CN101712621B - Method for continuously preparing toluenediamine - Google Patents
Method for continuously preparing toluenediamine Download PDFInfo
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- CN101712621B CN101712621B CN2009101697799A CN200910169779A CN101712621B CN 101712621 B CN101712621 B CN 101712621B CN 2009101697799 A CN2009101697799 A CN 2009101697799A CN 200910169779 A CN200910169779 A CN 200910169779A CN 101712621 B CN101712621 B CN 101712621B
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Abstract
The invention relates to a method for continuously preparing toluenediamine, continuously rectifying toluenediamine so as to separate toluenediamine into expected meta-position toluenediamine (a 2,4-TDA and 2,6-TDA isomer mixture), ortho toluenediamine (a 2,3-TDA and 3,4-TDA isomer mixture) and unwanted tar. The invention is characterized in that a solvent-free hydrogenization process is adopted to carry out gas-liquid-solid three phase hydrogenization reduction reaction under the existence of a nickel catalyst, and then violent stirring is carried out; a mode of combining external circulation cooling and internal coil pipecooling is adopted to take away reaction heat generated in a reactor (1); dinitrotoluene is reduced by hydrogen to generate crude toluenediamine; the nickel catalyst is recycled through the parallel operation of three tilted-plate settling separators, and water is removed through two distilling towers; waste water is delivered to a waste water treating system, and then three distilling towers are utilized to separate the dehydrated mixture into the expected meta-position toluenediamine, the ortho toluenediamine isomer and the unwanted tar, wherein the meta-position toluenediamine is delivered to a TDI synthesis process, the ortho toluenediamine is delivered to a deep processing process and the condensed tar is discharged out of a barrel to be burnt.
Description
Technical field
The present invention relates to a kind of continuous preparation tolylene diamine (TDA); And continuous rectification is separated into desired toluylenediamine (a kind of 2,4-TDA and 2,6-TDA isomer mixture), ortho-toluene diamine (a kind of 2; 3-TDA and 3,4-TDA isomer mixture) and the method for unwanted tar.In the method, make the DNT catalytic hydrogenating reduction, through settlement separate and reuse nickel catalyzator, through dephlegmate, using the multistage rectification tower then is desired isomer and unwanted higher-boiling compound with the mixture separation of dehydration.
Technical background
Toluylenediamine is a kind of midbody for preparing tolylene diisocyanate.In addition, toluylenediamine also is used as the dyestuff of the usefulness of having hair dyed.
According to prior art ,-TDA is that hydrogenation through DNT prepares, is used for through the phosgenation reaction TDI that purchases.Hydrogenation can carry out in the presence of solvent.Usually at first catalyst separating is removed.This step can be operated through for example filtration or sedimentation and carried out.Except between title product-TDA, neighbour-TDA, also can form high-molecular weight by-products in the hydrogenation.These by products comprise low-boiling point material and high boiling substance.Low-boiling point material is the compound that boiling point is lower than TDA.High boiling substance is the compound that boiling point is higher than TDA.Nitro among the DNT under high pressure reduces on the powder nickel catalyzator that suspends with hydrogen, and this process can randomly be carried out in the presence of thinner or solvent.Through with corresponding nitro-compound DNT preparing aromatic amine by catalytic hydrogenation for example many methods of TDA disclosed.These methods see and are set forth in for example DE-OS 1542544,1947851,2016644,2135154,2214056,2456308, and BEPS 631964,661047,661946, and FR-PS 1359438, and GB-PS 768111, and EP-A 0124010.The suitable solvent or thinner comprise compound for example methyl alcohol, ethanol or propyl alcohol (Ullmann, the 4th edition, 1977, the 13 volumes, the 14th page).The existence of these solvents or thinner can help a large amount of reaction heat (every mole of about 418KJ of nitryl group) is distributed in a large amount of reactants, and helps its removal and increase the operability of DNT in suspension-s through improving solubleness.What run in the opposite direction with these desirable performances is the existence of solvent, and separating these solvents will have extra distillation cost.Therefore, the consumption of solvent being reduced to minimum and can be kept simultaneously in this step is optimum target with the needs that react safely.Therefore, continuous production TDA and not use solvent be preferred for the inventive method.
