A process for the production of H 12 Process for the production of MDA

Abstract

The application discloses a method for producing H 12 MDA with low content of trans-trans isomer, which comprises the following steps: taking H6MDA and MDA as raw materials, and adding hydrogen under the action of a supported catalyst to produce H 12 MDA; the mass ratio of the H6MDA and the MDA is 1:(1-10); the content of cis isomer in the H6MDA is not less than 50wt%; and the content of trans-trans isomer in the H 12 MDA is low.

Description

Technical Field

[0001] This invention relates to a production method, and more particularly to a method for producing H with low trans-trans isomer content. 12 The method of MDA. Background Technology

[0002] H 12 MDA is an important alicyclic diamine, mainly used in the preparation of alicyclic dicyclohexylmethane diisocyanate (H2O). 12 MDI (methyl methacrylate) can be used as an epoxy resin curing agent or in the preparation of polyamide resin materials. Currently, H... 12 MDA (4,4'-diaminodicyclohexylmethane) is mainly produced by high-pressure catalytic hydrogenation of MDA (4,4'-diaminodiphenylmethane). The reaction process is as follows: the first step of the MDA hydrogenation reaction yields a partial hydrogenation product, diaminomonocyclohexylmonophenylmethane (H6MDA), which is then further hydrogenated to obtain H... 12 MDA.

[0003]

[0004] It can be seen that H 12 MDA has three isomers: cis-cis, cis-trans, and trans-trans. When H 12 When the content of the trans-trans isomer in MDA is below 24 wt% (e.g., product grade PACM20), it exhibits excellent resistance to yellowing and weathering, making it suitable for producing lightweight and stable polyurethane coatings and paints, as well as for high-end epoxy curing applications. Therefore, the preparation of H with low trans-trans isomer content... 12 MDA is a research direction that this field is dedicated to.

[0005] US patent 5196594A discloses a continuous hydrogenation reduction process for MDA, using supported ruthenium as a catalyst, although H 12 The yield of MDA can reach 93.7%, but at high yields, the content of trans-trans isomers is high, exceeding 20%.

[0006] Patent CN109851508B discloses a method for synthesizing HMDA with low trans-trans isomer content and low tar content. The method involves a two-step synthesis: partial hydrogenation under catalyst I to produce diaminomonocyclohexylmonophenylmethane (H6MDA); and complete hydrogenation of the obtained product under catalyst II to produce H… 12 MDA requires two different catalysts to complete the corresponding hydrogenation reactions, and the control process for each step is different, which increases the workload. At the same time, the hydrogenation reaction conditions are high, which is difficult and increases equipment investment and safety risks. Summary of the Invention

[0007] To address the above technical problems, this invention proposes a method for producing H with low trans-trans isomer content. 12 The method of MDA.

[0008] A method for producing H with low trans-trans isomer content 12 The MDA method uses H6MDA and MDA as raw materials to produce H by hydrogenation in the presence of a supported catalyst. 12 MDA;

[0009] The mass ratio of H6MDA to MDA is 1:(1-10); the content of cis isomer in H6MDA is not less than 50wt%.

[0010] As a preferred embodiment of the present invention, the supported catalyst comprises an active metal and a support; wherein the active metal is at least one selected from Pd, Pt, Ir, Co, Ru, and Rh; and the support is at least one selected from activated carbon, silicon dioxide, alumina, zirconium oxide, barium sulfate, and calcium carbonate.

[0011] As a preferred embodiment of the present invention, the content of active metal in the supported catalyst is 0.1-10 wt%, preferably 4-5 wt%.

[0012] As a preferred embodiment of the present invention, the amount of the supported catalyst used in the reaction is 0.5-4 wt% of the total mass of H6MDA and MDA.

[0013] As a preferred embodiment of the present invention, the hydrogenation reaction temperature is 140-160℃.

[0014] As a preferred embodiment of the present invention, in the initial stage of the reaction, the temperature is first raised to 100-110°C, and then the heating rate is controlled at 0.15-0.5°C / min until the reaction temperature is reached.

[0015] During hydrogenation, reactants diffuse to the catalyst surface and pores. The reaction is rapidly exothermic, causing the temperature on the catalyst surface or inside the pores to exceed the system temperature. Controlling the heating rate can mitigate this temperature rise within the catalyst, thus controlling the content of the trans-trans isomers. Furthermore, the introduction of H6MDA reduces the content of the reacting functional groups, further lowering the internal temperature of the catalyst and resulting in a product with an even lower trans-trans isomer content. 12 MDA, but when the trans structure content of H6MDA is higher than 50%, the isomerization reaction will increase the content of trans-trans isomers in the product.

[0016] As a preferred embodiment of the present invention, the hydrogenation reaction pressure is 3-10 MPa gauge pressure.

[0017] As a preferred embodiment of the present invention, the hydrogenation reaction is carried out in an inert solvent; the inert solvent is selected from one or more of methanol, ethanol, isopropanol, n-butanol, 2-butanol, tetrahydrofuran, 2-methyltetrahydrofuran, and dioxane.

