing carbon deposits, and reducing catalyst lifespan. Moreover, these reactions are equilibrium reactions; thermodynamically, high temperatures are unfavorable for the forward reaction. Therefore, if the generated heat of reaction cannot be effectively removed, it will promote the reverse reaction, leading to a decrease in plant capacity.

[0010] Therefore, if a method can be developed to reduce the reaction scale, enhance mass transfer, reduce carbon buildup, lower reaction pressure, and improve production efficiency, it can significantly reduce equipment investment, reduce the stock of hazardous raw materials such as liquid ammonia and olefins in the equipment, reduce the risk of major hazard sources in the equipment, and at the same time improve reaction efficiency, save equipment investment, and reduce product consumption per unit. Summary of the Invention

[0011] To address the shortcomings of existing technologies, this invention proposes an alumina-supported molecular sieve membrane catalyst and its preparation method. Compared with traditional molecular sieves or metal catalysts, this catalyst has more unobstructed pores, which is more conducive to molecular diffusion. The diffusion distance of raw materials within the membrane is shorter, resulting in lower mass transfer resistance and facilitating internal diffusion in the reaction. After more than 1000 hours of operation, the catalyst carbon deposition is less than 5%.

[0012] The present invention also provides a method for carrying out an amination reaction by using the above-mentioned alumina-supported molecular sieve membrane as a catalyst packed in a microchannel reactor.

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] In a first aspect, the present invention provides a method for preparing an alumina-supported molecular sieve membrane catalyst, comprising the following steps:

[0015] 1) Mix alumina powder with water, stir evenly, compress into tablets, dry, calcine, polish smooth, then wash with solvent, dry, and obtain a carrier;

[0016] 2) Using silicon source, aluminum source, template agent tetrapropylammonium hydroxide (TPAOH), mineralizer and water as raw materials, a precursor synthesis solution is prepared and transferred to the carrier in step 1) in a hydrothermal reactor for crystallization. After crystallization, the solution is filtered, washed with water until neutral, dried and calcined to obtain the molecular sieve membrane catalyst precursor.

[0017] 3) The molecular sieve membrane catalyst precursor from step 2) is subjected to ultrasonic surface treatment with an ion exchange solution, then filtered, washed with water until neutral, dried, and calcined to obtain an alumina-supported molecular sieve membrane catalyst.

[0018] In this invention, the alumina mentioned in step 1) is one or more of α-Al2O3, θ-Al2O3, η-Al2O3, and γ-Al2O3;

[0019] Preferably, the alumina powder has a bulk density of 0.2-1 g / ml, for example, 0.2, 0.4, 0.6, 0.8, or 1 g / ml, and a specific surface area of ​​20-300 m². 2 / g, for example 20, 50, 100, 150, 200, 250, 300mg 2 / g, pore volume is 0.1-0.5ml / g, for example 0.1, 0.2, 0.3, 0.4, 0.5ml / g; particle size is 5-100μm, for example 5, 10, 30, 50, 70, 90, 100μm.

[0020] In this invention, the amount of water used in step 1) is 5-15 wt% of the mass of the alumina powder, for example 5, 7, 9, 11, 13, or 15 wt%, preferably 6-8 wt%.

[0021] In this invention, after tableting in step 1), the drying process is carried out at a temperature of 30-60℃, for example, 30, 40, 50, or 60℃, for a time of 24-48 hours, for example, 24, 30, 35, 40, 45, or 48 hours; the calcination process is carried out at a temperature of 800-1400℃, for example, 800, 1000, 1200, or 1400℃, for a time of 12-24 hours, for example, 12, 14, 16, 18, 10, 22, or 24 hours.

[0022] Preferably, the tablet has a size of 1-3 mm, for example, 1, 2, or 3 mm.

