CN114380698B - Method for synthesizing methylcyclohexanediamine by selective hydrogenation of diaminotoluene by continuous method - Google Patents
Method for synthesizing methylcyclohexanediamine by selective hydrogenation of diaminotoluene by continuous method Download PDFInfo
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- CN114380698B CN114380698B CN202210092226.3A CN202210092226A CN114380698B CN 114380698 B CN114380698 B CN 114380698B CN 202210092226 A CN202210092226 A CN 202210092226A CN 114380698 B CN114380698 B CN 114380698B
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- DYFXGORUJGZJCA-UHFFFAOYSA-N phenylmethanediamine Chemical compound NC(N)C1=CC=CC=C1 DYFXGORUJGZJCA-UHFFFAOYSA-N 0.000 title claims abstract description 49
- NWYDEWXSKCTWMJ-UHFFFAOYSA-N 2-methylcyclohexane-1,1-diamine Chemical compound CC1CCCCC1(N)N NWYDEWXSKCTWMJ-UHFFFAOYSA-N 0.000 title claims abstract description 34
- 238000005984 hydrogenation reaction Methods 0.000 title claims abstract description 34
- 238000000034 method Methods 0.000 title claims abstract description 21
- 230000002194 synthesizing effect Effects 0.000 title claims abstract description 16
- 238000011437 continuous method Methods 0.000 title claims abstract description 10
- 238000006243 chemical reaction Methods 0.000 claims abstract description 81
- 239000003054 catalyst Substances 0.000 claims abstract description 73
- 239000002904 solvent Substances 0.000 claims abstract description 42
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 33
- 239000002994 raw material Substances 0.000 claims abstract description 31
- 239000000463 material Substances 0.000 claims abstract description 29
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 28
- 239000001257 hydrogen Substances 0.000 claims abstract description 28
- 239000002002 slurry Substances 0.000 claims abstract description 27
- 238000003756 stirring Methods 0.000 claims abstract description 14
- 239000012528 membrane Substances 0.000 claims abstract description 13
- 238000000926 separation method Methods 0.000 claims abstract description 13
- 239000007791 liquid phase Substances 0.000 claims abstract description 12
- 239000006227 byproduct Substances 0.000 claims abstract description 10
- 239000007789 gas Substances 0.000 claims abstract description 10
- 238000011084 recovery Methods 0.000 claims abstract description 9
- 238000010924 continuous production Methods 0.000 claims abstract description 6
- 238000001704 evaporation Methods 0.000 claims abstract description 6
- 239000000758 substrate Substances 0.000 claims abstract description 4
- 239000002638 heterogeneous catalyst Substances 0.000 claims abstract description 3
- 239000012295 chemical reaction liquid Substances 0.000 claims description 7
- 239000012071 phase Substances 0.000 claims description 7
- 239000011949 solid catalyst Substances 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 238000001816 cooling Methods 0.000 claims description 5
- 230000008020 evaporation Effects 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 5
- 238000007599 discharging Methods 0.000 claims description 2
- 238000004821 distillation Methods 0.000 claims description 2
- UAEPNZWRGJTJPN-UHFFFAOYSA-N methylcyclohexane Chemical compound CC1CCCCC1 UAEPNZWRGJTJPN-UHFFFAOYSA-N 0.000 abstract description 4
- 238000012824 chemical production Methods 0.000 abstract description 2
- GYNNXHKOJHMOHS-UHFFFAOYSA-N methyl-cycloheptane Natural products CC1CCCCCC1 GYNNXHKOJHMOHS-UHFFFAOYSA-N 0.000 abstract description 2
- 238000006073 displacement reaction Methods 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 17
- 238000010517 secondary reaction Methods 0.000 description 12
- 239000000047 product Substances 0.000 description 9
- 238000004519 manufacturing process Methods 0.000 description 8
- 238000005086 pumping Methods 0.000 description 6
- 239000007795 chemical reaction product Substances 0.000 description 5
- 239000007787 solid Substances 0.000 description 4
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- XTUVJUMINZSXGF-UHFFFAOYSA-N N-methylcyclohexylamine Chemical compound CNC1CCCCC1 XTUVJUMINZSXGF-UHFFFAOYSA-N 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 230000009615 deamination Effects 0.000 description 3
- 238000006481 deamination reaction Methods 0.000 description 3
