A kind of production method of bismorpholinyl diethyl ether

Abstract

The present application discloses a kind of production method of bismorpholinyl diethyl ether, it is with molecular sieve type catalyst as catalyst, raw material N hydroxyethyl morpholine enters into reactor and reacts, the moisture generated by reaction enters into cooling device after being discharged from the top of reactor and is cooled, the material discharged from reactor bottom enters in rectifying tower, the unreacted N hydroxyethyl morpholine separated from rectifying tower enters reactor and is recycled, and the bottom material at the bottom of rectifying tower is used as product bismorpholinyl diethyl ether;Molecular sieve type catalyst is obtained after being modified by alkaline earth metal by acidic mesoporous molecular sieve.Utilizing the present application, the conversion rate of N hydroxyethyl morpholine can be made to reach 97.5 99.1wt%, improves reaction efficiency, saves separation energy consumption, and also simultaneously improves product yield.

Description

Technical Field

[0001] The invention relates to a method for producing bismorpholinyl diethyl ether. Background Art

[0002] The molecular formula of bismorpholino diethyl ether (DMDEE) is C 12 H 24 N2O3 is a strong foaming catalyst. It appears as a colorless to pale yellow liquid, soluble in water, and is an amine catalyst suitable for water-curing systems. Due to the steric hindrance of the amino group, NCO-containing components have a very long shelf life. It is primarily used in one-component rigid polyurethane foam systems, but can also be used in polyether and polyester polyurethane soft foams, semi-rigid foams, and case materials. DMDEE is one of the three major polyurethane catalysts, but domestic production capacity is limited and relies primarily on imports.

[0003] There are many methods for synthesizing bismorpholino diethyl ether, but the two methods that have been truly implemented for large-scale industrial production are as follows: (1) diethylene glycol and ammonia react in the presence of hydrogen and a metal catalyst at high temperature and high pressure to produce bismorpholino diethyl ether; (2) diethylene glycol and morpholine react in the presence of hydrogen and a metal catalyst, copper or cobalt, at high temperature and high pressure to produce bismorpholino diethyl ether. Both of the above synthetic routes use metals as catalysts and generally proceed in the gas phase at high temperature and high pressure. These routes have the disadvantages of high production cost, difficulty in operation, and difficulty in product separation.

[0004] In addition, Zheng Xueming et al. disclosed a method using dichloroethyl ether and morpholine as raw materials and post-treatment with sodium hydroxide. This process will produce a large amount of sodium chloride as a by-product, the amount of wastewater is large, it is difficult to handle, and it causes serious corrosion to the equipment. Patent US4095022 discloses a method for preparing DMDEE, which uses N-hydroxyethyl morpholine as a raw material and a phosphorus-containing substance as a catalyst to react at 240-280°C to obtain DMDEE. This method requires reaction at high temperature, and phosphorus-containing waste liquid is generated, which is not environmentally friendly. Patent CN201910358412 discloses a method for producing bismorpholino diethyl ether, which uses triethanolamine (TEOA for short) and concentrated sulfuric acid as raw materials, and is etherified, neutralized, and distilled to obtain a method for preparing DMDEE. However, the product yield of this method is low, and concentrated sulfuric acid is a strong acid, which has high requirements for equipment.

[0005] The synthesis of bismorpholinyl diethyl ether using N-hydroxyethylmorpholine as a raw material produces water as the main byproduct, and has good selectivity. However, this method currently uses a fixed-bed reactor with activated alumina, SiO2-Al2O3, or SiO2 loaded with a phosphorus compound as the catalyst. The product yield is low, generally only reaching 16.2-56.6% by weight, which is far from industrial level and is in great need of improvement. Summary of the Invention

[0006] In order to improve the product yield of bismorpholinyl diethyl ether, the present invention provides a production method of bismorpholinyl diethyl ether. The method uses a molecular sieve catalyst as a catalyst, wherein a raw material N-hydroxyethyl morpholine enters a reactor for reaction, water generated by the reaction is discharged from the top of the reactor and then enters a cooling device for cooling, the material discharged from the bottom of the reactor enters a distillation tower, the unreacted N-hydroxyethyl morpholine separated from the distillation tower enters the reactor for recycling, and the bottom material at the bottom of the distillation tower is used as the product bismorpholinyl diethyl ether. The molecular sieve catalyst is obtained by modifying an acidic mesoporous molecular sieve with an alkaline earth metal.

[0007] Specifically, the acidic mesoporous molecular sieve is an acidic molecular sieve containing a mesoporous structure of 2-50 nm, and the acidic mesoporous molecular sieve is selected from Al-modified silicon-based mesoporous molecular sieves, microporous acidic molecular sieves with mesoporous structures, and acidic molecular sieves with mesoporous structures themselves. The Al-modified silicon-based mesoporous molecular sieve is selected from M41S series, SBA-n series, MSU series, CMK series, HMS or KIT series, etc.; the microporous acidic molecular sieve with mesoporous structures is selected from mesoporous Y-type molecular sieve, mesoporous ZSM-5 molecular sieve or mesoporous β molecular sieve, etc.; the acidic molecular sieve with mesoporous structures itself is selected from MCM-36.

