A continuous hydro- synthesis of low trans- trans body content H 12 Method of MDA

Abstract

The application discloses a kind of continuous hydrogenation synthesis low trans-trans body content H 12 The method utilizes the differences in hydrogenation activity, selectivity and stereoisomer selectivity of Ru and Rh catalysts for MDA and intermediate H6MDA, so that the MDA-containing reaction material successively flows through reactor A filled with Ru catalyst and reactor B filled with Rh catalyst, and through control of process conditions, low trans-trans body content H 12 MDA product is obtained by hydrogenation.The application is easy to implement and has industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of alicyclic amine synthesis, specifically to the continuous hydrogenation synthesis of 4,4'-diaminodiphenylmethane (MDA) into 4,4'-diaminodicyclohexylmethane (H2O). 12 The method of MDA (Medium-to-Dose Alcoholization), particularly a method for obtaining H+ with low anti-reproduct content through continuous hydrogenation with high selectivity. 12 The method of MDA. Background Technology

[0002] H 12 MDA is an important alicyclic diamine fine chemical with wide applications in epoxy curing agents, polyurethanes and polyamides.

[0003] Industrially, hydrogenation of MDA as a raw material yields H... 12 MDA has a negative (hereinafter abbreviated as t, tH) 12 MDA), cis-reverse (hereinafter abbreviated as c,tH) 12 MDA), Shunshun (hereinafter abbreviated as c, cH) 12 MDA) has three stereoisomers, t and tH in the product. 12 The content of MDA determines the properties and uses of the product: t, tH 12 The lower the MDA content, the lower the product's freezing point, which is more conducive to its application in high-end epoxy curing agents and polyurethane fields.

[0004] H 12 MDA stereoisomers:

[0005]

[0006] Because the boiling points of the three isomers are extremely close, it is difficult to achieve effective separation of the three isomers in industry through methods such as distillation and derivatization, thereby obtaining H with low trans-trans content. 12 MDA, therefore, hydrogenation of MDA directly yields H+ with low anti-antibody content. 12 MDA is the most effective method.

[0007] MDA hydrogenation generally proceeds in two steps, as shown in the following equation: MDA first undergoes hydrogenation of a benzene ring to produce diaminomonocyclohexylmonophenylmethane (H6MDA), and then H6MDA undergoes hydrogenation of a second benzene ring to produce H... 12 MDA. H6MDA consists of two isomers: cis and trans (hereinafter abbreviated as c-H6MDA and t-H6MDA, respectively). In the second step of the reaction, t-H6MDA is hydrogenated to produce t,tH. 12 MDA and c,tH 12 MDA, c-H6MDA is hydrogenated to produce c,cH12 MDA and c,tH 12 MDA. As can be seen from the following equation, hydrogenation of c-H6MDA does not produce t,tH. 12 MDA, to obtain H with low anti-reproduct content 12 In the MDA reaction, the first step is to improve the selectivity of c-H6MDA and inhibit the formation of t-H6MDA. The second step is to inhibit the hydrogenation of t-H6MDA to form t,tH. 12 MDA.

[0008]

[0009] Regarding the hydrogenation synthesis of H from MDA 12 The following are current technical reports on MDA:

[0010] Patent CN115772086A reports a batch hydrogenation process for MDA using a Rh / Al2O3 catalyst. By adding a certain amount of N,N,N',N'-tetramethyl-MDA compound to the reaction system, the reaction process is controlled using its weak basicity and steric hindrance effect, yielding H+ with a reaction-reaction content of 10-14%. 12 MDA products.

[0011] Patent CN116023272A reports a method for producing H with low anti-reactive content using a dual-reactor series connection. 12 The MDA process uses Rh / Al₂O₃ catalyst in both reactors, n-butanol as solvent, and lithium acetate as an additive to obtain H. 12 The overall yield of MDA reached approximately 90%, with the anti-antibody content in the product being approximately 17%.

[0012] Patent CN116478048A reports a fixed-bed hydrogenation process for MDA using a Ru / Al2O3 catalyst and a n-butanol-tetrahydrofuran mixed solvent. Although it can yield H+ with a counter-counterpart content of 12-14%,... 12 MDA products are available, but this technology uses a large amount of mixed solvents and operates at low substrate concentrations and low feed space velocities, resulting in problems such as low production efficiency and high separation energy consumption.