- VOZKAJLKRJDJLL-UHFFFAOYSA-N 2,4-diaminotoluene Chemical compound CC1=CC=C(N)C=C1N VOZKAJLKRJDJLL-UHFFFAOYSA-N 0.000 description 2
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 208000012839 conversion disease Diseases 0.000 description 2
- 239000003112 inhibitor Substances 0.000 description 2
- 239000000543 intermediate Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 1
- HDONYZHVZVCMLR-UHFFFAOYSA-N N=C=O.N=C=O.CC1CCCCC1 Chemical compound N=C=O.N=C=O.CC1CCCCC1 HDONYZHVZVCMLR-UHFFFAOYSA-N 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 239000003463 adsorbent Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000003599 detergent Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 230000003090 exacerbative effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012527 feed solution Substances 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 238000009775 high-speed stirring Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 239000004848 polyfunctional curative Substances 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000002336 sorption--desorption measurement Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
- C07C209/68—Preparation of compounds containing amino groups bound to a carbon skeleton from amines, by reactions not involving amino groups, e.g. reduction of unsaturated amines, aromatisation, or substitution of the carbon skeleton
- C07C209/70—Preparation of compounds containing amino groups bound to a carbon skeleton from amines, by reactions not involving amino groups, e.g. reduction of unsaturated amines, aromatisation, or substitution of the carbon skeleton by reduction of unsaturated amines
- C07C209/72—Preparation of compounds containing amino groups bound to a carbon skeleton from amines, by reactions not involving amino groups, e.g. reduction of unsaturated amines, aromatisation, or substitution of the carbon skeleton by reduction of unsaturated amines by reduction of six-membered aromatic rings
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a method for synthesizing methylcyclohexanediamine by selective hydrogenation of diaminotoluene by a continuous method, belongs to the field of chemical production, and aims to solve the problems of low selectivity of methylcyclohexanediamine and difficult catalyst recovery in the prior art. The method comprises the following steps: continuously conveying the diaminotoluene raw material solution, circulating hydrogen and a heterogeneous catalyst into a hydrogenation reactor, and stirring for reaction; the mixed gas of the byproduct gas and the unreacted hydrogen is continuously discharged from the top of the reactor, cooled, deaminated and pressurized and then mixed with the new hydrogen to be supplemented, and returned to the reactor; flash evaporating the hydrogenated material, and performing membrane separation and solvent displacement on the obtained substrate to obtain catalyst-containing slurry and liquid-phase material; the slurry containing the catalyst returns to the reactor to participate in the hydrogenation again; the liquid phase material is treated by solvent recovery and rectification to obtain methyl cyclohexane diamine. The method can continuously recycle the catalyst, realize continuous production and improve the conversion rate of diaminotoluene and the selectivity of methylcyclohexanediamine.
Description
Technical Field
The invention belongs to the field of chemical production, and particularly relates to a method for synthesizing methylcyclohexanediamine by selective hydrogenation of diaminotoluene by a continuous method.
Background
Methyl cyclohexane diamine is an important intermediate in organic chemical industry and fine chemical industry, can be applied to the production of coating hardeners, aging polymerization inhibitors, coating resins and epoxy resin curing agents, can also be used as raw materials of dyes, detergents and medical intermediates, and is more important as a raw material for preparing methyl cyclohexane diisocyanate, so that aliphatic polyurethane which is an important functional material with wide application range is prepared. Because of high production technology requirements, no enterprise can produce methyl cyclohexanediamine at home, and main product sources in China at present comprise U.S. Henschel and German Basoff chemistry.
