CN113979882A

CN113979882A - Production process for preparing dibutyl formamide

Info

Publication number: CN113979882A
Application number: CN202111431008.XA
Authority: CN
Inventors: 吕晓梅; 崔德文; 张明; 徐为民
Original assignee: Suqian Xinya Technology Co ltd
Current assignee: Suqian Xinya Technology Co ltd
Priority date: 2021-11-29
Filing date: 2021-11-29
Publication date: 2022-01-28

Abstract

The invention belongs to the technical field of synthesis, and particularly relates to a production process for preparing dibutylformamide. The invention solves the blank of the N, N-dibutylformamide, and the high-purity dibutylformamide is obtained by taking methyl formate and dibutylamine as raw materials through solid-phase catalytic heat-preservation reaction and three-stage rectification treatment, thereby not only greatly improving the reaction efficiency and shortening the process time, but also providing the product quality and yield, and further providing the economic benefit of the enterprise market.

Description

Production process for preparing dibutyl formamide

Technical Field

The invention belongs to the technical field of synthesis, and particularly relates to a production process for preparing dibutyl formamide.

Background

N, N-Dibutylformamide, named N, N-Dibutylformamide in English, named N, N-di-N-butylformamide in Chinese, abbreviated as Dibutylformamide herein, with CAS number of 761-65-9, molecular formula of C9H19NO, boiling point of 240 deg.C 766mmHg, flash point of 97.7 deg.C, specific gravity of 0.865g/cm³. Has irritation and avoids direct contact, and is a chemical intermediate. N, N-dibutylformamide is a carboxamide compound. Formylated amine compounds in chemical engineering and medicineHas wide application in the field of product production. However, no report on N, N-dibutylformamide exists at present.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a production process for preparing dibutyl formamide, which solves the blank of N, N-dibutyl formamide, and the high-purity dibutyl formamide is obtained by taking methyl formate and dibutylamine as raw materials through solid-phase catalytic heat-preservation reaction and three-stage rectification treatment, so that the reaction efficiency is greatly improved, the process time is shortened, the product quality and the yield are improved, and the economic benefit of the enterprise market is further provided.

In order to achieve the technical purpose, the technical scheme of the invention is as follows:

a process for preparing dibutylformamide uses methyl formate and dibutylamine as raw materials to react to obtain reaction liquid, which is then treated by thermal insulation and three-stage rectification and separated to obtain dibutylformamide.

The reaction steps of the reaction solution are as follows: a1, introducing methyl formate and dibutylamine into a reaction kettle containing a catalyst; the molar ratio of the methyl formate to the dibutyl ester is 1: 2; a2, introducing nitrogen to adjust the reaction pressure, and reacting to obtain a mixed solution of the dibutylformamide and the methanol, wherein the reaction pressure is 0.1-0.2MPa, and the reaction temperature is 80-95 ℃.

Further, the catalyst adopts a magnetic catalyst, ferroferric oxide is used as an inner core of the catalyst, an active matter is covered on the surface of the catalyst, the active matter is a palladium-lanthanum composite oxide, and the preparation method of the catalyst comprises the following steps: b1, spraying the ferroferric oxide fine powder into a reaction kettle, and standing for 20-30min to obtain activated ferroferric oxide fine powder, wherein the atmosphere in the reaction kettle is a mixed gas of hydrogen chloride and nitrogen, the volume ratio of the hydrogen chloride to the nitrogen is 3:7-8, and the standing temperature is 100-; in the treatment process, an acidification system is formed on the surface of the ferroferric oxide, an acidic activation state is formed on the surface of the ferroferric oxide, and the amount of the ferroferric oxide and hydrogen chloride is controlled to form a reaction system with insufficient hydrogen chloride, wherein generally speaking, the molar weight of the hydrogen chloride is 5-10% of that of the ferroferric oxide; b2, adding dichlorodimethylsilane into anhydrous ether to form a dilute solution, spraying the dilute solution into a ferroferric oxide reaction kettle for reaction, standing at a constant temperature for 10-20min, and then purging with nitrogen to obtain silane-coated ferroferric oxide, wherein the addition amount of the dichlorodimethylsilane is 30-50g/L in the anhydrous ether, the spraying speed is 3-6mL/min, the addition amount of the dichlorodimethylsilane is 5-10% of the molar amount of the ferroferric oxide, the reaction temperature is 60-70 ℃, dry nitrogen is adopted for purging, and the nitrogen temperature is 100-110 ℃; b3, adding palladium acetate and lanthanum acetate into the diethyl ether-benzene mixed solution, and adding ethyl cellulose and ammonium carbonate to uniformly form a suspension, wherein the concentration of the palladium acetate is 20-40g/L, the concentration of the lanthanum acetate is 2-8g/L, the volume ratio of diethyl ether to benzene in the diethyl ether-benzene mixed solution is 5:1-2, the addition amount of the ethyl cellulose is 1-3g/L, and the concentration of the ammonium carbonate is 0.3-0.6 g/L; b4, uniformly coating the suspension on the surface of silane-coated ferroferric oxide, and drying at a constant temperature for 30-50min to obtain coated particles, wherein the coating amount is 1-2mL/cm2, the drying temperature at the constant temperature is 40-50 ℃, ether in the suspension is converted into steam to be directly evaporated in the process, the steam is volatile liquid based on benzene, gradual volatilization is formed, ethyl cellulose is formed as an adhesive in the drying process, and a surface film with ammonium carbonate, palladium acetate and lanthanum acetate as dopants is formed; b5, placing the coated particles into a reaction kettle, standing for 20-30min at constant temperature, and then sintering at constant temperature for 20-40 min; obtaining a crude catalyst, placing the crude catalyst into an ethanol water solution, performing ultrasonic dispersion for 10-20min, performing magnetic separation to obtain a magnetic catalyst, wherein the temperature of constant-temperature standing is 80-100 ℃, the temperature of constant-temperature sintering treatment is 200-250 ℃, the volume concentration of ethanol in the ethanol water solution is 40-60%, the temperature of ultrasonic dispersion is 20-40 ℃, and the ultrasonic frequency is 50-70 kHz. The magnetic catalyst can improve the separability of the catalyst by utilizing magnetism, and the ferroferric oxide is matched with silane to form an insoluble core system, so that palladium and lanthanum serving as active substances can be completely fixed.

