CN117186029A

CN117186029A - Production method of dimorpholinodiethyl ether

Info

Publication number: CN117186029A
Application number: CN202311163147.8A
Authority: CN
Inventors: 陈鉴; 解委托; 代训达; 田爱玲; 常二辉
Original assignee: Nanjing Kemisicui New Energy Technology Co ltd
Current assignee: Nanjing Kemisicui New Energy Technology Co ltd
Priority date: 2023-09-11
Filing date: 2023-09-11
Publication date: 2023-12-08

Abstract

The application discloses a production method of dimorpholinodiethyl ether, which takes a molecular sieve catalyst as a catalyst, raw material N-hydroxyethyl morpholine enters a reactor for reaction, moisture generated by the reaction is discharged from the top of the reactor and then enters a cooling device for cooling, materials discharged from the bottom of the reactor enter a rectifying tower, unreacted N-hydroxyethyl morpholine separated from the rectifying tower enters the reactor for recycling, and tower bottom materials at the bottom of the rectifying tower are used as dimorpholinodiethyl ether products; the molecular sieve type catalyst is obtained by modifying an acidic mesoporous molecular sieve by alkaline earth metal. The application can make the conversion rate of N-hydroxyethyl morpholine reach 97.5-99.1wt%, raise the reaction efficiency, save separation energy consumption and raise the product yield.

Description

Production method of dimorpholinodiethyl ether

Technical Field

The application relates to a method for producing dimorpholinodiethyl ether.

Background

Dimorpholinodiethyl ether (DMDEE) of formula C ₁₂ H ₂₄ N ₂ O ₃ The catalyst is a strong foaming catalyst, is colorless to pale yellow liquid in appearance, is dissolved in water, and is an amine catalyst suitable for a water curing system. The steric effect of the amino groups can lead the NCO-containing component to have a long storage period, and is mainly used for a single-component rigid polyurethane foam system, and also can be used for polyether type and polyester type polyurethane soft foam, semi-rigid foam, CASE materials and the like. DMDEE is one of three polyurethane catalysts, and limited domestic production capacity mainly depends on import.

The synthesis method of the dimorpholinodiethyl ether is various, but the large-scale industrial production is truly realized at present, and the synthesis method mainly comprises the following two steps: (1) Diethylene glycol and ammonia react under high temperature and high pressure in the presence of hydrogen and a metal catalyst to obtain dimorpholinodiethyl ether; (2) Diethylene glycol and morpholine react under high temperature and high pressure in the presence of hydrogen and metallic catalyst copper or cobalt to obtain dimorpholinyldiethyl ether. The two synthetic routes adopt metal as a catalyst, and the reaction is generally carried out at high temperature and high pressure in gas phase, so that the method has the defects of high production cost, difficult operation, difficult product separation and the like.

Besides, zheng Xueming discloses a process which uses dichlorodiethyl ether and morpholine as raw materials and uses sodium hydroxide for post-treatment, and the process can produce a large amount of sodium chloride as a byproduct, has large wastewater volume, is difficult to treat and has serious corrosion to equipment. Patent US4095022 discloses a process for preparing DMDEE, which comprises reacting N-hydroxyethyl morpholine as raw material and phosphorus-containing material as catalyst at 240-280 ℃. The method needs to react at high temperature, has the generation of phosphorus-containing waste liquid, and is not friendly to the environment. Patent CN201910358412 discloses a method for preparing DMDEE by using Triethanolamine (TEOA) and concentrated sulfuric acid as raw materials and carrying out etherification, neutralization and rectification. But the method has lower product yield, and the concentrated sulfuric acid is strong acid and has higher equipment requirement.

The byproduct of synthesizing the dimorpholinodiethyl ether by using the N-hydroxyethyl morpholine as a raw material is mainly water, the selectivity is good, but the fixed bed reactor and the catalyst adopted by the method at presentIs active alumina, siO ₂ -Al ₂ O ₃ Or SiO loaded with phosphorus-containing compounds ₂ The product yield is lower, generally only 16.2-56.6wt percent can be achieved, the industrialization level can not be achieved, and improvement is highly needed.

Disclosure of Invention

In order to improve the product yield of the dimorpholinodiethyl ether, the application provides a production method of the dimorpholinodiethyl ether, which takes a molecular sieve catalyst as a catalyst, raw material N-hydroxyethyl morpholine enters a reactor for reaction, moisture generated by the reaction is discharged from the top of the reactor and then enters a cooling device for cooling, materials discharged from the bottom of the reactor enter a rectifying tower, unreacted N-hydroxyethyl morpholine separated from the rectifying tower enters the reactor for recycling, and tower bottom materials at the bottom of the rectifying tower are used as the dimorpholinodiethyl ether product; the molecular sieve type catalyst is obtained by modifying an acidic mesoporous molecular sieve by alkaline earth metal.

