A production process for directly catalytic amination of isobutene to synthesize tert-butylamine

Abstract

The present invention provides a production process for directly catalytic amination of isobutene to synthesize tert-butylamine. The production process of the present invention includes the steps of: mixing ZSM-5 zeolite with an aqueous solution of a soluble metal salt, and adjusting the pH to 3-6; after reflux adsorption and washing with water until neutral, drying to obtain a catalyst powder; mixing the catalyst powder, a binder, and an aqueous nitric acid solution uniformly to obtain a mixture, and through crystallization treatment, shaping, drying, and calcination, a molecular sieve catalyst doped with a metal element is obtained; under the catalysis of the molecular sieve catalyst doped with a metal element, liquid ammonia and isobutene undergo an amination reaction, and then tert-butylamine is obtained through purification. The present invention uses a molecular sieve acidic catalyst doped with a metal element to directly aminate isobutene and liquid ammonia in a liquid phase state to generate tert-butylamine; the catalyst of the method of the present invention has high catalytic efficiency, long catalyst life, low reaction temperature, high isobutene conversion rate, and high tert-butylamine selectivity.

Description

Technical Field

[0001] The present invention relates to a production process for directly catalytic amination of isobutene to synthesize tert-butylamine, belonging to the technical field of petrochemical industry. Background Art

[0002] As an important organic chemical raw material, tert-butylamine is mainly used for synthesizing rubber accelerator tert-butylbenzothiazole sulfenamide (NS) and tert-butylbisbenzothiazole sulfenamide (NOBS). At the same time, tert-butylamine is also an important intermediate for pharmaceuticals and pesticides; it can also be used in the production of dyes, lubricant additives, dyes, etc. With the increasingly strict national environmental protection requirements for rubber auxiliaries, as a green rubber auxiliary friendly to the environment, the market demand for the main downstream product of tert-butylamine, rubber accelerator NS, continues to rise, and the demand for high-quality and low-cost tert-butylamine is also increasing day by day.

[0003] Since the industrialization of tert-butylamine in the 1950s, process routes such as tert-butylurea hydrolysis method, tert-butylamide hydrolysis method, and isobutene-HCN method have been successively applied to the synthesis of tert-butylamine. The process route of directly aminating isobutene to prepare tert-butylamine has a clean process and high atom economy, meeting the requirements of green chemistry and sustainable development, and is the development direction of future research and industrial production of tert-butylamine.

[0004] US5840988A reports the use of a molecular sieve catalyst with an NES structure for the direct amination reaction of isobutene; the reaction temperature is 200-300 °C, the reaction pressure is 10-30 MPa, and the space velocity is 0.38-3 h -1 . However, this method has a relatively high reaction temperature and a low catalyst service life.

[0005] CN112745227A reports a method for preparing tert-butylamine from isobutene and ammonia. To avoid catalyst carbon deposition and extend the catalyst service life, water or tert-butanol needs to be introduced into the reactor to achieve competitive adsorption on the acidic sites of the catalyst. However, after the reaction, the water or tert-butanol in the material needs to be removed, and the steps are relatively cumbersome. The removal of water or tert-butanol involves higher energy consumption and more material losses; moreover, the isobutene conversion rate is not satisfactory.

[0006] According to the existing technology, the isobutene raw material in the isobutene amination reaction is prone to polymerization to form high-molecular carbides such as diisobutene. Due to the relatively high reaction temperature, the high-molecular polymer is prone to carbonization, causing blockage of the catalyst pores and reducing the catalyst life; most existing devices use fixed-bed adiabatic reactors for catalytic amination reactions under high temperature and high pressure, and the single-pass conversion rate of the amination reaction is relatively low; moreover, the existing methods have relatively high reaction temperatures, which is not conducive to the equilibrium conversion of isobutene thermodynamically.

[0007] To solve the above problems, the present invention is proposed. Summary of the Invention

[0008] In view of the deficiencies of the prior art, the present invention provides a production process for directly catalytic amination of isobutene to synthesize tert-butylamine. The present invention uses a molecular sieve acidic catalyst doped with metal elements to directly aminate isobutene and liquid ammonia in the liquid phase to produce tert-butylamine; the catalyst of the method of the present invention has high catalytic efficiency, long catalyst life, low reaction temperature, high isobutene conversion rate and high tert-butylamine selectivity.

[0009] The technical solution of the present invention is as follows:

[0010] A production process for directly catalytic amination of isobutene to synthesize tert-butylamine, comprising the steps of:

[0011] (1) Mix ZSM-5 zeolite with an aqueous solution of a soluble metal salt, and adjust the pH to 3-6; after reflux adsorption, washing with water until neutral, and drying to obtain a catalyst powder; mix the catalyst powder, binder, and aqueous nitric acid solution evenly to obtain a mixture, and after crystallization treatment, shaping, drying, and calcination, obtain a molecular sieve catalyst doped with metal elements;

[0012] (2) Under the catalysis of the molecular sieve catalyst doped with metal elements, liquid ammonia and isobutene are subjected to an amination reaction, and then purified to obtain tert-butylamine.

[0013] According to the preference of the present invention, in step (1), the soluble metal salt is one or a combination of two or more of gallium nitrate, iron sulfate, nickel nitrate, or copper nitrate; the mass concentration of the aqueous solution of the soluble metal salt is 7%-56%.

[0014] According to the preference of the present invention, in step (1), the mass ratio of ZSM-5 zeolite to the soluble metal salt is 1-15:1, preferably 4-7:1.

[0015] According to the preference of the present invention, in step (1), an aqueous phosphoric acid solution with a mass concentration of 10%-40% is used to adjust the pH.

[0016] According to the preference of the present invention, in step (1), the reflux adsorption temperature is 50°C-100°C, and the reflux adsorption time is 1-3 h.

[0017] According to the preference of the present invention, in step (1), the binder is one or a mixture of two or more of pseudo-boehmite, γ-Al 2 O 3 , aluminum sol, or silica-alumina sol.