Further, the ammonium carbonate is micro-nano ammonium carbonate, and in the formation of the ethylcellulose-based film, the ammonium carbonate as a solid of a suspension cannot be dissolved in a liquid material to form uniform dispersion, so that the granular ammonium carbonate is very easy to distribute unevenly based on the particle size problem, and therefore, the micro-nano ammonium carbonate has good dispersibility and forms pseudo-solubility in the suspension, namely, the particles are extremely small and form stable suspension dispersion in a solvent; further, the preparation method of the micro-nano ammonium carbonate comprises the following steps: c1, adding ammonium carbonate into absolute ethyl alcohol to be uniformly dispersed to obtain a suspension; the mass ratio of the ammonium carbonate to the absolute ethyl alcohol is 5: 1-2; and c2, placing the suspension into a sealed ball mill for ball milling and extrusion at constant temperature, slowly flushing steam into the diethyl ether-ethanol mixed solution to obtain micro-nano-grade precipitates, filtering and washing to obtain micro-nano-grade ammonium carbonate, wherein the pressure of the constant-temperature ball milling and extrusion is 0.7-0.9MPa, the temperature is 80-90 ℃, the flushing speed of the steam is 1-3mL/min, the steam is directly introduced into the mixed solution, the temperature of the diethyl ether-ethanol mixed solution is 10-20 ℃, and the volume ratio of diethyl ether to ethanol in the diethyl ether-ethanol mixed solution is 5: 2-4.

And the heat preservation treatment is to introduce the mixed solution into a buffer device for standing at a constant temperature, detect the mixed solution until the conversion rate of the methyl formate is 98.8 percent, and consider the reaction to be complete to obtain a mixed reaction solution, wherein the temperature for standing at the constant temperature is 80-95 ℃, and the pressure is 0.1-0.2 MPa. Further, the mixed reaction solution is subjected to magnetic filtration, and the catalyst is taken out through magnetic adsorption.

Furthermore, the molar ratio of the dibutylamine to the methyl formate in the methyl formate reactor is 1:2, the reaction temperature is 80-95 ℃, and the pressure is controlled to be 0.1-0.2Mpa by introducing nitrogen through a pressure stabilizing valve; then, directly introducing dibutylamine and methyl formate into a dibutylcarboxamide reactor to avoid the influence of pressure on the reaction process; and then the temperature in the reaction buffer tank is controlled to be about 85 ℃ by hot water circulation in a jacket of the reaction buffer tank through a progressive interlayer of the reaction buffer tank, and the pressure is controlled to be 0.1-0.2Mpa, so that the continuous production can be realized.

The three-stage rectification comprises the following steps:

step 1, conveying the mixed reaction liquid to a primary rectifying tower through a primary rectifying tower feed pump for separation operation, wherein methanol is obtained at the top of the primary rectifying tower, and crude dibutylformamide is obtained at the bottom of the primary rectifying tower; the temperature of the tower kettle of the primary rectifying tower is about 165 ℃, the temperature of the tower top is 65 ℃, and the methanol obtained from the tower top of the primary rectifying tower is sent into a methanol recovery tank; separating methanol by a primary rectifying tower, detecting the content of the dibutylformamide in the tower top of the primary rectifying tower, and controlling the index of the dibutylformamide to be less than or equal to 0.2 percent so as to control the yield of the dibutylformamide;

step 2, detecting the crude dibutylformamide liquid in the first-stage rectifying tower kettle, and when the content of the dibutylformamide is detected to be more than or equal to 95%, enabling the crude dibutylformamide liquid to enter a second-stage rectifying tower through a second-stage rectifying tower feeding pump, removing light components in the second-stage rectifying tower under a vacuum condition, and obtaining a second-stage rectifying tower kettle liquid from the second-stage rectifying tower kettle; the secondary rectifying tower adopts negative pressure rectification, the temperature of a tower kettle is 138 ℃, the temperature of a tower top is 110 ℃, and the pressure of the tower top is controlled to be-0.08 to-0.09 Mpa; the secondary rectifying tower is mainly used for separating light components from the dibutylformamide product and separating the light components back to the buffer device, and the separation effect is good and the purity of the final product is improved by the principle of vacuum suction;

