Method for continuously producing N-alkylaniline compounds from nitrobenzene compounds and ketones

Abstract

The invention discloses a method for continuously producing N-alkylaniline compounds from nitrobenzene compounds and ketones, which comprises the following steps: mixing the nitrobenzene compounds and the ketones to obtain a raw material mixture, preheating the raw material mixture and hydrogen to 60-80 DEG C, and reacting for 2-4 hours; continuously introducing the raw material mixture and hydrogen into a reaction tube A at the temperature of 60-80 DEG C for reaction, introducing an obtained primary catalytic mixture into a reaction tube B at the temperature of 80-100 DEG C through a pipeline for reaction, and introducing an obtained secondary catalytic mixture into a reaction tube C at the temperature of 100-160 DEG C through a pipeline for reaction; the obtained tertiary catalytic mixture is subjected to cooling, gas-liquid separation and purification, and then the N-alkyl arylamine compound is obtained. According to the continuous chemical process provided by the invention, cyclic utilization of all materials can be realized, the production cost is reduced, and solid acid is used for replacing liquid acid, so that corrosion to the device is reduced; and moreover, the production efficiency is improved, and the advantages of high yield and high efficiency are achieved.

Description

Technical Field

[0001] The invention relates to the field of fine chemical production, and in particular to a method for continuously producing N-alkylaniline compounds from nitrobenzene compounds and ketones. Background Art

[0002] N-alkylaniline compounds are important fine chemical products and intermediates for pesticides, medicines, dyes, etc. The chemical formula is C x H y N1, the structural formula is formula 1.

[0003]

[0004] There are many existing methods for synthesizing N-alkylaniline compounds. The reaction is mainly divided into two steps of hydrogenation and condensation in a reactor. First, nitrobenzene compounds and aldehydes and ketones are mixed, a catalyst is added, H2 is introduced, and the reaction pressure is adjusted. The product is alkylaniline through hydrogenation and condensation reaction. For example, as shown in Formula 2 below, the method is that nitrobenzene compounds and ketones react under the catalysis of a catalyst to generate an intermediate product, an aromatic amine intermediate, and the aromatic amine intermediate continues to undergo a condensation reaction under the catalysis of the catalyst to generate an aromatic amine imine, and then a hydrogenation reaction is performed to generate alkylaniline.

[0005]

[0006] At present, the industry often adopts the one-pot production of kettle reaction. For example, the patent with publication number CN104250215A discloses a kettle synthesis method of N-(1-ethylpropyl)-3,4-dimethylaniline, which includes: 3,4-dimethylnitrobenzene, hydrogen and 3-pentanone react in a reactor under the action of multiple catalysts at a reaction temperature of 40-55°C and a pressure of 0.1-0.5MPa. The types of catalysts for this reaction include: (a) platinum carbon catalyst; (b) phosphoric acid-sodium dihydrogen phosphate buffer solution, and the pH value of the buffer solution is 2.5-3.5. The platinum content in the platinum carbon catalyst is 2%-4%, and the yield of the product N-(1-ethylpropyl)-3,4-dimethylaniline under optimized conditions reaches 99.8%. This system requires the addition of liquid acid, which has problems such as equipment corrosion, and phosphoric acid is a substance that eutrophicates water bodies, and it is difficult to handle in industrial applications. Patent publication number CN101302168A discloses a method for preparing N-(1-ethylpropyl)-3,4-dimethylaniline by a two-step process with o-xylene. O-xylene is put into a mixed acid reactor, the temperature is controlled at 20-25°C, the molar ratio of the reaction materials is controlled, and the substance obtained by the reaction is reacted with 3-pentanone under the action of a catalyst to obtain the target product. The materials of this method are recycled, but liquid acid needs to be added in the production process, and there are problems such as equipment corrosion. The patent with publication number CN101891631A discloses a method for synthesizing the intermediate of dimetholine, the final product of N-(1-ethylpropyl)-3,4-dimethylaniline, as shown in Formula 3 below. The method mainly uses meta-halogenated o-xylene and 3-pentylamine as raw materials, and the catalyst is one of cuprous iodide and cuprous oxide, meta-halogenated o-xylene: 3-pentylamine = 1: 1-50, the temperature is 80-120°C, and the amination reaction is carried out by heating in the presence of the catalyst, and then the nitration reaction is carried out to prepare N-(1-ethylpropyl)-3,4-dimethylaniline. This method avoids the process of nitration reaction of o-xylene in the traditional process. However, this process generates hydrogen halide, and an acid binding agent needs to be added (the acid binding agent will react to form salts, which will affect the balance of the reaction and increase the difficulty of wastewater treatment).

