CN117623940A - Method for preparing 4,4' -HMDA with low trans-trans isomer content - Google Patents
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- 238000000034 method Methods 0.000 title claims abstract description 23
- 239000003054 catalyst Substances 0.000 claims abstract description 50
- 238000006243 chemical reaction Methods 0.000 claims abstract description 36
- 239000002994 raw material Substances 0.000 claims abstract description 16
- YBRVSVVVWCFQMG-UHFFFAOYSA-N 4,4'-diaminodiphenylmethane Chemical compound C1=CC(N)=CC=C1CC1=CC=C(N)C=C1 YBRVSVVVWCFQMG-UHFFFAOYSA-N 0.000 claims abstract description 10
- 239000007788 liquid Substances 0.000 claims abstract description 8
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 6
- 239000001257 hydrogen Substances 0.000 claims abstract description 6
- 239000007858 starting material Substances 0.000 claims description 9
- 239000002904 solvent Substances 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 6
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- 239000002184 metal Substances 0.000 claims description 6
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 claims description 4
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 2
- 239000007789 gas Substances 0.000 claims description 2
- 239000000395 magnesium oxide Substances 0.000 claims description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 2
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 2
- 239000000463 material Substances 0.000 claims description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 2
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims description 2
- 229910052763 palladium Inorganic materials 0.000 claims description 2
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 2
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 2
- 229910001928 zirconium oxide Inorganic materials 0.000 claims description 2
- 239000012527 feed solution Substances 0.000 claims 1
- NAQMVNRVTILPCV-UHFFFAOYSA-N hexane-1,6-diamine Chemical compound NCCCCCCN NAQMVNRVTILPCV-UHFFFAOYSA-N 0.000 abstract description 8
- 238000011282 treatment Methods 0.000 abstract description 4
- 238000001514 detection method Methods 0.000 abstract description 2
- JWUJQDFVADABEY-UHFFFAOYSA-N 2-methyltetrahydrofuran Chemical compound CC1CCCO1 JWUJQDFVADABEY-UHFFFAOYSA-N 0.000 description 18
- 238000005984 hydrogenation reaction Methods 0.000 description 16
- 230000000694 effects Effects 0.000 description 7
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 5
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- 238000010924 continuous production Methods 0.000 description 4
- 238000004817 gas chromatography Methods 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N monobenzene Natural products C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- BTANRVKWQNVYAZ-UHFFFAOYSA-N butan-2-ol Chemical compound CCC(C)O BTANRVKWQNVYAZ-UHFFFAOYSA-N 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 3
- 229910052707 ruthenium Inorganic materials 0.000 description 3
- 238000006467 substitution reaction Methods 0.000 description 3
- 229910052720 vanadium Inorganic materials 0.000 description 3
- OXMIDRBAFOEOQT-UHFFFAOYSA-N 2,5-dimethyloxolane Chemical compound CC1CCC(C)O1 OXMIDRBAFOEOQT-UHFFFAOYSA-N 0.000 description 2
- DZIHTWJGPDVSGE-UHFFFAOYSA-N 4-[(4-aminocyclohexyl)methyl]cyclohexan-1-amine Chemical compound C1CC(N)CCC1CC1CCC(N)CC1 DZIHTWJGPDVSGE-UHFFFAOYSA-N 0.000 description 2
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 2
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 2
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 2
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- 230000015572 biosynthetic process Effects 0.000 description 2
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- 150000002989 phenols Chemical class 0.000 description 2
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 2
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 2
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 description 1
- JKTCBAGSMQIFNL-UHFFFAOYSA-N 2,3-dihydrofuran Chemical compound C1CC=CO1 JKTCBAGSMQIFNL-UHFFFAOYSA-N 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- 241000282326 Felis catus Species 0.000 description 1
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- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
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- KEIQPMUPONZJJH-UHFFFAOYSA-N dicyclohexylmethanediamine Chemical compound C1CCCCC1C(N)(N)C1CCCCC1 KEIQPMUPONZJJH-UHFFFAOYSA-N 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
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- AFRJJFRNGGLMDW-UHFFFAOYSA-N lithium amide Chemical compound [Li+].[NH2-] AFRJJFRNGGLMDW-UHFFFAOYSA-N 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- SYSQUGFVNFXIIT-UHFFFAOYSA-N n-[4-(1,3-benzoxazol-2-yl)phenyl]-4-nitrobenzenesulfonamide Chemical class C1=CC([N+](=O)[O-])=CC=C1S(=O)(=O)NC1=CC=C(C=2OC3=CC=CC=C3N=2)C=C1 SYSQUGFVNFXIIT-UHFFFAOYSA-N 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
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- 230000002035 prolonged effect Effects 0.000 description 1
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- 230000001172 regenerating effect Effects 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000004383 yellowing Methods 0.000 description 1
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a method for preparing 4,4' -HMDA with low trans-trans isomer content, which comprises the following steps: in the presence of a catalyst, a raw material liquid containing 4,4' -diaminodiphenyl methane and hydrogen are respectively subjected to continuous kettle reaction at a feeding speed which varies with time. The catalyst performance can be improved over 2000h without significant attenuation without other special treatments, and the maximum treatment capacity of the catalyst reaches 30gMDA/gCAT h. In addition, the detection frequency can be reduced, and the cost is further saved. Wherein the MDA conversion rate is more than 99%, the HMDA yield reaches more than 90%, and the content of the trans-trans isomer is stabilized by about 17%.