step 3, detecting the bottom liquid of the second-stage rectifying tower, and when the mass fraction of the dibutylformamide is larger than or equal to 99.0%, sending the bottom liquid of the second-stage rectifying tower into a third-stage rectifying tower through a feed pump of the third-stage rectifying tower, performing third-stage rectification under vacuum, and collecting a product dibutylformamide from the tower top; the third-stage rectifying tower adopts negative pressure rectification, the temperature of the tower bottom is 140 ℃ plus 130 ℃, and the temperature of the tower top is 115 ℃ plus 125 ℃; the pressure at the top of the tower is controlled between-0.09 MPa and-0.095 MPa; the three-stage rectifying tower is mainly used for the final refining operation of the dibutylformamide product, and simultaneously, the dibutylformamide product is further purified at high temperature under vacuum, so that the dibutylformamide with less impurities and high purity is obtained.

Further, the methanol and formic acid are subjected to solid-phase catalytic reaction to obtain methyl formate.

The temperature of the solid-phase catalytic reaction is 40-45 ℃, the pressure is normal pressure, and the catalyst is magnetic copper sulfate; the magnetic copper sulfate takes copper sulfate as a surface layer and a ferroferric oxide core as a core.

From the above description, it can be seen that 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 taking methyl formate and dibutylamine as raw materials through solid-phase catalytic heat-preservation reaction and three-stage rectification treatment, thereby not only greatly improving the reaction efficiency and shortening the process time, but also providing the product quality and yield, and further providing the economic benefit of the enterprise market.

2. The invention utilizes methanol as the raw material of methyl formate, thereby greatly reducing the usage amount of methyl formate, realizing the recycling of methanol, playing the role of emission reduction and simultaneously reducing the production cost.

3. The invention utilizes the magnetic catalyst as the amidation catalyst, the catalyst with the shell-core structure not only utilizes the high-efficiency catalytic system of palladium and lanthanum to realize the improvement of the yield, but also utilizes the magnetism as the core to facilitate the recycling.

Detailed Description

The present invention is described in detail with reference to examples, but the present invention is not limited to the claims.

Example 1

The reaction steps of the reaction solution are as follows: a1, introducing methyl formate and dibutylamine into a reaction kettle containing a catalyst; the molar ratio of the methyl formate to the dibutyl ester is 1: 2; a2, introducing nitrogen to adjust the reaction pressure, and reacting to obtain a mixed solution of the dibutylformamide and the methanol, wherein the reaction pressure is 0.1MPa, and the reaction temperature is 80 ℃.

The catalyst takes ferroferric oxide as a core, and the surface of the catalyst is covered with palladium-lanthanum composite oxide, and the specific preparation method comprises the following steps: b1, spraying the ferroferric oxide fine powder into a reaction kettle, and standing for 20min to obtain activated ferroferric oxide fine powder, wherein the atmosphere in the reaction kettle is a mixed gas of hydrogen chloride and nitrogen, the volume ratio of the hydrogen chloride to the nitrogen is 3:7, and the standing temperature is 100 ℃; the molar weight of the hydrogen chloride is 5 percent of that of the ferroferric oxide; b2, adding dichlorodimethylsilane into anhydrous ether to form a dilute solution, spraying the dilute solution into a ferroferric oxide reaction kettle for reaction, standing at a constant temperature for 10min, and then blowing nitrogen to obtain silane-coated ferroferric oxide, wherein the addition amount of the dichlorodimethylsilane is 30g/L in the anhydrous ether, the spraying speed is 3mL/min, the addition amount of the dichlorodimethylsilane is 5% of the molar amount of the ferroferric oxide, the reaction temperature is 60 ℃, the blowing adopts dry nitrogen, and the nitrogen temperature is 100 ℃; b3, adding palladium acetate and lanthanum acetate into the diethyl ether-benzene mixed solution, and adding ethyl cellulose and ammonium carbonate to uniformly form a suspension, wherein the concentration of the palladium acetate is 20g/L, the concentration of the lanthanum acetate is 2g/L, the volume ratio of diethyl ether to benzene in the diethyl ether-benzene mixed solution is 5:1, the addition amount of the ethyl cellulose is 1g/L, and the concentration of the ammonium carbonate is 0.3 g/L; b4, uniformly coating the suspension on the surface of silane-coated ferroferric oxide, drying at constant temperature for 30min to obtain coated particles, wherein the coating amount is 1mL/cm2, the drying temperature at constant temperature is 40 ℃, b5, placing the coated particles into a reaction kettle, standing at constant temperature for 20min, and then sintering at constant temperature for 20 min; and (3) obtaining a crude catalyst, placing the crude catalyst into an ethanol water solution, performing ultrasonic dispersion for 10min, performing magnetic separation to obtain the magnetic catalyst, standing at the constant temperature of 80 ℃, sintering at the constant temperature of 200 ℃, performing ultrasonic dispersion at the ultrasonic dispersion temperature of 20 ℃ and the ultrasonic frequency of 50kHz, wherein the volume concentration of ethanol in the ethanol water solution is 40%. The preparation method of the ammonium carbonate comprises the following steps: c1, adding ammonium carbonate into absolute ethyl alcohol to be uniformly dispersed to obtain a suspension; the mass ratio of the ammonium carbonate to the absolute ethyl alcohol is 5: 1; and c2, placing the suspension into a sealed ball mill for ball milling and extrusion at constant temperature, slowly flushing steam into the diethyl ether-ethanol mixed solution to obtain micro-nano-grade precipitates, filtering and washing to obtain micro-nano-grade ammonium carbonate, wherein the pressure of the constant-temperature ball milling and extrusion is 0.7MPa, the temperature is 80 ℃, the flushing speed of the steam is 1mL/min, the steam is directly introduced into the mixed solution, the temperature of the diethyl ether-ethanol mixed solution is 10 ℃, and the volume ratio of the diethyl ether to the ethanol in the diethyl ether-ethanol mixed solution is 5: 2.

