Method for preparing 4, 4 '-diaminodicyclohexylmethane with high trans-trans content through continuous hydrogenation

Abstract

The invention provides a method for preparing 4, 4 '-diaminodicyclohexylmethane with high trans-trans content through continuous hydrogenation, the problems of low MDA conversion rate and low H12MDA yield are solved through a circulating process of connecting a fixed bed reactor with a rectifying tower, and the yield of 4, 4'-diaminodicyclohexylmethane is increased by controlling the air speed of a reaction solution, performing continuous hydrogenation and improving the efficiency and yield of hydrogenation reaction, so that the yield of 4, 4 '-diaminodicyclohexylmethane with high trans-trans content is increased. A post-treatment scheme of unreacted materials is provided, the cost is reduced, and the preparation process is simple, easy to operate, high in safety, short in reaction time and suitable for large-scale industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of organic compound preparation, and specifically relates to a method for preparing 4,4′-diaminodicyclohexylmethane with high anti-isomer content by continuous hydrogenation Background Art

[0002] H 12 MDA (4,4'-diamino-dicyclohexylmethane) is an important organic intermediate of alicyclic amines. Its main use is to prepare a new generation of anti-aging polyurethane dicyclohexylmethane diisocyanate (H 12 MDI), this type of isocyanate is suitable for preparing lightweight, stable performance polyurethane coatings and paints; H 12 MDA can also be used as a curing agent for epoxy resin.

[0003] Industrial 12 MDA is usually made from MDA (4,4'-diaminodiphenylmethane) as raw material, through high temperature and high pressure hydrogenation and purification under the action of catalyst. 12 MDA has three stereoisomers with different thermodynamic properties: trans / trans, cis / trans, and cis / cis. The composition of the isomers determines the properties and uses of the product. 12 The isomer content distribution of MDA in equilibrium state is trans-trans 50%, cis-trans 43%, and cis-cis 7%. Among the three isomers, the trans-trans isomer is the most thermodynamically stable, and high temperature reaction is conducive to its formation. After hydrogenation reaction, a mixture of the three isomers is obtained, and H 12 It is difficult to separate MDA stereoisomer mixtures in industry.

[0004] The trans-trans isomer content is about 20% 12 MDA is called H 12 MDA-20, trans-trans isomer content is about 50% H 12 MDA is called H 12 MDA-50, H 12 MDA-20 is mainly used to prepare polyurethane coatings with stable performance. 12 MDA-50 is mainly used to prepare aliphatic polyamide resin. From the perspective of material structure, when the size of the polymer material crystal is lower than the wavelength of the light wave, it allows the minimum scattering of the projected light to pass through, which is an effective way to improve the mechanical properties of the material and meet the requirements of special optical properties. 12 Microcrystalline transparent nylon prepared by MDA-50 is a new type of nylon that combines the high stress cracking resistance and chemical resistance of crystalline polymers with good thermal stability and optical properties, and has broad market application prospects.

[0005] US Patent No. 2494563 provides a method for producing high-anti-H 12 The method for isomerization of MDA uses ruthenium dioxide as a catalyst and dioxane or ethanol as a solvent to reduce 4,4'-diaminodiphenylmethane.

[0006] U.S. Patent No. 3,347,917 provides a method for selectively reducing 4,4'-diaminodiphenylmethane to generate an anti-isomer with a maximum content of 54.2 wt%. The method uses 0.1-10 wt% of a ruthenium catalyst and 5-40 wt% of ammonia, isopropyl ether or cyclohexane as a solvent, and hydrogenates at high temperature and high pressure for 1-30 minutes.

[0007] Chinese patent CN1970528 provides a lithium aluminate-based ruthenium-containing catalyst, which can hydrogenate and reduce aromatic amine compounds to alicyclic amines with high trans-content in a solvent or diluent at high temperature and high pressure.

[0008] US Patent No. 3711550 provides a method for changing H 12 The method for measuring the content of various isomers in MDA uses 0.01-1wt% of solid-supported Ru / Al2O3 as a catalyst and 0.5-10wt% of sodium hydroxide or sodium carbonate as an auxiliary agent, reacts under a certain hydrogen partial pressure and high temperature in an inert organic solvent, and can change the content ratio of the three isomers.

