CN117756672A - Refining method of N-cyanoethylaniline - Google Patents
Refining method of N-cyanoethylaniline Download PDFInfo
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- CN117756672A CN117756672A CN202311676563.8A CN202311676563A CN117756672A CN 117756672 A CN117756672 A CN 117756672A CN 202311676563 A CN202311676563 A CN 202311676563A CN 117756672 A CN117756672 A CN 117756672A
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- cyanoethylaniline
- aniline
- water
- pickling
- acrylonitrile
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- FENJKTQEFUPECW-UHFFFAOYSA-N 3-anilinopropanenitrile Chemical compound N#CCCNC1=CC=CC=C1 FENJKTQEFUPECW-UHFFFAOYSA-N 0.000 title claims abstract description 106
- 238000007670 refining Methods 0.000 title claims abstract description 47
- 238000000034 method Methods 0.000 title claims abstract description 46
- PAYRUJLWNCNPSJ-UHFFFAOYSA-N Aniline Chemical compound NC1=CC=CC=C1 PAYRUJLWNCNPSJ-UHFFFAOYSA-N 0.000 claims abstract description 158
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 81
- 238000005554 pickling Methods 0.000 claims abstract description 61
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 claims abstract description 44
- 238000005406 washing Methods 0.000 claims abstract description 33
- 239000002253 acid Substances 0.000 claims abstract description 32
- 238000010438 heat treatment Methods 0.000 claims abstract description 28
- 239000012043 crude product Substances 0.000 claims abstract description 27
- 239000000047 product Substances 0.000 claims abstract description 25
- 238000001816 cooling Methods 0.000 claims abstract description 20
- 239000000463 material Substances 0.000 claims abstract description 20
- 238000007278 cyanoethylation reaction Methods 0.000 claims abstract description 14
- 150000003839 salts Chemical class 0.000 claims abstract description 14
- 230000003472 neutralizing effect Effects 0.000 claims abstract description 5
- 239000012452 mother liquor Substances 0.000 claims description 28
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 24
- 235000002639 sodium chloride Nutrition 0.000 claims description 21
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 20
- 239000011780 sodium chloride Substances 0.000 claims description 10
- 239000007788 liquid Substances 0.000 claims description 5
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 4
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 3
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 3
- 235000011152 sodium sulphate Nutrition 0.000 claims description 3
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 2
- 239000003513 alkali Substances 0.000 claims description 2
- 235000019270 ammonium chloride Nutrition 0.000 claims description 2
- 238000006386 neutralization reaction Methods 0.000 claims description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims 1
- 230000032798 delamination Effects 0.000 claims 1
- 238000004821 distillation Methods 0.000 abstract description 12
- 230000009286 beneficial effect Effects 0.000 abstract description 6
- 238000004064 recycling Methods 0.000 abstract description 5
- 239000012535 impurity Substances 0.000 abstract description 3
- 238000002156 mixing Methods 0.000 abstract description 3
- 238000009776 industrial production Methods 0.000 abstract description 2
- 238000006243 chemical reaction Methods 0.000 description 37
- 239000003054 catalyst Substances 0.000 description 24
- 238000011084 recovery Methods 0.000 description 12
- 125000001731 2-cyanoethyl group Chemical group [H]C([H])(*)C([H])([H])C#N 0.000 description 11
- 238000004321 preservation Methods 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 9
- 238000000926 separation method Methods 0.000 description 9
- 238000004458 analytical method Methods 0.000 description 7
- 230000001105 regulatory effect Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 239000002351 wastewater Substances 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000002425 crystallisation Methods 0.000 description 4
- 238000007599 discharging Methods 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 3
- 238000001704 evaporation Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 2
- MMCPOSDMTGQNKG-UHFFFAOYSA-N anilinium chloride Chemical compound Cl.NC1=CC=CC=C1 MMCPOSDMTGQNKG-UHFFFAOYSA-N 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 239000000975 dye Substances 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000012847 fine chemical Substances 0.000 description 2
- 239000000543 intermediate Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000000575 pesticide Substances 0.000 description 2
- 230000002194 synthesizing effect Effects 0.000 description 2
- 238000004065 wastewater treatment Methods 0.000 description 2