[0018] As a preferred embodiment of the present invention, the amount of the inert solvent is such that the concentration of the mixture of H6MDA and MDA is 10-55 wt%.

[0019] The beneficial technical effects of the present invention are as follows:

[0020] (1) A method for producing low-reactive H6MDA and MDA as raw materials is provided. 12 MDA's scheme has a trans-trans isomer content as low as 15% or less;

[0021] (2) The process is safe and controllable, and the operation is simple. It can effectively avoid catalyst deactivation caused by catalyst sintering due to overheating.

[0022] (3) The product yield is high, the content of heavy components is low, and the catalyst cycle life is improved. Detailed Implementation

[0023] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0024] Unless otherwise specified, all raw materials and reagents used in this invention can be purchased commercially.

[0025] The MDA raw material is from Wanhua WANAMINE MDA-100.

[0026] H6MDA was synthesized according to the method described in patent CN110078627B, and then the cis and trans isomers were separated by conventional vacuum distillation: the bottom temperature was 180-260℃, the top temperature was 170-210℃, and the pressure was absolute 0.1-3 kPa. The cis and trans isomers were blended in a weight ratio to provide H6MDA with different cis and trans isomer contents in various embodiments and comparative examples.

[0027] Gas chromatography was performed using an Agilent 7890B DB-5 capillary column with an FID detector at 300°C. The initial column temperature was 50°C, increased to 300°C at a rate of 10°C / min, and held for 20 min. Where t, tH 12 MDA indicates the content of trans-trans isomers, while the rest are mainly light components and some incompletely hydrogenated products.

[0028]

Example 1

[0029] 2.0 g of Ru / SiO2 catalyst (Ru content 4 wt%) was added to the reactor. H6MDA (80 wt% cis isomer, 20 wt% trans isomer) and MDA were mixed at a mass ratio of 1:1.86 to obtain a total of 200 g of mixed raw material. This mixed raw material was then dissolved in 200 g of 2-methyltetrahydrofuran and added to the reactor. The gas in the reactor was purged three times with N2, followed by three purgings with H2, and then pressurized to 1 MPa with H2. The temperature was raised to 109 °C, and then maintained at a heating rate of 0.18 °C / min to increase the reaction temperature to 145 °C. Hydrogen was added during the heating and reaction process until the reaction pressure reached 5 MPa. After the reaction was completed, the product composition was analyzed, and the results are shown in Table 1.

[0030]

Example 2

[0031] 2.0 g of Pd / C catalyst (3 wt% Pd content) was added to the reactor. H6MDA (60 wt% cis isomer, 40 wt% trans isomer) and MDA were mixed at a mass ratio of 1:3 to obtain a total of 100 g of mixed feedstock. This mixed feedstock was then dissolved in 300 g of tetrahydrofuran and added to the reactor. The gas in the reactor was purged three times with N2, followed by three purgings with H2, and then pressurized to 1 MPa with H2. The temperature was raised to 107 °C, and then maintained at a heating rate of 0.48 °C / min to increase the reaction temperature to 155 °C. Hydrogen was added during the heating and reaction process until the reaction pressure reached 6 MPa. After the reaction was completed, the product composition was analyzed, and the results are shown in Table 1.

[0032]

Example 3

[0033] 2.0 g of Rh / Al₂O₃ catalyst (5 wt% Rh content) was added to the reactor. H₆MDA (70 wt% cis isomer, 30 wt% trans isomer) and MDA were mixed at a mass ratio of 1:9 to obtain a total of 200 g of mixed feedstock. This mixed feedstock was then dissolved in 300 g of isopropanol and added to the reactor. The gas in the reactor was purged three times with N₂, followed by three purgings with H₂, and then pressurized to 1 MPa with H₂. The temperature was raised to 105 °C, and then maintained at a heating rate of 0.3 °C / min until the reaction temperature reached 150 °C. Hydrogen was added during the heating and reaction process until the reaction pressure reached 7 MPa. After the reaction was completed, the product composition was analyzed, and the results are shown in Table 1.

[0034]

Example 4

[0035] 2.0 g of Pt / C catalyst (1 wt% Pt content) was added to the reactor. H6MDA (60 wt% cis isomer, 40 wt% trans isomer) and MDA were mixed at a mass ratio of 1:3 to obtain a total of 320 g of mixed feedstock. This mixed feedstock was then dissolved in 320 g of tetrahydrofuran and added to the reactor. The gas in the reactor was purged three times with N2, followed by three purgings with H2, and then pressurized to 1 MPa with H2. The temperature was raised to 110 °C, and then maintained at a heating rate of 0.15 °C / min to increase the reaction temperature to 140 °C. Hydrogen was added during the heating and reaction process until the reaction pressure reached 8 MPa. After the reaction was completed, the product composition was analyzed, and the results are shown in Table 1.

