CN115385813A - Production process for preparing dibutyl formamide - Google Patents
Production process for preparing dibutyl formamide Download PDFInfo
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- CN115385813A CN115385813A CN202211023871.6A CN202211023871A CN115385813A CN 115385813 A CN115385813 A CN 115385813A CN 202211023871 A CN202211023871 A CN 202211023871A CN 115385813 A CN115385813 A CN 115385813A
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C231/00—Preparation of carboxylic acid amides
- C07C231/02—Preparation of carboxylic acid amides from carboxylic acids or from esters, anhydrides, or halides thereof by reaction with ammonia or amines
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
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- C—CHEMISTRY; METALLURGY
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- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C231/00—Preparation of carboxylic acid amides
- C07C231/22—Separation; Purification; Stabilisation; Use of additives
- C07C231/24—Separation; Purification
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Abstract
The invention belongs to the technical field of dibutyl formamide, and particularly relates to a production process for preparing dibutyl formamide. The invention solves the blank of the N, N-dibutylformamide, and the high-purity dibutylformamide is obtained by matching separation and impurity removal on the basis of a fixed bed reaction system, thereby not only greatly improving the reaction efficiency, needing no catalyst removal, shortening the process time, but also providing the product quality and the yield.
Description
Technical Field
The invention belongs to the technical field of dibutyl formamide, and particularly relates to a production process for preparing dibutyl formamide.
Background
The dibutyl formamide is short for N, N-dibutyl formamide, is a chemical intermediate and belongs to formamide compounds. The molecular formula of the dibutyl formamide is C 9 H 19 NO, with a boiling point of 240 ℃ and is inherently irritating. Current dibutylformamide is based on its own carboxamidesThe characteristics of the compound have wide practical value in the fields of chemistry and chemical engineering and drug production, but the report of the dibutylformamide is rare and the process content is not reported yet.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a production process for preparing dibutylformamide, which solves the blank of N, N-dibutylformamide, and is matched with separation and impurity removal to obtain high-purity dibutylformamide on the basis of a fixed bed reaction system, so that the reaction efficiency is greatly improved, a catalyst is not required to be removed, the process time is shortened, and the product quality and the yield are improved.
In order to achieve the technical purpose, the technical scheme of the invention is as follows:
a process for preparing dibutyl formamide uses methyl formate and dibutyl as raw materials, and includes catalytic reaction in fixed bed to obtain coarse dibutyl formamide liquid, and separation to remove impurities.
Further, the catalyst for the fixed bed catalytic reaction adopts a composite titanium-based lanthanide catalyst, and the using amount of the catalyst is 1-2% of the mass of the methyl formate. The thickness of the fixed bed is 100-150mm.
Furthermore, the composite titanium-based lanthanide catalyst takes activated alumina as a porous substrate, titanium monoxide as an auxiliary active material and lanthanum oxide as an active material, and the lanthanum oxide is fixed on the surface of the activated alumina through the titanium monoxide. In the whole catalytic system, lanthanum oxide has a certain catalytic effect in a fixed bed catalytic reaction system, the catalytic activity of the lanthanum oxide is lower than that of a simple lanthanum substance, but when the simple lanthanum substance is used as a catalytic active material, the surface of the simple lanthanum substance is easily affected by reactants, so that the exposed area of the surface is reduced, the catalytic activity is substantially and rapidly reduced, even the activity is dissipated, and aiming at the problem, the technical scheme utilizes titanium monoxide as a composite layer to improve the surface activity of the lanthanum oxide, and meanwhile, the conductivity of the titanium monoxide can effectively improve the electron conduction rate in the lanthanum oxide catalytic process, so that a synergistic catalytic system is effectively formed; the activated alumina is used as a carrier in the whole system, and the electron transfer of the titanium monoxide can be accelerated by the activity of the surface of the activated alumina, namely, the activated alumina can form the electron transfer of lanthanum oxide, shorten the electron transfer distance of the lanthanum oxide and form an internal electron transfer network. The preparation method of the composite titanium-based lanthanide catalyst comprises the following steps: a1, adding aluminum isopropoxide and ethyl cellulose into isopropanol, uniformly stirring, granulating to obtain mixed particles, standing the mixed particles in a reaction kettle for 1-2 hours, and purging to obtain prefabricated particles, wherein the mass ratio of the aluminum isopropoxide to the ethyl cellulose is 2-4; the method comprises the following steps of ensuring that aluminum isopropoxide and ethyl cellulose are completely mixed by