[0008] This method differs from existing methods for preparing bismorpholinyl diethyl ether in that it utilizes a molecular sieve catalyst, which is highly active and produces a high product yield. It is also non-corrosive to equipment, resulting in mild reaction conditions and reduced equipment investment. Furthermore, the use of N-hydroxyethylmorpholine as a raw material produces few byproducts, with only water produced. Furthermore, the use of a catalytic distillation reactor removes water during the reaction, facilitating a forward reaction, improving raw material conversion, and increasing product yield.

[0009] In the present invention, the molecular sieve catalyst is obtained by modifying an acidic mesoporous molecular sieve with an alkaline earth metal, and can form an acid-base synergistic catalytic center to catalyze the dehydration of N-hydroxyethylmorpholine to form bismorpholinyl diethyl ether.

[0010] The acidic mesoporous molecular sieve uses Al-modified silicon-based mesoporous molecular sieves because the traditional silicon-based mesoporous molecular sieves have fewer acidic centers on the pore wall surface and a large number of silanol groups on the pore wall, resulting in poor hydrothermal stability; fewer acidic centers lead to lower catalytic activity, and at the same time, the water released by the reaction of N-hydroxyethylmorpholine will destroy the molecular sieve structure with poor hydrothermal stability and reduce the life of the catalyst. 3+ The radius is And Si 4+ The radius is The radius of the two is relatively close. 3+ Replace Si 4+ When entering the framework of the mesoporous molecular sieve, in order to maintain the balance of electricity prices, Al3+ The hydroxyl groups will produce The addition of Al increases the polarity of the molecular sieve, making it easier to adsorb raw materials and improving hydrothermal stability. Methods for Al modification include, but are not limited to, direct synthesis and post-treatment.

[0011] The direct synthesis method involves directly mixing an Al-containing compound with other reactants required for the synthesis of silica-based mesoporous molecular sieves during the synthesis of silica-based mesoporous molecular sieves to carry out a silica-based mesoporous molecular sieve synthesis reaction, thereby introducing Al atoms into the framework of the silica-based mesoporous molecular sieve to form an acidic mesoporous molecular sieve. The post-treatment method involves reacting the synthesized pure silica mesoporous molecular sieve with an Al-containing compound under certain conditions, whereby Al atoms partially replace silicon atoms and enter the framework, thereby forming acidic centers.

[0012] The introduction of a mesoporous microporous acidic molecular sieve is due to the fact that traditional microporous acidic molecular sieves have small pore sizes, with the main pore size less than 1nm. However, the molecules of bismorpholinyl diethyl ether are large and highly polar. The microporous structure (<2nm) is not conducive to the diffusion of the product, resulting in an increase in by-products. Therefore, the introduction of a mesoporous structure is necessary. Methods for introducing a mesoporous structure into a microporous acidic molecular sieve include but are not limited to "constructive methods" and "destructive methods."

[0013] The "constructive method" refers to the synthesis of a microporous acidic molecular sieve containing a mesoporous structure by simultaneously adding a microporous template and a mesoporous template to react with other reactants required for the synthesis of the molecular sieve, or using a mesoporous molecular sieve as a silicon source. The "destructive method" refers to the formation of a mesoporous structure by selectively removing atoms from the molecular sieve framework. Specific methods include but are not limited to steam dealumination, acid dealumination, chelating agent dealumination, and alkali desiliconization.

[0014] If the mesoporous molecular sieve is a sodium or potassium type molecular sieve, an ammonium salt solution needs to be used to carry out an ion exchange reaction with the molecular sieve at 80-100°C until the alkali metal content of the molecular sieve is lower than 100PPM to obtain an acidic mesoporous molecular sieve.

[0015] While acidic catalysts can also catalyze the dehydration of N-hydroxyethylmorpholine to bismorpholinodiethyl ether, they produce a high number of byproducts, including 1,2-dimorpholinoethane and heavy components, resulting in a low selectivity for bismorpholinodiethyl ether. Furthermore, N-hydroxyethylmorpholine is weakly basic and adsorbs on acidic molecular sieves, requiring higher temperatures for desorption. The stronger the acidic center, the higher the desorption temperature. High temperatures not only exacerbate side reactions but also increase the rate of catalyst coking and shorten catalyst life. However, alkaline earth metal modification can cover most of the medium-strong acidic active sites in the mesoporous molecular sieve, reducing the acidity and creating basic catalytic sites. These sites, in conjunction with the acidic sites, synergistically catalyze the dehydration of N-hydroxyethylmorpholine. Once the reaction occurs, the reaction product, bismorpholinodiethyl ether, desorbs from the catalyst, reducing byproduct production and enabling selectivity for bismorpholinodiethyl ether to exceed 99 wt%. The reaction mechanism for the synergistic acid-base catalysis of N-hydroxyethylmorpholine to bismorpholinodiethyl ether is as follows:

[0016]

[0017] In the reaction formula, A represents the acidic center and B represents the basic center.