[0023] In this invention, the solvent washing in step 1) uses a solvent volume to alumina powder mass ratio of 10-100:1, for example 10:1, 30:1, 50:1, 70:1, 90:1, 100:1;

[0024] Preferably, the solvent is selected from at least one of acetone, ethanol, and tetrahydrofuran.

[0025] In this invention, the silicon source in step 2) is at least one of silica, silica sol, tetraethyl orthosilicate, and silicon dioxide;

[0026] The aluminum source is at least one of aluminum nitrate, sodium aluminate, and aluminum sulfate;

[0027] The mineralizing agent is at least one of sodium hydroxide and potassium hydroxide.

[0028] In this invention, the mass ratio of silicon source to carrier in step 2) is 9-200:1, for example 9:1, 30:1, 60:1, 90:1, 120:1, 150:1, 200:1, preferably 10-30:1;

[0029] The molar ratio of the template agent tetrapropylammonium hydroxide to the silicon source is 0.1-1.5:1, for example 0.1:1, 0.3:1, 0.5:1, 0.7:1, 0.9:1, 1.1:1, 1.3:1.5:1, preferably 0.1-0.5:1;

[0030] The molar ratio of the silicon source to the aluminum source is 520-50:1, for example 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, preferably 30-50:1.

[0031] In this invention, the template agent tetrapropylammonium hydroxide and the aluminum source mentioned in step 2) are mixed with water to prepare an aqueous solution;

[0032] Preferably, the template agent tetrapropylammonium hydroxide is prepared as an aqueous solution with a concentration of 10-30 wt%, for example, 10, 15, 20, 25, or 30 wt%.

[0033] Preferably, the aluminum source is prepared as an aqueous solution with a concentration of 10-40 wt%, for example, 10, 20, 30, or 40 wt%.

[0034] In this invention, the amount of mineralizer added in step 2) is to adjust the pH of the solution to 12-14, for example, 12, 13, or 14;

[0035] Preferably, the mineralizing agent is prepared as an aqueous solution by mixing it with water.

[0036] In this invention, the specific preparation process of the precursor synthesis solution in step 2) is as follows: First, the aqueous solution of the template agent tetrapropylammonium hydroxide is mixed with the silicon source and stirred vigorously for 1-5 hours, for example, 1, 2, 3, 4, 5 hours. Then, a mineralizing agent is added to adjust the pH of the solution to 12-14. Then, an aqueous solution of the aluminum source is added and the solution is stirred vigorously at 20-80°C, for example, 20, 40, 60, 80°C, for example, 12, 20, 30, 40, 48 hours, to obtain the precursor synthesis solution.

[0037] Preferably, the vigorous stirring speed is 500-1000 rpm, for example, 500, 700, 900, or 1000 rpm.

[0038] In this invention, the mass ratio of the precursor synthesis liquid to the carrier in step 2) is 50-750:1, for example 50:1, 100:1, 200:1, 300:1, 400:1, 500:1, 600:1, 700:1, 750:1.

[0039] In this invention, the crystallization in step 2) is performed under the following conditions: the hydrothermal reactor is heated to 150-220°C at a rate of 0.5-2°C / min, for example, 150, 170, 190, 210, or 220°C, and held at that temperature for 100-300 hours, for example, 100, 150, 200, 250, or 300 hours, and then cooled to 30-60°C at a rate of 0.5-1°C / min, for example, 0.5, 0.6, 0.7, 0.8, 0.9, or 1°C / min, for example, 30, 40, 50, or 60°C.

[0040] Preferably, the hydrothermal reactor is a hydrothermal reactor with a polytetrafluoroethylene liner.

[0041] In this invention, the roasting in step 2) is carried out at a temperature of 450-650℃, for example 450, 500, 550, 600, 650℃, for a time of 6-18h, for example 6, 8, 10, 12, 14, 16, 18h.

[0042] In this invention, the ratio of the volume of the ion exchange solution to the mass of the molecular sieve membrane catalyst precursor in step 3) is 20-30 ml / g, for example, 20, 22, 24, 26, 28, or 30 ml / g.