utilizing the solubility of the isopropanol to the aluminum isopropoxide and the ethyl cellulose, and slowly releasing the isopropanol in the granulation process, so that the aluminum isopropoxide and the ethyl cellulose are mixed in a solid state, and the effect of uniform dispersion is realized; in the standing process, water molecules do not want to ethyl cellulose, the water molecules and aluminum isopropoxide form hydrolysis reaction and are converted into isopropanol and aluminum hydroxide, the isopropanol can soften the ethyl cellulose, and the isopropanol and water have good solubility, so that the effect of capturing the water molecules is achieved, the reaction of the aluminum isopropoxide and the water molecules in the inner layer is promoted, and the complete conversion of the aluminum isopropoxide is realized; a2, placing the prefabricated particles into a reaction kettle, standing and sintering for 2-3h, then soaking the prefabricated particles into anhydrous ether, carrying out ultrasonic treatment for 20-30min, taking out the prefabricated particles and drying to obtain porous active alumina particles; the standing and sintering atmosphere is a nitrogen atmosphere, the sintering temperature is 170-190 ℃, the ultrasonic treatment temperature is 10-20 ℃, the ultrasonic frequency is 40-70kHz, and the drying temperature is 40-50 ℃; in the step, in the standing and sintering process, aluminum hydroxide is converted into activated alumina, and simultaneously ethyl cellulose is not changed, namely, the aluminum hydroxide is polymerized into the activated alumina in situ, and the ethyl cellulose serving as a spacing agent is dissolved under the dissolubility of diethyl ether and the high-frequency vibration of ultrasound to achieve the effect of quick removal, so that the activated alumina with a porous structure is formed; a3, dissolving n-butyl titanate in diethyl ether, uniformly stirring, adding porous activated alumina, taking out after soaking, and drying to obtain coated activated alumina, wherein the concentration of n-butyl titanate in diethyl ether is 100-200g/L, the stirring speed is 300-500g/L, and the drying temperature is 40-50 ℃; in the step, n-butyl titanate is dissolved in diethyl ether, and in the soaking process, the adsorbability of activated alumina can adsorb the n-butyl titanate to the surface of an active group, so that the effect of uniform coating is achieved; a4, putting the coated active alumina into a reaction kettle for hydrolysis and sintering to obtain titanium dioxide coated active alumina particles, then carrying out surface reduction reaction on the titanium dioxide coated active alumina particles for 1-2h, and cooling to obtain titanium monoxide coated active alumina; the atmosphere of the reaction kettle is a steam-containing atmosphere, the volume of the steam accounts for 5-8%, the hydrolysis temperature is 40-50 ℃, the sintering temperature is 200-250 ℃, the reduction reaction adopts a hydrogen reduction method, the atmosphere is a nitrogen atmosphere, the flow rate of hydrogen is 10-20mL/min, the temperature is 220-240 ℃, the pressure is 0.2-0, and 3MPa; hydrolyzing and sintering n-butyl titanate to form a titanium dioxide structure by using an in-situ hydrolysis mode, and converting the titanium dioxide into titanium monoxide by using a hydrogen reduction mode to obtain titanium monoxide coated activated alumina; at the moment, the connection part of the titanium dioxide and the alumina still maintains a titanium dioxide structure, so that stable connection is realized, and the chemical connection characteristic of the titanium monoxide and the activated alumina is ensured; adding lanthanum oxide into ethanol, performing ultrasonic mixing to obtain lanthanide precursor solution, soaking titanium oxide coating active aluminum oxide material into the lanthanide precursor solution, performing ultrasonic treatment for 10-20min, standing for 1-2h, taking out the material, and drying to obtain a catalyst, wherein the concentration of lanthanum oxide in ethanol is 10-20g/L, the ultrasonic treatment temperature is 10-20 ℃, the ultrasonic frequency is 40-60kHz, and the drying temperature is 80-90 ℃; the step forms in-situ adsorption on the lanthanum oxide by utilizing the oxygen deficiency and the titanium deficiency of the titanium monoxide, so that the combined connection effect of the titanium monoxide and the lanthanum oxide is achieved. The catalyst prepared by the process has an excellent catalytic effect, and simultaneously, titanium monoxide is used as a conductive material, and the catalytic activity of lanthanum oxide is effectively improved by the compound synergistic effect of active alumina and surface titanium dioxide. The active alumina has good heat conduction performance, can realize temperature transfer in the catalyst, ensures that the catalyst is in a relatively average temperature state, and has a relatively balanced catalytic reaction system. The catalyst prepared by the process is based on the oxygen deficiency characteristic of titanium monoxide, and can attract the oxygen element of lanthanum oxide, particularly lanthanum-oxygen double bonds in lanthanum oxide, so that the lanthanum element is exposed, and the aim of improving the catalytic activity is fulfilled; meanwhile, the adsorption characteristic of the titanium monoxide ensures that the surface is covered by the activated alumina and the lanthanum oxide, and the problem of inactivation cannot occur.