The thick solution that in DNT and hydrogen reaction process, obtains comprises about 60% (weight) TDA and about 40% (weight) reaction water.After solid catalyst was separated with filtration method or settling process, this thick solution also contained the by product of this method.These by products mainly are 2,3-TDA and 3, and 4-TDA can account for about 3-5% (weight) of this thick solution.Other by product also possibly exist, and comprises that some have the high-molecular weight material.For preparation can be used for the suitable initiator of phosgenation, must the water that exist and any thinner that possibly exist or solvent for example be removed through distillation with known method itself fully.In addition, be to obtain the possible maximum yield of TDI, it also is suitable removing by product through distillation, so can obtain the TDA that can buy on the market of conventional purity.The TDA of conventional purity comprise about 80% (weight) 2,2 of 4-tolylene diamine and about 20% (weight), 6-tolylene diamine.
Normally TDA is carried out drying then, promptly remove the water in the dereaction, these water account for about 40% (weight) of gained reaction mixture.In principle, thus this operation can be simply through heating TDA solution under vacuum and remove steam and steam is carried removed.But in this easy steps, the purity of separating the water that obtains can not reach the requirement of harmless emission, but is usually polluted by TDA.Therefore, the water in the reaction is preferably in the suitable distillation plant and removes through distillation.This can carry out through following steps, for example in distillation tower, rough TDA solution is heated to 200 ℃, if distillation tower operation and this tower under normal pressure or high slightly pressure have about 20-30 column plate, then obtains the water of respective pure form at the top.Take out TDA then from the bottom, the water of last part tracer level is removed through the vacuum tightness that expand into the 30-300 millibar.
In the art methods through distillation purifying methylbenzene diamines (TDA), the thick TDA that at first will in the hydrogenation of DNT, obtain is conducted in the rectifying tower.In said rectifying tower, shift out low boiling component from cat head.Low boiling component for example is 2.3-TDA and 3,4-TDA, neighbour-Tolylamine and water.Neighbour-Tolylamine and water only tracer level occur.Mixture especially comprises 2 at the bottom of the tower that in said rectifying tower, obtains, 4-TDA and 2,6-TDA and the oligomer mixture that has the TDA isomer that exists in the mixture at the bottom of the said tower to form.Comprise 2 in order to shift out, 4-TDA and 2, the valuable product of 6-TDA is conducted to mixture at the bottom of the said tower in the thin-film evaporator.In said thin-film evaporator, remove said toluene class isomer.At for example SRI report 1A, in 1968, the 55-65 pages or leaves this method has been described.
The another kind of currently known methods that shifts out the TDA isomer mixture at the bottom of the said tower the mixture is to use second rectifying tower.Here, discharge said TDA isomer mixture, with especially comprising oligomer mixture that said TDA isomer forms and being conducted in the suitable processing operation from the bottoms material of the residual catalyst of said hydrogenation from cat head.
EP-A-0236839 has described the multi-form of this method.This method that is disclosed can make water and high volatile volatile compound, also has low-boiling point material to remove through separation to a certain extent.
The rough TDA mixture of gained usually by contain the neighbour-TDA, the high boiling substance that is less than 5% weight that are less than 10% (weight), be less than the low-boiling point material of 5 weight % and be less than 5 weight % water and-TDA forms.2,3 and 3,4 separation of isomer from the TDA isomer mixture are known.Therefore, for example, US-A-3420752 has disclosed the use distillation tower and has carried out this separation, obtains neighbour-TDA at the top, between the bottom obtains-and TDA.Because the rough TDA that obtains from this reaction contains low-boiling point material and high boiling substance usually, can clearly understand immediately, if without further step, top product not only contains neighbour-TDA, also contains low-boiling point material.Equally, between bottoms not only contains-TDA, also contain high boiling substance.For-TDA, these impurity are disadvantageous for this method, because do not hope to have these high boiling substances in the title product, so between further using-TDA, for example, before being used for preparing TDI through phosgenation reaction, these impurity is removed in separation earlier.