Specifically, the acidic mesoporous molecular sieve is an acidic molecular sieve containing a mesoporous structure of 2-50nm, and comprises a silicon-based mesoporous molecular sieve modified by Al, a microporous acidic molecular sieve with a mesoporous structure introduced, and an acidic molecular sieve with a mesoporous structure. Wherein the Al modified silicon-based mesoporous molecular sieve comprises M41S series, SBA-n series, MSU series, CMK series, HMS or KIT and the like; the microporous acid molecular sieve with the mesoporous structure comprises a mesoporous Y-type molecular sieve, a mesoporous ZSM-5 molecular sieve, a mesoporous beta molecular sieve and the like; the acidic molecular sieve itself containing a mesoporous structure includes MCM-36.

The method is different from the existing method for preparing the dimorpholinodiethyl ether in that: the molecular sieve type catalyst has higher activity, high product yield, no corrosion to equipment, mild reaction conditions and less equipment investment; n-hydroxyethyl morpholine is used as a raw material, byproducts are fewer, and only water can be produced. The catalytic distillation reactor is adopted, so that the water can be removed in the reaction process, the forward reaction is facilitated, the raw material conversion rate is improved, and the product yield is improved.

In the application, the molecular sieve catalyst is obtained by modifying an acidic mesoporous molecular sieve through alkaline earth metal, and can form an acid-base synergistic catalytic center to catalyze N-hydroxyethyl morpholine to dehydrate to form dimorpholinodiethyl ether.

The acidic mesoporous molecular sieve adopts the Al modified silicon-based mesoporous molecular sieve, because the acidic center of the surface of the pore wall of the traditional silicon-based mesoporous molecular sieve is less, and a large number of silicon hydroxyl groups are arranged on the pore wall, so that the hydrothermal stability of the traditional silicon-based mesoporous molecular sieve is poor; the acidic center is less, so that the catalytic activity is lower, and meanwhile, the water removed by the reaction of the N-hydroxyethyl morpholine can damage the molecular sieve structure with poor hydrothermal stability, so that the service life of the catalyst is reduced. Al (Al) ³⁺ Radius of (2) isAnd Si is ⁴⁺ Is +.>The radius of the two is similar, when Al ³⁺ Substituted Si ⁴⁺ When entering the framework of the mesoporous molecular sieve, al is used for maintaining the balance of electricity price ³⁺ Will generate hydroxyl groups of (2)Acid centers, thereby enhancing the acidity of the material. Meanwhile, the polarity of the molecular sieve is increased by introducing Al, raw materials are easier to adsorb, and the hydrothermal stability is also increased. Methods of Al modification include, but are not limited to, "direct synthesis" and "post-treatment".

The direct synthesis method is characterized in that in the process of synthesizing the silicon-based mesoporous molecular sieve, an Al-containing compound and other reactants required by synthesizing the silicon-based mesoporous molecular sieve are directly mixed to carry out the synthesis reaction of the silicon-based mesoporous molecular sieve, so that Al atoms can be introduced into the framework of the silicon-based mesoporous molecular sieve to form the acidic mesoporous molecular sieve. The post-treatment method is to react the synthesized pure silicon oxide mesoporous molecular sieve with an Al-containing compound under a certain condition, wherein Al atoms partially replace silicon atoms and enter a framework, so that an acidic center is formed.

The microporous acid molecular sieve with the mesoporous structure is introduced, because the traditional microporous acid molecular sieve has smaller aperture, main aperture is smaller than 1nm, and the dimorpholinodiethyl ether has larger molecules and stronger polarity, and the microporous (< 2 nm) structure is unfavorable for the diffusion of the product, so that byproducts are increased, and therefore, the mesoporous structure needs to be introduced. Methods for introducing the microporous acidic molecular sieve into the mesoporous structure include, but are not limited to, "constructive methods" and "destructive methods".

The constructive method is to synthesize microporous acid molecular sieve with mesoporous molecular sieve as silicon source and through adding microporous template agent and mesoporous template agent to react with other reactant to synthesize molecular sieve. The "destructive method" refers to a method that the microporous acid molecular sieve forms a mesoporous structure by selectively removing molecular sieve framework atoms, and specific methods include, but are not limited to, steam treatment dealumination, acid treatment dealumination, chelating agent dealumination, alkali treatment desilication and the like.

If the mesoporous molecular sieve is a sodium type or potassium type molecular sieve, an ammonium salt solution and the molecular sieve are required to carry out ion exchange reaction at 80-100 ℃ until the alkali metal content of the molecular sieve is lower than 100PPM, and the acidic mesoporous molecular sieve is obtained.