- RRGWFPOSTSQIQE-UHFFFAOYSA-N 2-[n-(2-cyanoethyl)anilino]ethyl acetate Chemical compound CC(=O)OCCN(CCC#N)C1=CC=CC=C1 RRGWFPOSTSQIQE-UHFFFAOYSA-N 0.000 description 1
- ZTTPWPKJVSSSMW-UHFFFAOYSA-N 3-(n-benzylanilino)propanenitrile Chemical compound C=1C=CC=CC=1N(CCC#N)CC1=CC=CC=C1 ZTTPWPKJVSSSMW-UHFFFAOYSA-N 0.000 description 1
- WYRNRZQRKCXPLA-UHFFFAOYSA-N 3-(n-ethylanilino)propanenitrile Chemical compound N#CCCN(CC)C1=CC=CC=C1 WYRNRZQRKCXPLA-UHFFFAOYSA-N 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 125000004093 cyano group Chemical group *C#N 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 229910017053 inorganic salt Inorganic materials 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 229920000767 polyaniline Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 235000017557 sodium bicarbonate Nutrition 0.000 description 1
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a refining method of N-cyanoethylaniline, which comprises the following steps: heating the oil phase of the material subjected to cyanoethylation of aniline to recover acrylonitrile to obtain a crude product of N-cyanoethylaniline; crude N-cyanoethylaniline with the density of 1.04-1.08 g/cm 3 Mixing and pickling the pickling solution at 65-95 ℃ to obtain an N-cyanoethylaniline finished product and refined solution; neutralizing the refined solution, cooling, and separating oil from water to obtain the recovered aniline. The invention utilizes the properties of aniline and N-cyanoethylaniline, adopts an acid washing mode, can avoid the occurrence of impurity and salt hardening caused by high temperature in the distillation and rectification processes, can simply realize the recycling of aniline, is beneficial to automatic control, improves the refining efficiency, reduces the equipment investment, reduces the treatment risk and the cost, and is beneficial to realizing industrial production.
Description
Technical Field
The invention relates to the technical field of N-cyanoethylaniline production, in particular to a refining method of N-cyanoethylaniline.
Background
N-cyanoethylaniline is an important fine chemical raw material and intermediate, can be used for synthesizing fine chemical intermediates such as dyes, pesticides and the like, for example, N-cyanoethyl-N-benzyl aniline, N-ethyl-N-cyanoethylaniline, N-cyanoethyl-N-acetoxyethyl aniline and the like, and is widely used for synthesizing dyes, pesticides and the like.
The refining method of N-cyanoethylaniline disclosed in the prior art mainly comprises a cooling crystallization method, such as a cooling crystallization method is adopted in the patent application with the publication number of CN105037204A, CN114292210A, and the method can achieve the purpose of refining the N-cyanoethylaniline, but has large wastewater quantity, unconverted aniline is difficult to recover, the yield of a target product is reduced, the production cost is increased, and the reaction and treatment method is gradually abandoned in the industry at present. The other is distillation, for example, the patent application with publication number CN102241606A, JP1992139159A adopts the mode, the mode adopts a water-oil two-phase reaction mode, the catalyst is dissolved in water to achieve the catalytic effect, and the effect of applying the catalytic mother liquor by layering after the reaction is finished. Unreacted aniline is distilled out of materials, recycling is easy, but due to instability of aniline and cyano, high-temperature recycling is easy to cause problems of aniline oxidation, self-polymerization of acrylonitrile and the like, and a neutralizing agent added before distillation is hardened after distillation, so that heat exchange efficiency is reduced, periodic cleaning is needed, and risks are high. In addition, patent specification publication No. CN104003905A discloses a method for purifying N-cyanoethylaniline by distillation, which has low feasibility because N-cyanoethylaniline is easily decomposed after exceeding 200 ℃ in addition to the same problems of the distillation process.
Disclosure of Invention
Aiming at the technical problems and the defects existing in the field, the invention provides a refining method of N-cyanoethylaniline, which utilizes the properties of aniline and N-cyanoethylaniline, adopts an acid washing mode, can avoid the occurrence of impurity and salt hardening caused by high temperature in the distillation and rectification processes, can simply realize the recycling of aniline, is beneficial to automatic control, improves the refining efficiency, reduces the equipment investment, reduces the treatment risk and the cost, and is beneficial to realizing industrial production.