US-A-6547933 has described a kind of method, in the method, and between obtaining-TDA do not contain high boiling substance.In an embodiment of this method, rough TDA is separated into its isomer in distillation tower.From taking out the part stream of vapor form apart from distillation tower bottom 1/3rd column lengths, and transfer in the condensing surface, do not contained high boiling substance between-TDA.But, the considerable part of product stream still by contain high boiling substance between-TDA forms, this product is used in the for example phosgenation reaction in downstream subsequently.In the another kind of form of this method, between from tower, taking out-TDA stream, and evaporation.With the steam flow condensation of gained, do not contained high boiling substance between-TDA.To be recycled in this tower without the part that contains high boiling substance of evaporation.Take out from the bottom of tower between another strand that contains high boiling substance-TDA stream.In these two kinds of forms, the stream that contains high boiling substance of discharging from the bottom will contain produce to some extent between-major portion of TDA.Therefore, only under the situation of utilizing this stream that contains high boiling substance, this method just can be used economically.Therefore, the object of the invention this method that can't pass through to be disclosed realizes.
The method that discloses among the US-A-6359177 can realize high boiling substance fully from-separate the TDA.This carries out through at first in distillation tower, making TDA be separated into its isomer.Will as bottoms obtain between-mixture of TDA and high boiling substance in second equipment, be separated between-TDA stream flows with high boiling substance, this second equipment is made up of vaporizer and condensing surface.Still between containing in the high boiling substance stream-TDA is eliminated in another stripping tower, and part is substituted by neighbour-TDA.Contain the high boiling substance and the neighbour-TDA that account for major portion in the stream that obtains like this, this stream is discharged and burns.Will by neighbour-TDA and-TDA form second stream be recycled in the isomer distillation tower.Also disclosed the multi-form of this method among the US-A-6359177.This method realized making in the high boiling substance stream to be discharged between-purpose of TDA minimization of loss.But this method improves the cost of equipment and energy.
Chinese invention patent ublic specification of application (application number: 200610105898) can be as documents of the present invention.The method that this document discloses is produced tolylene diamine through following steps; And with the reaction separation of by-products: a) in the presence of catalyzer, make DNT hydrogenation; B) from hydrogenation mixture, isolate nickel catalyzator, water and optional solvent, obtain the crude cresylic acid diamines, c) in partitioned column, the crude cresylic acid diamines is separated at least four kinds of product streams through distillation; Product stream P1 comprises low-boiling point material; Product stream P2 comprises ortho-toluene diamine, and product stream P3 comprises toluylenediamine, and product stream P4 comprises toluylenediamine and high boiling substance.
The purpose of this invention is to provide a kind of from the hydrogenation of DNT in the reaction mass that obtain and that comprise TDA through purify out the method for toluylenediamine, ortho-toluene diamine of distillation.
Summary of the invention
It is following that hydrogenation of dinitro toluene generates tolylene diamine hydrogenation equation:
Hydrogenation is the very big reaction of thermal discharge, must in time spread out of reaction heat, so the coiled pipe of very big heat-transfer surface is arranged in the reactor drum.This reaction must have violent stirring for gas-liquid-solid phase reaction, makes the hydrogen well dispersed in liquid phase, impels reaction to carry out fast.
Overall technological scheme of the present invention comprises:
1, a kind of method for preparing tolylene diamine is characterized in that:
A) the first step is in the presence of nickel catalyzator, to carry out the reaction of gas-solid liquid three-phase catalytic hydrogenating reduction in the reactor drum (1); Violent stirring; Adopt the outer circulation cooling with the inner coil pipe cooling mode that combines the reaction heat that reactor drum (1) produces to be shifted out, DNT is generated the crude cresylic acid diamines by hydrogen reducing;
B) second step was from product a), to isolate nickel catalyzator and water, obtained the crude cresylic acid diamines, and catalyst recirculation is used, and waste water is sent to Waste Water Treatment;
(i) reaction mixture gets into separator (2) through flowrate control valve (5) in the reactor drum (1); Catalyst recycle liquid after separator (2) bottom concentrates is sent back in the reactor drum (1) by recycle pump (4); Gas in separator (2) reaction solution is sent to torch through pressure controlled valve (6) by vent line; Liquid in the separator (2) after sedimentation is overflow to vapor-liquid separation tank (3) from top