[0018] Furthermore, the reactor is a catalytic distillation reactor comprising a reaction section and a separation section located above the reaction section. The catalyst is loaded within the reaction section, and N-hydroxyethylmorpholine enters the reactor through the top of the reaction section. To ensure uniform feedstock distribution within the reactor, a feedstock distributor may be provided between the reaction section and the separation section. The separation section is in the form of trays. In a specific embodiment, the number of trays within the separation section may be selected between 10 and 20.

[0019] After N-hydroxyethylmorpholine enters the reaction section, it reacts under the corresponding temperature and pressure to generate bismorpholinyl diethyl ether. The reaction formula is as follows:

[0020]

[0021] During the reaction, N-hydroxyethylmorpholine and bismorpholinyl diethyl ether are both liquid and flow downward, while the generated water forms water vapor and flows upward into the separation section, where it is separated from the raw materials and product. This separation of water facilitates the forward reaction. Within the reaction section, the water content decreases from top to bottom, promoting an increase in the conversion rate of the raw materials. The N-hydroxyethylmorpholine and bismorpholinyl diethyl ether carried in the water vapor are separated and flow downward, returning to the reaction section, effectively separating the water generated by the reaction and ensuring that the discharged wastewater is free of N-hydroxyethylmorpholine and bismorpholinyl diethyl ether.

[0022] Compared with a reactor having only a reaction section, the catalytic distillation reactor improves the conversion rate of N-hydroxyethylmorpholine by more than 15 wt% and maintains the selectivity of bismorpholinyl diethyl ether by timely separating and treating the water produced during the reaction. In a conventional fixed-bed reactor, the conversion rate of N-hydroxyethylmorpholine is 82.5-83.9 wt% due to the inability to timely separate water, which affects the forward reaction. However, the catalytic distillation reactor achieves a conversion rate of 97.5-99.1 wt%, improving reaction efficiency, saving separation energy, and simultaneously increasing product yield to over 96.5 wt%.

[0023] The distillation tower in the present application is a tray tower, in which an upper tray group and a lower tray group are arranged, wherein the upper tray group is located above the lower tray group, and in the height direction, the material inlet of the distillation tower is located between the upper tray group and the lower tray group, wherein the upper tray group includes 10-20 layers of upper trays, and the lower tray group includes 10-20 layers of lower trays.

[0024] Specifically, to ensure that there are enough acidic centers and basic centers, and that the acidic centers and basic centers can perform synergistic catalysis, the molecular sieve catalyst contains 60-90wt% acidic mesoporous molecular sieve, 1-20wt% alkaline earth metal oxide, and 5-30wt% binder.

[0025] Specifically, to ensure that the catalyst has sufficient acidic active centers, the silicon-aluminum ratio of the acidic mesoporous molecular sieve is 20-50, and the alkali metal content is less than 100 PPM; in order to ensure smooth diffusion of the product in the catalyst, the specific surface area of the acidic mesoporous molecular sieve is 300-1200 m 2 / g, with an average pore size of 3-30nm. Furthermore, the average pore size of the acidic mesoporous molecular sieve is 4-10nm. Bismorpholino diethyl ether molecules are relatively large and weakly alkaline. A pore size that is too small is not conducive to product diffusion, causing the product to continue reacting and produce byproducts. A catalyst pore size that is too large reduces the possibility of the raw material contacting the catalyst's active centers, reducing the conversion rate.

[0026] Specifically, the alkaline earth metal is preferably Mg, Ca or Ba. When modifying the acidic mesoporous molecular sieve, the alkaline earth metal is specifically in the form of a metal salt solution.

[0027] Specifically, the alkaline earth metal is introduced by a kneading method, an equal amount impregnation method, or a multi-step impregnation method, wherein the alkaline earth metal is loaded on the acidic mesoporous molecular sieve, forming an acid-base synergistic catalysis with the acidic center of the catalyst to catalyze the dehydration of N-hydroxyethylmorpholine to form bismorpholinyl diethyl ether. The alkaline earth metal exists in the catalyst as an oxide.

[0028] The molecular sieve catalyst is prepared by the following two methods:

[0029] Method 1:

[0030] (1) Put the acidic mesoporous molecular sieve into a kneader and keep stirring. Add the alkaline earth metal salt solution dropwise into the kneader, then add the kneading agent into the kneader. After mixing evenly, add nitric acid solution and knead the materials into a colloid.