The specific technical scheme is as follows:
a refining method of N-cyanoethylaniline comprises the following steps:
heating the oil phase of the material subjected to cyanoethylation of aniline to recover acrylonitrile to obtain a crude product of N-cyanoethylaniline;
crude N-cyanoethylaniline with the density of 1.04-1.08 g/cm 3 The pickling solution of (2) is mixed and pickled at 65-95 ℃ (preferably 75-85 ℃) to obtain an N-cyanoethylaniline finished product and refined solution; the viscosity of N-cyanoethylaniline is increased when the pickling temperature is too low, the fluidity is reduced, the refining efficiency is affected, the temperature is too high, the light components of the system are easy to boil, and the separation effect is poor;
neutralizing the refined solution, cooling, and separating oil from water to obtain the recovered aniline.
In the refining method, the N-cyanoethylaniline finished product and the refined solution can be separated efficiently in a layering mode.
In one embodiment, the refining method of the N-cyanoethylaniline comprises standing and layering materials after cyanoethylation of aniline to separate mother liquor water and oil phase. Furthermore, the mother liquor water can be recycled for cyanoethylation of aniline. When the mother liquor water jacket is used, a small amount of catalyst can be added according to actual conditions.
According to the invention, the temperature of the oil phase after cyanoethylation of aniline is raised to recover acrylonitrile, if the acrylonitrile is not recovered preferentially, the content of acrylonitrile in the product N-cyanoethylaniline after the pickling process is higher, the loss of acrylonitrile is large, and the quality of the subsequent products is affected.
In one embodiment, the method for refining N-cyanoethylaniline is used for recovering acrylonitrile by heating to 105-115 ℃.
In one embodiment, the method for refining N-cyanoethylaniline can recycle the recovered acrylonitrile for the cyanoethylation reaction of aniline.
The acid in the pickling solution can be combined with aniline to form aniline salt so as to be dissolved in water. In one embodiment, the refining method of the N-cyanoethylaniline comprises the steps of 2-8wt% of acid in pickling solution, more preferably 2-6wt% of acid, and the higher acid concentration can lead to the reduction of the yield of the N-cyanoethylaniline and the reduction of the removal efficiency of aniline due to the excessively low concentration.
In one embodiment, in the method for refining N-cyanoethylaniline, the mass ratio of the dried crude N-cyanoethylaniline to the pickling solution is 1:1.25-1.71, preferably 1:1.4-1.5, if the mass ratio is higher, the refining effect is reduced, the raw materials in the N-cyanoethylaniline cannot be well removed, and if the feeding mass ratio is lower, the wastewater production amount and the refining cost are increased.
In the refining method of the invention, the density control of the pickling solution is very important, and the separation effect of the finished product of the N-cyanoethylaniline and the refined solution and the refining cost are obviously influenced. The density of the pickling solution is lower than 1.04g/cm 3 The separation effect of the finished product of the N-cyanoethylaniline and the refined solution is affected due to the fact that the density of the finished product of the N-cyanoethylaniline is too similar to that of the N-cyanoethylaniline; the density of the pickling solution is higher than 1.08g/cm 3 When the pickling solution is prepared, more salt needs to be added, the refining cost is increased, and the solubility of the pickling solution to the aniline is affected by excessive salt, so that the purity of the N-cyanoethylaniline finished product is not facilitated. The density of the pickling solution can be regulated and controlled by adding water-soluble salt capable of increasing the water density into the pickling solution, the subsequent layering efficiency is reduced after the salt is too little, and the solubility of the polyaniline salt is reduced after the salt is too much.
In an embodiment, the composition of the pickling solution comprises water, salt and acid, wherein the salt is water-soluble salt capable of increasing water density, for example, at least one of sodium sulfate, sodium chloride and ammonium chloride, the acid is at least one of hydrochloric acid and sulfuric acid, and the solubility of the corresponding aniline salt and the ion singleness in the wastewater are mainly considered, and hydrochloric acid is preferred.
In one embodiment, the refining method of the N-cyanoethylaniline adopts a countercurrent multistage gradient washing mode for continuous acid washing of the crude product of the N-cyanoethylaniline and the pickling solution, thereby being beneficial to improving the acid washing effect. For example, a three-stage pickling tower is adopted, the crude product of the N-cyanoethylaniline sequentially and continuously passes through a first stage, a second stage and a third stage pickling tower and then is subjected to layered discharge from the three-stage pickling tower to obtain a finished product of the N-cyanoethylaniline, and the pickling solution sequentially and continuously passes through the third stage, the second stage and the first stage pickling tower and then is subjected to layered discharge from the first stage pickling tower to obtain refined solution.
