Method for activating metal-supported catalyst in process of preparing diaminodicyclohexylmethane through hydrogenation

Abstract

The invention relates to an activation method of a metal-supported catalyst in a process of preparing diaminodicyclohexylmethane through hydrogenation, MDA, 4-((4-aminocyclohexyl) methyl) aniline (H6MDA) and a reaction solvent are used as mixed raw materials, the catalyst is subjected to first-batch hydrogenation activation treatment, and the metal activation degree M of the catalyst is controlled to be 0.1-12 in the activation process. By adopting the activation method, the performance of the catalyst can be quickly improved, and the production efficiency is effectively improved while high yield and low trans-body content of H12MDA are maintained.

Description

Technical Field

[0001] The present invention relates to a method for activating a metal-supported catalyst, and more particularly to a method for activating a metal-supported catalyst in the process of preparing diaminodicyclohexylmethane (H12MDA) by hydrogenation of diaminodiphenylmethane (MDA). Background Art

[0002] Diaminodicyclohexylmethane (H12MDA) is mainly used in the fields of isocyanate synthesis and epoxy curing agents. Due to the stability of the aromatic ring and steric hindrance effects, the hydrogenation of diaminodiphenylmethane (MDA) is very difficult. In the prior art, mostly supported noble metal catalysts are used to carry out batch catalytic reactions under high temperature and high pressure in a stirred autoclave reactor or a fixed bed reactor to obtain satisfactory yields and anti-isomer ratios.

[0003] At present, there are many studies on the production process of H12MDA, the preparation method of the supported noble metal catalyst used for H12MDA, and the activation and regeneration process of waste catalysts. However, there is little mention of how to effectively pre-reduce and activate the supported noble metal catalyst before its first use to quickly and efficiently achieve the best reaction performance.

[0004] US20060047173 uses MDA-85 as a raw material, first performs pretreatment under a supported ruthenium fixed bed catalyst, and then cools the temperature to 100-130 °C to carry out aromatic ring hydrogenation reaction under a rhodium / ruthenium mixed supported monolith catalyst. US6075167 provides a ruthenium-catalyzed reduction process of aromatic diamine compounds with metal nitrite as a promoter, which improves the reaction rate and reduces the amount of high-boiling by-product tar. US 3697449 uses an aqueous solution of an alcoholate or hydroxide of 1-35% alkali metal to modify the supported ruthenium catalyst to carry out the hydrogenation reduction of MDA. US 6054619 prepares a support containing Cr, Mo, W, Mn or Re by drying and calcining under alkaline conditions, activates the support with an Rh salt, dries at 80-350 °C and reduces with hydrogen to prepare a supported Rh noble metal catalyst, and reduces aromatic amine compounds at 0.5-40 bar.

[0005] CN201010291971 discloses a method for regenerating Cu, Ru, Co, Ni, Pd and Pt metal catalysts. This method first removes carbon deposits, and after activation treatment, the catalyst is subjected to silanization treatment. However, this method is not easily implemented in actual industry, especially in the field of low-temperature liquid-phase hydrogenation catalysts. CN96198018.4 discloses a method for reactivating ruthenium catalysts. This method includes contacting the catalyst with oxygen in the liquid phase, and then treating it under the conditions that the pressure is lower than the hydrogen partial pressure of the hydrogenation reaction and the temperature is not lower than 50 °C of the hydrogenation reaction. The activity of the treated catalyst is improved. However, since this method uses oxygen, when contacting the liquid phase with organic solvents such as alcohols or hydrocarbons, it is very easy to cause combustion or explosion, and there are certain safety hazards.

[0006] The above similar technologies only mention that after impregnation and calcination of noble metal-supported catalysts, hydrogen is needed to reduce their metals, but rarely mention how to quickly improve the reaction performance of the catalysts during the first use. For the MDA hydrogenation process, newly supported noble metal catalysts often need to be pre-reduced again under pure solvent and high-pressure hydrogen for the first time, and 1-5 batches of catalytic reaction processes are required to make the reaction activity and selectivity of the catalysts reach the best state. Therefore, for industrial plants, this will have a greater impact on the plant production capacity. Summary of the Invention

[0007] Aiming at the above problems existing in the prior art, the purpose of the present invention is to provide an activation method for metal-supported catalysts used in the hydrogenation of diaminodiphenylmethane (MDA), which can quickly improve the catalyst performance, and while maintaining a high yield of diaminodicyclohexylmethane (H12MDA) and a low content of trans,trans-isomer, effectively improve the production efficiency.