And the heat preservation treatment is to introduce the mixed solution into a buffer device for standing at a constant temperature, detect the mixed solution until the conversion rate of methyl formate is 98.8 percent, consider the reaction to be complete, obtain a mixed reaction solution, allow the mixed reaction solution to stand at the constant temperature of 80 ℃ under the pressure of 0.1MPa, perform magnetic filtration on the mixed reaction solution, and take out the catalyst through magnetic adsorption.

The three-stage rectification comprises the following steps:

step 1, conveying the mixed reaction liquid to a primary rectifying tower through a primary rectifying tower feed pump for separation operation, wherein methanol is obtained at the top of the primary rectifying tower, and crude dibutylformamide is obtained at the bottom of the primary rectifying tower; the temperature of the tower kettle of the primary rectifying tower is about 165 ℃, the temperature of the tower top is 65 ℃, and the methanol obtained from the tower top of the primary rectifying tower is sent into a methanol recovery tank;

step 2, detecting the crude dibutylformamide liquid in the first-stage rectifying tower kettle, wherein the detected content of the dibutylformamide is 95%, the crude dibutylformamide liquid enters a second-stage rectifying tower through a second-stage rectifying tower feeding pump, light components are removed from the second-stage rectifying tower under a vacuum condition, and a second-stage rectifying tower kettle liquid is obtained from the second-stage rectifying tower kettle; the secondary rectifying tower adopts negative pressure rectification, the temperature of a tower kettle is 138 ℃, the temperature of a tower top is 110 ℃, and the pressure of the tower top is controlled to be-0.08 to-0.09 Mpa;

step 3, detecting the bottom liquid of the second-stage rectifying tower, and when the mass fraction of the dibutylformamide is 99.0 percent through detection, sending the bottom liquid of the second-stage rectifying tower into a third-stage rectifying tower through a feed pump of the third-stage rectifying tower, performing third-stage rectification under vacuum, and collecting a product of the dibutylformamide from the tower top; the third-stage rectifying tower adopts negative pressure rectification, the temperature of a tower kettle is 130 ℃, and the temperature of a tower top is 115 ℃; the pressure at the top of the tower is controlled between-0.09 MPa and-0.095 MPa.

The temperature of the solid-phase catalytic reaction is 40 ℃, the pressure is normal pressure, and the catalyst is magnetic copper sulfate; the magnetic copper sulfate takes copper sulfate as a surface layer and a ferroferric oxide core as a core.

Example 2

The reaction steps of the reaction solution are as follows: a1, introducing methyl formate and dibutylamine into a reaction kettle containing a catalyst; the molar ratio of the methyl formate to the dibutyl ester is 1: 2; a2, introducing nitrogen to adjust the reaction pressure, and reacting to obtain a mixed solution of the dibutylformamide and the methanol, wherein the reaction pressure is 0.2MPa, and the reaction temperature is 95 ℃.