[0043] In this invention, the ion exchange solution in step 3) is selected from at least one aqueous solution of ammonium salt, alkaline earth metal, transition metal nitrate, or acetate.

[0044] Preferably, the concentration of the ion exchange solution is 20-50 wt%, for example 20, 30, 40, or 50 wt%, preferably 20-30 wt%.

[0045] In this invention, the ultrasonic surface treatment in step 3) is performed under the following conditions: ultrasonic frequency 20-50KHz, for example 20, 30, 40, 50KHz; temperature 20-80℃, for example 20, 40, 60, 80℃; and time 1-5h, for example 1, 2, 3, 4, 5h.

[0046] The catalyst preparation method of the present invention also includes operations such as tableting, filtration, washing, and drying, which are all conventional technical means in the field. The present invention does not make any special limitations. Preferably, step 3) adopts the same filtration, washing, drying, and calcination operations as step 2).

[0047] Secondly, the present invention provides an alumina-supported molecular sieve membrane catalyst prepared by the above method;

[0048] The catalyst has a particle size of 1-3 mm, for example, 1, 2, or 3 mm.

[0049] Thirdly, the present invention also provides an application of the above-mentioned catalyst in an amination process.

[0050] This invention provides a microchannel reactor amination reaction method, the steps of which include:

[0051] The above-mentioned alumina-supported molecular sieve membrane catalyst was loaded into a microchannel reactor, and liquid ammonia and olefins reacted in the microchannel reactor to obtain the amination product.

[0052] In this process, liquid ammonia and olefins are pumped into a static mixer via a diaphragm pump, then heated to the reaction temperature by a preheater, and finally fed into a microchannel reactor for reaction. The reaction products are then separated to obtain the final product.

[0053] The olefin is one or more of isobutylene, ethylene, styrene, and propylene.

[0054] The feed molar ratio of the olefin to ammonia is 1:1-6, for example 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, preferably 1:1.2-1.8.

[0055] The reaction is carried out at a pressure of 0.1-20 MPaG, for example 0.1, 1, 5, 10, 15, 20 MPaG, preferably 1-5 MPaG; and at a temperature of 200-400℃, for example 200, 250, 300, 350, 400℃.

[0056] Preferably, the space velocity (based on olefin liquid-phase feed) for the reaction is 0.5-50 h⁻¹. -1 For example, 0.5, 1, 10, 20, 30, 40, 50h -1 Preferred 2-12h -1 .

[0057] The microchannel structure of the microchannel reactor is a direct-flow tubular structure with a diameter of 0.5-8 mm, such as 0.5, 1, 3, 5, 7, 8 mm, preferably 1-3 mm.

[0058] In some preferred embodiments of the present invention, the preparation method is as follows: before the reaction begins, the catalyst is heat-treated in an inert gas atmosphere for 8-24 hours, for example, 8, 12, 16, 20, or 24 hours. Since the alumina-supported molecular sieve membrane type catalyst prepared by the present invention has a large specific surface area and high adsorption performance, its active sites are easily occupied by impurities when left for a long time. Therefore, it is necessary to activate the catalyst by pretreatment with hot inert gas. After the catalyst is activated, the reactor temperature is adjusted and the feed is fed in the corresponding proportion. The system pressure is controlled by the reactor outlet regulating valve, and the amination product is obtained after separation.

[0059] Preferably, the inert gas used in the heat treatment is one or more of nitrogen, helium, and argon.

[0060] Preferably, the heat treatment process conditions are as follows: temperature is 300-500℃, for example 300, 350, 400, 450, 500℃, preferably 350-450℃; pressure is 0.1-5MPaG, for example 0.1, 1, 2, 3, 4, 5MPaG, preferably 0.1-0.5MPaG.