In one embodiment, the method for refining N-cyanoethylaniline can use at least one of alkaline reagent such as liquid alkali and ammonia water to neutralize the refined liquid.
In one embodiment, the pH of the neutralized refined solution is 7-8.
In one embodiment, the method for refining N-cyanoethylaniline is characterized in that the temperature of the neutralized refined solution is reduced to 20-40 ℃, preferably 25-35 ℃. The temperature of the cooling end point is higher, the solubility of aniline in water is higher, the loss of aniline can be caused, the wastewater treatment cost is increased, the temperature is lower, and the cooling energy consumption is increased.
In one embodiment, the method for refining N-cyanoethylaniline is described, and the recovered aniline can be reused for cyanoethylation.
Compared with the prior art, the invention has the beneficial effects that:
1) The invention utilizes the characteristic that aniline is easy to combine with acid to generate corresponding salt and is dissolved in water, and uses dilute acid with specific density to refine, separate and purify the crude product of N-cyanoethylaniline, thereby avoiding the generation of oxidation and high polymer impurities in the N-cyanoethylaniline which are easy to occur in distillation and purification and improving the quality of the N-cyanoethylaniline.
2) The acid washing wastewater can be easily recycled through neutralization and density control, so that the yield of the N-cyanoethylaniline is improved, and the wastewater treatment cost is reduced.
3) According to the invention, the high-temperature distillation process is avoided, the conditions of inorganic salt precipitation and hardening caused by material dehydration are avoided, the equipment does not need to be cleaned regularly, and the operation is more stable and safer.
4) The refining process of the invention can adopt a continuous layering mode, and is superior to a distillation method and a crystallization filtration method in terms of automation degree, stability, treatment efficiency and the like. The production amount of the wastewater is not much different from that of the wastewater produced by the distillation method. And the recycling of the raw materials can be easily realized, and the method has great application prospect in industry.
Drawings
FIG. 1 is a schematic flow chart of a continuous refining method of N-cyanoethylaniline.
Detailed Description
The invention will be further elucidated with reference to the drawings and to specific embodiments. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention.
The methods of operation, under which specific conditions are not noted in the examples below, are generally in accordance with conventional conditions, or in accordance with the conditions recommended by the manufacturer.
Referring to fig. 1, the continuous refining method of N-cyanoethylaniline of the present invention comprises:
separating mother liquor water and an oil phase of the material subjected to cyanoethylation of aniline through standing and layering, circularly sleeving the mother liquor water for cyanoethylation of aniline, and heating the oil phase to recover acrylonitrile to obtain a crude product of N-cyanoethylaniline;
crude N-cyanoethylaniline with the density of 1.04-1.08 g/cm 3 Mixing and pickling the pickling solution at 65-95 ℃ to obtain an N-cyanoethylaniline finished product and refined solution; specifically, a three-stage pickling tower is adopted, the crude product of the N-cyanoethylaniline sequentially and continuously passes through a first stage, a second stage and a third stage pickling and then is subjected to layered discharge from the three-stage pickling tower to obtain a finished product of the N-cyanoethylaniline, and the pickling solution sequentially and continuously passes through the third stage, the second stage and the first stage pickling and then is subjected to layered discharge from the first stage pickling tower to obtain refined solution;
continuously neutralizing the refined solution, cooling, and separating oil from water to obtain the recovered aniline.
Example 1
The refining method of the N-cyanoethylaniline is adopted.
Adding the previous batch of layered mother liquor water into a cyanoethyl reaction kettle, measuring the catalyst content, adding a small amount of catalyst, cooling to 55 ℃, adding 450kg of aniline and a batch of acid-washing recovered aniline, 300kg of acrylonitrile and a batch of recovered acrylonitrile, slowly heating, carrying out heat preservation reaction at 80-93 ℃, standing for 30min after the reaction is qualified, separating the lower-layer mother liquor water, and heating the upper-layer material to 110 ℃ to recover the acrylonitrile. And after the recovery is finished, the crude product of the N-cyanoethylaniline is placed into a transfer kettle.