[0018] According to the preference of the present invention, in step (1), the mass ratio of the catalyst powder to the binder is 1:0.1-0.2; the mass ratio of the catalyst powder to the volume of the aqueous nitric acid solution is 30-80:1 g / mL; the mass concentration of the aqueous nitric acid solution is 2%-10%.

[0019] Preferably according to the present invention, in step (1), the crystallization treatment method is as follows: the mixture is dispersed in a mixed solution of tetrapropylammonium bromide (TPABr), sodium hydroxide and water, and treated at 150 °C to 250 °C for 20 - 30 h; in the mixture, the molar ratio of SiO 2 , sodium hydroxide, tetrapropylammonium bromide and water is 1:0.02 - 0.1:0.05 - 0.2:50 - 70.

[0020] Preferably according to the present invention, in step (1), the forming method is meshing extrusion.

[0021] Preferably according to the present invention, in step (1), after forming, the drying temperature is 100 - 200 °C and the drying time is 2 h - 5 h.

[0022] Preferably according to the present invention, in step (1), the calcination temperature is 300 - 600 °C and the calcination time is 2 h - 5 h.

[0023] Preferably according to the present invention, in step (1), the molecular sieve catalyst doped with a metal element is a cylindrical strip with a height of 2 - 4 mm.

[0024] Preferably according to the present invention, in step (2), the amination reaction of liquid ammonia and isobutene is carried out in a fluidized bed adiabatic reactor, a high-pressure autoclave reactor or a fixed bed reactor; preferably, the amination reaction of liquid ammonia and isobutene is carried out in a fluidized bed adiabatic reactor.

[0025] Preferably, the fluidized bed adiabatic reactor includes: a catalyst storage distributor 2, a reaction chamber 8, a catalyst particle settler 6 and a solid-liquid separator 4;

[0026] The catalyst storage distributor 2 is fixed at the top inside the reaction chamber 8; the catalyst storage distributor 2 is composed of a storage tank 9 and a vibrating screen 10; the storage tank 9 is used for storing the catalyst; the storage tank 9 is located directly above the vibrating screen 10, and a valve is provided at the bottom of the storage tank 9 to control the release of the catalyst to the vibrating screen 10; a liquid ammonia inlet is provided at the upper part of the storage tank 9, which is connected to a liquid ammonia feed tank through a pipeline to input or output liquid ammonia; the storage tank 9 and the vibrating screen 10 are movably connected; the vibrating screen 10 can be of an existing structure; the shape and size of the holes on the vibrating screen 10 can be according to the existing technology, as long as the catalyst can pass through the screen and enter the reaction system;

[0027] A reaction material inlet 1 is provided on the lower side wall of the reaction chamber 8; a reaction material distributor 3 is provided inside the reaction chamber 8; the reaction material distributor 3 is composed of several vertical pipes connected in parallel, and the side walls and the top of the vertical pipes are covered with small holes, so that the reaction material can enter the reaction chamber 8 through the small holes, and at the same time, the catalyst is prevented from entering the reaction material distributor 3; the reaction material inlet 1 is connected to the reaction material distributor 3 through a pipeline;

[0028] The catalyst particle settler 6 is funnel-shaped, and a settler outlet is provided at the bottom of the catalyst particle settler 6, and a valve is provided at the settler outlet; the side wall of the catalyst particle settler 6 is directly connected to the lower end of the side wall of the reaction chamber 8, and the catalyst particle settler 6 communicates with the reaction chamber 8;

[0029] The solid-liquid separator 4 is provided with a reaction material outlet 5, a reaction material inlet, and a catalyst outlet; the reaction material inlet of the solid-liquid separator 4 is connected to the top of the side wall of the reaction chamber 8 through a pipeline; a valve is provided between the solid-liquid separator 4 and the reaction chamber 8;

[0030] The settler outlet of the catalyst particle settler 6 and the catalyst outlet of the solid-liquid separator 4 are connected to the storage tank 9 of the catalyst storage distributor 2 through the catalyst pipe chain circulation conveying system 7; the conveying mode of the pipe chain circulation conveying system 7 is pipe chain conveying, which can be according to the existing structure.

[0031] According to the present invention, the material of the reaction chamber 8 is a heat-insulating material or the reaction chamber 8 is coated with a heat-insulating material on the outside. The heat-insulating material is an existing material. An opening door is provided at the top of the reaction chamber 8, and the upper part of the storage tank 9 can be disassembled to load the catalyst; the above structure can be according to the existing technology.

[0032] According to the present invention, in step (2), the amount of the catalyst can be obtained according to the size of the fluidized bed adiabatic reactor and the production capacity of the device by the existing method.

[0033] Preferably according to the present invention, in step (2), the molar ratio of liquid ammonia to isobutene is 1-2:1, preferably 1.5-2:1.

[0034] Preferably according to the present invention, in step (2), before the amination reaction, an activation step of the molecular sieve catalyst doped with a metal element is further included, specifically as follows: soaking the molecular sieve catalyst doped with a metal element in liquid ammonia at room temperature for 3 to 13 h; preferably, the soaking time is 5 to 10 h. Through the above treatment, ammonia pre-occupies the catalyst reaction active sites.

[0035] Preferably according to the present invention, in step (2), the amination reaction temperature is 100 to 130 °C, the amination reaction pressure is 15 to 25 MPa, and the amination reaction residence time is 0.5 min - 10 min; preferably, the amination reaction pressure is 18 to 22 MPa.

[0036] According to the present invention, in step (2), the amination reaction is a catalytic reaction of a heterogeneous catalyst, that is, the reaction material is in a liquid state, the molecular sieve catalyst doped with a metal element is in a solid state, and the reaction occurs at the solid-liquid interface.

[0037] Preferably, according to the present invention, in step (2), after the amination reaction is completed, the obtained molecular sieve catalyst doped with metal elements is recovered and reused through solid-liquid separation; and the obtained liquid material is purified.