[0008] To achieve the above purpose, the technical solution of the present invention is as follows:

[0009] The present invention provides an activation method for metal-supported catalysts in the process of hydrogenating to produce diaminodicyclohexylmethane (H12MDA), including the following steps:

[0010] Using diaminodiphenylmethane (MDA), 4-((4-aminocyclohexyl)methyl)aniline (H6MDA) and a reaction solvent as activation raw materials, mixing them with the metal-supported catalyst, and introducing hydrogen for hydrogenation activation treatment. After the activation is completed, it enters the catalytic hydrogenation reaction stage of diaminodiphenylmethane;

[0011] During the hydrogenation activation treatment process, the metal activation degree M of the catalyst is controlled to be 0.1-12, such as 0.1, 0.5, 1.0, 1.5, 2.0, 4.0, 6.0, 8.0, 10.0, 12.0, preferably 0.55-0.74.

[0012] In the present invention, the calculation formula of the activation degree M of the catalyst metal is shown as the following formula (1):

[0013] M = (M (MDA) *2 + M (H6MDA) *1)*C (Cat) / (M (MDA) + M (H6MDA) )*W (Cat) , (1)

[0014] In the formula: M (MDA) represents the mass of diaminodiphenylmethane in the activated raw material during the hydrogenation activation treatment / g;

[0015] M (H6MDA) represents the mass of 4-((4-aminocyclohexyl)methyl)aniline in the activated raw material during the hydrogenation activation treatment / g;

[0016] C (Cat) represents the catalyst concentration / wt%, based on the mass of diaminodiphenylmethane in the catalytic hydrogenation reaction stage;

[0017] W (Cat) represents the metal loading amount / wt% in the metal-loaded catalyst, based on the total mass of the catalyst.

[0018] In the present invention, the activation method is applicable to the hydrogenation activation treatment of the metal-loaded catalyst during the first batch of hydrogenation for preparing diaminodicyclohexylmethane.

[0019] In the present invention, the reaction solvent is selected from one or more of alcohols, ethers, alkanes or amine compounds, preferably one or more of cyclohexane, dioxane, tetrahydrofuran, cyclohexylamine, dicyclohexylamine, methanol, ethanol, isopropanol, n-butanol, 2-butanol and methylcyclohexane, and more preferably tetrahydrofuran (THF);

[0020] Preferably, during the hydrogenation activation treatment, the concentration of the reaction solvent is ≥30wt% and <100wt%, such as 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, 90wt%, 99wt%, and preferably 60 - 80wt%, based on the total mass of the activated raw material.

[0021] In the present invention, the metal loading amount W in the metal-loaded catalyst (Cat) is 0.5 - 10wt%, such as 0.5wt%, 1wt%, 3wt%, 5wt%, 7wt%, 9wt%, 10wt%, and preferably 4 - 5wt%, based on the total mass of the metal-loaded catalyst;

[0022] Preferably, in the metal-loaded catalyst, the carrier can be a porous commercially available carrier or a natural product, etc., and is selected from one or more of rare earth, diatomite, alumina, activated carbon, lithium aluminate, spinel, silica, and silica-alumina oxide;

[0023] Preferably, in the metal-loaded catalyst, the metal is one or more of Group VIII B metals, preferably one or more of Pt, Rh, Ru, Ir, and Pd, and more preferably Ru.

[0024] In the present invention, in the activation raw material, the dosage of the metal-loaded catalyst is 1-10 wt% of the total mass of diaminodiphenylmethane and 4-((4-aminocyclohexyl)methyl)aniline, such as 1 wt%, 3 wt%, 5 wt%, 7 wt%, 9 wt%, 10 wt%, and preferably 2-7 wt%;

[0025] In the activation raw material, the dosage of diaminodiphenylmethane is M (MDA) and the dosage of 4-((4-aminocyclohexyl)methyl)aniline is M (H6MDA) , which is regulated by the metal activation degree M, that is, it only needs to jointly satisfy the calculation formula (1) of the catalyst metal activation degree M with the catalyst concentration C (Cat) and the metal loading amount W in the metal-loaded catalyst (Cat) ; preferably, the mass ratio of diaminodiphenylmethane to 4-((4-aminocyclohexyl)methyl)aniline is 0.1-5, and preferably 0.5-2.

[0026] Preferably, the concentration C (Cat) of the metal-loaded catalyst is 0.5-5 wt% of the feeding amount of diaminodiphenylmethane in the catalytic hydrogenation reaction stage, such as 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, preferably 1-3 wt%, and more preferably 1.5-2 wt%.