(ii) the gas in the reaction solution is sent to torch by vent line in the vapor-liquid separation tank (3), and liquid gets into dehydration tower (7),
(iii) dehydration tower (7) refluxes from a cat head part and satisfies operational condition; A part is drawn drainage water, is sent to Waste Water Treatment through cooled water, and bottoms material liquid phase after interchanger (12) heats up is delivered to minor amount of water and removed tower (8) top in the dehydration tower (7); Gas phase is returned dehydration tower (7) end
(iv) remove tower (8) end in minor amount of water and send into hot nitrogen, upwards fall material gas-liquid two-phase counter current contact with cat head, stripping goes out micro-moisture contained in the material, and overhead vapours returns dehydration tower (7) end, and tower bottoms send rectifying tower (9),
C) the 3rd step was a distillation crude cresylic acid diamines in having the tolylene diamine rectifying tower (9) of dividing plate, (10), (11); So that the crude cresylic acid diamines is divided into toluylenediamine, ortho-toluene diamine, tar; Toluylenediamine is given TDI synthesis procedure; Ortho-toluene diamine is given the deep processing operation, and spissated tar is discharged barrelling and made burning disposal;
(i) tolylene diamine rectifying tower (9) satisfies operational condition from a small amount of backflow of cat head, draws separated products in a large number and comprises low-boiling point material, gets into rectifying tower (10), and separated products comprises high boiling substance at the bottom of the tower, gets into rectifying tower (11),
(ii) rectifying tower (10) satisfies operational condition from a small amount of backflow of cat head, and drawing separated products in a large number is ortho-toluene diamine, and separated products is a toluylenediamine at the bottom of the tower,
(iii) rectifying tower (11) satisfies operational condition from a small amount of backflow of cat head, and drawing separated products in a large number is toluylenediamine, and separated products is a tar at the bottom of the tower,
(iv) toluylenediamine is given TDI synthesis procedure, and ortho-toluene diamine is given the deep processing operation, and spissated tar is discharged barrelling and made burning disposal.
2, method according to claim 1, the crude cresylic acid diamines that wherein said the first step reaction generates is by four kinds of isomer 2 of tolylene diamine, 4-TDA, 2,6-TDA, 2; 3-TDA, 3,4-TDA and high-molecular weight by-products and water mix and form, and 2,4-TDA and or 2; 6-TDA accounts for 40-60% (wt), 2,3-TDA with or 3; 4-TDA accounts for 3.0-5.0% (wt), and high-molecular weight by-products accounts for 0.2-1.8% (wt), H
2O accounts for 33.2-56.8% (wt), reducible thing≤100ppm.
3, method according to claim 1; It is characterized in that the solvent-free hydrogenation process of the first step reaction employing; The working pressure of reactor drum (1) is 1.5-2.5MPa, and service temperature is 100-200 ℃, and nickel catalyzator pumps into reactor drum (1) after need pouring into and mixing in the hot water; Hydrogen is sent in the reactor drum (1) by compressor, and DNT need be heated to 80 ℃ and send in the reactor drum (1).
4, method according to claim 1 is characterized in that the driving step of the first step reaction comprises:
A) charge into reactor drum (1) with nitrogen and boost to 1.5-2.5MPa;
B) with compressor with hydrogen boost and purge (1) replace nitrogen, supply pressure is 1.15MPa, guarantees H
2Middle oxygen level＜50ppm;
C) inserting inner coil pipe with steam hose is warmed up to 100-200 ℃ for reactor drum (1);
D) heating pumps into reactor drum (1) for DNT to 80 ℃, opens and stirs 200 rev/mins of normal back maintenance rotating speeds;
E) nickel catalyzator is poured into and is pumped into reactor drum (1) in the hot water tank behind the mixed hot water;
F) when reaction heat makes temperature begin to rise, break off fast and remove the heating steam flexible pipe, be communicated with water coolant and keep temperature to 100-200 ℃;
G) reaction mixture controllably gets into separator (2) through flowrate control valve (5) by demand.
5, method according to claim 1 is characterized in that the working pressure of separator (2) in second step (i) is 0.2-1.5MPa, and service temperature is 10-200 ℃; After the upper clear supernate discharging 2,4TDA with or 2,6-TDA40-60%; 2,3-TDA with or 3,4-TDA3.0-5.0% (weight); High-molecular weight by-products 0.2-1.8% (weight), H
2O content 33.2-56.8% (weight), reducible thing≤100ppm contains the nickel catalyzator that the liquid of higher concentration catalyzer settles down by the bottom and forms filter cake, adopts three separator parallel operations, makes its discharging order Returning reactor (1).