[0038] According to the preferred embodiment of the present invention, in step (2), the purification comprises the following steps: the liquid material is treated by a lightness removal tower to obtain crude tert-butylamine at the bottom of the tower, and unreacted isobutylene and liquid ammonia are separated from the top of the tower and recovered as raw materials; the pressure of the lightness removal tower is 1-3 MPa, the temperature of the top of the tower is 50-70°C, and the temperature of the bottom of the tower is 160-180°C; the crude tert-butylamine is transported to a refining tower, and after refining, tert-butylamine is obtained at the top of the tower, and heavy components such as by-product diisobutylene are obtained at the bottom of the tower; the pressure of the refining tower is 0.05Mpa-0.2MPa, the temperature of the top of the tower is 50°C-100°C, and the temperature of the bottom of the tower is 90-110°C.

[0039] Preferably, according to the present invention, in step (2), the method for preparing tert-butylamine using a floating bed adiabatic reactor comprises the steps of:

[0040] a. Loading the molecular sieve catalyst doped with metal elements into the storage tank 9 of the catalyst storage distributor 2 of the floating bed adiabatic reactor; inputting liquid ammonia through the liquid ammonia inlet of the storage tank 9, and soaking the catalyst at room temperature for 3 to 13 hours; outputting the recovered liquid ammonia to the liquid ammonia feed tank through the liquid ammonia inlet of the storage tank 9, and using it as a raw material;

[0041] b. Fully mix liquid ammonia and isobutylene, heat to 100-130° C., and pressurize to 15-25 MPa; then continuously introduce the liquid ammonia and isobutylene into the reaction chamber 8 and the catalyst particle settler 6 through the reaction material inlet 1 and the reaction material distributor 3 of the floating bed adiabatic reactor, fill the reaction chamber 8 and the catalyst particle settler 6 with the reaction material, and maintain the pressure in the reaction chamber 8 and the catalyst particle settler 6 at 15-25 MPa; simultaneously start the catalyst storage distributor 2, open the bottom valve of the storage tank 9, allow the molecular sieve catalyst doped with metal elements to enter the vibrating screen 10, and open the vibrating screen 10 to allow the molecular sieve catalyst doped with metal elements to evenly enter the reaction system; Under the condition of argonization, liquid ammonia and isobutylene undergo amination reaction, and the reaction residence time is 0.5min-10min; the reaction liquid after the amination reaction is continuously transported to the solid-liquid separator 4, and the liquid material and the molecular sieve catalyst doped with metal elements are obtained through solid-liquid separation; the obtained liquid material is continuously transported to the light removal tower, and the crude tert-butylamine is obtained at the bottom of the tower, and the unreacted isobutylene and liquid ammonia are separated from the top of the tower and recovered as raw materials; the crude tert-butylamine is continuously transported to the refining tower, and tert-butylamine is obtained at the top of the tower after refining, and heavy components such as by-product diisobutylene are obtained at the bottom of the tower; the molecular sieve catalyst doped with metal elements obtained through solid-liquid separation is continuously transported to the catalyst storage distributor 2 through the catalyst pipe chain circulation conveying system 7, and re-enters the reaction system.

[0042] Preferably, during the reaction process, a small amount of the molecular sieve catalyst doped with metal elements in the reaction system will settle to the bottom of the catalyst particle settler 6. Therefore, during the reaction process, the valve at the outlet of the settler of the catalyst particle settler 6 is periodically opened to collect the molecular sieve catalyst doped with metal elements, and then it is transported to the storage tank 9 of the catalyst storage distributor 2 through the catalyst tube chain circulation conveying system 7 and re-enters the reaction system.

[0043] Preferably, the heat source used for heating is one or a combination of two or more of steam, an electric heater, and the discharged material from the fluidized bed adiabatic reactor.

[0044] According to the present invention, the purpose of the catalyst storage distributor is to evenly distribute the catalyst to obtain a uniform reaction system.

[0045] The technical features and beneficial effects of the present invention are as follows:

[0046] 1. The present invention uses a molecular sieve acidic catalyst doped with metal elements, which has characteristics such as appropriate reaction pores, high reaction activity, and high mechanical strength. The raw materials used for the catalyst of the present invention are simple and easily available, the obtained catalyst has a long service life, and it does not need to be regenerated after the reaction and can be continuously used in the reactor for 2 to 3 years.

[0047] 2. During the preparation process of the catalyst of the present invention, a crystallization treatment method, namely liquid-phase transformation crystallization, is adopted. Through the crystallization process, the molecular sieve has richer intracrystalline mesopores, the mesopore volume is increased, so as to obtain better reaction efficiency, and at the same time, the service life of the catalyst is improved. Through the forming method of meshing extrusion (meshing by a meshing machine and extruding into thin strips), the catalyst is processed to have good mechanical strength and is more suitable for industrial production.

[0048] 3. Before the catalyst provided by the present invention for directly catalytic amination of isobutene to synthesize tert-butylamine is used, it is soaked with liquid ammonia, one of the reaction raw materials, so that ammonia can pre-occupy the catalyst reaction active sites. After reaching the adsorption-desorption equilibrium, the reaction is carried out, which can prevent the polymerization of olefins in the catalyst pores and extend the service life of the catalyst.

[0049] 4. The present invention adopts a fluidized bed adiabatic reactor, and a catalyst storage distributor is installed on the upper part of the reactor, which can effectively disperse the catalyst in the reactor and increase the catalytic efficiency of the catalyst. At the same time, the reactor is equipped with a catalyst circulation system, which can collect and reuse the catalyst and make the catalyst evenly distributed through the distributor.

[0050] 5. In the present invention, isobutene and liquid ammonia are directly aminated to form tert-butylamine in the liquid phase under the action of a catalyst. The specific catalyst of the present invention combined with a specific reaction pressure enables the reaction temperature of the present invention to be lower than that of the existing process. Under the temperature condition of 100°C to 130°C, olefin polymerization can be effectively reduced, the catalyst carbon deposition during the reaction can be reduced, thereby greatly extending the catalyst life; moreover, this reaction is an exothermic reaction, and a relatively low reaction temperature is beneficial to the forward progress of the reaction.