The acidic catalyst can also catalyze the dehydration of N-hydroxyethyl morpholine to form dimorpholinodiethyl ether, but the byproduct is more, 1, 2-dimorpholinoethane, recombination and other byproducts can be generated, and the selectivity of dimorpholinodiethyl ether is lower; meanwhile, the N-hydroxyethyl morpholine is slightly alkaline and can be adsorbed on an acidic molecular sieve, the desorption needs a higher temperature, and the stronger the acid strength of the acidic center is, the higher the desorption temperature is. The high temperature not only can aggravate the occurrence of side reaction, but also can increase the carbon deposition rate of the catalyst and shorten the service life of the catalyst. The alkaline earth metal modification can cover most of strong acid active centers in the mesoporous molecular sieve, so that the acidity of the molecular sieve is reduced, an alkaline catalytic center is generated, the alkaline catalytic center and the acidic center of the molecular sieve are used for synergetically catalyzing the dehydration of N-hydroxyethyl morpholine, once the reaction occurs, the reaction product dimorpholinodiethyl ether is desorbed from the catalyst, the generation of byproducts is reduced, and the dimorpholinodiethyl ether selectivity can reach more than 99 wt%. The reaction mechanism of acid-base synergistic catalysis of N-hydroxyethyl morpholine to produce dimorpholinodiethyl ether is as follows:

in the reaction formula, A represents an acidic center, and B represents a basic center.

Further, the reactor is a catalytic distillation reactor, the catalytic distillation reactor comprises a reaction section and a separation section positioned on the upper side of the reaction section, a catalyst is filled in the reaction section, and N-hydroxyethyl morpholine enters the reactor from the top of the reaction section. In order to allow the raw materials to enter the reactor uniformly, a raw material distributor may be provided between the reaction section and the separation section. The separation section takes the form of trays, and in particular embodiments the number of trays within the separation section may be selected between 10 and 20.

After entering a reaction section, N-hydroxyethyl morpholine reacts at corresponding temperature and pressure to generate dimorpholinodiethyl ether, wherein the reaction formula is as follows:

in the reaction process, the N-hydroxyethyl morpholine and the dimorpholinodiethyl ether are in liquid state and flow downwards, the generated water is formed into water vapor, and the water flows upwards to enter the separation section to be separated from raw materials and products, and the separation of the water is beneficial to the forward reaction. The water content in the reaction section is lower from top to bottom, so that the conversion rate of the raw materials is promoted to be increased. The N-hydroxyethyl morpholine and the dimorpholinodiethyl ether carried in the water vapor can be separated, flow downwards and return to the reaction section, and the water generated by the reaction is effectively separated, so that the discharged wastewater does not carry the N-hydroxyethyl morpholine and the dimorpholinodiethyl ether.

Compared with a reactor only provided with a reaction section, the catalytic distillation reactor is adopted, and the water produced by the reaction can be separated and treated in time in the reaction process, so that the conversion rate of N-hydroxyethyl morpholine can be improved by more than 15wt%, and the selectivity of dimorpholinodiethyl ether is kept unchanged. The conventional fixed bed reactor is adopted, so that water cannot be separated in time, the forward reaction is affected, and the conversion rate of the N-hydroxyethyl morpholine is 82.5-83.9wt%; after the catalytic distillation reactor is adopted, the conversion rate of the N-hydroxyethyl morpholine is 97.5-99.1wt%, the reaction efficiency is improved, the separation energy consumption is saved, the product yield is improved, and the product yield can reach more than 96.5 wt%.

The rectifying tower is a tray tower, an upper tray group and a lower tray group are arranged in the rectifying tower, wherein the upper tray group is positioned above the lower tray group, and a material inlet of the rectifying tower is positioned between the upper tray group and the lower tray group in the height direction, wherein the upper tray group comprises 10-20 layers of upper trays, and the lower tray group comprises 10-20 layers of lower trays.

Specifically, in order to ensure that sufficient acid centers and alkali centers are available and that the acid centers and the alkali centers can be co-catalyzed, the molecular sieve-type catalyst comprises 60 to 90wt% of an acidic mesoporous molecular sieve, 1 to 20wt% of an alkaline earth metal oxide and 5 to 30wt% of a binder.

Specifically, in order to ensure that the catalyst has enough acid active centers, the silicon-aluminum ratio of the acid mesoporous molecular sieve is 20-50, and the alkali metal content is less than 100PPM; in order to ensure the smooth diffusion of the product in the catalyst, the specific surface area of the acidic mesoporous molecular sieve is 300-1200m ² And/g, the average pore diameter is 3-30nm. Further, the average pore diameter of the acidic mesoporous molecular sieve is 4-10nm. The dimorpholinodiethyl ether has larger molecules and weak alkalinity, and the aperture is too small to be beneficial to the diffusion of the product, so that the product continues to react to generate byproducts; if the catalyst pore diameter is too large, the possibility of the raw material contacting the active center of the catalyst is reduced, and the conversion rate is lowered.

