CN114380698A - Method for synthesizing methylcyclohexanediamine by continuous selective hydrogenation of diaminotoluene - Google Patents
Method for synthesizing methylcyclohexanediamine by continuous selective hydrogenation of diaminotoluene Download PDFInfo
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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 52
- NWYDEWXSKCTWMJ-UHFFFAOYSA-N 2-methylcyclohexane-1,1-diamine Chemical compound CC1CCCCC1(N)N NWYDEWXSKCTWMJ-UHFFFAOYSA-N 0.000 title claims abstract description 51
- 238000005984 hydrogenation reaction Methods 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims abstract description 25
- 230000002194 synthesizing effect Effects 0.000 title claims abstract description 15
- 238000006243 chemical reaction Methods 0.000 claims abstract description 84
- 239000003054 catalyst Substances 0.000 claims abstract description 72
- 239000002904 solvent Substances 0.000 claims abstract description 38
- 239000000463 material Substances 0.000 claims abstract description 33
- 239000002994 raw material Substances 0.000 claims abstract description 32
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 28
- 239000002002 slurry Substances 0.000 claims abstract description 27
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 25
- 239000001257 hydrogen Substances 0.000 claims abstract description 25
- 239000012528 membrane Substances 0.000 claims abstract description 13
- 239000007791 liquid phase Substances 0.000 claims abstract description 12
- 238000000926 separation method Methods 0.000 claims abstract description 12
- 238000003756 stirring Methods 0.000 claims abstract description 12
- 239000007789 gas Substances 0.000 claims abstract description 11
- 239000006227 byproduct Substances 0.000 claims abstract description 10
- 238000011437 continuous method Methods 0.000 claims abstract description 8
- 238000001816 cooling Methods 0.000 claims abstract description 6
- 238000001704 evaporation Methods 0.000 claims abstract description 6
- 230000008020 evaporation Effects 0.000 claims abstract description 6
- 239000000758 substrate Substances 0.000 claims abstract description 4
- 238000007599 discharging Methods 0.000 claims abstract description 3
- 239000002638 heterogeneous catalyst Substances 0.000 claims abstract description 3
- 150000002431 hydrogen Chemical class 0.000 claims abstract description 3
- 238000002156 mixing Methods 0.000 claims abstract description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 12
- 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
- 229910021529 ammonia Inorganic materials 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 238000004821 distillation Methods 0.000 claims description 2
- 238000005406 washing Methods 0.000 claims description 2
- 238000011084 recovery Methods 0.000 abstract description 7
- 238000010924 continuous production Methods 0.000 abstract description 4
- 238000012824 chemical production Methods 0.000 abstract description 2
- 239000000047 product Substances 0.000 description 9
- 238000010517 secondary reaction Methods 0.000 description 9
- 230000009615 deamination Effects 0.000 description 7
- 238000006481 deamination reaction Methods 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 7
- 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
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- 238000005086 pumping 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
- XTUVJUMINZSXGF-UHFFFAOYSA-N N-methylcyclohexylamine Chemical compound CNC1CCCCC1 XTUVJUMINZSXGF-UHFFFAOYSA-N 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
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- 239000003795 chemical substances by application Substances 0.000 description 2
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- 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
- 238000009825 accumulation 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
- 239000012752 auxiliary agent Substances 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000009903 catalytic hydrogenation reaction Methods 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
- 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
- 239000003822 epoxy resin Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 238000009775 high-speed stirring Methods 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
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- 239000002245 particle Substances 0.000 description 1
- 229920000647 polyepoxide Polymers 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
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000002336 sorption--desorption measurement Methods 0.000 description 1
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- 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)
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- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a method for synthesizing methylcyclohexanediamine through 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 feeding the diaminotoluene raw material solution, circulating hydrogen and a heterogeneous catalyst into a hydrogenation reactor, and stirring for reaction; continuously discharging the mixed gas of the byproduct gas and the unreacted hydrogen from the top of the reactor, cooling, deaminating, pressurizing, mixing with the supplemented new hydrogen, and returning the mixed gas to the reactor; carrying out flash evaporation on the hydrogenated material, and carrying out membrane separation and solvent replacement on the obtained substrate to obtain catalyst-containing slurry and a liquid-phase material; returning the slurry containing the catalyst to the reactor to participate in the hydrogenation reaction again; and (3) recovering the solvent from the liquid phase material, and rectifying to obtain the methylcyclohexanediamine. The method can continuously recover the catalyst, realize continuous production and improve the conversion rate of the diaminotoluene and the selectivity of the methylcyclohexanediamine.