Description
Technical Field
The invention relates to the field of hydrogenation, in particular to a process for continuously producing 4,4 '-diamino dicyclohexylmethane (4, 4' -HMDA) by taking 4,4 '-diamino diphenylmethane (4, 4' -MDA) as a raw material.
Background
The 4,4'-HMDA is mainly prepared by high-pressure catalytic hydrogenation of 4,4' -MDA, and a mixture of three configuration isomers, namely cis-cis, cis-trans and trans-trans isomers, is obtained. Among the three isomers, the trans-trans isomer is thermodynamically most stable, and high temperature reaction is advantageous for its formation. The different isomer ratios determine the value of application when the trans-trans isomer content is below 24%, i.e. PACM20. Because PACM20 does not contain double bonds, the prepared 4,4 '-dicyclohexylmethane diisocyanate (4, 4' -HMDI) has the characteristics of unique yellowing resistance and weather resistance, and is an important intermediate in polyurethane and polyamide industries. In addition, it is used as amine epoxy curing agent. With the economic development, the demands of the technology in the domestic and foreign markets are increasing year by year.
CN106631826a discloses a preparation method of diamino dicyclohexylmethane, which improves the activity of a catalyst through the acidity of a phenolic compound, reduces the generation of high-boiling tar, thereby prolonging the service life of the catalyst and improving the production efficiency, but the introduced phenolic compound has a similar boiling point with a product, and increases the energy consumption during refining.
CN110204447a discloses a method for regenerating catalyst in the continuous production process of 4,4' -diamino dicyclohexyl methane, which comprises the steps of sequentially switching liquid ammonia-alkali metal salt solution-liquid ammonia to replace and wash, then modifying at high temperature, and simultaneously generating a large amount of wastewater.
CN103265438A discloses a method for preparing 4,4' -HMDA by hydrogenation of 4,4' -MDA, wherein 4,4' -MDA is used for preparing 4,4' -HMDA by hydrogenation, when the activity of the catalyst is reduced, the catalyst is switched to a mixture of 24' -MDA and 4,4' -MDA, and after the activity is stabilized, the catalyst is switched to 4,4' -MDA. The catalyst activity is recovered by switching different feeds, and the device co-produces different products.
CN111804324a discloses a method that the addition of lithium amide can reduce the proportion of anti-trans isomer in the product and increase the selectivity of the product. By reaction with water, liOH and NH are formed 3 The secondary modification of the catalyst improves the product selectivity, and the problem of catalyst activity is not mentioned. LiOH and NH formed 3 The catalyst has strong alkalinity, can improve the selectivity after long-term use, can also cause serious corrosion to the catalyst carrier, damage the carrier structure, and cause a certain degree of influence on the activity and the service life of the catalyst, and is not beneficial to long-time operation of the continuous process.
EP0231788A discloses an improved batch hydrogenation process, which uses THF as a solvent and bimetallic rhodium and ruthenium components as catalysts, and has the problem of catalyst performance degradation after long-period use.
US20020198409a discloses a continuous hydrogenation reduction process for MDA, in which when the catalyst reaction activity is reduced, the catalyst is washed with a solvent at a standstill.
US5196594a discloses a continuous hydrogenation reduction MDA process with supported ruthenium as catalyst, although the yield of HMDA can reach 93.7%, the efficiency is relatively low, the amount of raw materials processed per hour is only 0.04-0.1Kg MDA/Kg Cat, which is a challenge for industrial devices requiring efficient production.