Specifically, the alkaline earth metal is preferably Mg, ca or Ba. When the acidic mesoporous molecular sieve is modified, the alkaline earth metal is specifically in the form of a metal salt solution.

Specifically, the introduction mode of the alkaline earth metal comprises any one of a kneading method, an equivalent impregnation method or a multi-step impregnation method, so that the alkaline earth metal is loaded on the acidic mesoporous molecular sieve, acid-base synergistic catalysis is formed with the acidic center of the catalyst, and dehydration of the N-hydroxyethyl morpholine is catalyzed to form the dimorpholinodiethyl ether. The alkaline earth metal is present in the catalyst in the form of an oxide.

Wherein, the molecular sieve type catalyst is prepared by the following two methods:

the method comprises the following steps:

(1) Adding an acidic mesoporous molecular sieve into a kneader, keeping stirring, dripping alkaline earth metal salt solution into the kneader, adding a kneading agent into the kneader, uniformly mixing, adding a nitric acid solution, and kneading the materials into colloid;

(2) The colloid is extruded and shaped, dried for 5 to 12 hours at the temperature of 90 to 150 ℃, and then baked for 3 to 6 hours at the temperature of 500 to 600 ℃ to obtain the molecular sieve type catalyst.

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

The second method is as follows:

(1) Adding the binder and the acidic mesoporous molecular sieve into a kneader, uniformly mixing, adding a nitric acid solution, and kneading the materials into colloid;

(2) Extruding the colloid to form, drying at 90-150 deg.c for 5-12 hr, and roasting at 500-550 deg.c for 3-6 hr to obtain molecular sieve strip particle;

(3) Modifying the molecular sieve strip particles by adopting an impregnation method, and modifying the molecular sieve strip particles by using alkaline earth metal salt solution to obtain modified particles;

(4) Drying at 90-150 deg.c for 5-12 hr, and roasting at 500-600 deg.c for 3-6 hr to obtain molecular sieve catalyst.

When the molecular sieve type catalyst is prepared by adopting the method, the concentration of the nitric acid solution is 8-12wt%, 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 the content of alkaline earth metal in the catalyst is too high or the solubility of alkaline earth metal salt is too low, the content of alkaline earth metal in the catalyst cannot reach the content required by the catalyst by one-time impregnation, the impregnation method can be adopted for multiple times, namely, the step (3) and the step (4) in the method are repeatedly adopted for multiple times until the content of alkaline earth metal in the catalyst reaches the requirement.

Specifically, the binder is any one or at least two of alumina, silica or zirconia.

Specifically, in the reactor, the reaction temperature is 100-300 ℃, the reaction pressure is 0.1-1.0MPa, and the mass space velocity of N-hydroxyethyl morpholine is 0.5-5h to ensure the smooth progress of the reaction ^-1 . During the reaction, at the reaction pressure, the reaction temperature is higher than the boiling point temperature of water and lower than the boiling points of N-hydroxyethyl morpholine and dimorpholinodiethyl ether.

The reaction temperature has a larger influence on the reaction, and is too high, so that the dehydration reaction is facilitated, but when the reaction temperature is too high, the dimorpholinodiethyl ether can be continuously dehydrated to generate vinyl morpholine, and the product quality is influenced. When the reaction temperature is too low, the dehydration reaction is not facilitated, the conversion rate of N-hydroxyethyl morpholine is low, the reaction efficiency is low, and the separation energy consumption is increased.

The main function of the reaction pressure is to keep the N-hydroxyethyl morpholine and the dimorpholinodiethyl ether in liquid phase at the reaction temperature, and the water is in gas phase, so that the water can leave the reaction section rapidly, which is beneficial to the forward progress of the reaction.

When the mass space velocity of the N-hydroxyethyl morpholine is too high, the residence time of the raw material on the surface of the catalyst is shortened, the conversion rate is reduced, and the separation energy consumption is increased. When the mass space velocity is too low, the throughput decreases, and the utilization of the catalyst and the equipment decreases.

Drawings

FIG. 1 is a flow chart of an embodiment of the present application.

FIG. 2 is a flow chart of another embodiment of the present application.

FIG. 3 is a BJH diagram of an H-type MCM36 molecular sieve prepared in example 1.

Fig. 4 is a small angle XRD pattern of the H-type MCM36 molecular sieve prepared in example 1.

Fig. 5 is a BJH diagram of the mesoporous H-type beta molecular sieve prepared in example 2.