[0061] Compared with the prior art, the positive effects of the present invention are:

[0062] The amination method using a continuous microchannel reactor described in this invention achieves the same conversion rate with a reaction space velocity that is more than 5 times higher than that of traditional processes, significantly improving reaction efficiency. Simultaneously, this process enhances mass and heat transfer performance, maintains a constant reaction temperature, and avoids temperature runaway. Compared to adiabatic bed reactors, this method maintains a constant temperature and reduces the conversion rate drop caused by thermodynamic limitations. Furthermore, the reactor has a small material storage capacity, minimizing the amount of hazardous chemicals in the device and improving the safety of the reaction process.

[0063] Alumina-supported molecular sieve membranes are used as catalysts packed in microchannel reactors. Compared with traditional molecular sieves or metal catalysts, the pores are more open, which is more conducive to molecular diffusion. The diffusion distance of raw materials in the membrane is short, the mass transfer resistance is small, which is conducive to internal diffusion in the reaction and improves the reaction selectivity. After more than 1000 hours of operation, the carbon deposition on the catalyst is less than 5%. Detailed Implementation

[0064] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0065] The main raw material sources in the various embodiments and comparative examples of this invention are shown in Table 1 below. Unless otherwise specified, all other raw materials were purchased from commercially available finished products.

[0066] α-Al2O3: Zibo Yishengjia Aluminum Co., Ltd.;

[0067] 30wt% silica sol: Shandong Baite New Materials Co., Ltd.

[0068] The performance test parameters and corresponding test methods used in the various embodiments and comparative examples of this invention are as follows:

[0069] In the embodiments and comparative examples of this invention, gas chromatography was performed using an Agilent GC 7890A, with an online TCD detector used. The chromatographic column was a CP-VOLAMINE, the column temperature was 250℃, and the detector temperature was 300℃.

[0070] Example 1

[0071] The steps for preparing alumina-supported molecular sieve membrane catalysts are as follows:

[0072] 1) Take 10g of α-Al₂O₃ (its loose bulk density is 0.6g / ml, and its specific surface area is 50m²). 2 Alumina flakes were prepared by mixing alumina flakes with 0.6 g of deionized water (pore volume 0.33 ml / g, particle size 35 μm), filling the mixture into a mold, and pressing it into tablets (1 mm) using a tablet press. The tablets were dried at 30°C for 48 h, then calcined at 1300°C for 12 h to obtain the alumina flakes. The pressed alumina flakes were then polished smooth with sandpaper, cleaned with 200 g of acetone solvent, and dried at 80°C for 24 h to obtain the final carrier.

[0073] 2) Take 152g of 20wt% tetrapropylammonium hydroxide aqueous solution (0.15mol) and mix with 300g of 30wt% silica sol (1.5mol). Stir vigorously at 800rpm for 2h. Then add 10wt% sodium hydroxide aqueous solution to adjust the pH of the mixture to about 13. Then add 75g of 10wt% aluminum nitrate aqueous solution (0.03mol). Stir and mix evenly. Finally, age the mixture at 50℃ with vigorous stirring at 800rpm for 24h to obtain about 530g of precursor synthesis solution and place it in a polytetrafluoroethylene-lined hydrothermal reactor. The 10g support from step 1) was then transferred to the hydrothermal reactor for crystallization. The hydrothermal reactor was heated to 160℃ at a rate of 2℃ / min and held at that temperature for 120h. Then, it was cooled to 50℃ at a rate of 0.5℃ / min. After crystallization, the solid was filtered and washed with deionized water until neutral. It was dried at 80℃ for 10h and then calcined at 550℃ for 16h to obtain the molecular sieve membrane catalyst precursor.

[0074] 3) The 40g molecular sieve membrane catalyst precursor obtained according to step 2) was ultrasonically surface treated with 800ml of 20wt% ammonium nitrate aqueous solution at an ultrasonic frequency of 40KHz and a temperature of 60℃ for 2h. Then, it was filtered, washed, dried and calcined under the same conditions as in step 2) to obtain the alumina supported molecular sieve membrane catalyst.