In summary, the prior art has the following drawbacks: the problem of catalyst life exists in the production of 4,4' -HMDA by either batch or continuous processes, and the regeneration scheme is complex and requires additional process flows as the catalyst becomes progressively deactivated with the increase of catalyst life. The catalysts are not sufficiently efficient, generally have a throughput of 0.04 to 0.1kg MDA/kg cat per hour, and have low conversions and selectivities. While ensuring high conversion, higher reaction temperatures and pressures are often required, which is detrimental to the formation of the low anti-trans isomer.
Disclosure of Invention
The invention aims at the defects of the prior art and provides a method for preparing 4,4' -HMDA with low trans-trans isomer content. Adopts a kettle type continuous production process, has low production cost and high efficiency, and produces low-reverse HMDA.
In order to achieve the purpose of the invention, the technical scheme adopted is as follows:
a process for preparing 4,4' -HMDA having a low trans-trans isomer content comprising the steps of: in the presence of a catalyst, a raw material liquid containing 4,4' -diaminodiphenyl methane and hydrogen are respectively subjected to continuous kettle reaction at a feeding speed which varies with time.
The concentration omega of the raw material liquid containing 4,4' -diaminodiphenyl methane is 20-60 wt percent, and the raw material liquid is calculated by taking the mass of the solvent and the raw material as the reference.
The purity of the 4,4' -diaminodiphenyl methane is more than or equal to 99.5 percent.
The solvent is one or more selected from methanol, ethanol, isopropanol, n-butanol, 2-butanol, dihydrofuran, tetrahydrofuran, 2-methyltetrahydrofuran, 2, 5-dimethyltetrahydrofuran and dioxane.
The feed rate of the raw material liquid containing 4,4' -diaminodiphenyl methane is as followsWherein T is a flow rate control period, is an integer of which the T is more than or equal to 8 and less than or equal to 24, and is in unit of h, T is an integer of which the running time is more than or equal to 0 and less than or equal to 2000, and is in unit of h.
For example, the product in each control period is collected, sampled and analyzed, for example, the control period is 8 hours, the products in 8 hours are collected in the same product tank, uniformly mixed, 3 to 5 drops of the product are taken and dissolved in 1ml of ethanol, and the analysis is performed by gas chromatography, for example, the analysis method is as follows: the gas chromatography was Agilent 7890B, DB-5 capillary chromatography column, FID detector temperature 300 ℃, initial column temperature 50 ℃,10 ℃/min rise to 300 ℃, 20min hold.
The feeding speed of the hydrogen is V Air flow ＝6K 1 V m ωV Material /M MDA L/h, where 1.1.ltoreq.K 1 ≤1.5，V m For a standard gas molar volume of 22.4L/mol, M MDA The molar mass of the MDA starting material was 198g/mol.
In the method of the invention, the maximum value of the mass space velocity of the catalyst in a control period is not more than 30 gMDA/gCAT.
The catalyst of the invention is a supported catalyst and comprises active metal and a carrier.
The active metal of the present invention includes one or more of Pd, pt, ir, co, ru, rh.
The carrier comprises one or more of aluminum oxide, activated carbon, silicon oxide, zirconium oxide, diatomite, barium sulfate, magnesium oxide, titanium oxide and calcium carbonate.
The catalyst according to the invention has an active metal content of 0.1 to 10 wt.%, preferably 2 to 4 wt.%.
The catalyst of the invention is preferably Ru/SiO 2 。
The reaction temperature is 100-200 ℃, the reaction pressure is 3-12 MPa, preferably 140-150 ℃ and 5-8 MPa.
The MDA conversion rate is more than 99%, the HMDA yield reaches more than 90%, the content of the trans-trans isomer is about 17%, the content of the heavy component is not more than 5%, the rest components are light components and partial hydrogenation products, and the catalyst performance is more than 2000 hours without obvious attenuation.