The feed flow of the crude product of N-cyanoethylaniline (water content 4.5wt%, aniline content 5.8wt%, insoluble matter 0.19 wt%) is 104.7kg/h, the acid washing water (hydrochloric acid content 6wt%, sodium chloride content 5.6wt%, and the water content of the acid washing water is 1.04 g/cm) 3 ) The feeding flow is 170kg/h, the pickling temperature is 80-85 ℃, the residence time of continuous refining equipment (a three-stage pickling tower) is about 2 hours, the pH value of refined solution is regulated to 7-8, the temperature is reduced to 20-25 ℃, and 60.4kg of recovered aniline is obtained through oil-water separation. Analysis of data after feed was completed: the aniline content in the obtained N-cyanoethylaniline finished product is 0.37wt%, the insoluble content is 0.2wt%, and the yield of the N-cyanoethylaniline is 98.87 percent by calculation.
Example 2
The refining method of the N-cyanoethylaniline is adopted.
Adding the previous batch of layered mother liquor water into a cyanoethyl reaction kettle, measuring the catalyst content, adding a small amount of catalyst, cooling to 55 ℃, adding 450kg of aniline and a batch of acid-washing recovered aniline, 300kg of acrylonitrile and a batch of recovered acrylonitrile, slowly heating, carrying out heat preservation reaction at 80-93 ℃, standing for 30min after the reaction is qualified, separating the lower-layer mother liquor water, and heating the upper-layer material to 110 ℃ to recover the acrylonitrile. And after the recovery is finished, the crude product of the N-cyanoethylaniline is placed into a transfer kettle.
The feed flow of the crude product of N-cyanoethylaniline (water content 4.5wt%, aniline content 2.9wt%, insoluble matter 0.18 wt%) is 104.7kg/h, the acid washing water (hydrochloric acid content 2wt%, sodium sulfate content 10.7wt%, and the water content of the acid washing water is 1.08 g/cm) 3 ) Feeding flow rate is 125kg/h, pickling temperature is 75-80 ℃, and continuous refining equipment (three-stage pickling tower)) The residence time is about 2 hours, the pH value of the refined solution is regulated to 7-8, the temperature is reduced to 35-40 ℃, and 61.5kg of recovered aniline is obtained by oil-water separation. Analysis of data after feed was completed: the aniline content in the obtained N-cyanoethylaniline finished product is 0.36wt%, the insoluble content is 0.19wt%, and the yield of the N-cyanoethylaniline is 98.91 percent.
Example 3
The refining method of the N-cyanoethylaniline is adopted.
Adding the previous batch of layered mother liquor water into a cyanoethyl reaction kettle, measuring the catalyst content, adding a small amount of catalyst, cooling to 55 ℃, adding 450kg of aniline and a batch of acid-washing recovered aniline, 300kg of acrylonitrile and a batch of recovered acrylonitrile, slowly heating, carrying out heat preservation reaction at 80-93 ℃, standing for 30min after the reaction is qualified, separating the lower-layer mother liquor water, and heating the upper-layer material to 110 ℃ to recover the acrylonitrile. And after the recovery is finished, the crude product of the N-cyanoethylaniline is placed into a transfer kettle.
Feeding flow rate of cyanoethylaniline crude product (water content 4.5wt%, aniline content 4.4wt%, insoluble matter 0.18 wt%) is 104.7kg/h, acid washing water (hydrochloric acid content 6wt%, sodium chloride content 7.6wt%, and acid washing water content 1.06 g/cm) 3 ) The feeding flow is 145kg/h, the pickling temperature is 78-83 ℃, the residence time of continuous refining equipment (a three-stage pickling tower) is about 2 hours, the pH value of refined solution is regulated to 7-8, the temperature is reduced to 25-30 ℃, and 59.4kg of recovered aniline is obtained through oil-water separation. Analysis of data after feed was completed: the aniline content in the obtained N-cyanoethylaniline finished product is 0.35wt%, the insoluble content is 0.19wt%, and the yield of the N-cyanoethylaniline is 98.94% by calculation.