The catalyst takes ferroferric oxide as a core, and the surface of the catalyst is covered with palladium-lanthanum composite oxide, and the specific preparation method comprises the following steps: b1, spraying the ferroferric oxide fine powder into a reaction kettle, and standing for 30min to obtain activated ferroferric oxide fine powder, wherein the atmosphere in the reaction kettle is a mixed gas of hydrogen chloride and nitrogen, the volume ratio of the hydrogen chloride to the nitrogen is 3:8, and the standing temperature is 110 ℃; the molar weight of the hydrogen chloride is 10 percent of that of the ferroferric oxide; b2, adding dichlorodimethylsilane into anhydrous ether to form a dilute solution, spraying the dilute solution into a ferroferric oxide reaction kettle for reaction, standing at a constant temperature for 20min, and then blowing nitrogen to obtain silane-coated ferroferric oxide, wherein the addition amount of the dichlorodimethylsilane is 50g/L in the anhydrous ether, the spraying speed is 6mL/min, the addition amount of the dichlorodimethylsilane is 10% of the molar amount of the ferroferric oxide, the reaction temperature is 70 ℃, the blowing adopts dry nitrogen, and the nitrogen temperature is 110 ℃; b3, adding palladium acetate and lanthanum acetate into the diethyl ether-benzene mixed solution, and adding ethyl cellulose and ammonium carbonate to uniformly form suspension, wherein the concentration of the palladium acetate is 40g/L, and the method comprises the following steps ofThe concentration of lanthanum acetate is 8g/L, the volume ratio of diethyl ether to benzene in the diethyl ether-benzene mixed solution is 5:2, the addition amount of ethyl cellulose is 3g/L, and the concentration of ammonium carbonate is 0.6 g/L; b4, uniformly coating the suspension on the surface of silane-coated ferroferric oxide, and drying at constant temperature for 50min to obtain coated particles, wherein the coating amount is 2mL/cm²B5, placing the coated particles into a reaction kettle, standing for 30min at constant temperature, and then sintering at constant temperature for 40 min; and (3) obtaining a crude catalyst, placing the crude catalyst into an ethanol water solution, performing ultrasonic dispersion for 20min, and performing magnetic separation to obtain the magnetic catalyst, wherein the temperature for constant-temperature standing is 100 ℃, the temperature for constant-temperature sintering treatment is 250 ℃, the volume concentration of ethanol in the ethanol water solution is 60%, the temperature for ultrasonic dispersion is 40 ℃, and the ultrasonic frequency is 70 kHz. The preparation method of the ammonium carbonate comprises the following steps: c1, adding ammonium carbonate into absolute ethyl alcohol to be uniformly dispersed to obtain a suspension; the mass ratio of the ammonium carbonate to the absolute ethyl alcohol is 5: 2; and c2, placing the suspension into a sealed ball mill for ball milling and extrusion at constant temperature, slowly flushing steam into the diethyl ether-ethanol mixed solution to obtain micro-nano-grade precipitates, filtering and washing to obtain micro-nano-grade ammonium carbonate, wherein the pressure of the constant-temperature ball milling and extrusion is 0.9MPa, the temperature is 90 ℃, the flushing speed of the steam is 3mL/min, the steam is directly introduced into the mixed solution, the temperature of the diethyl ether-ethanol mixed solution is 20 ℃, and the volume ratio of the diethyl ether to the ethanol in the diethyl ether-ethanol mixed solution is 5: 4.

And the heat preservation treatment is to introduce the mixed solution into a buffer device for standing at a constant temperature, detect the mixed solution until the conversion rate of methyl formate is 98.8 percent, consider the reaction to be complete, obtain a mixed reaction solution, allow the mixed reaction solution to stand at the constant temperature of 95 ℃ under the pressure of 0.2MPa, perform magnetic filtration on the mixed reaction solution, and take out the catalyst through magnetic adsorption.

The three-stage rectification comprises the following steps:

step 2, detecting the crude dibutyl formamide liquid in the kettle of the primary rectifying tower, and after detecting that the content of dibutyl formamide is 95.5%, feeding the crude dibutyl formamide liquid into a secondary rectifying tower through a feeding pump of the secondary rectifying tower, removing light components in the secondary rectifying tower under a vacuum condition, and obtaining the kettle liquid of the secondary rectifying tower from the kettle of the secondary rectifying tower; the secondary rectifying tower adopts negative pressure rectification, the temperature of a tower kettle is 138 ℃, the temperature of a tower top is 110 ℃, and the pressure of the tower top is controlled to be-0.08 to-0.09 Mpa;

step 3, detecting the bottom liquid of the second-stage rectifying tower, and when the mass fraction of the dibutylformamide is larger than or equal to 99.3%, sending the bottom liquid of the second-stage rectifying tower into a third-stage rectifying tower through a feed pump of the third-stage rectifying tower, performing third-stage rectification under vacuum, and collecting a product dibutylformamide from the tower top; the third-stage rectifying tower adopts negative pressure rectification, the temperature of a tower kettle is 140 ℃, and the temperature of a tower top is 125 ℃; the pressure at the top of the tower is controlled between-0.09 MPa and-0.095 MPa.

The temperature of the solid-phase catalytic reaction is 45 ℃, the pressure is normal pressure, and the catalyst is magnetic copper sulfate; the magnetic copper sulfate takes copper sulfate as a surface layer and a ferroferric oxide core as a core.

EXAMPLE 3

The reaction steps of the reaction solution are as follows: a1, introducing methyl formate and dibutylamine into a reaction kettle containing a catalyst; the molar ratio of the methyl formate to the dibutyl ester is 1: 2; a2, introducing nitrogen to adjust the reaction pressure, and reacting to obtain a mixed solution of the dibutylformamide and the methanol, wherein the reaction pressure is 0.1MPa, and the reaction temperature is 85 ℃.