Detailed Description

In the following examples and comparative examples, the contents of the components were analyzed by Shimadzu gas chromatography, and the conversion of N-hydroxyethyl morpholine was X _HEM And dimorpholinodiethyl ether S _DMDEE Selectivity ofCalculated as follows:

in each of the following examples and comparative examples, N-hydroxyethyl morpholine was used as purchased from Jiangsu Aikang biological medicine research and development Co., ltd.

Example 1

The preparation of the catalyst CHTD-1 comprises the following specific steps:

1. h-type MCM36 molecular sieve is synthesized according to Zhangming et al, namely MCM-22 and MCM-36 molecular sieves are statically synthesized by taking piperidine as a template agent, the silicon-aluminum ratio is 34, and the specific surface area is 411.7m ² The average pore diameter is 4.24nm, the BJH pattern is shown in FIG. 3, and the small angle XRD pattern is shown in FIG. 4.

2. The H-type MCM36 molecular sieve was added to the kneader.

3. The metal calcium is selected for modification by a kneading method, and the specific method comprises the following steps: calcium nitrate calculated according to the addition amount of calcium was prepared into an aqueous solution with a concentration of 50wt%, and slowly dropped into a kneader to be kneaded with the H-type MCM36 molecular sieve for 0.5 hour. While the aqueous solution of calcium nitrate was being added dropwise, stirring was maintained so that calcium nitrate could be added uniformly.

4. Alumina is selected as a binder to be added into a kneader, after being uniformly mixed, a nitric acid solution with the concentration of 10 weight percent is added, the materials are kneaded into colloid, and when the nitric acid solution is added, the materials can be kneaded into colloid.

5. And (3) molding the colloid extrusion strips, drying at 110 ℃ for 8 hours, and roasting at 550 ℃ for 4 hours to obtain the catalyst CHTD-1.

Catalyst CHTD-1 contains 73wt% of H-type MCM36 molecular sieve, 7wt% of calcium oxide and 20wt% of binder.

Example 2

Catalyst CHTD-2 was prepared substantially as in example 1 except that the H-type MCM36 molecular sieve had a silica to alumina ratio of 21; modifying by adopting barium nitrate; and (3) after the colloid extrusion molding, drying at 90 ℃ for 11 hours, and roasting at 510 ℃ for 6 hours to obtain the catalyst CHTD-2.

Catalyst CHTD-2 contains 65wt% of H-type MCM36 molecular sieve, 12wt% of barium oxide and 23wt% of binder.

Example 3

Catalyst CHTD-3 was prepared substantially as in example 1 except that the H-type MCM36 molecular sieve had a silica to alumina ratio of 45; and (3) after the colloid extrusion molding, drying at 135 ℃ for 6 hours, and roasting at 600 ℃ for 3 hours to obtain the catalyst CHTD-3.

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

Example 4

Preparing a catalyst CHTD-4, namely dealuminating an H-type beta molecular sieve for 4 hours by adopting 800 ℃ water vapor, dealuminating the H-type beta molecular sieve for 2 hours at 80 ℃ by adopting 10wt% nitric acid, washing with water, drying the dealuminated molecular sieve for 8 hours at 110 ℃ after washing with water to be neutral, and roasting the molecular sieve for 4 hours at 500 ℃ to prepare the mesoporous H-type beta molecular sieve, wherein the silicon-aluminum ratio is 28, and the specific surface area is 881.4m ² /g, average pore size 4.78nm, see FIG. 5 for a BJH plot. The H-type beta molecular sieve is purchased from Tianjin Shencan technology Co.

2. Alumina is selected as a binder, and the alumina and the mesoporous H-type beta molecular sieve are mixed according to the mass ratio of 2:8, adding into a kneader, uniformly mixing, adding a proper amount of 10wt% nitric acid, and kneading the materials into colloid.

3. Extruding the colloid to form, drying at 110 deg.c for 8 hr, and roasting at 500 deg.c for 4 hr to obtain molecular sieve strip particle;

4. the metal magnesium is selected for modification by an immersion method, and the specific method is as follows: preparing magnesium nitrate with concentration of 30wt% according to magnesium addition amount into water solution, wherein the total mass of the magnesium nitrate solution is the product of the total mass of molecular sieve strip particles and the water absorption rate of the molecular sieve strip particles, placing the molecular sieve strip particles into a rotary evaporator, dropwise adding the magnesium nitrate solution while rotating, and continuing rotating for 3 hours after the dropwise adding is finished to obtain modified particles.

5. The modified particles were dried at 110℃for 8 hours and then calcined at 550℃for 4 hours to give catalyst CHTD-4.

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

Example 5

Catalyst CHTD-5 was prepared substantially as in example 4 except that catalyst CHTD-5 contained 64wt% of mesoporous H-type beta molecular sieve, 20wt% of magnesium oxide, and 16wt% of binder.