[0013] Patent CN109851508A reports a method for synthesizing low trans-trans isomers and low tar content H. 12 The MDA method utilizes the stepwise hydrogenation characteristic of MDA. First, using a supported rhodium catalyst, MDA is hydrogenated in a reactor to obtain a reaction solution mainly containing H6MDA. This solution is then separated and added to another reactor for further hydrogenation using a supported ruthenium catalyst, ultimately yielding H6MDA with a yield greater than 98% and a content of approximately 12% in the reaction product. 12 MDA products.

[0014] In summary, existing technologies generally employ a single supported Ru or Rh catalyst, using batch or continuous processes, although this can yield H+ with a low content of the anti-antibody. 12 MDA products, but still have the following various problems:

[0015] 1) While using Rh catalyst alone is beneficial for controlling the content of the anti-antibody in the product, Rh catalyst easily catalyzes the deamination side reaction of MDA, generating various high and low boiling point impurities, resulting in low product yield. Using Ru catalyst alone can effectively suppress the deamination side reaction and improve product yield, but it is difficult to stably control the content of low anti-antibody. 2) Although adding additives can improve the yield or suppress the formation of anti-antibody, it increases the difficulty of post-processing the product. 3) Although patent CN109851508A utilizes the stepwise hydrogenation characteristics of MDA, using Rh and Ru catalysts to hydrogenate MDA and intermediate H6MDA respectively, it obtains H6MDA with an anti-antibody content of about 12%. 12 MDA products are available, but the Rh catalyst requires modification using 10 to 500 times the mass of MDA trimer under high temperature (150–250°C) and high pressure (5–15 MPa) hydrogen conditions. These conditions are quite demanding, and the disposal of the modifier after use is also a problem. Secondly, the second-step hydrogenation uses a Ru catalyst because it readily catalyzes C,CH... 12 MDA and c,tH 12 MDA undergoes an isomerization reaction to produce t,tH. 12 MDA makes it difficult to control t and tH in the product. 12 The content of MDA; finally, since both hydrogenation steps are carried out intermittently and require two filtration separations, production efficiency is severely affected.

[0016] Therefore, it is necessary to develop an efficient and stable continuous hydrogenation process for MDA to continuously and stably obtain H+ with low anti-reproduct content while ensuring high yield. 12 MDA products. Summary of the Invention

[0017] To overcome the various problems existing in the prior art, this invention develops a continuous hydrogenation synthesis method for H+ with low anti-antibody content. 12The main characteristics of the MDA method are: Reactors A and B are connected in series. Reactor A is loaded with a supported Ru catalyst, utilizing its high activity for MDA hydrogenation and relatively low activity for the hydrogenation of the intermediate H6MDA, as well as its low selectivity for the t-H6MDA isomer in MDA hydrogenation. The product mainly containing H6MDA is obtained at the outlet of reactor A, with a low t-H6MDA content. Reactor B is loaded with a supported Rh catalyst, utilizing its high activity for H6MDA hydrogenation and its low selectivity for the t,tH isomer in the hydrogenation of t-H6MDA. 12 MDA isomers have low selectivity and are not easily catalyzed at C, CH 12 MDA and c,tH 12 MDA undergoes an isomerization reaction to produce t,tH. 12 The characteristics of MDA ultimately result in H with low anti-antibody content. 12 MDA products.

[0018] To achieve the above objectives, the present invention adopts the following technical solution:

[0019] This invention provides a continuous hydrogenation synthesis of H with low anti-antibody content. 12 The MDA method involves sequentially passing a solution containing solvent and MDA through two reactors, A and B, connected in series to efficiently and stably produce H2 with low anti-reproduct content. 12 MDA products.

[0020] Preferably, reactors A and B in this invention are both fixed-bed reactors; the reactor feed and discharge methods can be either top-in-bottom-out or bottom-in-top-out, with top-in-bottom-out being preferred.

[0021] The reactor A is loaded with a supported Ru catalyst, which includes a support and an active component Ru and an auxiliary agent attached to the support.

[0022] The supported Ru catalyst support is selected from one or more of alumina, activated carbon, zirconium dioxide, and titanium dioxide.