[0031] (2) The colloid is extruded into strips, dried at 90-150°C for 5-12 hours, and then calcined at 500-600°C for 3-6 hours to obtain a molecular sieve catalyst.

[0032] When the molecular sieve catalyst is prepared by this method, the concentration of the nitric acid solution is 8-12wt%.

[0033] Method 2:

[0034] (1) Put the binder and the acidic mesoporous molecular sieve into a kneader, mix them evenly, add nitric acid solution, and knead the materials into a colloid;

[0035] (2) Extruding the colloid into strips, drying at 90-150°C for 5-12 hours, and then calcining at 500-550°C for 3-6 hours to obtain molecular sieve strip particles;

[0036] (3) using an impregnation method to modify the molecular sieve strip particles using an alkaline earth metal salt solution to obtain modified particles;

[0037] (4) Drying at 90-150°C for 5-12 hours and then calcining at 500-600°C for 3-6 hours to obtain a molecular sieve catalyst.

[0038] When using this method to prepare a molecular sieve catalyst, the concentration of the nitric acid solution is 8-12 wt%, and the total mass of the alkaline earth metal salt solution is the product of the total mass of the molecular sieve strip particles and the water absorption rate of the molecular sieve strip particles. If a single impregnation cannot achieve the required catalyst content due to factors such as too high an alkaline earth metal content in the catalyst or too low solubility of the alkaline earth metal salt, a multiple impregnation method can be used, i.e., steps (3) and (4) of the method are repeated multiple times until the alkaline earth metal content in the catalyst reaches the required level.

[0039] Specifically, the binder is any one or at least two of aluminum oxide, silicon oxide, or zirconium oxide.

[0040] Specifically, in order to ensure the smooth progress of the reaction, the reaction temperature is 100-300°C, the reaction pressure is 0.1-1.0 MPa, and the mass space velocity of N-hydroxyethylmorpholine is 0.5-5h -1During the reaction, under the reaction pressure, the reaction temperature is higher than the boiling point of water and lower than the boiling points of N-hydroxyethylmorpholine and bismorpholinodiethyl ether.

[0041] Reaction temperature has a significant impact on the reaction. While high reaction temperatures are beneficial for the dehydration reaction, they can also cause further dehydration of bismorpholino diethyl ether to form vinylmorpholine, affecting product quality. Low reaction temperatures are also detrimental to the dehydration reaction, resulting in low N-hydroxyethylmorpholine conversion, low reaction efficiency, and increased separation energy consumption.

[0042] The main function of the reaction pressure is to maintain that N-hydroxyethylmorpholine and bismorpholinyl diethyl ether can both remain in the liquid phase and water is in the gas phase at the above reaction temperature, so that water can quickly leave the reaction zone, which is conducive to the forward progress of the reaction.

[0043] When the mass space velocity of N-hydroxyethylmorpholine is too high, the residence time of the raw material on the catalyst surface becomes shorter, the conversion rate decreases, and the separation energy consumption increases. When the mass space velocity is too low, the processing capacity decreases and the utilization rate of the catalyst and equipment decreases. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a flowchart of an embodiment of the present application.

[0045] Figure 2 It is a flowchart of another embodiment of the present application.

[0046] Figure 3 This is the BJH diagram of the H-type MCM36 molecular sieve prepared in Example 1.

[0047] Figure 4 This is the small-angle XRD pattern of the H-type MCM36 molecular sieve prepared in Example 1.

[0048] Figure 5 This is the BJH diagram of the mesoporous H-type β molecular sieve prepared in Example 2. DETAILED DESCRIPTION

[0049] In the following examples and comparative examples, the content of each component was analyzed by Shimadzu gas chromatography, and the conversion rate of N-hydroxyethylmorpholine was x HEM and bismorpholinyl diethyl ether S DMDEE Selectivity is calculated as follows:

[0050]

[0051] In the following examples and comparative examples, all N-hydroxyethylmorpholine used was purchased from Jiangsu Aikon Biopharmaceutical Research and Development Co., Ltd.

[0052] Example 1

[0053] The preparation steps of catalyst CHTD-1 are as follows:

[0054] 1. According to the literature of Zhang Ming et al. "Static Synthesis of MCM-22 and MCM-36 Molecular Sieves Using Piperidine as Template", H-type MCM36 molecular sieve was synthesized with a silicon-aluminum ratio of 34 and a specific surface area of 411.7 m 2 / g, average pore size 4.24nm, BJH diagram see Figure 3 , small angle XRD see Figure 4 .

[0055] 2. Add H-type MCM36 molecular sieve into the kneader.