[0007]

[0008] The above-mentioned kettle reaction production process has the advantages of high conversion rate and high yield, and can achieve certain large-scale production, but because it produces certain waste, has a large liquid holding capacity, and is a hydrogenation reaction, there is a certain safety production risk, and the kettle reaction production needs to add liquid acid, which will cause certain corrosion to the equipment. The patent of publication number CN105348113A discloses a continuous production device and method of N-(1-ethylpropyl)-3,4-dimethylaniline, which is to catalyze hydrogenation of 4-nitro-o-xylene and 3-pentanone in a hydrogenation reactor, and then obtain N-(1-ethylpropyl)-3,4-dimethylaniline through a falling film evaporation system. In this process, it is necessary to add C2-12 carboxylic acid or sulfonic acid, and the use of these acids requires separation of waste acid in the product, and there is a waste acid treatment process, and the presence of these waste acids will react chemically with Raney nickel or Pt-Pd / C, Pd / C, causing the loss of metal components. In addition, the mechanical strength of Raney nickel or Pt-Pd / C, Pd / C used in this patent is not high, which will lead to structural damage during long-term use, pulverization leading to increased bed pressure drop, metal loss and bringing heavy metals into subsequent products. Summary of the invention

[0009] The object of the present invention is to provide a method for continuously producing N-alkylaniline compounds from nitrobenzene compounds and ketones. By improving the reaction device and using a solid acid catalyst, the use of liquid acid is avoided, the production efficiency is improved, the continuity and automation of the reaction process are achieved, the production efficiency is improved, and the method has broad industrial prospects.

[0010] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0011] A method for continuously producing N-alkylaniline compounds from nitrobenzene compounds and ketones, the device used in the method comprises a fixed bed reactor, the fixed bed reactor is composed of a reaction tube A, a reaction tube B, and a reaction tube C connected in series from top to bottom through a pipeline; the reaction tube A, the reaction tube B, and the reaction tube C are all filled with a supported catalyst, the supported catalyst comprises a carrier and an active component, the carrier is selected from one or more combinations of activated carbon, metal oxides, molecular sieves, and MXenes, and the active component is selected from one or more combinations of Fe, Ni, Cu, Zn, Mn, La, Pt, Pd, and Au;

[0012] The method comprises the following steps: mixing nitrobenzene compounds and ketone compounds in a molar ratio of 1:10-1 to obtain a raw material mixture, preheating the raw material mixture and hydrogen to 60-80°C, then continuously introducing the raw material mixture and hydrogen into a reaction tube A with a temperature set at 60-80°C for reaction, controlling the introduced hydrogen pressure to be 1-2MPa, the obtained primary catalytic mixture entering a reaction tube B with a temperature set at 80-100°C through a pipeline for reaction, the obtained secondary catalytic mixture entering a reaction tube C with a temperature set at 100-160°C through a pipeline for reaction, cooling the obtained tertiary catalytic mixture, performing gas-liquid separation and purification to obtain N-alkyl aromatic amine compounds; during the reaction process, the reaction temperatures of the reaction tubes A, B and C are successively increased, and the volume space velocity of the liquid is controlled to be equal to the volume flow rate of the raw material mixture (20°C, m 3 ·h -1 ) / catalyst volume (m 3 )=(0.6-12)×10 -3 h -1 , where the catalyst volume is based on the total volume of the catalyst in reaction tubes A, B, and C.