[0009] The preparation method disclosed in the above prior art has the following defects:

[0010] 1. The content of trans-trans isomer in the final product is low;

[0011] 2. The MDA conversion rate and target product yield are low;

[0012] 3. The reaction process is complicated and costly, which is not conducive to industrial production. Summary of the invention

[0013] In view of the above-mentioned shortcomings in the prior art, the present invention provides a method for preparing 4,4′-diaminodicyclohexylmethane with high content of reversed isomer by continuous hydrogenation, and solves the problem of MDA conversion rate and H 12 The problem of low MDA yield can be solved by controlling the space velocity of the reaction liquid, improving the efficiency and yield of the hydrogenation reaction, reducing the cost, and obtaining H 12 MDA has a high content of trans-trans isomer.

[0014] To achieve the above purpose, the technical solution of the present invention is as follows:

[0015] Step 1: The raw material MDA is dissolved in an organic solvent, and the raw material liquid mass space velocity is 0.15-0.30 g / g, and reacts in a fixed bed reactor under the action of a catalyst to generate H 12 MDA, reaction temperature 100-150°C, hydrogen pressure 9-15MPa, when the MDA content in the reaction solution excluding the solvent is between 0 and 8wt% through gas phase detection, the reaction is stopped;

[0016] Step 2: The reaction liquid of step 1 is passed through a distillation tower from a fixed bed reactor, and the unreacted MDA and incomplete hydrogenation products are returned to the hydrogenation reaction system of step 1. The mass space velocity of the reaction liquid is 0.20 to 0.40 g / g. After the reaction is completed, the feed liquid enters a separator for gas-liquid separation.

[0017] Furthermore, in step 1, the organic solvent is selected from any one or more of ethanol, tert-butanol, tetrahydrofuran, 1,4-dioxane, cyclopentane, ethylene glycol, n-propanol, and n-butanol, preferably 1,4-dioxane and tetrahydrofuran.

[0018] Furthermore, in step 1, the ratio of 1,4-dioxane to tetrahydrofuran is 15-40%:60-90%, preferably 30%:70%.

[0019] Furthermore, the reaction temperature in step 1 is 100-150°C, preferably 120°C.

[0020] Furthermore, the mass space velocity of the raw material liquid in step 1 is 0.20 g / g, and the mass space velocity of the raw material liquid in step 2 is 0.40 g / g.

[0021] Furthermore, the catalyst in step 1 is selected from any one of Co2O3, CaO, Na2CO3, Ru, Rh, Ru / LiAlO2, and Ru / Al2O3, preferably Ru / LiAlO2.

[0022] Furthermore, the concentration of the catalyst Ru / LiAlO2 in step 1 is 1wt% to 5wt%, preferably 3wt%.

[0023] Further, in step 1, the gas phase detection method is:

[0024] MDA and H were analyzed by gas chromatography. 12 For the quantitative analysis of MDA, the chromatographic analysis conditions of the samples are as follows: HP-5 chromatographic column (60m×0.25mm×0.25μm), hydrogen flame ionization detector (FID), detector temperature 270℃, H2 flow rate 25mL / min, air flow rate 300mL / min; carrier gas is N2; pure sample injection, injection volume 0.3μL; vaporization chamber temperature 270℃, split ratio 100:1.

[0025] Beneficial Effects

[0026] 4,4'-Diaminodicyclohexylmethane was prepared in a fixed bed reactor using 4,4-diaminodiphenylmethane (MDA) as raw material under the action of a catalyst, with a yield of 99-100%, an MDA conversion rate of 100%, and H 12 The content of trans-trans isomers in MDA is more than 55%. The fixed bed reactor is connected with a distillation tower. By controlling the space velocity of the reaction liquid, continuous hydrogenation is performed and the reaction hydrogenation rate is improved. The method of the invention also provides a post-processing scheme for unreacted materials, reduces production costs, and has a simple preparation process, is easy to operate, has high safety, and has a short reaction time, and is suitable for large-scale industrial production. DETAILED DESCRIPTION

[0027] The technical scheme of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0028] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0029] Instruments and test, analysis methods

[0030] Embodiment 1:

[0031] Step 1:

[0032] Weigh 500 g of 4,4'-diaminodiphenylmethane (MDA) and mix it with 3500 mL of 1,4-dioxane-tetrahydrofuran solution (3:7), stir it thoroughly and dissolve it to obtain a raw material mixed solution, load 30 g of Ru / LiAlO2 (3 wt%) into a fixed bed reactor, connect the connecting pipes between the various components of the device, pump the mixed solution into the reactor at a raw material mass space velocity of 0.20 g / g through a metering pump, introduce nitrogen into the reactor, exhaust the air in the reactor, switch to hydrogen, maintain the pressure in the reactor at 12.00 MPa, and react at 120°C. When the MDA content in the reaction solution excluding the solvent is 0-8 wt% as detected by gas phase, stop the reaction;

[0033] Step 2:

[0034] The reaction liquid passes through a distillation tower from a fixed bed reactor, and unreacted MDA and incomplete hydrogenation products are returned to the hydrogenation reaction system in step 1. The mass space velocity of the reaction liquid is 0.40 g / g. After the reaction is completed, the feed liquid enters a separator for gas-liquid separation. The separated reaction liquid is taken for HPLC analysis. The test results show that the MDA conversion rate is 100%, the yield is 99.42%, and the trans-isomer content is 59.31%.

[0035] Embodiment 2:

[0036] Step 1:

[0037] Weigh 500 g of 4,4'-diaminodiphenylmethane (MDA) and mix it with 3500 mL of 1,4-dioxane-tetrahydrofuran solution (3:7), stir it thoroughly and dissolve it to obtain a raw material mixed solution, load 30 g of Ru / LiAlO2 (3 wt%) into a fixed bed reactor, connect the connecting pipes between the various components of the device, pump the mixed solution into the reactor at a raw material mass space velocity of 0.15 g / g through a metering pump, introduce nitrogen into the reactor, exhaust the air in the reactor, switch to hydrogen introduction, maintain the pressure in the reactor at 9.00 MPa, and react at a temperature of 100°C. When the MDA content in the reaction solution excluding the solvent is 0-8 wt% as detected by gas phase, stop the reaction;

[0038] Step 2:

[0039] The reaction liquid passes through a distillation tower from a fixed bed reactor, and unreacted MDA and incomplete hydrogenation products are returned to the hydrogenation reaction system in step 1. The mass space velocity of the reaction liquid is 0.20 g / g. After the reaction is completed, the feed liquid enters a separator for gas-liquid separation. The separated reaction liquid is taken for HPLC analysis. The test results show that the MDA conversion rate is 100%, the yield is 99.19%, and the trans-isomer content is 57.26%.

[0040] Embodiment 3:

[0041] Step 1:

[0042] Weigh 500 g of 4,4'-diaminodiphenylmethane (MDA) and mix it with 3500 mL of 1,4-dioxane-tetrahydrofuran solution (3:7), stir it thoroughly and dissolve it to obtain a raw material mixed solution, load 30 g of Ru / LiAlO2 (3 wt%) into a fixed bed reactor, connect the connecting pipes between the various components of the device, pump the mixed solution into the reactor at a raw material mass space velocity of 0.30 g / g through a metering pump, introduce nitrogen into the reactor, exhaust the air in the reactor, switch to hydrogen, maintain the pressure in the reactor at 15.00 MPa, and react at a temperature of 150°C. Stop the reaction when the MDA content in the reaction solution excluding the solvent is 0-8 wt% as detected by gas phase;

[0043] Step 2:

[0044] The reaction liquid passes through a distillation tower from a fixed bed reactor, and unreacted MDA and incomplete hydrogenation products are returned to the hydrogenation reaction system in step 1. The mass space velocity of the reaction liquid is 0.40 g / g. After the reaction is completed, the feed liquid enters a separator for gas-liquid separation. The separated reaction liquid is taken for HPLC analysis. The test results show that the MDA conversion rate is 100%, the yield is 99.76%, and the trans-isomer content is 58.43%.