The catalyst takes ferroferric oxide as a core, and the surface of the catalyst is covered with palladium-lanthanum composite oxide, and the specific preparation method comprises the following steps: b1, spraying the ferroferric oxide fine powder into a reaction kettle, and standing for 25min to obtain activated ferroferric oxide fine powder, wherein the atmosphere in the reaction kettle is a mixed gas of hydrogen chloride and nitrogen, the volume ratio of the hydrogen chloride to the nitrogen is 3:8, and the standing temperature is 105 ℃; the molar weight of the hydrogen chloride is 8 percent of that of the ferroferric oxide; b2, adding dichlorodimethylsilane into anhydrous ether to form a dilute solution, spraying the dilute solution into a ferroferric oxide reaction kettle for reaction, standing at a constant temperature for 15min, then blowing nitrogen to obtain silane-coated ferroferric oxide, wherein the addition amount of the dichlorodimethylsilane is 40g/L in the anhydrous ether, the spraying speed is 5mL/min, the addition amount of the dichlorodimethylsilane is 8% of the molar amount of the ferroferric oxide, the reaction temperature is 65 ℃, the blowing adopts dry nitrogen, and the nitrogen temperature is 105 ℃; b3, adding palladium acetate and lanthanum acetate into the diethyl ether-benzene mixed solution, and adding ethyl cellulose and ammonium carbonate to uniformly form a suspension, wherein the concentration of the palladium acetate is 30g/L, the concentration of the lanthanum acetate is 6g/L, the volume ratio of diethyl ether to benzene in the diethyl ether-benzene mixed solution is 5:2, the addition amount of the ethyl cellulose is 2g/L, and the concentration of the ammonium carbonate is 0.5 g/L; b4, uniformly coating the suspension on the surface of silane-coated ferroferric oxide, drying at a constant temperature for 40min to obtain coated particles, wherein the coating amount is 2mL/cm2, the constant-temperature drying temperature is 45 ℃, b5, placing the coated particles into a reaction kettle, standing at a constant temperature for 25min, and then sintering at a constant temperature for 30 min; and (3) obtaining a crude catalyst, placing the crude catalyst into an ethanol water solution, performing ultrasonic dispersion for 15min, performing magnetic separation to obtain the magnetic catalyst, standing at a constant temperature of 90 ℃, sintering at a constant temperature of 240 ℃, performing ultrasonic dispersion at a temperature of 30 ℃ and an ultrasonic frequency of 60kHz, wherein the volume concentration of ethanol in the ethanol water solution is 50%. The preparation method of the ammonium carbonate comprises the following steps: c1, adding ammonium carbonate into absolute ethyl alcohol to be uniformly dispersed to obtain a suspension; the mass ratio of the ammonium carbonate to the absolute ethyl alcohol is 5: 2; and c2, placing the suspension into a sealed ball mill for ball milling and extrusion at constant temperature, slowly flushing steam into the diethyl ether-ethanol mixed solution to obtain micro-nano-grade precipitates, filtering and washing to obtain micro-nano-grade ammonium carbonate, wherein the pressure of the constant-temperature ball milling and extrusion is 0.8MPa, the temperature is 85 ℃, the flushing speed of the steam is 2mL/min, the steam is directly introduced into the mixed solution, the temperature of the diethyl ether-ethanol mixed solution is 15 ℃, and the volume ratio of the diethyl ether to the ethanol in the diethyl ether-ethanol mixed solution is 5: 3.

And the heat preservation treatment is to introduce the mixed solution into a buffer device for standing at a constant temperature, detect the mixed solution until the conversion rate of methyl formate is 98.8 percent, consider the reaction to be complete, obtain a mixed reaction solution, allow the mixed reaction solution to stand at the constant temperature of 85 ℃ under the pressure of 0.2MPa, perform magnetic filtration on the mixed reaction solution, and take out the catalyst through magnetic adsorption.

The three-stage rectification comprises the following steps:

step 1, conveying the mixed reaction liquid to a primary rectifying tower through a primary rectifying tower feed pump for separation operation, wherein methanol is obtained at the top of the primary rectifying tower, and crude dibutylformamide is obtained at the bottom of the primary rectifying tower; the temperature of the tower kettle of the primary rectifying tower is 165 ℃, the temperature of the tower top is 65 ℃, and the methanol obtained from the tower top of the primary rectifying tower is sent to a methanol recovery tank;

step 2, detecting the crude dibutylformamide liquid in the kettle of the primary rectifying tower, and when the content of the dibutylformamide is detected to be 95.8 percent, feeding the crude dibutylformamide liquid into a secondary rectifying tower through a feeding pump of the secondary rectifying tower, removing light components in the secondary rectifying tower under the vacuum condition, and obtaining the kettle liquid of the secondary rectifying tower at the kettle of the secondary rectifying tower; the secondary rectifying tower adopts negative pressure rectification, the temperature of a tower kettle is 138 ℃, the temperature of a tower top is 110 ℃, and the pressure of the tower top is controlled to be-0.08 to-0.09 Mpa;

step 3, detecting the bottom liquid of the second-stage rectifying tower, and when the mass fraction of the dibutylformamide is larger than or equal to 99.4%, sending the bottom liquid of the second-stage rectifying tower into a third-stage rectifying tower through a feed pump of the third-stage rectifying tower, performing third-stage rectification under vacuum, and collecting a product dibutylformamide from the tower top; the third-stage rectifying tower adopts negative pressure rectification, the temperature of the tower bottom is 140 ℃ plus 130 ℃, and the temperature of the tower top is 115 ℃ plus 125 ℃; the pressure at the top of the tower is controlled between-0.09 MPa and-0.095 MPa.

The temperature of the solid-phase catalytic reaction is 43 ℃, the pressure is normal pressure, and the catalyst is magnetic copper sulfate; the magnetic copper sulfate takes copper sulfate as a surface layer and a ferroferric oxide core as a core.