[0013] Preferably, the nitrobenzene compound is 3,4-dimethylnitrobenzene, and the ketone compound is 3-pentanone.

[0014] Preferably, the catalyst in the reaction device is in granular form, which is beneficial to improving mass transfer efficiency.

[0015] Preferably, the pressure of the hydrogen introduced is controlled to be 0.8-1.2 MPa.

[0016] As a preference, the volumetric space velocity of the liquid is controlled to be (1-1.5)×10 -3 h -1 .

[0017] Preferably, the reaction tube A, reaction tube B and reaction tube C are all reaction tubes with circular cross-sections and smooth inner walls, which effectively reduces the problem of material backmixing in the reaction device, is beneficial to improving mass transfer efficiency, and is easy to maintain and clean.

[0018] Preferably, the tail gas obtained after gas-liquid separation is recycled after tail gas treatment.

[0019] Preferably, the liquid product obtained after gas-liquid separation is a mixture of N-alkyl aromatic amine compounds and excess ketone compounds obtained after the reaction of nitrobenzene compounds and ketone compounds, and the ketone compounds are recovered by distillation and recycled.

[0020] Compared with the prior art, the present invention has the following beneficial effects: the continuous process provided by the present invention can realize the recycling of various materials, reduce production costs, and use solid acid instead of liquid acid to avoid the use of liquid acid, thereby reducing corrosion to the device. In addition, the continuous process is used to replace the traditional kettle reaction, which also improves the production efficiency, avoids the shortcomings of batch production of kettle reaction in traditional production, and has the advantages of high output and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a gas chromatography analysis report of the product prepared in Example 1;

[0022] Figure 2 The present invention provides a device for continuous production of N-alkylanilines, wherein 1 is a raw material supply device, 2 is a high-pressure pump, 3 is a stop valve, 4 is a three-way valve, 5 is a hydrogen gas cylinder, 10 is a nitrogen gas cylinder, 6, 11 are pressure reducing valves, 7, 12 are precision electronic flow meters, 8, 13 are stop valves, 9, 14 are check valves, 15 are heaters, 16 are reaction tubes A, 17 are reaction tubes B, 18 are reaction tubes C, 19 are condensers, 20 are storage tanks, 21 are stop valves, 22 are collection devices, 23 are back pressure valves, and 24 are tail gas treatment devices. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] like Figure 2 A fixed bed device for continuously synthesizing N-(1-ethylpropyl)-3,4-dimethylaniline is shown, comprising a raw material supply device 1, a nitrogen supply device, a hydrogen supply device, a fixed bed reactor, a condenser 19, a storage tank 20 and a collecting device 22;

[0025] The hydrogen supply device comprises a hydrogen cylinder 5, a pressure reducing valve 6, a precision electronic flow meter 7, a stop valve 8 and a check valve 9 connected in sequence through pipelines, and the nitrogen supply device comprises a nitrogen cylinder 10, a pressure reducing valve 11, a precision electronic flow meter 12, a stop valve 13 and a check valve 14 connected in sequence through pipelines. The pipelines of the hydrogen supply device and the nitrogen supply device are combined into one after passing through the check valves 8 and 14 respectively and connected to the three-way valve 4. The raw material supply device 1 and the fixed bed reactor are also connected to the three-way valve 4 through pipelines respectively. A high-pressure pump 2 is arranged between the raw material supply device 1 and the three-way valve 4;

[0026] The fixed bed reactor is composed of reaction tube A16, reaction tube B17, and reaction tube C18 connected in series from top to bottom through pipelines. A heater 15 is arranged between the reaction tube A16 and the three-way valve 4. The reaction tube C18 is connected to the condenser 19, the storage tank 20 and the collecting device 22 through pipelines in sequence. The storage tank 20 is also provided with a back pressure valve 23 for discharging tail gas. A stop valve 21 is arranged between the storage tank 20 and the collecting device 22.