Description
Technical Field
The invention belongs to the field of chemical production, and particularly relates to a method for synthesizing methylcyclohexanediamine through selective hydrogenation of diaminotoluene by a continuous method.
Background
The methylcyclohexanediamine is an important intermediate in organic chemical industry and fine chemical industry, can be applied to producing coating hardening agents, ageing polymerization inhibitors, coating resins and epoxy resin curing agents, can also be used as raw materials of dyes, detergents and medical intermediates, and more importantly is used as a raw material for preparing methylcyclohexane diisocyanate, so that the important functional material aliphatic polyurethane with wide application is prepared. Due to high production technical requirements, no enterprise can produce the methylcyclohexanediamine in China basically, and the main product sources in the current Chinese market comprise U.S. Henschel and German Pasteur chemistry.
Chinese patent CN106994344B "an application of catalyst for preparing methylcyclohexanediamine by selective hydrogenation of toluenediamine" discloses a supported selective hydrogenation catalyst synthesized by using alumina, silica, etc. as carriers, ruthenium as active component, and cerium, etc. as auxiliary agent. Adding a deamination inhibitor LiOH into a 300ml high-pressure reaction kettle, adopting a catalyst amount accounting for 3-20% of the raw material, and carrying out a selective hydrogenation kettle type batch reaction under the conditions of a reaction temperature of 150 ℃ and 250 ℃, a reaction pressure of 6.0-15.0MPa and a stirring speed of 500 r/min, wherein the conversion rate of toluenediamine is 99% and the selectivity of methylcyclohexanediamine is higher than 92%. The patent adopts a supported catalyst, the catalyst is damaged under the high-speed stirring of a reaction kettle, and the service life of the catalyst is short; the supported catalyst has the advantages of few active point positions, poor catalytic effect, long reaction time and low production efficiency. A1000-ton/year device of a certain enterprise in Henan adopts a supported catalyst, diaminotoluene is subjected to catalytic hydrogenation in a stirring kettle to prepare the methylcyclohexanediamine, and the single-kettle reaction time is as long as 9 hours.
The micron-sized carbon-based ruthenium-supported 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 the selective hydrogenation of diaminotoluene based on the catalyst can realize continuous, large-scale, safe and environment-friendly production, obviously shorten the reaction retention time, improve the yield of the target product methylcyclohexanediamine, prolong the service life of the catalyst and reduce the production cost. However, the carbon-based ruthenium-supported catalyst with the micron particle size has the problems of long retention time required for settling separation, increased investment and increased production cost caused by micro powder loss and the like.
Therefore, the method for synthesizing methylcyclohexanediamine by selective hydrogenation of diaminotoluene is provided, which can realize continuous production, has high diaminotoluene conversion rate, high selectivity of methylcyclohexanediamine and low production cost, and is a problem to be solved by the technical personnel in the field.
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 selectivity of methylcyclohexanediamine, high catalyst loading, difficult separation and micro-powder loss in the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the invention provides a method for synthesizing methylcyclohexanediamine by selective hydrogenation of 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 to perform hydrogenation reaction;
s3, continuously discharging mixed gas of byproduct gas and unreacted hydrogen from the top of the reactor, cooling, washing with water to remove ammonia, pressurizing, mixing with supplemented new hydrogen, 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 a liquid-phase material;
s4, returning the slurry containing the catalyst to the reactor to participate in the hydrogenation reaction again; and (3) recovering the solvent and rectifying the liquid phase material to obtain the methylcyclohexanediamine.