[0027] In the present invention, the diamino diphenyl methane has a mass percentage composition comprising 80 - 100 wt%, such as 80 wt%, 85 wt%, 90 wt%, 95 wt%, 100 wt% of 4,4'-MDA, 0 - 18 wt%, such as 0 wt%, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 18 wt% of 2,4'-MDA, 0 - 1 wt%, such as 0 wt%, 0.3 wt%, 0.6 wt%, 0.9 wt% of N-methyl-4,4'-MDA, and 0 - 1 wt%, such as 0 wt%, 0.3 wt%, 0.6 wt%, 0.9 wt% of impurities, based on the total mass of the diamino diphenyl methane; preferably 84.5 - 99.5 wt% of 4,4'-MDA, 0 - 15 wt% of 2,4'-MDA, 0 - 0.4 wt% of N-methyl-4,4'-MDA, and 0 - 0.1 wt% of impurities, based on the total mass of the diamino diphenyl methane.

[0028] In the present invention, the 4-((4-aminocyclohexyl)methyl)aniline has a mass percentage composition comprising 90 - 100 wt%, such as 90 wt%, 95 wt%, 100 wt% of 4,4'-H6MDA, 0 - 9 wt%, such as 0 wt%, 1 wt%, 5 wt%, 9 wt% of 2,4'-H6MDA, and 0 - 1 wt%, such as 0 wt%, 0.3 wt%, 0.6 wt%, 0.9 wt% of impurities, based on the total mass of the 4-((4-aminocyclohexyl)methyl)aniline; preferably 98 - 100 wt% of 4,4'-H6MDA, 0 - 1.5 wt% of 2,4'-H6MDA, and 0 - 0.5 wt% of impurities, based on the total mass of the 4-((4-aminocyclohexyl)methyl)aniline.

[0029] In the present invention, for the activation method, the reactor used is a batch high-pressure autoclave reactor with a catalyst filtration device, and the catalyst filtration device is preferably an internal filter or an external filter, more preferably an internal filter of the autoclave.

[0030] In the present invention, in the hydrogenation activation treatment process, the activation temperature is 100 - 250 °C, such as 100 °C, 120 °C, 140 °C, 160 °C, 180 °C, 200 °C, 220 °C, 240 °C, 250 °C, preferably 150 - 200 °C, more preferably 170 - 190 °C;

[0031] In the hydrogenation activation treatment process, the activation pressure is 3 - 15 MPaA, such as 3 MPaA, 5 MPaA, 7 MPaA, 9 MPaA, 11 MPaA, 13 MPaA, 15 MPaA, preferably 5 - 10 MPaA, more preferably 6 - 8 MPaA;

[0032] In the hydrogenation activation process, when the hydrogen consumption pressure drop is lower than 0.01 MPa / min, such as 0.01 MPa / min or 0.005 MPa / min, it is the activation end point.

[0033] In the present invention, for the subsequent catalytic hydrogenation reaction, the production process is a method already disclosed in the prior art, and there are no special limitations on the reaction conditions involved in the catalytic hydrogenation reaction stage. Those skilled in the art can screen according to needs through the already disclosed methods in the prior art. For example, the reaction temperature is 100 - 250 °C, such as 100 °C, 120 °C, 140 °C, 160 °C, 180 °C, 200 °C, 220 °C, 240 °C, 250 °C, and the reaction pressure is 3 - 15 MpaA, such as 3 MPaA, 5 MPaA, 7 MPaA, 9 MPaA, 11 MPaA, 13 MPaA, 15 MPaA;

[0034] The dosage of the catalyst, namely the aforementioned metal - loaded catalyst concentration C (Cat) , is 0.5 - 5 wt% of the mass of diaminodiphenylmethane, such as 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, preferably 1 - 3 wt%, and more preferably 1.5 - 2 wt%;

[0035] The concentration of the reaction solvent is 40 - 70 wt%, such as 40 wt%, 50 wt%, 60 wt%, 70 wt%, preferably 50 - 60 wt%, based on the total mass of the catalytic hydrogenation reaction system.

[0036] Using the activation method of the present invention, the conversion rate of MDA after catalytic hydrogenation is 98 - 100%, the secondary amine yield ≤ 5%, and the content of the trans - trans isomer ≤ 17 wt% (based on the weight of H12MDA).