[0027] Embodiment 1:

[0028] The platinum alumina catalyst was prepared by the equal volume impregnation method. First, a certain amount of alumina carrier (Si-15 produced by Shandong Yinghe Chemical) was weighed, and then chloroplatinic acid was dissolved in deionized water to prepare a platinum aqueous solution with a platinum concentration of 5%. The prepared platinum aqueous solution was added to the carrier in an amount equal to the volume of the catalyst according to the required loading amount, allowed to stand for 12 hours, taken out after impregnation, dried in an oven at 110°C for 2 hours, calcined in a muffle furnace at 450°C for 2 hours, heated to 300°C in a tubular furnace, introduced hydrogen for reduction for 2 hours, and then protected with nitrogen to obtain a platinum alumina catalyst, wherein the platinum loading amount = the mass of platinum contained in the platinum aqueous solution ÷ the mass of the carrier × 100% = 5%.

[0029] Example 2

[0030] The catalyst was prepared by an equal volume impregnation method. First, a certain amount of silica carrier (T-15 produced by Shandong Yinghe Chemical Industry) was weighed, and then palladium chloride was dissolved in deionized water to prepare a palladium aqueous solution with a palladium concentration of 5%. The prepared palladium aqueous solution was added to the carrier according to the required loading amount, allowed to stand for 12 hours, taken out after impregnation, dried in an oven at 110°C for 2 hours, calcined in a muffle furnace at 450°C for 2 hours, heated to 300°C in a tubular furnace, introduced hydrogen for reduction for 2 hours, and then protected with nitrogen to obtain a palladium / silicon dioxide catalyst, wherein the loading amount of palladium = the mass of palladium contained in the palladium aqueous solution ÷ the mass of the carrier × 100% = 5%.

[0031] Example 3

[0032] The catalyst was prepared by vacuum impregnation method. First, palladium chloride was dissolved in deionized water to prepare a palladium aqueous solution with a palladium concentration of 5%; a certain amount of γ-alumina carrier (Si-15 produced by Shandong Yinghe Chemical Industry) was weighed and placed in a reaction bottle, and the reaction bottle was vacuumed for 20 minutes. Then, the prepared palladium aqueous solution was gradually added to the carrier through a Buchner funnel, and the vacuum was continued for 20 minutes. After being taken out, it was dried at 110° C. for 2 hours in an oven, calcined at 450° C. for 2 hours in a muffle furnace, heated to 300° C. in a tubular furnace, and hydrogen was introduced for reduction for 2 hours, and then protected with nitrogen to obtain a palladium / alumina catalyst, wherein the palladium loading amount = the mass of palladium contained in the palladium aqueous solution / the mass of the carrier × 100% = 5%.

[0033] Example 4

[0034] The catalyst was prepared by vacuum impregnation method. First, chloroplatinic acid was dissolved in deionized water to prepare a platinum aqueous solution with a platinum concentration of 5%; a certain amount of γ-alumina carrier (Si-15 produced by Shandong Yinghe Chemical Industry) was weighed and placed in a reaction bottle, and the reaction bottle was vacuumed for 20 minutes. Then, the prepared platinum aqueous solution was gradually added dropwise to the carrier through a Buchner funnel, and the vacuum was continued for 20 minutes. After being taken out, it was dried at 110° C. in an oven for 2 hours, calcined at 450° C. in a muffle furnace for 2 hours, heated to 300° C. in a tubular furnace, and hydrogen was introduced for reduction for 2 hours, and then protected with nitrogen to obtain a platinum / alumina catalyst, wherein the platinum loading = the mass of platinum contained in the platinum aqueous solution / the mass of the carrier × 100% = 5%.

[0035] Example 5

[0036] A method for continuously synthesizing N-(1-ethylpropyl)-3,4-dimethylaniline comprises the following steps:

[0037] 1. Use the catalyst prepared in Example 1.