In the invention, the reaction product methyl cyclohexanediamine is subjected to excessive hydrogenation side reaction, 1 branched chain amino group can be removed, and byproducts methyl cyclohexylamine and ammonia gas are generated. The accumulation of ammonia gas as a byproduct in the system can reduce the hydrogen partial pressure of the system and influence the reaction conversion rate. Therefore, it is necessary to perform deamination of a mixed gas of by-product gas and unreacted hydrogen. The deamination treatment method is the prior art and can adopt sulfuric acid absorption, phosphoric acid absorption, water absorption or adsorbent adsorption-desorption.
In the technical scheme of the invention, in S2, after the raw material solution and hydrogen react in the primary reactor for a period of time under the catalysis condition, the reaction liquid phase and the catalyst automatically flow into the secondary reactor through the upper outlet of the primary reactor to continue the hydrogenation reaction.
According to the technical scheme, the raw material solution obtained in the step S1 is sent to a raw material buffer tank and then sent to a reactor from the raw material buffer tank.
In the technical scheme of the invention, the solvent removed by flash evaporation in S3 and the solvent recovered by distillation in S4 are returned to S1 for dissolving diaminotoluene.
In the technical scheme of the invention, in the S4, the slurry containing the catalyst is firstly sent to a catalyst buffer tank and then continuously sent to a reactor through the catalyst buffer tank to participate in the reaction.
According to the technical scheme, the mass ratio of the solvent to the diaminotoluene to the catalyst is 2 to 5 to 1.01 to 0.06, and the mass ratio of the solvent to the diaminotoluene to the catalyst is 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 4.8-9.0 MPa.
Preferably, the reaction pressure in the first reactor is 5.0-9.0MPa and the reaction pressure in the second reactor is 4.8-8.8 MPa.
According to the technical scheme, the raw material solution reacts in the primary reactor for 1-1.5 hours, the reaction liquid phase and the catalyst enter the secondary reactor, and react in the secondary reactor for 1.0-2 hours.
In the technical scheme of the invention, in the slurry containing the catalyst obtained by membrane separation, the concentration of the solid catalyst is less than or equal to 10 wt%, and the concentration of the methylcyclohexanediamine is less than 15 wt%.
The catalyst-containing slurry obtained by membrane separation in the present invention is a mixture composed of a catalyst, a solvent and a reaction material. The lower solid content in the slurry containing the catalyst is beneficial to material conveying, and the abrasion of a pump and a pipeline is reduced; too high a concentration of the product methylcyclohexanediamine also means that the reaction product is further returned to the reaction system, and the deamination side reaction is aggravated. After a large number of experiments and creative labor, the invention discovers that when the concentration of the solid catalyst in the catalyst-containing slurry is less than or equal to 10 wt%, the material conveying is facilitated, and meanwhile, the concentration of the methylcyclohexanediamine in the catalyst slurry is controlled not to exceed 15%, so that the selectivity of the target product methylcyclohexanediamine is facilitated to be improved.
Compared with the prior art, the invention has the following beneficial effects:
the method has scientific design and ingenious conception, can effectively recover the catalyst, realize continuous production, and improve the conversion rate of the diaminotoluene and the selectivity of the methylcyclohexanediamine.
The invention removes the solvent from the reacted materials by flash evaporation, separates the catalyst and the product by the obtained substrate through membrane separation and solvent replacement, returns the obtained slurry containing the catalyst to the reactor to participate in the hydrogenation reaction again, can realize continuous production, and effectively reduces the production cost.
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 clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
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 specifically comprises the following steps:
s1, conveying solid diaminotoluene to a material dissolving tank filled with 3 times of volume of 1, 4-dioxane solvent by a spiral material conveyer under the condition of stirring at 45-50 ℃ under normal pressure, and stirring to dissolve the diaminotoluene. The raw material solution in which the diaminotoluene is dissolved is pumped to a raw material buffer tank.