Example 4

The catalyst takes ferroferric oxide as a core, and the surface of the catalyst is covered with palladium-lanthanum composite oxide, and the specific preparation method comprises the following steps: b1, spraying the ferroferric oxide fine powder into a reaction kettle, and standing for 25min to obtain activated ferroferric oxide fine powder, wherein the atmosphere in the reaction kettle is a mixed gas of hydrogen chloride and nitrogen, the volume ratio of the hydrogen chloride to the nitrogen is 3:8, and the standing temperature is 105 ℃; the molar weight of the hydrogen chloride is 8 percent of that of the ferroferric oxide; b2, adding dichlorodimethylsilane into anhydrous ether to form a dilute solution, spraying the dilute solution into a ferroferric oxide reaction kettle for reaction, standing at a constant temperature for 15min, then blowing nitrogen to obtain silane-coated ferroferric oxide, wherein the addition amount of the dichlorodimethylsilane is 40g/L in the anhydrous ether, the spraying speed is 5mL/min, the addition amount of the dichlorodimethylsilane is 8% of the molar amount of the ferroferric oxide, the reaction temperature is 65 ℃, the blowing adopts dry nitrogen, and the nitrogen temperature is 105 ℃; b3, adding palladium acetate and lanthanum acetate into the diethyl ether-benzene mixed solution, and adding ethyl cellulose and ammonium carbonate to uniformly form a suspension, wherein the concentration of the palladium acetate is 30g/L, the concentration of the lanthanum acetate is 6g/L, the volume ratio of diethyl ether to benzene in the diethyl ether-benzene mixed solution is 5:2, the addition amount of the ethyl cellulose is 2g/L, and the concentration of the ammonium carbonate is 0.5 g/L; b4, uniformly coating the suspension on the surface of silane-coated ferroferric oxide, drying at a constant temperature for 40min to obtain coated particles, wherein the coating amount is 1mL/cm2, the constant-temperature drying temperature is 45 ℃, b5, placing the coated particles into a reaction kettle, standing at a constant temperature for 25min, and then sintering at a constant temperature for 40 min; and (3) obtaining a crude catalyst, placing the crude catalyst into an ethanol water solution, performing ultrasonic dispersion for 10min, performing magnetic separation to obtain the magnetic catalyst, standing at a constant temperature of 90 ℃, sintering at a constant temperature of 240 ℃, performing ultrasonic dispersion at a temperature of 30 ℃ and an ultrasonic frequency of 60kHz, wherein the volume concentration of ethanol in the ethanol water solution is 50%. The preparation method of the ammonium carbonate comprises the following steps: c1, adding ammonium carbonate into absolute ethyl alcohol to be uniformly dispersed to obtain a suspension; the mass ratio of the ammonium carbonate to the absolute ethyl alcohol is 5: 1; and c2, placing the suspension into a sealed ball mill for ball milling and extrusion at constant temperature, slowly flushing steam into the diethyl ether-ethanol mixed solution to obtain micro-nano-grade precipitates, filtering and washing to obtain micro-nano-grade ammonium carbonate, wherein the pressure of the constant-temperature ball milling and extrusion is 0.8MPa, the temperature is 85 ℃, the flushing speed of the steam is 2mL/min, the steam is directly introduced into the mixed solution, the temperature of the diethyl ether-ethanol mixed solution is 15 ℃, and the volume ratio of the diethyl ether to the ethanol in the diethyl ether-ethanol mixed solution is 5: 4.

The three-stage rectification comprises the following steps:

step 2, detecting the crude dibutyl formamide liquid in the kettle of the primary rectifying tower, and when the content of dibutyl formamide is detected to be 95.5%, feeding the crude dibutyl formamide liquid into a secondary rectifying tower through a feeding pump of the secondary rectifying tower, removing light components in the secondary rectifying tower under a vacuum condition, and obtaining the kettle liquid of the secondary rectifying tower from the kettle of the secondary rectifying tower; the secondary rectifying tower adopts negative pressure rectification, the temperature of a tower kettle is 138 ℃, the temperature of a tower top is 110 ℃, and the pressure of the tower top is controlled to be-0.08 to-0.09 MPa;

step 3, detecting the bottom liquid of the second-stage rectifying tower, and when the mass fraction of the dibutylformamide is larger than or equal to 99.4%, sending the bottom liquid of the second-stage rectifying tower into a third-stage rectifying tower through a feed pump of the third-stage rectifying tower, performing third-stage rectification under vacuum, and collecting a product dibutylformamide from the tower top; the third-stage rectifying tower adopts negative pressure rectification, the temperature of a tower kettle is 135 ℃, and the temperature of a tower top is 120 ℃; the pressure at the top of the tower is controlled between-0.09 MPa and-0.095 MPa.