[0023] Preferably, the supported Ru catalyst support is alumina, and according to crystal form classification, the alumina is selected from one or more of γ-Al2O3, η-Al2O3, δ-Al2O3, θ-Al2O3, k-Al2O3, and α-Al2O3, with θ-Al2O3 and / or α-Al2O3 being preferred.

[0024] The supported Ru catalyst has a specific surface area of ​​0.1–100 m². 2 / g, preferably 2-20m 2 / g.

[0025] The supported Ru catalyst has a pore volume of 0.001–2 cm³.3 / g, preferably 0.01~0.2cm 3 / g.

[0026] The supported Ru catalyst has an average pore size of 1–500 nm, preferably 30–200 nm.

[0027] The supported Ru catalyst has an average Ru crystallite size of 0.05–50 nm, preferably 4–10 nm.

[0028] The supported Ru catalyst has an auxiliary agent selected from one or more of Li, Na, K, Rb, Cs, Ca, Ba, La, B, P, Ti, Zr, and Ga, preferably one or more of K, Ca, and B.

[0029] The supported Ru catalyst has a Ru loading of 0.01–30 wt%, preferably 0.5–15 wt%, based on the total mass of the catalyst.

[0030] The supported Ru catalyst has an additive loading of 0.001–20 wt%, preferably 0.05–10 wt%, based on the total mass of the catalyst.

[0031] The reactor B is loaded with a supported Rh catalyst, which includes a support and an active component Rh and an auxiliary agent II attached to the support.

[0032] The supported Rh catalyst support is selected from one or more of alumina, activated carbon, zirconium dioxide, and titanium dioxide.

[0033] Preferably, the supported Rh catalyst support is alumina, and according to crystal form classification, the alumina is selected from one or more of γ-Al2O3, η-Al2O3, δ-Al2O3, θ-Al2O3, k-Al2O3, and α-Al2O3, with γ-Al2O3 and / or δ-Al2O3 being preferred.

[0034] The supported Rh catalyst has a specific surface area of ​​50–500 m². 2 / g, preferably 80-250m 2 / g.

[0035] The supported Rh catalyst has a pore volume of 0.05–5 cm³. 3 / g, preferably 0.1~1.5cm 3 / g.

[0036] The supported Rh catalyst has an average pore size of 0.1–100 nm, preferably 1–20 nm.

[0037] The supported Rh catalyst has an average Rh crystallite size of 0.05–10 nm, preferably 0.5–5 nm.

[0038] The supported Rh catalyst has an auxiliary agent selected from one or more of Li, Na, K, Rb, Cs, Ca, Ba, La, B, P, Ti, Zr, Ga, Fe, Co, Cu, Ni, Ag, and Mo, preferably one or more of Li and La.

[0039] The supported Rh catalyst has an Rh loading of 0.001–10 wt%, preferably 0.05–5 wt%, based on the total mass of the catalyst.

[0040] The supported Rh catalyst has an additive loading of 0.001–10 wt%, preferably 0.01–5 wt%, based on the total mass of the catalyst.

[0041] In this invention, the solvent is selected from a mixture of tetrahydrofuran and organic amines.

[0042] The organic amine is selected from one or more of the following organic amines: methylamine, dimethylamine, trimethylamine, ethylamine, ethylenediamine, diethylamine, triethylamine, propylamine, propylenediamine, propylenetriamine, butylamine, butyldiamine, pentylamine, hexylamine, hexamethylenediamine, cyclohexylamine, 1,2-cyclohexanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1,3-cyclohexanedimethylamine, 1,4-cyclohexanedimethylamine, ethanolamine, isopropanolamine, polyetheramine, etc., preferably one or more of trimethylamine, diethylamine, and cyclohexylamine.

[0043] The mass ratio of organic amine to tetrahydrofuran in the mixed solvent is 1:1 to 1:1000, preferably 1:10 to 1:100.

[0044] The mass ratio of the tetrahydrofuran and organic amine mixed solvent to MDA is 1000:1 to 1:20, preferably 50:1 to 1:10.

[0045] In this invention, the reaction temperature of reactor A is 40–200°C, preferably 60–120°C.

[0046] In this invention, the reaction temperature of reactor B is 80–250°C, preferably 120–200°C.

[0047] Reactors A and B use the same reaction pressure, which is 2 to 20 MPa, preferably 4 to 10 MPa.