[0075] Example 2

[0076] The steps for preparing alumina-supported molecular sieve membrane catalysts are as follows:

[0077] 1) Take 10g of θ-Al2O3 (its loose bulk density is 0.7g / ml, and its specific surface area is 100m²). 2 Alumina (with a pore volume of 0.32 ml / g and a particle size of 32 μm) was mixed with 0.7 g of deionized water, placed in a mold, and compressed into tablets (1 mm) using a tablet press. The tablets were dried at 60 °C for 24 h, then calcined at 1100 °C for 16 h to obtain an alumina sheet-like carrier. The compressed alumina carrier was then polished smooth with sandpaper, cleaned with 500 g of acetone solvent, and dried at 80 °C for 24 h for later use.

[0078] 2) Take 34g of 20wt% tetrapropylammonium hydroxide aqueous solution (0.03mol) and mix it with 100g of 10wt% silica (0.17mol) hydrosol. Stir vigorously at 800rpm for 2h. Then add 10wt% sodium hydroxide aqueous solution to adjust the pH of the mixture to about 13. Then add 0.85g of 40wt% sodium aluminate (0.004mol) aqueous solution and stir to mix evenly. Finally, age the mixture at 50℃ with vigorous stirring at 800rpm for 24h to obtain about 135g of precursor synthesis solution and place it in a polytetrafluoroethylene-lined hydrothermal reactor. The 1g support from step 1) was then transferred to the hydrothermal reactor for crystallization. The reactor was heated to 200℃ at a rate of 1℃ / min and held at that temperature for 200h. The temperature was then lowered to 50℃ at a rate of 0.5℃ / min. After crystallization, the solid was filtered and washed with deionized water until neutral. It was then dried at 80℃ for 10h and calcined at 450℃ for 14h to obtain the molecular sieve membrane catalyst precursor.

[0079] 3) The 40g molecular sieve membrane catalyst precursor obtained according to step 2) was ultrasonically surface treated with 1200ml of 20wt% ammonium nitrate aqueous solution at an ultrasonic frequency of 40KHz and a temperature of 60℃ for 2h. Then, it was filtered, washed, dried and calcined under the same conditions as in step 2) to obtain the alumina supported molecular sieve membrane catalyst.

[0080] Example 3

[0081] The steps for preparing alumina-supported molecular sieve membrane catalysts are as follows:

[0082] 1) Take 10g of γ-Al2O3 (its loose bulk density is 0.6g / ml, and its specific surface area is 80m²). 2Alumina (with a particle size of 45 μm and a pore volume of 0.33 ml / g) was mixed with 0.8 g of deionized water and placed into a mold for tableting (1 mm). The tablets were dried at 40 °C for 30 h and then calcined at 1100 °C for 18 h to obtain alumina sheet-like carriers. The tableted alumina carriers were then polished smooth with sandpaper, cleaned with 1000 g of acetone solvent, and dried at 80 °C for 24 h for later use.

[0083] 2) Take 490g of 20wt% tetrapropylammonium hydroxide aqueous solution (0.48mol) and mix with 200g of tetraethyl orthosilicate (0.96mol). Stir vigorously at 800rpm for 2h. Then add 10wt% sodium hydroxide aqueous solution to adjust the pH of the mixture to about 13. Then add 49g of 20wt% aluminum sulfate aqueous solution (0.03mol) and stir to mix evenly. Finally, age the mixture at 50℃ with vigorous stirring at 800rpm for 24h to obtain about 740g of precursor synthesis solution and place it in a polytetrafluoroethylene-lined hydrothermal reactor. The 1g support from step 1) was then transferred to the hydrothermal reactor for crystallization. The reactor was heated to 180℃ at a rate of 0.5℃ / min and held at that temperature for 280h. The temperature was then lowered to 30℃ at a rate of 1℃ / min. After crystallization, the solid was filtered and washed with deionized water until neutral. It was dried at 80℃ for 10h and then calcined at 600℃ for 10h to obtain the molecular sieve membrane catalyst precursor.