Comparative example 1

The preparation of the catalyst DHTD-1 comprises the following specific steps:

the catalyst DHTD-1 is prepared according to the patent US4095022, a silicon oxide carrier is provided by Jiang Yanshi Aute chemical catalyst carrier research of Jiangsu province, and the specific surface area is 352m ² And/g. The phosphoric acid impregnating amount is 30wt%, the impregnating method is an equivalent impregnating method, and the specific method comprises the following steps: preparing an aqueous solution according to the adding amount of phosphoric acid, wherein the total mass of the aqueous solution is the product of the total mass of the silicon oxide carrier and the water absorption rate of the silicon oxide carrier, placing the silicon oxide carrier in a rotary evaporator, dropwise adding the aqueous solution while rotating, and continuing to rotate for 3 hours after the dropwise adding is finished; then drying at 110 ℃ for 8 hours, and roasting at 550 ℃ for 4 hours to obtain the catalyst DHTD-1.

Example 6

In this embodiment, the production process of the bis-morpholinyldiethyl ether is described below, and referring to fig. 1, in the production process, N-hydroxyethyl morpholine as a raw material is first heated along the first feeding pipe 111 through the refrigerant channel of the first heat exchanger 14, then heated in the first heating furnace 11, and then enters the raw material distributor 123 through the feeding port 124. The catalytic distillation reactor 12 comprises a reaction section 121 and a separation section 122 positioned on the upper side of the reaction section 121, a raw material distributor 123 is positioned between the reaction section 121 and the separation section 122, a feed inlet 124 of the catalytic distillation reactor 12 is communicated with the raw material distributor 123, and a catalyst is filled in the reaction section. Trays are mounted in the separation section, in this example 10 trays are mounted in the separation section. The reaction section is in the form of a fixed bed.

After being discharged from the raw material distributor 123, the N-hydroxyethyl morpholine flows downwards to enter a reaction section for reaction, namely, the N-hydroxyethyl morpholine enters the reactor from the top of the reaction section, under the action of a catalyst, the N-hydroxyethyl morpholine reacts to generate dimorpholinodiethyl ether and water, the water forms steam and flows upwards to enter a separation section 122, and part of the N-hydroxyethyl morpholine and dimorpholinodiethyl ether carried by the steam flows downwards and returns to the reaction section under the separation action of a tray. The vapor discharged from the top of the catalytic distillation reactor is cooled by the first air cooler 15 and then discharged into the wastewater treatment system.

The mixture of N-hydroxyethyl morpholine and dimorpholinodiethyl ether discharged from the bottom of the catalytic distillation reactor 12 enters the first rectifying tower 13, the gas phase flows upward and the liquid phase flows downward in the first rectifying tower 13, the boiling point of the N-hydroxyethyl morpholine is lower than that of dimorpholinodiethyl ether, the gas phase is N-hydroxyethyl morpholine gas mixed with dimorpholinodiethyl ether, the main component of the liquid phase is dimorpholinodiethyl ether, and a small amount of N-hydroxyethyl morpholine is mixed, and the bottom material of the first rectifying tower 13 enters the first reboiler 134 for heating.

The temperature in the first reboiler is higher than the boiling point of N-hydroxyethyl morpholine and lower than the boiling point of dimorpholinodiethyl ether, and the gas phase in the first reboiler returns to the bottom of the first rectifying tower after being discharged from the top of the first reboiler and flows upwards. The bottom of the first reboiler is connected with a first material pump 135, and the liquid phase in the first reboiler is discharged as a product after being cooled by the heat medium channel of the first heat exchanger 14 and the first cooler 16 under the action of the first material pump 135.

The gas phase discharged from the top of the first rectifying tower 13 enters the first reflux tank 132 after being condensed by the second air cooler 131, the bottom of the first reflux tank is communicated with the inlet of the first circulating pump 133, the outlet of the first circulating pump is led out to form two branch pipes, the two branch pipes are respectively a first branch pipe 143 and a second branch pipe 144, the first branch pipe 143 is communicated with the upper part of the first rectifying tower 13, the second branch pipe 144 is communicated with the first feeding pipe 111, and the connection point of the second branch pipe 144 and the first feeding pipe 111 is positioned between the first heat exchanger and the first heating furnace. Under the pushing of the first circulating pump, a part of liquid in the first reflux tank 132 returns to the upper part of the first rectifying tower 13 through the first branch pipe, and the other part of liquid enters the first feeding pipe through the second branch pipe and is mixed with raw materials, and enters the catalytic distillation reactor after being heated by the first heating furnace, is recycled and continuously participates in the reaction.