S2, the raw material solution is conveyed to the primary reaction kettle through a high-pressure pump, is stirred and mixed with the catalyst slurry circularly returned to the reaction kettle from the membrane separation equipment, and is introduced into the primary reaction kettle from the bottom. The ratio of the solvent to the diaminotoluene to the catalyst is 3 to 1 to 0.05; and (3) hydrogen gas and the raw material solution (circulation volume ratio) is 13: 1, the reaction temperature is 180-190 ℃, the reaction pressure is 8.5-9.0MPa (G), the rotation speed of a stirrer is 300 r/min, the reaction residence time is 1.5 hours, and the reaction liquid phase and the catalyst overflow into the second-stage reaction kettle through an outlet at the upper part 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 rotating speed of the stirrer is 300 r/min, and circulating hydrogen is introduced into the secondary reaction kettle from the bottom. Hydrogen gas/feed (cycle volume ratio) 6/1, reaction residence time 1.0 hr. The reaction produces methylcyclohexanediamine and a small amount of deamination by-products.
S3, overflowing the reaction product, the solvent and the catalyst out of the secondary reaction kettle in a mixed state, reducing the pressure by a pressure reducing valve, flashing partial solvent by a flash tower, pumping and cooling the material at the bottom of the flash tower to 100 ℃ and 0.8-1.0 MPa (G), then feeding the material into a membrane separator, 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 10 wt% and the concentration of the methylcyclohexanediamine to be less than or equal to 15 wt%. And (3) the liquid-phase material is sent to a recovery tower to recover the solvent and is rectified by a rectifying tower to obtain the product methyl cyclohexanediamine. The slurry containing the catalyst enters a catalyst buffer tank under self-pressure, is pressurized by a pump and is sent to a first-stage reaction kettle, and circularly participates in the reaction. And (3) the circulating hydrogen is extracted from the tops of the first-stage reaction kettle and the second-stage reaction kettle, and is mixed with supplemented new hydrogen and returned to the second-stage reaction kettle after being cooled, washed to remove ammonia and pressurized by a circulating hydrogen compressor.
In this example, the first-stage reactor diaminotoluene conversion rate is 75%, the second-stage reactor diaminotoluene conversion rate is 68%, the total conversion rate of diaminotoluene is 94%, the selectivity of methylcyclohexanediamine is 95%, and the catalyst recovery rate 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 specifically comprises the following steps:
s1, conveying solid diaminotoluene to a material dissolving tank filled with 2 times of volume of 1, 4-dioxane solvent by a spiral material conveyer under the condition of stirring at 30-35 ℃ under normal pressure, and stirring to dissolve the diaminotoluene. The raw material solution in which the diaminotoluene is dissolved is pumped to a raw material buffer tank.
S2, the raw material solution is conveyed to the primary reaction kettle through a high-pressure pump, is stirred and mixed with the catalyst slurry circularly returned to the reaction kettle from the membrane separation equipment, and is introduced into the primary reaction kettle from the bottom. The ratio of the solvent to the diamino toluene to the catalyst is 2 to 1 to 0.01; and (3) hydrogen gas and the raw material solution (circulation volume ratio) is 15: 1, the reaction temperature is 160-165 ℃, the reaction pressure is 5.0-5.5MPa (G), the rotation speed of a stirrer is 100 r/min, the reaction residence time is 1 hour, and the reaction liquid phase and the catalyst overflow into a second-stage reaction kettle through an 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 rotating speed of the stirrer is 300 r/min, and circulating hydrogen is introduced into the secondary reaction kettle from the bottom; the hydrogen gas/raw material solution (cycle volume ratio) was 5/1, and the reaction residence time was 1.5 hours. The reaction produces methylcyclohexanediamine and a small amount of deamination by-products.