The reaction steps of the crude dibutylformamide liquid are as follows: b1, placing the fixed bed in a reaction kettle, heating and activating to obtain the reaction kettle with an activated catalyst, wherein the temperature for heating and activating is 200-300 ℃, the time is 2-3h, the atmosphere of the reaction kettle is an inert gas atmosphere, the inert gas is argon or helium, and the flow rate of the inert gas is 20-50mL/min; under the temperature, the catalyst is influenced by the temperature, the catalytic activity of the surface is increased, meanwhile, the self heat transfer performance of the aluminum oxide ensures that the surface temperature of the catalyst is relatively balanced, and the problem of overhigh local temperature does not exist, b2, nitrogen is introduced into a reaction kettle to form a nitrogen atmosphere, then methyl formate and dibutylamine are introduced for reaction until the conversion rate of the methyl formate is 98.8 percent, the reaction is complete, the pressure of the nitrogen atmosphere for obtaining the reaction liquid is 0.4-0.6MPa, and the temperature is 230-250 ℃. Wherein the molar ratio of methyl formate to dibutylamine is 1. In the reaction system, dibutylamine and methyl formate are put into a reaction kettle according to a proportion, and a fixed bed catalytic reaction is formed under the temperature condition to form methanol and dibutyl formamide. Meanwhile, in a fixed bed catalytic reaction system, the catalyst belongs to a solid state, can be quickly separated from reaction products, and does not contain catalyst impurities.
The reaction step also comprises b3, settling the reaction solution at constant temperature, and purging with nitrogen to obtain crude dibutylformamide solution and methanol, wherein the temperature of constant temperature settling is 90-100 ℃, and the temperature of nitrogen purging is 80-100 ℃; in the process of constant temperature sedimentation, methanol as a product is converted into a gas state, the dibutylformamide is converted into a liquid state to form gas-liquid separation, and the methanol is recovered at the temperature of 5-10 ℃ in the process of nitrogen purging.
The methyl formate is obtained by taking methanol as a raw material for catalytic reaction, and the methanol recycled by b3 can be used as a raw material for preparing the methyl formate. The methanol in b3 contains a small amount of methyl formate, and cannot influence the process for preparing the methyl formate by catalyzing the methanol. The methyl formate process is well known in the art and will not be described in detail herein, but the methanol recovered from b3 is directly used in the catalytic process of methyl formate.
The separation and impurity removal method comprises the following steps:
step 1, placing crude dibutylformamide liquid into an adsorption column for adsorption treatment, wherein the flow rate of the adsorption treatment is 50-100mL/min, the adsorption column is filled with alumina-based adsorbent, the filling amount is 80-90% of the length of the adsorption column, the alumina-based adsorbent is porous particles of 5-10mm, and the alumina-based adsorbent takes calcium oxide as an inner core and porous alumina as a surface shell layer; and the preparation method of the alumina-based adsorbent comprises the following steps: c1, adding calcium hydroxide and ethyl cellulose into diethyl ether, uniformly stirring, and then granulating to obtain prefabricated particles, wherein the mass ratio of the calcium hydroxide to the ethyl cellulose is 5; the method comprises the following steps of forming a suspension by utilizing the solubility of ethyl cellulose and the insolubility of calcium hydroxide in diethyl ether, and granulating at low temperature to obtain particles; c2, adding aluminum isopropoxide and ethyl cellulose into ethanol, uniformly stirring, spraying to the surface of the prefabricated particles, standing to obtain coated particles, wherein the mass ratio of the aluminum isopropoxide to the ethyl cellulose is 10; the method comprises the following steps of forming a stable curing effect by utilizing the same material characteristics of ethyl cellulose and prefabricated particles, and fixing aluminum isopropoxide on the surfaces of the prefabricated particles to form a liquid film; c3, standing the coated particles for 10min, and then placing the coated particles into a muffle furnace for sintering treatment for 2h to obtain porous alumina-coated calcium oxide; the standing atmosphere is water vapor and nitrogen atmosphere, the volume ratio of the water vapor is 10%, and the sintering treatment temperature is 530 ℃; the aluminum isopropoxide is converted into the aluminum hydroxide by an in-situ hydrolysis mode, and the influence of calcium hydroxide is avoided by utilizing the hydrophobicity of the ethyl cellulose; and secondly, the ethyl cellulose is completely removed in the sintering process, the calcium hydroxide is decomposed into calcium oxide, and the aluminum hydroxide is converted into an aluminum oxide structure. The inner layer of the adsorbent is provided with calcium oxide, residual water molecules in crude liquid can be absorbed, a large amount of heat is generated, the performance of the adsorbent can be influenced by local high temperature, the heat conductivity of the alumina can be quickly transferred, the temperature balance of the whole system is realized, the local high temperature is converted into the overall heat to be improved, and the adsorption efficiency is properly improved by utilizing the temperature;
and 2, putting the crude dibutylformamide liquid after adsorption treatment into a rectifying tower for vacuum rectification treatment to obtain high-purity dibutylformamide, wherein the rectification treatment adopts negative pressure rectification, the temperature is 130-140 ℃, the temperature at the top of the tower is 115-125 ℃, and the pressure is-0.09 to-0.095 MPa. In the negative pressure rectification treatment process in the rectification tower, further separation is carried out under the vacuum condition, impurities in liquid are removed, and high-purity dibutyl formamide is obtained, wherein the content of dibutyl formamide is not less than 99.0%, namely the end point of reaction when the dibutyl formamide reaches 99.0%.
As can be seen from the above description, the present invention has the following advantages:
1. the invention solves the blank of the N, N-dibutylformamide, and the high-purity dibutylformamide is obtained by matching separation and impurity removal on the basis of a fixed bed reaction system, thereby not only greatly improving the reaction efficiency, needing no catalyst removal, shortening the process time, but also providing the product quality and the yield.