In this embodiment, the first rectifying tower 13 is a tray tower, and an upper tray group 138 and a lower tray group 139 are disposed in the first rectifying tower 13, wherein the upper tray group 138 is located above the lower tray group 139, and in the height direction, the first material inlet 137 of the first rectifying tower is located between the upper tray group 138 and the lower tray group 139. Wherein the upper tray set 138 comprises 15 layers of upper trays and the lower tray set 139 comprises 15 layers of lower trays. The mixture of N-hydroxyethyl morpholine and dimorpholinodiethyl ether exiting the bottom of catalytic distillation reactor 12 enters first rectifying column 13 through first feed inlet 137.

In this example, the catalyst CHTD-1 prepared in example 1 was used as the catalyst in the reaction zone, and the reaction conditions in the reaction zone were: the reaction temperature is 180 ℃, the reaction pressure is 0.2MPa, and the mass space velocity of N-hydroxyethyl morpholine is 3.0h ^-1 . The obtained product was analyzed by gas chromatography, and the analysis results are shown in Table 1.

Example 7

The production apparatus and the flow are basically the same as those of example 6, except that in this example, the catalyst CHTD-2 prepared in example 2 is used as the catalyst in the reaction section, and the reaction conditions in the reaction section are as follows: the reaction temperature is 110 ℃, the reaction pressure is 0.1MPa, and the mass space velocity of N-hydroxyethyl morpholine is 0.6h ^-1 . The obtained product was analyzed by gas chromatography, and the analysis results are shown in Table 1.

Example 8

The production apparatus and the flow are basically the same as those of example 6, except that in this example, the catalyst CHTD-3 prepared in example 3 is used as the catalyst in the reaction section, and the reaction conditions in the reaction section are as follows: the reaction temperature is 210 ℃, the reaction pressure is 0.8MPa, and the mass space velocity of N-hydroxyethyl morpholine is 3.5h ^-1 . Subjecting the obtained product to gas chromatography analysisThe results are shown in Table 1.

Example 9

The production apparatus and the flow chart of this example are basically the same as those of example 6, except that the catalyst CHTD-4 prepared in example 4 is used as the catalyst, and the reaction conditions are as follows: the temperature is 260 ℃, the pressure is 1.0MPa, and the mass space velocity of N-hydroxyethyl morpholine is 2.5h ^-1 . The obtained product was analyzed by gas chromatography, and the analysis results are shown in Table 1.

Example 10

The production apparatus and the flow of this example are basically the same as those of example 6, except that the catalyst CHTD-5 prepared in example 5 is used as the catalyst, and the reaction conditions are as follows: the temperature is 280 ℃, the pressure is 0.9MPa, and the mass space velocity of N-hydroxyethyl morpholine is 4.1h ^-1 . The obtained product was analyzed by gas chromatography, and the analysis results are shown in Table 1.

Example 11

The production process in this embodiment is greatly different from that in embodiment 6, and the production process in this embodiment is described below, referring to fig. 2, in the production process, N-hydroxyethyl morpholine as a raw material is first heated along the second feeding pipe 211 through the refrigerant channel of the second heat exchanger 24, 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, where the fixed bed reactor 22 has only a reaction section, no separation section is provided, and the catalyst is filled in the fixed bed reactor.

The N-hydroxyethyl morpholine reacts under the action of a catalyst to generate dimorpholinodiethyl ether and water, and a reaction mixture formed by unreacted N-hydroxyethyl morpholine, dimorpholinodiethyl ether and water is discharged from the bottom of the fixed bed reactor and then enters a second rectifying tower 23, wherein the second rectifying tower 23 has the same structure as the first rectifying tower 13.

The bottom material of the second rectifying tower enters a second reboiler 234 for heating, the temperature in the second reboiler is higher than the boiling point of N-hydroxyethyl morpholine and lower than the boiling point of dimorpholinodiethyl ether, and the gas phase in the second reboiler 234 is discharged from the top of the second reboiler, returns to the bottom of the second rectifying tower and flows upwards. The bottom of the second reboiler is connected with a second material pump 235, and the liquid phase in the second reboiler is discharged as a product after being cooled by the heat medium channel of the second heat exchanger 24 and the second cooler 26 under the action of the second material pump 235.

The gas phase discharged from the top of the second rectifying tower 23 is condensed by the third air cooler 231 and then enters the second reflux tank 232, the material in the second reflux tank 232 is divided into two parts, one part returns to the second rectifying tower from the top of the second rectifying tower 23 under the action of the second circulating pump 233, and the other part is discharged as waste water and enters the waste water system. A side line 238 is led out from the upper part of the second rectifying tower 23, the side line 238 is communicated with the second feeding pipe 211, the connection point of the side line 238 and the second feeding pipe 211 is positioned between the second heat exchanger and the second heating furnace, partial materials at the upper part of the second rectifying tower 23 are led out as circulating materials, and after the circulating materials are mixed with raw materials, the circulating materials are returned into the fixed bed reactor 22 through the second heating furnace 21 to continue to react and are recycled. The point of attachment of the side stream 238 to the second rectification column 23 is directly opposite the upper portion of the upper tray set of the second rectification column 23.