Comparative example 1
Adding the previous batch of layered mother liquor water into a cyanoethyl reaction kettle, measuring the catalyst content, adding a small amount of catalyst, cooling to 55 ℃, adding 450kg of aniline and a batch of acid-washing recovered aniline, 300kg of acrylonitrile and a batch of recovered acrylonitrile, slowly heating, carrying out heat preservation reaction at 80-93 ℃, standing for 30min after the reaction is qualified, separating the lower-layer mother liquor water, and heating the upper-layer material to 110 ℃ to recover the acrylonitrile. And after the recovery is finished, the crude product of the N-cyanoethylaniline is placed into a transfer kettle.
Cyanoethylaniline crude product (water content 4.5wt%, aniline content 4.4wt%, insoluble)0.18 wt%) of feed flow rate 104.7kg/h, pickling water (hydrochloric acid content 6wt%, sodium chloride content 2.6wt%, pickling water content 1.02 g/cm) 3 ) The feeding flow is 145kg/h, the pickling temperature is 78-83 ℃, the residence time of continuous refining equipment (a three-stage pickling tower) is about 2 hours, and the refining purpose can not be achieved due to the fact that the density difference between water and oil phase is too small, the discharging of the three-stage pickling tower and the water outlet are mixed.
Comparative example 2
Adding the previous batch of layered mother liquor water into a cyanoethyl reaction kettle, measuring the catalyst content, adding a small amount of catalyst, cooling to 55 ℃, adding 450kg of aniline and a batch of acid-washing recovered aniline, 300kg of acrylonitrile and a batch of recovered acrylonitrile, slowly heating, carrying out heat preservation reaction at 80-93 ℃, standing for 30min after the reaction is qualified, separating the lower-layer mother liquor water, and heating the upper-layer material to 110 ℃ to recover the acrylonitrile. And after the recovery is finished, the crude product of the N-cyanoethylaniline is placed into a transfer kettle.
Feeding flow rate of cyanoethylaniline crude product (water content 4.5wt%, aniline content 4.4wt%, insoluble matter 0.18 wt%) is 104.7kg/h, acid washing water (hydrochloric acid content 6wt%, sodium chloride content 13.5wt%, and acid washing water content 1.10 g/cm) 3 ) The feeding flow is 145kg/h, the pickling temperature is 78-83 ℃, the residence time of continuous refining equipment (a three-stage pickling tower) is about 2 hours, the pH value of refined solution is regulated to 7-8, the temperature is reduced to 25-30 ℃, and 53.8kg of recovered aniline is obtained through oil-water separation. Analysis of data after feed was completed: the aniline content in the obtained N-cyanoethylaniline finished product is 1.24wt%, the insoluble matter is 0.2wt%, and the yield of the N-cyanoethylaniline is 99.08 percent.
Comparative example 3
Adding the previous batch of layered mother liquor water into a cyanoethyl reaction kettle, measuring the catalyst content, adding a small amount of catalyst, cooling to 55 ℃, adding 450kg of aniline and a batch of acid-washing recovered aniline, 300kg of acrylonitrile and a batch of recovered acrylonitrile, slowly heating, carrying out heat preservation reaction at 80-93 ℃, standing for 30min after the reaction is qualified, separating the lower-layer mother liquor water, and heating the upper-layer material to 110 ℃ to recover the acrylonitrile. And after the recovery is finished, the crude product of the N-cyanoethylaniline is placed into a transfer kettle.
Cyanoethylaniline crude product (water content 4.5wt%, aniline content 4.4wt%, insoluble matter)0.18 wt%) of feed flow 104.7kg/h, pickling water (hydrochloric acid content 6wt%, sodium chloride content 7.6wt%, pickling water content 1.06 g/cm) 3 ) The feeding flow is 145kg/h, the pickling temperature is 55-60 ℃, and the residence time of continuous refining equipment (a three-stage pickling tower) is about 2 hours. The material with too low temperature is coagulated and can not be subjected to acid washing and discharging.
Comparative example 4
Adding the previous batch of layered mother liquor water into a cyanoethyl reaction kettle, measuring the catalyst content, adding a small amount of catalyst, cooling to 55 ℃, adding 450kg of aniline and a batch of acid-washing recovered aniline, 300kg of acrylonitrile and a batch of recovered acrylonitrile, slowly heating, carrying out heat preservation reaction at 80-93 ℃, standing for 30min after the reaction is qualified, separating the lower-layer mother liquor water, and heating the upper-layer material to 110 ℃ to recover the acrylonitrile. And after the recovery is finished, the crude product of the N-cyanoethylaniline is placed into a transfer kettle.