Chinese patent CN106994344B "application of catalyst for selective hydrogenation of toluenediamine to prepare methylcyclohexamethylenediamine" discloses a supported selective hydrogenation catalyst synthesized by using alumina, silica and the like as carriers, ruthenium as an active component, cerium and the like as an auxiliary agent. Adding deamination inhibitor LiOH into 300ml high-pressure reactor, adopting catalyst quantity accounting for 3-20% of raw material, under the condition of reaction temperature 150-250 deg.C, reaction pressure 6.0-15.0MPa and stirring rotation speed 500 rpm making selective hydrogenation reactor batch reaction, toluene diamine conversion rate 99% and methyl cyclohexanediamine selectivity higher than 92%. The patent adopts the supported catalyst, the catalyst is damaged under the high-speed stirring of the reaction kettle, and the service life of the catalyst is short; the supported catalyst has few active sites, poor catalytic effect, long reaction time and low production efficiency. A1000 ton/year device of a certain Henan enterprise adopts a supported catalyst, and the diaminotoluene is catalyzed and hydrogenated in a stirred tank to prepare the methylcyclohexanediamine, and the reaction time of a single kettle is as long as 9 hours.
The micron-sized carbon-based ruthenium-carrying catalyst is suitable for high-pressure, high-temperature, strong-stirring and fluid-state conveying environments, and has the characteristics of high conversion activity and good stability. The method for synthesizing the methylcyclohexanediamine by selectively hydrogenating the diaminotoluene based on the catalyst can realize continuous, large-scale, safe and environment-friendly production, obviously shorten the reaction residence time, improve the yield of the target product methylcyclohexanediamine and the service life of the catalyst, and reduce the production cost. However, the carbon-based ruthenium-carrying catalyst with the micron particle size has the problems of long residence time required for sedimentation and separation, increased investment caused by micro powder loss, increased production cost and the like.
Therefore, the method for synthesizing the methylcyclohexanediamine by selectively hydrogenating the diaminotoluene can realize continuous production, has high diaminotoluene conversion rate, high methylcyclohexanediamine selectivity and low production cost, and becomes a problem to be solved by those skilled in the art.
Disclosure of Invention
The invention aims to provide a method for synthesizing methylcyclohexylamine by selective hydrogenation of diaminotoluene by a continuous method, which solves the problems of low methylcyclohexylamine selectivity, high catalyst loading, difficult separation and micro powder loss in the prior art.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the invention provides a method for synthesizing methylcyclohexanediamine by selectively hydrogenating diaminotoluene by a continuous method, which comprises the following steps:
s1, dissolving diaminotoluene in a solvent to obtain a raw material solution;
s2, continuously conveying the raw material solution into a hydrogenation reactor by a pump, continuously introducing circulating hydrogen from the bottom of the reactor, continuously conveying a heterogeneous catalyst into the hydrogenation reactor, and stirring for hydrogenation reaction;
s3, continuously discharging the mixed gas of the byproduct gas and the unreacted hydrogen through the top of the reactor, cooling, eluting with water, deaminizing and pressurizing, and then mixing with the new hydrogen to be supplemented and returning to the reactor; removing the solvent from the hydrogenated material by flash evaporation, and performing membrane separation and solvent replacement on the obtained substrate to obtain catalyst-containing slurry and liquid-phase material;
s4, returning the slurry containing the catalyst to the reactor to participate in the hydrogenation again; and (3) recovering the solvent from the liquid phase material, and rectifying to obtain methylcyclohexanediamine.
In the invention, the reaction product methylcyclohexyldiamine undergoes excessive hydrogenation side reaction, and 1 branched amino group is removed, so that byproduct methylcyclohexylamine and ammonia gas are generated. The byproduct ammonia is accumulated in the system, which can reduce the partial pressure of hydrogen in the system and affect the reaction conversion rate. Therefore, the mixed gas of the by-product gas and the unreacted hydrogen gas needs to be deaminated. Deamination treatment methods are prior art and may employ sulfuric acid absorption, phosphoric acid absorption, water absorption or adsorbent adsorption-desorption.
In the technical scheme of the invention, in the S2, after the raw material solution reacts with hydrogen in the primary reactor for a period of time under the catalysis condition, a reaction liquid phase and a catalyst flow into the secondary reactor from an outlet at the upper part of the primary reactor to continuously carry out hydrogenation reaction.
In the technical scheme of the invention, the raw material solution from S1 to S is sent to a raw material buffer tank, and then is sent to a reactor from the raw material buffer tank.