2. According to the invention, the methanol recovery of the crude dibutyl formamide liquid is utilized, the methanol is recycled, and the methanol is used in a system for preparing methyl formate from methanol, so that the methanol is recycled, the emission reduction effect is achieved, and the production cost is reduced.
3. According to the invention, the adsorption column is matched with the negative pressure rectification mode to remove impurities through a solid-liquid impurity removal mode, and meanwhile, the vacuum negative pressure is matched with the high temperature mode to remove dissolved impurities, so that the high purity of the dibutyl formamide is realized.
Detailed Description
The present invention will be described in detail with reference to examples, but the present invention is not limited to the claims.
Example 1
A process for preparing dibutyl formamide uses methyl formate and dibutyl as raw materials, and includes catalytic reaction in fixed bed to obtain coarse dibutyl formamide liquid, and separation to remove impurities.
The catalyst for the fixed bed catalytic reaction adopts a composite titanium-based lanthanide catalyst, and the using amount of the catalyst is 1% of the mass of methyl formate. The thickness of the fixed bed is 100mm.
The composite titanium-based lanthanide catalyst takes activated alumina as a porous substrate, titanium monoxide as an auxiliary active material and lanthanum oxide as an active material, and the lanthanum oxide is fixed on the surface of the activated alumina through the titanium monoxide. The preparation method of the composite titanium-based lanthanide catalyst comprises the following steps: a1, adding aluminum isopropoxide and ethyl cellulose into isopropanol, uniformly stirring, granulating to obtain mixed particles, standing the mixed particles in a reaction kettle for 1h, and purging to obtain prefabricated particles, wherein the mass ratio of the aluminum isopropoxide to the ethyl cellulose is 2; a2, placing the prefabricated particles into a reaction kettle, standing and sintering for 2 hours, then soaking the prefabricated particles into anhydrous ether, carrying out ultrasonic treatment for 20min, taking out the prefabricated particles, and drying the prefabricated particles to obtain porous active alumina particles; the standing and sintering atmosphere is a nitrogen atmosphere, the sintering temperature is 170 ℃, the ultrasonic treatment temperature is 10 ℃, the ultrasonic frequency is 40kHz, and the drying temperature is 40 ℃; a3, dissolving n-butyl titanate in diethyl ether, uniformly stirring, adding porous activated alumina, taking out after soaking, and drying to obtain coated activated alumina, wherein the concentration of n-butyl titanate in diethyl ether is 100g/L, the stirring speed is 300g/L, and the drying temperature is 40 ℃; a4, putting the coated active alumina into a reaction kettle, hydrolyzing and sintering to obtain titanium dioxide coated active alumina particles, then carrying out surface reduction reaction on the titanium dioxide coated active alumina particles for 1h, and cooling to obtain titanium monoxide coated active alumina; the atmosphere of the reaction kettle is an atmosphere containing water vapor, the volume percentage of the water vapor is 5%, the hydrolysis temperature is 40 ℃, the sintering temperature is 200 ℃, the reduction reaction adopts a hydrogen reduction method, the atmosphere is a nitrogen atmosphere, the flow rate of hydrogen is 10-20mL/min, the temperature is 220 ℃, and the pressure is 0.2MPa; adding lanthanum oxide into ethanol, performing ultrasonic mixing to obtain lanthanide precursor solution, soaking titanium oxide coated active aluminum oxide material into the lanthanide precursor solution, performing ultrasonic treatment for 10min, standing for 1-2h, taking out the material, and drying to obtain a catalyst, wherein the concentration of lanthanum oxide in ethanol is 10g/L, the ultrasonic treatment temperature is 10 ℃, the ultrasonic frequency is 40kHz, and the drying temperature is 80 ℃.
The reaction steps of the crude dibutylformamide liquid are as follows: b1, placing the fixed bed in a reaction kettle, heating and activating to obtain the reaction kettle with an activated catalyst, wherein the temperature for heating and activating is 200 ℃, the time is 2h, the atmosphere of the reaction kettle is an inert gas atmosphere, the inert gas is argon, and the flow rate of the inert gas is 20mL/min; b2, introducing nitrogen into the reaction kettle to form a nitrogen atmosphere, then introducing methyl formate and dibutylamine to react until the conversion rate of the methyl formate is 98.8%, wherein the reaction is complete, and the pressure of the nitrogen atmosphere is 0.4MPa, and the temperature is 230 ℃. Wherein the molar ratio of methyl formate to dibutylamine is 1.
The reaction step also comprises b3, carrying out constant temperature sedimentation on the reaction liquid, and carrying out nitrogen purging to obtain crude dibutyl formamide liquid and methanol, wherein the constant temperature sedimentation temperature is 90 ℃, and the nitrogen purging temperature is 80 ℃; in the process of constant temperature sedimentation, methanol as a product is converted into a gas state, the dibutyl formamide is converted into a liquid state to form gas-liquid separation, and the methanol is recovered at 5-10 ℃ in the process of nitrogen purging.