6, method according to claim 1 is characterized in that second goes on foot (ii) vapor-liquid separation tank (3) at atmospheric operation, and temperature is below 100 ℃, is dissolved in gas in the reaction solution and all overflows by vent line and be sent to torch.
7, method according to claim 1 is characterized in that (iii) middle dehydration tower (7) of second step is a valve tray column, 10-20 piece column plate; Preferred 15 blocks of column plates, operation under normal pressure, the cat head gas phase refluxes through a part after the condensation; A part is sent to Waste Water Treatment after drawing cooling, does not have the gas phase emptying of the nitrogenous G&W steam that condensation gets off, and tower top temperature is 70-100 ℃; Cat head steams the water of 50-90%, uses the forced circulating reboiler steam heating at the bottom of the tower, and column bottom temperature is 100-150 ℃; The bottoms material gets into minor amount of water and removes tower (8) top through interchanger (12) the back liquid phase that heats up, and gas phase and minor amount of water remove the gas phase that tower (8) cat head comes and return dehydration tower (7) end together, (iv) in minor amount of water remove tower (8) cat head and import the whole still liquid of dehydration tower (7); Feed hot nitrogen at the bottom of the tower, liquid, the contact of gas two phase countercurrent flow make in the crude cresylic acid diamines moisture content less than 700ppm; This tower is a sieve-tray tower, 4-10 piece column plate, preferred 6 blocks of column plates.
8, method according to claim 1; It is characterized in that tolylene diamine rectifying tower (9), (10), (11) that the 3rd step will have a dividing plate are coupled to a cover vacuum distilling system; Realize separating of product, ortho position and tar; Its negative pressure is produced by vacuum pump (13), and the overhead condenser of rectifying tower (9), (10), (11) uses 85-95 ℃ of hot water, guarantees that TDA can not solidify in condensing surface.
9, method according to claim 3 is characterized in that among the said DNT 2,4 and 2,6-TDA isomer>=94.8% (wt), 2,3 and 3,4-TDA isomer≤4.5% (wt); Hydrogen moderate purity (butt)>=99.8% (vol), O
2≤30ppm (vol), CO≤10ppm (vol); Ni content 58-64.9% (wt) in the nickel catalyzator, specific surface area 143-216m
2/ g, mean diameter＜5mm.
10, method according to claim 8 is characterized in that rectifying tower (9) top is structured packing, and the bottom is a valve tray column, 10-20 piece column plate; Preferred 15 blocks of column plates, vacuum operating, absolute pressure 40mbar; The tower still is used the pump pump circulation, through the reboiler heating, for full tower provides heat.
Also use 85-95 ℃ of hot-water system in the rectification cell, it is used for the overhead condenser of tolylene diamine rectifying tower (9), (10), (11), because the TDA zero pour is about 80～90 ℃.Therefore with 85 ℃ of hot water coolings, guarantee that TDA can not solidify in condensing surface.Hot-water system is made up of hot water pump, hot water water cooler and hot water tank.
Flare system comprises torch gas separating tank and torch and the facility of lighting a fire automatically.Torch diameter phi 200, high 30m is by the steel tower support of high 26m.
Description of drawings
Fig. 1 realizes the process flow diagram of preparation tolylene diamine continuously.
Embodiment
The following example is used for further explain the inventive method.The top the spirit and scope of the present invention that disclose do not receive the restriction of these embodiment.Those skilled in the art should be understood that the condition that can use following method carries out known change.
Embodiment 1: reactor drum, tower process condition are controlled like following table:
Embodiment 2: reactor drum, tower process condition are controlled like following table:
Embodiment 3: reactor drum, tower process condition are controlled like following table:
Although in above illustrating, describe the present invention in detail, should be understood that described details only is used to illustrate, those skilled in the art can make change to it in not deviating from spirit that claim of the present invention limits and scope.