In the technical scheme of the invention, the solvent removed by flash evaporation in the step S3 and the solvent recovered by distillation in the step S4 are returned to the step S1 for dissolving the diaminotoluene.
In the technical scheme of the invention, in the step S4, the slurry containing the catalyst is firstly sent to a catalyst buffer tank and then is continuously sent to a reactor to participate in the reaction through the catalyst buffer tank.
In the embodiment of the present invention, the mass ratio of the respective materials is solvent to diaminotoluene to catalyst=2 to 5 to 1 to 0.01 and preferably 3 to 1 to 0.05.
In the technical scheme of the invention, the reaction temperature is 160-190 ℃, and the reaction pressure is 4.8-9.0MPa.
Preferably, the reaction pressure in the primary reactor is 5.0-9.0MPa and the reaction pressure in the secondary reactor is 4.8-8.8MPa.
In the technical scheme of the invention, the raw material solution is reacted in the primary reactor for 1-1.5 hours, the reaction liquid phase and the catalyst enter the secondary reactor, and the reaction is carried out in the secondary reactor for 1.0-2 hours.
In the technical scheme of the invention, in the catalyst-containing slurry obtained through membrane separation, the concentration of the solid catalyst is less than or equal to 10wt%, and the concentration of the methylcyclohexanediamine is less than 15wt%.
The catalyst-containing slurry obtained by membrane separation in the invention is a mixture composed of catalyst, solvent and reaction materials. The lower solid content in the catalyst-containing slurry is beneficial to material transportation, and reduces abrasion of a pump and a pipeline; too high a concentration of product methylcyclohexamethylenediamine also means that the reaction product is further returned to the reaction system, exacerbating deamination side reactions. Through a large number of experiments, the invention discovers that when the concentration of the solid catalyst in the catalyst-containing slurry is less than or equal to 10wt%, the invention is beneficial to material transportation, and simultaneously, the concentration of the methylcyclohexanediamine in the catalyst slurry is controlled to be not more than 15%, so that the selectivity of the target product methylcyclohexanediamine is improved.
Compared with the prior art, the invention has the following beneficial effects:
the method has scientific design and ingenious conception, can effectively recycle the catalyst, realize continuous production, and can also improve the conversion rate of diaminotoluene and the selectivity of methylcyclohexamethylenediamine.
According to the invention, the solvent is removed by flash evaporation of the reacted material, and the obtained substrate is subjected to membrane separation and solvent replacement, so that the separation of the catalyst and the product is realized, the obtained slurry containing the catalyst returns to the reactor to participate in hydrogenation again, continuous production can be realized, and the production cost is effectively reduced.
In the invention, the mixed gas of the byproduct gas and the unreacted hydrogen is deaminated, so that the reaction conversion rate is improved.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
The catalyst used in the examples of the present invention was a commercially available micron-sized carbon-based ruthenium-supported catalyst.
Example 1
The embodiment discloses a method for synthesizing methylcyclohexanediamine by selective hydrogenation of diaminotoluene by a continuous method, which comprises the following steps:
s1, conveying solid diaminotoluene to a dissolving tank filled with 3 times of 1, 4-dioxane solvent by a screw conveyer under the condition of stirring at the temperature of 45-50 ℃ and the normal pressure, and stirring to dissolve the diaminotoluene. The raw material solution in which diaminotoluene is dissolved is pumped to a raw material buffer tank.
S2, pumping the raw material solution to a first-stage reaction kettle through a high-pressure pump, stirring and mixing the raw material solution with catalyst slurry which is circulated from the membrane separation equipment and returns to the reaction kettle, and introducing circulating hydrogen into the first-stage reaction kettle from the bottom. The ratio of the amount of each material was solvent to diaminotoluene to catalyst=3:1:0.05; hydrogen gas (ratio of circulation volume) =13:1, reaction temperature is 180-190 ℃, reaction pressure is 8.5-9.0MPa (G), rotation speed of a stirrer is 300 rpm, reaction residence time is 1.5 hours, and reaction liquid phase and catalyst overflow into a secondary reaction kettle through an outlet at the upper part of the primary reaction kettle to continue hydrogenation reaction.