S3, overflowing the reaction product, the solvent and the catalyst out of the secondary reaction kettle in a mixed state, reducing the pressure by a pressure reducing valve, flashing partial solvent by a flash tower, pumping and cooling the material at the bottom of the flash tower to 50 ℃ and 0.2-0.3 MPa (G), then feeding the material into a membrane separator, 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 10 wt% and the concentration of the methylcyclohexanediamine to be less than or equal to 15 wt%. And (3) the liquid-phase material is sent to a recovery tower to recover the solvent and is rectified by a rectifying tower to obtain the product methyl cyclohexanediamine. The slurry containing the catalyst enters a catalyst buffer tank under self-pressure, is pressurized by a pump and is sent to a first-stage reaction kettle, and circularly participates in the reaction. And (3) the circulating hydrogen is extracted from the tops of the first-stage reaction kettle and the second-stage reaction kettle, and is mixed with supplemented new hydrogen and returned to the second-stage reaction kettle after being cooled, washed to remove ammonia and pressurized by a circulating hydrogen compressor.
In this example, the first-stage reactor diaminotoluene conversion rate is 70.2%, the second-stage reactor diaminotoluene conversion rate is 66.5%, the total conversion rate of diaminotoluene is 92%, the selectivity of methylcyclohexanediamine is 90%, and the catalyst recovery rate is 99.97%.
Example 3
The embodiment discloses a method for synthesizing methylcyclohexanediamine by selective hydrogenation of diaminotoluene by a continuous method, which specifically comprises the following steps:
s1, conveying solid diaminotoluene to a material dissolving tank filled with 5 times volume of 1, 4-dioxane solvent by a spiral material conveyer under the condition of stirring at 40-45 ℃ under normal pressure, and stirring to dissolve the diaminotoluene. The raw material solution in which the diaminotoluene is dissolved is pumped to a raw material buffer tank.
S2, the raw material solution is conveyed to the primary reaction kettle through a high-pressure pump, is stirred and mixed with the catalyst slurry circularly returned to the reaction kettle from the membrane separation equipment, and is introduced into the primary reaction kettle from the bottom. The dosage ratio of the materials is 5: 1: 0.06; and (3) hydrogen gas and the raw material solution (the circulation volume ratio) is 16: 1, the reaction temperature is 175-180 ℃, the reaction pressure is 7.0-7.5MPa (G), the rotation speed of a stirrer is 200 revolutions per minute, the reaction retention time is 1.5 hours, and the reaction liquid phase and the catalyst overflow into the second-stage reaction kettle through an outlet at the upper part of the first-stage reaction kettle to continue the hydrogenation reaction.
The reaction temperature in the secondary reaction kettle is 175-180 ℃, the reaction pressure is 6.8-7.2MPa (G), the rotating speed of the stirrer is 100 revolutions per minute, and circulating hydrogen is introduced into the secondary reaction kettle from the bottom; the hydrogen gas/raw material solution (cycle volume ratio) was 5/1, and the reaction residence time was 1 hour. The reaction produces methylcyclohexanediamine and a small amount of deamination by-products.
S3, overflowing the reaction product, the solvent and the catalyst out of the secondary reaction kettle in a mixed state, reducing the pressure by a pressure reducing valve, flashing partial solvent by a flash tower, pumping and cooling the material at the bottom of the flash tower to 50 ℃ and 0.2-0.3 MPa (G), then feeding the material into a membrane separator, 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 10 wt% and the concentration of the methylcyclohexanediamine to be less than or equal to 15 wt%. And (3) the liquid-phase material is sent to a recovery tower to recover the solvent and is rectified by a rectifying tower to obtain the product methyl cyclohexanediamine. The slurry containing the catalyst enters a catalyst buffer tank under self-pressure, is pressurized by a pump and is sent to a first-stage reaction kettle, and circularly participates in the reaction. And (3) the circulating hydrogen is extracted from the tops of the first-stage reaction kettle and the second-stage reaction kettle, and is mixed with supplemented new hydrogen and returned to the second-stage reaction kettle after being cooled, washed to remove ammonia and pressurized by a circulating hydrogen compressor.
In this example, the first-stage reactor diaminotoluene conversion rate is 73.6%, the second-stage reactor diaminotoluene conversion rate is 65.4%, the total conversion rate of diaminotoluene is 89%, the selectivity of methylcyclohexanediamine is 87%, and the catalyst recovery rate is 99.95%.