[0045] Embodiment 4:

[0046] Step 1:

[0047] Weigh 500 g of 4,4'-diaminodiphenylmethane (MDA) and mix it with 3500 mL of 1,4-dioxane solution, stir it thoroughly and dissolve it to obtain a raw material mixed solution, load 30 g of Ru / LiAlO2 (2 wt%) into a fixed bed reactor, connect the connecting pipes between the various components of the device, pump the mixed solution into the reactor at a raw material mass space velocity of 0.30 g / g through a metering pump, introduce nitrogen into the reactor, exhaust the air in the reactor, switch to hydrogen, maintain the pressure in the reactor at 10.00 MPa, and react at a temperature of 105°C. When the MDA content in the reaction solution excluding the solvent is 0-8 wt% by gas phase detection, stop the reaction;

[0048] Step 2:

[0049] The reaction liquid passes through a distillation tower from a fixed bed reactor, and the unreacted MDA and incomplete hydrogenation products are returned to the hydrogenation reaction system in step 1. The mass space velocity of the reaction liquid is 0.30 g / g. After the reaction is completed, the feed liquid enters a separator for gas-liquid separation. The separated reaction liquid is taken for HPLC analysis. The test results show that the MDA conversion rate is 100%, the yield is 98.38%, and the trans-isomer content is 55.27%.

[0050] Embodiment 5:

[0051] Step 1:

[0052] Weigh 500 g of 4,4'-diaminodiphenylmethane (MDA) and mix it with 3500 mL of tetrahydrofuran solution, stir it thoroughly and dissolve it to obtain a raw material mixed solution, load 30 g of Ru / LiAlO2 (1 wt%) into a fixed bed reactor, connect the connecting pipes between the various components of the device, pump the mixed solution into the reactor at a raw material mass space velocity of 0.15 g / g through a metering pump, introduce nitrogen into the reactor, exhaust the air in the reactor, switch to hydrogen, maintain the pressure in the reactor at 10.00 MPa, and react at a temperature of 100°C. When the MDA content in the reaction solution excluding the solvent is 0-8 wt% as detected by gas phase, stop the reaction;

[0053] Step 2:

[0054] The reaction liquid passes through a distillation tower from a fixed bed reactor, and unreacted MDA and incomplete hydrogenation products are returned to the hydrogenation reaction system in step 1. The mass space velocity of the reaction liquid is 0.35 g / g. After the reaction is completed, the feed liquid enters a separator for gas-liquid separation. The separated reaction liquid is taken for HPLC analysis. The test results show that the MDA conversion rate is 100%, the yield is 98.45%, and the trans-isomer content is 55.73%.

[0055] Embodiment 6:

[0056] Step 1:

[0057] Weigh 500 g of 4,4'-diaminodiphenylmethane (MDA) and mix with 3500 mL of ethanol solution, stir and dissolve to obtain a raw material mixed solution, load 30 g of Ru / Al2O3 (0.5 wt%) into a fixed bed reactor, connect the connecting pipes between the various components of the device, pump the mixed solution into the reactor at a raw material mass space velocity of 0.10 g / g through a metering pump, introduce nitrogen into the reactor, exhaust the air in the reactor, switch to hydrogen, maintain the pressure in the reactor at 8.00 MPa, and react at 90°C. When the MDA content in the reaction solution excluding the solvent is 0-8 wt% as detected by gas phase, stop the reaction;

[0058] Step 2:

[0059] The reaction liquid passes through a distillation tower from a fixed bed reactor, and the unreacted MDA and incomplete hydrogenation products are returned to the hydrogenation reaction system in step 1. The mass space velocity of the reaction liquid is 0.15 g / g. After the reaction is completed, the feed liquid enters a separator for gas-liquid separation. The separated reaction liquid is taken for HPLC analysis. The test results show that the MDA conversion rate is 99.53%, the yield is 98.72%, and the trans-isomer content is 35.29%.