The methyl formate is obtained by taking methanol as a raw material for catalytic reaction, and the methanol recycled by b3 can be used as a raw material for preparing the methyl formate.
The separation and impurity removal method comprises the following steps:
step 1, placing crude dibutylformamide liquid into an adsorption column for adsorption treatment, wherein the flow rate of the adsorption treatment is 50mL/min, the adsorption column is filled with an alumina-based adsorbent, the filling amount of the alumina-based adsorbent is 80% of the length of the adsorption column, the alumina-based adsorbent is porous particles of 5mm, and the alumina-based adsorbent takes calcium oxide as an inner core and porous alumina as a surface shell layer; and the preparation method of the alumina-based adsorbent comprises the following steps: c1, adding calcium hydroxide and ethyl cellulose into diethyl ether, uniformly stirring, and then granulating to obtain prefabricated particles, wherein the mass ratio of the calcium hydroxide to the ethyl cellulose is 5; c2, adding aluminum isopropoxide and ethyl cellulose into ethanol, uniformly stirring, spraying to the surface of the prefabricated particles, standing to obtain coated particles, wherein the mass ratio of the aluminum isopropoxide to the ethyl cellulose is 10; c3, standing the coated particles for 10min, and then placing the coated particles into a muffle furnace for sintering treatment for 2h to obtain calcium oxide coated by porous alumina; the standing atmosphere is water vapor and nitrogen atmosphere, the volume ratio of the water vapor is 10%, and the sintering treatment temperature is 530 ℃;
and 2, putting the crude dibutylformamide liquid after adsorption treatment into a rectifying tower for vacuum rectification treatment to obtain high-purity dibutylformamide, wherein the rectification treatment adopts negative pressure rectification, the temperature is 130 ℃, the temperature at the top of the tower is 115 ℃, and the pressure is-0.09 MPa to-0.095 MPa.
Example 2
A process for preparing dibutyl formamide uses methyl formate and dibutyl as raw materials, and includes catalytic reaction in fixed bed to obtain coarse dibutyl formamide liquid, and separation to remove impurities.
Further, the catalyst for the fixed bed catalytic reaction adopts a composite titanium-based lanthanide catalyst, and the using amount of the catalyst is 2% of the mass of the methyl formate. The thickness of the fixed bed is 150mm.
Furthermore, the composite titanium-based lanthanide catalyst takes activated alumina as a porous substrate, titanium monoxide as an auxiliary active material and lanthanum oxide as an active material, and the lanthanum oxide is fixed on the surface of the activated alumina through the titanium monoxide. The preparation method of the composite titanium-based lanthanide catalyst comprises the following steps: a1, adding aluminum isopropoxide and ethyl cellulose into isopropanol, uniformly stirring, granulating to obtain mixed particles, standing the mixed particles in a reaction kettle for 2 hours, and purging to obtain prefabricated particles, wherein the mass ratio of the aluminum isopropoxide to the ethyl cellulose is 4; a2, placing the prefabricated particles into a reaction kettle, standing and sintering for 3 hours, then soaking the prefabricated particles into anhydrous ether, carrying out ultrasonic treatment for 30min, taking out the prefabricated particles and drying the prefabricated particles to obtain porous active alumina particles; the standing and sintering atmosphere is nitrogen atmosphere, the sintering temperature is 190 ℃, the ultrasonic treatment temperature is 20 ℃, the ultrasonic frequency is 70kHz, and the drying temperature is 50 ℃; a3, dissolving n-butyl titanate in diethyl ether, uniformly stirring, adding porous activated alumina, taking out after soaking, and drying to obtain coated activated alumina, wherein the concentration of n-butyl titanate in diethyl ether is 200g/L, the stirring speed is 500g/L, and the drying temperature is 50 ℃; a4, putting the coated active alumina into a reaction kettle, hydrolyzing and sintering to obtain titanium dioxide coated active alumina particles, then carrying out surface reduction reaction on the titanium dioxide coated active alumina particles for 2 hours, and cooling to obtain titanium monoxide coated active alumina; the atmosphere of the reaction kettle is an atmosphere containing water vapor, the volume percentage of the water vapor is 8%, the hydrolysis temperature is 50 ℃, the sintering temperature is 250 ℃, the reduction reaction adopts a hydrogen reduction method, the atmosphere is a nitrogen atmosphere, the flow rate of hydrogen is 20mL/min, the temperature is 240 ℃, and the pressure is 0.3MPa; and a5, adding lanthanum oxide into ethanol, performing ultrasonic mixing to obtain lanthanide precursor liquid, then soaking the titanium oxide coating active aluminum oxide material into the lanthanide precursor liquid, performing ultrasonic treatment for 20min, standing for 2h, taking out the material, and drying to obtain the catalyst, wherein the concentration of lanthanum oxide in ethanol is 20g/L, the ultrasonic treatment temperature is 20 ℃, the ultrasonic frequency is 60kHz, and the drying temperature is 90 ℃.