The reaction mixture of N-hydroxyethyl morpholine, water and dimorpholinodiethyl ether discharged from the bottom of the fixed bed reactor 22 enters the second rectification column 23 through the second material inlet 237, and the position of the second material inlet on the second rectification column is the same as that of the first material inlet on the first rectification column.

In this example, the catalyst CHTD-1 prepared in example 1 was used as the catalyst in the fixed bed reactor. The reaction conditions are as follows: 180 ℃ and 0.2MPa, and 3.0h of N-hydroxyethyl morpholine mass space velocity ^-1 The obtained product was analyzed by gas chromatography, and the analysis results are shown in Table 1.

Comparative example 2

The experimental setup, procedure of this comparative example 2 was the same as in example 3, except that catalyst DHTD-1 prepared in comparative example 1 was used as the catalyst, and the reaction conditions were: the temperature is 260 ℃, the pressure is 1.0MPa, and the mass space velocity of N-hydroxyethyl morpholine is 2.5h ^-1 . The obtained product was analyzed by gas chromatography, and the analysis results are shown in Table 1.

Table 1 analysis results table

As can be seen from Table 1, the conversion of N-hydroxyethyl morpholine and the selectivity of dimorpholinodiethyl ether can be effectively improved by using a simple fixed bed reactor compared with the prior art. And after the catalytic distillation reactor is adopted, compared with a simple fixed bed reactor, the yield of the dimorpholinodiethyl ether can be effectively improved by more than 15wt percent. The adopted catalytic distillation reactor form can effectively remove the generated water in the reaction stage, so that the influence of the water on the reaction is eliminated, the forward progress of the N-hydroxyethyl morpholine dehydration reaction is promoted, and the reaction efficiency is improved; meanwhile, the molecular sieve catalyst used in the application is dehydrated through the acid-base active center synergistic catalysis, so that byproducts generated by the acid center are avoided, and the conversion rate and selectivity are improved.

Claims

1. A method for producing dimorpholinodiethyl ether is characterized in that,

taking a molecular sieve type catalyst as a catalyst, introducing N-hydroxyethyl morpholine serving as a raw material into a reactor for reaction, discharging water generated by the reaction from the top of the reactor, introducing the water into a cooling device for cooling, introducing materials discharged from the bottom of the reactor into a rectifying tower, introducing unreacted N-hydroxyethyl morpholine separated from the rectifying tower into the reactor for recycling, and taking the bottom material at the bottom of the rectifying tower as a product dimorpholinodiethyl ether; the molecular sieve type catalyst is obtained by modifying an acidic mesoporous molecular sieve by alkaline earth metal.

2. The process according to claim 1, wherein the reactor is a catalytic distillation reactor comprising a reaction section and a separation section located at the upper side of the reaction section, wherein the catalyst is packed in the reaction section and wherein the N-hydroxyethyl morpholine is fed into the reactor through the top of the reaction section.

3. The method according to claim 1, wherein the molecular sieve catalyst comprises 60 to 90wt% of the acidic mesoporous molecular sieve, 1 to 20wt% of the alkaline earth metal oxide, and 5 to 30wt% of the binder.

4. The production method according to claim 1, wherein the acidic mesoporous molecular sieve is an acidic molecular sieve having a mesoporous structure of 2 to 50nm, and the acidic mesoporous molecular sieve comprises a silicon-based mesoporous molecular sieve modified with Al, a microporous acidic molecular sieve having a mesoporous structure introduced therein, and an acidic molecular sieve having a mesoporous structure itself.

5. The production method according to claim 1, wherein the acidic mesoporous molecular sieve has a silica-alumina ratio of 20-50, an alkali metal content of less than 100PPM, and a specific surface area of 300-1200m ² And/g, the average pore diameter is 3-30nm.

6. The method according to claim 1, wherein the alkaline earth metal is Mg, ca or Ba.

7. The production method according to claim 1, wherein the alkaline earth metal is introduced by any one of a kneading method, an equivalent impregnation method, and a multi-step impregnation method.

8. The method of claim 1, wherein the molecular sieve catalyst is prepared by two methods:

the method comprises the following steps:

(2) Extruding the colloid to form, drying at 90-150 deg.c for 5-12 hr, and roasting at 500-600 deg.c for 3-6 hr to obtain molecular sieve catalyst;

the second method is as follows:

9. The method of claim 8, wherein the binder is any one or at least two of alumina, silica, and zirconia.

10. The process according to claim 1, wherein the reaction temperature is 100 to 300℃and the reaction pressure is 0.1 to 1.0MPa and the mass space velocity of N-hydroxyethyl morpholine is 0.5 to 5 hours in the reactor ^-1 。