Feeding flow rate of cyanoethylaniline crude product (water content 4.5wt%, aniline content 4.4wt%, insoluble matter 0.18 wt%) is 104.7kg/h, acid washing water (hydrochloric acid content 6wt%, sodium chloride content 7.6wt%, and acid washing water content 1.06 g/cm) 3 ) The feeding flow rate is 145kg/h, the pickling temperature is 100-105 ℃, and the residence time of continuous refining equipment (a three-stage pickling tower) is about 2 hours. The liquid heat convection in the pickling equipment is obvious, the discharging and water mixing phenomenon occurs at the discharging and water outlet of the pickling tower, and the refining purpose can not be achieved.
Comparative example 5
Adding the previous batch of layered mother liquor water into a cyanoethyl reaction kettle, measuring the catalyst content, adding a small amount of catalyst, cooling to 55 ℃, adding 450kg of aniline and a batch of acid-washing recovered aniline, 300kg of acrylonitrile and a batch of recovered acrylonitrile, slowly heating, carrying out heat preservation reaction at 80-93 ℃, standing for 30min after the reaction is qualified, separating the lower-layer mother liquor water, and heating the upper-layer material to 110 ℃ to recover the acrylonitrile. And after the recovery is finished, the crude product of the N-cyanoethylaniline is placed into a transfer kettle.
Feeding flow rate of cyanoethylaniline crude product (water content 4.5wt%, aniline content 4.4wt%, insoluble matter 0.18 wt%) is 104.7kg/h, acid washing water (hydrochloric acid content 1wt%, sodium chloride content 7.9wt%, acid washing water content 1.06 g/cm) 3 ) The feeding flow rate is 145kg/h, the pickling temperature is 78-83 ℃, and the continuous refining equipment (three-stage pickling)Tower) for about 2 hours, regulating the pH value of the refined solution to 7-8, reducing the temperature to 25-30 ℃, and obtaining 34.3kg of recovered aniline by oil-water separation. Analysis of data after feed was completed: the aniline content in the obtained N-cyanoethylaniline finished product is 2.07wt%, the insoluble content is 0.19wt%, and the yield of the N-cyanoethylaniline is 98.44 percent.
Comparative example 6
Adding the previous batch of layered mother liquor water into a cyanoethyl reaction kettle, measuring the catalyst content, adding a small amount of catalyst, cooling to 55 ℃, adding 450kg of aniline and a batch of acid-washing recovered aniline, 300kg of acrylonitrile and a batch of recovered acrylonitrile, slowly heating, carrying out heat preservation reaction at 80-93 ℃, standing for 30min after the reaction is qualified, separating the lower-layer mother liquor water, and heating the upper-layer material to 110 ℃ to recover the acrylonitrile. And after the recovery is finished, the crude product of the N-cyanoethylaniline is placed into a transfer kettle.
Feeding flow rate of cyanoethylaniline crude product (water content 4.5wt%, aniline content 4.4wt%, insoluble matter 0.18 wt%) is 104.7kg/h, acid washing water (hydrochloric acid content 10wt%, sodium chloride content 6.8wt%, and acid washing water content 1.06 g/cm) 3 ) The feeding flow is 145kg/h, the pickling temperature is 78-83 ℃, the residence time of continuous refining equipment (a three-stage pickling tower) is about 2 hours, the pH value of refined solution is regulated to 7-8, the temperature is reduced to 25-30 ℃, and 136.5kg of recovered aniline is obtained through oil-water separation. Analysis of data after feed was completed: the aniline content in the obtained N-cyanoethylaniline finished product is 0.29wt%, the insoluble content is 0.19wt%, and the yield of the N-cyanoethylaniline is 98.44 percent.
Comparative example 7
Adding the previous batch of layered mother liquor water into a cyanoethyl reaction kettle, measuring the catalyst content, adding a small amount of catalyst, cooling to 55 ℃, adding 450kg of aniline and a batch of evaporated recovered aniline, 300kg of acrylonitrile and a batch of recovered acrylonitrile, slowly heating, carrying out heat preservation reaction at 80-93 ℃, standing for 30min after the reaction is qualified, separating the lower-layer mother liquor water, adding 6kg of baking soda into the upper-layer material to neutralize the residual catalyst, and heating to 110 ℃ to recover the acrylonitrile. And (5) after the recovery is finished, placing the materials into an evaporation kettle.