The reaction temperature in the secondary reaction kettle is 180-190 ℃, the reaction pressure is 8.3-8.8MPa (G), the rotation speed of a stirrer is 300 revolutions per minute, and circulating hydrogen is introduced into the secondary reaction kettle from the bottom. Hydrogen, starting material (cycle volume ratio) =6:1, reaction residence time 1.0 hours. The reaction produces methylcyclohexamethylenediamine and a small amount of deaminated byproducts.
S3, overflowing the mixed state of the reaction product, the solvent and the catalyst out of the secondary reaction kettle, reducing the pressure by a pressure reducing valve, flashing part of the solvent by a flash tower, cooling the material at the bottom of the flash tower to 100 ℃ by pumping, and then entering a membrane separator under the pressure of 0.8-1.0 MPa (G), separating and replacing the solvent to obtain a liquid-phase material and a slurry containing the catalyst, and controlling the concentration of the solid catalyst in the slurry containing the catalyst to be less than or equal to 10wt% and the concentration of the methylcyclohexanediamine to be less than or equal to 15wt%. And (3) removing the liquid phase material to a recovery tower to recover the solvent, and rectifying the solvent by a rectifying tower to obtain the product methylcyclohexanediamine. The slurry containing the catalyst is automatically pressed into a catalyst buffer tank, and then is pumped into a first-stage reaction kettle by pump pressurization to be circularly reacted. The circulating hydrogen is pumped out from the tops of the first-stage reaction kettle and the second-stage reaction kettle, cooled, eluted by water, pressurized by a circulating hydrogen compressor, and then mixed with the replenished new hydrogen to return to the two-stage reaction kettle.
In this example, the conversion rate of the diaminotoluene in the primary reaction kettle is 75%, the conversion rate of the diaminotoluene in the secondary reaction kettle is 68%, the total conversion rate of the diaminotoluene is 94%, the selectivity of the methylcyclohexamethylenediamine is 95%, and the recovery rate of the catalyst is more than 99.99%.
Example 2
The embodiment discloses a method for synthesizing methylcyclohexanediamine by selective hydrogenation of diaminotoluene by a continuous method, which comprises the following steps:
s1, conveying solid diaminotoluene to a dissolving tank filled with 2 times of 1, 4-dioxane solvent by a screw conveyer under the condition of stirring at 30-35 ℃ and normal pressure, and stirring to dissolve the diaminotoluene. The raw material solution in which diaminotoluene is dissolved is pumped to a raw material buffer tank.
S2, pumping the raw material solution to a first-stage reaction kettle through a high-pressure pump, stirring and mixing the raw material solution with catalyst slurry which is circulated from the membrane separation equipment and returns to the reaction kettle, and introducing circulating hydrogen into the first-stage reaction kettle from the bottom. The ratio of the amount of each material was solvent to diaminotoluene to catalyst=2:1:0.01; hydrogen gas (ratio of circulating volume) =15:1, reaction temperature 160-165 ℃, reaction pressure 5.0-5.5MPa (G), stirrer rotation speed 100 rpm, reaction residence time 1 hour, reaction liquid phase and catalyst overflows into the second-stage reaction kettle through the upper outlet of the first-stage reaction kettle to continue hydrogenation reaction.
The reaction temperature in the secondary reaction kettle is 180-190 ℃, the reaction pressure is 8.3-8.8MPa (G), the rotation speed of a stirrer is 300 revolutions per minute, and circulating hydrogen is introduced into the secondary reaction kettle from the bottom; hydrogen gas, feed solution (cycle volume ratio) =5:1, reaction residence time 1.5 hours. The reaction produces methylcyclohexamethylenediamine and a small amount of deaminated byproducts.