[0048] The feed space velocity, expressed as the ratio of the mass of MDA feed per unit time to the mass of the supported Ru catalyst in reactor A, ranges from 0.01 to 50 g. MDA .g Ru催化剂 -1 .h-1 Preferred dosage: 0.5–5g MDA .g Ru催化剂 -1 .h -1 .

[0049] The molar ratio of hydrogen feed rate to MDA feed rate per unit time is 10:1 to 500:1, preferably 15:1 to 50:1.

[0050] The mass ratio of the supported Ru catalyst packed in reactor A to the supported Rh catalyst packed in reactor B is 1:100 to 10:1, preferably 1:10 to 1:1.

[0051] In this invention, the MDA percentage of the material emanating from reactor A after deducting the solvent is 0–10 wt%, preferably 0–5 wt%; the MDA percentage of H6 is 80–100 wt%, preferably ≥90 wt%; H 12 The MDA content is 0-10 wt%, preferably 0-5 wt%; other components (referring to those other than MDA, H6MDA, H...) 12 The total percentage content of all substances other than MDA is 0-2 wt%, preferably 0-1 wt%; the percentage content of t-H6MDA in the intermediate H6MDA is 0-20 wt%, preferably 0-15 wt%.

[0052] Compared with the prior art, the advantages of the technical solution of the present invention are as follows:

[0053] Taking advantage of the stepwise nature of MDA hydrogenation, this study utilizes Ru catalysts, which exhibit high activity for MDA hydrogenation but lower activity for H6MDA hydrogenation. Furthermore, Ru catalysts effectively suppress t-H6MDA formation during MDA hydrogenation and are less prone to catalytic deamination side reactions. By combining the synergistic effects of the catalyst active components, promoters, and supports, and by adjusting the hydrogenation process conditions, most or all of the MDA is converted into the hydrogenation intermediate H6MDA with low t-H6MDA content in reactor A. Rh catalysts, on the other hand, exhibit high activity for H6MDA hydrogenation and effectively suppress t,tH6MDA formation during t-H6MDA hydrogenation. 12 MDA is generated and is not easily catalyzed by C,CH. 12 MDA and c,tH 12 MDA undergoes an isomerization reaction to produce t,tH. 12 The characteristic of MDA is that it ultimately yields H+ with a low content of the reactants at the outlet of reactor B. 12 MDA products. This invention enables the hydrogenation of MDA to produce H2O. 12 MDA yield reached over 98%, with H 12 MDA total mass metering, in which the anti-antibody content is less than 10%. Detailed Implementation

[0054] The embodiments of the present invention are described in detail below. The specific embodiments described below are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0055] Gas chromatograph: Agilent 7890B, FID detector, DB-5 capillary column (30m x 250μm x 0.25μm), injection port 280℃, detector 300℃; temperature program: initial temperature 50℃, hold for 2 min, increase to 80℃ at 5℃ / min, then increase to 300℃ at 15℃ / min, hold for 15 min.

[0056] Quantitative analysis was performed using the external standard method to calculate the raw material conversion rate and product yield.

[0057] H6MDA and H were calculated using the peak area normalization method. 12 Percentage content of various isomers in MDA. For example, the t-H6MDA content in H6MDA = t-H6MDA peak area / (t-H6MDA peak area + c-H6MDA peak area) * 100%; H 12 In MDA, t, tH 12 MDA content = t, tH 12 MDA peak area / (t, t-H2MDA peak area + c, tH) 12 MDA peak area + c, cH 12 (MDA peak area) * 100%.

[0058] The main raw material sources in the embodiments and comparative examples of this invention are as follows. Unless otherwise specified, other raw materials and reagents were obtained through ordinary commercial channels:

[0059] MDA was provided by Wanhua Chemical Group Co., Ltd.