Adding a batch of crude N-cyanoethylaniline (water content 4.5wt%, aniline content 4.4wt%, insoluble matter 0.18 wt%) into an evaporation kettle, starting a vacuum pump and a condenser, heating a jacket to 130 ℃, starting straight-through steam, controlling the temperature in the kettle to slowly rise to 155 ℃, evaporating and recovering for 0.5h to obtain a finished N-cyanoethylaniline product, and calculating by analysis: the aniline content in the finished product is 0.46wt%, the insoluble content is 0.45wt%, and the yield of the N-cyanoethylaniline is 98.45 percent.
Comparative example 8
Adding a certain amount of bottom water into a cyanoethyl reaction kettle, adding a certain amount of catalyst, adding 450kg of aniline and 300kg of acrylonitrile, slowly heating, carrying out heat preservation reaction at 80-93 ℃, slowly adding 2500kg of water into the reaction kettle after the reaction is finished, diluting, cooling, crystallizing, filtering and washing to obtain an N-cyanoethyl aniline crystal finished product. By analytical calculation: the aniline content in the finished product is 1.14wt%, the insoluble content is 0.20wt%, and the yield of the N-cyanoethylaniline is 96.78 percent.
According to the embodiment and the comparative example, compared with a distillation method, the refining method can obviously reduce the generation amount of insoluble substances and improve the recovery rate of aniline to a certain extent; compared with a cooling crystallization method, the recovery rate of the aniline can be greatly improved. Therefore, the refining method of the invention can improve the quality and the yield of the product and reduce the production cost.
Further, it will be understood that various changes and modifications may be made by those skilled in the art after reading the foregoing description of the invention, and such equivalents are intended to fall within the scope of the claims appended hereto.
Claims (9)
1. A method for refining N-cyanoethylaniline is characterized by comprising the following steps:
heating the oil phase of the material subjected to cyanoethylation of aniline to recover acrylonitrile to obtain a crude product of N-cyanoethylaniline;
crude N-cyanoethylaniline with the density of 1.04-1.08 g/cm 3 The pickling solution of (2) is mixed and pickled at 65-95 ℃ (preferably 75-85 ℃) to obtain an N-cyanoethylaniline finished product and refined solution;
neutralizing the refined solution, cooling, and separating oil from water to obtain the recovered aniline.
2. The method for purifying N-cyanoethylaniline according to claim 1, wherein the material after cyanoethylation of aniline is subjected to standing and delamination to separate a mother liquor water and an oil phase, and the mother liquor water is circulated and sleeved for cyanoethylation of aniline.
3. The method for purifying N-cyanoethylaniline according to claim 1, wherein acrylonitrile is recovered by heating to 105 to 115 ℃;
the recovered acrylonitrile is reused for aniline cyanoethylation reaction.
4. The method for refining N-cyanoethylaniline according to claim 1, wherein the acid mass fraction in the pickling solution is 2-8wt%, preferably 2-6wt%;
the mass ratio of the dried N-cyanoethylaniline crude product to the pickling solution is 1:1.25-1.71, preferably 1:1.4-1.5.
5. The method for purifying N-cyanoethylaniline according to claim 1, wherein the composition of the pickling solution comprises water, a salt and an acid, wherein the salt is at least one of sodium sulfate, sodium chloride and ammonium chloride, and the acid is at least one of hydrochloric acid and sulfuric acid.
6. The method for purifying N-cyanoethylaniline according to claim 1, wherein the continuous acid washing is performed by countercurrent multistage gradient washing of the crude N-cyanoethylaniline and the pickling solution.
7. The method for purifying N-cyanoethylaniline according to claim 1, wherein the purified solution is neutralized with at least one of a liquid alkali and aqueous ammonia;
the pH value of the refined liquid after neutralization is 7-8.
8. The method for purifying N-cyanoethylaniline according to claim 1, wherein the neutralized purified solution is cooled to 20 to 40 ℃, preferably 25 to 35 ℃.
9. The method for purifying N-cyanoethylaniline according to claim 1, wherein the recovered aniline is reused for cyanoethylation.
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