The invention provides a method for preparing 4,4' -HMDA with low trans-trans isomer content, because the product obtained after hydrogenation has three different isomers, the trans-trans isomer content is limited by a catalyst and is also influenced by the reaction degree, when the reaction is excessive, the low trans-trans product can undergo isomerization reaction and gradually convert into a thermodynamically more stable high trans-trans product, namely, the cis-cis isomer and the cis-trans isomer in the low trans-trans product are gradually converted into the trans-trans isomer, the raw material conversion rate is improved under the condition of realizing low flow rate through the periodicity control of the function and the specific hydrogen flow rate, and the trans-trans isomer is further reduced under the condition of high flow rate, so that the isomer conversion is reduced. The mixed products with different reaction degrees are obtained in one feeding rate period, and the interconversion among isomers is reduced, so that the conversion rate of raw materials can be improved in the feeding period, and the trans-trans isomer content of the products is reduced. If fed directly at high flow rates, a large amount of partial hydrogenation products, i.e. mono-benzene ring hydrogenation products (H 6 MDA) can be accumulated, and after the hydrogenation product of the mono-benzene ring is further fed from high speed to low speed, the replacement time of the hydrogenation product in the continuous kettle is prolonged after the low speed feeding, so that the hydrogenation product of the mono-benzene ring (H) 6 MDA) is added, if the conversion of isomers is increased by prolonging the time of feeding at a low speed, resulting in an increase in the content of the anti-reflection substances, the periodic function controls the flow rate trend of the raw material liquid to gradually decrease from low to high, and the pause feeding control is added after feeding at a high speed to slow stop, so that partial hydrogenation products can be obtainedDeep hydrogenation is carried out, excessive accumulation is avoided, and the product yield is increased. The catalyst performance can be improved over 2000h without significant attenuation without other special treatments, and the maximum treatment capacity of the catalyst reaches 30gMDA/gCAT h. Meanwhile, the detection frequency can be reduced, and the cost is further saved.
Detailed Description
To further illustrate the invention, experiments were performed as described above, but the listed procedures and data are not meant to limit the scope of the invention. The experimental results were analyzed by gas chromatography.
The raw materials used in the following examples or comparative examples are all commercially available industrial-grade conventional raw materials, and the main raw materials and test instrument information are as follows, unless otherwise specified:
the 4,4 '-diaminodiphenylmethane (4, 4' -MDA) raw material is from Wanhua chemistry and has a purity of more than 99%.
2-methyltetrahydrofuran was purchased from Beijing enokic technologies, inc., analytically pure.
The catalyst was purchased from Zhuang Xinmo Feng Co.
The gas chromatography was Agilent 7890B, DB-5 capillary chromatography column, FID detector temperature 300 ℃, initial column temperature 50 ℃,10 ℃/min rise to 300 ℃, 20min hold. Wherein t, t-H 12 MDA is the content of trans-trans isomer, and the other is mainly light component and mono-benzene ring hydrogenation product.
Example 1
800g of solvent 2-methyltetrahydrofuran and 4wt% Ru/SiO are added into a reaction kettle (the volume of the kettle is 2L) 2 7.5g of catalyst. With N of 1MPa 2 After three substitutions, H of 1MPa is used again 2 The displacement is performed three times. Thereupon H 2 And the pressure is complemented to 1MPa. The reaction temperature was raised to 145℃and the pressure was maintained at 5MPa.
The 4,4' -MDA was prepared into a solution of 35wt% 2-methyltetrahydrofuran (based on the total weight of the starting material and 2-methyltetrahydrofuran), the flow rate was controlled for a period of T=8h, and V was controlled for the period Air flow Between 0 and 78L/h (K) 1 =1.1), the maximum mass space velocity of the catalyst in the control period is 14.0h -1 。
The results were as follows:
example 2
The 4,4' -MDA concentration in example 1 was changed to 40wt% of 2-methyltetrahydrofuran solution (based on the total weight of the starting material and 2-methyltetrahydrofuran), the flow rate was controlled for a period of T=12h, V Air flow Between 0 and 98L/h (K) 1 =1.2), the maximum mass space velocity of the catalyst in the control period is 16.0h -1 The reaction temperature was 140℃and the reaction pressure was 5MPa.
The results were as follows:
example 3
The 4,4' -MDA concentration in example 1 was changed to 45% by weight of 2-methyltetrahydrofuran solution (based on the total weight of the starting material and 2-methyltetrahydrofuran), the flow rate was controlled for a period of T=16 h, V Air flow Between 0 and 110L/h 0 (K) 1 =1.2), the maximum mass space velocity of the catalyst in the control period is 18.0h -1 The reaction temperature was 150℃and the reaction pressure was 7MPa.
The results were as follows:
example 4
To a reaction vessel (volume of the vessel: 2L), 800g of 2-methyltetrahydrofuran as a solvent and 6.0g of 4wt% Rh/C catalyst were added. With N of 1MPa 2 After three substitutions, H of 1MPa is used again 2 The displacement is performed three times. Thereupon H 2 And the pressure is complemented to 1MPa. The reaction temperature was raised to 145℃and the pressure was maintained at 5MPa.