The embodiments described above are some, but not all embodiments of the invention. The detailed description of the embodiments of the present 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 derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Claims (10)
1. A method for synthesizing methylcyclohexanediamine by selective hydrogenation of diaminotoluene by a continuous method 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 to perform hydrogenation reaction;
s3, continuously discharging mixed gas of byproduct gas and unreacted hydrogen from the top of the reactor, cooling, washing with water to remove ammonia, pressurizing, mixing with supplemented new hydrogen, 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 a liquid-phase material;
s4, returning the slurry containing the catalyst to the reactor to participate in the hydrogenation reaction again; and (3) recovering the solvent and rectifying the liquid phase material to obtain the methylcyclohexanediamine.
2. The method of claim 1, wherein in S2, at least two hydrogenation reactors are connected in series, the raw material solution is continuously fed into the first-stage reactor by a pump, and after reacting for a period of time, the reaction liquid phase and the catalyst continuously overflow into the second-stage reactor through an upper outlet of the first-stage reactor to continue the hydrogenation reaction.
3. The method for continuously and selectively hydrogenating diaminotoluene to synthesize methylcyclohexanediamine as claimed in claim 1, wherein the raw material solution obtained in S1 is sent to a raw material buffer tank, and then sent to the reactor from the raw material buffer tank.
4. The method for continuously and selectively hydrogenating diaminotoluene to synthesize methylcyclohexanediamine as claimed in claim 1, wherein the solvent removed by flash evaporation in S3 and the solvent recovered by distillation in S4 are returned to S1 for dissolving diaminotoluene.
5. The method for continuously and selectively hydrogenating diaminotoluene to synthesize methylcyclohexanediamine as claimed in claim 1, wherein in S4, the slurry containing the catalyst is first sent to the catalyst buffer tank, and then continuously sent to the reactor through the catalyst buffer tank to participate in the reaction.
6. The continuous selective hydrogenation of diaminotoluene to methylcyclohexanediamine as claimed in any one of claims 1 to 5, wherein the mass ratio of solvent to diaminotoluene to catalyst is from 2 to 5 to 1 to 0.01 to 0.06, preferably from 3 to 1 to 0.05.
7. The method for continuously synthesizing methylcyclohexanediamine through the selective hydrogenation of diaminotoluene according to any one of claims 1 to 5, wherein the reaction temperature is 160 to 190 ℃ and the reaction pressure is 4.8 to 9.0 MPa.
8. The method for continuously and selectively hydrogenating diaminotoluene to synthesize methylcyclohexanediamine as claimed in any one of claims 1 to 5, wherein the reaction pressure in the primary reactor is 5.0 to 9.0MPa and the reaction pressure in the secondary reactor is 4.8 to 8.8 MPa.
9. The method for continuously synthesizing methylcyclohexanediamine through the selective hydrogenation of diaminotoluene according to any one of claims 1 to 5, wherein the raw material solution is reacted in the primary reactor for 1 to 1.5 hours, and the reaction liquid phase and the catalyst enter the secondary reactor and are reacted in the secondary reactor for 1.0 to 2 hours.
10. The method for continuously synthesizing methylcyclohexanediamine through the selective hydrogenation of diaminotoluene according to any one of claims 1 to 5, wherein the catalyst-containing slurry obtained through membrane separation and solvent replacement has a solid catalyst concentration of 10 wt% or less and a methylcyclohexanediamine concentration of 15 wt% or less.
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| CN105801536A (en) * | 2016-04-07 | 2016-07-27 | 上海华谊（集团）公司 | Method for preparing succinic anhydride from maleic anhydride through liquid-phase selective hydrogenation |
| 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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| CN105801536A (en) * | 2016-04-07 | 2016-07-27 | 上海华谊（集团）公司 | Method for preparing succinic anhydride from maleic anhydride through liquid-phase selective hydrogenation |
| 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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