[0051] 6. As a whole, each step and each condition of the process method of the present invention work together to achieve the excellent effects of the present invention. The present invention provides a continuous production process, and the materials after the reaction are subjected to light component removal and refining to obtain tert-butylamine products. The process is simple and the product purity is high. The single-pass conversion rate of isobutene can reach 21%, the selectivity reaches 98.5%, and the purity of tert-butylamine after refining reaches more than 99.9%. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic structural diagram of a floating bed reactor for directly catalytic amination of isobutene to synthesize tert-butylamine according to the present invention;

[0053] Among them: 1 - reaction material inlet, 2 - catalyst storage and distributor, 3 - reaction material distributor, 4 - solid-liquid separator, 5 - reaction material outlet, 6 - catalyst particle settler, 7 - catalyst tube chain circulation and conveying system, 8 - reaction chamber, 9 - storage tank, 10 - vibrating screen. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] For the purpose of making the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0055] The raw materials, compounds, methods and devices not described in detail in the present invention are all prior arts and will not be elaborated.

[0056] In order to further understand the present invention, the following is a detailed description of a production process for directly catalytic amination of isobutene to synthesize tert-butylamine provided by the present invention in conjunction with embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0057] Example 1

[0058] A floating bed adiabatic reactor, comprising: a catalyst storage and distributor 2, a reaction chamber 8, a catalyst particle settler 6 and a solid-liquid separator 4;

[0059] The catalyst storage and distributor 2 is fixed to the top inside the reaction chamber 8; the catalyst storage and distributor 2 consists of a storage tank 9 and a vibrating screen 10; the storage tank 9 is used for storing the catalyst; the storage tank 9 is located directly above the vibrating screen 10, and a valve is provided at the bottom of the storage tank 9 to control the release of the catalyst to the vibrating screen 10; a liquid ammonia inlet is provided at the upper part of the storage tank 9 and is connected to the liquid ammonia feed tank through a pipeline to input or output liquid ammonia; the storage tank 9 and the vibrating screen 10 are movably connected; the vibrating screen 10 can be of the existing structure; the shape and size of the holes on the screen of the vibrating screen 10 can be according to the existing technology, as long as the catalyst can pass through the screen and enter the reaction system;

[0060] A reaction material inlet 1 is provided on the lower side wall of the reaction chamber 8; a reaction material distributor 3 is provided inside the reaction chamber 8; the reaction material distributor 3 is composed of several vertical pipes connected in parallel, and the side walls and the top of the vertical pipes are covered with small holes so that the reaction materials can enter the reaction chamber 8 through the small holes, and at the same time, the catalyst is prevented from entering the reaction material distributor 3; the reaction material inlet 1 is connected to the reaction material distributor 3 through a pipeline;

[0061] The catalyst particle settler 6 is in a funnel shape, a settler outlet is provided at the bottom of the catalyst particle settler 6, and a valve is provided at the settler outlet; the side wall of the catalyst particle settler 6 is directly connected to the lower end of the side wall of the reaction chamber 8, and the catalyst particle settler 6 and the reaction chamber 8 are communicated;

[0062] The solid-liquid separator 4 is provided with a reaction material outlet 5, a reaction material inlet and a catalyst outlet; the reaction material inlet of the solid-liquid separator 4 is connected to the bottom of the side wall of the reaction chamber 8 through a pipeline; a valve is provided between the solid-liquid separator 4 and the reaction chamber 8;

[0063] The settler outlet of the catalyst particle settler 6 and the catalyst outlet of the solid-liquid separator 4 are connected to the storage tank 9 of the catalyst storage and distributor 2 through a catalyst tube chain circulation conveying system 7; the conveying mode of the tube chain circulation conveying system 7 is tube chain conveying, which can be of the existing structure.

[0064] The reaction chamber 8 is coated with heat insulation material. The heat insulation material is an existing material. An opening door is provided at the top of the reaction chamber 8, and the upper part of the storage tank 9 can be disassembled to load the catalyst; the above structure can be according to the existing technology.

[0065] Example 2

[0066] A production process for directly catalytic amination of isobutene to synthesize tert-butylamine, including the steps:

[0067] (1) Put 120 g of Cu(NO 3 ) 2 ·3H 2O was dissolved in 880 mL of pure water to prepare an aqueous copper nitrate solution with a concentration of 12 wt%. 210 g of Ga(NO 3 ) 2 ·9H 2 O was dissolved in 790 mL of pure water to prepare an aqueous gallium nitrate solution with a concentration of 21 wt%. 600 mL of the aqueous copper nitrate solution, 700 mL of the aqueous gallium nitrate solution and 1000 g of ZSM-5 zeolite were stirred and mixed thoroughly. A dilute phosphoric acid aqueous solution with a mass concentration of 20% was added dropwise to adjust the pH to 3. After reflux adsorption at 50 °C for 2 h, the solid powder was washed with pure water until the pH reached 7, and then filtered and dried to obtain the catalyst powder.

[0068] 1000 g of the obtained catalyst powder was mixed evenly with 105 g of pseudoboehmite and 20 mL of a nitric acid aqueous solution with a mass concentration of 5% to obtain a mixture. The mixture was dispersed in an aqueous solution containing TPABr and sodium hydroxide, and the molar ratio of SiO 2 , sodium hydroxide, tetrapropylammonium bromide and water in the mixture was controlled to be 1:0.1:0.15:50. The system was crystallized at 200 °C for 24 h. After meshing and extrusion molding, it was dried at 120 °C for 5 h and calcined at 500 °C for 5 h to obtain a molecular sieve catalyst doped with metal elements, that is, cylindrical long particles with a height of 3 mm.