[0056] 3. Select metallic calcium for kneading modification. The specific method is as follows: Calcium nitrate is prepared into a 50 wt% aqueous solution according to the amount of calcium added. The solution is slowly added dropwise to a kneader and kneaded with the H-type MCM36 molecular sieve for 0.5 hours. When adding the calcium nitrate aqueous solution, keep stirring to ensure that the calcium nitrate is added evenly.

[0057] 4. Alumina is selected as a binder and added to a kneader. After mixing evenly, a nitric acid solution with a concentration of 10 wt% is added to knead the material into a colloid. When adding the nitric acid solution, the material can be kneaded into a colloid.

[0058] 5. The colloid was extruded into strips, dried at 110°C for 8 hours, and calcined at 550°C for 4 hours to obtain catalyst CHTD-1.

[0059] The catalyst CHTD-1 contains 73 wt% of H-type MCM36 molecular sieve, 7 wt% of calcium oxide, and 20 wt% of binder.

[0060] Example 2

[0061] Preparation of catalyst CHTD-2. This embodiment is basically the same as Example 1, except that the silicon-aluminum ratio of the H-type MCM36 molecular sieve is 21; barium nitrate is used for modification; after the colloid is extruded, it is dried at 90°C for 11 hours and calcined at 510°C for 6 hours to obtain catalyst CHTD-2.

[0062] The catalyst CHTD-2 contains 65 wt% of H-type MCM36 molecular sieve, 12 wt% of barium oxide, and 23 wt% of a binder.

[0063] Example 3

[0064] Preparation of catalyst CHTD-3: This embodiment is basically the same as embodiment 1, except that the silicon-aluminum ratio of the H-type MCM36 molecular sieve is 45; after the colloid is extruded, it is dried at 135°C for 6 hours and calcined at 600°C for 3 hours to obtain catalyst CHTD-3.

[0065] The catalyst CHTD-3 contains 76 wt% of H-type MCM36 molecular sieve, 16 wt% of calcium oxide, and 8 wt% of binder.

[0066] Example 4

[0067] Preparation of catalyst CHTD-4: 1. After dealuminizing H-type β molecular sieve with 800°C steam for 4 hours, dealuminizing with 10wt% nitric acid at 80°C for 2 hours, and then washing with water. After washing to neutrality, the dealuminized molecular sieve is dried at 110°C for 8 hours and then calcined at 500°C for 4 hours to prepare a mesoporous H-type β molecular sieve with a silicon-aluminum ratio of 28 and a specific surface area of 881.4m 2 / g, average pore size 4.78nm, BJH diagram please refer to Figure 5 The above-mentioned H-type β molecular sieve was purchased from Tianjin Shenneng Technology Co., Ltd.

[0068] 2. Alumina is selected as a binder and added to a mesoporous H-type β molecular sieve at a mass ratio of 2:8. The mixture is added into a kneader and mixed evenly. An appropriate amount of 10 wt% nitric acid is then added to knead the material into a colloid.

[0069] 3. Extrude the colloid into strips, dry at 110°C for 8 hours, and then calcine at 500°C for 4 hours to obtain molecular sieve strip particles;

[0070] 4. Select metallic magnesium for modification by the impregnation method. The specific method is: prepare magnesium nitrate calculated based on the amount of magnesium added into a 30wt% aqueous solution. The total mass of the magnesium nitrate solution is the product of the total mass of the molecular sieve strip particles and the water absorption rate of the molecular sieve strip particles. Place the molecular sieve strip particles in a rotary evaporator and add the magnesium nitrate solution dropwise while rotating. After the addition is completed, continue rotating for 3 hours to obtain modified particles.

[0071] 5. The modified particles were dried at 110°C for 8 hours and then calcined at 550°C for 4 hours to obtain catalyst CHTD-4.

[0072] The catalyst CHTD-4 contains 76 wt% of mesoporous H-type beta molecular sieve, 5 wt% of magnesium oxide, and 19 wt% of a binder.

[0073] Example 5

[0074] Preparation of catalyst CHTD-5: This embodiment is basically the same as embodiment 4, except that catalyst CHTD-5 contains 64 wt% of mesoporous H-type β molecular sieve, 20 wt% of magnesium oxide, and 16 wt% of binder.

[0075] Comparative Example 1

[0076] The preparation of catalyst DHTD-1 is as follows:

[0077] Catalyst DHTD-1 was produced according to patent US4095022. The silica carrier was provided by Aote Chemical Catalyst Carrier Research Institute in Jiangyan City, Jiangsu Province. The specific surface area was 352m 2 / g. The phosphoric acid impregnation amount was 30wt%, and the impregnation method was an equal amount impregnation method. Specifically, an aqueous solution was prepared according to the amount of phosphoric acid added. The total mass of the phosphoric acid solution was the product of the total mass of the silica support and the water absorption rate of the silica support. The silica support was placed in a rotary evaporator and the phosphoric acid solution was added dropwise while rotating. After the addition was completed, the silica support was rotated for 3 hours. The catalyst was then dried at 110°C for 8 hours and calcined at 550°C for 4 hours to obtain the catalyst DHTD-1.