The 4,4' -MDA was formulated as a 35wt% solution of 2-methyltetrahydrofuran (based on the total weight of starting material and 2-methyltetrahydrofuran) with a flow rate control period of t=12h, v Air flow Between 0 and 78L/h (K) 1 =1.1) control of intra-cycle catalysisThe maximum mass space velocity of the catalyst is 17.5h -1 。
The results were as follows:
example 5
The 4,4' -MDA concentration in example 4 was changed to 40wt% of 2-methyltetrahydrofuran solution (based on the total weight of the starting material and 2-methyltetrahydrofuran), the flow rate was controlled for a period of T=16 h, V Air flow Between 0 and 98L/h (K) 1 =1.2), the maximum mass space velocity of the catalyst in the control period is 20.0h -1 The reaction temperature was 140℃and the reaction pressure was 5MPa.
The results were as follows:
example 6
The 4,4' -MDA of example 4 was formulated as a 55wt% solution of 2-methyltetrahydrofuran (based on the total weight of starting material and 2-methyltetrahydrofuran) and the flow rate was controlled for a period of T=24h, V Air flow Between 0 and 157L/h (K) 1 =1.4), the maximum mass space velocity of the catalyst in the control period is 27.5h -1 The reaction temperature was 150℃and the reaction pressure was 7MPa.
The results were as follows:
comparative example 1
Adding 800g of solvent 2-methyltetrahydrofuran, ru/SiO into a reaction kettle (the volume of the kettle is 2L) 2 7.5g of catalyst. With N of 1MPa 2 After three substitutions, H of 1MPa is used again 2 The displacement is performed three times. Thereupon H 2 And the pressure is complemented to 1MPa. The reaction temperature was raised to 145℃and the pressure was maintained at 5MPa.
The 4,4' -MDA was formulated as a 35wt% strength solution in 2-methyltetrahydrofuran (starting material and 2-methyltetrahydrofuranTotal weight of hydrofuran), maintaining a high constant feed rate of 300g/h, V Air flow ＝78L/h
The results were as follows:
comparative example 2
The feed rate in comparative example 1 was changed to a low flow rate feed, and the feed rate was 75g/h.
The results were as follows:
Claims (9)
1. a process for preparing 4,4' -HMDA having a low trans-trans isomer content comprising the steps of: in the presence of a catalyst, a raw material liquid containing 4,4' -diaminodiphenyl methane and hydrogen are respectively subjected to continuous kettle reaction at a feeding speed which varies with time.
2. The method according to claim 1, wherein the feed rate of the feed solution containing 4,4' -diaminodiphenylmethane isWherein T is a flow rate control period, is an integer of which the T is more than or equal to 8 and less than or equal to 24, and is in unit of h, T is an integer of which the running time is more than or equal to 0 and less than or equal to 2000, and is in unit of h.
3. The method according to claim 1 or 2, wherein the hydrogen is fed at a rate V Air flow ＝6K 1 V m ωV Material /M MDA L/h, where 1.1.ltoreq.K 1 ≤1.5，V m For a standard gas molar volume of 22.4L/mol, M MDA The molar mass of the MDA starting material was 198g/mol.
4. A process according to any one of claims 1 to 3, wherein the concentration ω of the 4,4' -diaminodiphenylmethane-containing feedstock is from 20 to 60wt%, based on the mass of solvent and feedstock.
5. The method of any one of claims 1-4, wherein the mass space velocity of the catalyst does not exceed a maximum of 30 gda/gCAT x h over a control period.
6. The method of any one of claims 1-5, wherein the catalyst is a supported catalyst comprising an active metal and a support; the active metal comprises one or more of Pd, pt, ir, co, ru, rh; the carrier comprises one or more of aluminum oxide, activated carbon, silicon oxide, zirconium oxide, diatomite, barium sulfate, magnesium oxide, titanium oxide and calcium carbonate.
7. The method according to any of claims 1 to 6, characterized in that the active metal content in the catalyst is 0.1 to 10wt%, preferably 2 to 4wt%.
8. The method according to any one of claims 1 to 7, wherein the catalyst is preferably Ru/SiO 2 。
9. The process according to any one of claims 1 to 8, wherein the reaction temperature is 100 to 200 ℃, the reaction pressure is 3 to 12MPa, preferably 140 to 150 ℃,5 to 8MPa.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311675637.6A CN117623940A (en) | 2023-12-08 | 2023-12-08 | Method for preparing 4,4' -HMDA with low trans-trans isomer content |
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