[0037] Compared with the prior art, the positive effects of the present invention are as follows:

[0038] The present invention provides an activation method for an MDA hydrogenation catalyst, which can rapidly improve the catalyst performance. While maintaining a high yield of H12MDA and a low content of the trans - trans isomer, it simplifies the catalyst activation process and greatly improves the production efficiency of the device.

[0039] The inventors of the present application found in experiments that when activating with pure solvents, since there is a lack of raw materials to be reacted in the reaction system, the heat of the hydrogenation reaction cannot be generated, resulting in a relatively low hot spot temperature on the catalyst surface, making it impossible to effectively reduce the noble metals in the catalyst. Therefore, it is necessary to gradually return to the normal level during the subsequent hydrogenation reaction process. When activating only with MDA and organic solvents, since MDA generates a large amount of reaction heat and consumes a large amount of hydrogen during the hydrogenation process, this will lead to a significant decrease in the hydrogen concentration around the catalyst. At the same time, the significant increase in the hot spot temperature on the catalyst surface will cause sintering of some catalyst particles, resulting in a large amount of secondary amines produced by the condensation of MDA being wrapped on the catalyst surface, thereby affecting the reaction performance of the subsequent catalyst. When activating only with H6MDA and organic solvents, since the reaction activity of H6MDA is significantly weaker than that of MDA, a higher reaction temperature is required to complete the reaction, and the high temperature will lead to a significant increase in the content of the anti-anti body. At the same time, H6MDA is more basic than MDA and erodes the catalyst support more, further weakening the inhibitory effect of the catalyst on the anti-anti body. Therefore, it cannot meet the downstream demand for low anti-anti products.

[0040] Compared with the activation methods using pure solvents, high-pressure hydrogen or other reducing agents, the activation method of the present invention does not require additional addition of alkali metal salts, nor does it require additional addition of other reducing agents outside the reaction system, avoiding the potential safety risks caused by impurity accumulation and the increase in three wastes due to difficult product separation.

[0041] The activation method of the present invention uses raw materials MDA and H6MDA and the reaction solvent as activation raw materials, and controls parameters such as the appropriate metal activation degree M of the catalyst during the activation process to generate an appropriate amount of heat of the hydrogenation reaction. These heats raise the local temperature of the catalyst particles to the specified level, thereby realizing a rapid hydrogen reduction activation process. Specific Embodiments

[0042] The following further illustrates the present invention in conjunction with embodiments, but the present invention is not limited to the listed embodiments.

[0043] The sources of the main raw materials in the embodiments and comparative examples of the present invention are as follows. Others are obtained from ordinary commercial channels if not otherwise specified:

[0044] The metal-loaded catalyst was purchased from Johnson Matthey;

[0045] Tetrahydrofuran was purchased from Kermel, analytical grade;

[0046] MDA-100 is from Wanhua WANAMINE MDA-100, in which the content of 4,4'-MDA is 99.5 wt%, the content of N-methyl-4,4'-MDA is 0.35 wt%, and the content of other impurities is 0.15 wt%;

[0047] MDA-85 is from WANAMINE MDA-85, where the content of 2,4'-MDA is 15 wt%, the content of 4,4'-MDA is 84.5 wt%, the content of N-methyl-4,4'-MDA is 0.35 wt%, and the content of other impurities is 0.15 wt%.

[0048] H6MDA is an intermediate in the hydrogenation reaction of MDA, obtained by rectifying the mother liquor of the MDA hydrogenation reaction unit of Wanhua Chemical (tower pressure 1.5 KPa, the temperature of the extracted fraction is 200 - 210 °C). Among them, the content of 4,4'-H6MDA is 99.3 wt%, the content of 2,4'-H6MDA is 0.4 wt%, and the content of other impurities is 0.3 wt%.

[0049] The gas chromatograph is of the 7890 series from Agilent Technologies, with a DB-5 capillary chromatographic column. The temperature of the FID detector is 300 °C, the initial column temperature is 160 °C, which is raised to 300 °C at a rate of 10 °C / min and held for 20 min.

[0050] The metal activation degree M of the catalyst: It is calculated by the above formula (1).

[0051] Example 1

[0052] The process of hydrogenation activation treatment of the metal-loaded catalyst (activation of the first batch of catalysts): In a 1-L high-pressure autoclave with an internal filter, 4 g of catalyst (4 wt% Ru / Al 2 O 3 ) is added, and at the same time, 24 g of MDA-100, 36 g of H6MDA, and 240 g of THF are added (at this time, the metal activation degree M of the catalyst is 0.7, where M (MDA) = 24 g, M (H6MDA) = 36 g, C (Cat) = 2 wt%, W (Cat) = 4 wt%).