[0060] The relevant information for Ru catalysts is shown in the table below:

[0061]

[0062] The relevant information for Rh catalysts is shown in the table below:

[0063]

[0064] Example 1

[0065] A fixed bed (reactor A) with an inner diameter of 24 mm and a length of 60 cm was loaded with 30 g of 5% Ru-0.5% K / α-Al2O3 catalyst, with inert ceramic balls at both ends. A fixed bed (reactor B) with an inner diameter of 24 mm and a length of 60 cm was connected in series at the outlet of reactor A, and was loaded with 30 g of 2% Rh-0.1% La / γ-Al2O3 catalyst, with inert ceramic balls at both ends. The reaction apparatus was purged with nitrogen and hydrogen to remove air, then hydrogen was introduced to 6 MPa at a continuous flow rate of 500 NL / h. Reactors A and B were then heated to 250 °C at a rate of 120 °C / h and maintained for 4 hours to activate the catalyst. After activation, keeping other conditions constant, reactors A and B were cooled to 80℃ and 140℃ respectively and kept at a constant temperature. Then, the hydrogen flow rate was set to 50.9 L / h (H2 / MDA molar ratio of 15), and an MDA solution (using a mixed solvent of diethylamine and tetrahydrofuran, with a mass ratio of diethylamine to tetrahydrofuran of 1:20, a mass ratio of the mixed solvent to MDA of 1:1, and an MDA feed space velocity of 1 g) was introduced into the reactors at a rate of 60 g / h using a high-pressure constant flow pump. MDA .g Ru催化剂 -1 .h -1 The hydrogenation reaction was carried out continuously under stable conditions. After 200 hours, samples were taken from the outlets of reactors A and B, respectively, and quantitative analysis was performed using gas chromatography. The composition of the material at the outlet of reactor A, after deducting the solvent, was: MDA content 0.9 wt%, H6MDA content 95.6 wt%, H... 12 MDA content 3.1 wt%, 0.4 wt% by-products (excluding MDA, H6MDA, H...) 12 (All substances other than MDA), the t-H6MDA percentage in H6MDA is 13.0 wt%; the composition of the material at the outlet of reactor B after deducting the solvent is: MDA content 0.0 wt%, H6MDA content 0.5 wt%, H 12 MDA content 98.8 wt%, 0.7 wt% by-products (excluding MDA, H6MDA, H...) 12 All substances other than MDA), H 12 In MDA, t, tH 12 The MDA content is 6.7%.

[0066] Example 2

[0067] A fixed bed (reactor A) with an inner diameter of 24 mm and a length of 60 mm was loaded with 30 g of 10% Ru-5% Ca / θ-Al2O3 catalyst, and inert ceramic balls were placed at both ends of the fixed bed. A fixed bed (reactor B) with an inner diameter of 36 mm and a length of 120 mm was connected in series at the outlet of reactor A, and was loaded with 150 g of 0.05% Rh-0.002% Li / θ-Al2O3 catalyst, with inert ceramic balls placed at both ends of the fixed bed. The reaction apparatus was purged with nitrogen and hydrogen to remove air, then hydrogen was introduced to 4 MPa at a continuous flow rate of 1000 NL / h. Reactors A and B were then heated to 250 °C at a rate of 120 °C / h and maintained for 4 h to activate the catalyst. After activation, keeping other conditions constant, reactors A and B were cooled to 110℃ and 200℃ respectively and kept at a constant temperature. Then, the hydrogen flow rate was set to 848 L / h (H2 / MDA molar ratio of 50), and an MDA solution (using a mixed solvent of cyclohexylamine and tetrahydrofuran, with a mass ratio of cyclohexylamine to tetrahydrofuran of 1:100, a mass ratio of the mixed solvent to MDA of 1:2, and an MDA feed space velocity of 5g) was introduced into the reactors at a rate of 225g / h using a high-pressure constant flow pump. MDA .g Ru催化剂 -1 .h -1 The hydrogenation reaction was carried out continuously under stable conditions. After 200 hours, samples were taken from the outlets of reactors A and B, respectively, and quantitative analysis was performed using gas chromatography. The composition of the material at the outlet of reactor A, after deducting the solvent, was: MDA content 0.0 wt%, H6MDA content 98.4 wt%, H... 12 MDA content 1.4wt%, 0.2wt% by-products (excluding MDA, H6MDA, H...) 12 (All substances other than MDA), the t-H6MDA percentage in H6MDA is 10wt%; the composition of the material at the outlet of reactor B after deducting the solvent is: MDA content 0.0wt%, H6MDA content 0.0wt%, H 12 MDA content 99.5wt%, 0.5wt% by-products (excluding MDA, H6MDA, H...) 12 (the sum of all substances other than MDA), H 12 In MDA, t, tH 12 The MDA content is 7.2%.