Claims (10)
1. method for preparing tolylene diamine is characterized in that:
A) the first step is in the presence of nickel catalyzator, to carry out the reaction of gas-solid liquid three-phase catalytic hydrogenating reduction in the reactor drum (1); Violent stirring; Adopt the outer circulation cooling with the inner coil pipe cooling mode that combines the reaction heat that reactor drum (1) produces to be shifted out, DNT is generated the crude cresylic acid diamines by hydrogen reducing;
B) second step was from product a), to isolate nickel catalyzator and water, obtained the crude cresylic acid diamines, and catalyst recirculation is used, and waste water is sent to Waste Water Treatment;
(i) reaction mixture gets into separator (2) through flowrate control valve (5) in the reactor drum (1); Catalyst recycle liquid after separator (2) bottom concentrates is sent back in the reactor drum (1) by recycle pump (4); Gas in separator (2) reaction solution is sent to torch through pressure controlled valve (6) by vent line; Liquid in the separator (2) after sedimentation is overflow to vapor-liquid separation tank (3) from top
(ii) the gas in the reaction solution is sent to torch by vent line in the vapor-liquid separation tank (3), and liquid gets into dehydration tower (7),
(iii) dehydration tower (7) refluxes from a cat head part and satisfies operational condition; A part is drawn drainage water, is sent to Waste Water Treatment through cooled water, and bottoms material liquid phase after interchanger (12) heats up is delivered to minor amount of water and removed tower (8) top in the dehydration tower (7); Gas phase is returned dehydration tower (7) end
(iv) remove tower (8) end in minor amount of water and send into hot nitrogen, upwards fall material gas-liquid two-phase counter current contact with cat head, stripping goes out micro-moisture contained in the material, and overhead vapours returns dehydration tower (7) end, and tower bottoms send the first tolylene diamine rectifying tower (9),
C) the 3rd step was a distillation crude cresylic acid diamines in having the tolylene diamine rectifying tower of dividing plate (9,10,11); So that the crude cresylic acid diamines is divided into toluylenediamine, ortho-toluene diamine, tar; Toluylenediamine is given TDI synthesis procedure; Ortho-toluene diamine is given the deep processing operation, and spissated tar is discharged barrelling and made burning disposal;
(i) the first tolylene diamine rectifying tower (9) satisfies operational condition from a small amount of backflow of cat head; Draw separated products in a large number and comprise low-boiling point material, get into the second tolylene diamine rectifying tower (10), separated products comprises high boiling substance at the bottom of the tower; Get into trimethylbenzene diamines rectifying tower (11)
(ii) the second tolylene diamine rectifying tower (10) satisfies operational condition from a small amount of backflow of cat head, and drawing separated products in a large number is ortho-toluene diamine, and separated products is a toluylenediamine at the bottom of the tower,
(iii) trimethylbenzene diamines rectifying tower (11) satisfies operational condition from a small amount of backflow of cat head, and drawing separated products in a large number is toluylenediamine, and separated products is a tar at the bottom of the tower,
(iv) toluylenediamine is given TDI synthesis procedure, and ortho-toluene diamine is given the deep processing operation, and spissated tar is discharged barrelling and made burning disposal.
2. method according to claim 1, the crude cresylic acid diamines that wherein said the first step reaction generates is by four kinds of isomer 2 of tolylene diamine, 4-TDA, 2,6-TDA, 2; 3-TDA, 3,4-TDA and high-molecular weight by-products and water mix and form, and 2,4-TDA and or 2; 6-TDA accounts for 40-60% (wt), 2,3-TDA with or 3; 4-TDA accounts for 3.0-5.0% (wt), and high-molecular weight by-products accounts for 0.2-1.8% (wt), H
2O accounts for 33.2-56.8% (wt), reducible thing≤100ppm.
3. method according to claim 1; It is characterized in that the solvent-free hydrogenation process of the first step reaction employing; The working pressure of reactor drum (1) is 1.5-2.5MPa, and service temperature is 100-200 ℃, and nickel catalyzator pumps into reactor drum (1) after need pouring into and mixing in the hot water; Hydrogen is sent in the reactor drum (1) by compressor, and DNT need be heated to 80 ℃ and send in the reactor drum (1).