[0078] Example 6

[0079] This example is the production of bismorpholinyl diethyl ether. The production process is first described below. Figure 1 During production, the raw material, N-hydroxyethylmorpholine, is first heated along the first feed pipe 111 through the refrigerant passage of the first heat exchanger 14, then heated in the first heating furnace 11, and then enters the raw material distributor 123 through the feed port 124. The catalytic distillation reactor 12 includes a reaction section 121 and a separation section 122 located above the reaction section 121. The raw material distributor 123 is located between the reaction section 121 and the separation section 122. The feed port 124 of the catalytic distillation reactor 12 is connected to the raw material distributor 123, and the catalyst is loaded into the reaction section. The separation section is equipped with tower trays. In this embodiment, 10 tower trays are installed in the separation section. The reaction section is a fixed bed.

[0080] After exiting the feed distributor 123, N-hydroxyethylmorpholine flows downward into the reaction zone for reaction. Specifically, N-hydroxyethylmorpholine enters the reactor via the top of the reaction zone and, under the action of the catalyst, reacts to produce bismorpholinyl diethyl ether and water. The water forms steam and flows upward into the separation zone 122. Within the separation zone, the N-hydroxyethylmorpholine and bismorpholinyl diethyl ether carried by the steam flow downward and return to the reaction zone due to separation by the tower trays. The steam exiting the top of the catalytic distillation reactor is cooled in the first air cooler 15 and then discharged into the wastewater treatment system.

[0081] The mixture of N-hydroxyethylmorpholine and bismorpholinyl diethyl ether discharged from the bottom of the catalytic distillation reactor 12 enters the first distillation tower 13. In the first distillation tower 13, the gas phase flows upward and the liquid phase flows downward. Since the boiling point of N-hydroxyethylmorpholine is lower than that of bismorpholinyl diethyl ether, the gas phase is N-hydroxyethylmorpholine gas mixed with bismorpholinyl diethyl ether, and the main component of the liquid phase is bismorpholinyl diethyl ether mixed with a small amount of N-hydroxyethylmorpholine. The bottom material of the first distillation tower 13 enters the first reboiler 134 for heating.

[0082] The temperature within the first reboiler is higher than the boiling point of N-hydroxyethylmorpholine and lower than the boiling point of bismorpholinyl diethyl ether. The vapor phase within the first reboiler is discharged through the top of the first reboiler and then returns to the bottom of the first distillation column, flowing upward. A first material pump 135 is connected to the bottom of the first reboiler. The liquid phase within the first reboiler is cooled by the first material pump 135 through the heat medium passage of the first heat exchanger 14 and the first cooler 16 before being discharged as a product.

[0083] The gas phase discharged from the top of the first distillation tower 13 is condensed in the second air cooler 131 and then enters the first reflux tank 132. The bottom of the first reflux tank is connected to the inlet of the first circulation pump 133. The outlet of the first circulation pump leads to two branch pipes, namely a first branch pipe 143 and a second branch pipe 144. The first branch pipe 143 is connected to the upper part of the first distillation tower 13, and the second branch pipe 144 is connected to the first feed pipe 111. The connection point between the second branch pipe 144 and the first feed pipe 111 is located between the first heat exchanger and the first heating furnace. Driven by the first circulation pump, a portion of the liquid in the first reflux tank 132 returns to the upper part of the first distillation tower 13 through the first branch pipe, and the other portion of the liquid enters the first feed pipe through the second branch pipe, mixes with the raw materials, and after being heated in the first heating furnace, enters the catalytic distillation reactor for recycling and continues to participate in the reaction.

[0084] In this embodiment, the first distillation tower 13 is a tray tower. An upper tray assembly 138 and a lower tray assembly 139 are provided within the first distillation tower 13. The upper tray assembly 138 is located above the lower tray assembly 139. A first material inlet 137 of the first distillation tower is located vertically between the upper tray assembly 138 and the lower tray assembly 139. The upper tray assembly 138 includes 15 layers of upper trays, and the lower tray assembly 139 includes 15 layers of lower trays. The mixture of N-hydroxyethylmorpholine and bismorpholinyl diethyl ether discharged from the bottom of the catalytic distillation reactor 12 enters the first distillation tower 13 through the first material inlet 137.

[0085] In this embodiment, the catalyst in the reaction zone is the catalyst CHTD-1 prepared in Example 1, and the reaction conditions in the reaction zone are: reaction temperature 180°C, reaction pressure 0.2 MPa, mass space velocity of N-hydroxyethylmorpholine 3.0 h -1 The obtained product was analyzed by gas chromatography, and the analysis results are shown in Table 1.