[0053] After purging with N 2 three times, then purging with H 2 at 1 MPaA three times, and then H 2 is repressurized to 4.5 - 5.0 MPaA. The temperature is raised to 190 °C, and during the activation process, H 2 is continuously introduced into the reaction kettle through a hydrogen flow controller to ensure that the activation pressure is maintained at 8.0 MPaA. When the pressure drop of hydrogen consumption in the reaction kettle is less than 0.01 MPa / min, the activation is stopped. The reaction kettle is cooled and depressurized. When the temperature of the reaction kettle drops to 50 °C, N 2 not exceeding 0.6 MPaA is used to filter and separate the product liquid from the catalyst through the internal filter, and the product liquid is analyzed by gas chromatography.

[0054] Catalyst hydrogenation reaction stage (multiple applications of the catalyst): After the product liquid is filtered clean, add 200 g of MDA-100 and 200 g of THF each time, control the reaction temperature at 170 °C, control the reaction pressure at 6 MPaA, and stop the reaction when the pressure drop of hydrogen consumption in the reaction kettle is less than 0.01 MPa / min. Repeat the above steps to recycle the catalyst.

[0055] The results obtained are shown in Table 1.

[0056] Table 1 Reaction results of catalyst application in Example 1

[0057]

[0058]

[0059] Example 2

[0060] Hydrogenation activation process of metal-loaded catalyst (activation of the first batch of catalyst): In a 1-L high-pressure autoclave with an internal filter, add 3 g of catalyst (4 wt% Ru / Al 2 O 3 ), and at the same time add 72 g of MDA-85, 48 g of H6MDA, and 180 g of THF (at this time, the metal activation degree M of the catalyst is 0.6, where M (MDA) = 72 g, M (H6MDA) = 48 g, C (Cat) = 1.5 wt%, W (Cat) = 4 wt%).

[0061] After purging with N 2 three times, then purge with H 2 at 1 MPaA three times, and then immediately repressurize H 2 to 3.5 - 4.0 MPaA. Raise the temperature to 170 °C, and continuously introduce H 2 into the reaction kettle through the hydrogen flow controller during the activation process to ensure that the activation pressure is maintained at 6.0 MPaA. Stop the activation when the pressure drop of hydrogen consumption in the reaction kettle is less than 0.01 MPa / min. Cool down and relieve the pressure of the reaction kettle. When the temperature of the reaction kettle drops to 50 °C, use N 2 not exceeding 0.6 MPaA to filter and separate the product liquid and the catalyst through the internal filter, and perform gas chromatography analysis on the product liquid.

[0062] Catalyst hydrogenation reaction stage (multiple applications of the catalyst): After the product liquid is filtered clean, add 200 g of MDA-100 and 200 g of THF each time, control the reaction temperature at 190 °C, control the reaction pressure at 8 MPaA, and stop the reaction when the pressure drop of hydrogen consumption in the reaction kettle is less than 0.01 MPa / min. Repeat the above steps to recycle the catalyst.

[0063] The obtained results are shown in Table 2.

[0064] Table 2 Reaction results of catalyst reuse in Example 2

[0065]

[0066] Example 3

[0067] Hydrogenation activation process of metal-loaded catalyst (activation of the first batch of catalyst): In a 1 L high-pressure autoclave with an internal filter, add 6 g of catalyst (1 wt% Rh / Al 2 O 3 ), and at the same time add 24 g of MDA-100, 36 g of H6MDA, and 240 g of THF (at this time, the metal activation degree M of the catalyst is 4.2, where M (MDA) = 24 g, M (H6MDA) = 36 g, C (Cat) = 3 wt%, W (Cat) = 1 wt%).

[0068] After purging with N 2 three times, then purge with H 2 at 1 MPaA three times, and then immediately replenish the pressure of H 2 to 4.5 - 5.0 MPaA. Raise the temperature to 200 °C, and continuously introduce H 2 into the reaction autoclave through a hydrogen flow controller during the activation process to ensure that the activation pressure is maintained at 10.0 MPaA. Stop the activation when the pressure drop of hydrogen consumption in the reaction autoclave is less than 0.01 MPa / min. Cool down and relieve the pressure of the reaction autoclave. When the temperature of the reaction autoclave drops to 50 °C, use N 2 not exceeding 0.6 MPaA to filter and separate the product liquid from the catalyst through the internal filter, and perform gas chromatography analysis on the product liquid.