The reaction steps of the crude dibutylformamide liquid are as follows: b1, placing the fixed bed in a reaction kettle, heating and activating to obtain the reaction kettle with an activated catalyst, wherein the temperature for heating and activating is 300 ℃, the time is 3 hours, the atmosphere of the reaction kettle is an inert gas atmosphere, the inert gas is argon or helium, and the flow rate of the inert gas is 50mL/min; b2, introducing nitrogen into the reaction kettle to form a nitrogen atmosphere, then introducing methyl formate and dibutylamine to react until the conversion rate of the methyl formate is 98.8%, wherein the reaction is complete, and the pressure of the nitrogen atmosphere is 0.6MPa, and the temperature is 250 ℃. Wherein the molar ratio of methyl formate to dibutylamine is 1.
The reaction step also comprises b3, carrying out constant temperature sedimentation on the reaction liquid, and carrying out nitrogen purging to obtain crude dibutyl formamide liquid and methanol, wherein the constant temperature sedimentation temperature is 100 ℃, and the nitrogen purging temperature is 100 ℃; in the process of constant temperature sedimentation, methanol as a product is converted into a gas state, and dibutylformamide is converted into a liquid state to form gas-liquid separation, and methanol is recovered at 10 ℃ in the process of nitrogen purging.
The methyl formate is obtained by taking methanol as a raw material for catalytic reaction, and the methanol recycled by b3 can be used as a raw material for preparing the methyl formate.
The separation and impurity removal method comprises the following steps:
step 1, placing crude dibutylformamide liquid into an adsorption column for adsorption treatment, wherein the flow rate of the adsorption treatment is 100mL/min, the adsorption column is filled with an alumina-based adsorbent, the filling amount of the alumina-based adsorbent is 90% of the length of the adsorption column, the alumina-based adsorbent is porous particles of 10mm, and the alumina-based adsorbent takes calcium oxide as an inner core and porous alumina as a surface shell layer; and the preparation method of the alumina-based adsorbent comprises the following steps: c1, adding calcium hydroxide and ethyl cellulose into diethyl ether, uniformly stirring, and then granulating to obtain prefabricated particles, wherein the mass ratio of the calcium hydroxide to the ethyl cellulose is 5; c2, adding aluminum isopropoxide and ethyl cellulose into ethanol, uniformly stirring, spraying to the surface of the prefabricated particles, standing to obtain coated particles, wherein the mass ratio of the aluminum isopropoxide to the ethyl cellulose is 10; c3, standing the coated particles for 10min, and then placing the coated particles into a muffle furnace for sintering treatment for 2h to obtain calcium oxide coated by porous alumina; the standing atmosphere is water vapor and nitrogen atmosphere, the volume ratio of the water vapor is 10%, and the sintering treatment temperature is 530 ℃;
and 2, putting the crude dibutyl formamide liquid after adsorption treatment into a rectifying tower for vacuum rectification treatment to obtain high-purity dibutyl formamide, wherein the rectifying treatment adopts negative pressure rectification, the temperature is 140 ℃, the temperature at the top of the tower is 125 ℃, and the pressure is-0.09 to-0.095 MPa.
Example 3
A process for preparing dibutyl formamide uses methyl formate and dibutyl as raw materials, and includes catalytic reaction in fixed bed to obtain coarse dibutyl formamide liquid, and separation to remove impurities.
Further, the catalyst for the fixed bed catalytic reaction adopts a composite titanium-based lanthanide catalyst, and the using amount of the catalyst is 2% of the mass of the methyl formate. The thickness of the fixed bed is 150mm.
Furthermore, the composite titanium-based lanthanide catalyst takes activated alumina as a porous substrate, titanium monoxide as an auxiliary active material and lanthanum oxide as an active material, and the lanthanum oxide is fixed on the surface of the activated alumina through the titanium monoxide. The preparation method of the composite titanium-based lanthanide catalyst comprises the following steps: a1, adding aluminum isopropoxide and ethyl cellulose into isopropanol, uniformly stirring, granulating to obtain mixed particles, standing the mixed particles in a reaction kettle for 2 hours, and purging to obtain prefabricated particles, wherein the mass ratio of the aluminum isopropoxide to the ethyl cellulose is 4; a2, placing the prefabricated particles into a reaction kettle, standing and sintering for 3 hours, then soaking the prefabricated particles into anhydrous ether, carrying out ultrasonic treatment for 25min, taking out the prefabricated particles and drying the prefabricated particles to obtain porous active alumina particles; the standing and sintering atmosphere is nitrogen atmosphere, the sintering temperature is 180 ℃, the ultrasonic treatment temperature is 15 ℃, the ultrasonic frequency is 50kHz, and the drying temperature is 45 ℃; a3, dissolving n-butyl titanate in diethyl ether, uniformly stirring, adding porous activated alumina, taking out after soaking, and drying to obtain coated activated alumina, wherein the concentration of n-butyl titanate in diethyl ether is 150g/L, the stirring speed is 400g/L, and the drying temperature is 45 ℃; a4, putting the coated active alumina into a reaction kettle for hydrolysis and sintering to obtain titanium dioxide coated active alumina particles, then carrying out surface reduction reaction on the titanium dioxide coated active alumina particles for 2 hours, and cooling to obtain titanium monoxide coated active alumina; the atmosphere of the reaction kettle is an atmosphere containing water vapor, the volume ratio of the water vapor is 5-8%, the hydrolysis temperature is 45 ℃, the sintering temperature is 230 ℃, the reduction reaction adopts a hydrogen reduction method, the atmosphere is a nitrogen atmosphere, the flow rate of hydrogen is 15mL/min, the temperature is 230 ℃, and the pressure is 0.2MPa; and a5, adding lanthanum oxide into ethanol, performing ultrasonic mixing to obtain lanthanide precursor liquid, then soaking the titanium oxide coating active aluminum oxide material into the lanthanide precursor liquid, performing ultrasonic treatment for 15min, standing for 1-2h, taking out the material, and drying to obtain the catalyst, wherein the concentration of lanthanum oxide in ethanol is 15g/L, the ultrasonic treatment temperature is 15 ℃, the ultrasonic frequency is 50kHz, and the drying temperature is 85 ℃.