[0084] 3) The 40g molecular sieve membrane catalyst obtained according to step 2) was ultrasonically surface treated with 1000ml of 20wt% ammonium nitrate aqueous solution at an ultrasonic frequency of 40KHz and a temperature of 60℃ for 2h. Then, it was filtered, washed, dried and calcined under the same conditions as in step 2) to obtain the alumina supported molecular sieve membrane catalyst.

[0085] Examples 4-5

[0086] The catalyst was prepared according to the method of Example 1, except that the ammonium nitrate solution in Example 1 was replaced with equal amounts of ferric nitrate and cobalt nitrate solutions.

[0087] Comparative Example 1

[0088] The alumina powder used in step 1) of Example 1 was used as a catalyst, but molecular sieve membrane loading was not performed, as a comparison.

[0089] Comparative Example 2

[0090] The catalyst was prepared according to the method of Example 1, except that step 3) was omitted and step 2) was used to obtain the molecular sieve membrane catalyst precursor, as a comparison.

[0091] Comparative Example 3

[0092] The catalyst was prepared according to the method of Example 1, except that step 2) was omitted, and the raw material alumina powder from step 1) was used for ultrasonic surface treatment in step 3) to obtain the catalyst, as a comparison.

[0093] The catalysts prepared in the examples and comparative examples were used in the reaction of isobutylene amination to produce tert-butylamine:

[0094] Examples 6-10

[0095] The amination reaction in the microchannel reactor proceeds as follows:

[0096] The catalysts prepared in Examples 1-5 were crushed to 0.5-1 mm and packed into a 2 mm DC tube microchannel reactor. Before the reaction began, the catalysts were treated with hot nitrogen at 300°C and 0.1 MPaG for 10 h. The feedstock plunger pump was then turned on, and isobutylene and liquid ammonia were injected into the static mixer at a molar ratio of 1:1.5. After being mixed evenly, the mixture was passed through the microreactor for reaction at a temperature of 220°C, a pressure of 2 MPaG, and a space velocity of 10 h⁻¹. -1 The product was analyzed in real time by online chromatography, and the results are shown in Table 1.

[0097] Examples 11-12

[0098] The reaction process is the same as in Example 1, except that the reaction space velocity is 2 h⁻¹. -1 5h -1 The results are shown in Table 1.

[0099] Comparative Examples 4-9

[0100] The reaction process was the same as in Example 1, except that the catalysts prepared in Comparative Examples 1-3 and commercially available ZSM-5, ZSM-11, and MCM-41 molecular sieves were used as catalysts for evaluation. The results are shown in Table 1.

[0101] Table 1 Evaluation results of the examples and comparative examples

[0102]

[0103]

[0104] The results show that the catalyst activity and selectivity of the method of the present invention are significantly improved compared with the comparative example. By reducing the reaction scale through the microchannel reactor, mass and heat transfer are enhanced and reaction efficiency is improved. By using molecular sieve membrane catalyst combined with microchannel reactor, the reaction space velocity can be increased by more than 5 times compared with the traditional process to achieve the same conversion rate, which significantly improves the reaction efficiency. At the same time, the residence time of the catalyst in the channel is reduced, the catalyst lifetime is greatly improved, the reaction time is more than 1000 hours, and the carbon deposition of the catalyst is less than 5%.