[0038] 2. Catalyst loading: Figure 2 As shown, the fixed bed reactor is formed by reaction tube A16, reaction tube B17, and reaction tube C18 connected in series from top to bottom through pipelines. The three reaction tubes are all stainless steel tubes with an inner diameter of 15 mm and an outer diameter of 30 mm, wherein the height of reaction tube A16 is 300 mm, the height of reaction tube B17 is 300 mm, and the height of reaction tube C18 is 300 mm. Removing the height of the inert filler, the effective height of the internal filler containing the loaded catalyst in reaction tube A16 is 200 mm, and the filling amount is 5 g; removing the inert filler, the effective height of the internal filler containing the loaded catalyst in reaction tube B17 is 200 mm, and the filling amount is 5 g; the effective height of the internal filler containing the loaded catalyst in reaction tube C18 is 150 mm, and the filling amount is 3.7 g.

[0039] 3. Reaction and product collection:

[0040] The specific process is as follows: first, the entire fixed bed reactor is evacuated with nitrogen, and a raw material mixture obtained according to a molar ratio of 3-pentanol: o-methylnitrobenzene = 2:1 is placed in a raw material supply device 1, and is pumped into a heater 15 by a high-pressure pump 2 for heating. At the same time, a hydrogen supply device is turned on, and the hydrogen pressure is controlled to be 1.4 MPa by a pressure reducing valve 6, so that hydrogen is passed into the heater 15 for heating, and the heater temperature is set to 60°C. After being heated by the heater 15, the raw material mixture and hydrogen enter the reaction tube A16, and react under the action of a catalyst at 60°C in the reaction tube A16 to obtain a primary catalytic mixture, and the primary catalytic mixture then enters the reaction tube B17, and undergoes a condensation reaction under the action of a catalyst, and the reaction temperature is controlled to be 80°C to obtain a secondary catalytic mixture; the secondary catalytic mixture enters the reaction tube C18 through a pipeline for reaction, and the reaction temperature is controlled to be 100°C to obtain a tertiary catalytic mixture; during the reaction, the volumetric space velocity of the liquid is controlled to be 1.2×10 -3 h -1 The three catalytic mixtures flowed into the condenser and were cooled to 40°C in the condenser. Then the liquid and gas flowed into the storage tank. The stop valve at the bottom of the storage tank was opened to collect the liquid phase. The liquid phase was N-isopropyl-o-toluidine. The conversion rate was 99.98%, the selectivity was 99.89%, and the yield was 99.87%. Figure 1 .

[0041] Example 6

[0042] Refer to Example 5, but for industrial amplification, the device is completely in accordance with Figure 1 The three reaction tubes were all stainless steel tubes with an inner diameter of 100 mm and an outer diameter of 120 mm. The height of the middle section reaction tube A16 was 3000 mm, the height of the reaction tube B17 was 4000 mm, and the height of the reaction tube C18 was 3000 mm. After removing the height of the inert filler, the effective height of the internal filler containing the supported catalyst in reaction tube A16 was 2800 mm, and the filling amount was 5000 g; after removing the inert filler, the effective height of the internal filler containing the supported catalyst in reaction tube B17 was 3800 mm, and the filling amount was 6000 g; the effective height of the internal filler containing the supported catalyst in reaction tube C18 was 2800 mm, and the filling amount was 5000 g. The volumetric space velocity of the liquid was changed to 1.2×10 -2 (20℃,m 3 .h -1 ), and other conditions were the same as those in Example 5. The results obtained showed that the selectivity of N-isopropyl-o-toluidine was 99.11% and the yield was 98.32%.

[0043] Example 7

[0044] Referring to Example 5, the only difference is that the hydrogenation reaction is carried out at the same temperature in the three reaction tubes, the reaction temperature is 100° C., and the other conditions are the same as in Example 5. The results obtained are that the selectivity of N-isopropyl-o-toluidine is 97.60% and the yield is 92.90%.

[0045] Example 8

[0046] Referring to Example 5, the only difference is that the liquid volume space velocity is changed from 1.2×10 -3 h -1 Change to 6×10 -3 h -1 , other conditions are the same as those in Example 5. Then the result obtained is that the selectivity of N-isopropyl-o-toluidine is 95.50% and the yield is 94.60%.