[0069] Catalyst hydrogenation reaction stage (multiple reuse of the catalyst): After the product liquid is filtered clean, each time add 200 g of MDA-100 and 200 g of THF, control the reaction temperature at 150 °C, control the reaction pressure at 10 MPaA, and stop the reaction when the pressure drop of hydrogen consumption in the reaction autoclave is less than 0.01 MPa / min. Repeat the above steps to recycle the catalyst.

[0070] The obtained results are shown in Table 3.

[0071] Table 3 Reaction results of catalyst reuse in Example 3

[0072]

[0073] Example 4

[0074] Hydrogenation activation process of metal-loaded catalyst (activation of the first batch of catalyst): In a 1L autoclave with an internal filter, add 10g of catalyst (1wt% Rh / SiO 2 ), and at the same time add 72g of MDA-85, 48g of H6MDA, and 180g of THF (at this time, the metal activation degree M of the catalyst is 8, where M (MDA) = 72g, M (H6MDA) = 48g, C (Cat) = 5wt%, W (Cat) = 1wt%).

[0075] After purging with N 2 three times, then purge with H 2 at 1MPaA three times, and then immediately replenish the pressure of H 2 to 2.5 - 3.0MPaA. Raise the temperature to 150°C, and continuously introduce H 2 into the reaction kettle through the hydrogen flow controller during the activation process to ensure that the activation pressure is maintained at 5.0MPaA. Stop the activation when the pressure drop of hydrogen consumption in the reaction kettle is less than 0.01MPa / min. Cool down and relieve the pressure of the reaction kettle. When the temperature of the reaction kettle drops to 50°C, use N 2 not exceeding 0.6MPaA to filter and separate the product liquid from the catalyst through the internal filter, and perform gas chromatography analysis on the product liquid.

[0076] Hydrogenation reaction stage of the catalyst (multiple applications of the catalyst): When the product liquid is filtered clean, add 200g of MDA-100 and 200g of THF each time, control the reaction temperature at 200°C, control the reaction pressure at 5MPaA, and stop the reaction when the pressure drop of hydrogen consumption in the reaction kettle is less than 0.01MPa / min. Repeat the above steps to recycle the catalyst.

[0077] The results obtained are shown in Table 4.

[0078] Table 4 Reaction results of catalyst recycling in Example 4

[0079]

[0080] Comparative Example 1

[0081] Catalyst activation reaction: Only use 300g of THF as the activation raw material to activate the catalyst (at this time, the metal activation degree of the catalyst is 0, where M (MDA) = 0g, M (H6MDA) = 0g, C (Cat) = 2wt%, W (Cat) = 4wt%), and the remaining activation steps are the same as in Example 1.

[0082] Catalyst hydrogenation reuse: same as Example 1.

[0083] The results obtained are shown in Table 5.

[0084] Table 5 Reaction results of catalyst reuse in Comparative Example 1

[0085]

[0086]

[0087] As can be seen from the above table, when only THF is used to activate the catalyst, the initial reaction activity of the catalyst is relatively low, and it still takes 5 batches for the catalyst performance to gradually recover to the normal level.

[0088] Comparative Example 2

[0089] Catalyst activation reaction: Only 120 g of MDA-85 and 180 g of THF are used as activation raw materials to activate the catalyst (at this time, the metal activation degree of the catalyst is 0.75, where M (MDA) = 120 g, M (H6MDA) = 0 g, C (Cat) = 1.5 wt%, W (Cat) = 4 wt%), and the remaining activation steps are the same as in Example 2.

[0090] Catalyst hydrogenation reuse: same as Example 2.

[0091] The results obtained are shown in Table 6.

[0092] Table 6 Reaction results of catalyst reuse in Comparative Example 2

[0093]

[0094] As can be seen from the above table, when only MDA and THF are used to activate the catalyst, although the reaction activity of the catalyst is relatively high, the secondary amine content is as high as over 9.0%.

[0095] Comparative Example 3

[0096] Catalyst activation reaction: Only 60 g of H6MDA and 240 g of THF are used as activation raw materials to activate the catalyst (at this time, the metal activation degree of the catalyst is 0.5, where M (MDA) = 0 g, M (H6MDA) = 60 g, C (Cat) = 2 wt%, W (Cat) = 4 wt%), and the remaining activation steps are the same as in Example 1.

[0097] Catalyst hydrogenation reuse: same as Example 1.

[0098] The results obtained are shown in Table 7.