Through detection:

the time for mixing the reaction solution to reach 98.8% in examples 1 to 4 is shown in the following table:

examples	Time (h)
		1	37
2	36
		3	34
4	34

The yields of examples 1-4 are as follows:

examples	Yield (%)
		1	99.68
2	99.73
		3	99.72
4	99.73

And taking example 1 as an example, the yield effect of the catalyst which takes ferroferric oxide as the core and is covered with the palladium-lanthanum composite oxide on the surface after being recycled is as follows: (the molar ratio of the dibutylamine to the methyl formate in the methyl formate reactor is 1:2, the reaction temperature is 80-95 ℃, nitrogen is introduced, the pressure is controlled to be 0.1-0.2Mpa by a pressure stabilizing valve, the dibutylamine and the methyl formate are directly introduced into the dibutylcarboxamide reactor to avoid the influence of the pressure on the reaction process, and then the temperature in the reaction buffer tank is controlled to be about 85 ℃ by hot water circulation in a jacket of the reaction buffer tank by a progressive interlayer of the reaction buffer tank, the pressure is controlled to be 0.1-0.2Mpa, and continuous production can be realized)

Examples	Yield (%)
		For the first time	99.68
For the second time	99.68
		The third time	99.67
Fifth time	99.66

The detection result of the product of the example 1 is as follows:

the fifth test result after catalyst recycling is as follows

Through multiple verification, the process for producing the dibutylformamide is effective for improving the implementation of mass production, can achieve continuous production, improves the product quality and yield, and directly improves the economic benefit of enterprise production.

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 appreciated by those skilled in the art that the present invention may be modified or substituted equally as well to achieve the same technical result; as long as the use requirements are met, the method is within the protection scope of the invention.

Claims

1. A production process for preparing dibutyl formamide is characterized by comprising the following steps: methyl formate and dibutylamine are used as raw materials to react to obtain reaction liquid, and the reaction liquid is subjected to heat preservation treatment and three-stage rectification and then is separated to obtain the dibutylformamide.

2. The process according to claim 1 for preparing dibutylformamide, characterized in that: the reaction steps of the reaction solution are as follows: a1, introducing methyl formate and dibutylamine into a reaction kettle containing a catalyst; the molar ratio of the methyl formate to the dibutyl ester is 1: 2; a2, introducing nitrogen to adjust the reaction pressure, and reacting to obtain a mixed solution of the dibutylformamide and the methanol, wherein the reaction pressure is 0.1-0.2MPa, and the reaction temperature is 80-95 ℃.

3. The process according to claim 2 for preparing dibutylformamide, characterized in that: the catalyst adopts a magnetic catalyst, and the catalyst takes ferroferric oxide as a core, and the surface of the catalyst is covered with an active matter.

4. The process according to claim 3 for preparing dibutylformamide, characterized in that: the active matter is palladium-lanthanum composite oxide.

5. The process according to claim 1 for preparing dibutylformamide, characterized in that: and the heat preservation treatment is to introduce the mixed solution into a buffer device for standing at a constant temperature, detect the mixed solution until the conversion rate of the methyl formate is 98.8 percent, and consider the reaction to be complete to obtain a mixed reaction solution, wherein the temperature for standing at the constant temperature is 80-95 ℃, and the pressure is 0.1-0.2 MPa.

6. The process according to claim 5 for preparing dibutylformamide, characterized in that: and carrying out magnetic filtration on the mixed reaction liquid, and taking out the catalyst through magnetic adsorption.

7. The process according to claim 1 for preparing dibutylformamide, characterized in that: the three-stage rectification comprises the following steps:

step 1, conveying the mixed reaction liquid to a primary rectifying tower through a primary rectifying tower feed pump for separation operation, wherein methanol is obtained at the top of the primary rectifying tower, and crude dibutylformamide is obtained at the bottom of the primary rectifying tower;

step 2, detecting the crude dibutylformamide liquid in the first-stage rectifying tower kettle, and when the content of the dibutylformamide is detected to be more than or equal to 95%, enabling the crude dibutylformamide liquid to enter a second-stage rectifying tower through a second-stage rectifying tower feeding pump, removing light components in the second-stage rectifying tower under a vacuum condition, and obtaining a second-stage rectifying tower kettle liquid from the second-stage rectifying tower kettle;

and 3, detecting the bottom liquid of the second-stage rectifying tower, and when the mass fraction of the dibutylformamide is larger than or equal to 99.0%, sending the bottom liquid of the second-stage rectifying tower into a third-stage rectifying tower through a feed pump of the third-stage rectifying tower, performing third-stage rectification under vacuum, and collecting the product dibutylformamide from the tower top.

8. The process according to claim 7 for preparing dibutylformamide, characterized in that: the temperature of the tower kettle of the primary rectifying tower in the step 1 is about 165 ℃, the temperature of the tower top is 65 ℃, and the methanol obtained from the tower top of the primary rectifying tower is sent to a methanol recovery tank.

9. The process according to claim 7 for preparing dibutylformamide, characterized in that: the secondary rectifying tower in the step 2 adopts negative pressure rectification, the temperature of a tower kettle is 138 ℃, the temperature of a tower top is 110 ℃, and the pressure of the tower top is controlled to be-0.08 to-0.09 Mpa.

10. The process according to claim 7 for preparing dibutylformamide, characterized in that: the third-stage rectifying tower in the step 3 adopts negative pressure rectification, the temperature of the tower kettle is 130-140 ℃, and the temperature of the tower top is 115-125 ℃; the pressure at the top of the tower is controlled between-0.09 MPa and-0.095 MPa; the three-stage rectifying tower is mainly used for the final refining operation of the dibutylformamide product, and simultaneously, the dibutylformamide product is further purified at high temperature under vacuum, so that the dibutylformamide with less impurities and high purity is obtained.