[0047] Example 9

[0048] Referring to Example 5, the hydrogen pressure was controlled to be 1.4 MPa by the pressure reducing valve 6, but the catalyst in Example 2 was loaded into Figure 2 In a fixed bed reactor, N-isopropyl-o-toluidine is produced. The raw material mixture and hydrogen enter the reaction tube A16 for reaction. The reaction temperature of the reaction tube A16 is 80°C to obtain a primary catalytic mixture. The primary catalytic mixture enters the reaction tube B17 through a pipeline for reaction. The reaction temperature is 100°C to obtain a secondary catalytic mixture. The secondary catalytic mixture enters the reaction tube C18 through a pipeline and undergoes hydrogenation reaction under the action of the catalyst. The reaction temperature is 150°C to obtain a tertiary catalytic mixture. During the reaction, the liquid volume space velocity is controlled to be 1.2×10 -3 h -1 The three catalytic mixtures were cooled to 40°C in a condenser, and then the liquid and gas flowed into a storage tank. The stop valve at the bottom of the storage tank was opened to collect the liquid phase, which was N-isopropyl-o-toluidine. The conversion rate was 99.25%, the selectivity was 99.30%, and the yield was 98.55%. The reactions in the three reaction tubes all reached equilibrium, and the equilibrium time was 40 minutes.

Claims

1. A method for continuously producing N-alkylaniline compounds from nitrobenzene compounds and ketones, characterized in that: The device used in the method includes a fixed bed reactor, which is composed of a reaction tube A, a reaction tube B, and a reaction tube C connected in series from top to bottom through a pipeline; the reaction tube A, the reaction tube B, and the reaction tube C are all filled with a supported catalyst, and the supported catalyst includes a carrier and an active component, the carrier is selected from one or more combinations of activated carbon, metal oxides, molecular sieves, and MXenes, and the active component is selected from one or more combinations of Fe, Ni, Cu, Zn, Mn, La, Pt, Pd, and Au; The method comprises the following steps: mixing nitrobenzene compounds and ketone compounds in a molar ratio of 1:10-1 to obtain a raw material mixture, preheating the raw material mixture and hydrogen to 60-80°C, then continuously introducing the raw material mixture and hydrogen into a reaction tube A with a temperature set at 60-80°C for reaction, controlling the introduced hydrogen pressure to be 1-2MPa, the obtained primary catalytic mixture entering a reaction tube B with a temperature set at 80-100°C through a pipeline for reaction, the obtained secondary catalytic mixture entering a reaction tube C with a temperature set at 100-160°C through a pipeline for reaction, cooling the obtained tertiary catalytic mixture, performing gas-liquid separation and purification to obtain N-alkyl aromatic amine compounds; during the reaction process, the reaction temperatures of the reaction tubes A, B and C are successively increased, and the volume space velocity of the liquid is controlled to be equal to the volume flow rate of the raw material mixture (20°C, m 3 ·h -1 ) / catalyst volume (m 3 )=(0.6-12)×10 -3 h -1 , where the catalyst volume is based on the total volume of the catalyst in reaction tubes A, B, and C.

2. The method according to claim 1, characterized in that: The nitrobenzene compound is 3,4-dimethylnitrobenzene, and the ketone compound is 3-pentanone.

3. The method according to claim 1, characterized in that: The pressure of the hydrogen introduced was controlled to be 0.8-1.2 MPa.

4. The method according to claim 1, characterized in that: Control the volume space velocity of the liquid to be (1-1.5)×10 -3 h -1 .

5. The method according to claim 1, characterized in that: The reaction tube A, reaction tube B and reaction tube C are all reaction tubes with circular cross-sections and smooth inner walls.

6. The method according to claim 1, characterized in that: The tail gas obtained after gas-liquid separation is recycled after tail gas treatment.

7. The method according to claim 1, characterized in that: The liquid product obtained after gas-liquid separation is distilled to recover excess ketone compounds, and the recovered ketone compounds are recycled.

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