[0060] Embodiment 7:

[0061] Step 1:

[0062] Weigh 500 g of 4,4'-diaminodiphenylmethane (MDA) and mix it with 3500 mL of tetrahydrofuran solution, stir it thoroughly and dissolve it to obtain a raw material mixed solution, load 30 g of Ru / Al2O3 (6 wt%) into a fixed bed reactor, connect the connecting pipes between the various components of the device, pump the mixed solution into the reactor at a raw material mass space velocity of 0.35 g / g through a metering pump, introduce nitrogen into the reactor, exhaust the air in the reactor, switch to hydrogen introduction, maintain the pressure in the reactor at 16.00 MPa, and react at 160°C. When the MDA content in the reaction solution excluding the solvent is 0-8 wt% as detected by gas phase, stop the reaction;

[0063] Step 2:

[0064] The reaction liquid passes through a distillation tower from a fixed bed reactor, and unreacted MDA and incomplete hydrogenation products are returned to the hydrogenation reaction system in step 1. The mass space velocity of the reaction liquid is 0.45 g / g. After the reaction is completed, the feed liquid enters a separator for gas-liquid separation. The separated reaction liquid is taken for HPLC analysis. The test results show that the MDA conversion rate is 99.63%, the yield is 99.41%, and the trans-isomer content is 45.82%.

[0065] Embodiment 8:

[0066] Gas chromatography Agilent 7890A gas chromatograph was used for quantitative analysis of H12MDA and the like in the raw materials and hydrogenation mixed products. The chromatographic analysis conditions of the samples were as follows: HP-5 chromatographic column (60m×0.25mm×0.25μm), hydrogen flame ionization detector (FID), detector temperature 270°C, H2 flow rate 25mL / min, air flow rate 300mL / min; carrier gas was N2; pure sample injection, injection volume 0.3μL; vaporization chamber temperature 270°C, split ratio 100:1.

[0067] The above is a description of a specific embodiment of the present invention. It should be understood that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for illustrating the principles of the present invention. Those skilled in the art may make various non-substantial changes and improvements to the present invention without departing from the concept of the present invention, which all fall within the scope of the present invention.

Claims

1. A method for preparing 4,4′-diaminodicyclohexylmethane with high content of reversed isomer by continuous hydrogenation, comprising: Step 1: The raw material MDA is dissolved in an organic solvent, and the raw material liquid mass space velocity is 0.15-0.30 g / g, and reacts in a fixed bed reactor under the action of a catalyst to generate H 12 MDA, reaction temperature 100-150°C, hydrogen pressure 9-15MPa, when the MDA content in the reaction solution excluding the solvent is between 0 and 8wt% through gas phase detection, the reaction is stopped; Step 2: The reaction liquid of step 1 is passed through a distillation tower from a fixed bed reactor, and the unreacted MDA and incomplete hydrogenation products are returned to the hydrogenation reaction system of step 1. The mass space velocity of the reaction liquid is 0.20 to 0.40 g / g. After the reaction is completed, the feed liquid enters a separator for gas-liquid separation.

2. A method according to claim 1, characterized in that In step 1, the organic solvent is selected from any one or more of ethanol, tert-butanol, tetrahydrofuran, 1,4-dioxane, sulfolane, ethylene glycol, n-propanol, and n-butanol, preferably 1,4-dioxane and tetrahydrofuran.

3. A method as claimed in claim 2, characterized in that The ratio of 1,4-dioxane to tetrahydrofuran is 15-40%:60-90%, preferably 30%:70%.

4. A method according to claim 1, characterized in that The mass space velocity of the raw material liquid in step 1 is 0.20 g / g, and the mass space velocity of the raw material liquid in step 2 is 0.40 g / g.

5. A method according to claim 1, characterized in that The catalyst in step 1 is selected from any one of Co2O3, CaO, Na2CO3, Ru, Rh, Ru / LiAlO2, and Ru / Al2O3, preferably Ru / LiAlO2.

6. A method according to claim 1, characterized in that The concentration of the catalyst Ru / LiAlO2 is 1 wt% to 5 wt%, preferably 3 wt%.

7. A method according to claim 1, characterized in that In step 1, the gas phase detection method is: MDA and H were analyzed by gas chromatography. 12 For the quantitative analysis of MDA, the chromatographic analysis conditions of the samples were as follows: HP-5 chromatographic column (60m×0.25mm×0.25μm), hydrogen flame ionization detector (FID), detector temperature 270°C, H2 flow rate 25mL / min, air flow rate 300mL / min; carrier gas was N2; Pure sample injection, injection volume 0.3μL; vaporization chamber temperature 270℃, split ratio 100:1.