[0099] Table 7 Catalyst recycling reaction results of Comparative Example 3

[0100]

[0101] As can be seen from the above table, when only H6MDA and THF are used to activate the catalyst, the catalyst still requires 1 - 2 reaction batches to recover to normal reaction activity, and the content of the trans - trans isomer is as high as over 17%.

[0102] Comparative Example 4

[0103] Catalyst activation reaction: Using 24 g of MDA - 100, 36 g of HMDA (diaminodicyclohexylmethane), and 240 g of THF as the activation raw materials to activate the catalyst (at this time, the metal activation degree of the catalyst is 1, where M (MDA) = 24 g, M (H6MDA) = 0 g, C (Cat) = 2 wt%, W (Cat) = 4 wt%), and the remaining activation steps are the same as in Example 1.

[0104] Catalyst hydrogenation recycling: The same as in Example 1.

[0105] The obtained results are shown in Table 8.

[0106] Table 8 Catalyst recycling reaction results of Comparative Example 4

[0107]

[0108] As can be seen from the above table, when using MDA, HMDA, and THF to activate the catalyst, although the reaction activity of the catalyst is high, HMDA is prone to deamination condensation to form secondary amines during the activation process, and the secondary amines wrap around the catalyst surface, resulting in a significant decrease in the selectivity of the catalyst, increasing the trans - trans content to over 20%, and the secondary amine content is as high as 11 - 13%.

[0109] Comparative Example 5

[0110] Hydrogenation activation process of metal - supported catalyst (activation of the first - batch catalyst): In a 1 - L high - pressure autoclave with an internal filter, add 7 g of catalyst (0.5 wt% Ru / Al 2 O 3 ), and at the same time add 80 g of MDA - 100, 20 g of H6MDA, and 200 g of THF (at this time, the metal activation degree M of the catalyst is 12.6, where M (MDA) = 80 g, M (H6MDA) = 20 g, C (Cat) = 3.5 wt%, W (Cat) = 0.5 wt%).

[0111] Replace with N 2 After replacing three times, then use H at 1 MPaA 2 Replace three times, then immediately H 2 Make up the pressure to 3.5 - 4.0 MPaA. Raise the temperature to 170 °C. During the activation process, continuously introduce H into the reaction kettle through the hydrogen flow controller 2 , ensure that the activation pressure is maintained at 6.0 MPaA. Stop the activation when the pressure drop of the reaction kettle is less than 0.01 MPa / min. Cool down and relieve the pressure of the reaction kettle. When the temperature of the reaction kettle drops to 50 °C, use N not exceeding 0.6 MPaA 2 Filter and separate the product liquid and the catalyst through the built-in filter, and conduct gas chromatography analysis on the product liquid.

[0112] Catalyst hydrogenation reaction stage (multiple applications of the catalyst): When the product liquid is filtered clean, add 200 g of MDA-100 and 200 g of THF each time, control the reaction temperature at 190 °C, control the reaction pressure at 8 MPaA, and stop the reaction when the pressure drop of the reaction kettle is less than 0.01 MPa / min. Repeat the above steps to recycle the catalyst.

[0113] The results obtained are shown in Table 9.

[0114] Table 9 Reaction results of catalyst application in Comparative Example 5

[0115]

[0116] As can be seen from the above table, when using the raw material with a metal activation degree M of 12.6 for catalyst activation, the reaction cannot be effectively accelerated, the catalyst activity is low, the reaction time is as high as more than 400 min, and at the same time, a large amount of secondary amines are formed at high temperature.

Claims

1. A method for activating a metal-loaded catalyst in the process of preparing diaminodicyclohexylmethane by hydrogenation, characterized in that, it comprises the following steps: Using diaminodiphenylmethane, 4-((4-aminocyclohexyl)methyl)aniline and a reaction solvent as activation raw materials, mixing them with the metal-loaded catalyst, and introducing hydrogen for hydrogenation activation treatment. After the activation is completed, it enters the catalytic hydrogenation reaction stage of diaminodiphenylmethane; During the hydrogenation activation treatment process, the catalyst metal activation degree M is controlled to be 0.1 - 12, preferably 0.55 - 0.

74.

2. The activation method according to claim 1, characterized in that, the calculation formula of the catalyst metal activation degree M is as shown in the following formula (1): M = (M (MDA) * 2 + M (H6MDA) * 1) * C (Cat) / (M (MDA) + M (H6MDA) ) * W (Cat) , (1) Where: M (MDA) represents the mass of diaminodiphenylmethane in the activated raw material during the hydrogenation activation treatment / g; M (H6MDA) represents the mass / g of 4 - ((4 - aminocyclohexyl)methyl)aniline in the activated raw material during the hydrogenation activation treatment; C (Cat) represents the catalyst concentration / wt%, based on the mass of diaminodiphenylmethane in the catalytic hydrogenation reaction stage; W (Cat) represents the metal loading in the metal-loaded catalyst / wt%, calculated based on the total mass of the catalyst.