[0069] (2) 800 g of the above molecular sieve catalyst doped with metal elements was loaded into the storage tank 9 of the catalyst storage distributor 2 of the floating bed adiabatic reactor described in Example 1; liquid ammonia was input through the liquid ammonia inlet of the storage tank 9, and the catalyst was soaked at room temperature for 10 h; the recycled liquid ammonia was output through the liquid ammonia inlet of the storage tank 9 to the liquid ammonia feed tank.

[0070] According to the molar ratio of liquid ammonia to isobutene of 1.6:1, the raw material isobutene and liquid ammonia are mixed in a feed tank; pressurized to 20 MPa by a feed pump, and the material is heated to 130 °C using steam; then continuously introduced into the reaction chamber 8 and the catalyst particle settler 6 through the reaction material inlet 1 and the reaction material distributor 3 of the fluidized bed adiabatic reactor. The reaction chamber 8 and the catalyst particle settler 6 are filled with the reaction material, and the pressure in the reaction chamber 8 and the catalyst particle settler 6 is maintained at 20 MPa. At the same time, start the catalyst storage distributor 2, open the bottom valve of the storage tank 9, and the molecular sieve catalyst doped with metal elements enters the vibrating screen 10. Turn on the vibrating screen 10 to evenly introduce the molecular sieve catalyst doped with metal elements into the reaction system; under the catalysis of the molecular sieve catalyst doped with metal elements, liquid ammonia and isobutene carry out an amination reaction, and the reaction residence time is 3 min. The reaction liquid after the amination reaction is continuously transported to the solid-liquid separator 4, and liquid material and the molecular sieve catalyst doped with metal elements are obtained through solid-liquid separation; the obtained liquid material continuously enters the light component removal tower. The pressure of the light component removal tower is 1.9 MPa, the top temperature is 50 °C, the bottom temperature is 169 °C, and crude tert-butylamine is obtained at the bottom. Unreacted isobutene and liquid ammonia are separated from the top and recycled into the feed tank for use as raw materials; the crude tert-butylamine is continuously transported to the refining tower. The pressure of the refining tower is 0.07 MPa, the top temperature is 59 °C, the bottom temperature is 98 °C. After refining, tert-butylamine is obtained at the top, and heavy components such as diisobutene are obtained at the bottom as by-products; the molecular sieve catalyst doped with metal elements obtained through solid-liquid separation is continuously transported to the catalyst storage distributor 2 through the catalyst tube chain circulation conveying system 7 and re-enters the reaction system;

[0071] During the reaction process, regularly open the valve at the outlet of the catalyst particle settler 6 of the settler to collect the molecular sieve catalyst doped with metal elements, and then transport it to the storage tank 9 of the catalyst storage distributor 2 through the catalyst tube chain circulation conveying system 7 and re-enter the reaction system.

[0072] In the above continuous reaction system, samples of the reaction material (reactor outlet material) obtained at the reaction material outlet 5 and the refined tert-butylamine product are taken every 1 h for gas chromatography analysis, and the operation lasts for 240 h. Partial chromatographic analysis results of the reactor outlet material and the tert-butylamine product are shown in Table 1;

[0073] Table 1 Partial gas chromatography analysis data of the reactor outlet material and the tert-butylamine product in Example 1

[0074]

[0075] According to the mass ratio of each component analyzed by gas chromatography, the average single-pass conversion rate of isobutene can reach 21%, and the selectivity of isobutene converted to tert-butylamine is above 98.5%. After the process of the present invention operates stably, the purity of the refined tert-butylamine product can reach above 99.95%.

[0076] In summary, the production process for synthesizing tert-butylamine by direct catalytic amination of isobutylene provided by the present invention has a simple process, high per-pass conversion rate, good product selectivity, few reaction by-products, and mild reaction conditions. The floating bed reactor is used for reaction, the reactor structure is simple, continuous operation can be achieved, the product stability is good, and the product purity is high. After a long period of continuous reaction, the catalytic activity of the catalyst does not decrease, indicating that the catalyst produced by the process has good stability and a long service life.

[0077] Example 3

[0078] A production process for synthesizing tert-butylamine by direct catalytic amination of isobutylene, comprising the steps of:

[0079] (1) 240 g Cu(NO 3 ) 2 ·3H 2 O was dissolved in 760 mL pure water, and a 24 wt% copper nitrate aqueous solution was prepared. 760 mL copper nitrate aqueous solution and 1000 g ZSM-5 zeolite were fully stirred and mixed. A 20% mass concentration dilute phosphoric acid aqueous solution was added dropwise to adjust the pH to 3, and after reflux adsorption at 50°C for 2 hours, the solid powder was washed with pure water until the pH was 7. Then the catalyst powder was obtained after filtration and drying.

[0080] 1000 g of the obtained catalyst powder was uniformly mixed with 105 g of pseudo-boehmite and 20 mL of a 5% nitric acid aqueous solution to obtain a mixture, which was dispersed in an aqueous solution containing TPABr and sodium hydroxide to control the SiO 2 The molar ratio of sodium hydroxide, tetrapropylammonium bromide and water is 1:0.1:0.15:50. The system is placed at 200°C for crystallization for 24 hours. After meshing extrusion, drying at 120°C for 5 hours, and calcining at 500°C for 5 hours, a molecular sieve catalyst doped with metal elements is obtained, that is, cylindrical long strip particles with a height of 3 mm.

[0081] (2) Step (2) is the same as in Example 2.

[0082] In the above continuous reaction system, the reaction material (reactor discharge) obtained from the reaction material outlet 5 is sampled every 1 hour for gas chromatography analysis.

[0083] Among the main components of the reactor discharge (reactor operation 120h), NH 3 The mass ratio is 29.26%, C 4 H 8 The mass ratio is 53.86%, C 4 H 11 The mass ratio of N is 16.58%, and the mass ratio of C 8 H16 The mass ratio is 0.18%, and the mass ratio of other heavy components is 0.12%. The single-pass conversion rate of isobutene is calculated to be 19.97%, and the selectivity of isobutene converted to tert-butylamine is 94.65%.