Claims

1. A microchannel reactor amination reaction method, characterized in that the steps include... include: An alumina-supported molecular sieve membrane catalyst is loaded into a microchannel reactor, and liquid ammonia reacts with olefins inside the microchannel reactor to obtain an amination product. The alumina-supported molecular sieve membrane catalyst is prepared by the following method, including the following steps: 1) Mix alumina powder with water, stir evenly, compress into tablets, dry, calcine, polish smooth, then wash with solvent, dry, and obtain a carrier; 2) Using silicon source, aluminum source, template agent tetrapropylammonium hydroxide, mineralizer and water as raw materials, a precursor synthesis solution is prepared and transferred to the carrier in step 1) in a hydrothermal reactor for crystallization. After crystallization, the solution is filtered, washed with water until neutral, dried and calcined to obtain the molecular sieve membrane catalyst precursor. 3) The molecular sieve membrane catalyst precursor from step 2) is subjected to ultrasonic surface treatment with an ion exchange solution, then filtered, washed with water until neutral, dried, and calcined to obtain an alumina-supported molecular sieve membrane catalyst.

2. The amination reaction method using a microchannel reactor according to claim 1, characterized in that, Step 1) The alumina is one or more of α-Al₂O₃, θ-Al₂O₃, η-Al₂O₃, and γ-Al₂O₃; and / or Step 1) The amount of water used is 5-15 wt% of the alumina powder mass; and / or Step 1) After tableting, the drying process is carried out at a temperature of 30-60℃ for 24-48 hours; the calcination process is carried out at a temperature of 800-1400℃ for 12-24 hours; and / or In step 1), the solvent washing process involves a solvent volume ratio of 10-100:1 to the mass of alumina powder.

3. The amination reaction method using a microchannel reactor according to claim 2, characterized in that, The amount of water used is 6-8 wt% of the alumina powder.

4. The amination reaction method using a microchannel reactor according to claim 1, characterized in that, The alumina powder mentioned in step 1) has a bulk density of 0.2-1 g / ml and a specific surface area of ​​20-300 m². 2 / g, pore volume is 0.1-0.5ml / g; particle size is 5-100μm.

5. The amination reaction method using a microchannel reactor according to claim 1, characterized in that, The tablets mentioned in step 1) have a size of 1-3mm.

6. The amination reaction method using a microchannel reactor according to claim 1, characterized in that, Step 1) The solvent is selected from at least one of acetone, ethanol, and tetrahydrofuran.

7. The amination reaction method using a microchannel reactor according to claim 1, characterized in that, Step 2) The silicon source is at least one of silica, silica sol, tetraethyl orthosilicate, and silicon dioxide; The aluminum source is at least one of aluminum nitrate, sodium aluminate, and aluminum sulfate; The mineralizing agent is at least one of sodium hydroxide and potassium hydroxide; and / or Step 2) The mass ratio of silicon source to carrier is 9-200:1; The molar ratio of the template agent tetrapropylammonium hydroxide to the silicon source is 0.1-1.5:1; The molar ratio of the silicon source to the aluminum source is 20-50:1; and / or Step 2) The template agent tetrapropylammonium hydroxide and the aluminum source are respectively mixed with water to prepare an aqueous solution; and / or Step 2) The amount of mineralizer added is to adjust the pH of the solution to 12-14; and / or Step 2) The specific preparation process of the precursor synthesis solution is as follows: First, mix the aqueous solution of the template agent tetrapropylammonium hydroxide with the silicon source and stir vigorously for 1-5 hours. Then, add the mineralizing agent to adjust the pH of the solution to 12-14. Then, add the aqueous solution of the aluminum source and stir vigorously at 20-80℃ for 12-48 hours to obtain the precursor synthesis solution.

8. The amination reaction method using a microchannel reactor according to claim 7, characterized in that, The mass ratio of the silicon source to the carrier is 10-30:

1.

9. The amination reaction method using a microchannel reactor according to claim 7, characterized in that, The molar ratio of the template agent tetrapropylammonium hydroxide to the silicon source is 0.1-0.5:

1.

10. The amination reaction method using a microchannel reactor according to claim 7, characterized in that, The molar ratio of the silicon source to the aluminum source is 30-50:

1.

11. The amination reaction method using a microchannel reactor according to claim 7, characterized in that, The template agent, tetrapropylammonium hydroxide, is prepared as an aqueous solution with a concentration of 10-30 wt%.