S3, overflowing the mixed state of the reaction product, the solvent and the catalyst out of the secondary reaction kettle, reducing the pressure by a pressure reducing valve, flashing part of the solvent by a flash tower, cooling the material at the bottom of the flash tower to 50 ℃ by pumping, and then entering a membrane separator under the pressure of 0.2-0.3 MPa (G), separating and replacing the solvent to obtain a liquid-phase material and a slurry containing the catalyst, and controlling the concentration of the solid catalyst in the slurry containing the catalyst to be less than or equal to 10wt% and the concentration of the methylcyclohexanediamine to be less than or equal to 15wt%. And (3) removing the liquid phase material to a recovery tower to recover the solvent, and rectifying the solvent by a rectifying tower to obtain the product methylcyclohexanediamine. The slurry containing the catalyst is automatically pressed into a catalyst buffer tank, and then is pumped into a first-stage reaction kettle by pump pressurization to be circularly reacted. The circulating hydrogen is pumped out from the tops of the first-stage reaction kettle and the second-stage reaction kettle, cooled, eluted by water, pressurized by a circulating hydrogen compressor, and then mixed with the replenished new hydrogen to return to the two-stage reaction kettle.
In this example, the conversion of diaminotoluene in the primary reactor was 70.2%, the conversion of diaminotoluene in the secondary reactor was 66.5%, the total conversion of diaminotoluene was 92%, the selectivity to methylcyclohexamethylenediamine was 90%, and the recovery rate of the catalyst was 99.97%.
Example 3
The embodiment discloses a method for synthesizing methylcyclohexanediamine by selective hydrogenation of diaminotoluene by a continuous method, which comprises the following steps:
s1, conveying solid diaminotoluene to a dissolving tank filled with 5 times of 1, 4-dioxane solvent by a spiral conveyer under the condition of stirring at 40-45 ℃ and normal pressure, and stirring to dissolve the diaminotoluene. The raw material solution in which diaminotoluene is dissolved is pumped to a raw material buffer tank.
S2, pumping the raw material solution to a first-stage reaction kettle through a high-pressure pump, stirring and mixing the raw material solution with catalyst slurry which is circulated from the membrane separation equipment and returns to the reaction kettle, and introducing circulating hydrogen into the first-stage reaction kettle from the bottom. The ratio of the amount of each material was solvent to diaminotoluene to catalyst=5:1:0.06; hydrogen gas (circulation volume ratio) =16:1, reaction temperature is 175-180 ℃, reaction pressure is 7.0-7.5MPa (G), rotation speed of a stirrer is 200 rpm, reaction residence time is 1.5 hours, and reaction liquid phase and catalyst overflow into a secondary reaction kettle through an outlet at the upper part of the primary reaction kettle to continue hydrogenation reaction.
The reaction temperature in the secondary reaction kettle is 175-180 ℃, the reaction pressure is 6.8-7.2MPa (G), the rotation speed of a stirrer is 100 revolutions per minute, and circulating hydrogen is introduced into the secondary reaction kettle from the bottom; hydrogen gas, raw material solution (cycle volume ratio) =5:1, reaction residence time 1 hour. The reaction produces methylcyclohexamethylenediamine and a small amount of deaminated byproducts.
S3, overflowing the mixed state of the reaction product, the solvent and the catalyst out of the secondary reaction kettle, reducing the pressure by a pressure reducing valve, flashing part of the solvent by a flash tower, cooling the material at the bottom of the flash tower to 50 ℃ by pumping, and then entering a membrane separator under the pressure of 0.2-0.3 MPa (G), separating and replacing the solvent to obtain a liquid-phase material and a slurry containing the catalyst, and controlling the concentration of the solid catalyst in the slurry containing the catalyst to be less than or equal to 10wt% and the concentration of the methylcyclohexanediamine to be less than or equal to 15wt%. And (3) removing the liquid phase material to a recovery tower to recover the solvent, and rectifying the solvent by a rectifying tower to obtain the product methylcyclohexanediamine. The slurry containing the catalyst is automatically pressed into a catalyst buffer tank, and then is pumped into a first-stage reaction kettle by pump pressurization to be circularly reacted. The circulating hydrogen is pumped out from the tops of the first-stage reaction kettle and the second-stage reaction kettle, cooled, eluted by water, pressurized by a circulating hydrogen compressor, and then mixed with the replenished new hydrogen to return to the two-stage reaction kettle.
In this example, the conversion of diaminotoluene in the primary reactor was 73.6%, the conversion of diaminotoluene in the secondary reactor was 65.4%, the total conversion of diaminotoluene was 89%, the selectivity to methylcyclohexamethylenediamine was 87%, and the recovery rate of the catalyst was 99.95%.