[0084] Example 4

[0085] A production process for directly catalytic amination of isobutene to synthesize tert-butylamine, comprising the steps:

[0086] (1) Prepare a molecular sieve catalyst doped with metal elements according to the method of Example 2.

[0087] (2) Step (2) is as described in Example 2, the difference is: the activation step of the molecular sieve catalyst doped with metal elements is omitted. Other steps and conditions are the same as those in Example 2.

[0088] That is: load 800 g of the above-mentioned molecular sieve catalyst doped with metal elements into the storage tank 9 of the catalyst storage distributor 2 of the floating bed adiabatic reactor described in Example 1. According to the molar ratio of liquid ammonia to isobutene of 1.6:1, mix the raw materials isobutene and liquid ammonia in the feed tank; pressurize to 20 MPa by a feed pump, and use steam to heat the material to 130 °C; then continuously introduce it into the reaction chamber 8 and the catalyst particle settler 6 through the reaction material inlet 1 and the reaction material distributor 3 of the floating bed adiabatic reactor. The reaction chamber 8 and the catalyst particle settler 6 are filled with the reaction material, and the pressure in the reaction chamber 8 and the catalyst particle settler 6 is maintained at 20 MPa. At the same time, start the catalyst storage distributor 2, open the bottom valve of the storage tank 9, the molecular sieve catalyst doped with metal elements enters the vibrating screen 10, turn on the vibrating screen 10, and make the molecular sieve catalyst doped with metal elements evenly enter the reaction system; under the catalysis of the molecular sieve catalyst doped with metal elements, liquid ammonia and isobutene carry out an amination reaction, and the reaction residence time is 3 min. The reaction liquid after the amination reaction is continuously transported to the solid-liquid separator 4, and liquid material and the molecular sieve catalyst doped with metal elements are obtained after solid-liquid separation; the obtained liquid material continuously enters the light component removal tower, the pressure of the light component removal tower is 1.9 MPa, the top temperature is 50 °C, the bottom temperature is 169 °C, and crude tert-butylamine is obtained at the bottom of the tower. Unreacted isobutene and liquid ammonia are separated from the top of the tower and recycled into the feed tank for use as raw materials; the crude tert-butylamine is continuously transported to the refining tower, the pressure of the refining tower is 0.07 MPa, the top temperature is 59 °C, the bottom temperature is 98 °C, and after refining, tert-butylamine is obtained at the top of the tower, and heavy components such as diisobutene are obtained at the bottom of the tower; the molecular sieve catalyst doped with metal elements obtained by solid-liquid separation is continuously transported to the catalyst storage distributor 2 through the catalyst tube chain circulation transport system 7 and re-enters the reaction system;

[0089] During the reaction process, the valve at the outlet of the catalyst particle settler 6 is periodically opened to collect the molecular sieve catalyst doped with metal elements, which is then transported to the storage tank 9 of the catalyst storage distributor 2 through the catalyst tube chain circulation conveying system 7 and re-enters the reaction system.

[0090] In the above continuous reaction system, samples of the reaction materials (reactor discharge) obtained from the reaction material outlet 5 are taken every 1 h for gas chromatography analysis.

[0091] Among the main components of the reactor discharge (the reactor runs for 120 h), the mass ratio of NH 3 is 29.64%, and the mass ratio of C 4 H 8 is 53.97%, the mass ratio of C 4 H 11 N is 15.23%, the mass ratio of C 8 H 16 is 0.85%, and the mass ratio of other heavy components is 0.31%. The single-pass conversion rate of isobutene is calculated to be 19.80%, and the selectivity of isobutene converted to tert-butylamine is 87.66%.

[0092] Example 5

[0093] A production process for directly catalytic amination of isobutene to synthesize tert-butylamine, including the steps:

[0094] (1) Prepare the molecular sieve catalyst doped with metal elements according to the method of Example 2.

[0095] (2) Take 10 g of the catalyst particles obtained in the above steps and put them into a high-pressure autoclave reactor (a commercially available device). 27.2 g of liquid ammonia is introduced into the reactor. After soaking at room temperature for 10 h, 56.1 g of isobutene is introduced. After mixing evenly, the reactor is heated to 130 °C and maintained at a pressure of 20 MPa for 1 h.

[0096] Samples are taken for gas chromatography analysis. The conversion rate of isobutene is calculated to be 11.2%, and the selectivity is 91.6%. Nearly 0.5 g of isobutene polymerizes to form diisobutene.

[0097] Example 6

[0098] A production process for directly catalytic amination of isobutene to synthesize tert-butylamine, including the steps:

[0099] (1) Prepare the molecular sieve catalyst doped with metal elements according to the method of Example 2.

[0100] (2) Load 800 g of the molecular sieve catalyst doped with metal elements into the catalyst packing layer in the middle of a fixed-bed reactor (a commercially available device). Input liquid ammonia, soak the catalyst at room temperature for 10 h; output and recycle the liquid ammonia to the liquid ammonia feed tank.

[0101] According to the molar ratio of liquid ammonia to isobutene being 1.6:1, after mixing the raw material isobutene and liquid ammonia in the feed tank, boost the pressure to 20 MPa through a feed pump, use steam to heat the material to 130 °C, and continuously feed it into the reactor, with the pressure in the reactor maintained at 20 MPa. Under the catalysis of the molecular sieve catalyst doped with metal elements, liquid ammonia and isobutene carry out an amination reaction, and the reaction residence time is 3 min. The reaction liquid after the amination reaction continuously enters the light component removal tower. The pressure of the light component removal tower is 1.9 MPa, the top temperature is 50 °C, the bottom temperature is 169 °C, crude tert-butylamine is obtained at the bottom of the tower, and the unreacted isobutene and liquid ammonia are separated from the top of the tower and recycled into the feed tank for use as raw materials.