[0068] Example 3

[0069] A fixed bed (reactor A) with an inner diameter of 24 mm and a length of 60 mm was loaded with 30 g of 0.5% Ru-0.01% B / γ-Al2O3 catalyst, with inert ceramic balls at both ends. A fixed bed (reactor B) with an inner diameter of 24 mm and a length of 30 mm was connected in series at the outlet of reactor A, loaded with 5 g of 8% Rh-5% Ba / γ-Al2O3 catalyst, with inert ceramic balls at both ends. The reaction apparatus was purged with nitrogen and hydrogen to remove air, then hydrogen was introduced to 12 MPa at a continuous flow rate of 200 NL / h. Reactors A and B were then heated to 250 °C at a rate of 120 °C / h and maintained for 4 hours to activate the catalyst. After activation, keeping other conditions constant, reactors A and B were cooled to 60℃ and 100℃ respectively and maintained at a constant temperature. Then, the hydrogen flow rate was set to 34 L / h (H2 / MDA molar ratio of 100), and an MDA solution (using a mixed solvent of trimethylamine and tetrahydrofuran, with a mass ratio of trimethylamine to tetrahydrofuran of 1:1, a mass ratio of the mixed solvent to MDA of 10:1, and an MDA feed space velocity of 0.1 g) was introduced into the reactors at a rate of 33 g / h using a high-pressure constant flow pump. MDA .g Ru催化剂 -1 .h -1 The hydrogenation reaction was carried out continuously under stable conditions. After 200 hours, samples were taken from the outlets of reactors A and B, respectively, and quantitative analysis was performed using gas chromatography. The composition of the material at the outlet of reactor A, after deducting the solvent, was: MDA content 8.7 wt%, H6MDA content 90.7 wt%, H... 12 MDA content 0.2wt%, 0.4wt% by-products (excluding MDA, H6MDA, H...) 12 (All substances other than MDA), the t-H6MDA percentage in H6MDA is 14.0 wt%; the composition of the material effluent from reactor B after deducting the solvent is: MDA content 0.0 wt%, H6MDA content 0.8 wt%, H... 12 MDA content 98.6 wt%, 0.6 wt% by-products (excluding MDA, H6MDA, H...) 12 All substances other than MDA), H 12 In MDA, t, tH 12 The MDA content was 8.6%.

[0070] Comparative Example 1

[0071] Unlike Example 1, reactors A and B were both packed with 30g of 5% Ru-0.5% K / α-Al2O3 catalyst. The composition of the effluent from reactor A after deducting the solvent was the same as in Example 1; the composition of the effluent from reactor B after deducting the solvent was: MDA content 0.0wt%, H6MDA content 35.4wt%, H...12 MDA content 64.1 wt%, 0.5 wt% by-products (excluding MDA, H6MDA, H...) 12 All substances other than MDA), H 12 In MDA, t, tH 12 The MDA content was 28.4%.

[0072] Comparative Example 2

[0073] Unlike Example 1, reactors A and B were both packed with 30g of 2% Rh-0.1% La / γ-Al2O3 catalyst. The composition of the effluent from reactor A, after deducting the solvent, was: MDA content 0.0wt%, H6MDA content 6.4wt%, H... 12 MDA content 89.1 wt%, 4.5 wt% by-products (excluding MDA, H6MDA, H...) 12 (All substances other than MDA), the t-H6MDA percentage in H6MDA is 25.0 wt%; the composition of the material at the outlet of reactor B after deducting the solvent is: MDA content 0.0 wt%, H6MDA content 0.0 wt%, H 12 MDA content 94.9 wt%, 5.1 wt% by-products (excluding MDA, H6MDA, H...) 12 All substances other than MDA), H 12 In MDA, t, tH 12 The MDA content was 16.2%.

[0074] Comparative Example 3

[0075] Unlike Example 1, reactor A was charged with 30g of 2% Rh-0.1% La / γ-Al2O3, while reactor B was charged with 30g of 5% Ru-0.5% K / α-Al2O3 catalyst. The composition of the effluent from reactor A, after deducting the solvent, was: MDA content 0.0wt%, H6MDA content 6.4wt%, H... 12 MDA content 89.1 wt%, 4.5 wt% by-products (excluding MDA, H6MDA, H...) 12 The total amount of all substances other than MDA), the t-H6MDA percentage in H6MDA is 25.0 wt%; the composition of the material at the outlet of reactor B after deducting the solvent is: MDA content 0.0 wt%, H6MDA content 0.0 wt%, H 12 MDA content 95.4 wt%, 4.6 wt% by-products (excluding MDA, H6MDA, H...) 12 All substances other than MDA), H 12 In MDA, t, tH 12 The MDA content is 34.5%.