The reaction steps of the crude dibutylformamide liquid are as follows: b1, placing the fixed bed in a reaction kettle, heating and activating to obtain the reaction kettle with an activated catalyst, wherein the temperature for heating and activating is 250 ℃, the time is 3h, the atmosphere of the reaction kettle is an inert gas atmosphere, the inert gas is argon or helium, and the flow rate of the inert gas is 40mL/min; b2, introducing nitrogen into the reaction kettle to form a nitrogen atmosphere, introducing methyl formate and dibutylamine to react until the conversion rate of the methyl formate is 98.8%, and taking complete reaction to obtain a reaction solution, wherein the pressure of the nitrogen atmosphere is 0.5MPa, and the temperature is 240 ℃. Wherein the molar ratio of methyl formate to dibutylamine is 1.
The reaction step also comprises b3, carrying out constant temperature sedimentation on the reaction liquid, and carrying out nitrogen purging to obtain crude dibutyl formamide liquid and methanol, wherein the constant temperature sedimentation temperature is 95 ℃, and the nitrogen purging temperature is 80-100 ℃; in the process of constant temperature sedimentation, methanol as a product is converted into a gas state, and the dibutylformamide is converted into a liquid state to form gas-liquid separation, and the methanol is recovered at 8 ℃ in the process of nitrogen purging.
The methyl formate is obtained by taking methanol as a raw material for catalytic reaction, and the methanol recycled by b3 can be used as a raw material for preparing the methyl formate.
The separation and impurity removal method comprises the following steps:
step 1, placing crude dibutylformamide liquid into an adsorption column for adsorption treatment, wherein the flow rate of the adsorption treatment is 80mL/min, the adsorption column is filled with an alumina-based adsorbent, the filling amount is 85% of the length of the adsorption column, the alumina-based adsorbent is porous particles of 8mm, and the alumina-based adsorbent takes calcium oxide as an inner core and porous alumina as a surface shell layer; and the preparation method of the alumina-based adsorbent comprises the following steps: c1, adding calcium hydroxide and ethyl cellulose into diethyl ether, uniformly stirring, and then granulating to obtain prefabricated particles, wherein the mass ratio of the calcium hydroxide to the ethyl cellulose is 5; c2, adding aluminum isopropoxide and ethyl cellulose into ethanol, uniformly stirring, spraying to the surface of the prefabricated particles, standing to obtain coated particles, wherein the mass ratio of the aluminum isopropoxide to the ethyl cellulose is 10; c3, standing the coated particles for 10min, and then placing the coated particles into a muffle furnace for sintering treatment for 2h to obtain porous alumina-coated calcium oxide; the standing atmosphere is water vapor and nitrogen atmosphere, the volume ratio of the water vapor is 10%, and the sintering treatment temperature is 530 ℃;
and 2, putting the crude dibutylformamide liquid after adsorption treatment into a rectifying tower for vacuum rectification treatment to obtain high-purity dibutylformamide, wherein the rectification treatment adopts negative pressure rectification, the temperature is 135 ℃, the temperature at the top of the tower is 120 ℃, and the pressure is-0.09 to-0.095 MPa.
Performance detection
The time taken for the reaction solution to be mixed to reach 98.8% in examples 1 to 3 is as follows:
| examples | Time (h) |
| 1 | 35 |
| 2 | 33 |
| 3 | 33 |
The yields of examples 1-3 are as follows:
| examples | Yield (%) |
| 1 | 99.70 |
| 2 | 99.73 |
| 3 | 99.72 |
The detection result of the product of the example 1 is as follows:
| item | Index (I) | The result of the detection |
| Appearance of the product | Colorless transparent liquid without visible impurities | Qualified |
| N, N-dibutylformamide (mass fraction), omega/%, ≧ | 99.50 | 99.7 |
| Chroma (Hazen unit-Pt-Co number) is less than or equal to | 5 | 5 |
| Water content (mass fraction), omega/%, is less than or equal to | 0.050 | 0.022 |
| Methanol (mass fraction), omega/%, is less than or equal to | 0.050 | 0.007 |
| Fe, mu g/kg, not more than | 20 | 10 |
After continuous reaction, the product quality and the income of the process are not changed, the requirement of batch production of enterprises is met, and the economic benefit of enterprise production is improved by matching with the recycling of methanol.