[0102] In the above continuous reaction system, samples are taken from the reactor outlet and the crude tert-butylamine at the bottom of the light component removal tower for gas chromatography analysis every 1 h, and the operation lasts for 72 h. The chromatographic analysis results of the reactor outlet part are shown in Table 1:

[0103] Table 2 Gas Chromatography Analysis Data of the Reactor Outlet in Comparative Example 2

[0104]

[0105] According to the mass percentage of each component analyzed by gas chromatography, calculate that the average single-pass conversion rate of isobutene is 19.98%, and the selectivity of tert-butylamine is 96.92%.

[0106] Comparative Example 1

[0107] A production process for directly catalytic amination of isobutene to synthesize tert-butylamine, as described in Example 2, the difference is: in step (1) during the catalyst preparation process, the crystallization treatment step is omitted; other steps and conditions are the same as in Example 2.

[0108] That is, the catalyst preparation method is as follows:

[0109] Dissolve 120 g of Cu(NO 3 ) 2 ·3H 2 O in 880 mL of pure water to prepare an aqueous copper nitrate solution with a concentration of 12 wt%. Dissolve 210 g of Ga(NO 3 ) 2 ·9H 2O was dissolved in 790 mL of pure water, and a gallium nitrate aqueous solution with a concentration of 21 wt% was prepared. 600 mL of copper nitrate aqueous solution, 700 mL of gallium nitrate aqueous solution and 1000 g of ZSM-5 zeolite were fully stirred and mixed. A dilute phosphoric acid aqueous solution with a mass concentration of 20% was dripped into the solution to adjust the pH to 3, and after reflux adsorption at 50°C for 2 h, the solid powder was washed with pure water until the pH was 7, and then filtered and dried to obtain the catalyst powder.

[0110] The obtained 1000g catalyst powder was evenly mixed with 105g pseudo-boehmite and 20mL 5% mass concentration nitric acid aqueous solution, extruded into strips by meshing, dried at 120°C for 5h, and calcined at 500°C for 5h to obtain a molecular sieve catalyst doped with metal elements, i.e., cylindrical long strip particles with a height of 3mm.

[0111] In the continuous reaction system, the reaction material (reactor discharge) obtained from the reaction material outlet 5 and the tert-butylamine product obtained after purification were sampled for gas chromatography analysis every 1 hour, and the operation was carried out for a total of 240 hours.

[0112] Within 160 hours of reaction operation, the average single-pass conversion rate of isobutylene was 20.21%, and the selectivity of isobutylene to tert-butylamine was 98.51%. After the 160th hour of operation, the single-pass conversion rate of isobutylene gradually decreased and averaged 18.45%.

[0113] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A production process for directly catalytic amination of isobutene to synthesize tert-butylamine, comprising the steps: (1) Mix ZSM-5 zeolite with an aqueous solution of a soluble metal salt, and adjust the pH to 3-6; after reflux adsorption and washing with water until neutral, dry to obtain a catalyst powder; mix the catalyst powder, binder, and aqueous nitric acid solution evenly to obtain a mixture, and after crystallization treatment, shaping, drying, and calcination, obtain a molecular sieve catalyst doped with metal elements; The soluble metal salts are a combination of gallium nitrate and copper nitrate; the binder is one or a mixture of two or more of pseudoboehmite, γ-Al 2 O 3 , aluminum sol or silica-alumina sol; the crystallization treatment method is as follows: disperse the mixture in a mixed solution of tetrapropylammonium bromide (TPABr), sodium hydroxide and water, and treat it at 150°C to 250°C for 20 - 30 h; the molar ratio of SiO 2 , sodium hydroxide, tetrapropylammonium bromide and water in the mixture is 1:0.02 - 0.1:0.05 - 0.2:50 - 70; the calcination temperature is 300°C to 600°C, and the calcination time is 2 h - 5 h; (2) Under the catalysis of the molecular sieve catalyst doped with metal elements, liquid ammonia and isobutene undergo an amination reaction, and then tert-butylamine is obtained through purification; Before the amination reaction, it also includes an activation step of the molecular sieve catalyst doped with metal elements, specifically as follows: soak the molecular sieve catalyst doped with metal elements in liquid ammonia at room temperature for 3-13 h; The amination reaction of liquid ammonia and isobutene is carried out in a fluidized bed adiabatic reactor or a fixed bed reactor; The amination reaction temperature is 100-130 °C, the amination reaction pressure is 15-25 MPa, and the amination reaction residence time is 0.5 min - 10 min.

2. The production process for directly catalytic amination of isobutene to synthesize tert-butylamine according to claim 1, characterized in that, in step (1), one or more of the following conditions are included: i. The mass concentration of the aqueous solution of the soluble metal salt is 7%-56%; ii. The mass ratio of ZSM-5 zeolite to the soluble metal salt is 1-15:1; iii. Adjust the pH using an aqueous phosphoric acid solution with a mass concentration of 10%-40%; iv. The reflux adsorption temperature is 50 °C - 100 °C, and the reflux adsorption time is 1-3 h; v. The mass ratio of the catalyst powder to the binder is 1:0.1-0.2; the mass of the catalyst powder and the volume ratio of the aqueous nitric acid solution is 30-80:1 g / mL; the mass concentration of the aqueous nitric acid solution is 2%-10%.

3. The production process for directly catalytic amination of isobutene to synthesize tert-butylamine according to claim 1, characterized in that, in step (1), one or more of the following conditions are included: i. The shaping method is meshing extrusion; ii. The drying temperature after shaping is 100-200 °C, and the drying time is 2 h - 5 h.

4. The production process for directly catalytic amination of isobutene to synthesize tert-butylamine according to claim 3, characterized in that, the molecular sieve catalyst doped with metal elements is a cylindrical long strip with a height of 2-4 mm.