4. method according to claim 1 is characterized in that the driving step of the first step reaction comprises:
A) charge into reactor drum (1) with nitrogen and boost to 1.5-2.5MPa;
B) with compressor with hydrogen boost and purge (1) replace nitrogen, supply pressure is 1.15MPa, guarantees H
2Middle oxygen level＜50ppm;
C) inserting inner coil pipe with steam hose is warmed up to 100-200 ℃ for reactor drum (1);
D) heating pumps into reactor drum (1) for DNT to 80 ℃, opens and stirs 200 rev/mins of normal back maintenance rotating speeds;
E) nickel catalyzator is poured into and is pumped into reactor drum (1) in the hot water tank behind the mixed hot water;
F) when reaction heat makes temperature begin to rise, break off fast and remove the heating steam flexible pipe, be communicated with water coolant and keep temperature to 100-200 ℃;
G) reaction mixture controllably gets into separator (2) through flowrate control valve (5) by demand.
5. method according to claim 1 is characterized in that the working pressure of separator (2) in second step (i) is 0.2-1.5MPa, and service temperature is 10-200 ℃; After the upper clear supernate discharging 2,4TDA with or 2,6-TDA40-60%; 2,3-TDA with or 3,4-TDA3.0-5.0% (weight); High-molecular weight by-products 0.2-1.8% (weight), H
2O content 33.2-56.8% (weight), reducible thing≤100ppm contains the nickel catalyzator that the liquid of higher concentration catalyzer settles down by the bottom and forms filter cake, adopts three separator parallel operations, makes its discharging order Returning reactor (1).
6. method according to claim 1 is characterized in that second goes on foot (ii) vapor-liquid separation tank (3) at atmospheric operation, and temperature is below 100 ℃, is dissolved in gas in the reaction solution and all overflows by vent line and be sent to torch.
7. method according to claim 1 is characterized in that (iii) middle dehydration tower (7) of second step is a valve tray column, 10-20 piece column plate; Operation under normal pressure, the cat head gas phase refluxes through a part after the condensation, and a part is sent to Waste Water Treatment after drawing cooling; Do not have the gas phase emptying of the nitrogenous G&W steam that condensation gets off, tower top temperature is 70-100 ℃, and cat head steams the water of 50-90%; Use the forced circulating reboiler steam heating at the bottom of the tower, column bottom temperature is 100-150 ℃, and bottoms material liquid phase after interchanger (12) heats up gets into minor amount of water and removes tower (8) top; Gas phase and minor amount of water remove the gas phase that tower (8) cat head comes and return dehydration tower (7) end together, (iv) in minor amount of water remove all still liquid of tower (8) cat head input dehydration tower (7), feed hot nitrogen at the bottom of the tower; Liquid, the contact of gas two phase countercurrent flow; Make that moisture content is less than 700ppm in the crude cresylic acid diamines, this tower is a sieve-tray tower, 4-10 piece column plate.
8. method according to claim 1; It is characterized in that the tolylene diamine rectifying tower (9,10,11) that the 3rd step will have a dividing plate is coupled to a cover vacuum distilling system; Realize separating of product, ortho position and tar; Its negative pressure is produced by vacuum pump (13), and the overhead condenser of tolylene diamine rectifying tower (9,10,11) uses 85-95 ℃ of hot water, guarantees that TDA can not solidify in condensing surface.
9. method according to claim 3 is characterized in that among the said DNT 2,4 and 2,6-TDA isomer>=94.8% (wt), 2,3 and 3,4-TDA isomer≤4.5% (wt); Hydrogen moderate purity (butt)>=99.8% (vol), O
2≤30ppm (vol), CO≤10ppm (vol); Ni content 58-64.9% (wt) in the nickel catalyzator, specific surface area 143-216m
2/ g, mean diameter＜5mm.
10. method according to claim 8 is characterized in that rectifying tower (9) top is structured packing, and the bottom is a valve tray column, 10-20 piece column plate, and vacuum operating, absolute pressure 40mbar, the tower still is used the pump pump circulation, through the reboiler heating, for full tower provides heat.
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| CN103012161A (en) * | 2013-01-16 | 2013-04-03 | 青岛科技大学 | Cleaning and dehydrating method of toluenediamine |
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| CN111233703A (en) * | 2020-02-24 | 2020-06-05 | 山东金石新材料有限公司 | Primary diamine production equipment and method for producing primary diamine by adopting same |
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| CN114516802B (en) * | 2020-11-19 | 2023-12-19 | 万华化学集团股份有限公司 | Method for refining toluenediamine |
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