[0086] Example 7

[0087] The production apparatus and process of this embodiment are basically the same as those of Example 6. The difference is that in this embodiment, the catalyst in the reaction section adopts the catalyst CHTD-2 prepared in Example 2, and the reaction conditions in the reaction section are: reaction temperature 110°C, reaction pressure 0.1 MPa, mass space velocity of N-hydroxyethylmorpholine 0.6h -1 The obtained product was analyzed by gas chromatography, and the analysis results are shown in Table 1.

[0088] Example 8

[0089] The production apparatus and process of this embodiment are basically the same as those of Example 6. The difference is that in this embodiment, the catalyst in the reaction section adopts the catalyst CHTD-3 prepared in Example 3, and the reaction conditions in the reaction section are: reaction temperature 210°C, reaction pressure 0.8 MPa, mass space velocity of N-hydroxyethylmorpholine 3.5h -1 The obtained product was analyzed by gas chromatography, and the analysis results are shown in Table 1.

[0090] Example 9

[0091] The production apparatus and process of this embodiment are basically the same as those of Example 6. The difference is that the catalyst used is the catalyst CHTD-4 prepared in Example 4, and the reaction conditions are: temperature 260°C, pressure 1.0 MPa, mass space velocity of N-hydroxyethylmorpholine 2.5h -1 The obtained product was analyzed by gas chromatography, and the analysis results are shown in Table 1.

[0092] Example 10

[0093] The production apparatus and process of this embodiment are basically the same as those of Example 6. The difference is that the catalyst used is the catalyst CHTD-5 prepared in Example 5. The reaction conditions are: temperature 280°C, pressure 0.9 MPa, mass space velocity of N-hydroxyethylmorpholine 4.1h -1 The obtained product was analyzed by gas chromatography, and the analysis results are shown in Table 1.

[0094] Example 11

[0095] The production process of this embodiment is quite different from that of embodiment 6. The production process of this embodiment is first described below. Figure 2 During production, N-hydroxyethylmorpholine as a raw material is first heated through the refrigerant channel of the second heat exchanger 24 along the second feed pipe 211, then heated through the second heating furnace 21, and then enters the fixed bed reactor 22 through the top of the fixed bed reactor 22. In this embodiment, the fixed bed reactor 22 only has a reaction section and no separation section is provided. The catalyst is loaded in the fixed bed reactor.

[0096] Under the action of the catalyst, N-hydroxyethylmorpholine reacts to produce bismorpholinyl diethyl ether and water. The unreacted N-hydroxyethylmorpholine and the reaction mixture formed by bismorpholinyl diethyl ether and water are discharged from the bottom of the fixed bed reactor and enter the second distillation tower 23. The second distillation tower 23 has the same structure as the first distillation tower 13.

[0097] The bottoms from the second distillation column enter the second reboiler 234 for heating. The temperature within the second reboiler is higher than the boiling point of N-hydroxyethylmorpholine and lower than the boiling point of bismorpholinyl diethyl ether. The vapor in the second reboiler 234 is discharged from the top of the second reboiler and then returns to the bottom of the second distillation column, flowing upward. A second material pump 235 is connected to the bottom of the second reboiler. The liquid in the second reboiler is cooled by the second material pump 235 through the heat medium channel of the second heat exchanger 24 and the second cooler 26 before being discharged as a product.

[0098] The gaseous phase discharged from the top of the second distillation tower 23 is condensed in the third air cooler 231 and then enters the second reflux drum 232. The material in the second reflux drum 232 is split into two streams. One stream is returned to the second distillation tower 23 through the top of the second distillation tower 23 by the second circulation pump 233, while the other stream is discharged as wastewater and enters the wastewater system. A side line 238 is drawn from the top of the second distillation tower 23. This side line 238 is connected to the second feed pipe 211. The connection point between the side line 238 and the second feed pipe 211 is located between the second heat exchanger and the second heating furnace. A portion of the material from the top of the second distillation tower 23 is withdrawn as recycle material. After mixing with the raw materials, the recycle material is returned to the fixed bed reactor 22 through the second heating furnace 21 for further reaction and recycling. The connection point of the side line 238 on the second distillation tower 23 is directly above the upper tray assembly of the second distillation tower 23.

[0099] The reaction mixture of N-hydroxyethylmorpholine, water and dimorpholinyl diethyl ether discharged from the bottom of the fixed bed reactor 22 enters the second distillation tower 23 through the second material inlet 237. The position of the second material inlet on the second distillation tower is the same as the position of the first material inlet on the first distillation tower.

[0100] In this embodiment, the catalyst in the fixed bed reactor is the catalyst CHTD-1 prepared in Example 1. The reaction conditions are: temperature 180°C, pressure 0.2 MPa, mass space velocity of N-hydroxyethylmorpholine 3.0 h -1 The obtained product was analyzed by gas chromatography, and the analysis results are shown in Table 1.