5. The production process for directly catalytic amination of isobutene to synthesize tert-butylamine according to claim 1, characterized in that, in step (2), the fluidized bed adiabatic reactor includes: a catalyst storage distributor 2, a reaction chamber 8, a catalyst particle settler 6, and a solid-liquid separator 4; The catalyst storage distributor 2 is fixed at the top inside the reaction chamber 8; the catalyst storage distributor 2 consists of a storage tank 9 and a vibrating screen 10; the storage tank 9 is used to store the catalyst; the storage tank 9 is located directly above the vibrating screen 10, and a valve is provided at the bottom of the storage tank 9 to control the release of the catalyst to the vibrating screen 10; a liquid ammonia inlet is provided at the upper part of the storage tank 9, which is connected to a liquid ammonia feed tank through a pipeline to input or output liquid ammonia; the storage tank 9 and the vibrating screen 10 are movably connected; A reaction material inlet 1 is provided on the lower side wall of the reaction chamber 8; a reaction material distributor 3 is arranged in the reaction chamber 8; the reaction material distributor 3 is composed of several vertical pipes connected in parallel, and the side walls and the top of the vertical pipes are covered with small holes, so that the reaction material enters the reaction chamber 8 through the small holes, and at the same time, the catalyst is prevented from entering the reaction material distributor 3; the reaction material inlet 1 is connected to the reaction material distributor 3 through a pipe; The catalyst particle settler 6 is in a funnel shape, a settler outlet is arranged at the bottom of the catalyst particle settler 6, and a valve is arranged at the settler outlet; the side wall of the catalyst particle settler 6 is directly connected to the lower end of the side wall of the reaction chamber 8, and the catalyst particle settler 6 communicates with the reaction chamber 8; The solid-liquid separator 4 is provided with a reaction material outlet 5, a reaction material inlet and a catalyst outlet; the reaction material inlet of the solid-liquid separator 4 is connected to the top of the side wall of the reaction chamber 8 through a pipe; a valve is arranged between the solid-liquid separator 4 and the reaction chamber 8; The settler outlet of the catalyst particle settler 6 and the catalyst outlet of the solid-liquid separator 4 are connected to the storage tank 9 of the catalyst storage distributor 2 through the catalyst pipe chain circulation conveying system 7.

6. The production process for directly catalytic amination of isobutene to synthesize tert-butylamine according to claim 1, characterized in that, in step (2), one or more of the following conditions are included: i. The molar ratio of liquid ammonia to isobutene is 1-2:1; ii. After the amination reaction is completed, through solid-liquid separation, the molecular sieve catalyst doped with metal elements obtained is recovered and reused; the obtained liquid material is purified; the purification includes the steps: the liquid material is treated by a light component removal tower, and crude tert-butylamine is obtained at the bottom of the tower, and unreacted isobutene and liquid ammonia are separated from the top of the tower and recovered for use as raw materials; the pressure of the light component removal tower is 1~3 MPa, the top temperature of the tower is 50~70 °C, and the bottom temperature of the tower is 160-180 °C; the crude tert-butylamine is transported to a refining tower, and after refining, tert-butylamine is obtained at the top of the tower, and the by-product diisobutene heavy component is obtained at the bottom of the tower; the pressure of the refining tower is 0.05 Mpa-0.2 MPa, the top temperature of the tower is 50 °C-100 °C, and the bottom temperature of the tower is 90-110 °C.

7. The production process for directly catalytic amination of isobutene to synthesize tert-butylamine according to claim 1, characterized in that, in step (2), the amination reaction pressure is 18~22 MPa.

8. The production process for directly catalytic amination of isobutene to synthesize tert-butylamine according to claim 1, characterized in that, in step (2), the method for preparing tert-butylamine by using a fluidized bed adiabatic reactor includes the steps: a. Load the molecular sieve catalyst doped with metal elements into the storage tank 9 of the catalyst storage distributor 2 of the fluidized bed adiabatic reactor; input liquid ammonia through the liquid ammonia inlet of the storage tank 9, and soak the catalyst at room temperature for 3~13 h; output and recycle the liquid ammonia from the liquid ammonia inlet of the storage tank 9 to the liquid ammonia feed tank for use as a raw material; b. Thoroughly mix liquid ammonia and isobutene, heat to 100 - 130 °C, and pressurize to 15 - 25 MPa; then continuously feed through the reaction material inlet 1 of the floating bed adiabatic reactor and the reaction material distributor 3 into the reaction chamber 8 and the catalyst particle settler 6. The reaction chamber 8 and the catalyst particle settler 6 are filled with the reaction material, and the pressure in the reaction chamber 8 and the catalyst particle settler 6 is maintained at 15 - 25 MPa; at the same time, start the catalyst storage distributor 2, open the bottom valve of the storage tank 9, and the molecular sieve catalyst doped with metal elements enters the vibrating screen 10. Turn on the vibrating screen 10 to evenly introduce the molecular sieve catalyst doped with metal elements into the reaction system; under the catalysis of the molecular sieve catalyst doped with metal elements, liquid ammonia and isobutene carry out an amination reaction, and the reaction residence time is 0.5 min - 10 min; the reaction liquid after the amination reaction is continuously transported to the solid-liquid separator 4, and liquid material and the molecular sieve catalyst doped with metal elements are obtained through solid-liquid separation; the obtained liquid material continuously enters the light component removal tower, and crude tert-butylamine is obtained at the bottom of the tower. Unreacted isobutene and liquid ammonia are separated from the top of the tower and recycled as raw materials; the crude tert-butylamine is continuously transported to the refining tower. After refining, tert-butylamine is obtained at the top of the tower, and the by-product diisobutene heavy components are obtained at the bottom of the tower; the molecular sieve catalyst doped with metal elements obtained through solid-liquid separation is continuously transported to the catalyst storage distributor 2 through the catalyst tube chain circulation conveying system 7 and re-enters the reaction system; During the reaction process, a small part of the molecular sieve catalyst doped with metal elements in the reaction system will settle to the bottom of the catalyst particle settler 6. Therefore, during the reaction process, regularly open the valve at the outlet of the catalyst particle settler 6 to collect the molecular sieve catalyst doped with metal elements, and then transport it to the storage tank 9 of the catalyst storage distributor 2 through the catalyst tube chain circulation conveying system 7 and re-enter the reaction system.

Images