3. The activation method according to claim 1, characterized in that, the reaction solvent is selected from one or more of alcohols, ethers, alkanes or amine compounds, preferably one or more of cyclohexane, dioxane, tetrahydrofuran, cyclohexylamine, dicyclohexylamine, methanol, ethanol, isopropanol, n-butanol, 2-butanol and methylcyclohexane, more preferably tetrahydrofuran; and / or the concentration of the reaction solvent is ≥ 30wt% and < 100wt%, preferably 60 - 80wt%, based on the total mass of the activation raw materials.

4. The activation method according to claim 1, characterized in that, The metal loading W in the metal-loaded catalyst (Cat) is 0.5-10 wt%, preferably 4-5 wt%, based on the total mass of the metal-loaded catalyst; and / or in the metal-loaded catalyst, the carrier is selected from one or more of rare earth, diatomite, alumina, activated carbon, lithium aluminate, spinel, silica and silica-aluminum oxide; and / or in the metal-loaded catalyst, the metal is one or more of Group VIIIB metals, preferably one or more of Pt, Rh, Ru, Ir and Pd, more preferably Ru.

5. The activation method according to claim 1, characterized in that, in the activation raw materials, the dosage of the metal-loaded catalyst is 1 - 10wt% of the total mass of diaminodiphenylmethane and 4-((4-aminocyclohexyl)methyl)aniline, preferably 2 - 7wt%; Preferably, the mass ratio of diaminodiphenylmethane to 4-((4-aminocyclohexyl)methyl)aniline is 0.1 - 5, preferably 0.5 - 2.

6. The activation method according to claim 1, characterized in that, The concentration C of the metal-loaded catalyst (Cat) is 0.5 - 5 wt% of the feed amount of diaminodiphenylmethane in the catalytic hydrogenation reaction stage, preferably 1 - 3 wt%, and more preferably 1.5 - 2 wt%.

7. The activation method according to claim 1, characterized in that, for the diaminodiphenylmethane, its mass percentage composition contains 80 - 100wt% of 4,4’-MDA, 0 - 18wt% of 2,4’-MDA, 0 - 1wt% of N-methyl-4,4’-MDA and 0 - 1wt% of impurities, based on the total mass of diaminodiphenylmethane; preferably 84.5 - 99.5wt% of 4,4’-MDA, 0 - 15wt% of 2,4’-MDA, 0 - 0.4wt% of N-methyl-4,4’-MDA and 0 - 0.1wt% of impurities, based on the total mass of diaminodiphenylmethane; and / or The 4-((4-aminocyclohexyl)methyl)aniline has a mass percentage composition comprising 90-100 wt% of 4,4'-H6MDA, 0-9 wt% of 2,4'-H6MDA, and 0-1 wt% of impurities, based on the total mass of 4-((4-aminocyclohexyl)methyl)aniline; preferably 98-100 wt% of 4,4'-H6MDA, 0-1.5 wt% of 2,4'-H6MDA, and 0-0.5 wt% of impurities, based on the total mass of 4-((4-aminocyclohexyl)methyl)aniline.

8. The activation method according to claim 1, characterized in that the reactor used is a batch autoclave reactor with a catalyst filtration device, and the catalyst filtration device is preferably an internal filter or an external filter, more preferably an internal filter in the autoclave.

9. The activation method according to claim 1, characterized in that in the hydrogenation activation treatment process, the activation temperature is 100-250 °C, preferably 150-200 °C, more preferably 170-190 °C; and / or in the hydrogenation activation treatment process, the activation pressure is 3-15 MPaA, preferably 5-10 MPaA, more preferably 6-8 MPaA; and / or in the hydrogenation activation treatment process, when the hydrogen consumption pressure drop is lower than 0.01 MPa / min, it is the activation end point.

10. The activation method according to claim 1, characterized in that in the catalytic hydrogenation reaction, the reaction temperature is 100-250 °C and the reaction pressure is 3-15 MpaA; and / or the concentration of the reaction solvent is 40-70 wt%, preferably 50-60 wt%, based on the total mass of the catalytic hydrogenation reaction system.

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