[0101] Comparative Example 2

[0102] The experimental apparatus and process of Comparative Example 2 are the same as those of Example 3, except that the catalyst used is the catalyst DHTD-1 prepared in Comparative Example 1, and the reaction conditions are: temperature 260°C, pressure 1.0 MPa, mass space velocity of N-hydroxyethylmorpholine 2.5 h -1 The obtained product was analyzed by gas chromatography, and the analysis results are shown in Table 1.

[0103] Table 1 Analysis results

[0104]

[0105] As can be seen from Table 1, compared with the prior art, the use of a simple fixed-bed reactor can effectively improve the conversion rate of N-hydroxyethylmorpholine and the selectivity of bismorpholinyl diethyl ether. Moreover, after adopting a catalytic distillation reactor, compared with a simple fixed-bed reactor, the yield of bismorpholinyl diethyl ether can be effectively increased by more than 15wt%. Because the catalytic distillation reactor form adopted can effectively remove the water produced during the reaction stage, the influence of water on the reaction is eliminated, the forward direction of the N-hydroxyethylmorpholine dehydration reaction is promoted, and the reaction efficiency is improved. At the same time, the molecular sieve catalyst used in the present invention catalyzes the dehydration through the acid-base active center, avoids the by-products produced by the acid center, and improves the conversion rate and selectivity.

Claims

1. A method for producing bismorpholinyl diethyl ether, characterized in that: The method uses a molecular sieve catalyst as a catalyst, feeds N-hydroxyethylmorpholine as a raw material into a reactor for reaction, discharges water generated by the reaction from the top of the reactor and enters a cooling device for cooling, feeds discharged from the bottom of the reactor enter a distillation tower, unreacted N-hydroxyethylmorpholine separated from the distillation tower enters the reactor for recycling, and the bottom material at the bottom of the distillation tower is used as the product bismorpholinyl diethyl ether; in the reactor, the reaction temperature is 100-300°C, the reaction pressure is 0.1-1.0 MPa, and the mass space velocity of N-hydroxyethylmorpholine is 0.5-5h -1 ; Molecular sieve catalysts are obtained by modifying acidic mesoporous molecular sieves with alkaline earth metals; The acidic mesoporous molecular sieve is an acidic molecular sieve containing a mesoporous structure of 2-50 nm, and the acidic mesoporous molecular sieve is selected from a silicon-based mesoporous molecular sieve modified with Al, a microporous acidic molecular sieve introduced with a mesoporous structure, and an acidic molecular sieve containing a mesoporous structure itself; the alkaline earth metal is Mg, Ca or Ba, and the alkaline earth metal is introduced by any one of a kneading method, an equal amount impregnation method or a multi-step impregnation method.

2. The production method according to claim 1, characterized in that The reactor is a catalytic distillation reactor, which includes a reaction section and a separation section located above the reaction section. The catalyst is loaded in the reaction section, and N-hydroxyethylmorpholine enters the reactor through the top of the reaction section.

3. The production method according to claim 1, characterized in that The molecular sieve catalyst contains 60-90 wt% of acidic mesoporous molecular sieve, 1-20 wt% of alkaline earth metal oxide, and 5-30 wt% of binder.

4. The production method according to claim 1, characterized in that The silicon-aluminum ratio of acidic mesoporous molecular sieve is 20-50, the alkali metal content is less than 100PPM, and the specific surface area is 300-1200m 2 / g, and the average pore size is 3-30nm.

5. The production method according to claim 1, characterized in that The molecular sieve catalyst is prepared by the following two methods: Method 1: (1) Put the acidic mesoporous molecular sieve into a kneader and keep stirring. Add the alkaline earth metal salt solution dropwise into the kneader, then add the kneading agent into the kneader. After mixing evenly, add nitric acid solution and knead the materials into a colloid. (2) Extruding the colloid into strips, drying at 90-150°C for 5-12 hours, and then calcining at 500-600°C for 3-6 hours to obtain a molecular sieve catalyst; Method 2: (1) Put the binder and the acidic mesoporous molecular sieve into a kneader, mix them evenly, add nitric acid solution, and knead the materials into a colloid; (2) Extruding the colloid into strips, drying at 90-150°C for 5-12 hours, and then calcining at 500-550°C for 3-6 hours to obtain molecular sieve strip particles; (3) using an impregnation method to modify the molecular sieve strip particles using an alkaline earth metal salt solution to obtain modified particles; (4) Drying at 90-150°C for 5-12 hours and then calcining at 500-600°C for 3-6 hours to obtain a molecular sieve catalyst.

6. The production method according to claim 5, characterized in that The binder is any one or at least two of aluminum oxide, silicon oxide, or zirconium oxide.

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