The embodiments described above are some, but not all embodiments of the invention. The detailed description of the embodiments of the invention is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Claims (5)
1. A method for synthesizing methylcyclohexanediamine by selective hydrogenation of diaminotoluene by a continuous method, which is characterized by comprising the following steps:
s1, dissolving diaminotoluene in a solvent to obtain a raw material solution;
s2, continuously conveying the raw material solution into a hydrogenation reactor by a pump, continuously introducing circulating hydrogen from the bottom of the reactor, continuously conveying a heterogeneous catalyst into the hydrogenation reactor, and stirring for hydrogenation reaction; the mass ratio of the materials is solvent to diaminotoluene to catalyst=2-5 to 1.01-0.06; the reaction temperature is 160-190 ℃;
s3, continuously discharging the mixed gas of the byproduct gas and the unreacted hydrogen from the top of the reactor, cooling, eluting with water, deaminizing and pressurizing, and then mixing with the supplemented new hydrogen and returning to the reactor; removing solvent from the hydrogenated material by flash evaporation, and performing membrane separation and solvent replacement on the obtained substrate to obtain catalyst-containing slurry and liquid-phase material; in the catalyst-containing slurry obtained by membrane separation and solvent replacement, the concentration of the solid catalyst is less than or equal to 10wt%, and the concentration of the methylcyclohexanediamine is less than 15 wt%;
s4, returning the slurry containing the catalyst to the reactor to participate in the hydrogenation again; the liquid phase material is subjected to solvent recovery and rectification treatment to obtain methylcyclohexanediamine;
in the step S2, at least two hydrogenation reactors are connected in series, the raw material solution is continuously sent into the first-stage reactor by a pump, and after a period of reaction, the reaction liquid phase and the catalyst continuously overflows into the second-stage reactor through an outlet at the upper part of the first-stage reactor to continuously carry out hydrogenation reaction; the reaction pressure in the primary reactor is 5.0-9.0MPa, and the reaction pressure in the secondary reactor is 4.8-8.8MPa;
the raw material solution is reacted in the first-stage reactor for 1-1.5 hours, the reaction liquid phase and the catalyst enter the second-stage reactor, and the reaction is carried out in the second-stage reactor for 1.0-2 hours.
2. The method for synthesizing methylcyclohexanediamine by selective hydrogenation of diaminotoluene in a continuous process as claimed in claim 1, wherein the raw material solution obtained in step S1 is fed into a raw material buffer tank and then fed into the reactor from the raw material buffer tank.
3. The method for synthesizing methylcyclohexanediamine by selective hydrogenation of diaminotoluene in a continuous process as claimed in claim 1, wherein the solvent removed by flash evaporation in step S3 and the solvent recovered by distillation in step S4 are returned to step S1 for dissolving the diaminotoluene.
4. The method for synthesizing methylcyclohexanediamine by selective hydrogenation of diaminotoluene as claimed in claim 1, wherein in S4, the slurry containing the catalyst is fed into a catalyst buffer tank, and then is fed into the reactor continuously through the catalyst buffer tank to participate in the reaction.
5. The method for synthesizing methylcyclohexanediamine by selective hydrogenation of diaminotoluene in accordance with any one of claims 1-4, wherein the mass ratio of the materials is solvent to diaminotoluene to catalyst = 3 to 1 to 0.05.
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| CN106518608A (en) * | 2016-10-28 | 2017-03-22 | 中国石油化工股份有限公司 | A continuous preparing method and apparatus for cyclohexanedimethanol |
| CN106994344A (en) * | 2017-03-31 | 2017-08-01 | 江苏清泉化学股份有限公司 | The method and catalyst of toluenediamine selection Hydrogenation methyl cyclohexane diamines |
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| CN106518608A (en) * | 2016-10-28 | 2017-03-22 | 中国石油化工股份有限公司 | A continuous preparing method and apparatus for cyclohexanedimethanol |
| CN106994344A (en) * | 2017-03-31 | 2017-08-01 | 江苏清泉化学股份有限公司 | The method and catalyst of toluenediamine selection Hydrogenation methyl cyclohexane diamines |
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