12. The amination reaction method using a microchannel reactor according to claim 7, characterized in that, The aluminum source is prepared as an aqueous solution with a concentration of 10-40 wt%.

13. The amination reaction method using a microchannel reactor according to claim 7, characterized in that, The vigorous stirring speed is 500-1000 rpm.

14. The amination reaction method using a microchannel reactor according to claim 1, characterized in that, Step 2) The mass ratio of the precursor synthesis solution to the carrier is 50-750:1; and / or Step 2) crystallization is performed under the following conditions: the hydrothermal reactor is heated to 150-220°C at a rate of 0.5-2°C / min, held at that temperature for 100-300 hours, and then cooled to 30-60°C at a rate of 0.5-1°C / min; and / or The roasting in step 2) is carried out at a temperature of 450-650℃ for 6-18 hours.

15. The amination reaction method using a microchannel reactor according to claim 14, characterized in that, The hydrothermal reactor is a hydrothermal reactor with a polytetrafluoroethylene liner.

16. The amination reaction method using a microchannel reactor according to claim 1, characterized in that, Step 3) The volume ratio of the ion exchange solution to the mass of the molecular sieve membrane catalyst precursor is 20-30 ml / g; and / or Step 3) The ion exchange solution is selected from at least one aqueous solution of ammonium salts, alkaline earth metals, transition metal nitrates, or acetates; and / or Step 3) describes the ultrasonic surface treatment under the following conditions: ultrasonic frequency 20-50KHz; temperature 20-80℃; time 1-5h.

17. The amination reaction method using a microchannel reactor according to claim 16, characterized in that, The concentration of the ion exchange solution is 20-50 wt%.

18. The amination reaction method using a microchannel reactor according to claim 17, characterized in that, The concentration of the ion exchange solution is 20-30 wt%.

19. The amination reaction method using a microchannel reactor according to claim 1, characterized in that, Liquid ammonia and olefins are pumped into a static mixer via a diaphragm pump, then heated to the reaction temperature by a preheater, and finally introduced into a microchannel reactor for reaction. The reaction products are then separated to obtain the final product; and / or The olefin is one or more of isobutylene, ethylene, styrene, and propylene; and / or The feed molar ratio of the olefin to ammonia is 1:1-6; and / or The reaction is carried out at a pressure of 0.1-20 MPaG and a temperature of 200-400 °C; and / or The microchannel reactor has a direct-flow tubular structure with a diameter of 0.5-8 mm.

20. The amination reaction method using a microchannel reactor according to claim 19, characterized in that, The feed molar ratio of olefins to ammonia is 1:1.2-1.

8.

21. The amination reaction method using a microchannel reactor according to claim 19, characterized in that, The reaction is carried out at a pressure of 1-5 MPaG.

22. The amination reaction method using a microchannel reactor according to claim 19, characterized in that, The space velocity of the reaction is 0.5-50 h⁻¹. -1 .

23. The amination reaction method using a microchannel reactor according to claim 22, characterized in that, The airspeed is 2-12 h. -1 .

24. The amination reaction method using a microchannel reactor according to claim 22, characterized in that, The diameter is 1-3mm.

25. The amination reaction method using a microchannel reactor according to claim 1, characterized in that, Before the reaction begins, the catalyst is heat-treated in an inert gas atmosphere for 8-24 hours.

26. The amination reaction method using a microchannel reactor according to claim 25, characterized in that, The inert gas used in the heat treatment is one or more of nitrogen, helium, and argon.

27. The amination reaction method using a microchannel reactor according to claim 25, characterized in that, The heat treatment process conditions are: temperature 300-500℃, pressure 0.1-5MPaG.

28. The amination reaction method using a microchannel reactor according to claim 27, characterized in that, The heat treatment process conditions are: temperature 350-450℃, pressure 0.1-0.5MPaG.

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