[0036]

Example 5

[0037] 2.0 g of Ru / Al₂O₃ catalyst (8 wt% Ru content) was added to the reactor. H₆MDA (60 wt% cis isomer, 40 wt% trans isomer) and MDA were mixed at a mass ratio of 1:3 to obtain a total of 200 g of mixed raw materials. The mixed raw materials were then dissolved in 200 g of ethanol and added to the reactor. The gas in the reactor was purged three times with N₂, followed by three purgings with H₂, and then pressurized to 1 MPa with H₂. The temperature was raised to 105 °C, and then maintained at a heating rate of 0.3 °C / min to increase the reaction temperature to 150 °C. Hydrogen was added during the heating and reaction process until the reaction pressure reached 7 MPa. After the reaction was completed, the product composition was analyzed, and the results are shown in Table 1.

[0038]

Example 6

[0039] 2.0 g of Ru / ZrO2 catalyst (Ru content 0.5 wt%) was added to the reactor. H6MDA (70 wt% cis isomer, 30 wt% trans isomer) and MDA were mixed at a mass ratio of 1:4 to obtain a total of 50 g of mixed feedstock. This mixed feedstock was then dissolved in 450 g of n-butanol and added to the reactor. The gas in the reactor was purged three times with N2, followed by three purgings with H2, and then pressurized to 1 MPa with H2. The temperature was raised to 102 °C, and then maintained at a heating rate of 0.4 °C / min until the reaction temperature reached 160 °C. Hydrogen was added during the heating and reaction process until the reaction pressure reached 8 MPa. After the reaction was completed, the product composition was analyzed, and the results are shown in Table 1.

[0040] Comparative Example 1

[0041] The reaction was carried out using essentially the same method as in Example 1, except that after heating to 109°C, the temperature was increased to 145°C at a rate of 0.6°C / min. After the reaction was completed, the product composition was analyzed, and the results are shown in Table 1.

[0042] Comparative Example 2

[0043] The reaction was carried out using essentially the same method as in Example 1, except that the content of the raw material H6MDA was adjusted to 40 wt% cis isomer and 60 wt% trans isomer. After the reaction was completed, the product composition was analyzed, and the results are shown in Table 1.

[0044] Table 1. Composition of products prepared in each example and comparative example

[0045]

[0046]

[0047] In addition, the catalyst packed in the reactor of Example 1 was kept unchanged, and the reaction was repeated to carry out the catalyst recycling experiment. The test results are shown in Table 2.

[0048] Table 2. Results of the cyclic application test

[0049] Number of times to apply <![CDATA[H 12 MDA / %]]> <![CDATA[t,t-H 12 MDA / %]]> Recombinant components / % other / % 1 96.78 13.1 1.23 1.99 10 96.75 13.3 1.24 2.01 20 96.72 13.2 1.25 2.03 30 96.81 13.4 1.27 1.92 40 96.77 13.5 1.29 1.94 50 96.68 13.6 1.31 2.01 60 96.66 13.6 1.33 2.01

[0050] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A method for producing H with low trans-trans isomer content 12 The method of MDA is characterized by, Using H6MDA and MDA as raw materials, hydrogenation is carried out in the presence of a supported catalyst to produce H 12 MDA; The mass ratio of H6MDA to MDA is 1:(1-10); the content of the cis isomer in the H6MDA is not less than 50 wt%. The supported catalyst comprises an active metal and a support; wherein the active metal is at least one selected from Pd, Pt, Ir, Co, Ru, and Rh; and the support is at least one selected from activated carbon, silica, alumina, zirconium oxide, barium sulfate, and calcium carbonate. In the initial stage of the reaction, the temperature is first raised to 100-110℃, and then the heating rate is controlled at 0.15-0.5℃ / min until the reaction temperature is reached.

2. The method for producing H with low trans-trans isomer content according to claim 1 12 The method of MDA is characterized by, The supported catalyst contains 0.1-10 wt% active metal.

3. The method for producing H with low trans-trans isomer content according to claim 2 12 The method of MDA is characterized by, The supported catalyst contains 4-5 wt% active metal.

4. The method for producing H with low trans-trans isomer content according to claim 2 12 The method of MDA is characterized by, The amount of the supported catalyst used in the reaction is 0.5-4 wt% of the total mass of H6MDA and MDA.

5. The method for producing H with low trans-trans isomer content according to any one of claims 1-4 12 The method of MDA is characterized by, The hydrogenation reaction temperature is 140-160℃.

6. The method for producing H with low trans-trans isomer content according to any one of claims 1-4 12 The method of MDA is characterized by, The hydrogenation reaction pressure is 3-10 MPa gauge pressure.

7. The method for producing H with low trans-trans isomer content according to any one of claims 1-4 12 The method of MDA is characterized by, The hydrogenation reaction is carried out in an inert solvent; the inert solvent is selected from one or more of methanol, ethanol, isopropanol, n-butanol, 2-butanol, tetrahydrofuran, 2-methyltetrahydrofuran, and dioxane.

8. The method for producing H with low trans-trans isomer content according to claim 7 12 The method of MDA is characterized by, The amount of inert solvent used makes the concentration of the mixture of H6MDA and MDA 10-55 wt%.

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