It should be understood that the detailed description of the invention is merely illustrative of the invention and is not intended to limit the invention to the specific embodiments described. It will be understood by those skilled in the art that the present invention may be modified and equivalents substituted for elements thereof to achieve the same technical result; and are within the scope of the present invention as long as the requirements of use are met.
Claims (10)
1. A production process for preparing dibutyl formamide is characterized by comprising the following steps: methyl formate and dibutyl are used as raw materials, a dibutyl formamide crude liquid is obtained through fixed bed catalytic reaction, and purified dibutyl formamide is obtained after separation and impurity removal.
2. The process according to claim 1 for preparing dibutylformamide, characterized in that: the catalyst for the fixed bed catalytic reaction adopts a composite titanium-based lanthanide catalyst, and the using amount of the catalyst is 1-2% of the mass of methyl formate.
3. The process according to claim 2 for preparing dibutylformamide, characterized in that: the thickness of the fixed bed is 100-150mm.
4. The production process for preparing dibutylformamide according to claim 2, characterized in that: the composite titanium-based lanthanide catalyst takes activated alumina as a porous substrate, titanium monoxide as an auxiliary active material and lanthanum oxide as an active material, and the lanthanum oxide is fixed on the surface of the activated alumina through the titanium monoxide.
5. The process according to claim 1 for preparing dibutylformamide, characterized in that: the reaction steps of the crude dibutylformamide liquid are as follows: b1, placing the fixed bed in a reaction kettle, heating and activating to obtain the reaction kettle with an activated catalyst, wherein the temperature for heating and activating is 200-300 ℃, the time is 2-3h, the atmosphere of the reaction kettle is an inert gas atmosphere, the inert gas is argon or helium, and the flow rate of the inert gas is 20-50mL/min; b2, introducing nitrogen into the reaction kettle to form a nitrogen atmosphere, and then introducing methyl formate and dibutylamine to react until the conversion rate of the methyl formate is 98.8%, wherein the reaction is complete, and the pressure of the nitrogen atmosphere is 0.4-0.6MPa, and the temperature is 230-250 ℃ to obtain a reaction solution; wherein the molar ratio of methyl formate to dibutylamine is 1.
6. The process according to claim 5 for preparing dibutylformamide, characterized in that: the reaction step also comprises b3, settling the reaction solution at constant temperature, and purging with nitrogen to obtain crude dibutylformamide solution and methanol, wherein the temperature of constant temperature settling is 90-100 ℃, and the temperature of nitrogen purging is 80-100 ℃; in the process of constant temperature sedimentation, methanol as a product is converted into a gas state, the dibutylformamide is converted into a liquid state to form gas-liquid separation, and the methanol is recovered at the temperature of 5-10 ℃ in the process of nitrogen purging.
7. The production process for preparing dibutylformamide according to claim 6, characterized in that: the methyl formate is obtained by taking methanol as a raw material through catalytic reaction, and the methanol recycled by b3 can be used as a raw material for preparing the methyl formate.
8. The process according to claim 1 for preparing dibutylformamide, characterized in that: the separation and impurity removal method comprises the following steps:
step 1, placing crude dibutylformamide liquid into an adsorption column for adsorption treatment, wherein the flow rate of the adsorption treatment is 50-100mL/min;
and 2, putting the crude dibutylformamide liquid after adsorption treatment into a rectifying tower for vacuum rectification treatment to obtain high-purity dibutylformamide.
9. The process according to claim 8 for preparing dibutylformamide, characterized in that: the adsorption column in the step 1 is filled with alumina-based adsorbent, the filling amount is 80-90% of the length of the adsorption column, the alumina-based adsorbent is porous particles with the diameter of 5-10mm, and the alumina-based adsorbent takes calcium oxide as an inner core and porous alumina as a surface shell layer.
10. The process according to claim 8 for preparing dibutylformamide, characterized in that: the rectification treatment in the step 2 adopts negative pressure rectification, the temperature is 130-140 ℃, the temperature at the top of the tower is 115-125 ℃, and the pressure is-0.09 to-0.095 MPa.
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| CN103012183A (en) * | 2012-12-18 | 2013-04-03 | 王传良 | Preparation method of N,-N-diethyl-formamide |
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| CN111253274A (en) * | 2020-02-13 | 2020-06-09 | 南京工业大学 | Preparation method of dialkyl formamide |
| CN113979882A (en) * | 2021-11-29 | 2022-01-28 | 宿迁新亚科技有限公司 | Production process for preparing dibutyl formamide |
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| CN103012183A (en) * | 2012-12-18 | 2013-04-03 | 王传良 | Preparation method of N,-N-diethyl-formamide |
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