Claims

1. A method for continuous hydrogenation synthesis of H12MDA with low anti-antibody content, comprising passing a solution containing solvent and MDA sequentially through two reactors A and B connected in series; reactor A is loaded with a supported Ru catalyst, the Ru catalyst comprising a support and an active component Ru attached to the support and an auxiliary agent one; reactor B is loaded with a supported Rh catalyst, the Rh catalyst comprising a support and an active component Rh attached to the support and an auxiliary agent two; the supported Ru catalyst support is selected from one or more of alumina, activated carbon, zirconium dioxide, and titanium dioxide; the auxiliary agent one is selected from one or more of K, Ca, and Ba; the supported Rh catalyst support is selected from one or more of alumina, activated carbon, zirconium dioxide, and titanium dioxide; the auxiliary agent two is selected from one or more of Li, Ba, and La.

2. The method according to claim 1, characterized in that, The supported Ru catalyst support is selected from one or more of γ-Al2O3, η-Al2O3, δ-Al2O3, θ-Al2O3, k-Al2O3, and α-Al2O3.

3. The method according to claim 1, characterized in that, The supported Ru catalyst has a specific surface area of ​​0.1~100 m2 / g; a pore volume of 0.001~2 cm3 / g; an average pore size of 1~500 nm; and an average Ru crystallite size of 0.05~50 nm.

4. The method according to claim 1, characterized in that, The supported Ru catalyst has a specific surface area of ​​2~20 m2 / g; the supported Ru catalyst has a pore volume of 0.01~0.2 cm3 / g; the supported Ru catalyst has an average pore size of 30~200 nm; and the supported Ru catalyst has an average Ru crystallite size of 4~10 nm.

5. The method according to claim 1, characterized in that, The supported Ru catalyst has a Ru loading of 0.01~30 wt% based on the total mass of the catalyst; the supported Ru catalyst has an additive loading of 0.001~20 wt% based on the total mass of the catalyst.

6. The method according to claim 1, characterized in that, The supported Ru catalyst has a Ru loading of 0.5~15 wt% based on the total mass of the catalyst; the supported Ru catalyst has an additive loading of 0.05~10 wt% based on the total mass of the catalyst.

7. The method according to claim 1, characterized in that, The supported Rh catalyst support is selected from one or more of γ-Al2O3, η-Al2O3, δ-Al2O3, θ-Al2O3, k-Al2O3, and α-Al2O3.

8. The method according to claim 1, characterized in that, The supported Rh catalyst has a specific surface area of ​​50~500 m2 / g; a pore volume of 0.05~5 cm3 / g; an average pore size of 0.1~100 nm; and an average Rh crystallite size of 0.05~10 nm.

9. The method according to claim 1, characterized in that, The supported Rh catalyst has a specific surface area of ​​80~250 m2 / g; a pore volume of 0.1~1.5 cm3 / g; an average pore size of 1~20 nm; and an average Rh crystallite size of 0.5~5 nm.

10. The method according to claim 1, characterized in that, The supported Rh catalyst has an Rh loading of 0.001~10 wt% based on the total mass of the catalyst; the supported Rh catalyst has an additive loading of 0.001~10 wt% based on the total mass of the catalyst.

11. The method according to claim 1, characterized in that, The supported Rh catalyst has an Rh loading of 0.05~5 wt% based on the total mass of the catalyst; the supported Rh catalyst has an additive loading of 0.01~5 wt% based on the total mass of the catalyst.

12. The method according to claim 1, characterized in that, The reaction temperature of reactor A is 40~200℃; the reaction temperature of reactor B is 80~250℃; the mass ratio of the supported Ru catalyst in reactor A to the supported Rh catalyst in reactor B is 1:100~10:

1.

13. The method according to claim 1, characterized in that, The reaction temperature of reactor A is 60~120℃; the reaction temperature of reactor B is 120~200℃; the mass ratio of the supported Ru catalyst in reactor A to the supported Rh catalyst in reactor B is 1:10~1:1.

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